• Biomolecules & Therapeutics
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• 제16권1호
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• pp.14-20
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• 2008

In the present study, we examined how the transport of choline is regulated at the blood-brain barrier (BBB) under the central nervous system (CNS) cellular damages by oxidative stress using a conditionally immortalized rat brain capillary endothelial cells (TR-BBB), in vitro the BBB model. It was also tested whether the choline uptake is influenced by membrane potential, extracellular pH, protonophore (FCCP) and amiloride in TR-BBB cells. In result, $[^3H]choline$ uptake was inhibited by FCCP and dependent on extracellular pH. The treatment of TR-BBB cells with 20 ng/mL tumor necrosis $factor-{\alpha}$ $(TNF-{\alpha})$, 10 ng/mL lipopolysaccharide (LPS), 100 ${\mu}M$ diethyl maleate (DEM) and 100 ${\mu}M$ glutamate resulted in 3.0-fold, 2.6-fold, 1.8-fold and 2.0-fold increases of $[^3H]choline$ uptake at the respective peak time, respectively. In contrast, hydrogen peroxide and raffinose did not show any significant effects on choline uptake. In addition, choline efflux was significantly inhibited by $TNF-{\alpha}$, LPS and DEM producing cell damage states. In conclusion, the influx and efflux transport system for choline existed in TR-BBB cell line and this process was affected by several oxidative stress inducing agents.

• 한국콘텐츠학회논문지
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• 제8권9호
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• pp.259-273
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• 2008

경제의 발전과 더불어 산업사회가 고도화 되면서 국민소득의 증가, 여가시간의 증가, 여성의 취업 증가 등의 변화에 따라 국민의 생활수요도 다양해지고 있다. 이러한 수요의 변화에 따라 서비스 산업은 여러 형태로 발전하면서 오늘날 현대 경제는 서비스 경제 또는 서비스 사회라고도 불리어 지고 있다. 이는 서비스 산업이 경제 전체에서 차지하는 비중이 확대되고 서비스 산업의 범위가 넓어지고 있고 현대사회에서 서비스 산업의 중요성이 크게 부각되고 있기 때문이다. 이러한 서비스 산업의 경우 최근 경쟁이 치열해지고 브랜드에 대한 충성도가 감소함에 따라 신규고객 유치와 시장점유율 확대 등의 공격적 마케팅전략 보다는 기존고객 유지의 방어적 마케팅 전략의 중요성이 커지고 있다. 특히 여행사와 항공사의 경우 많은 경쟁과 성수기, 비수기의 수요 양극화 현상 등으로 인하여 서비스전환의 용이성이 증가함에 따라 기존 고객을 유지하고 전환을 억제하는 것이 더욱 중요시되고 있는 실정이다. 이에 본 연구는 고객특성에 따른 전환장벽과 전환의도 그리고 재방문 의사의 관계에 대하여 연구하여 업계에 도움이 되는 시사점을 찾고자 하였다.

• 한국전기전자재료학회논문지
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• 제31권6호
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• pp.362-366
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• 2018

Silicon carbide is widely used in power semiconductor devices owing to its high energy gap. In particular, Schottky barrier diode (SBD) and PiN diodes fabricated on 4H-SiC wafers are being applied to various fields such as power devices. The characteristics of SBD and PiN diodes can be extracted from C-V and I-V characteristics. The measured Schottky barrier height (SBH) was 1.23 eV in the temperature range of 298~473 K, and the average ideal factor is 1.17. The results show that the device with the Schottky contact is characterized by the theory of thermal emission. As the temperature increases, the parameters are changed and the Vth is shifted to lower voltages.

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.241-245
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• 2022

In this study, we measured and comparatively analyzed the characteristics of MPS (Merged Pin Schottky) diodes in 4H-SiC by changing the areal ratio between the Schottky and PN junction region. Increasing the temperature from 298 K to 473 K resulted in the threshold voltage shifting from 0.8 V to 0.5 V. A wider Schottky region indicates a lower on-resistance and a faster turn-on. The effective barrier height was smaller for a wider Schottky region. Additionally, the depletion layer became smaller under the influence of the reduced effective barrier height. The wider Schottky region resulted in the ideality factor being reduced from 1.37 to 1.01, which is closer to an ideal device. The leakage saturation current increased with the widening Schottky region, resulting in a 1.38 times to 2.09 times larger leakage current.

• BMB Reports
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• 제45권3호
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• pp.200-205
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• 2012

Enzymatic oxidation of commercially available pyrogallol was efficiently transformed to an oxidative product, purpurogallin. Purpurogallin plays an important role in inhibiting glutathione S-transferase, xanthine oxidase, catechol O-methyltransferase activities and is effective in the cell protection of several cell types. However, the anti-inflammatory functions of purpurogallin are not well studied. Here, we determined the effects of purpurogallin on lipopolysaccharide (LPS)-mediated proinflammatory responses. The results showed that purpurogallin inhibited LPS-mediated barrier hyper-permeability, monocyte adhesion and migration and such inhibitory effects were significantly correlated with the inhibitory functions of purpurogallin on LPS-mediated cell adhesion molecules (vascular cell adhesion molecules, intracellular cell adhesion molecule, E-selectin). Furthermore, LPS-mediated nuclear factor-${\kappa}B$ (NF-${\kappa}B$) and tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) releases from HUVECs were inhibited by purpurogallin. Given these results, purpurogallin showed its anti-inflammatory activities and could be a candidate as a therapeutic agent for various systemic inflammatory diseases.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.262-265
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• 1999

