• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.448-453
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• 2002

Remote sensing technology is one of the most powerful tools for human to know the nature and their living environment. However, before microwave remote sensing was developed and applied, remote sensing application was limited strongly by weather and time. Microwave remote sensing technology solves the problem. It makes us to have the capability to acquire information at all time of the day and under all weather condition, and make remote sensing technology be used in more wider area. Microwave remote sensing system include mainly Synthetic Aperture Radar (SAR), Microwave Radiometer, Microwave Scatterometer, and Altimeter (ALT). As SAR can acquire image whose spatial resolution is similar with visible and infrared image, it is paying much attention to and playing a more and more important role in earth observation. In recent year, the development of new SAR technology (multi-band and multi-polarization technology, InSAR technology, D-InSAR technology, and so on) makes SAR remote sensing go to an new stage, and its application area become more and more widely. The first Synthetic Aperture Radar (SAR) in the world appeared in 1960. After that, SAR and its application all developed very fast. Some radar satellites launched and run (include Seasat-A in 1978, ERS-1 in 1991, JERS-1 in 1992, Radarsat in 1995, and so on) promote SAR research and application in world greatly. China began to develop its SAR sensor and research SAR application in 1970s. After more than 30 years' research, it get some important development in sensor development data processing method, and application. Some operational systems have been used and play an important role. This paper will introduce the development of SAR technology and its application in China.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2003.03a
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• pp.113-120
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• 2003

The estimation of the coeff. of permeability is a major process that influenced in very large portion to the changing of gound water movement and estimation of the outflow’s quantity in the ground water movement modelling. To overcome the error caused by difficulty of the ground investigation for the hydraulic parameter’s estimation, in this paper, we study of correlation between electric resistivity and coeff. of permeability, and analyse of coeff. of permeability from electric resistivity. To accomplish this purpose, we carry out electrical logging, AMT survey as an in-situ test, and measure electric resistivity, porosity, permeability for the intact rock as a laboratory test. Based on the results of this research, it can be applied that estimation of the coeff. of permeability using electrical logging and AMT survey is a effective method for the impossible area of the ground investigation caused by geographical condition and petition.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2B
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• pp.187-195
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• 2006

A bridge scour management system is developed to evaluate the vulnerability of bridge piers to scour and to help establish effective disaster measures, taking into account the locality and scour characteristics in Korea. This system is programmed using the techniques of the geographical information system(GIS) for the storage, retrieval, and display of information regarding to bridge scour. The system functions are basically divided into two parts; prioritization and maintenance. Bridges are initially screened and prioritized for bridge scour inspection and evaluation using the basic information which is obtained from the office review. The bridge scour evaluation including site investigation is performed and the vulnerability of bridge piers is categorized into six groups taking into account the local scour depth, foundation bearing capacity, foundation type, foundation depth, and present scour condition. The system tabulates and plots all the data and the results.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.2
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• pp.107-120
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• 2014

First purpose of this study is to build Korean mountain ridgelines based on GIS by using spatial information and analyze natural environment around mountain ridgelines built before. Second purpose of this study is to integrate Korean ridgelines and natural environment built before and then provide the integrated information related to ridgelines for public. To do so, fist of all, Korean mountain ridgelines including Deagan, Jeongmeak, Gimeak, Jimeak, are built as spatial information. Second, Encoding of mountain ridgelines is conducted to analyze main and divaricate ridgelines systematically as grades of ridgelines. Third, based on spatial information, present condition using natural environment including geographical information, ecological zoning map, environmental conservation value assessment map, is analyzed. Finally, as a method integrating and using the aforementioned three information, the system providing integrated information based on GIS is proposed, To build the GIS data of Gimeak and Jimeak, they should be analyzed in more detail than Beakdu Deagan and Jeongmeak, so existing methodology to build mountain ridgelines based on GIS is improved. According to the distance of each mountain ridgeline, they are separated into five grades, and encoding of each mountain ridgeline based on Beakdu Deagan is applied to all mountain ridgelines to figure out the present condition of ridgelines themselves. In addition, according to the distance of each mountain ridgeline, it is separated into three areas: core, buffer, median zone. Based on three zones, the way to make use of the information efficiently related to mountain ridgelines is proposed. This study systematizes Korean mountain ridgelines which did not have systematic structures and then analyzes systematic mountain ridgelines. Based on this analysis, this study finds the way to makes use of information related to mountain ridgelines effectively.

