운용가용도제약하에서 일정 비율 수리가능한 동시조달부품의 구매량 결정

오근태(Geuntae Oh),김명수(Myungsoo Kim) 한국신뢰성학회 2002 신뢰성응용연구 Vol.2 No.2

고흡수성폴리머 및 무기질계 혼화재를 혼입한 시멘트계 합성물의 균열치유효과 특성

홍근태(Geuntae Hong),최성철(Seongcheol Choi),최영철(Youngcheol Choi) 한국콘크리트학회 2015 한국콘크리트학회 학술대회 논문집 Vol.2015 No.5

Modeling rapid self-sealing of cracks in cementitious materials using superabsorbent polymers

Hong, Geuntae,Choi, Seongcheol Elsevier 2018 Construction and Building Materials Vol.164 No.-

<P><B>Abstract</B></P> <P>The aim of the study involves quantitatively evaluating rapid self-sealing of cracks in cementitious materials incorporating superabsorbent polymers (SAPs). To this end, the study proposes a model to predict changes in the amount of water runoff through cracks over time when spherical SAPs in cementitious materials exhibit rapid swelling by absorbing the first water ingress after the occurrence of cracks. X-ray computed tomography analysis demonstrates that the swelling of SAPs in the cracks of the specimens by distilled water was less than that in a free state. The water flow test results indicate that the ratio of water runoff over time decreases sharply in SAP-added specimens immediately after the commencement of the water flow test. Additionally, the reduction ratio of the flow rate for the specimens with a crack width range of 0.24–0.36 mm corresponds to 0.343–0.519, 0.524–0.716, and 0.631–0.826 in specimens S-0.5, S-1.0, and S-1.5, respectively. A nonlinear regression analysis was performed on the results of the water flow test, and this reveals that the modification factor for the volume fraction of cracks sealed by the swelling of spherical SAPs corresponds to 0.7056, 0.6642, and 0.6574 for SAP 0.5%, SAP 1.0%, and SAP 1.5%, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A model was proposed to evaluate rapid self-sealing of cracks by SAPs. </LI> <LI> Swelling exhibited by SAPs in cracks was less than those exhibited in a free state. </LI> <LI> Self-sealing efficiency increased with increases in SAP dosage. </LI> <LI> Self-sealing efficiency decreased with increases in crack width. </LI> <LI> The predicted reduction ratio of the flow rate exceeded the measured one. </LI> </UL> </P>

고흡수율 폴리머를 포함한 시멘트계 재료의 급속 균열 셀프실링 히스테리시스 거동에 관한 실험적 분석

홍근태(Geuntae Hong),송치원(Chiwon Song),김지영(Jiyoung Kim),심예원(Yewon Shim),최성철(Seongcheol Choi) 한국콘크리트학회 2018 한국콘크리트학회 학술대회 논문집 Vol.30 No.2

시멘트계 재료 내 고흡수율 폴리머의 급속 균열 셀프실링 성능 예측 모델링

홍근태(Geuntae Hong),심예원(Yewon Shim),최성철(Seongcheol Choi) 한국콘크리트학회 2017 한국콘크리트학회 학술대회 논문집 Vol.29 No.1

데이터 기반 심층강화학습을 통한 모션 생성

박근태(Geuntae Park),이윤상(Yoonsang Lee) 한국컴퓨터그래픽스학회 2022 한국컴퓨터그래픽스학회 학술대회 Vol.2022 No.7

