• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.261-266
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• 1998

The purpose of this study is to present the reference data on the development of undispersed underwater mortar for augered pile under various replacement ratio of fly-ash. According to the experimental results, when 10% of fly-ash is mixed under mix proportion of 1:1.5(c:s), as strength and shrinkage decrease slightly, whereas fluidity increase, high quality mortar for augered pile can be achieve in case above condition is applied.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 공동학술발표회
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• pp.252-252
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• 2017

• 한국건축시공학회지
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• 제5권1호
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• pp.63-68
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• 2005

Generally, aggregate may limit the workability, strength and durability of concrete, and good concrete cannot be made with aggregate of bad property including low strength, bad shape and grading. But recently, it has been insufficient in quantity to collect good natural aggregate because of exhaustion of aggregate resources. In case of Korea, the using ratio of crushed stone occupies about 97 percent of total coarse aggregate, and ratio of crushed sand occupies about 18.3 percent of total fine aggregate. This is an experimental study to compare and analyze the properties of crushed sand for concrete in capital region and concrete according to the replacement ratio of crushed sand to improve quality and mix design of concrete using crushed sand. According to test results, it was found that nearly all the properties of crushed sand satisfied with the value recommended by KS. And it is recommended that FM of crushed sand should be lowered by improvement of manufacture system or grading adjustment should be used because FM of crushed sand was a bit higher.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2004년도 학술.기술논문발표회
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• pp.51-55
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• 2004

Generally, aggregate may limit the strength of concrete, and aggregate with undesirable properties including strength, shape and grading etc. cannot produce good concrete. Also, the properties of aggregate greatly affect the durability and structural performance of concrete. Recently, it has increased the using of crushed aggregate for concrete due to the exhaustion of good natural aggregate. In case of Korea, the using ratio of crushed stone occupies about 97％ of whole coarse aggregate, and ratio of crushed sand occupies about 18.3％ of whole fine aggregate. This is an experimental study to compare and analyze the properties of crushed sand for concrete in capital region and concrete according to the replacement ratio of crushed sand to do suitable mix design and improve the concrete quality. According to results, it was found that nearly all the properties of crushed sand satisfied with the value recommended by KS.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.262-268
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• 1998

This research is to examine the selected method of optimal mixing proportion and cost analysis in the super flowing concrete. As confined water $ratio($\beta_p$)$ and K is introduced, itis to establish optimal mixing design of super flowing concrete according to the steps of paste, mortar and concrete. From paste and mortar test, it was led to $$\beta_p$$ and $K_p$satisfying the optimum condions depending on the kinds of binders. Then $$\beta_p$$ and $K_p$ is reflected to the mix condition of super flowing concrete. The result of test, the mix condition of super flowing concrete satisfied the quality performance of concrete with adjustment of additional rate of the superplasticizer. Besides, in case of design strength $350kg/\textrm{cm}^2$ of concrete, material cost in super flowing concrete is able to be reduced 5~16% in replacement of fly ash 30% in ordinary portland cement and slag cement.

• Tuberculosis and Respiratory Diseases
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• 제70권2호
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• pp.143-149
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• 2011

Background: Stopping medical treatment by tuberculosis (TB) patients prior to completing treatment period is a major concern in private hospitals. We evaluated the impact of public-private mix (PPM) project on increasing treatment success rate of TB in a private tertiary hospital in Korea. Methods: Starting in February 2009, TB patients treated at Dankook University Hospital received health education and case monitoring activities by specially trained public health nurses (PPM project). On a retrospective basis, we reviewed medical records and compared the treatment outcome of TB patients treated under the PPM project (PPM group) to patients treated without the PPM project (control group) between January 2008 and June 2010. In addition, we also evaluated the risk factors treatment non-completion. Results: The number of patients in the PPM group and control group were 123 (85 pulmonary TB and 38 extrapulmonary TB) and 146 (101 pulmonary TB and 45 extra-pulmonary TB), respectively. The PPM group had demographic and clinical findings comparable to those of control group. The PPM group showed a significantly higher treatment success rate (93.5%) compared to the control group (77.9%). However, development of complications, proximity to the hospital, and presence of co-morbid disease did not influence the treatment success rate. Conclusion: The PPM project was effective at increasing the TB treatment success rate. An effort to improve and to expand the PPM project is needed in private Korean hospitals.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.85-88
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• 2006

