• Membrane and Water Treatment
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• 제10권3호
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• pp.201-206
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• 2019

In this study, we performed an electrowinning process for effective removal of metals (Cu and Ni) in solution and their recovery as solid forms. A complete removal of Cu and Ni (1,000 mg/L) was observed during four times recycling test, indicating that our electrowinning system can ensure the efficient metal removal with high stability and durability. In addition, we investigated effect of operation parameters (i.e., concentration of boric acid only for Ni, variation of pH, concentration of electrolyte ($H_2SO_4$), and cell voltage) on the efficiency of metal removal (Cu and Ni) during the electrowinning. The addition of boric acid significantly enhanced removal efficiency of Ni as the concentration of boric acid increased up to 10 g/L. Compared to negligible pH effect (pH 1, 2, and 4) on the Cu removal, we observed the increase in removal efficiency of Ni as the pH increased from 1 to 4. The electrolyte concentration did not significantly influence the removal of Cu and Ni in this study. We also obtained great removal rates of Cu and Ni at 2.5 V and 4.0 V, which were much faster than those at lower voltages. Finally, almost 99% of each Cu and Ni (1,000 mg/L) was selectively removed from the mixture of metals by adjusting pH and addition of boric acid after the completion of Cu removal. The findings in this study can provide a fundamental knowledge about effect of important parameters on the efficiency of metal recovery during the electrowinning.

• 한국항해항만학회지
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• 제48권2호
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• pp.125-136
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• 2024

This research presents an innovative integrated ethanol solid oxide fuel cell (SOFC) system designed for applications in marine vessels. The system incorporates an exhaust gas heat recovery mechanism. The high-temperature exhaust gas produced by the SOFC is efficiently recovered through a sequential process involving a gas turbine (GT), a regenerative system, steam Rankine cycles, and a waste heat boiler (WHB). A comprehensive thermodynamic analysis of this integrated SOFC-GT-SRC-WHB system was performed. A simulation of this proposed system was conducted using Aspen Hysys V12.1, and a genetic algorithm was employed to optimize the system parameters. Thermodynamic equations based on the first and second laws of thermodynamics were utilized to assess the system's performance. Additionally, the exergy destruction within the crucial system components was examined. The system is projected to achieve an energy efficiency of 58.44% and an exergy efficiency of 29.43%. Notably, the integrated high-temperature exhaust gas recovery systems contribute significantly, generating 1129.1 kW, which accounts for 22.9% of the total power generated. Furthermore, the waste heat boiler was designed to produce 900.8 kg/h of superheated vapor at 170 ℃ and 405 kP a, serving various onboard ship purposes, such as heating fuel oil and accommodations for seafarers and equipment.

• KSBB Journal
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• 제23권4호
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• pp.281-284
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• 2008

본 연구에서는 식물세포배양액에서 회수한 식물세포인 biomass로부터 항암제 paclitaxel을 효율적으로 회수하기 위해, microwave를 이용한 추출 (MAE) 방법을 도입하여 기존의 유기용매 추출 (CSE) 방법과 추출효율을 비교하였다. CSE 방법에서 추출온도 25, $30^{\circ}C$에서는 추출시간 (3, 6, 10 min)에 대해 추출효율이 온도에 영향을 받지 않은 반면, 40, $50^{\circ}C$에서는 추출시간 10 min에서 paclitaxel 수율이 감소하는 경향을 보여 온도에 영향을 받음을 알 수 있었다. CSE 방법의 경우 총 4회의 추출로 식물세포 내 대부분의 paclitaxel을 회수 (>99%) 가능한 반면 MAE 방법의 경우 1회의 추출로 식물세포 내 대부분의 paclitaxel을 회수 (>99%) 가능하였다. MAE 방법이 CSE 방법보다 paclitaxel를 회수하는데 있어서 높은 추출효율, 공정시간 단축, 에너지 절감 효과가 있음을 알 수 있었다. 또한 MAE 공정에서 최적의 biomass/methanol의 비율은 1/1 (w/v)임을 알 수 있었다.

