• Journal of the Society of Naval Architects of Korea
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• v.40 no.5
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• pp.53-59
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• 2003

Ocean space utilization using VLFS(Very Large Floating Structures) can provide environmental impact free space by allowing sea water flow freely through the floating structure. Use of Pontoon type VLFS for that purpose needs employment of breakwaters for reduction of wave effects. Therefore, in order to maximize advantage of environmental impact free structure, the breakwater should be the one that can allow water flow freely through it, too. In this paper hydroelastic response of a pontoon type structure is analyzed considering breakwaters which allow water flow through its opening at bottom of the breakwaters. Mode superposition technique is used for solving equation of flexible body while interactions between the pontoon and breakwaters is considered based on generalized mode concept. Bi-quadratic nine node higher-order boundary element method is adopted for more accurate numerical treatment near sharp edged body shape. Performance of various combinations of breakwaters is investigated.

• Proceedings of the KSRS Conference
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• v.2
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• pp.764-767
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• 2006

It can be important framework data to monitor the change of land-use pattern of river boundary in design and management of river. This study analyzed the change of land-use pattern of Gab- and Yudeung River using time-series aerial images. To do this, we carried out radiation and geometric correction of image, and estimated land-use changes in inland and floodplain. As the analysis of inland, the ratio of residential, commercial, industrial, educational and public area, that is urbanized element, increases, but that of agricultural area shows a decline on the basis of 1990. Also, Minimum Distance Method, which is a kind of supervised classification method, is applied to extract water-body and sand bar layer in floodplain. As the analysis of land-use, the ratio of level-upped riverside land and water-body increases, but that of sand bar decreases. These time-series land use information can be important decision making data to evaluate the urbanization of river boundary, and especially it gives us goodness in river development project such as the composition of ecological habitat.

• Toxicological Research
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• v.19 no.4
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• pp.315-320
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• 2003

This study was carried out to investigate the effect of chitosan on lead metabolism in SD rats. Ten male rats were divided into a experimental group and a control group. Each experimental and control rats were administered by water contaminated with 100 mg/l of lead for 4 weeks, respectively. Experimental group received diets supplemented artificially with 5% of chitosan for 4 weeks. Body weight change, food and water consumption, fecal and urinary excretion, and fecal and urinary lead excretion were measured. There were no significant differences in body weight gain, food and water consumption, and fecal and urinary excretion between the two groups. However, fecal lead excretion of rats fed the diet containing 5% of chitosan were higher than the control group. Whereas urinary lead excretion of rats fed the diet containing 5% of chitosan were lower than the control group. The results suggested that the oral administration of chitosan prevents the gastrointestinal lead absorption in rats.

• The Korean Journal of Mycology
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• v.44 no.4
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• pp.314-317
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• 2016

To develop a new anti-dementia acetylcholinesterase (AChE) inhibitor from edible mushrooms, AChE inhibitory activities were determined on water and ethanol extracts of various edible mushrooms from oriental medicine markets and agriculture markets. As a result, the 70% ethanol extract from Pholiota adiposa fruiting body had the highest AChE inhibitory activity of 30.6, and its water extract also had an AChE inhibitory activity of 23.8%. Therefore, we finally selected P. adiposa as a potent anti-dementia AChE inhibitor-containing mushroom. The AChE inhibitor of P. adiposa was maximally extracted when its fruiting body was treated with water for 3hr at $70^{\circ}C$ and 70% ethanol for 12 hr at $70^{\circ}C$, respectively.

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.693-698
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• 2001

Ab initio density functional calculations on the structural isomers, the hydration energies, and the hydrogen bond many-body interactions for gauche-, trans-protonated ethylenediamine-(water)3 complexes (g-enH+(H2O)3, t-enH+(H2O)3) have been performed. The structures and relative stabilities of three representative isomers (cyclic, tripod, open) between g-enH+(H2O)3 and t-enH+(H2O)3 are predicted to be quite different due to the strong interference between intramolecular hydrogen bonding and water hydrogen bond networks in g-enH+(H2O)3. Many-body analyses revealed that the combined repulsive relaxation energy and repulsive nonadditive interactions for the mono-cyclic tripod isomer, not the hydrogen bond cooperativity, are mainly responsible for the greater stability of the bi-cyclic isomer.

