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Microalgae and cyanobacteria are photosynthetic microorganism used as human nutrients. Light is the most important factor affecting the biomass accumulation and production of bioactive compound by photosynthetic microorganisms. However, excessive light can suppress their growth by damaging the photosynthetic machinery such as Photosystem II (PS2). Therefore, an LED-based illumination system that is used for cultivation of photosynthetic cells needs a device to appropriately regulate the light level, but the addition of an electronic dimmer increases the initial costs. Spirulina is one of the promising and representative photosynthetic microorganisms. In the present study, we describe the use of a new semicylindrical column photobioreactor for cultivation of Spirulina. The amount of incident light reaching the photobioreactor was easily adjusted by changing angle of the LED in relation to the flat surface of the bioreactor. Arrangement of the LED bar at a 45° angle led to the highest growth and chlorophyll content, and led to no retardation of cell growth during the initial growth phase.

This paper explores the characteristics of a new lightweight thermoplastic composite filament filled with hollow glass beads developed for material extrusion additive manufacturing. Compounding experiments, which mix hollow glass beads with neat acrylonitrile butadiene styrene matrix, were conducted using a twin-screw extruder to prepare composite filaments. Two different types of hollow glass beads were selected as the fillers of composite filament due to their varying densities. In order to characterize the final components produced using composite filament, various specimens were fabricated by a material extrusion additive manufacturing process. In order to characterize the physical properties of the specimens, measurements of density and flexural testing were performed. To identify the thermomechanical effects of hollow glass beads on the neat acrylonitrile butadiene styrene matrix, thermal diffusivity and specific heat were obtained. Consequently, the thermal conductivity of the specimen was derived from its density, thermal diffusivity, and specific heat capacity. The microstructures of the fractured interfaces of the specimens were also observed by scanning electron microscopy. The experimental results revealed that most of the hollow glass beads survived, thus bringing about lighter weight (lower density) and thermal insulation (lower thermal conductivity), which can be useful for numerous potential applications.

Background: A polarization-directed flat (PDF) lens acts as a converging lens with a focal length (f) > 0 and a diverging lens with f < 0, depending on the polarization state of the incidental light. To produce a multifocal lens with two focal lengths, a PDF and a converging lens having shorter focal length were combined. In this study, we tested to determine its potential as a new multifocal intraocular lens (IOL).Methods: Constructed a multifocal lens with a PDF lens (f=+/- 100 mm) and a converging lens (f= +50 mm). In an optical bench test, we measured the lens’s focal lengths to test the multifocal function. The multifocal function and optical quality of the lens in various situations were tested. An Early Treatment Diabetic Retinopathy Study (ETDRS) chart as a near target and a parking lot as a distant target were photographed using a digital single-lens reflex (DSLR) camera. Both lenses (multifocal and monofocal) were tested under same conditions. Results: In the optical bench test, the multifocal lens’s focal lengths were 31.2 and 71.2 mm. In the DSLR test using the multifocal lens, the parking lot appeared slightly cloudy compared to the monofocal lens results. With the multifocal lens, the ETDRS chart’s images became blurry as the ETDRS chart’s distance decreased, but became very clear again at a certain position.Conclusions: We confirmed the multifocal function of the multifocal lens using a PDF lens. This lens can be used as a multifocal IOL in the future.

Fused deposition modeling (FDM), one of representative additive manufacturing (AM) technologies, has been widely used for fabricating functional parts with geometrical complexity. However, it has suffered from degraded part quality and low process reliability and controllability. Therefore, it is of much significance to develop a monitoring and diagnosis system for the FDM process to overcome such drawbacks. In this paper, a data-driven FDM process monitoring and diagnosis system is developed by using two types of sensors – an accelerometer and an acoustic emission (AE) sensor. A large number of experimental data, collected from the accelerometers and AE sensor under healthy and faulty process states, are processed to obtain a critical feature – a root mean square (RMS). The RMS values are then used for training the FDM process monitoring and diagnosis models based on a support vector machine (SVM) algorithm and a k-fold cross validation approach. In particular, the SVM-based models for the odd- and evennumbered layers of one FDM specimen are developed. For a real-time validation in a factory floor, the non-linear SVM-based models using the acceleration signals are used for the software development. The diagnosis accuracy is better than 87.5%, and an applicability of the models is verified.

