• Nuclear Engineering and Technology
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• 제46권3호
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• pp.373-380
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• 2014

Safety-related parameters are very important for confirming the status of a nuclear power plant. In particular, the reactor vessel water level has a direct impact on the safety fortress by confirming reactor core cooling. In this study, the reactor vessel water level under the condition of a severe accident, where the water level could not be measured, was predicted using a fuzzy neural network (FNN). The prediction model was developed using training data, and validated using independent test data. The data was generated from simulations of the optimized power reactor 1000 (OPR1000) using MAAP4 code. The informative data for training the FNN model was selected using the subtractive clustering method. The prediction performance of the reactor vessel water level was quite satisfactory, but a few large errors were occasionally observed. To check the effect of instrument errors, the prediction model was verified using data containing artificially added errors. The developed FNN model was sufficiently accurate to be used to predict the reactor vessel water level in severe accident situations where the integrity of the reactor vessel water level sensor is compromised. Furthermore, if the developed FNN model can be optimized using a variety of data, it should be possible to predict the reactor vessel water level precisely.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.702-710
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• 2016

Global concern and interest in the safety of nuclear power plants have increased considerably since the Fukushima accident. In the event of a severe accident, the reactor vessel water level cannot be measured. The reactor vessel water level has a direct impact on confirming the safety of reactor core cooling. However, in the event of a severe accident, it may be possible to estimate the reactor vessel water level by employing other information. The cascaded fuzzy neural network (CFNN) model can be used to estimate the reactor vessel water level through the process of repeatedly adding fuzzy neural networks. The developed CFNN model was found to be sufficiently accurate for estimating the reactor vessel water level when the sensor performance had deteriorated. Therefore, the developed CFNN model can help provide effective information to operators in the event of a severe accident.

• Ocean and Polar Research
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• 제39권3호
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• pp.221-232
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• 2017

The purpose of this study is to estimate the extent of fisheries resource rebuilding and other economic effects on coastal gill-net fishery as a result of the Korean vessel buy-back program using with-without analysis based on methods estimating sustainable yields for all species caught by coastal gill-net fishery. Based on the results of with-without analysis, maximum sustainable yields (MSY) of all species caught by coastal gill-net fishery have been increased by the Korean vessel buy-back program. In addition, profits per vessel of maximum economic yield (MEY) of the species have been improved by the program. Further, yields and a producer surplus per vessel under an equilibrium of open access (OA) have increased because of the program. In detail, first of all, at the MSY level, the vessel buy-back program has led to about 21% fisheries resource recovery, and at the MEY level, it has led to about a 19% resource recovery. Secondly, at the MEY level and the OA level, the producer surplus per vessel has been increased by about 24% and 22% respectively by the vessel buy-back program.

• 동서간호학연구지
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• 제22권1호
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• pp.32-40
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• 2016

Purpose: This study aimed to provide basic data for vascular health of patient who underwent percutaneous coronary intervention (PCI) by verifying the mediating effect of compliance in the relationship between risk level of coronary artery disease (CAD) and blood vessel elasticity. Methods: This is a descriptive study with 115 patients, who underwent the PCI a year ago and visited in the cardiology department from January to March, 2015. The risk level of CAD, blood vessel elasticity and the compliance were measured. For data analysis, SPSS/WIN 21.0 and AMOS (IBM) 21.0 were used. Results: There were a positive correlation with blood vessel elasticity score (i.e. inelasticity of the blood vessel wall) (r=.189) and a negative correlation with compliance (r=-.658) in mediating effect of risk level of CAD. There was a negative correlation between compliance and blood vessel elasticity (r=-.482). The direct effect (${\beta}=-.226$), indirect effect (${\beta}=.415$) and total effect (${\beta}=.186$) of mediating effect of risk level of CAD on blood vessel elasticity were significant. Compliance had a partial mediating effect of risk level of CAD on blood vessel elasticity. Conclusion: The results of this study suggest that managing and preventing moderating effect of risk level of CAD on compliance is helpful in restoring blood vessel elasticity.

• 대한토목학회논문집
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• 제34권4호
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• pp.1251-1259
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• 2014

본 연구에서는 산재되어 있는 부산항 입출항 선박의 개별 활동도(정박 접안 특성) 및 선박제원 정보를 기존 항만운영정보시스템(PORT-MIS) DB에 연계 구축하기 위한 방법론을 제시하고, 연계 구축된 3가지 DB를 이용하여 18개월(2009.01~2010.06) 동안 부산항에 입출항한 선박의 온실가스 배출량을 산정하여 그 결과를 비교 분석하였다. 본 연구에서는 선박의 기본 활동도 변수만을 포함하고 있는 저해상도의 L-PORT-MIS DB에 각 선박의 정박시간 자료를 추가하여 중해상도의 M-PORT-MIS DB를 연계 구축하였으며, 각 선박의 온실가스 배출량에 직접적인 영향을 주는 엔진출력 등과 같은 선박제원 정보를 연계시켜 고해상도의 H-PORT-MIS DB를 구축하였다. 각 활동도 DB를 이용한 선박의 온실가스 배출량 산정결과, 선박 활동도의 해상도가 높아질수록 총 온실가스 배출량은 감소하는 것으로 분석되었다. 구체적으로 저해상도 및 중해상도의 선박 활동도 자료를 이용할 경우에는 과거에 집계화된 정박 및 접안 특성에 의존하여 온실가스 배출량이 과다 산정되는 반면, 고해상도의 선박 활동도 자료를 이용할 경우에는 각 선박의 개별 접안 정박 특성과 엔진출력이 고려되는바 H-PORT-MIS DB를 이용한 선박의 온실가스 배출량은 보다 신뢰성 높은 추정치로 판단된다. 이처럼 부산항을 입출항하는 개별 선박의 특성을 반영하여 온실가스 배출량을 산정했을 경우 그 추정치는 기존 추정치와 매우 달라질 수 있어 실효성 있는 온실가스 저감대책 수립을 위해서는 본 연구에서 제안한 DB의 연계 구축이 시급하다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권4호
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• pp.374-385
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• 2012

