• The Journal of Dong Guk Oriental Medicine
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• v.7 no.1
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• pp.87-98
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• 1998

This study was undertaken to determine whether Bombycis Corpus extract (Bom) has antioxidant action. Kidney tissues were exposed to t-butylhydroperoxide (t-BHP) to induce oxidative stress. Lipid peroxidation was estimated by measuring malondialdehyde, a product of lipid peroxidation, and cell injury was estimated by measuring lactate dehydrogenase (LDH) release in rabbit renal cortical slices. t-BHP increased lipid peroxidation and LDH release in a dose-dependent manner over the concentration range of 0.1-1 mM. Such effects of t-BHP on lipid peroxidase and LDH release were prevented by 0.5% Bom. When tissues were treated with t-BHP in the presence of various concentrations of Bom, lipid peroxidation and LDH release were dose-dependently inhibited by Bom. Bom at 1 and 2% concentrations inhibited lipid peroxidation and LDH release in normal tissues. Bom at 2% concentration increased glutathione peroxidase activity in tissues treated or untreated with 1.0 mM t-BHP. However, catalase activity was not altered by addition of Bom. Bom inhibited generation of reactive oxygen species. These results indicate that Bom inhibits lipid peroxidation and cell injury in tissues treated with or without oxidant and this effect is, at least in part, attributed to increased activity of glutathione peroxidase and a direct sacvenging action.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.506-514
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• 2007

To select the best oxygen carrier particle for syngas fueled chemical-looping combustor, the reduction reactivity and carbon deposition characteristics were determined in a thermogravimetric analyzer. Four kinds of oxygen carrier particles (NiO/bentonite, $NiO/LaAl_{11}O_{18}$, $Co_xO_y/CoAl_2O_4$, $NiO/NiAl_2O_4$) were tested with the simulated syngas (30% $H_2$, 10% $CO_2$, 60% CO) as a reduction gas. With each of these particles, the maximum conversion and oxygen transfer capacity increase with increasing the reduction temperature At the given experimental range, the optimum operating temperature to maximize oxygen transfer rate is found to be $900^{\circ}C$ and carbon deposition on the particles could avoid at the temperature above $800^{\circ}C$. Among four kinds of oxygen carrier particles, the NiO-based particles exhibits better reactivity than the CoO-based particle. Moreover, the NiO/bentonite particle produces the best reactivity based on the oxygen transfer rate and the degree of carbon deposition. The measured oxygen transfer rate increases as the metal oxide content in NiO/bentonite particle is increased thereby higher metal oxide contents could provide stable operation of chemical-looping combustor.

• 대한예방의학회:학술대회논문집
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• 1999.10a
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• pp.308-309
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• 1999

• Clinical and Experimental Pediatrics
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• v.45 no.5
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• pp.560-567
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• 2002

주산기 뇌손상은 주로 급격한 저산소-허혈 손상에 의하는데 급격한 산소 공급의 차단은 oxidative phosphorylation을 정지 시켜서 뇌대사를 위한 에너지 공급이 차단되게 된다. 에너지 공급이 차단된 뇌세포는 뇌세포막에서 세포 내외의 이온 농도 차를 유지시키던 ATP-dependent $Na^{+}-K^{+}$ pump의 기능이 정지 되고, 세포 내외의 농도 차에 따라 $Na^{+}$, $Cl^{+}$, $Ca^{{+}{+}}$의 대규모 세포 내로 이동이 일어난다. 세포 내로 calcium 이온의 이동은 glutamate 수용체의 활성화에 의해서도 일나는데, 세포 내 calcium 이온의 증가는 protease, lipase, nuclease 등을 활성화 시켜 세포를 사망에 이르게 하는 연속적이고 다양한 생화학적 반응을 일으키게 된다. Glutamate는 대표적인 신경 전달 물질인데 저산소-허혈 손상 시 glutamate 수용체의 지나친 흥분은 미성숙 뇌에 뇌손상을 유발하는데, NMDA 또는 non-NMDA 수용체와 복합체를 형성하고 있는 calcium 이동 통로를 활성화 시켜 세포 내 calcium 이온을 증가시키고, 그 외에 metabotropic recetor는 G-protein의 활성화 등을 통해 뇌손상을 유발하는 다양한 생화학적 반응을 매개한다. 저산소-허혈 손상 후 재산소화와 재관류가 일어나면서 뇌세포의 지연성 사망(secondary neuronal death)이 일어나는데 이는 초기 손상 후 뒤이어 일어나는 다양한 생화학적 반응에 의하는데 다량의 산소 자유기 발생, nitric oxide의 생성, 염증 반응과 싸이토카인, 신경전도 물질의 과흥분 등이 관여하며, 신경 세포 사망은 세포괴사(necrosis)뿐 아니라 일부는 세포 사멸(apoptosis)로 알려진 의도된 세포 사망(programmed cell death)에 의한 것으로 생각되고 있다(Fig. 2).

