• 대한기계학회논문집B
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• 제26권6호
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• pp.859-867
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• 2002

Radiative transfer in energy systems such as furnaces, combustors, boilers and high temperature machineries is a significant mode of heat transfer. Although there are many solution schemes suggested for analysis of radiative transfer in multi-dimensional systems, the applicabilities and accuracies of these schemes have not fully tested for nongray gases. Especially reference data for enclosures of non-orthogonal shapes are not yet enough. In this paper we present some precise radiative transfer solutions for a black walled 3-dimensional cylindrical system filled with nongray gases. The SNB(statistical narrow band) model and the ray-tracing method with the T$_{N}$ quadrature set are used for finding nongray solutions. Although the solution method used in this study is not suitable for engineering purposes, the resulting solutions are proved to be quite accurate and can be regarded as the exact solutions and the results presented in this paper can be used in developing various solution schemes fur radiative transfer by real gas mixtures.s.

• 한국시뮬레이션학회논문지
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• 제32권3호
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• pp.1-8
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• 2023

영상레이더(SAR)에서 인공표적에 대한 모델링은 주로 3차원 CAD(Computer Aided Design) 모델의 면(face) 및 모서리(edge)에서 반사되는 레이더 신호를 광선추적(ray-tracing) 방식으로 시뮬레이션하고 있고, 지구 표면의 클러터(clutter)에 대한 모델링은 영상레이더 이미지 자체에 대한 통계학적(statistical) 분석을 통해 분포(distribution) 특성이 유사한 종류들을 구분하는 방식을 사용하고 있다. 본 논문에서는 지상의 인공표적 및 지표면의 배경 클러터를 3차원 점구름(point cloud) 산란점(scatterer point) 모델로 만들고 두 개의 모델이 통합된 상황에서 계산적(computational)인 신호처리 과정을 통해 영상 레이더 이미지를 생성하였으며, 이것을 실제 차량탑재형 영상레이더 시스템의 스트립맵(stripmap) 이미지 생성 결과 및 전자기적(EM) 모델링 또는 통계학적 분포 모델을 사용하여 분석한 결과와 유사한 지 비교해 보았다. 모델링 대상은 지상의 인공표적인 교량(다리)을 선정 했는데, 그 이유는 교량의 경유 주변에 수면과 지면이 같이 존재하는 특성이 있고 또한 군사용 및 민간용 활용에서 모두 관심이 많은 표적이기 때문이다.

• 방송공학회논문지
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• 제5권2호
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• pp.273-280
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• 2000

건물 외부에 위치하는 송신기와 건물 내부에 위치하는 수신기 사이의 채널 특성을 분석하기 위해 전파 추적 기법을 기반으로 한 모의 실험을 수행하였다. 본 모의 실험에서는 건물 내에 29개의 수신기를 설치하고, 각 수신기에서의 수신 특성을 다중 경로를 통해 수신된 여러 개의 신호의 상호 간섭 패턴을 이용하여 분석하였다. 모의 실험 결과에서 수신기의 위치와 송신기의 위치 및 전파의 편파 특성에 따라 수신 특성이 다르게 나타났고, 상쇄 간섭으로 인해 창가 쪽에 위치한 수신기의 수신 파워가 건물 안 쪽에 위치한 수신기의 수신 파워보다 작게 나타나는 경우도 있었다. 본 논문에서는 채널 파라미터들, 즉 mean excess delay와 rms delay spread를 통해 송신기와 수신기간의 채널 특성 분석도 수행하였다.

• 대한기계학회논문집
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• 제17권12호
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• pp.2962-2969
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• 1993

Recently, a study on the mirror-like surface grinding of brittle materials is active and as branch of these study, new dressing method for superabrasive wheel, electrolytic inprocess dressing(Elid) was developed. Using Elid, the mirror-like surface of brittle material can be generated without polishing or lapping process. In the future, Elid grinding will take important place in industry. But so far the analysis on Elid grinding was not quantitative but qualitative. In this study, The purpose is the quantitative analysis on Elid grinding by computer simulation, For computer simulation, the mean and the variance of the abrasive distribution were measured by tracing of the grinding wheel with stylus in transverse direction in the case of respective dressing current condition. This measurement result in a density distribution of abrasive by mathematical formulation using statistical method. The prediction of the surface roughness in Elid grinding was based on this density distribution.

