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OWC design to increase wave energy absorption efficiency in wave conversion systems
오진석,장재희 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.7
Oscillating water column (OWC) systems are commonly used as wave energy converters. Such a system consists of an air chamberwith a seawater inlet and an air discharger. If seawater moves as a result of the vertical motion of external waves, then the seawaterwithin the OWC moves as well. This movement within the system generates air pressure, which produces power with which to turn theWells turbine in the air discharge port. OWC systems must be designed in consideration of vibration because waves possess basic oscillationproperties. In this research, the efficiency characteristics of OWC systems combined with breakwaters are studied by applying avibration model. Factors affecting the energy conversion rate of OWC include the volume of air in the air chamber, pressure, and waveperiod. In this study, changes in the energy absorption efficiency of OWC are measured according to the area ratio between the air dischargerand the air chamber, as well as on the basis of air chamber length. Simulations are performed with varying design parameters,such as internal wave, air pressure, and energy, according to changes in external waves. In addition, wave period properties are modifiedaccording to the surroundings of the sea in which the OWC system is installed. Variations in these period properties affect energy conversionefficiency. Therefore, changes in energy absorption efficiency due to the wave period are simulated in this study to design anOWC system with high absorption efficiency in view of the characteristic of wave periods in Korea.
Inlet geometry effect of wave energy conversion system
오진석,Sung-Hun Han 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.9
A floating marine facility, such as a buoy, plays an important role as an aid to navigation for maritime safety. Due to development of the wave energy conversion system, installing an oscillating water column (OWC) with rechargeable batteries on a buoy has become the trend. In order to extend the battery replacement cycle, the battery voltage must be kept within a certain range by improving the energy conversion efficiency. This paper suggests using inlet geometry modification of the OWC to increase vertical displacement. Two types of inlet geometry, the trumpet type and the cylindrical type, are designed and compared with each other through a scale model experiment in a 2-D wave tank, as well as through a full-scale experiment at sea. The results show that the trumpet-shaped inlet of the OWC generates more electric power than does the cylindrical-shaped inlet.
오진석 한국마린엔지니어링학회 2003 한국마린엔지니어링학회지 Vol.27 No.6
This paper considers the method of elimination harmonics in AC/DC converters, There are few practical methods to reduce the harmonics in AC/DC converters, particularly in filter design and control strategy. In this paper, a harmonic elimination methods are proposed, which includes hybrid PWM control strategy. These methods achieve precise output control along with the optimum performance simultaneously. The control method in this paper is developed to eliminate a fixed number of harmonics in AC to DC converter. The higher order harmonics can be easily eliminated by using filter proposed in this paper. The validity of these methods is confirmed experimentally.
오진석,김윤식,오세준,최순만,신명철 한국마린엔지니어링학회 1997 한국마린엔지니어링학회지 Vol.21 No.3
In this paper, a controller with monitoring functions is proposed for controlling temperature of an electric furnace system. The controller includes holding and ramp control functions, and the control program for the temperature process monitor of the electric furnace. For this purpose, the implementation and performance of auto tuning algorithms in a computer¬based controller is studied in relation to control of a nonlinear electric furnace system which is characterized with large time delay. The communicator of a control and detection signals, between the controller and the electric furnace is implemented by an I/O data card. Experiments for the practical electric furnace are performed to illustrate the performance of the proposed controller.
오진석(?珍?) 고구려발해학회 2019 고구려발해연구 Vol.65 No.-
‘삼연문화’는 1990년대 초반 전립곤이 제기한 고고학문화의 한 개념으로 이와 관련된 연구가 지난 20여 년 동안 한 · 중 · 일의 몇 몇 학자들에 의해서 진행되었다. 한국에서는 고구려 · 백제 · 신라 · 가야 등 고대사를 연구하는 역사학자들에 의해 주로 다루어 졌으며, 삼연문화와 관련된 고고학연구의 방향은 삼연문화 자체 보다는 마구 등 일부 문물의 비교에 치중되었다. 이와 같은 연구 성향은 단기적으로 일부 성과를 볼 수 있지만, 장기적 · 종합적으로 보면 한계를 보일 수밖에 없다. 본고에서는 삼연문화의 성립 배경과 현재까지 조사 · 연구된 내용을 종합하여, 이후 이어지는 삼국시대 관련 연구에 도움이 되고자 하였다. 본문에서는 먼저 문헌에서 보이는 삼연과 관련된 자료를 정리하고, 중국의 ‘삼연문화’란 고고학적 개념 성립 과정을 살폈다. 다음으로 현재까지 조사ㆍ연구된 삼연문화와 관련된 고분자료 및 출토 유물을 고찰하여 삼연문화 시기를 크게 4시기로 구분하였다. 제1기는 조위 초년시기에서 모용선비가 요서지역으로 진입한 3세기 초에서 3세기 말경이며 주변문화의 영향을 많이 받지 않은 시기이다. 제2기는 모용외 시기인 3세기 말에서 4세기 초경이다. 모용선비 세력이 요서지역에서 확장되면서 한문화, 해당지역 토착문화, 기타선비문화, 부여문화 등 주변문화의 영향을 받기시작 하였다. 제3기는 전연시기인 4세기 초에서 4세기 후반경이다. 모용선비 본연의 문화요소가 급속히 감소하고 한문화의 흡수가 가속화 되어가는 시기이다. 제4기는 후연, 북연시기인 4세기 후반에서 5세기 전반경이다. 주변문화와 모용선비 문화가 심도 깊게 융합하여 나타난다.
하이브리드 RSPWM 인버터의 설계 및 특성해석에 관한 연구
오진석,김윤식 한국마린엔지니어링학회 1995 한국마린엔지니어링학회지 Vol.19 No.1
In this paper, a new speed control scheme for induction motor drives that regular sampled PWM and harmonic elimination switching pattern over the full range of output speed is presented. The proposed scheme(hybrid scheme) provides three mode and guarantees smooth voltage boost. A detailed description of the scheme, along with the relalization aspect, is described. Moreover, methods of compensating for dead time and optical transmission system of drive signal are proposed and investigated. Finally, experimental investigation of hybrid scheme is presented.