• 한국항해항만학회지
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• 제28권7호
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• pp.619-627
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• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. We also considered the increase of water depth at the entrance channel by dredging work up to 15 meters depth in order to see the dredging effect. Among several model analyses, the nonlinear and breaking wave conditions are showed the most applicable results. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1266-1269
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• 2004

With increasingly wide needs for a new energy source, many operation types of a wave-forced generation have been studied. To obtain an economically avaliable energy, it is imperative that the speed of the in put wave should be increased by a proper mechanism. In this study, we propose a new speed-increaser mechanism for the wave-force generation using a well-known Stephenson mechanism. In this paper, we have analysed kinematically the proposed speed-increasing mechanism. then a computer program based on the C++ language is developed to prove the validity of our mechanism and to simulate a wave-forced generation.

• 수산해양기술연구
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• 제28권2호
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• pp.228-239
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• 1992

The purpose of the present research is to develop an efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. Some numerical results for series 60, C sub(b) =0.6, hull are presented in this paper. The wave pattern and wave resistance are computed at two Froude numbers, 0.267 and 0.304. These results are better than those of Michell's thin ship theory in comparison with measured results. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.

• 한국전기전자재료학회논문지
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• 제13권4호
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• pp.280-285
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• 2000

The conventional ultrasonic linear motors developed so far utilize a standing wave and are of a pi-type or a hybrid transducer type structure. Traveling wave type bi-direction linear motors have not been developed yet. This paper describes design of a new bi-directional ultrasonic linear motor working by means of a traveling wave. With the finite element method we design and verify validity of the new structure. And we determine its optimal structure size of design variables material and boundary conditions for proper generation of the traveling wave.

• 한국해안·해양공학회논문집
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• 제31권6호
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• pp.395-402
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• 2019

기존 케이슨의 안정성을 높이기 위해 신규 케이슨을 기존 케이슨 전면 또는 후면에 추가로 설치하여 보강하는 설계 및 시공사례가 발생되고 있다. 본 연구에서는 고유함수전개법을 이용하여 원형케이슨으로 구성된 기존 방파제 후면에 신규 원형케이슨이 설치될 경우 각 원형케이슨에 작용하는 파력특성을 분석하였다. 수치해석의 신뢰성을 확보하기 위해 상용화 프로그램인 ANSYS AQWA의 수치 해석결과와 비교를 수행하였으며, 원형 케이슨 추가설치에 따른 파와 구조물의 상호작용 영향을 고려하여 각 원형케이슨에 작용하는 파력을 산출하였다.

• 한국수소및신에너지학회논문집
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• 제21권1호
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• pp.35-41
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• 2010

Water management is an important issue of PEM fuel cell operation. Water is the product of the electrochemical reactions inside fuel cell. If liquid water accumulation becomes excessive in a fuel cell, water columns will clog the gas flow channel. This condition is referred to as flooding. A number of researchers have examined the water removal methods in order to improve the performance. In this paper, a new water removal method that investigates the use of vibro-acoutic methods is presented. Piezo-actuators which are devices to generate the flexural wave are attached at the end of a cathode bipolar plate. Flexural wave is used to impart energy to resting droplets and thus cause movement of the droplets in the direction of the traveling wave.

• 한국해안·해양공학회논문집
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• 제34권6호
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• pp.233-246
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• 2022

기존 케이슨방파제의 전면 또는 후면에 추가로 케이슨을 설치하여 구조물의 안정성을 향상시키기 위한 설계 및 시공사례가 보고되고 있다. 본 연구에서는 상용프로그램인 ANSYS AQWA를 이용하여 신규 케이슨이 추가로 설치되는 경우 입사하는 파랑과 케이슨들간의 상호작용 영향에 의해 개별 케이슨에 작용하는 파력 특성을 분석하였다. 앞뒤 케이슨간의 간격변화에 따른 개별 케이슨에 작용하는 파력 특성을 주파수영역에서 수치해석을 수행하였다. 그리고 특이한 파력분포 특성이 발생되는 주파수에 대해서는 불규칙파 조건에서의 시간영역 수치해석을 통해 개별 케이슨에 작용하는 동적파력 특성을 면밀하게 검토하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1100-1103
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• 2007

For the past decade many effort has been delivered to understand noise generation mechanism for the small size engine cooling fan. As a result of that effort, the low noise fan such as the Wave fan was developed. Now the Wave fan becomes the well known low noise engine cooling fan. But in case of the new car development, the system in the new car will be different from previous one. So we need system optimization for every new model. In case of special application, a low speed fan should be developed to match system requirement. In that case, we meet severe engineering requirement by conducting fan system optimization instead of the simple fan scaling. In this paper, I will show you the system optimize process.

• 한국해안·해양공학회논문집
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• 제34권6호
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• pp.177-187
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• 2022

본 연구는 2020년 해양수산부에서 제시한 개정된 천해설계파 추산방법인 바람장을 이용하여 부산항 신항을 대상으로 태풍 내습 시 설계파를 추산하고 파랑 관측자료와의 검증을 통해서 신뢰할 수 있는 천해설계파 산출방법을 제안하였다. 부산항 신항에 영향을 미친 태풍에 대해서 현업에서 일반적으로 많이 사용하고 있는 태풍 바람장과 SWAN 수치모델을 이용하여 태풍파를 추산한 결과 태풍 KONG-REY(1825), MAYSAK(2009)을 제외하고 재현성이 불량한 것으로 나타났다. 특히 부산항 신항에 가장 크게 영향을 미쳤던 태풍 MAEMI(0314)의 경우 최대유의 파고가 파랑 관측치에 비해서 약 35.0% 작게 추산되었다. 이에 바람장을 보정한 방법과 Boussinesq 방정식 수치모델을 이용하는 방법을 각각 적용하여 태풍파 재현성 개선방안을 검토하였다. 검토결과 바람장을 보정한 경우는 바람장 보정전과 동일하게 재현성이 떨어지는 것으로 나타났으나, 바람장 자료와 SWAN 모델 실험결과 그리고 Bou ssinesq 수치모델을 연계하는 방법으로 태풍 MAEMI(0314) 내습 시 태풍파를 추산한 결과 파랑 관측치와 최대유의파고가 유사하게 나타나 재현성이 양호한 것으로 검토되었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.171-171
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• 2010

An innovative design of a floating-buoy wave energy converter (WEC) using hydrostatic transmission (HST), named HSTWEC, is presented in this paper. The system is designed to convert ocean wave fluctuation into electricity by using the HST circuit and an electric generator. Based on the floating-buoy concept, the wave forces the sub-buoy to move up and down. Consequently, the electric power can be obtained from the generator in both the moving directions of the sub-buoy through the HST circuit as shown in Fig. 1. In order to investigate the HSTWEC operations, a mathematical model of the system is indispensible. In addition, the method to control the HSTWEC, including: pump displacement control, tension adjustment control and ballast weight control, is also discussed in this paper. Finally, the design concept as well as simulation results indicated that this HSTWEC design is an effective solution and possible to fabricate for wave energy generation.