• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.197-201
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• 2008

Conceptual cost estimates for domestic highway projects have generally been conducted using governmental unit-price references. Inaccuracies in governmental unit-price data has repeatedly addressed in the Korean construction industry which often lead to poor decision making and cost management practices. Thus, needs for developing a better way of conceptual cost estimating has been widely recognized. This research is considered as the first step in developing such model using real-world cost data based on actual construction activities. The data analyzed in this paper includes 41 P.S.C (Prestressed Concrete) Box bridges which broke into 4 categories based on construction methods such as I.L.M(Incremental Launching Method), M.S.S(Movable Scaffolding System), F.S.M(Full Staging Method), and F.C.M(Free Cantilever Method). Actual design documents; including actual cost estimating documents, drawings and specifications were carefully reviewed to effectively break down cost structures for PSC girder bridges. Among more than 40 cost categories for each P.S.C girder bridge type, 7 of them were identified which accounted for more than 95% of total construction cost (ILM: 99.47%, MSS: 99.22%, FSM: 98.18%, and FCM: 98.12%). In order to validate the clustering of cost categories, the variation of each cost category has been investigated which resulted in between -1.16 % and 0.59%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.205-211
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• 2015

Most of the sulfur is obtained from desulfurization of natural gas and crude oil. In Korea, more than 120 tons of sulfur are produced by refinery, and about 50 % of the produced sulfur is used as a raw material for the production of fertilizer and sulfuric acid. Modified sulfur is manufactured from excessive sulfur that could be used to improve concrete properties, and this study evaluated concrete strength and durability that contains modified sulfur. Flexural and compressive strengths of concrete with sulfur modified polymer were comparable to those of OPC concrete with mixing water at similar temperatures, while the strengths increased a little as mixing water temperature increased. It was also confirmed that the resistance to freeze-thaw damage was more dependent on entrained air characteristics obtained by a proper use of air entraining agent than on the use of sulfur modified polymer. When concrete was immersed in 5 % sulfuric acid, the rate of reduction in compressive strength of OPC concrete was less than 1/4 of the strength reduction of concrete with sulfur modified polymer. Also, the resistance of concrete with sulfur modified polymer to scaling due to the use of de-icing salt was evaluated as Class 1, while that of OPC concrete was evaluated as Class 4, as aggregates were exposed. Accordingly, it is believed that sulfur modified polymer could be effectively used for bridge deck concrete since sulfur modified polymer improves the durability of concrete.

• Journal of the Korean Geographical Society
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• v.38 no.2
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• pp.156-172
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• 2003

In this paper we identify that there are High Higher surfaces(HH-surface) around Jeongdongjin and Daejin area where Higher surfaces(H-surface) of marine terrace are formed on a large scale. On the basis of an altitude of the ancient shoreline of the marine terraces, geomorphic surfaces can be classified into HH I (140m a.s.l), HH II (110m a.s.l), H I (90m a.s.l), H II (70m a.s.l), M (40m a.s.l), L I (25m a.s.l) and L II (10m a.s.l). Besides, we identify that the lowest surfaces(5~6m a.s.l) are found extensively in the research area which are assumed to be formed in the Holocene. Considering that the formation mechanism of the marine terraces in the research area is similar to that of the marine terraces at both Campo area in the south east coastal region of Korea md the thalassostatic terraces of Osip River in Samchuk in a short distance from the research area, we can assume that the HH-surfaces in both areas were formed in the same period. Based on the fact that L I- surface was formed on the Last Interglacial Stage of MIS 5, we can infer that M- was formed in MIS 7, H I- in MIS 9, H II- in MIS 11, HH I- in MIS 13 and HH II- in MIS 15. The reason for that H-surfaces, similar to those at Gampo area, to remain on a large scale is that the Holsteinian Interglacial continued for a long period of time and at that time there was a large wave-cut platform in the vicinity of the shoreline.

• Korean Journal of Environment and Ecology
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• v.24 no.4
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• pp.395-405
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• 2010

This study was carried out to offer basic data to minimize the indiscreet development and damage of coastal wetlands through an evaluation from an ecological standpoint highlighting the importance of the coastal wetland in South Gyeongsang Province, Korea. The result of the macrobenthos survey for the coastal wetland assessment showed that Dongdal and Hwasan-ri, Yongnam-myeon, and Tongyeong city had the largest species number; Oegan-ri and Naegan-ri, Geoje-myeon, and Geoje city had the largest population and biomass; and Miryong-ri, Samsan-myeon, Goseong-gun had the highest species diversity. In the halophytes survey, Imyeong-ri, Jinjeon-myeon, Masan city and Oegan-ri and Naegan-ri, Geoje-myeon, Geoje city had the large character species and companion species. The evaluation results of the ecological values of the coastal wetlands were categorized into five grades based on the field surveys, and the sedimentary environment factor in the case of Danghang-ri, Hoehwa-myeon, and Goseong-gun; Miryong-ri, Samsan-myeon, Goseong-gun; Guho-ri, Gonyang-myeon, Sacheon city; Sulsang-ri Yangpo-ri, Jingyo-myeon, Hadong-gun; and Seokpyeong-ri, Idong-myeon, Namhae-gun, were appraised at the highest rating of grade II. The halophytes factor in the case of Imyeong-ri, Jinjeon-myeon, Masan city, Dongdal-ri and Hwasan-ri, Yongnam-myeon, Tongyeong city and Oegan-ri and Naegan-ri, Geoje-myeon, Geoje city, were highly evaluated as grade II. The macrobenthos factor in the case of Imyeong-ri, Jinjeon-myeon, Masan city and Oegan-ri and Naegan-ri, Geoje-myeon, Geoje city was highly evaluated as grade II. The final evaluation grade was calculated by the mean values of three evaluation factors, and Imyeong-ri, Jinjeon-myeon, Masan city and Oegan-ri and Naegan-ri, Geoje-myeon, and Geoje city had the highest rating of II. On the other hand, Seokpyeong-ri, Idong-myeon, Namhae-gun had the lowest rating of IV. These locations will require future research to survey and monitor the coastal wetland ecosystems by season, in addition to the construction of the GIS-based wetland information system with a view to manage the coastal wetlands.