In this paper, we discuss the subnetwork structure of the Blockchain system, which is expected to develop various application platforms in the future. Blockchain is an innovative trading system, and many studies have been conducted recently. It is expected to be used in various fields with stable security function of each node taking part in the system without central server control. However, due to its three functional limitations (excessive traffic generation, lack of distributed control, and unfairness of network resources) presented in this paper, it is difficult to provide complete service in the present network. In order to minimize such problems, a subnetwork structure providing a Blockchain service should provide an appropriate network configuration according to a Blockchain application or service type. In addition, based on the number of the node participated in Blockchain and the amount of data transmitted, it is necessary to provide appropriate QoS and the subnetwork should provide stable protocol function and efficient traffic operation. This subnetwork structure is proposed as a service function of the future network structure of ISO / IEC JTC1 SC6 which is being standardized.

With the advent of many IoTs, users need a common use environment to easily connect, search, and share various IoTs. In addition, as IoTs become increasingly intelligent, there is a growing demand for services that work together. However, a large number of IoTs can cause serious traffic to the network when they collaborate with each other in a common usage environment. In this paper, we have designed the structure of IoT to construct a distributed social network based on semantic web to solve this problem. We also designed and implemented an autonomous collaborative service of IoT that can find collaborative partners through social network and accumulate experience knowledge after collaboration. We defined IoT with this structure as Smart Thing and a unique Basic Identity Information (BII) that allows Smart Thing to identify each other. In addition, we defined Basic Response Rules (DRRFS) for Smart Thing to follow in the Query & Answer process for Collaboration. Smart Thing with basic identity information is an independent, autonomous IoT device. Smart Thing with a distributed social network finds collaborative partners though recursive queries and provides services. In addition, we have confirmed in the autonomous collaborative system that Smart Thing who has experienced collaborations can work faster and more accurately using the accumulated experience knowledge when the same thing is done again. If all IoTs have basic identity information and use semantic technology, the Internet will be a huge space where Smart Thing can collaborate.

Soybean curd wastewater (SCWW) is a by-product of the compression of protein coagulants performed during production of soybean curd (tofu). In this study, SCWW was used as a low-cost nutrient source for the cultivation of an Aurantiochytrium strain known to produce significant amounts of polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA). Instead of sterilization of the SCWW medium by heating (which promotes the Maillard reaction and production of hydroxymethylfurfural), the SCWW medium was sterilized using peracetic acid (PAA) followed by neutralization with a ferric ion solution. The growth of cells was similar in PAA-sterilized SCWW medium and sterile-filtered or autoclaved M7D20 medium that contained commercial components (glucose, yeast extract, and peptone). Surprisingly, cells grown in PAA-sterilized SCWW medium had more than 4-fold greater production of DHA than cells grown in autoclaved or filtered M7D20 medium.

Graduate School of Energy & Environment, Seoul National University of Science & Technology, 232 Gongreung-Ro, Nowon-Gu, Seoul 01811, KoreaMarine Biodiversity Assessment and Management Team, National Marine Biodiversity Institute, 101-75 Jangsan-Ro, Janghang-Eup, Seocheon-Gun, Chungnam 33662, Korea요 약 : 본 논문에서는 해양수산부가 지정한 보호대상해양생물 중 하나인 대추귀고둥을 대상으로 하여 보전가치를 정량적으로 평가하고자 한다. 이를 위해 대추귀고둥과 같은 비시장재화에 대한 경제적 가치 평가기법인 조건부 가치측정법을 적용하였고, 무작위로 추출된 전국 1,000가구를 대상으로 설문조사를 수행하여 대추귀고둥의 보전을 위한 지불의사액 정보를 유도했다. 지불의사 유도방법으로 1.5경계 모형을 적용했으며, 영(0)의 지불의사액 자료를 다루기 위해 스파이크 모형을 결합하였다. 분석결과 대추귀고둥의 보전가치는 가구당 연간 2,346원으로 추정되었으며, 이 값은 유의수준 1%에서 통계적으로 유의하였다. 이 값을 전국으로 확장하면 연간 438억원에 달한다. 즉 우리나라 국민들은 대추귀고둥의 보전을 위해 유의한 금액을 기꺼이 부담할 용의가 있었다.핵심용어 : 보호대상해양생물, 보전가치, 대추귀고둥, 조건부 가치측정법, 지불의사액Abstract : This paper attempts to quantitatively assess the conservation value of Ellobium chinense (EC), which belongs to the endangered marine species designated by Ministry of Oceans and Fisheries. To this end, we apply the contingent valuation (CV) method, an economic technique of valuing a non-market goods such as EC. A national survey of randomly selected 1,000 households was administered in order to derive the public’s willingness to pay (WTP) for conserving EC. One-and-one-half-bound model was adopted to elicit the WTP responses and a spike model was employed to deal with the zero WTP responses. The results show that the conservation value of EC is estimated to be 2,346 won per household per year that is statistically significant at the 1% level. Expanding the value to the national population gives us an annual value of 43.8 billion won. We can judge that the Korean people are willing to pay a significant amount to conserve EC. Key Words : Endangered marine species, Conservation value, Ellobium chinense, Contingent valuation method, Willingness to pay1)

