• Journal of Korea Water Resources Association
• /
• v.44 no.2
• /
• pp.157-167
• /
• 2011

A numerical model was developed to predict the stage-discharge curve and lateral distribution of unit discharge in open channels with nonuniform cross section or compound open-channels. The governing equation is the one-dimensional momentum equation based on assumptions of the steady and uniform flow conditions in the longitudinal direction and the uniform water surface elevation in a cross section. Vegetative drag force term was included in governing equation in order to reflect the effect of floodplain vegetation on the flow characteristics. Finite element method was applied to obtain the numerical solution of the governing equation. Stage-discharge curve and lateral distribution of unit discharge for a given water surface are calculated based on input data, such as the cross sectional geometry, Manning's roughness coefficient, vegetative information and longitudinal slope of channel bed. The developed model was verified by comparing the calculated results with the observed data and the results of Darby and Thorne's(1996) model and the nonlinear k-$\epsilon$ model. The verified model was applied to estimate the upstream boundary conditions in two-dimensional flow model. The numerical results using laterally distributed unit discharge were compared with those obtained using uniformly distributed unit discharge in two-dimensional flow model.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.12
• /
• pp.8-14
• /
• 2019

A drop structure, one of the representative river-crossing structures, is constructed to stabilize a riverbed. On the other hand, the structure interrupts the continuity of the river and causes the destruction of the hydro-ecological environment. Therefore, laboratory experiments of a natural type of drop structure with low differences were performed, and the empirical formula of a local scour hole is proposed. Four experimental flow rates were tested for various types of the drop structure models with 28 test cases. Based on the scour test, it was confirmed that the maximum scour depth occurs rather than the result of applying the previously proposed scour depth formulae. Correlation analysis of the major factors of scour hole at the downstream of the drop structure revealed a strong correlation between the upstream flow characteristics, drop structure height, and total crossing length of the drop model. In addition, the depth and length estimation formula of the maximum scour hole were proposed using the dimensionless variables and validated. In the future, it is also expected that more accurate scour prediction and calculation can be derived by conducting experimental studies and numerical analysis considering the various bed materials and flow conditions.

• Journal of Korean Society of Transportation
• /
• v.29 no.5
• /
• pp.157-167
• /
• 2011

Many problems, such as unexpected delay and collision with pedestrians or vehicles, occur generally at signalized intersections where bicycle users are frequently involved. These problems have hindered bicycle users from riding bicycles on urban highways. The aim of this study is to suggest proper traffic signal operation methods for safe and convenient highway crossing of bicycles. Three types of crossing methods at signalized intersections are proposed and analyzed: (1) indirect left turn, (2) direct left turn on an exclusive bicycle lane, and (3) direct left turn on a bicycle box. The VISSIM simulation tests were conducted based on fifty-four operation scenarios prepared by varying vehicle and bicycle traffic volumes. Both delay and the number of stops are used as the measures of effectiveness in the analysis. The results from the three-legged signalized intersections suggested that (1) the indirect left turn is appropriate when vehicle demand is high while bicycle demand is not, (2) direct left turn on an exclusive bicycle lane is appropriate when both vehicle and bicycle demands are high, and (3) direct left turn on a bicycle box is appropriate when both vehicle and bicycle demands are light.

