• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.44-55
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• 1994

This paper describes the development of real-time irrigation reservoir operation models that adequately allocate available water resources for paddy rice irrigation. Water requirement deficiency index(WRDI) was proposed as a guide to evaluate the operational performance of release schemes by comparing accumulated differences between daily release requirements for irrigated areas and actual release amounts. Seven reservoir release rules were developed, which are constant release rate method (CRR), mean storage curve method(MSC), frequency analysis method of reservoir storage rate(FAS), storage requirement curve method(SRC), constant optimal storage rate method (COS), ten-day optimal storage rate method(TOS), and release optimization method(ROM). Long-term forecasting reservoir operation model(LFROM) was formulated to find an optimal release scheme which minimizes WRDIs with long-term weather generation. Rainfall sequences, rainfall amount, and evaporation amount throughout the growing season were to be forecasted and the results used as an input for the model. And short-term forecasting reservoir operation model(SFROM) was developed to find an optimal release scheme which minimizes WRDIs with short-term weather forecasts. The model uses rainfall sequences forecasted by the weather service, and uses rainfall and evaporation amounts generated according to rainfall sequences.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.243-247
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• 2012

Photocatalysis has been applied to decompose the waste and toxic materials produced in daily life and in the global environment. Pure $TiO_2$ (Zn-$TiO_2$-0) and Zn-doped $TiO_2$ (Zn-$TiO_2$-x, x = 3-10 mol %) samples were synthesized using a novel sol-gel and ammonia-evaporation method. The Zn-doped $TiO_2$ samples showed high photocatalytic activity for the degradation of methylene blue (MB). The physicochemical properties of the samples were investigated using XRD, SEM, ICP, DLS and BET methods. In addition, the most important measurement of photocatalytic ability was investigated by a UV-vis spectrophotometer. The effects of the mol % of zinc ion doping in $TiO_2$ on photocatalytic activity were studied. Among the mol % Zn ions investigated, the Zn-$TiO_2$-9 sample showed the highest photoreactivity. This sample removed 91.4% of the MB after 4 h, while the pure $TiO_2$ only removed 46.4% of the MB.

• Journal of the Korean Institute of Gas
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• v.22 no.4
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• pp.1-6
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• 2018

An LNG bunkering system stores LNG in a horizontal IMO's C-Type tank insulated with perlite powder, and $10^{-2}$ Torr vacuum in the annular space between the double walls. Current storage tanks have high heat leakage, evaporating over 2.0% daily. A more efficiently insulated storage tank reducing the evaporation rate is required to develope. This research carried out thermal analysis on a new effective insulation method, i.e. double shield insulation system, that separates high super vacuum in the annular space between two tanks with a perlite vacuum in the back side of outer tank. This highly efficient insulation system obtained an evaporation rate of 0.16% per day under a $10^{-4}$ Torr vacuum. Even if the space loses its vacuum, the new insulation system showed a lower evaporation rate of 5.23% than the present perlite system of 4.9%.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.197.1-197.1
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• 2010

This study was carried out to evaluate the operating performances of the evaporation desalination system with solar energy. This system was designed to use evacuated solar collector as the heat source, supplying the required heat energy and photovoltaic power as the electric source, supplying required power to pumps in the desalination system. The 5kW photovoltaic power generation system to make the electricity, the single-stage fresh water generator with plate heat exchanger, and remote control and monitoring system. Solar desalination system was designed and installed in Jeju-island, Korea in 2006, after about 4 years of operation, usability and stability of solar desalination system was guaranteed. The system comprises of the desalination unit which was designed to have daily fresh water capacity of $2m^3$, a $120m^2$ evacuated tubular solar collector to supply the heat, a $6m^3$ heat storage tank, and a 5.2kW photovoltaic power generation to supply the electricity to hydraulic pumps for the heat medium fluids. On a clear day, average daily solar irradiance in Jeju-island was measured to be $500W/m^2$ and the daily fresh water yield showed to be more than 500 liters under this condition. After around three years of a long term operation of the system from January 2007 to August 2009, average daily freshwater yield was analyzed to be around $330{\ell}$. The relationship equation between solar irradiance and freshwater yield was found to be y=1.1806x - 107.89.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.3
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• pp.37-45
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• 1980

