• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.634-645
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• 2011

A newly developed rainwater harvesting (RWH) system reliability model is evaluated for roof area of buildings in Haeundae District of Busan. RWH system is used to supply water for toilet flushing, back garden irrigation, and air cooling. This model is portable because it is based on a non-parametric precipitation generation algorithm using a markov chain. Precipitation occurrence is simulated using transition probabilities derived for each day of the year based on the historical probability of wet and dry day state changes. Precipitation amounts are selected from a matrix of historical values within a moving 30 day window that is centered on the target day. Then, the reliability of RWH system is determined for catchment area and tank volume ranges using synthetic precipitation data. As a result, the synthetic rainfall data well reproduced the characteristics of precipitation in Busan. Also the reliabilities of RWH system for each of demands were computed to high values. Furthermore, for study area using the RWH system, reduction efficiencies for rooftop runoff inputs to the sewer system and potable water demand are evaluated for 23%, 53%, respectively.

• Journal of Bio-Environment Control
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• v.30 no.1
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• pp.46-55
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• 2021

This experiment was conducted to investigate the effect on chlorophyll fluorescence, stem sap flux relative rate (SFRR) and leaf temperature of cucumber when irrigation is controlled using a soil moisture tensiometer. Cucumber (Cucumis sativus L.) 'Chungchun' was irrigated of 10-10-20 kPa and 20-10-10 kPa by soil starting point of irrigation at each growth stage. At the 66 days after treatment (DAT) of 736 to 854 W·m-2 and above 32℃, chlorophyll fluorescence variables (Fo, Fm, Fv/Fm) values showed significantly different between treatments. The Fo and Fv/Fm value in the daytime (10:30 am to 6:00 pm) at 66 DAT was higher in 20-10-10 kPa treatment than in 10-10-20 kPa treatment. The Fv/Fm value decreased when the leaf temperature was increased. There was no difference in leaf growth (length, width and area) at 28 and 66 DAT, but the chlorophyll content (SPAD value) was significantly higher in 20-10-10kPa treatment. SFRR and leaf temperature increased with light intensity and temperature increased. In both treatments, the SFRR started to increase sharply between 8 am and 9 am when the solar radiation is 170 W·m-2 or higher. The soil temperature of the treatments decreased after irrigation, that showed 31.0℃ at 10-10-20kPa and 28.5℃ at 20-10-10kPa on July 5 (820W·m-2 at 1 pm). However, there was no difference in SFRR, leaf temperature, temperature difference (leaf temperature - air temperature) and VPD between treatments. SFRR was significantly positive correlate with the leaf temperature (p < 0.01, r = 0.770). The SFRR and leaf temperature showed positive significant correlation with solar radiation, temperature, soil temperature, soil moisture content and VPD. There was a negative significant correlation with relative humidity and temperature difference.

• Ecology and Resilient Infrastructure
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• v.6 no.2
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• pp.79-88
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• 2019

In order to study the water quality status and its causal environmental factors, the water quality variables of chemical oxygen demand (COD), chlorophyll a (Chl a), Total phosphorus (TP), and total nitrogen (TN), the hydrogeomorphologic variables of water level fluctuation, total water storage, dam elevation, watershed area, and shoreline development index, and the land cover variables of forest, agricultural area, and urbanized area in the watershed were investigated in total 73 reservoirs with various operational purposes, water level fluctuation and geographical distribution in South Korea. The water quality was more eutrophic in the reservoirs of the more urbanized and agricultural area in the watershed, the low altitude, the narrow water level fluctuation, the narrowed watershed area, and the more circular shape. In terms of the purposes of reservoir operation, the reservoirs for agricultural irrigation were more eutrophic than the reservoirs for flood control. The results of the variable selection and path analysis showed that COD determined by Chl a and TP was directly affected by water level fluctuation and the shoreline development of the reservoirs. TP was directly affected by the urbanized area of the watershed which was related to the elevation of the reservoir. TP was also influenced by the water level fluctuation and the shoreline development. In conclusion, the eutrophication of the reservoirs in Korea would be influenced by the land use of the watershed, hydrological and geographical characteristics of the reservoir, water level fluctuation by the anthropogenic management according to the reservoir operation purpose, and the location of the reservoirs.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.266-274
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• 2010