• Cross-Cultural Studies
• /
• v.48
• /
• pp.1-30
• /
• 2017

The purpose of this study is to review two books on the history of Korean literature written in Japanese, taking special interest in ancient Korean literature, examining transcultural patterns between the history of North and South Korean literature and that of Japanese literature, and thereby identifying perceptions and description patterns of the history of Korean literature from the perspective of comparative literature. This study analyzes two books with the same title The History of Joseon Literature written in Japanese by Kim Dongwook and Byeon Jaesoo. The two books are not translations of Korean books but were written in Japanese for Japanese and ethnic Korean readers in Japan. The History of Joseon Literature (1974) by Kim Dongwook mainly compares Joseon literature with Japanese literature. The History of Joseon Literature (1985) by Byeon Jaesoo, an ethnic North Korean in Japan, was written from socialistic perspectives. The two books have different standards for evaluating value of the history of Joseon literature and different perceptions about it. Due to the division between North and South Korea, the history of literature is unfolding in different ways in the two Koreas, and the two books reflect such differences. However, they have several common features. For example, they highly regard the value of literature written in Chinese characters and originality of hangga (a folk song of Silla), Hangeul (the Korean alphabet), and pansori (a form of Korean folk music in which a singer accompanied by a supportive drummer sings and chants an epic story). In addition, they both demonstrated that literature written in Hangeul and that written in Chinese characters interacted with each other as the same Korean literature. When the two books were written, the history of Korean literature had been considered a subunit of the history of East Asian or Chinese literature. However, as this study found, Kim and Byeon wrote the two books from a perspective of departing from this view based on nationalism, re-establishing the value of Korean literature, promoting Japanese people's understanding of the high quality of Korean literature, and imbuing ethnic Koreans in Japan with nationalistic pride.

• Journal of Korean Society of Forest Science
• /
• v.42 no.1
• /
• pp.67-73
• /
• 1979

In order to observe the anatomical phenomena of root formation in the hypocotyl cuttings of maples, the hypocotyls of Acer palmatum. Acer micro-sieboldianum, and Acer saccharinum were used as the materials. The rooted portions were sectioned by a microtom and doubly stained by safranin and fast green. The results obtained are summarized as follows; 1. A cross section structure of hypocotyl cuttings of Acer sp. is consist of epidermis, cortex, vascular bundle and pith from the outside. The vascular bundle makes circular shape forming polyarch in A. saccharinum and tetrarch in both A. palmatum and A. micro-sieboldianum. 2. An adventitious root of A. saccharinum originated in phloem parenchyma, while that of A. palmatum and A. micro-sieboldianum originated in interfascicular parenchyma related with phloem cells. 3. The hypocotyl cuttings of Acer sp. is commonly composed of parenchyma tissue having vigorous differentiation capability. Therefore, the originated root grow easily through the cortex and epidermis breaking their tissues.

• Journal of Forest and Environmental Science
• /
• v.15 no.1
• /
• pp.77-88
• /
• 1999

This experiment was carried out to compare the cultural characteristics of mycorrizal fungi associated with Pinus species, and to form mycorrhizal association with Pinus thunbergii by artificial inoculation of these fungi. Mycorrhizal fungi tested showed great variations in cultural characteristics. Most fungal isolates was best grown on MP medium, except PDA for Lepista sp.(Ln73/92). Hagem for Rhizopogon rubescens(FRI91017), and FDA for Paxillus sp.(Pa60/92). Optimum temperature for these fungi was $25^{\circ}C$, except $30^{\circ}C$ for Pisolithus tinctorius(FRI91004 and Pt1). The range of pH conditions favorable for these fungal isolates were also variable from weak acidic(pH5) to weak alkalic(pH8). Utilization of the carbon sources for these mycorrhizal fungi was different. Fructose, glucose, and maltose were all utilized well, while xylose was not utilized generally. Mycelial growth on the media supplemented with potassium nitrate was better than those on other media with urea, asparagine, or peptone as a nitrogen source, and the poor growth was observed on the media with urea. Pisolithus tinctorius(Pt1) among 7 mycorrhizal fungi artificially inoculated for the mycorrhizal synthesis on pinus thunbergii seedlings in the test tube containing a mixture of peat moss-vermiculite(2:1, v/v) formed mycorrhizae successfully after 3 months. P. tinctorius formed branched and unbranched roots covered with thick fungal mantle and radiating extemal hyphae. Mycorrhizal root cross-sectioned by hand, stained, and observed by Nomarski interference microscope showed typical characteristics of ectomycorrhizae: fungal mantle on epidermal cells and thick Hartig net hyphae around cortex cells.

