Implementation of UPT Service in WIN-Based Mobile Communication Networks

Yun Won Chung(정윤원),Min Young Chung(정민영),Dan Keun Sung(성단근),In Jeong Kim(김인정),Jung Keun Shin(신정근),Sung Kim(김성) 한국통신학회 1999 한국통신학회 학술대회 및 강연회 Vol.1999 No.4

콘크리트 공극 분석을 위한 평면간격계수의 제안

정원경,최성용,김성환,윤경구 江原大學校 産業技術硏究所 2005 産業技術硏究 Vol.25 No.A

Air void systems in hardened concrete has an important influence on concrete durability such as freeze-thaw resistance, water permeability, surface scaling resistance. Linear traverse method and point count method described at ASTM are the routine analysis of the air void system that have been widely used to estimate the spacing factor in hardened concrete. Recently, many concretes often have a spacing factor higher than the generally accepted 200-250㎛ limit for the usual range of air contents. This study is proposed to estimate the plane spacing factor by calculation of simplicity. The plane spacing factor need two parameters that are air content and numbers of air voids in the hardened concrete. Those obtained from the standard air-void system analysis of the ASTM C 457. The equation is valid for all values of paste-to-air ratio because the estimation of paste content is unnecessary at the using ASTM C 457. The plane spacing factor yields a similar estimate of the standard spacing factor.

콘크리트 鋪裝의 初期計測을 통한 初期擧動 特性分析

정원경,김동호,권혁찬,윤경구 강원대학교 산업기술연구소 2003 産業技術硏究 Vol.23 No.A

The purpose of this paper is to analysis of initial behavior of concrete pavement with initial measurement strain gauge for concrete pavement at field, and to investigate the field test results for field applicability testing. The early-age behaviors of concrete pavement slabs were measured using the strain gauges. From the slab depths and positions, the outputs from each gauges were recorded at initial curing period The initial measurement of concrete pavement and check of crack at the joint were performed. the results could be summarized as follows. From the results of concrete strength, compressive strength and flexural strength were showed 271kgf/㎝', 43kgf/㎝' respectively. From the tests of early-age strain measurement, it was found that the strain varied at the maximum value of 150μ ε and early1 behavior of concrete slab was showed a tensile strain However. for long-term was showed a compressive strain due to dry-shrinkage.

소포제를 이용한 초속경 LMC의 특성 개선연구

윤경구,김성환,정원경,권혁찬 강원대학교 부설 석재복합신소재 제품연구센터 2003 석재연 논문집 Vol.8 No.-

본 논문은 콘크리트 배합시 발생하는 과도한 기포 발생 문제점을 해결하기 위하여 최적의 소포제 종류 및 혼입률 범위를 산정하여 초속경 라텍스개질 콘크리트 성능을 개선하는 것이다. 초속경 라텍스개질 콘크리트 실험은 2종류의 소포제 A, C와 혼입률 0, 1, 2, 3%을 주요 변수로 하여 공기량 시험, 압축강도 및 휨강도 시험을 수행하였다. 또한, 내구성 평가를 위하여 염소이온 투과실험도 수행하였다. 초속경 라텍스 개질 콘크리트의 공기량시험 결과 소포제 종류에 상관없이 소포제 혼입률 1%이상 첨가시 공기량은 50%이상 감소하였다. 또한, 소포제 첨가에 의한 기포 발생량 감소에 의해서 압축강도의 증진을 이루었다. 초속경 라텍스개질 콘크리트 실험은 A, C 소포제로 선정하여 실험을 수행하였다. 초속경 라텍스개질 콘크리트의 강도 특성에서는 A 소포제 혼입률 1%에서 압축강도 235kgf/㎠ , 휨강도는 조기 교통개방에 요구되는 휨강도 기준 45kgf/㎠를 초과하는 49kgf/㎠를 나타내었다. The purpose of this study was to remove the excessive air foaming which was produced in mixing the RSLMC(latex-modified concrete with rapid-setting cement) by choosing the best antifoam agent type and the optimized quantity for performance improved RSLMC. The main experimental variables such as antifiamer types(A, C), antifoamer contents(0, 1, 2, 3%), and latex contents(15%). Air content test and compressive, flexural tests were carried out to measure the improved properties of RSLMC. the rapid chloride permeability was carried out to estimate a durability of RSLMC. The results of RSLMC showed that the decrease of 50% air content was obtained by admixturing a antifoam agent by 1%. Two kinds and the optimized quantities of antifoam agent were selected for using in RSLMC. The results of RSLMC were obtained at a latex content of 15% and a antifoam agent quantity of 1% with antifoamer A type. The compressive strength and flexural strength at 3 hours after RSLMC placement were 235kgf/㎠ and 49kgf/㎠, respectively, which exceeded the flexural strength criterion of 45kgf/㎠ in order to open the RSLMC placed to traffic.

