• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.373-381
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• 2012

An automatic flow and water quality monitoring system was applied to estimate pollutant loads to an urban stream during storm events in DTV (Daeduk Techno Valley), Daejeon, Korea. The monitoring system consists of rainfall gage, ultrasonic water level meter, water quality sensors for DO, temperature, pH, conductivity, turbidity and automatic water sampler for further laboratory analysis. All data are transmitted through on-line system and the monitoring system is designed to be controlled manually in the field and remotely from laboratory computer. Flow rates were verified with field measurements during storm events and showed good agreements. Automatic sampler was used to collect real time samples and analyzed for BOD, COD, TN, TP, SS and other pollutant concentrations in the laboratory. SWMM (Storm Water Management Model) urban watershed model was applied and calibrated using the observed flow and water quality data for the study area. While flow modeling results showed good agreement for all events, water quality modeling results showed variable levels of agreement. These results indicate that current options in the SWMM model to predict pollutant build up and wash-off effects are not sufficient to satisfy modeling of all the rainfall events under study and thus need further modification. This study showed the automatic monitoring system can be used to provide data to assist further refinement of modeling accuracy. This automatic stormwater monitoring and modeling system can be used to develop basin scale water quality management strategies of urban streams in storm events.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.18-25
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• 2019

Recently, micro-grids based on a CVCF inverter have been replacing diesel generators to reduce CO2 emissions in island areas with the increase of renewable energy sources. Stable operation methods are also being researched. These micro-grids may cause energy sinking if the total output of renewable energy sources is larger than the total customer loads. In the case of energy sinking, the voltage of a CVCF battery could rapidly increase according to the condition of SOC, and blackout could occur in the micro-grid due to the operation of a protection device in a CVCF inverter. Therefore, this paper analyzes the operation characteristics of a CVCF-inverter-based micro-grid when energy sinking occurs and proposes a transient operation strategy to prevent shut-down of the CVCF inverter. A test device of a 30-kW CVCF-inverter-based micro-grid was implemented, and the transient operation characteristics for the energy sinking phenomenon are presented. The simulation results confirm that blackout can be properly prevented according to the conditions of SOC and voltage in a CVCF battery.

• Journal of Korean Society of Disaster and Security
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• v.15 no.2
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• pp.27-36
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• 2022

The adequacy of industrial water supply is one of the core elements of the construction of industrial complexes. This study examined the supply of industrial water through various ways, according to the planning and creation of industrial complexes and the operating utilization rate of tenant companies oksan industrial complex. As for calculating the supply of industrial water and establishing water supply plan, the basic data analysis and the land use plan are utilised. The adequacy of calculating the basic unit by industry, which is the basis for calculating industrial water, was evaluated. In addition, analyzed industrial water usage data and the raw unit of each industry was compared with the actual data from the Oksan Industrial Complex, which selected as the research target area among the industrial complexes in Cheongju-si administrative districts, where actual data can be secured. The result of the study shows that the peak load rate of industrial water was found to have the peak load of more than twice as the result of analyzing the actual usage, and the basic unit of industrial water industry showed a significant difference from the actual usage. In particular, the decreasing rate of the basic units was significant comparing the increasing rate of basic units. In addition, the raw unit of the industry that uses more water decreased significantly, and the raw unit of the industry that uses less water increased slightly.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1035-1042
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• 2005

Granular Activated Carbon(GAC) is widely used in drinking water treatment. At S and B Water Treatment Plant, GAC is used in place of granular media in conventional rapid filters(GAC Filter-Adsorber) for removal of Disinfection By-products(DBPs). The primary focus of this study is on the performance of existing filter-adsorber, and their operation. It was found that F/A process removed turbidity as effective as sand system. The ratio of Hydrophobic DOM (HPO) and hydrophilic DOM (HPI) fraction in the raw water at S and B WTP was similar. Filter Adsorber presented earlier DOC breakthrough and steady state condition which was contributed by biodegradation during operation period. The removal efficiency of DBPs were used to evaluate the filter performance. The DBPs concentration of F/A treated water was below treatment goal level (THM < $80\;{\mu}g/L$, HAA < $60{\mu}g/L$). The removal efficiency of THM decreased rapidly during operation period. However, HAA were removed steadily regardless of the influent concentration of HAA. These results indicate that the removal of THM depend upon the adsorption mechanism while the removal of HAA depend upon biodegradation as well as adsorption. The decrease of adsorption capacity and characteristic value of GAC may be attributed to the effect of high organic loading, residual free chlorine, coagulants, manganese oxidants and frequently backwashing. This study has confirmed that Filter adsorber process can be considered as effective alternatives for the removal of DBPs, especially HAA.

• Journal of Life Science
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• v.34 no.1
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• pp.37-47
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• 2024

FUN14 domain-containing protein 1 (FUNDC1), an outer mitochondrial membrane protein, contributes to removal of damaged mitochondria through mitophagy. In this study, to elucidate the role of the FUNDC1 in the amyloid beta peptide (A_β)-induced neuropathy, changes in the degree of mitochondrial dysfunction and cell injury caused by A_β treatment were examined in the HT-22 neuronal cells in which the FUNDC1 expression was transiently silenced or overexpressed. We found that A_β treatment causes a time-dependent decrease of the FUNDC1 expression. In the A_β-treated cells, there were a drop in MTT reduction ability, depletion of cellular ATP, disruption of mitochondrial membrane potential, stimulation of cellular ROS production, and increased mitochondrial Ca²⁺ load. Activation of caspase-3 and induction of apoptotic cell death were also observed. Transient silencing of the FUNDC1 expression by transfection with the FUNDC1 small interfering RNA per se caused mitochondrial dysfunction and apoptotic cell death like the effect of A_β treatment. Conversely, in cells in which the FUNDC1 was transiently overexpressed by FUNDC1-Myc transfection, overexpression itself had no effect on the mitochondrial functional integrity and cell survival but showed a significant prevention effect against mitochondrial and cell injury caused by A_β treatment. Overall, these results suggest that the FUNDC1 is importantly involved in the A_β-induced mitochondrial dysfunction and cell injury in the HT-22 neuronal cells.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.11
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• pp.675-690
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• 2003

In this paper, we present the virtual dancing studio for distributed virtual environment. In this system, geographically distributed user shares the virtual dancing hall and interacts with each other. The participating object can be a graphical avatar or a live video stream. It allows the coexistence of graphic objects and real images in the shared virtual space. One of the main technical challenges in developing the distributed virtual environment is to handle excessive network traffic. In an effort to effectively reduce the network traffic, we propose a scheme to adjust the QoS of each object with respect to the distance from the observer in the virtual space. The server maintains the QoS vector for each client's shared space and controls the packet traffic to individual clients based on its QoS vectors. We develop a proto-type virtual dancing environment. Java based development enables the client to be platform independent. The result of experiment shows that the adoption of hierarchical QoS management significantly reduces the overall network traffic.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.11
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• pp.749-757
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• 2017

To cope with the development of alternative fuels and international environmental regulations, this study provides a numerical analysis of the effects of composition and temperature changes of n-decane and ethanol on auto-ignition characteristics. CHEMKIN-PRO is used as the analysis program and the LLNL model is used as the reaction model. The numerical results show that the ignition delay time increases as the mole fraction of ethanol increases for temperatures below 1000 K, where low temperature reactions occur. Because of the high octane number of ethanol, the high percentage of ethanol delays the increase in the concentration of OH radicals that cause ignition. The oxygen concentration in the mixture is changed to apply the exhaust gas recirculation and a numerical analysis is then performed. As the oxygen concentration decreases, the total ignition delay time increases because the nitrogen gas acts as a thermal load in the combustion chamber.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.1
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• pp.57-65
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• 2001

The speed control without a speed sensor is expected strongly to progress reliability, simplicity and cost performance of Induction Motor(I.M) systems. Also, it contributes to expansion of I.M systems into various industrial application fields. This paper investigates a novel speed sensorless control method of I.M considering the secondary resistance identification based on the transientless torque control technique. Especially, this paper aimed at the identification of the secondary resistance simultaneously with speed estimation superposing of sinusoidal flux wave to a constant flux value. Furthermore, the secondary flux with some frequency is controlled independently on torque control. The proposed speed estimation method is derived from a motor circuit equation theoretically and also it can be conducted easily by detecting primary motor currents and primary voltage commands at every sampling time. Some numerical simulations with the assumption of using a pulse width modulation(PWM) voltage source inverter are performed to verify the proposed method.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.715-719
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• 2005

현재 우리나라는 1970년대 이후 급속한 경제성장으로 인하여 산업화 및 도시화 현상이 심화되고 있는 실정이며, 이러한 과정에서 불투수층의 증가로 인하여 첨두유출량의 증가, 자연유역에서 도시유역으로 변하면서 유역내 도달시간의 감소 등의 수문학적 특성이 변화로 예기치 못한 홍수로 인하여 피해가 발생하고 있다. 다라서 첨두유출량이 관망으로 전달되는 과정에서 관에 발생하는 부하의 증가로 인하여 내수침수 피해를 입게 되는데, 도시 유역에서의 인구 증가 및 산업활동에 따른 도시 개발로 인한 불투수면적의 증가로 우수유출량이 커지고 있으며, 저지대의 활용이 증대됨에 따라 내수 피해는 더욱 증가되고 있는 실정이다. 이러한 도시 유역의 재배 저감 대책 수립을 위해서는 먼저 실측자료와 도시유출 모형에서 산정된 첨두유출량과의 비교$\cdot$분석하여 최적의 모형을 채택하여야 한다. 또한 채택된 모형으로 적절한 설계 강우량이 선정되어야 하고, 그에 따른 유출량을 정확히 산정하여야 하나, 설계 강우량 산정을 위한 강우의 지속시간의 결정에 대해서 일반적인 기준이 확립되지 못하고 있는 실정이기에 재해 저감 대책 수립에 많은 어려움이 따르고 있다. 이에 본 연구에서는 실측 강우량, 첨두유출량 및 유출총량과 도시지역의 유출량 산정에 사용되어지는 ILLUDAS, SWMM 모형에 모의치와의 비교 연구를 통해 최적의 도시유출모형을 제시하고자 한다. 따라서 실측자료가 있는 서울시 장안$\cdot$뚝섬배수구역의 실측 강우와 펌프장에서 조사된 실측 유량과 ILLUD AS, SWMM 모형에 의해 산정된 유량과의 비교 분석 결과 SWMM 모형에 의한 첨두유량이 실측 첨두유출량과의 오차율에서 장안배수구역은 $21.1\%$, 뚝섬배수구역은 $4.3\%$로 가장 근접한 결과를 나타내었으며, 총 유출량에서도 각각 $7.8\%,\;13.2\%$의 오차율을 가지는 것으로 분석되어 타 모형에 비해 실유량과의 차가 가장 적은 것으로 모의되었다. 향후 도시유출을 모의하는 데 가장 근사한 유출량을 산정할 수 있는 근거가 될 것이며, 도시재해 저감대책을 수립하는데 기여할 수 있을 것이라 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.986-993
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• 2012

The objective of this study is to investigate performance characteristics of the thermal management system for passenger hydrogen fuel cell vehicle under various operating conditions. The thermal management systems comprised of a stack cooling system, an electric device cooling system and an air conditioning system for a passenger room were tested with driving conditions. As a result, in highway driving mode, the cooling performance of the stack cooling system with air conditioning on condition was 28.8 % lower than that of the air conditioning off condition. And cooling load of the electric cooling system in the city driving mode was 65.6% higher than that of the highway driving mode.