• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.193-197
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• 2004

A finite element analysis is proposed to assess the dynamic response due to impulse excitation of UUV cable system. 'Onnuri'. a special purpose ship of KORDI. was adopted as a support vessel. and all the main dimensions and properties used in the analysis were determined by the support vessel. Transient dynamic response analysis was carried out for various types of impulses. and the magnitude of cable tension induced by impulse was discussed as results.

• Nuclear Engineering and Technology
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• 제43권2호
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• pp.167-174
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• 2011

A pressurizer in a small integral type pressurized water reactor is located inside the upper region of the reactor vessel, and uses a space between the upper head of the reactor vessel and the upper region of the upper guide structure which is partially filled with fluid depending on the operating power. This new design requires a comprehensive investigation of vibration characteristics. This study investigates the modal characteristics of a pressurizer which uses a simplified cylindrical shell model, focusing on how having fluid in the shell affects vibration and response characteristics. In addition, an analysis of sloshing is performed and the response characteristics are addressed.

• 해양환경안전학회지
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• 제27권7호
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• pp.1031-1037
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• 2021

국내 선박의 해양사고 발생률은 지속적으로 증가하고 있으며, 총톤수(Gross tonnage) 10톤 미만의 소형선박에서 집중적으로 발생하고 있다. 선박의 전복사고는 인명 및 재산 피해를 동반하기 때문에 반드시 예방되어야 하는 사고임에도 불구하고, 전복사고와 관련이 깊은 운항중인 소형선박의 내항성능 연구는 미진한 상태이며 내항성능과 관련된 국내·외 규정이 존재하지 않는 실정이다. 이에 본 연구에서는 전복사고가 발생한 소형선박의 재결서를 조사하여 전복사고의 주요 원인이 적재상태 불량이라는 점을 파악하고, 대표 선박을 선정하여 유체정역학적 계산 및 내항성능 해석을 수행하였다. 일반적으로 선박은 운항중 6자유도 운동을 하게 되는데 본 연구에서는 전복사고와 관련이 깊은 횡동요(Roll)를 알아보기 위해 대표 선박의 응답진폭연산자(RAO) 및 운동응답 스펙트럼(Response Spectrum)을 계산하고 3시간동안의 파도 정상상태(Stationary)에 대한 단기(Short Term) 통계 해석을 수행하였다. 그 결과 적재상태가 불량할 때에는 선박의 횡동요가 크게 발생하여 선박의 안정성을 크게 감소시킨다는 사실을 알 수 있었다.

• 상하수도학회지
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• 제34권1호
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• pp.53-60
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• 2020

Due to global climate change, Korea is experiencing flooding and drought severely. It is hard to manage water resources because intensive precipitation during short periods and drought are commonly occurred in Korea, recently. Severe drought occurred in 2015 and 2017 in the islands, and coastal and inland areas in Korea, and the citizens experienced decreased water supply and emergency water service by using bottled water. Therefore, the Korean government provided additional governmental funds such as the grant of drought disaster. In this study, we tried to calculate the cost of water for drought response based on the cost of tap water for the regional local governments in Korea and the grant of drought disaster by the Ministry of the Interior and Safety in Korea, etc. The estimated costs of water for drought responses in coastal and inland areas which have a chance to apply alternative water sources such as brackish or seawater desalination and water reuse in Korea were higher than in other areas in Korea. Additionally, as the novel approach of drought response, the 300 ㎥/day-scale desalination vessel was suggested to provide desalinated water for the islands in Korea. The estimated expenses of water supply for the target island areas (Sinan-gun and Jindo-gun) by the desalination vessel was lower than those by emergency water service by using bottled water.

• 소음진동
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• 제7권5호
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• pp.837-845
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• 1997

본 연구에서는 가압경수로의 핵심부품인 원자로용기와 제어봉구동장치사이의 동적 상호작용의 영향을 평가하였다. 원자로용기와 제어봉구동장치를 단순 수학모델화하여 단순조화 기저가진에 대한 정상상태 주파수응답을 구하고, 응답을 최소화할 수 있는 설계변수를 제시하였다. 단순 수학모델의 적합성을 입증하기 위하여 원자로용기와 제어봉구동장치의 유한요소 모델에 대하여 ANSYS 코드를 사용하여 해석한 후 정상상태응답을 수학모델로 구한 응답과 비교하였다. 또한 기존설계와 최적화설계에 대하여 지진사고 시간이력해석을 각각 수행함으로써, 본 연구에서 제시한 최적설계변수가 내진설계에 대하여도 적용할 수 있음을 확인하였다.