• Toxicological Research
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• 제16권2호
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• pp.163-172
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• 2000

Recently, there is a worldwide concern that a great number of man-made chemicals have a hormone-like action both in humans and in animals. DECD is developing screening programs using validated test systems to determine whether certain substances may have an effect in humans. In the present study. the establishment oj repeated-dose toxicity test method was tried. Flutamide. an anti-androgenic agent. was administered by gavage to Sprague-Dawley rats for 28 days at dose levels of 0. 0.5. 3 and 18 mg/kg body weight (10-15 rats/sex/group) to examine the effects on general findings. especially reproductive and endocrine parameters. Clinical signs. body weights, food consumption, and sexual cycle were checked and measured. For the gross and microscopic examinations. 10 rats/sex/group were sacrificed at the end of dosing period and the remaining animals of control and high dose groups (5 each) were sacrificed after 14 days recovery. Examinations for hematology and clinical chemistry were carried out at necropsy. There were no treatment-related changes in clinical signs. body weights, food consumption. gross necropsy. hematology and clinical chemistry at all doses of both sexes. The period and regularity of sexual cycle were not adversely affected at all doses by the test agent. At 18 mg/kg. both decreased weights of prostate, seminal vesicle and epididymis in males and increased weights of spleen and thymus in females were observed. In addition, decreased number of spermatids and sperms. increased serum testosterone concentration and increased incidence (100%) of interstitial cell hyperplasia were seen in males. At 18 mg/kg of the recovery group. decreased prostate weight. reduced sperm count and increased incidence (20%) of interstitial cell hyperplasia in males and increased thymus weight in females were observed. At 3 mg/kg. reduced sperm count was found. There were no adverse effects on parameters examined at 0.5 mg/kg of both sexes. The results suggested that the potential target organs of flutamide may be accessory sexual glands including testes for males and spleen and thymus for females. Taken together. this test method was found to be a useful screening test system for endocrine disrupting chemicals.

• 한국환경과학회지
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• 제6권1호
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• pp.61-67
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• 1997

미생물에 의한 흡착법으로 중금속을 효과적으로 제거, 회수할 수 있다. 알콜 발효 후 부산물로 생성되는 폐 Saccharomyces cerevisiae는 비교적 가격이 저렴하고, 중금속 생체흡착에 유용한 자원으로 이용될 수 있다. 생체흡착 실험에 사용된 미생물은 부유 및 alginate에 고정화된 S. cerevisiae로 수행하였다. 회분식 실험에서 생체흡착량은 Pb > Cu > Cd의 순으로 이루어졌다. Pb 이온의 흡착 평형은 Freundlich와 Langinuir 모델로 설명하였고, Freundlich 모델이 실험자 료와 잘 부합되었다 고정화된 S. cerevisiae를 이용한 혼합용액( Pb, Cu, Cr 및 Cd )흡착 실험에서 각 중금속들은 선택적 흡착 특성을 나타내었다. 고정화 미생물을 고정층 반응기에 충진하여 혼합 중금속 용액의 생체흡착 실험을 수행한 결과 Pb 이온이 가장 많이 흡착을 하였다. 고정화된 미생물에 흡착된 Pb의 탈착실험에서 0.1M의 HCI 및 $H_2SO_4$가 효과적이었다.

• BMB Reports
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• 제33권3호
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• pp.213-220
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• 2000

A fulminant hepatitis is associated with massive liver cell necrosis and a high mortality rate. But survivors regenerate a normal liver and do not have chronic liver disease. This clinical course suggests that the acutely injured livers release a factor that allows a recovery from chronic hepatitis or cirrhosis. The objective of this study was to isolate and characterize an anti-fibrotic factor from acutely damaged rat livers. The liver cell necrosis was prepared from rat by warm ischemical perfusion and the perfusates were assessed against the growth inhibition of fat-storing cells (FSC). A liver-derived growth inhibitory factor (LDGIF) was purified from ischemically damaged rat livers by chromatographies on Sephacryl S-300, CM Sepharose, hydroxyapatite, and Superose 12. The LDGIF was isolated with an overall purification of 194-fold and 40% recovery. Although LDGIF was identified as the rat liver arginase by Nterminal sequence analysis, LDGIF exists as a monomer and the purified native arginase has a trimer form. Furthermore, LDGIF has a lower enzyme activity on the hydrolysis of L-arginine and a higher inhibitory effect on proliferation of FSC than the normal rat liver arginase. The catalytic activity of LDGIF is ascribed to the monomeric characteristics of the LDGIF. Therefore, the inhibitory action of LDGIF might not be due to the arginine depletion by the catalytic activity of arginase. In conclusion, the presence of the LDGIF could interpret the clinical course that serious fibrosis is not found in the liver of patients recovering from severe hepatic necrosis due to fulminant hepatitis, suggesting that this LDGIF may provide a novel target for the prevention and treatment of hepatic fibrosis.