• Geotechnical Engineering
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• v.12 no.6
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• pp.65-78
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• 1996

The Chungpyung Dam is a 16 yearn old rock-fill dam for a Pumped storage hydro-Power plant, located in the middle of the Korean Peninsula. Since the dam is subjected to the daily water level fluctuation, such as rapid drawdown and refill, thus inducing a structural impact on the behavior of dam body, it draws attention of many engineering concerns. Traditionally, steady-state analysis was employed to investigate the seepage in the dam body, but in this study the seepage analysis was numerically performed by 2-D FEM thansient analysis. As a boundary condition for an analysis, the water level fluctuation was incorporated to simulate the daily change. As a res41t, the various seepage phenomena such as hydraulic gradient, seepage vector, and pore water pressure distribution were quantified at the corresponding time of interest as the water level rises and recedes. The seepage flux was also estimated and compared with the measured data which were both acceptable considering design criteria. The result proves that there is no sign of hazardous sources contributing to the possibility of piping, internal erosion and excess leakage through the dam body.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.4
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• pp.345-351
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• 2011

Two feeding trials were conducted to investigate the optimum feeding rates in juvenile olive founder Paralichthys olivaceus fed practical expanded pellet(EP) containing 58.1% crude protein, 10.7% crude lipid, and 10.8% ash at low and high water temperatures. In the first experiment, triplicate groups of 15 fish with average weight of 7.7 g were fed at one of seven feeding rates(0, 1, 1.5, 2, 2.25, or 2.5% of body weight/day or to satiation) for 4 weeks at low water temperature. In the second experiment, quadruplicate groups of 20 fish with average weight of 5.5 g were fed at one of eight feeding rates(0, 3, 3.5, 4, 4.25, 4.5, or 4.75% of body weight/day or to satiation) for 4 weeks at high water temperature. Based on growth performance, we estimated that the optimum feeding rates for juvenile olive flounder were 1.97-2.51% and 4.82-6.36% of body weight/day at low and high water temperatures, respectively.

• The Korean Journal of Ecology
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• v.7 no.4
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• pp.232-238
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• 1984

The author hatched the eggs of Korean frog, Rana nigromaculata in natural water, and reared the tadpoles in natural water as control group and in seven copper ion groups contaminated by 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, and 1.0 ppm of copper ion. The influences of copper ion on the growth of the tadpoles were analyzed, and the results were summarized as follows: 1) The copper ion inhibited the growth of the tadpole. 2) The tadpoles were not survived for 20 days in the copper ion of 0.4~0.5ppm, and in the 0.7ppm, the tadpoles were not survived for 1 day after hatch. 3) The critical lethal concentration of Korean tadpole is regarded as 0.6ppm of copper ion. 4) The growth of head with and body length show a convexin increase pattern. 5) In the growth quantity of head width and body length, that of natural water shows the most rapid increase pattern, and that of the copper ion groups 0.1, 0.2, and 0.3ppm follows in that order. 6) The coefficient of relative growth($\alpha$) of control group is the greatest value, and that of the copper ion groups of 0.1, 0.2, and 0.3ppm follows in that order. The natural water shows the positive allometry, the contaminated groups shows the negative allometry in the relative growth of the contaminated groups to the natural water. 7) Body length shows positive allometry in the relative growth to head width.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1211-1218
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• 2005

Temperature variation according to space and time on the inner parts of engineering constructions(e.g.: dam, slope) can be a basic information for diagnosing their safety problem. In general, as constructions become superannuated, structural deformation(e.g.: cracks, defects) could be occurred by various factors. Seepage or leakage of water through these cracks or defects in old dams will directly cause temperature anomaly. Groundwater level also can be easily observed by abrupt change of temperature on the level. This study shows that the position of seepage or leakage in dam body can be detected by multi-channel temperature monitoring using thermal line sensor. For this, diverse temperature monitoring experiments for a leakage physical model were performed in the laboratory. In field application of an old dam, temperature variations for water depth and for inner parts of boreholes located at downstream slope were measured. Temperature monitoring results for a long time at the bottom of downstream slope of the dam showed the possibility that temperature monitoring can provide the synthetic information about flowing path and quantity of seepage of leakage in dam body.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.756-761
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• 2017

This study investigated the growth of juvenile mandarin fish Siniperca scherzeri, reared at high water temperatures. Feed-trained juvenile fish were reared at four water temperatures: 27, 29, 31, and $33^{\circ}C$. The fish were fed to apparent satiation twice daily using pelleted diet. After 10 weeks of feeding trial, the survival exceeded 98% in all groups. The weight gain of fish reared at $31^{\circ}C$ was higher than for fish reared at the other temperatures. The feed efficiency and protein efficiency ratio of fish reared at 29 and $31^{\circ}C$ were higher than for the fish reared at 27 and $33^{\circ}C$. The daily feed intake of fish reared at 27 and $33^{\circ}C$ was higher than for the 29 and $31^{\circ}C$ groups. The whole body moisture content of fish reared at $33^{\circ}C$ was higher than in the $27^{\circ}C$ group. The whole body crude protein and lipid contents of fish reared at $27^{\circ}C$ were higher than in the $33^{\circ}C$ group. The results indicate that suitable rearing water temperature was $31^{\circ}C$ for optimal growth and feed efficiency of juvenile mandarin fish under the experimental conditions.