• Development and Reproduction
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• v.4 no.2
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• pp.203-213
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• 2000

To investigate the effects of reactive oxygen species (ROS) on capacitation, acrosome reaction in human spermatozoa. Human spermatozoa were incubated with xanthine-xanthine oxidase (X-XO), $H_2O$$_2$, sodium nitroprusside (SNP) or lymphocyte. Otherwise, spermatozoa were incubated under low $O_2$ (5 ％) condition. Chlortetracycline (CTC) staining was conducted to assess capacitation and acrosome reaction. Analysis of lipid peroxidation was done by spectrophotometric determination of malondialdehyde (MDA) production in spermatozoa. $H_2O$$_2$, X-XO, SNP and lymphocyte treatment significantly increased capacitated spermatozoa within 1 h of incubation. There was no significant difference in capacitation between low- and high $O_2$ groups. In the presence of low concentration of $H_2O$$_2$, lipid peroxidation decreased significantly. However, under the high concentration of $H_2O$$_2$, lipid peroxidation significantly increased at the end of incubation compared to control. In the presence of high concentration of lymphocytes, lipid peroxidation significantly increased compared to control at 1hr of incubation. There was no significant difference in lipid peroxidation according to $O_2$ concentration examined. Acrosome reaction (AR) was evaluated by CTC staining after the progesterone challenge. In all ROS groups, AR increased compared to control. The X(100 $\mu$M) - XO (100mIU) system was the most potent to induce AR. Taken together, it suggested positive control of AR by ROS and the positive relationship between the lipid peroxidation and AR. The early onset of capacitation in the presence of ROS suggest that ROS might be a positive regulator of sperm capacitation and hyperactivation.

• Environmental engineer
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• s.115
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• pp.43-45
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• 1996

강력한 오존 발생기에서 나오는 4.6$\%$의 오존이 액체에 주어졌을 때 처음 반응은 오존이 산소분자와 원자로 분열을 일으키고 산소 발생기로 접어들게 함으로써 산화물을 촉진케 하는 불소를 능가하는 단 하난의 음전성의 산화가능성을 가진 것이기 때문에 오존은 거의 모든 유기성 화합물을 공격할 수 있는 자연이 준 강력한 산화제이며 만능의 처리제인 것이다.

• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.287-292
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• 2010

We have investigated the effects of oxygen flow ratios on the structural, morphological, and optical properties of AlN thin films grown by using radio-frequency reactive magnetron sputtering. The AlN thin films were deposited at $300^{\circ}C$ of substrate temperature, and the reactive gas were supplied with both nitrogen and oxygen. The oxygen flow ratio was varied by controlling the amount of oxygen with respect to the total mixed gases, 0%, 10%, 15%, 20%, 25%, and 30%. The structural, morphological, and optical properties of the deposited AlN thin films were examined by using X-ray diffractometer, scanning electron microscopy, and ultraviolet-visible spectrophotometer. The AlN thin film grown at 10% of oxygen flow ratio indicated an average transmittance of 91.3% in the wavelength range of 350~1,100 nm and an optical band gap of 4.30 eV. The experimental results suggest that AlN thin films can be deposited optionally by varying the oxygen flow ratio.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.291-291
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• 2009

