• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.456-459
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• 2011

The Dual-type Solenoid Valve was developed for a domestic production of a fuel-supply valve on the satellite attitude control thruster system. The satellite valve using a hydrazine as a fuel must fulfill the cycle life, shock, vibration and the environment of an extremely low temperature In addition to the basic performance of the response time, mass flow and leakage etc.. in this paper, the design, production and performance experiment using the nitrogen pneumatic equipment were conducted.

• The Korean Journal of Pain
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• v.5 no.1
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• pp.23-28
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• 1992

The use of epidural narcotics to treat cancer pain was first described by Behar et al in 1979. More recently, a variety of implantable INDSs have been described for long-term intraspinal narcotic administration. Especially, among these systems INDS typeIII which is designed by Poletti et al is relatively low cost and less risk of infection, therefore this system has been widely accepted but the clinical experience is insufficient yet. 1, Problems, 1) thorough education of patients and care-givers about this system the method of drug delivery and the situations could be happen in using this system. 2) high cost of continuous drug delivery system 3) legal problems about morphine carry-out in the case of bolus infusion by syringe 1. Complications; 1) by morphine; Significant respiratory depression was not found in all 21cases. other morphine-related complications were occurred occasionally but improved within a few days by appropriate treatment. 2) by system, Blockage or leakage of catheter was occurred in 2cases and wound infection was occurred in 2cases and so reimplantation was done.

• 연구논문집
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• s.34
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• pp.69-77
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• 2004

Electro-pneumatic servo valve is an electro-mechanical device which converts electric signals into a proper pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristics, no air leakage at a null point, and can be fabricated at a low-cost. The objective of this research is to design and to fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In order to design the mechanism of the servo valve optimally, the flow inside the valve depending upon the position of spool was analyzed variously, and on the basis of such analysis results, the valve mechanism, which was formed by combination of the spool and the sleeve, was designed and manufactured. Further, the performance of pneumatic servo valve has been verified through an overall performance test on the developed product.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.815-818
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• 2004

The emerging applications such as reliable back-up power system and renewable energy call for high boost U-n converter. The conventional topologies to get high output voltage are using flyback circuit, cascade converters, and coupled inductor DC-DC converter. They have the stress and loss related to the leakage energy which results in low efficiency Tn this paper, novel high boost converter is presented. It has a structure of cascade boost converter but only one switch. Therefore, drive circuit is simple and extreme duty ratio is eliminated. To verify the proposed circuit, theoretical analysis and experimental results has been done using a prototype power supply.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.8
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• pp.392-401
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• 2001

This paper presents the single-stage high power factor AC to DC converter operated in active-clamp mode. The proposed converter is added active-clamping circuit to boost-flyback single-stage power factor corrected power supply. The active-clamping circuit limits voltage spikes, recycles the energy trapped in the leakage inductance, and provides a mechanism for achieving soft switching of the electronic switches to reduce the switching loss. The auxiliary switch of active-clamping circuit uses the same control and driver circuit as the main switch to reduce the additional cost and size. To verify the performance of the proposed converter, a 100W converter has been designed. The proposed converter gives good power factor correction, low line current harmonic distortions, and tight output voltage regulation, as used unity power factor.

• Korean Journal of Bronchoesophagology
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• v.14 no.1
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• pp.34-37
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• 2008

Although prolonged periods of intubation, chronic respiratory infection and inflammation have been reported to cause tracheomalacia. it is of relatively low incidence in adults, The clinical suspicion should be high when there has been a history of prolonged intubation with high cuff pressure and air leakage. When this clinical situation is encountered, rather than increasing the cuff pressure, the diagnosis of tracheomalacia should be considered.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.847-849
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• 2008

상수도시설은 준공후 관련지자체에 이관 관리하는 시설로서 사용관종이 현재 다양하게 생산 보급되고 있어 관종 선정시 다각적인 측면에서 검토하여 채택하여야 한다. 최근 한국토지공사에서 사용하고 있는 상수도 관종은 대부분 택지개발계획 등 인허가 당시부터 관리주체인 지자체 등과의 협의과정을 거쳐 선정되는 경우가 많아 자재선택에 한계성이 있다. 이를 극복하기 위해서는 자재 성능에 대한 공사내 명확한 기준이 제시되어야 한다. 따라서 본 연구에서는 공사가 시공하여 준공한 사업지구내 매설된 상수도 자재에 대한 샘플링조사를 통하여 적정한 관의 선정과 년도별, 관종별, 용도별 사용 현황을 파악하여 향후 대응방안을 마련하고, 기존 상수도관의 선정시 비교검토된 관의 제원(관의 재질 및 개요, 생산규격, 특성, 관접합 및 수밀성, 시공성, 경제성, 공사비, 관종선정(안) 결정)별 비교검토서를 보완 작성하고, 국내에서 생산되고 있는 각종 상수도관에 대한 정량적 분석을 수행하였다. 이를 통하여 상수도 관종 설계 및 시공에 대한 적용방안을 마련하였다.

• Tribology and Lubricants
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• v.20 no.2
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• pp.58-67
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• 2004

In this study a general Galerkin FE lubrication analysis method for the compressible Reynolds equation in cylindrical coordinates is presented. Then, the method is applied for analyzing lubrication performances of spiral groove dry gas seals. The effects of toning and number of groove on performance indices are evaluated at low and high rotating speeds: 3,600 and 15,000 rpm. Results show that, for the primary design consideration performances such as the opening force and axial and angular stiffnesses, a negative or small coning and a large number of groove are preferred.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.173-176
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• 1999

Vacuum insulated pipes (VIP) are one of the important equipments for cryogenic fluids' transfer. Flange type of VIP, which can easily be installed at the site, uses a set of male and female bayonet with very small gap between them. In order to prevent leakage of liquid from inner pipe to bayonet. Teflon or Kel-F is located outside both the inner pipe of male and the guide of female. Even though liquid may leak at room temperature, it cannot leak at cryogenic temperature since Teflon shrinks much more than pipes and adheres closely to the inner pipe and guide. Teflon seal method has the advantage of easy fabrication, low cost and effective sealing compared to the conventional method.

• The Journal of the Korean dental association
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• v.12 no.8
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• pp.613-617
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• 1974

The authors have studied the marginal leakage of various dental cements; Fynal cement (Caulk), Zinc cement (S.S. White) Carbo cement (Shofu, Poly-carboxylate cement), EBA cement (Opotow alumina cement), Propac (G-C's zinc oxide euginol cement), and Super cement (Shofu oxyphosphate zinc cement), by means of penetration of 2% methylene blue solution between orden crown restorations and human teeth in 150 cases. The result revealed as follow 1. None of the cements tested were free from dye penetration. 2. There was a wide difference in dye penetration among the trade brands of dental cement when immersed in dye solution before setting of cements. 3. EBA cement and Carbo cement showed comparatively low grade of dye penetration at the restorative margins.