• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.2
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• pp.116-121
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• 2004

Physiological responses and tolerance limit of hybrid striped bass $(Morone\;Chrysops\;male{\times}\;M.\;saxatilis\;female),$ were investigated on salinity changes from 33 psu to 0 psu and from 0 to psu 33 psu in two separate trials, respectively. In the acute salinity decrease from sea water (33 psu) to fresh water (0 psu), plasma level of cortisol, glucose, total protein, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not affected, however, $Na^+,\;Cl^-$ and osmolality significantly decreased. In the acute salinity increase from fresh water to sea water (33 psu), plasma cortisol level did not change. Glucose and total protein concentrations in plasma and hematocrit (Hct) decreased, whereas AST, ALT, $Na^+,\;Cl^-$ and osmolality increased. The hybrid striped bass can overcome the acute changes of salinity, from 0 psu to 33 psu or from 33 psu to 0 psu, But salinity decrease stressed the fish much more than salinity increase.

• Journal of Korea Water Resources Association
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• v.49 no.7
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• pp.615-623
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• 2016

This Study calculated the Submerged Flow Characteristics and Discharge coefficient by the rising angular change of the Improved-Pneumatic-Movable. According to the result, the smaller the ratio of weir height and weir length (L/W) or the weir standing angle, the bigger of the downstream head ($H_2$). The change of discharge reduction factor ($Q_s/Q_1$), by the hight from weir crest to downstream surface and the ratio form weir crest to upstream water height ($h_t/H$), was decreased when the $h_t/H$ closed to number 1. Although the weir water depth of the down-stream was shallower level than the up-stream, the velocity was faster then before. And the more the flow, the less the gab between the upper and lower reaches level. And when the same flow condition, the downstream head ($H_2$) was increased when the L/W was bigger. The Submerged Flow Discharge coefficient of Improved-Pneumatic-Movable weir was made by the upstream approach flow head and the upper lower stream flow condition, not by the physical data of Movable weir.

• Journal of Korean Society on Water Environment
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• v.32 no.2
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• pp.135-141
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• 2016

This study investigated changes of hydrology, soil characteristics, riparian vegetation communities, and geomorphology in sandbars before and after sand-mining to determine the effect of sand-mining at upstream of Guemgang and Bochungcheon streams in Korea. Sand-mining events affected the mining area. They supplied organic matters and nutrients during flood. Sediment deposition caused soil texture change and expansion of vegetation area. However, riverbeds were stabilized after the disturbance. According to the analyses of aerial photographs, the vegetation area was significantly expanded in both dam-regulated streams and dam-unregulated streams after sand-mining. Willow shrubs advanced in disturbed area at an average of 10 years after sand-mining. It took willows trees 10.6 years to become dominant communities. Therefore, it took a total of 20.6 years for new riparian forest to form in sandbar after sand-mining. Our results confirmed that stream flow condition were dependent on vegetation recruitment in dam-regulated streams and dam-unregulated streams. For willow recruitment in unregulated streams, calculation of water level below dimensionless bed shear stress is important because low water level variation is a limiting factor of vegetation recruitment.

• Journal of Soil and Groundwater Environment
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• v.17 no.4
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• pp.51-62
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• 2012

Effects of climate change on groundwater system requires understanding the groundwater system in temporal and spatial scales through the long-term monitoring. In this study, the spatio-temporal variations of groundwater were analyzed through the continuous observation of water level, electrical conductivity (EC) and water temperature with automatic data-loggers and sampling in a Gwangneung catchment, Korea, for the four years from 2008 to 2011. Groundwater monitoring were performed at the nest-type wells, MW1 and MW2, located in upsteam and downstream of the catchment, respectively. During the survey period, both the total amount of annual precipitation and the frequency of concentrated rainfall have increased resulting in the elevation of runoff. Water level of MW1 showed no significant fluctuations even during the rainy season, indicating the confined groundwater system. In contrast, that of MW2 showed clear seasonal changes, indicating the unconfined system. The lag-time of temperature at both wells ranged from one to three months depending on the screened depths. Results of chemical analyses indicated that major water compositions were maintained constantly, except for the EC decreases due to the dilution effect. Values of the stable-isotope ratios for oxygen and deuterium were higher at MW2 than MW1, implying the confined system at the upstream area could be locally developed.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.259-262
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• 2003

In the Republic of Korea, Ministry of Construction & Transportation and Korea Water Resources Corporation manage the national groundwater monitoring network at the 169 stations and will organize the supplementary groundwater monitoring network at the 10,000 stations by 2011 year. The method that organizes the monitoring network was developed using the Analytic Hierarchy Process with pairwise comparison. Several estimation factors for the estimating every district were selected to reflect each district conditions. Their weighting value was decided by pairwise comparison and questions to the experts about groundwater The optimal number of groundwater monitoring well was calculated through the developed method. To verify this method, groundwater was monitored in Jeonju city by way showing the example. The study area In Jeonju city needs 7 stations for the supplementary groundwater monitoring network. The results monitored in 7 stations inferred the groundwater level around the study area by Kriging. The mean of residual between inferred groundwater level value from Kriging and actual groundwater level is rather low. Furthermore, the mean and standard deviation of residual between inferred groundwater level change and actual groundwater change is much lower. The Fact that 7 monitoring stations are sufficient for observing the groundwater condition in the study area makes it possible for suggested monitoring number to be proper.

