• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.161-169
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• 2000

Recycled aggregates were generated when concrete structures were dismembered. However, in concrete structures, because of durability, strength and toughness, recycled aggregates don't use generally. This study was done to use recycled aggregate in concrete structures. Problems of durability, strength, and toughness were caused troubles, when recycled aggregates were used, were solved as steel fibers and additives were added. Of course, steel fiber length, steel fiber contents, additive substitution, and recycled aggregate substitution were variables of this study. After flexural specimens($15{\times}15{\times}70cm$) with notch(45mm) were fabricated, basic strength tests were done and toughness was estimated using fracture mechanics parameters. The results suggest that JIC is a promising fracture criterion for all of these, while KIC(or GIC) almost certainly are not.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.77-80
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• 2005

Lightweight concrete is known for its advantage of reducing the self-weight of the structures, reducing the areas of sectional members as well as making the construction convenient. Thus the construction cost can be saved when applied to structures such as long-span bridge and high rise buildings. However, the lightweight concrete requires specific mix design method that is quite different from the typical concrete, since using the typical mix method would give rise the material segregation as well as lower the strength by the reduced weight of the aggregate. In order to avoid such problems, it is recommended to apply the mix design method of self-compacting concrete for the lightweight concrete. Experimental tests were performed as such compressive strength, dry shrinkage and carbonation of high strength lightweight self-compacting concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.365-368
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• 2005

Waste concrete powder(WCP) has been estimated with a great value-added material as by-product of waste concrete manufactured to fine and coarse aggregate for concrete, because it is able to utilized for cement clinker and concrete admixture. Experimental tests were performed as such plastic viscosity of paste, flow and compressive strength of mortar by surface area of WCP. As a result, flow and 28days compressive strength of mortar was decreased according to increased replacement ratio of WCP as compared to control mortar. Also, plastic viscosity of paste used WCP1 and WCP2 was decreased with increasing replacement ratio, but WCP3 was increased with increasing replacement ratio.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.546-547
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• 2013

This paper proposes an arc fault circuit interrupter (AFCI) using the distorted voltage wave in electric arc faults. It perceives a voltage instantaneously at the time of voltage drop. and occurrence. It is an AFCI of the new concept which operates with high reliability. The primary reason of electric fire is arc and spark. It prevents an electric fire or an electric leakage accident with quick responsiveness. Earth Leakage Circuit Breaker(ELB), Molded_case Circuit Breaker (MCCB) or Residual Current Protective Device(RCD) can not cut off electric arc or spark to be a major factor of electrical fire. This theory will be able to intercept an arc or a spark. which occurrence with periodic. Consequently It raises a reliability and validates a practicality of RCD.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.499-500
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• 2017

This study is about a sound source direction detection system and method using intelligent source collection and analysis. The sound source direction detecting apparatus according to the present invention is equipped with four microphone sensors and calculates a time difference using TDOA (Time Delay of Arrival) technique for a plurality of acoustic signals generated from a sound source, And a sound source detection and analysis algorithm for estimating the direction of the sound source.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.5-6
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• 2014

According to 2013 fire statistical yearbook in the National Emergency Management Agency, the main cause of an electrical fire are classified to short circuit fault, overload fault, electric leakage, partial disconnection, and joint/contact badness. The occurrence factor of fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Devices(RCDs) of high sensitivity type used at single phase (220V) cut off earth leakage and overload but the RCDs can not cut off electric arc or spark to be a main cause of electrical fire. To be improved on such problem, this thesis is proposed to a auxiliary control device for RCD cut off electric arc or spark.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.3
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• pp.229-234
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• 2010

This paper presents the analysis of pitch static attitude(PSA) in thermally assisted magnetic recording(TAMR) suspension. The TAMR suspension using an optical fiber has high stiffness such as vertical, pitch and roll. Therefore, P-torque is greatly increased by the optical fiber. Also, flying height(FH) of the slider with TAMR suspension can be largely changed by PSA. In this paper, we focus on the FH by PSA of TAMR suspension. The FH is investigated using various PSA and proper PSA is proposed.

• Annual Conference of KIPS
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• 2012.11a
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• pp.1531-1534
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• 2012

모델기반 아키텍처 MDA (Model Driven Architecture)는 소프트웨어 개발의 추상화 수준을 높이기 위한 최근의 개발 아키텍처이며 완벽한 이해성을 확보하기 위해서 구체적인 구현기술은 반드시 개발자에게 추상적으로 (encapsulation) 숨겨져야 한다. 즉, 개발자는 자동적으로 실행 가능한 시스템으로 변환하는 플랫폼에 구애 받지 않는 모델들 PIM(Platform Independent Model)만을 고려하게된다. 본 논문에서는 MDA 를 캠퍼스 안내 앱에 적용하여 개발함으로써 모바일 디바이스 및 OS 에 독립된 어플리케이션을 개발 방법론을 제시한다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.24 no.2
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• pp.83-93
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• 1988

Recent Experimental results show that the J integral can be effectively used to obtain a valid parameter for predicting plane strain and plane stress fracture. However, only a few research results have been reported for the effect of thickness where the plane strain state can not be assumed. A purpose of this study is to find the behavior of fracture touhness and tearing modulus varing the specimen thickness. The type of specimen in the present study is compact tension (CT). The thicknesses of the low carbon steel specimens that are used in the experiments are 5, 10, 15, 20 and 25mm. The measurement of crack length is taken by optical measurements method. From the study, the followings are found; 1) The fracture toughness and the tearing modulus which are obtained by using Yoon's and Simpson's formula show more conservative than that by using Rice's and Merkel's. 2) The fracture toughness is increase in specimen thickness which is reached 15mm. Beyond this thickness the fracture toughness is decreased in specimen thickness. 3) In the case of CT specimen with the thickness ranging from 5 to 25mm, the tearing modulus which is applied the same J integral equation is almost constant. 4) By using Yoon's formula, the correlation of the plane slress fracture toughness J sub(C) with specimen thickness B is expressed as the following formula. J sub(C)/J sub(IC)=1.7-15.1(B/W)+112.9(B/W) super(2) -301.3(B/W) super(3) +260.6(B/W) super(4)

• Journal of Industrial Convergence
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• v.18 no.3
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• pp.53-61
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• 2020

Travel speed is an important parameter for measuring road traffic and incident detection system. In this paper I suggests a model developed for estimating reliable and accurate average roadway link travel speeds using image processing sensor. This method extracts the vehicles from the video image from CCTV, tracks the moving vehicles using deep neural network, and extracts traffic information such as link travel speeds and volume. The algorithm estimates link travel speeds using a robust data-fusion procedure to provide accurate link travel speeds and traffic information to the public. In the field tests, the new model performed better than existing methods.