• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.145-146
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• 2006

The recent power systems are very complex and to model them completely is impractical for analysis of electromagnetic transient. Therefore areas outside the immediate area of interest must be represented by some form of Frequency Dependent Network Equivalent (FDNE). In this paper a method for developing Frequency Dependent Network Equivalent (FDNE) using Z-domain rational Function Fitting is presented and demonstrated. The FDNE is generated by Linearized Least Squares Fitting(LSF) of the frequency response of a Z-domain formulation. This Three-port FDNE have been applied to the test AC power system. The electromagnetic transient package PSCAD/EMTDC is used to assess the transient response of the Three-port FDNE developed under different condition. The study results have indicated the robustness and accuracy of Three-port FDNE for analisys of electromagnetic transient and harmonic assessment.

• Nuclear Engineering and Technology
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• 제33권6호
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• pp.626-637
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• 2001

A series of study on energy dependence in chemiluminescence dosimetry with sugar and sorbite produced in two different countries was carried out administering a dose of 5 Gy to the samples at six different mean photon energies of 30, 50, 80, 130, 662 and 1250 keV. The results revealed distinct energy dependence of chemiluminescence(CL) output of sugar and sorbite. Although the energy dependence, in general, could be fitted by a polynomial of (os E, with I being radiation energy, up to cubic term, we reached a conclusion that the adoption of a fitting function, $y_{R}$$^{=a}$.(1-e $^{-b.logE}$)$^{c}$ +d, deduced from theoretical energy response curve calculated as the ratio of the mass energy absorption of the samples of interest to the soft tissue is more reasonable and rational. Herecoefficients $y_{R}$ is CL intensity, and a, b, c and d are constants to be determined in the fitting process. Energy dependence of relative sensitivities of one sample to the other, discrepancy in sensitivities of the samples from the two countries, and prominent grain size effect in Sorbitol were also shown.shown.

• Journal of electromagnetic engineering and science
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• 제16권3호
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• pp.169-181
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• 2016

This work presents a new method for enhancing the performance of a dual band Planer Inverted-F Antenna (PIFA) and its lumped equivalent circuit formulation. The performance of a PIFA in terms of return loss, bandwidth, gain, and efficiency is improved with the addition of the proposed open stub in the radiating element of the PIFA without disturbing the operating resonance frequencies of the antenna. In specific cases, various simulated and fabricated PIFA models illustrate that the return loss, bandwidth, gain, and efficiency values of antennas with longer optimum open stub lengths can be enhanced up to 4.6 dB, 17%, 1.8 dBi, and 12.4% respectively, when compared with models that do not have open stubs. The proposed open stub is small and does not interfere with the surrounding active modules; therefore, this method is extremely attractive from a practical implementation point of view. The second presented work is a simple procedure for the development of a lumped equivalent circuit model of a dual band PIFA using the rational approximation of its frequency domain response. In this method, the PIFA's measured frequency response is approximated to a rational function using a vector fitting technique and then electrical circuit parameters are extracted from it. The measured results show good agreement with the electrical circuit results. A correlation study between circuit elements and physical open stub lengths in various antenna models is also discussed in detail; this information could be useful for the enhancement of the performance of a PIFA as well as for its systematic design. The computed radiated power obtained using the electrical model is in agreement with the radiated power results obtained through the full wave electromagnetic simulations of the antenna models. The presented approach offers the advantage of saving computation time for full wave EM simulations. In addition, the electrical circuit depicting almost perfect characteristics for return loss and radiated power can be shared with antenna users without sharing the actual antenna structure in cases involving confidentiality limitations.

• ETRI Journal
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• 제35권5호
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• pp.915-918
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• 2013

This work presents an accurate finite-difference time-domain (FDTD) dispersive modeling of concrete materials with different water/cement ratios in 50 MHz to 1 GHz. A quadratic complex rational function (QCRF) is employed for dispersive modeling of the relative permittivity of concrete materials. To improve the curve fitting of the QCRF model, the Newton iterative method is applied to determine a weighting factor. Numerical examples validate the accuracy of the proposed dispersive FDTD modeling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1434-1435
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• 2008

In this paper, we propose a method that applies Vector Fitting(VF) and Adaptive Frequency Sampling(ASF) technique to the equivalent circuit model for RF passive components. VF and ASF schemes are implemented to obtain the rational functions. S parameters of the equivalent circuit model is compared to those of EM simulation in case of the microstrip structure with coupled bandpass filter.

• International Journal of CAD/CAM
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• 제9권1호
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• pp.47-53
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• 2010

In this paper we propose a new type of splines-biquadratic submesh splines over hierarchical T-meshes. The biquadratic submesh splines are in rational form consisting of some biquadratic B-splines defined over tensor-product submeshes of a hierarchical T-mesh, where every submesh is around a cell in the crossing-vertex relationship graph of the T-mesh. We provide an effective algorithm to locate the valid tensor-product submeshes. A local refinement algorithm is presented and the application of submesh splines in surface fitting is provided.

