2-Propanol-물 혼합용매에 대한 n-Alkylamine 염산염의 Partial Molal Volume에 관한 연구

윤상기,엄태섭,김봉규,박종열 東亞大學校 1977 東亞論叢 Vol.14 No.-

2-propanol-물 혼합용매계에 대한 n-alkylamine 염산염의 "겉보기몰랄부피" ø??를 부력법을 이용하여 30℃에서 측정하였다. Amine염 C??H??NH??Cl은 C??에서 C??에 이르는 저급 동족체를 시료로 하고 혼합용매 각 조성마다. 0.01M~0.2M 농도범위안의 용액에 대한 float의 무게를 소수점이하 5위까지 평량하였다. Limiting law equation에 의거 농도의 평방근 √vsø?? plot한 것을 C→0 즉 무한대의 묽은 쪽으로 extrapolation 함으로서 "분몰랄부피"V를 구하였다. 실험결과는 농도변화와 용매조성에 따른 ø?? 및 V의 변화, limiting slope S'와 ion의 charge effects 등에 대하여 논의하였다. 즉 √대 ø?? plot의 결과는 기울기가 크고 positive한 두 직선이 생기는데 이것이 √ 0.2부근에서 예리하게 교차되는 것이 관측 되었다. 또한 0.2m.f. 조성 때에 maximum의 S'와 minimum의 V?? 값이 나타나고 아울러 ion의 charge effect가 maximum임을 알았다. 실험결과는 또한 같은 시료를 methanol-물, ethanol-물 혼합계에 각각 적용한 결과와 비교하여 논의하였다. The apparent and partial moral volumes (ø?? and V??) of the lower homologous salts of n-alkylamine hydrochloride C??H??NH??Cl where C?? varies from C?? to C?? have been determined to the fifth decimal place at 30℃ by means of float method in 2-propanol-water mixtures, and the values of ø?? extrapolated to infinite dilution according to the limiting law equation give partial molar volumes. The experimental results are discussed in terms of the charge of ion and of the volume change in apparent molar volumes depend upon the increase of he concentration of the solutions and in partial molal volume according to the varing composition of mixed solvent. It has been observed that the plot of ø?? vs c?? showed sharp transition at approximately c?? 0.2 with anomalously positive and large slope, while the maximum charge effect related to the limiting slope S'?? causes minimum in V?? at 0.2 mole fraction of mixed solvent. It has been discussed and compared with respect to the results of the previous study as examined for the same sample species in methanol and ethnol-water mixtures respectively.

기업의 지속적 발전(sustainability)에 관한 평가 연구

장기윤,김봉구 고려대학교 2007 생명자원연구 Vol.15 No.-

고온설비의 FFS평가를 위한 308 스테인리스강의 크리프 균열성장 재료물성에 대한 연구

이경용,백운봉,윤기봉 한국산업안전학회 2002 한국안전학회지 Vol.17 No.4

For fitness-for-service evaluation of high temperature plant components with defects, crack growth life must be assessed properly as indicated in the recent draft of API 579 code. Type 308 stainless steel has been widely used as a field weld material in the petrochemical industry. In this study, creep crack growth data of type 308 stainless steel are colleted and re-analyzed using C_t as a characterizing fracture parameter. A unique da/dt versus C_t relationship was obtained despite of difference of creep deformation constant or the reviewed materials and specimen geometry of the tested specimens. The obtained results can be employed for crack growth life assessment and fitness-for-service evaluation for the cracks in high temperature components. It is also argued that since the effect of creep properties and other material variability on the creep crack growth behavior would be minor the obtained model may be applied for most of the 308 stainless steels.

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.

API 기준에 근거한 RBI 절차 개발 및 소프트웨어의 구현 (Ⅲ) : 정량적 접근법 Quantitative Approach

송정수,심상훈,최송천,윤기봉 한국산업안전학회 2003 한국안전학회지 Vol.18 No.1

During the last decade, effort has been made for reducing maintenance cost for aged equipments and ensuring safety, efficiency and profitability of petrochemical and refinery plants. Hence, it was required to develop advanced methods which meet this need. RBI(Risk Based Inspection) methodology is one of the most promising technology satisfying the requirements in the field of integrity management. In this study, a quantitative assessment algorithm for RBI based on the API 581 code was reconstructed for developing as RBI software. The user-friendly realRBI software is developed with a module for evaluating quantitative risk and financial risk using the potential consequence and the likelihood. Also inspection planning module for inspection time and inspection method are included in it.

