현장실험을 통한 VES-LMC 균열발생 원인 분석

최판길,이봉학 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.A

Many concrete bridge decks develop transverse cracking shortly after construction. These cracks accelerate corrosion of reinforcing steel and lead to concrete deterioration, damage to components beneath the deck, unsightly appearance. These cracks shorten the service life and increase maintenance costs of bridge structures. In this study, VES-LMC overlay, which provides the same benefits as a conventional overlay, is designed to cure very quickly. Although the materials for VES overlays are more expensive, the cost is more than offset by the savings on traffic control and work zone safety measures. Otherwise, reaction of hydration occurs very rapidly in beginning step(concrete placing). As a results, thermal cracking can be occur by thermal stress in accordance with hydration-heat The purpose of this study was to estimate diagnosis of crack occurrence of VES-LMC through field tests at early-age.

구조적 분석과 DP정합 방법에 의한 한글인식에 관한 연구

유봉길,문창수 順天靑巖大學 1994 論文集-順天靑巖大學 Vol.18 No.-

In this paper, an on-line recognition system for hand-written Korean characters using Structure Analysis and DP Matching Method was implemented. Korean "Hangul" consists of a phonetic alphabet containing consonants and vowels. The consonants were divided into two groups: the standard fourteen simple consonants and five double consonants. Similarly, eleven double vowels have been added to the standard ten simple vowels. These forty make up the basic letters of the Korean alphabet for the purpose of this research. The proposed algorithm, invariant to size and distance, reduces greatly the computational requirement of dynamic programming by matching phonemes rather than character patterns. where the angle difference and the ratio of lengths between input and reference patterns are adopted as matching features. it converts the mouse input into character vector composed of stroke type and relative start position.

算術平均에 의한 바닥衝擊音 遮音性能 評價에 관한 硏究

장길수,남기봉,문연준 東新大學校 1999 論文集 Vol.11 No.-

It is known that arithmetic mean values of impact sound have an unexpectedly high correlation with the loudness of the sound. This measure is simple and much more easily obtained than the measures specified in tile existing standards. This finding was obtained by psycho-acoustic experiments, however, not by field experiments. This paper aims to specify the relationship between this measure and existing measure, L value by JIS A 1419, and to review the proper range of frequencies to be considered by using 63 data of actual impact sounds for domestic floors. As a result, arithmetic mean values of sound levels showed good correlation with L values. And mean values in octave bands from 125 to 2㎑ were proper for light weight impact sound and those from 125 to 2kH were proper for heavy weight impact sound. In addition it was found that L values(by JIS A 1419) estimated from same floor could be underestimated compared to arithmetic values.

초속경 라텍스개질 콘크리트의 균열 억제방안

이봉학,최판길 江原大學校 産業技術硏究所 2008 産業技術硏究 Vol.28 No.A

An increase in the amount of cracking in repaired concrete bridge decks using VES-LMC(Very Early Strength - Latex Modified Concrete ; below VES-LMC) has been noticed by Yun et a1(1). Literature indicates that indeed many concrete bridge decks develop transverse cracking, most developing at early ages(3~7 days), many right after construction. The purpose of this study was to establish prevention of map, transverse and longitudinal cracking in VES-LMC and to provide a control methods for minimizing the occurrence of cracks. The proposed prevention against map and transverse cracking was verified by field ayplications. VES cement was modified, the unit cement contents was reduced into 360kg/m^(3) from 390kg/m^(3), the maximum size of coarse aggregate was increase into 19mm from 13mm, wire mesh and steel fibers were incorporated in concrete mixture. A series of variable combinations were attempted. As a results, the proposed prevention against map and transverse cracking was verified because no crack were occurred until 90 days after overlay.

건물 피난관련규정의 국가별 차이 비교

장길수,남기봉 東新大學校 1997 論文集 Vol.9 No.-

There are fire safety provisions in building codes for means of escape. But these provisions don't satisfy the new concepts and technics of architectual planning and forms. In this study, the escape provisions in the codes and regulatoins of 5 countries are compared. The concept and differences among countries are discussed for developing perfomance based standards. The fundamental difference between Korea and other countries in escape capacity is based on the occupant load factors.

