• 생물환경조절학회지
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• 제25권1호
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• pp.49-56
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• 2016

본 연구는 의료살균기술의 하나인 전극을 이용한 전기충격 살균법을 순환식 수경재배의 배양액 재순환을 위한 배액 살균기술로 활용하고, 배액의 전기살균소독시스템을 구축하고자 할 때, 살균소독 효과가 높으며, 친환경적이고 경제적인 배양액 살균소독기술의 개발 및 전기살균소독시스템에서 사용될 전극의 최적 조건을 구명하고 전기소독의 가능성을 확인하기 위해 수행되었다. 전기살균소독시스템 구축 시 적정 전극소재 구명을 위해 금속 전도체의 특성 조사 및 전기실험을 실시하여 배액의 pH와 EC변화유무와 침전물 발생여부 및 배액의 원소변화 유무를 분석하였다. 새로이 개발된 전기살균소독시스템 구축 시 가장 적합한 금속 전도체 전극소재로는 전기전도도가 높고, 저항이 적으며, 소재의 수급이 용이하고, 가격이 저렴한 스테인리스 스틸임을 확인하였으며. 또한 스테인리스 스틸을 전극으로 사용하였을 때, 전기를 공급하기 전과 24V 이내의 전기를 공급한 후의 배양액내 원소변화는 거의 없는 것으로 분석되었다. 전극의 두께보다는 넓이가 증가함에 따라 전류의 양이 증가하였으며 전극의 거리가 멀수록 목표 전류량에 도달하는 시간이 증가하였다. 적합한 전류량에 따른 주요 병원균의 살균력을 조사한 결과 대표적 세균병인 풋마름병의 원인균인 Ralstonia solanacearum가 전류 15V-3A 170초에서 97%가 사멸되는 것을 확인하였으며 곰팡이병인 Fusarium oxysporum은 24V-10A에서 98%의 살균력을 보였다.

• 한국식품저장유통학회지
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• 제10권3호
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• pp.293-296
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• 2003

저장온도에 따른 1,000 mL 카톤팩의 벌지를 측정하기 위하여 원지 board의 물성을 측정하고, 저장조건에 따라 벌지를 측정하였다. 카톤팩 원지의 함수율은 5.6～7.0%, stiffness는 MD(machine direction) 방향이 243.3～266.7 g/cm, CD(cross direction) 방향이 99.2～109.2 g/cm였다. 카톤팩 낱장의 중량은 29.17～31.26 g이었다. 6$^{\circ}C$에 저장하면서 벌지를 측정한 결과, 저장 7일 후 6.33～6.93 mm였다. 1$0^{\circ}C$에 저장하면서 벌지를 측정한 결과, 저장 7일 후 7.26～8.56 mm였다. 1$0^{\circ}C$에 저장하면서 매일 1시간씩 상온 shock 처리 후 벌지를 측정한 결과, 저장 7일 후 8.66 mm였다. 저장온도 조건에 따른 카톤팩의 벌지는 6$^{\circ}C$ < 1$0^{\circ}C$ < 1$0^{\circ}C$＋상온 shock순으로 증가하였다. 따라서 벌지 예방의 최선책은 원지 및 카톤팩의 보관 및 관리 철저, 그리고 충전 후 냉장유통 과정에서 온도변화를 적게 해주는 것이라고 사료되며 본 실험결과가 카톤팩 벌지에 대한 최초의 연구보고라 생각된다.

• 한국세라믹학회지
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• 제12권2호
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• pp.3-9
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• 1975

The continuous grading method of pyrophyllite particles was adopted to prepare the refractories for ladle. The optimum conditions of fabrication adjusting the binders, the amount of water, the forming pressure and the firing temperature were investigated. The various properties, such as strength, density, porosity, thermal shock, corrosion resistance to slag were measured and compared with properties of ladle bricks presently used at local steel plants. The specimen studied in the present investigation showed a rather superior properties to theconventional product available locally.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.405-411
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• 2000

This study reviews qualitatively the flow characteristics around th tidal gap during seadike closures using a three-dimensional model for shallow water equations. The Princeton Ocean Model(POM) was adapted and applied to the Sihwa Seadike which was closed in 1994. The simulated flow patterns around the gap showed that tidal velocities increase with the cross-sectional area during ebb tide. The accelerated flow extended to wider zones passing the gap, and shock waves were generated. Vertical tidal velocity profiles were affected as the bottom scours developed beyond normal conditions.

• 환경위생공학
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• 제14권1호
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• pp.54-61
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• 1999

The industrial techniques of ultrasound have been used in the various fields, such as cleaning, medical surgery, emulsification, cell disruption etc. Especially the application of cell disruption was interested in the field of disinfection process in water by ultrasonic irradiation. It has been recognized that the ultrasounds are irradiated in aqueous solution, cavitation bubbles are generated and shock waves of high temperature and pressure are emitted as the bubbles are developed and finally broken, which function as a energy source to promote reaction efficiencies of various kinds of chemical reactions such as disinfection reaction in water. Therefore, this study was performed to apply the ultrasound for the disinfection method of infected drinking raw water and to discuss the limiting factors such as pH, sample volume and reaction temperature influenced on the removal efficiency of E. coli from experimental analysis of the results obtained in bench-scale plant. For the experiments to measure the influence of reaction parameters in the ultrasonic disinfection process, escalated reactivity of aqueous solutions was excellent when pH in aqueous solution was low, and sample volume was small. On the contrary, the reactivity of disinfection became elevated when reaction temperature was high. It was found that the rate constant of disinfection reaction was applied by Chick's law, reaction kinetics of Chick's law was irreversible and pseudo-first order at all the tested conditions.As a conclusion it appeared that the technology using ultrasonic irradiation can be applied to the treatment of disinfection in infected water which are difficult to be treated by conventional methods.

