• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.10
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• pp.989-994
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• 2016

This study was conducted the management of a water level through the water sensor, the waterline and the drain applied to the rice paddy. The gateway transfers the information to oneM2M(: Machine to Machine) platform of IoT(: Internet of Thing) standards to the height of the water level sensor information through the LoRa connection. Depending on the water level requested by the IoT platform, the gateway is to On or Off waterline or drain motor switch and send the information of the water level sensor. IoT platform performs the intelligent application function according to the condition of the water level.

• Journal of Korean Society on Water Environment
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• v.30 no.6
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• pp.612-621
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• 2014

Physicochemical factors and the phytoplankton communities in the downstream area of Namhan-River were investigated from June 2012 to November 2013. We also assessed water quality using biological water quality indices. Total nitrogen was 2.4 mg/L, total phosphorus was 0.04 mg/L, and biological oxygen demand was 1.1 mg/L. This resulted in a level 2 (Ib, good) water quality rating. A total of 259 phytoplankton taxa were classified, consisting of 26 families, two subfamilies, 64 genera, 222 species, 32 varieties, and five formas. Bacillariophyceae dominated during a1l seasons and at all sites. The dominant species were Aulacoseira granulata, Cyclotella meneghiniana, C. stelligera, Melosira varians, Cocconeis placentula var. lineata, Nitzschia palea, N. amphibia, Cymbella minuta, and Achnanthes convergens. The diatom assemblage index for organic pollution values was level A-D, and TDI was level B-D. P-IBI at most sites was at the M (moderate) level, but TSI was at the E (eutrophic) level. Most indices dropped from upstream to downstream.

• The Korean Journal of Community Living Science
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• v.26 no.2
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• pp.351-360
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• 2015

The study examines the effects of the Cnidium officinale Makino water extract on hyperlipidemia. For this, three levels (low, moderate, and high) of the Cnidium officinale Makino water extract were supplemented to six-week-old male sprague Dawley rats for five weeks. According to the results, serum total lipid, triglyceride, total cholesterol, and LDL cholesterol levels showed significant decreases (p<0.05) in the group with the Cnidium officinale Makino water extract. The serum total lipid level decreased by 8~22%; the triglyceride level, by 13~25%; the total cholesterol level, by 6~23%; and the LDL cholesterol level, by 14~25%. Total cholesterol and triglyceride levels in the liver were significantly lower in the group with the Cnidium officinale Makino water extract than in the control group (p<0.05), and fecal total cholesterol and triglyceride levels were significantly higher in the group with the Cnidium officinalle Makino water extract. These results suggest that the Cnidium officinale Makino water extract in the hypercholesterol diet may reduce hyperlipidemia, a major cause of cardiovascular disease, by reducing serum cholesterol and triglyceride level in the liver through the facilitation of their excretion by feces.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.899-908
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• 2023

Droughts can alter the dynamics of aquatic ecosystems, including fish communities. This study compared the variations in fish communities in Juam reservoir before and after drought events. Fish sampling was conducted five times from April 2021 to April 2023 using three different sampling methods (kick net, cast net, and gill net). The water level in the reservoir reached its peak (103.73 EL.m, 62.2% capacity) in September 2021, before the drought, and dropped to its lowest point (88.84 EL.m, 17.6% capacity) in April 2023. The dissolved oxygen content in the reservoir decreased from 27 to 6.3 mg/L between the period with the lowest water level (April 2023) and the period with the highest water level (September 2021). In September 2021, 466 fish were collected, but after one year of drought, the number of individuals decreased to 105. Further, the number of fish collected and water levels were positively correlated. Dominant species exhibited a population decline of over 60% with decreasing water levels. These findings highlight the importance of fishery resource management during drought periods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.164-174
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• 2007

Phenomena of hydraulic transient such as water hammer should be analyzed to design the pipeline systems effectively in dam. Surge tanks generally are used to reduce change in pressure caused by hydraulic transient from load changes on the turbines. In this study, the appropriate scale of surge tank with chamber is investigated for dam safety management. The variation of water level in the surge tank are computed using governing equation. Using the Thoma-Jaeger's stability condition, static and dynamic stability are investigate for the cases of flood water level, normal high water level, rated water level and low water level. Finally appropriate diameters of shaft and chamber are determined in the surge tank with chamber.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.173-173
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• 2015

