• 한국CDE학회논문집
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• 제8권1호
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• pp.10-18
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• 2003

FEM (Finite Element Method) is a fundamental numerical analysis technique in wide spread use in engineering application. As the solving time occupies small portion of entire FEM analysis time because of development of hardware, the relative lime to the whole analysis time to make mesh mod-els is growing. In particular, in the case of stiffeners such as features attached to plate in ship structure, the line constraints are imposed on mesh model together with other constraints such as holes. To auto-matically generate two dimensional quadrilateral mesh with the line constraints, an algorithm is pro-posed based on the constrained Delaunay triangulation and Q-Morph algorithm in which the line constraints are not considered. The performance of the proposed algorithm is evaluated. And some numerical results of our proposed algorithm ate presented.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권2호
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• pp.119-127
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• 2005

제품계열분석(product line analysis)은 제품계열자산(product line asset)을 개발하기에 앞서, 제품계열 내에 속한 제품들의 다양한 요구사항과 이들 간의 관계 및 제약사항을 분석하는 활동을 말한다. 지금까지 특성모델링(feature modeling)이라 불리는 특성 지향의 공통성과 가변성 분석은 제품계열분석의 핵심적인 부분으로 간주되어 왔다. 비록 공통성과 가변성 분석이 제품계열분석의 핵심적인 요소이지만, 이것만으로는 재사용가능하고 적응성이 뛰어난 제품계열자산(예, 아키텍처와 컴포넌트) 개발에 한계가 있다. 특성간의 의존성 및 특성결합시간도 제품계열자산 개발에 중대한 영향을 미치는 요소이다. 따라서 본 논문에서는 기존에 공통성과 가변성 관점에서 제품계열을 분석한 결과인 특성모델(feature model)을 세 가지의 특성 측면(즉, 제품특성의 공통성과 가변성, 특성간의 의존성, 그리고 특성결합시간)으로 확장한 특성지향의 제품계열분석 모델을 제안한다. 특히, 세 가지 측면의 일관성을 검증하기 위해서, 특성 지향의 제품계열분석 모델을 정형적으로 정의하고, 모델의 일관성을 검사하는 규칙을 제공한다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.1025-1032
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• 2006

The PVRC(Pressure Vessel Research Council) damping is for the response spectrum analysis of the piping system. In this study, the possibility to apply it to the time history analysis is evaluated to reduce the higher conservatism for the structural integrity. The evaluation was performed for the surge line connecting the pressurizer to the hot-leg, and the whole mode includes the RCS and the building structures with the surge line. The analyses were performed using ANSYS code. The first modal analysis shows the modes of the surge line are isolated from those of the other structures. The composite modal damping was calculated with PVRC damping for the surge line and RG 1.60 damping for the other structures by using ANSYS routines. Of the calculated composite modal damping values, the composite modal damping values related to the modes of the surge line were replaced with the PVRC damping values with respect to its frequencies. With this replacement, the composite modal damping values of the other structures were not changed. Based on this decouple characteristics, the time history analyses for the seismic events with PVRC damping for the surge line were performed. And the results show the resultant loads can be reduced by up to 50%.

• Journal of Nutrition and Health
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• 제31권8호
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• pp.1347-1354
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• 1998

The purposes of this study were to : (a) anlayze wating time, service rate, arrival rate, and coustomer expectations/satisfaction in cafeteria business foodservices and (b) identify the differences in those factors between foodservices by menu managmenet systems. The samples were two business foodservices operated by contract management in Seoul. The queue, laptime , service rate, and arrival rate were measured at each foodservice by stopwatch observation. The menu type, delivery system, number of meals served , servide time, and turnover rate of each foodservic was investigated. Questionnaires were developed to survey customer expectations and satisfaction. Satistical data analysis was completed using the SAS package programs for descriptive analysis and t-test. The mean waiting time of island type dafeteria system with separte set -menu was shorter than that of the other. In both foodservices, arrival rates were not significantly different from one another , but sevice rates were significnatly high in dafeteria menu systems. The peak time of the queue was found out at combination set menu line. The separate set menu line had a higher servide rate than the combination set menu line. The mean waiting time of the island type cafeteria line was shorter than that of the straifth type . At the straight type dafeterial line, both arrival rate and service rate were higher than those of island-type. The results of this study suggested that a separate set-menu would be more desirable than a combination set-menu in case of providing set menu with cafeteria menu.

