단열소재 종류 및 조합에 따른 외벽단열 패널용 시멘트 복합체의 공학적 특성

한민철,조병영,이건철,노상균,전규남 한국건축시공학회 2011 한국건축시공학회지 Vol.11 No.2

본 연구에서는 단열소재 종류 및 조합의 치환률 변화에따른 외벽단열패널의 공학적 특성에 대하여 분석하였는데,그 결과 굳지않은 모르터의 플로우의 경우 단열소재 치환률이 증가할수록 급격히 저하되는 결과를 나타내었으며, 공기량의 경우 단열소재 치환률이 증가될수록 점차 증가되는 결과를 나타내었다. 경화 모르터의 휨강도의 경우 단열소재치환률이 증가될수록 전반적으로 플레인에 비해 점차 강도가 저하되는 경향을 나타내었으나 PL 2% 치환 시 증가되는결과를 나타내었다. 열전도율의 경우 단열소재 치환률이 증가될수록 급격히 낮아지는 경향을 나타내었으며, 단위용적질량과 열전도율의 상관관계의 경우 단위용적질량이 감소할수록 열전도율은 우수한 결과를 나타내었다. 단열소재 종류및 조합에 따른 휨강도의 경우 전반적으로 플레인과 유사한강도값을 나타내었으나 V+CB+PL을 3% 치환한 조합의 경우 모르터 내부가 밀실해짐에 따라 강도값이 증가되는 결과를 나타내어 단열소재 종류 및 조합 가운데 가장 우수한 결과를 도출할 수 있었다. In this study, the engineering characteristics of outer wall insulation panels according to type of insulation materials, their combination, and the contents of insulation materials were tested. Vermiculate, ceramic bead, perlite and expanded polystyrene were used as insulation materials. Flexural strength and thermal conductivity depending on the insulation materials used were measured. It was found that the flow of fresh mortar significantly decreased with an increase in the contents of insulation materials. In terms of the effect of insulation materials on thermal conductivity, an increase in insulation materials resulted in a decrease of thermal conductivity. In particular, PL and EPS, when used together, have lower thermal conductivity than other materials. Regarding the flexural strength of the hardened mortar, the strength showed a tendency to gradually decrease according to the increase in contents of insulation materials, compared to that of the plain mortar. In terms of the flexural strength depending on various types of insulation materials and its combination, it was found that the flexural strength of cement mortar containing 3% of vermiculate(V)+ceramic bead(CB)+perlite(PL) was the highest among the specimens tested.

유동화 공법에 의한 고유동 콘크리트의 제조에 관한 모의 구조체 적용 실험

한민철,김경민,손성운,김기철,김성수,한천구 대한건축학회 2001 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.21 No.2

This paper presents the results of mock up test on the manufacturing of high fluidity concrete by applying flowing methods with segregation reducing type superplasticizer(SRS). Three kinds of mock up structure are made such as. conventional concrete(A), high fluidity concrete(B) and high fluidity concrete incorporating 20% of fly ash(C). Physical and mechanical properties, temperature history of structure and nondestructive test are performed. Segregation reducing type superplasticizer is put into base concrete at field, and base concrete is also flowed at field. C mock up structure which requires 0.85% of SRS to flow base concrete shows most desirable performance at fresh state. The highest rising temperature shows the lowest at C structure among the tested structures. Strength variations before and after flowing also show the lowest values at C structures.

기후요소에 의한 건설공사 작업불능일 산정에 관한 연구

한민철 청주대학교 2010 産業科學硏究 Vol.27 No.2

The objective of this paper is to compare and provide the estimation of non-working days of the construction project in Seoul due to climate condition such as temperature, rainfall and wind velocity according to climate collecting period. In this study, we applied climate data for 5 years from 2003 to 2008 and 30 years from 1979 to 2008, respectively. The national climate weather temperature has gradually moved up around 25%, however rainfall and wind has not shown much change. In case of rainfall, minimum of 5.3 mm and maximum of 18.9 mm were recorded and the wind speed was generally recorded around 2 m/s. The most of the non working days were found on November through February effected by low temperature, and July through August was recorded high by the reason of high temperature. There were no clear tendency in change of working days in the statistical year. It is thought that July and August were the month with most non working days by rainfall. Generally, the number of dates recorded from minimum of 25 to maximum of 37 days. Not even one non working day was found effected by wind.

충격파쇄석술 후 상부요관결석의 배출에 미치는 Tamsulosin의 역할

한민철,정우식,심봉석 대한비뇨의학회 2006 Investigative and Clinical Urology Vol.47 No.8

고로슬래그를 사용한 초지연 콘크리트의 응결시간 예측

한민철 대한건축학회 2006 大韓建築學會論文集 : 構造系 Vol.22 No.12

This paper presents a method to estimate the setting time of concrete using super retarding agent(SRA) and blast furnace slag(BS) under various curing temperature conditions by applying maturity based on equivalent age. To estimate setting time, the equivalent age using apparent activation energy(Ea) was applied. Increasing SRA content and decreasing curing temperature leads to retard initial and final set markedly. Ea at the initial set and final set obtained by Arrhenius function showed differences in response to mixture type. It is estimated to be from 20~33KJ/mol in all mixtures, which is smaller than that of conventional mixture ranging from 30~50KJ/mol. Based on the application of Ea to Freisleben-Hansen and Pederson's equivalent age function, equivalent age is nearly constant, regardless of curing temperature and SRA contents. This implies that the concept of maturity is applicable in estimating the setting time of concrete containing SRA and BS. A high correlation between estimated setting time and measured setting time is observed. Multi-regression model to determine appropriate dosage of SRA reflecting BS contents and equivalent age was provided. Thus, the setting time estimation method studied herein can be applicable to the concrete containing SRA and BS in the construction fields.

