• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.49-52
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• 2008

현재 산업사회의 발달과 더불어 신뢰성 높은 양질의 전기에너지와 운전 및 보수의 간편화, 계통운용의 신뢰성의 확보가 요구되고 있다. 또한 $SF_6$을 대체할 친환경적인 절연매체의 개발이 절실히 요구되고 있다. 이에 본 연구는 모의 GIS내 친환경적인 절연재료인 질소($N_2$)와 산소($O_2$)의 혼합가스($N_2:O_2=79:21$, $N_2:O_2=60:40$, $N_2:O_2=40:60$)의 기본적인 절연특성을 구명함으로서 각종 전력응용 설비의 절연매체로 사용가능함을 구명하고저 한다.

• Journal of the Korean Chemical Society
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• v.38 no.12
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• pp.880-884
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• 1994

An indirect spectrophotometric method, presumably heretofore unmentioned, for the rapid determination of COD in the presence of chloride of high concentration is described. The alkaline sample is refluxed to react with a definite amount of permanganate, present in excess. A photometric measurement at 535 nm for the extent of the fading of the permanganate color after refluxing completes the procedure. The optimum conditions which give the absorbance-concentration plot the maximum linearity and slope in the range of 0∼5 ppm COD are as follows: reflux at $100\circC$ for 10 min in the presence of 0.15 mM permanganate and 0.2% NaOH with a sample size of 5 ml. An overall running time was less than 15 min. The t-test reveals that the proposed method is not significantly different from the official method.

• The Journal of the Korea Contents Association
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• v.6 no.10
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• pp.1-8
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• 2006

The new system evaluating the pollution of the water quality for the branches of geum river using the fuzzy integral was proposed in this study. In this paper, the five individual factors, such as BOD(biochemical oxygen demand), COD(chemical oxygen demand), SS(suspended solids), T-N(total nitrogen), and T-P(total phosphorus) are selected. The measurement of fuzzy integral was determined depending on the degree of how they affect the pollution of water quality. The real values for the five factors measured and obtained from the branches of the geum river was normalized to ranging from 0 to 1. Finally, using the fuzzy integral, the degree of the pollution for the branches of geum river was expressed as the real numerical number. As a result, it appears that this approach can be proposed as the new system evaluating the pollution of the water quality for the branches of the geum river.

• Clean Technology
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• v.19 no.3
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• pp.295-299
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• 2013

This study was purposed and performed to evaluate removal efficiency of non-point source pollution in the process and system based on bio-retention design criteria regulated by EPA. Basic Column Reactors (BCR) were prepared for optimal determinations of inflow rate of first rainfall runoff and composition and ratio of soil layers. Removal efficiencies of non-point source pollution from synthetic runoff and real first rainfall runoff, directly sampled from motor way and parking lot, were analyzed, respectively. Removal efficiency of SS, BOD, COD, T-N, and T-P were all shown to be more than 80%.

• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.544-561
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• 2004

Weekly monitoring of discharge and water quality in forested and agricultural subcatchments were performed to understand the difference of water quality caused by land uses in Doegwollyong area. Correlations between water quality variables including discharge were analyzed for the same purpose. There was little variation of water Quality in forested subcatchment. On the other hand, the range of water quality variation in agricultural subcatchment was wide due to soil loss and the application of chemical fertilizers and livestock manure. Dissolved oxygen(DO) had strong negative correlation with discharge in both subcatchments. Total nitrogen(T-N) and potassium ion(K$^{+}$) had stronger positive correlation with discharge in forested subacatchment than in agricultural one. On the other hand, total suspended sediments(TSS), total phosphorus(T-P), and chemical oxygen demand(COD) had stronger correlation with discharge in agricultural subcatchment than in forested one. As water pollution of the Doam Lake, especially the increase of T-P is serious, soil conservation is very important to improve water quality. In particular, the loss of soil and nutrients from late June till early July were more serious than any other seasons, therefore it is necessary to apply environmentally sustainable methods of cultivation.n.

• Journal of Animal Environmental Science
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• v.1 no.2
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• pp.165-171
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• 1995

Aerobic treatment of animal slurries represents an increasingly popular option for farmers in the management of animal wastes. This study was performed to find out the chemical characteristics of dairy slurry associated with liquid-solid separation. Total solids concentration varies widely depending on the slurry manure handling systems. Hydrogen ion exponent(pH), volatile solids(VS), ammonia nitrogen(NH$_3$-N), nitrate nitrogen (NO$_3$-N), and chemical oxygen demand(COD) essentially depends on the total solids content of animal liquid wastes. Total solids content of the dairy slurry ranges from 6.6 to 7.5% depending on the feed slurry and separator. Separated liquids from dairy slurry have been successfully downed for up to about 21, 900mg/$\ell$ of the COD value. It has also been found that separated slurry decreased from 37.8 to 26.0mg/$\ell$ of the NO$_3$-N concentration.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.49-49
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• 1999