• 동력기계공학회지
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• 제3권1호
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• pp.74-79
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• 1999

This paper describes formulation for algorithm of time historical response analysis of vibration for straight-line structure. This method is derived from a combination of the transfer stiffness coefficient method and the Newmark method. And this present method improves the computational accuracy of the transient vibration response analysis remarkably owing to several advantages of the transfer stiffness coefficient method. We regarded the structure as a lumped mass system here. The analysis algorithm for the time historical response was formulated for the straight-line structure containing crooked, tree type system. The validity of the present method compared with the transfer matrix method and the Finite Element Method for transient vibration analysis is demonstrated through the numerical computations.

• 한국항해학회지
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• 제22권1호
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• pp.15-22
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• 1998

In this paper, discontinuity parts in microstrip line with $\lambda$/4 open stub and one in crank type have been anlayzed by using FDTD(Finite-Difference Time-Domain) analysis method. The noise components, in this case, are occred at the discontinuites of the given microstrip lines, the complex poles were extracted by the analysis using GPOF (Generalized Pencil-of Function) method from electric field of time domain. It has, then, been found that the noise level and the noise frequency components included in signal could be derived.

• 전기학회논문지
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• 제57권2호
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• pp.268-275
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• 2008

In this paper, we introduce a new method for detecting and estimating faults on a power line using the time-frequency domain reflectometry system. The system rests upon time-frequency signal analysis and uses a chirp signal which is multiplied by Gaussian envelope. The chirp signal is used as a reference signal, and we can get the reflected signal from a fault on a wire. To detect and estimate faults, we analyze the reflected signal by Wigner time-frequency distribution function and normalized time-frequency cross correlation function. In this paper we design an optimal reference signal for power line and implement a system for estimating fault distance on a power line with the TFDR implemented by PXI equipments. This approach is verified by some experiments with HIV 2.25mm power lines.

• 한국해양공학회지
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• 제30권3호
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• pp.161-168
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• 2016

This paper presents a methodology through which the time series of the dynamic response of mooring line tension can be predicted without relying on a time-consuming nonlinear time-domain analysis. The mooring line tension for the target short-term sea states was predicted using a Hammerstein-Wiener model, a popular system identification scheme, based upon the pre-calculated motion-tension time history data for some selected short-term sea states that do not overlap with the targeted ones. The obtained mooring line tension was further processed, and a fatigue damage comparison was made between the predicted and calculated values. The results showed that the predicted time series of the mooring line tension matched the calculated one fairly well. Thus, it is expected that the methodology may be employed to enhance the efficiency of mooring line tension analysis.

• 한국전자파학회논문지
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• 제18권11호
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• pp.1309-1317
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• 2007

본 논문은 낙뢰에 의해 전송 선로에 유기되는 유도뢰 전압을 해석하고 낙뢰 위치 및 선로 길이에 따른 유도뢰 전압의 크기, 파두장, 파미장 등에 대한 낙뢰 파라미터 변화를 분석하였다. 분석한 결과를 확인하기 위해 실제 통신 선로를 대상으로 유도뢰 전압을 측정하였다. 선로 길이가 길어짐에 따라 그리고 낙뢰 위치가 선로와 멀어짐에 따라 파두장, 파미장이 증가하는 경향을 확인하였다. 전체 선로 길이보다는 가공 선로 길이가 상대적으로 유도 전압 크기에 영향을 끼침을 확인하였다.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.402-409
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• 2019

When a loss of coolant accident (LOCA) occurs in a nuclear power plant, accident scenarios which can prevent core damage are defined based on break size. Current probabilistic safety assessment evaluates that core damage can be prevented under small-break LOCA (SBLOCA) and steam generator tube rupture (SGTR) with rapid cool down (RCD) strategy when all safety injection systems are unavailable. However, previous research has pointed out a limitation of RCD in terms of initiation time. Therefore, RCD success criteria estimation based on allowable coping time under a SBLOCA or SGTR when all safety injection systems are unavailable was performed based on time-line and thermal-hydraulic analyses. The time line analysis assumed a single emergency operating procedure flow, and the thermal hydraulic analysis utilized MARS-KS code with variables of break size, cooling rate, and operator allowable time. Results show while RCD is possible under SGTR, it is impossible under SBLOCA at the APR1400's current cooling rate limitation of 55 K/hr. A success criteria map for RCD under SBLOCA is suggested without cooling rate limitation.