• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.99-106
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• 2008

With globally increasing interests in climate-soil-vegetation system, a new stochastic model of soil water and plant water stress is derived for better understanding of the soil water and plant water stress dynamics and their role in water-controlled ecosystem. The steady-state assumption is used for simplifying the equations. The derived model is simple yet realistic that it can account for the essential features of the system. The model represents the general characteristics of rainfall, soil, and vegetation; i.e. the soil moisture constitutes the decrease form of the steady-state and the plant water stress becomes increasing with the steady state when the rainfall is decreased. With this model, further deep study for the effects of soil water and plant water stress on the system will be accomplished.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.426-435
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• 2012

The variation of stream flow is the one of the most important factors which influence on that of water quality in the unit watershed. The target water quality goal is established and permissible load is allotted in the base of the standard flow condition along with its water quality for the management of Total Maximum Daily Loads (TMDLs). A standard flow selected could cause problems in the load allotment if it was not properly arranged. This study reviewed the acquisition of water quality data, the self-variation and the retainability in water quality on the specific flow conditions. This study also proposed the median and the adjusted average flow condition out of general flow conditions as alternative standard flow conditions. It is considered that the alternatives can make the water quality data easily acquired and the water quality representativeness more enhanced on the standard flow conditions.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.133-139
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• 2010

Global human activities associated with the use of fossil fuels have aggravated climate change, increasing air temperature. Consequently, climate change has the potential to alter surface water temperature with significant impacts on biogeochemical cycling and ecosystems in natural water body. In this study, we examined temporal trends on historical records of surface water temperature, and investigated the air temperature/water temperature relationship and the potential water temperature change from an air temperature scenario developed with regional climate model. Although the temporal trends of water temperature are highly variable site-by-site, surface water temperature was highly dependent on air temperature, and has increased significantly in some sub-watersheds over the last two decades. The results presented here demonstrate that water temperature changes are expected to be slightly higher in river system than reservoir systems and more significant during winter than summer for both river and reservoir system. Projected change of surface water temperature will likely increase $1.06^{\circ}C$ for rivers and $0.95^{\circ}C$ for reservoirs during the period 2008 to 2050. Given the potential climatic changes, every $1^{\circ}C$ increase in water temperature could cause dissolved oxygen levels to fall every 0.206 ppm.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.6
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• pp.437-454
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• 2021

This study investgates Korean water technology through the water market perspective and analyses its competitiveness. Based on the water technology classification, water technology competitiveness is analysed through the technological influence index and market dominance index which are based on the extracted water technology patents from the US, Europe, Korea, and Japan for the last decade. As a result, the Korean water technology patents were lack in influence and competitiveness in global market considering the large volume of patents. There are two most tech-influential industries in Korea; manufacturing industry consisting pipes, sterilization, disinfection, and advanced water purification equipment, and construction industry including seawater desalination and water resource development. Due to the domestic usage of the patents, the Korean water technology patents scored low in global market PFS(Patent Family Size) index compared to their CPP(Cites Per Patent) index. The study is meaningful in a way that the analysis on Korean water technology competitiveness using water technology classification system and patent analysis was conducted based on the perspective of the global water market.

• Corrosion Science and Technology
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• v.21 no.5
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• pp.327-339
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• 2022

The water-jet technique started by Bridgman can cut metal and alloys without harmful gas and fume. However, while this technique is convenient to cut metals and alloys, in the case of coated pipe, water jet induces the degradation of coatings on the pipes, and may facilitate structural failure, leakage, and loss of products. While there are many reports on the effect of water jet on cut metals and the damage of metallic materials, research on the effect of water impingement on the epoxy coatings has been little studied. In this work, we therefore control the velocity of water jet, distance between nozzle and specimen, and water temperature, and discuss the effect of water impingement on the epoxy coatings. Increasing water velocity and water temperature and reducing nozzle distance increased the degradation rates of three epoxy coatings were increased. Among three test parameters - water velocity, nozzle distance and water temperature, water temperature was relatively effective to increase the degradation rate of epoxy coatings.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.932-937
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• 2011

