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To reduce the end-to-end delay in EH-WSNs (energy-harvesting wireless sensor networks), medium access control protocols using pipelined-forwarding have been introduced and studied. In real-life applications, there are several situations where it is difficult to harvest more energy than the energy consumed. Therefore, it is crucial to design a MAC protocol that allows nodes to efficiently relay data without exhausting the power in pipelined-forwarding multihop transmission. In this paper, we propose a PP-MAC (priority-based pipelined-forwarding MAC) protocol that determines the priority of relay nodes based on the residual power and energy-harvesting rate. The proposed protocol determines the probability of a node becoming a relay node based on the priority of the node and attempts to access the channel in a distributed manner. Furthermore, the PP-MAC protocol controls the sleep interval based on the power conditions of the nodes. It also minimizes the power exhaustion problem by controlling the sleep interval based on the priority of the nodes. The performance of the proposed PP-MAC was evaluated via computer simulation, and the results indicated that PP-MAC could improve the network lifetime by mitigating the power imbalance of nodes.

Location choice has been one of the key elements to affect the performance of firms. While existing literature highlights the strategic value of agglomeration, we question whether the value also applies in the context of developing economies, considering the weak institutional environment would hamper the overall benefit of clusters. Based on the exploitation-exploration framework proposed by March (1991), this study posits that the exploration-oriented locations provide more opportunities for firms operating in developing countries. Reflecting the characteristics of developing countries that state intervention is common and strong, we hypothesize that the state ownership, opposite to the venturing spirit, flexibility, and agility on the private businesses, weakens the strategic fit with the exploration-oriented location choices. Using a dataset of Vietnamese firms listed in the Ho Chi Minh Stock Exchange, our statistical findings show that firms’ level of exploration orientation would have a positive effect on firm performance. Additionally, the level of state ownership would weaken the effect of exploration-oriented location choice on the performance. Overall, this study suggests that exploration-oriented locations may be the optimal choice for firms who would seek profitability and achieve competitive advantage in developing countries. At the same time, state ownership may prevent firms from efficiently utilizing the accessible resource in those locations.

This study concerns the complicated institutional logics that SMEs in emerging markets employ when deciding to upgrade management quality. We assume that social relationships affect business decisions. Political ties induce SME decisions to upgrade quality by urging firms to align with the institutional rationale for upgrading management quality. By contrast, business ties may induce or discourage standard adoption, depending on the logic. We further hypothesize that innovation orientation positively moderates the effects of political and business ties on the decision to upgrade. However, a global orientation shifts the rationale of the decision from the “domestic” to the “foreign,” thereby negatively moderating all links between network ties and the upgrading of management quality. We use an unbalanced panel of 373 Vietnamese SMEs, with 1,012 firm-year observations. A fixed-effect logit regression analysis shows that political ties increase standard adoption, whereas business ties discourage it. Furthermore, an innovation orientation strengthens the negative effect of business ties on management quality upgrades, whereas a global orientation weakens the positive link between political ties and standard adoption as well as the negative link between business ties and standard adoption. Our study suggests that state initiatives for upgrading management quality may not easily reach emerging-market SMEs owing to the competing logics surrounding them.

Cognitive radio network was proposed to use the spectrum resource more efficiently. In a multichannel ad-hoc cognitive radio network, there is no central station and requires distributed channel scheduling. An important requirement of the cognitive radio network is to avoid interference to primary networks. In this paper, the authors propose the distributed packet scheduling scheme for ad-hoc multichannel cognitive radio networks. Each secondary user calculates independently its own priority with probabilistic manner and selects one of multi channels considering the primary user’s traffic pattern to minimize interference to the primary networks.

It is important that using of efficient radio resource because of deficiency spectrum problem, so that related to this problem many researches are have proceeded. To solve this problem, Cognitive Radio(CR) was suggested. The channels are allocated to the secondary users when the primary users don`t use the channels, and unfairness of secondary users can be serious problem and channel quality of multichannel can be different due to the different traffic pattern of primary users. In this paper, we propose MAC prtocol both of the user`s fairness and channel quality in CR networks. Simulation results show the comparison with CR MAC protocols.

Herein, a novel stretchable Cu conductor with excellent conductivity and stretchability is reported via the flash‐induced multiscale tuning of Cu and an elastomer interface. Microscale randomly wrinkled Cu (amplitude of ≈5 µm and wavelength of ≈45 µm) is formed on a polymer substrate through a single pulse of a millisecond flash light, enabling the elongation of Cu to exceed 20% regardless of the stretching direction. The nanoscale interlocked interface between the Cu nanoparticles (NPs) and the elastomer increases the adhesion force of Cu, which contributes to a significant improvement of the Cu stability and stretchability under harsh yielding stress. Simultaneously, the flash‐induced photoreduction of CuO NPs and subsequent Cu NP welding lead to outstanding conductivity (≈37 kS cm−1) of the buckled elastic electrode. The 3D structure of randomly wrinkled Cu is modeled by finite element analysis simulations to show that the flash‐activated stretchable Cu conductors can endure strain over 20% in all directions. Finally, the wrinkled Cu is utilized for wireless near‐field communication on the skin of human wrist.

