• Korean Chemical Engineering Research
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• 제60권2호
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• pp.277-281
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• 2022

The wetting dynamics of water droplets dispensed on the surface of dry and wet hydrophilic membranes were investigated experimentally from a microscale point of view. By using a high-speed, white-beam x-ray microimaging (WXMI) synchrotron, consecutive images displaying the dynamic motions of the droplets were acquired. Through analyzing the characteristics observed, it was found that the dry hydrophilic membrane showed local hydrophobicity at a certain point during the absorption process with apparent contact angles greater than 90. While on the other hand, the apparent contact angles of a water droplet absorbing into the wet membrane remained less than 90 and showed total hydrophilicity. The observations and interpretation of characteristics that affect the contact, wetting, recoiling, and dynamic behaviors of droplets are significant for controlling liquid droplet impingement in a desired manner.

• Journal of applied mathematics & informatics
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• 제42권2호
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• pp.305-320
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• 2024

We consider a mathematical model which describes the quasistatic contact of electro-viscoelastic rod with an obstacle. We use a modified Kelvin-Voigt viscoelastic constitutive law in which the elasticity operator is nonlinear and locally Lipschitz continuous, taking into account the piezoelectric effect of the material. We model the contact with a general damped response condition. We establish a local existence and uniqueness result of the solution by using arguments of time-dependent nonlinear equations and Schauder's fixed-point theorem and obtain a global existence for small enough data.

• 한국안전학회지
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• 제27권2호
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• pp.7-12
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• 2012

This paper describes electrical fire on electric pad caused by defect of hot wires. We analyzed two type electric pad using by carbon type hot wire and magnetic shielded type hot wire. First, a carbon type hot wires electric pad is virtually impossible to connect hot wire as a method of electrical welding or soldering. In order to connect between hot wires, that has to splice carbon type material connector. If junction of hot wires was occurrence of poor connection on electric pad, it increase contact resistance on this junction point. With increasing contact resistance, junction of hot wires on electric pad generates local heating and finally leads to electrical fire. An electric pad using by a magnetic shielded type hot wire happened local heating on signal wire for sensing temperature-rise caused by applying current for magnetic shielded. With increasing local heating of signal wire, insulated coating of hot wire was melted. Finally the magnetic shielded type hot wire electric pad lead to electrical fire with breakdown between signal wire and hot wire. In this paper, we analyzed shape of damage in hot wire caused by electrical local heating and investigated fire cause on electric pad due to defect of hot wires.

• 한국산학기술학회논문지
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• 제21권4호
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• pp.268-275
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• 2020

국내 산악 지역 자연공원에서는 자연 환경과 주변 조망을 보존하기 위해 전차선의 설치가 불가하다. 따라서 산악 트램은 무가선으로 운행되어야 한다. 이를 위해 본 연구에서는 차량의 추진 배터리에 전기를 공급할 수 있는 지상 집중식 급전장치를 개발하고 동작 및 기능 시험을 실시하여 성능을 검증하였다. 개발한 지상 집중식 급전장치는 검수고 또는 정거장의 한 지점에 고정 설치되어 있으며, 차량의 대차가 진입하여 정차하면 스프링 장력으로 암과 집전 슈를 올려 대차 하부에 있는 차량측 집전 바와 접촉하고, 전기를 흘려 배터리에 전력을 공급한다. 지상 집중식이므로 차량 지붕 위의 집전장치와 전차선이 필요 없게 되고, 산악트램은 무가선 상태로 운행을 할 수 있다. 정거장이나 검수고에서 움직이지 않고 정지한 상태에서 집전하므로, 이선이나 아크 발생이 없다. 집전 슈의 마모나 손상을 초래할 수 있는 가동 접촉면이 사라지게 되므로 집전장치 수명이 연장되는 장점이 있다. 시험 결과에 따르면, 절연저항은 기준치인 10㏁ 이상이었고, 전류 335A를 1시간 동안 일정하게 공급하여도 이상 발열이 없음을 확인하였다.

• 한국실내디자인학회논문집
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• 제26권3호
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• pp.55-62
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• 2017

As recently too many local museums have been built in the whole country, most of them cannot attract enough spectators. In order to resolve this problem, it is needed for local museums to differentiate their spaces and programs related to their exhibition. Thus, the purpose of this study was to analyze the characteristics of spaces and programs of local museums from the perspective of spatial marketing to activate them, and contribute to development of local cultures. This study targeted historical public museums located in Seoul and Incheon. Through preceding research, an analysis frame was established based on the keywords related to spatial marketing, and then the characteristics of spaces and programs of local museums were analyzed based on the frame. The study results are as follows. 1) Access convenience refers to openness that public museums located in Seoul and Incheon can embrace accessible locations, points of interest, and convenient facilities easily recognized by pedestrians. 2) Symbolic formativeness is to express symbolic historical contents in the museum lobby or exhibition to show the identity of local museums. 3) Visibility is needed for direct guidance signs or spaces to let spectators know directions and locations. 4) Public concern is for spectators and local residents to participate in local museums to share and utilize their partial spaces. 5) Interactivity is to induce activation of local museums by utilizing experience exhibition contents and having spectators directly contact exhibits. 6) Interest is related to cultural festival programs of exhibition to arouse spectators' and local residents' curiosity. 7) Participation is to activate spaces and spectators by providing educational programs. 8) Usefulness is to induce spectators' interest in local museums by providing historical, social, and cultural information. These results are expected to be used as baseline data to suggest a new direction for activation of local museums from the perspective of spatial marketing.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.561-566
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• 2001