• 상하수도학회지
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• 제22권2호
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• pp.239-243
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• 2008

The fluctuation of inlet flow to a water treatment plant makes a serious problem that it can change the outlet flow-rate from each process abruptly, and ultimately occur the detachment of the attached particles inside each unit process. Also, since it takes very short time for the surface wave occurred from the fluctuation of inlet flow to reach the latter processes, it is impossible for operators to cope with that stably. Therefore this study was conducted to suggest the methodology for accurately predicting the travel time of surface wave occurred from the fluctuation of inlet flow to reach the latter process. Through the experiment, which was carried out for the full-scale water treatment plants(capacity : 2,000m3/d), it could be confirmed that the flow rate fluctuation from equalization tank produce the surface wave. And the wave transfer velocity is a function of the hydraulic radius and the length of each open type tanks which are comprised in the latter processes.

• Journal of Advanced Marine Engineering and Technology
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• 제8권2호
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• pp.25-38
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• 1984

Since the energy shock in 1973, there have been wide studies for the developments of the alternative energy source, the rationalization of the energy utilization and the energy economy because of the recognition of the limitation of energy source all over the world. This study is experimentally examined in and compared with the engine performance of output, torque and fuel consumption rate, and the exhaust emissions with the change of engine rmp in the cases of using water-gashol blends, gashol and gasoline as a fuel in a conventional 4 cycle 4 cylinder gasoline engine. In the case of using water-gashol blends, it is installed by the exhaust manifold pipe into the intake manifold, and water is injected from nozzle fitted up the air horn of the carburetor. The results are obtained as follows; 1. In the case of an addition with water, the engine output and the torque are little difference with the case of gasoline. 2. The fuel consumption rate is decreased as compared with the case of gasoline. Especially, the decrease in quantity is remarkable at the low rpm. 3. The exhaust emissions are remarkably decreased as compared with the case of gasoline. Especially, decreases of CO and HC in quantity are remarkable at the low rpm, and a decrease of No/sub x/ in quantity is remarkable at the high rpm. 4. There is a moderate condition of operation because the producing factors of NO/sub x/ and CO, HC are contrary to each other.

• 대한기계학회논문집B
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• 제35권7호
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• pp.677-683
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• 2011

지금껏 TNT 폭발에 의한 피해를 계산하는 방법에는 몇 가지 실험에 의한 모델이 제안되었다. 본 논문에서는 fire-ball 중심에서 가스가 단열이라는 가정하에 연속방정식, 오일러 및 에너지 방정식에 대한 해석적 해를 얻어 TNT 가 폭발 후 팽창하는 fire-ball 에 대한 시간에 따른 반경의 변화를 얻었다. 급격히 팽창하는 fire-ball 에 의한 충격파의 전파는 Kirkwood-Bethe 가정에 의해 구하였다. 해저에서 TNT 가폭발하게 되면 fire-ball 이 생성, 팽창해 기포로 거동하게 된다. 이 기포의 주기와 최대반경에 대한 계산 값을 실험 값과 비교한 결과 계산 값은 실험 값과 잘 일치 하였다.

• 대한기계학회논문집A
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• 제34권12호
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• pp.1821-1828
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• 2010

레이저 샥 피닝(LSP)은 금속재료 표면처리를 위한 획기적인 기술로서 금속 부품의 피로성능 개선을 위해 최근에 널리 적용되고 있다. 널리 알려진 바와 같이 금속재료의 피로 균열은 재료의 응력 상태가 인장(Tension)하에서만 발생되고, 압축(Compression)상태에서는 발생하지 않는다. 따라서 피로수명 개선을 위해 전통적인 샷 피닝(SP)과 함께 다양한 분야에 응용되고 있으며, 특히 LSP 는 금속재료의 표면과 깊이방향에 대해 높은 압축잔류응력을 생성시켜 준다. 본 논문에서는 유한요소 해석기법을 이용하여 LSP 에 의해 발생되는 압축잔류응력 생성과정을 모사하고, 압축잔류응력에 영향을 미치는 다양한 변수에 대해 민감도 해석을 수행하였다.

• Journal of Plant Biotechnology
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• 제44권3호
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• pp.287-295
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• 2017

Water temperature is one of the major factors that impacts the growth and life cycle of Pyropia tenera, one of the most valuable and cultivated marine red algae belonging to Bangiales (Rhodophytes). We analyzed transcriptome from gametophyte of P. tenera under normal and high temperature conditions, and identified four small heat shock proteins (sHSPs). They have no significant amino acid sequence homology with known proteins in public databases except PhsHSP22 from Pyropia haitanensis. PtsHSP19.3 gene responded to high temperature but slightly or not to desiccation, freezing or high salt condition. When the PtsHSP19.3 gene was overexpressed in Chlamydomonas reinhardtii, transformed Chlamydomonas lines revealed much higher growth rate than that of control cells under heat stress condition. Transformed cells also grew well in those of the control cell onto the medium containing high salt or $H_2O_2$. When the PtsHSP19.3 was fused to GFP and introduced into tobacco protoplast, fluorescence was detected at several spots. Results indicate that PtsHSP19.3 may form super-molecular assembles and be involved in tolerance to heat stress.