• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.73-79
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• 2003

The steam turbine efficiency is an important factor in power plant. Accurate evaluation of steam turbine performance is essential. However, it is not easy to evaluate the steam turbine performance due to its high temperature and high pressure circumstance. Therefore most steam turbine performance tests were conducted by air similarity test. This paper described a test program for air similarity test of steam turbine at Korea Aerospace Research Institute. A test facility has been designed and built to evaluate aerodynamic performance of turbines. The test facility consists of air supply system, single stage test section, power absorption system, instrumentation and auxiliary system. For evaluation of steam turbine performance, the test of single stage axial turbine air similarity performance was conducted and uncertainty analysis was performed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1149-1149
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• 2006

The leakage characteristic is an important factor in power plant. However, most of power plant have efficiency problem which is occurred leaking between high pressure steam turbine axle and stator. The labyrinth seal which is used between the main turbine axle and stator in the power plant. Because it is able to be non-contact seal and it is minimize clearance to decrease the leakage. But its actual system is too huge to experiment. Therefore, most steam turbine seal performance tests were conducted by air similarity test. This paper described a test facility and program for air similarity test of high pressure steam turbine seal. A test facility has been designed and built to evaluate leakage verification of labyrinth seal. The test facility consist of air compressor, anti-swirl labyrinth seal for 1/3 air similarity model, pressure transducer, air flow measure system, instrumentation and auxiliary system. For evaluation of steam turbine seal performance, the air similarity test of labyrinth seal leakage verification was conducted and we compared experiment data and analysis result.

• 한국유체기계학회 논문집
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• 제7권5호
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• pp.29-35
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• 2004

The turbine efficiency is an important factor in power plant, and accurate evaluation of steam turbine performance is the key issue in turbo machinery industry. The difficulty of evaluating the steam turbine performance due to its high steam temperature and pressure environment makes the most steam turbine tests to be replaced by air similarity test. This paper presents how to decide the similarity conditions of the steam turbine test and describes its limitations and assumptions. The test facility was developed and arranged to conduct an air similarity turbine performance test with various inlet pressure, temperature and mass flow rate. The eddy-current type dynamometer measures the turbine-generated shaft power and controls the rotating speed. Pressure ratio of turbine can be controled by back pressure control valve. To verify its test results, uncertainty analysis was performed and relative uncertainty of turbine efficiency was obtained.

• 한국추진공학회지
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• 제10권2호
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• pp.39-45
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• 2006

로켓 엔진 터보펌프용 터빈은 고온, 고압의 연소가스를 사용하기 때문에 실제 환경에서 성능시험을 수행하기가 매우 어렵다. 따라서 대부분의 경우, 시험에 따르는 위험을 줄이기 위하여 공기를 사용한 시험을 통하여 성능을 평가한다. 본 논문에서는 10 톤급 액체로켓엔진 터보펌프용 터빈에 대한 공기 상사 성능시험에 대하여 기술하였다. 터빈의 공기역학적인 성능을 평가하기 위한 성능시험설비를 구성하였으며, 성능시험설비는 고압공기 공급시스템, 유량측정용 노즐, 시험부, 동력계. 압력조절을 위한 출구 오리피스 그리고 측정 및 제어 시스템으로 구성된다. 본 논문에서는 터빈성능 시험을 위한 상사시험 조건을 결정하는 방법과 시험조건을 조절하는 방법에 대하여 기술하였다. 시험결과, 측정 변수들의 상대 표준오차는 1%이내였으며 측정된 터빈 효율은 해석결과와 2% 이내로 일치하였다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권3호
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• pp.162-168
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• 2014

This paper discusses the application of Bayesian techniques with test data on similar products for performing the Economical Reliability Test of new one-shot device. Using the test data on similar products, reliability test required lower sample size currently being spent in order to demonstrate a target reliability with a specified confidence level. Furthermore, lower sample size reduces cost, time and various resources on reliability test. In this paper, we use similarity as calculating weight of similar products and analyze similarity between new and similar product for comparison of the essential function.

• 한국대기환경학회지
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• 제16권4호
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• pp.351-362
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• 2000

To set the similarity conditions between a prototype usually in the field and its reduced-scale model is a crucial part in model tests. No technique is available to keep perfect similarity for this procedure so far. The experimental work using a wind tunnel is not exceptional. based on the field measurements, the effect of stack parameters and wind conditions on the dispersion of stack plume has been investigated in the laboratory. in this paper intensive methodology is focused on matching these similarities. Due to the limitations to keep perfect similarity conditions some simplifications are involved in common. In this study geometric conditions and kinematic conditions using Froude number and Reynolds number have been con-sidered to keep the similarity conditions required. From the tests it is found that the critical Reynolds number (Recrit) is 2,700 when the height of stack discharge is 50mm. The dispersion has a similar trend for the higher Reynolds number than the critical Reynolds number. It is also found that different Froude number does not make any significant influence for the normalized tracer gas concentrations at the recipient providing the same ratio of the wind speed to the discharge speed. No significant effect of stack diameter is observed in the normalized tracer gas concentrations with the same Frounde number. The similarity conditions therefore used in this study are reliable to simulate the conditions in prototype into the wind tunnel tests.