한국원자력연구원의 파이로 실험 시설인 ACPF (ACP Facility)에는 공학규모 전해환원 반응기가 설치되어 공정 대용량화를 위한 연구가 수행되고 있다 본 연구에서는 전해환원 공정의 Scale-up을 위해 기존 반응기를 개선하여 전해환원 실험을 수행한 결과를 담고 있다. 장치의 대형화 빛 원격운전성 향상을 위해 기존의 전해환원 반응기의 상부 플랜지는 보다 간단하게 정리되었으며 염 이송에 의한 고온 조건 노출 시간을 줄임과 동시에 염 재사용을 목적으로 상부 플랜지는 이중으로 설계되었다. 따라서, 반응 종료후 전극이 설치된 상부 플랜지를 들어 올림으로서 반응기를 불활성 분위기로 유지하는 동시에 전해환원 금속전환체를 회수 할 수 있도록 반응기가 제작되었다. 또한, 새로운 반응기는 용융염 내의 강제 유동을 위해 아르곤 버블링이 가능하도록 설계 제작되었다. 새로 제작 설치된 전해환원 반응기를 사용하여 산화물 분말을 혼합하여 준비한 모의 사용후핵연료를 사용하여 전해환원 실험을 수행하였다. 그 결과, 산화물이 충진된 음극의 전영역에서 고루 96% 이상의 높은 금속전환율을 얻었으며 시간에 따라 선택된 FP들의 용융염 내 거동을 측정하였다. 실리더 형태의 음극에서 Cs, Sr 등의 원소들이 용융염으로 시간에 따라 용출되는 것을 확인하였으며 동시에 반응기 재질인 Fe 등도 일부 용융염에서 검출되었다. 아르곤 버블링에 의한 강제 유동은 전압 및 전류 거동에는 큰 영향을 미치지 못하였으나 염의 휘발량을 증가시켜 영조성올 변화시키는 것으로 측정되었다. ACPF의 전해환원 실험결과를 바탕으로 반응기를 상부 기체상과 하부 액체상으로 나누어 전산모사를 수행하였다 상부 기체상은 유입되는 아르곤 기체와 발생되는 산소기체의 흐름을 모사하는 결과를 얻었으며 온도 및 산소의 분압을 계산하였다. 하부 액체상에서는 전기장을 모사하여 전류 밀도 등을 3차원으로 모사하였다.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.10
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• pp.578-582
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• 2015

It was investigated whether the removal of nitrogen ions included livestock wastewater were increased by increasing the reaction time of livestock wastewater and microbubbles with catalyst. For this study, the nitrogen reduction system using microbubbles with catalyst was used. The two reactors were consecutively arranged, and the second reactor (Step 2) was located to next the first reactor (Step 1). Each reactor was reacted for 2 hours and air or oxygen as oxidant was fed into the reactor during operation before microbubble device. When oxygen was used, ammonia nitrogen was removed each 18.3% and 52.8% during 2 (only step 1) and 4 (step 1 and step 2) hours reactions. This value was higher than that of when air was fed. When oxygen was used, the longer the reaction time, the ammonia nitrogen removal was higher. The longer the reaction time, the higher the nitrite and nitrate was also removed such as ammonia nitrogen. Also this system was examined whether organic matter removal is effective. The total chemical oxygen demand (TCOD) removal was higher than the soluble chemical oxygen demand (SCOD). Some materials among causing substances COD were difficult to decompose biologically. Therefore, it means that it will be easy to operate the biological processes following step and reduce the concentration of organic contaminants in effluent.

• KSBB Journal
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• v.7 no.4
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• pp.252-257
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• 1992

A flat-type membrane bioreactor(FMBR ) for aerobic whole cell immobilization was developed and its performance for the citric acid production was investigated using Aspergillus niger (KCTC 1232). The reactor consisted of three layers. The top layer contained flowing air for oxygen supply, the middle layer had stationary cells, and the bottom layer had flowing aqueous nutrients. The initial pH of the culture medium played an important role in citric acid production and the lower initial pH of the culture medium resulted in a higher citric acid yield. Under air and pure oxygen aerations the volumetric productivity reached 0.20 and 0.40g/Lh. Furthermore, the productivity improved with the increase of the culture medium feed rate.