• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.53-64
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• 2017

Ultra-high performance fiber-reinforced concrete (UHPFRC) is characterized by a post-cracking residual tensile strength with a large tensile strain as well as a high compressive strength. To determine a material tensile strength of UHPFRC, three-point loading test on notched prism and direct tensile test on doubly notched plate were compared and then the design tensile strength is decided. Shear tests on nine I-shaped beams with varied types of fiber volume ratio, shear span ratio and size effect were conducted to investigate shear behavior in web. From the test results, the stress redistribution ability represented as diagonal cracked zone was quantified by inclination of principal stress in web. The test results shows that the specimens were capable of resistance to shear loading without stirrup in a range of large deformation and the strength increase with post-cracking behavior is stable. However at the ultimate state all test specimens failed as a crack localization in the damaged zone and the shear strength of specimens is affected by shear span ratio and effective depth. Strength predictions show that the existing recommendations should be modified considering shear span ratio and effective depth as design parameters.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.517-524
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• 2014

The ultimate goal of seismic design is to reduce the probable losses or damages occurred during an expected earthquake event. To achieve this goal, this study represents a procedure that can estimate annual loss probability of a structure damaged by strong ground motion. First of all, probabilistic seismic performance assessment should be performed using seismic fragility analyses that are presented by a cumulative distribution function of the probability in each exceedance structural damage state. A seismic hazard curve is then derived from an annual frequency of exccedance per each ground motion intensity. An annual loss probability function is combined with seismic fragility analysis results and seismic hazard curves. In this paper, annual loss probabilities are estimated by the structural fragility curve of steel moment-resisting frames(SMRFs) in San Francisco Bay, USA, and are compared with loss estimation results obtained from the HAZUS methodology. It is investigated from the comparison that seismic losses of the SMRFs calculated from the HAZUS method are conservatively estimated. The procedure presented in this study could be effectively used for future studies related with structural seismic performance assessment and annual loss probability estimation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.483-493
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• 2013

The high strength materials have been more widely used in a large reinforced concrete structures. It is known that the use of high strength material in RC structures give the benefits of the mechanical and durable properties, but the ductility decreases with an increase in the strength of the materials. In the design of a reinforced concrete beam, both the flexural strength and ductility need to be considered. So, it is necessary to assess accurately the ductility of the beam with high strength materials in order to ensure the ductility requirement in design. In this study, the effects of the material strength on the flexural behavior and curvature ductility factor of reinforcement concrete beam sections with various reinforcement conditions have been evaluated and a newly prediction formula for curvature ductility factor of RC beam has been developed considering the stress of compression reinforcement at ultimate state. The proposed predictions for the curvature ductility factor which is applicable to both singly and doubly reinforced concrete beam are verified by comparisons with other prediction formulas and the proposed formula offers fairly accurate within 9% error and consistent predictions for curvature ductility factor of reinforced concrete beam.

• Management & Information Systems Review
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• v.31 no.4
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• pp.363-376
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• 2012

In Korea, religious bodies are being given tax benefits like tax exemption and reduction in accordance with the Local Tax Law. By the way, there's no difference between tax benefits given to religious bodies and other kinds of non-profit corporations. In other words, tax exemption and reduction for religious bodies are being made without considering the very nature of the bodies. This is causing lots of problems. Currently, tax supports to religious bodies are mostly focusing on tax items related to their property, considerably diverting from the ultimate purpose and objectives of tax exemption and reduction for religious organizations. This is not also weakening local finance, but also diverting from the basic intent of so-called the induction system that if necessary, tax supports are given, but they have to be minimized. To solve these problems, comprehensive actions need to be taken, for example, reducing tax benefits given to religious bodies' property and motivating the bodies to make a variety of donations like in developed countries. Now, religious bodies should change their consciousness of tax liability that is imposed by the Local Tax Law. And the government should be more systematic in the collection and management of data that are necessary to levy taxes on religious bodies. If required, the government show the data to religious bodies, convincing them to positively fulfil their tax liability without complaint. This study discusses the current state and problems of existing local tax systems in relation to religious bodies and then propose how to improve the systems. If the systems of tax exemption and reduction for religious bodies under the Local Tax Law can be improved, it would contribute to improve the finance of local autonomous bodies.