공동주택 바닥 목재 마루널 들뜸 사례에 관한 연구

한민철,최성용,한천구 청주대학교 2009 産業科學硏究 Vol.27 No.1

This paper was to discuss the case and cause of debonding defect of wood floor board in apartment house by investigating field survey. Most frequent defect in wood floor board was debonding of floor board. Scratch, gap and crack of floor board were also found in floor board installment work. Causes of debonding of floor board is shrinkage of cement mortar beneath floor board and expansion of floor board. Haste in floor board work did not provide enough time to dry cement mortar fully, which led to continue to dry after the installment of floor board. It caused moisture movement toward wood floor board. Accordingly, Before floor board work, careful consideration on moisture condition of cement mortar and enough curing time to eliminate the effect of moisture are taken into.

고온양생이 콘크리트의 강도발현에 미치는 영향

한민철 청주대학교 산업과학연구소 2007 産業科學硏究 Vol.24 No.2

In this paper, estimation of compressive strength of concrete subjected to high temperature was discussed. Water to binder ratios ranging from 30% to 60% and curing temperature ranging from 20℃∼65℃ were adopted for experimental parameters. According to results, high curing temperature resulted in an increase in early age strength, while it led to decrease later age strength. for strength estimation, Logistic model based on maturity equation and Carino model based on equivaltlt age were applied to verify the availability of estimation model. It shows that fair agreements betwetl calculated values and measured values were obtained evaluating compressive strength with logistic curve. The application of logistic model at high temperature had remarkable deviations at later maturity. Whereas, the application of Carino model showed good agreements between calculated values and measured ones regardless of W/B. However, correction factors should be considered to enhance the accuracy of later age strength estimation of concrete for both Logistic and Carino model.

적산온도 기법에 의한 시멘트 킬른 더스트 사용 콘크리트의 압축강도 특성 평가

한민철 대한건축학회 2007 大韓建築學會論文集 : 構造系 Vol.23 No.7

This paper is to investigate the effect of the curing temperature on strength development of concrete incorporating cement kiln dust(CKD) quantitatively. Contents of CKD, curing temperature ranging from 5℃~35℃ and water to binder ratio from 40% to 50% were chosen for test parameters. Estimation of the compressive strength of the concrete was conducted using the equivalent age equation and the rate constant model proposed by Carino. Correction of Carino model was studied to secure the accuracy of strength development estimation by introducing correction factors regarding rate constant and age. An increasing curing temperature results in an increase in strength at early age, but with the elapse of age, strength development at high curing temperature decreases compared with that at low curing temperature. Especially, the use of CKD resulted in a decrease in compressive strength both at early and later age slightly, regardless of curing temperature. It is thought that CKD does not play a role in enhancing compressive strength by pozzolanic reaction and its effect on strength development is limited to filler effect. Based on the strength development estimation using modified Carino model, good agreements between measured strength and calculated strength are obtained with 28 days of equivalent age.

AHP 기법에 의한 한중환경 적정 보온양생 공법 결정

한민철 청주대학교 2008 産業科學硏究 Vol.26 No.1

This paper discussed effective decision making for the heat curing method subjected to cold weather condition based on AHP technique. Six priority index for heat curing method is suggested and analysed using AHP. Among 6 priority index, heat insulation capability has the most high value by as much as 41% and convenience in execution. For decision making of proper heat curing method, two different heat curing methods including heat supplying method and heat insulation method using double layer air cap are compared. The heat insulation method has excellent heat insulation capability and convenience in execution based on AHP analysis.

혹한 조건하 열선가열 콘크리트의 강도수준별 온도이력 및 강도발현 특성

한민철 청주대학교 2013 産業科學硏究 Vol.30 No.2

The objective of this study was to experimentally investigate the results of the temperature history and strength development of the concrete with different strength level applying heating coil and bubble sheet exposed to -10°C. The slab and the wall specimens with the size of 1200× 600×200 mm and 900×600×200 mm were fabricated, respectively. The concrete with 30 MPa(4500 psi) and 45 MPa(6000 psi) were applied. Heating coil was embedded into slab specimen covered with quadruple layer bubbled sheet. Heating coil was also embedded into wall specimen. The specimens were cured at curing chamber maintained with -10℃ for 7 days and then they were moved to the chamber with 20℃ for 21 days. Minimum maturity and strength were calculated and measured. Test results revealed that it took more than 3 days to secure the stability against the frost damage at early age of the slab concrete and took more than 1 days for wall concrete having more than 45°D·D of maturity.