• 설비공학논문집
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• 제8권4호
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• pp.463-472
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• 1996

Experiments were carried out to study the operation characteristics of a regenerator with a thermo-syphon pump and a surface-flame burner for a lithium bromide (LiBr)-water absorption heat pump. A cylindrical-shape metal-fiber burner and commercial grade propane were used. The emission of carbon monoxide and nitric oxide was measured by a combustion gas analyzer. Ther regeneration rate of water vapor as a refrigerant was measured. It could be as a reference value showing the performance of the regenerator. The circulation rate of the LiBr-water solution was also measured from both the tanks for the weak-and the strong-solution. Using a refractometer, the LiBr concetration in the solution was calculated from the measured refractory index of the solution. Temperature of the solution and the condensed water was recorded at several points in the experimental apparatus with thermocouples, using a personal computer. This data collecting system for measuring temperature was calibrated with a set of standard thermometers. The generating rate of water vapor as refrigerant increased linearly with heat supplied. It was about 4.0g/s with the heat supplied at a rate of 16,500kcal/h. The circulation rate of LiBr solution also increases with the heat supplied. The difference in LiBr concentrations between the weak and the strong solution was in the range of 1 to 5% when the concentration of the strong solution was about 60%. It was dependent upon both the heat supplied and the circulation rate of the solution. The initial concentration and the level of the LiBr solution in the regenerator were measured and recorded before experiments. The effect of them on the generating rate of water vapor and the circulation rate of the solution was also studied. The generating rate of water vapor was not strongly dependent upon both the level of the LiBr solution and the initial LiBr concentration. However, the concentration difference of the solution increases with the initial level of the LiBr solution.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.173-173
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• 2015

The flood water level in tidal river is determined by the joint effects of flood discharge and tidal water levels at downstream boundary. Due to the variable tidal boundary conditions, the evaluated design water levels associated with a certain flood event can be significantly different. To avoid determining of design water levels just by a certain tidal boundary condition and remove the influence of variability in boundary condition from the evaluation of design water levels, a probabilistic approach is considered in this study. This study focuses on the development of a method to evaluate the realistic design water levels in tidal river with taking into account the combined effects of river discharge and tidal level. The flood water levels are described by the joint probability of two driving forces, river discharge and tidal water levels. The developed method is applied to determine design water levels for the tidal reach of the Han River. An unsteady flow model is used to simulate the flow in the reach. To determine design water levels associated with a certain flood event, first, possible boundary conditions are obtained by sampling starting times of tidal level time series; then for each tidal boundary condition, corresponding peak water levels along the channel are computed; and finally, design water levels are determined by computing the expectations of the peak water levels. Two types of tides which are composed by different constituents are assumed (one is composed by $M_2$, and the other one is composed by $M_2$ and $M_2$) at downstream boundary, and two flood events with different maximum flood discharges are considered in this study. It is found that (a) the computed design water levels with two assumed tides have no significant difference for a certain flood event, though variability of peak water levels due to the tidal effect is considerably different; (b) tidal effect can reach to the Jamsil submerged weir and the effect is obvious in the downstream reach of the Singok submerged weir; (c) in the tidally affected reach, the variability of peak water levels due to the tidal effect is greater if the maximum flood discharge is smaller.

• 대한원격탐사학회지
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• 제16권2호
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• pp.117-133
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• 2000

We studied the sea level variations at Kerguelen island in the South Indian Ocean with ARGOS data and meteorological data during about 1 year(May 1993~April 1994) through using filter, spectral analysis, coherency and phase, and found characteristics for the two oceanic signal levels(detided oceanic signal level, h$_{detided}$ and seasonal oceanic level, h$_{corr.ib}$). The forms of atmospheric pressure variations are good agreed to between ARGOS data and meteorological data in the observed periods. This Kerguelen area shows the inflow of an air temperature(gain of a radiant heat) into the sea water and the stagnation of high atmospheric pressure bands in summer, and the outflow of a sea water temperature(loss of sensible and latent heat) toward the atmosphere and the stagnation of low atmospheric pressure bands in winter. The seasonal difference of sea level between summer and winter is about 1.6cm. Both the detided oceanic signal level(h$_{detided}$) variation and the inverted barometer level(h$_{ib}$) variation have a strong correlation for T>1day period bands. The characteristics of h$_{detided}$ variation are not decided by the influence of any meteorological distributions (atmospheric pressure), but the influence of other factors(bottom water temperature) for T>2days periods bands. h$_{corr.ib}$ plays a very important role of sea level variation in the observed periods (especially T>about 180days period bands).

