• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.399-402
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• 2006

This paper presents a new circuit topology of dc bus line switch-assisted half-bridge soft switching PWM inverter type dc-dc converter for arc welder. The proposed power converter is composed of typical voltage source half-bridge high frequency PWM inverter with a high frequency transformer link in addition to dc bus line side power semiconductor switching devices fer PWM control scheme and capacitive lossless snubbers. All the active power switches in the half-bridge arm and dc bus lines can achieve ZCS turn-on and ZVS turn-off commutation operation and consequently the total turn-off switching losses can be significantly reduced. As a result, a high switching frequency of using IGBTs can be actually selected more than about 20 kHz. The effectiveness of this new converter topology is proved for low voltage and large current dc-dc power supplies such as arc welder from a practical point of view.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.482-489
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• 2004

Paging extensions for Mobile IP was proposed to avoid unnecessary registration signaling overhead of Mobile IP. In order to support the paging function in Mobile IP, the slates of a mobile node arc divided into active on, active off, idle. The active on state means when any incoming or outgoing data session arrives to a mobile node. After data session is completed, the state of the motile node is changed into active off from active on. At this moment, the active timer starts to be operated. If the active timer expires, the mobile node moves to idle state. If a mobile node has very frequently data sessions at the same cell, the mobile node is better to move slowly into idle state. The other way, if the mobile node very frequently moves into new cell area and receives or sends little data, the mobile node is better to move earlier into idle state. In this raper, the active timer is adaptively set by the mobile nodes traffic and mobility characteristics and the paging scheme using this active timer is proposed to reduce the location registration cost.

• International Journal of Automotive Technology
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• v.3 no.3
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• pp.123-128
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• 2002

This paper presents the design of an active roll control system for a ground vehicle and an experimental study using an devised electric-actuating roll control system. Based on a three degree of freedom linear vehicle model, the controller is designed using lateral acceleration and rollrate feedback. In order to investigate the feasibility of an active control system, experimental work is carried out using a hardware-in-the-loop (Hil) setup which has been constructed by the devised electric-actuating system and the full vehicle model including tire characteristics. The performance is evaluated by an experiment using the Hil setup with limited bandwidth. Finally, in order to enhance the control performance in the transient region, a hybrid control strategy is proposed and evaluated.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.694-699
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• 2001

This paper presents a control of active suspension system for quarter-car model with two-degree-of-freedom using $H_{inf}$ and nonlinear adaptive robust control method. Suspension dynamics is linear and treated by $H_{inf}$ method which guarantees the robustness of closed loop system under the presence of uncertainties and minimizes the effect of road disturbance to system. An Adaptive Robust Control (ARC) technique is used to design a force controller such that it is robust against actuator uncertainties. Simulation results are given for both frequency and time domains to verify the effectiveness of the designed controllers.

• Journal of Powder Materials
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• v.19 no.1
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• pp.6-12
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• 2012

Electricity is generated by the combined reactions of hydrogen oxidation and oxygen reduction which occur on the Pt/C catalyst surface. There have been lots of researches to make high performance catalysts which can reduce Pt utilization. However, most of catalysts are synthesized by wet-processes and a significant amount of chemicals are emitted during Pt/C synthesis. In this study, Pt/C catalyst was produced by arc plasma deposition process in which Pt nano-particles are directly deposited on carbon black surfaces. During the process, islands of Pt nano-particles were produced and they were very fine and well-distributed on carbon black surface. Compared with a commercialized Pt/C catalyst (Johnson & Matthey), finer particle size, narrower size distribution, and uniform distribution of APD Pt/C resulted in higher electrochemical active surface area even at the less Pt content.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.522-524
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• 1994

This paper presents power factor and distortion improvement methods via active boost converter and mode select. This method not only reduces the current and voltage distortion but also the physical size and expected low cost. Optimum parameter values arc derived to minimize the harmonise in the input current. A theoretical analysis, simulation and experimental results arc presented.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.209-210
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• 2006

