• Computational Structural Engineering
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• v.11 no.4
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• pp.351-360
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• 1998

본 논문에서는 실용적 체계신뢰성에 기초한 강사장교의 안전도평가를 위한 체계적인 모형을 제안하였다. 공용중인 강사장교의 시스템 안전도평가를 위하여 요소신뢰성해석을 위한 케이블, 주형 그리고 주탑의 한계 상태모형과 각 요소들간의 조합파괴를 포함하는 주파괴경로를 정의할 수 있는 체계신뢰성해석 모형을 제안하였다. 요소신뢰성해석을 위한 수치해석기법으로는 AFOSM(Advanced First Order Second Moment) 방법을 사용하였고, 체계신뢰성해석을 위해서는 부분 ETA(partial Event Tree Analysis) 모형을 사용하였다. 제안된 방법의 타당성을 고찰하기 위하여 진도대교의 안전도 평가에 적용하였다. 부분 ETA 모혀을 사용한 체계신뢰성 평가 방법은 기존의 요소신뢰성 방법에 비해 구조물의 여용성을 충분히 반영하는 상당히 합리적이며 실제적인 결과를 보여주는 실용적인 방법으로 판단된다.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.423-426
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• 2008

에탄올아민(ETA: Ethanolamine)은 탄소, 질소, 산소로 이루어진 유기화합물로 각종 산업에서 널리 사용되는 물질이다. 이러한 ETA는 상온에서는 휘발성을 띠지만 산 염기의 평형상수가 9.4 이므로 그 이하에서는 양이온 형태로 존재한다. 또한 수중에 존재할 경우 COD 및 T-N을 유발하는 물질이므로 이를 제거해야 한다. 따라서 본 연구에서는 수중에 존재하는 ETA를 제거하기 위해 온도, pH, 내부압력에 따른 ETA 증발 특성을 조사하였다. ETA증발 초기에는 끓는점의 차이로 인하여 물이 먼저 증발하며 일정시간 경과 후 농축된 ETA가 급격히 증발하였다. 내부압력이 낮아짐에 따른 ETA 수용액의 끓는점은 낮아졌으며 내부압력이 160mmHg이하일 때 가열온도에 영향을 받지 않고 ETA는 전량 증발하였다. 대기압 상태에서 ETA의 증발량은 pH에 영향을 받지만 진공상태에서는 ETA의 부분압이 낮아져 그 영향력은 매우 적었다.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.305-310
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• 1992

(${\eta}^5$-Cyclopentadienyl)bis(ethylene)cobalt (Jonas reagent), (${\eta}^5$-cyclopentadienyl)di(carbonyl)cobalt, and bis(${\eta}^5$-cyclopentadienyl)cobalt (cobaltocene) were reacted with oximes, respectively, under various conditions for synthesizing cobalt oxime sandwich complex. Jonas reagent and a dienemonooxime, 2,4-hexadienealdoxime underwent the reaction. This produced unexpected compound, (${\eta}^5$-cyclopentadienyl)(2,4-hexadienenitrile)cobalt [VII]. The compound [VII] was identified by NMR, mass spectrometer, IR and elemental analyzer etc.

• Journal of Korean Society of Steel Construction
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• v.19 no.4
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• pp.395-402
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• 2007

Probabilistic risk assessment was conducted on a hybrid cable-stayed bridge consisting of a steel-composite plate girder and a concrete girder with a long span, designed using the working stress design and strength design methods. The component reliabilities of the bridge's cables, pylons, girders, and steel-concrete conjunction were evaluated using the AFOSM(Advanced First Order Second Moment) algorithm and the simulation technique at the critical sections, based on the maximum axial force, shear, and positive and negative moments of the selected sections. For the analysis of system reliability, the hybrid cable-stayed bridge consisting of cables, pylons, and plate girders was modeled into combined failure modes, and for system reliability, the probabilities of failure and reliability index of the structural system were evaluated. Based on the results of this study, the critical failure modes of the hybrid cable-stayed bridge based on the bridge's structural characteristics are suggested, and the efficiency of the partial ETA technique for use in the risk assessment method was confirmed.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.209-213
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• 1998

The higher order structure of Pseudomonas alcaligenes 5S rRNA has been investigated by using ($\eta^{6}$-mesitylene) manganese (Ⅰ) tricarbonyl hexafluorophosphate[MTH-Mn (Ⅰ)], dimethylpyrocarbonate, potassium permanganate as chemical probes. The sequences cleaved strongly by MTH-Mn (Ⅰ) on the tertiary structure of the 5S rRNA are $G_{12}AUGG_{16}$ of loop a, $G_{51}AAGUGAAGC_{60}$ of the region b-C, $U_{65}-AGCG_{69}$. of the region B-a, and $G_{72}AUGG_{76}$ of loop d. Based on such cleavage patterns of 5S rRNA by MTH-Mn(Ⅰ) and other chemical probes, we presume that the sequences strongly cleaved form pocket-like structure as in the the corner of L structure of $tRNA^{Phe}$. We also presume that the region b-C and loop d together play a role of hinge in forming the pocket-like structure in the 5S rRNA.

