• Weed & Turfgrass Science
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• v.2 no.1
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• pp.82-87
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• 2013

This research will be utilized as a base line data by researching on growth and the accumulation of inorganic nutrients during the cultivation period of zoysiagrass and also to establish a cultivation strategy of zoysiagrass. It involves the management such as fertilizer and mowing which ultimately led to the difference of growth and accumulation of inorganic nutrients. The accumulation of inorganic nutrients after mowing, the amount of accumulation was small when compared to the amount lost for the shoot, rhizome and root. Difference in the accumulation of inorganic nutrients, but as for K, Ca and Mg accumulation it shows similar aspects to N accumulation. The orders of inorganic nutrients in zoysiagrass were N > K > P > Ca > Mg. The characteristics of inorganic nutrients absorption of such zoysiagrass acts as the foundation of cultivation, and in the aspect of making decisions on the fertilization amount and soil management, it is closely related to the requirement on nutrients. In order to increase the productivity based on the zoysiagrass's growth and density rate improvement, accumulation of inorganic nutrients per growth period needs to be analyzed, and supplying nutrients in an efficient method suitable to the growth period is advisable, so such basic research was necessary.

• Journal of Korean Society of Steel Construction
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• v.27 no.6
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• pp.503-511
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• 2015

In long span steel structure, the plate girder reinforced with stiffeners are commonly used. When choosing the cross section with deep depth of girder as well as narrow width, however, out of plane buckling can be a problem due to web slenderness. In an effort to solve this issue, current study determined the applicability of using corrugated web girder with deep depth as bending member, which is generally being utilized in both factory and warehouse nationwide. To accomplish this, we performed the loading test of H-shaped beam with sinusoidal corrugated web. Corrugated web CP-2.3 specimen exhibited 12% less maximal bending strength but CP-3.2 specimen exerted 24% increase in strength compared to plate web P-4.5. this result indicates that corrugated web provides enough strength even with unfavorable width-thickness ratio of plate. And bending as well as shear strength estimated by the Eurocode (EN 1993-1-5) were compared with both bending strength by loading test and shear strength estimated by KBC2009. In case of eurocode, increase in plate thickness did not help in bending performance improvement. moreover, shear performance was sensitive to the thickness of the web folds and the shape of the web plate.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.4
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• pp.62-73
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• 2003

The study was to apply a mat style reed planting method at confluence to improve plants growth conditions by relaxing disturbed topographical base due to water flow and was intended to review the effect to build up a vegetation strip by monitoring process after the construction. First off, We've attempted to construct reed mats on selected sites as confluences of Tan and Gaehwa stream and then examined and analyzed characteristics of soil and vegetation community. As the results of the examination, the soil texture was proven to be a mix of sand and loamy sand and be 6.3 ~ 7.0 soil pH. In addition, it contained 1.0 ~ 4.6% of organic matter, 0.04 ~ 0.22% of T-N and 27.8 ~ 41.2% of water content. For its vegetation structure, the Tan stream confluence was first actually a point bar without plants prior to the construction but 8 kinds of hygrophytes including Persicaria hydropiper and 9 kinds of terrestrial plants such as Potentilla supina, Artemisia annua, and Alopecurus aequalis var. amurensis. On the other hand, the Gaehwa stream confluence contained 6 kinds of hygrophytes such as Bidens frondosa and other 11 kinds of terrestrial plants prior to the construction while it produced 7 kinds of hygrophytes including Ranunculus ternatus as well as Phragmites australis and 9 kinds of terrestrial plants such as Potentilla supina after the construction. For the Phragmites australis, almost of them was weathered away in early days just after planting because of development period passed, but on May, six months later from planting, it was investigated that its length was approximated as 65 ~ 85cm with 75% coverage and that the number of it was 437 ~ 633/$m^2$. The study was shown that reed mats can improve environmental conditions of disturbed topographical base, enabling natural growth of various riparian vegetation including the introduced plant, reed. In the meantime, it was supposedly judged that to recover or build up a vegetarian strip, supplementary materials should be prepared to help produce and grow plants because it is not probable to expect river drift by water flow at confluence and that corrosion, burying or inundation owing to changes of water lever should be considered.

