• Journal of the Korea Organic Resources Recycling Association
• /
• v.29 no.1
• /
• pp.19-27
• /
• 2021

Hydroponic farming is a method to grow a plant without soil. Plants can be grown on water or hydroponic growing media, and they are fed with mineral nutrient solutions, which are fertilizers dissolved into water. Hydroponic farming has the advantage of increasing plant productivity over conventional greenhouse farming. Previous studies of hydroponic nutrient wastewater from acyclic hydroponic farms pointed out that hydroponic nutrient wastewater contained residual nutrients, and they were drained to a nearby river bank which causes several environmental issues. Also, previous studies suggest that excessive use of the nutrient solution and disposal of used hydroponic growing media and crop wastes in hydroponic farms are major problems to hydroponic farming. This study was conducted to determine the impact of hydroponic nutrient wastewater, used hydroponic growing media, and crop wastes from acyclic hydroponic farms on the surrounding environment by analyzing water quality and soil analysis of the above three factors. Three soil cultivation farms and several hydroponic farms in the Gangwon C region were selected for this study. Samples of water and soils were collected from both inside and outside of each farm. Also, a sample of soil and leachate from crop waste piles stacked near the farm was collected for analysis. Hydroponic nutrient wastewater from acyclic hydroponic farm contained an average of 402 mg/L of total nitrogen (TN) concentration, and 77.4 mg/L of total phosphate (TP) concentration. The result of TP in hydroponic nutrient wastewater exceeds the living environmental standard of the river in enforcement decree of the framework act on environmental policy by 993.7 times. Also, it exceeds the standard of industrial wastewater discharge standards under the water environment conservation act by 6~19 times in TN, and 2~27 times in TP. Leachate from crop waste piles contained 11,828 times higher COD and 395~2662 times higher TP than the standard set by the living environmental standard of the river in enforcement decree of the framework act on environmental policy and exceeds 778 times higher TN and 5 times higher TP than the standard of industrial wastewater discharge standards under the water environment conservation act. For more precise studies of the impact of hydroponic nutrient wastewater, used hydroponic growing media, and crop wastes from acyclic hydroponic farms on the surrounding environment, additional information regarding a number of hydroponic farms, arable area(ha), hydroponic farming area, seasonal, weather, climate factor around the river, and the property of the area and farm is needed. Analysis of these factors and additional water and soil samples are needed for future studies.

• Journal of Korean Society of Environmental Engineers
• /
• v.36 no.8
• /
• pp.570-578
• /
• 2014

A three-dimensional ocean circulation model was applied to a shallow estuary, Mobile Bay, to study local wind setup and setdown. Tides started from the northern Gulf of Mexico propagates up to the Mobile River system which is located in the north of the Mobile Bay. However, the tides started in the south of Mobile Bay were distorted when travelling upstream while affected by river discharge and local winds. The water surface elevation was less/over predicted responding north/south winds, respectively, when winds only at the Dauphin Island station (DPI) were used. However, the model predicted water surface elevation better when using two local winds from DPI and Mobile Downtown Airport (MDA). Wind speeds were greatly reduced (~ 88%) in about 43 km distance between DPI and MDA, and the canopy effects may be the reason for this. For this reason, the local winds are greatly responsible for local surface elevation setup and setdown especially at the shallow estuary like Mobile Bay.

• Journal of Korean Academy of Nursing Administration
• /
• v.1 no.2
• /
• pp.338-348
• /
• 1995

We need to continuously evaluate for nursing quality and the outcome to reflect nursing, to repair and improve of nursing. The first problem for nursing quality improvement is development of evaluation tool for the quality of nursing care. We need a system for quality assurance evaluation that is, development and framework of evaluation tool for nursing care quality. The purpose of this study was attempted to develop an evaluation tool for the quality of nursing care in musculoskeletal disorder patients. The approach method of nursing quality for the development of the tool in this study was process evaluation framework. The study were devided dvelopment process and reliability, validity verification process. The subjects of development process of this tool are three nursing export groups, and the subject of reliability, validity verification process are 20 samples of two university hospital in seoul, who were within discharge 3 months after admission treatment in musculo-skeletal disorder. Data for this study was collected from March 10 to April 13, 1995. The development process of the tool were as follows : 1. Make preliminary list of the tool by focal group were constituted 12 clinical nurses. 2. Modify and add preliminary list by 4 nursing expert panel. 3. Calculate content validity of the tool by 25 nursing expert panel of judge. 4. Verify reliability and validity of the tool. 5. Finalize an evaluation tool for the quality of the nursing care in musculo-skeletal disorder. The results of this study were as follows : 1) Development an evaluation tool for the quality of nursing care in musculo-skeletal disorder. (1) The evalution tool of this study was developed 5 standards, 33 criterias and 133 indicators. (2) 5 standards were divided according to Nursing Process. from standard 1 to standard 5, involved criterias were each 6(18%), 3(9%), 3(9%), 15(46%), 6(18%). 2) Verify reliability and validity of the tool. (1) Score of adequate degree for content validity of 33 criterias and 133 indicators were every average 2.82. (2) Inter-rater reliabilities(consentaneity score) of the tool by pearson correlation coefficient between three raters were : r=.7506, r=.8934, r=.6695. and Inter-rater reliabilities by single-facet crossed design were : r=.7464. (3) The alpha coefficient relating to internal consistency was .8524 over all 30 items of 33 criterias of developed tool. (4) Score of the quality of nursing care following to generaal characteristics of this study subjects were stastically significant differences according to educational level (F=2.93, p=.029)and diagnosing classification (F=2.50, p=.042). Through this study, I'm sure that the developed tool for the quality of patient care in musculo-skeletal disorder will show the way of more improvement of the quality of nursing care and effective nursing interventions.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.12 no.4
• /
• pp.227-234
• /
• 2009

