• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1576-1580
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• 2007

Typical lip seals are widely used as sealing mechanism of rotary and reciprocating shaft. Double lip seal has comparatively high stiffness and dynamic radial eccentricity. Usually material of these seals is made of elastomer and nonlinear finite element analysis is required to analyze behaviour of this material because Young's modulus is varied with working load. In this paper, MSC MARC/MENTAT is used for nonlinear analysis of double lip seal with pressure variation and interference. The contact normal force of double lip seal between lip and shaft is analyzed to reduce power loss when shaft rotates.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2031-2037
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• 2011

최근의 냉장고 등에 채택되고 있는 프렌치 도어는 2개의 도어를 사용하지만, 내부에 칸막이가 없어 내부 공간을 효율적으로 사용할 수 있는 장점이 있다. 그러나 프렌치 도어는 2개의 도어와 몸체와의 밀폐를 위해 부착된 개스킷이 서로 간섭을 일으키기 때문에 개스킷의 마모로 인해 밀폐성능에 치명적인 영향을 미치고 도어의 개폐력이 증가되는 문제점이 있다. 본 연구에서는 프렌치 도어의 개폐를 위해 4절 링크기구의 동작을 이용한 개폐 메커니즘을 개발하였다. 또한, 개발된 4절 링크기구를 설계 및 제작한 후 실제 냉장고에 적용하여 간섭이 발생하지 않음을 검증하였고, 개방력도 저감됨을 확인하였다. 본 연구에서 제안된 메커니즘은 냉장고뿐만 아니라 프렌치 도어를 채택하는 다른 가전제품이나 산업제품에도 적용될 수 있다.

• Journal of Computational Design and Engineering
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• 제3권1호
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• pp.63-70
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• 2016

Deep drawing is a forming process in which a blank of sheet metal is radially drawn into a forming die by the mechanical action of a punch and converted to required shape. Deep drawing involves complex material flow conditions and force distributions. Radial drawing stresses and tangential compressive stresses are induced in flange region due to the material retention property. These compressive stresses result in wrinkling phenomenon in flange region. Normally blank holder is applied for restricting wrinkles. Tensile stresses in radial direction initiate thinning in the wall region of cup. The thinning results into cracking or fracture. The finite element method is widely applied worldwide to simulate the deep drawing process. For real-life simulations of deep drawing process an accurate numerical model, as well as an accurate description of material behavior and contact conditions, is necessary. The finite element method is a powerful tool to predict material thinning deformations before prototypes are made. The proposed innovative methodology combines two techniques for prediction and optimization of thinning in automotive sealing cover. Taguchi design of experiments and analysis of variance has been applied to analyze the influencing process parameters on Thinning. Mathematical relations have been developed to correlate input process parameters and Thinning. Optimization problem has been formulated for thinning and Genetic Algorithm has been applied for optimization. Experimental validation of results proves the applicability of newly proposed approach. The optimized component when manufactured is observed to be safe, no thinning or fracture is observed.

• Tribology and Lubricants
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• 제21권4호
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• pp.171-176
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• 2005

O-ring seal is an essential component in various mechanical apparatuses for a sealing of oil container and pressure vessels. This paper presents the sealing pressure and compressive contact behaviors of hi-polymer O-rings, which is made by an outer shell of FFKM material and an inner solid ring of FKM one. The contact normal pressure and its ratios are measured by experimental method with an automatic control system of the working temperature and analyzed numerically by using the non-linear Marc FEM program. The results show reasonably good agreements between the computed FEM results and measured ones when the operating temperature is kom normal temperature of $18^{\circ}C$ and a high temperature of $300^{\circ}C$ But the compared values between the computed and tested results show a little difference because of the increased temperature, which is related to the non-linear parameter of the O-ring material. Bi-polymer 0-ring shows a good contact normal stress and compression behavior for a given operation temperature and compression ratio.

• 한국분무공학회지
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• 제18권1호
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• pp.55-60
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• 2013

In this study, injection flow rates and material of the solenoid sealing of the injectors were improved for the development of a di-methyl Ether(DME) common-rail system. To deliver the same amount of energy provided by injection pressure of diesel $P_{inj}$ = 160 MPa, the DME injectors need to have larger diameter of nozzle hole and more No. of hole at low injection pressure of $P_{inj}$ = 40~50 MPa. The simplified nozzle flow model, which takes account of nozzle geometry and injection condition, was employed in order to design the concept of a injector nozzle such as No. of hole, diameter of hole and diameter of needle seat, etc. Injection amount and rate were tested by diesel and DME test stand. As a result, the diameter of nozzle hole were enlarged by 0.25 mm. The diameter of the orifice in the high pressure line was increased by 1.0 mm to maintain hydraulic force in the nozzle. The material of the solenoid sealing was changed to HNBR, which was strong against the corrosive. Experimental results showed that the injection amount of the DME injector drastically increased by 191.9% comparison to that of diesel at $P_{inj}$ = 40 MPa.