• 수산경영론집
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• 제13권1호
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• pp.47-61
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• 1982

This paper first makes a survey of fishing household economy which possess fishing boats under 10 gross Tons by a questionnaire, and makes a comparative study of major indicators of fishing household economy between Korea and Japan, and finally suggests some policies for the fisheries management. Major indicators are the status of fishery household members, number of fishing boats which possess, fisheries incomes, fishing household incomes, side business incomes of fishing household, disposal incomes, living expenses, sufficient degree of living cost, average propensity to consumption and so on. Some policies for improvement in fishing household incomes are suggested in the paper as follows: ⑴ Form a policy similar to a project aiming for increasing the income of fishermen so that the side business income will also increase. ⑵ The point of view in tracing origin of low productivity. ⑶ It has drawn up a plan to encourage saving after analyzing the cause of high propensity to consumption. ⑷ The paper is aimed to collect basic statistical materials for fisheries administration.

• 대한치과의사협회지
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• 제22권12호통권187호
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• pp.1043-1046
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• 1984

The clinical and statistical evaluation on the patients of maxillofacial deformities who were operated by author were analyzed after several month or years or se. Pre and post operative cephalometric radiographs of 45 orthognathic surgery patients were compared. The post operative radiographs had been taken at least 9 month to several years. Measurements were made between constructed hard tissue and soft tissue points located on each before and after film tracing. The items studied and evaluated are as follows: 1) Classification and divid of patients 2) Operation technic adopted by operator. 3) Motives of patients for operation and their untowards. 4) Self satisfication of patients after operation. 5) Post operative changes of soft and hard tissue. 6) Side action during and after operation.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.19-22
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• 2009

This thesis offers forecast & warning algorithm about the accessing networks though statistical sampling methods to prevent computer terrors. These networks are occurred among U-city network groups. The main characteristic of current computer attacks is avoiding well-known detection patterns by successive changes in spreading speeds and attacking codes. The improvement of attacking stills leads to a problem causing the defense-time delay and creates vicious cycle that tries to fix networks after damage. Proposed algorithm notices and warns the potential attacking areas through defecting previous attacking signs, analysing attaching results ed tracing attaching sources at the beginning of the attack.

• International Journal of Quality Innovation
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• 제1권1호
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• pp.64-74
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• 2000

This paper investigates the issue of performance testing on web browsing environments. Among the typical non-functional characteristics, index of link validity will be deeply explored. A framework to certify link correctness in web site is proposed. All possible navigation paths are first formulated to represent a usage model with the Markov chain property, which is then used to generate test script file statistically. With collecting any existing failure information followed by tracing these testing browsed paths, certification analysis may be performed by applying Markov chain theory. The certification result will yield some significant information such as: test coverage, reliability measure, confidence interval, etc. The proposed mechanism may provide not only completed but also systemic methodologies to find any linking errors and other web technologies errors. Besides, an actual practice of the proposed approach to a web-based system will be demonstrated quantitatively through a certification tool.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.996-1001
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• 2000

The sound transmission from the machine room where air-conditioner outdoor unit is located into the adjacent room is predicted and evaluated. The software package for statistical energy analysis(SEA) is utilized to determine the transmission losses of multi-layerd panels. To determine the noise level in the machine room, ray tracing method is adopted. The various sound transmission paths have been effectively identified and evaluated by the SEA tool.

• 한국음향학회지
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• 제18권2호
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• pp.32-39
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• 1999

본 논문에서는 2차원 구조물의 고주파수 대역 진동 해석을 위하여, 원형파를 기본으로 한 레이 추적 기법(RTM)의 특성에 관한 논의를 하였다. 발산되는 원형파를 묘사하는 레이튜브 개념을 사용하여, 연성경계에서 입사파, 전달파, 그리고 반사파가 경계조건을 만족하도록 관계식을 유도하였다. 제안된 레이 모델을 직렬 배열 연결 평판 구조물에 적응하였는데, 직렬로 배열된 2개의 연결된 평판, 3개 및 4개의 연결된 평판에 대한 해석 결과를 통계적 에너지 해석법(SEA) 및 파동 인텐시티 해석법(WIA)과 비교하여 보았다. 그 결과, SEA 보다 개선된 예측을 할 수 있으며, WIA와는 비슷한 예측 성능을 보임을 확인할 수 있었다. 또한, 제안된 RTM을 사용하면 진동 에너지와 진동 인텐시티의 대략적 공간 분포를 알 수 있는 장점이 있다. 제안된 RTM은 2차원 연성 구조물의 고주파수 진동 해석을 위한 유용한 기법으로써 쓰일 것으로 기대된다.