• 대한조선학회논문집
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• 제42권1호
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• pp.18-23
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• 2005

The transmission and reflection coefficiencies of a BBDB-type floating breakwater in water of finite depth are studied taking account of fluctuating air pressure in the air chamber. The wave potential is calculated by a hybrid integral equation consisting of a Green integral equations associated with the Rankiue Green function inside the BBDB and the Kelvin Green function outside. The transmission and reflection coefficients of the breakwater are obtained directly from the potential solution in the outer region.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.659-662
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• 2009

Railway has been pointed to the efficiency of transportation, rapid transit, and comfortable train ride. the construction of railway near the downtown area and station building are increasing for maximization of utilization and convenience. but the heavy of transportation and rapid transit lead to increase noise and vibration. the noise and vibration of railway may cause the civil appeal, decline in the serviceability and insufficiency of environmental standard. In this study, floating slab system which is one of the solution to avoid noise and vibration in railway has been introduced, and analyzed floating Slab Track into arrangement of reduction material of vibration. As a result of analysis, It was estimated the bearing installation though slab have not a negative factor and terminal arrangement of reduction material of vibration have advantage for static behavior.

• 센서학회지
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• 제11권5호
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• pp.294-300
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• 2002

In this study, we fabricated thermopile infrared sensor with floating membrane structure. Floating membrane was formed by SOI(Silicon On Insulator) structure. In SOI structure, silicon dioxide layer between top silicon layer and bottom silicon substrate was etched by HF solution, then membrane was floated over substrate. After membrane was floated, thermopile pattern was formed on membrane. By insertion of SOI technology, we could obtain thermal isolation structure easily and passivation process for sensor pattern protection was not required during fabrication process. Then, the amplifier circuit for thermopile sensor was fabricated by using $1.5{\mu}m$ CMOS process. The voltage gain of fabricated amplifier was about two hundred.

• 한국정보통신학회논문지
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• 제8권5호
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• pp.1089-1095
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• 2004

주어진 네트워크에서 최적의 스타이너 트리를 구하는 문제는 NP-hard이며, 최적에 가까운 스타이너 트리를 구하기 위하여 유전자 알고리즘을 이용한다. 본 논문에서는 이 문제를 해결하기 위하여 유전자 알고리즘에서 염색체를 기존의 이진스트링 대신 부동소수점으로 표현하였다. 먼저 주어진 네트워크에 Prim의 알고리즘을 적용하여 스패닝 트리를 구하고, 부동소수점 표현을 갖는 유전자 알고리즘을 사용하여 새로운 스타이너 점을 트리에 추가하는 과정을 반복함으로써 최적에 가까운 스타이너 트리를 구했다 이 방법을 사용하면 이진스트링을 사용하는 기존의 방법에 비해서 트리가 보다 빠르고 정확하게 최적에 가까운 스타이너 트리에 접근했다.

• 한국결정성장학회지
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• 제5권2호
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• pp.87-93
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• 1995

Floating zone법으로 strontium titanate 단결정을 육성하였다. 성장조건은 공기 분위기하에서 성장속도 3mm/hr, 상부축 회전속도 20~25rpm, 하부축 회전속도 15~20rpm이었으며 육성한 단결정은 옅은 갈색을 띄고 있었으며 투명하였고 annealing 후 색깔이 옅어짐을 확인할 수 있었다. 성장방위는 [112] 방향이었으며 XRD, EDS로 화학양론적인 조성은 $SrTiO_3$단일 결정상임을 알 수 있었다. $350^{\circ}C$, KOH용액에서 5분동안 chemical etching하여 etch pit pattern을 조사하였으며 상온하에서$350^{\circ}C$의 온도 범위에서 유전상수 값을 조사하였다.

