• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.5
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• pp.521-526
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• 1999

It was investigated that traps were generated inside of the oxide and at the oxide interfaces by the stress bias voltage. The charge state of the traps can easily be changed by application of low voltage after the stress high voltage. It determined to the relative traps locations inside the oxides ranges from 113.4$\AA$to 814$\AA$ with capacitor areas of $10^{-3}{$\mid$textrm}{cm}^2$. The traps are charged near the cathode with negative charge and charged near the anode with positive charge. The oxide charge state of traps generated by the stress high voltage contain either a positive or a negative charge.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.1
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• pp.13-18
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• 1999

The trap density by the stress bias in silicon oxides with different thicknesses has been investigated. The trap density by stress bias was shown to be composed of on time current and off time current. The on time trap density was composed of dc current. The off time trap density was caused by the tunneling charging and discharging of the trap in the interfaces. The on time trap density was used to estimate to the limitations on oxide thicknesses. The off time trap density was used to estimate the data retention in nonvolatile memory devices.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.335-345
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• 1996

A critical role of oxygen-derived free radicals has been implicated in ischemia/reperfusion (I/R)-induced brain damage. In this study, we have produced experimental I/R to the brains of Mongolian gerbil (Meriones unguiculatus) by a transient occlusion and release of the common carotid arteries. We have attempted to determine whether the oxidative stress is generated upon I/R and whether this oxidative stress is linked to the cell damage. Since hippocampus has been suggested as one of the most vulnerable regions of the brain to the oxidative stress, we analyzed samples from hippocampus in comparison with those from cortex. In addition, we have examined the expression of heat shock protein 70kD species (HSP70) in these regions in order to evaluate a possible role of this protein in I/R-induced brain damage. To determine whether the oxidative stress is produced upon I/R, we measured the glutathione oxidation, GSSG/ (GSH + 2xGSSG), as an index of oxidative stress. We found an increase of the glutathione oxidation primarily in hippocampus upon I/R. To determine whether this oxidative stress is linked to the cell damage, we measured the degree of lipid peroxidation upon I/R. We found an increase of lipid peroxidation in both regions. However, the magnitude of increases was greater in hippocampus than in cortex. In addition, we found that changes in both the magnitude and the temporal patterns of glutathione oxidation closely correlated with those of lipid peroxidation. Our study provides biochemical evidences that the oxidative stress is generated upon I/R and this oxidative stress is linked to the oxidative cell damage. Our study also provides evidences that the degree of oxidative stress as well as oxidative cell damage is greater in hippocampus than in cortex. We could not find difference in the basal level of HSP70 expression between hippocampus and cortex, indicating that the intrinsic vulnerability of hippocampus cannot be explained by the lower level of HSP70 expression. We did find, however, that the induction of HSP70 expression upon I/R was impaired in the hippocampus. This impairment appeared to be at the transcriptional level. These results suggest that the measurement of HSP70 induction may be employed as a useful predictor of differential cellular susceptibilities to the I/R-induced brain damage.

• Korean Journal of Plant Resources
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• v.21 no.5
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• pp.395-401
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• 2008

Flavonoids are ubiquitous substances in fruits and vegetables. A main subgroup of the flavonoids are the flavonols, of which quercetin and kaempferol are the major representatives in foods. They are used in food supplements at high doses, because of their preventive effects on degenerative diseases. The aim of this study was to determine the combined and separate effects of kaempferol and quercetin on oxidative stress in cow pulmonary artery endothelium (CPAE) cells over a broad concentration range. The results demonstrate that cell viability was greatly increased in kaempferol and quercetin treated cells whether $H_{2}O_{2}$-treated or not. Cell viability also increased when treated with flavonols in the absence of oxidative stress. Both preincubation and simultaneous incubation with kaempferol and quercetin protected against the loss of cell viability induced by 1mM $H_{2}O_{2}(5h)$. Protective effects of flavonols against oxidative stress were shown to depend on the treated flavonol concentrations. No protective effect was shown under low concentration treatment and cell viability increased 1.6 times at $200{\mu}M$ relative to the control group. At the highest flavonol concentration of $300{\mu}M$, the increased cell viability by flavonol treatment was decreased to almost half of the maximum values. Combined treatments with kaempferol and quercetin showed more protective effects against oxidative stress by $H_{2}O_{2}$ than the separate effects of each flavonol. In conclusion, the protective effect of kaempferol and quercetin against oxidative stress was very pronounced but high concentrations of flavonols can also induce cell cytotoxicity.

