Search

Recently, recommender systems have been used in various fields. However, they are still plagued by many issues, including cold-start and sparsity problems. The cold-start problem occurs when users are unable to make recommendations to other users owing to a complete lack of information about certain items. This problem can exist both at the user side and the item side. User-side cold-start problems occur when new users access the systems; item-side cold-start problems occur when new items are added to databases. In this study, we addressed the item-side cold-start problem using the concept of weak supervision. First, a new process for identifying feature based representative reviewers in a rater group was designed. Then, we developed a method to predict the expected preferences for new items by combining content-based filtering and the preferences of representative users. Through extensive experiments, we first confirmed that in comparison to existing methods, the proposed approach provided enhanced accuracy, which was evaluated by determining a mean absolute error for the average ratings. Then, we compared the proposed scheme with the collaborative filtering (CF) and neural CF approaches (NCF). The estimation by the proposed approach was 21% and 38% more accurate than CF and NCF in terms of mean absolute error (MAE), respectively. In future, the proposed framework can be applied in various recommender systems as a core function.

Unicompartmental knee arthroplasty (UKA) is a successful treatment modality in selected patients having advanced, single-compartment osteoarthritis of the knee. The bone and ligament preservation leading to shorter recovery periods, better functional outcomes, lower perioperative complication rates, and easier revision, if needed, are proposed as some of the advantages of UKA over total knee arthroplasty (TKA). Despite several advantages, UKA is reported to have higher failure rates as compared to TKA. The prosthesis failure of UKA is directly correlated to intraoperative technique-related factors like malpositioning of components and the inability to replicate the target-limb alignment as per preoperative planning. An evidence-based surgical technique for UKA may help surgeons to avoid the intraoperative technique-related errors. The purpose of this paper is to describe a stepwise surgical technique for the fixed-bearing medial UKA.

Renewable energy generation capacity in Korea is expected to reach about 63.8 GW by 2030 based on calculations using values from a power plan survey (Korea's renewable energy power generation project plan implemented in September 2017) and the &ldquo, 3020&rdquo, implementation plan prescribed in the 8th Basic Plan for Long-Term Electricity Supply and Demand that was announced in 2017. In order for the electrical grid to accommodate this capacity, an appropriate power system reinforcement plan is critical. In this paper, a variety of scenarios are constructed involving renewable energy capacity, interconnection measures and reinforcement measures. Based on these scenarios, the impacts of large-scale renewable energy connections on the future power systems are analyzed and a reinforcement plan is proposed based on the system assessment results. First, the scenarios are categorized according to their renewable energy interconnection capacity and electricity supply and demand, from which a database is established. A dynamic model based on inverter-based resources is applied to the scenarios here. The transmission lines, high-voltage direct current and flexible alternating current transmission systems are reinforced to increase the stability and capabilities of the power systems considered here. Reinforcement measures are derived for each stage of renewable penetration based on static and dynamic analysis processes. As a result, when large-scale renewable energy has penetrated some areas in the future in Korean power systems, the most stable systems could be optimally configured by applying interconnection measure two and reinforcement measure two as described here. To verify the performance of the proposed methodology, in this paper, comprehensive tests are performed based on predicted large-scale power systems in 2026 and 2031. Database creation and simulation are performed semi-automatically here using Power System Simulator for Engineering (PSS/E) and Python.

A distributed system guarantees the acceptance of Byzantine fault tolerance (BFT) for information transmission. Practical BFT (pBFT) and asynchronous BFT (aBFT) are among the various available forms of BFT. Distributed systems generally share information with all participating nodes. After information is shared, the systems reshare it. Thus, ensuring BFT consumes a considerable amount of time. Herein, we propose Decision search protocols that apply the gossip protocol, denoted by DecisionBFT, for distributed networks with guaranteed BFT. Each protocol in DecisionBFT is completely asynchronous and leaderless, it has an eventual consensus but no round-robin or proof-of-work. The core concept of the proposed technology is the consensus structure, which is based on the directed acyclic graph (DAG) and gossip protocol. In the most general form, each node in the algorithm has a set of k neighbors of most preference. When receiving transactions, a node creates and connects an event block with all its neighbors. Each event block is signed by the hashes of the creating node and its k peers. The consensus structure of the event blocks utilizes a DAG, which guarantees aBFT. The proposed framework uses Lamport timestamps and concurrent common knowledge. Further, an example of a Decision search algorithm, based on the gossip protocol DecisionBFT, is presented. The proposed DecisionBFT protocol can reach a consensus when 2/3 of all participants agree to an event block without any additional communication overhead. The DecisionBFT protocol relies on a cost function to identify the k peers and generate the DAG-based consensus structure. By creating a dynamic flag table that stores connection information between blocks, the gossip protocol achieves a consensus in fewer steps than that in the case of the existing aBFT protocol.