This study aim to investigate fundamentally the growth and physiological responses of tomato plants in responses to two different levels of water deficit, a weak drought stress (-25 kPa) and a severe drought stress (-100 kPa) in soil. The two levels of water deficit were maintained using a micro-irrigation system consisted of soil sensors for the real-time monitoring of soil water content and irrigation modules in a greenhouse experiment. Soil water contents were fluctuated throughout the 30 days treatment period but differed between the two treatments with the average -47 kPa in -25 kPa set treatment and the -119 kPa in -100 kPa set treatment. There were significant differences in plant height between the two different soil water statuses in plant height without differences of the number of nodes. The plants grown in the severe water-deficit treatment had greater accumulation of biomass than the plants in the weak water-deficit treatment. The severe water-deficit treatment (-119 kPa) also induced greater leaf area and leaf dry weight of the plants than the weak water-deficit treatment did, even though there was no difference in leaf area per unit dry weight. These results of growth parameters tested in this study indicate that the severe drought could cause an adaptation of tomato plants to the drought stress with the enhancement of biomass and leaf expansion without changes of leaf thickness. Greater relative water content of leaves and lower osmotic potential of sap expressed from turgid leaves were recorded in the severe water deficit treatment than in the weak water deficit treatment. This finding also postulated physiological adaptation to be better water status under drought stress. The drought imposition affected significantly on photosynthesis, water use efficiency and stomatal conductance of tomato plants. The severe water-deficit treatment increased PSII activities and water use efficiency, but decreased stomatal conductance than the weak water-deficit treatment. However, there were no differences between the two treatments in total photosynthetic capacity. Finally, there were no differences in the number and biomass of fruits. These results suggested that tomato plants have an ability to make adaptation to water deficit conditions through changes in leaf morphology, osmotic potentials, and water use efficiency as well as PSII activity. These adaptation responses should be considered in the screening of drought tolerance of tomato plants.

• Korean Journal of Agricultural Science
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• v.26 no.2
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• pp.77-93
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• 1999

This study is aiming at identifying the foreward and backward lingkage effects of the farm land base development project. Korean Government has continuously carried out farmland base development projets including the integrated agricultural development projects. large and medium scale irrigation projects and the comprehensive development of the four big river basin including tidal land reclamation and estuary dam construction for the all weather farming since 1962. the starting year of the five year economic development plans. Consequently the irrigation rate of paddy fields in Korea reached to 75% in 1998 and to escalate the irrigation rate, the Government had procured heavy investment fund from IBRD. IMF and OECF etc. To cope with the agricultural problems like trade liberalization in accordance with WTO policy, the government has tried to solve such problems as new farmland base development policy, preservation of the farmland and expansion of farmland to meet self-sufficiency of foods in the future. Especially, farmland base development projects have been challanged to environmental and ecological problems in evaluating economic benefits and costs where the value of non-market goods have not been included in those. Up to data, in evaluating benefits and costs of the projects, farmland base development projects have been confined to direct incremental value of farm products and it's related costs. Therefore the projects'efficiency as a decision making criteria has shown the low level of economic efficiencies. In estimating economic efficiencies including Leontiefs input-output analysis of the projects could not be founded in Korea at present. Accordingly this study is aimed at achieving and identifying the following objectives. (1) To identify the problems related to the financial supports of the Government in implementing the proposed projects. (2) To estimated backward and foreward linkage effects of the proposed project from the view point of national economy as a whole. To achieve the objectives, Hwangrak benefited area with reservoir which is located in Seosan-haemi Disticts, Chungnam Province were selected as a case study. The main results of the study are summarized as follows : a. The present value of investment and O & M cost were amounted to 3,510million won and the present value of the value added in related industries was estimated at 5.913million won for the period of economic life of 70 years. b. The total discounted value of farm products in the concerned industries derived by the project was estimated at 10,495million won and the foreward and backward linkage effects of the project were amounted to 6,760 and 5,126million won respectively. c. The total number of employment opportunities derived from the related industries for the period of project life were 3,136 man/year. d. Farmland base development projects were showed that the backward linkage effects estimated by index of the sensitivity dispersion were larger than the forward linkage effect estimated by index of the power of dispersion. On the other hand, the forward linkage effect of rice production value during project life was larger than the backward linkage effect e. The rate of creation of new job opportunity by means of implementing civil engineering works were shown high in itself rather than any other fields. and the linkage effects of production of the project investment were mainly derived from the metal and non-metal fields. f. According to the industrial linkage effect analysis, farmland base development projects were identified economically feasible from the view point of national economy as a whole even though the economic efficiencies of the project was outstandingly decreased owing to delaying construction period and increasing project costs.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.314-339
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• 1982

