• Journal of Power Electronics
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• 제13권2호
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• pp.275-286
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• 2013

An explicit frequency-domain circuit model for the conventional coupled magnetic resonance system (CMRS) is newly proposed in this paper. Detail circuit parameters such as the leakage inductances, magnetizing inductances, turn-ratios, internal coil resistances, and source/load resistances are explicitly included in the model. Accurate overall system efficiency, DC gain, and key design parameters are deduced from the model in closed form equations, which were not available in previous works. It has been found that the CMRS can be simply described by an equivalent voltage source, resistances, and ideal transformers when it is resonated to a specified frequency in the steady state. It has been identified that the voltage gain of the CMRS was saturated to a specific value although the source side or the load side coils were strongly coupled. The phase differences between adjacent coils were ${\pi}/2$, which should be considered for the EMF cancellations. The analysis results were verified by simulations and experiments. A detailed circuit-parameter-based model was verified by experiments for 500 kHz by using a new experimental kit with a class-E inverter. The experiments showed a transfer of 1.38 W and a 40 % coil to coil efficiency.

• 천문학회보
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• 제40권1호
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• pp.67.1-67.1
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• 2015

In the past two decades, diverse methods and computer codes for reconstruction of coronal magnetic fields have been developed. Some of them can reproduce a known analytic solution quite well when the magnetic field vector is fully specified by the known solution at the domain boundaries. In practical problems, however, we do not know the boundary conditions in the computational domain except the photospheric boundary, where vector magnetogram data are provided. We have developed a new, simple variational method employing vector potentials. We have tested the computational code based on this method for problems with known solutions and those with actual photospheric data. When solutions are fully given at all boundaries, the accuracy of our method is almost comparable to best performing methods in the market. When magnetic field vectors are only given at the photospheric boundary, our method excels other methods in "figures of merit" devised by Schrijver et al. (2006). Our method is expected to contribute to the real time monitoring of the sun required for future space weather prediction.

• 한국전자거래학회지
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• 제11권3호
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• pp.35-51
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• 2006

정보의 시각화는 정보의 직관적 이해를 위해 중요한 역할을 하며, 다양한 응용영역에서 해당 환경의 특징에 맞추어 활용되고 있다. 본 논문에서는 전자상거래에서 상품을 효과적으로 검색하여 보여주기 위해서는 기존의 방식이 아닌 상품 정보의 특색에 맞는 검색 방식과 시각화 기법이 필요하다고 판단하여, 기존의 MapNet이나 클러스터맵 등의 기술을 반영한 상품 검색 비주얼라이제이션 기법을 소개한다. 상품 카테고리 검색과 속성 검색의 분리를 통해 검색조건에 명확한 시맨틱 부여를 가능하게 하고, 사용자에게 검색 결과를 평가하고 재검색을 수행할 수 있게 한다. 결과 평가는 원하는 결과를 얻지 못했을 경우 사용자가 질의어를 재작성하여 최적의 결과를 찾을 수 있게 한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.488-491
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• 1995

The paper presents a new global maximum search method for multimodal unknown functions of two variables. The search method is composed of two stages and sequentially samples the candidate point in a subdomain selected using a priority function in each stage. The search domain is auto-similarly divided into triangular subdomains, or cells, during the search process. A measure of accuracy of local maximum search is introduced to check if a local search has converged to a specified accuracy or the maximum of a local peak cannot be the global maximum. A criterion for switching from the first to the second stage, is proposed using a ratio of the observed peak width to the largest cell in the domain. By numerical simulations, the required number of trials is evaluated for some function models with different peak parameters, and the switching criterion is optimally determined. The results show that the proposed method obtains global maximum points with certainty and saves largely computation time even for functions with extremely steep peaks.

• 인터넷정보학회논문지
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• 제10권4호
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• pp.139-149
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• 2009

본 논문에서는 데이터 보호 규정에 관련된 요구사항들이나 규칙들이 소프트웨어에 잘 표현되어 있는지를 검증하기 위하여 도메인 고유의 언어인 DSML(Domain Specific Modeling Language)을 사용해 정책을 정규화 혹은 계산적 표현에 관련된 솔루션을 제시하고 있다. 모든 정책들은 공식적으로 프롤로그( Prolog) 언어 기반으로 표현된 후 DSML에 통합되며 정책검증은 요구사항 준수가 언제 평가되어야 하는지에 따라 정적 정책검증과 동적 정책검증의 두가지 정책이 존재한다.

