Mock-Up 시험에 의한 고성능 콘크리트의 수축특성 분석

한천구,강수태,고경택,한창평 한국구조물진단유지관리공학회 2006 한국구조물진단유지관리공학회 논문집 Vol.10 No.5

본 연구는 개발된 저수축 고성능 콘크리트를 대상으로 모의부재 시험체에 있어서 콘크리트의 기초적 물성과 수축특성에 대하여 검토한 것이다. 실험연구 결과, 콘크리트의 배합특성으로 제안 배합은 목표 슬럼프플로우 및 목표 공기량을 만족하기 위해 SP제량 증가, AE제량 감소의 배합보정이 필요하였다. 응결시간은 제안 배합이 8시간 정도 빠르게 나타났으며, 굳은 콘크리트의 압축강도는 60MPa 이상의 고강도로 나타냈다. 수축특성으로 제안 배합 자기수축의 경우 플레인 배합 자기수축에 비해 50% 정도 저감되었고, 제안 배합의 중심부 건조수축은 수분발산이 없는 것에 기인하여 자기수축과 유사한 경향이었으나, 표면부는 크게 수축하였다. 단, 철근배근 시험체인 경우는 철근구속에 의해 내부 및 표면의 수축량이 작게 나타났다. This paper investigates the fundamental properties and shrinkage characteristics of low shrinkage high performance concrete(LSHPC), using mock-up specimens. According to the test results, the most suitable mix proportions of LSHPC need a higher dosage of SP agent and AE agent, in order to obtain the target of slump flow and air content. This is due to reduce fluidity and air content respectively. It also presented earlier setting time than control concrete by 6 hours and exhibited compressive strength of 60MPa at age 28 days. Autogenous shrinkage of LSHPC was the half of the value of control concrete. Drying shrinkage of center section of LSHPC showed similar tendency with autogenous shrinkage, because of no internal moisture movement, while surface section had larger drying shrinkage. The specimen with embedded reinforcing bar had smaller deformation owing to confinement of reinforcing bar.

최대 사이클링 운동 중 무산소성 파워와 하지 골격근의 근수축 특성 사이의 관계

이윤곤 ( Yungon Lee ),신성훈 ( Sunghoon Shin ) 한국체육학회 2020 한국체육학회지 Vol.59 No.3

본 연구의 목적은 최대 사이클링 운동에서 무산소성 파워에 영향을 미치는 하지근육과 무산소성 파워를 예측할 수 있는 근수축 특성이 무엇인지를 밝히는데 있었다. 총 24명의 남성 참가자(age: 23.0±2.0 years, height: 175.7±4.4cm, and weight: 76.3±8.7kg)가 연구에 참여하였다. 참가자의 최대 사이클링 운동 중 무산소성 파워를 평가하기 위해 윈게이트-검사(Wingate-test)를 실시하였고, 하지근수축 특성은 근장력계(Tensiomyography)를 사용하여 측정하였다. 통계 분석은 무산소성 파워 변인인 무산소성 최대 파워(peak power), 평균 파워(mean power), 피로율(rate to fatigue)을 종속변인으로 각각 설정하고, 9개의 하지근육(대퇴 이두근, 외측 비복근, 내측 비복근, 대둔근, 대퇴직근, 반건양근, 전경골근, 외측 광근, 내측 광근)의 근수축 특성 변인(maximum displacement(Dm), contraction time(Tc), delay time(Td), sustain time(Ts), relaxation time(Tr))을 독립변수로 하는 단계적 입력방법(step-wise method)의 다중회귀분석(multiple linear regression analysis)을 실시하였다. 연구결과 외측 비복근(gastrocnemius lateralis)의 근수축 속도를 나타내는 Tc와 근경직도를 나타내는 Dm이 측정값이 낮아질수록 최대무산소성 파워가 증가되었다. 따라서 본 연구는 일반인이 실내자전 거에르고미터에서 최대 사이클링 운동을 실시할 때 근장력계(TMG)를 통한 근수축 특성을 통해 최대무산소성 파워를 예측가능하며, 최대무산소성 파워를 발휘하기 위해서는 상대적으로 외측 비복근(GL)의 근수축 특성이 중요하다는 사실을 밝혔다. The purpose of this study was to reveal the lower extremity muscles affecting the anaerobic power in the maximum cycling exercise and what musculoskeletal characteristics could effectively predict the anaerobic power. A total of 24 male participants (age: 23.0±2.0 years, height: 175.7±4.4cm, and weight: 76.3±8.7kg) participated in the study. A wingate-test was performed to assess the anaerobic power of the participants’ maximum cycling exercises, and the contractile properties of the lower extremity skeletal muscles characteristics were measured using a tensiomyography(TMG). In statistical analysis, the anaerobic power variables, i.e. anaerobic peak power, mean power, and rate to fatigue, were set as the dependent variables respectively, Multiple linear regression analyses of step-wise method, with the nine muscles (i.e., BF: biceps femoris; GL: gastrocnemius lateralis; GM: gastrocnemius medialis; GT: gluteus maximus; RF: rectus femoris; ST: semitendinosus; TA: tibialis anterior; VL: vastus lateralis; VM: vastus medialis.) as independent variables, were performed. The study showed that the lower the measurement of the Contraction time (Tc) of the gastrocnemius Lateralis, the greater the peak power. Therefore, it was revealed that when the general public carries out maximum cycling exercise on the indoor bicycle ergometer, the anaerobic peak power is predictable through the contractile properties measured by TMG, and that the muscular contraction of the gastrocnemius lateralis (GL) is relatively important in order to exert maximum anaerobic power.

