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.

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.

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.

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>

흰쥐에서 말초신경 손상후 뒤뿌리신경절세포의 신경영양인자와 그 수용체의 발현 양상

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

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.

急性特發性心囊炎의 1例

金星潤,孫宜錫,李禎均,許鳳烈,咸駿洙,金鮮宙 대한의학협회 1977 대한의학협회지 Vol.20 No.9

내구성을 고려한 표면피복재의 성능평가에 관한 실험적 연구

김영덕,조봉석,윤종기,김용로,장종호,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. The basic method to prevent reinforcement corrosion is coating the reinforcement concrete with surface coating materials but evaluating their performance is necessary to the work satisfactory because they have different performance for each other. In this study. to evaluate performance of surface coating materials, we compare their properties in terms of sticking strength and permeability of carbonation, chloride ion and water with actual reinforcement corrosion under environment of complex deterioration. The results showed that an increase in age also decreases Carbonation velocity coefficients, increases Chloride ion diffusion coefficients and increases water absorption coefficients. As well, an increase in age also increases corrosion of reinforcement due to permeability of carbonation and chloride ion. And sticking strength of inorganic coating material is higher than organic coating material.

仲裁判定에 의한 執行判決의 節次와 그 問題點

김봉석 韓國仲裁學會 2003 중재연구 Vol.13 No.1

Arbitration means the procedure that a party inquires a third party arbitrator for a resolution on the dispute on certain matters of interest to follow through with the commitment of the arbitration, and a series of procedures performed by the arbitrator of the Korean Commercial Arbitration Board. Arbitration is implemented in accordance with the procedure determined by the Arbitration Act and Arbitration Regulations. In the event the parties reach to the reconciliation during the process of arbitration, the reconciliation is recorded in the form of arbitration award(decision), and in the event a reconciliation is not made, the arbitrator shall make the decision on the particular case. The arbitration award(decision) for reconciliation during the arbitration procedure (Article 31 of Arbitration Act, hereinafter referred to as the "Act") or the mediation under the Arbitration Regulation of the Korean Commercial Arbitration Board (Article 18 of the Arbitration Regulations) shall have the same effectiveness with the decision rendered by a court that, in the event a party does not perform the obligation, the enforcement document is rendered under the Rules on Enforcement Document on Mediation Statement of various dispute resolution committees of the Supreme Court to carry out the compulsory enforcement. However, in the event that the party to take on the obligation to perform under the arbitration award (decision) rendered by the arbitrator (Article 32 of the Act) does not perform without due cause, a separate enforcement decision in accordance with the procedure determined under the Civil Enforcement Act shall be obtained since the arbitration award(decision) cannot be the basis of enforcement under the Civil Enforcement Act. And, in order to enforce the judgment compulsorily in accordance with the regulations under the Civil Enforcement Act under the foreign arbitration judgment (Article 39 of the Act), it shall fulfill the requirement determined under the Civil Litigation Act (article 217 of Civil Litigation Act) and shall obtain a separate enforcement decision in accordance with the procedure determined under the Civil Enforcement Act (Article 26 and Article 27 of Civil Enforcement Act) since the arbitration judgment of foreign country shall not be based on enforcement under the Civil Enforcement Act. It may be the issue of legislation not to recognize the arbitration award(decision) as a source of enforcement right, and provide the compulsive enforcement by recognizing it for enforcement right after obtaining the enforcement document with the decision of a court, however, not recognizing the arbitration award(decision) as the source of enforcement right is against Clause 3 of Article 31 of the Act, provisions of Article 35, Article 38 and Article 39 that recognized the validity of arbitration as equal to the final judgment of a court, and the definition that the enforcement decision of a court shall require the in compulsory enforcement under Clause 1 of Article 37 of the Act which clearly is a conflict of principle as well. Anyhow, in order to enforce the arbitration award(decision) mandatorily, the party shall bring the litigation of enforcement decision claim to the court, and the court shall deliberate with the same procedure with general civil cases under the Civil Litigation Act. During the deliberation, the party obligated under the arbitration award(decision) intended to not to undertake the obligation and delay it raises the claim and suspend the enforcement of cancelling the arbitration award(decision) on the applicable arbitration decision within 3 months from the date of receiving the authentic copy of the arbitration award(decision) or the date of receiving the authentic copy of correction, interpretation or additional decision under the Regulation of Article 34 of the Act (Clause 3 of Article 36 of the Act). This legislation to delay the sentencing of the enforcement and then to sentence the enforcement decision brings the difficulties to a party to litigation costs and time for compulsory enforcement where there is a requirement of an urgency. With the most of cases for arbitration being the special field to make the decision only with the specialized knowledge that the arbitrator shall be the specialists who have appropriate knowledge of the system and render the most reasonable and fair decision for the arbitration. However, going through the second review by a court would be most important, irreparable and serious factor to interfere with the activation of the arbitration system. The only way to activate the arbitration system that failed to secure the practicality due to such a factor, is to revise the Arbitration Act and Arbitration Regulations so that the arbitration decision shall have the right to enforce under the Rules on Enforcement Document on Mediation Statement of various dispute resolution committees of the Supreme Court.