콘크리트의 급속염화물침투시험에 의한 염화물이온 확산계수 평가에 관한 실험적 연구

김갑수,조봉석,장종호,김재환,김용로,김무한 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

Chloride ions are considered to be the major cause of steel corrosion in concrete structures exposed to seashore environments and also permeation of chloride is controlled by chloride diffusion. Therefore, the study on chloride diffusion of concrete have been done so far by many researchers. In this study, several factors such as capacity of voltage, time of an electric current, concentration of NaCl solution, water-cement ratio, and temperature of the solution were examined to grasp what influence they were on the chloride ion diffusion properties using the Rapid Chloride Penetration Test(RCPT) by electrophoresis. Also standing on the basis of the such result application possibility of Rapid Chloride Penetration Test(RCPT) used in this study will be evaluated and the basic data on the durability design for the chloride attack will be suggested.

PVA-ECC를 활용한 Half PC 복합체의 역학적 특성에 관한 실험적 연구

김재환,김영덕,김갑수,조봉석,장종호,김무한 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

ECC represents one particular class of HPFRCC, which are defined by an ultimate strength higher than their first cracking strength and the formation of multiple cracking during the inelastic deformation process. This study is to provide the fundamental data for the development of hybrid construction method such as the half PC(Precast concrete) reinforced by PVA-ECC, the mechanical properties of half PC according to the alteration of properties of PVA-ECC in terms of the type of fiber, Vr, S/M, placing height of PVA-ECC, are experimentally investigated. As the results. it is found that the half PCs of PVA-ECC have very higher mechanical performance in terms of yield load, strain capacity beyond yield point and maximum flexural load than that of mortar. Also, flexural crack in the half PCs of PVA-ECC are not localized at first crack and are growed to many micro crack, especially multiple cracking in specimen of P(12)-30-0.1ㆍ3 occurred.

뿜칠시공에 의한 단면복구재의 시공성 및 공학적 특성에 관한 실험적 연구

조봉석,김영선,장재봉,김용로,김경덕,김무한 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1

These days, serious concerns of reinforced concrete have been raised recently over steel-bar corrosion, cracking, the deterioration of durability and structural stress resistance and so on, all due to the effects of exterior factors. Such being the case, in domestic, various repair materials and method systems to keep up with these reinforced concrete deteriorated due to salt damage, carbonation, chemical decay et. developed and applied. However, on-site quality control of various repair materials and method systems isn't achieved desirably because it is depend completely on a men of experience' opinions above all else regardless of various on - site environments. In this background, mock up test with due regard to real on-site environments was performed to secure fundamental data for establishment of desirable on-site quality control. Mock up test using repair mortar analyzed from angles of construction methods, mechanical spraying pressures, W 1M. Construction methods were designed manpower method and spraying method, spraying pressures were designed 32, 42, 52 psi, W/M were designed 14.4, 15.4, 16.4 %. And compressive strength, Chloride ion diffusion coefficient, bond strength, SEM of mock up test specimens were evaluated. In conclusion, we confirmed excellency of mechanical spraying pressures, fined extremely excellency of condition of spraying pressure 42 ps, W/M 14.4% within this study. therefore the results of this study will be useful to provide fundamental data for establishment of desirable on-site quality control.

복합열화환경하에서의 중성화 및 염화물이온 확산특성이 철근부식에 미치는 영향에 관한 실험적 연구

조봉석,장재봉,김재환,김용로,권영진,김무한 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

It is recognized that reinforcement corrosion is the main distress behind the present concern regarding concrete durability. In this study, to confirm corrosion of reinforced concrete due to permeability of carbonation and chloride ion affected by thickness of cover, kinds of surface coating, measured electric potential, ratio of corrosion area, weight reduction, corrosion velocity of steel bar under environment of complex deterioration. The results showed that an increase in age also decreases Carbonation velocity coefficients and increases Chloride ion diffusion coefficients. As well, an increase in age also increases corrosion of reinforcement due to permeability of carbonation and chloride ion. Corrosion of reinforcement by thickness of cover is superior to 10mm thick than 20mm thick. It showed that an increase in thickness of cover prevent steel bar from deteriorating due to permeability of carbonation and chloride ion. The results of this study showed that corrosion velocity was affected by thickness of cover, kinds of surface coating. data on the development of corrosion velocity made with none, organic B, organic A, inorganic B. and inorganic A is shown.

