• Ocean and Polar Research
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• v.26 no.2
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• pp.351-360
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• 2004

To investigate latitudinal variations in the zooplankton community along the meridian line ($5^{\circ}N-12^{\circ}N$, $131.5^{\circ}W$), we measured temperature, salinity, nitrate, chlorophyll-a and zooplankton at depths above 200 m from July $10^{th}$ to $25^{th}$, 2003. For comparative analysis, data of the physico-chemical properties and chl-a were matched to the two sampling depths (surface mixed layer and thermocline depth-200 m) of zooplankton. Latitudinal differences in the mesozooplankton distribution were mainly influenced by divergence formed at a boundary line formed by currents of opposing directions, consisting of North Equatorial Current (NEC) and North Equatorial Counter Current (NECC). High concentrations of chl-a south of $9^{\circ}N$, caused by equatorial upwelling related nutrients, is thought to be affected by the role of this divergence barrier, supported by relatively low concentrations in waters north of $9^{\circ}N$. The latitudinal differences of the chl-a were significantly associated with the major groups of zooplankton, namely calanoid and cyclopoid copepods, appendicularians, ostracods, chaetognaths, invertebrate larvae, and others. And temperature significantly affected the latitudinal variation of radiolarians, siphonophores, salps and immature copepods. The latitudinal differences in the two factors, temperature and chl-a, which explained 71.0% of the total zooplankton variation, were characterized by the equatorial upwelling as well as the divergence at $9^{\circ}N$. The physical characteristics also affected the community structure and abundance of zooplankton as well as average ratios of cyclopoid versus calanoid copepods. The abundance of dominant copepods, which were consistent with chl-a, were often associated with the carnivorous zooplankton chaetognaths, implying the relative importance of bottom-up regulation from physical properties to predatory zooplankton during the study period. These results suggested that latitudinal distribution of zooplankton is primarily controlled by current-related divergences, while biological processes are of secondary importance in the northeastern Equatorial Pacific during the study period in question.

• The Journal of the Korea Contents Association
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• v.14 no.6
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• pp.428-441
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• 2014

The Han river flowing the southern boundary of Hangyang city wall was known for scenic remote villa spot. This research is about a study on the historical and cultural landscape value of Apgujung built on hills of the Han river by Han Myeong Hoe in the mid-15th century. The results are as follows. First, the Han river has been a cultural poetical place. Second, the pavilion of west river was built as thatched roof at 1454-1456, while that of east river was erected as grand villa at 1469-1473. Third, there are characteristics of periodical landscape and origin was included on historical and cultural landscape, therefore, Apgujuing-dong has been recognized with the story. Han river where Apgujung was built has beautiful water landscape in spite of the landscape of modem downtown. Fourth, there are placeness and Han river of main landscape text streams nearby Apgujung site. Historical and cultural landscape of Apgujung should be changed, but, the landscape value could be progressed with the application as cultural contents while the Han river flows. It could be cultivated on the application of various culture contents and story of Apgujung when the historical landscape of water system be restored in Han river.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.2
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• pp.161-170
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• 1997

The concentrations of dimethylsulfide (DMS) were determined using samples collected from a station located at Kosan, Cheju Island during two field campaigns held in December 1996 and January 1997. The atmospheric DMS concentrations measured at 6-hr intervals during the entire campaign periods, after excluding a few extreme values, spanned in the range of 14 to 410 pptv with mean and 1 SD value of 127 $\pm$ 94 pptv (N=42). Between two month periods during which the field campaigns were conducted, a notable reduction in DMS levels was observed which was comparable to the dramatic shift in air temperature. A considerable difference was also noted in DMS levels, when data were grouped by day/night basis. The cause of unexpected, high day-to-night DMS ratios is best explained in terms of high efficiency of daytime source processes relative to low efficiency of nighttime sink processes due to the characteristics of the study location. The surface water DMS of the study site, although scarcely measured, also behaved similarly to its atmospheric counterpart with its range from 0.3 to 19 nM (N=11). When correlation analysis was conducted between the atmospheric DMS concentration and other concurrently determined parameters, significant correlations were observed from most basic meteorological parameters such as windspeed, relative humidy, and air temperature. However, the existence of "not-so-strong" correlations between air temperature and DMS concentrations relative to other ones indicated that the effect of temperature on DMS behavior must be reflected in more complicated manners at the study site. The sea-to-air flux of DMS was approximated through an application of the mass-balance flux calculation method of Wylie and de Mora (1996) under the assumption that sink mechanism within the marine boundary layer is in steady-state condition with its counterpart, source mechanism. Based on this estimation method, we reached a conclusion that oceanic DMS emitted from the southwest sea of the Korean Peninsula can amount to approximately 9 $\sim$ 36 Gg S $yr^{-1}$.$yr^{-1}$.

• Journal of Biomedical Engineering Research
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• v.33 no.4
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• pp.169-176
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• 2012

Tumor cell morphology is closely related to its migratory behaviors. An active tumor cell has a highly irregular shape, whereas a spherical cell is inactive. Thus, quantitative analysis of cell features is crucial to determine tumor malignancy or to test the efficacy of anticancer treatment. We use 3D time-lapse phase-contrast microscopy to analyze single cell morphology because it enables to observe long-term activity of living cells without photobleaching and phototoxicity, which is common in other fluorescence-labeled microscopy. Despite this advantage, there are image-level drawbacks to phase-contrast microscopy, such as local light effect and contrast interference ring. Therefore, we first corrected for non-uniform illumination artifacts and then we use intensity distribution information to detect cell boundary. In phase contrast microscopy image, cell is normally appeared as dark region surrounded by bright halo ring. Due to halo artifact is minimal around the cell body and has non-symmetric diffusion pattern, we calculate cross sectional plane which intersects center of each cell and orthogonal to first principal axis. Then, we extract dark cell region by analyzing intensity profile curve considering local bright peak as halo area. Finally, we calculated the Fourier descriptor that morphological characteristics of cell to classify tumor cells into active and inactive groups. We validated classification accuracy by comparing our findings with manually obtained results.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.44-50
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• 2010

This study is devoted to understand the basic characteristics of the flowfield around a train in evacuated tube and to suggest an efficient numerical method to calculate the flowfield. To get steady-state solution in minimum calculation domain, various boundary condition have been tried for steady calculation and have been compared to the solution of unsteady calculation. At the train velocity of 300km/h, the aerodynamic drag results of both calculation method agreed very well. The drag ratio between on the open filed and in the tube from the calculation result by the suggested numerical method lied in the same fitting curve with that from the filed test of high-speed trains running in the line.

