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SPSS를 활용한 플라이애시 혼입 콘크리트의 효율적 배합 제안
조홍범(Cho Hong-Bum),지남용(Jee Nam-Yong) 대한건축학회 2011 大韓建築學會論文集 : 構造系 Vol.27 No.1
For efficient mix design, this paper offers following information: the fly ash (FA) replacement ratio in which strength development is the maximum, the range of FA replacement ratio in which the strength of FA concrete is higher than that of ordinary Portland cement (OPC) concrete, and the binder content per unit strength. For these matters, various statistical analyses were performed based on a wide range of mix proportions and a number of strength test results of ready mixed concretes used in eight construction sites. The strength ratio, the ratio of FA concrete to OPC concrete in compressive strength, was expressed as the function of binder-water ratio and FA replacement ratio by multiple linear regression analysis. This equation suggests the range of FA replacement ratios in which strength ratio of 1 or higher can be obtained when binder content of FA concrete is the same as that of OPC concrete. The strength ratio increases with increasing water-binder ratio. As water-binder ratios decrease, the range of FA replacement ratios also decreases. It is desirable that FA concrete should have FA replacement ratio of about 15% to guarantee required average compressive strength using minimum binder contents. In FA replacement ratio of about 15%, the binder content per unit strength is 10.1∼10.6㎏/㎥/㎫ with respect to water-binder ratio. Because the binder content per unit strength is calculated with respect to water-binder ratio and FA replacement, its concept can be used as a means of determination of the binder content in mix design of FA concrete.
조홍범(Cho Hongbum),윤상천(Yoon Sangchun),지남용(Jee NamYong) 대한건축학회 2003 大韓建築學會論文集 : 構造系 Vol.19 No.4
There are only a few tests to ensure concrete quality before placing in domestic construction site; One is the slump test for workability, the others are the air content test and the chloride content test for durability. The concrete compressive strength which is the one of important factors to influence on concrete quality was tested after 28 days when placed. Methods for early estimation of concrete strength have been introduced for concrete quality control, but such methods are expensive, and required experienced skill and time. Therefore, these have difficulties in situ application for concrete quality control. The subject of this study is the result of 1442 compressive strength tests on 59 different kinds of mix design with specified compressive strength of 180∼270kgf/㎠, water-cement ratio of 0.39∼0.62, Gmax 25㎜, and slump of 12∼15㎝. This study aimed at reviewing application of prediction equation of compressive strength as a means of strength control of ready-mixed concrete, making an regression equation which enables to estimate compressive strength at 28 days by multiple linear regression analysis on the basis of mix proportion of ready-mixed concrete and compressive strength testresults of construction site.
조홍범 ( Hong Bum Cho ),정순오 ( Soon Oh Jeung ),최용근 ( Yong Gun Choi ) 한국환경생물학회 2004 환경생물 : 환경생물학회지 Vol.22 No.1
동굴 내 정점별 세균 군집 구조를 분석하기 위하여 PCR amplified 16S rDNA denaturing gradient gel electrophoresis (DGGE)를 적용하였다. DGGE는 동일한 분자량을 갖는 dsDNA band라고 할지라도, 각각의 염기서열 차이에 따라 전기영동 상에서 고유한 band 양상을 나타낼 수 있다. eubacteria의 16S rDNA V3 region을 증폭하기 위해 GC341F와 PRUN518r을 primer로 사용하여 지하수내에 미생물 군집의 다양성과 유사성을 분석하였다. DGGE band양상을 통해 동굴내의 세균 군집 구조는 외부 환경에 비해 상대적으로 종다양성이 낮으며 동굴내에서 특이적으로 서식하는 종이 있음을 확인하였다. 또한 유기 영양물질의 공급이 제한되어 있는 동굴에서 구아노가 주요 유기 영양물질의 공급원으로서 큰 영향을 미치고 있는 것으로 파악되었다. DGGE상의 일부 band의 염기서열분석 결과 Pseudomonas sp. NZ060과 Pseudomonas pseudoalcaligenes, uncultured Variouorax sp,. soil bacterium NS7로 동정되었다. The bacterial community of water stream, soil and guano in Gossi cave was examined by using PCR amplified the 16S rDNA-denaturing gradient gel electrophoresis (DGGE). In this study, the genetic diversity and the similarity of bacterial community between open area and non-open area for cave tour were investigated, and the seasonable variation pattern was compared each other. DGGE is attractive technique, as it separate same length dsDNA according to sequence variation typical 16S rDNA genes. The diversity and similarity of bacterial community in cave was analyzed by GC341f and PRUN518r primer sets for amplification of V3 region of eubacteria 16S rDNA. The specific DGGE band profile of the cave water gives the possibility that the specific bacterial cell can be adapting to the specific cave environment and living in the cave. The DGGE band profiles of all samples with guano were compared and analyzed by image analyzer, in which mutual band profile was compared to be and the band intensity of guano was the highest. From these result, it is thought that the guano was main nutrient source and influenced on the community structure of the cave environment where is nutritionally limited. Pseudomonas sp. NZ060, Pseudomonas pseudoalcaligenes, uncultured Variovorax sp. and soli bacterium NS7 were identified to be on some sample from analysing DNA sequence of some DGGE band.
원자로 입출구 노즐 이종금속 용접부 Weld Inlay 레이저 클래딩 공정 개발
조홍석,정광운,모민환,조기현,최동철,이장욱,조상범,Cho, Hong Seok,Jung, Kwang Woon,Mo, Min Hwan,Cho, Ki Hyun,Choi, Dong Chul,Lee, Jang Wook,Cho, Sang Beum 한국압력기기공학회 2015 한국압력기기공학회 논문집 Vol.11 No.1
This study was investigated to develop process technology of laser cladding with austenite stainless steel for Weld Inlay repair of dissimilar metal weld in reactor vessel in/outlet nozzles. Weld Inlay experiments were performed by laser cladding repair system consisting of common manipulator, laser apparatus and welding process scheduler, etc. Single pass welding experiments were conducted in order to obtain the optimum welding process parameters for filler wires of ER309L and Alloy 52M before multi-layer laser cladding. Based on the above obtained results, multi-layer laser cladding experiments were carried out, and welding qualities for weld specimens were estimated by PT, OM, SEM and EDS analysis. Consequently, it was revealed that multi-layer laser cladding on austenite stainless steel using filler wires of ER309L and Alloy 52M could be possible to meet ASME Code standard without any weld defect.