• Journal of Plant Biology
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• 제37권3호
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• pp.343-347
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• 1994

In order to compare the adjustment of 6 oak species to water stress, the components of water status, tissue elastic modulus, free proline content of leaves and morphological characteristics were determined in pot culture. uercus dentata and . mongolica responded effectively to drought with high root : shoot (R/S) ratio or maintenance of high turgor pressure by large and fast osmotic adjustment and . variabilis with maintenance of high turgor pressure by low elastic modulus under drought. Meanwhile, . aliena and . serrata responded effectively with low omotic potential (Ψo) at full saturation and . acutissima with long root in spite of rigid cell wall and high osmotic potential (Ψo) at full saturation. Proline content in leaves of . dentata, . mongolica and . aliena increased early and rapidly at high leaf water potential (Ψleaf). The results indicate that 6 oak species have adjustment different from each other to water stress.

• 동력기계공학회지
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• 제20권5호
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• pp.92-97
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• 2016

In this study, the seawater Heat Pump System using seawater with temperature of annual domestic conditions ($0^{\circ}C$ to $25^{\circ}C$) is designed in order to compare its performance against the Heat Pump using unused heat of seawater. As a potential replacement for current refrigerants that exacerbate global warming and ozone delpetion, a Low GWP refrigerant's performance is analyzed. The basic water to water Heat Pump system is chosen and three commercial refrigerants - R134a, R410a, R32 - are used to compare against new Low GWP refrigerant R1234ze. When seawater with temperature of $25^{\circ}C$ is used, the performance change showed maximal increase in COP, 38.3%. low GWP refrigerant R1234ze, showed great performance characteristics reach to 5.242 and Existing commercial refrigerant, R134a showed only less than 0.03 performance difference against R1234ze. The study confirms notable performance of R1234ze refrigerant through simulation as environmentally friendly refrigerant for domestic seawater Heat Pump.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.876-878
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• 2003

It was studied on the choice of potential area for red tide occurrence from oceanographic factors. Oceanographic factors of favorable marine environmental conditions for the red tide formation included warm water temperature, low salinity, high suspended solid, low phosphorus, low nitrogen. It was founded the potential areas for red tide occurrence in August 2000 by GIS conception: Yeosu~Dolsan coast, Gamak bay, Namhae coast, Marado coast, Goheung coast, Deukryang bay, respectively.

• Ocean and Polar Research
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• 제29권1호
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• pp.33-42
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• 2007

To obtain the overall distribution patterns and characteristics of the East Sea Intermediate Water (ESIW), the historical data obtained by the Japan Maizuru Marine Observatory (MMO) and the Korea Ocean Research and Development Institute (KORDI) were analyzed. To obtain water characteristics of the ESIW on isopycnal surfaces, temperature, salinity and dissolved oxygen were interpolated at every 0.01 interval of potential density. And then the interpolated values were averaged at the same potential density. This potential density average method preserved the salinity minimum layer more clearly compared to the depth average method. The potential density(${\sigma}_{\theta}$) range of the ESIW was $26.9{\sim}27.3$. The representative potential density of the ESIW was found to be 27.2, because the characteristics of the ESIW was clear at this density. From the horizontal distributions of physical properties on the isopycnal surface of $27.2{\sigma}_{\theta}$ it is suggested that the low salinity ESIW circulates anticlockwise over the whole basin with the high salinity intermediate water. The low salinity intermediate water extended from the northwestern part to the east along the sub-polar front and to the Ulleung Basin along the east coast of Korea.

• 생물환경조절학회지
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• 제16권3호
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• pp.174-179
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• 2007

참외 발효과 발생에 영향을 미치는 증산과 관련된 몇 가지 요인을 검토한 결과는 다음과 같다. 참외의 증산율은 지온이 높고 토양수분 함량이 많을수록 높았으며, 광도가 약하여 온도가 낮을 경우 증산율과 기공 전도도가 낮아졌고, 저온 다습한 기상조건에 의한 증산의 억제는 식물체와 대기사이의 증기압기울기가 낮아지는 것으로 생각된다. 발효과 발생은 과실의 비대가 느린 착색기 이후에 토양수분이 -10 kPa로 많고, 저온 다습하여 참외와 대기 사이에 증기압기울기가 낮게 형성되어 증산이 억제될 때 발생하였다. 따라서 참외의 발효과 발생은 착색기 이후 참외의 과실 비대가 지연되는 반면 지온이 높아 뿌리로부터 지상부로 수분의 공급이 원활하고, 저온 다습한 기상조건하에 수분의 증산이 억제되어 수분이 태좌부로 유입되면 발효과가 발생되는 것으로 생각된다.

