• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.39-40
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• 2006

Diesel power plant(DPP) with the medium speed diesel engine is operated under the very severe condition in aspect of load and operating time as compared with the marine diesel generator set. So, minimized vibration level have to be insured for the more stable operation of engine and generator. The vibration of generator set mainly comes from the resonance between the rigid modes by resilient mount or distortion modes by structural stiffness and the excitation forces of engine. Then, avoidance of resonance with structural modification is generally well known. In this paper, the first order vibration in non-resonance range and local vibration modes were investigated by impact test, response/ODS(operational deflection shape) measurement and 3D finite element analysis for the additional reduction of vibration. The proposed countermeasures were actually applied and their final effects were verified through the in-situ measurement.

• 한국소음진동공학회논문집
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• 제17권3호
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• pp.235-240
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• 2007

In this work, the operational deflection shape(ODS) of an automobile exhaust system is measured by using a recently-developed magnetic sensor. The magnetic sensor is composed of a solenoid and two pairs of permanent magnets generating an antisymmetric magnetic field in the lateral direction inside the solenoid. Lateral movement of a ferromagnetic pipe inside the magnetic field of the suggested sensor induces an electromotive force in the solenoid corresponding to the lateral velocity of the pipe. Due to the simplicity and non-contact characteristics of the magnetic sensor, dynamic behaviors of the structures operating under high temperature such as an exhaust pipe can be efficiently observed. It is shown that the lateral ODS of an exhaust system can be successfully measured by the suggested sensors.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권2호
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• pp.270-287
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• 2015

According to the increase of the operating cost and material cost of a ship due to the change of international oil price, a demand for the lightening of the ship weight is being made from various parties such as shipping companies, ship owners, and shipyards. To satisfy such demand, many studies for a light ship are being made. As one of them, an optimal design method of an existing hull structure, that is, a method for lightening the ship weight based on the optimization technique was proposed in this study. For this, we selected a hatch cover of a bulk carrier as an optimization target and formulated an optimization problem in order to determine optimal principal dimensions of the hatch cover for lightening the bulk carrier. Some dimensions representing the shape of the hatch cover were selected as design variables and some design considerations related to the maximum stress, maximum deflection, and geometry of the hatch cover were selected as constraints. In addition, the minimization of the weight of the hatch cover was selected as an objective function. To solve this optimization problem, we developed an optimization program based on the Sequential Quadratic Programming (SQP) using C++ programming language. To evaluate the applicability of the developed program, it was applied to a problem for finding optimal principal dimensions of the hatch cover of a deadweight 180,000 ton bulk carrier. The result shows that the developed program can decrease the hatch cover's weight by about 8.5%. Thus, this study will be able to contribute to make energy saving and environment-friendly ship in shipyard.

• 한국산학기술학회논문지
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• 제17권10호
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• pp.319-330
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• 2016

3D 프린팅 기술은 다양한 산업분야에서 개념모델 및 기능성 시제품을 제작하는데 많이 응용되고 있지만, 3D 프린팅 소재 및 제작된 제품 신뢰성 등의 여러 가지 이유로 상용화 제품으로 적용되는 데 한계가 존재한다. 본 논문에서는 3D 프린팅 기술을 이용한 산업적 응용분야 중 하나로 발전소 저탄장에 사용되는 풀 코드 스위치 모듈의 부품들 중 잦은 돌발 상황으로 인해 파손이 자주 발생하는 허브 구동부와 레버 고정부 부품들에 대해 현장에서 작업자들이 단기 대체부품으로 적용이 가능하도록 하는 부품 최적 설계 및 FDM 방식 3D 프린팅 제조공정기술에 대한 연구결과를 제시하였다. 3D 프린팅 기술의 경우 소재 적용에 있어서 한계가 존재하므로, 본 논문에서는 구조 최적화 설계를 통해 구조 안정성을 확보하는 방안에 대해 연구를 수행하였다. 허브 구동부 부품에 대해 내부 구조 형상 및 구조 설계 변수 최적화를 수행하여 좌측구동모드에서는 안전계수가 153.67% 증가한 1.243을 확보할 수 있었으며, 우측구동모드에서는 404.96% 증가한 3.156을 확보할 수 있었다. 레버 고정부 부품의 경우, 반복적인 스위칭 구동에 의한 굽힘 모멘트로 인해 발생하는 파손을 최소화하기 위해 구조 최적화 설계를 수행하여 26% 증가한 구조 안전계수(7.52)를 확보할 수 있었다. 본 연구를 통해 3D 프린팅 기술을 단기 대체부품 제조공정에 적용함에 있어서 소재 최적화를 통한 설계보다는 3D 프린팅 공정의 적층특성을 활용한 구조적 최적화 설계기법 이 더욱 유연한 결과를 도출할 수 있음을 확인할 수 있었다.