秦諸夏考

우근태(Geuntae WOO) 경북대학교 인문학술원 2021 동서인문 Vol.- No.15

본고는 先秦시대 출토사료에 나타난 정통성의 확보라고 하는 측면을 파악하기 위해서, 銘文과 秦簡에서 通時的으로 언급되고 있는 ‘諸夏’의 관념에 주목하여 살펴보고자 하였다. 먼저 春秋시기 청동기 명문의 秦公鐘에서는 秦武公이 “선조가 직접 천명을 받아 도읍을 정하고 강역을 받아 蠻方을 관할하였다.”고 하며, 秦公簋에서는 秦景公이 “선조가 천명을 받아 禹跡을 영유하여 蠻夏를 다스렸다.”고 하는 것을 보면, 秦나라를 중심으로 非秦 지역의 통합을 정당화하기 위한 개념으로써 ‘蠻夏’가 등장하는데, 이것은 秦나라 주변의 이민족 국가들(蠻方)과 중원의 제후국들(諸夏)을 함께 가리키는 것으로 보인다. 이러한 청동기 명문을 제작한 이유는 아마도 秦나라 穆公의 업적을 이어가면서 晉나라를 중심으로 하는 패권체제를 무너뜨리기 위해서라도 ‘蠻夏’라고 하는 주변국과의 통합을 위한 명분이 무엇보다도 필요했을 것이다. 한편 戰國시기 秦나라 법률조문의 경우에도 ‘夏’, ‘秦屬’, ‘臣邦’, ‘它邦’, ‘外臣邦’ 및 ‘諸侯’ 등의 범주를 규정한 후에 ‘夏子’, ‘眞’, ‘戎’ 등과 같은 출신을 구분하는 법률규정에 이르기까지 구체화시킨 것이나, 실제로 법률에 적용된 호적과 주언서의 재판 기록에서도 ‘秦’과 ‘荊’을 구분지어서 관리했다는 것을 알 수 있다. 이러한 백성들의 구분은 秦王政의 통일과정에서 새로이 정복한 옛 6국의 호적정보를 계승하여 정복지의 반란을 사전에 방지하고, 나아가 왕권의 유지를 위한 정당성을 확보하기 위한 정책임에는 틀림이 없었을 것이다. 春秋시기 秦나라의 武公 및 景公이 주장하는 패권의 경쟁과 戰國시기 秦王政이 주장하는 왕권의 유지는 아마도 이러한 당대의 현실적인 필요에 의해서 편집된 사료라고 생각한다. 이처럼 각 시기에 필요한 정통성을 확보하기 위한 역사의 산물을 지역적이고 시대적인 특수성으로부터 어떻게 보편적으로 바라볼 것인가에 따라서 보다 더 가까운 역사적 사실에 접근할 수 있다고 생각한다. This paper focuses on the concept of ‘Zhuxia (諸夏)’, which is commonly mentioned in Bronze Age inscriptions and Qin bamboo slips, as a way of identifying the specificity and legitimacy of historical records in the pre-Qin(秦) period. First, in the Bronze inscription of Qin Gong-zhong (秦公鐘) from the Spring and Autumn period, Qin Wu gong (秦武公) said, “My ancestor received Heaven’s mandate, set up a capital city, established a nation, and ruled the whole country.” On the Qin Gong-gui (秦公簋) he further said, “My ancestor received a Heavenly mandate, took possession of the vestiges of Yu (禹), and ruled over Manxia (蠻夏).” Here, ‘Manxia (蠻夏)’ appears as a concept to justify the integration of the Non-Qin (非秦) regions around the Qin (秦) empire, referring to the barbarian states (蠻方) and the midland empires (諸夏). The production of this bronze inscription was probably driven by the need to integrate the neighboring countries, namely the ‘Manxia (蠻夏)’, to break down the hegemonic system centered around the Jin (晉) while continuing the work of Qin Mu gong (秦穆公). On the other hand, the legal provisions of the Qin bamboo slips, which date from the Warring States Period, define categories such as ‘Xia(夏)’, ‘Qin Shu(秦屬)’, ‘Chen Bang(臣邦)’, ‘Ta Bang(它邦)’, ‘Wai Chen Bang(外臣邦)’ and ‘Zhu Hou(諸侯)’. It can be seen that even in the judicial record of the family register and the ju-eon, which were actually conform to the regulations that distinguished origin such as ‘Xia Zi(夏子)’, ‘Zhen(眞)’, and ‘Rong(戎)’, ‘Qin(秦)’ and ‘Jing(荊)’ were dealt with separately. This distinction among the people was indubitably a policy to prevent rebellions by inheriting information from the family registers of the six states newly conquered during the reunification process by Qin Wang Zheng (秦王政), and to secure legitimacy in the maintenance of kingship. The present author argues that the claim for supremacy vied by Wu Gong (武公) and Jing Gong (景公) of the Qin (秦) dynasty during the Spring and Autumn Period and the claim for kingship by Qin Wang Zheng (秦王政) during the Warring States Period were probably edited by the practical needs of the time. Thus, approaches to historical facts may be much closer based on how to view universally the regional and period-specific products of history which aim at securing legitimacy needed for a given period.

