• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.253-256
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• 1997

KESF-1 foot conceptually provides storage of potential energy and is converted to kinetic energy throughout the weight - bearing phase of the gait cycle. This stored energy is progressively released as the foot continues through the toe-off phase to rebound and propel the body forward. A weight deflects the keel through a predetermined range, then the keel "springs back" as weight is removed. Foot designs criteria were selected to guide development beyond the proof-of concept composite material keels; 1) store and return energy (1-3/4 " metatarsal deflection at 435 pounds vertical load), 2) natural feel and stability; 3) useful life of 3-years: 4) lightweight; 5) reduced production costs. The purpose of this study is developed the comfortable stable foot that fitted with Korean lifestyle and road condition. The results produced the realistic cosmetic foot cover with polyurethane form and the keel composed with composite materials of both glass fiber and carbon fiber.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.34-36
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• 2008

This paper is given a full detail of mathematical analyses of input current for novel active type power factor correction(PFC) AC-DC converter of step up-down added electric isolation. These are compared with harmonics components of input current for a conventional PFC converter of electric isolation type. The proposed PFC converter is constructed in using a new loss-less snubber circuit to achieve a soft switching of control device. Also the proposed converter for discontinuous conduction mode(DCM) eliminates the complicated circuit control requirement and reduces the size of components. The input current waveform in the proposed converter is got to be a sinusoidal form of discontinuous pulse in proportion to magnitude of ac input voltage under the constant duty cycle switching. Therefore, input power factor is nearly unity and the control method is simple. Particularly, the stored energy of loss-less snubber capacitor is recovered with input side and increases input current from resonant operation. The result is that input power factor of the proposed converter is higher than that of a conventional PFC converter. Some simulative results on computer and experimental results are included to confirm the validity of the analytical results.

• 한국컴퓨터정보학회논문지
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• 제15권10호
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• pp.137-145
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• 2010

본 논문은 USN(Ubiquitous Sensor Network) 기술 기반의 적외선 센서를 사용한 비접촉식 식물 생장 측정 시스템을 제안한다. 제안된 시스템은 식물 생장을 측정할 때 식물의 생장 피해를 줄이기 위하여 비접촉 센서를 사용하였다. 이 시스템은 직경, 단면적, 비대 형상과 같은 식물 생장 요소를 실시간 비접촉 방식으로 측정할 수 있다. 측정된 데이터는 센서 네트워크 기술을 사용하여 원격 서버까지 전송되고, 서버에서 저장 및 분석되며, 최종적으로 분석된 데이터는 사용자에게 제공될 수 있도록 구성하였다. 본 논문에서 제안된 식물 생장 측정시스템은 측정 방식과 장치에 비접촉 적외선 센서를 사용하여 설계 및 구현을 하였다. 그리고 시스템의 성능은 필드에서 측정 실험을 통하여 검증해 보았다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 춘계학술대회
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• pp.436-439
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• 2011

휴대용 디지털 기기 보급의 확산되면서 휴대용 저장장치 수요가 급증하고 있으며, 디지털 카메라 및 캠코더에서는 대부분 SD 메모리 카드를 이용하고 있다. SD 메모리 카드는 일반적으로 플래시 메모리를 기반으로 사용자 데이터를 저장한 후 PC에 데이터를 복사하는 형태로 사용되고 있다. 본 논문에서는 플래시 메모리에 데이터를 저장하는 방식이 아닌, 네트워크를 통하여 사진 및 영상 데이터 저장을 할 수 있는 SD 메모리 카드를 제안한다. SD Slave IP를 통해서 들어오는 데이터 및 메모리 주소 값들을 플래시 메모리로 보내지 않고 네트워크 서버에 전달하여, 실시간으로 SD 메모리에 저장할 데이터를 안전하고 편리하게 저장할 수 있다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.238-243
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• 2003

As there are many advantages on underground caverns, such as safety and operation, they can also be used for gas storage purpose. When liquefied gas is stored underground, the cryogenic temperature of the gas will affect the stability of the storage cavern. In order to store the liquefied gas successfully, it is essential to estimate the exact temperature distribution of the rock mass around the cavern. In this study, an analytic solution and a conceptual model that can estimate three-dimensional temperature distribution around the storage cavern are suggested. When calculating the heat transfer within a solid, it is likely to consider the solid as the intersection of two or more infinite or semi-infinite geometries. Therefore heat transfer solution for the solid is expressed by the product of the dimensionless temperatures of the geometries, which are used to form the combined solid. Based on the multi-dimensional transient heat transfer theory, the analytic solution is successfully derived by assuming the cavern shape to be of simplified geometry. Also, a conceptual model is developed by using the analytic solution of this study. By performing numerical experiments of this multi-dimensional model, the temperature distribution of the analytic solution is compared with that of numerical analysis and theoretical solutions.

