• Water for future
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• v.10 no.2
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• pp.113-124
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• 1977

Alone the southwesten coast of Korean peninsula, the extensive available arable acreages suited for forming are found in the development of tidal flats in the geographically curved bays with a motable tidal emplitude. It was found that the developments of these tidal flats cover an estimated area more than 276,000ha. In this paper, a flood control system by Pul's Storage Indication Method and Pul's Graphical Method at Return Periods-50 yrs, design rainfall-267mm per 48hrs and design flood-926c.m.s. and at 0.2meter control height above the High Water Ordinary Spring Tide Level (+11.0m) was studied. At the result, the flood demage in the reservoir at Return Periods-50 yrs and the tidal level at H.W.O.S.T.L. were satisfied to the below E.L. 11.20m (Flood Level in the reservoir). Well skilled flood control technique and management and control of draining sluice gate should be required for the disaster prevention from the flood and tide damage.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.89-102
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• 2010

Future uncertainty on water demand caused by future climate condition and water consumption leads a difficulty to determine the reservoir operation rule for supplying sufficient water to users. It is, thus, important to operate reservoirs not only for distributing enough water to users using the limited water resources but also for preventing floods and drought under the unknown future condition. In this study, the reservoir storage is determined in the first stage when future condition is unknown, and then, water distribution to users and river stream is optimized using the available water resources from the first stage decision using 2-stage stochastic linear programming (2-SLP). The objective function is to minimize the difference between target and actual water storage in reservoirs and the water shortage in users and river stream. Hedging rule defined by a precaution against severe drought by restricting outflow when reservoir storage decreases below a target, is also applied in the reservoir operation rule for improving the model applicability to the real system. The developed model is applied in a system with five reservoirs in the Han River basin, Korea to optimize the multi-reservoir system under various future water demand scenarios. Three multi-purposed dams - Chungju, Hoengseong, and Soyanggang - are considered in the model. Gwangdong and Hwacheon dams are also considered in the system due to the large capacity of the reservoirs, but they are primarily for water supply and power generation, respectively. As a result, the water demand of users and river stream are satisfied in most cases. The reservoirs are operated successfully to store enough water during the wet season for preparing the coming drought and also for reducing downstream flood risk. The developed model can provide an effective guideline of multi-reservoir operation rules in the basin.

• Journal of the Korean Professional Engineers Association
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• v.17 no.4
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• pp.8-14
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• 1984

In this part of the studies on dielectric dehydration of foamed fish-starch paste, quality stability and shelflife of the product of which the preparation formula and processing conditions were described in the previous report (Lee et at., 1982) were determined by means of accelerated reaction test. The product was stored for 50 days under the conditions of temperatures at 35, 45, and 55$^{\circ}C$ in steady state and various water activities of 0.44, 0.52, 0.65, and 0.75, respectively. The loss of available lysine, the extent of TBA value, and the development of browning during the storage were measured and reaction kinetically analysed to assess quality stability and shelf-life of the product for the storage at room temperature of 25$^{\circ}C$. The extent of browning was accelerated with the increase of water activity and temperature marking the time to reach a limit of color and flavor deterioration, or to reach brown color density of 0.17 O.D./g at 420nm, 106 days at a$\_$w/=0.44, 35$^{\circ}C$, and 41 days at aw=0.65, 55$^{\circ}C$. These reaction rates resulted in a prediction of shelf-life, 130 to 110 days in the storage at au=0.44 to 0.75, 25$^{\circ}C$. The quality limit assessed by TBA values and sensory evaluation of rancidity was 87 days at a$\_$w/=0.44, 35$^{\circ}C$, and 30 days at aw=0.73, 55$^{\circ}C$ which gave a predicted shelf-life, 128 to 113 days at a$\_$w/=0.44 to 0.75, 25$^{\circ}C$ storage.

• Solar Energy
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• v.7 no.2
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• pp.22-29
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• 1987

This paper dealed with thickness variation of bottom heat sotrage zone due to salinity and flow rate of extration hot brine in small test solar pond (0.5m wide, 0.5m high, 1.0m long). Testing apparatus and situation were follows: 7.1 cm of height of suction diffuser and 1.8cm of height of discharge diffuser above the test pond respectively, 0.3cm of slot size of suction diffuser, 1.0cm of slot size of discharge diffuser, 47cm of length of the slot; heating of hot water ($75^{\circ}C$) through separated hot water tank, discharge of the brine into storage zone through discharge diffuser, the extration of the brine through suction diffuser, circulation of the extracted brine through a heat exchanger (cooler). Following results were obtained through the experiments. 1. In small test solar pond, the typical three zone which showed up in real solar pond were established. 2. Richardson Number was used more effectively to confirm hydrodynamic stability of the stratified flow. 3. The thickness of non convective layer had a great effect on the heat storage of the bottom convective layer, then the temperature of bottom convective layer had a relation to that of upper convective layer. 4. Optimum operating condition in the test pond was on 10%-15% of salt concentration and $0.05m^3/hr$ of flow rate of extraction hot brine. 5. Following thickness of 3 zones were available to obtain under optimum operation condition: o bottom storage zone: $30%{\pm}10%$ of total pond depth o non-convective zone: $40%{\pm}10%$ of total pond depth o Upper surface zone: $20%{\pm}10%$ of total pond depth.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.4
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• pp.4001-4008
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• 1975

