• Fire Science and Engineering
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• v.27 no.4
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• pp.1-6
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• 2013

When the pressurization system that uses difference of pressure for smoke control is designed, the factors influencing on the pressure field in building should be applied to design process and the stack effect is one of the main factors. Numerical analysis based on network model in 20-story building is carried out to analyze the pressurization system of smoke control in consideration of stack effect. Calculations are conducted for three conditions, that is, stack effect only, pressurization only and stack effect plus pressurization. Results including the detailed pressure field and flow rate at each floor are represented and the stack effect are effectively visualized. Meanwhile, the pressure of stairwell is increased as much as the summation of the stack effect and pressurization, and the problem induced by rise of pressure is pointed out.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2010.04a
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• pp.43-43
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• 2010

국내에 천연가스버스가 보급된 이래 5차례의 용기파열 사고가 발생하였는데 그중 2005년 8월 전주 덕진충전소에서 발생한 용기파열사고는 CNG용기의 라이너를 감싸고 있는 복합재료가 손상되어 발생한 사고로 보고되었다. 복합재료용기의 외피손상이 원인이 되어 발생한 사고사례는 해외에서 약 13건이 보고되었다. CNG용기 외피손상은 용기룰 고정하는 스트랩과 밀접한 관련이 있다. 용기고정이 불완전하면 슬립이 발생하고 이는 복합재의 손상으로 이어진다. 본 연구에서는 ISO 19078, CGA C6.4 등 국제코드의 규정을 고려하여 국내에서 제조된 Type 2, 3, 4 용기와 외국에서 생산된 Type 3 용기를 대상으로 결함깊이, 길이, 넓이에 따른 복합재료 결함 내구성시험을 수행하여 CNG용기의 내구성능을 평가하였고, 시험과 동일한 조건으로 복합재료 손상결함 조건을 컴퓨터로 전산모사하여 시험결과의 타당성과 유효성을 비교 검증하였다. 실험결과, Type 2 용기의 경우, 11,250회의 최소반복가압 회수를 충족하였으나 외피손상부와 반복가압에 따른 실제누출부위가 일치하지 않아 실험조건을 달리한 추가실험이 요구되었다. Type 3 용기의 경우에는 복합재 결함부위와 누수부위가 일치된 시험용기의 수는 67%정도로, 복합재료 용기의 수명을 저하시키는 원인으로 라이너와 외피손상이 서로 밀접한 관련이 있음을 확인하였다. Type 4 용기는 국제기준에서 요구하는 반복횟수를 만족하였고, 손상깊이 0.75mm와 1.25mm에서 반복가압회수가 60,000회 이상이 되어도 누설이 발생되지 않았다. 이는 라이너의 재질이 폴리머로서 균일한데다 탄소섬유 복합재료층 위에 유리섬유 복합재료 층이 1.5mm 정도 추가로 적층되어 있어서 3등급의 손상결함(결함깊이 1.25mm)에서도 구조 층이 전혀 손상되지 않은 것으로 판단되며, 이는 Type 2 용기의 강재라이너나 Type 3의 알루미늄 라이너와 비교하여 Type 4 용기의 폴리에틸렌 라이너의 물성이 반복성능이 탁월함을 확인할 수 있었다.

• Composites Research
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• v.29 no.2
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• pp.60-65
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• 2016

In this paper, finite element analysis and real time monitoring experimental work using FBG sensor were carried out for analyzing structural integrity of a Type IV hydrogen pressure vessel under impact loading condition. By using finite element analysis with the ply based modeling technique, sensor insertion points and pressure condition were suggested. Tensile test with an angle ply specimen was conducted for getting the reliability of FBG sensor insertion method. After fabricating the vessel, total five times pressurization fatigue tests were conducted (Non-impact pressurization: 1, After impact pressurization: 4). Experimental results revealed that filling cycle time was gradually increased and filling gradient was decreased when the vessel experienced impact.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.1-5
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• 2003

This study was carried out to prepare the depolymerized alginates by physical treatment processing with organic acids. The applied physical treatment methods were autoclaving, microwaving, and ultrasonicating, Among several physical depolymerization methods, autoclaving treatment was the most effective for hydrolyzing the alginate to low molecular compounds such as oligosaccharides. Citrate was most effective catalyst in hydrolyzing alginate to some oligosaccharides among organic acids. An acceptable autoclaving conditions for hydrolyzing alginate to oligosaccharides were to treat at $110^{\circ}C$ for 90 min and $120^{\circ}C$ for 60 min, respectively. The maximum depolymerization percentage produced by autoclaving was $56.8\%$. The depolymerized alginates prepared by autoclaving at $110^{\circ}C\;and\;120^{\circ}C$ has oligosaccharides of $3\~4 $and $7\~8$ species, respectively. The optimum condition for alginate oligosaccarides was autoclaving treatment with $0.5\%$ citrate solution at $120^{\circ}C$ for 90 min.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.546-552
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• 2009

