• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.13 no.2
• /
• pp.71-79
• /
• 1999

In this paper, high concentration.yield trulti-discharge type ozonizer( MDO ) of new discharge type using superposed silent discharge was designed and manufactured MDO can be consisted with 3 kind of superposed silent discharge type ozmizer( SDO ) in accordance with power supply method that suwlying power, which has $180[^{\circ}]$ phase difference, to 3 electrodes and amble gap. At the rroment, discharge characteristics and ozone generation characteristics of each SDO were investigated in accordance with quantity of suwlied gas, the number of SDO, and the shapes of each SDO. In result, ozone generatioo characteristics of 17185[ppm] and 783[g/kWh] were obtained, and when ozone of 17185[ppm] was in contact with dyeing water waste, decolorization characteristics was excellent, so it confinred that MDO could be used as water environment improvement facility.cility.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.43 no.2
• /
• pp.94-104
• /
• 2001

A pilot study was performed at the experimental field of Konkuk University in Seoul, to examine the feasibility of the constructed wetland system for sewage and the effect of treated sewage irrigation on the paddy rice culture and its soil characteristics. The constructed wetland performed well, in that effluent concentrations of pollutants were significantly lower than concentrations of the influent. Median removal efficiencies of BOD$_{5}$ was about 78% and slightly lower during winter. Removal efficiencies form TN and TP were approximately 48 and 21%, respectively, and relatively less effective than that of BOD$_{5}$. Irrigation of treated sewage to paddy rice culture did not affect adversely in both growth and yield of rice. Instead, plots of treated sewage irrigation showed up to 50% more yield in average than the control plot. It implies that treated sewage irrigation might be beneficial to rice culture rather than detrimental as long as it is treated adequately and used properly. Soil was sampled and analyzed before transplanting and after harvesting. pH was slightly increased due to irrigation water, but it may not be concerned as long as the treated sewage is within the normal range. EC was increased in first year but decreased in second year, therefore salts accumulation in the soil could be less concerned. OM and CES was slightly increased, which might be beneficial on growing plants. TN did not show apparent pattern. Available phosphorus was decreased after rice culture, but the quantity of phosphorus(TP-available phosphorus) was rather increased which implies that excessive phosphorus supply may result in phosphorus accumulation in the soil. Overall, the constructed wetland was thought to be an effective sewage treatment alternative, and treated sewage could be reused as a supplemental source of irrigation water for paddy rice culture without causing adverse effect as long as it is treated adequately and used properly. For full-scale application, further investigation should be followed on environmental risk assessment, tolerable water quality, and fraction of supplemental irrigation.ion.

• Fisheries and Aquatic Sciences
• /
• v.12 no.2
• /
• pp.118-129
• /
• 2009

To develop a sustainable management model for oyster farming in Pukman Bay, Korea, we estimated the carrying capacity for oyster farming using food availability data. Optimal culture densities were calculated to be 124-133 individuals per unit flux area ($m^2$) and 310-330 individuals per string. The present annual production is approximately 1,038 tons/year, which is 87% of the estimated maximum yield of 1,193 tons/year. Therefore, considering annual fluctuations and a critical buffer to reduce ecological impacts, the current level is within optimal conditions. During periods of increased water temperature, energy demand was largely met by high primary production. The food supply significantly decreased as the harvest season approached, and 10 out of 21 oyster farms had a deficient food supply for at least 1 month. Therefore, these farms (39% of the farms within the bay) exceeded optimal densities.

• Journal of Environmental Science International
• /
• v.33 no.6
• /
• pp.355-365
• /
• 2024

This study was conducted to investigate the effects of CO₂ supplement on growth and quality in greenhouse lettuce cultivation. When CO₂ was supplied at 1,500 ppm in lettuce cultivation, overall growth parameters such as number of leaves, leaf area, plant length, fresh weight, and dry weight were superior compared to those of the control group. While there was no significant difference in relative growth rate due to CO₂ supplement, an increase in leaf area index was observed with CO₂ usage. Furthermore, although there was no significant difference in the content of water-soluble vitamins such as Vitamin C, B1, B2, B5, and B6 due to CO₂ supplement, the Vitamin B3 content in the CO₂ treatment group was 0.5 mg/kg higher than in the control group. Therefore, the use of CO₂ in lettuce cultivation resulted in increased yield and promoted growth, enabling early harvesting.