• 한국CDE학회논문집
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• 제15권6호
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• pp.411-417
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• 2010

In this paper, the boom of a floating crane is modeled as a 3-dimensional elastic beam in order to analyze the dynamic response of the crane and its cargo. The boom is divided into more than two elements based on finite element formulation, and deformation of each element is expressed in terms of shape matrix and nodal coordinates. The equations of motion for the elastic boom consist of a mass matrix, a stiffness matrix, and a quadratic velocity vector that contains the gyroscopic and Coriolis forces. The size and complicity of the matrices increase in proportion with the number of elements. Therefore, it is not possible to derive the equations of motion explicitly for different number of elements. To overcome this difficulty, matrices for one 3-dimensional element are expressed with elementary sub-matrices. In particular, the quadratic velocity vector is derived as a product of a shape matrix and a 3-dimensional rotation matrix. By using the derived matrices, the equations of motion for the multi-element boom are automatically constructed. To verify the implementation of the elastic boom based on finite element formulation, we simulated a simple vibration of the elastic boom and compared the average deformation with the analytic solution. Finally, heave motion of the floating crane and surge motion of the cargo are presented as application examples of the elastic boom.

• 산업공학
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• 제24권1호
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• pp.78-86
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• 2011

To mitigate space restriction and to raise productivity, some shipbuilding companies use floating-docks on the sea instead of dry-docks on the land. In that case, a floating-crane that can lift very heavy objects (up to 3,600 tons) is used to handle the blocks which are the basic units in shipbuilding processes, and so, very large blocks (these are called the mega-blocks) can be used to build a ship. But, because these mega-blocks can be made only in the area near the floating-dock and beside the sea, the space is very important resource for the process. Therefore, our problem is to make an efficient spatial schedule for the mega-block assembly yard. First of all, we formulate this situation into a mathematical model and find optimal solution for a small problem using a commercial optimization software. But, the software could not give optimal solutions for practical sized problems in a reasonable time, and so we propose a GA-based heuristic algorithm. Through a numerical experiment, finally, we show that the spatial scheduling algorithm can provide a very good performance.

• 산업공학
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• 제17권spc호
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• pp.28-36
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• 2004

The main purpose of this study is to find out the optimal solution of the vehicle routing problem considering heterogeneous vehicle(s), double-trips, and multi depots. This study suggests a mathematical programming model with new numerical formula which considers the amount of delivery and sub-tour elimination and gives optimal solution by using OPL-STUDIO(ILOG). This study also suggests modified genetic algorithm which considers the improvement of the creation method for initial solution, application of demanding point, individual and last learning method in order to find excellent solution, survival probability of infeasible solution for allowance, and floating mutation rate for escaping from local solution. The suggested modified genetic algorithm is compared with optimal solution of the existing problems. We found the better solution rather than the existing genetic algorithm. The suggested modified genetic algorithm is tested by Eilon and Fisher data(Eilon 22, Eilon 23, Eilon 30, Eilon 33, and Fisher 10), respectively.

• East Asian mathematical journal
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• 제32권3호
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• pp.301-310
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• 2016

Lookback options, in the terminology of nance, are a type of exotic option with path dependency whose the payoff depends on the optimal (maximum or minimum) underlying asset's price occurring over the life of the option. In this paper, we exploit Mellin transform techniques to find a closed-form solution for European lookback options in Black-Scholes model.

• Ocean Systems Engineering
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• 제10권4호
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• pp.399-414
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• 2020

A floating bridge is an innovative solution for deep-water and long-distance crossing. This paper presents a curved floating bridge's dynamic behaviors under the wind, wave, and current loads. Since the present curved bridge need not have mooring lines, its deep-water application can be more straightforward than conventional straight floating bridges with mooring lines. We solve the coupled interaction among the bridge girders, pontoons, and columns in the time-domain and to consider various load combinations to evaluate each force's contribution to overall dynamic responses. Discrete pontoons are uniformly spaced, and the pontoon's hydrodynamic coefficients and excitation forces are computed in the frequency domain by using the potential-theory-based 3D diffraction/radiation program. In the successive time-domain simulation, the Cummins equation is used for solving the pontoon's dynamics, and the bridge girders and columns are modeled by the beam theory and finite element formulation. Then, all the components are fully coupled to solve the fully-coupled equation of motion. Subsequently, the wet natural frequencies for various bending modes are identified. Then, the time histories and spectra of the girder's dynamic responses are presented and systematically analyzed. The second-order difference-frequency wave force and slowly-varying wind force may significantly affect the girder's lateral responses through resonance if the bridge's lateral bending stiffness is not sufficient. On the other hand, the first-order wave-frequency forces play a crucial role in the vertical responses.