• Journal of Korean Society for Atmospheric Environment
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• v.27 no.1
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• pp.73-86
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• 2011

Haze phenomena were analyzed to assess the impact of long range transport process on the air quality of Seoul and Busan. We statistically classified haze days observed in both Seoul and Busan into two types of haze cases: stagnant case and long-range transport case, and analyzed the air pollutant levels comparatively for each of the two cases for the period of 2000~2007. The results showed that the long-range transport haze case occurs less frequently with the occurrence frequency of 35.5% than stagnant case with the occurrence frequency of 64.5%. During the observed all haze days, all pollutants have high concentration in comparison with those under other meteorological conditions (Rain, Mist, Dust, Clear, Rain+Mist) except for only $PM_{10}$ of Dust case where its level shows highest among total 6 categorized conditions. The long range transport haze case shows similar levels of $PM_{10}$ and $NO_2$, but higher $SO_2$ and lower $O_3$ compared with stagnant haze cases, suggesting the importance of sulfur chemistry for long range transport haze case and local photochemistry for stagnant haze case. In addition, by employing the NOAA/HYSPLIT-4 backward trajectory model, we subdivided the long range transport haze cases into two different sources: urban anthropogenic high emission areas of central China, and natural emission sources over north China and/or Mongolia. The former long range transport haze case shows higher occurrence (with Seoul 70% and Busan 85%) than the latter haze case (with Seoul 30% and Busan <10%). This is also implying that the long haze phenomena occurred over Korea have been influenced by not only the anthropogenic emissions but also the natural dust emissions. These both emission sources can be good contributors in calculating the source-receptor relationship over Korean atmospheric environment.

• Fashion & Textile Research Journal
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• v.17 no.3
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• pp.351-363
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• 2015

This research explores diachronic fashion design trends through a structure analysis of a connection network based on fashion show concepts implemented by modern fashion designers from S/S 2009 to F/W 2013. The findings from this research are as follows. First, four categories affect the inspiration and thinking of design: the experience of the designer, social atmosphere and phenomena, natural sensitivity (or formative characteristics of natural objects), and the influence and quality of other fields. Second, in cases where the designers' experiences influenced design inspiration and thinking, designers express personal memories with keywords like high school, grandmother's closet, prom, beauty and the beast, heritage, past, and reminiscence through design elements such as lines, silhouettes, materials, and colors. Third, the representative example of the social atmosphere and phenomena that influenced design inspiration and thinking was the 2008 Global Financial Crisis that reflected the social climate through design concepts of keywords such as Recession, Black, Economy, US, Depression, Gray, Dark Age, White and New York. Fourth, inspired by nature and the formative characteristics in design, the designers employed ornamental elements to collections and design concepts that focused on nature words connected to light, sun, wild, dirt, rock, moss, and trees. Fifth, the designers took their ideas from different fields of personal interest in the arts, science and humanities (sports, architecture, sculpture, painting, and literature) that were decisive in determining materials, design colors and silhouettes. The theme of architecture was analyzed as a central element that had an ongoing impact on the concepts of designers.

• Ocean and Polar Research
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• v.31 no.1
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• pp.111-119
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• 2009

Biogenic surface films, which are often present in coastal areas, may enhance the signatures of hydrodynamic processes in microwave, optical, and infrared imagery. We analyzed ERS-1/2 Synthetic Aperture Radar (SAR) and Envisat Advanced Synthetic Aperture Radar (ASAR) images taken over the Japan/East Sea (JES). We focused on the appearance of the contrast SAR signatures, particularly the dark features of different scales caused by various oceanic and atmospheric phenomena. Spiral eddies of different scales were detected through surface film patterns both near the coast and in the open regions of the JES in warm and cold seasons. During field experiments carried out at the Pacific Oceanological Institute (POI) Marine Station 'Cape Shults' in Peter the Great Bay, the sea surface roughness characteristics were measured during the day and night using a developed polarization spectrophotometer and various digital cameras and systems of floats. The velocity of natural and artificial slicks was estimated using video and ADCP time series of tracers deployed on the sea surface. The slopes of gravity-capillary wave power spectra varied between .4 and .5. Surface currents in the natural and artificial slicks increased with the distance from the coast, varying between 4 and 40 cm/s. The contrast of biogenic and anthropogenic slicks detected on vertical and horizontal polarization images against the background varied over a wide range. SAR images and ancillary satellite and field data were processed and analyzed using specialized GIS for marine coastal areas.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.69-79
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• 2000

Fractal geometry has become one of prospective research approaches as the complex structure of natural entities is not easily characterized by traditional Euclidean geometry. With the fractal geometry, we can better decipher the complex structure and identify natural and anthropogenic agents of landscape patterns occurring at different spatial scales. The usefulness of fractal, however, has not been fully appreciated among Korean academic societies, especially in ecological and limnological fields. We attempt to address three points in this study. First, we introduce the concept and dimension of fractal and review relevant research approaches, especially with respect to ecological and limnological phenomena. Second, we explore possible applications of fractal to some aspects of geography and land use characteristics in South Korea. For the analyses of fractal dimensions, we used data published in other studies previously and collected for this study. Data were analyzed by a perimeter/area method of fractal dimension for the spatial distribution of global solar radiation and leaf area index, and the movement of wild boars in forested landscapes of mid-eastern Korea. The same approach was also applied to the water channel of a hypothetical river and the shape of reservoirs in Yongin, Kyunggi Province. Finally, we discuss the results and key issues to consider when a fractal approach is employed in ecology and limnology.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.4
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• pp.321-329
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• 2018