• 대한본초학회지
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• 제26권3호
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• pp.75-82
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• 2011

Objectives : In this study, we evaluated the effect of Chungganhaeju-hwan(CGHJH) on hydrogen peroxide($H_2O_2$)-induced and ethanol(EtOH)-induced neuronal damage in vitro and in vivo, respectively. Methods:We carried out the anti-oxidant effects of CGHJH against hydrogen peroxide($H_2O_2$)-induced toxicity in HT22 and PC12 cells using thiazolyl blue tetrazolium bromide. Then, to investigate the protective effect on CGHJH against EtOH-induced memory impairment and hippocampal cell damage in male ICR mice, we performed novel object recognition test(NORT), and analysed the brain tissues after immunohistochemistry and western blotting. Results:CGHJH showed protective effect from $H_2O_2$-induced cell toxicity at doses of $1\sim100{\mu}g$/mL in both HT22 and PC12 cells. CGHJH had also recovery effect from EtOH-induced memory impairment in ICR mice from NORT and it protected hippocampal cells against EtOH toxicity in the result of cresyl violet and NeuN immunoreactivity. Conclusion : These results demonstrate that CGHJH has protective effect in neuronal cells against $H_2O_2$ and EtOH toxicities and this effect could be a main role of recovery effect on EtOH-induced memory loss.

• The Korean Journal of Physiology
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• 제24권2호
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• pp.377-388
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• 1990

Ca movements during the late plateau phase in rabbit atrium implicate Na-Ca exchange. In single atrial cells isolated from the rabbit the properties of the inward current of Na-Ca exchange were investigated using the whole cell voltage clamp technique. The inward currents were recorded during repolarization following brief 2 ms depolarizing pulse to +40 mV from a holding potential of -70 mV. Followings are the results obtained: 1) When stimulated every 30 sec, the inward currents were activated and reached peak values $6{\sim}12\;ms$ after the beginning of depolarizing pulse. The mean current amplitude was 342 pA/cell. 2) The current decayed spontaneously from the peak activation and the timecourse of the relaxation showed two different phases: fast and slow phase. 3) The recovery of the inward current was tested by paired pulse of various interval. The peak current recovered exponentialy with a time course similar to that of Ca current recovery. 4) Relaxation timecourse was also affected by pulse interval and time constant was reduced almost linearly according to the decrease of pulse interval between 30 sec and 1 sec. 5) The peak inward current was increased by long prepulse stimulation, Bay K, isoprenaline or c-AMP. 6) The relaxation time constant of the inward current was prolonged by Bay K or c-AMP, and shortened by isoprenaline. From the above results, it could be concluded that increase of the calcium current potentiates and prolongs intracellular calcium transients, while shortening of the timecourse by isoprenaline or short interval stimulations might be due to the facilitation of Ca uptake by SR.

• 자원리싸이클링
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• 제20권2호
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• pp.67-73
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• 2011

연료전지 폐스택으로부터 백금을 회수하여 재사용하기 위하여 백금의 농도, pH, 환원제, 분산제의 영향을 살펴본 결과 1 mM $H_2PtCl_6$:10 mM $NaBH_4$:8 mM Cl4TABr = 1:0.4:0.4(vol.%), pH4, $50^{\circ}C$, 160 rpm, 10분 조건에서 최적 백금 나노 입자 제조 조건을 확립하였다. 시용 후 폐기된 MEA로부터 산침출을 통해 회수되어진 백금 침출 용액으로부터 백금 모사 용액과 동일한 조건에서 5 nm 이하의 백금 나노 입자를 합성하였다. 백금 모사 용액과 백금 침출 용액으로부터 합성된 백금 나노 입자를 XPS 분석을 통해 백금 이온에서 zero-valent의 백금 나노 입자로 환원되었음을 확인하였다.

• 자원리싸이클링
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• 제20권4호
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• pp.52-57
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• 2011

본 논문에서는 초음파나 교반 없이 전해질막과 확산층을 분리하기위한 새로운 방법에 대해 연구하였다. 증류수, 부탄올, 계면활성제를 이용하여 연료전지 막전극접합체의 전해질막과 확산층을 침지법으로 촉매입자의 분산 없이 분리하였다. 또한 분리된 확산층의 촉매와 연료전지 Pt/C 촉매를 왕수에서 $80{\sim}85^{\circ}C$로 가열하여 촉매입자를 녹여 침전제를 첨가하였다. 이후 소성하여 백긍 금속을 회수하였고 이는 새로운 연료전지용 전극촉매를 만드는데 사용될 것이다.