The indoor noise of a ship is usually determined using the A-weighted sound pressure level. However, in order to better understand this phenomenon, evaluation parameters that more accurately reflect the human sense of hearing are required. To find the level of the satisfaction index of the noise inside a naval vessel such as "Loudness" and "Annoyance", psycho-acoustic evaluation of various sound recordings from the naval vessel was performed in a laboratory. The objective of this paper is to develop a single index of "Loudness" and "Annoyance" for noise inside a naval vessel according to a psycho-acoustic evaluation by using psychological responses such as Noise Rating (NR), Noise Criterion (NC), Room Criterion (RC), Preferred Speech Interference Level (PSIL) and loudness level. Additionally, in order to determine a single index of satisfaction for noise such as "Loudness" and "Annoyance", with respect to a human's sense of hearing, a back-propagation neural network is applied.

• 한국소음진동공학회논문집
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• 제21권7호
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• pp.650-656
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• 2011

The noise inside a naval vessel is very important in considering the need for hearing protection, improving the working environment and maintaining good communications for crews living on board a naval vessel. The indoor noise of a ship usually is specified by the A-weighted sound pressure level, but other evaluating parameters are required to reflect human senses more effectively. This paper uses additional noise indices related to room acoustics, such as NR(noise rating), NC(noise criterion), RC(room criterion), PSIL(preferred speech interference level) and loudness level to evaluate the noise inside cabins on a naval vessel. Using these psychological noise indices, allowable limit of noise level in cabins is suggested through psycho-acoustic evaluation for the noise in cabins.

• International Journal of Control, Automation, and Systems
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• 제4권5호
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• pp.660-667
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• 2006

This paper presents a novel region-based snake method for vessel segmentation. According to geometric shape analysis of the vessel structure with different scale, an efficient statistical estimation of vessel branches is introduced into the energy objective function, which applies not only the vessel intensity information, but also geometric information of line-like structure in the image. The defined energy function is minimized using the gradient descent method and a new region-based speed function is obtained, which is more accurate to the vessel structure and not sensitive to the initial condition. The narrow band algorithm in the level set framework implements the proposed method, the solution of which is steady. The segmentation experiments are shown on several images. Compared with other geometric active contour models, the proposed method is more efficient and robust.

• Journal of Mechanical Science and Technology
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• 제14권9호
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• pp.935-946
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• 2000

Elastic-plastic stress analysis has been performed to evaluate the fatigue life of an autofrettaged pressure vessel containing cross-bores subjected to pulsating internal pressure of 200 MPa. Finite element analyses were used to calculate the residual and operating stress distributions of the pressure vessel due to the autofrettage process and pulsating internal pressure, respectively. Theoretical stress concentration factors of 3.06, 2.58, and 2.64 were obtained at the cross-bore of the pressure vessel due to internal pressure, 50%, and 100% autofrettage loadings, respectively. Local stresses and local strains determined from the elastic-plastic finite element analysis were employed to calculate the failure location and fatigue life of the pressure vessel with radial cross-bores, incorporating the low-cycle fatigue properties of the pressure vessel steel and fatigue damage parameters. Increase in the amount of overstrain by autofrettage process moved the crack initiation location from the inner radius toward a mid-wall, and extended the crack initiation life. Predicted fatigue life of the fully autofrettaged pressure vessel with cross-bores increased about 50%, compared to the unautofrettaged pressure vessel. At the autofrettage level higher than 50%, the failure location and fatigue life of the pressure vessel were not significantly influenced by the autofrettage level.

• 소음진동
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• 제7권1호
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• pp.33-41
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• 1997

경수로형 원자력발전소 표준화 작업의 일환으로 만들어진 한국표준형 원자력 발전소는 그 건설부지를 한반도뿐만 아니라 인접 아시아국가의 여러곳을 목표로 하고 있으며 이와 관련하여 안전정지지진의 레벨을 0.3g로 증가시키려는 시도가 계획되고 있다. 본 연구에서는 이와 같은 지진레벨 증가가 기존의 0.2g로 설계된 원자로 내부 구조물과 핵연료집합체에 미치는 영향을 평가하였다. 운전기준지진 및 안전정지지진의 응답을 비교함으로써 비선형 응답특성을 조사하였고 한국표준형 원자력발전소의 원자로 내부구조물 및 핵연료집합체의 설계 타당성에 대하여 언급하였다.