• Fire Science and Engineering
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• v.22 no.2
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• pp.63-69
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• 2008

The characteristics of the spread of a forest fire are generally related to the attributes of combustibles, geographical features, and meteorological conditions, such as wind conditions. The most common methodology used to create a prediction model for the spread of forest fires, based on the numerical analysis of the development stages of a forest fire, is an analysis of heat energy transmission by the stage of heat transmission. When a forest fire breaks out, the analysis of the transmission velocity of heat energy is quantifiable by the spread velocity of flame movement through a physical and chemical analysis at every stage of the fire development from flame production and heat transmission to its termination. In this study, the formula used for the 1-D surface forest fire behavior prediction model, derived from a numerical analysis of the surface flame spread rate of solid combustibles, is introduced. The formula for the 1-D surface forest fire behavior prediction model is the estimated equation of the flame spread velocity, depending on the condition of wind velocity on the ground. Experimental and theoretical equations on flame duration, flame height, flame temperature, ignition temperature of surface fuels, etc., has been applied to the device of this formula. As a result of a comparison between the ROS(rate of spread) from this formula and ROSs from various equations of other models or experimental values, a trend suggesting an increasing curved line of the exponent function under 3m/s or less wind velocity condition was identified. As a result of a comparison between experimental values and numerically analyzed values for fallen pine tree leaves, the flame spread velocity reveals a prediction of an approximately 10% upward tendency under wind velocity conditions of 1 to 2m/s, and of an approximately 20% downward tendency under those of 3m/s.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.337-347
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• 2018

The government has been operating residential improvement projects through the "Act on the Maintenance and Improvement of Urban Areas and Dwelling Conditions for Residents" as a type of a remedial measure for deteriorated residential areas. However, in recent years, the residential improvement projects have experienced difficulties due to the effects of various factors including the slowdown in economic growth. After observing the depression in a number of projects, various studies have been carried out to investigate the causality and improve the promotion of the residential improvement projects. In the trend of research, this study aims to analyze the effects of land and building characteristics on the improvement projects of Busan Metropolitan City. The dependent variables of the study represent different phases of improvement project as specified in the "Act on the Maintenance and Improvement of Urban Areas and Dwelling Conditions for Residents". The independent variables represent land and building characteristics which refer to the criteria used in the designation process of maintenance area according to the act. The empirical analysis uses the ordered logit model. The results from the analysis suggest that geographical condition, factors related to the number of union members, factors related to the parcel price and condition of a location have impact on the promotion of the improvement project. The results of the analysis show that majority of the factors are related to the economic feasibility of the projects. Residential improvement project is a part of urban planning projects that rehabilitates deteriorated residential environment, and it is closely associated with the quality of life of public. Accordingly, we hope that such projects are reasonable and take effective approach to those with urgent needs rather than to focus on profitability. Also, potential administrative and economical loss should be avoided by taking necessary planning measures in advance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.249-259
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• 2018

More than half of annual rainfall occurs in summer season in Korea due to its climate condition and geographical location. A frequency analysis is mostly adopted for designing hydraulic structure under the such concentrated rainfall condition. Among the various distributions, univariate Gumbel distribution has been routinely used for rainfall frequency analysis in Korea. However, the distributional changes in extreme rainfall have been globally observed including Korea. More specifically, the univariate Gumbel distribution based rainfall frequency analysis is often fail to describe multimodal behaviors which are mainly influenced by distinct climate conditions during the wet season. In this context, we purposed a Gumbel mixture distribution based rainfall frequency analysis with a Bayesian framework, and further the results were compared to that of the univariate. It was found that the proposed model showed better performance in describing underlying distributions, leading to the lower Bayesian information criterion (BIC) values. The mixed Gumbel distribution was more robust for describing the upper tail of the distribution which playes a crucial role in estimating more reliable estimates of design rainfall uncertainty occurred by peak of upper tail than single Gumbel distribution. Therefore, it can be concluded that the mixed Gumbel distribution is more compatible for extreme frequency analysis rainfall data with two or more peaks on its distribution.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1804-1820
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• 1997

