• Journal of the Korea Institute of Building Construction
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• v.6 no.3 s.21
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• pp.123-129
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• 2006

In these days, as building structures are getting taller, larger, and more diversified, structural systems with more economy and more efficiency are being required and so are more efficient building materials, this study conducted a basic experiment to conclude an adequate selection of materials and to calculate an optimal mixing proportion of those materials to produce High-strength concrete in a 100MPa of specified concrete strength. And also we conducted an experiment to find out basic properties of this concrete such as slump-flow, strength.

• Environmental Analysis Health and Toxicology
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• v.6 no.1_2
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• pp.83-93
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• 1991

The specified industrial wastes increased 26% annually during the last 5 years from 1984 to 1988 in Korea, and the special treatment and proper management are required. The effective methods are studied on the process of generation, keeping, transportation, and treatment/disposal for specified industrial wastes and materials. Also, in this paper, the author describes the plans to develop the public disposal facilities and manage specific industrial waste properly in Korea.

• English Language & Literature Teaching
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• v.11 no.3
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• pp.139-164
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• 2005

The purpose of this study is to analyze the writing activity materials presented in the thirteen middle school textbooks and determine if the writing activity materials are appropriate for the goals and contents of the 7th national curriculum. The writing activity materials are analyzed based on three criteria. First, the writing activity materials are analyzed based on Rivers'(1981) five writing guidances, which are specified with detailed writing activity materials. The first criterion was suggested by Young-Ran Lee(2004). Second, the writing activity materials in the textbooks are analyzed according to the criterion prescribed by the 7th national curriculum, which are specified with writing activities presented by Rivers(1981), Raimes(1983), Hedge(1988), and Beverly and Carol(1988). Third, the writing activity materials related to other skills, such as listening, speaking, and reading, in the textbooks are selected and analyzed according to the proportion of the integration of skills. The results are as follows: First, writing activity materials in the textbooks belong to the type of 'reproduction', ie. the second stage of Rivers' writing guidance, 'recombination, which is the third stage of Rivers' writing guidance, and the type of 'guided writing', noted on the fourth stage of the guidance. Second, the writing activity materials satisfy the criterion in the 7th national curriculum, as for the proportions, but they are not balanced. Third, most of the writing activity materials contain writing activities that involve non-writing skills such as listening, speaking and reading, but they are not balanced. Particularly, writing activity materials related to reading activities are common.

• Current Optics and Photonics
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• v.7 no.3
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• pp.273-282
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• 2023

This paper presents a new method for redistributing effectively the first orders of each lens element to achromatize and athermalize an optical system, by introducing a novel method for adjusting the slope of an achromatic and athermal line. This line is specified by connecting the housing, equivalent single lens, and aberration-corrected point on a glass map composed of available plastic and glass materials for molding. Thus, if a specific lens is replaced with the material characterized by the chromatic and thermal powers of an aberration-corrected point, we obtain an achromatic and athermal system. First, we identify two materials that yield the minimum and maximum slopes of the line from a housing coordinate, which specifies the slope range of the line spanning the available materials on a glass map. Next, redistributing the optical first orders (optical powers and paraxial ray heights) of lens elements by moving the achromatic and athermal line into the available slope range of materials yields a good achromatic and athermal design. Applying this concept to design a mobile-phone camera lens, we efficiently obtain an achromatic and athermal system with cost-effective material selection, over the specified temperature and waveband ranges.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.92-93
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• 2018

This study analyzed the physical properties of insulation materials upon completion of building completion years and found the suitability of the current energy performance analysis methodology to apply the insulation specified in the design drawings to the same thermal conductivity values as the new materials.

• Journal of Applied Reliability
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• v.6 no.4
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• pp.275-284
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• 2006

A test method for assessing service life of building materials and components based on performance degradation data is developed. The performance of a building material degrades as time goes by and the failure of the material is often defined as the point at which the performance of the material reaches a pre-specified degraded level. A performance-based test method is developed and a numerical example is provided to illustrate the use of the developed test method.