• 패션비즈니스
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• 제10권6호
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• pp.63-78
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• 2006

The purpose of this research is to propose the scientific and rational establishment of research projects and directions for research by analyzing the research trends on clothing construction. The 689 papers in the field of clothing construction are selected among 5433 papers published within the recent ten years (1996-2005) in Journal of the Korean Home Economics Association, Journal of the Korean Society of Clothing and Textiles, Journal of the Korean society of costumes, Research Journal of the Costume Culture, Journal of the Korean Society of Clothing Industry and Journal of Fashion Business. The trend of researches on clothing construction is analyzed by classifying the topics by design, body type, pattern, size of apparel, fitting of clothing, protective clothing and functional clothing, and the others, and the results are as follows. The frequency order of the studies in the field of clothing construction is body type (32%) > pattern (24%) > size of apparel (13%) > protective clothing and functional clothing (10%) > the others (8%) > design-related clothing construction (6%) > fitting of clothing (4%) > sewing (3%). The major areas of research are body types, pattern, and sizes resulting from them. Most of researches are focused on women, and researches on men are relatively lacking. In addition to the deficiency of men-related research, Moreover, researches on characteristics of body types and on corresponding sizes of consumers in the target countries of export are necessary when the reality of Korean clothing and fashion industry that depends more on foreign demand than domestic demand is considered. For production of segmented and specialized results from clothing construction research, related tools such as CAD, 3D shape systems and dress form should be developed and utilized to contribute to precision of research results.

• 대한전자공학회논문지SP
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• 제37권3호
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• pp.17-30
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• 2000

본 논문에서는 NURBS (Non-Uniform Rational B-Splines) 곡면 근사에 기반하여 거리 데이터로부터 3차원 곡면 모델을 생성하는 기법을 제안한다 입력으로 이용되는 거리 데이터는 연결 정보가 알려지지 않고 정렬되지 않은 일반적인 3차원 점들의 집합으로 가정한다 제안하는 알고리듬은 초기 모델 추정, 계층적 모델 표현, NURBS 곡면 네트워크 생성의 3단계로 나뉘어진다 초기 모델 추정 단계에서는 K-평균 군집화 기법을 이용하여 다각형면과 삼각형으로 표현되는 근사 모델을 생성하고, 계층적 트리 구조를 이용하여 초기 모델을 표현한다. 계층적 트리 구조로 부터 생성된 사각형면 모델에 의하여 $G^1$ 연속인 NURBS 곡면 네트워크를 효율적으로 생성한다. 제안하는 알고리듬은 초기 모델의 계층적 그래프 해석을 통하여 곡면 네트워크 형성에 필요한 계산량을 감소시켰으며, 또한 정확한 NURBS 제어점 추정을 통하여 근사 오차를 감소시킨다. 모의 실험 결과 거리 데이터로 부터 초기 모델과 다양한 해상도의 NURBS 곡면 네트워크가 효과적으로 생성되었으며 생성된 NURBS 곡면 모델의 근사 오치는 무시할 수 있는 수준임이 관찰되었다.

• 복식
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• 제18권
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• pp.307-319
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• 1992

The Purpose of this study Gerber company AM-300 system of the automatic system of Producing the original form the automatic system of Producing the original form of "Jogori(a Korean Jacket)' and Grading by the usage of computers and find out its efficiency. In the result, the auther has found out the following facts and became confident on the facts; The AM-300 program of the automatic system enabled to produce the original form of 'Jogori' and Grading fitting in a short time and definately, and which indicated that the automatically producing system of the original form of 'Jorgori' and Granding is efficient. Even in the aspect of education, it has been acknowledged that there is necessity of using computers, the accumulation of techincs and technology based on traditions by cultivating professional designers, and computerization so that the composition of 'Hanbok' (Korean clothes) should be rational and scientific. In addition, advertisement and education on the traditionalism and superiority of 'Hanblk' are indispensable and absolutely necessary. Also, to succeed folk costumes rightly, the usage of computers is thought to be a way to effectiveness. So far in the study, only the automatic system of producing the original form of 'Jogori' and Grading through computers is emphasized on, however in the future, such an automatic system should be continuously supplemented, studied on and developed even in other various fields such as in pattern making, design, products planning, etc..

• 한국농공학회지
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• 제35권3호
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• pp.117-129
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• 1993

This study was conducted to get reasonable and abundant hydrological time series of monthly flows simulated by a best fitting stochastic simulation model for the establishment of rational design and the rationalization of management for agricultural hydraulic structures including reservoirs. Comparative analysis carried out for both statistical characteristics and synthetic monthly flows simulated by the multi-season first order Markov model based on Gamma distribution which is confirmed as good one in the first report of this study and by Harmonic synthetic model analyzed in this report for the six watersheds of Yeong San and Seom Jin river systems. 1.Arithmetic mean values of synthetic monthly flows simulated by Gamma distribution are much closer to the results of the observed data than those of Harmonic synthetic model in the applied watersheds. 2.In comparison with the coefficients of variation, index of fluctuation for monthly flows simulated by two kinds of synthetic models, those based on Gamma distribution are appeared closer to the observed data than those of Harmonic synthetic model both in Yeong San and Seom Jin river systems. 3.It was found that synthetic monthly flows based on Gamma distribution are considered to give better results than those of Harmonic synthetic model in the applied watersheds. 4.Continuation studies by comparison with other simulation techniques are to be desired for getting reasonable generation technique of synthetic monthly flows for the various river systems in Korea.