• Journal of Digital Convergence
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• v.13 no.8
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• pp.153-160
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• 2015

The domestic stock market has been subjected to a major change since the September 1997 financial crisis. Foreign capital came repeat themselves in the stock market and bond market, foreign exchange market opening up domestic financial markets after the financial crisis. The domestic stock market has been most affected by domestic capital before the financial crisis. But it has been receiving an absolute influenced by foreign capital after the financial crisis. The purpose of this study is to analyze the trends in the two sections that look at any changes in the volatility of the KOSPI appears after the crisis. To this, obtained a daily weekly monthly normal distribution and kurtosis, skewness degree it should be analyze the tilt phenomenon and variability of the two intervals. This study also predict the future movement of the domestic stock market Based on this, look at the difference between the two sections. Analysis result, after the financial crisis change width has a reduction but direction of the KOSPI has appeared relatively distinct in the medium to long term. Based on this future market seems desirable the mid- to long-term investment looking for direction.

• Korean Journal of Environment and Ecology
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• v.20 no.3
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• pp.281-288
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• 2006

The purpose of this study was to investigate the distribution status and environmental index of the naturalized plants and exotic plants In the 16 sites in Gayasan National Park from March to October 2004. The exotic plants were recorded as 88 taxa, 39 families, 72 genera, 82 species, 5 varieties and 1 form. The naturalized plants among the exotic plants were certified as 47 taxa. The Naturalized Ratio (NR) was 4.06% and the Urbanization Index (UI) was 17,74% in area of Gayasan National Park. The naturalized plants were distributed around the region that had accepted artificial disturbance however, it was so difficult to identify distribution of naturalized plants in the conserved area as well as natural vegetation without artificial turbulence. The naturalized plants appeared as almost all speciesas 37 taxa (72%) which both originated from Europe and North America. Although a national degree for integrated management plans of exotic plants is needed, distribution and steady management of exotic plants in Gayasan National Park are playing an important role in conservation and protection of natural species.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.2
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• pp.125-145
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• 2001

To compare the stress distribution patterns between cement-retained and screw-retained implant supported fixed prostheses according to four different abutment types, a three dimensional finite element analysis was performed. The hypothetical three unit fixed partial denture case was modelled on the three implants(10mm length and 3.75 diameter) in mandibular bone. Four angles of implantation(vertical, 10, 15 and 20 degree inclined mesially) were created and three different directions of force (vertical, oblique, horizontal) were applied at the center of the second premolar and distal end of the first molar for each cases. Within the limits of this study, the results were as follows, 1. In vertically installed cases, the more stress was concentrated at upper components, but mesially inclined cases, the more stress was concentrated at cortical bone. 2, The more inclined mesially the more stress was observed, especially at cortical bone. 3. The cement-retained models showed lower principal stress and more even stress distribution than the screw-retained models. 4. The similar stress distribution pattern was showed in model 1 and model 2, model 3 and model 4. 5. The more stress was observed when the loads were applied at the distal end of 1st molar than the center of 2nd premolar. 6 The fixture and the model as a whole, lesser stress values were observed when vertical loads were applied as compared to horizontal and oblique loads.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.31-38
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• 2008

The primary objective of this study was to evaluate the variation of the molecular size distribution by granular activated carbon (GAC) adsorption. GAC adsorption was assessed by using the rapid small-scale column test (RSSCT) and high-performance size-exclusion chromatography (HPSEC) was used to analyze the molecular size distribution (MSD) in the effluent of GAC column. RSSCT study suggested that GAC adsorption exhibited excellent interrelationship between dissolved organic carbon (DOC) breakthrough and MSD as function of bed volumes passed. After GAC treatment, the nonadsorbable fraction which was about 25percents of influent DOC corresponded to the hydrophilic (HPI) natural organic carbon (NOM) of NOM fractions and was composed entirely of <300 molecular weight (MW) in the HPSEC at the initial stage of the RSSCT operation. The dominant MW fraction in the source water was 1,000~5,000daltons. At the bed volumes 2,500, MW <500 of GAC treated water was risen rather than it of source water. After the bed volumes 7,300 of operation, the MW 1,000~3,000 fraction was closed to about 80percents of DOC found in the GAC influent. The Number-average molecular weight (Mn) value determined using HPSEC for the effluent of GAC column was gently increased as DOC breakthrough progress. The quotient p(Mw/Mn) can be used to estimate the degree of polydispersity was shown greatest value for the GAC effluent at the initial stage of the RSSCT operation.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.3
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• pp.287-297
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• 2014

