• Proceedings of the Korea Water Resources Association Conference
• /
• 2010.05a
• /
• pp.23-27
• /
• 2010

인공수로 내 효율적인 물 순환 시스템 운영을 위해서는 지속적인 유량공급을 통해 순환흐름을 유도하는 것이 매우 중요하다. 따라서 수로 내 적절한 유입부 위치를 결정하고 계획 유입유량에 따른 수질개선효과 및 물 순환주기를 분석하는 연구가 대두되고 있어, 모형을 통한 이론적인 예측 및 모형실험을 통한 검증이 필요한 실정이다. 본 연구에서는 농도-pH 지표곡선을 이용하여 시간에 따른 수로 내 농도변화로 물 순환주기를 분석하였다. 수로 내 설치된 유입부에 평면상 위치변화를 주어 순환흐름에 적합한 유입부 위치를 제시할 수 있었으며, 농도변화가 없어지는 시점을 통해 최소 물 순환주기를 산정할 수 있었다.

• Journal of Aquaculture
• /
• v.8 no.2
• /
• pp.117-131
• /
• 1995

In order to improve the present running seawater system for seedling production of marine fishes, rearing experiments with the juveniles of black seabream (Acanthopagrus schlegeli) and oblong rockfish (Sebastes oblongus) were conducted. The recirculating seawater system (F) equipped with the rotating biological contactors and the running seawater system (R) were used. Environmental factors, growth, survival rate and rearing density of the fish were compared between two systems during the experimental period. In the rearing experiment of black seabream, water temperature in F was fluctuated with surrounding air temperature and was higher than that in R. Specific gravity of the rearing seawater in F was relatively stable in the range of 1.0252 to 1.0266, while that in R was greatly fluctuated. pH in F turned out to be 7.51, but pH in R was similar to that in the natural seawater. Dissolved nitrite and nitrate in F were higher than those in R. While no significant differences in the growth of black seabream juveniles were recognized between two systems, survival rates of fishes in F were higher than those of fishes in R. In the rearing experiment of oblong rockfish, water temperature in F was higher than that in R. Specific gravity in F was slightly higher than that in R which showed relatively less fluctuation in the range of 1.0253 to 1.0270. pH in F turned out to be 7.96, but pH in R was similar to that in the natural seawater. Dissolved nitrite and nitrate in F were higher than those in R, but ammonia was lower in F. The juveniles of oblong rockfish reared in F grew significantly faster in their total length and body weight than those in R (P<0.05). However, survival rates of fishes between two systems showed no significant differences.

• Journal of Bio-Environment Control
• /
• v.12 no.2
• /
• pp.89-94
• /
• 2003

This study was conducted to identify the effect of recycling method of drained solution on the concentration of drained solution, and growth and yield of tomato in the recycling system. The recycling methods of drained solution were composed of control, MEC (measurement of EC) and ANS (analysis of nutrient solution). The plant height in the early growth stage was not different among the treatments, but plant fresh weight and dry weight were higher in the MEC or the ANS than in the control. The growth including fruit number, fruit weight, and yield of tomato in the ANS as compared with the control was favorable. The EC of drained solution tended to decrease in the early growth stage, but that of drained solution increased in the late growth stage. It was low in the MEC and the ANS as compared with the control. The pH of drained solution was maintained by 6.2 to 6.5 throughout the growth period in the MEC and the ANS, but the pH of the control increased up to 7.2 at the late growth stage. The N and K concentrations of drained solution tended to decrease in the early growth stage, while those of P, Ca and Mg increased. In the late growth stage, concentrations of N, P, Ca and Mg tended to decrease, but that of K in the ANS was very low. Concentrations of N, P, K, Ca and Mg were lower in the MEC and the ANS than in the control.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.3 no.4
• /
• pp.269-278
• /
• 2005