• Tunnel and Underground Space
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• v.12 no.4
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• pp.312-320
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• 2002

It is well-known that when single rock fractures undergo shear displacement, they are influenced by the boundary conditions and fracture roughness. In this case, aperture geometry will change by means of dilation due to the shear displacement. As fractures become the flow paths, fluid flow through rock fractures is affected by the void geometry. In this study, therefore, the influence of roughness on shear behavior of fractures has been investigated, and the resulting hydraulic behavior has been analyzed. In order for this study, a statistical method has been used to generate rough fractures, and they have been adopted into new conceptual models fur fracture shearing and flow calculations. The main contributions of this study are as follows: firstly, fracture shear behavior becomes less brittle with decreasing fracture roughness and increasing normal stress. Then, the characteristics of aperture distribution becomes those of roughness of fractures indicating its hydraulic significance. Finally, it is observed that with decreasing fracture roughness the breakdown of channel flow occurs more slowly.

• Nuclear Engineering and Technology
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• v.41 no.8
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• pp.1025-1044
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• 2009

Systematic research has been conducted by KAERI to develop a supercritical carbon dioxide Brayton cycle energy conversion system coupled with a sodium cooled fast reactor. For the development of the supercritical $CO_2$ Brayton cycle ECS, KAERI researched four major fields, separately. For the system development, computer codes were developed to design and analyze the supercritical $CO_2$ Brayton cycle ECS coupled with the KALIMER-600. Computer codes were developed to design and analyze the performance of the major components such as the turbomachinery and the high compactness PCHE heat exchanger. Three dimensional flow analysis was conducted to evaluate their performance. A new configuration for a PCHE heat exchanger was developed by using flow analysis, which showed a very small pressure loss compared with a previous PCHE while maintaining its heat transfer rate. Transient characteristics for the supercritical $CO_2$ Brayton cycle coupled with KALIMER-600 were also analyzed using the developed computer codes. A Na-$CO_2$ pressure boundary failure accident was analyzed with a computer code that included a developed model for the Na-$CO_2$ chemical reaction phenomena. The MMS-LMR code was developed to analyze the system transient and control logic. On the basis of the code, the system behavior was analyzed when a turbine load was changed. This paper contains the current research overview of the supercritical $CO_2$ Brayton cycle coupled to the KALIMER-600 as an alternative energy conversion system.

• Journal of Korea Water Resources Association
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• v.48 no.8
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• pp.625-634
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• 2015

The diverse patterns of separation zone according to the marked bed discordance by dredging at confluence in addition to the confluence angle of tributary and discharge ratio between tributary and main channels have been analyzed by CCHE2D model simulation. The separation zone is defined by inside of zero velocity boundary at down-stream of confluence. The separation zone dose not formed at the $30^{\circ}$ of confluence angle of tributary. The size of separation zone increases as the discharge ratio and confluence angle increase in general. The separation zone decreases as the dredging depth increases which shows the relative momentum reduction compared by the flow volume increasing by dredging at confluence. The contraction factor with the variation of confluence angle and discharge ratio has been investigated and confirmed the corresponding conveyance decreasing results in backwater effect. The regression equation of shape factor with confluence angle and discharge and dredging depth ratios has been suggested.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.147-154
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• 2010

In this study, flood control effects for infiltration trench which is one of runoff reduction facilities were analyzed based on hydraulic experiments. Hydraulic experiments were conducted using 25 cm diameter circular pipe, and water depths for boundary conditions are 5, 10, 15, 20, 25 cm. Infiltration volume, runoff volume, runoff initiation time, final infiltration capacity and final infiltration capacity reached time etc. were measured from infiltration trench hydraulic experiment. We assumed that drainage area of each infiltration trench is $130\;m^2$ ($6.5\;m{\times}20\;m$) and calculated CN with area based on those experimental characteristics. In AMC-I condition, the calculated CN with five water depths is 84 for 2% pipe slope, 83 for 5% pipe slope. In AMC-III condition, the calculated CN is 84 for 2% and 5% pipe slope.

• Korean Journal of Materials Research
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• v.5 no.1
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• pp.3-11
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• 1995

$(TiO_{2})$ thin films were deposited on p-Si(100) substrate by APMOCVD using titanium isopropoxide as a source material. The deposition mechanism was well explained by the simple boundary layer theory and the apparent activation energy of the chemical reaction controlled process was 18.2kcal /mol. The asdeposited films were polycrystalline anatase phase and were transformed into rutile phase after postannealing. The postannealing time and the film thikness as well as the postannealing temperature also affected the phase transition. The C-V plot exhibited typical charateristics of MOS diode, from which the dielectric constant of about 80 was obtained. The capacitance of the annealed film was decreased but those of the Nb or Sr doped films were not changed. I-V characteristics revealed that the conduction mechanism was hopping conduction. The postannealing and the doping of Nb or Sr cause to decrease the leakage current and to increase the breakdown voltage.