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화재 시 중공슬래브의 온도분포 예측을 위한 1방향 열전달 모델
정주홍,최현기 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 논문집 Vol.23 No.5
In general, a reinforced concrete slabs are known to have a high fire resistance performance due to thermal properties of concrete materials. However, according to previous research, the thermal behavior of voided slabs is reported to be different from that of conventional RC solid slabs, and the differences seem to be caused by the air layer formed inside the voided slab. Therefore, it is difficult to estimate the temperature distribution of the voided slab under fire by using the existing methods that do not take into account the air layer inside the voided slab. In this study, a numerical analysis model was proposed to estimate the temperature distribution of voided slabs under fire, and evaluated. Heat transfer of slabs under fire is generally caused by conduction, convection and radiation, and time-dependent temperature changes of slab can be determined considering these phenomena. This study proposed a numerical method to estimate the temperature distribution of voided slabs under fire based on a finite difference method in which a cross-section of the slab is divided into a number of layers. This method is also developed to allow consideration of heat transfer through convection and radiation in air layer inside of slabs. In addition, the proposed model was also validated by comparison with the experimental results, and the results showed that the proposed model appropriately predicts the temperature distribution of voided slabs under fire. 일반적으로 철근콘크리트 슬래브는 콘크리트 재료의 열적특성에 의해 높은 수준의 화재 저항 성능을 보유하고 있는 것으로 알려져 있다. 그러나 기존연구에 따르면 중공슬래브의 열적거동은 일반 슬래브와 상이한 것으로 보고되고 있으며, 이는 중공슬래브 내부에 형성된 공기층 때문인 것으로 판단된다. 따라서 슬래브 내부의 공기층을 고려하지 못하는 기존의 방법을 통해서 화재 시 중공슬래브의 내부온도를 추정하는 것은 어려울 것으로 판단된다. 본 연구에서는 화재 시 중공슬래브의 내부온도 분포를 산정하기 위한 수치해석 모델을 제안하고 이를 평가하였다. 기본적으로 화재 시 슬래브의 열전달은 전도, 대류, 복사 등을 통해 발생하며, 이를 기반으로 시간에 따른 슬래브 내부 단면 온도분포를 산정하게 된다. 이에 본 연구에서는 슬래브를 유한개의 층으로 분할하여 각 층의 온도를 산정하는 유한차분법을 도입한 중공슬래브의 수치해석적 모델을 개발하였으며, 슬래브 내부 공기층에서의 대류 및 복사에 의한 열전달 경로를 고려할 수 있도록 개발하였다. 또한 제안된 모델을 실험결과와의 비교를 통해 검증하였으며, 그 결과 제안된 모델은 화재 시 중공슬래브의 온도변화를 적절히 예측하고 있는 것으로 나타났다.
정주홍,지삼룡,최은정,유승정,윤준식,이홍섭,이상헌,박성재,박하영 대한소화기학회 2022 대한소화기학회지 Vol.80 No.4
Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTCL-NT) is the most common subtype of Epstein-Barr virus-associated NK/T-cell lymphomas. ENKTCL-NT occurs infrequently in the gastrointestinal tract. In particular, reports of ENKTCL-on NT arising from the stomach are extremely rare. Several clusters of differentiation (CDs) have been useful in recognizing NK-cells, T-cells, and tumor cells of NK/T-cell lymphomas. Among them, the CD56 antigen is considered the most sensitive marker for ENKTCL-NT and is expressed in almost all cases of ENKTCL-NT. Thus, the development of CD56-negative ENKTCL-NT is highly atypical. This paper reports a case of a young Asian female who presented with gastric ulcer bleeding. The patient was histologically diagnosed with ENKTCL-NT. No tumor cells for CD56 were observed, whereas no monoclonality of the T-cell receptor gamma gene rearrangement was detected in the tumor cells. The patient was scheduled for systemic chemotherapy six times and achieved complete remission. Peripheral blood-hematopoietic stem cell transplantation was performed later.
이방향 중공슬래브의 최적 중공형성체 형상 도출을 위한 해석적 연구
정주홍,최현기,이승창,최창식,Chung, Joo-Hong,Choi, Hyun-Ki,Lee, Seung-Chang,Choi, Chang-Sik 대한건축학회 2011 대한건축학회논문집 Vol.27 No.7
This paper presents optimal hollow sphere shapes in a biaxial hollow slab. To derive optimal shapes, numerical simulations using nonlinear Finite Element Methods were executed by the nonlinear finite element program 'LUSAS'. Recently, various types of slab systems which can reduce self-weight of slabs have been studied as the height and width of building structures rapidly increase. A biaxial hollow slab system is widely known as one of the effective system which can reduce weight of slab. A biaxial hollow slab has hollow spheres within slab in order to reduce weight of slab. Because of reducing self-weight of slab by hollow spheres, size of vertical elements like walls and columns can be smaller and slabs span can be longer. A capacity of biaxial hollow slabs is influenced by the shape and volume of hollow spheres. Therefore, in this study, several biaxial hollow slabs which have different shapes of hollow spheres were analyzed by using the finite element method program in order to derive optimal hollow sphere shapes.
정주홍,윤광식,최수명,윤석군,고영배,김영택,Jeong, Ju-Hong,Yoon, Kwang-Sik,Choi, Soo-Myung,Yoon,, Suk-Gun,Go, Young-Bae,Kim, Young-Taek 한국관개배수위원회 2010 한국관개배수논문집 Vol.17 No.2
Tidal land reclamation provided water resources and land for agriculture and contributed stable crop production. However, climate change by global warming disrupts the hydrologic circulatory system of the earth resulting in sea level rise and more frequent flood for reclaimed arable land. Recently, Suyu reclaimed paddy field in Jindo-gun experienced prolonged inundation after heavy rainfall and there is a growing risk of flood damage. Onsite survey and flood analysis using GATE_Pro model of Korea Rural Corporation were conducted to investigate causes of flooding. To perform the analysis, input data such as inflow hydrograph, the lowest elevation of paddy field, neap tide level, management level of Gunnae estuary lake at the time of the flood were collected. Flood analysis confirmed that current drainage facilities are not enough to prevent 20year return period flood. The result of analysis showed flooding more than 24hours. Therefore, flood mitigation alternatives such as sluice gate expansion, installation drainage pumping station, refill paddy land, and catch canal were studied. Replacing drainage culvert of Suyu dike to sluice gate and installing drainage pumping station at the Gunne lake were identified as an effective flood control measures. Furthermore, TM/TC (SCADA) system and expert for gate management are required for the better management of drainage for estuary dam and flood mitigation.