• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1555-1562
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• 2023

Natural circulation phenomena have been nowadays largely revisited aiming to investigate the performances of passive safety systems in carrying-out heat removal under accidental conditions. For this purpose, assessment studies using CFD (Computational Fluid Dynamics) and also 3D thermal-hydraulic system codes are considered at different levels of the design and safety demonstration issues. However, these tools have not being extensively validated for specific natural circulation flow regimes involving flow mixing, temperature stratification, flow recirculation and instabilities. In the present study, an experimental test case based on a small-scale pool test rig experiment performed by Korea Atomic Energy Research Institute, is considered for code-to-code and code-to-experimental data comparison. The test simulation is carried out using the FLUENT and the 3D thermal-hydraulic system CATHARE-2 codes. The objective is to evaluate and compare their prediction capabilities with respect to the test conditions of the experiment. It was observed that, notwithstanding their numerical and modelling differences, similar agreement results are obtained. Nevertheless, additional investigations efforts are still needed for a better representation of the considered phenomena.

• 정보처리학회논문지D
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• 제16D권2호
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• pp.213-222
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• 2009

추적성 개념은 모델 중심의 개발에서만이 아니라 테스트를 위하여 매우 중요한 요소이다. 어떤 기능을 중심으로 높은 추상수준에서부터 낮은 수준의 프로그램까지 수직적인 추적은 모델로부터 테스트와 디버깅 단계에 이르기까지 시스템을 잘 관리할 수 있게 한다. 또한 테스트 단계에서 발견한 결함에 대한 오류를 추적할 때 발생하는 단계별 추상 수준의 분리를 추적가능성으로 극복하게 한다. 이 논문에서는 XML을 기반으로 모델과 시험사례 그리고 소스코드를 수직적으로 추적하여 더욱 엄격한 테스트가 되는 방법을 제안한다. 실험을 통하여 추적이란 개념이 어떻게 작동하고 오류 부분을 찾아내는지 보이며 구체적인 사례를 이용하여 방법을 소개한다.

• 정보과학회 논문지
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• 제43권9호
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• pp.953-962
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• 2016

모델 기반 테스팅은 시스템의 행위를 표현하는 모델을 시스템 명세로 활용하여 테스트를 수행하는 기술이다. 자동차, 국방/항공, 의료, 철도, 원자력과 같은 산업 도메인에서는 소프트웨어의 품질 향상을 위해 모델 기반 테스팅과 코드 커버리지 기반 테스팅을 요구하고 있다. 모델 기반 테스팅과 코드 커버리지 기반 테스팅이 모두 요구됨에도 모델과 소스 코드 간의 추상화 수준 차이로 인해 모델 기반 테스팅만으로 높은 코드 커버리지를 달성하는 것이 어려워 모델 기반 테스팅과 코드 커버리지 기반 테스팅이 별도로 수행되어져 왔다. 본 연구에서는 기존의 모델 기반 테스팅의 한계점을 개선하기 위하여 모델 기반 테스팅에서 테스트 모델로서 이용되는 대표적인 모델링 방법 중 하나인 프로토콜 상태 머신을 테스트 모델로서 이용하여 효과적으로 코드 커버리지를 향상시키는 상태 머신 변환 방법을 제안한다. 또한 본 연구에서는 두 시스템을 대상으로 한 사례 연구를 수행하여 제안 방법의 효과성을 분석하였다.

• 한국안전학회지
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• 제27권6호
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• pp.14-19
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• 2012

The Helium cooled ceramic reflector(HCCR) test blanket module(TBM) has been designed and developed to participate the ITER(International Thermonuclear Experimental Reactor) test blanket program in Korea. The TBM was one of the main objectives for developing ITER for proving the tritium self-sufficiency and the heat transfers to produce the electricity with the breeding blanket concept. Among the TBM components, the first wall(FW) was the most important component in safety since it was directly faced a high level of a heat and fast neutrons from the plasma side and could protect the others components inside TBM. In this paper, the FW has been designed through the thermo-mechanical analysis considering ITER operation conditions. With the developed simple models, the stress limit analysis based on RCC-MR code which is the nuclear power plant design codes in France was evaluated for the allowable design criteria. The results showed that the designed FW model satisfied $1.5S_m$ or $3S_m$ of the allowable stress($S_m$) in RCC-MR code at the maximum stress region in the FW.

• 한국시뮬레이션학회논문지
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• 제20권4호
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• pp.41-48
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• 2011