Social Internet of things is one of the most up-to-date research issues in the applications of Internet of things technologies. In social Internet of things, accuracy and reliability are standard features to discerning decisions. We assume that decision support systems based on social Internet of things could leverage research from recommender systems to achieve more stable performance. Therefore, we propose a trust-aware recommender systems suitable for social Internet of things. Trust-aware recommender systems adapt the concept of social networking service and utilize social interaction information. Trust information not only improves recommender systems from opinion spam problems but also more accurately predicts users’ preferences. We confirm that the performance of a recommender system becomes more improved when implicit trust is able to satisfy the properties of trust in the social Internet of things environment. The structure and amount of social link information are context-sensitive, so applying the concept of trust into social Internet of things environments requires a method to optimize implicit and explicit trust with minimal social link information. Our proposed method configures an asymmetric implicit trust network utilizing user–item rating matrix and transforms trust propagation metrics for a directional and weighted trust network. Through experiments, we confirm that the proposed methods enable higher accuracy and wider coverage compared to the existing recommendation methods.

Greenhouse gas (GHG) emission factors previously reported from various waste incineration plants have shown significant variations according to country-specific, plant-specific, and operational conditions. The purpose of this study is to estimate GHG emissions and emission factors at nine incineration facilities in Korea by measuring the GHG concentrations in the flue gas samples. The selected incineration plants had different operation systems (i.e., stoker, fluidized bed, moving grate, rotary kiln, and kiln & stoker), and different nitrogen oxide (NOx) removal systems (i.e., selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR)) to treat municipal solid waste (MSW), commercial solid waste (CSW), and specified waste (SW). The total mean emission factors for A and B facilities for MSW incineration were found to be 134 ± 17 kg CO2 ton-1, 88 ± 36 g CH4 ton-1, and 69 ± 16 g N2O ton-1, while those for CSW incineration were 22.56 g CH4 ton-1 and 259.76 g N2O ton-1, and for SW incineration emission factors were 2959 kg CO2 ton-1, 43.44 g CH4 ton-1 and 401.21 g N2O ton-1, respectively. Total emissions calculated using annual incineration for MSW were 3587 ton CO2-eq yr-1 for A facility and 11,082 ton CO2-eq yr-1 for B facility, while those of IPCC default values were 13,167 ton CO2-eq yr-1 for A facility and 32,916 ton CO2-eq yr-1, indicating that the emissions of IPCC default values were estimated higher than those of the plant-specific emission factors. The emission of CSW for C facility was 1403 ton CO2-eq yr-1, while those of SW for D to I facilities was 28,830 ton CO2-eq yr-1. The sensitivity analysis using a Monte Carlo simulation for GHG emission factors in MSW showed that the GHG concentrations have a greater impact than the incineration amount and flow rate of flue gas. For MSW incineration plants using the same stoker type in operation, the estimated emissions and emission factors of CH4 showed the opposite trend with those of NO2 when the NOx removal system was used, whereas there was no difference in CO2 emissions.

This work proposes a new adaptive sliding mode controller to enhance ride comfort and steering stability of automobile associated with a semi-active magneto-rheological damper. In this study, a Macpherson strut type suspension system which is widely used in light vehicles is considered. The dynamic model of the Macpherson strut with magneto-rheological damper is obtained and the governing equations are then formulated using kinematic properties of the suspension system following Lagrange’s formulation. In the formulation of the model, both the rotation of the wheel assembly and the lateral stiffness of the tire are considered to represent the nonlinear characteristic of Macpherson type suspension system. Subsequently, in order to effectively reduce unwanted vibrations, a new adaptive sliding mode controller is designed by adopting moving sliding surface instead of conventional fixed sliding surface. In order to demonstrate the effectiveness of the proposed controller, a cylindrical magneto-rheological damper is designed and manufactured on the basis of practical application conditions such as required damping force. Then, ride comfort, suspension travel, and road handling are evaluated and some benefits of the proposed controller such as enhanced ride comfort are evaluated.

