• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.137-140
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• 2003

The flow characteristics of secondary recirculation region in a liquid fuel ramjet combustor are measured using PIV method. The model combustor has two rectangular inlets that form 90 degree angle each other. The tested angles of the air intakes were 30, 45 and 60. Three guide vanes are installed in each rectangular inlet to improve the flow stability. The experiments are performed in the water tunnel test with the same Reynolds number as the case of Mach 0.3 at the inlet. PIV software is developed to measure the characteristics of the flow field in the combustor. The accuracy of the developed PIV program is verified with rotating disk experiment and standard data. The experimental results show that the secondary recirculation flow occurred at the front junction of inlet main stream and combustorchamber. The size of secondary recirculation regions are increased with increasing air inlet angles. Since the performanceof combustor is very dependant on not only the main recirculation in the dome region but also the secondary recirculation flow in a junction region, the optimal angle of the air intakes should consider the both recirculation size as a frame holder.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.7
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• pp.930-937
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• 2011

The characteristics of mean velocity and turbulence have been analyzed in the circular open channel flow using PIV measurement data for a wide range of water depth. The measured data are fitted to a velocity distribution function over the whole depth of the open channel. Reynolds shear stress and mean velocity in wall unit are compared with the analytic models for fully-developed turbulent boundary layer. Both the mean velocity and Reynolds shear stress have different distributions from the two-dimensional boundary layer flow when the water depth increases over 50% since the influence of the side wall penetrates more deeply into the free surface. The cross-stream Reynolds normal stress also has considerably different distribution in view of its peak value and decreasing rate in the outer region whether the water depth is higher than 50% or not.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.7 no.1
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• pp.9-27
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• 1971

Oceanography of the Subarctic North Pacific Ocean is reviewed. The submarine topography and the current systems in the region are explained. Recent serial observation data reveals that. though the upper mixed layer of low salinity is relatively thick. the pattern of the property distribution in winter is essencially similar to that in summer. Alaskan Stream Extension Water. which influences the abundance and the location of demersal fishes. extends northward to 58${\circ}$ N Lat in the Bering Sea. A southeastward intrusion of the Bering Borcal Cold Water causes the formation of a sharp oceanic front. where the demersal fishes such as Alaska pollacks and cods arc concentrated. The Alaska pollacks seem to avoid the low salinity water of the Alaskan Coastal Water.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.7 no.1
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• pp.8-8
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• 1971

Oceanography of the Subarctic North Pacific Ocean is reviewed. The submarine topography and the current systems in the region are explained. Recent serial observation data reveals that. though the upper mixed layer of low salinity is relatively thick. the pattern of the property distribution in winter is essencially similar to that in summer. Alaskan Stream Extension Water. which influences the abundance and the location of demersal fishes. extends northward to 58${\circ}$ N Lat in the Bering Sea. A southeastward intrusion of the Bering Borcal Cold Water causes the formation of a sharp oceanic front. where the demersal fishes such as Alaska pollacks and cods arc concentrated. The Alaska pollacks seem to avoid the low salinity water of the Alaskan Coastal Water.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2210-2214
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• 2009

This paper summarizes progress on work under the Asian Pacific FRIEND(Flow Regimes from International Experimental and Network Data - APFRIEND) initiative of the International Hydrological Programme (IHP) of the United Nations Educational, Scientific and Cultural Organisation (UNESCO) from 2005 to 2009. The results of initial work on Rainfall Intensity Duration Frequency (IFD) have just been published as a volume by UNESCO. The results of work to date is concisely presented and observations made about lessons learnt on how to successfully integrate work from nine diverse countries with differing approaches to both hydrology and water resource management structures and on some possible directions for future work.

• Korean Journal of Microbiology
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• v.29 no.5
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• pp.339-343
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• 1991

Heterotrophic activity, total bacteria and salinity were determined seasonally in the estuary of Naktong River over half tidal cycle. Heterotrophic activity was determined by the uptake of [U- $^{14}$ C]glucose. Heterotrophic activity fluctuated with the tides and was decreased as salinity increased. Teh great activity occurred near low ebb tide at all seasons except summer. The main environmental factor affecting hetreotrophic activity was the salinity rather than water temperature in the estuary of Naktong River. In order to estimate the effect of salt, salt was added to estuarine water. Vmax for glucose of salt-added water was 17% and 77% of original estuarine water at station 1 and 2 respectively and slight increase was observed at station 3. Respiration rate and Kt+Sn for glucose of salt-added sample increased at all 3 stations. The increase of the Kt value implies the reduced affinity of bacterial population for glucose. The effects of salinity on the heterotrophic activity were more extensive in the upper region of estuary than at the mouth.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.38-44
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• 1997

6063-T5 alloys are tested in laboratory air, water and 3% NaCl solution to investigate the effects of corrosive environment on the retardation behavior through single overload fatigue test. Also, the fatigue crack propagation and the crack closure behavior are studied. The results obtained in this experimental study are summarized as follows. 1) Behaviors of fatigue crack growth retardation are observed in water and 3% NaCl solution as they do in air. The number of delay cycles and the size of affected region by single overload decrease greatly in water and 3% NaCl compared with those in air. 2) In fractographic results, the overload marking by single overload appear remarkably in air, but indistinctly in water and 3% NaCl solution. 3) The effect of crack closure on crack propagation is most remarkable in the beginning of crack propagation. With crack propagation, the crack closure level and its effect decrease greatly.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.7
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• pp.549-556
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• 2001

Heat flow characteristics during hot water extraction process was studied experimentally. Data were taken at various outlet port type for the fixed inlet port type, inlet-outlet temperature differences and mass flow rates. In this study, the temperature distribution in a storage tank and an outlet temperature were measured to predict a flow pattern in the storage tank, and a hot water extraction efficiency was analysed with respect to the variables dominating a extraction process. Experimental results show that the extraction efficiency is high in a low flow rate in case of using modified distributor I(MDI) as a outlet port type.

• Water Engineering Research
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• v.6 no.1
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• pp.1-15
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• 2005

The numerical model, FLUENT, was employed to investigate the effect of the heated water discharged from the diffuser of Boryung Power Plant. Temperature patterns of the thermal effluent discharged from two proposed types of the diffusers was evaluated for maximum flood and maximum ebb tide. The hydraulic model experiments were also performed in the reduced scale of 1/150 to verify the numerical simulation results. The buoyant jets discharged from the diffusers were found to be significantly affected by the ambient flows beyond the region where the effluent momentum was dissipated. Both the numerical and experimental results showed that the area of the excess isotherm for Type 1 diffuser was larger than that for Type 2 diffuser. Type 2 diffuser system was observed to be a more effective diffuser design than Type 1 diffuser system based on the temperature reduction and excess isotherm obtained from the numerical simulation in the ambient flows.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.577-580
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• 2003

Problem of repairing by boring is that it deteriorates stabelety and durability of structure by permeation of seawater from underneath after damage and repair of reinforcing rod regarding of spot. The purpose of this study is to improve the porblem by using the repair method of general boring to mend the of large mat basis. Direction of thes experiment is to apply the new repair material and the method to control the blazing fire factor caused by the crack from the foundation of large mat and also to estimate it's integrity. New method of construction is method of contruction that do speace scurity in vertical drilling and bottom useing water jet. New material used bantonite and rubberized asphalt. Test result existent repair method of construction large size mat basis perforation is difficult and reinforcing rod can be damaged coule there were a lot of problems with re-water leakage of crack repair region, but overcomes existent short coming by method that apply in this study.