This study was carried out to investigate the consumptive use of water for red peppers and soy beans. The correlation between the soil moisture contents and the selected meteorological factors during the growing season was analyzed. Characteristics of the drought at Jinju, Yeosu, Gwangju, and Mokpo area were figured out in view of frequency analysis. The results obtained from this study could be used as a reasonable criteria for the estimation of the duty of water in the design of upland irrigation systems. Obtained results are summarized as follows: 1. Red peppers were grown at the three levels of soil moisture contents; 75 percent, 50 percent, and 25 percent, respectively. The red pepper grown at the 75 percent of soil moisture content showed the highest yield. The total evapotranspiration during the growing season from red peppers was 471. lmm, which was 86.6mm less than the pan evaporation. 2. The soy bean grown at 75 percent soil moisture content showed the highest yield, although there was no signicant difference in yields among treatments. The total evapotranspiration during the growing season from the soy bean was 342.8 mm, which was 119.2mm less than the pan evaporation. 3. Coefficients of consumptive use(k) and meteorological data are shown on Table-9. 4. The significant correlations between the evapotranspiration and the humidity and daily temperature range were observed. Results are shown on Table-11.. Evaporanspiration can be easily estimated from the humidity and daily temperature range by using the equation...... (1) Ept=4.808-0.041H+0.207T.......(1) where, Ept; evapotranspiration(mm/day) H ; humidity(%) T ; daily temperature range ($^{\circ}C$) 5. The variations of soil moisture content during the growing season at the soil depth of 5cm, 15cm, and 45cm are shown on Fig. 4~9. The results of the correlation analysis between the evapotranspiration from the crops and the soil moisture content are shown on Table-12. The evapotranspiration can be estimated from soil moisture content at the different depth of the soil by using the equation....... (2). Ept = 3.433 - 0. 364M1 +0. 359M$_2$- 0. 055M$_3$....... (2) where, Ept; evapotranspiration (mm/day) M1 soil moisture meter reading at 5cm depth M$_2$; " 15cm " M$_2$; " 40cm " 6. The estimated probab]e successive dry days in selected areas are shown on Table 13. Gumbel-Chow method was used to calculate the probable successive dry days. Further investigation are required to obtain the more detailed and reliable results.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.210-215
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• 2004

The Purpose of this study are to develop the simulation(Tank model, Rainfall-runoff model) for the estimation of wily river discharge and for evaluation of wily pollutant loads from the watersheds of the objected basin area. As apply this constructed Tank model to Nakdong river region, we evaluated the wily river discharge of Nakdong river from use-land conditions, precipitation and evaporation data of 3 years(from 1998 to 2000) and investigate the seasonal fluctuation of SS, COD, TN, TP inflowing into Nakdong river. The result shows that summer has high pollutant level than winter in seasonal characteristic and the down stream has high pollutant level than the upper stream. The annual average of SS, COD, TN, TP flawing in Nakdong river(Samranjin) was estimated each 691ton-COD/year, 1854.2ton-SS/year, 382.8ton-TN/year and 13.0ton- TP/year.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.605-609
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• 2005

This study is to perform the rainfall-runoff analysis of the basin of Yongdam dam where is loacted in the Geumriver basin. The model used is the SAC-SMA model which was developed by U.S. National Weather Service. The Precipitation data used as the input data of the model are daily ones observed in 2002 and the mean of values recorded in 5 rainfall stations. The evaporation data are used observed in Daejeon meteorological station. The geographical data such as basin slope and stream gradient are elicited from the numerical map analysis. In the verification through the comparison of calculated daily inflow with observed one, parameters used in the model are estimated manually. As the result of verification, total annual calculated inflow is 13,547CMS and agree accurately with the observed one. During the period of one year of 2002, before 100 days and after 250 days, the soil moisture condition in the upper zone was significantly dry and in spite of the rainfall in this period, the runoff was not generated. Through this result, we can observe that the moisture condition in the soil affects strongly the runoff in a basin.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.2
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• pp.111-117
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• 2008