초음파 전파 및 산란 문제의 유한요소 해석

정현조,박문철,박윤원 한국비파괴검사학회 2002 한국비파괴검사학회지 Vol.22 No.4

초음파의 전파와 결합에 의한 산란장의 정확한 해석은 초음파 비파괴평가에서 중요한 역할을 한다. 수치해석법은 매개변수에 대한 연구를 간단하고 값싸게 할 수 있으므로 결함 탐지 확률을 높이고 결과적으로 검사의 신뢰도를 개선시키는데 도움이 된다. 본 연구에서는 초음파 전파와 산란장의 계산을 위하여 유한요소법(finite element method)을 사용하였으며, 대표적인 몇 가지 문제에 대하여 시뮬레이션을 실시하여 해석의 타당성을 검증하였다. 상용 FEM 프로그램을 이용하여 안정적인 수치해를 얻기 위한 유한요소 격자 크기와 시간 근사 스텝을 먼저 결정하였다. 2-D등방성 및 이방성 재료에서의 전파와 산란 문제를 다루었으며, 이론적 정해 또는 실험 결과가 알려진 문제를 선정하여 FEM 해석 결과와 비교, 분석하였다. The accuate analysis of ultrasonic wave propagation and scatttering plays an important role in many aspects of nondestructive evaluation. A numeracal analysis makes it possible to perform parametic studies, and in this way the probability of detection and reliability of test results can be improved. In this study, a finite element method was developed for the analysis fo ultrasonic fields, and the accuracy of results was checked by solving several representative preblems. The size of element and the integral time step, which are the critical components for the convergence of numerical results, were determineed in a commercial finite element code. Several propagation and scattering problems in 2-D isotropic and anisotropic materials were solved and their results were compared with known analytical or experimental results.

라덱스 혼입률에 따른 철근콘크리트의 휨파괴 거동특성

정원경,김동호,이주형,임홍범,윤경구 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.A

Reinforced concrete(R/C) is commonly used to structures because they have many merits that compressive strength, economy and so on. However, reinforced concrete has a crack at the tensile section which is due to the relatively lower tensile strength than its compressive strength. Latex modified concrete(LMC) has higher tensile and flexural strength than the ordinary portland cement, due to the interconnections of hydrated cement and aggregates by a film of latex particles. The purpose of this study was to investigate the flexural behavior of reinforced concrete beam with latex modified concrete, having the main experimental variables such as concrete types(ordinary portland cement concrete, latex modified concrete), latex contents(0%, 15%), flexural steel ratios(0.012, 0.0235), and with/without shear reinforcement. The beam of LMC showed considerably higher initial cracking loads and ductility than that of OPC, but, similar to ultimate strength and deflection. This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation. The beam with latex modified concrete could be adopted at field for controlling and reducing the tensile crack due to its higher tensile strength.

자동차 허브 내·외경 측정 시스템 개발

윤규택,이동주,최만용,박해원,박정학 한국공작기계학회 2002 한국공작기계학회 춘계학술대회논문집 Vol.2002 No.-

An automobile hub is composed of a hollow cylindrical part with inner and outer diameters. These hub diameters must be precise, as any irregularities in them (diameters) can influence/degrade the motion of an automobile with this problem. Highly accurate and reliable hub inner and outer diameters measurement systems are therefore required for inspection of the diameters. In this research, an automobile hub inner and outer diameters measurement system has been developed and tested. The system consists of measuring heads with LVDT sensors, and associated software for automatic measurement and calibration of the diameters and the sensors respectively. The system has been evaluated in comparison with an existing measurement system, and the following outcomes have been achieved; ·Improved and guaranteed quality and reliability ·Increased productivity and cost reduction These results prove the system developed in this research to be suitable for automobile hub inspection.

수직 냉각면이 있는 정방형내 성층유체의 열적거동에 관한 실험적 연구

정현철,윤재원,장원택,전승배,이동석,김병철 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.1

This study was investigated by experimentals on the thermal behavior of stratified fluids in the square cavity with the vertical cooling surface by variation of initial temperature and cooling surface temperature and concluded as follows: 1. When the cooling surface temperature of the square cavity was -4℃. the supercooling phenomena was occurred every times regardless initial temperature of fluids and when -6℃ freezing was begun with out supercooling phenomena. 2. The higher the initial temperature was, the longer supercooling phenomena duration was, and the longer the supercooling phnomena was, the higher the temperature of the upper fluids was. 3. When the supercooling phenomena of water was occurred, the rate of temperature decrease of silicon oil was higher and when there was no supercooling phenomena, it was almost same the rate of temperature decrease.

