• Journal of Periodontal and Implant Science
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• 제26권2호
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• pp.429-447
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• 1996

Transforming growth factor $-{\beta}$ is one of the polypeptide growth factors that mediate the activity of mesenchymal cells and regulate wound healing process via cell proliferation, migration and extracellular matrix formation. The purposes of this study is to evaluate the effects of transforming growth factor $-{\beta}$ on the protein synthetic activity of human periodontal ligament cells and human gingival fibroblasts. The cells which were prepared were primary cultured gingival fibroblasts and periodontal ligament cells from humans, and the fourth or sixth subpassage were used in the experiments. Cells were seeded and at a confluent state, 0, 0.5, I, 2.5, 5, 10 ng/ml $TGF-{\beta}$ and $2{\mu]Ci/ml\;[^3H]$ proline were added to the cells and cultured for 24 hours. Then, 1 and 5 ng/ml concentrations were selected and added to confluent cells and cultured for 24 and 48 hours. They were labeled with $2{\mu}Ci/ml\;[^3H]$ proline for 24 hours and a collagen assay was done by the Peterkofsky and Diegelman method. The results were presented as the mean disintegration per minute (dpm) per well and S.D. of four determinations, The results were as follows. : The total protein, collagen and noncollagenous protein synthesis in periodontal ligament cells and gingival fibroblasts were increased dose- dependently by transforming growth factor-p to 2.5-5 ng/ml concentration and decreased at 10 ng/ml concentration. The percent of collagen was slightly changed according to the concentration of transforming growth factor-po The effect of transforming growth $factor-{\beta}$ was not specific for collagen synthesis since it increased the total, noncollagenous and collagenous protein, simultaneously. In the comparison of protein synthetic activity between the human periodontal ligament cells and human gingival fibroblasts, the human gingival fibroblasts had higher activities than the human periodontal ligament cells at all times and concentrations of $TGF-{\beta}$. In the comparison of protein synthetic activity between the 24 hour effect and the 48 hour effect of $TGF-{\beta}$, the 48 hour cultured cells' synthetic activity decreased more than the 24 hour cultured cells at human periodontal ligament cells and human gingival fibroblasts. In conclusion, $TGF-{\beta}$ has important roles in the stimulation of protein synthesis in human periodontal ligament cells and human gingival fibroblasts. Thus, it may be useful for clinical application in periodontal regenerative procedures.

• Structural Engineering and Mechanics
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• 제23권6호
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• pp.651-674
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• 2006

The fatigue cracks initiate and propagate in the Armored Vehicle Launch Bridge (AVLB) components, especially like the splice doubler angle, splice plate, and bottom chord, due to the cyclic loading by repeated AVLB-launchings and tank-crossings. In this study, laboratory fatigue tests were conducted on six aluminum 2014-T6, four aluminum 7050-T76511, and four ASTM A36 steel compact-tension specimens to evaluate the crack growth behavior of the materials used for the components. The experimental results provide the relationship (Paris Law) between crack growth rate, da/dn, and stress intensity range, ${\Delta}K$, whose material dependent constants C and m can later be used in the life estimation of the components. Finite Element Method (FEM) was used to obtain the stress intensity factor, K, of the components with cracks. Because of the complexity of loading conditions and component geometry, several assumptions and simplifications are made in the FEM modeling. The FEM results, along with the results obtained from laboratory fatigue tests, are then utilized to estimate critical crack length and remaining life of the components.

• 한국정밀공학회지
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• 제14권7호
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• pp.82-90
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• 1997

When a structure is made by the process of forging, it has the different mechanical properties from those it has before the process. This study is based on the crack closure phenomenon of the crack growth behavior of forged AI7050-T7452. The specimens were prepared in three kinds of forging ratio in order to find out the effects of crack closure on the forged material and compare the crack growth behavior with not-forged aluminum. COD method and strain gage method were used in measuring the crack closure stress and the results from those methods were compared each other. FEM analysis was applied to verify the effective stress intensity factor range by the superposition of the crack closure load to the crack tip. In the result of this study, the crack closure stress decreased with increasing the forging ratio due to the finer grain size and the brittle manner.

• 산경연구논집
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• 제10권12호
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• pp.43-55
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• 2019

Purpose : With the proliferation of O2O platform services that combine offline and online services, many startups are fiercely competing to lead services in the O2O service market. While the prospects for growth in the O2O service market are optimistic because of the close convenience to life, startups can achieve corporate performance only through close cooperation and partnership with suppliers. The purpose of this study is to verify the effect of O2O-based startups' and suppliers' cooperation in supply chain management on SCM performance through supply chain partnerships and startup satisfaction with suppliers. Research design, data, methodology : Data were collected from O2O service-based startups and hypotheses were verified through frequency analysis, exploratory factor analysis, reliability analysis, confirmatory factor analysis, feasibility analysis, and structural equation path analysis. In addition, the mediating effects of supply chain partnerships and startup satisfaction on suppliers were verified. Results : As a result of this study, IT utilization of the O2O startup cooperation method affects the financial perspective of supply chain partnership and SCM performance. The contract implementation of the cooperation method had an impact on the financial and innovation growth perspectives of the SCM performance, and the communication of the cooperation method had an effect on the supply chain partnership, startup satisfaction in the supply chain, and the innovation growth perspective of the SCM performance. Supply chain partnerships had an impact on the financial, innovation growth, and customer perspectives of SCM performance and startup satisfaction within the supply chain had a significant effect on innovation growth and customer perspectives. Conclusions : The implications of this study identified the factors that can improve SCM performance through the cooperation method of O2O startup, supply chain partnership and startup satisfaction with suppliers, and it is significant that the causal relationship was identified by the structural model through the supply chain cooperation factors derived by characteristics. Based on the empirical results, as the services of O2O startups grow, it is expected that empirical research and practical activation of academia should be considered as important in the cooperation of the supply chain.