Isothiocyanates (ITCs) derived from cruciferous vegetables, including benzyl isothiocyanate (BITC), phenethyl isothiocyanate (PEITC) and sulforaphane (SFN), exhibit preventative effects against various types of cancers. Yet, the inhibitory effects of ITCs on C6 glioma cell invasion and migration have not been reported. Thus, we aimed to analyze ITC-regulated MMP-9 activation, a crucial enzyme of cancer metastasis that degrades the extracellular matrix, in C6 glioma cells to investigate the inhibitory effects on cancer invasion and migration by ITCs. In the present study, we found that ITCs specifically suppressed PMA-induced MMP-9 secretion and protein expression. The inhibitory effects of ITCs on PMA-induced MMP-9 expression were found to be associated with the inhibition of MMP-9 transcription levels through suppression of nuclear translocation of NF-κB and activator protein-1 (AP-1). It was also confirmed that ITCs decreased MMP-9-mediated signaling such as FAK and JNK, whereas they had no effect on the phosphorylation of ERK and p38. Moreover, wound-healing and Τranswell invasion assays showed that ITCs inhibited the migration and invasion of C6 glioma cells. These results suggest that ITCs could be potential agents for the prevention of C6 glioma cell migration and invasion by decreasing FAK/JNK-mediated MMP-9 expression.

Intraocular pressure is measured after a cornea air puff by observing biomechanical properties such as thickness or displacement of the cornea. In this paper, we deal with a frequency domain analysis of corneal deformation in the air puff tonometry that is used to diagnose glaucoma or lasik. We distinguish the patient from the normal by measuring the oscillation frequency in the neighborhood of the central cornea section. A binary image was obtained from the video images, and cornea vertical oscillation profile was extracted from the difference between the vertical displacement data and the curve fitting. In terms of Fourier transform, a vibration frequency of 479.2Hz for the patient was obtained as well as more higher 702.8Hz for the normal due to stiffness. Hilbert-Huang transform's empirical mode decomposition generally describes local, nonlinear, and nonstationary data. After the data were decomposed into intrinsic mode functions, a spectrum and power were analysed. Finally, we confirm that the patient has 6 times more higher power ratio for the specific intrinsic mode function between the patient and the normal.

As both laboratory accelerated experiment and field exposure experiment were performed, at recent, the fifth field test at five year exposures was proceeded according to long period experimental plan. Field experiment, for the adoption of the developed evaluation model, which is consisted of the analysis of chloride penetration profile at gate bridges of sea-dike completed 30 years ago was carried out during upgrading the basic evaluation model with analyzing the annual field test data. The surface concentration of chlorides was replaced to the concentration of chloride of inner concrete near the surface chlorides among his research results at basic model. Maage’s suggestion function was accepted too as a diffusion coefficient of chloride after verifying the change of diffusion coefficient by analysis of annual field test data. The comparison of field data with model predictions and the estimation of remaining life time demonstrates that the proposed updated model and maintenance simulation system can be used to predict the chloride penetration profile in the marine tidal zone and appropriate repair period and cost.

This paper proposes new phase error compensation method of RVDT encoder in the FFT domain. Phase errors are measured with a small combination of compensation resistors and the changes of first order coefficients of FFT for each resistor are obtained. It is found that the coefficient change is inversely proportional to the inserted resistor. The proposed method takes less time and the size of the table is smaller than previous time domain approaches. In addition, the location of the compensation resistor can be found through axis transformation of the coefficients. Finally, the peak-to-peak phase error was improved to 0.57 which is two times better than previous one.

This article describes “WAMbot,'' an autonomous unmanned ground vehicle and the Team MAGICian solution to the 2010 Multi Autonomous Ground-robotic International Challenge (MAGIC). The system architecture, hardware, sensing, planning, navigation, mapping systems, and user interface were specifically designed to address the demands of the large-scale distributed reconnaissance and surveillance task presented in the challenge. The resulting system was selected as a finalist and ultimately placed 4th in MAGIC 2010. © 2012 Wiley Periodicals, Inc. © 2012 Wiley Periodicals, Inc.