치과용 디지털 색상 분석용 기기의 정확성과 재현 능력에 대한 평가

정중재,박수정,조현구,황윤찬,오원만,황인남 大韓齒科保存學會 2008 Restorative Dentistry & Endodontics Vol.33 No.4

본 연구에서는 치과용 디지털 색상 분석기기 중 하나인 ShadeScan (CYNOVAD, Montreal, Canada)의 색상 분석의 정확성과 재현 능력을 평가하였다. 균일한 치아 배열을 가진 20대 성인 남자 8명과 여자 8명의 상악 인상을 고무인 상제 (Exaflex, GC, Japan)를 이용하여 채득하고, 인상에 A2 색상의 임시 크라운 제작용 자가중합형 레진을 주입하여 치아 모델을 완성하고, ShadeScan을 이용해 각 치아의 영상을 얻어 컴퓨터의 ShadeScan 프로그램으로 분석하였다. 그리고 측정 결과의 재현 능력를 평가하기 위해 2개의 치아 모델을 임의로 선택하여 각 치아마다 10회의 색상 측정을 시행하여 분석 결과를 비교하였다. 또한 분석된 영상의 동일 shade 간의 색차를 확인하기 위해 광중합 복합레진인 Gradia Direct (GC, Tokyo, Japan)와 shade guide의 CIE L^(*)a^(*)b^(*) 값을 백색과 흑색 배경판 상에서 spectrophotometer (Spectrolino, GretagMacbeth, USA)로 측정하고, ShadeScan에 의해 동일한 shade로 분석된 shade guide간의 색차를 계산하여 다음의 결과를 얻었다. 모든 치아에서 모델 제작 재료와 동일한 A2 색상므로 분석된 경우는 없었으며, 개개의 치아에서 전체 순면이 동일한 색상으로 분석된 예는 없었다. 또한 동일한 치아군에서 치아의 크기 , 형태 , 순면의 굴곡 등에 따라 서로 다른 색상 분포를 보였다. 재현성 평가에서 각 치아의 중앙부는 비교적 일정한 재현성출 보였으나, 절단부와 주변 부위는 재현성이 낮았으며, 동일한 shade로 분석된 shade guide 간에는 3 이상의 색차 (ΔE^(*))를 보였다. 이상의 결과는 치과용 디지털 색상 분석기기는 비록 높은 재현 능력은 가지고 있지만 정확성에 오류가 있음을 시사하며 , 따라서 이러한 기기를 이용한 색상 분석 시 좀 더 세밀한 주의와 다른 방법의 추가 사용이 필요하리라 사료된다. This study was done to evaluate the reliability of the digital color analysis system (ShadeScan, CYNOVAD, Montreal, Canada) for dentistry. Sixteen tooth models were made by injecting the A2 shade chemical cured resin for temporary crown into the impression acquired from 16 adults. Surfaces of the model teeth were polished with resin polishing cloth. The window of the ShadeScan handpiece was placed on the labial surface of tooth and tooth images were captured, and each tooth shade was analyzed with the ShadeScan software. Captured images were selected in groups, and compared one another. Two models were selected to evaluate repeatability of ShadeScan, and shade analysis was performed 10 times for each tooth. And, to ascertain the color difference of same shade code analyzed by ShadeScan, CIE L^(*)a^(*)b^(*)values of shade guide of Gradia Direct (GC, Tokyo, Japan) were measured on the white and black background using the Spectrolino (GretagMacbeth, USA), and Shade map of each shade guide was captured using the ShadeScan. There were no teeth that were analyzed as A2 shade and unique shade. And shade mapping analyses of the same tooth revealed similar shade and distribution except incisal third. Color difference (ΔE^(*)) among the Shade map which analyzed as same shade by ShadeScan were above 3. Within the limits of this study, digital color analysis instrument for dentistry has relatively high repeatability, but has controversial in accuracy.

VES-LMC 덧씌우기를 이용한 콘크리트 포장 보수

정원경,김용곤,김기헌,윤경구 강원대학교 산업기술연구소 2005 産業技術硏究 Vol.25 No.B

Since in 1970, the length of concrete pavements(JCP, JRCP and CRCP) are growing rapidly at both of main highways and local roads. Many of them are deteriorated and old enough to be repaired or replaced. The pavement is more important than the other infrastructures and it is very difficult to go around or block the traffic during the rehabilitation. The very-early strength latex-modified concrete(VES-LMC)may offer the advantages of high-early-strength, higher flexural strength, higher bond strength, and improved durability. The VES-LMC could be used at a kind of fast track ofr early opening to the traffic after 3 hours of concrete placement. The installation of VES-LMC overlay at Jung-Boo highway was successfully done from April 28 to 29, 2005. The traffic was closed at 07:00 PM and opened to traffic at 08:30 AM. The compressive and flexural strength of VES-MC were more than 28MPa, 6.2MPa after 4 hours, respectively.