We report the activation energies which is calculated by adding a term being neglected usually, and magnetic relaxation effects for the surface barrier. The activation energies U at initial magnetization m (m$_{en}$ and m$_{ex}$) and equilibrium magnetization m$_{eq}$ are nearly similar to those of Burlachkov, but the m dependence of the activation energy U is remarkably different. The relaxation effects, which were determined by the m dependence of the activation energies U, are nonlinear for vortex entry, but linear at the initial stage and nonlinear at m(Int) ${\simeq}$ m$_{eq}$ for vortex exit. During relaxation process, the vortex entry at m = m$_{en}$ is faster than the vortex exit at m = m$_{ex}$ by about factor 90. The vortex exit at m = m$_{eq}$ is faster than one at m = m$_{ex}$ by about factor 1.3

• 방사성폐기물학회지
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• 제14권1호
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• pp.11-19
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• 2016

This paper focuses on the estimation of durability and service-life of reinforced concrete structures in Wolsong Low- and intermediate-level wastes Disposal Center (WLDC) in Korea. There are six disposal silos located in the saturated environment. The silo concrete is degraded due to reactions with groundwater and chemical attacks, and finally it will lose its properties as a transport barrier. The infiltration of sulfate and magnesium, leaching of potassium hydroxide, and chlorine induced corrosion are the most significant factors for degradation of reinforced concrete structure in underground environment. From the result of evaluation of the degradation time for each factor, the degradation rate of the reinforced concrete due to sulfate and magnesium is $1.308{\times}10^{-3}cm/yr$, and it is estimated to take 48,000 years for full degradation while potassium hydroxide is leached in depth of less than 1.5 cm at 1,000 years after the initiation of degradation. In case of chlorine induced corrosion, it takes 1,648 years to initiate corrosion in the main reinforced bar and 2,288 years to reach the lifetime limit of the structural integrity, and thus it is evaluated as the most significant factor.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1998년도 춘계종합학술대회
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• pp.405-408
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• 1998

본 논문에서는, 백금 실리사이드와 실리콘 접합에서 n형 실리콘 기판의 농도와 온도 변화(상온, 55$^{\circ}C$, 75$^{\circ}C$)에 따라서 전류-전압 특성을 분석하였다. 측정한 전기적 파라미터들은 순방향 임계전압, 역방향 항복전압, 장벽높이(øbn), 포화전류, 이상인자와 동적저항의 변화이다. 결과로써, 기판 농도의 변화에 따라서는 순방향 임계전압, 역방향 항복전압, 장벽 높이, 동적저항은 감소하였으나 포화전류와 이상인자는 증가하였다. 온도 변화에 따라서는 역방향 항복전압과 동적저항이 증가하였다.

• Journal of Periodontal and Implant Science
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• 제26권1호
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• pp.80-88
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• 1996

The aim of the present investigation was to see the effect of combined use of PDGF BB and IGF -1 on the guided tissue regeneration(GTR) using barrier membrane in the treatment of human furcation involvement. Twelve patients with initially diagnosed as having moderate to advanced adult periodontitis with mandibular class II buccal furcation defects have been wer selected. Initial scaling and root planing has been performed and baseline data consisting of probing depths and attachment levels have been recorded prior to surgical procedures. The GTR procedures using either barrier membrane(control : ePTFE) alone or together with the application of PDGF - BB and IGF -l(experimental : ePTFE+PDGF/IGF) have been done under the routine guidelines. During the surgery, the distance from CEJ either to the bottom of the bone defects(CEJ - BD) or to the bone crest(CEJ-BC) were measured. Horizontal distance to the deepest area in the furcal defects were measured from the reference line connection the most prominent bony walls of the two buccal roots. 6 months following the GTR therapy, all the measurements were made repeatedly. The probing attachment gain of the experimental and the control grous were 2.14mm and l.07mm, respectively with no statically significnant difference. Amont of vertical bone fill in the experimental and the control groups were 2.43mm and 2.29mm, rexpectively. Amonut of horizontal bone fill were 2.86mm in the experimental group and 2.17mm in the control group, respectively. However, there were no significant differences in the amount of bone fill(both vertical and horizontal)between the two groups.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.65-65
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• 2009

High temperature silicon carbide Schottky diode was fabricated with Au deposited on poly 3C-SiC thin film grown on p-type Si(100) using atmospheric pressure chemical vapor deposition. The charge transport mechanism of the diode was studied in the temperature range of 300 K to 550 K. The forward and reverse bias currents of the diode increase strongly with temperature and diode shows a non-ideal behavior due to the series resistance and the interface states associated with 3C-SiC. The charge transport mechanism is a temperature activated process, in which, the electrons passes over of the low barriers and in turn, diode has a large ideality factor. The charge transport mechanism of the diode was analyzed by a Gaussian distribution of the Schottky barrier heights due to the Schottky barrier inhomogeneities at the metal-semiconductor interface and the mean barrier height and zero-bias standard deviation values for the diode was found to be 1.82 eV and $s_0$=0.233 V, respectively. The interface state density of the diode was determined using conductance-frequency and it was of order of $9.18{\times}10^{10}eV^{-1}cm^{-2}$.