• Korean Chemical Engineering Research
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• v.60 no.2
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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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• v.42 no.2
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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.

• Journal of the Korean Society of Safety
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• v.27 no.2
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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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.268-275
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• 2020

In domestic mountain resort areas, a catenary system cannot be installed for the protection of the natural environment and view. Therefore, mountain trams must be operated wireless. In this study, a local ground pantograph, which supplies electricity to the battery on board, was developed for this purpose, and its performance was verified by tests. The system is installed on ground at stops or repair shops. While a bogie goes to the pantograph, the arms and collection shoes are raised by a spring force to make contact with the collection bar under the bogie so electric power can be supplied to the battery. Because it is a local ground type, it does not require a roof pantograph and catenary system. The system enables the mountain tram to run wireless. In addition, there is no separation and arc because it collects current while standing at stops or shops. The system has a long life because moving contact, which generates wear and damage to shoes, is avoided. The insulation resistance was above the criteria of 10 ㏁, and there was no abnormal temperature increase when a current of 335A was supplied for one hour.

• Korean Institute of Interior Design Journal
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• v.26 no.3
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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.

• Proceedings of the KSME Conference
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• 2001.06a
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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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• v.28 no.4
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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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1201-1207
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• 2010

As the mobile services have been increased, the PIMD(Passive Inter-Modulation Distortion) as well as the active-IMD of the CDMA system should be considered for the design of base station antenna systems, because they have an interference of the neighboring base stations. In this paper, in order to reduce the nonlinearity of current caused by the local point contact, we have investigated an influence of the combination of nuts, contact torque(kgf.cm), and the contact area on the PIMD. We propose the improvement techniques of PIMD by investigating the effects of the distance of nuts, the contact area, and the type of nuts.

• Herbal Formula Science
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• v.13 no.2
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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.

• Journal of agricultural medicine and community health
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• v.17 no.2
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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.