We estirmted the yearly and monthly variation in discharge from the Nakdong River Barrage. We studied the total monthly discharge, the mean daily discharge, and the maximum daily discharge based on the observational discharge data for the 11-year period 1996-2006. We also examined the correlation between the discharge and the meteorologiml factors that influence the river inflow. The results from this study are as follows. (1) The total monthly discharge for 11 years at the Nakdong River Barrage was $224,576.8{\times}10^6\;m^3$: The daily maximum was in 2003, with $56,292.3{\times}10^6\;m^3$. The largest daily mean release discharges occurred in August with $52,634.2{\times}10^6\;m^3$ (23.4% of the year), followed by July and September in that order with 23.1 and 17%, respectively. (2) The monthly pattern of discharge could be divided into the flood season for the period July-September (discharge =$1000{\times}10^6\;m^3$/day), the normal season from April to June and October (discharge=$300{\times}10^6\;m^3$/day), and the drought season from December to March (discharge < $300{\times}10^6\;m^3$/day). (3) Periods of high temperature, low evaporation loss, and short sunshine duration produced a much higher discharge in general. Conditions of low rainfall and high evaporation loss, as was the rose in 2003, tended to reduce the discharge, but high rainfall and low evaporation loss tended to increase the discharge as it did in 200l. (4) The dominant wind directions during periods of high discharge were NNE (15.5%), SW and SSW (13.1%), S(12.1%), and NE (10.8%) This results show that it run bring on accumulation of fresh water when northern winds are dominant, and it run flow out fresh water toward offslwre when southern winds are dominant.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.876-880
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• 2015

In 2016, the IMO's new rules for an 80% reduction in NOx emissions in newly built ships will necessitate the use of LNG as a clean fuel. So far, the developed European countries have led the development of LNG bunkering ships and related facilities. An LNG bunkering system stores LNG in a horizontal or vertical IMO "C"-Type tank insulated with perlite powder, and a vacuum in the annular space between the double walls, like the cryogenic liquid nitrogen tank. Current storage tanks have high heat leakage, evaporating over 2.0% daily, and are difficult to build with the required vacuum. A more efficiently insulated storage tank could reduce the evaporation rate. This research carried out thermal analysis on a new effective insulation method that separates high vacuum in the annular space between two tanks with a solid insulation material, such as urethane foam, lining the outer vessel. This highly efficient insulation system obtained an evaporation rate of 0.03% per day under a $10^{-3}torr$ vacuum, and an evaporation rate of 0.11% at $10^{-45}torr$. Even if the space loses its vacuum, the new insulation system showed a lower evaporation rate of 4.12% than the present perlite system of 4.9%. This newly developed tank can increase the efficiency of LNG storage tank and may help keep LNG bunkering systems safe.

• Journal of Korea Water Resources Association
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• v.39 no.3 s.164
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• pp.261-274
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• 2006

This study performs a daily long-term runoff analysis for 30 years to forecast medium- and long-term probabilistic reservoir inflows on the Soyang River basin. Snowmelt is computed by Anderson's temperature index snowmelt model and potenetial evaporation is estimated by Penman-combination method to produce input data for a rainfall-runoff model. A semi-distributed TOPMODEL which is composed of hydrologic rainfall-runoff process on the headwater-catchment scale based on the original TOPMODEL and a hydraulic flow routing model to route the catchment outflows using by kinematic wave scheme is used in this study It can be observed that the time variations of the computed snowmelt and potential evaporation are well agreed with indirect observed data such as maximum snow depth and small pan evaporation. Model parameters are calibrated with low-flow(1979), medium-flow(1999), and high-flow(1990) rainfall-runoff events. In the model evaluation, relative volumetric error and correlation coefficient between observed and computed flows are computed to 5.64% and 0.91, respectively. Also, the relative volumetric errors decrease to 17% and 4% during March and April with or without the snowmelt model. It is concluded that the semi-distributed TOPMODEL has well performance and the snowmelt effects for the long-term runoff computation are important on the study area.