In order to produce only a pH-controlled solution without discharging any unwanted solution, this work has developed a continuous electrolytic system with a pH-adjustment reservoir being placed before an ion exchange membrane-equipped electrolyzer, where as a target solution was fed into the pH-adjustment reservoir, some portion of the solution in the pH-adjustment reservoir was circulated through the cathodic or anodic chamber of the electrolyzer depending on the type of the ion exchange membrane used, and some other portion of the solution in the pH-adjustment reservoir was discharged from the electrolytic system through the other counter chamber with its pH being controlled. The internal circulation of the pH-adjustment reservoir solution through the anodic chamber in the case of using a cation exchange membrane and that through the cathodic chamber in the case of using an anion exchange membrane could make the solution discharged from the other counter chamber effectively acidic and basic, respectively. The phenomena of the pH being controlled in the system could be explained by the electro-migration of the ion species in the solution through the ion exchange membrane under a cell potential difference between anode and cathode and its consequently-occurring non-charge equilibriums and electrolytic water- split reactions in the anodic and cathodic chambers.

• Journal of Biosystems Engineering
• /
• v.23 no.2
• /
• pp.167-178
• /
• 1998

An Aero-NFT nutriculture system using microcomputer for cultivation of greenhouse melon was developed and the performance of the system was evaluated through experiments. The system could control temperature, EC and pH of the nutrient solution within the error ranges of $\pm$ 0.2$^{\circ}C$, $\pm$ 0.2 mS/cm, $\pm$ 0.1 pH, respectively. The results of cultivation experiment showed that temperature, EC and pH of the nutrient solution were generally controlled within the setting ranges during cultivation period. The growth results were good until pinching, but the fruit quality of melons was not high except sweetness and shape. To optimize performance of the system, more techlical information for nutriculture of greenhouse melon was needed.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.3
• /
• pp.477-484
• /
• 2017

In the conventional recirculation fish farms, there is a lot of difficulties due to lack of professional manpower and high reliance on imported measurement equipment. In this paper, we implement an automatic water quality measurement system which can measure the pollution degree in a water tank of fish farms using an optical sensor(pH, DO) with the IoT technology. The problem with existing systems is that the fish tank should be checked by means of human, or put the measuring equipment into the water tank of fish farms and measurement directly. But, it has a bad influence on the growth of fish. In this paper, we propose a method of indirect measurement without immersing the measurement equipment in a water tank of fish farm and develop a sustainable measurement system in an environment containing salt and lots of pollutants without affecting the growth of fish within the water tank of fish farms.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.175-175
• /
• 2020

본 연구는 경남지역의 주요 양액재배 작물인 토마토, 딸기, 파프리카를 대상으로 순환식/비순환식 양액재배 시설을 대상으로 모니터링을 실시하고 그 결과를 분석하여 양액재배로 인한 배출부하량의 특성을 분석하고 관리방안을 마련하는 데 그 목적이 있다. 이를 위해 대표 재배작물에 대한 순환식/비순환식 양액재배 농가를 선정하고, 작물의 생육기간을 고려하여 유입수와 유출수의 유량과 수질모니터링을 실시하여 생육시기별로 양액재배 농가로부터 배출되는 작물별 배출부하량을 분석하였다. 순환식/비순환식 양액재배농가를 대상으로 매월 1회 pH, EC, DO, BOD, SS, T-N, T-P 등의 수질항목을 조사하였으며, 수질은 공인인증기관을 통해 분석하였다. 또한, 폐양액의 인근 하천 유입에 따른 수질영향을 분석하기 위하여 인근 하천의 양액재배 단지 상류지역, 재배단지 내 배수로, 재배단지 하류를 선정하여 수질의 변화 양상을 분석하였다. 본 연구를 통해 폐양액 배출을 최소화하는 순환식 양액재배 시스템의 효과를 분석하고, 양액재배 지역의 폐양액과 주변 하천수의 정량적 분석을 통해 양액재배 밀집지역의 오염화 정도와 환경부하 저감을 위한 기초데이터로 활용될 수 있을 것으로 기대한다.

