• 설비공학논문집
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• 제13권12호
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• pp.1306-1318
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• 2001

This paper presents leakage and performance characteristics of a tip-seal type scroll compressor, The performance of a scroll compressor is strongly dependent on the leak age across the compression pockets. However, literature for leakage characteristics of the tip seal type scroll compressor is very limited due to complex sealing mechanism. In the present study, a simulation study was executed to investigate the tip-seal type scroll compressor by considering leakages passing through flank and tip clearance. As a result, the leakage phenomena of the tip seal type scroll compressor as a function of discharge pressure, tip clearance, dimension of the tip seal were analyzed. Effects of leakage on the performance of the compressor were also clarified.

• 방사성폐기물학회지
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• 제18권2_spc호
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• pp.237-245
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• 2020

사용후핵연료를 저장하는 볼트체결 저장용기의 격납경계를 형성하는 주된 구성요소는 금속 밀봉재이다. 이러한 금속 밀봉재는 열과 방사선에 의해 그 성질이 저하된다. 또한, 금속 밀봉재가 강한 열에 장기간 노출되면 크리프 현상이 발생한다. 이러한 크리프는 밀봉시스템에 응력 이완을 가져와서, 결국 밀봉재의 건전성을 해치게 된다. 이러한 응력 이완은 금속 밀봉재의 밀봉성능 저하로 이어지며, 저하의 정도에 따라 저장용기의 누설을 야기할 수 있다. 또한, 볼트 체결력의 감소도 밀봉성능 저하에 영향을 미친다. 본 논문에서는 금속 밀봉재의 격납건전성과 볼트체결력 감소를 평가하기 위해 수행한 가속화 시험의 결과에 대하여 기술한다. 전 시험기간 동안 각 시편에서의 누설률, 볼트 변형률, 금속 밀봉재 주변 온도를 계측하여 분석하였고, 금속 밀봉재는 저장기간 50년 동안 격납건전성을 유지함을 입증하였다. 또한, 가속화 시험의 타당성에 대해서 기술하였다.

• 대한기계학회논문집A
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• 제24권12호
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• pp.2989-2994
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• 2000

A mechanical face seal is a tribo-element intended to control leakage of working fluid at the interface of a rotating shaft and its housing. Leakage of working fluid decreases drastically as the clearance between mating seal faces gets smaller. But the very small clearance may result in an increased reduction of seal life because of high wear and heat generation. Therefore, in the design of mechanical face seals a compromise between low leakage and acceptable seal life is important, ant it present a difficult and practical design problem. A fluid film or sealing dam geometry of the seal clearance affects seal lubrication performance very much, and thereby is optimization is one of the main design consideration. in this study the Reynolds equation for the sealing dam of mechanical face seals is numerically analyzed, using the Galerkin finite element method, which is readily applied to various seal geometries, to give lubrication performances, such as opening force, restoring moment, leakage, and axial and angular stiffness coefficients. Then, to improve the seal performance an optimization is performed, considering various design variables simultaneously. For the tested case the optimization ha successfully resulted in the optimal design values of outer and inner seal radii, coning, seal clearance, and balance radius while satisfying all the operation subjected constraints and design variable side-constraints, and improvements of axial and angular stiffness coefficients by 16.8% and 2.4% respectively and reduction of leakage by 38.4% have been achieved.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1159-1162
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• 2003

Recently we suffered lot of failures of polymer surge arresters made by same manufacture after one year field operation. In order to set up countermeasures we investigated the causes of failures. We extracted faulted arresters and sound ones which were installed in same pole with faulted ones for the electrical test and dissection. 44 arresters were removed from 8 branch offices. Almost all of faulted arresters hadtracking damage on the interface between inner module and housing and the surface of inner module was very rough and irregular. It was possible to occur moisture ingress into the interface between inner module and housing due to the void of the interface and non tight sealing caps. Lots of sound arresters were failed during the moisture ingress test. This result must relate with tracking damage of faulted arresters. Therefore we can say that arresters had poor interface and sealing system. But we could not found aging and defects of ZnO elements because the electrical performance except moisture ingress test of arresters showed good.

