• Journal of the Korean GEO-environmental Society
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• v.2 no.3
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• pp.5-15
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• 2001

The purpose of this study is to find sedimentation patterns variation before and after the Saemangeum reclamation. Water circulations before and after the Saemangeum reclamation are calculated diagnostically and prognostically from the water temperature, salinity data, wind data and tidal residual current. Three dimensional movements of injected particles due to currents, turbulence and sinking velocity are tracked by the Euler-lagrange method. The dispersion range of soil grain for one and three day after releasing in the Geum river indicates that the soil grain was sedimented coastal area of Janghang and outer harbor of Kunsan. The soil grain moves a quite distance from the release point when size of soil grain is a small. These results indicate that size of soil grain and residual current is greatly influenced on the dispersion range of soil grain.

• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.315-323
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• 2023

Marine accidents due to loss of stability of small ships have continued to increase over the past decade. In particular, since sudden winds have been pointed out as main causes of most small ship accidents, safety measures have been established to prevent them. In this regard, to prevent accidents caused by sudden winds, a systematic analysis technique is required. The aim of the present study was to develop a probabilistic approach to estimate extreme value and evaluate effects of wind on motion characteristics of ships. The present study included studies of motion analysis, extraction of extreme values, and motion characteristics. A series analysis was conducted for three conditions: wave only, wave with uniform wind speed, and wave with the NPD wind model. Hysteresis filtering and Peak-Valley filtering techniques were applied to time-domain motion analysis results for extreme value extraction. Using extracted extreme values, the goodness of fit test was performed on four distribution functions to select the optimal distribution-function that best expressed extreme values. Motion characteristics of a fishing boat were evaluated for three periodic motion conditions (Heave, Roll, and Pitch) and results were compared. Numerical analysis was performed using a commercial solver, ANSYS-AQWA.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1041-1048
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• 2023

Wind LiDAR and Wind Profiler are devices that produce continuous vertical distribution of wind vector in high-resolution data, and their use has recently been increasing. Although the observation and data processing methods of the two devices are similar, differences in wind detection accuracy may occur depending on weather and operation settings. introduce the characteristics of the two instruments and wind calculation methods, and apply the latest instrument verification standards to evaluate their accuracy by comparing them with the wind observed with a radiosonde. Accordingly, a new direction for performance verification following the introduction of equipment and additional necessary complements are presented.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.4
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• pp.12-23
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• 2019

This study aims to suggest analysis schemes of urban forests acting as wind ventilation corridor(wind ventilation forest). For this purpose, wind corridor forests were classified into three types: wind-generating forests(WGF), wind-spreading forests (WSF), and wind-connecting forests(WCF), and they were classified into three grades. WGF, WSF and WCF were classified based on the density of forest type map, vegetation index, and ventilation networks, respectively. As a result of analyzing wind corridor forests for Daegu Metropolitan City(883.56㎢), the area of WGF was classified as 443.1㎢ and distributed in the northern and southern regions of Daegu Metropolitan City. Among them, the first grade of WGF occupied the largest area(345.59㎢) and the highest rate(54.44%) in Dalseong-gun. On the other hand, WGF was not found in Jung-gu, because this administrative district is isolated from the forest area. WSF was 32.4㎢, which included representative urban parks of Daegu Metropolitan City, and WSF were found relatively much in Suseong-gu and Dalseong-gun. However, WSF were distributed throughout Metropolitan City, and the vegetation index was not high. The ventilation network that can form WCF included major rivers and roads in Daegu Metropolitan City, but this network was not connected to the urban park from the outer forest. Therefore, it was judged that the formation of WCF connecting WGF outside the city and WSF inside the city would be important. The results of this study can be used as a basic data for systematic wind corridor forest projects, and can be used as basic data for establishing guidelines for wind corridor forest analysis at national and local levels.

• Proceedings of the KGS Conference
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• 2003.11a
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• pp.49-53
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• 2003

기후에 대한 인간의 체감 정도는 "춥다", "덥다"의 정도를 구분하지만 이것이 반드시 기온과 일치하는 것은 아니다. 즉, 습도가 높을 때는 기온이 높지 않아도 더위를 느끼고, 강한 바람이 불 때는 기온이 낮지 않아도 추위를 느낄 수 있다. 국내의 생리기후에 대한 연구는 불쾌지수, apparent temperature, heat index, 윈드칠 지수 등과 같이 지역의 특성을 고려하지 않은 절대적 기준에 의한 지수가 대부분이다.(이와 전, 1982; 윤과 봉, 1987; 최광용 외, 2002.). (중략)

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.125-138
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• 2001