• 한국분무공학회지
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• 제27권4호
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• pp.181-187
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• 2022

For carbon neutrality, direct-injection hydrogen engines are attracting attention as a future power source. It is essential to estimate the transient injection rate of hydrogen for the optimization of hydrogen injection in direct injection engines. However, conventional injection rate measurement techniques for liquid fuels based on the injection-induced fuel pressure change in a test section are difficult to be applied to gaseous fuels due to the compressibility of the gas and the sealing issue of the components. In this study, a momentum flux measurement technique is introduced to obtain the transient injection rate of gaseous fuels using a force sensor. The injection rate calculation models associated with the momentum flux measurement technique are presented first. Then, the volumetric injection rates are estimated based on the momentum flux data and the calculation models and compared with those measured by a volumetric flow rate meter. The results showed that the momentum flux measurement can detect the injection start and end timings and the transient and steady regimes of the fuel injection. However, the estimated volumetric injection rates showed a large difference from the measured injection rates. An alternative method is suggested that corrects the estimated injection rate results based on the measured mean volumetric flow rates.

• 한국항공우주학회지
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• 제37권8호
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• pp.812-818
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• 2009

산화제 개폐밸브는 일반적으로 공압으로 포핏을 열고 닫음으로써 로켓엔진에 액체산화제유량을 제어한다. 상용되는 산업용 밸브와는 달리 현재 개발 중인 산화제 개폐밸브는 밸브는 효과적인 기밀을 위해 피스톤과 포핏이 접촉되어 있을 뿐, 분리되어 설계되어졌다. 밸브가 닫히는 동안 피스톤과 포핏이 떨어져서 움직이는 것을 피하고, 밸브의 전반적인 작동 성능을 파악하기 위해서 힘평형 해석이 수행되었다. 또한 더욱 정확한 해석을 위해, 마찰력과 포핏에 작용하는 힘을 각각 시험과 CFD 해석을 통해 구해내었다. 해석 결과를 통해 힘평형 해석에서 스프링, 마찰력과 공압부의 오리피스 크기와 같은 중요한 설계인자들의 영향을 알아보았으며, 현재 개발 설계중인 산화제 개폐밸브의 작동성능을 확인하였다.

• 한국기계가공학회지
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• 제9권3호
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• pp.83-88
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• 2010

This study aimed to enhance the durability by distributing the stress concentration at the contact and increasing the mechanical characteristics, as well as by changing the surface shape for LIP in the low-pressure seal among oil seals installed to the power steering of automotive. Accordingly, results were derived from comparisons and reviews with oil seals under the existing mass production by carrying out the performance tests after designs and productions are done with the addition of embo shapes on the surface of LIP in the low-pressure seal. As a result of this study, it has been identified that the durability of oil seals with the addition of embo shapes was enhanced with higher radial force and less variation in the internal diameter for the LIP. In addition, it was seen that the sealing ability for those oil seals is superior to the existing oil seals as their rotational torque values are less than those of the existing oil seals.

• Tribology and Lubricants
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• 제30권2호
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• pp.116-123
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• 2014

The objective of this study is to model and simulate the nonlinear lubrication performance of the sliding part between the piston and cylinder wall in a hydrostatic swash-plate-type axial piston pump. A numerical algorithm is developed that facilitates simultaneous calculation of the rotating body motion and fluid film pressure to observe the fluid film geometry and power loss. It is assumed that solid asperity contact, so-called mixed lubrication in this study, invariably occurs in the swash-plate-type axial piston pump, which produces a higher lateral moment on the pistons than other types of hydrostatic machines. Two comparative mixed lubrication models, rigid and elastic, are used to determine the reaction force and sliding friction. The rigid model does not allow any elastic deformation in the partial lubrication area. The patch shapes, reactive forces, and virtual local elastic deformation in the partial lubrication area are obtained in the elastic contact model using a simple Hertz contact theory. The calculation results show that a higher reaction force and friction loss are obtained in the rigid model, indicating that solid deformation is a significant factor on the lubrication characteristics of the reciprocating piston part.

• 대한기계학회논문집
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• 제17권8호
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• pp.1940-1950
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• 1993

The theoretical investigation is done on the dynamic behavior of a crank shaft used in a scroll compressor. The compression performance of a scroll compressor is directly influenced by the sealing characteristics between fixed and orbiting scrolls, which is related with the dynamic behavior of a scroll compressor. Analyzing the constrained power transmitting system is came to be of importance, accordingly. The equations of motion and interacting forces of a scroll compressor are derived and solved numerically in this paper. The locus of the crank shaft is also obtained by employing the reaction force caused by the oil film of journal bearing. The results show that the crank shaft of a scroll compressor has considerably stable rotating locus.