• Journal of Climate Change Research
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• v.7 no.4
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• pp.433-442
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• 2016

In this study, we examine future changes in surface radiation associated with cloud amount and aerosol emission over East Asia. Data in this study is HadGEM2-CC (Hadley Centre Global Environmental Model version 2, Carbon Cycle) simulations of the Representative Concentration Pathways (RCPs) 2.6/4.5/8.5. Results show that temperature and precipitation increase with rising of the atmosphere $CO_2$. At the end of $21^{st}$ century (2070~2099) relative to the end of $20^{st}$ century (1981~2005), changes in temperature and precipitation rate are expected to increase by $+1.85^{\circ}C/+6.6%$ for RCP2.6, $+3.09^{\circ}C/+8.5%$ for RCP4.5, $+5.49^{\circ}C/10%$ for RCP8.5. The warming results from increasing Net Down Surface Long Wave Radiation Flux (LW) and Net Down Surface Short Wave Radiation Flux (SW) as well. SW change increases mainly from reduced total Aerosol Optical Depth (AOD) and low-level cloud amount. LW change is associated with increasing of atmospheric $CO_2$ and total cloud amount, since increasing cloud amounts are related to absorb LW radiation and remit the energy toward the surface. The enhancement of precipitation is attributed by increasing of high-level cloud amount. Such climate conditions are favorable for vegetation growth and extension. Expansion of C3 grass and shrub is distinct over East Asia, inducing large latent heat flux increment.

• Journal of the Korean earth science society
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• v.25 no.7
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• pp.629-636
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• 2004

In order to study developments of the marine atmosphere boundary layer in cloud incoming, important parameters like heat advection, surface layer heat flux, and radiation energy were estimated using the rawinsonde, AWS data, satellite images, and buoy data which was installed at the East Sea. We explained the variation and the development of mixed layer in terms of surface layer heat flux and long wave radiation under the cloudy sky. The heat flux was obtained by means of the bulk method. Conservation of heat was analysed by heat budget equation, which was consist of buoy data in the East sea, and sounding data at Ulleungdo and at Pohang. During the inflow of cloud, radiative cooling at the surface after was suppressed and long wave radiation from cloud played a role of warming. The surface layer temperature was also remained warm by influence of warm advection from south-easterly direction. The air temperature in night was increased, as a result, mixed layer was not destroyed and The nocturnal boundary layer was composed of the mixed layer and the residual layer.

• The Journal of the Acoustical Society of Korea
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• v.28 no.1E
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• pp.1-8
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• 2009

Primary radiation force on ultrasound contrast agents (UCA) in a propagating and standing acoustic field was explored. A specific ultrasound contrast agent $Albunex^{(R)}$ and $Optison^{(R)}$ were chosen for simulation. The model was developed based on a shelled bubble model proposed by Church. The numerical simulation suggests that bubble translational motion is more significant in therapeutic ultrasound due to higher intensity and long pulse duration. Even a single cycle of a propagating wave of 4 MPa at 1 MHz can cause a bubble translational motion of greater than $1{\mu}m$ which is approximately one tenth of capillary. Hence, UCA characteristics can be significantly changed in therapeutic ultrasound without rapid bubble collapses.

• Journal of Ocean Engineering and Technology
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• v.30 no.6
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• pp.440-450
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• 2016

The capsizing and consequent sinking of a coastal car ferry was recently reported, with numerous human casualties. The primary cause was determined to be a sudden turn with improperly stowed and secured cargo. Part I of this study introduces how long term acceleration components are determined from seakeeping analyses. A carferry with a displacement of 1,633 tonf was selected as the target vessel. Sea data that included the significant wave heights and periods were collected at four observation buoys, some of which were far away from two main voyage routes: Incheon-Jeju and Pusan-Jeju. Frequency response analyses were performed to obtain the linearized radiation force coefficients, hydrostatic stiffnesses, and wave excitation forces. Time response analyses were sequentially performed to produce the motion-induced acceleration processes. The probabilistic distributions of the acceleration components were determined using a peak and valley counting method. Long term extreme acceleration components were proposed as a final result.

• Journal of Environmental Science International
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• v.25 no.8
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• pp.1057-1063
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• 2016

The heat budget is investigated in the Gumi Reservoir of the Nakdong river. In warm climate season, solar radiation effects play a important role in the change of water temperature. The features of the surface heat balance are almost derived by the latent heat flux and the solar radiation flux. On the other hand, in cold climate season, change of heat stored in the water is mainly dominated by latent and sensible heat transfer between water and air, since flux of solar radiation and loss of outgoing long wave radiation balance approximately. For the annual averages, net flux of radiation, evaporation(latent heat) loss are dominant in the Gumi reservoir. The evaporation losses are dominant from spring to early winter. This means that the Gumi reservoir rolls like a lake of thermal medium or deep depth.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.40-45
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• 2019