• The Journal of Asian Finance, Economics and Business
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• 제7권7호
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• pp.251-260
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• 2020

The purpose of this paper is to investigate the impact of total factor productivity (TFP), institutional quality, and interactive variable between them on economic growth in 13 low-middle income countries in Asia for the period 2000-2018. The paper uses the difference Generalized Method of Moments (GMM) to explore the dataset provided by the World Bank. The empirical results show that TFP and the interactive variable positively impact on the economic growth, while the institutional determinants have a negative influence. The negative effect is explained by the weak institutions in these low-middle income countries. The findings of the study suggest two points. First, the government should continue to improve TFP, which is associated with the application of technical advances, technological innovations, improvement of management methods, and skilled workers. Second, far more important, is that the authorities should pay special attention to implement institutional reform and strengthen the governance in the future. The successful experiences from Japan, Korea and Singapore will help other governments in Asian low-middle income countries to build developmental state. Probably, the developmental state actively interfere in the market to promote and realize the development goals. By doing so, these economies might overcome the so-called "middle-income trap".

• 한방안이비인후피부과학회지
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• 제20권1호통권32호
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• pp.27-37
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• 2007

Background and Objective : Psoriasis is a chronic skin disease characterized by angiogenesis. It has been reported that growth factor as vascular endothelial growth factor (VEGF) and insulin-like growth factor (IGF)-II are overexpressed in psoriatic epidermis. This stydy was carried out for whether SB extracts have an anti-angiogenic effect for angiogenic factor. Method : To investigate the inhibitory effect of VEGF expression by the SB extracts, we performed MTS assay, western blots using HaCaT cells. HaCaT cells were pretreated with SB extracts for 1 hour followed by treatment with IGF-II. Result : SB extracts significantly reduced IGF-II induced HIF-1 ${\alpha}$ protein level via p53 and MAPK pathway in HaCaT cells. Also, SB extracts inhibited IGF-II induced VEGF mRNA and protein expression levels in the HaCaT keratinocytes. Conclusion : These results suggest that inhibition of HIF-1 ${\alpha}$ and VEGF expressions by SB extracts contributes to the anti-angiogenic effects.

• 한국유기농업학회지
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• 제20권4호
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• pp.543-561
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• 2012

This work is for reasonable valuation method of environmental-friendly and organic company. Reasonable valuation method is principal for the sound development, the reasonable investment and the growth of stock market. This study proposes valid valuation and method for environmental-friendly and organic company. The author selected 4 companies from certificate list of environmental-friendly and organic food and LOHAS (Lifestyles Of Health And Sustainability) food of Korean standards association. Applying financial audit report of 5 years, the author output 5 variables from each companies by using Growth Option model of Real Option model. And the author valuated companies by adding option value calculated with these variables and residual value discounted with cash flow discounted method. Company values from ROV model were 1.71 time higher than DCF model. This results show that the value of environmental-friendly and organic food company may own high option premium, that is the growth factor.

• Structural Engineering and Mechanics
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• 제57권1호
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• pp.65-89
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• 2016

This paper presents the development of methodologies using Extended Finite Element Method (XFEM) for cracked unstiffened and concentric stiffened panels subjected to constant amplitude tensile fatigue loading. XFEM formulations such as level set representation of crack, element stiffness matrix formulation and numerical integration are presented and implemented in MATLAB software. Stiffeners of the stiffened panels are modelled using truss elements such that nodes of the panel and nodes of the stiffener coincide. Stress Intensity Factor (SIF) is computed from the solutions of XFEM using domain form of interaction integral. Paris's crack growth law is used to compute the number of fatigue cycles up to failure. Numerical investigations are carried out to model the crack growth, estimate the remaining life and generate damage tolerant curves. From the studies, it is observed that (i) there is a considerable increase in fatigue life of stiffened panels compared to unstiffened panels and (ii) as the external applied stress is decreasing number of fatigue life cycles taken by the component is increasing.

• 한국정밀공학회지
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• 제16권2호통권95호
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• pp.225-233
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• 1999

This paper describes a versatile finite element technique which has been used to investigate of wide range of structural defects of practical importance. The procedure automatically remeshes the three-dimensional finite element model during the stages of crack growth. Problems analyzed to date include the surface cracks in leak-before-break situations, the development of quarter-elliptical corner defects, planar semi-elliptical surface defects and the fatigue growth of defects.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.133-141
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• 2002

This paper describes a versatile finite element technique which has been used to investigate wide range of structural defects of practical importance. The procedure automatically remeshes the three-dimensional finite element model during the stages of crack growth. Problems include the surface cracks in leak-before-break situations, the shape development of multiple surface defects.