Background: The goal of this study was to evaluate whether a modified fluoroscopic technique for positioning a hook plate affected the clinical results of treating Neer type II distal clavicle fractures and Rockwood type V acromioclavicular (AC) joint separations with this device. Methods: The study was a retrospective consecutive case series with data analysis. Sixty-four patients with a Neer type II distal clavicle fracture or a Rockwood type V AC joint injury treated between March 2009 and June 2013 were divided into 2 groups: traditional fluoroscopic technique (traditional view, 31 patients) or modified fluoroscopic technique (‘hook’ view, 33 patients). A visual analogue scale (VAS) score, the modified University of California-Los Angeles (UCLA) shoulder scale score, and radiographic osteolysis were the main outcome measures. Results: The traditional group included a significantly larger number of patients with acromial osteolysis than the hook view group: 23 patients (74.2%) vs. 11 patients (33.3%), respectively (p=0.01). Before plate removal, the hook group reported less pain and higher UCLA shoulder scale scores than the traditional group: average VAS score, 1.55 vs. 2.26, respectively; average UCLA score, 30.88 vs. 27.06, respectively. However, there was no significant difference after plate removal. Conclusions: The hook view allows more accurate bending of the hook plate around the contour of the acromion, resulting in decreased osteolysis, decreased pain, and better function with the plate in situ.

This paper presents a new hybrid controller which is a combination of three control schemes: fuzzy neural control, PI control and sliding mode control. The interval type 2 fuzzy model featuring updated rules via online is used in this study and in order to support the fuzzy model, a granular clustering method is applied to find groups of data related to the initial fuzzy rule. Then the output for fuzzy model is used for the PI-sliding mode controller. The combination of PI and sliding mode controls is carried out by H-infinity technique method which is rely on the modified Riccati-like equation. After developing the mathematical model, the proposed controller is applied to vibration control of a vehicle seat suspension featuring magneto-rheological (MR) damper. In order to demonstrate the effectiveness of the proposed controller, two different excitations of bump and random signals are adopted and corresponding vibration control performances are evaluated. It is demonstrated through both simulation and experiment that the proposed controller can provide much better than vibration control performance compared with the conventional controllers showing more robust stability.

This article presents the control performances of a vehicle seat suspension system equipped with magneto-rheological dampers using a new adaptive fuzzy sliding mode controller. A magneto-rheological damper is designed by applying the Bingham model incorporating with the field-dependent rheological properties of magneto-rheological fluid. On the other hand, a seat suspension model is established by integrating with a 4-degree-of-freedom human body model. Then, the governing equations are then derived considering the vertical motion of the seat. Subsequently, an adaptive fuzzy controller is formulated by considering the acceleration of the seat. This controller is combined with the sliding mode controller to ensure the robustness against model uncertainty and external disturbances. The controller is then evaluated through experiment. It is demonstrated that the proposed seat suspension system realized by the proposed adaptive fuzzy sliding mode controller can provide very effective ride comfort performances by reducing vertical acceleration under regular bump, random signal, and sinusoidal excitations.

Our many various relationships with persons from home, work and school give rise to our social networks. In a social network, people receive, provide, and pass a great deal of information. In this process, we often observe that certain individuals have especially strong influences on others. We call these highly influential people opinion leaders. Since the late 20th century, the number of Internet users has increased rapidly, and a huge number of people now interact with each other in online social networks. In this way, the Web community has become similar to real-world society. Internet users receive information not only from the mass media, but also from opinion leaders. For example, online articles posted by influential bloggers are often used as marketing tools or political advertisements, due to their huge influence on other users. Therefore, it is important and useful to identify the influential users in an online society. We thus propose a simple yet reliable algorithm that identifies opinion leaders in a cyber social network. In this paper, we first describe our algorithm for identifying influential users in an online society. We then demonstrate the validity of the selection of representative reviewers using the Yahoo! music and GroupLens movie databases and performing 10-fold cross-validation and z-tests.