• Journal of Biosystems Engineering
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• v.29 no.6 s.107
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• pp.521-530
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• 2004

The solar powered water pump is very ideal equipment because solar power is more intensive when the water is more needed in summer and it is very helpful in the rural area, in which electrical power is not available. The average solar radiation power is $3.488\;kWh/(m^2{\cdot}day)$ in Korea. In this study, the experimental system of the water pump driven by the radiation energy were designed, assembled, tested and analyzed fur realizing the solar powered water pump. Energy conversion ken radiation energy to mechanical energy by using n-pentane as operating material was done and the water pumping cycles were able to be continued. The quantity of the water pumped per cycle ranged from 2 L to 10 L depending on the level of the valve open area far the vapour supply. The average quantity was about 4,366 cc. The thermal efficiency was about $0.018\%$. The pressure level of the n-pentane vapour in flash tank was about $110\~150\;kPa$ and that in the water tank was $93\~130\;kPa$. The pressure in the condenser during cycles was maintained as about 70 kPa. The condensation of the n-pentane vapour in the water tank was increased with the cycles even though the internal and external insulation were done. Air tank performance was better with increasing of the water piston displacement and the water could be pumped with the water piston displacement becoming higher than 6,500 cc.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.4
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• pp.244-254
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• 2013

In this study, a method has been developed for estimating the change of nearshore random waves in response to sea-level rise, by extending the method proposed for regular waves by Townend in 1994. The relative changes in wavelength, refraction coefficient, shoaling coefficient, and wave height for random waves are presented as functions of relative change in water depth. The changes in wavelength and refraction coefficient are calculated by using the significant wave period and principal wave direction in the regular-wave formulas. On the other hand, the changes in shoaling coefficient and wave height are calculated by using the formulas proposed for shoaling and transformation of random waves in the nearshore area including surf zone. The results are proposed in the form of both formulas and graphs. In particular, the relative change in wave height is compared with the result for regular waves.

• Journal of Korean Society of Disaster and Security
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• v.13 no.4
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• pp.1-12
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• 2020

Recently, as the extreme drought continued due to the reckless development and the dramatical climate change, national concern about the water management issues has been increased rapidly around the world, especially in Korea. Meanwhile, it is necessary to analyze and review the related cases in Australia, where they have developed the consistently, eco-friendly and systematically management from the national level, which is similar to that of Korea in difficult circumstances. Australia has been suffered by repeated droughts and floods due to low rainfall and dryness, and water disputes were begun with immigrant settlement in the 1890s. In the early days, water management agreements for efficient distribution of water resources, water use regulation programs, and federal water laws were enacted, and now the established water management system in which development and conservation are assumed to be well balanced. In Korea, however, in the past, the Ministry of Environment was responsible for water quality issues while the quantity was managed by the Ministry of Land, Infrastructure and Transport, and the main local departments for water management were divided. Therefore, it was difficult to manage the integrated water management due to problems such as duplicated works, excessive investments, and inefficiency. To resolve this situation, in 2018, all water management functions were unified, such as enacting the fundamental water-related laws, thereby laying the foundation for the integrated water management system for each basin. From 2019, even the integrated water management system was implemented, we are promoting the effect of sustainable water resource management. In order to establish a management policy for efficient and eco-friendly water management, the IWRM (Integrated Water Resource Management) of Australia, which has been devised in various ways, was analyzed and compared with the present situations and cases occurred in Korea, and the implications from this study would be suggested the future of IWRM in Korea.

• Ocean and Polar Research
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• v.45 no.2
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• pp.71-87
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• 2023

Climate change causes ocean warming, ocean acidification, sea-level rise, dynamic coastal risk, change of ecosystem structure and function, and degradation of ecosystem services. Not only that, but it has negatively impacted the well-being of people, society, and culture, including food security, water resources, water quality, livelihood, health, welfare, infrastructure, transport, tourism, recreation, and so on, especially by particularly degrading indigenous communities and generating an inequitable distribution of benefits and costs. As pointed out here, these adverse impacts of climate change on the ocean have been emphasized at the international and national levels. In contrast, the ocean field has been neglected in the climate change conversation for too long. However, since the UNFCCC COP 25, the ocean has been drawn into the discussion as a solution to address climate change. Moreover, the U.S. Congress recently unveiled a bill called the 'Ocean-Based Climate Solution Act, OBCSA' that reflects the new paradigm of the international regime. The comprehensive legislative bill includes elements related to climate inequity, a blue economy, and a community-led bottom-up policy mechanism, which will have a significant bearing on the ocean-climate legal system. Therefore, this study reviews the OBCSA and deduces implications with regard to the ocean-climate legal system in Korea.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.4
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• pp.93-103
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• 2018

The aim of this study is to apply the Water-Energy-Food-Land Nexus approach which can analyze the trade-offs among resources, and assess the holistic impacts of food security. First, we applied rice as a study crop and analyzed the trend of consumption of rice and the area of paddy fields. Second, the portfolios of water, energy, and land for rice production were constructed using data of footprints and productivity. Finally, the self-sufficiency ratio (SSR) of rice in target year was set as food security scenario and assessed the impacts of food security on water, energy, and land availability. In 2030, the SSR of rice decreased to 87 %, and water use for producing rice decreased from 4,728 to $3,350million\;m^3$, and the water availability index increased from 0.33 to 0.53. However, food security is essential issue and we set the 50 % and 100 % SSR of rice as high and low food security scenarios. For 100% SSR in 2030, about $3,508million\;m^3$ water was required and water availability index reached to 0.5. In other words, there is the trade-off between food security and water-energy-lands availability. Therefore, it is difficult to make a decision whether a high level of SSR is better or worse. However, this study showed the both positive and negative impacts by change of food security and it can be useful for setting the policy decision considering both food security and sustainable resource management at the same time.