• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2477-2486
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• 2000

A planetary gear assembly is a key component to combine and/or split a power from the source. With a planetary gear assembly, a continuously variable unit extends its capacity by means of power bra nching mechanism. Power branching with one planetary gear assembly and one continuously variable unit is categorized into 12 basic types. Each type represents peculiar power transmitting characteristics. Additionally, a multi-mode (range) continuously variable transmission can be designed with accompanying clutches. A multi-mode continuously variable transmission changes the path through which the source power is transmitted. Each path has its own features, such as high efficiency. In this paper, some design principles are examined such as, criteria to guarantee the minimum power efficiency, and constraints to guarantee the smooth mode shift after discussing well-known features of multi-mode M mathematically.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.799-802
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• 2002

Continuously variable transmission(CVT) mechanisms considered here combine the functions of a K-H-V type differential gear unit and a V-belt type continuously variable unit(CVU). As combining the functions of a K-H-V type differential gear unit and a V-belt type CVU, 24 different mechanisms are presented. Some useful theoretical formula related to speed ratio, power flow and efficiency are derived and analyzed. These mechanisms have many advantages which are the decrease of CVT size, the increase of overall efficiency, the extension of speed ratio range, and the generation of geared neutral.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.758-761
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• 1991

Using one chip microcontroller 87Cl96 (On chip EPROM type) and EPLD (Erasable & Programable Logic Device), an implantable control system to drive pendulum type electromechanical total artificial heart was developed. This control system consists of 4 parts, main management system, motor driver with power regulator, state monitoring system and communication part. The main system has the functions for speed detection, PI(proportional and integration) control, PWM generation, communication and analog data processor. Two kinds of power system were used and separated by 8 photo coupler arrays to improve the system stability. The performances of each compartments were compared with our previous z80 microprocessor based control system and good correspondences was shown. Logic power consumption was reduced to a one third of our previous controller. Using mock circulation tests, the overall performances of control system are evaluated.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.957-960
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• 2003

Many solar cell way need to be connected by series or parallel to extract the high power Especially, during parallel operation to reduce circulation current the individual converter has to share and control the load current. Generally, Current Sharing(CS) can be implemented using droop and active current sharing method. In this paper, one 3[KW] PWM converter was replaced as one 3[KW] solar cell array(3 parallels, each parallel has twenty single modules), two 3[KW] solar cell way Is Paralleled to generate 6[KW] power. Also each converter used voltage-current controller and Automatic MSCPM(Master-Slave Current-programming Method) for current sharing(AS).

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.199-208
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• 2003

Continuously variable transmission (CVT) mechanisms considered here combine the functions of a K-H-V type differential gear unit and a V-belt type continuously variable unit (CVU). As combining the functions of a K-H-V type differential gear unit and a V-belt type CVU, 24 different mechanisms are presented. Some useful theoretical formula related to speed ratio, power flow and efficiency are derived and analyzed. These mechanisms have many advantages which are the decrease of CVT size, the increase of overall efficiency, the extension of speed ratio range, and the generation of geared neutral.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.590-593
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• 2009

Tidal current power system is one of ocean renewable energies that can minimize the environmental impact with many advantages compared to other energy sources. Not like others, the produced energy can be precisely predicted without weather conditions and also the operation rate is very high. To convert the current into power, the first device encountered to the incoming flow is the rotor that can transform into rotational energy. The performance of rotor can be determined by various design parameters including numbers of blade, sectional shape, diameter, and etc. The stream lines near the rotating rotor is very complex and the interference effects around the system is also difficult to predict. This paper introduces the experiment of rotor performance and also the effect of design parameter on the performance of HAT rotor by CFD.

• 한국디지털정책학회:학술대회논문집
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• 2007.06a
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• pp.171-180
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• 2007

The purpose of this paper is to find an policy vision and action plans for the growth of the Korean cultural contents industry as a new growth power in the 21th century. For this purpose, I referred to sundry records to analyze the characteristics, industrial situation and the prospects of the cultural contents industry. I also made an analysis on the outcome of the cultural contents policy with the help of the official concerned in the Ministry of Culture and Tourism, which made it possible for me to draw a few urgent problems of Korean cultural contents industry. With these preceding analyses, I proposed the strategy and action plans of the government policy for the Korean cultural contents industry as follows : strengthening the creative power of the cultural contents industry, systemizing the healthy circulation of the cultural contents, and improvement of the cultural welfare on the basis of contents.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.31-38
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• 2022

Recently, the development of offshore wind farms based on past technical experiences from onshore wind turbine installations has become a worldwide issue. This study investigated the technical issues related to offshore wind farms and large-diameter monopiles from an economic perspective. In particular, the monopile foundation system (MFS), which is the most important part of the proposed fast construction system, is applied for the first time in Korea, and structural verification is essential because it supports large-diameter monopiles and is in charge of excavation. Therefore, in this study, a rapid construction system for large offshore wind power generators was introduced, and stability verification was performed through the structural analysis of the MFS.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.82-85
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• 2007

A cooling system for a 22.9kV, 1.25kA 100m HTS power cable has been installed and tested. The cooling system consists of decompression cooling system with the cooling capacity of 3kW and a closed circulation system of subcooled liquid nitrogen. This paper describes the outline of the installed cooling system and performance test results.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.251-252
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• 2020

화석연료 사용으로 발생하는 환경문제 대처방안으로 풍력 등 신재생 에너지원 사용의 필요성이 강조되고 있으며, 이러한 사회적 요구에 따라 신재생 에너지 발전 시스템의 대용량화 추세에 있다. 시스템 대용량화에 있어 안정적인 에너지 발전과 공급을 위해 전력변환장치의 신뢰성 향상이 필요하다. 특히, 풍력발전시스템의 경우 돌풍 등 일정하지 않은 풍속으로 인하여 전력변환장치의 잦은 고장이 발생하고, 이는 전체 시스템의 신뢰성 결정에 주된 영향을 미친다. 본 논문에서는 병렬형 전력변환장치에서 높은 고장률을 보이는 스위칭 소자의 열적 스트레스를 줄이기 위한 무효전력순환 기반 능동 열 제어기법을 제안한다. 제안한 기법의 동작특성을 이론적으로 분석하고, 열 회로망 시뮬레이션을 통해 그 영향을 검증한다.