• Korean Journal of Environment and Ecology
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• v.26 no.5
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• pp.801-811
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• 2012

The purpose of this study is to find out how land cover and planting of an urban park influence temperature. Field research on the land cover and planting status was conducted for Bundang Central Park in Sungnam-si. 30 study plots in the site were selected to closely analyze land cover type and planting structure. The temperature was measured 10 times for each plot. Land coverage type, planting type, planting layer structure and green space area (the ratio of green coverage, GVZ) were chosen as factors impacting temperature and statistics were analyzed for the actual temperature measured. Analysis on how the land coverage type influences temperature showed that planting site had a low temperature and that grassland and paved land had a high temperature. When it comes to planting type, the temperature at the land planted with conifers and broad-leaved trees was low, while the temperature at grassland and paved land was high. With regard to planting layer structure, canopy and canopy-underplanting type showed low temperature, while grassland and paved land showed high temperature. An analysis on the relation between green space area and temperature found out that both ratio of green coverage and GVZ had a high level of negative correlation with the temperature measured. According to regression model of green space area and the temperature measured, for every 1% increase in the ratio of green coverage, temperature is expected to lower by $0.002^{\circ}C$. Also, for every $1m^3/m^2$ increase in GVZ, temperature is expected to go down by $0.122^{\circ}C$.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.91-100
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• 2010

Existing traffic safety studies have focused on identifying the relationship among roadway crashes, highway design and incremental weather condition such as rainy/ice weather. However, it is hard to find researches that studied the effect of sun glare on traffic safety although there are abundant evidences demonstrating that fatal traffic crashes are attributed to the sun glare. Affecting drivers'vision particularly during the morning or the evening time when the sun positions close to the horizon, sun glare directly deteriorate drivers'judgmental capability. In this paper, we numerically analyze the effect of sun glare on the drivers'vision in time and space domains. Applied to the roadways around St Louis area in the United States, the GIS based simulation analysis identifies the time of day in a year and the segments of highways that are potentially influenced by the sun glare. This study evidentially confirms the fact that roadway bounded for West and East directions have longer time influenced by sun glare particularly during Spring and Fall season than other roadways. The computational result provides risky time periods of day at intersections or pedestrian crossings where the sun glare potentially endangers traffic safety, which be utilized to reduce the crashes due to the sun glare.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.78-90
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• 2010

This research tried to suggest a method of DB construction in the field using evaluation variables and Mobile GIS focusing on Changwon City as a leading study to encourage walking and biking in everyday life. First, twenty evaluation variables of WEs(walking environments) were selected through the literature review, and also scored separately. Second, the field survey-DB of each variable was built effectively using Mobile GIS. Finally, WEs were evaluated synthetically based on the obtained data. The results of this research are summarized as follows. While the WE of the zones located in the fringe of Changwon square were generally got a high score as over 42, other zones located in detached or row house area were evaluated relatively highly bad. Findings from this research will help in determining the zone required improvement of WEs or easy access to main destination such as a park, shopping center, school, etc. and also selecting variables of WEs, needed an intensive improvement, in the selected zone after comparing the results of field and questionnaire survey. Furthermore, those will be used as a means of decision making support for planing, designing and maintaining of WEs to promote people's physical activity in their daily lives.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.691-697
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• 2015

