• Journal of Advanced Marine Engineering and Technology
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• 제10권4호
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• pp.41-49
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• 1986

With the trend towards high propulsive level, increasing ship's dimensions and heavier shaft systems supported by the hull structure of relatively stiffness in modern ships, transverse vibrations of propulsion shaft system have become one of the problems that should be predicted in the early design stage. Regarding transverse vibrations, coupling terms such as oilfilm, gyroscope and hydrodynamic effect of the propeller exist between the vertical and horizontal vibration, furthermore for the shaft system with strut and bossing its physical properties incorporated with hull structure must be considered. In order to predict the transverse vibratory condition of the propulsion shaft and take some appropriate countermeasures, it is necessary to make a fairly strict estimation of the vibratory behaviours of it. In this paper, theoretical approach using the finite element method is investigated to calculate natural frequencies and vibration modes for coupled free transverse vibrations of shaft system in two planes. Based on the method investigated a digital computer program is developed and is applied to calculate the above-mentioned vibrations of an experimental model shaft system. The results of the calculation are compared with those of the experimental measurements and they show an acceptable agreement.

• 한국통신학회논문지
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• 제36권5B호
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• pp.549-556
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• 2011

본 연구에서는 기존의 우선 부표가 지니고 있는 문제점들을 해결할 수 있는 원근해 어로용 고성능 무선 부표 시스템을 개발하였다. 2진 FSK 변조방식과 우선부표용 송수신 프로토콜을 도입하여 사용시간을 대폭 개선하였으며, GPS 위치정보와 여러 계측정보를 수집한 후 모선의 탐지기 호출이 있을 경우 전송함으로써 쉽게 탐색이 이루어질 수 있도록 하였다. 개발된 우선부표는 평균 73일의 동작시간과 120km 이상의 동작시간과 120km 이상의 동작범위를 갖으며, 분실과 도난을 방지할 수 있다.

• Journal of Electrical Engineering and Technology
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• 제6권6호
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• pp.750-759
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• 2011

This paper focuses on the control of bidirectional power flow in the electric shipboard power systems, especially in the Medium-Voltage Direct Current (MVDC) shipboard power system. Bidirectional power control between the main MVDC bus and the local zones can improve the energy efficiency and control flexibility of electric ship systems. However, since the MVDC system contains various nonlinear loads such as pulsed power load and radar in various subsystems, the voltage of the MVDC and the local zones varies significantly. This voltage variation affects the control performance of the bidirectional DC-DC converters as exogenous disturbances. To improve the control performance regardless of uncertainties and disturbances, this paper proposes a novel controller design method of the bidirectional DC-DC converters using $L_1$ control theory and intelligent optimization algorithm. The performance of the proposed method is verified via large-scale real-time digital simulation of a notional shipboard MVDC power system.

• 수산해양기술연구
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• 제35권1호
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• pp.54-59
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• 1999

High-speed electronic digital computers have enabled engineers to employ various numerical discretization techniques for solutions of complex problems. The Finite Element Method is one of the such technique. The Finite Element Method is one of the numerical analysis based on the concepts of fundamental mathematical approximation. Three dimensional plate structures used often in partition of ship, box girder and frame are analyzed by Finite Element Method. In design of structures, the static deflections, stress concentrations and dynamic deflections must be considered. However, these problem belong to geometrically nonlinear mechanical structure analysis. The analysis of each element is independent, but coupling occurs in assembly process of elements. So, to overcome such a difficulty the shell theory which includes transformation matrix and a fictitious rotational stiffness is taken into account. Also, the Mindlin's theory which is considered the effect of shear deformation is used. The Mindlin's theory is based on assumption that the normal to the midsurface before deformation is "not necessarily normal to the midsurface after deformation", and is more powerful than Kirchoff's theory in thick plate analysis. To ensure that a small number of element can represent a relatively complex form of the type which is liable to occur in real, rather than in academic problem, eight-node quadratic isoparametric elements are used. are used.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.58-59
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• 2017

Through the case study, we surveyed the performance of a CNC-T BAR system on irregular-shaped building construction project. By CNC T-BAR system, we mean a surface curvature control system has been used in aircraft and ship manufacturing by controlling entire surface points on shape. For the past 10 year, the number of irregularly-shaped building design and construction project has been increased, and also the studies on irregular-shaped construction methods have been conducted. However, the previous studies did not review on the performance of the CNC T-BAR system. We collected construction-completed cases in Korea, which applied the CNC T-BAR system, and we studied its performance by comparing with a segment system in terms of construction duration and its quality. The result shows that the CNC T-BAR system can shorten the construction duration comparing with segment-assembly system while maintaining high quality. The CNC T-BAR system is expected to apply on the more number of irregularly-shape building construction project.