The Bismarck Sea represent a unique region in the equatorial western Pacific where one can explore the relationship between tectonic and magmatic processes associated with back-arc opening. The sea, located north of Papua New Guinea and just south of the equator, formed during the final stages of a long, complex geological development of the Melanesian Borderland. The development resulted from the Cenozoic convergence between the Australian and Pacific- Caroline Plates and the opening of back-arc basins. At present, the Bismarck Sea straddles two oppositely facing trenches, the inactive Manus trench and the active New Britain trench, and covers two basins, the New Guinea Basin (NGB) to the west and the Manus Basin (MB) to the east. The two basins are separated by the shallow Willaumez-Manus Rise (WMR), which trends roughly from WNW to ESE. The origin of these major structural units and their relationship with the presentday zone of major seismicity along the Bismarck Sea Seismic Lineation (BSSL) remains unclear and is the main focus of our study.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.107-108
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• 2022

본 연구에서는 Arc GIS의 Network Analysis로 119안전센터의 재난 대응 권역을 설정해 재난 취약 면적을 계산하고 지역자율방재단의 재난피해 완충효과를 분석했다. 모든 값은 Min-Max Normalization 되어 동일한 Scale로 계산되었다. 지역자율방재단은 재난피해 완충 대책으로써 유의미한 효과가 있음을 확인했다. 지속적인 지역자율방재단의 활성화는 주민 참여, 지역특화적 재난 방재 대책 수립에 효과적이다.

• Journal of Agricultural Extension & Community Development
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• v.21 no.4
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• pp.1227-1259
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• 2014

This paper explores agricultural extension systems, extension challenges, research and extension models, governance structures of agricultural extension and advisory services in Sudan. Agricultural extension services in Sudan are provided by a variety of governmental department and corporation. The Technology Transfer and Extension Administration under the Ministry of Agriculture and Irrigation, had been launched during mid 2000's aims at making extension systems farmer driven and farmer accountable by way of new institutional arrangements for technology dissemination in the form of community participation approach at the state level, to make the extension reforms have the active participation of farmers/farmer groups. The main problem facing agricultural extension services in developing countries is poor link between extension organization and research. Both extension administration and Agricultural Research Corporation (ARC) are operating as departments of ministry of Agricultural and irrigation for very long time. There are three recommendations to achieve the effectiveness of the Agricultural Research Corporations (ARC) in reaching farmers. Firstly, extension staff members should be assigned to every ARC station. Secondly, the ARC might increase positions for Agricultural development specialist or Farming System Research (FSR) specialist. Their role would be to reflect the needed of farmer and translate them to the researchable topics. Thirdly, researcher should conduct more research on farmer's fields.

• Journal of Welding and Joining
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• v.18 no.2
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• pp.196-196
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• 2000

Formation of the weld defect, such as a blowhole and a pit in lap-jointed fillet arc welds has been a serious problem in arc welding of Zn-coated steel sheet. In this study, the relationship among welding conditions, welding materials and defect formation was investigated in order to minimize these defects in the CO₂ welds. In addition, the arc stability of the commercial welding wires was evaluated for revealing their effects on defect formation. Main conclusions obtained are as follows:1) There was no difference between shear tensile strength of the sound welds and that of the welds with blowholes whose diameters are less than 0.5mm. However, the welds with blowholes whose diameters are equal or larger than 0.5mm and pits exhibited tensile strength 10~20% and 30~40% lower than that of the sound welds respectively.2) The optimum welding condition to effectively prevent or reduce the weld defects formation are as follows:- The welding variables of 220A-23V-100cm/min and 120A-190V-30cm/min were recommended for minimizing the weld defects.- The gap between the two sheets at the lap-joint should be controlled to more than 0.2mm- Solid wire was less susceptible to the formation of the weld defects than the flux-cored wire.- The low welding current condition produced less weld defects than the hihg welding current condition.3) One of the reason why the amount of the defect was reduced at the low welding current was the gas discharging by the active agitation of the molten pool, due to an increasing in the number of the short circuit. (Received September 27, 1999)