• Journal of the Korea Safety Management & Science
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• v.16 no.2
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• pp.211-216
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• 2014

Using a high-rise building water piping after hydrostatic test of the reliability of the leak to be completed if the pressure is maintained until the leak is not commercially available considered. Due to the nature of high-rise buildings and the construction period will take several years from the lower levels of use of the water supply and fire fighting water pipe construction is in progress, the order of which I do most of the first pipe to the construction and more than three years. So kind of riser pipe is complete, install the valve in the basement by installing an automatic pump to maintain a constant pressure after hydrostatic test and after each floor plumbing piping is complete, the progress of the hydrostatic test without undergoing a separate branch pipe the valve is opened automatically when the number of the pressing pressure of the structure. I kind of do and keep working pressure of pipe until the completion of the construction work to keep the damage to human error when it is intended to prepare. In winter, the frost protection and an alternative to drainage water pipe is damaged or deformed, even if unaware of the finishing work to the building, the use of the damage caused by a leak in a after construction of finish work to be expected. Alternative to reduce this damage if the pressure test without fear of freezing to help maintain long-term commercial pressures may be considered.

• Journal of Internet of Things and Convergence
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• v.9 no.6
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• pp.93-98
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• 2023

In paddy rice farming, water management is a critical task. To suppress weed emergence during the early stages of growth, fields are deeply flooded, and after transplantation, the water level is reduced to promote rooting and stimulate stem generation. Later, water is drained to prevent the production of sterile tillers. The adequacy of water supply is influenced by various factors such as field location, irrigation channels, soil conditions, and weather, requiring farmers to frequently check water levels and control the ingress and egress of water. This effort increases if the fields are scattered in remote locations. Automated irrigation systems have been considered to reduce labor and improve productivity. However, the net income from rice production in 2022 was about KRW 320,000/10a on average, making it financially unfeasible to implement high-cost devices or construct new infrastructure. This study focused on developing an IoT-Based irrigation valve that can be easily integrated into existing agricultural infrastructure without additional construction. The research was carried out in three main areas: Firstly, an irrigation valve was designed for quick and easy installation on existing agricultural pipes. Secondly, a power circuit was developed to connect a low-power Cat M1 communication modem with an Arduino Nano board for remote operation. Thirdly, a cloud-based platform was used to set up a server and database environment and create a web interface that users can easily access.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.5
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• pp.436-443
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• 2005

Experimental study was performed to understand the operation of an on-site showcase working in a super discount store. Inlet and outlet temperatures of evaporator, condenser, expansion valve and compressor were measured for both air and refrigerant sides. Electric power consumption of compressors, defrosting heaters, cooling water pumps and etc. were measured. The operating characteristics of the showcase system under various working conditions were analyzed and discussed. During the defrosting process, the air temperature inside the showcase increased to $15^{\circ}C$, which gave harmful effect to the frozen food. The collected data will serve as valuable information for diagnosing and improving the performance of showcases.

• Journal of Power System Engineering
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• v.19 no.3
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• pp.69-74
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• 2015

Check valves used in vessels include shock-release function on piping system, aside from basic back flow prevention. However, proper and enough protection of system is not obtainable due to use of high-pressure and bulk fluids, resulting from enlargement of vessels. In this study, casting analysis of check valves protecting systems in flow path from water hammering or back flow is conducted, using Z-CAST program. Also, molten metal filling, flow analysis, solidification analysis and shrinkage cavity analysis are conducted. The main results are as following. Regarding filling of each risering, molten metal showed stable supply condition without being isolated. It was identified that the final solidification exists on risering, but shrinkage cavity possibly might happens at the point of isolation solidification.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.50-55
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• 2015

This study examined the relationship between the shape of the inside of the PRV and the cavitation of the water supply system of an apartment house. In this paper, nine types of PRV with different gaps and shapes were analyzed numerically using a 3D model embedded in the commercial code, ANSYS-CFX. The lowest pressure and the maximum velocity occurred at the narrow gap, which is located at the between the stem and the disk. When the gap size was increased, the vapor volume fraction was always greater than 0, but the vapor volume fraction of the type of expansion pipe approached 0. These results indicate that the cavitation of PRV can be reduced by a shape change to the type of expansion pipe.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.19-19
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• 2018

최근 경주, 울산, 포항 등 경상도 지역에서 잇달아 발생한 대규모 지진으로 인해 사회기반시설물의 내진 안전성이 이슈가 되고 있다. 지진 안전 국가라고 여겨지던 우리나라는 상대적으로 지진에 대한 대비가 매우 부족한 실정이며, 자칫 대규모 피해로 이어질 우려가 있다. 특히 상수관망의 경우, 지중에 매설되어 있는 특성상 지진에 취약하고, 그 피해를 발견하기 어려워 장기적인 피해가 불가피하다. 상수관로의 지진피해는 누수와 파손으로 구분할 수 있으며, 파손관의 경우 용수공급능력을 크게 저하시키기 때문에 신속한 복구가 요구된다. 파손관의 복구는 부근에 위치한 차단밸브를 닫아 피해관로의 통수를 차단한 후에 복구 작업을 진행하는 것이 일반적이다. 이때, 차단밸브의 위치에 따라 단수구역이 광범위하게 발생할 수 있어 시스템 전반의 용수공급능력 저하로 이어질 가능성이 있다. 본 연구에서는 지진 발생 후 피해관로의 효율적인 복구전략 마련을 위한 상수관망 지진피해 복구 시뮬레이션 모형을 개발하였다. 개발 모형은 피해복구에 따른 상수관망 시스템의 용수공급능력을 정량적으로 산정할 수 있으며, 지진 발생과 같은 비정상 상황의 시스템 용수공급능력을 수리학적으로 정확하게 해석하기 위해 압력기반의 해석(Pressure-driven analysis, PDA)을 적용하였다. 또한, 피해관로의 복구 시, 차단밸브에 의해 발생되는 단수구역을 탐색한 후, 수리해석 모의에 적용함으로써 현실적인 용수공급 상황을 모의할 수 있도록 하였다. 본 연구에서는 개발모형을 활용하여 차단밸브의 위치 및 개수가 단수구역의 범위 및 지진복구에 미치는 영향을 정량적으로 비교 분석하였으며, 이를 통해 효율적인 지진피해 복구 전략을 제시하였다.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.3
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• pp.395-406
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• 2015

This research carried out an analysis on input cost and leakage reduction effect by leakage reduction method, focusing on the project for establishing an optimal water pipe network management system in the Taebaek region, which has been executed annually since 2009. Based on the result, optimal cost-benefit analysis models for water distribution network rehabilitation project were developed using DEA(data envelopment analysis) and multiple regression analysis, which have been widely utilized for efficiency analysis in public and other projects. DEA and multiple regression analysis were carried out by applying 4 analytical methods involving different ratios and costs. The result showed that the models involving the analytical methods 2 and 4 were of low significance (which therefore were excluded), and only the models involving the analytical methods 1 and 3 were suitable. From the result it was judged that the leakage management method to be executed with the highest priority for the improvement of revenue water ratio was installation of pressure reduction valve, followed by replacement of water distribution pipe, replacement of water supply pipe, and then leakage detection and repair; and that the execution of leakage management methods in this order would be most economical. In addition, replacement of water meter was also shown to be necessary in case there were a large number of defective water meters.

• 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.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.399-404
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• 2008

Condensing gas boiler units may make a big role for the reduction of energy consumption in heating industries. In order to decrease the energy consumption of a condensing gas boiler unit, the effective control of the system is necessary. In this study, control algorithms of a condensing gas boiler were developed. Control algorithms are composed of the setpoint algorithm and the control algorithm. The setpoint algorithm consists of the supply water temperature setpoint algorithm and the pump setpoint algorithm. The control algorithm consists of the gas valve control algorithm and the blower control algorithm. In order to analyse the performance of control algorithms, dynamic models of a condensing gas boiler system were used. Simulation results showed that control algorithms developed for this study may be practically applied to the condensing gas boiler.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.5
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• pp.397-402
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• 2016

This study presents the performance characteristics of a small Francis turbine with an inline casing and is a continuation of a previous study. A new runner design has been implemented using the previous facility. The specific speed of the new runner has been modified from $N_s$ 80 to $N_s$ $100m-kW-min^{-1}$. This turbine can be installed in a city water supply system. To dissipate excess pressures in the water line system an inline-turbine can be used instead of an inline-pressure reducing valve. Thus, some of the energy can be recovered by utilizing the pressure difference. For best applicability and minimal space consumption, the turbine is designed with an inline casing instead of a common spiral casing. As a characteristic of inline casing, the flow accesses to the runner are in the radial direction, showing low efficiency. The installation of vanes improves the internal flow and positively affects the output power. In contrast to the previous study, the new runner reduces the effect of the stay vanes by maintaining a higher efficiency.