For the reconstruction of the past vegetational changes in Jeju Island, Korea, pollen analysis and radiocarbon dating on the sediments obtained from the Mulyeongari fen were carried out. By the results, the vegetational changes around the Mulyeongari fen from ca. 3,300 cal. yr BP to the present can be interpreted and reconstructed. The pollen record from the Mulyeongari fen was divided into two local pollen assemblage zones and three sub-pollen assemblage zones. Zone I (Quercus-Carpinus-Herbs Zone) was characterized by the predominance of Quercus(30~63%), Carpinus(9~35%) and herbs(40~424%). Zone II was characterized by three sub-pollen assemblage zones and the high occurrence ratio of the tree layer in comparison with Zone I. In Zone IIa (Quercus-Carpinus Zone), herbs(3~161%) were drastically decreased in predominance of Quercus(28~56%) and Carpinus(14~31%). In Zone IIb (Carpinus-Quercus Zone), Carpinus(36~48%) was preferentially increased but Quercus(29~39%) was slightly decreased. In Zone IIc (Quercus-Carpinus Zone), Carpinus(26~38%) was decreased inversely but Quercus(36~50%) was increased. In addition, Cyperaceae was also increased to 52%. Consequently, it is suggested that cool temperate southern/sub-montane vegetation composed of Quercus and Carpinus which was physiognomy of deciduous broad leaved forest was distributed around the Mulyeongari fen from ca. 3,300 cal. yr BP. In addition, Cyclobalanopsis(4~23%), Castanopsis(1~12%) and Myrica(under 1%) which are warm-temperate evergreen deciduous forest components were constantly appeared from this period. Accordingly, it can be inferred that the present vegetation type around the Mulyeongari fen was formed from ca. 180 cal. yr BP.

Existing error compensation method of industrial electronic absolute displacement detector only depends on skilled engineers. This paper proposes a new table method in order to automatize error compensation. An waveform changes according to the parallel resistance for each pole were tabularized and four waveforms were superimposed to minimize total phase error. These process was verified using simulink. As a result of applying proposed method to the real sensor, peak to peak error was reduced from 3.428° to 0.879°. In this case, compensation resistance is 4.7kΩ in B pole and 20kΩ in C pole. This compensation rate is comparable to skilled engineers, and it takes 0.8 second which is far shorter than 15 minutes when expert does.

In this work we demonstrate the hot-embossing process under different forming conditions such as forming temperature, load, and holding time in pressing, in order to determine the suitable conditions required for linear patterning on polymer plates (PMMA and PC). Results showed that the replicated pattern depth increased in proportion to an increase in the forming temperature, load, and time. The reduction of the workpiece thickness increased according to the holding time in the pressing process. In the process of time, the reduction ratio of the workpiece thickness decreased due to the surface area increment of the workpiece, while the pressure on the workpiece declined. In order to reduce the bulging ratio we introduced a temperature difference between the upper and the lower punch.

In this paper, a novel CMA (constant modulus algorithm) algorithm employing fast convolution in the DFT (discrete Fourier transform) domain is proposed. We propose a non-linear adaptation algorithm that minimizes CMA cost function in the DFT domain. The proposed algorithm is completely new one as compared to the recently introduced similar DFT domain CMA algorithm in that, the original CMA cost function has not been changed to develop DFT domain algorithm, resulting improved convergence properties. Using the proposed approach, we can reduce the number of multiplications to O(N log 2 N), whereas the conventional CMA has the computation order of O(N2). Simulation results show that the proposed algorithm provides a comparable performance to the conventional CMA.

We present the optical coherence tomography (OCT) made to investigate the early dental caries in human teeth and compare its results with those taken by conventional imaging modalities including light illuminating examination (LIE), digital intra-oral radiography (DIOR), and electron probe micro analyzer (EPMA). Morphological features and caries-involved areas of the dental structure were mainly investigated by LIE, DIOR, and OCT to study the infection of the caries lesion in pits and fissures. The biochemical information acquired with EPMA and the morphological features taken with OCT in the early stage of caries were compared and analyzed to present an objective and practical index for the degree of caries. The experimental results allow us to conclude that OCT could be used to provide quantitative analysis of caries based on the reflectivity difference in the specimen.