• 설비공학논문집
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• 제26권3호
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• pp.137-143
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• 2014

A gasket is known as an important component for mechanical sealing between mating surfaces. In case of the refrigerator, a gasket is generally installed into the edge line of a door to prevent cold air leaking out from the inside of a cabinet. The gasket shape used in a refrigerator is very complicated; it has a few deformable small rooms and wings (upper part) and inserting part (lower part) into the door. By the intricate shape, it takes much time and trouble on analysis by using a full-shape model. To settle down this problem, an effective design way of a gasket is proposed in this work. The inserting part is parametrically designed using FEM without considering the complicate upper part, Through this work, computational time and efforts are much reduced comparing to the full-shape analysis method. And the performance of a newly designed gasket was evaluated qualitatively.

• 한국전산유체공학회지
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• 제20권4호
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• pp.102-108
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• 2015

Recently, There are many studies in progress in order to improve the efficiency of the gas turbine. Leakage in losses of the gas turbine account for the largest proportion. Seal is a sealing device to reduce the flow from leaking by the pressure difference inside the turbine. Compressor has another value according to the shape and pressure conditions in each stage. Thus, it is necessary to seal design for boundary conditions in order to minimize leakage. At the actual operating conditions of the compressor, numerical analysis of honeycomb labyrinth seal was performed in accordance with pressure, temperature, rotor speed for CFD. As a result, when the temperature increases, the leakage is decreased. Also, when the pressure increases linearly with increased leakage, and there was no effect of the rotation speed.

• 한국기계가공학회지
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• 제17권1호
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• pp.8-15
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• 2018

Recently, the manufacturing market for low-cost airlines has led to an increase in aircraft demand. Most processes in the production of these aircrafts are manual such as drilling, sealing, and swaging. A drilling and riveting machine is a numerical-control based equipment that automatically performs drilling, sealing, and swaging operations. The accuracy of the drilled holes and the exit burr length has a significant impact on the quality of the aircraft wing during assembly. This study was conducted to identify the conditions necessary to maintain a uniform quality by controlling the rotation speed of the spindle, which directly affects the hole diameter and the quality of the exit burr.

• 한국생산제조학회지
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• 제19권3호
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• pp.365-369
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• 2010

Magnetic fluid seal is characterized by its simple design, low friction and being dustless. Those advantages are deduced from the fact that the sealing element is not a solid such as rubber or plastic but it is a fluid. Those are critical for application to a rotating shaft which is inserted into a vacuum chamber where high level of vacuum and cleanness are required. For the reason the magnetic fluid seal has become a standard for vacuum chambers for semiconductor and LCD processing. It should be noted that its sealing performance is sensitive to temperature. If necessary, water cooling should be considered. Thus anticipation of the temperature distribution of the magnetic fluid seal is important before applying it. In this paper an FEM analysis of the heat transfer has been executed and compared with experimental results. An overall convective heat transfer coefficient has been adopted for the analysis, which results in satisfactory consistency of the theoretical and experimental results.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.390-391
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• 2006

This paper describes the design, fabrication and characteristics of a micromachined piezoelectric valve utilizing a multilayer ceramic actuator (MCA). The micromachined MCA valve, which uses a buckling effect, consists of three separate structures: the MCA, the valve actuator die and the seat die. The valve seat die with 6 trenches was made, and the actuator die, which is driven by the MCA under optimized conditions, was also fabricated. After Si wafer direct bonding between the seat die and the actuator die, the MCA was also anodically bonded to the seat/actuator die structure. A polydimethylsiloxane (PDMS) sealing pad was fabricated to minimize the leak rate. Finally, the PDMS sealing pad was also bonded to the seat die and the stainless steel package. The MCA valve shows a flow rate of 9.13 sccm at an applied DC voltage of 100 V with a 50% duty cycle and a maximum non-linearity of 2.24% FS. Therefore, the fabricated MCA valve is suitable for a variety of flow control equipment, as a medical bio-system and in the automobile industry.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.528-533
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• 1988

Recently the needs for industrial robot system of high speed continuous path motion such as sealing application have been increasing. To apply to this kinds of work, dynamic analysis for Hyundai 8601 robot has been carried out by experiment. For the good design of high performance robot manipulator, accurate analysis of dynamic characteristics is important especially for current semi-closed loop control type industrial robots.