Efficient routing algorithm is required to transmit data from source to destination by multi-hop transmission in wireless sensor networks. In the multi-hop transmission, multipath routing can be one of the solutions to cope with the traffic congestion and unstable link condition. In this paper, we propose partial multipath routing which does not establish a secondary full routing path but a partial multipath to complement some poor links, and it can enable stable data transmission and reduce the number of nodes in routing path and the required total power compared with conventional multipath routing.

In wireless sensor networks, sensor nodes have a short transmission range and data is transferred from source to destination node using the multi-hop transmission. Sensor nodes are powered by battery and the link qualities are different, and the routing protocol in the wireless sensor network is one of the important technical issues. Multipath routing was proposed to reduce the data congestion and increase data throughput. In the multipath routing, however, each path can be interfered by the other path, and it can aggravate network performance. In this paper, we propose the multipath routing scheme for multi-rate wireless sensor networks. The multipath routing selects transmission paths to minimize transmission delay and path interference.

In this research, we develop an immersive mixed reality game environment using an actuated conveyor belt surface as a game stage. One game player creates the game environment by arranging tangible objects; those objects linearly flow and interact with a virtual character manipulated by another player. We expect that game enjoyment could be leveraged while being highly immersed into mixed reality game world. Also, new kinds of interaction between two players with different game roles are expected. The prototype was pilot-tested and planned for a future demonstration.

Skateboarding is an extreme sport that is consists of various trick performances. You can control your board with various foot movements, and slip over the obstacle with the board. In this research, we provided a Motion Log Skateboard system that visualizes the pressure distribution of the foot on the board. A customizable pressure sensor sheet was attached to the top of the skateboard deck, and the distribution of pressure was imaged and reproduced along with the recorded video in smartphone App. We have focused on visualizing non-visible information of body movement, which is not easily observed but acts as important elements in sports activity. We expect that the providing these kinds of information through the interactive technology will encourage discussion on the body movement and induce people to share their boy movement with others.

Knowing your own body movement is an essential element of sports. Recently, the popularization of smartphones has enabled people to easily record their performance in most situations. However, these observations have limited applicability in assisting with a clear understanding of body movement. In this paper, we propose the Motion Log Skateboard, which records and shares non-visible information about body movement that is difficult to obtain through current observation methods in skateboarding. A pressure-sensor matrix on a skateboard deck is used to record the pressure distribution data, which are then played using the video function of a smartphone camera. With this logged data, a user can access the feet positions, pressure intensity, and timing of the foot movements. To verify the proposed concept and determine the specific context of its use, an experimental session and interviews were conducted with skateboarders of various skill levels. Based on the results of this research, the shared experiences of non-visible information, which is perceived differently depending on the individual, are expected to become a standard for exploring and training body movement.

Spectrum handoff is the process of exchanging progressing data transmission from the current channel to another idle channel. The essential goal of spectrum handoff in CR(Cognitive Radio) networks is to perform consistent data transmission while sustaining performance of ongoing transmission of secondary users. This handoff procedure can cause additional latency that eventually affects on the performance of CR transmission. Channel prediction method is expected to avoid the disruption to primary users and to reduce the handoff latency. In this paper, adaptive channel prediction is proposed to cope with time-varying channel and an adaptive channel prediction based proactive handoff procedure is designed to enhance data transmission performance.

Cognitive radio (CR) has been proposed to solve the spectrum utilization problem by dynamically exploiting the unused spectrum. In CR networks, a spectrum selection scheme is an important process to efficiently exploit the spectrum holes, and an efficient channel allocation scheme must be designed to minimize interference to the primary network as well as to achieve better spectrum utilization. In this paper, we propose a multichannel selection algorithm that uses spectrum hole prediction to limit the interference to the primary network and to exploit channel characteristics in order to enhance channel utilization. The proposed scheme considers both the interference length and the channel capacity to limit the interference to primary users and to enhance system performance. By using the proposed scheme, channel utilization is improved whereas the system limits the collision rate of the CR packets.

Recently, multimedia data transmission becomes important issues in the wireless sensor network. For the multimedia data transmission in wireless sensor network, QoS (Quality of service) is an important factor to determine the system performance. AODV algorithm is one of the widely used algorithm for wireless ad-hoc environment. In AODV, the destination node selects the route with the smallest hop count. Since AODV only considers the hop count, the selected route could have low channel condition, and degrade QoS. In this paper, we propose a modified AODV algorithm that considers the successful transmission rate of each link. The proposed algorithm regards the number of retransmission which can be obtained from the successful transmission rate as the hop count, and applies the modified hop count to AODV. The advantage of the proposed algorithm is that the modified AODV can support QoS without significant change of the conventional algorithm.

Cognitive radio has been recently proposed to dynamically access unused-spectrum. The CR users can share the same frequency band with the primary user without interference to each other. Usually each CR user needs to determine spectrum availability by itself depending only on its local observations. But uncertainty communication environment effects can be mitigated so that the detection probability is improved in a heavily shadowed environment. Soft detection is a primary user detection method of cooperative cognitive radio networks. In our research, we will improve system detection probability by using optimal cooperative node selection algorithm. New algorithm can find optimal number of cooperative sensing nodes for cooperative soft detection by using maximum ratio combining (MRC) method. Through analysis, proposed cooperative node selection algorithm can select optimal node for cooperative sensing according to the system requirement and improve the system detection probability.

