• Journal of the Korean Solar Energy Society
• /
• v.27 no.4
• /
• pp.105-111
• /
• 2007

Hybrid PV/Thermal systems consisting of photovoltaic module and thermal collector can produce the electricity and thermal energy. The solar radiation increases the temperature of PV modules, resulting in the decrease of their electrical efficiency. Accordingly hot air can be extracted from the space between the PV panel and roof, so the efficiency of the PV module increases. The extracted thermal energy can be used in several ways, increasing the total energy output of the system. This study describes a basic type of PV/T collector using water. In order to analyze the performance of the collector, the experiment was conducted. The result showed that the thermal efficiency was 17% average and the electrical efficiency of the PV module was about $10.2%{\sim}11.5%$, both depending on solar radiation, inlet water temperature and ambient temperature.

• Journal of Korean Society of Water and Wastewater
• /
• v.33 no.6
• /
• pp.457-467
• /
• 2019

Because non-point source pollution is very closely related to hydrological characteristics, its importance is highly emphasized nowadays along with accelerating climate change. Especially for Korea, the non-point source pollution and its control are entirely depending on runoff, precipitation, drainage, land use or development, based on geographical and topographical reasons of Korea. Many studies reported the physical (e.g., apparatus- and natural-type facilities, etc.) and chemical methods (e.g., organic and inorganic coagulants, etc.) of controling non-point pollutant source pollution, however, those are needed to be reconsidered along with climate change causing the unexpected patterns and amounts of precipitation and strengthen complexity of social community. The objectives of this study are to assess recent situations of non-point source pollution in Korea and its control means and to introduce possible effective ways of non-point source pollution against climate change in near future.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.11a
• /
• pp.91-94
• /
• 2006

The way to shorten a construction period is considered to an very important technology development element as reducing the formwork removal periods with promoting strength revelation own concrete. This study executed experiment to review usability of early strength revelation chemical admixture which is judged in ways effective with premature removal of form about concrete. Use of early strength revelation AE water reducin admixture is apperaing so that strength revelation by early hydration promotions is excellent. The results of being applied proposed work process are that compressive strength are appeared more than 5MPa within 16 hours so that removal of vertical form was possible. the concrete compressive strength satisfied with a more than 2/3 of specified concrete strength for removal of horizontal form are appeared in 42 hours of 27 MPa proportioning strength, in 36 hours of 30, 35 MPa proportioning strength so that the 6 days cycle time of concrete structural frame work is cut by 2 days as shortening delayed period in works of removing slab forms. So construction cost reductions and a construction period shortening are judged so that it is possible.

• Journal of the Society of Naval Architects of Korea
• /
• v.32 no.4
• /
• pp.48-54
• /
• 1995

A new propeller open water testing device is developed and tested in a tow tank. The devised dynamometer consists of a torque measuring part, a thrust measuring part and a driving motor with an RPM counter. Torque is designed to be measured directly from the torsion of the structure holding the motor by using strain gauges and, consequently, conventional slip ring is removed. Also, in order to make the device fit in relatively small model ships, the weight and the size of the whole integrated structure are reduced in various ways. The developed tester is proved to be easily utilized in small circulating water channel experiments and is believed to have provided us with essential information for future design of various types of conventional or object oriented force measuring device.

• Journal of Korean Society on Water Environment
• /
• v.27 no.3
• /
• pp.286-292
• /
• 2011

Preparing for the Standards for Effluents which will be strengthen from 2012, many ways like remodellings and repairs of sewage treatment plant (STP) are considered. The treatment of the recycle water from the sludge treatment process contains high-strength organic compounds and nitrogen is considered as alternative. In the treatment of high-strength nitrogen, nitritation has more economic advantages than nitrification. In this study, lab-scale reactor was operated at the $35^{\circ}C$, $20^{\circ}C$ and $10^{\circ}C$ conditions using effluent of anaerobic digester to investigate the nitrogen removal by nitritation. Long-term stable nitritation was achieved at the $35^{\circ}C$, $20^{\circ}C$ but $10^{\circ}C$. In the stable nitritation states, nitrite conversion was higher at the high temperature of $35^{\circ}C$ than the room temperature of $20^{\circ}C$. Also shorter solid retention time (SRT) was needed to induce high nitrite conversion at the high temperature of $35^{\circ}C$. It was showed that temperature and SRT are important factors to induce nitritation.

• Journal of dental hygiene science
• /
• v.22 no.1
• /
• pp.51-56
• /
• 2022

Background: The coronavirus disease (COVID-19) pandemic increased awareness regarding the importance of hand hygiene in infection prevention. Although social distancing and vaccination are the strongest ways to prevent infection, personal hand hygiene is the most basic and easiest way to maintain public health. However, in addition to hand washing using running water, sanitizing tissues, and disinfection products are convenient for hand hygiene, especially outdoors. Therefore, it is necessary to improve the appropriateness of individual hand hygiene methods. In this study, we investigated the degree of hand hygiene offered by various hygiene products and hand drying methods for maintaining hand hygiene. Methods: An LED UV light kit was used for fluorescent observation of hand contamination. Bacteria from the hands were cultured to compare the degree of hand hygiene offered by various hygiene products. Bacteria were cultured in a hand-shaped medium dish to identify areas vulnerable to hand hygiene. Moreover, the degree of hand hygiene was observed according to the drying method using bacterial cultures. Results: We confirmed that hand washing under running water with antibacterial soap, sanitizing with alcohol gel disinfectant, and wiping with antibacterial wet wipes was effective for hand hygiene compared to washing under running water alone. However, for all hygiene products, a large number of bacteria were detected on the fingertips. We verified that natural drying, rather than rubbing, is effective in maintaining hand hygiene. Conclusion: These results suggest that hand hygiene products and drying methods are critical in hand hygiene management. Therefore, these results provide a basis for determining whether an individual's hand hygiene management method is appropriate.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.60 no.1
• /
• pp.47-56
• /
• 2024