Resonance phenomena occurs at large vertical pump which is operating to cool down the hot steam using sea water in the power plant. To avoid the resonance, the natural frequency needs to be isolated about 20% from motor operating speed. Yet, excessive vibration occurs especially at low tide. At first, natural frequency of the whole pump system and each part is calculated using ANSYS. As it is revealed in the previous journal papers that only circular pipe part is related to resonance, the FSI technique is applied for free vibration analysis. The natural frequency is reduced to 60% (compared to that) of the frequency measured in air as it is similar to other published results. And the frequency obtained by finite element analysis is almost same to that obtained from modal test. Based on the accurate finite element model and analysis, design change is tried to avoid the resonance by changing the thickness of pipe and base supporting plate. In stead of doing optimization process, design sensitivity is computed and used to find such designs to avoid resonance.

• Journal of computational fluids engineering
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• v.21 no.2
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• pp.47-53
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• 2016

This study investigated natural convection flow behavior in airflow path designed in concrete dry storage cask to remove the decay heat from spent nuclear fuels. Using FLUENT 16.1 code, thermal analysis for natural convection was carried out for three dimensional, 1/4 symmetry model under the normal condition that inlet ducts are 100% open. The maximum temperatures on other components except the fuel regions were satisfied with allowable values suggested in nuclear regulation-1536. From velocity and temperature distributions along the flow direction, the flow behavior in horizontal duct of air inlet and outlet duct, annular flow-path and bent pipe was delineated in detail. Theses results will be used as the theoretical background for the composing of airflow path for the designing of passive heat removal system by understanding the flow phenomena in airflow path.

• Journal of Korea Water Resources Association
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• v.32 no.1
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• pp.61-70
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• 1999

The two-dimensional Random-Walk model in which fluid and pollutant particles are tracked using statistical concept was developed to simulate dispersion processes in natural streams. The calibration of the model shows that the error decreases as the number of grid increases, and/or the number of particles in each grid increases. The proposed model is tested against the dispersion data collected in the Grand River, Canada. The simulation results show that the 2-D Random-Walk model describes two-dimensional mixing phenomena occurred in the irregular meandering stream very accurately.

• Solar Energy
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• v.12 no.1
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• pp.48-58
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• 1992

In the present investigation, experimental analysis was performed to research heat transfer phenomena generated by means of conduction and natural convection at a succession of tube-inclimations relative to the vertical tube during inward melting process of a phase change material. The phase change material used in the experiments is 99 percent pure n-docosane paraffin($C_{22}H_{46}$). When the tube is vertical, the dominant mode of energy transfer between the tube wall and the melting interface is natural convection. On the other hand, when the tube is inclined to the vertical, the melting solid is brought into direct contact with the tube wall by the action of gravity. In the experimental results, direct contact gave rise to substantial enhancements in the amount of melted mass, relative to those for natural-convection-dominated melting.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2353-2364
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• 1995

The ignition phenomena of a solid fuel plate of polymethyl-methacrylate(PMMA), which is vertically positioned and exposed to a thermal radiation source, is numerically studied here. A two-dimensional transient model includes such various aspects as thermal decomposition of PMMA, gas phase radiation absorption, gas phase chemical reaction and air entrainment by natural convection. Whereas the previous studies considers the problem approximately in a one-dimensional form by neglecting the natural convection, the present model takes account of the two-dimensional effect of radiation and air entrainment. The inert heating of the solid fuel is also taken into consideration. Radiative heat transfer is incorporated by th Discrete Ordinates Method(DOM) with the absorption coefficient evaluated using gas species concentration. The thermal history of the solid fuel plate shows a good agreement compared with experimental results. Despite of induced natural convective flow that induces heat loss from the fuel surface, the locally absorbed radiant energy, which is converted to the internal energy, is found to play an important role in the onset of gas phase ignition. The ignition is considered to occur when the rate of variation of gas phase reaction rate reaches its maximum value. Once the ignition takes place, the flame propagates downward.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.157-164
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• 2008

A modeling and visualization system of flood inundation in natural river, FloodViz, has been developed. Unsteady river flow and flood inundation are calculated by FLDWAV model. FLDWAV model and HEC-RAS model have been applied to a flood event at the same time to check model reliability. Simulation results of the two models showed good agreements. Flood propagation and inundation process can be analyzed accurately and easily by using visualization function of the FloodViz. Even though FloodViz users don't know well about both hydraulics and hydrology, they can understand flood inundation phenomena easily. This system can be used as a useful tool in forecasting flood inundation and observing the simulation results. Countermeasures for natural disaster prevention due to flood inundation can be established rapidly by using the FloodViz.