Wind turbine experiment was carried out for the horizontal axis wind turbine with the aerodynamically optimized blade. From the comparison of aerodynamic performance between upwind and downwind type wind turbine rotor, the measured torque fluctuation of the latter is larger than that of the former. This phenomenon is owing to the interaction of wake generated from support column and blades. The wind turbine model satisfies the design condition in that the measured result of the power coefficient at zero pitch angle shows maximum peak at the designed tip speed ratio, λ

Optical coherence tomography(OCT) is a high resolution imaging system which can image the cross section of microscopic organs in a living tissue with about resolution. In this paper, we implement OCT system and acquire 2-D images of rat eye and human molar samples especially in the field of opthalmology and dentistry. In terms of 2-D images, we reconstruct 3-D OCT images which give us another inner structural information of target objects. OPEN-GL reduces the 3-D processing time 10 times less than MATLAB.

Absolute position detector which is one of the major equipment in the field of factory automation, not only perceives the absolute position of the rotary machine but also outputs switch data according to the given angle. Absolute position detector is composed of sensor module and its controller. In this paper, a sensor driver is implemented using FPGA with VHDL. This chip has a less form factor than conventional circuit. A test shows reliable precision within THD(total harmonic distortion) of 0.2% which can be applicable commercially. Also, FPGA-based phase error compensation methods were newly discussed. In the future, more research will be conducted to enhance the precision by the introduction of 3-phase transformer.

HEC-RAS model is used for estimation of rating-curve of Musung in Wi stream. Discharge is computed from stage estimated by HEC-RAS model, is compared with the discharge of water surface slope method. The relative deviation of observed and computed discharge is 5.37%, and shows as a good results. A rating-curve by HEC-RAS model shows better results than by water surface slope method.

A novel all-fiber optical delay line for an advanced optical coherence tomography (OCT) system is proposed. Using the distributed reflectance characteristic of a chirped fiber Bragg grating (CFBG), the optical delay can be obtained without leaving the fiber that forms the system. The proposed delay line consists of a pair of identical CFBGs. The gratings are cascaded in reverse order to cancel the inherent wavelength dependency of CFBGs. Tunable optical delay is obtained by applying small strain on one of the CFBGs through an attached piezo actuator. The small displacement induced by the piezo actuator is amplified by a factor of up to 100 due to the distributed reflectance characteristic of the CFBGs. This principle and characteristics of the proposed optical delay line are analyzed in detail.

Optical Coherence Tomography (OCT) is considered as fundamentally new image modality having advantages such as high-speed, real-time cross sectional imaging with non-invasive in vivo investigation of biological tissue and its potential for clinical application is highly evaluated. In spite of these merits, the research activity in OCT has not taken much attention until recently. However the situation in Korea is gradually changing due to understanding of its versatile applications. Active research and commercialization are underway. Bulk optics-based OCT system is changed into alignfree fiber-optics system. With our expertise in the fabrication of fiber grating devices and strong background in control of fiber based system, we hope to contribute in developing simplified all-fiber OCT system with better performance. As a leading research group, working on OCT, we have firstly implemented fiber-based OCT system in Korea and demonstrated the imaging performance with glass plate and onion.

We propose the noncontact photoacoustic tomography system that reads the acoustic signal by using an optical fiberbased heterodyne interferometer. The surface displacement of a specimen, resulting from the acoustic wave generated by irradiation of a laser pulse and its absorption inside the specimen, is optically measured by the heterodyne interferometer. With the data set of the surface displacement, the photoacoustic image of the specimen is reconstructed by a Fourier transform based reconstruction algorithm. This proposed method is experimentally evaluated by using a phantom sample that contains PET fibers.

We report an all-fiber heterodyne interferometer for the measurements of laser-induced thermoelastic deformation to estimate the Gruneisen coefficient and the optical attenuation depth of a sample. The system comprises a Q-switched Nd-YAG laser providing a nanosecond excitation pulse and an all-fiber heterodyne interferometer that measures the induced displacement of the sample surface. To evaluate the system, phantom experiments were carried out with various gelatin-based models. The results show that the attenuation depth and Gruneisen coefficient of the phantoms were about 4.256 mm and 0.568, respectively. In addition, increase of the weight fraction of gelatin led increase in the Gruneisen coefficient.

A problem in configuring modular self-reconfigurable robots with distributed control is determining whether a module can be moved without breaking the system apart. In finding a set of modules that can be safely moved, the key issues are to maximize the number of mobile modules identified and minimize the time consumed in finding these modules. In this study, a distributed search algorithm is proposed and compared to an existing approach.