• Journal of Korea Water Resources Association
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• v.39 no.12 s.173
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• pp.1043-1056
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• 2006

Our ultimate purpose is to investigate the potential change in regional surface climate due to the global warming and to produce higher quality regional surface climate information over the Korean peninsula for comprehensive impact assessment. Toward this purpose, we carried out two 30-year long experiments, one for present day conditions (covering the period 1971-2000) and one for near future climate conditions (covering the period 2021-2050) with a regional climate model (RegCM3) using a one-way double-nested system. In order to obtain the confidence in a future climate projection, we first verify the model basic performance of how the reference simulation is realistic in comparison with a fairly dense observation network. We then examine the possible future changes in mean climate state as well as in the frequency and intensity of extreme climate events to be derived by difference between climate condition as a baseline and future simulated climate states with increased greenhouse gas. Emphasis in this study is placed on the high-resolution spatial/temporal aspects of the climate change scenarios under different climate settings over Korea generated by complex topography and coastlines that are relevant on a regional scale.

• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.687-694
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• 2014

This study established a displacement ductility ratio model for ductile design for the boundary element of shear walls. To determine the curvature distribution along the member length and displacement at the free end of the member, the distributions of strains and internal forces along the shear wall section depth were idealized based on the Bernoulli's principle, strain compatibility condition, and equilibrium condition of forces. The confinement effect at the boundary element, provided by transverse reinforcement, was calculated using the stress-strain relationship of confined concrete proposed by Razvi and Saatcioglu. The curvatures corresponding to the initial yielding moment and 80% of the ultimate state after the peak strength were then conversed into displacement values based on the concept of equivalent hinge length. The derived displacement ductility ratio model was simplified by the regression approach using the comprehensive analytical data obtained from the parametric study. The proposed model is in good agreement with test results, indicating that the mean and standard deviation of the ratios between predictions and experiments are 1.05 and 0.19, respectively. Overall, the proposed model is expected to be available for determining the transverse reinforcement ratio at the boundary element for a targeted displacement ductility ratio.

• Journal of the Economic Geographical Society of Korea
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• v.10 no.2
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• pp.197-210
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• 2007

This study focuses on the actual condition and level of residents' participation in the case of Jinmok village, located in Jeonnam province Jangheung-gun Hwejin-myeon, and presents suggestions to inspire residents' awareness and enhance participation. This village has been developing a Green Rural Tourism Village Building Project under management of the Ministry of Agriculture and Forestry. Consequently, the importance of residents recognizing they are a "community" has been emphasized as well as promoting the residents cooperation as a community. In addition, it was necessary to research ways to inspire the village to realize the ultimate goal of building rural tourism village. For this, in the beginning of the project, profitable work needed to be provided for the residents to participate in. Constructive participation by all residents is essential in each stage of the project s development. Operating a farm stay or running lodging facilities are options that could be considered. Moreover, it is imperative to immediately establish a awareness about the importance of participation in those who might have a negative or impartial opinion about the project, by providing education. The most efficient way to encourage residents' participation is to support various opportunities for education and field trips. Through these efforts, the residents are able to raise their level of education and develop their man-power as well. Once more, providing an incentive for residents' reliance is the kernel of the project. Considering the state of Korean rural areas, which are rapidly aging and becoming depopulated, green tourism can be a practical alternative for continuing rural development.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.4
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• pp.49-63
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• 2010