• Journal of Life Science
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• v.17 no.11
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• pp.1571-1575
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• 2007

This research was carried out to investigate the effects of Hambag mushroom on the oxidative stress in diabetic rats, Sprague-Dawley. The diabetic rats induced by streptozotocin were fed with hambag mushroom-powder(G. frondosa) for 6 weeks. For the level of oxidative stress in liver and pancreas tissues, it was studied by measuring LPO (lipid oxide) level as an indicator of lipid peroxidation, XOD(xanthine oxidase) as one of important sources for free radicals and the levels of GSH and GST as anti-oxidant systems. Also, as an indicator of liver damaged by oxidative stress, the activities of serum ALT and AST were measured. It was observed that the levels of ALT, AST, LPO and XOD were higher by about two times in both tissues from diabetic rats than in those from control rats. This indicates that the oxidative stress induced by diabetes caused the tissues damages. However, these levels were decreased in the tissues from rats with hambag mushroom-powder. Futhermore, the activity of GST were higher in both tissues from diabetic rats fed with hambag mushroom-powder than in those from diabetic rats. Thus, it is considered that the hambag mushroom-powder decreases the level of oxidative stress by increasing activity of anti-oxidant system such as GSH and GST. It is suggested that the hambag mushroom-powder can be useful for preventing the tissues damaged by diabetes-induced oxidative stress.

• Environmental Analysis Health and Toxicology
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• v.19 no.3
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• pp.241-250
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• 2004

본 연구는 건전지나 플라스틱 등 산업물질, 식품, 흡연 그리고 공기, 물 등을 통해 인간과 생태계에 노출되고 있는 중금속 카드뮴을 인간 유방암 세포 MCF-7에 처리하였을 때 일어나는 현상을 살펴보고 나아가 카드뮴의 독성기전을 규명하기 위해 시행되었다. 카드뮴으로 인한 아폽토시스는 DNA분절 현상과 핵의 쪼개짐, 세포주기에 있어서 sub-G1의 출현 그리고 아폼토시스시에 발현되는 단백질 caspase의 발현, 특히 산화적 스트레스상태에서 마이토콘드리아가 손상을 입었을 때 발현되는 caspase-9의 발현을 통해 확인하였다. 카드뮴으로 인한 산화적 스트레스는 활성 산소종이 대조군에 비해 증가하고 이를 방어하기 위한 항산화효소 superofide dismutase, catalase, glutathion redurtase가 감소함을 통하여 확인하였다. 이 상의 결과들을 통해 카드뮴은 인간 유방암 세포 MCF-7에서 산화적 스트레스를 유발시켜 아폼토시스를 일으키는 것으로 추정할 수 있다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.352-352
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• 2012

MOSFET의 크기는 작아지고 다양한 소자열화 현상으로 신뢰성 문제가 나타나고 있다. 특히 CMOS 인버터에서 PMOS가 'HIGH'일 때 음의 게이트 전압이 인가되고 소자 구동으로 인해 온도가 높아지면 드레인 전류의 절대값은 줄어들고 문턱 전압 절대값과 GIDL전류가 증가하는 NBTI현상이 발생한다. 본 연구에서는 NBTI현상에 따른 열화 특성을 분석하였다. 측정은 드레인과 소스는 접지시킨 상태에서 온도 $100^{\circ}C$에서 게이트에 -3.4V과 -4V의 게이트 스트레스를 인가한 후 게이트 전압에 따른 드레인 전류를 스트레스 시간에 따라 측정하였다. 측정에 사용된 소자의 산화막 두께는 25A, 채널 길이는 $0.17{\mu}m$, 폭은 $3{\mu}m$이다. 게이트에 음의 전압이 가해지면 게이트 산화막에 양전하의 interface trap이 생기게 된다. 이로 인해 채널 형성을 방해하고 문턱 전압은 높아지고 드레인 전류의 절대값은 낮아지게 된다. 또한 게이트와 드레인 사이의 에너지 밴드는 게이트 전압으로 인해 휘어지게 되면서 터널링이 더 쉽게 일어나 GIDL전류가 증가한다. NBTI스트레스 시간이 증가함에 따라 게이트 산화막에 생긴 양전하로 인해 문턱 전압은 1,000초 스트레스 후 스트레스 전압이 각각 -3.4V, -4V일 때 스트레스 전에 비해 각각 -0.12V, -0.14V정도 높아지고 드레인 전류의 절대값은 5%와 24% 감소한다. GIDL전류 역시 스트레스 후 게이트 전압이 0.5V일 때, 스트레스 전에 비해 각각 $0.021{\mu}A$, $67{\mu}A$씩 증가하였다. 결과적으로, NBTI스트레스가 인가됨에 따라 게이트 전압 0.5V에서 0V사이의 드레인 전류가 증가함으로 GIDL전류가 증가하고 문턱전압이 높아져 드레인 전류가 -1.5V에서 드레인 전류의 절대값이 줄어드는 것을 확인할 수 있다.

