• 한국물환경학회지
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• 제21권1호
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• pp.40-45
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• 2005

Sedimentation is one of the most common and important units in conventional water treatment plant. Structure such as various baffle walls and inclined plate settler may be obstacles to the horizontal flow when it is poorly designed. Therefore, the effects of these structures on characteristics of hydraulic flow must be evaluated to improve the settling efficiency of the floc. The hydraulic characteristic of the two sedimentations at Y water treatment plant (YWTP), which have different deflector baffles inside the settling basin, were investigated by tracer (fluoride) test. The inclined plate settler installed inside settling basin caused an undesirable impact on horizontal flow and produced dead zone. Solid baffle wall under the plate settler could help to minimize the formation of density currents and flow short circuiting. NaF used as a tracer was recovered more than 90% at investigated all basins. Morill index ($t_{90}/t_{10}$), Modal index ($t_p/T-HRT$) and short-circuiting index ($[M-HRT-t_p]/M-HRT$) were determined from tracer test results performed at YWTP. Those indices ranged 2.95~3.02, 0.40~0.53 and 0.32~0.46, respectively.

• The Korean Journal of Physiology
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• 제9권1호
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• pp.57-61
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• 1975

뇌 해마가 전기충격에 의한 내력(tolerance)에 미치는 영향을 구명하기 위하여, 두정 후두 경계 부위의 대뇌피질을 양측성으로 둥글게 떼어내고, 이를 거쳐 해마를 평균 97%가량 떼어버린 흰쥐(해마군) 14마리와 해마를 덮는 대뇌피질 부분만을 떼어버린 흰쥐(대뇌피질 대조군) 17마리 및 두개골을 노출하는데 그치고 뇌에 손상을 주지 않은 흰쥐(정상 대조군) 17마리를 사용하여 다음과 같은 실험을 실시하였다. 24시간 동안 먹이 없이 물만으로 지나게 한 다음 구금판에 세 무리를 구금하고 24시간 동안 매회 1.5초 동안씩 계속되는 4mA의 교류전류에 의한 충격을 1분 간격으로 반복하여 폐사하는 동물의 수효를 세어 다음과 같은 결과를 얻었다. 1. 전기충격을 가하는 동안 폐사한 동물의 수효에서 해마군의 값은 두 대조군의 값에 비하여 유의하게 적었으나, 두 대조군 사이에는 이렇다 할 차가 없었다. 2. 전기충격으로 인하여 폐사한 예에서 전기충격의 시작부터 폐사할 때까지의 시간은 해마군의 값이 두 대조군의 값에 비하여 연장된 경향을 보여 주었다. 이상의 결과로 미루어 뇌 해마는 전기충격에 대한 내력(耐力)에 억제적 영향을 끼친다고 추리된다.

• Advances in Traditional Medicine
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• 제7권3호
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• pp.254-260
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• 2007

Alstonia scholaris (Family: Apocynaceae) has been indicated for the treatment of various diseases, one among which is wound healing. The purpose of this study is to investigate the wound healing effect and antioxidant role of Alstonia scholaris leaves in animal models. The ethanol and aqueous extracts of Alstonia scholaris (EEAS, AEAS respectively) were tested against excision, incision and dead space wound models to evaluate the wound healing activity. In excision wound model, treatment was continued till the complete healing of wound, in incision and dead space wound models, the treatment was continued for 10 days. For topical application, 5% w/w ointment of EEAS and AEAS were prepared in 2% sodium alginate. For oral administration, EEAS was suspended in distilled water using Tween 80 and AEAS was dissolved in distilled water. The wound healing was assessed by the rate of wound contraction, period of epithelialisation, skin breaking strength, granulation strength, dry granulation tissue weight, hydroxyproline, collagen and histopathology of granulation tissue. Malondialdehyde level was also estimated to evaluate the extent of lipid peroxidation. AEAS and EEAS significantly promoted wound healing activity in all the wound models studied. Increase in the rate of wound contraction, skin breaking strength, granulation strength, dry granulation tissue weight, hydroxyproline and collagen, decrease in the period for epithelialisation and increased collagenation in histopathological section were observed with EEAS and AEAS treated groups. EEAS and AEAS also significantly decreased the levels of lipid peroxidation. The present study is suggestive that EEAS and AEAS promote wound healing activity.

• 한국자기학회지
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• 제11권3호
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• pp.97-103
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• 2001

Water-based 졸겔 증착법을 이용하여 디결정체 La$_{2}$3/Sr$_{1}$3/MnO$_3$(LSMO) 박막을 2000$\AA$ 두께의 열 산화층을 갖는 Si(100) 기판상에 제조하여 상온에서 LSMO박막의 두께변화 따른 저 자장영역(120 Oe)에서의 터널형 자기저항 변화를 연구하였다. XRD 회절분석 결과 단일상의 페롭스카이트 결정구조임을 알 수 있었으며 RBS 스펙트럼 분석결과 박막의 조성비 La:Sr:Mn:O는 0.67:0.33:1.0:3.0임을 알 수 있었다. LSMO 박막의 자성특성 측정결과 두께 증가에 따라 포화자화는 750$\AA$까지 급격한 증가현상을 보이다 150$\AA$을 기점으로 점차 감소하는 경향을 나타내고 있으며, 보자력은 800 $\AA$ 까지 급격한 증가를 보이다 일정해지는 경향을 볼 수 있었다. 저 자장영역에서의 터널형 자기저항 변화비는 약 1500 $\AA$의 두께 영역에서 최대값을 나타냄을 알 수 있었다. 이러한 저 자장 영역에서 LSMO 박막의 터널형 자기저항 변화비의 두께 의존성은 LSMO 박막과 Si 기판의 계면에 존재하는 상호확산 현상에 의한 dead layer의 존재 및 LSMO 박막의 열처리시 발생되는 열 격자 변형 효과로 설명하였다.