This study describes the optimum mix proportion of the high strength and self-compacting concrete placed in main structures of LNG above tank. This concrete requires high strength level about $60{\sim}80MPa$, low hydration heat, balance between workability and consistency without vibrating in the actual work. For this purpose, low heat portland cement and fly ash are selected and design factors including water-binder ratio, replacement ratio of fly ash are tested. As experimental results, low heat portland cement shows lower the confined water ratio than another cement type and the optimum replacement ratio of fly ash in order to improve properties of the binder-paste shows 10% by cement weight considering test results of the confined water ratio$({\beta}p)$. Also, flowability of the high strength and self-compacting concrete by using fly ash about $10{\sim}20%$ is improved. The replacement ratio of fly ash 10% and water-binder ratio $25{\sim}27%$ are suitable to the design strength 80MPa and cost, In case of the design strength 60MPa, the replacement ratio of fly ash and water-binder ratio show 20% and $25{\sim}30%$ separately. Based on the results of this study, the optimum mix proportions of the high strength and self-compacting concrete will be applied to the construction of LNG above tank as a new type.

• Advances in concrete construction
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• 제1권4호
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• pp.341-358
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• 2013

Due to fast growth in urbanisation, a highly developed infrastructure is essential for economic growth and prosperity. One of the major problems is to preserve, maintain, and retrofit these structures. To meet the requirements of construction industry, the basic information on all the mechanical properties of various concretes is essential. This paper presents the details of development of various concretes, namely, normal strength concrete (around 50 MPa), high strength concrete (around 85 MPa) and ultra high strength concrete (UHSC) (around 120 MPa) including their mechanical properties. The various mechanical properties such as compressive strength, split tensile strength, modulus of elasticity, fracture energy and tensile stress vs crack width have been obtained from the respective test results. It is observed from the studies that a higher value of compressive strength, split tensile strength and fracture energy is achieved in the case of UHSC, which can be attributed to the contribution at different scales viz., at the meso scale due to the fibers and at the micro scale due to the close packing of grains which is on account of good grading of the particles. Micro structure of UHSC mix has been examined for various magnifications to identify the pores if any present in the mix. Brief note on characteristic length and brittleness number has been given.

• 한국경영과학회지
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• 제27권1호
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• pp.95-106
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• 2002

The tilde use of Information Technology (IT), especially the rapid diffusion of the internet, brings us a new paradigm, called "Electronic Commerce," or "Digital Economy." The paradigm is regarded as a business strategy essential to organizations′competitive advantages. Because few studies have been shown in the area of e-strategies, especially in the combined strategies of clicks and mortars, a study of this area is required. The main questions of this study are empirically to validate the usefulness and applicability of a decision roadmap and to analyze the situation of Korean firms in the view of the decision roadmap. Major results of this study are as follows : First, there is an evidence that the roadmap can be applied to Korean firms regardless of their industry and size. Second, the usefulness of the roadmap is proved because companies following the directions of the roadmap show high degree of satisfaction with online sales. Third, Korean companies in general do not achieve an Ideal Integration (or separation), especially In terms of management and operation. In conclusion, this study provides an e-business strategy Planner some guidelines about how to achieve right mix of on-line and off-line business.

• The Journal of Asian Finance, Economics and Business
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• 제8권7호
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• pp.151-160
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• 2021

The purposes of this research were: 1) to analyze the confirmatory factors with the business operational model of entrepreneurs of small and medium enterprises (SMEs) in the textile and clothing industry, and 2) to verify the congruence of the model with the operational ways of the entrepreneurs of SMEs in the textile and clothing industry. The sample consisted of 500 small and medium enterprise entrepreneurs in the textile and clothing industry. This study was quantitative research and the instrument used to collect the data was a questionnaire. The data was analyzed using 1^st order and 2^nd order of confirmatory analysis (CFA). The findings of this research revealed that the model of SMEs in the textile and clothing industry was overall at a high level. Four main factors were used for the model of SMEs in the textile and clothing industry by their importance in descending order as follows: marketing mix (MM), collaboration network (CN), production inventory management (PIM), and creativity (CT). The results of verification of model congruence revealed the model of SMEs in the textile and clothing industry was fit and in accordance with the empirical data.