습윤/건조 반복 작용이 고흡수율 폴리머를 함유한 시멘트계 재료의 자기치유에 미치는 영향

홍근태(Geuntae Hong),최성철(Seongcheol Choi) 한국건설순환자원학회 2020 한국건설순환자원학회 논문집 Vol.8 No.1

이 연구에서는 고흡수율 폴리머(SAPs)를 포함하는 시멘트계 재료의 자기치유에 대한 습윤/건조 반복 작용의 영향을 실험적으로 평가하였다. 매 주기마다 SAP 함량을 변수로 하는 시멘트 페이스트 시편을 균열 이후 1시간 동안 습윤 조건에 노출시키고(흡수율시험 및 투수시험 진행), 47시간 동안 건조 조건에 노출시켰다. 흡수율시험 결과 SAP 미혼입 시편, SAP 0.5%, SAP 1.0%, SAP 1.5% 혼입 시편의 균열을 통한 흡수율이 각각 1주기 대비 8주기 이후 22.9%, 36.8%, 42.8%, 46.3% 감소한 것으로 나타났다. 또한, 투수시험 결과 모든 시편의 균열을 통한 물 유출량은 습윤/건조 주기에 따라 점차 감소하였으며, 특히 SAP 함량이 증가할수록 유량 감소율은 증가하였다. 또한, X-ray CT 분석을 통해 균열 내 SAPs의 유입수에 의한 팽윤 거동이 확인되었다. 실험 결과는 SAPs가 유입수를 흡수하여 팽윤함에 따라 유효 균열폭이 감소될 수 있고, SAPs는 흡수한 물을 건조 조건에서 주변 균열부에 공급함에 따라 치유 생성물의 형성을 촉진시킬 수 있음을 나타낸다. 이 연구의 결과는 SAPs의 혼입이 균열의 수밀성을 증가시킴에 따라 시멘트계 재료의 자기치유 성능을 향상시킬 수 있음을 나타낸다. In this study, the effect of cyclic wetting-drying on the self-healing of cementitious materials containing superabsorbent polymers (SAPs) were experimentally evaluated. In each cycle, cracked cement paste specimens containing various SAP dosages were exposed to wet conditions for 1 h, during which the capillary water absorption tests and water flow tests were conducted, and then exposed to dry conditions for 47 h. The capillary water absorption test results showed that the sorptivity values of the specimen without SAPs, SAP 0.5%, SAP 1.0%, and SAP 1.5% specimens were decreased by approximately 22.9%, 36.8%, 42.8%, and 46.3%, respectively, after 8 cycles. In addition, the water flow test results showed that the amount of water runoff through the cracks of all cracked specimens gradually decreased over wet/dry cycles, especially the reduction ratio of the amount of water runoff increased with increasing SAP dosage. Furthermore, the swelling behavior of SAPs in cracks by ingress water was confirmed via X -ray computed tomography (CT) analysis. These results indicate that the effective crack width can be reduced as SAPs absorb water and swell, while the water absorbed in SAPs can be released to crack surfaces under dry conditions, further promoting healing product formation. This study demonstrates that the in corporation of SAPs c an increase the water tightness of cracks, thereby improving the self-healing efficiency of cementitious materials.

부품재활용이 허용될 때 목표운동가용도 조건을 갖는 소모성 동시조달부품의 구매량 결정

오근태(Geuntae Oh),김명수(Myungsoo Kim) 한국신뢰성학회 2004 신뢰성응용연구 Vol.4 No.2

Rapid self-sealing of cracks in cementitious materials incorporating superabsorbent polymers

Hong, Geuntae,Choi, Seongcheol Elsevier 2017 Construction & building materials Vol.143 No.-

<P><B>Abstract</B></P> <P>The effect of superabsorbent polymers (SAPs) on rapid self-sealing of cracks in cementitious materials was investigated experimentally. Rapid swelling of SAPs effectively sealed cracks in materials within five minutes, resulting in the reduction ratio of water runoff per unit time in ranges of 34–52% and 52–72% for SAP dosages of 0.5% and 1.0%, respectively. X-ray computed tomography (CT) analysis showed that the swelling ratio of SAPs in the specimens was less than that in the filtered cement pore and synthetic solutions. Analyses of images obtained using X-ray CT, cryofracture scanning electron microscopy, and optical microscopy indicated that when a crack occurred, most SAPs, which were split because of the crack while remaining bonded to the surrounding cement matrix, swelled only as much as the volume of voids formed by swelling of SAPs, not including the crack. However, a part of the SAPs that remained intact swelled across voids, including the crack.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Rapid self-sealing of cracks by SAPs in cementitious materials was investigated. </LI> <LI> Rapid swelling of SAPs effectively sealed the cracks within five minutes. </LI> <LI> Most SAPs were split in the cracks while remaining bonded to the surrounding matrix. </LI> <LI> Intact SAPs swelled across voids formed by swelling of SAPs including the cracks. </LI> <LI> Split SAPs swelled only as much as the volume of voids by SAPs not including crack. </LI> </UL> </P>