• 대한조선학회논문집
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• 제44권3호
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• pp.340-347
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• 2007

Main purpose of the study is to develop a transit model for icebreaking cargo vessels in the Northern Sea Route and to select optimum sea routes with the shortest navigation time and the lowest operation cost. This numerical model executed with basic information such as ship capabilities, transit directions and months of transit, can calculate total transit distance and elapsed time, mean speed, operation cost for each vessel. In the transit model. environment information such as the site-specific ice conditions, wave and wind states are utilized for four different months (April, June, August, and October) along the Northern Sea Route. The model also defines a necessary period of an icebreaker escort. Then the optimum sea routes are selected and visually displayed on the digital map using a commercial software ArcGIS. Usefulness of the selected sea routes is discussed.

• 대한공간정보학회지
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• 제16권3호
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• pp.71-78
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• 2008

현재 해양 측량 및 선박항해 목적으로 음향측심기가 사용되어지고 있다. 하지만 신뢰성 있는 수심인식이 주 목적인 음향측심기가 낮은 수심 또는 험한 해저 지형에서 수심 인식률이 현저히 떨어지는 문제점이 있다. 이를 해결하기 위해 트랜듀서의 음파특성 파악 및 최적 알고리즘을 연구를 하였다. 알고리즘 연산처리를 하기 위해 최신 DSP프로세서(TMS320F2812)를 적용하여 고속으로 데이터처리를 하는 하드웨어 설계를 하였다. 마지막으로 기존방식과 최적 알고리즘을 적용한 방식을 비교하여 데이터 신뢰성을 비교하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제20권4호
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• pp.27-35
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• 1996

The ship's propulsion efficiency depends upon a combibation of engine and propeller. The propeller has better efficiency as the engine has lower rotational speed. This situation led the engine manufacures to design the engine that has lower speed, longer stroke and a small number of cylinders. With this new trends the conventional mechanical-hydrualic governors for engine speed control have been replaced by digital speed controllers which adopted the PID control or the optimal control algorithm. But these control algorithms have not enough robustness to suppress the variations of the delay-time and the parameter perturbation especially in low speed engine. In this study we consider the perturbations of the engine parameters as the modeling uncetainties and design a robust speed controller for marine medium speed diesel engine by means of $ extit{H}_{infty}$control theory having the central solution. By comparing the results of the robust speed controller with those of mechanical governor and PID controller, the validity of the robust speed controller under parameter variations is confirmed. The speed control of the experimental diesel engine of carried out using actuator which is composed of PWM signal generator and D.C servo motor.

• Journal of Advanced Marine Engineering and Technology
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• 제20권4호
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• pp.349-349
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• 1996

The ship's propulsion efficiency depends upon a combibation of engine and propeller. The propeller has better efficiency as the engine has lower rotational speed. This situation led the engine manufacures to design the engine that has lower speed, longer stroke and a small number of cylinders. With this new trends the conventional mechanical-hydrualic governors for engine speed control have been replaced by digital speed controllers which adopted the PID control or the optimal control algorithm. But these control algorithms have not enough robustness to suppress the variations of the delay-time and the parameter perturbation especially in low speed engine. In this study we consider the perturbations of the engine parameters as the modeling uncetainties and design a robust speed controller for marine medium speed diesel engine by means of $ extit{H}_{infty}$control theory having the central solution. By comparing the results of the robust speed controller with those of mechanical governor and PID controller, the validity of the robust speed controller under parameter variations is confirmed. The speed control of the experimental diesel engine of carried out using actuator which is composed of PWM signal generator and D.C servo motor.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2015년도 추계학술대회
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• pp.43-44
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• 2015

AIS-ASM은 AIS의 고유 기능인 선박의 위치 정보 외에 다양한 해양안전정보를 제공하기 위한 연구 중 하나로, 2004년부터 관련 규정을 정비하여 진행 중이다. 본 연구는 여객선의 출항에서 입항까지 안전항해를 위해 필요한 국내 여객선 항해사의 의무보고 내용을 조사하고 업무 부하를 줄이기 위해 자동화 할 수 있는 부분을 차세대 해상디지털통신 기술인 ASM2.0을 활용하여 자동화 하는데 목적이 있으며, 국내 여객선 운항 관련 법규를 조사하여 상호 교환해야하는 정보를 도출하고 국제적으로 사용하고 있는 AIS-ASM 메시지 분석을 통해 ASM2.0에서 활용하기 위한 프로토콜을 설계하고 프로토타입을 구현하였다.