• 한국조경학회지
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• 제32권5호
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• pp.63-72
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• 2004

This study was carried out to analyze effects of soil, water level and shading on growth of sweet flag(Acorus calamus var. angustatus). Three types of soil were used, which included sandy, silty loam and paddy loam soil. Three levels of shading were applied in the experiment: no shading, 55％ shading and 75％ shading. The water levels were also adjusted to three levels in the experiment. The results are summarized as follows; 1. The cultivation of sweet flag in sandy soil with low water level resulted in decreased fresh weight compared to that at planting. This result indicates that the water level should be maintained higher than the soil surface for sweet flag growth in sandy soil. 2. 5 out of 72 sweet flags died in paddy loam soil. Water saturation of soil easily reduced paddy loam soil, and root growth of sweet flags in reduced soil condition were restricted, resulting in the dead plants. 3. The growth of sweet flag in paddy loam soil was worse than those in silty loam, indicating that reduced soil conditions in paddy loam is harmful to root growth. In planting sweet flags in paddy loam, improved soil aeration in paddy loam soil is necessary for good growth of sweet flag. 4. The maintaining of high water levels is better than that of low water levels in sweet flag cultivation. During winter, soil near the water surface froze and sweet flags in frozen soil were stressed physiologically. Maintaining high water levels prevents soil from being frozen which is good for the growth of sweet flags. 5. There was not significant difference in the growth of the sweet flag between non-shading and 55％ shading. It thus appears that sweet flags can grow soundly under shading rate lower than 55％.

• 한국농촌생활과학회지
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• 제10권2호
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• pp.71-77
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• 1999

This study examined the effect of the pine needle sap administration on serum lipid composition and liver antioxidant defense system in rats fed with high fat diet. Forty eight male Sprague-Dawley rats were divided into six groups. three control groups were fed with 5% lipid diet and three high fat groups were fed with 30% lipid diet. Each group was administered with the following pine needle sap respectively : C-0.0, 1.ml water, C-0.5, 0.ml pine needle sap and 0.ml water C-1.0, 1.ml pine needle sap : H-0.0, 1.ml water, H-0.5, 0.ml pine needle sap and 0.ml water H-1.0, 1.0ml pinus needle sap. After 4 weeks of experimental periods the level of serum obtained and serum lipid was measured respectively. The results were as follows 1. Significant low level was observed for food intake, weight gain, FER in the experimental group administered with the pine needle sap. 2. No difference of the concentration of serum triglyceride was observed out the experimental group with 5% fat diet, however out of the experimental group with 30% fat diet it was low in (H-1.0) group where 1.0ml of the pine needle sap was administrated. 3. In the experimental group with 5% fat diet the concentration of serum total cholesterol and LDL cholesterol was low, especially the hypocholesteromic effect in serum administered by the pine needle sap was significantly high in group C-1.0 where 1.0ml of pine needle sap was administered. In the high fat group provided with 30% fat when the pine needle sap was administered there was a tendency that concentration of total cholesterol and LDL cholesterol decreased however there was no difference significantly. 4. Serum GOT activity was relatively high in high fat diet group. However, when 1$m\ell$ of pine needle sap was administered the activity was lower than that of the control group in H-1.0 group and the activity level was similar with that of the high fat diet group in c-1.0 group. There was no difference of serum GPT activitives followed by the administered of pine needle sap among the experimental group. 5. Liver TBARS levels were high in general in high fat diet group, however it showed no difference when the pine needle sap with different concentration level was administered. The results of this study indicate that the pine needle sap administration was effective in decreasing the food intake and weight gain of the experimental animals in the high fat diet and also effective in decreasing the levels of serum triglyceride, total cholesterol and LDL cholesterol and GOT activities. However it was not effective to change the level of TBARS and GSH -Px activities of liver. Thus, it was found that the pine needle sap administration was effective for the improvement of serum lipid composition condition of the experimental animals in the high fat diet group but it was not effective in the antioxidant defense system of liver.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1870-1872
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• 2005

