• Journal of Astronomy and Space Sciences
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• v.22 no.2
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• pp.147-174
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• 2005

To understand the physical processes that control the high-latitude lower thermospheric dynamics, we quantify the forces that are mainly responsible for maintaining the high-latitude lower thermospheric wind system with the aid of the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEGCM). Momentum forcing is statistically analyzed in magnetic coordinates, and its behavior with respect to the magnitude and orientation of the interplanetary magnetic field (IMF) is further examined. By subtracting the values with zero IMF from those with non-zero IMF, we obtained the difference winds and forces in the high-latitude 1ower thermosphere(<180 km). They show a simple structure over the polar cap and auroral regions for positive($B_y$ > 0.8|$\overline{B}_z$ |) or negative($B_y$ < -0.8|$\overline{B}_z$|) IMF-$\overline{B}_y$ conditions, with maximum values appearing around -80$^{\circ}$ magnetic latitude. Difference winds and difference forces for negative and positive $\overline{B}_y$ have an opposite sign and similar strength each other. For positive($B_z$ > 0.3125|$\overline{B}_y$|) or negative($B_z$ < -0.3125|$\overline{B}_y$|) IMF-$\overline{B}_z$ conditions the difference winds and difference forces are noted to subauroral latitudes. Difference winds and difference forces for negative $\overline{B}_z$ have an opposite sign to positive $\overline{B}_z$ condition. Those for negative $\overline{B}_z$ are stronger than those for positive indicating that negative $\overline{B}_z$ has a stronger effect on the winds and momentum forces than does positive $\overline{B}_z$ At higher altitudes(>125 km) the primary forces that determine the variations of tile neutral winds are the pressure gradient, Coriolis and rotational Pedersen ion drag forces; however, at various locations and times significant contributions can be made by the horizontal advection force. On the other hand, at lower altitudes(108-125 km) the pressure gradient, Coriolis and non-rotational Hall ion drag forces determine the variations of the neutral winds. At lower altitudes(<108 km) it tends to generate a geostrophic motion with the balance between the pressure gradient and Coriolis forces. The northward component of IMF By-dependent average momentum forces act more significantly on the neutral motion except for the ion drag. At lower altitudes(108-425 km) for negative IMF-$\overline{B}_y$ condition the ion drag force tends to generate a warm clockwise circulation with downward vertical motion associated with the adiabatic compress heating in the polar cap region. For positive IMF-$\overline{B}_y$ condition it tends to generate a cold anticlockwise circulation with upward vertical motion associated with the adiabatic expansion cooling in the polar cap region. For negative IMF-$\overline{B}_z$ the ion drag force tends to generate a cold anticlockwise circulation with upward vertical motion in the dawn sector. For positive IMF-$\overline{B}_z$ it tends to generate a warm clockwise circulation with downward vertical motion in the dawn sector.

• Nuclear Engineering and Technology
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• v.25 no.3
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• pp.470-479
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• 1993

노심설계의 검증을 통하여 설계의 신뢰성이 확인되며 이는 발전소 운전의 안전성과 경제성을 향상시킬 수 있는 발판이 된다. 본 기고문은 국산핵연료가 장전되었던 영광 2호기 4주기의 운전자료 중에서 핵설계와 관련한 인자의 측정치를 설계치와 비교 분석하고 평가하였다. 비교대상이 된 핵 특성인자는 반응도 관련 자료인 임계붕소농도, 제어봉가, 등온온도계수 및 감속재온도계수 둥이고 출력분포 관련자료인 핵반응률 분포, 집합체 출력분포, 반경방향 첨두출력 F_ $\Delta$H/$^{N}$ , 축방향 출력분포, 축방향 첨두출력 Fq(z) 및 노심 평균 축방향 출력편차(AO)등이다. 이들 인자들에 대한 설계치는 측정치와 잘 일치하였으며, 모두 안전성 관련 제한치이내로 만족함을 확인하였다. 또한 운전자료의 비교 분석을 통하여 후속주기의 핵설계에 반영할 수 있는 근거를 마련하였다.