• Korean Journal of Environmental Biology
• /
• v.31 no.2
• /
• pp.61-68
• /
• 2013

Microalgae can grow autotrophically with the supply of light, carbon dioxide and inorganic nutrients in water through photosynthesis. Generally, microalgal growth is limited by the concentrations and relative ratio of nitrogen (N) and phosphorus (P) among the nutrients in the aquatic environment. Each microalga has its specific optimum N : P ratio resulting in dominance in a particular water having similar nutrient composition. Algal bloom is an immense growth of certain microalga commonly cyanobacterium and can be sequestrated by reducing the limiting nutrient, generally P in the freshwater. Moreover, dominance of a less toxic blooming strain can be established by manipulating N : P ratio in the water. On the other hand, microalgal biomass of a certain species can be enhanced by increasing limiting nutrient and adjusting the N : P ratio to the target species. The above-mentioned eco-physiological features of microalgae can be more completely interpreted in connection with their genomic informations. Consequently, microalgal growth regulation which can be achieved on the basis of its eco-physiological and further genomic insights would be helpful not only in the control of algal bloom, but also for an increased yield of algal biomass.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.05b
• /
• pp.294-298
• /
• 2005

신뢰도를 이용하여 댐의 물 공급 안전도를 정의하였다. 그리고 보장 공급량 분석에 의한 댐의 물 공급 안전도 평가 절차를 제안하였고, 소양강댐과 충주댐의 물 공급 안전도를 평가하였다. 여러 묶음의 월 유출 시계열을 모의발생시키기 위하여 SAMS-2000을 사용하였고, 보장공급량 결정을 위한 저수지 모의운영에는 HEC-5가 사용되었다. 50년 계획 기간에 대하여 설계 유출자료에 의한 소양강댐 보장 공급량의 물 공급 안전도는 $80.5\%$로 평가되었고, 준공 후 기록 유입량에 의한 보장 공급량의 물 공급 안전도는 $53.7\%$였다. 기록 유입량 자료의 보장 공급량(15.85억 $M^3/yr$)을 계획 공급량으로 하면 연간 0.94억 $m^3 $의 용수를 추가 공급할 수 있다. 충주댐의 설계 유출자료에 의한 보장 공급량 34.22억 $M^3/yr$를 계획 공급량으로 하면 모든 시계열에 대하여 반드시 물 부족이 발생하였다. 이는 설계 당시 유입량의 과대평가에 기인한다. 제안된 절차를 적용하면 보다 객관적으로 댐의 물 공급 안전도를 평가할 수 있다.

• 한국태양에너지학회:학술대회논문집
• /
• 2008.11a
• /
• pp.172-177
• /
• 2008

This study was carry out evaluation of long-term performance for the decentralized desalination system with the solar thermal system and the photovoltaic power system. First operating demonstration system was set up in Cheju in 2006. These system comprises the desalination unit with designed daily fresh water capacity of $2m^3$ and is supplied by a $120m^2$ evacuated tubular solar collector, a $6m^3$ heat storage tank, and a 5kW photovoltaic power generation supply the electricity for hydraulic pumps to move the working fluids. In a clear day more than 400W/$m^2$, the daily fresh water showed to produce more than about 500liter, and from January, 2007 to October, 2008 for 2 years, solar irradiance daily averaged was measured 370W/$m^2$, the daily fresh water yield showed that can be produced about 330liter.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.337-337
• /
• 2017