• 한국산학기술학회논문지
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• 제12권6호
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• pp.2807-2814
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• 2011

본 논문은 컬러공간 특성을 이용하여 유해동영상을 식별하는 알고리즘을 개발하고, 실험을 통하여 알고리즘의 효율성을 검증한다. 유해동영상 식별 알고리즘은 2차원 투영맵에 기초하고 있다. 비디오 이미지의 컬러특성을 추출하는데 있어 2차원 투영맵은 후보 프레임을 효과적으로 추출하는데 적용되어진다. 본 연구에서는 제시된 유사도 계산 알고리즘을 이용하여 추출된 프레임과 기준 이미지 간의 유사도를 먼저 계산하고, 유사도 평가를 통하여 유해동영상 후보프레임을 식별해 내고 임계치를 적용하여 최종 판단을 내린다. 제시된 알고리즘을 적용한 실험결과, 유해동영상을 찾는데 있어 컬러히스토그램보다 본 연구에서 제안한 2차원 투영맵을 이용한 기법이 계산속도와 식별능력 면에서 더 우수함을 입증하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제34권2호
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• pp.275-281
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• 2010

선박용 엔진 또는 플랜트 시스템에 사용되는 대형 소음기의 개발단계에서 비용절감 및 개발기간의 단축을 위하여 축소모형으로 대체 실험이 가능하도록 기하상사법을 제안하고자 한다. 대형 소음기를 구성하고 있는 공명형과 단순 확장관형 소음기의 원형과 축소 모형에 대한 이론식으로부터 기하상사 변수를 규명하였다. 그리고 음향해석을 통하여 조합형과 배플형의 축소 모형에 기하상사법을 적용하여 원형모형의 성능을 예측하고, 이를 원형모형의 실제 성능과 비교하는 방법으로 기하상사 변수를 검증하였다.

• 산업기술연구
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• 제27권A호
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• pp.111-120
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• 2007

This paper is results of experimental research on the effect of application of similarity related to permeability of soil on the consolidation behavior as centrifuge modeling of consolidation is performed with the centrifuge model facility. In this research, the permeability of soil was controlled by changing the viscosity of porewater as the mixed water with glycerin was used during the centrifuge model experiments. The effect of drainage path on consolidation was investigated by installing the vertical drains. A serise of centrifuge model tests with conditions of single vertical and radial horizontal drainage were carried out. Kaolinite and Jumunjin standard sand were used as soft clay and surcharges respectively during tests. For testing condition of single vertical drainage considering similarity of permeability, it was found that consolidation with mixed porewater with glycerin was delayed in comparisons sons with test results with water only. For conditions of horizontal drainage with vertical drains, a low permeability by changing the viscosity of pore water resulted in delayed degree of consolidation at an initial stage of consolidation. But, it predicted not much differences in settlement as long as the consolidation time was sufficiently long enough to finish consolidation. Consequently, it was found that similarity in permeability should be considered to be critical for the case of centrifuge model experiments related to consolidation with long drainage path.

• 인지과학
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• 제12권1_2호
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• pp.35-42
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• 2001

본 논문에서 문서는 문서관계도라고 하는 가중치 그래프로 표현된다. 노드는 문서의 구성요소인 문장을 명사벡터로 표현하고, 링크는 노드들 간의 의미적인 관계를 표현하며 의미적 유사도를 가중치로 가지고 있다. 한 노드의 인접한 노드를 사이의 유사도 합을 도합유사도라고 하며, 이를 문서에서 문장의 중요도로 간주한다. 본 논문에서는도합유사도를 이용한 한국어 문서요약 시스템을 기술한다. 실험에 사용된 평가용 요약문서는 정보처리관련 분야에서 수집된 논문 100편과 KORDIC에서 구축한 신문기사 105건을 이용하였다. 문서요약 시스템에 의해서 생상된 요약문서와 크기가 본문의 20%이고 평가용 요약문서가 논문(서론과 결론)일 경우, 재현율과 정확률은 각각 46.6%와 76.9%를 보였으며, 또한 평가용 요약문서가 신문기사일 경우, 재현율과 정확률은 각각 30.5%과 42.3%를 보였다.