• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.366-370
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• 2002

GaAs has become a very popular material for the fabrication of high frequency, low noise and microwave power devices. GaAs devices are also well suited for high temperature operation because of the large band gap of this material. The standard GaAs technology and device structures have to be modified for stable operation at high temperature. In this paper, AlGaAs/GaAs HBT considering stable ohmic contact at high temperature as well as thermal effect such as self-heating effect are introduced. All the data obtained study will be used as input data for the simulator and the result will be compared with an analytical model available in this study,

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.297-300
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• 2006

This article discusses about the droplet movement on the super-hydrophobic surface by the electro-wetting on dielectric and the effect of particles on the contact angle as well as the movement is investigated. The movement of droplet, driven by the principle of electro-wetting on dielectric, and the effect of particles are experimentally verified according to the driving voltage and different particles concentrations (fluorescent, charged particles). To increase the contact angle, the super-hydrophobic surface is fabricated and applied to the dielectric layer for the EWOD device. Then its performance is verified and discussed.

• Journal of the Semiconductor & Display Technology
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• v.5 no.1 s.14
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• pp.21-25
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• 2006

To improve the performance of organic thin film transistor, we investigated the properties of gate insulator's surface according to the leakage current by I-V measurement. The surface was treated by the dilute n-octadecyltrichlorosilane solution. The alkyl group of n-octadecyltrichlorosilane induced the electron tunneling and the electron tunneling current caused the breakdown at high electric field, consequently shifting the breakdown voltage. The 0.5% sample with an electron-rich group was found to have a large leakage current and a low barrier height because of the effect of an energy barrier lowered by, thermionic current, which is called the Schottky contact. The surface properties of the insulator were analyzed by I-V measurement using the effect of Poole-Frankel emission.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.613-617
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• 2000

This paper descries the effect of the stylus tip size on the measuring error in surface topography measurement. To analyze the distortional effect of an actual surface geometry originating from the finite stylus size, the surface is modeled as a sinusoid and the stylus tip as a circle. the measuring error is defined as the ratio of the standard deviation of a tracing profile and an original profile. It is shown that this measuring error depends on the amplitude and wavelength of an original profile. In this paper, the spectrum analysis is applied to investigate the distortional effect due to the mechanical filtering of the stylus in the frequency domain. and, the cumulative power spectrum is applied to determinate the minimum wavelength limits to be measured with the various stylus tip radius from these results, a new method to select proper stylus tip radius is proposed.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.251-253
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• 2002

We have fabricated a novel Vertical Trench Hall-Effect Device sensitive to the magnetic field parallel to the sensor chip surface for non-contact angular position sensing applications. The Vertical Trench Hall-Effect Device is built on SOI wafer which is produced by silicon direct bonding technology using bulk micromachining, where buried $SiO_2$ layer and surround trench define active device volume. Sensitivity up to 150 V/AT is measured.

• Journal of the Semiconductor & Display Technology
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• v.17 no.3
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• pp.17-20
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• 2018

IGZO thin films were prepared on n-type Si substrates to research the interface characteristics between IGZO and substrate. After the annealing processes, the depletion layer was formed at the interface to make a Schottky contact owing to the electron-hall fair recombination. The carrier density was decreased by the effect of depletion layer and the hall mobility decreased during the deposition processes. But the annealing effect of depletion layer increased the hall mobility because of the increment of potential barrier and the extension of depletion layer. It was confirmed that it is useful to observe the depletion effect and Schottky contact's properties by complementary using the Hall measurement and I-V measurement.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.53-68
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• 2004

Protein deposit buildup on soft contact lenses(SCLs) is responsible for discomfort, optical defects and is even damaging to the eye. To better understand protein deposit formation on SCL, we investigated the pattern of protein attachment on patient-worn SCLs and the effect of the protein on the contact angle of SCLs and the transmission of visible light. This study used data from a clinical trial where subjects wore either daily-wear SCL(etafilcon A, N=40) for various period up to 14 days, or extended-wear SCL(balafilcon A, N=40) for 8 h day or night. The adsorption of protein in daily-wear SCLs was significantly increased in patient-worn time-dependent manner although the lenses were cleaned everyday by using the multi-purpose SCL solution. After 2 weeks wearing, the protein on the SCL influenced the contact angle of the lenses. Furthermore, the transmission of visible light of the lenses decreased up to almost 7%. Extended-wear SCLs worn during the closed eye condition were found to deposit significantly more protein than SCLs worn during the open eye condition. The amounts of protein adsorbed both after daily SCL wear and after overnight SCL wear were not affected the contact angle and the transmission of visible light of the lenses. The protein deposit buildup on SCL related to the corneal temperature and pH of tear fluid.