Accurate and optimal water supply to cereal crop is critical in growing stalks and producing maximum yields. Excessive soil moisture may cause nutrient deficiencies and oxygen deficiency. Excessive soil water during crop growth stages results in decrease of yields. In Korea, the largest agricultural lands are paddy fields. Recently, upland crops are cultivated in paddy field soils to reduce overproduced rice in Korea. In order to success this policy, it is necessary to fully understand crop response to excessive soil moisture condition from paddy field soils. Adzuki bean is one of major legumes which provide protein in daily diet. Adzuki bean has been well know its weakness to excessive soil moisture condition, In order to obtain optimal yields of adzuki bean from paddy field cultivation, it is necessary to understand response of adzuki bean under different soil moisture conditions. This study investigated characteristics of growths, yields and response degree of water stress from adzuki bean. Three cultivars were selected for this study; Chungju, Hongeon, and Arari. All adzuki beans were cultivated in a paddy field which was divided into three sections with different soil moistures. The paddy field was located in Milyang, Gyeongsangnam during 2016. One section of the paddy field had the greatest average soil moisture content as 35.1% during adzuki bean cultivation (very poor). The second greatest soil moisture section had 32.6% (somewhat poor) and the smallest soil moisture section had 28.9% of soil moisture (somewhat well). During cultivation of three cultivar adzuki beans, soil moisture contents and groundwater levels were monitored. All the characteristics of growth and yield components were measured; height, thickness, 100 seed weights etc. Stress index values were calculated by Stress Day Index (SDI). All cultivars had the greatest yields from somewhat well section. Chungju had the greatest yields throughout all three sections compared to other cultivars. Chungju had 81% greater yield than Hongeon which had the smallest yield from somewhat well section. Arari set in middle from all sections. However there was no significant differences yields from very poor and somewhat poor sections. Leaf SPAD values tended to decrease and stable carbon isotope values increased as soil moisture increased. However, Chungju had no difference across different soil moistures in SPAD and stable carbon isotope values, while Hongeon had the greatest differences across sections. These trends followed by SDI values. Chungju had the smallest SDI values compared to other cultivars, which meant that Chungju was the strongest tolerance against excessive soil moisture than other cultivars. All three cultivars showed severe decrease of yields from very poor and somewhat poor sections. Arari and Hongeon showed great decrease from somewhat well section compared to yields from upland soil. These two cultivars may not be proper cultivating in paddy fields. In conclusion, adzuki bean is very sensitive to soil moisture condition and detailed soil managements are required to obtain optimal yields of adzuki bean from paddy field cultivation.

• Korean Journal of Organic Agriculture
• /
• v.7 no.2
• /
• pp.115-124
• /
• 1999

This study was conducted to investigate the effects of fertigation level such as 50%, 75% and 100% N of standard amount of chemical fertilizer,m and fertigation interval such as every irrigation, intervals of 1 and 2 weeks of piggery waste water(PWW) on the growth, yield of red pepper plant and the chemical properties of soil used. In early stage, growth of red pepper plant fertigated with PWW and that of red pepper plant applicated standard chemical fertilezer was the same, while it were increased as increasing application amounts of PWW, and later growth and total yield of red pepper plant were much more at 75% N fertigation of PWW. Inorganic content such as nitrogen, phosphate and potassium and chlorophyll content of red pepper leaves were increased as increasing fergigation amount of PWW. 50% fertigation level showed the lowest rate of fruit setting of red peper plant. For soil chemical properties, pH was slightly decreased, but available $P_2O_5$, and exchangeable K content were increased as increasing fertigation amount of PWW. Because there was not statistically significant difference in the growth, the yield of red pepper and chemical properties of soil used according to various fertigation intervals, and no need to artificially supply PWW, therefore fertigation by simple automatic system with tensiometer was thought to be better.

• The Journal of Engineering Geology
• /
• v.23 no.4
• /
• pp.467-476
• /
• 2013

With increasing interest in environmental issues and the quality of surface water becoming inadequate for water supply, the Korean government has launched a groundwater development policy to satisfy the demand for clean water. To drive this policy effectively, it is essential to guarantee the accuracy of sustainable groundwater yield and groundwater use amount. In this study, groundwater use was monitored over several years at various locations in Korea (32 cities/counties in 5 provinces) to obtain accurate groundwater use data. Statistical analysis of the results was performed as a method for estimating rational groundwater use. For the case of groundwater use for living purposes, we classified the cities/counties into three regional types (urban, rural, and urban-rural complex) and divided the groundwater facilities into five types (domestic use, apartment housing, small-scale water supply, schools, and businesses) according to use. For the case of agricultural use, we defined three regional types based on rainfall intensity (average rainfall, below-average rainfall, and above-average rainfall) and the facilities into six types (rice farming, dry-field farming, floriculture, livestock-cows, livestock-pigs, and livestock-chickens). Finally, we developed groundwater-use estimation equations for each region and use type, using cluster analysis and regression model analysis of the monitoring data. The results will enhance the reliability of national groundwater statistics.