• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.631-636
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• 2002

This study shows basic data for using as the structural lightweight aggregate. This will be the procedural method of recycling environmental close waste PET bottle lightweight aggregate(PBLA) that is rapidly increased the amount of production of waste PET bottle recently, the quality of developed PBLA and the fundamental properties by analyzing of mortar containing with PBLA. After experiment, the result shows the PBLA quality that have oven dry specific gravity of 1.39, unit volume weight of 844 kg/m$^3$ and absorption rate of 0% is satisfied with qualify regulation of lightweight aggregate. The flowability of mortar containing PBLA is increased maximum 16% with increasing mixing ratio of PBLA, however the compressive strength of mortar is decreased maximum 35% with increasing mixing ratio of PBLA.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.376-379
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• 2004

The objective of in this study makes investigation into the characteristics of concrete as to properties and blended ratio of crushed aggregates through experimental researches. In this study, river sand is blended with crushed sand as to investigate the quality change and characteristics of concrete with variation of blend ratio of crushed sand(50, 60, 70, 80, 90, $100\%$). Measured the air contents and slump to investigate properties of fresh concrete, and unit weight and compressive strength in age of 7, 28days to investigate properties of hardened concrete. The experimental results of crushed aggregates' qualities were all satisfied with Korea Standard's values.

• Korean Institute of Interior Design Journal
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• no.19
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• pp.105-113
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• 1999

This study investigates the prayer House facilities in Korean Churches and improves them to the positive way in order to revive the church itself. The prayer houses in Korea manages the various facilities and special programs. Theses facilities are used in christian seminars, educations, belief-training for the more non-christian's resort and training center when they could meet the god naturally. The purpose of this paper suggests the condition of the current prayer house facilities and the main organizers. this leads the fundamental data for the patterns of the unit facilities. Methods of study and range are 20 places among Seoul, Kyunggi - do area and analyse document survey, phone interview, drawing analysis, direct visit including the prayer house type, building area, site area, total floor area, location condition as searching items.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.2
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• pp.204-211
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• 1983

To investigate the effects of oscillatory feed cutting on the chip breaking and surface roughness and circularity, A prototype unit developed for the experiment is used. The results obtained are as follows. (1) It is obtained the region of chip breaking as Ftmin $f_{+min}$0.03mm ( = 0.3f). (2) The surface roughness becomes worse with increasing the value of A/f, but the type of variation with respect to n/N differs from the case of A/f>1, f<1. (3) The circularity of workpiece is increasing from the fundamental mode of n/N=i to the maximum value of n/N=i+0.5, and becomes worse with increasing the value of A/f. (4) From the viewpoint of above details and tool mechanics, the condition of A/f=1.0 and n/N=i.+-. .delta. (0.3<.delta.<0.4) is recommended.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.170-178
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• 2004

Continuously variable transmission (CVT) mechanisms considered here are input coupled types that combine the functions of a 2K-H II type differential gear and a V-belt type continuously variable unit (CVU). For the 8 different mechanisms, 4 of them are power-circulation modes while the other 4 are power-split modes, various performance analysis (speed ratios, power flows, divisions of power transmission in a differential gear and a CVU, and theoretical efficiencies) are performed to vary design parameters. Experimental studies are executed to validate fundamental relations (speed ratios, power flows, efficiencies, occurrence of geared neutral). Some useful characteristics associated with performance also are discussed in the mechanisms.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.3
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• pp.190-196
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• 2004

In this paper, we address a layout design problem, PTL[3], for determining an optimal 3-class-based dedicated linear storage layout in a class of unit load storage systems. Our objective is to minimize the expected single command travel time. We analyze PTL[3] to derive a fundamental property that an optimal solution to PTL[3] is one of the partitions based on the PAI(product activity index)-nonincreasing ordering. Using the property and partial enumeration, we construct an efficient exact algorithm with O $(n\;{\lceil}\;log\;n\;{\rceil}\;)$ for solving PTL[3].

• Bulletin of the Korean Mathematical Society
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• v.49 no.4
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• pp.767-774
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• 2012

For a positive square-free integer $d$, let $t_d$ and $u_d$ be positive integers such that ${\epsilon}_d=\frac{t_d+u_d{\sqrt{d}}}{\sigma}$ is the fundamental unit of the real quadratic field $\mathbb{Q}(\sqrt{d})$, where ${\sigma}=2$ if $d{\equiv}1$ (mod 4) and ${\sigma}=1$ otherwise For a given positive integer $l$ and a palindromic sequence of positive integers $a_1$, ${\ldots}$, $a_{l-1}$, we define the set $S(l;a_1,{\ldots},a_{l-1})$ := {$d{\in}\mathbb{Z}|d$ > 0, $\sqrt{d}=[a_0,\overline{a_1,{\ldots},2a_0}]$}. We prove that $u_d$ < $d$ for all square-free integer $d{\in}S(l;a_1,{\ldots},a_{l-1})$ with one possible exception and apply it to Ankeny-Artin-Chowla conjecture and Mordell conjecture.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.475-478
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• 2005

Deicing salt has been generally used for traffic safety in winter, and the amount is increasing every year. However, deicing salt may induce the decrease of bond strength, surface scaling, and environmental pollution, etc. the purpose of this paper is to suggest the fundamental data on safety and durability for concrete structures through the estimation of chloride concentration profile and chloride diffusion coefficient. According to the test results, the critical chloride concentration($0.9\~1.2kg/m^3$)was measured at depth $23\~30mm$, and the limit chloride concentration($0.3kg/m^3$)was reached to depth 40mm. Also the surface chloride amount indicates 3.45kg per concrete unit weight, and the results showed the possibility of corrosion by deicing salt penetration.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.521-524
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• 2006

In this paper, admixture factors affecting the properties of lightweight foamed concrete incorporating cement kiln dust(CKD) and fly ash(FA), respectively are discussed. Increase in CKD contents resulted in loss of fluidity and decrease in settlement of concrete noticeably. Moreover, the higher the unit weight is, the smaller the settlement depth is. The use of CKD resulted in slight decrease in compressive strength and tensile strength compared to that with other admixture. However, all mixtures met the requirement of strength prescribed in Korean Industrial Standards.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.377-378
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• 2009

The purpose of this study was to evaluate basic physical prorerties of color mortar using an industrial by-product called iron sulphate. First as the characteristic of fresh mortar, addition of iron sulphate reduced flow, air content and unit volume weight. Compressive strength was increased the most at substitution of 6% iron sulphate.