A long bar impact test to alumina plates(AD 85 and AD 90) was carried out by using fabricated impact testing apparatus. The apparatus adopting a long bar of 2.1m in length made it possible to measure directly the applied impact force to the specimen during bar impact. The dimension of specimens was $33{\times}33mm$ and thickness was 3.4mm. Confinement of D2=18mm outer diameter and D1=10.5mm inner diameter was used to provide contact pressure to the specimen. Contact pressure of p=100 or 200MPa was applied to specimen before impact test. Damage caused in those cases were compared with the case of without contact pressure. The damage of specimen was different depending upon the pressure level of confinement. The existence of confinement had suppressed the development of radial cracks from the bottom of specimen and reduced the extent of damage as compared with cases without contact pressure(p=0MPa). Because the application of contact pressure to the specimen increased the apparent flexural stiffness of specimen during bar impact, it had produced the change of developed damage in the specimen; from the radial cracks to the local contact stress dominant damage. It would contribute to the improvement of the ballistic property in ceramic plates.

• Tribology and Lubricants
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• 제28권4호
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• pp.173-177
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• 2012

We used contact resonance force microscopy (CRFM) technique to determine the quantitative elastic properties of multiple materials integrated on the sub micrometer scale. The CRFM approach measures the frequencies of an AFM cantilever's first two flexural resonances while in contact with a material. The plain strain modulus of an unknown or test material can be obtained by comparing the resonant spectrum of the test material to that of a reference material. In this study we examined the following bumping materials for flip chip by using copper electrode as a reference material: NiP, Solder (Sn-Au-Cu alloy) and under filled epoxy. Data were analyzed by conventional beam dynamics and contact dynamics. The results showed a good agreement (~15% difference) with corresponding values determined by nanoindentaion. These results provide insight into the use of CRFM methods to attain reliable and accurate measurements of elastic properties of materials on the nanoscale.

• 한국전자파학회논문지
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• 제21권11호
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• pp.1201-1207
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• 2010

이동 통신 서비스가 확대됨에 따라 인접 기지국 간의 간섭 문제가 증가하게 되었으며, 그에 따라 CDMA 시스템의 능동 상호 변조 왜곡(AIMD: Active Inter-Modulation Distortion)뿐만 아니라 수동 상호 변조 왜곡(PIMD: Passive Inter-Modulation Distortion)에 대한 문제도 기지국 안테나 시스템 설계 시 고려되어야 한다. 본 연구에서는 기지국 안테나에 사용되는 도체와 도체 조립에 있어 국부적인 전류 비선형을 유발하는 전류 밀도의 특성을 분석하였고, 전류 비선형성을 낮추기 위한 방법을 연구하였다. 이를 통하여 안테나 구조의 도체-도체 결합을 위한 넛트의 간격, 면적 등이 미치는 영향을 분석하여 수동 상호 변조 왜곡의 개선 방향을 제안한다.

• 대한한의학방제학회지
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• 제13권2호
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• pp.59-69
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• 2005

Samyoyongantang (SMY), a herbal medicine, has been used as cure for gangrene. To evaluate anti-inflammatory effect of samyoyongantang, we treated samyoyongantang extract in animal model system induced contact hypersensitivity. Contact hypersensitivity, a local inflammatory response of the skin, was induced by 1% DNCB on the right ear of BALB/c mouse. Samyoyongantang was prepared as water extract and administrated everyday for 2 weeks per oral. A right ear of mouse was potently swelled by 1% of DNCB treatm ent, but a mouse ear thickness was significantly reduced by samyoyongantang after 2 we eks treatment. Samyoyongantang reduced IgG in serum obtained from blood of 1 % DNCB-treated mouse. IgE in serum was not changed by samyoyongantang treatment. From these results, anti-inflammatory effect of samyoyongantang, especially reduction of ear swell ing, might be partly due to reduction of IgG in serum.

• 농촌의학ㆍ지역보건
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• 제17권2호
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• pp.113-121
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• 1992

In order to estimate the pattern of medical care utilization and recognition for health factor among the inhabitants in Wan-do district which is located off the southern seashore from mainland Korea, household interview survey was performed from January 15 to 30, 1990 in Wan-do Gun area. The results observed were following: 1. Among the users of medical facilities 40.8% used public health facility as first contact facility. Lower the income level was and longer the residency duration was, the utilization rate of public health facilities was higher. By age groups and medical security status the utilization pattern was likely to disperse to local clinic and secondary contact medical resources. 2. Medical expense and access time were significantly different between primary contact and secondary contact medical resources. 3. Public health facility was recognized as the favoured institute having advantage of geographic and economic accessibility. 4. Statistically significant determinants in public health facility utilization among total medical service were the region, the medical expense, and the access time.