MPP^+와 6-OHDA에 대한 한약탕제의 보호효과 연구

강봉주,홍성길,조동욱 한국한의학연구원 1999 한국한의학연구원논문집 Vol.5 No.1

The effect of herbal medicine on 1-methyl-4-phenylpyridinium ion(MPP+) and 6-hydroxydopamine(6-OHDA) mediated neurotoxicity was studied in the rat phaeochromocytoma cell line PC12. The present study was designed to test the hypothesis that herbal medicine can protect cells from neurotoxiciy caused by MPP+ and 6-OHDA. Exposure of PC12 cells to 0.2mM MPP+ and 50 μM 6-OHDA for 24h resulted in a 50% cell death with respect to the control cells. MPP+ induced cell death was reduced by Yollyounggobondan(延齡固本丹), Sagunjatang(四君子湯), Palmihwan(八味丸), and Palmultang(八物湯) (p<0.05). However, herbal medicines did not protect cells trom degeneration caused by the 6-OHDA. Yollyounggobondan, Yungmijihwangwon(六味地黃元), Palmultang, and Samultnag(四物湯) were effective in protecting against MPP+ induced ATP loss in PC12 cells (p<0.05). Yollyounggobondan and Palmultang were effect in neurite protection against 6-OHDA treatment in differentiated PC12 cells with NGF.

교량 바닥판 보수공사에서 발생하는 콘크리트 폐수처리 방안

이봉학,최판길,김정기 江原大學校 産業技術硏究所 2008 産業技術硏究 Vol.28 No.A

As of 2003, construction waste has been produced at the level of 130,614.8 tons/day, in which the amount of waste concrete was 92,639.1 tons/day and accounted for about 66.4% of the amount of construction waste. Waste concrete is mainly produced in construction work and civil engineering work. Especially, road surface crushing method using a large amount of water requires thorough management of concrete wastewater. The aim of this study was to analyze water pollution due to concrete wastewater generated in repair of bridge deck using road surface crushing equipment and to suggest reasonable countermeasures for solve the problem. In this study, it was surveyed current conditions of produced concrete wastewater in bridge deck repair, analyzed physical features of concrete wastewater, expected effects of water pollution on inflow rivers if it is not treated, established treatment plan of water pollution by categories, and calculated capacity of each treatment process and required amount of necessary chemicals. As a result of sampling wastewater generated in field sites and testing it at a lab scale, it was revealed that the original wastewater was produced in removing concrete from bridge deck slabs using surface crushing equipment whose pH was 12.53, CODMn was 12.910mg/L, SS was 547.0mg/L, and other heavy metals were included in extremely small quantities.

초속경 라텍스개질 콘크리트의 균열발생 특징분석

이봉학,최판길 강원대학교 산업기술연구소 2007 産業技術硏究 Vol.27 No.A

Concrete is a material that will crack during its service life by its very nature. For bridge decks this is especially significant as these cracks allow accelerated ingress of chlorides and the subsequent corrosion of the reinforcing steel and deck deterioration. Very-early strength latex-modified concrete (below ; VES-LMC) was developed in order to realize early-opening-to-traffic bridge deck concrete. Although there has been little research to document the degree of cracking in VES-LMC overlay, there has been a general perception among highway agencies that overlay cracking of VES-LMC, particularly early-age cracking, is a one of problems which should be solved. The purpose of this study was to analyze the cause of map, transverse and longitudinal cracking in VES-LMC and to provide a control methods for minimizing the occurrence of cracks. The proposed prevention against map and transverse cracking was verified by field applications. VES cement was modified, the unit cement contents was reduced into 360kg/㎥ from 390kg/㎥, the maximum size of coarse aggregate was increase into 19mm from 13mm, wire mesh and steel fibers were incorporated in concrete mixture.

Hough Transform을 이용한 일부 파손된 영상복원 알고리즘 구현

유봉길,정종필 順天靑巖大學 1995 論文集-順天靑巖大學 Vol.19 No.-

This paper presents a method of restore lines and ellipses from the image by using Hough transform. For ellipse restoration parameters of the ellipse are restored by Least Square Method using particular points that contain geometric properties of the ellipse, instead of accumulating Hough array. Lines and ellipses are restoration, lines are first restored by conventional Hough transform, then the data of lines are eliminated to reduce the calculation cost and also to ease restoration of ellipses.

음원 방향각 추정에 관한 계산기 시뮬레이션

이채봉,김정국,김길중 東西大學校 1998 동서논문집 Vol.4 No.-

In this paper describes the optimum beamforming algorithm when it estimates source signal localization. It is proposed many methods for the identification of a sound source localization. But in this study, compares and ivestigates the angle resolution and sharp peak value by the simulation. The simulation perform to each of DSA(Delay Sum Arry), MV(Minimum Variance), MUSIC(MUltiple SIgnal Classification) method when signals with two or three frequency exist. In result, the MUSIC method has excellent angle resolution and sharp peak value in estimating the derection of arrival signals at each microphone for arbitrary direction of the sound source singnal.