• Journal of Forest and Environmental Science
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• v.32 no.3
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• pp.237-252
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• 2016

Improved knowledge of the environmental factors affecting the natural regeneration of tree species in limestone forest is urgently required for species conservation. We examined the environmental factors and tree species characteristics that are important for colonization in diverse forest stands growing on a limestone hill in northern Thailand. Our analysis estimated the relative influence of forest structure and environmental factors on the regeneration traits of tree species. We established sixty-four $100-m^2$ plots in four forest stands on the limestone hill. We determined the species composition of canopy trees, regenerating seedlings, and saplings in relation to the physical environment. The relationships between environmental variables and tree species abundance were assessed by canonical correspondence analysis (CCA), and we used generalized linear mixed models to examine data on seedling/sapling abundances. The CCA ordination indicated that the abundance of tree species within the mixed deciduous forest was closely related to soil depth. The abundances of tree species growing within the sink-hole and hill-slope stands were positively related to the extent of rocky outcropping; light and soil moisture positively influenced the abundance of tree species in the hill-cliff stand. Physical factors had a greater effect on tree regeneration than did factors related to forest structure. Tree species, such as Ficus macleilandii, Dracaena cochinchinensis, and Phyllanthus mirabilis within the hill-cliff or sink-hole stand, colonized well on large rocky outcroppings that were well illuminated and had soft soils. These species regenerated well under conditions prevailing on the limestone hill. The colonization of several species in other stands was negatively influenced by environmental conditions at these sites. We found that natural regeneration of tree species on the limestone hill was difficult because of the prevailing combination of physical and biological factors. The influence of these factors was species dependent, and the magnitude of effects varied across forest stands.

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.533-542
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• 2006

Lidar point clouds provide three dimensional information of terrain surface and have a great advantage to generate precise digital elevation model (DEM), particularly over forested area where some laser signals are transmitted to vegetation canopy and reflected from the bare ground. This study initially investigates the characteristics of lidar-derived height information as related to vertical structure of forest stands. Then, we propose a new filtering method to separate ground points from Lidar point clouds, which is a prerequisite process both to generate DEM surface and to extract biophysical information of forest stands. Laser points clouds over the forest stands in central Korea show that the vertical distribution of laser points greatly varies by the stand characteristics. Based on the characteristics, the proposed filtering method processes first and last returns simultaneously without setting any threshold value. The ground points separated by the proposed method are used to generate digital elevation model, furthermore, the result provides the possibilities to extract other biophysical characteristics of forest.

• International Journal of High-Rise Buildings
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• v.9 no.3
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• pp.273-282
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• 2020

An innovative high-rise timber-concrete hybrid structure was proposed in previous research, which is composed of the concrete frame-tube structure and the prefabricated timber modules as main structure and substructures, respectively. Considering that the timber substructures are built on the concrete floors at a different height, the floor response spectrum is more effective in estimating the seismic response of substructures. In this paper, the floor response spectra of the hybrid structure with different structural parameters were calculated using dynamic time-history analysis. Firstly, one simplified model that can well predict the seismic response of the hybrid structure was proposed and validated. Then the construction site, the mass ratio and the frequency ratio of the main-sub structure, and the damping ratio of the substructures were discussed. The results demonstrate that the peaks of the floor response spectra usually occur near the vibration periods of the whole structure, among which the first two peaks stand out; In most cases, the acceleration amplification effect on substructures tends to be more evident when the construction site is farther from the fault rupture; On the other hand, the acceleration response of substructures can be effectively reduced with an appropriate increase in the mass ratio of the main-sub structure and the damping ratio of the substructures; However, the frequency ratio of the main-sub structure has no discernible effect on the floor response spectra. This study investigates the characteristics of the floor response spectrum of the novel timber-concrete structure, which supports the future applications of such hybrid structure in high-rise buildings.

• Journal of Korean Society of Forest Science
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• v.65 no.1
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• pp.54-59
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• 1984

Research was conducted in a minirotation plantation with four different planting densities at Tatae-ri, Chongwoon-myon, Yangpyong-gun, Kyonggi-do, to investigate the relation between volume and biomass production. Nine-year-old Alnus hirsuta var. sibirica analyzed to determine volume yield and weight equations for aboveground parts. The results suggest that the most suitable harvesting or thinning period at highly dense plots, more than 6,000 trees per hectare, is five years after planting, and the most fitted regression equation model for estimating aboveground biomass or total tree biomass is $logY=b_0+b_1logd^2h$.

