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석회석 혼합재의 화학특성이 시멘트 모르타르에 미치는 영향
서동균 ( Suh Dong-kyun ) 한국건축시공학회 2022 한국건축시공학회 학술발표대회 논문집 Vol.22 No.2
Using the limestone powder as material that can substitute the clinker, it seems to get positive effect as filler and enhance workability of cement but the substitution amount and chemical properties of it can affect mechanical properties of cement. Thus, in this study, the effect limestone powder that has other properties on cement is evaluated. As a result, the workability enhancing effect was confirmed but deterioration of compressive strength was also checked. Later, with the view of workability, the experiment that the possibility of strength compensation by decreasing unit water weight of limestone powder cement is planned when the limestone powder is used.
고온이력을 받은 콘크리트의 강도별 기본파와 고조파 특성
서동균 ( Suh Dong-kyun ),김규용 ( Kim Gyu-yong ),손민재 ( Son Min-jae ),사수이 ( Sasui Sasui ),유하민 ( Eu Ha-min ),남정수 ( Nam Jeong-soo ) 한국건축시공학회 2021 한국건축시공학회 학술발표대회 논문집 Vol.21 No.1
The non-destructive method using ultrasonic waves has been applied in many studies due to its low damage to the structure and its simple evaluation method and high precision. On the other hand, if the concrete is subjected to a high-temperature, the mechanical properties may be deteriorated due to the micro-crack network and the damage may be severe depending on the strength of the concrete. Therefore, this study attempts to evaluate the fundamental wave behavior of different strength ranges using the ultrasonic non-destructive method for concrete that has been subjected to high-temperature. As a result, the relative power of the fundamental wave was decreased as temperature increase. And it was confirmed that the 2nd and 3rd harmonics were generated at 110 MPa. However, to check the 2nd, 3rd harmonics 110 MPa or less, there is a need for further research considering the ultrasonic output, the output of the sender and receiver, and the appropriate frequency accordingly.
단위수량 저감에 따른 수화열저감재를 사용한 콘크리트의 수화발열 특성
서동균(Suh, Dong Kyun),김규용(Kim, Gyu Yong),손민재(Son, Min Jae),유하민(Eu, Ha Min),이예찬(Lee, Ye Chan),남정수(Nam, Jeong Soo) 한국콘크리트학회 2021 한국콘크리트학회 학술대회 논문집 Vol.33 No.2
본 연구에서는 수화열저감재 사용에 따른 강도 저하를 보상하기 위해 단위수량을 저감한 고강도 콘크리트의 수화발열 특성을 평가하려고 한다. 간이단열온도 거푸집을 제작하여 시험체 중심부의 온도를 측정하였다. 결과적으로 수화발열 저감과 동시에 강도보상을 위하여 단위수량을 접근하는 방식은 10kg 이내로 하는 것이 워커빌리티를 확보할 수 있을 것으로 기대된다. This study is aim to evaluate the hydration heat characteristics of concrete with a reduced unit water weight in order to compensate for the decreased strength by the use of heat reducer. The simple insulation mold was made, the center temperature was measured. As a result, it is expected that workability can be secured if the method of approaching the unit water weight for strength compensation while reducing hydration fever is less than 10 kg.
MC1R gene의 PCR-RFLP를 이용한 한우,젖소고기 감별
서동균 ( Dong Kyun Suh ) 한국동물위생학회 2008 한국동물위생학회지 (KOJVS) Vol.31 No.3
The objective of this study was to differentiate the beef species between Hanwoo and Holstein from a total of 1,081 beef samples using PCR-RFLP of MC1R gene. When a PCR product of 403 bp specific band amplified from bovine MC1R gene sequence was digested with restriction enzyme MspA1I, Hanwoo type showed 2 bands, 220 bp and 183 bp size bands. Holstein type, however, showed three bands, 220 bp, 138 bp and 45 bp size band, respectively. The results of the differential test for beef species were as following; 7 samples (0.64%) were determined to Holstein type, of which 4 were submitted from administrative authorities, other 3 from self-collection planing, and none from civilian clients including school.