• Tribology and Lubricants
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• 제30권5호
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• pp.284-290
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• 2014

The influence of round embossed surface on slider bearing characteristics and its load carrying capacity is discussed for thin film effect of embossed slider bearing. For the numerical computation of lubrication parameters such as pressure, load capacity and shear stress that are normalized and a Reynolds equation is used for the analysis of embossed slider bearing characteristics. For this purpose, the finite difference method of central difference scheme is used in this study. In a slider bearing with embossed form, several simulation parameters such as pressure, load capacity and shear stress of the bearing can be obtained according to independent parameters such as the slope of the slider bearing and number of embossing in the upper slider. Also this results can be summarized and be stored in sequential data file for latter analysis. After all, their distribution of the pressure and shear stress parameters can be displayed and be analyzed easily by using the developed program with matlab GUI technique. The independent parameters such as a number of embossing and a slope of the embossed surface slider are used for discussing simulation parameters of pressure distribution, shear stress and load carrying capacity of the round embossing. These study results reported in this paper should be applied to the other shaped slider bearing with a rectangular embossed surface or rectangular waved surface.

• 전기학회논문지
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• 제58권1호
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• pp.126-131
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• 2009

This study was carried out for the reliability of PD(Partial Discharge) pattern recognition. For the pattern recognition, the database for PD was established by use of self-designed insulation defects which occur and were mostly critical in GIS(Gas Insulated Switchgear). The acquired database was analyzed to distinguish patterns by means of PRPD(Phase Resolved Partial Discharge) method and stored to the form with to unite the average amplitude of PD pulse and the number of PD pulse as the input data of neural network. In order to prove the performance of genetic algorithm combined with neural network, the neural networks with trial-and-error method and the neural network with genetic algorithm were trained by same training data and compared to the results of their pattern recognition rate. As a result, the recognition success rate of defects was 93.2% and the neural network train process by use of trial-and-error method was very time consuming. The recognition success rate of defects, on the other hand, was 100% by applying the genetic algorithm at neural network and it took a relatively short time to find the best solution of parameters for optimization. Especially, it could be possible that the scrupulous parameters were obtained by genetic algorithm.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2002년도 추계정기학술대회
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• pp.491-501
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• 2002

Case-based reasoning is emerging as a leading methodology for the application of artificial intelligence. CBR is a reasoning methodology that exploits similar experienced solutions, in the form of past cases, to solve new problems. Hybrid model achieves some convergence of the wide proliferation of credit evaluation modeling. As a result, Hybrid model showed that proposed methodology classify more accurately than any of techniques individually do. It is confirmed that proposed methodology predicts significantly better than individual techniques and the other combining methodologies. The objective of the proposed approach is to determines a set of weighting values that can best formalize the match between the input case and the previously stored cases and integrates fuzzy sit concepts into the case indexing and retrieval process. The GA is used to search for the best set of weighting values that are able to promote the association consistency among the cases. The fitness value in this study is defined as the number of old cases whose solutions match the input cases solution. In order to obtain the fitness value, many procedures have to be executed beforehand. Also this study tries to transform financial values into category ones using fuzzy logic approach fur performance of credit evaluation. Fuzzy set theory allows numerical features to be converted into fuzzy terms to simplify the matching process, and allows greater flexibility in the retrieval of candidate cases. Our proposed model is to apply an intelligent system for bankruptcy prediction.

• Journal of Computing Science and Engineering
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• 제4권3호
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• pp.207-224
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• 2010

This paper presents a compression scheme for mesh geometry, which is suitable for mobile graphics. The main focus is to enable real-time decoding of compressed vertex positions while providing reasonable compression ratios. Our scheme is based on local quantization of vertex positions with mesh partitioning. To prevent visual seams along the partitioning boundaries, we constrain the locally quantized cells of all mesh partitions to have the same size and aligned local axes. We propose a mesh partitioning algorithm to minimize the size of locally quantized cells, which relates to the distortion of a restored mesh. Vertex coordinates are stored in main memory and transmitted to graphics hardware for rendering in the quantized form, saving memory space and system bus bandwidth. Decoding operation is combined with model geometry transformation, and the only overhead to restore vertex positions is one matrix multiplication for each mesh partition. In our experiments, a 32-bit floating point vertex coordinate is quantized into an 8-bit integer, which is the smallest data size supported in a mobile graphics library. With this setting, the distortions of the restored meshes are comparable to 11-bit global quantization of vertex coordinates. We also apply the proposed approach to compression of vertex attributes, such as vertex normals and texture coordinates, and show that gains similar to vertex geometry can be obtained through local quantization with mesh partitioning.

• 한국도서관정보학회지
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• 제35권3호
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• pp.119-138
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• 2004

디지털보존은 디지털정보를 장기적으로 보유하여 이용자로 하여금 지속적으로 접근이 가능하도록 하는 일련의 행위를 말한다. 이를 위해서는 기술적인 문제를 포함하여 정책적인 문제, 기관의 역할, 법적 및 저작권 문제, 메타데이터 전략 등 여러 가지 복잡한 세부 과제들을 해결하여야 한다. 본 논문은 이 중에서 디지털보존과 관련된 기술적인 문제를 2가지로 구분하여 정리하고 있다. 먼저, 디지털보존의 기본적인 개념을 형성하는 요소인 디지털객체, 디지털객체의 수명주기, 아카이빙 워크플로우를 시스템의 입장에서 정의하였다. 둘째, 기술보존, 에물레이션, 파일재생, 포맷전환, 캡슐화 등 디지털보존에 사용되는 주요한 보존처리 기술을 비교 분석하였다.