• Analytical Science and Technology
• /
• v.12 no.4
• /
• pp.273-278
• /
• 1999

Simultaneous determination of mercury and arsenic has been studied by reductive vapor generation-ICP-AES. Samples were digested with a microwave digestion system and extracted with acids. Reductive vapor generation was carried out with 6N HCI and 2% $NaBH_4$. Detection limit of Hg and As are found to be 0.06 ppb and 0.08 ppb, respectively. Measured values of Hg and As in inorganic samples agree well with reference value of SRMs, but the recovery of As from organic samples is obtained approximately 80% of the reference values.

• Analytical Science and Technology
• /
• v.23 no.4
• /
• pp.389-394
• /
• 2010

An ICP-AES method for determination of calcium content and dissolution characteristics of oyster shell (Ostrea gigas) has been developed and validated. Total calcium content in oyster shell was determined using ICPAES. The dissolution characteristics, which would reflect the composition of $CaCO_3$ polymorphs and calcium salts in oyster shell, were also evaluated by dissolution test. The total calcium contents ranged from 31.8 to 39.9% and the dissolution ratios varied from 62.7 to 83.6% (n=15). The determination of calcium content and dissolution characteristics by ICP-AES would provide useful information for the quality control of oyster shell.

• Analytical Science and Technology
• /
• v.11 no.6
• /
• pp.413-420
• /
• 1998

The hydrophobic interaction has been studied on sodium naphthalene derivatives such as sodium 1-naphthaleneacetate (S1NA), sodium 1-naphthalenemalonate (SINM), sodium 2-naphthaleneacetate (S2NA), and sodium 2-naphthalenepropionate (S2NP) in $H_2O$-MeOH mixture solutions and in surfactant solutions. In $H_2O$-MeOH mixture solutions, the hydrophobic interaction was measured, and resulted in the red shift in emission spectra. In cationic surfactant, cetyltrimethylamonium bromide (CTAB) solution, the hydrophobic interaction was also observed by the red shift in absorption and emission spectra.

• Fire Science and Engineering
• /
• v.17 no.4
• /
• pp.117-123
• /
• 2003

In this study; the ignition and heat release rate characteristics of rigid polyurethane foam were investigated in accordance with setchkin ignition tester and cone calorimeter which is using oxygen consumption principle. In the ignition temperature study; flash-ignition temperature was $383^{\circ}C$-$390^{\circ}C$, self-ignition temperature was$ 493^{\circ}C$∼495$^{\circ}C$. The self-ignition temperature of rigid polyurethane foam was about $100^{\circ}C$ higher than the flash-ignition temperature. In the cone calorimeter study, the time to ignition of rigid polyurethane foam was faster as the external heat flux increase. In the same heat flux level, the time to ignition was faster as the density of rigid polyurethane foam decrease. Also the heat release rate was the largest value at the heat flux of /$50 ㎾\m^2$ and had a tendency of increase as the heat flux level and density increase. In the standpoint of time to ignition and heat release rate, the fire performance of rigid polyurethane foam was influenced by the applied heat flux level and density and the flashover propensity classified by Petrella's proposal was high.

• Journal of Life Science
• /
• v.20 no.11
• /
• pp.1595-1602
• /
• 2010

Oxidation of low density lipoprotein (LDL) has been recognized as an important role in the initiation and progression of atherosclerosis. In this study, effects of allylmercaptan, a major metabolite compound of garlic, was studied on endothelial cell injury induced by oxidized low density lipoprotein (ox-LDL). The antioxidative activity of allylmercaptan was investigated by monitoring a thiobarbituric acid substance (TBARS). Allylmercaptan inhibited LDL oxidation induced by $Cu^{2+}$ at concentrations of 0.1, 1 and 10 mM in a dose dependent manner. Lactate dehydrogenase (LDH) release, as an index of cell injury, and intracellular glutathione levels were determined. Pulmonary artery endothelial cells were preincubated with allylmercaptan at $37^{\circ}C$ and 5% $CO_2$ for 24 hr, washed, and then exposed to 0.1 mg/ml oxidized LDL for 24 hr. Preincubation of endothelial cells with allylmercaptan significantly prevented the LDH release and depletion of GSH. Peroxides were measured directly in 24 well plates using a fluorometric assay. Allylmercaptan inhibited release of peroxides induced by ox-LDL in pulmonary artery endothelial cells. In a free system, allylmercaptan was shown to scavenge hydrogen peroxide. The data indicate that allylmercaptan can protect pulmonary artery endothelial cells from injury caused by oxidized LDL, and suggest that allylmercaptan may be useful for the prevention of atherosclerosis.