Since the late 20th century, the number of Internet users has increased dramatically, as has the number of Web searches performed on a daily basis and the amount of information available. A huge amount of new information is transferred to the Web on a daily basis. However, not all data are reliable and valuable, which implies that it may become more and more difficult to obtain satisfactory results from Web searches. We often iterate searches several times to find what we are looking for. To solve this problem, researchers have suggested the use of recommendation systems. Instead of searching for the same information several times, a recommendation system proposes relevant information. In the Web 2.0 era, recommendation systems often rely on collaborative filtering by users. In general, a collaborative filtering approach based on user information such as gender, location, or preference is effective. However, the traditional approach can fail due to the cold-start problem or the sparsity problem, because initial user information is required for this approach to be effective. Recently, several attempts have been made to tackle these collaborative filtering problems. One such attempt used category correlations of contents. For instance, a movie has genre information provided by movie experts and directors. This category information is more reliable than user ratings. Moreover, newly created content always has category information, allowing avoidance of the cold-start problem. In this study, we consider a movie recommendation system and improve the previous algorithms based on genre correlations to correct its shortcomings. We also test the modified algorithm and analyze the results with respect to two characteristics of genre correlations.

This paper proposes an active mount of naval ships in order to reduce unwanted vibrations. The active mount consists of rubber element and piezostack actuator. To avoid being broken piezostack actuator, the inertial actuator which the piezostack actuator is connected to the inertial mass and rubber element is devised. After describing the configuration of the mount, the active mount system supported by four mounts is then constructed. To attenuate the transmitted vibrations, the feedforward control is designed and experimentally implemented to the system. Vibration control performances such as vertical accelerations are evaluated at each mount and presented in frequency domain.

In this work, an active hybrid mount using piezostack actuator and rubber element is manufactured, and its vibration control performance is evaluated via feedforward control. A hybrid active mount featuring inertia type of piezostack actuator is proposed and manufactured. After describing the configuration of the hybrid mount, a mount system is then constructed. To attenuate vibrations from vibration sources, a feedfoward controller is experimentally implemented to the system. Vibration control performances are evaluated at each mount. Effective control performances such as accelerations are obtained and presented in frequency domains.

A hybrid mount for shipboard machinery installed on naval ships was developed. The mount is combined with a rubber mount and a piezostack actuator. The rubber mount is one of the most popular and effective passive mounts to have been applied to various vibration systems to date. The piezostack actuator is featured by a fast response time, small displacement and low power consumption. Through a series of experimental tests conducted in accordance with MIL-M-17185A(SHIPS), MIL-M-17508F(SH), and MIL-S-901D which are US military specifications related to the performance requirements of the mount, it has been confirmed that the hybrid mount shows more effective performance for use in naval ships. * 1. 서 론 기술의 진보와 함께 항공기, 선박, 자동차 등 수송기계시스템에 탑재되는 장비의 성능사양 뿐만 아니라 소음, 진동 및 충격 등 특수성능 사양도 강화되고 있다. 특히 잠수함과 같은 해군 함정의 경우 생존성 분야 연구의 증가와 함께 고정도 스텔스 성능확보 및 탐지에 대한 사양이 강화되고 있다. 함정에 탑재되고 있는 각종 기계/전자 장비들을 살펴보면, 장비 하부에 다양한 형태의 마운트가 설치되어 있는 것을 알 수 있다. 이러한 마운트 설치의 목적†교신저자; 정회원, 한국기계연구원E-mail : sjmoon@kimm.re.krTel : (042)868-7428, Fax : (042)868-7418* 한국기계연구원** 정회원, 인하대학교*** 국방과학연구소**** 국방과학연구소 민군겸용센터은 첫째 탑재장비에서 발생하는 진동 및 소음이 하부 구조물로 전달되는 것을 차단함으로서 함내 거주성을 향상시키고, 적으로부터 탐지되는 확률을 저감시키는 데 있다. 둘째는 적으로부터의 공격 등 외부 충격으로부터 장비를 보호함으로서 함정의 작전능력을 항시 유지하는 데 있다.현재 사용되고 있는 함정 탑재장비용 마운트는 대부분 수동형 마운트로서 고무 또는 와이어의 탄성특성을 이용하는 탄성 마운트이다. 이러한 탄성 마운트는 작은 감쇠특성을 보유하고 있으며, 고주파수의 비공진 주파수 대역에서는 우수한 진동절연 성능을 보이고 있다. 그러나 탑재장비가 자체 기진력이 있는 경우에는 탑재장비의 기진력으로 인하여 특정 주파수에서 진동이 현저하게 나타날 수 있으며, 수동형 마운트로서는 만족스러운 결과를 얻기 어렵다. 이러한 경우에는 능동형 마운트를 고려할 수 있으나, 함정과 같이 입력되는 진동이 큰 경우에는 큰 제어력이 필요하게 되며, 일반적으로 수동형