Using a finite volume ocean circulation model based on an unstructured grid (FVCOM), we studied the structure of a fresh water bulge that influences on the Region Of Freshwater Influence. Fresh water discharged a river forms a coastal boundary current to the righthand side and a cyclonically circulation freshwater bulge that grows with time. In the middle of the bulge, vertical motions bring fresh water to the bottom. When tidal motions are included, the bulge disappears while the boundary currents becomes wider. Through a simple comparison of areas occupied low salinity water we quantified vertical and horizontal mixing due to the tide and showed that the tidal motion enhances the vertical mixing. During the first few tidal cycles right after the onset of the river discharge, due to tidal excursion the horizontal mixing becomes stronger. The vertical mixing by the tide mixes the fresh water After a certain time the water around the river mouth is well mixed and the horizontal excursion of the fresh water near the river mouth does not have much effect on the horizontal mixing. When there is no tidal motion horizontal mixing is mainly by the inertial instability at the surface and the horizontal mixing becomes stronger over time.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.2
• /
• pp.47-55
• /
• 2016

In this study, WUA (Weighted Usable Area) based on the Instream Flow Incremental Methodology (IFIM) was calculated to determine ecological flow at JeonJu-Cheon by using River2D model. To calibrate River2D, simulation results for low flow conditions of River2D were compared with calibrated HEC-RAS simulation results and the optimum parameters were determined. The results were RMSE (0.18), NSE (0.71) and coefficient of determination (0.78) for velocity and RMSE (0.02), NSE (0.71), coefficient of determination (0.73) for water depth. The result shows that the model successfully simulates the water flows. A selected target fish species to build the habitat suitability index were composed of Zaccoplatypus and Coreoleuciscus splendidus. These species showed the highest occurrences over the past decade in f ish monitoring. Also, The WUA-Discharge curve was calculated with the suitability index in a medium flow conditions. From the result, WUA is changed according to flowrate. In the flowrate-WUA/A graph, ecological flow can be determined at $1.8{\sim}2.0m^3/s$ for Zaccoplatypus $2.0m^3/s$ and Coreoleuciscus splendidus $1.8m^3/s$ at JeonJu-Cheon upstream. When compared with flow-duration analysis, it is demonstrative that simulation results fitted ecological flow considering quantity of available habitat for each fish species.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.1
• /
• pp.48-55
• /
• 2014

These Xenon flashlamp power supply for Ultra Violet has converter with high voltage conversion ratio. General model is composed of transformer with high voltage conversion ratio and voltage doubler rectifier circuit. Purpose of power supply leads dielectric breakdown of Xenon flashlamp and passes current rapidly. When passing current, it has to limit current to avoid over-heat, damage of electrode and acceleration of gas oxidation which are cause of performance degradation of lamps. Generally, inductors and resistors, which are called as "Ballast," are used to limit currents. Generally, Transformer has high turn ratio to make high voltages. But we can get high voltages using the transformer with low turn ratio which is driven with self resonance. Also, an advantage of self resonance is to make a circuit simply through impedance of transformer in resonance frequency which filters output voltage. As using an unique impedance of transformer, the circuit does not need other impedance elements like the ballast. So the power supply assures high efficiency of the arc discharge.

• Journal of Korea Water Resources Association
• /
• v.45 no.2
• /
• pp.151-163
• /
• 2012

The distribution of gravel-bed materials in mountainous river is formed by the process of deposition and transportation of sediment responding to stream power of the latest flood that is over the certain scale. The particle size of bed material was surveyed in the longitudinal points of river and detail points of a specific meandering section and used to estimate the critical velocity and stream power. Yang's critical unit stream power and Bagnold's critical stream power for gravel-bed materials increased with the distance from downstream to upstream. Dimensionless shear stress based on the designed flood discharge in Shields diagram was evaluated that the gravel-bed materials in most survey points may be transported as form of bedload. The mean diameter in the meandering section was the biggest size in first water impingement point of inflow water from upstream and the second big size in second water impingement point by reflection flow. The mean diameters were relatively the small sizes in points right after water impingement. The range of mean critical velocity was 0.77~2.60 m/s and critical unit stream power was big greatly in first water impingement point. The distribution of critical stream power, range of 7~171 $W/m^2$, was shown that variation in longitudinal section was more obvious than that of cross section and estimated that critical stream power may be affected greatly in first and second water impingement point.