90/150 선형 CA를 이용한 90/102(170)/150 선형 CA 합성

최언숙(Un Sook Choi),조성진(Sung Jin Cho),김한두(Han Doo Kim),권민정(Min Jeong Kwon),김석태(Seok Tae Kim) 한국전자통신학회 2016 한국전자통신학회 논문지 Vol.11 No.9

수축수열 생성기라고 하는 비선형 수열 생성기는 최대 주기를 갖는 두 개의 LFSR로 이루어진 비선형 키스트림 생성기이다. 이러한 수축수열 생성기에 의해 생성된 수축수열은 삽입수열로 한 부류에 포함되고, 셀룰라 오토마타(이하 CA)를 이용하여 생성할 수 있다. 본 논문에서는 수축수열의 특성다항식과 동일한 특성다항식을 갖는 90/150 CA 기반의 수열생성기를 합성하는 방법을 제안한다. The nonlinear sequence generator called the shrinking generator was designed as nonlinear keystream generator composed by two maximum-length LFSRs. The shrunken sequences generated by the shrinking generator are included in the class of interleaved sequences and can be modelled as one of the output sequences of cellular automata (CA). In this paper, we propose a method for synthesizing a 90/150 CA-based sequence generator to generate a family of sequences with the same characteristic polynomial as the shrunken sequences.

고인성 내화보수모르터(FR-ECC)를 활용한 RC 구조물 보수공법의 내구성능 및 내하력에 관한 실험적 연구

김정희,임승찬,김재환,권영진 한국구조물진단유지관리공학회 2012 한국구조물진단유지관리공학회 논문집 Vol.16 No.2

본 논문에서는 FR-ECC의 수축특성과 균열도입 전후의 내동해성을 평가하였으며, FR-ECC를 활용한 다층복공구조의 지수성능과 박리박락저항성, 또한 FR-ECC로 단면복구 된 보부재의 휨성능을 평가하였다. 그 결과, FR-ECC는 소성수축에 의한 균열 및 건조수축에 의한 길이변화율이 기존의 보수모르터에 비해 크게 저감되었으며, 구속상태에서의 건조수축에 대한 균열저항성이 개선됨을 알 수 있었다. 또한, FR-ECC는 내동해성이 매우 우수하였으며, 균열도입 후에도 동결융해작용에 의한 인장성능의 저하는 확인되지 않았다. 한편, FR-ECC로 보수된 휨부재는 초기균열모멘트, 항복모멘트 및 극한모멘트 등의 휨성능이 증대되었으며, 멀티플크랙 특성에 의해 휨파괴시까지 균열폭을 안정적으로 제어할 수 있었다. This paper presents some research results on the shrinkage characteristics and frost resistance before and after cracking of FR-ECC(Fire Resistance-Engineered Cementitious Composite). Also, a waterstop performance and exfoliating resistance of multi-layer lining specimens using FR-ECC and flexural performance of beam member by repaired FR-ECC are estimated in this paper. Experimental results indicate that the plastic shrinkage crack and length change ratio of FR-ECC have been reduced as compared with that of the existing repair mortar, and that its crack resistance on the dry shrinkage is improved under the confining stress. As well as FR-ECC has been great in the frost resistance and its tensile properties under the cracked state have been not reduced by freezing and thawing reaction. In addition, beam member by repaired FR-ECC have been increased in the flexural properties such as initial crack moment, yeild moment, and its crack width has been controled in a stable by the frexural failure.