This study focused on the method of separation - space organization- as one of the architectural methods that is considered by the view point of its location and arrangement of 'Byoul-seo' private garden pavilion in Honam province. As a result, the followings are conclusions; By this study, they can be found in the concept of '居敬窮理', '格物致知'. It is presumed that nature union is archived through the 'yan-sang(玩賞)' which is ultimate state of knowledge that is based on the premises of opened significance in emancipation from narrow view point in the past and cognition of value. Therefore, it is needed to know the unworldly point of space perception about the pavilion territory, furthermore to have conceptual method to distinct pavilion from the world. there are two methods in the distinct concept in this pavilion research: unworldly separation and meditative separation. It is concluded that the specific consideration of the method of separation that is applied in the Byoul-seo pavilion. And it is accomplished by the contemplation of separation method in approach and entrance of direct influence area. they could be 1) cross the hill, 2) cross over a brook, 3) lifted up in the mount, 4) penetrate the forest, and 5) narrow entrance, which could be part of location.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.359-368
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• 2011

Purpose: Aquacel Ag$^{(R)}$ is a hydrofiber wound dressing integrated with ionic silver. Sorbact$^{(R)}$ is a hydrophobiccoated dressing that uses the hydrophobic interaction with microbes. In this study, we compared the wound healing effects and the antibacterial effects of Medifoam$^{(R)}$, Betadine soaked, Aquacel Ag$^{(R)}$ and Sorbact$^{(R)}$ dressings against MRSA-infected wounds. Methods: Eighty rats were divided into four groups: Medifoam$^{(R)}$; Betadine soaked; Aquacel Ag$^{(R)}$; and Sorbact$^{(R)}$. A $1.5{\times}1.5cm$ square full-thickness wound was made on the dorsum of each rat and infected with MRSA. Twenty-four hours thereafter, each dressing was applied to the wound and changed every other day. One, 3, 7, 11 and 15 days after the wound infection, swab culture grade, wound bed appearance score, and wound defect size change were evaluated, and 7 and 15 days after, histologic evaluation was compared between the groups. Results: The bacteria load of wounds in the Sorbact$^{(R)}$ group decreased earlier than in the other groups. The wound bed appearance score of the Sorbact$^{(R)}$ group also increased quicker, compared with the other groups. However, the size of wounds of the Aquacel Ag$^{(R)}$ group decreased more rapidly, compared with other groups. From the histologic point of view, there was no significant difference between Betadine soaked, Aquacel Ag$^{(R)}$ and Sorbact groups. Conclusion: The hydrophobic dressing using Sorbact$^{(R)}$ showed a more rapid reduction in the MRSA load and an elevation in the wound bed appearance score, but a slower decrease in wound size change due to detachment of wound bed tissue when the dressing was eliminated in the low exudate wound. The silver-containing hydrofiber dressing using Aquacel Ag$^{(R)}$ was more effective in ultimate wound size reduction, but some debris was trapped in the wound tissue and induced foreign body reaction in the high exudate wound. Thus, ongoing selection process of treatment based on the evaluation of the infectious wound state will be very important.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.209-217
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• 2021

This paper investigates the effect of high strength hooked-end steel fiber content and aspect ratio on the compressive and flexural performance of concrete. A total of ten mixtures were prepared and tested. Concretes with specific compressive strength of 30 MPa were reinforced with three different aspect ratios (l/d) of steel fibers 64, 67, and 80 and three different percentages of steel fibers 0.25, 0.50, and 0.75% by volume of concrete. Tensile strengths of steel fibers with l/d of 64, 67, and 80 are 2,000, 2,400, and 2,100 MPa, respectively. The compressive and flexural properties of plain and steel fiber-reinforced concrete (SFRC) mixtures were evaluated and compared. The experimental results indicated that the incorporation of high-strength hooked-end steel fibers had significant effects on the compressive and flexural performance of concrete. With the increase of steel fiber content, compressive performances, such as Poisson's ratio and toughness, of concrete were improved. The steel fibers with the least l/d of 67 resulted in a larger enhancement of compressive performances. The residual flexural strength, that is, post-cracking flexural resistance and toughness, of concrete is mainly depended on the dosage and aspect ratio of steel fibers. The residual flexural strength at serviceability (SLS) and ultimate limit state (ULS) defined in fib Model Code 2010 (MC2010) is increased as the fiber content and aspect ratio increase.