• Journal of the Korean Institute of Landscape Architecture
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• v.41 no.3
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• pp.31-42
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• 2013

This study was carried out to systematically maintain and manage the trails by assessing the types of deterioration and naturalness of trails located in Mt. Toham, Mt. Nam, Mt. Danseok and in the Mt. Gumi district of the Gyeongju National Park. The route length of Mt. Toham was 2.7km, 2.3km of Mt. Nam, 1.0km of Mt. Danseok and 2.7km of Mt. Gumi district. The numbers of measuring points in Mt. Toham were 37 units, 29 units of Mt. Nam, 16 units of Mt. Danseok and 40 units of Mt. Gumi district. In characteristics of physical environments, Mt. Danseok was the widest and Mt. Gumi was the narrowest in the width of trail. In the bared width of trail, Mt. Danseok was the widest and Mt. Gumi was the narrowest. In depth of erosion, Mt. Danseok was the deepest and Mt. Gumi was the shallowest. Mt. Danseok was the steepest and Mt. Nam was the gentlest in the longitudinal slope. In the results of analysing the types of deterioration, Mt. Toham were 10 types, 14 types of Mt. Nam, 11 types of Mt. Danseok and 9 types of Mt. Gumi district. The times of appearance of deterioration types in Mt. Toham were 69 times, 87 times of Mt. Nam, 67 times of Mt. Danseok and 71 times of Mt. Gumi district. The most common type was the exposure of root in 4 districts of Gyeongju National Park. In the results of assessing the naturalness, Mt. Toham was 2.1 score(II degree), 2.6 score(II degree) of Mt. Nam, 2.9 score(III degree) of Mt. Danseok and 2.0 score(II degree) of Mt. Gumi district. The average naturalness was 2.4 score and II degree.

• Journal of Korean Society of Forest Science
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• v.81 no.4
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• pp.363-371
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• 1992

This study was aimed at developing a computer model to determine rational road networks in mountainous forests. The computer model is composed of two major subroutines for digital terrain analyses and route selection. The digital terrain model(DTM) provides various information on topographic and vegetative characteristics of forest stands. The DTM also evaluates the effectiveness of road construction based on slope gradients. Using the results of digital terrain analyses, the route selection subroutine, heuristically, determines the optimal road layout satisfying the predefined road densities. The route selection subroutine uses the area-partitioning method in order to fully of roads. This method leads to unbiased road layouts in forest areas. The size of the unit partitiones area can be calculated as a function of the predefined road density. In addition, the user-defined road density of the area-partitioning method provides flexibility in applying the model to real situations. The rational road network can be easily achived for varying road densities, which would be an essential element for network design of forest roads. The optimality conditions are evaluated in conjuction with longitudinal gradients, investment efficiency earthwork quantity or the mixed criteria of these three. The performance of the model was measured and, then, compared with those of conventional ones in terns of average skidding distance, accessibility of stands, development index and circulated road network index. The results of the performance analysis indicate that selection of roading routes for network design using the digital terrain analysis and the area-partitioning method improves performance of the network design medel.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.378-391
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• 2012

The objective of this study was to determine temporal patterns and longitudinal gradients of water chemistry at eight artificial reservoirs and ten streams within the Han-River watershed along the main axis of the headwaters to the downstreams during 2009~2010. Also, we evaluated chemical relations and their variations among major trophic variables such as total nitrogen (TN), total phosphorus (TP), and chlorophyll-a (CHL-a) and determined intense summer monsoon and annual precipitation effects on algal growth using empirical regression model. Stream water quality of TN, TP, and other parameters degradated toward the downstreams, and especially was largely impacted by point-sources of wastewater disposal plants near Jungrang Stream. In contrast, summer river runoff and rainwater improved the stream water quality of TP, TN, and ionic contents, measured as conductivity (EC) in the downstream reach. Empirical linear regression models of log-transformed CHL-a against log-transformed TN, TP, and TN : TP mass ratios in five reservoirs indicated that the variation of TP accounted 33.8% ($R^2$=0.338, p<0.001, slope=0.710) in the variation of CHL and the variation of TN accounted only 21.4% ($R^2$=0.214, p<0.001) in the CHL-a. Overall, our study suggests that, primary productions, estimated as CHL-a, were more determined by ambient phosphorus loading rather than nitrogen in the lentic systems of artificial reservoirs, and the stream water quality as lotic ecosystems were more influenced by a point-source locations of tributary streams and intense seasonal rainfall rather than a presence of artificial dam reservoirs along the main axis of the watershed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.1
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• pp.1-17
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• 1982

The stream morphological characteristics of a river basin has a close correlation with the hydrological and hydraulic characteristics of the basin. In this study the correlations of flow duration and Hydraulic geometry with the stream morphological characteristics as well as the correlation between flow duration and hydraulic geometry were analyzed bases on the data for the Geum River basin. The purpose of this study was to provide the necessary informations for water utilization projects at ungauged locations along the river course. First of all, the stream morphological characteristics was analyzed based on the Horton's three laws on the morphology of a stream that is, the law of stream number, the law of average stream length and the law of average stream slope. As is the case for majority of the rivers it was found that the Geum River basin was well developed according to the Horton's laws. High correlations were also found between the basin characteristics and the channel characteristics. The flow duration curves obtained with the daily stream flow data of 10~90% frequency of occurences at the five stage gauging stations in the Geum River could, in general, be expressed as an exponential functional relationship. The concept of proportional stream ordering system was employed to describe continuously the longitudinal variation of the stream morphological characteristics, and the mathematical model was formulated for the discharge-frequency-proportional stream order relationship. With the morphological characteristics as a common parameter the relationships with flow duration, drainage area were established in mathematical expressions, respectively.