개발 기능에 대한 단위시험 모듈을 구현할 경우 도메인 구현부와 시험 구현부의 종속성이 높기 때문에 단위시험 모듈의 재사용이 어렵다. 특히, 동일한 구조나 기반 프레임워크를 재사용하는 시스템의 경우 구성 소프트웨어의 내부 인터페이스를 위한 단위시험 모듈의 중복이 불가피하며, 통합 시험 코드는 해당 모듈 간 연동 인터페이스 구현에 종속되기 때문에 각 모듈의 개발 일정에 따라 단위시험 수행이 제한될 수 있다. 이러한 문제를 해결하기 위해서 TDD 기법 중 하나인 모형 객체(Mock Objects) 패턴을 이용한 단위시험 방법이 제안되었다. 이 방법은 도메인 모듈과 시험 모듈을 분리할 수 있도록 도메인 모듈을 대리하는 모형 객체를 생성하고, 해당 모형 객체를 시험 모듈과 통합함으로써 단위시험 모듈의 구현을 용이하게 한다. 본 논문은 HLA 시뮬레이션 시스템 개발에 참여하는 Federate의 Federation 통합 및 연동 시험을 용이하게 하기 위해서 모형 객체를 적용한 모형 Federate를 설계하고, 모형 Federate의 구성 모듈을 위한 테스트 프레임워크를 제안한다. 제안 프레임워크는 RTI 서비스를 위한 시험 함수를 제공하며, 해당 함수들은 xUnit 패턴에 의해 자동화 된다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.250-257
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• 2002

Pseudo dynamic test is an on-line computer control method to achieve the realism of shaking table test with the economy and versatility of the conventional quasi-static approach Pseudo dynamic tests of six full-size RC bridge piers have been carried out to investigate their seismic performance. For the purpose of precise evaluation, the experimental investigation was conducted to study the seismic performance of the real size specimen, which is constructed for highway bridge piers in Korean peninsula. Since it is believed that Korea belongs to the moderate seismicity region, five test specimens were designed in accordance with limited ductility design concept. Another one test specimen was nonseismically designed according to a conventional code. Important test parameters were transverse reinforcement and lap splicing. Lap splicing was frequently used in the plastic hinge region of many bridge columns. Furthermore, the seismic design code is not present about lap splice in Korean Roadway Bridge Design Code. The results show that specimens designed according to the limited ductility design concept exhibit higher seismic resistance. Specimens with longitudinal steel lap splice in the plastic hinge region appeared to significantly fail at low ductility level.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.885-890
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• 2002

Pseudo dynamic test is an on-line computer control method to achieve the realism of shaking table test with the economy and versatility of the conventional quasi-static approach. Pseudo dynamic tests of four full-size RC bridge piers have been carried out to investigate their seismic performance. For the purpose of precise evaluation, the experimental investigation was conducted to study the seismic performance of the real size specimen, which is constructed for highway bridge piers in Korean peninsula. Since it is believed that Korea belongs to the moderate seismicity region, three test specimens were designed in accordance with limited ductility design concept. Another one test specimen was nonseismically designed according to a conventional code. Important test parameters were transverse reinforcement and lap splicing. Lap splicing was frequently used in the plastic hinge region of many bridge columns. Furthermore, the seismic design code is not present about lap splice in Korean Roadway Bridge Design Code. The results show that specimens designed according to the limited ductility design concept exhibit higher seismic resistance. Specimens with longitudinal steel lap splice in the plastic hinge region appeared to significantly fail at low ductility level.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.74-80
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• 2005

It becomes necessary for engine manufactures to verify whether lots of engines on test bed during shop test are in compliance with NOx Technical Code for marine diesel engines more efficiently on the basis of engine group test concept which contains parent engine and member engines since all the engines are not needed to take NOx measurement. In addition, it becomes more obliged to consider parameters which affect NOx emission level and describe these parameters in NOx technical file as engine information and settings to define engine operation range with tolerance to make sure the engines are still in compliance with NOx emission limit on board after shop test. During preparation of engine group test for 4-stroke marine diesel engines, we evaluated NOx emission value under different engine operating conditions and found that there are certain parameters, for example, Charge air temperature and Max. cylinder pressure which have influence on NOx emission level. The NOx emission shall be satisfied with NOx technical code by means of controlling such parameters.

• ETRI Journal
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• 제37권1호
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• pp.54-60
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• 2015

The use of serial concatenated codes is an effective technique for alleviating the error floor phenomenon of low-density parity-check (LDPC) codes. An enhanced sum-product algorithm (SPA) for LDPC codes, which is suitable for serial concatenated codes, is proposed in this paper. The proposed algorithm minimizes the number of errors by using the failed check nodes (FCNs) in LDPC decoding. Hence, the error-correcting capability of the serial concatenated code can be improved. The number of FCNs is simply obtained by the syndrome test, which is performed during the SPA. Hence, the decoding procedure of the proposed algorithm is similar to that of the conventional algorithm. The error performance of the proposed algorithm is analyzed and compared with that of the conventional algorithm. As a result, a gain of 1.4 dB can be obtained by the proposed algorithm at a bit error rate of $10^{-8}$. In addition, the error performance of the proposed algorithm with just 30 iterations is shown to be superior to that of the conventional algorithm with 100 iterations.

• 전자공학회논문지C
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• 제34C권10호
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• pp.43-50
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• 1997

In this paper, we present a method that can recognize face images by use of a sparse population code that is a learning model about a receptive fields of the simple cells in the primary visual cortex. Twenty front-view facial images form twenty persons were used for the training process, and 200 varied facial images, 20 per person, were used for test. The correct recognition rate was 100% for only the front-view test facial images, which include the images either with spectacles or of various expressions, while it was 90% in average for the total input images that include rotated faces. We analyzed the effect of nonlinear functon that determine the sparseness, and compared recognition rate using the sparese population code with that using eigenvectors (eigenfaces), which is compact code that makes contrast with the sparse population code.