In this paper, an embedded EM sensor was researched to estimate prestressing force of PS tendon in PSC girder. Recent methodologies for managing prestressing force loss were staying on verifying a applying prestressing force under construction, namely the loss management can not be controlled after construction. To estimate the tensile force of PS tendon during lifetime of PSC girder, this research proposed a bobbin-type embedded EM sensor that can be embedded in PSC girder is designed and fabricated considering the shape properties of anchorage zone and sheath. To verify the proposed sensor, a small PSC girder test was performed. The embedded EM sensor was connected to a sheath and anchor block, and the concrete was poured. After curing, the change of the permeability of PS tendon under tensile forces of 200, 710, 1070, 1300kN was measured using embedded EM sensor. The permeability of PS tendon had decreased according to the increment of applied tensile force. Also it is confirmed that the change of permeability due to applied tensile force could resolve the applied tensile force values. As a result, proposed embedded EM sensor could be embed into the PSC girder and it could be used to estimate the tensile force variation during lifetime of PSC girder.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.4
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• pp.369-374
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• 2015

In this paper, an EM sensing based prestressing force estimation method is proposed, in which it can estimate tensile force of PS tendon for PSC girder. The PSC girder has more improved performance than the general concrete girder by introducing the prestressing to the concrete. Thus the PSC girder bridge is widely constructed due to its high performance and low cost. However, the prestressing force has not been managed nevertheless it is major factor for the maintenance of the PSC girder bridge. The prestressing force was just measured during construction using jacking device and after that, it can not be managed. For this reason, this paper proposes a tensile force estimation method of PS tendon based on EM sensor. The permeability of ferroelectric material is changed according to the induced stress to the material, in which it can be measured using EM sensor. To measure the permeability of PS tendon, the EM sensor was fabricated and verified by performing the MTS test. The test was performed using 7-wire steel tendon under the 0, 40, 80, 120, 160, 200 KN of tensile force. The permeability of PS tendon was gradually decreased according to the increasement of tensile force. The regression method was used to find the relation between permeability and stress. As a result, the permeability has linear relation with the tensile force of PS tendon and the pre-stressing force can be estimated by the derived estimation equation.

• Korean Journal of Environment and Ecology
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• v.20 no.3
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• pp.340-344
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• 2006

The objective of this paper was to investigate the potential of road-crossing structures as biological corridors that can overcome wildlife habitat fragmentation caused by road construction. Snow tracking on animal trace adjacent to and under bridges, underpasses, and culverts of eight rural highways in Korea was carried out. A total 89 structures were monitored and the results follow. First, the probability of road crossing increases with the increasing cross sectional size of crossing structures. Second, small to medium sized carnivores such as raccoon dog, leopard cat, and Siberian weasel use all types of structures. Finally, water deer, or large herbivore crossed only under bridges. Consequently, further studies are necessary to identify suitable types of road crossing structures that can mitigate the probability of road-kills and habitat fragmentation of water deer.

• Korean Journal of Environment and Ecology
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• v.20 no.3
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• pp.299-310
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• 2006

The germination period, the germination under different saline concentration and temperature condition, the survival percent several halophytes in cross-transplanting experiment of marsh type and the soil environment factor of five dominant species were investigated on the halophytes population formation strategies on the salt marsh of Mankyeong river estuary from February to October 2005. In terms of germination, Suaeda japonica appeared first followed by Aster tyipolium Salicornia herbacda, Atriplex gmelini and Suaeda asparagoides. The germination percent on the humidify conditions and saline concentrations of halophytes were that Suaeda japonica germinated well under inundation conditions, high temperature and low salinity; Salicornia herbacda under high salinity; Aster tripolium and Atriplex gmelini under dry or inundation conditions, and Suaeda aspar agoides under dry conditions and high salinity. The survival percent in cross-transplanting experiment of five halophytes were high with Suaeda japonica in the low marsh; Salicornia herbacda, Aster tripolium and Atriplex gmelini in the mid marsh, Suaeda asparagoides in the high marsh. The soil properties were similar for the five halophytes, but soil texture appeared high in order of silt, sand and clay. These results suggested that population formation strategies of five halphytes. Suaeda iaponica was distributed in the low tidal marsh, Salicornia herbacda, Aster tripolium, Atriplex gmelini in the mid tidal marsh and Suaeda asparagoides in the high tidal marsh.