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.

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.

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.

흰쥐에서 말초신경 손상후 뒤뿌리신경절세포의 신경영양인자와 그 수용체의 발현 양상

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

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.

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.

매크로/마이크로 레벨 볼트 결합 구조물에서의 실험적/해석적 방법을 통한 시스템 특성 비교

김봉석,이성민,이문구,이수훈,Jun Ni,송준엽,이창우,하태호 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-

As the micro technology and miniaturization of a structure and component in the last couple of decades have been concretely realized, the understanding of structural and dynamic characteristics and prediction of dynamic behavior are indispensable to the miniaturized structures and micro machines. This paper shows the effect of dynamic characteristics in bolt-jointed structures by comparing natural frequencies and mode shapes between macro and micro-scale beams through experimental modal analysis and finite element analysis with a1 8 test models by materials, by size, and by joining condition; that is, SS41 and A16061-T651, micro and macro, and monolithic beam and bolt-jointed beam.

BoBos 특성에 따라 분류한 집단 간 인구통계적 · 관광행태적 차이에 관한 연구

김병숙,이봉구 동의대학교 경제경영전략연구소 2005 經濟經營硏究 Vol.3 No.1

With the advent of post-industrial society, a new social class called as BoBos has become a new icon. Though they have unique characteristics, few studies have investigated those aspects and their implications for tourism product development. This study implemented in order to fill the gap. More specifically, the purposes of this study were to examine demographic and tourism-related behavioral characteristics among social classes classified by BoBos traits and to suggest some practical implications for tourism product development geared to the niche market. A self-administered questionnaires was developed and distributed to Busan Metropolitan city residents conveniently during the period of May 8-11,2003. A total of 400 questionnaires were collected, but after discarding 5 incomplete ones, 395 valid questionnaires were used for data analysis. Results showed that groups classified by BoBos traits were mostly different from each other in terms of their demographic and tourism-related behaviors. Discussion on the results and their implication for tourism product development were briefly described.