• Korean Journal of Food Science and Technology
• /
• v.46 no.5
• /
• pp.630-635
• /
• 2014

Pine nut oil (PNO) is well known to impart beneficial effects in overweight individuals, but the mechanisms underlying PNO-mediated weight loss remain unclear. To investigate how PNO promotes weight loss, its composition was determined by gas chromatography coupled with mass spectrometry (GC-MS). In addition, the effects of PNO on cytotoxicity, lipid accumulation, expression of lipid metabolism-related biomarkers, and leptin secretion were assessed in 3T3-L1 cells. GC-MS analyses revealed that PNO contains several components, including linoleic acid, oleic acid, palmitic acid, and stearic acid. Moreover, PNO did not have a cytotoxic effect on 3T3-L1 cells. However, it inhibited the expression of peroxisome proliferator-activated receptor (PPAR) and adipocyte protein 2 (aP2). Finally, PNO significantly increased leptin secretion in a dose-dependent manner. Taken together, these results support the notion that PNO is useful for weight management in overweight individuals.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.1
• /
• pp.82-90
• /
• 2013

In this paper, conducted emission from the MDS(Motor Drive System) of a HEV/EV was analyzed using high- frequency circuit modeling in system-level approach. The conducted emission by PWM process can cause RFI(radio- frequency interference) problems in the AM/FM frequency range. In order to mitigate this conducted emission, a high-frequency equivalent circuit model is proposed by analyzing the fundamental circuits, parasitic components in their parts and connections and non-linear characteristics of IGBTs, high-power capacitors, inverters, motors, high-power cables, and bus bars which are composed of the MDS. It is confirmed that the simulated result by the proposed model is well agreed with measured results in spite of a large-scaled analysis in system level. We are looking forward that this approach can be effectively used in the EMC design of HEV/EV.

• Radiation Oncology Journal
• /
• v.20 no.4
• /
• pp.367-374
• /
• 2002

Purpose : To investigate the growth inhibitory effects, and the underlying mechanism of human colon cancer cell (HT-29) death, induced by a new synthetic bile acid derivative (HS-1200). Materials and Methods : Human colon cancer cells (HT-29), in exponential growth phase, were treated with various concentrations of a new synthetic bile acid derivative (HS-1200). The growth inhibitory effects on HT-29 cells were examined using a frypan blue exclusion assay. The extent of apoptosis was determined using agarose gel electrophoresis, TUNEL assays and Hoechst staining. The apoptotic cell death was also confirmed by Western blotting of PARP, caspase-3 and DNA fragmentation factor (DFF) analysis. To investigate the involvement of mitochondria, we employed immunofluorescent staining of cytochrome c and mitochondrial membrane potential analyses. Results : The dose required for the half maximal inhibition $(IC_{50})$ of the HT-29 cell growth was $100\~150\;{\mu}M$ of HS-1200. Several changes, associated with the apoptosis of the HT-29 cells, were reveal by the agarose gel eletrophoresis, TUNEL assays and Hoechst staining, following their treatment with $100\;{\mu}M$ of HS-1200. HS-1200 treatment also induced caspase-3, PARP and DFF degradations, and the western blotting showed the processed caspase-3 p20, PARP p85 and DFF p30 and p11 cleaved products. Mitochondrial events were also demonstrated. The cytochrome c staining indicated that cytochrome c had been released from the mitochondria in the HS-1200 treated cells. The mitochondrial membrane potential $(\Delta\Psi_m)$ was also prominently decreased in the HS-1200 treated cells. Conclusion : These findings suggest that the HS-1200 - induced apoptosis of human colon cancer cells (HT-29) is mediated via caspase and mitochondrial pathways.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.215.2-215.2
• /
• 2016