• Proceedings of the Korean Institute of Interior Design Conference
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• 1999.04a
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• pp.3-6
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• 1999

The purpose of this study is to analyze the characteristics of exhibition circulation through the movement pattern. It looks into the factoers under the influence with the visitor's movement. The method of analysis of investigation by following after visitors. The viewing behavioral of exhibition based on the time, speed, proportion of appreciation is classfied into three types of the profound, the general, the passing viewers. The characteristics of the viewing form of these patterns largely depend on the space elements which are the structure form. And particularly the position of exit, the width of exhibition space and the connection of exhibition space stand out the disparity of the factor of the spatial structure These three patterns bring about a lot of encounter in the exhibition space according to the difference of these routes consequently. So appropriate to the each pattern can offer visitors to more effective environment of exhibition.

• Journal of the Korean Institute of Landscape Architecture
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• v.19 no.2
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• pp.52-64
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• 1991

The actual vegetation and environmental impact grade of Daekwanrim in Hamyang were investigated and the structure of the plant community was analyzed by the classification of TWINSPAN and three kinds of multivariate ordination (PCA, RA, DCA) techniques.Twenty-eight plots were set up by the clumped sampling method in June of 1990. Carpinus laxiflora and C. tschonoskii communities covered 38% and Quercus species communities covered 39% of the total rea. Environmental impact class 3 and 4 area. Twenty-eight plots were divided into three groups according to the degree of damage by TWINSPAN and ordination techniques. The dominant species in the shrub layer of the heavily damaged site and the light damaged site were Styrax japonica and Sasamorpha purporanscens, so the sucessional trends should be disturbed. As a result of the analysis for the relationship between the stand scores of DCA and the environmental impact class, they had a tendancy to increase from the light damaged to heavily damaged site.

• Journal of Korean Society of Forest Science
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• v.97 no.2
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• pp.144-151
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• 2008

Using 8 isozyme polymorphic loci as gene markers, we studied the spatial distribution of genotypes in a naturally regenerated uneven-aged Eastern Siberian Fir (Abies nephrolepis Max.) stand (1ha, $100{\times}100m$) on Mt. Ohdae in northeastern South Korea. Gregorius' distograms and Moran's I correlograms revealed no evidence of significant genetic structure at three spatial classes of 5 m, 10 m, and 20 m. Extensive gene flow, due to the long distance dispersal of pollen and seeds in A. nephrolepis, may account for the lack of fine-scale spatial structure. Alternatives would be overlapping seed shadows caused by high densities of A. nephrolepis adult trees (160 trees/ha) and/or intraspecific competition resulting in extensive thinning within maternal half-sib groups.

• International Journal of Control, Automation, and Systems
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• v.1 no.2
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• pp.252-256
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• 2003

A biped robot should be designed to be an effective mechanical structure and have smaller hardware system if it is to be a stand-alone structure. This paper shows the design methodology of a biped robot controller using FPGA(Field Programmable Gate Array). A hardware system consists of DSP(Digital Signal Processor) as the main CPU, and FPGA as the motor controller. By using FPGA, more flexible hardware system has been achieved, and more compact and simple controller has been designed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5334-5337
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• 2013

In this paper, the structure of traffic lights removed the wire for the completion of urban aesthetics is analyzed. The finite element model consists of shell elements from three-dimensional CAD model of actual traffic signal. Traffic light pole, horizontal stand shape, thickness, stiffeners, etc. are considered in this study. Analysis of stress and deformation is performed by applying wind load. When the wind load is applied, the result on traffic signal is analyzed. This study is to perform the basic tasks for improving the design.

• Journal of Life Science
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• v.16 no.7 s.80
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• pp.1097-1103
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• 2006

Community structure varies not only in space but also in time. We stand in one position which located at Sinhung-ri, Sacheon-ci and observe the flora of area as time passes. This area begins after disturbance on sites where organisms are already present like secondary succession. In 2001, there are invaded by Trapa japonica, Salvinia natans, and Potamogon cristatus. Four or five years later, this abandoned areas support of clover, pine, and oak, resulting in a shifting pattern of species dominance and diversity through time. Patterns of community structure such as species composition and ecological diversity have shown through seasons and five years, that is the topic of this study. The values of turnover (TO) were changes through time intervals at three regions. The gradual and seemingly directional change in the structure of the community through time from aquatic like to field. Thus, we can observe the process of secondary succession at Sinhung-ri in the very short time.