Influence of the post-necking prediction of hardening law on the theoretical forming limit curve of aluminium sheets

Pham, Quoc-Tuan,Lee, Bong-Hyun,Park, Kee-Cheol,Kim, Young-Suk Elsevier 2018 International journal of mechanical sciences Vol.140 No.-

<P><B>Abstract</B></P> <P>This study clarified the influence of the post-necking prediction of the hardening law on the theoretical forming limit curve (FLC) of aluminium sheets subjected to punch-stretching tests. A procedure was developed to identify the parameters of a recently developed hardening model (Kim–Tuan hardening model) based on the curve fitting method. Subsequently, this model was used to capture the post-necking behaviours of two aluminium alloy sheets (AL5052-O and AL6016-T4), which were compared with those of various other hardening models, including the Swift model, Voce model, Hockett–Sherby model, Ghosh model, and a linear combination of the Swift and Voce models. These hardening models, with their extrapolations for post-necking prediction, were employed to analytically calculate the FLCs of the tested materials based on the modified maximum force criterion (MMFC). Furthermore, a simple and effective method was found to estimate the level of limited strain in the plane strain mode, namely FLC<SUB>0</SUB>. The proposed method was used to clarify the influence of the hardening law and yield function on the level of the computed FLC. The results indicated that the flow curves predicted by the Kim–Tuan hardening model effectively matched the experimental data obtained from uniaxial tensile tests, while their extrapolations provided intermediate predictions of the post-necking behaviour between the flow curves of the Swift and Voce models. In addition, the proposed hardening model improved the accuracy of the computed FLC for the studied materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> New formulation for strain hardening function is presented. </LI> <LI> A procedure for identifying parameters of proposed hardening model is developed based on curve fitting method. In this procedure, stress and strain data obtained from standard uniaxial tensile test were utilized. </LI> <LI> New method is presented for estimating the level of limited strain in the plane strain mode, FLC<SUB>0</SUB>. Based on this method, influence of post-necking prediction of hardening law on forming limit curve of aluminium sheet is discussed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

국내 발전소별 바텀애시를 잔골재 대체재로 사용한 모르터의 특성에 대한 실험적 연구

송민섭,장재봉,조봉석,김재환,김용로,김무한 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

With the advance in industrial development and modern living comfort, the demand for electricity throughout the country is ever increasing. Also the annual consumption of coal by coal-fired power plants is increasing. The amount of ash produced in 2000 is estimated to be about 4.5 million tons. The disposal of this huge amount of ash introduces serious environmental problems. Fly ash among the ash produced is used in building industries as a substitute to cement in concrete and the concrete thus produced is said to be lighter and stronger. But bottom ash among the ash produced is not used because of its poor properties. But encouraging the use of bottom ash as a construction material is a sensible method of utilization as it avoids the problems and costs associated with disposal and provides an alternative aggregate source. This study is aimed at using bottom ash as an alternative fine aggregate source to provide a solution to disposal and insufficient fine aggregate for the production of concrete. So properties of bottom ash produced in power plants were estimated due to the difference of bottom ash produced in each plant. And mortar strength was estimated as basic data to use bottom ash in building industries.

흰쥐에서 말초신경 손상후 뒤뿌리신경절세포의 신경영양인자와 그 수용체의 발현 양상

백선용,양만석,문총석,김봉선,김재봉,김진정 대한해부학회 1999 Anatomy & Cell Biology Vol.32 No.2

A rare case of extensive papillary muscle calcification in senile cardiac calcification syndrome

김은진;송봉근;강민호;손형래;홍수민;박동원;허승혜;김계연;최석구 인제대학교 2011 仁濟醫學 Vol.32 No.-

광범위 유두근 석회화는 흔하지 앉으며, 원인과 임상적 중요성에 관한 문헌만 드물게 찾아볼 수 있다. 반면에 작은 석회 침착은 노인에서 흔하며 심장 첨부에 주로 나타난다. 유두근 석회화는 관상동맥질환, 확장성 심근병증, 승모관 질환, 고칼슘혈증, 그리고 말기신부전에서 인산칼슘의 중가와 연관성이 있다. 저자는 심장초옴파와 MDCT를 통해 진단된 전외측 유두근의 광범위 석회화의 드문 사례가 있어 보고한다.