In this paper, an efficient call control procedure is presented for next generation wireless ATM networks and its performance is mathematically analyzed using the open queueing network. This procedure is based on a new scheme called as the cell clustering. When we use the cell clustering scheme, at the time that a mobile connection is admitted to the network, a virtual cell is constructed by choosing a group of neighboring base stations to which the call may probabilistically hand over and by assigning to the call a collection of virtual paths between the base stations. Within a microcell/picocell environment, it is seen that the cell clustering can support effectively a very high rate of handovers, provides very high system capacity, and guarantees a high degree of frequency reuse over the same geographical region without requiring the intervention of the network call control processor each time a handover occurs. But since mobiles, once admitted, are free to roam within the virtual cell, overload condition occurs in which the number of calls to be handled by one base station to exceed that cell site's capacity of radio channel. When an overload condition happens, the quality of service is abruptly degraded. We refer to this as the overload state and in order to quantify the degree of degradation we define two metrics, the probability of overload and the normalized average time spent in the overload state. By using the open network queueing model, we derive closed form expressions for the maximum number of calls that can be admitted into the virtual cell such that the two defined metrics are used as the acceptance criteria for call admission control.

• Korean Journal of Environment and Ecology
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• v.35 no.4
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• pp.398-407
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• 2021

This study intended to identify causes of poor tree vigor in the Hanbando coastal forest by investigating its geographical environment, climate condition, soil physicochemical characteristics, and growth condition of Pinus thunbergii. It divided the forest into an area with poor tree vigor or dead standing trees and a control area with good tree vigor and examined them separately. The survey showed that stand density was significantly higher in the area with poor tree vigor. In contrast, the crown width in the area with good tree vigor was wider. The number of dead standing trees and the stand density showed a negative correlation. The stand density and diameter at breast height (DBH), tree height, crown height, and crown width also showed a negative correlation. The result indicated that, as the tree's stand density increases, the crowns of individual trees overlapped and the lower branches died. Then crown height and crown width decreased, and the number of leaves and photosynthesis was reduced, leading to lower tree height and weaker growth of breast diameter. As a result, tree vigor weakened, and combined with environmental pressures from the lack of moisture and nutrients in coastal soil and salty wind, P. thunbergii in coastal areas is expected to die massively. Although the causes of dead standing trees and poor tree vigor of P. thunbergii in the Hanbando coastal forest are complicated, poor management of adequate tree density in response to the growth of P. thunbergii is the primary cause. The secondary cause is external environmental pressures, including unfavorable soil conditions and salty and strong wind that obstruct the growth of P. thunbergii.

• The Korean Journal of Ecology
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• v.25 no.5
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• pp.341-348
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• 2002

Correlations among the island area, distance to mainland, latitude, longitude, human impacts, diversity and composition of vascular plants were investigated by analyzing data on 261 islands(10.3% of total number of islands in Korea) selected from the annual reports for 'the natural evironment survey of the uninhabited islands in Korea' published by 'Ministry of Environment' during three years from 1999. The area of surveyed 261 islands ranged 1,100 to 961,000㎡(average of 75,000㎡), and the distance to mainland ranged 0.15 to 51.5km (average of 14.9km). Total number of plant species recorded in those islands was 1,109 species throughout 30 families, and mean mumber of plant species of each island was 98.7 species. Native species were 1,003 species (90.4%), and exotic species were 106 species(9.6%). The families with the largest number of species was the Compositae with 114 species, and followed in the order of Gramineae(90), Leguminosae(54), and Rosaceae(53). The result of multi-dimensional scaling analysis based on the plant species composition showed that 261 islands were distinctly divided into two groups, western sea group(131 islands) and southern sea group(130 islands). The islands of western sea group(average area of 93,000㎡) had greatly larger area than them of southern sea group(average area of 57,000㎡), but the average number of species (average species of 192) per island were less than in southern sea group (average species of 233). And, the partitioning into two groups was responsible for the species restricted to southern than to western sea group. Therefore, this results suggest that the distribution pattern and the composition of plant species could be also affected by the latitude of the island. When the species-area model was applied to total island and plant species, these results indicate that the island area was the most significant predictor of plant species diversity, and the distance to mainland and the human impacts were also shown to be significant predictors of plant species richness. But when applied to both groups of islands by the stepwise selection method, the result showed that islands of southern sea group were greatly affected by the factors such as human impacts, distance to mainland and longitude than western sea group. For the purpose of conservation of natural ecosystem on the uninhabited islands in Korea, we will also examine how the human impacts and the invasion of exotic plant species will disturb the native species diversity.