The flood water level in tidal river is determined by the joint effects of flood discharge and tidal water levels at downstream boundary. Due to the variable tidal boundary conditions, the evaluated design water levels associated with a certain flood event can be significantly different. To avoid determining of design water levels just by a certain tidal boundary condition and remove the influence of variability in boundary condition from the evaluation of design water levels, a probabilistic approach is considered in this study. This study focuses on the development of a method to evaluate the realistic design water levels in tidal river with taking into account the combined effects of river discharge and tidal level. The flood water levels are described by the joint probability of two driving forces, river discharge and tidal water levels. The developed method is applied to determine design water levels for the tidal reach of the Han River. An unsteady flow model is used to simulate the flow in the reach. To determine design water levels associated with a certain flood event, first, possible boundary conditions are obtained by sampling starting times of tidal level time series; then for each tidal boundary condition, corresponding peak water levels along the channel are computed; and finally, design water levels are determined by computing the expectations of the peak water levels. Two types of tides which are composed by different constituents are assumed (one is composed by $M_2$, and the other one is composed by $M_2$ and $M_2$) at downstream boundary, and two flood events with different maximum flood discharges are considered in this study. It is found that (a) the computed design water levels with two assumed tides have no significant difference for a certain flood event, though variability of peak water levels due to the tidal effect is considerably different; (b) tidal effect can reach to the Jamsil submerged weir and the effect is obvious in the downstream reach of the Singok submerged weir; (c) in the tidally affected reach, the variability of peak water levels due to the tidal effect is greater if the maximum flood discharge is smaller.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.3
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• pp.187-196
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• 2021

When evaluating the extent of the impact of water pollutants on the surrounding area, we would like to present the target level (proposal) of the quality of the environment, which is the standard for evaluation. We propose the environmental quality target level for substances that need to be applied domestically by investigating overseas cases operating the integrated environmental management system and the implications of domestic environmental pollutant management. The appropriateness of the environmental quality target level reviewed in this study was determined using data from the water quality measuring network, and future improvement measures were proposed. We review the available methodologies for setting quality objectives for the environment. It proposed the environmental quality target level for 21 substances that have domestic water pollutant emission standards and do not have environmental standards, and proposed future improvement measures. If it is necessary to add quality target-level items of the environment in the future, it is believed that expansion will be possible based on the methodology presented in this study.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.5
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• pp.63-72
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• 2004

This study was carried out to analyze effects of soil, water level and shading on growth of sweet flag(Acorus calamus var. angustatus). Three types of soil were used, which included sandy, silty loam and paddy loam soil. Three levels of shading were applied in the experiment: no shading, 55％ shading and 75％ shading. The water levels were also adjusted to three levels in the experiment. The results are summarized as follows; 1. The cultivation of sweet flag in sandy soil with low water level resulted in decreased fresh weight compared to that at planting. This result indicates that the water level should be maintained higher than the soil surface for sweet flag growth in sandy soil. 2. 5 out of 72 sweet flags died in paddy loam soil. Water saturation of soil easily reduced paddy loam soil, and root growth of sweet flags in reduced soil condition were restricted, resulting in the dead plants. 3. The growth of sweet flag in paddy loam soil was worse than those in silty loam, indicating that reduced soil conditions in paddy loam is harmful to root growth. In planting sweet flags in paddy loam, improved soil aeration in paddy loam soil is necessary for good growth of sweet flag. 4. The maintaining of high water levels is better than that of low water levels in sweet flag cultivation. During winter, soil near the water surface froze and sweet flags in frozen soil were stressed physiologically. Maintaining high water levels prevents soil from being frozen which is good for the growth of sweet flags. 5. There was not significant difference in the growth of the sweet flag between non-shading and 55％ shading. It thus appears that sweet flags can grow soundly under shading rate lower than 55％.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.709-720
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• 1997

When flood control storage lacks for the reservoir operation of multipurpose dams during flood period, the additional flood control storage should be considered for the flexible use of limited storage capacity. Flood period is divided by meteorological characteristics in this study and the water levels for water demand and flood control are investigated for the divided flood period. Based on the investigations, we suggest the variable restricted water level(VRWL) from the considerations of water conservation and flood control which can determine dam operating water level during flood period. This paper presents an application of the methodology to determination of the VRWL during flood period at the Taechong Dam and the results are discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.8
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• pp.468-474
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• 2009

Ground water source heat pump system is the oldest one of the ground source heat pump systems. Despite of this, little formal design information has been available until recently. The important design parameters for open system are the identification of optimum ground water flow, heat exchanger selection and well pump. In this study, the capacity of 50 RT system of two well type ground water heat pump system was used. As a result, static water level was -7 m and the level during the heating operation was -32 m, cooling operation was -40 m. The initial static water level recovered within 48 hrs. The temperature of ground water is $15.6^{\circ}C$ for heating season and $16.2^{\circ}C$ for cooling season and does not depend on the outdoor temperature. Operation efficiency of the system shows that, COP 3.1 for heating and COP 4.2 for cooling.