• Particle and aerosol research
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• v.17 no.3
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• pp.55-69
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• 2021

Chungnam region accounts for the largest SO_X (22.8%) emission with the second-largest NO_X (10.8%) emission in Korea due to the integration of many large industrial sources including a steel mill, coal-fired power plants, and petrochemical complex. Air pollutants emitted by large industrial sources can cause harmful problems to humans and the environment. Thus, it is necessary to understand dispersion patterns of air pollutants from large industrial sources in Chungnam to characterize atmospheric contamination in Chungnam and the surrounding area. In this study, seasonal atmospheric dispersion characteristics for SO_X, NO_X, and PM2.5 from ten major point sources in Chungnam were evaluated using HYSPLIT 4 model, and their contributions to SO₂, NO₂ concentrations in the regions near the source areas were estimated. The predictions of the HYSPLIT 4 model show a seasonal different dispersion pattern, in which air pollutants were dispersed toward the southeast in winter while, northeast in summer. In summer, due to weaker wind speed, air pollutants concentrations were higher than in winter, and they were dispersed to the metropolitan area. The local emissions of air pollutants in Taean area had a greater influence on the ambient SO₂ and NO₂ concentrations at Taean, whereas SO_X and NO_X emissions from large sources located at Seosan showed relatevely little effect on the ambient ambient SO₂ and NO₂ concentrations at Seosan.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.1
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• pp.107-115
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• 1993

This study was carried out to find the characteristics of surface ozone concentration data obtained during 1988-1991 by the Korea Ministry of Environment. Seasonal data (spring, summer, autumn and winter) wre obtained in May, August, November and February respectively at Kwanghwamun in Seoul. The pollutants analyzed in this study are $SO_2, TSP, CO, NO, NO_2 and NO_2/NO$. Atmospheric factors such as solar radiation, wind speed, relative humidity, cloud amount and atmospheric temperature are also analyzed. The influence of pollutants and atmospheric factors that affect ozone concentration were analyzed by statistical method. The results are summarized as follows : 1. The ozone concentration varied seasonally. The maximum values were 23 ppb in spring, 33 ppb in summer, 16 ppb in autumn and 13 ppb in winter. So the seasonal ozone value was highest in Summer. 2. Te diurnal concentration of ozone was highest during 2-4 P. M. and was very low in the morning and evening. 3. The maximal correlation coefficients of each season between ozone concentration and the influencing pollutants or atmospheric factors asr as follows ; a. spring, r = 0.44(solar radiation) b. summer, r = -0.59(relative humidity) c. autumn, r = -0.55(relative humidity) d. winter, r = -0.58($NO_2$) 4. The major factor affecting the ozone concentration in spring was solar radiation, Relative humidity was the first affecting factor in summer, autumn and $NO_2$ concentration was dominant in winter.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.165-171
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• 2005

When typhoon approaches, ship normally drops her anchor at proper anchorage for sheltering. If an anchoring ship is under the influence of typhoon, she can keep her position when the external force and counter force is balanced. Where, external force is induced by wind, wave and tidal currents while counter force is induced by holding power of anchor/chain and thrust force of main engine. In this study, authors presented a method to analyze theoretically the limit of external force for the ship to keep her position without being dragged and, to check the validity of method, applied this to the ship which had been anchored in Jinhae Bay when the typhoon MAEMI passed on September 2003.

• Korean Journal of Environment and Ecology
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• v.26 no.6
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• pp.876-883
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• 2012

In order to analyze the meteorological factors influencing breeding activities of the Kaloula borealis, spawning sites which are located in Daejung-Eub, Jeju Island were investigated for 4 years from 2008 to 2011. The factors for analysis were rainfall, humidity, temperature, barometric pressure and wind speed. Comparative analysis were done on the spawning activities on rainy days. The analysis shows that the main factors influencing breeding activities of the Kaloula borealis are rainfall, humidity, and barometric pressure. The most influencing factor among them is rainfall. According to the analysis, the Kaloula borealis participate in spawning activities when it rains hard and humidity and barometric pressure also have influence on their spawning activities to a certain degree. As for temperature, the breeding season is summer so it meets one of the conditions for breeding activities. As a result, like the previous studies on other anurans in temperate regions, rainfall and temperature have a great impact on breeding activities of the Kaloula borealis.

• Atmosphere
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• v.28 no.4
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• pp.457-467
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• 2018

This study investigated the variability of spring (March-May) forest fire risk in Korea for the period 1991~2017 and analyzed its relationship with large-scale climate factors. The Forest Weather Index (FWI) representing the meteorological risk for forest fire occurrences calculated based on observational data and its relationship with large-scale climate factors were analyzed. We performed the empirical orthogonal function (EOF) analysis on the spring FWI. The leading EOF mode of FWI accounting for about 70% of total variability was found to be highly correlated with total number of forest fire occurrences in Korea. The high FWI, forest fire occurrence risk, in Korea, is associated with warmer atmosphere temperature in midwest Eurasia-China-Korea peninsula, cyclonic circulation anomaly in northeastern China-Korea peninsula-northwest pacific, westerly wind anomaly in central China-Korea peninsula, and low humidity in Korea. These are further related with warmer sea surface temperature and enhanced outgoing longwave radiation over Western Pacific, which represents a typical condition for a La $Ni\tilde{n}a$ episode. This suggests that large-scale climate factors over East Asia and ENSO could have a significant influence on the occurrence of spring forest fires in Korea.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.357-363
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• 2005

When typhoon approaches, ship normally drops her anchor at proper anchorage for sheltering. If an anchored ship is under the influence of typhoon, she can keep her position when the external force and counter force is balanced. Where, external force is induced by wind, wave and tidal currents while counter force is induced by holding power of anchor/chain and thrust force of main engine. In this study, authors presented a method to analyze theoretically the limit of external force for the ship to keep her position without being dragged and, to check the validity of the method, applied this to the ship which had been anchored in Jinhae Bay when the typhoon MAEMI passed on September 2003.