• 한국기계가공학회지
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• 제18권1호
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• pp.65-71
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• 2019

The development of adsorbed natural gas (ANG) has emerged as one of potential solutions. It is desirable to reduce the weight of vessel by applying light-weighed a composite carbon fiber in order to response to a egulation of $CO_2$ emission. Through understanding of a composite carbon fiber, and material characteristic of a composite carbon fiber is required in order for better application of a reduction of weight and an analysis of material characteristic. Herein, this study suggest the composite carbon fiber vessel applied to the characteristic of carbon fiber, and it decides the preliminary shape based on the test of material characteristic for ANG vessel applied to a composite carbon fiber, and its basic shape calculate through on the netting theory. Moreover, the detail shape design is analyzed by a finite element analysis, and in the stage of detail sahp design and analysis of stress was performed on the typical shape using a finite element analysis, and the result of preliminary design was verified.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.221-226
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• 2011

The structural integrity of APR1400 reactor vessel internals has been being assessed referring the US Nuclear Regulatory Commission regulatory guide 1.20 comprehensive vibration assessment program. The program is composed of a vibration and stress analysis, a limited vibration measurement, and an inspection. This paper covers the vibration and stress analysis on the reactor vessel internals due to the pulsation of reactor coolant pump. 3-dimensional models to calculate the hydraulic loads and structural responses were built and the pressure distributions and the structural responses were predicted using ANSYS. The peak stress of the reactor vessel internals is much lower than the acceptance limit.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.1969-1982
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• 2015

The virtual inertia control (VIC) of wind turbine with directly-driven permanent-magnet synchronous generator (D-PMSG) can act similarly to the conventional synchronous generator in inertia response and frequency control, thereby supporting the system frequency stability. However, because the wind speed is inconstant and changeable to a certain extent and the D-PMSG is a complex nonlinear system, there are great difficulties in the virtual inertia optimal control of the D-PMSG. Based on the design principle of the active disturbance rejection control (ADRC), this paper presents a new VIC strategy for the D-PMSG from the perspective of power disturbance suppression in the system. The strategy helps fulfill the power grid disturbance estimation and compensation by means of the extended state observer (ESO) so as to improve the disturbance-resisting performance of the system. Compared with conventional proportional-derivative virtual inertia control (PDVIC), this method, which is of better adaptability and robustness, can not only improve the property of the D-PMSG responding to the system frequency but also reduce the influence of wind speed disturbance. The simulation and experiment results have verified the effectiveness and feasibility of the VIC based on the ADRC.

• 해양환경안전학회지
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• 제19권4호
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• pp.397-402
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• 2013

본 연구에서는 전장이 26.75 m인 해양플랜트지원선의 선형개발을 위한 수치해석을 수행하였고 수치해석 검증을 위한 1/10의 모형선 시험을 예인수조에서 수행하였다. 또한 운항해역의 해상조건으로 뷰포트 스케일 2, 3 및 4에서 향파, 선수사파 및 횡파에서 선속별 상하동요 및 종동요에 대해서 운동응답특성을 수치 해석하였다. 모형시험과 수치해석의 저항 예측 결과는 상호 일치하였다. 운동응답특성은 선수파에서 상하동요는 조우주파수 1.8~2.0 영역에서 크게 나타났으며, 종동요는 거친 해상에서 선미사파 및 고속영역에서 높은 운동특성을 보였다.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1513-1523
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• 2017

Improvement of numerical analysis methods has been required to solve complicated phenomena that occur in nuclear facilities. Particularly, fluid-structure interaction (FSI) behavior should be resolved for accurate design and evaluation of complex reactor vessel internals (RVIs) submerged in coolant. In this study, the FSI effect on dynamic characteristics of RVIs in a typical 1,000 MWe nuclear power plant was investigated. Modal analyses of an integrated assembly were conducted by employing the fluid-structure (F-S) model as well as the traditional added-mass model. Subsequently, structural analyses were carried out using design response spectra combined with modal analysis data. Analysis results from the F-S model led to reductions of both frequency and Tresca stress compared to those values obtained using the added-mass model. Validation of the analysis method with the FSI model was also performed, from which the interface between the upper guide structure plate and the core shroud assembly lug was defined as the critical location of the typical RVIs, while all the relevant stress intensities satisfied the acceptance criteria.