In this research, we propose an interactive snowboard concept, Motion Echo Snowboard, which helps perceiving body movement in snowboarding. By installing the display on the upper side of snowboard deck, a mundane wooden board, we visualized weight distribution, which is important movement related information in snowboarding. We expect that new kinds of interaction could be developed in individual usage and lesson usages of snowboarding. The prototype was pilot-tested on an indoor ski slope and formulated the structure of a user study for future.

Cognitive radio technology enables us to utilize the extra spectrum which is not used by the primary users by sensing the channel condition. To use such an extra spectrum, spectrum allocation is one of the important issues in the cognitive radio networks. The network is dynamic and the available channels are changeable, and the opportunistic channel allocation is required to use the resource efficiently without interference to the primary networks. In this paper, modified proportional fairness scheduling is proposed for cognitive radio networks to satisfy the both fairness and system throughput, and the modified scheduling was designed to reduce the interference to the primary users.

Channel allocation is one of the important issues in the multichannel transmission. In the cognitive radio networks, channel allocation scheme should be designed to improve spectrum efficiency without interfering with the transmission of licensed users. In this paper, we propose a spectrum hole prediction based channel allocation scheme. The proposed channel allocation scheme, predicts spectrum hole by using the channel success rate, and limit the transmission of secondary user`s data, and it reduces the interference to the primary user. The performance of proposed channel allocation scheme is evaluated by the computer simulation.

하지만 아직 이러한 용접재료가 상용화되었다는 보고는 접하지 못하였다. 국내에서도 유사한 연구가 2005년부터 수행되어 최근 800MPa급 강도를 가지면서 무예열 용접 가능한 GMAW용 용접재료 뿐만 아니라 SAW용 및 FCAW용 용접재료도 개발되었다. 그리고 이들 재료는 한국선급에서 제정한 ‘무예열 고강도 용접재료 승인 및 검사 지침’에 의거하여 기술시험평가를 실시하여 무예열 용접성 및 군수용 사용적합성 인증을 획득하였다. 본 기술보고에서는 GMAW용 용접재료에 대해 소개하고자 한다. 소개하고자 하는 GMA 용접재료는 무예열 용접성을 확보하기 위하여 C함량을 0.01% 수준으로 낮추었으며 와이어의 표면을 최적 관리하여 확산성수소량을 최소화하였다. 그리고 본 용접재료는 혼합가스용으로 개발되어 Ar+(5~20)%CO

Mobile WiMAX system provides broadband wireless access with a variety of services such as voice, video and data communications and providing QoS for each of these services become an important issue. In Mobile WiMAX system, it is important to allocate resources appropriately in order to support the efficient utilization of resources among various real-time and non real-time services. Although many packet scheduling schemes for real-time services in OFDMA system have been proposed, it need to be modified to apply to Mobile WiMAX system. Since Mobile WiMAX supports five types of service classes, QoS constraints of each class should be taken into consideration. In this paper, we propose an efficient packet scheduling scheme to support various services by considering the QoS constraints of each class.

— Opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. The proposed protocol’s simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.

An ubiquitous sensor network (USN) system to monitor the bio information and the emergency of the elderly in the silver town is presented. The USN system consists of the sensor node platforms based on MCU of Atmage128L and RF Chip of CC2420 satisfying IEEE 802.15.4, which includes the bios sensor module such as the electrocardiogram (ECG) sensor and the temperature sensor. Additionally, when an emergency of the elderly is occurred in the silver town, the routing algorithm suitable to find and inform the location of the elderly is proposed, and the proposed routing algorithm is applied to the USN. To collect and manage the ECG data at the PC connected to the sink node, LabView software is used. The bio information and the emergency of the elderly can also be monitored at the client PC by TCP/IP networks in the USN system.

Wireless Sensor Networks are widely applied for organizing real-time monitoring systems. Unlike general kinds of sensor networks, it is important to preferential send emergency data to the control server when urgent events are occurred. But IEEE 802.15.4 MAC protocol which is generally deployed for wireless sensor network does not support algorithm for urgency data handling. Therefore, we proposed a MAC protocol which consider the priority for the urgency data handling.

opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. A dynamical sensing range as a important parameter introduced to maintain the our protocol performance. The proposed protocol"s simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.

A power- and delay-efficient routing algorithm and emergency-efficient protocol of ubiquitous wireless sensor network systems for silver town applications is presented. For this protocol, a fixed node (without any limited resources) is established at one point which can communicate with one-hop to both the sink node and the mobile sensor nodes in the dark region (in which mobile sensor nodes cannot communicate to the sink node). The fixed nodes are operated like the fixed cluster head. The simulated lifetime of the proposed routing algorithm is longer than those of LEACH and HEED and the simulated time delay of the proposed routing algorithm is faster than those of LEACH and HEED when the three protocols are applied to a specific silver town environment.