• Fire Science and Engineering
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• v.24 no.4
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• pp.109-115
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• 2010

Maximum pressure difference in central core type 80th super_tall buildings was estimated as 75 Pa during no outside wind due to the winter stack effect. Maximum pressure difference of 225 Pa can be obtained depending on the location of air injection fan during the stairway pressurization at fire. Bottom_only air injection system provided the best results in the sense of required air flow rates and pressure distributions. Top_only air supply system was estimated as the worst for this country. It revealed that the decrease of the temperature in the stairway due to the cold outside air injection reduced the required flow rates of the fan and significantly changed the distribution of pressure differences.

• Journal of Ecology and Environment
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• v.41 no.10
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• pp.290-301
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• 2017

Background: Forest edges create distinctive ecological space as adjacent constituents, which distinguish between different ecosystems or land use types. These edges are made by anthropogenic or natural disturbance and affects both abiotic and biotic factors gradually. This study was carried out to assess edge effects on disturbed landscape at the pine-dominated clear-cut area in a genetic resources reserve in Uljin-gun, eastern Korea. This study aims to estimate the distance of edge influence by analyzing changes of abiotic and biotic factors along the distance from forest edge. Further, we recommend forest management strategy for sustaining healthy forest landscapes by reducing effects of deforestation. Results: Distance of edge effect based on the abiotic factors varied from 8.2 to 33.0 m. The distances were the longest in $Mg^{2+}$ content and total nitrogen, $K^+$, $Ca^{2+}$ contents, canopy openness, light intensity, air humidity, $Na^+$ content, and soil temperature followed. The result based on biotic factors varied from 6.8 to 29.5 m, coverage of tree species in the herb layer showed the longest distance and coverage of shrub plant in the herb layer, evenness, species diversity, total coverage of herb layer, and species richness followed. As the result of calculation of edge effect by synthesizing 26 factors measured in this study, the effect was shown from 11.0 m of the forest interior to 22.4 m of the open space. In the result of stand ordination, Rhododendron mucronulatum, R. schlippenbachii, and Fraxinus sieboldiana dominated arrangement of forest interior sites and Quercus mongolica, Vitis amurensis, and Rubus crataegifolius dominated spatial distribution of the open area plots. Conclusions: Forest interior habitat lies within the influence of both abiotic and biotic edge effects. Therefore, we need a forest management strategy to sustain the stability of the plant and further animal communities that depend on its stable conditions. For protecting forest interior, we recommend selective logging as a harvesting method for minimizing edge effects by anthropogenic disturbance. In fact, it was known that selective logging contributes to control light availability and wind regime, which are key factors affecting microclimate. In addition, ecological restoration applying protective planting for the remaining forest in the clear-cut area could contribute to prevent continuous disturbance in forest interior.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.31-38
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• 2005

Aerodynamic influence coefficient linearly relates pressure with downwash in panel method for load analysis in which the viscosity of a flow is ignored and the compressibility cannot be taken into account in transonic region. Since the planform of an aerodynamic surface determines the coefficient, the panel method has a limit to the analysis of low Reynolds number flow. The accuracy of the pressure distribution can be improved by a direct correction to the pressure or a correction to the downwash, which is considered the change of camber or thickness, using the aerodynamic coefficients from wind tunnel test as constraints. A premultiplying correction method as well as a postmultiplying correction method is applied to a micro air vehicle to provide more accurate aerodynamic pressure for trim and load analyses. Theoretical aerodynamic pressure is obtained from the panel method. Correction factor matrix and correct pressure coefficient are computed for the conditions with two constraints in addition to single constraint. The postmultiplying correction method gives a better improvement in pressure distribution on micro air vehicle due to the flow characteristics on it.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.102-105
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• 2002

ADSS(All Dielectirc Self-Supporting) cable installed under high voltage power cable line suffers a variety of environmental influence, rain, wind, snow fall, chemical pollution, salt fog and electrical stress. Its lifetime is required to be at least 20 years with this harsh weathering condition. The electrical stress under high voltage power line gives rise to dry band arcing and tracking, the severest damage, on the outer sheath of cable. Finally tracking might penetrate sheath and cause the break-down of ADSS cable. Tracking resistant sheath material, therefore, should be used to protect the core of ADSS from dry band arcing and to be sure long lifetime. In this work, we discuss various commercial tracking resistant material to investigate the way of track resistance and compare their mechanical, electrical, weathering and tracking properties through serial experiments. We found track resistant material is categorized into two main type : polyethylene with metal hydroxide and polyethylene with reduced carbon black. The Liquid contaminant, Inclined plane Tracking and Erosion test says the time to track of tracking resistant material with metal hydroxide has a little longer time to track in the high applied voltage than that with carbon black, but mechanical and weathering properties were inferior to.