• Microbiology and Biotechnology Letters
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• v.26 no.1
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• pp.40-44
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• 1998

A Penicillium strain which produces $eta$-galactosidase with high transgalactosylation activity, was isolated from soil and registered as Penicillium sp, KFCC 10888. When $eta$-galactosidase from Penicillium sp. KFCC 10855 reacted with 40% lactose, transgalactosylation ratio reached up to 70% at the 73% conversion of initial lactose. The biosynthesis of the enzyme in Penicillium sp. KFCC 10888 was not induced by lactose. The soybean meal was an effective component of the culture medium. The optimum pH and temperature for transgalactosylation were 4.0 and 55$^{\circ}C$, respectively. The production of galactooligosaccharides was in proportion to the initial lactose concentration. When the enzyme reacted with 40% lactose (pH 4.0) at 55$^{\circ}C$, the concentration of galactooligosaccharides increased up to 40% of total solid concentration.

• Journal of the Korean Chemical Society
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• v.48 no.5
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• pp.473-482
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• 2004

The homobimetallic anion, $M^+({\eta}^5-MeCp)Mn(CO)_2Mn(CO)_5^-(M^+=Na^+,\;PPN^+)$was disrupted by CH2CHCH2Cl in THF at various temperatures ($20^{\circ}C~50^{\circ}C$) under the pseudo 1st order reaction conditions where excess of allyl chloride was employed under a nitrogen atmosphere. This homobimetallic anion seems to be involved in a concerted reaction mechanism in which a four-centered transition state is proposed. After undergoing the transition state, this reaction eventually leads to (MeCp)Mn$(CO)_3$ on addition of CO and $({\eta}^1-allyl)Mn(CO)_5$, respectively. However, in case of $Na^+$ analog, $Na^+$ may play a novel counter ion effect on the disruption reaction either by transferring one terminal CO from the $Mn(CO)_5$ moiety on to the $({\eta}^5-MeCp)Mn(CO)_2$of the corresponding homobimetallic complex, eventually resulting in $({\eta}^5-MeCp)Mn(CO)_3$ or through the interaction between $Na^+$ and the leaving group (Cl) of allyl chloride. This reaction is of overall second order with respect to homobimetallic complex with the activation parameters (${\Delta}H^{\neq}=17.15{\pm}0.17kcal/mol,\;{\Delta}S^{\neq}=-9.63{\pm}0.10$ e.u. for $Na^+$ analog; ${\Delta}H^{\neq}=22.13{\pm}0.21 kcal/mol,\;{\Delta}S^{\neq}=9.74{\pm}0.19$ e.u. for $PPN^+$ analog reaction).

• Journal of the Microelectronics and Packaging Society
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• v.8 no.1
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• pp.5-11
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• 2001

Melting behavior and bridge phenomenon of solder paste, which is essential for surface mount technology in pachaging, were investigated. Solder paste of Sn-37%Pb was printed on Cu-pattern of PCB, and heated over melting point. Melting behavior of the paste was observed using CCD-camera. In order to modelize the melting and agglomeration phenomena of paste, two solder balls of 0.76 mm diameter were used. As experimental results, the paste start to melt from the margin of the printed shape. The height of the melted paste decreased from 270 $\mu\textrm{m}$ to 200 $\mu\textrm{m}$ firstly, and finally recovered to 250 $\mu\textrm{m}$ During the melting procedure, pores were evolved from the molted paste. Concerning melting model of solder ball, relationship between contact area of solder ball and soldering time was derived as $\chi^2/t=4r \; \gamma/\eta=7.56 m^2$/s at $280^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.886-892
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• 2013

Hydraulic hose assemblies are used as piping components for construction machinery, automobile, aircraft, industrial machinery, machine tools, and machinery for ships. Then the reliability of hose assemblies is important because total hydraulic system, which used to deliver the fluid power ($P^*Q$) needed to flexibility in the piping system, is not operated if the hose assembly failed in the system. The data of the accelerated life test estimated through the shape parameter(${\beta}$) resulting of the Weibull distribution analysis. This study has tried to reduce the test time resulting from varying impulse pressure range and the flexing diameter. Accelerated life test model for the test results was adopted the GLL(generalized log linear) and the accelerated indexes are identified as 6.64 for the pressure and 4.46 for flexing radius. Also, it found that shape parameter is 6.19, scale parameter(${\eta}$) is $1.035{\times}108$, which were adopted the pressure 35 MPa and the flexing diameter R100 mm in the used condition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.175-182
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• 2008

In this paper, through the study and consideration of the recently prominent monitoring of cable stayed-bridge, practical but reasonable suggested for the evaluation of the probabilistic safety of the bridges using probable measured data from monitoring measurement system. It is shown in the paper that the live load effects can be evaluated using measured data of cable-stayed bridge and this the realistic probabilistic safety of the cable-stayed bridge could be assessed in term of element reliability and system reliability. As a practical method for the evalution of the system reliability of system cable-stayed bridges partial ETA method is uesd, which can find the critical failure path including combined failure modes of cable, deck and pylon. Compared with the conventional safety analysis method, the propsed approach may be considered as the practical method that shows the considerably actual and reasonable results the system redundancy of the structure.