• Journal of Bio-Environment Control
• /
• v.11 no.4
• /
• pp.168-174
• /
• 2002

A new circulating hydroponic system was invented for oriental melons grown in the greenhouse. For developing nutrient solution management techniques, we examined the changes of nutrient contents of circulating solution in three different types of new hydroponic systems. The yield and fruit quality of oriental melons in Hydroponics were better than those in soil culture. The substrate culture was appropriate fer hydroponics of oriental melons, and NFT was turned to be the opposite due to the physiological disorder during hot seasons. Yamazaki's melon solution with EC 2.0dS.m$^{[-10]}$ was the most appropriate for oriental melons. The new circulating hydroponic system seemed to be appropriate for oriental melons because of the stable EC, pH and the macro- and micro-element contents. NO$_3$-N, Ca and Mg contents in the circulating solution kept a good balance in all types of hydroponics. However, p content, compared to other types, decreased by the degree of 1 me.L$^{[-10]}$ in perlite medium. K content showed irregular status in perlite but showed the stable status in cocopeat. Generally, microelements, except Mo, showed stable absorption in the substrate culture. However, in NET, most of the elements showed irregular absorption except B and Mn. Microelement absorption, especially Cu, Zn and Mo, decreased during hot seasons.

• Journal of Bio-Environment Control
• /
• v.6 no.1
• /
• pp.1-14
• /
• 1997

This experiment was conducted to find out the compositions of nutrient solution for closed system in substrate culture of cucumber. Cucumber(Cucumis sativus L. cv. Eunsung baekdadagi) plants were grown in the substrates supplied with the nutrient solutions whose strengths were 1/2, 1, and 3/2 of the original concentration developed by National Horticultural Research Station in Japan. By increasing the nutrient concentrations, plant height decreased but leaf length, leaf width, and leaf number showed little differences. A number of marketable fruit and marketable yield were the highest in the concentration of 1 strength. The nutrient compositions of solution developed for closed system in cucumber substrate culture were N 11.4, P 3.3, K 6.0, Ca 4.5, and Mg 3.5 me.$\ell$$^{-1}$ during the vegetative growth period and N 10.4, P 3.3, K 5.0, Ca 4.5, and Mg 3,5 me.$\ell$$^{-1}$ during the reproductive growth period. To examine the suitability of nutrient solution developed in the above experiment, cucumber plants were grown in the substrates supplied with different solutions and concentrations - Yamasaki's nutrient solution(Yamasaki) of 1 S, nutrient solution of Research Station for Greenhouse Vegetable and Floriculture on the Netherlands(PTG) of 1 S, nutrient solution developed in the above experiment(SCU) of 1/2, 1, and 3/2 S. EC and pH in root zone changed little in the all treatments during growing period. As cucumber plants grew, the concentrations of N, P, and K in root zone decreased but Ca concentration increased. Net $CO_2$ assimilation rate of cucumber leaves was high in SCU of 1 and 3/2 S, and Yamasaki of 1 S. Growth of cucumber plants was the lowest in SCU of 1/2 S.

• Ecology and Resilient Infrastructure
• /
• v.6 no.2
• /
• pp.109-119
• /
• 2019

Eutrophication has occurred due to the inflow of various water pollutants in many Korean reservoirs with low depth, and algal blooms of surface layer and low oxygenation of deep layer have repeated every year. There are several existing technologies to alleviate the stratification of reservoirs, but it is difficult to apply them in field sites due to the necessity of electric power and low economic efficiency. In this study, a non-powered water circulation system using natural energy of wind and water flow has been developed, and two test-beds constructed in the reservoirs with different conditions and examined its field applicability. Through computational fluid dynamics (CFD) simulation, it has been shown that the water circulation system could induce the downward flow to mitigate the stratification between surface and deep layers, and its influence radius could reach about 30 m. As a result of long-term monitoring of the test-beds, various water quality improvement effects have been observed such as moderation of DO fluctuation by water circulation, reduction of DO supersaturation and prevention of excessive pH rising. In order to improve the applicability of the water circulation system, it is considered necessary to review countermeasures against flood and depth conditions of each reservoir.