리튬 이차 전지를 박막화함으로써 개발된 고상의 마이크로 박막전지는 임의의 크기 및 형태로의 제작이 가능하며 액체전해질을 사용하지 않기 때문에 작동 중 열 또는 기체 생성물이 생기지 않아 높은 안정성을 갖으며 광범위한 사용 온도 범위를 가진다. 위와 같은 장점으로 인하여 충전 가능한 고상의 박막형 리튬 이차 전지는 점진적으로 그 사용 범위가 크게 확대될 것으로 판단된다. 즉, 초소형 전자, 전기 소자는 물론이며 조만간 실현될 스마트 카드, 셀루러폰 및 PCS와 같은 개인용 휴대 통신장비의 전력 공급계로의 응용이 가능할 것이다. 특히 장수명, 고에너지 밀도를 갖는 초소형의 전지를 필요로 하는 microelectronics, MEMS등에 이용될 수 있는 이차전지에 대한 요구가 점점 가시화 됨에 따라 박막공정을 이용한 이차전지개발기술이 요구되고 있으며, 박막제조기술을 이용한 고상의 박막형 및 전지에 관한 연구가 증가하고 있다. 본 연구에서는 박막형 리튬 이차전지의 Cathode 물질로써 비정질의 산화바나듐 박막을 반응성 스퍼터링에 의하여 상온에서 증착하였다. 박막형 이차전지의 여러 가지 Cathode 물질중 산화바나듐은 다른 물질들과는 달리 비정질 형태로 매우 우수한 충방전 특성을 나타낸다. 이런 특성으로 인해 다소 전지자체의 성능은 낮지만 저전력 저전압을 필요로 하는 초소형 전자 소자와 혼성되어 이용할 수 있는 잠재성이 매우 높은 물질이다. 바나듐 타겟의 경우 타겟 표면의 ageing에 따라 증착되는 박막의 특성이 매우 달라지게 되므로 presputtering의 시간을 변화시키면서 실험하였다. 또한 스퍼터링 중의 산소의 분압도 타겟의 ageing에 많은 영향을 주므로 실험 변수로 산소분압을 변화시키면서 실험하였다. 증착된 산화바나듐 박막의 표면은 scanning electron microscopy로 분석하였으며 구조 분석은 X-선 회절분석, X-ray photoelectron spectroscopy 그리고Auger electron spectroscope로 하였다. 증착된 산화바나듐 박막의 전기화학적 특성을 분석하기 위하여 리튬 메탈을 anode로 하고 EC:DMC=1:1, 1M LiPF6 액체 전해질을 사용한 Half-Cell를 구성하여 200회 이상의 정전류 충 방전 시험을 행하였다. Half-Cell test 결과 박막의 결정성과 표면상태에 따라 매우 다른 전지 특성을 나타내었다.

• KSBB Journal
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• v.8 no.2
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• pp.172-177
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• 1993

In order to reduce BOD of wastewater from alcohol distillery manufactory, the production of single cell lipid was attempted. Among five yeast strains tested, Rhodotorula glutinis was most desirable for lipid production. Wastewater was treated with 2N NaOH and used as a medium. The optimum pH and temperature for lipid production were found to be 5.0 and $30^{\circ}C$, respectively. The addition of monobasic phosphate was good for cultivation of Rhodotorula glutinis. The C/N ratio was an important factor for lipid production and composition. The best C/N ratio was 50 for the production of single cell lipid. By cultivation Rhodctorula glutinis for 4 days, 4g/L of single cell lipid was harvested and BOD of wastewater reduced by 88.7%.

• Microbiology and Biotechnology Letters
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• v.15 no.6
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• pp.396-401
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• 1987

Protein productivities of a cloned gene ($\beta$-galactosidase) and the cultural performances of two recombinant Escherichia coli strains, which use different host-vector systems, were studied. E. coli JM109/pTBG10 strain which carries Tac promoter had higher protein productivity than E. coli MH3000 (pRKc1857)/pASI(lacZ) strain which carries pL promoter. Induction of protein syn-thesis was optimum at the initial-and mid-logarithmic growth phases for both strains. Oxygen demand was observed to be very high during the cloned gene expression, and could be alleviated to some extent through pH control. The ratio of specific growth rates of plasmid-harboring to plasmidfree cell, $\mu$+ /$\mu$-, of the high productivity strain was observed to be lower than that of the low productivity one. Plasmid stability was analyzed for 20-30 generations, and it was found that the traction of plasmid-harboring cells dropped to l0% level in about 25 generations for both strains when the cloned gene expression was induced.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.3
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• pp.83-92
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• 1998

Field experiment was performed from August 1996 to January 1998 to examine the applicability of constructed wetland system for wastewater treatment in rural area. The pilot plant was installed in Kon-Kuk University and the school building septic tank effluent was used as an influent to the treatment basin. Hydraulic loading rate was about 0.1 6$0.16^3/m^2$ day and theoretical detention time in the system was 1.38 days. The treatment basin was composed of sand and reed. The influent DO concentration was low and many cases close to zero, but effluent concentration was higher than the influent which implies that oxygen was supplied naturally. The average concentration of influent BOD was 126mg/L, and with average removal rate of 69 % the average effluent concentration was 4Omg/L which satisfied the effluent water quality standard for the system of interest. The average influent concentration of COD was 2Olmg/L and average effluent concentration was 75mg/L with average removal rate of 60%. The performance of BOD and COD tends to deteriorate in the low temperature, and appropriate action needs to be taken during the cold winter time for stable operation. The average influent concentration of SS was 5Omg/L, and effluent was 1 1mg/L with average removal rate of 76% which satisfied the effluent water quality standard for the system of interest. The results for the regulated components, SOD and SS, from the experiment showed that constructed wetland system can meet the effluent water quality standards. The average influent concentration of total phosphorus was 25.6mg/L and average effluent concentration was 7.8mg/L with average removal rate of 63%. Not like the performance of the above components, average nitrogen removal rate was only 11.2% which is not satisfactory. Although, nitrogen is not regulated at this moment, it can cause many environmental problems including eutrophication. Therefore, nitrogen removal efficiency should be improved for actual application. From the result of the field experiment, constructed wetland system was thought to be an appropriate alternative for wastewater treatment in rural area.