• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.2
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• pp.43-51
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• 2011

Probabilistic seismic hazard analysis (PSHA), which can effectively apply inevitable uncertainties in seismic data, considers a number of seismotectonic models and attenuation equations. The calculated hazard by PSHA is generally a value dependent on peak ground acceleration (PGA) and expresses the value as an annual exceedance probability. To represent the uncertainty range of a hazard which has occurred using various seismic data, a hazard curve figure shows both a mean curve and percentile curves (15, 50, and 85). The percentile performs an important role in that it indicates the uncertainty range of the calculated hazard, could be calculated using various methods by the relation of the weight and hazard. This study using the weight accumulation method, the weighted hazard method, the maximum likelihood method, and the moment method, has calculated the percentile of the computed hazard by PSHA on the Shinuljin 1, 2 site. The calculated percentile using the weight accumulation method, the weighted hazard method, and the maximum likelihood method, have similar trends and represent the range of all computed hazards by PSHA. The calculated percentile using the moment method effectively showed the range of hazards at the source which includes a site. This study suggests the moment method as effective percentile calculation method considering the almost same mean hazard for the seismotectonic model and a source which includes a site.

• Korean Journal of Construction Engineering and Management
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• v.14 no.3
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• pp.107-114
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• 2013

The interest in traditional Korean housing has greatly increasing in Korean housing market. However, it is difficult to wildly disseminate for a high construction cost reason. In order to effectively facilitate the Hanok construction, Korean government has initiated a project that develops a new style Korean housing, which meets the requirements of low cost and modernized life style. Cost of building is mainly affected by materials and construction methods. Hanok has some special commodities those significantly impact the cost. In order to effectively cut down the costs, well-organized planning for costs is very important. Also, improving the productivity by utilizing new materials and methods can result in cost down. In this context, this paper compared and analyzed two different types of Korean housing; one is a modernized Korean house which used new materials and methods, the other is a traditional Korean house which was build up by purely traditional methods. Productivity has also been compared and analyzed for 5 major commodities between two types of models. Based on these comparative data, effect of cost down by new model has been analyzed. As a result it is confirmed that by using the new materials and methods could highly effect to increasing productivity and cost down. Especially, the cost of Roofing have been more influenced by using new material while the Wood and Finishes have been influenced by new construction method. Construction cost of Foundation (Earthwork, Concrete, Masonry) and Openings were influenced both factors, changing of materials and methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.718-727
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• 2011

This research aims to empirically investigate into the relationship between venture entrepreneurs' social network and their social competence to utilize the network, which is known to help overcome the weaknesses of small-and-medium-sized ventures. An analysis was made of SEM set up with 211 entrepreneurs' responses, and the following are the findings from the analysis. First, venture entrepreneurs' networking ability has a significant, strong and positive effect on weak tie of their social network(${\beta}$=.527, C.R.=3.626), strong tie(${\beta}$=.594, C.R.=3.969), and the network centrality(${\beta}$=.418, C.R.=4.884). Second, their social astuteness also has a significant and positive effect on weak tie(${\beta}$=.192, C.R.=1.701), strong tie(${\beta}$=.269, C.R.=2.509) and the network centrality(${\beta}$=.228, p=2.283). Third, their interpersonal influence has a significant but negative effect only on strong tie(${\beta}$=-.264, C.R.=-1.862) and the network centrality(${\beta}$=-.394, C.R.=-2.914). Lastly, their apparent sincerity has no significant effect on the subordinate factors of social network. This research has not just empirically analyzed the relationship between the entrepreneurs' social network and their social competence. But also, results of the research provide practical and detailed information to entrepreneurs of small and medium ventures. Moreover, the research is significant in that it has suggested and empirically analyzed the concept of political competence, which is a concrete substance of social competence, and that it has offered theoretical foundations for future researches, which will tackle the issue of the entrepreneurs' competence in the sphere of entrepreneurship.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.67-74
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• 2010

A variation of temperature acting on a RC roof slab causes a change of stress in concrete since it expands during summer and is compressed during winter. This behavior repeats annually and makes an affection to the structural capacity of member for both serviceability and ultimate level. In this paper, a cyclic temperature loading variation is calculated by analyzing the weather data of Korea for 20 years. In addition, an experimental work is planned to find the long term effect of temperature variation. Six RC slab are made with same dimension. Test parameters are loading duration (10, 20, 30 year) and whether it has pre-damage or not. Observation of stiffness variations according to cyclic loading period shows that the serious stiffness drop happens after 10 year's cyclic loading at summer while after 30 year's loading at winter. From the fracture test about slabs damaged by long term cyclic loading, however, the capacity of member such as initial stiffness and maximum strength were not changed except yield strength according to the period of long term cyclic loading. The yield strength tends to decrease after 20 year's cyclic loading.

