• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.6
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• pp.29-36
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• 2008

This study examined the de-icing agents' stresses on Pinus strobus and Pinus thunbergii by chlorophyll fluorescence analysis. The assumption of this study was that photosynthetic efficiency was changed by de-icing agents applied onto highways in winter by altering the concentration of the de-icier, types of de-icer and leaf surface coating liquid application. The practical purpose of this study was to investigate the de-icing gents stresses on Pinus strobus by the highway area where de-icing agents were used frequently and to discover out minimizing stratages to prevent further damages. or this simulation study, a sample plot was established in Bogae-myeon, Anseong, Gyeonggi-do and Pinus strobus and Pinus thunbergii were planted for the examination in April, 2005. Five types of de-icing agents - NaCl, $CaCl_2$, T product(NS40:low cWoride de-icer type), NaCl+$CaCl_2$ and T product+$CaCl_2$ - were selected and the their concentration was altered to 0%, 5%, and 9%. Five types of de-icing agents were applied to both trees treated by a leaf surface coating liquid and trees not treated by leaf surface coating liquid. For the fluorescence analysis, the leaf surface coating liquid, which was diluted by 10 times, was sprkinkled onto the two tree species three days prior to gathering samples. Sample leaves from the two tree species were gathered at 10 o'clock in the morning of mid-August, 2006 and brought to the laboratory within three hours to be dipped in different concentrations (0%, 5%, or 9%) of the five de-icing agents for two minutes. Then the eaves were placed on the filter paper dipped in each solution on a petri dish, sealed with polyethylene film and kept in a growth chamber at $22^{\circ}C$ for 72 hours. Out of the growth chamber, the leaves were treated with a chorophyll fluorescence reaction analyzer for 30 minutes to measure the initial light acceptance rate(Fo), maximum light acceptance ate(Fv/Fm), light acceptance usage(F' q/F' m) and optical electron delivery coefficient(qP). As a result, Pinus strobus' initial light acceptance rate(Fo) decreased as T product and NaCl increased in concentration, and $Cal_2$ did not reduce much with the eaf surface coating liquid application. Maximum light acceptance rate(Fv/Fm) and light acceptance usage(F' q/F' m) decreased sharply as T product and NaCl increased in concentration and NaCl+$CaCl_2$ and T product+$CaCl_2$ did not reduce much with leaf surface coating liquid application. Optical electrons delivery coefficient (qP) decreased as T product increased in concentration on trees without the leaf surface coating liquid application and all other de-icing agents did not show much reduction. As for Pinus thunbergii, the initial light acceptance rate(Fo) decreased as T product increased in concentration, but the maximum light acceptance rate(Fv/Fm) was not reduced much by changes in concentration. light acceptance usage(F' q/F' m) decreased as NaCl increased in concentration and optical electron delivery coefficient(qP) decreased as NaCl increased in concentration in both with and without leaf surface coating liquid application. In conclusion, it was possible to plant Pinus strobus if spraying leaf surface coating liquid or cleaning deicing salt to prevent the damage caused by deicing agents was more economical than replacing the trees. If not, it was better to plant Pinus thunbergii. Another way to decrease the deicing gents stresses of landscape plants would be planting the trees further away from the roads even though it might take longer period to display its planting functions.

• Journal of the Korean Geographical Society
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• v.31 no.3
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• pp.593-612
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• 1996

This study concern with the changes of street from the Choseon Dynasty to present days around Old-Boundary in Taegu, analyzing the backgrounds of change factors and development trends of the Taegu City. The basis element of a city structure is the street. Therefore, in this study, a chage of street space of a city was investigted. Historically, Taegu was a walled city and had a Mono-nucleus which was restricted by the castle, and served as a starting point of formation of spatial structuure. The form of the artery street took a "T" pattern, othe streets were formed in irregular shapes. As the city grew gradually, the castle was removed on account of diversification in traffic network, change of socio-economic organization in traffic network, change of socio-economic organization, formation of industrial bases and functional distribution. CBD of this city has been located within the area surrounded by these streets. This is a kind of general pattern of traditional walled cities through the world in both Western and Oriental societies. A s the begining of this centry, a 'Dark Ages' descended upon Korea because the country was under the Japanese-Korean Annexation, and, throughout this period, the urban planning was planned exclusively for Japanese. The street pattern within residential areas of Korea took the maze type, in contrast with Japanese residential areas which showed grid pattern of streets. This is another general pattern of almost of all colonial cities especially in Asia. High class residential areas were planned and built by Japanese, and they were located within 5-10 minutes' on-foot distance from the CBD hard core. This high prestige has continued until the 1980s when it occurred land use succession which commerical functions invaded into residential areas. Back in the colonial period, there was a between two hetrogeneous groups due to the fact that the Japanese lived mainly oriented the new railway system but that Koreans still lived along the old highway system which ran through the Korea Peninsula. Street netwook formed in the above process has maintained its shape without great changes after the liberation form the Japanese Colony. Taegu has, accordingly, developed ring-radial network system which has been a combination of radial and ring facilities. The present conditions of street patterns in Taegy mainly depend on 4 rings and 8 radius, with grid pattern street able to be found in Old Boundary.