• Journal of Digital Convergence
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• v.15 no.1
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• pp.571-581
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• 2017

The purpose of this study was to investigate the effects of virgin coconut oil supplementation and complex exercise on body composition, oxidative stress and blood pressure in the middle-aged women with metabolic syndrome. As a result, weight and body fat in coconut oil+complex exercise and coconut oil group are significantly decreased after the program. BMI and WHR in coconut oil+complex exercise group are significantly decreased after than before the program. MDA in coconut oil+complex exercise and coconut oil group is significantly decreased after the program. SOD in coconut oil+complex exercise and coconut oil group is significantly increased after the program. Systolic blood pressure in coconut oil+complex exercise and coconut oil group is significantly decreased after than before the program. Diastolic blood pressure in coconut oil+complex exercise group is significantly decreased after than before the program.

• Journal of Life Science
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• v.23 no.12
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• pp.1553-1556
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• 2013

Flavonoids are one of the major components found in the peels of citrus fruits. Present evidence has suggested that polymethoxyflavonoids, including nobiletin and tangeretin isolated from Citrus sunki, have many biological properties, such as anti-inflammatory, anti-oxidant, and anti-obesity capabilities. Here, we investigated the effect of Citrus sunki peel extract and its possible mechanisms on oxidative stress-induced MMP-1 expression, a major marker of skin photoaging. $H_2O_2$ induced MMP-1 expression in a dose- and time-dependent manner. Extract of Citrus sunki peel (1-25 ${\mu}g/ml$) dose-dependently decreased MMP-1 mRNA levels. When $H_2O_2$ was combined with Citrus sunki peel extract, the phosphorylation of ERK was further decreased compared to a single treatment with $H_2O_2$ alone. Moreover, U0216, an MEK inhibitor, markedly prevented the production of MMP-1. These data suggest that Citrus sunki peel extract has demonstrated protective activity against oxidative damage on MMP-1 expression, and ERK MAP kinase may be involved.

• Korean Journal of Food Science and Technology
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• v.47 no.4
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• pp.517-524
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• 2015

The objectives of the present study were to investigate the protective effects of Angelica keiskei juice and Oenanthe javanica juice against oxidative damage in LLC-$PK_1$ renal epithelial cells and to evaluate their free radical-scavenging activities. Both A. keiskei juice and O. javanica juice showed a strong in vitro antioxidant activities such as ${\alpha}$, ${\alpha}$-diphenyl-${\beta}$-picrylhydrazyl (DPPH), nitric oxide (NO), $O_2{^-}$, and ${\cdot}OH$ radical-scavenging activities. The LLC-$PK_1$ cells showed significant lipid peroxidation and cell death due to oxidative stress when it was induced by 2, 2'-azobis (2-amidinopropane) dihydrochloride (AAPH), sodium nitroprusside (SNP), pyrogallol, and 3-morpholinosydnonimine (SIN-1). Treatment with both A. keiskei juice and O. javanica juice significantly increased cell viability and inhibited lipid peroxidation. These results suggest that A. keiskei juice and O. javanica juice are potential natural antioxidants.