플라즈마는 현대 산업에서 다양한 고부가가치 산업 분야에 걸쳐 이용되고 있다. 이러한 플라즈마를 정밀하게 진단하고 제어하는 기술이 공정의 수율을 증대하고 생산성을 높이는데 크게 기여함은 자명하다. 플라즈마를 진단하는 방법은 크게 광학적 진단 방법과, 전기적 진단 방법으로 나눌 수 있는데 광학적 진단 방법은 방전시 발생하는 방출광을 통해 플라즈마의 현재 상태를 예측하는 방법이고, 전기적 진단 방법은 플라즈마 내로 직접 탐침을 접촉하여 전기적 물리량을 측정하는 방법이다. 각각은 정성적, 정량적 진단을 하는 데에 장점이 있다. 공정 모니터링은 주로 광학적 진단 방법에 의해 이루어지는데 전기적 진단 방법은 플라즈마와 직접 접촉하기 때문에 플라즈마에 대한 간섭현상이 발생하므로 부적합하다. 해당 실험에서는 유도 결합형 플라즈마 발생 용기에 아르곤, 산소 혼합 유체를 유입하여 방전하며 광학적 진단 방법을 통해 플라즈마를 관측하며 실험을 진행하였다. 측정 장치는 3채널 광학 진단이 가능한 시스템을 구성하여 공정중 발생하는 방출광의 특정 피크 변화를 공정 변수 변화로 인지하여 질량 유량 제어기를 조작, 피크를 초기상태로 되돌리는 공정 제어가 가능하도록 시스템을 구성하였다. 이를 통해 플라즈마를 이용한 공정 중 공정 변화에 자동으로 대응하는 공정제어 시스템을 시험 하였다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.291-291
• /
• 2011

플라즈마에 노출된 재료 표면의 온도 증가는 다음과 같은 요인에 의해서 결정된다. 이온의 충돌에 의한 역학적 에너지, 이온의 중성화, 라디칼의 안정화에 의한 에너지 방출(잠열, latent heat), 플라즈마에서 방출된 빛의 흡수. 이중 식각을 위한 기판 바이어스에 의해서 주로 결정되는 이온 충돌 에너지와 잠열의 방출이 300 mm wafer용 유도 결합 플라즈마 식각 장치에서 소스 전력과 바이어스 전력에 따라서 어떻게 변화하는지 전산 유체 역학 모사 프로그램인 CFD-ACE를 이용하여 상용 식각 장비인 AMAT사의 DPS II를 대상으로 온도 분포의 변화를 계산하였다. 실험 결과와 비교를 위하여 다섯 곳에(상, 하, 좌, 우, 중심) 열전대를 부착한 온도 측정 웨이퍼를 기판의 위치에 설치하고 여러 가지 실험 조건에 대해서 온도의 변화를 측정하였다. Ar 10 mTorr에서 2열 병렬 안테나의 전력을 300 W에서 시간에 따른 온도의 변화를 측정하였다. 이때 wafer의 평균 온도는 $28.9^{\circ}C$에서 $150^{\circ}C$까지 12분 내에 상승하였으며 최고 온도에 도달한 다음에는 거의 일정하게 유지 되었다. Si의 식각에서 온도의 영향을 가장 크게 받는 반응은 F 라디칼에 의한 Si의 직접 식각이며 Arrhenius 식의 형태로 표현하면 0.116*exp (-1250/T)의 형태로 된다. 문헌에 보고된 계수를 이용해서 $29^{\circ}C$의 식각 속도와 플라즈마에 의한 가열 최고 온도인 $150^{\circ}C$ 때의 값을 비교해보면 3.3배의 차이가 난다. 따라서 4%내의 식각 균일도를 목표로 하는 폴리 실리콘 게이트 식각 장비의 설계에서는 플라즈마에 의한 가열 불균일을 상쇄 할 수 있는 히터와 냉각 구조의 최적 설계가 필요하다.