API 기준에 근거한 RBI 절차 개발 및 소프트웨어의 구현 (Ⅱ) : 준정량적 접근법 Semi-Quantitative Approach

송정수,심상훈,권정락,윤기봉 한국산업안전학회 2002 한국안전학회지 Vol.17 No.4

During the last then years, the need has been increased for reducing maintenance cost for aged equipments and ensuring safety, efficiency and profitability of petrochemical and refinery plants. American Petroleum institute(API) developed a code, API 581 for proposing standard procedures of risk based inspection. Even though the API 581 code covers general RBI procedures, there must be some limitations. In this study, a semi-quantitative assessment algorithm for RBI based on the API 581 code was reconstructed for developing an RBI software. The user-friendly realRBI software is developed with a module for evaluating semi-quantitative risk category using the potential consequence factor and the likelihood factor. Also, inspection planning module for inspection time and inspection method for equipments are included.

API 기준에 근거한 RBI 절차 개발 및 소프트웨어의 구현 (Ⅰ) : 정성적 접근법 Qualitative Approach

심상훈,송정수,김지윤,윤기봉 한국산업안전학회 2002 한국안전학회지 Vol.17 No.3

During the last ten years, effort has been made for reducing maintenance cost for aged equipments and ensuring safety, efficiency and profitability of petrochemical and refinery plants. Hence, it was required to develop advanced methods which meet this need. RBI(Risk Based Inspection) methodology is one of the most promising technology satisfying the requirements in the field of integrity management. In this study, a qualitative assessment algorithm for RBI based on the API 581 code was reconstructed for developing an RBI software. The user-friendly realRBU software is developed with a module for evaluation qualitative risk category using the potential consequence factor and the likelihood factor.

초내열 합금 Alloy718의 저주기 피로시험에서 반복연화 및 R=X (X=0,-1)효과

최병학,신수근,신정근,김선화,윤기봉,염종택,박노광 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-

The LCF properties for R=0 as tension-tension and R=-1 as tension-compression were examined in DA alloy718. While the hysteresis loops composed of ?ε_(t), ?ε_(p) and ?σ were figured with similaity in both of R=0 and R=-1, the loops of R=0 were continuely going down along the stress axis during cyclic fatigue progressing. It was caused by Bauschinger effect, which includes a tendancy for stress recovering as an amount of compression stress. The phenomena of cyclic softening in both of R=0 and R=1 seem to be caused by planar slip of dislocations, which was accompanied by shearing the γ'/γ" precipitates during the cyclic fatigue test.

A Study on Hydrogen Embrittlement for Inconel 617 and Hasteloy C-276 Using Small Punch Testing

Kee Bong Yoon,J.Y. Lee,P.V. Duyet,S.Y. Jeong,Y.W. Ma 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

Cracking of 5Cr steel tee-pipe during start-up operation in heavy oil upgrade refinery

Yoon, Kee Bong,Byun, Chul Hyun,Nguyen, Tuan Son,Yu, Jong Min,Jeon, Gyu Min Elsevier 2017 Engineering failure analysis Vol.81 No.-

<P><B>Abstract</B></P> <P>During the start-up operation of an HOU refinery plant, leaking through a crack at the top of a T-pipe was found in a hydrocracking process. Various kinds of metallurgical inspections of the failed T-pipe were performed in order to find the cause of cracking e.g., metallography, fractography, hardness measurement, EDS analysis and hydrogen concentration measurement. Since thermal loading in the T-pipe was usually higher during the start-up operation than under steady operations, a system load analyses of the pipe was conducted. Detailed finite element analysis of the T-pipe was also conducted to identify high stress locations and to assess the stress intensity factor of the crack partly penetrated the T-pipe.</P> <P>The 5Cr T-pipe steel satisfied the chemical composition requirements for ASTM A234 but the tensile strength and hardness were significantly higher than recommended in the standard, which made the pipe steel vulnerable to a hydrogen environment formed by the feed inside of the pipe. The cracking started from the inclusions near the inner surface of the pipe and grew due to the hydrogen effect. Inspection results supporting this argument are explained. And recommendations for preventing similar cracking failures were made.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Leaking at T-pipe occurred during start-up operation of a refinery plant. </LI> <LI> Cracking can occur at very low stress locations if hydrogen damage is involved. </LI> <LI> 5Cr steel with high hardness/strength made it vulnerable to hydrogen damage. </LI> <LI> Inclusions (Al<SUB>2</SUB>O<SUB>3</SUB>, SiO<SUB>2</SUB>) near the inner surface may act as hydrogen crack initiation locations. </LI> <LI> Hydrogen charging as a result of SCC reaction can cause hydrogen cracking. </LI> </UL> </P>