After the United Nations Convention on the Law of the Sea (UNCLOS) and the United Nations Fish Stocks Agreement (UNFSA) came into effect, international cooperation through Regional Fisheries Management Organizations (RFMOs) was required, and each RFMO established and adopted the Conservation and Management Measure (CMM) for the regional Observer Programs to collect data on fishing activities and biological information and to monitor compliance with its CMMs. The observer coverage required by RFMO is set differently for each organization, ranging from 5% to 100%. In addition, tuna-RFMOs recommend increasing observer coverage in longline fisheries by at least 20% for reliable quantitative analysis of not only target species but also bycatch species and ecologically related species such as sharks, seabirds, sea turtles, and marine mammals. Therefore, in this study, we discussed ways to improve the national observer programs of Korean distant water fisheries that should be addressed in the future to respond to the RFMO trends.

• Journal of the Korean association of regional geographers
• /
• v.7 no.3
• /
• pp.14-28
• /
• 2001

This study is to discuss the problems due to the maldevelopment occurred at the reserved areas of natural environments of the Ulleung Island, Gyeongsangbuk-do province, and it also suggests the ways of solving them The types of the maldevelopment practiced on the Ulleung Island consist of the change of land use, the opening of a round road, the destruction of mountains for the construction of harbor, the development of tourist areas, and the construction of military facilities. The decreased habitat of animals and the pollution of drinking water are occurred by the change of land use. The destruction of ecological system is due to the opening of a round road. The damage of natural landscape and the change of ocean eco-system is closely related to the construction of harbor and the destruction of mountains. Finally, the damage of rare plants and the pollution of drinking water are due to the development of tourist areas and the construction of military facilities. In the followings, the ways of solving the problems occurred by the various types of maldevelopment are suggested. First, the planning of pro-environmental development has to be established and practiced to preserve rare plants which are damaged due to the change of land use. Second, the destruction of natural landscape and resources has to be minimized by the implementation of environmental impact assesment when road and harbor are constructed. Third, the stones needed for the development of islands ought to be imported from mainland. Fourth, the established tourist areas are needed to rationally manage and the potential tourist areas has to be transferred to the reserved areas of natural environments. Fifth, military facilities should be constructed though the cooperation of autonomous local government. Finally, government officers' and residents' conscience of protecting and reserving natural environments is needed, and government has to give residents financial supports.

• Journal of Environmental Health Sciences
• /
• v.25 no.3
• /
• pp.13-22
• /
• 1999

For the purpose of inquiring into the actual conditions of water quality management of Simple Piped Water Supply(SPWS) and the satisfaction and attitudes of inhabitants about utilizing water-supply, this research was done through the questionnaires, the investigation of surrounding environment and water quality analysis in the Sangju city, Kyungsang-pookdo during 4 months from March to June, 1998. The fountainhead of SPES using ground water accounted for 65.3%, which was the highest rate in the group. Most of them was at least 10 years in the number of utilization year. 79.6% of them were exposed to many sorts of surrounding pollution origins. The examination of water was performed only through a test about water purification and 24.5% of them disinfection by chlorine also no residual chlorine was detected at all. All the waterworks did not have any education to the managers of water quality and 81.5% of them held physical examination. As a result of the water examination about SPWS, 65.3% of them were found incongruity and the valley and springing water accounted for higher than the underground water in the rate of incongruity. Looking into the details of the result in the water examination, a category of colon bacilli was ranked in the highest rate and the next one was general bacilli, nitric acid nitrogen and turbidity in order. In the satisfaction degree of the water quality, the satisfied accounted for 44.6%, and 29.2% each. Over the state of satisfaction about the ways of water examination, satisfaction accounted for 44.6%, and unsatisfaction 28.3%. Summarizing the result of the above-stated, the state of Water Quality Management of the SPWS was in a poor condition. Thus for the water Quality Management, systematic and scientific water Quality Management mainly by the administrative organization other than voluntary management by the village should be done beyond doubt. Additionally the opinions and demands of inhabitants utilizing the water supply have to be positively reflected in the affairs of water Quality Management so that the distrust of inhabitants to the SPWS should be settled.

• Journal of Korea Water Resources Association
• /
• v.57 no.4
• /
• pp.301-310
• /
• 2024

The spatial and temporal non-uniform distribution of precipitation makes water management difficult. Due to climate change, nonuniform distribution of precipitation is worsening, and droughts and floods are occurring frequently. Additionally, the intensity of droughts and floods is intensifying, making existing water management systems difficult. From June 2022 to June 2023, most of the water storage rates of major dams in the Yeongsan river and Seomjin river basin were below 30%. In the case of Juam dam, which is the most dependent on water use in the basin, the water storage rate fell to 20.3%, the lowest ever. Pyeongnim dam recorded the lowest water storage rate of 27.3% on May 4, 2023. Due to a lack of precipitation starting in the spring of 2022, Pyeongnim dam was placed at a drought concern level on June 19, 2022, and entered the severe drought level on August 21. Pyeongrim dam and Suyangje(dam) have different operating institutions. Nevertheless, the low water level was not reached at Pyeongnim dam through organic linkage operation in a drought situation. Pyeongnim dam was able to stably supply water to 63,000 people in three counties. In order to maximize the use of limited water resources, we must review ways to move water smoothly between basins and water sources, and prepare for water shortages caused by climate change by establishing a consumer-centered water supply system.