• 로봇학회논문지
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• 제10권4호
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• pp.179-185
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• 2015

The versatility of a human hand is what the researchers eager to mimic. As one of the attempt, the redundant degree of freedom in the human hand is considered. However, in the force domain the redundant joint causes a control issue. To solve this problem, the force control method for a redundant robotic hand which is similar to the human is proposed. First, the redundancy of the human hand is analyzed. Then, to resolve the redundancy in force domain, the artificial minimum energy point is specified and the restoring force is used to control the configuration of the finger other than the force in a null space. Finally, the method is verified experimentally with a commercial robot hand, called Allegro Hand with a force/torque sensor.

• 한국대기환경학회지
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• 제16권6호
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• pp.641-652
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• 2000

The effect of block arrangement has been investigated on the particle deposition in the specified collecting cell of two-stage electrostatic precipitator by numerical analysis. Recirculation zone existed at the downstream of the block in the collecting cell, and the particles entering the recirculation zone were deposited on the collecting plate. Particle trajectory and deposition had considerably different phenomenon according to electrostatic and inertial effect, which depended on inlet mean velocity, electrostatic number, and particle diameter in the collecting cell. The total collection efficiency reached a minimum value through an interaction of electrostatic and inertial effect. In the computational domain, total collection efficiency for the case of two blocks in the computational domain was more than that of one block at the relative small electrostatic number. However as the block distance and inertial effect increased, the difference between the collection efficiency of two cases decreased. In the range of relatively small particle size total collection efficiency was always superior to particle collection efficiency that was predicted by Deutsch equation.

• Wind and Structures
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• 제21권5호
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• pp.489-503
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• 2015

This paper surveys and complements contributions by the National Institute of Standards and Technology to techniques ensuring that the wind tunnel procedure for the design of high-rise structures is based on sound methods and allows unambiguous inter-laboratory comparisons. Developments that enabled substantial advances in these techniques include: Instrumentation for simultaneously measuring pressures at multiple taps; time-domain analysis methods for estimating directional dynamic effects; creation of large simulated extreme directional wind speed data sets; non-parametric methods for estimating mean recurrence intervals (MRIs) of Demand-to-Capacity Indexes (DCIs); and member sizing based on peak DCIs with specified MRIs. To implement these advances changes are needed in the traditional division of tasks between wind and structural engineers. Wind engineers should provide large sets of directional wind speeds, pressure coefficient time series, and estimates of uncertainties in wind speeds and pressure coefficients. Structural engineers should perform the dynamic analyses, estimates of MRIs of wind effects, sensitivity studies, and iterative sizing of structural members. The procedure is transparent, eliminates guesswork inherent in frequency domain methods and due to the lack of pressure measurements, and enables structural engineers to be in full control of the structural design for wind.

• 한국정보시스템학회지:정보시스템연구
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• 제8권1호
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• pp.27-44
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• 1999

Case-Based Reasoning(CBR) offers a new approach for developing knowledge based systems. CBR has several research issues which can be divided into two categories : (1) static issues and (2) dynamic issues. The static issues are related to case representation scheme and case data model, that is, focus on casebase which is a repository of cases. The dynamic issues, on the other hand, are related to case retrieval procedure and problem solving process, i.e. case adaptation phase. This research is forcused on retrieval procedure Traditional query processing accepts precisely specified queries and only provides exact answers, thus requiring users to fully understand the problem domain and the casebase schema, but returning limited or even null information if the exact answer is not available. To remedy such a restriction, extending the classical notion of query answering to approximate query answering(AQA) has been explored. AQA can be achieved by neighborhood query answering or associative query answering. In this paper, neighborhood query answering technique is used for AQA. To reinforce the CBR process, a new retrieval procedure(cooperative CBR) using neighborhood query answering is proposed. An neighborhood query answering relaxes a query scope to enlarge the search range, or relaxes an answer scope to include additional information. Computer Aided Process Planning(CAPP) is selected as cooperative CBR application domain for test. CAPP is an essential key for achieving CIM. It is the bridge between CAD and CAM and translates the design information into manufacturing instructions. As a result of the test, it is approved that the problem solving ability of cooperative CBR is improved by relaxation technique.

• 한국전자파학회논문지
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• 제12권7호
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• pp.1139-1146
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• 2001

일차원 매질에 대한 역산란법을 이용하여 테이퍼형 임피던스 정합선로를 설계한다. 역산란법으로 유전율 분포를 추정하는 과정에서 오타를 줄이기 위하여 위상 보정인자(PCF: Phase Compensation Factor)를 도입한다. 설계하고자 하는 정합선로와 동일한 반사특성을 갖는 가상(virtual) 일차원 유전체의 유전율 분포를 추정하여 정합선로를 합성한다. 이 설계법은 등가회로에 대한 회로망 이론을 적용하지 않고 임의의 대역 특성을 갖는 정합선로를 설계할 수 있다. 주파수 영역의 반사계수를 사용함으로써 시간 영역의 반사계수를 사용하는 설계법에서 필연적으로 나타나는 오차를 피할 수 있다.