• Journal of Navigation and Port Research
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• v.26 no.3
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• pp.323-328
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• 2002

Soil-steel structures have been used for the underpass, or drainage systems in the road embankment. This type of structures sustain external load using the correlations with the steel wall and engineered backfill materials. Buried flexible conduits made of corrugated steel plates for the coastal road was tested under vehicle loading to investigate the effects of live load. Testing conduits was a circular structure with a diameter of 6.25m. Live-load tests were conducted on two sections, one of which an attempt was made to reinforce the soil cover with the two layers of geo-gird. Hoop fiber strains of corrugated plate, normal earth pressures exerted outside the structure, and deformations of structure were instrumented during the tests. This paper describes the measured static and dynamic load responses of structure. Wall thrust by vehicle loads increased mainly at the crown and shoulder part of the conduit. However additional bending moment by vehicle loads was neglectable. The effectiveness of geogrid-reinforced soil cover on reducing hoop thrust is also discussed based on the measurements in two sections of the structure. The maximum thrusts at the section with geogrid-reinforced soil cover was 85-92% of those with un-reinforced soil cover in the static load tests of the circular structure; this confirms the beneficial effect of soil cover reinforcement on reducing the hoop thrust. However, it was revealed that the two layers of geogrid had no effect on reducing the overburden pressure at the crown level of structure. The obtained values of DLA decrease approximately in proportion to the increase in soil cover from 0.9m to 1.5m. These values are about 1.2-1.4 times higher than those specified in CHBDC.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.33-43
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• 2007

Because usually signal controllers on the crosswalks of mid-block provide pedestrian signals every cycle based on the fixed signal plan, pedestrian signals are provided even when there is no pedestrian demand. Consequently, signal is operated inefficiently and this may cause drivels to experience useless delay or violate the signal. Even though recently pushbuttons have been installed to improve the efficiency of pedestrian signal control in the crosswalks of mid-block and the pedestrian safety. they are not spread out national-wide in Korea because of the cost of the pushbutton equipments and the lack of an acknowledgement of the efficiency of the pushbutton. In this study, the effectiveness of the pushbutton on saving the vehicle delay was verified through before and after study in 4 study sites using a traffic micro-simulation model, VISSIM. To evaluate the viability of the pushbutton, a benefit/cost analysis was also performed for 4 study sites. It was found that B/C ratio of all of 4 study sites was greater than 1. The sensitivity analysis for the traffic volume and pedestrian volume were performed to identify the impact of the both volume on the operation of pushbutton. And, a benefit/cost analysis was performed for all scenarios. It was found that when the pedestrian volume is greater than 90ped/h, the pedestrian signal was operated same as the fixed signal plan. That is, there is no benefit of pushbutton at all once the pedestrian volume is greater than 90ped/h. When the pedestrian volume is equal to or less than 90ped/h and the traffic volume is greater than 2,500veh/h, B/C ratio is greater than 1. Also it was found that as traffic volume increases and pedestrian volume decreases, the benefit increases. In this study, the criteria for installation of pushbutton on the crosswalks of mid-block are developed through the sensitivity analysis and benefit/cost analysis. The results of this study may be used as a criteria for expansion of pushbutton system.

• Journal of Environmental Impact Assessment
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• v.28 no.4
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• pp.387-399
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• 2019

This research aimed to prepare the classification of the damage types and the damage rating system of noise barriers for expressway noise barriers and to develop deterioration evaluation method of noise barriers by reflecting them. The noise barrier consists of soundproof panels, foundations and posts and the soundproof panels with 10 different types of materials are used in a single or mixed form.In this paper, damage of soundproof panel shows a single or composite damage, and thus a evaluation model of deterioration has been developed for noise barriers that can reflect the characteristic of noise barriers. Materials used mainly for soundproof walls were divided into material types for metal, plastic, timber, transparent and concrete. And damage types for noise barrier were classified into corrosion, discoloration, deformation, spalling and dislocation and damage types were subdivided according to the noise barrier's components and materials. Damage rating was divided into good, minor, normal and severe for each major part of noise barrier to assess damage rating of soundproof panel, foundation and post. The deterioration degree of noise barrier was evaluated comprehensively by using the deterioration evaluation method of whole noise barrier using weighted average. Deterioration evaluation method that can be systematically assessed has been developed for noise barrier using single or mixed soundproof panel and noise barrier with single or complex damage types. Through such an evaluation system, it is deemed that the deterioration status of noise barrier installed can be systematically understood and utilized for efficient maintenance planning and implementation for repair and improvement of noise barriers.