Fluctuating climate is still most important environmental constrain, although improved modem agricultural technology has succeeded to increase crop production in the world. To stabilize the food production under fluctuating weather conditions, it is very needed to obain the quantitative information of interactions between crops and climate. The main purpose of this paper is three hold. Using the JIBP-data, the dry matter accumulation of rice crops is studied in relation to weather indexes (\SigmaTa and \SigmaSt). Temperature dependence of the yield index of rice is analyzed as to air temperature and water temperature. \SigmaT$_{10}$ -fluctuations are studied using meteorological data at various stations. The possible shift of \SigmaT$_{10}$ -isopleths due to climate fluctuation is evaluated. The second interest is in the plant climate of rice crops. Using results of canopy photosynthesis, it is pointed that the canopy structure has most important implication in plant climate. Leaf-air, stomatal, and mesophyll resistances of rice crops are described in relation to weather conditions. The change in light condition and aerodynamical property of rice crops with the growth is illustrated. The energy partition is also studied at different growing stages. Third point is to show in more detail effective countermeasures against cold irrigation water and cool summer. Heat balance of warming pond and polyethylene tube as a heat exchanger is studied to make nomo-grams for evaluating the necessary area and necessary length. Effects of windbreak net on rice crops are illustrated by using experimental and simulation results.lts.

• Journal of Chest Surgery
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• v.29 no.1
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• pp.63-66
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• 1996

Postoperative empyema thoracis with bronchopleural fistula (BPF) Is uncommon but serious complication. The management remains troublesome area in the field of the general thoracic surgery During the period of October 1993 to December 1994, four patients with postresectional empyema thoracic with BPF were treated consecutively in Ewha Womans University Mokdong Hosp tal. The treatment procedures include irrigation and debridement of the empyema cavity and muscle flap transposition. Follow-up periods after surgery were 4-12 months. Three patients were thought successful, one patient failed. We think that the cause of failure is muscle necrosis of rectos abdominis muscle flap due to vascular injury and infection of muscle due to residual infected debridement of empyema cavity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.1
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• pp.79-84
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• 1991

The rice plants (Oryza sativa L.) established from the shattered grains by combine harvesting at the previous year showed great variations of yield and yield components from site to site at the abandoned rice crop field. The cultural condition was very similar to direct seeding under no-tillage system but no cultural practices such as application of fertilizer, weed control, irrigation and drainage had been carried out. The highest yield of 188kg/10a was observed at one of the quadrats randomly located on the field, which showed the possibility of exploitation of no-tillage system. The interrelationship between crop growth and coverage of weed species was measured by calculating the correlation coefficients. The investigations of how to establish sufficient number of seedlings per unit area, plant succession on the abandoned crop field, crop mixture with legume crops, and breeding appropriate plant type of rice for the enhancement of competitive ability would be required for the success of no-tillage system.

• KCID journal
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• v.21 no.1
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• pp.55-63
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• 2014

A sedimentation basin for agricultural water quality improvement was researched to analyze the water quality purification characteristics. The sedimentation basin constructed at the inlet of Gamdon reservoir in Muan-gun, Jeollanam-do was selected as the research field of this study. The surface area of the sedimentation basin is $34,000m^2$, volume is $122,000m^3$, and hydraulic retention time is 0.3hr~7.3day. The average influent loading of SS was 156.6kg-SS/d, and the effluent loading was 67.5kg-SS/d with the average removal rate of 56.9%. The average influent loadings of BOD and COD were 33.0kg-BOD/d and 60.3kg-COD/d respectively, and the effluent loadings were 26.4kg-BOD/d and 48.6kg-COD/d with the average removal rate of 20.1% and 19.3% respectively. Therefore, the results of this study show that a sedimentation basin can purify SS and organic matters. The average influent loadings of T-N and T-P were 28.7kg-TN/d and 2.97kg-TP/d respectively, and the effluent loadings were 16.3kg-TN/d and 1.41kg-TP/d with the average removal rate of 43.0% and 52.6% respectively. In conclusion, the overall results of this study show that a sedimentation basin is a feasible alternative to purify organic matters and nutrients.

• Journal of the Korean Professional Engineers Association
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• v.3 no.10
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• pp.7-17
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• 1970

Fourteen reservoirs maintained by the local land improvement associations in the province of Chullabuk-Do and 20 reservoirs maintained by those in the province of Chullanam-Do, were surveyed in connection with a correction between storage capacity and sediment deposit. In addition to this survey, 3347 of small scale reservoirs, that lie scattered around in the above mentioned two provinces were investigated by using existing records pertaining to storage capacity in the office of City and Country, respectively. According to this inrestigation. the following conclusions are derived. 1. A sediment deposition rate is high, being about 10.63m$^3$/ha of drainage area, and resulting in the average decrease of storage capacity by 27.5%. This high rate of deposition could be mainly attributed to the severe denudation of forests due to disorderly cuttings of trees. Especially, in small scale reservoirs, an original average design storage depth of 197mm in irrigation water depth is decreased to about 140mm. 2. An average unit storage depth of 325.6mm as the time of initial construction is decreased to 226mm at present. This phenomena causes a greater shortage of gation water, since it was assumed that original storage quantity itself was already in short.