• 설비공학논문집
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• 제15권12호
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• pp.979-986
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• 2003

The performance characteristics of heating and cooling operation for a heat pump system using seawater heat source and exhaust energy are presented. The heat pump system is made of a waste heat recovery system and a vapor compression refrigeration system. The working fluid is R-22. The heat pump system COPs are measured during heating and cooling operation modes, and the resultant COPs were 9.7 and 7.9, respectively, which are three times higher than those of the heat pump itself. Therefore, the performance of the heat pump system using exhaust energy is excellent compared to that of a general heat pump. The experimental data can be effectively used for the design of the high efficient heat pump using a seawater heat source.

• Elastomers and Composites
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• 제52권4호
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• pp.280-286
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• 2017

The mechanical and dynamic properties according to the content of filler, plasticizer, and crosslinking agent of rubber composites for Lipseal were measured in this study. The mechanical properties of the composite including the silane coupling agent and silica were found to be superior to those of the composite containing carbon black. It was found that the rebound resilience characteristics were influenced by the crosslink density of sulfur rather than the filler or plasticizer. In the case of recovery, it was confirmed that the elastic restoring force improved in the compression deformation condition and recovery increased as the crosslinking density increased. The rubber composite for Lipseal of this study is expected to improve the manufacturing technology of the rubber composite which can implement the optimum function for recognizing the performance such as oil resistance, durability and compression set.

• 전자공학회논문지CI
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• 제44권6호
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• pp.10-18
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• 2007

데이터의 증가 추세와 중요성을 고려할 때, 효율적인 대용량의 백업시스템이 필요하다. 그러나 기존의 백업시스템들은 저장매체의 속도와 기술적인 문제 등을 갖고 있다 이러한 문제들을 해결하기 위하여 제안하는 고성능, 대용량 백업 및 복구시스템은 고속화, 압축 기술 및 백업 가속기 등을 이용하여 설계 및 구현하였다. 구현된 백업 및 복구시스템은 고속화를 위하여 멀티 쓰레딩 기술과 멀티 프로세싱 기술 그리고 멀티 스트리밍 기술을 적용하였다. 그리고 기존의 백업미디어가 테이프 기반이지만 제안하는 백업운영모델은 디스크기반으로 설계하였다. 때문에 구현된 백업시스템은 백업미디어의 한계를 극복하면서, 고속화 및 고용량이 가능하다.

• 한국공작기계학회논문집
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• 제10권5호
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• pp.96-103
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• 2001

The quality requirements for thickness accuracy in cold rolling continue to become more stringent, particularly in response to exacting design specification from automotive customers. One of the major impacts from the tighter tolerance level is more unusable product on the head end and tail end of tandem mill coils when the mill is in transition to or from steady state rolling condition. A strip thickness control system for a tandem cold steel rolling mills is composed with blocked non-interacting controller and controllers for strip thickness and tension control of each rolling stands. An intelligent mathematical model included an elastic deformation of strip has been developed and applied to the field in order to predict the rolling force. The simulated results showed that the effect of elastic recovery should be included the model, even if the effect of elastic compression was not important.

• 대한조선학회논문집
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• 제53권3호
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• pp.195-200
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• 2016

In this study, compression tests for the polyisocyanurate foam which is recognized as the insulation material for the storage tank of the liquefied natural gas (LNG) were carried out for investigation of the material characteristic of mechanical behavior. Deformation recovery ratio according to the various initial deformation levels were estimated and the mechanical behavior of foams that are experienced compressive deformation was also obtained experimentally. The test results were analyzed based on the conditions of initially applied strain level and engineering strain rate.

• 한국의류학회지
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• 제33권5호
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• pp.701-710
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• 2009

This study was conducted to develop excellent insole with good thermal insulation using new materials. We investigated that aerogel/fiber composite can be used as padding materials of shoes by comparing surface shape, moisture regain, water vapor permeability, thermal insulation and compression rate of insole materials tried with nonwoven fabric padding materials and insole sold in market. The results are as follows. Surface shapes were shown that the most appropriate material for sealing aerogel/fiber composite was high density fabric as per size of particle of aerogel. Moisture regain of aerogel/fabric composite was better than nonwoven fabric padding samples. However, when compared to insole sold in market, its moisture regain was worse than those of insole merchandises. Water vapor permeability was higher in material padded with nonwoven fabric than materials padded with aerogel/fiber composite in all three kinds of sealing fabrics. Thermal conductivity of aerogel/fabric composite was lower than nonwoven fabric material regardless of sealing fabrics. Thermal insulation of aerogel/fiber composite was higher than padding material of nonwoven fabric regardless of sealing fabrics. Compression rate of nonwoven (SP1) was higher than that of aerogel/fiber composite (SP2). Compressive elastic recovery rate of SP1 was also higher than that of SP2, which its compression rate and compressive elastic recovery rate were both poor. As the above result, ultra porous aerogel/fiber composite were proved to be material of good thermal insulation with lower thermal conductivity and also compression rate was proved to be low. Therefore, we can say that aerogel/fiber composite have high possibility to be used as insole materials for cold winter shoes requiring good thermal insulation protection.

• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1961-1971
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• 2006

A soft recovery system (SRS) is a device that stops a high speed projectile without damaging the projectile. The SRS is necessary to verify the shock resistant requirements of microelectronics and electro-optic sensors in smart munitions, where the projectiles experience over 20,000 g acceleration inside the barrel. In this study, a computer code for the performance evaluation of a SRS based on ballistic compression decelerator concept has been developed. It consists of a time accurate compressible one-dimensional Euler code with use of deforming grid and a projectile motion analysis code. The Euler code employs Roe's approximate Riemann solver with a total variation diminishing (TVD) method. A fully implicit dual time stepping method is used to advance the solution in time. In addition, the geometric conservation law (GCL) is applied to predict the solutions accurately on the deforming mesh. The equation of motion for the projectile is solved with the four-stage Runge-Kutta time integration method. A small scale SRS to catch a 20 mm bullet fired at 500 m/s within 1,600 g-limit has been designed with the proposed method.

• Korea-Australia Rheology Journal
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• 제18권4호
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• pp.183-189
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• 2006

High internal phase emulsions are highly concentrated emulsion systems consisting of a large volume of dispersed phase above 0.74. The rheological properties of high internal phase water-in-oil emulsions were measured conducting steady shear, oscillatory shear and creep/recovery experiments. It was found that the yield stress is inversely proportional to the drop size with the exponent of values between 1 and 2. Since the oil phase contains monomeric species, microcellular foams can easily be prepared from high internal phase emulsions. In this study, the microcellular foams combining a couple of thickeners into the conventional formulation of styrene and water system were investigated to understand the effect of viscosity ratio on cell size. Cell size variation on thickener concentration could be explained by a dimensional analysis between the capillary number and the viscosity ratio. Compression properties of foam are important end use properties in many practical applications. Crush strength and Young's modulus of microcellular foams polymerized from high internal phase emulsions were measured and compared from compression tests. Of the foams tested in this study, the foam prepared from the organoclay having reactive group as an oil phase thickener showed outstanding compression properties.

• Journal of Chest Surgery
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• 제25권10호
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• pp.1066-1069
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• 1992

The bronchogenic cyst is not so rare in incidence, but it is rare for this cyst to cause compression of trachea and main bronchi. A 6-year old female child was evaluated for coughing, fever and left total atelectasis. This patient had a history of frequent upper respiratory symptom like bronchial asthma since 6month after birth. Fiberoptic bronchoscopy revealed external compression at distal trachea and both main bronchi. Computed Tomography revealed well demarcated homogeneous mass compressing distal trachea and main bronchi. The pathological examination showed bronchogenic cyst and this patient had uneventful recovery.

• 대한치과보철학회지
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• 제34권4호
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• pp.657-664
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• 1996

The purpose of this study was to compare the dimensional stability, compression resistance, elastic recovery and surface hardness of elastomeric interocclusal recording materials. Five commonly used elastomeric interocclusal recording materials(Ramitec, Regisil, Blue-Mousse, Stat-Br, Coltoflax) were selected for this study. According to ADA specification No. 19, two types of specimen were fabricated. Cylinder type specimens were used to test compression resistance and elastic recovery and plate type specimens were used to evaluate dimensional stability and surface hardness. Paired t-test was applied to detect significance among the occlusal registration materials. The obtained results were as follows: 1. There were statistical difference in dimensional stability between the elastic interocclusal recording materials. The dimensional stability of silicone was higher than that of polyether tested(p<0.05). 2. Coltoflax was significantly less resistance to compression than the other elastic interocclusal recording materials(p<0.001). 3. The elastic recovery capacity of Blu-Mousse and Stat-Br is better than that of Coltoflax (p<0.01). 4. The surface hardness of Coltoflax was lower than that of Blu-Mousse and Stat-Br(p<0.05). 5. The percentage dimensional change of alll materials was acceptable according to the limid of 0.5% suggeted by ADA specificatin No. 19.