This paper presents vibration control of an active hybrid engine mount featuring a magneto-rheological(MR) fluid and a piezostack actuator. The MR fluid is adopted to improve isolation performance at resonant frequencies, while the piezostack actuator is adopted for performance improvement at non-resonant frequencies, especially at high frequencies. Based on some particular practical requirements of engine mounts, the proposed mount is designed and manufactured. The characteristics of rubber element, piezostack actuator and MR fluid are verified for system analysis and controller synthesis. The dynamic model of the proposed mount with a supported mass (engine) is established. In this work, a sliding mode controller is synthesized for the mount system to reduce vibrations transmitted from the engine in a wide frequency range. Computer simulations are performed to evaluate control performances of the proposed active engine mount in time and frequency domains.

The bearing strength of a blind riveted single lap joint of a carbon/epoxy composite after thermal exposure was studied. Considering the maximum service temperature based on material specifications and glass transition temperature, six types of specimens were prepared and tested in accordance with ASTM D5961. Failure loads of specimens exposed to a 177 °C environment were above 90% compared to sound specimens. Failure loads of 77% were obtained for specimens exposed to a 232 °C environment for 4 h. Bearing and rivet pulling-through failure modes were observed in all specimens. Delamination caused by degradation of the matrix property was found in specimens exposed to temperature higher than 204 °C.

This paper presents active vibration control performance of a hybrid mount. The proposed hybrid mount is devised by adopting both piezostack as an active actuator and rubber as a passive element. After experimentally identifying actuating force characteristics of the piezostack and dynamic characteristics of the rubber, the hybrid mount was designed and manufactured. Subsequently, a vibration control system with a specific mass loading is constructed, and its governing equations of motion are derived. In order to actively attenuate vibration transmitted from the base, a feedforward controller is formulated and experimentally realized. Vibration control responses are then evaluated in time and frequency domains.

To incorporate a diagnostic technique for measuring subtalar motion, namely “talar rotation”, into the manual supination-anterior drawer stress radiographs for evaluation of the severity of rotational instability, and to determine its clinical relevance. Sixty-six patients with combined injuries of the anterior talofibular (ATFL) and calcaneofibular ligament (CFL) underwent three bilateral manual stress radiographs, and mean increments of anterior talar translation (mm), talar tilt (°), and talar rotation (%) in the injured ankle compared to the normal opposite side were measured with the technique. Intraobserver and interobserver reliability of each measure was assessed, and the difference in the degree of increments was compared according to the presence of additional cervical ligament insufficiency. Ankle stress radiographic intraobserver and interobserver agreement was ICC = 0.91 and 0.82 for talar rotation (%), ICC = 0.64 and 0.51 for anterior talar translation, and ICC = 0.78 and 0.71 for talar tilt angle, respectively. In group 2 including patients with combined injuries of the ATFL and CFL along with additional cervical ligament insufficiency, a significantly higher increment of talar rotation, mean 6.4 % (SD 3.4 %), was observed compared to that of talar rotation, mean 4.1 % (SD 2.7 %), in the other group (group 1) with an intact cervical ligament (p

Progressive failure analysis based on the complete unloading method was conducted to investigate the crippling failure of carbon/epoxy composite stiffeners under axial compression. A modified arc-length algorithm was incorporated into a nonlinear finite element method to trace the equilibrium path after local buckling. For the validation of the finite element method, several carbon/epoxy Z-section stiffeners were tested in compression. The finite element results on the buckling and crippling stresses showed good agreement with the experimental results.