2006년 도축장 출하 지육에 대한 항생물질 잔류현황 분석
서동균 ( Dong Kyun Suh ),박대현 ( Dae Hyun Park ),홍주연 ( Ju Yeon Hong ),임현숙 ( Hyun Sook Lim ),김경희 ( Kyung Hee Kim ),이춘식 ( Chun Sik Lee ) 한국동물위생학회 2008 한국동물위생학회지 (KOJVS) Vol.31 No.1
A total of 3,943 samples (beef 698, pork 2,178 and chicken 1,067)were collected from slaughter houses in Daegu from January to December 2006 for analysis of antimicrobial residues. The results were also comparatively analyzed with those carried out from 16 veterinary service laboratories nationwide as a part of national residue program in 2006. The samples from 11 farms (cattle 2, pig 9) were found to exceed the legal limit. Among them 5 were classified as tetracyclines, 3 as β-lactams, 2 as sulfonamides and 1 as quinolone. Nationally a total of 222 farms (241 cases) were found to violate the residual limits, of which 47.3% were detected by screening test, followed by surveillance (38.3%). Failure to observe withholding periods of antimicrobial drugs after treatment was the most significant cause of the non-compliance.
서중환경에서 스트론튬계 수화열저감재를 사용한 콘크리트의 수화발열특성 평가
서동균 ( Dong-kyun Suh ),김규용 ( Gyu-yong Kim ),길배수 ( Bae-su Kil ),코야마토모유키 ( Tomoyuki Koyama ),남정수 ( Jeong-soo Nam ) 한국구조물진단유지관리공학회 2020 한국구조물진단유지관리공학회 논문집 Vol.24 No.6
초고층 건축물과 같은 대형 건축물의 부재가 대형화 되면 수화발열로 인하여 내 외부 온도차가 커져 균열이 발생한다. 잠열재인 상전이 물질을 수화열저감재로써 사용하는 방법은 다른 방법들보다 접근성, 사용성, 효율성이 높다. 이에 따라 수화열저감재로 상전이 물질을 사용한 연구들이 많이 진행되고 있다. 하지만 상전이 물질은 상전이 반응온도가 다르기 때문에 외기온도, 콘크리트 비빔온도 같은 환경요인에 영향을 받을 수 있는데 이를 고려한 연구는 미미한 수준이다. 따라서 본 논문에서는 서중환경에서 수화열저감재를 사용한 콘크리트의 수화발열특성과 품질을 평가하였다. 그 결과, 서중환경에서 스트론튬계 수화열저감재를 3wt.%, 5wt.%를 혼입했을 경우, OPC수준보다 수화발열은 8%, 21% 저감이 가능하고 발열속도는 약 75분, 85분 정도 지연할 수 있는 것으로 나타났다. 이는 온도가 높을 때 상전이 반응이 상대적으로 촉진되어 실험실환경보다 향상된 성능 나타난 것으로 판단된다. 향후 서중환경에서 다른 종류의 수화열저감재 효율과 비교하고, 장기 재령에서의 강도발현 등에 대한 세부적인 검토를 진행할 예정이다. When concrete member become large like in high rise buildings, hydration heat makes temperature difference inside and outside and cause cracks. The method of using latent heat material as heat reducer could be more accessible, usable and efficient than other methods. Therefore, many studies using PCM as heat reducer are being conducted. Since heat reducer have different reacting temperature, they may be affected by environmental factors like ambient and concrete mixing temperature but studies issuing this are insignificant. Therefore, this paper attempt to evaluate the hydration heat characteristics and quality of concrete using strontium-based PCM under hot weather conditions. As a result, when the strontium-based hydration heat reducer was mixed 3wt.% and 5wt.% in hot weather condition, hydration heat speed and heating rate could be reduced by 8%, 21%, and 75, 85 minutes compared to OPC, respectively. This is considered to be the phase change reaction is relatively promoted when the temperature is high and cause improve performance than room condition result. Later, comparing the efficiency of other types of P.C.M in hot weather condition, and conduct detailed reviews on the strength development in long-term age.