Main objectives of this paper were; firstly, to explain impacts of suspended solid in the water body on the relationship between water quantity and water quality; secondly, study on the inter-relationship between organic materials, nutrients, pathogens, and suspended solids considering eco-friendly water resources. Relationship between water quality and water quantity is not easy to understand as it includes physicochemical-biological reactions and diffuse pollutions. Especially, suspended solid makes water resource management difficult. Eroded soil in the upper land transported to the downstream by water flows carrying biological and physicochemical information and sedimented in the downstream. As sediment scoured under high flow condition and environmental change, suspended solid and sediment should be emphasized for understanding the inter-relationship between water quality and water quantity. Knowledge gaps between known monitored data and management of suspended solid were identified as well for future study.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.3
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• pp.26-33
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• 1994

To slove the problems by the scum, which causes operational and water quality problems in water treatment plants, several researches were conducted based on the site investigations on twelve large water treatment plants, biological and chemical analysis of scum, analyzing raw water quality data. Two types of scum, which are from scum and floe scum, can be classified based on the analysis and site investigations. The major parameter generating floe scum was indicated as fine bubbles dissolved in the water. The fine bubbles dissolved in the water can be generated by over-saturated air in the water, adding aluminum surface as the coagulant, conducting the break point pre-chlorination and so on. The water spray method, which is one of the physical treatment methods for removing scum, was selected for conducting experiments on the removal efficiency in the flocculation basin of the real water treatment plant. The water spray method was successfully applied for removing scum with the advantages of using spiral nozzles in case of using the raw water rather than the cleaned water.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.5
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• pp.707-717
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• 2011

Replacement of old water distribution pipes for protecting water quality induced by pipe corrosion requires enormous budget. Even after the replacement, however, corrosion can occur again at any times and, therefore, inhibitive measure of the corrosion will be not only economical but needed to diminish the consumers' distrust on tap water quality. In 2008, National Environmental Research Institute did a survey on 8 major drinking water source and proposed to establish the Langelier Saturation Index(LI) as a corrosion index in Drinking Water Quality Criteria. Among the water industries of Korea, K-Water is the only one that set up the level of pH over 7.0 and LI above -1.5 on yearly average basis. However, no systematic regulation including LI to inhibit the corrosive tendency has been established yet. In this paper, LI values out of 31 drinking water treatment plants were analyzed and two-stage control of LI value as a measure of corrosive tendency of water is proposed. Primarily, water treatment facilities may operate the system at a target LI value below -1.5. Following the investigation on the effect caused by adjusting the LI value on water quality and corrosiveness, it will be desirable to improve LI value below -1.0 in the long run. In addition to the LI, supplemental use of Larson's modified ratio (LMR) which incorporates hydraulic detention time will be necessary. Several methods to prove the inhibitive effect of improving the LI value on water quality have been also suggested.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.386-396
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• 2006

• Current Research on Agriculture and Life Sciences
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• v.31 no.2
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• pp.139-147
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• 2013

This study analyzed agricultural water distribution systems for the utilization of water demand-oriented water supply systems. Three major TM/TC(telemeter/telecontrol) districts of agricultural water management were selected for analyzing the characteristics of the water distribution systems. In addition, the characteristics of the water supply systems for general water supply zones based on irrigation facilities were also investigated, along with the case of special water management during the drought season. As a result, high annual and monthly variations were observed for the water supply facilities, including the reservoirs and pumping stations. In particular, these variations were more obvious during the drought season, depending on the type of facility. The operations of the pumping stations and weirs were more sensitive to the stream levels than the reservoirs, and the smaller reservoirs were influenced more than the larger reservoirs. Therefore, a water-demand-oriented water supply system should consider the existing general practices of water management in the agricultural sector, and focus on achieving a laborsaving system rather than water conservation in the case of reservoirs. Equal water distribution from the start to the end point of irrigation channels could be an effective solution for managing pumping stations.