• The Korean Journal of Ecology
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• v.24 no.3
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• pp.149-156
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• 2001

Zostera caespitosa Miki has been identified to be distributed along the seacoasts of Korea and Japan. This study was intended to clarify the morphological characters and the habitat characteristics of Korean Z. caespitosa. It was confirmed that Z. caespitosa is distributed along the seacoasts of South, Yellow and East Seas of South Korea. The habitats were located in the bay and port with the depth varying from 2.5 to 5.2 m. The habitats of Z. caespitosa were rather deeper than that of mixed bed with Z. marina. The sediment in the habitats was composed of well-sorted fine sand or muddy sand. Z. caespitosa showed marked differences in several morphological characters among sites. Morphology of Z. caespitosa varied with water depths, grain size and organic contents of sediments. Flowering shoots occurred by water temperature of 6.0∼13.7℃ from January to early April.

• The Korean Journal of Ecology
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• v.5 no.4
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• pp.143-153
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• 1982

Distributional pattern of vascular plant species in terms of species-area relationship and distances from their species pool on the 53 islands selected in the South Korea were studied. From the relationship between vascular plant species and area the equation of species-area was established as the follow: S=cA2 c=135.52 z=0.226 S; number of species A; area of island In the equation the Z value 0.226 is lower than those of any other localities reported in the world. Z value increased with the increasing distance from the species pool while C value decreased. The relationships of Z and/or C and distance from species pool, D, were established; Z=0.002D+0.176 C=-39.5logD+178.5 The tendency of common species decrease of them with the increasing islands was fifted to the Fisher's logarithm series. Common species 50% above was 39 species, including the most common species, Pinus thunbergii. Quotient of Similarity value by Sorensen (1948) on common species was relatively low i.e. 0.27∼0.47. It is noticeable for their vegetation conditions that the naturalized plant as a indicator of disturbance, for example Erigeron canadensis, was widely distributed.

• Korean Journal of Remote Sensing
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• v.33 no.5_1
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• pp.469-480
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• 2017

This study aims to understand the relationship between lineaments and epicenters in Geochang region, Gyungsangnam-do, South Korea. An instrumental observation of earthquakes has been started by Korea Meteorological Administration (KMA) since 1978 and there were 6 earthquakes with magnitude ranging 2 to 2.5 in Geochang region from 1978 to 2016. Lineaments were extracted from LANDSAT 8 satellite image and shaded relief map displayed in 3-dimension using Digital Elevation Model (DEM). Then, lineament density was statistically examined by hotspot analysis. Hexagonal grids were generated to perform the analysis because hexagonal pattern expresses lineaments with less discontinuity than square girds, and the size of the grid was selected to minimize a variance of lineament density. Since hotspot analysis measures the extent of clustering with Z score, Z scores computed with lineaments' frequency ($L_f$), length ($L_d$), and intersection ($L_t$) were used to find lineament clusters in the density map. Furthermore, the Z scores were extracted from the epicenters and examined to see the relevance of each density elements to epicenters. As a result, 15 among 18 densities,recorded as 3 elements in 6 epicenters, were higher than 1.65 which is 95% of the standard normal distribution. This indicates that epicenters coincide with high density area. Especially, $L_f$ and $L_t$ had a significant relationship with epicenter, being located in upper 95% of the standard normal distribution, except for one epicenter in $L_t$. This study can be used to identify potential seismic zones by improving the accuracy of expressing lineaments' spatial distribution and analyzing relationship between lineament density and epicenter. However, additional studies in wider study area with more epicenters are recommended to promote the results.

• Atmosphere
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• v.25 no.2
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• pp.339-351
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• 2015

The purpose of this study is for the fundamental understandings about building morphological parameters and aerodynamic roughness parameters of Seoul, Korea using the detailed urban geographic information datasets. Applied roughness parameter calculations are based on a digital map of buildings with lot area polygons. The quality of the developed roughness length ($z_0$) of Seoul was evaluated with densely installed 107 automatic weather stations. The correlation coefficient results between averaged wind speeds of AWS data and averaged $z_0$ is -0.303 in night and -0.398 in day (200 m radii circles case). Further $z_0$ enhancement should follow by considering other surface features such as high tree and orography of Seoul. However, this study would meet the needs to for local- or meso-scale meteorological modeling applications of Seoul. However, further studies would require for enhancing the $z_0$ applications of Seoul.