The economic evaluation of the feasibility of expanding fully irrgated agriculture in the Ogseo project must consider preproject yields of rice under rainfed and partially irrigated paddy cultivation in order to assess incremental incomes from irrigation. Statistical data on yields available from official sources and field surveys conducted in the project area do not specify whether given unit yields refer to actually cropped or potentially cropped lands. This latter factor obviously affects any evaluation of marginal benefits to be derived from irrigation as the extent of rainfed areas actually cropped varies from year to year according to rain fall at the critical growth periods for low land rice. Although less dependent on direct rainfall, yields from partially irrigated lands are also highly affected by seasonal rainfalls. In this paper on attempt has been made to determine average yield under rainfed and partially irrigated conditions by relating yields to a available water. For rainfed paddy cultivation, the analysis discriminates between effects of rain deficiencies during transplanting and subsquent growth periods. For partially irrigated paddy cultivation, seasonal rainfalls have been considered, implying sufficient storage capacity for supplementary irrigation. The average yield of rainfed paddy has been calculated as 2.11 t/ha and that of partially irrigated paddy as 2.8 t/ha. Assuming even division between these two water supply patterns of areas not fully irrigated, a composite yield of 2.46 t/ha is oftained. This figure will be adopted as the basis for the on-going studies and project evaluation.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.3
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• pp.11-19
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• 2017

The decision-making process is the act of finding the best solution among various alternatives through comparison between various criteria based on objectives of the project, evaluation standard, and conditions. However, in practice it is not easy to simply decide the optimum decision, especially for selecting malfunctioning reservoirs because no systematic evaluation criteria or standard assessment process are available. Therefore, this study adopted AHP method, which is a MCDM (multi-criteria decision making technique) to identify the malfunctioning reservoirs for efficient management of reservoirs. Important criteria of the selection of malfunctioning reservoirs and priority weights of each criteria were determined based on results of expert's survey under a stepwise hierarchical approach. The most important factor for the decision of malfunctioning reservoirs was obtained as Reservoir efficiency among the selected criteria including Reservoir efficiency decrease, Disaster Risk, Reservoir efficiency, Available water storage, Future water demand, Resident Needs. The AHP technique was applied on 11 reservoirs in Andong region to verify its applicability. Scoring method was applied for the comparison with the results of AHP method.

• Journal of Korea Water Resources Association
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• v.39 no.8 s.169
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• pp.645-658
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• 2006

A hydrological drought index, MSWSI (Modified Surface Water Supply Index) was suggested based on SWSI. South Korea was divided into 32 regions considering the distribution of available gauge station of precipitation, dam storage, stream water level and natural groundwater level. The indices estimated in the regions represent a spatially distribution of drought. Monthly MSWSI was evaluated for the period of 1974 and 2001. The result was compared with PDSI and checked the applicability of the suggested index in our hydrologic drought situation.

• Journal of Forest and Environmental Science
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• v.31 no.1
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• pp.14-23
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• 2015

In this study, we investigated the effects of three land uses on soil properties in two soil layers; surface soil (0~15 cm) and subsoil (15~30 cm). Soil samples were collected from planted forest, barren lands and cultivated lands from different areas in Chittagong Cox's Bazar and analyzed for some physical and chemical properties. Results showed that soil textural class varied from sandy clay loam in planted forest and barren land site to sandy loam in cultivated soils. Maximum water holding capacity was higher in forest followed by barren land and the lowest in cultivated lands. At both soil depths, soils of cultivated land showed the highest values of bulk density (1.42 to $1.50g\;cm^{-3}$), followed by barren lands (1.37 to $1.46g\;cm^{-3}$) and the least (1.32 to $1.45g\;cm^{-3}$) in forest soils. Total porosity decreased with depth ranging from 40.24% to 41.53% in subsoils and from 42.04 to 43.23% in surface soil of cultivated and of planted forest sites respectively. The result further revealed that organic carbon (OC) and total nitrogen (TN) contents were higher in the planted forest soil than in other two land uses. The soils of all land uses under study are acidic in nature and the lowest pH was found in both surface and subsoils of barren land. Cultivated soil contained the highest amount of available P, Ca, Mg and K in both surface soil and subsoils. In contrast, barren site had the lowest contents of available P, Ca, Mg and K in both layers. The soil organic carbon (SOC) and total N storage were higher in planted forest than in barren and cultivated land uses.

• Water for future
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• v.29 no.6
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• pp.203-215
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• 1996

A physically based model for rainfall-runoff simulation in agricultural watersheds equipped with tile drains is developed from the TOPMODEL framework. The model is based on detailed topographical information provided by the Digital Elevation Model (DEM), which is available in the Geographic Information System GRASS. Nine possible flow generation scenarions are suggested and used in the development of the model. The storage and delaying effects in the soil matrix and in the tile system are simulated with a second order linear reservoir. The model can identify the portions of the hydrators resulting from tile flow, subsurface flow and surface runoff.

• Water for future
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• v.29 no.4
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• pp.109-118
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• 1996

The neural network is a mathematical model of theorized brain activity which attempts to exploit the parallel local processing and distributed storage properties. The neural metwork is a good model to be applied for the classification problem, large combinatorial optimization and nonlinear mapping. A multi-layer neural network is constructed to predict rainfall. The network learns continuourvalued input and output data. Application of neural network to 1-hour real data in Seoul metropolitan area and the Soyang River basin shows slightly good predictions. Therefore, when good data is available, the neural network is expected to predict the complicated rainfall successfully.