• Nuclear Engineering and Technology
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• 제29권5호
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• pp.417-431
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• 1997

To resolve a general argument about OBE elimination for the future nuclear power plant design, seismic responses of reactor vessel internals and fuel assembly for Ulchin nuclear power plant units 3 and 4 in Korea are investigated as an example. Dynamic analyses of the coupled internals and core are performed for the seismic excitations using the reactor vessel motions. By investigating the response relations between OBE and SSE and their response characteristics, the critical components for OBE loading are addressed. Also the fuel assembly responses are calculated using the core plate motions and their behavior is found to be insignificant for OBE elimination.

• International Journal of Ocean System Engineering
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• 제3권4호
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• pp.175-187
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• 2013

Moonpools are vertical wells in a floating body used onboard many types of vessels like Exploration and drilling vessels, Production barges, Cable-laying vessels, Rock dumping vessels, Research and offshore support vessels. Moonpool gives passage to underwater activities for different types of ships as per their mission requirements. It is observed that inside a moonpool considerable relative motions may occur, depending on shape, depth of the moonpool and on the frequency range of the waves to which the ship is exposed. The vessel responses are entirely different in zero and non-zero Froude number. Former situation is paid attention in this study as the mission requirement of the platform is to be in the particular location for long period of operation. It is well known that there are two modes of responses depending on the shape of the moonpool viz., piston mode for square shape and sloshing mode for rectangular shapes with different aspect ratios of opening like 1:1.5 and 1:2 ratios. Circular shaped moonpool is also tested for measuring the responses. The vessel moored using heavy lines are modelled and tested in the wave basin. The pretensions of the lines are varied by altering the touchdown points and the dynamic tensions on the lines are measured. The different modes of oscillations of water column are measured using wave gauge and the vessel response at a particular situation is determined. RAOs calculated for various situations provide better insight to the designer.

• Steel and Composite Structures
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• 제38권2호
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• pp.189-211
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• 2021

An analytical solution is presented to analyze the thermoelastoplastic response of a rotating thick-walled cylindrical pressure vessel made of functionally graded material (FGM). The analysis is based on Tresca's yield condition, its associated flow rule and linear strain hardening material behaviour. The uncoupled theory of thermoelasticity is used, and the plane strain condition is assumed. The material properties except for Poisson's ratio, are assumed to vary nonlinearly in the radial direction. Elastic, partially plastic, fully plastic, and residual stress states are investigated. The heat conduction equation for the one-dimensional problem in cylindrical coordinates is used to obtain temperature distribution in the vessel. It is assumed that the inner surface is exposed to an airstream and that the outer surface is exposed to a uniform heat flux. Tresca's yield criterion and its associated flow rule are used to formulate six different plastic regions for a linearly hardening condition. All these stages are studied in detail. It is shown that the thermoelastoplastic stress response of a rotating FGM pressure vessel is affected significantly by the nonhomogeneity of the material and temperature gradient. The results are validated with those of other researchers for appropriate values of the system parameters and excellent agreement is observed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.319-321
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• 1994

This paper describes the analysis and modeling process of vessel which is used for induction heating jar and induction healing cooker. We present how to calculate the value of modeling parameter according to the shape of the vessel and work coil, and the temperature of vessel.

• 해양환경안전학회지
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• 제19권2호
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• pp.219-224
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• 2013

해양유류오염사고가 발생한 경우에 필요한 모든 방제자원을 사전에 확보하고 사고에 대응하는 것이 가장 효과적이지만 현실적으로는 한계가 있는 실정이다. 그러므로 대규모 유류오염사고에 대비하여 유류오염으로 피해를 입게 되는 오염지역의 어선을 활용하는 방안이 중요한 대안이 될 수 있다. 미국 등 선진국에서도 지역 어선을 이용한 임시방제정 프로그램이 개발되어 운영되고 있는 사례를 찾아볼 수 있다. 본 연구는 국내 소형어선에 적합한 기름방제용 스위핑 암 시스템을 검토하였다. 모델로 선정된 소형 선박은 연안유자망어선 및 연안복합어선으로 2.5~3.5톤, 길이 8~9 m, 폭 2.5~2.8 m, 마력 200~250 HP, 선질 FRP인 어선이다. 개발된 장치는 모델 선박에 간편하게 장착할 수 있고 이동이 가능한 구조로 설계되었다. 조립 및 분해를 쉽게 하기위해 각 부품의 무게를 10 kg 이하로 구성함으로써 현장 실용성을 높였다.

