• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1105-1108
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• 2008

This paper investigated measures of spalling prevention and mechanism to secure stability of subjected to a fire circumstance. The results were summarized as following. 1) There were 4 kinds of methods for spalling prevention, such as declining percentage of water content and cement water ratio, isolating from high temperature with fire proof covering, giving lateral resistance stress, and discharging vapor pressure using fibers. 2) It was confirmed that methods using fibers to a new construction and fire proof covering to a existing construction on the basis of investigation for the spalling mechanism through the existing theory of spalling and a new theory of WPB.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.137-138
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• 2019

To overcome the limitation in relation to thermal insulator's selection and installation method that is suitable for exterior insulation and waterproof construction methods, a production basis of thermal insulators of which manufacturing knowhow is held by companies was ensured and future-oriented construction methods to adopt new materials were applied. Performance verification was conducted through performance and mock-up tests of thermal transmittance on the cross sections where the flexible insulators were applied based on the improved prototype and performance data were obtained. To overcome the biggest drawbacks (walking feeling and damage etc.) in the exterior insulation and waterproof construction method, inserting a protective layer between thermal insulator and water-proof layer was proposed, and polypropylene corrugated cardboards.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.769-776
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• 2007

The comprehensive Topic of Total Quality Management (TQM) has been put forward since the 6^th decade in industrial countries. The serious attention to it in developing countries goes back to recent years. Unfortunately serious attention is not paid to quality issues in building industry. Therefore, the construction of buildings is highly vulnerable against natural events while having low effective lifetime. Wide-range destruction of the residential buildings in the earthquake of Bam ( in IRAN ) is a clear proof for this claim. In this paper we tried to present the corresponding effects between quality issues and other aspects of a building project (such as costs) and proposed general solutions to improve quality indices in construction industry.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.303-306
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• 1999

For the purpose of Military means, explosion proof concrete, which protect the structures from the damage due to the explosion of bomb and maintain its shape, is required to develop. Therefore, in this paper, mechanical and explosionproof properties of concrete are tested under various steel fiber contents and member size. According to the experimental results, compressive, tensile and flexural strength go up with the increase of fiber contents. Energy bearing capacities is higher with the increase of fiber contents. Especially, it is confirmed that slurry infiltrated fiber concrete (SIFCON) gains in high strength and has high energy bearing capacities. SIFCON is expected to apply in the construction of explosion proof structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.652-655
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• 2004

In these days, repair materials for leakage cannot help but being taken in temporary way without any noticeable countermeasure. This kind of repair is socially criticized many times that is defective construction even if tills costs a lot. It was not arrange the standard for performance evaluation test method and quality maintenance for materials, even it has been used various injection repairing agent. In conclusion, We suggest that the test method for repair materials for leakage to establish the leakage repairing technology as increase of structure demand, so that the necessity of the establishment of the quality control standard and the performance testing way on the relevant water-proof seal is increasing a lot to regulate the water-proof technology and the leakage repair technology.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.292-298
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• 2005

Tunnel in subway should be designed as a water-proof type tunnel as much as possible but it is difficult to make it come true due to several facts, such as construction technique and cost. A drainage type tunnel as a substitute of a water-proof tunnel lead to the increase of water pressure on the concrete lining that make bad effect to tunnel structure when it has some problem to operate the drainage system. Throughout studying about cases on defects of tunnel drainage in subway We hope it contributes to tunnel maintenance.

• Journal of ILASS-Korea
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• v.21 no.3
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• pp.162-169
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• 2016

When we construct a road near an apartment complex, we consider a soundproof wall. To make residential places quieter, we may consider a soundproof road tunnel. Such a tunnel, however, would become highly concentrated with soot from vehicles whenever a traffic jam might occur. To create an optimum design, this study utilizes the PHOENICS-VR software. The work considers three cases: (1) no openings (2) openings at 30m intervals, and (3) openings at 60m intervals on the upper side of the tunnel. The study finds that in the second case shows CO concentration distributions were 15% less than those without openings. And the CO concentration distributions of the second and third cases are almost the same. The findings suggest that we should make the soundproof tunnel to reduce construction fees.

• Journal of the Korean Mathematical Society
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• v.58 no.5
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• pp.1227-1237
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• 2021

This paper is concerned with a reaction-diffusion logistic model. In [17], Lou observed that a heterogeneous environment with diffusion makes the total biomass greater than the total carrying capacity. Regarding the ratio of biomass to carrying capacity, Ni [10] raised a conjecture that the ratio has a upper bound depending only on the spatial dimension. For the one-dimensional case, Bai, He, and Li [1] proved that the optimal upper bound is 3. Recently, Inoue and Kuto [13] showed that the supremum of the ratio is infinity when the domain is a multi-dimensional ball. In this paper, we generalized the result of [13] to an arbitrary smooth bounded domain in ℝⁿ, n ≥ 2. We use the sub-solution and super-solution method. The idea of the proof is essentially the same as the proof of [13] but we have improved the construction of sub-solutions. This is the complete answer to the conjecture of Ni.

• East Asian mathematical journal
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• v.36 no.4
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• pp.493-513
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• 2020

The reason for this study is that the learning content of geometric construction in school mathematics is very insufficient. Geometric construction not only enables in-depth understanding of shapes, but also improves deductive proof skills. In school mathematics education, geometric construction is a very important learning factor, and educational significance is very high in that it can develop reasoning skills essential to the future society. Nevertheless, the reduction of geometric construction learning content in Korean curriculum and mathematics textbooks is against the times. Therefore, the purpose of this study is to analyze the transition of geometric construction learning contents in middle school mathematics curriculum and mathematics textbooks. In order to achieve the purpose of this study, the following studies were conducted. First, we analyze the characteristics of geometric construction according to changes in curriculum and textbooks. Second, we develop a framework for analyzing geometric construction tasks. Third, we explore geometric construction tasks according to the developed framework. Through this, it is expected to provide significant implications for the geometric areas of the new middle school curriculum that will be developed in the future.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1474-1478
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• 2009

The cooperation and trust among the project participants play a critical role in the success or failure of any delivery system in construction industry. But it is very difficult to establish trust between an owner and a contractor when rational people only pursue only their own material self-interest. Based on the principal-agent theory, this paper will introduce the altruistic behavior into the traditional principal-agent model, and model the reciprocal behavior between the owner and contractor. We will show that both the owner and the contractor benefit from their reciprocal behavior, and hence trust establishing between them is possible. More importantly, we will proof that the higher the project uncertainty is, the more important trust establishing is.