It is important to predict chlorine decay with different water purification processes and distribution pipeline materials, especially because chlorine decay is in direct relationship with the stability of water quality. The degree of chlorine decay may affect the water quality at the end of the pipeline: it may produce disinfection by-products or cause unpleasant odor and taste. Sand filtrate and dual media filtrate were used as influents in this study, and cast iron (CI), polyvinyl chloride (PVC), and stainless steel (SS) were used as pipeline materials. The results were analyzed via chlorine decay models by comparing the experimental and model parameters. The models were then used to estimate rechlorination time and chlorine decay time. The results indicated that water quality (e.g. organic matter and alkalinity) and pipeline materials were important factors influencing bulk decay and sand filtrate exhibited greater chlorine decay than dual media filtrate. The two-component second-order model was more applicable than the first decay model, and it enabled the estimation of chlorine decay time. These results are expected to provide the basis for modeling chlorine decay of different water purification processes and pipeline materials.

• Korean Journal of Environmental Biology
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• v.19 no.4
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• pp.239-247
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• 2001

The Herbal Vegetation on Running Waterside in the Main Stream of Genmho River, Daegu and Gyeongsanbuk-do, Korea was investigated by the methodology from June to August of 1994 and analyzed distribution characteristics of vegetation that was related Water Environment. The vegetation is divided into 6 communities of Persicaria sieboldi-Persicaria hydropiper community, Persicaria thunbergii community, Impatiens textori community, Zizania latifoloa community, Phragmites communis community and Echinochloa crus-galli var. oryzicola community. A BOD and COD that indicate degree of contamination in water were showed 0.9 ppm and 1.6 ppm at upstream and 15.9 ppm and 24.8 ppm at downstream, respectively. The distribution patterns of vegetation have dominated by Impatiens textoricommunity in the upstream, by Persicaria sieboldi-Persicaria hydropiper community from upstream to mid-upstream, by Persicaria thunbergii community from upstream to midstream, by Zizania latifoloa community from nidstream to mid-downstream and by Phragmites communis community and Echinochloa crus-galli var. oryzicola community from mid-downstream to downstream. Especially, I suggested that Persicaria sieboldi-Persicaria hydropiper community and Persicaria thunbergii community will use as biotic indicator in water environment.

• Journal of Ocean Engineering and Technology
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• v.17 no.2
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• pp.34-39
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• 2003

Recent deepwater offshore structures in the Gulf of Mexico utilize butt welded tubular joints. Application of a welded tubular joint includes tendons, production risers, and steel catenary risers. Fatigue life assessment of these joints becomes more critical, as the structures to which they are attached are allowed to undergo cyclic and sometimes large displacements around an anchored position. Estimation of the fatigue behavior of these tubular members in the design stage is generally condrcted by using S-N curves, as specified in the codeds and standards. Applying the stress concentration factor of the welded structure to the S-N approach often results in a very conservative assessment, because the stress field acting on the tubular has a non-uniform distribution through the thickness. Fatigue life analysis using fracture mechanics has been applied in the design of the catenary risers. This technology enables the engineer to establish proper requirements on weld quality and inspection acceptance criteria to assure satisfactory structural integrity during its design life. It also provides guidance on proper design curves and a methodology for accounting for the effects of non-uniform stress distribution through the wall thickness. Still, there is inconsistency when designing tubular joints using a conventional S-N approach and when specifying weld flaw acceptance criteria using fracture mechanics approach. This study developed fatigue curves that are consistent with both the S-N approach and the fracture mechanics approach. Accounting for non-uniform stress distribution and threshold stress intensity factor were key parameters in relating both approaches. A series of S-N curves, generated from the fracture mechanics approach, were compared to the existing S-N curves. For flat plate butt joint, the S-N curve generated from fracture mechanics matches with the IIW class 100 curve when initial crack depth was 0.5 mm (0.02 ). The new curves for tubular joint agree very well with the experimental results. The comparison also indicated the degree of conservatism built into the API X design curve.