• 한국건축시공학회지
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• 제19권5호
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• pp.449-456
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• 2019

최근 비정형 건축물의 비중이 증가함에 따라 거푸집 재사용이 불가하여 건설폐기물이 증가하고 있는 추세이다. 또한 비정형 건축물 건축 시 생산자의 숙련도에 따라 비정형 패널의 품질이 결정되며 이에 따른 정확한 공사비 측정불가 및 인건비 증대라는 문제점이 있다. 본 연구는 이러한 비정형 건축물의 문제점을 보완하기 위하여 오차율이 적고 작업성이 좋은 최적의 배합을 찾는 것을 목표로 실험을 진행한다.

• 한국농공학회논문집
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• 제60권2호
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• pp.121-132
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• 2018

Along with climate change, it is reported that the extreme climate events such as severe drought could cause difficulties of agricultural water supply. To minimize such damages, it is necessary to secure the agricultural water resources by using or saving the amount of irrigation water efficiently. The objectives of this study were to develop paddy water management scenarios and to evaluate their effectiveness on water saving. Three water management scenarios (a) deep irrigation with ponding depth of 20~80 mm (control, CT), (b) no/intermittent irrigation until paddy cracks (water management A, WM-A), and (c) intermittent irrigation with ponding depth under 20 mm (water management B, WM-B) were developed. Water saving effects were analyzed using monitored data from experimental paddy fields, and agricultural water supply was analyzed on a reservoir-scale using MASA model. The observed irrigation amounts were reduced by 21 % and 17 % for WM-A and WM-B compared to CT, respectively, and mainly occurred by the increase of effective rainfall. The simulation results showed that water management scenarios could reduce irrigation by 21~51 % and total inflow by 10~24 % compared to CT. The long-term simulated water level change of agricultural reservoir resulted in the decrease of dead level occurrence for WM-A and WM-B. The study results showed that WT-A and WT-B have more benefit than CT in the aspect of agricultural reservoir water supply.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.183-186
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• 2003

This paper presents the results of slamming experiment using air pressure cylinder to increase the repeatability of the experiment. When it comes to the slamming experiment, the traditional way of doing it has been the free fall experiment. By adopting air pressure cylinder almost equal peak pressures were obtained with that of free fall experiment. Jet takes place when the wedge enters water. Slamming doesn't take place when Dead rise angle is more then 20 degrees.

• 상하수도학회지
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• 제26권1호
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• pp.29-35
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• 2012

A bio-encapsuled media was developed to apply on reducing odors produced from organic waste treatment process. The microorganism, candida tropicalis, was encapsulated in sponge media consisted of polyurethane material. Sodium alginate as a natural polymer which does not affect to hydrophilic microbes and PEGDA(poly ethylene glycol diacrylate) as a artificial polymer were used for the encapsuled media. The media was evaluated with TMEDA (N,N,N',N'-tetramethylethylenediamine, 0.02~0.1%) as a catalyst at different temperature 25 and $35^{\circ}C$. The best performance was achieved with 0.02% of TMEDA at $25^{\circ}C$. The microbes' activity in the media was examined by Live/Dead cell method.

• 태양에너지
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• 제11권2호
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• pp.34-40
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• 1991

Thermal stratification enhancement for the higher extraction efficiency of hot water storage tank was experimentally studied with transparent fiber glass cylindical tank($350{\ell}$, D=516mm, H=1680mm). Height to diameter ratio (H/D =1,2,3), flow rate(Q= 8,10,12LPM), inlet-outlet temperature differences(${\Delta}T=20,25,30^{\circ}C$), and geometry of inlet-outlet port were the parameters. In particular, three kind of distributors were used for geometry of inlet-outlet port. As a result, it was possible to get extraction efficiency of 95% by using the distributor having variable diameter but keeping a constant diameter of perforation. So it is recommendable to design the distributor so that the main pipe decrease in diameter toward the dead end.

• Environmental Engineering Research
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• 제11권4호
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• pp.201-207
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• 2006

A simple empirical model with good quantitative prediction of inter-particle and intra-particle distance in a cake layer with respect to ionic strength was developed. The model is an inverse length scale with functions of interaction energy and hydrodynamic factor and it explains that the inter-particle and intra-particle distance in a cake is directly related to the effective size of particles. Particle compressibility with respect to ionic strength was also predicted by the model. The model corroborated very well with experimental results of polystyrene microsphere latex particles microfiltation in a dead end operation. From the results of the model, specific cake resistance could be controlled by the same variables affecting the height of particle energy barrier described by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory.