• Journal of Environmental Science International
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• v.26 no.8
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• pp.881-891
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• 2017

In this study, the discharge loads of non-point pollution sources were analyzed using a Hydrologic Simulation Program-Fortran (HSPF) model for 46 sub-watersheds in order to guide the management plan for water and streams passing through the city. The results using HSPF showed good applicability in comparison to point measurements, which were based on BOD, TP, and TN. The mean value of the BOD loads was $4.08kg/km^2$ per day, and the highest level of BOD was $17.75kg/km^2$ per day at Namri. Three potential areas of high priority for the installment of constructed wetlands were selected in order to reduce non-point pollution sources based on BOD loads and on environmental and economic conditions. The results for these scenarios indicated a maximum rate of reduction in BOD of 39.12% within the proposed constructed wetlands.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.167-174
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• 1998

The numerical methodology for simulating water entry behaviors of the high-speed bodies has been developed. Since the present method assumed the impact occurs within a very short time interval, the viscous effects do not have enough time to play a significant role in the impact forces, that is, the flow around a water-entry object was assumed as an incompressible potential flow and is solved by the source panel method. The elements fully submerged into the water are routinely teated, but the elements intersected by the effective planar free surface are redefined and reorganized to be amenable to the source panel method. To validate the present code, it has been applied to the ogive model and compared with experimental data. Good agreement has been obtained. The water entry behavior of the bouncing phenomena from the free surface has been also simulated using the impact forces and two degree of freedom dynamic equation. Physically, acceptable results have been obtained.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.79-79
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• 2011

The oceans are an untapped resource, capable of making a major contribution to our future energy needs. In the search for a non polluting renewable energy source, there is a push to find an economical way to harness energy from the ocean. Tidal stream is one of ocean energy form that is being investigated as potential source for power generation. Tidal current turbines are therefore designed as conversion machinery to generate power from tidal currents. A study on energy extraction from tidal currents is presented in this paper.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.623-628
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• 2009

Desiccant based air conditioning system offers a promising alternative to conventional one using vapour compression refrigeration for energy saving and greenhouse gas reduction. It is a heat driven cycle which has high potential for the use of low grade heat source such as the waste heat from the cogeneration plant or the solar thermal energy. In this study, the cooling performance of a desiccant cooling system incorporating a regenerative evaporative cooler was characterized in various operation conditions through numerical simulation. The cooling capacity and COP were evaluated at various outdoor conditions, regeneration temperatures, and supply flow rates. Based on the performance characteristics, the optimal control scheme was discussed to minimize the cooling cost at part load condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.688-691
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• 2004

We have studied the possibility of global noise reduction by the sound power control through selection of distribution and impedance of absorptive materials. It is necessary to investigate the relation between the global sound energy in the field and the total sound power radiated by sources. In the previous work (1,2), the authors presented a useful design method to change boundary condition that can be useful to reduce noise in acoustically small enclosures. The possibility of total acoustic potential energy reduction by acoustic source power control is examined in an acoustically small cavity. Using acoustic energy balance equation, the relation between global noise control performance and absorptive material's arrangement/impedance is deduced. Numerical simulation is performed to interpret its physical meaning in terms of absorbent's distribution and impedance.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.153-154
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• 2015

Voltage Source Converter HVDC (VSC-HVDC) are a better alternative than conventional thyristor based HVDC systems. Unfortunately, VSC-HVDC's full potential cannot be utilized up till now due to absence of suitable HVDC protection. Recently, hybrid HVDC circuit breakers (HDCCB) have been developed and successfully lab tested. However, their application and feasibility in VSC-HVDC needs to be investigated. In this research paper we have modelled an existing HDCCB and evaluated its impact on fault reduction and interruption in VSC-HVDC systems. The HDCCB was applied in Korean Jeju-Haenam VSC-HVDC system model and its impact was analyzed for HVDC line-to-ground and line-to-line faults. HDCCB successfully interrupted the fault current and prevented the damages to costly IGBTs and converter transformers.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.190-201
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• 1998

The numerical methodology for computing the impact forces of the water entry bodies has been developed. The present method assumed the impact occurs within a very short time interval and the viscous effects do not have time enough to play a significant role in the impact forces, that is, the flow around a water-entry object was assumed as an inviscid potential flow and is solved by the source panel method. The elements fully submerged into the water are routinely treated, but the elements intersected with the effective planar free surface are redefined and reorganized to be amendable to the source panel method. To validate the present code, it has been applied to disk and ogive model and compared with experimental data. Good agreement has been obtained.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.267-270
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• 2003

In this paper, a new energy recovery circuit for AC PDP(Plasma Display Panel) is proposed to decrease a sustain voltage and voltage stress on switching elements. In the proposed circuit, two auxiliary capacitors are connected directly to the power source through switching elements and inductors when ground potential is supplied to the panel. Therefore, the voltage across auxiliary capacitors can be increased by turns over the half of the source voltage. Because the intrinsic capacitance of PDP is charged sufficiently from the auxiliary capacitors, the level of sustain voltage and the voltage stress on the switching devices are decreased. To verify the validity of the proposed energy recovery circuit, computer simulations using PSpice program are carried out.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.426-429
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• 2004

Eleven fungal strains previously isolated from the Mexican desert were evaluated for their capacity to use catechin as carbon source in submerged cultures. At 2 g/l of catechin, all strains grew better than the control strains, Aspergillus niger Aa-20. Aspergillus niger PSH and Penicillium commune EH2 degraded 79.33％ and 76.35％ with degradation rates of 0.0065 and 0.0074 g/l/h, respectively, when an initial catechin concentration of 3 g/l was used. Obtained results demonstrated the potential biotechnological capacity of these fungal strains to use condensed tannins as carbon source.

• Korean Journal of Pharmacognosy
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• v.28 no.2
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• pp.65-71
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• 1997

This study was carried out to purify and to characterize various bioactive material acemannan from Aloe vera. Purified acemannan was mannose (67%) and acetyl group (23%), and the rest of glucose was galactose that consists of long chain polydispered beta-(1, 4) linked mannan polymers. The sugar and acetyl group in the molecule were linked by molar ratio of 3 : 1. This polysaccharide from Aloe vera may provide functional flood and potential drug source with antiviral and immunomodulating properties.