수축저감제의 종류 및 혼입률에 따른 변형경화형 시멘트복합체의 역학적 특성

한승주(Seung-Ju Han),장석준(Seok-Joon Jang),길배수(Bae-Su Khil),최무진(Mu-Jin Choi),윤현도(Hyun-Do Yun) 한국콘크리트학회 2016 콘크리트학회논문집 Vol.28 No.1

수축저감제 혼입률 변화에 따른 콘크리트의 공학적 특성에 관한 연구

한민철,金光華,정규문,정평유,윤성노,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

In this paper, tests are carried out using concrete incorporating shrinkage reducing agent(SR) in order to investigate the engineering properties of concrete. The contents of SR and W/C are varied. According to test results, as for fresh concrete, as SR content increases, slump and air content shows decline tendency, and setting time is accelerated with increase of SR content and decrease of W/C. As for compressive strength, as SR contents increases compressive strength shows to be decreased. As for the effect of SR on drying shrinkage, it shows to be reduced with increase of SR content. This is due to the reduced surface tensile strength of water and tensile strength of capillary pore in concrete.

잔골재 종류 및 섬유혼입에 따른 콘크리트의 초기수축특성 평가에 관한 실험적 연구

남정수(Nam Jeong-Soo),박윤미(Park Yun-Mi),신관수(Shin Kwan-Soo),김영덕(Kim Young-Duck),김규용(Kim Gyu-Yong),김무한(Kim Moo-Han) 대한건축학회 2007 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.27 No.1

Recently the amount of crushed sand and recycled fine aggregate have been increasing due to difficulty of supplying natural fine aggregate, but the concrete used crushed sand and recycled fine aggregate has the problem which is increasing of the crack because of plastic shrinkage and drying shrinkage. To solve this problem, the study is proceeded actively for purpose of reducing crack by fiber reinforcement which has been developed diversity about early shrinkage property of concrete, but in case of existing study, it is insufficiency to apply to construction site due to unsatisfactory of quantitative estimation about early shrinkage property. Therefore, this study presents a foundational data of fiber reinforced concrete according to sort of fine aggregate for reducing shrinkage crack by comparing and examination experimentally about early shrinkage property of fiber reinforced concrete based on kind of fine aggregates.

고강도콘크리트의 수축특성에 미치는 폭렬방지용 섬유혼입 및 표면수분증발조건의 영향

김규용(Kim, Gyu-Yong),김홍섭(Kim, Hong-Seop),미야우치 히로유키(Miyauchi Hiroyuki),김정진(Kim, Jung-Jin),구경모(Koo, Kyung-Mo),문형재(Moon, Hyung-Jae) 대한건축학회 2012 大韓建築學會論文集 : 構造系 Vol.28 No.10

In this study, compressive strengths, elasticity modules and shrinkages of high strength concrete with 80~100MPa, which are usually applied in skyscrapers in Korea, were evaluated in regard to fiber and surface drying conditions. Also a comparison with ACI 209 Model Code, generally applied in structure designs in Korea, was carried out to secure a reliability of the study results. As a result, specimens mixed with fiber produced a reduction effect of shrinkage independent from the evaporation conditions of unsealed and sealed specimen. Shrinkage of unsealed specimen was decreased and compressive strength increased, but sealed specimens as autogenous shrinkage or self desiccation of specimen, shrinkage amount was increased as compressive strength was increased.

Tensiomyogrphy를 이용한 대학 남자 축구선수의 포지션별 하지 근육 수축 특성 비교

황부근(Hwang, Boo-Geun) 한국코칭능력개발원 2022 코칭능력개발지 Vol.24 No.1

초고층 현장 적용을 위한 초고강도 콘크리트의 각종 공학적 특성에 따른 관한 실험적 연구

고주환(Ko, Joo-Hwan),유승엽(Yoo, Seung-Yeup),구자술(Koo, Ja-Sul),문형재(Moon, Hyung-Jae),김정진(Kim, Jung-Jin),박순전(Park, Soon-Jeon) 대한건축학회 2012 大韓建築學會論文集 : 構造系 Vol.28 No.1

The aim of this study is to analyze various mechanical properties of 80㎫ high strength concrete developed for the field application of super high-rise building. Expecially, for reducing hydration heat and increasing various mechanical properties, two mixtures by the binder types were mixed and tested. And, as the test item of 80㎫, fresh, hardened, shrinkage and durability properties were tested. The results of study are as follows; Fresh properties of concrete such as flowability and air content are satisfied with targetted standard. Especially slump flow 500㎜ approaching time is lower than 5 seconds because of fine viscosity. The 28day’s compressive strength is higher than design strength regardless of concretes types. Tensile and flexural strength showed 1/15 and 1/8 of compressive strength. And the value of elastic modulus is above 40㎬. Durability properties of high strength concrete is extremely excellent. Three factors make the result like that. One factor is low water/binder ratio and second factor is the increase of hydration caused by high volume binder weight. And the final factor is that C-S-H gel originated by pozzolan reaction and latent hydraulicity of FA and BFS made inner organization closely.