• Asian Journal of Turfgrass Science
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• v.13 no.2
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• pp.113-124
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• 1999

This study was carried out to know the oviposition preference site of chestnut brown chafer ( CBC ), Adoretus tenuimaculatus and its temporal activity and spatial distribution in green. Larval distribution was also investigated in golf courses for the control of CBC. CBC collected from Yongwon Golf Club in Chinhae, Tongdo Golf Club in Yangsan, Gyeongsan Province, Daegu Golf Club in Gyeongsan, Kyeongbuk Province, Dongrae Golf Club laid more eggs on broableaf of Zoysia matrella than Z. japonica, broadleaf+middleleaf of Z. matrella, Poa pratensis, and P. annua. The number of CBC egg was $19.7\pm$6.7 in Z. japonica,$ 1.7\pm$1.5 in P. pratensis, $1.3\pm$1.5 in sandy loam and $5.7\pm$2.9 in sand. Acitivity time of CBC in a day was the peak at 20:00 and continued to 24:00. CBCs adults were more collected from outside of golf courses whichhad many host plants than roadside courses. Density of white grubs was significantly different in fairway only. CBCs were more collected at tee and fairway than green. Density of white grubs was $54.6\pm$100 in broadleaf of Z. matellia and $37.7\pm$33.8 in P. pratensis at the back tee of the 7th hole in Dongrae Golf Club.

• Journal of the Korean Wood Science and Technology
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• v.28 no.2
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• pp.3-9
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• 2000

This study concerns the distribution and dependence of moisture content(MC) in wood for same thickness in different vapor transmission conditions. The specimens were disks of 70-mm in diameter and 20-mm in thickness from quartersawn lumber of Korean red pine(Pinus densiflora S. et Z.). The experiments were conducted in ten different conditions on the difference of the vapor pressures by the JIS Z-0208. The distribution of moisture content in wood can be illustrated by two straight lines intersecting at the point of about ten percent Me. On the other hand, when more or less than about 10 percent, the distribution of the Me can be illustrated by one straight lines. Therefore, it is considered that the values of 10 percent Me has no relation to the wood and experimental conditions. It's assumed that 10 percent is the boundary point at which the moisture sorption energy changes. In a previous study, diffusion coefficient is almost constant with no relation to a thickness of the woods for the constant experimental conditions. But, in this study, it seems that diffusion coefficient from the moisture gradient vary with the Me of wood in different vapor transmission conditions.

• Journal of the Society of Disaster Information
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• v.17 no.2
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• pp.319-328
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• 2021

Purpose: Recently, a large social disaster has called for the need to diagnose social disaster safety, and the Ministry of Public Administration and Security calculates and publishes regional safety ratings such as regional safety index and national safety diagnosis every year. The existing safety diagnosis system uses equal intervals or normal distribution to grade risk maps in a uniform manner. Method: However, the equidistant technique can objectively analyze risk ratings, but there is a limit to classifying risk ratings when the distribution is skewed to one side, and the z-score technique has a problem of losing credibility if the population does not follow a normal distribution. Because the distribution of statistical data varies from indicator to indicator, the most appropriate rating should be applied for each data distribution. Result: Therefore, in this paper, we analyze the data of disaster indicators and present a comparison and suitable method for traditional equidistant and natural brake techniques to proceed with optimized grading for each indicator. Conclusion: As a result, three of the six new indicators were applied differently from conventional grading techniques

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.412-418
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• 2007

The dynamics of Zacco platypus population of upstream and downstream in the lake Hoengseong, Korea were investigated from April to October 2005. Length-weight relationship, condition factor (K) and relative condition factor $(K_n)$ of Z. platypus were compared by the study stations. The equations based on length-weight relationship in the lake Hoengseong were $Log(T_w)=-2.2s+3.18{\cdot}Log(T_L)\;(r^2=0.99)$. The result in comparison of variations of Z. platypus populations, in lake was more remain to better than in upstream and downstream them. Also the b value, assessed by Length-weight relationship in lake was 3.36, in upstream and downstream were 3.09, 3.15, respectively indicating the fish in lake better than stream. The slopes of population condition controlled by K factor also showed positive relationship. It was higher in lake environment than in stream sample, reflecting that population of Z. platypus distributed in lake Hoengseong was favorable and stable condition. The lake environment seems to be providing more favorable condition for Z. platypus population.