• Ecology and Resilient Infrastructure
• /
• v.8 no.1
• /
• pp.64-78
• /
• 2021

This study was conducted to find out the effect of the construction and operation of river-crossing structures on the habitat landscape characteristics in the Geum-gang River, South Korea. A total of three study reaches were selected in the downstream of the Daecheong Dam: the Buyong-ri reach, which is a control that is not affected by the construction and operation of the weir of the Four Rivers Project and Sejong-bo Weir reach and Gongju-bo Weir reach of the upper and lower sections of each weir that are affected by the weir construction and operation. The habitat type was classified, and then the structural characteristics of the landscape were analyzed using aerial photographs taken before and after the construction of the Daecheong Dam, before and after the construction of the weir, and before and after the weir gate operation. After the construction of Daecheong Dam in Geum River, the area of the bare land greatly decreased, and the area of grassland and woodland increased in the downstream of the dam. In addition, the patch number in the river landscape increased, the patch size decreased, and the landscape shape index and the habitat diversity increased. Therefore, after the construction of the dam, the bare land habitat was changed to a vegetated habitat, and the habitat was fragmented and diversified in the downstream of the dam. After the construction of the weirs, the area of open water increased by 18% in the Sejong-bo reach and by 90% in the Gongju-bo reach, and the landscape shape index of the open water decreased by 32% in the Sejong-bo reach and by 35% in the Gongju-bo reach, and the habitat diversity index decreased to 25% in the Sejong-bo reach and to 24% in the Gongju-bo reach. Therefore, the open water habitat was expanded, the shape of the habitat was simplified, and the habitat diversity decreased according to the construction of the weirs. After water-gate opening of the weir, the bare land that disappeared after the construction of the weir reappeared, and the landscape shape index and habitat diversity index increased in both terrestrial and open water habitats. Therefore, it was found that the landscape characteristics of the river habitats were restored to the pre-construction of the weir by the operation of the weir gate. The effect of weir gate opening was delayed in the downstream than in the upstream of the weir. Although the characteristics of the landscape structure in the river habitat changed due to the construction of the river-crossing structures, it is thought that proper technology development for the ecological operation of the structures is necessary as the habitat environments can be restored by the operation of these structures.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.4C
• /
• pp.276-282
• /
• 2005

These studies developed system as well as its algorithm which can measure traffic flow and vehicle speed on the highway as well as road by using industrial television(ITV) system. This algorithm used the real time processing of dynamic images. The processing algorithm of dynamic images is developed and proved its validity by frame grabber. Frame grabber can process the information of a small number of sample points only instead of the whole pixel of the images. In the techniques of this algorithm, we made approximate contour of vehicle by allocating sampling points in cross-direction of image, and recognized top of contour of vehicle. Applying these technique, we measured the number of passing vehicles of one lane as well as multilane. Speed of each vehicle is measured by computing the time difference between a pair of sample points on two sample Points lines.

• Journal of Advanced Navigation Technology
• /
• v.9 no.1
• /
• pp.10-18
• /
• 2005

These studies developed system as well as its algorithm which can measure traffic flow and vehicle speed on the highway as well as road by using industrial television(ITV) system. This algorithm used the real time processing of dynamic images. The processing algorithm of dynamic images is developed and proved its validity by frame grabber. Frame grabber can process the information of a small number of sample points only instead of the whole pixel of the images. In the techniques of this algorithm, we made approximate contour of vehicle by allocating sampling points in cross-direction of image, and recognized top of contour of vehicle. Applying these technique, we measured the number of passing vehicles of one lane as well as multilane. Speed of each vehicle is measured by computing the time difference between a pair of sample points on two sample points lines.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.5 no.2 s.10
• /
• pp.61-71
• /
• 2006

The main purpose of this study is to search a method for reducing traffic accident at signalized intersections. One of the important factors for this is the Left-turn phase sequence. In 1985, the operational principle of Left-turn phase Sequence was changed from Lagging left-turn to Leading left-turn in Korea. Then there was a resonable motive-no exclusive left turn-lane and narrow intersection. So, it is necessary to evaluate the performance difference between Leading and Lagging left -turn phase Sequence. The process of this study is as follows: $\cdot$ First, all the intersection was divided three parts for analysis the traffic safety: Inside part of an Intersection, Crosswalk, Intersection approach and exit. $\cdot$ Second, a safety analysis was performed by using the concepts of 'Effective interphase Period(EIP)' and 'Conflict method' The Study result is that the benefit of of phase Sequence changes from Leading to Lagging phase were significant. For an example the Accident cost will reduced about 41.8 billion won per year in korea.