Unlike the welded pipes in the primary system of light water nuclear power plants being periodically inspected with in-Service inspection program, relatively small pipes with the outer diameter less than 2 inch have not been regularly inspected to date. However, after several failure reports on the occurrence of critical crack-like defects in small pipes, inspection for the small pipes has been more demanded because it could cause the provisional outage of nuclear power plants. Nevertheless, there's no particular method to examine the small pipes having access limitations for inspection due to various reasons; inaccessible area, excessive radiation exposure, hazardous surrounding, and etc. This study is to develop a reliable inspection technique using torsional and flexural modes of guided wave to detect defects that could occur in inaccessible area. The attribute of guided wave that can travel a long distance enables to inspect even isolated range of the pipe from accessible location. This paper presents a case study of the evaluation test on 3/4" small-bore pipes with guide wave method. The test result demonstrates the crack signal behavior and assures possibility to detect the crack signal in a flexural mode, which is clearly distinguishable from the symmetric structure signal in a torsional mode.

• Journal of Environmental Science International
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• v.15 no.7
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• pp.653-657
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• 2006

Based on the monthly weather report of Korea Meteorological Administration (KMA) and daily sea surface temperature (SST) data from National Fisheries Research and Development Institute (NFRDI) (1995-2004), mean heat fluxes were estimated at the port of Yeosu. Net heat flux was transported from the air to the sea surface during February to September, and it amounts to $205 Wm^{-2}$ in daily average value in May. During October to January, the transfer of net heat flux was conversed from the sea surface to the air with $-70 Wm^{-2}$ in minimum of daily average value in December. Short wave radiation was ranged from $167 Wm^{-2}$ in December to $300 Wm^{-2}$ in April. Long wave radiation (Sensible heat) was ranged from $27 (-14) Wm^{-2}$ in July to $90 (79) Wm^{-2}$ in December. Latent heat showed $42 Wm^{-2}$ with its minimum in July and $104 Wm^{-2}$ with its maximum in October in daily average value.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.1
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• pp.123-132
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• 1999

One of the major difficulties in the seismic analysis of a dam-reservoir system is the treatment of the energy radiation in the upstream direction of the reservoir. In the paper, a new transmitting boundary is presented that can model properly the radiation of energy in the far field direction of a semi-infinite reservoir with constant depth. In the newly developed method, effects of surface wave motion are taken into accounted and the reservoir-foundation interaction is approximately accounted for with an absorbing boundary condition. If a dam has vertical upstream face and the infinitely long reservoir maintains constant depth, then the proposed transmitting boundary can be directly coupled with the model of dam body. In present study, the dam body is assumed to behave elastically and modeled by finite element method. Seismic responses of a dam model are investigated using the newly developed transmitting boundary.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.2 s.115
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• pp.18-25
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• 2006

This study aims to measure and to analyze the thermal environment characteristics of the various permeable pavement materials such as grass pavement (GREEN BLOCK PARK), stone and grass pavement (GREEN BLOCK STEP), stone pavement (GREEN BLOCK MOSAIC) and wood pavement (WOOD BLOCK) under the summer outdoor environment. The thermal environment characteristics measured in the study includes the changes of surface temperature during the day, changes of the temperature on each pavement layer, and long and short wave radiation of each pavement surface. The experimental condition is based on the data on the hottest temperature (August 5, 2005, $34.0^{\circ}C$) of the you. Some of main findings are: 1) The heat environment was worse on the wood pavements than on the stone pavement. This is mainly due to the low albedo of the wood pavements (0.37) while the albedo value of stone pavements is 0.41. Small heat capacity of the wood pavements also contributes to this difference. 2) The heat environment was worse on the stone pavements than on the turf pavements. This was mainly due to the evapotranspiration of the plant growth layer of the turf pavements. 3) The peak surface temperature was the highest on the wood pavements ($56.1^{\circ}C$). The peak surface temperatures on the stone pavements, the stone-grass pavements and the grass pavements were $43.1^{\circ}C,\;40.1^{\circ}C\;and\;37.9^{\circ}C$, respectively. 4) To improve the thermal environments in the urban area, it is recommended to raise the albedo of the pavements by brightening the surface color of the pavement materials. Further studies on the pavement materials and the construction methods which can enhance the continuous evapotranspiration from the pavements surface are needed.

• Journal of Environmental Science International
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• v.4 no.3
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• pp.197-206
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• 1995

Surface heat balance of the northern sea of Cheju Island for summer in 1993 and 1994 is analyzed using the observation data obtained by Marine Research Institute, Cheju National University. Each flux elements at the sea surface is derived from the marine meteorological reports with application of an aerodynamical bulk method for the turbulent heat fluxes, and empirical formulae for the long-wave radiation heat fluxes. The flux divergence of oceanic heat transport and the rate of heat storage in the ocean are estimated as residual. The features of the surface heat balance are mainly decided by the solar radiation flux and the latent heat flux for 199B. But the Bowen Ratios were large for 1993. This means that the sensible heat fluxes were nearly equal to the latent heat fluxes for 1993. In this period, mean flux divergence of oceanic heat transport is about 130 W/$m^2$.