• Journal of Digital Convergence
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• v.16 no.1
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• pp.187-195
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• 2018

The purpose of this study was to identify the moderated effects of multicultural contact experience on the relationship between social distance and multicultural acceptability among nursing students. The sample for this study consisted of 174 nursing students from four universities located in Korea. Data were analyzed by descriptive statistics, t-test, ANOVA, $Scheff{\acute{e}}$ test, Pearson correlation and hierarchical multiple regression with SPSS/WIN 23.0. It was found that: (a) multicultural acceptability had a negative correlation with social distance(r=-.61, p<.001), whereas a positive correlation was observed with experience of multicultural contact(r=.24, p=.002); (b) the interaction effect by multicultural contact experience and social distance had a significant influence on the multicultural acceptability(${\beta}=-.18$, p=.003); (c) experience of multicultural contact moderated the relationship between social distance and multicultural acceptability(${\Delta}R^2=0.30$, p=.003). Results of the study suggest that the greater the experience of multicultural contact, the greater the negative effect of social distance on multicultural acceptability. Therefore, to increase the multicultural acceptability of nursing students, it is important to encourage the positive experiences of multicultural contact and thus reduce social distance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.480-480
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• 2008

Vacuum circuit breaker(VCB) is now emerging as an alternative of gas circuit breaker(GCB) which uses SF6 gas as insulating material whose dielectric strength is outstanding. But we have to reduce SF6 gas because SF6 gas is one of greenhouse gas and efforts to reduce greenhouse gas are now trend of the world. Therefore, we can say VCB is the optimal alternative of GCB because vacuum is environmentally friendly. The vacuum interrupter is the core part of VCB to interrupt arcing current. There are mainly two methods to extinguish arc. One is radial magnetic field (RMF) method and the other is axial magnetic field (AMF) method. We deals with RMF method in this paper. Compared with AMP, RMF arc quenching method has different principle to extinguish arc. In case of RMF method, pinch effect is much larger than AMF method. Because of pinch effect RMF type contact electrodes have the single large spot which is severly damaged and melted while AMF type contact electrodes have small and multiple spots which are slightly damaged and melted. To prevent contact electrode being damaged and melted from high temperature-arc, RMF method uses Lorentz force to move arc. In this paper we calculated and compared the arc driving force of two cases and we analyzed the force acting on each part of arc by means of commercial finite element method software Maxwell 3D. They have 3petals and we considered two cases. One is the case when fixed(upper) and movable(lower) contacts are in mirror arrangement (Case 1). The other is the case when one of two contacts (movable contact) is revolved at maximum angle as possible as it can be (Case 2). And at each case above, we analyzed arc driving force at two positions, position 1 is the closest to the center of contact and position 2 is near the edge of petal on fixed contact. As a result we could find that Case 2 generated stronger arc driving force than Case 1 at position 1. But at position 2 Case 1 generated stronger arc driving force than Case 2. This simulation method can contribute to optimizing spiral-type electrode designs in a view of arc driving force.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.22 no.1
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• pp.46-61
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• 2009

Background and Objectives : Allergic Contact Dermatitis is the disease affected by industrialization. The more industrialization advanced, the more materials that could induce the allergic contact dermatitis have been increased. Therefore in oriental medicine, various studies have been performed. The objective of this study is to investigate the effects of Naetakchunkeum-san on the Allergic Contact Dermatitis induced by 2,4-dinitro-chlorobezene(DNCB). Meterial and Methods : Twenty eight mice were divided into four groups ; normal, control, experimental group A and B. Control and experimental group were induced allergic contact dermatitis by DNCB. Experimental group A was orally administered the Naetakchunkeum-san and experimental group B was orally administered the prednisolone. In this study, ear thickness measurement, observation auricle microphotograph, Myeloperoxidase(MPO) activity measurement, Reverse transcription-polymerase chain reaction(RT-PCR) analysis of the mRNA level of $TNF-\alpha$, $IL-1\beta$, $INF-\gamma$ were performed on these four groups. In addition, the effect of Naetakchunkeum-san on cell viability and the effect of Naetakchunkeum-san on the compound 48/80-induced histamine release from HMC and RPMC were measured, Results : 1. In contact hypersensitivity assay, experimental group A and B showed decreased ear thickness compared with control group, 2. In experimental group A, pathological lesion of dermatitis were alleviated. In addition, the numbers of infiltrated cells were reduced, and cleft was not shown compared with control group, In experimental group B, similar results were shown. 3. There was a significant increase in MPO activity in control group compared with normal group, Experimental group A and B significantly inhibited the increase in MPO activity compared with control group. 4, The level of expression of $TNF-\alpha$, $IL-1\beta$, $INF-\gamma$ in experimental group A and B were significantly lower than those in control group. As the internal control, cyclophilin mRNA was also reverse-transcribed and amplified. 5, In MTT assay, there were no statistically significant differences in 100 ${\mu}g/ml$, 200 ${\mu}g/ml$, 500 ${\mu}g/ml$, 1000 ${\mu}g/ml$ Naetakchunkeum-san treated group from 0 ${\mu}g/ml$ Naetakchunkeum-san treated group as determined by the Tukey test. 6. Naetakchunkeum-san dose-dependently inhibited the compound 48/80-induced histamine release from both HMC and RPMC. Conclusions : According to above experiments, Naetakchunkeum-san may be applied to allergic contact dermatitis.