비판적 사고능력 신장을 위한 주제 상세화 질문 구성의 원리와 방법

김재봉,위숙량,설향순 한국초등국어교육학회 2007 한국초등국어교육 Vol.33 No.-

Critical Thinking Ability is potential power that we make an inner representation about given problem, and in their point of view find a problem and solve it. This article, named by 'The Principles and Methods of The Construction of Theme Detailing Question for Improving Critical Thinking Ability' is a tentative plan. we can improve critical thinking ability through korean language education. The principles of the construction of theme detailing question are relation, certification, generalization, reconstruction, extension. These are the network of relation. They are based on the principle of relation. Theme detailing question is an asking statement, and an asking statement subdivide a theme of text, especially with an argument as the central figure. In this article, the types of theme detailing question are fact finding question and cause and effect question. With given material as the central figure, at first we grasp the theme of a text. And with theme as the central figure, we make fact finding question. With fact identification and question elicit as the central figure, we make a cause and effect question. And with background variable as the central figure, we make a new fact finding question. Fact finding question plus fact identification and question elicit make a causal and effect question. causal and effect question plus background variable make fact finding question. When we make a fact finding question with new view point, background variable is very important. This activities of the construction of theme detailing question continues through question chain. 비판적 사고능력은 ‘주어진 문제에 대해서 내적 표상을 만들고, 이를 바탕으로 자기의 시각에서 무엇이 문제인지를 발견하고 해결하는 잠재적인 힘’이다. 이 글에서는 국어과교육에서 이러한 힘을 신장시킬 수 있는 하나의 시안으로 ‘주제 상세화 질문 구성의 원리와 방법’을 논의했다. 이 글에서 살핀 주제 상세화 질문 구성의 원리에는 ‘관계성의 원리, 구체화의 원리, 일반화의 원리, 재구성의 원리, 사고확장의 원리’가 있으며, 이들은 관계성의 원리를 바탕으로 하여 하나의 관계의 망을 이룬다. 주제 상세화 질문은 ‘글의 주제의 특정한 논항을 하위 개념으로 세분화하여 묻는 진술’이다. 이 글에서는 주제 상세화 질문을 ‘실태 파악형 질문’과 ‘인과 관계형 질문’으로 유형화해보았다. 주어진 자료를 바탕으로 먼저 글의 주제를 파악하고, 주제를 바탕으로 ‘실태 파악형 질문’을 만든다. 이어서 사실 확인과 질문 유도를 바탕으로 ‘인과관계형 질문’을 만들고, 이것과 ‘배경 변인’을 관련지어 새로운 실태 파악형 질문을 만든다. 실태 파악형 질문에 ‘사실 확인과 질문 유도’를 첨가하여 인과 관계형 질문을 만들고, 여기에 ‘배경 변인’을 고려하여 새로운 실태 파악형 질문을 하위에 만든다. 이 과정에서 새로운 관점이 반영된 실태 파악형 질문을 만들 때 ‘배경 변인’은 매우 중요한 역할을 한다. 이러한 주제 상세화 질문 구성 활동은 질문 연쇄를 이루면서 하위 단계로 계속된다.

공간능력, 시지각 회상 능력, 학습양식에 따른 지구와 달의 운동 개념

김봉섭,정진우,양일호,정지숙 한국교원대학교 과학교육연구소 1998 청람과학교육연구논총 Vol.8 No.1

The purpose of this study was to investigate the relationship among spatial ability, learning styles, visual-perception-recall ability, and the conceptual construction of the earth and moon's motion. Four paper-and-pencil tests were used to measure students' cognitive variables. Spatial ability was measured by Spatial Visualization Test, visual-perception-recall ability was measured by Rey's Figure which also have used to test visual-perception-recall ability of right-temporal lobes, and VVT were used to investigate students' learning styles. Further, the test of concept construction was consisted of 15 items about the earth and moon's motion developed by researcher. One hundred and twenty-seven 6th-, one hundred and sixteen 7th-, eighty-seven 9th-grade, ninety-three college students were participated in the investigation of the effects of age and learning style on conceptual construction. In the analysis of students' performances, spatial ability, visual-perception-recall ability, and conceptual achievement showed an increasing pattern with grading. In addition, visual learner's conceptual achievement showed a significantly higher score on conceptual test than verbal learner's(p<0.05). The results of the present study supported the hypothesis that learning styles would differently influence to learning atmospheric concepts by students' learning styles. This study also indicated to be considered the students' spatial ability in learning atmospheric concepts.