• The Korean Journal of Ecology
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• v.7 no.3
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• pp.132-157
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• 1983

This study was performed to investigated the flora and vegetation of Kokum-do island from July 1982 thru December 1983; and the findings hereof are summarized as follows: The flora investigated thereform comprises 737 species whih are classified into 128 families, 466 genera, 651 species, 79 varieties and 7 formae; and those which are worthy of close attention among the same include such endemic species of Korea as Celtis choseniana, Corylopsis coreana, Carpinus tschonoskii var. eximia and Tricyrtis dilatata, and a few plants, to be distributed in the north, such as Lilium distichum, Girardinia cuspidata and Orostachys sikokianus. Now that the said island belongs to the warm temperate zone, the distribution thereof consists of 120 species of evergreen plants including 74 species of evergreen broadleaf trees. The rich distribution of evergreen broadleaf trees in the island is thanks to the plantation thereof by the public organizations for scenic beauty. The destruction of flora in this island was caused by felling, fire nization and other human activities around 1940, and in particular, has been correlated with the population densiity of Yonhong-do, Sanghwa-do, and Hahwado islets; and that of top soil and ground vegetation in he quarry area of Ojon-ri town resulted from the collection of natural rocks an stones. It is evaluated as necessary that such evergreen broadleaf trees as Castanopsis cuspidata var. thunbergii, Machillus thunbergii and Ligustrum japonicum of Hyongje-do. Chun-do, Tok-do, Taech'wi-do, and Soch'wi-do islets, andPhyllostachys bambusoides, Caesalpinia japonica and Albizzia julibirssin of Kokum-do island, and Machillus thunbergii of Hongryon-ri town be under protection. The average DGN of the whole archipelago proves to be 5.84, which shows the tendency of the inverse proportion to the number of resident population per unit area. The pteridophyta distributed in this island comprises 39 species, and the coefficient of cryptogam as to the destruction of vegetation shows a high value of 1.4 which is regarded as indicating the diversified distribution of pteridophyta, forestbed shade plants under the forestbeds of some wellpreserved lots of this island. The naturalized plants, distributed in this island, were found out comprising a total of 23 species, and the Urbanization Index(UI) as to the destruction degree of natural vegetatioin shows a low value of 20.9.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.425-432
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• 2004

Large studs were suggested not only for the design of steel-concrete composite bridges with simplified sections but also for the shear connection in precast decks requiring uniform distribution of shear pockets. Based on the push-out test results on studs with diameters of more than 25 mm, partial composite beams with 40%-degree shear connection were fabricated, and static tests were performed. The ultimate strength and horizontal shear load redistribution of partial composite beams, which have parameters of stud shank diameters and distribution, were evaluated, and group failure in the shear span was observed. Since the flexural strength of composite beams are dependent on the strength of their shear connection, the strength of the stud connection was estimated and it showed considerably higher shear strength. From the load-slip curves, the sufficient ductility and load redistribution of large studs were confirmed. Uniformly distributed large studs can provide proper ultimate behavior of composite beams.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.130-135
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• 2010

In this study, the performance improvement of epoxy resin system had been tried by the improvement of particle size distribution and globularization of filler using polymerization method. From the results of particle size distribution measurement, the polydispersity value of reformed filler was 1.04 and that of silica flour before reformation was 2.6, it could be confirmed that the particle size uniformity of reformed filler had been improved greatly and the shape of particle was globular. Compatibility between monomer and silica was improved remarkably with the silanization pretreatment of silica flour. From the results of degree of crosslinking test, it could be confirmed that the binding structure of reformed filler was 3-dimensional net structure. And it could be also confirmed that the fluidness was improved at the casting of epoxy resin with reformed filler. From the above results, it could be concluded that the reformation of filler with the improvement of particle size distribution and globularization was very successful method to improve the performance of cast epoxy resin system.