• Ocean Systems Engineering
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• 제3권2호
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• pp.137-147
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• 2013

Moonpools are vertical wells in a floating body used onboard many types of vessels like cable-laying vessels and offshore support vessels. Moonpool gives passage to underwater activities for different types of ships as per their mission requirements. It is observed that inside a moonpool considerable relative motions may occur, depending on shape, depth of the moonpool and on the frequency range of the waves to which the ship is exposed. The vessel responses are entirely different in zero and non-zero Froude number. Former situation is paid attention in this study as the mission requirement of the platform is to be in the particular location for long period of operation. It is well known that there are two modes of responses depending on the shape of the moonpool viz., piston mode for square shape and sloshing mode for rectangular shapes with different aspect ratios of opening like 1:1.5 and 1:2 ratios. Circular shaped moonpool is also tested for measuring the responses. The vessel moored using heavy lines are modeled and tested in the wave basin. The moored lines are provided with pre-tension and the dynamic tensions on the lines are measured. The different modes of oscillations of water column are measured using wave gauge and the vessel response at a particular situation is determined. RAOs determined for various situations provide better insight to the designer. The experiments done in the wave basin may also be compared with a software package meant for handling moored floating bodies.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1221-1222
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• 2010

• 한국해양공학회지
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• 제32권6호
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• pp.440-446
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• 2018

The effects of an anti-rolling tank (ART) on vessel motions were numerically investigated. The potential-based BEM vessel motion simulation program and particle-based computational fluid dynamics program were dynamically coupled and used to perform a simulation of vessel motions with ART. From the time domain simulation results, the response amplitude operators for sway and roll motions were obtained and compared with the corresponding experimental and numerical results. Because the main purpose of ART was only to reduce roll motions, it was important to show that the natural properties of a floating vessel were not changed by the effects of ART. Various ART filling ratios and several ART positions were considered. In conclusion, ART only reduced the roll motion regardless of its filling ratio and position.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2716-2727
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• 2021

The core shroud is one of the most important internal components of the reactor vessel internals because it meets the neutron fluence directly emitted by the nuclear fuel. In particular, dynamic effects for an earthquake should be evaluated with respect to the neutron irradiation flux. As a prerequisite to this study, simplified and detailed finite element models are developed for the core shroud using the ANSYS Design Parametric Language. Using the El Centro earthquake, seismic analyses are performed for the simplified and detailed core shroud models. Modal characteristics are obtained and their results are used for a time history analysis. Response spectrum analyses are also performed to access the degree of seismic excitation. The results of these analyses are compared to investigate the response characteristics between the simplified and detailed core shroud models from the time history and response spectrum analyses.

• 한국컴퓨터정보학회논문지
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• 제29권1호
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• pp.131-138
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• 2024

해군 함정의 위협에 대한 전투체계의 신속하고 정확한 대응능력은 함정의 생존력 및 전투력과 직결된다. 하지만 현재 해군 함정전투체계의 적 잠수함 잠망경 탐지 방법은 센서로부터 수신한 정보를 운용자가 직접 확인하고 분석하는 수동적이고 주관적인 방법에 의존하고 있다. 이는 위협에 대한 대응 시간을 지연시켜 함정의 생존력을 저해하는 요인이 된다. 본 논문에서는 표적의 고해상도 거리 측면도(High Resolution Range Profile, 이하 HRRP)를 통해 생성된 Plot 정보를 확률에 따른 의심 등급으로 구분하고, 등급별 알림을 통해 위협 대응 시간을 비약적으로 단축시키는 잠망경 탐지 알고리즘을 소개한다. 알고리즘 테스트 결과 운용자 대비 133.3791 × 10⁶배 빠른 탐지판단시간과 12.78%p 높은 탐지 성공률을 도출하여 해군 함정 생존력을 높일 수 있는 위협 대응시간 단축 가능성을 확인하였다.