• Journal of Korean Home Economics Education Association
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• v.12 no.3
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• pp.145-156
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• 2000

This study was intended to develop an efficient web-based instruction materials in clothing unit. The clothing unit was chosen because this unit was supposed to be appropriate to analyze and utilize web. By using languages of html asp, the study developed web materials to use this unit and constructed this unit into web site. Finally the study tried to examined educational effect by performing the constructed web site and representing some ways which can be applied in the classroom. The result of this study can be summed up as follows: $\circled1$The web materials were developed with steps of planning longrightarrowdesigninglongrightarrowdevelopmentlongrightarrowevaluation. In each step detailed activities, content analysis examples of developed materials, which presents the concrete procedures and directions were specified. $\circled2$The web materials were developed to be able to change an add up the materials in the web site. $\circled3$The web materials were developed by teaching-leaning model and the lesson plan, and then they are applied. $\circled4$Instruction materials were developed according to the lesson plan and in concrete ways.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.85-93
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• 2017

This paper presents mechanical properties and carbonation behavior of the recycled aggregate concretes(RAC) in which natural aggregate was replaced by recycled coarse aggregate and fine aggregate by specified concrete strength levels(21, 35, 50MPa). A total of 18 RAC were produced and classified into six series, each of which included three mixes designed with three specified concrete strength levels of 21MPa, 35MPa and 50MPa and three recycled aggregate replacement ratios of 0, 50 and 100%. Physical and mechanical properties of RAC were tested for slump test, compressive strength, and carbonation depth. The test results indicated that the slump of RAC could be improved or same by recycled coarse aggregate replacement ratios, when compared with natural aggregate. But slump of RAC was decreased as the recycled fine aggregate replacement ratios increase. Also, the test results showed that the compressive strength was decreased as the recycled aggregate replacement ratios increased and it had a conspicuous tendency to decrease when the content of the recycled aggregate exceeded 50%. Furthermore, the result indicated that the measured carbonation depth increases by 40% with the increase of the recycled aggregate replacement. In the case of the concrete having low level compressive strength, the increase of carbonation depth tends to be higher when using the RCA. However, the trend of carbonation resistivity in high level compressive strength concrete is similar to that obtained in natural aggregate concrete. Therefore, an advance on the admixture application and mix ratio control are required to improve the carbonation resistivity when using the recycled aggregate in large scale.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.6
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• pp.505-513
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• 2005

We measured the time-dependent concentration of VOCs emitted from Ondol floor, furniture, and the wall made of various building materials. After obtaining results from the previous measurement, we developed the estimation equations of the concentration decay, and obtained the estimated graphs for the concentration decay under different air change rates and loading factor conditions by using the estimated equations. We conducted our tests by applying our measurements to real residences for 110 days in the case of furniture and for 40 days in the case of the floor. We also conducted experiments in the cases of various wall materials for 7 days which totaled 10 times. We used the GC/FID for experiments for real residences accord-ing to the specified procedures of the NIOSH 1501, and carried out experiments for wall materials according to the specified procedures of the ASTM 5116-97. When conducting experiments for wall materials, we set the temperature and relative humidity at $23^{\circ}C$ and $50\%$, respectively. We also set the air change rate and loading factor at 0.7/h and $1.617 m^2/m^3$, respectively. Our results showed that it is possible to predict proplrly the time-dependent concentration decay of VOCs by using logarithmic functions in both cases of experiments for real residences and for wall materials. Furthermore, we found that the concentration decay rate of VOCs increased rapidly as the air exchange rate increased while the concentration decay rate decreased as the loading factor increased.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.1
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• pp.23-27
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• 2016

This study investigates the effect of carbon fiber sheet (CFS) and carbon fiber strand sheet (CFSS) on the fatigue resistance and compressive strength of RC slabs. The results of a comparison of the number of equivalent cycles between the CFS- and CFSS-reinforced RC slab test specimens obtained from a fatigue test indicate that the CFSS-reinforced RC slab has 1.2~1.3 times greater effect of reinforcement than the CFS-reinforced RC slab. This study also indicates that the fatigue resistance of the CFS- and CFSS-reinforced RC slabs is ensured when the compressive strength of concrete is not lower than the specified design strength prescribed in the Specifications for Highway Bridges but is not ensured when the compressive strength of concrete is lower than the specified design strength, although the effect of reinforcement is secured.