• Journal of Navigation and Port Research
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• v.37 no.6
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• pp.727-732
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• 2013

This primary purpose of this study is to suggest strategies for developing the Gwangyagn region as a logistics city. In order to achieve such purpose, the following methodology is used. First, the literature survey on papers, related-organization's homepage, reports and journals related to Gwangyang Bay and Gwangyang port. Second, an pilot survey and field survey for suggesting SWOT analysis are carried out. Finally, questionnaire survey using a AHP analysis technique is distributed and analyzed. The strategies for developing as a logistics city are suggested as followings. First, ST strategy such as the development of the international hinterland logistics center related to the port logistics function is considered as the most important factor and followed by ST strategy, WT strategy and WO strategy. Second, creation of the revenue-creating logistics business model is to be considered as the most important factor and followed by development of the international hinterland logistics center related to the port logistics function, operation of the logistics center, creating high value-added of free trade area etc. For further research, more concrete and empirical study have to be carried out.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.144-152
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• 2016

This paper focuses on the experimental study for investigating the performance for lap splice of hooked or headed reinforcement in beam with different depths. In the experiment, seven specimens, with its variables as the lap length of headed or hooked bar, the existence of stirrups, etc., was manufactured. Bending test was conducted. Lap strengths by test were compared with the theoretical model based on KCI2012. The result showed that the cracks at failure mode occurred along the axial direction to a headed bar. The initial stiffness and the stiffness after initial crack were similar for all specimens. For HS series specimens without stirrups, a 25% increase in lap length was increased 11.8~18.1% maximum strengths. For HH series specimens without stirrups, a increase in lap length did not affect the maximum strengths because of the pryout failure of headed bar. For HS series specimens, the theoretical lap strengths based on KCI2012 considering the B grade lap and the reduction factor for stirrup were evaluated. They are smaller than the test strengths and can ensure the safety in terms of strength capacity. For HH series specimens, the stirrups in the lap zone are needed to prevent the pryout behaviour of headed bar.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.193-204
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• 2007

Deformation strength($S_D$) is a property which shows relatively good correlation with rut resistance of asphalt mixtures at high temperature. The Asphalt Pavement Analyzer (APA) is widely used as an equipment for estimating rut resistance of asphalt mixtures. The APA was used as corresponding property of the $S_D$ to estimate rutting resistance of asphalt mixtures. Many data were collected to establish the correlation of $S_D$ with APA. For $S_D$ test, the specimen is submerged into the $60^{\circ}C$ water for 30 minutes before applying a vertical load at the speed of 50mm/min to obtain peak load (P) and deformation (y) for $S_D$ calculation. For the same materials, APA test was performed. Relation of the $S_D$ with APA rut depth was evaluated using regression analysis. The $R^2$ value was 0.76, indicating this simple test procedure being a possible method for predicting deformation resistance of asphalt concretes at high temperature. It was also shown that, using the regression model, minimum value(s) of $S_D$ of surface course asphalt mixture or binder course for a particular road level can be determined. The limit values may be possible to use as cut-off value(s) of asphalt mixtures for the layer after further elaborated studies.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.4
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• pp.527-533
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• 2011