Recently, the Internet of things (IoT) became useful in various applications based on the web communication technology. The IoT has great potential in several service domains including cultural, educational, or medical areas. We consider a recommendation technique suitable for the IoT-based service. A personalized recommender system often relies on user preferences for better suggestions. We notice that we need a different recommendation approach in the IoT platform. While the conventional recommendation approaches rely on user preferences provided by users, these approaches may not be suitable for the IoT environment. The conventional systems utilize user ratings for items to compose recommendation list. This implies that the systems require additional user activities such as adding their preferences. We notice that the IoT environment can naturally provide user information such as users’ item selection history without users’ additional actions. We propose a recommendation model that does not require users’ additional actions and is more suitable for the IoT environment. We examine the usability of the bandwagon effect to build a new recommender system based on users’ selection history. We first consider the bandwagon effects in movie recommendation domain and show its usefulness for the IoT. We then suggest how to use the bandwagon effect in recommender systems with IoT.

With the development of the Internet, the users share information using Web applications. Because of this reason, there is lots of information on the Web. The information includes not only high quality information, but also useless one. With the phenomena, the recommendation system appears on the Web. Existing information recommendation systems on the Web have known problems. One famous problem is cold-start. We tackle the cold-start problem for a new item in recommendation system. To alleviate cold-start for a new item, we use method for identifying representative reviewers in raters group and recommendation algorithm based on category correlations. The representative reviewers mean the users who represent their raters group. Namely, the ratings of the reviewers can represent the average ratings of other users. If there are the ratings for new items rated by the representative reviewers, then we can consider the ratings rated by many other users. We predict the ratings of these reviewers for a new item. To predict ratings, we use the recommendation algorithm based on the category correlations. This algorithm can draw the prediction results without ratings since the algorithm uses category information. We propose the prediction results of the representative reviewers as the representative ratings for a new item. We propose the algorithm to alleviate cold-start for a new item and show the reliability of our approach through tests.

Since the late 20th century, the number of Internet users has noticeably increased. Recently, the number of Internet queries and the quantity of information available on the web has increased drastically. A large amount of new information is uploaded to the Web on a daily basis. However, search results are not always reliable due to the vast amount of data available on-line. As a result, users often have to repeat their searches in order to find exactly what they are looking for. To remedy this, some researchers have suggested recommendation systems. Since a recommendation system proposes information relevant to a particular query, users no longer need to repeat a search to obtain desired data. In the Web 2.0 era, recommendation systems often rely on the collaborative filtering approach, which is based on user information such as age, location, or preference. However, the traditional approach is affected by the cold-start and sparsity problems. The reason for these problems is the fact that the traditional system requires user information to operate properly. In this paper we address the sparsity problem associated with the current recommendation systems. We also suggest a new recommendation system approach and compare the performance of the proposed method with that of the traditional approach.

There are opinion leaders in a society who represent the opinion of general public. The general public accepts information not only by mass media but also by opinion leaders. Since the late 20th century, the number of Internet users has increased fast. Many users interact with each other in an online social network. This makes the Web community similar to the real society. Thus it is a natural task to find influential users in an online society. For example, many online articles posted by influential bloggers are used as marketing tools for companies or political advertisements for parties since these articles have huge influence to other users. We first revisit the previous researches on finding influential users in online society. Then we compose test sets from the GroupLens movie database and identify representative reviewers. Next, we show the validity of the chosen representative reviewers and test the reliability using the 10-fold cross- validation. Finally, we explain applicability of the proposed approach to improve current recommendation systems.

Since the late 20th century, the Internet users have noticeably increased and these users have provided lots of information on the Web and searched for information from the Web. Now there are huge amount of new information on the Web everyday. However, not all data are reliable and valuable. This implies that it becomes more and more difficult to find a satisfactory result from the Web. We often iterate searching several times to find what we are looking for. Researcher suggests a recommendation system to solve this problem. Instead of searching several times, a recommendation system proposes relevant information. In the Web 2.0 era, a recommendation system often relies on the collaborative filtering from users. In general, the collaborative filtering approach works based on user information such as gender, location or preference. However, it may cause the cold-star problem or the sparsity problem since it requires initial user information. Recently, there are several attempts to tackle these collaborative filtering problems. One of such attempts is to use category correlation of contents. For instance, a movie has genre information given by movie experts and directors. We notice that these category information are more reliable compared with user ratings. Moreover, a newly created content always has category information; namely, we can avoid the cold-start problem. We consider a movie recommendation system. We revisit the previous algorithm using genre correlation and improve the algorithm. We also test the modified algorithm and analyze the results with respect to a characteristic of genre correlations.