• 한국작물학회지
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• 제30권1호
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• pp.33-38
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• 1985

토양수분, 질소시비량 및 도복의 발생 유무가 소맥엽신의 기공개도에 미치는 영향을 알고져 소맥 조광 품종을 공시하여 침윤법으로 개화기에 기공개도의 일중변화를 조사하였던바 그 결과는 다음과 같다. 1. 기공이 폐공되는 시각은 토양수분 Potential이 낮을수록 빨라졌으며 폐공되는 정도도 컸었다. 2. 기공개도는 하위엽이 상위엽에 비하여 작았고 토양수분 Potential 이 낮을수록 기공개도의 감소정도는 더욱 컸다. 3. 도복된 맥체의 기공개도는 정상 맥체에 비하여 작았는데 그 경향은 토양수분 정도 및 측정시각에 관계없이 동일하였다. 4. 질소 보비구는 소비구에 비하여 기공개도가 큰 일중변화를 하였는데 도복구나 건조구에서도 같은 경향이었다. 5. 도복후 일수가 경과함에 따라 기공개도는 크게 감소하였는데 도복후 6 일에는 무도복구에 비하여 50％이하의 개도를 보였으며 그 감소정도는 하위엽이 더욱 컸으며 일중에서는 오후에 현저하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2177-2181
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• 2007

In this paper, effective thermal conductivities of water-based $Al_2O_3$-nanofluids with low concentration from 0.01 vol. % to 0.3 vol. % are experimentally obtained by transient hot wire method (THWM). The water-based $Al_2O_3$-nanofluids are manufactured by two-step method which is widely used. To examine suspension and dispersion characteristics of the water-based $Al_2O_3$-nanofluids, Zeta potential as well as transmission electron micrograph (TEM) is observed. We confirm the manufactured $Al_2O_3$-nanofluids have good suspension and dispersion. The effective thermal conductivities of the water-based $Al_2O_3$-nanofluids with low concentration are enhanced up to 1.64% compared with that of DI water at $21^{\circ}C$. In addition, experimental results are compared with theoretical results from Jang and Choi model.

• International Journal of Fluid Machinery and Systems
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• 제7권2호
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• pp.68-79
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• 2014

The type of turbine developed is based on the very low head of water potential source for the electric power production. The area of research is focused for the axial water turbine that can be applied at the simple site open channel with has a very low cost and environmental impact compared to the conventional hydro installation. High efficiency of axial turbine which applied to the very low potential head will made this type of turbine can be used at wider potential site. Existing irrigation weir and river area will be the perfect site for this turbine. This paper will compare the effects of the variation of swirl velocity criterion during the design of the blade of guide vane and rotor of the turbine. Effects of the swirl velocity criterion is wider known as a vortex conditions (free vortex, force vortex and swirl velocity constant), and the free vortex is the very popular condition that applied by most of turbine designer, therefore will be interesting to do a comparison against other criterion. ANSYS Fluent will be used for simulation and to determine the predictive performance obtained by each of design criteria.

• 한국환경보건학회지
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• 제35권5호
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• pp.376-385
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• 2009

The characteristics of Lake Cheonhoji water and sediment were investigated in oder to utilize these as fundamental materials for the management of lake water quality. The hydrographic properties of Lake Cheonhoji which are relatively low chance of nutrients loading from the watershed and a long retention time of lake water, lead to the probability of high lake productivity. It was also observed that lake water showed stratification during summer and complete mixing during fall, even though water depth was relatively shallow. The trophic state was eutrophic to hypertrophic from summer to late fall. The overall properties of the sediment were oligohumic, high ignition loss and high composition of NAIP and Resid.-P, which might serve as potential pollution sources of lake water quality. In laboratory scale experiments, it was observed that leaching potential of nutrients in the sediment was greatly dependant upon water temperature and dissolved oxygen. Finally, water pollution in Lake Cheonhoji was considered to be largely due to the adverse cycle of uncontrollable eutrophication, which resulted in the subsequent occurrence of dead algae and animal plankton, organic sedimentation, reduction of dissolved oxygen and nutrients leaching, which again reinforced the cycle of eutrophication in the lake.

• 한국환경과학회지
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• 제25권1호
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• pp.173-179
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• 2016

Leaf water and osmotic potential, chlorophyll content, photosynthetic rate, and electrolyte leakage were measured to evaluate tolerance to water stress in wild-type (WT) and transgenic tobacco plants (TR) expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts. Leaf water potential of both WT and TR plants decreased similarly under water stress condition. However, leaf osmotic potential of TR plants more negatively decreased in the process of dehydration, compared with WT plants, suggesting osmotic adjustment. Stomatal conductance (Gs) in WT plants markedly decreased from the Day 4 after withholding water, while that in TR plants retained relatively high values. Relatively low chlorophyll content and photosynthetic rate under water stress were shown in WT plants since $4^{th}$ day after treatment. In particular, damage indicated by electrolyte leakage during water stress was higher in WT plants than in TR plants. On the other hand, SOD and APX activity was remarkably higher in TR plants. These results indicate that transgenic tobacco plants expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts improve tolerance to water stress.