고유진동수와 감쇠비는 지진이나 바람과 같은 동적 횡하중에 대해 구조물의 응답을 결정하는 주요한 특성이다. 본 연구는 지진하중에 대하여 목표응답 수준을 만족하는 구조물의 고유진동수와 감쇠비를 지정하고, 이 값을 실현하는 점탄성 감쇠기 파라미터의 처적분포를 구하는 설계방법을 제안한다. 여기서 지정할 고유진동수와 감쇠비는 목표응답 수준을 만족하는 여러 조합 중 설계조건과 원래 건물의 특성에 따라 결정될 수 있다. 제안한 설계방법은 점탄성 감쇠기의 감성 파라미터를 고유값의 기울기 정보를 바탕으로 분포시키므로 최적 위치와 크기에 대한 정보를 동시에 제공한다. 예제로서 평면 10층 전단 건물을 대상으로 최적설계를 수행하여 지정된 고유값을 실현하는 파라미터의 최적분포를 구하고 이를 통해 제안한 최적 설계의 특성을 확인하였다. 또한 더 나아가 3차원 일방향 비대칭 전단전물에 제안된 최적설계를 수행하여 그에 대한 적용가능성을 확인하였다.

• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.339-350
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• 2009

This study was carried out to investigate distributional condition of rare plants and useful plant resources, and to verify distributional patterns of understory vegetation associated with the upper layer's vegetation structure. Total 59 families, 160 genera, 218 kinds of vascular plants were identified at the study site including 6 rare plants designated by Korea Forest Service (Lloydia triflora Bak., Trillium kamtschaticum Pall., Lilium distichum Nakai, Anemone koraiensis Nakai, Iris odaesanensis Y.N. Lee, Viola diamantica Nakai). Twenty three species of useful plant resources were also identified at the site; 8 of them showed clustered distributions and the others were prone to scatter. Actual vegetation of this study area consisted of one natural community dominated by Quercus mongolica Fisch. and three disturbed communities of Larix kaempferi (Lamb.) Carriere, Abies holophylla Max. and/or a herbaceous vegetation resulting from forest removal and strong wind of mountain top. This classification was strongly supported by cluster analysis based on the surveyed plot data. Distributional patterns of understory vegetation within forest stand were somewhat related to overstory vegetation structure, but showed a different tendency according to site condition, species composition, and competitive pressure among understory vegetation. Therefore, in order to protect the important understory components as forest genetic resources, forest treatments such as density control of overstory should be implanted based on understanding of impact on understory's dynamics and growing condition.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.3
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• pp.205-215
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• 1994

A 3-dimensional numerical model of wind-induced flows has been established. and comparative evaluation of determination methods of vertical eddy viscosity has been performed. The model uses turbulence models to calculate vertical eddy viscosity. The examined methods arp 0-equation model of functional form, 1-equation model of turbulence kinetic energy, and two 2-equation models ($textsc{k}$-$\varepsilon$ and $textsc{k}$-ι models). The evaluation includes the verification tests against experimental data for wind-driven current On a closed one-dimensional channel and a recirculating one-dimensional channel. Comparative study of turbulence models has shown that the proper distribution of turbulence scale is parabolic and the eddy viscosity is depending strongly on mixing depth due to wind.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.2
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• pp.35-42
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• 2001

We demonstrated the importance of initial estimates of model parameters and the utility of an optimization approach of the uncertain forcing of wind-driven circulation off the southeastern coastal waters of Korea. The wind stress represents the upper boundary condition in this model and enters in the model equation as a forcing term in the numerical formalism. The wind field contributes to maintain the almost time-independent distribution of the upper layer thickness feature in a north-south direction and negative wind stress curl to maintain the formation of warm eddy off the southeastern coastal waters of Korea. Elucidated is the variational characteristics of the East Korean Warm Current due to the variations of the zonally averaged wind stress (southward transport) from the seasonal variations of the meridional transport by the Ekman transport.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.3
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• pp.101-113
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• 2015

The purpose of this study is increasing ventilation network usability for urban green space planning by enhancing its practicality and detail. A ventilation network feature extraction technique using roughness length($z_0$) was proposed. Continuously surfaced DZoMs generated from $z_0$(cadastral unit) using three interpolations(IDW, Spline, and Kriging) were compared to choose the most suitable interpolation method. Ventilation network features were extracted using the most suitable interpolation technique and studied with land cover and land surface temperature by spatial overlay comparison. Results show Kriging is most suitable for DZoM and feature extraction in comparison with IDW and Spline. Kriging based features are well fit to the land surface temperature(Landsat-7 ETM+) on summer and winter nights. Noteworthy is that the produced ventilation network appears to mitigate urban heat loads at night. The practical use of proposed ventilation network features are highly expected for urban green space planning, though strict validation and enhancement should follow. (1) $z_0$ enhancement, (2) additional ventilation network interpretation and editing, (3) linking disconnected ventilation network features, and (4) associated dataset enhancement with data integrity should technically preceded to enhance the applicability of a ventilation network for green space planning. The study domain will be expanded to the Seoul metropolitan area to apply the proposed ventilation network to green space planning practice.