We propose a movie recommendation system based on genre correlations. We modify the previous algorithm; we use a list of movies as input instead of genre combinations. We implement a new recommendation algorithm as Android application with additional functions. By combining with existing web services such as Google Movie Showtimes and Open APIs, our system can recommend movies playing in cinemas currently and show the detailed information of movies. Location-based function is also implemented. We utilize GPS information of mobile device and web service provided by Google Maps for recommending suitable cinemas for users with mobile devices.

In recent years, the idea of wireless sensor networks has produced lots of research, because of wireless sensor networks can be applied widely in many fields. In wireless sensor networks, erroneous transmission can happen by wireless channel noise. Automatic repeat request (ARQ) detects errors using cyclic redundancy check (CRC) and retransmission of data is used as error control scheme for wireless sensor networks. Sensor node requires long lifetime with limited battery, but retransmission reception of data is the primary source of energy consumption and reduces the lifetime of sensor node. Therefore, error control scheme of forward error correction (FEC) for wireless sensor networks is necessary [1].

In Web 2.0, there is no clear distinction between users and webmasters. Many internet users are not only information consumers but also information providers. There are lots of information in the Web and most people can find what they want by searching the Web. One problem of the large number of data in the Web is that we often spend most of our time to find a correct result from search results. Thus, people start looking for a better system that can suggest relevant information instead of letting users go through all search results: We call such systems recommendation systems. A recommendation system is often based on collaborative filtering (CF). A traditional CF approach requires lots if user data so that a recommendation system can compute the similarity of user preferences and suggest items based on the computed preferences between users. This approach has two problems: sparsity and cold start. We propose a different CF approach based on the category correlation of contents. First, we show how to compute the category correlations of contents. Then, we design a new recommendation algorithm based on the category correlations to a user with certain preferences. Note that our approach does not require computing the preference similarity between users.

In a society, we have many forms of relations with other people from home, work or school. These relationships give rise to a social network. People in a social network receive, provide and pass lots of information. We often observe that there are a group of people who have high influence to other people. We call these high influence people opinion leaders. Thus, it is important and useful to identify opinion leaders in a social network. In Web 2.0, there are many user participations and we can create a social network from the user activities. We propose a simple yet reliable algorithm that finds opinion leaders in a cyber social network. We consider a social network of users who rate musics and identify representative users of the social network. Then, we verify the correctness of the proposed algorithm by the T-test.

During the early stages of combustion when bituminous coal particles are in a nearly single particle combustion environment, a surrounding mantle of volatile products is observed. Initially, the cloud is of spherical shape and almost concentric with the particle. As the reaction progresses, more material is ejected in the shape of jet-like tails. This rapid mass release was observed through in-situ high speed photographs of particles in combustion environment, and was also confirmed by examining cross sections of the quenched samples of coal particles. The inner structure became porous, while base material softened and some portion of it was ejected due to high pressure build up inside. Direct sampling of the partly burned coal particles revealed that the material in the volatile cloud contained tarry substances and small sized particle fragments in addition to gaseous volatiles. These solid and condensible substances were seen as a luminous envelope which implied that they participated in the radiative transfer process.

In this paper, a new type of switchgear, electro magnetic force driving actuator (EMFA), is developed and analyzed, applicable to high voltage gas circuit breakers (HGCB). Transient analysis is performed in order to obtain the dynamic characteristics of the EMFA. The distribution of static magnetic flux is obtained using the finite element method (FEM). The governing electric and kinematical equations are solved using the time difference method (TDM). Fabrication and experiments were performed in order to prove the applicability of HGCB for overall class. In comparing the experiment with simulated data, it is confirmed that analysis of the dynamic characteristics of EMFA is appropriate for design.