• Clean Technology
• /
• v.26 no.3
• /
• pp.228-236
• /
• 2020

Korea has an economy based on manufacturing industrial fields, which produce high amounts of hazardous wastes, in spite of few landfill candidates, and a significant concern for fine airborne particulates; therefore, traditional waste management is difficult to apply in this country. Moreover, waste collection and accumulation have recently been intensified by the waste import prohibitions or regulations in developing nations, the universalization of delivery services in Korea, and the global COVID-19 crisis. This study thus presents a domestic waste management strategy that aims to address the recent issues on waste. The contents of the strategy as the main results of the study include the (1) improvement of the compatibility of the classification codes between the domestic hazardous waste and the international ones such as those of the Basel Convention; (2) consideration of the mixed hazard indices to represent toxicity from low-content components such as rare earth metals often contained in electrical and electronic equipment waste; (3) management application based on risks throughout the life cycles of waste; (4) establishment of detailed material flow information of waste by integrating the Albaro system, Pollutant Release and Transfer Register (PRTR) system, and online trade databases; (5) real-time monitoring and prediction of the waste movement or discharge using positional sensors and geographic information systems, among others; and (6) selection and implementation of optimal treatment or recycling practices through Life Cycle Assessment (LCA) and clean technologies.

• Agribusiness and Information Management
• /
• v.9 no.1
• /
• pp.7-17
• /
• 2017

Agricultural water management has gained enormous attention in the developing world to alleviate poverty, reduce hunger and conserve ecosystems in small-scale production systems of resource-poor farmers. The story of food security in the $21^{st}$ century in India is likely t o be closely linked to the story of water security. Today, the water resource is under severe threat. The past experiences in India in general and in Andhra Pradesh in particular, indicated inappropriate management of irrigation has led to severe problems like excessive water depletion, reduction in water quality, water logging, salinization, marked reduction in the annual discharge of some of the rivers, lowering of ground water tables due to pumping at unsustainable rates, intrusion of salt water in some coastal areas etc. Considering the importance of irrigation water resource efficiency, Krishna Western Delta (KWD) of Andhra Pradesh was purposively selected for this in depth study, as the farming community in this area are severely affected due to severe soil salinity and water logging problems and hence, adoption of different water saving crop production technologies deserve special mention. It is quite disappointing that, canals, tube wells and filter points and other wells could not contribute much to the irrigated area in KWD. Due to less contribution from these sources, the net area irrigated also showed declining growth at a rate of -6.15 per cent. Regarding paddy production, both SRI and semi-dry cultivation technologies involves less irrigation cost (Rs. 2475.21/ha and Rs. 3248.15/ha respectively) when compared to transplanted technology (Rs. 4321.58/ha). The share of irrigation cost in Total Operational Cost (TOC) was highest for transplanted technology of paddy (11.06%) followed by semi-dry technology (10.85%) and SRI technology (6.21%). The increased yield and declined cost of cultivation of paddy in SRI and semi-dry production technologies respectively were mainly responsible for the low cost of production of paddy in SRI (Rs. 495.22/qtl) and semi-dry (Rs. 532.81/qtl) technologies over transplanted technology (Rs. 574.93/qtl). This clearly indicates that, by less water usage, paddy returns can be boosted by adopting SRI and semi-dry production technologies. Both the system-level and field-level interventions should be addressed to solve the issues/problems of water management. The enabling environment, institutional roles and functions and management instruments are posing favourable picture for executing the water management interventions in the State of Andhra Pradesh in general and in KWD in particular. This facilitates the farming community to harvest good crop per unit of water resource used in the production programme. To achieve better results, the Farmers' Organizations, Water Users Associations, Department of Irrigation etc., will have to aim at improving productivity per unit of water drop used and this must be supported through system-wide enhancement of water delivery systems and decision support tools to assist farmers in optimizing the allocation of limited water among crops, selection of crops based on farming situations, and adoption of appropriate alternative crops in drought years.

• Journal of Korea Water Resources Association
• /
• v.50 no.4
• /
• pp.241-252
• /
• 2017

This study aims to evaluate applicability of both online and offline parameter calibration techniques on rainfall-runoff modeling using a conceptual lumped hydrologic model. To achieve the goal, the storage function model was selected and then two different automatic calibration techniques: SCE-UA (offline method) and particle filter (online method) were applied to calibrate the optimal parameter sets for 9 rainfall events in the Cheoncheon catchment, upper area of the Yongdam multi-purpose dam. In order to assess reproducibility of hydrographs from the parameter sets of both techniques, the observed discharge of each event was divided into low flow (below average flow) and high flow (over average flow). The results show that the particle filter method, updating the parameters in real-time, provides more stable reproducibility than the SCE-UA method regardless of low and high flow. The optimal parameters estimated by SCE-UA are very sensitive to the selected objective functions used in this study: RMSE and HMLE. In particular, the parameter sets from RMSE and HMLE demonstrate superior goodness-of-fit values for high flow and low flow periods, respectively.