Decomposition of compost applied to soils is affected basically by its biological stability; but, many other chemical properties of the compost may also influence compost organic-C mineralization. This study was conducted to investigate the principal substrate quality factors of composts that determine C mineralization of compost with similar stability degree (SD). Three composts samples with similar SD but different chemical properties such as pH, C/N, $K_2SO_4$-extractable C, and molar ratio of $NH_4^+$ to $NO_3^-$ were mixed with an acid loamy soil and $CO_2$ emission was monitored during the laboratory incubation for 100 days. Temporal pattern of cumulative compost organic-C mineralization expressed as % of total organic C ($C_{%\;TOC}$) followed double exponential first order kinetics model and the $C_{%\;TOC}$ ranged from 4.8 to 11.8% at the end of incubation. The pattern of C%TOC among the composts was not coincident with the SD pattern (40.1 to 58.6%) of the composts; e.g. compost with the lowest SD resulted in the least $C_{%\;TOC}$ and vice versa. This result indicates that SD of compost can not serve as a concrete predictor of compost mineralization as SD is subject not only to maturity of compost but also to characteristics of co-composting materials such as rice hull (low SD) and sawdust (high SD). Meanwhile, such pattern of $C_{%\;TOC}$ collaborated with pH, C/N, $K_2SO_4$-extractable C, and molar ratio of $NH_4^+$ to $NO_3^-$ of the composts that are regarded as chemical indices of the progress of composting. Therefore, for better prediction of compost mineralization in soils, it is necessary to consider both SD and other chemical indices (pH, C/N, and molar ratio of $NH_4^+$ to $NO_3^-$).

• Journal of Korea Water Resources Association
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• v.40 no.6 s.179
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• pp.485-494
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• 2007

This study was performed to evaluate the environmental qualities of the revetment construction methods and the river-facility materials using Life-Cycle-Assessment(LCA) for the nature-friendly design of close-to-nature river, The investigation results on the environmental qualities of energy and materials used to the close-to-nature river plan showed that the environmental impacts per unit weight increased in the order of gasoline > diesel > cement > wood. The environmental impacts per unit area of revetment construction method exhibited that the environmental loadings increased in the order of gabion > revetment > cribwork. In addition, it was observed that the environmental impact was reduced by improving the materials of zinc-galvanized wire. The model basin investigated in this study was the $0.3km^2$ area of river improvement works in Kyung stream, which is a tributary to the Seomjin river and the second regional stream. The research was conducted based on the 30years by life expectancy of artificial facilities. For the comparisons of revetment techniques with respect to the environmental qualities, the method resulted in the highest environmental loadings. The method using ready-mixed concrete ranked second in the environmental loadings of revetment techniques. The present results of this study are expected to play a beneficial role in the nature-friendly design of close-to-nature river by quantitatively identifying the environmental quality of total procedures (i.e., combination of techniques, selection of river-facility materials, maintenance of river-facility) applied to close-to-nature river plan.

• Communications of Mathematical Education
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• v.20 no.1 s.25
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• pp.117-145
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• 2006

Mathematically gifted children have creative curiosity about novel tasks deriving from their natural mathematical talents, aptitudes, intellectual abilities and creativities. More effect in nurturing the creative thinking found in brilliant children, letting them approach problem solving in various ways and make strategic attempts is needed. Given this perspective, it is desirable to select open-ended and atypical problems as a task for educational program for gifted children. In this paper, various types of open-ended problems were framed and based on these, teaming activities were adapted into gifted children's class. Then in the problem solving process, the characteristic of bright children's mathematical thinking ability and examples of problem solving strategies were analyzed so that suggestions about classes for bright children utilizing open-ended tasks at elementary schools could be achieved. For this, an open-ended task made of 24 inquiries was structured, the teaching procedure was made of three steps properly transforming Renzulli's Enrichment Triad Model, and 24 periods of classes were progressed according to the teaching plan. One period of class for each subcategories of mathematical thinking ability; ability of intuitional insight, systematizing information, space formation/visualization, mathematical abstraction, mathematical reasoning, and reflective thinking were chosen and analyzed regarding teaching, teaming process and products. Problem solving examples that could be anticipated through teaching and teaming process and products analysis, and creative problem solving examples were suggested, and suggestions about teaching bright children using open-ended tasks were deduced based on the analysis of the characteristic of tasks, role of the teacher, impartiality and probability of approaching through reflecting the classes. Through the case study of a mathematics class for bright children making use of open-ended tasks proved to satisfy the curiosity of the students, and was proved to be effective for providing and forming a habit of various mathematical thinking experiences by establishing atypical mathematical problem solving strategies. This study is meaningful in that it provided mathematically gifted children's problem solving procedures about open-ended problems and it made an attempt at concrete and practical case study about classes fur gifted children while most of studies on education for gifted children in this country focus on the studies on basic theories or quantitative studies.