Photographic images of axisymmetric diffusion flames were interpreted using the computed tomographic techinque. The two dimensional images of an axisymmetric diffusion flame were measured by a commercial CCD array camera and a frame grabber. The image data were then used to reconstruct the original three dimensional spatially resolved distributions of emission intensities by using the computed tomographic technique. The reconstructed volumetric emission intensities were then converted into optical temperatures of soot particles by assuming that the system response parameters were constant. The constants were determined from the calibration tests with a blackbody cavity, and with thermocouple measurements. The reconstructed temperatures, which were considered as the temperatures of soot particles, showed reasonable resemblance to the expected temperature distribution. The characteristics of the optical system, such as F number and pixel distance (magnification of image), with respect to the accuracy of reconstructed data were discussed.

In this study, a hybrid mount featuring a magnetorheological (MR) fluid and a piezostack is devised to reduce vibrations occuring in dynamic systems which are operated in a wide frequency range. An MR fluid is adopted to improve isolation performance at resonant low frequencies, whereas a piezostack actuator is adopted for performance improvement at non-resonant high frequencies. As a first step, a passive rubber part is manufactured and its dynamic characteristics are experimentally evaluated. By adopting the MR fluid and the piezostack, semi-active and active actuating mechanisms are devised and their mathematical models are derived. In particular, the magnetic circuit for MR operation is optimally designed via finite element analysis. After evaluating the dynamic characteristics of the manufactured MR device and inertial piezostack actuator, the proposed hybrid mount is then established by integrating them with the rubber part. Subsequently, a vibration control system is constructed using the proposed hybrid mount, and a sliding mode controller (SMC) is designed to attenuate the vibrations transmitted from the base excitation. Control performances of the proposed mount are experimentally evaluated in time and frequency domains.

This paper presents an experimental investigation on vibration control using an active mount activated by piezostack actuators. After describing the schematic configuration and operational principle of the proposed active mount, dynamic characteristics of the rubber element and the piezostack are experimentally identified. An active mount is then manufactured using a rubber element and two piezostack elements. Prior to validating vibration control of the proposed active mount, fundamental characteristics such as resonant frequency, deflection at rated load, strength, shock and fatigue characteristics are experimentally investigated. A two-degree-of-freedom control system in which an active mount is installed with a supported mass of 100 kg is established for evaluating vibration control performance. In order to actively attenuate the vibration transmitted from the base excitation (50–1000 Hz), a negative velocity feedback controller is experimentally realized. Control responses such as mass acceleration are evaluated in both frequency and time domains.

In this work, a new active mount featuring piezostack actuators and a rubber element is proposed and applied to a vibration control system. After describing the configuration and operating principle of the proposed mount, an appropriate rubber element and appropriate piezostacks are designed and manufactured. Subsequently, the dynamic characteristics of the piezostacks and the rubber element are experimentally identified. A vibration control system with a supported mass of 50 kg is then constructed, and its governing equations of motion are derived. In order to actively attenuate the vibration transmitted from the base excitation, a robust sliding mode controller is formulated with consideration of parameter uncertainties. The controller is then experimentally realized and vibration control performances (acceleration and transmitted force) of the proposed mount are evaluated in both time and frequency domains.

A technique for estimating the instantaneous frictional force between the piston assembly and the cylinder wall has been developed by improving the moveable bore technique. The technique can be easily applied to small multi-cylinder engines since its structure is simple and stable so that the measuring range could be extended. The reliability of the friction data can be improved by a newly-proposed compensation method. The technique was applied to a four cylinder SI engine under various engine speeds, engine loads, and oil viscosity. An instrument for measuring the oil film thickness on the piston rings was also developed by using the commercially available gap sensors. It was possible to measure the oil film thickness on thin oil ring rails as well as on the compression rings. The frictional characteristics were established as a relationship between frictional mean effective pressure and a parameter which is the product of the piston mean speed and the oil viscosity.

This paper has been focused on developing a new hybrid mount for shipboard equipment used in naval surface ships and submarines. While the hybrid mount studied in our previous research was 100 kg-class series-type mount, the new hybrid mount has been designed as an inertia-type mount capable of supporting a static of 500 kg. The proposed mount consists of a commercial rubber resilient mount, a piezostack actuator and an inertial mass. The piezostack actuator connected with the inertial mass generates actively the control force. The performances of the proposed mount with a newly designed specific controller have been evaluated in accordance with US military specifications and compared with the passive mount. An isolation system consisting of four proposed mounts and auxiliary devices has been also tested. Through a series of experimental tests, it has been confirmed that the proposed mount provides better performance than the US Navy's standard passive mounts.