In this study, an ultrasonic level limit sensor with a new structure utilizing the acoustic impedance matching is proposed to be able to check it out a change of water-level. 2 PZT resonators with the same property are bonded directly on the polyethylene plate. One resonator is for transmitter as an ultrasonic transducer, the other one is for receiver. In this case, a polyethylene plate will operate as an acoustic guider to transmit a transverse wave between 2 PZT resonators in air. While in the water, a polyethylene plate having a similar acoustic impedance with the water will be emitted an acoustic energy into the water as a longitudinal wave. According to this mechanism, there was a wide difference of acoustic signal output between underwater and in air. As a summary, this proposed level limit sensor could be used as a strong candidate with low cost and more stable one.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.352-353
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• 2005

In this paper, an ultrasonic level limit sensor with a new structure utilizing the acoustic impedance matching is proposed to be able to check it out a change of water-level. 2 PZT resonators with the same property are bonded directly on the polyethylene plate. One is for transmitter as an ultrasonic transducer, the other one is for receiver. In this case, a polyethylene plate will operate as an acoustic guider to transmit a transverse wave between 2 PZT resonators in air. While in the water, a polyethylene plate having a similar acoustic impedance with the water will be emitted an acoustic energy into the water as a longitudinal wave. According to this mechanism, there was a wide difference of acoustic signal output between underwater and in air. As a summary, it is believed that this proposed level limit sensor could be used as a new one with strong toughness from the external electrical and mechanical noise.

• 한방안이비인후피부과학회지
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• 제24권2호
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• pp.16-27
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• 2011

Objective : To investigate the effects of Pyeongwi-san-gamibang on atopic dermatitis, this study measured TEWL(transepidermal water loss), observed scratching behaviors and checked levels of Total IgE, IL-4, IFN-${\gamma}$ and conducted skin biopsy on NC/Nga mice with atopic dermatitis. Methods : NC/Nga mice were challenged with DNCB during 5 weeks to develop atopic dermatitis-like skin lesions. The NC/Nga mice with atopic dermatitis were divided into three groups of control group, PW-d, PW-e group. Once a day for 22 days, Pyeongwi-san-GamiBang extract with water was administered for the PW-d group and the extract with 80% ethanol was administered for PW-e group compared with saline solution for control group. During drug administration, sensitization by DNCB had lasted for three times per week. Results : 1. TEWL had no statistical difference among 3 groups. 2. The scratching behaviors had no statistical difference among 3 groups. 3. The levels of Total IgE in PW-d, PW-e group had a statistically significantly higher than that of the control group although difference between the control group and the PW-d, PW-e group were similar. 4. The level of IL-4 had no statistical difference among 3 groups. 5. The level of IFN-${\gamma}$ had no statistical difference among 3 groups. 6. As the observation of toluidine blue stained lesion, both PW-d and PW-e group had lower level of histamine releasement compared with the control group. Conclusion : Result based on these experiments, Pyeongwi-san-GamiBang on atopic dermatitis-like skin inflammation in NC/Nga mice is not effective. But, as the study showed significantly individual differece, we need to repeat these study after supplementing the object number and modified indicator of clinical severity.

• 한국농공학회논문집
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• 제53권4호
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• pp.59-65
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• 2011

The purpose of this study was to analyze the water quality change when wastewater applied to study paddy fields. CREAMS-PADDY (Chemical, Runoff and Erosion from Agricultural Management System) model was used to estimate the field-scale water quality. Simulated results were compared with observed data monitored from Byeongjeom study paddy fields which is located near the Suwon sewage treatment plant in Gyeonggi-do. Significance analysis was performed for the three different irrigation water quality level and five fertilizer reduction scenarios using LSD (Least Significant Difference) and DMRT (Duncan's Multiple Range Test). Total nitrogen was found to be significant for both irrigation water quality level and fertilizer reduction while total phosphorus was not. Annual drainage load for total nitrogen was reduced by 66~92 % compared to irrigation load when treated wastewater irrigated to study paddy fields from 2002 to 2007. Total phosphorus was reduced by 70~86 %.

• 한국항만학회지
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• 제5권2호
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• pp.65-75
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• 1991

Tidal current and water level change in coastal waters are formulated in terms of mathematical models. A systematic discussion of the derivation of a set of governing equations, expressing conservation of mass and momentum is presented. A simplification is introduced by integrating all variables and equations over the total water depth, the Solution of the formulated problem is achieved by using the finite difference method(FDM). The applied study area is taken from Mokpo harbor and its adjacent coastal water which have significant hydrographical changes due to the construction of the estuary barrage and land reclamation work of estuary barren. Some comparisons with the observed current and water level changes the numerical solutions are found to be considerably fit well for the recent coastal water motion.