Enzymatic ethanolysis of wheat germ oil with immobilized lipase was investigated for enhancing the function of wheat germ oil. Ethanolysis reactions were carried out in two different systems; non-pressurized and pressurized system. In non-pressurized system, the enzymatic ethanolysis was carried out in an erlenmeyer flask(25 ml) containing a mixture of wheat germ oil and 99.90% ethanol using 1~5 wt% immobilized lipase as Lipozyme TL-IM and Lipozyme RM-IM and the reaction mixtures were incubated at $40{\sim}70^{\circ}C$ with 120 rpm shaking. In pressurized system, the enzymatic ethanolysis was carried out at various condition; immobilized lipase concentration(2 wt%), reaction time(24 h), reaction temperature($40{\sim}60^{\circ}C$) and reaction pressure(75, 100, 150, 200 bars). The samples obtained from each fraction were analyzed by HPLC for analysing contents of monoglyceride, diglyceride, and triglyceride. The conversion of wheat germ oil relied on the reaction temperature and the concentration of immobilized lipase. The optimum condition of enzymatic ethanolysis in non-pressurized and pressurized systems was at $50^{\circ}C$ and 100 bar.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.692-698
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• 2012

The chemical conversion pattern of salvianolic acid B (Sal B) in aqueous solution under different boiling conditions was compared. When the duration of boiling was varied, without varying temperature or pressure, the content of chemically converted compounds (CCCs) was mostly increased over time. In addition, under different conditions of temperature and pressure with the same boiling time, the content of a few compounds increased with increasing temperature and pressure. These results confirmed that high temperatures and pressures in boiling alter the final composition of CCCs of Sal B. Therefore, it was suggested that the boiling conditions (time, temperature, and pressure) may be responsible for alteration of biological activities of the compounds. Our investigation of the chemical conversion of compounds contained in foods and medicinal herbs may provide important information in clarifying the biological activity of Sal B containing foods and medicinal herbs.

• Food Science and Preservation
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• v.10 no.3
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• pp.333-338
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• 2003

pH values in all samples were in the range of 5.04 to 5.32. pH of kanjang prepared with normal pressure(NPK) was higher than that of kanjang prepared with high pressure(HPK) and kanjang prepared with steam(SPK). Titratable acidity(TA) in all samples were found to be 4.26～7.72 mL. TA in HPK(5.99～6.96 mL) was lower than that in SPK(4.26～5.61 mL) and NPK(7.32 mL). Reducing sugar(RS) contents in all samples were in the range of 25.18 to 194.81 mg％. RS contents of HPK and SPK were a similar pattern and were higher than that of NPK. Major free sugars(FS) were glucose, fructose and xylose. In total FS, SPK was higher than that of NPK and HPK. Major organic acids(OA) were succinic acid, oxalic acid, tartaric acid, malic acid and citric acid. In total OA contents, SPK(40.38～76.96 mg％) was higher than that of NPK(55.85 mg％)and HPK(27.78～34.21mg％). OA contents in HPK and SPK were decreased slightly according to the heating time of whole black bean. The highest percentage of fatty acid (FA) in all samples was palmitic acid(33.28～43.51 ％ as area ％ of GC chromatogram), followed in a decreasing order by stearic acid(14.15～19.16％) and myristic acid(5.93～19.14％). The composition ratios of three FA to total FA ranged from 55.97 to 72.85＆. In all samples, there was myristic acid that was not contained in raw soybean.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.5
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• pp.355-374
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• 2022

Soil conditioning improves the performance of EPB (earth pressure balance) shield TBMs (tunnel boring machines) by reducing shear strength, enhancing workability of the excavated soil, and supporting the tunnel face during EPB tunnelling. The mechanical and rheological behavior of the excavated muck mixed with additives should be properly evaluated to determine the optimal additive injection condition corresponding to each ground type. In this study, the laboratory pressurized vane test apparatus equipped with a vane-shaped rheometer was developed to reproduce the pressurized condition in the TBM chamber and quantitively evaluate rheological properties of the soil specimens. A series of the pressurized vane tests were performed for an artificial sand soil by changing foam injection ratio (FIR) and polymer injection ratio (PIR), which are the injection parameters of the foam and the polymer, respectively. In addition, the workability of the conditioned soil was evaluated through the slump test. The peak and yield stresses of the conditioned soil with respect to the injection parameters were evaluated through the rheogram, which was derived from the measured torque data in the pressurized vane test. As FIR increased or PIR decreased, the workability of the conditioned soil increased, and the maximum torque, peak stress, and yield stress decreased. The peak stress and yield stress of the specimen from the laboratory pressurized vane test correspond to the workability evaluated by the slump tests, which implies the applicability of the proposed test for evaluating the rheological properties of excavated soil.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.3
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• pp.199-209
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• 2014

Crevice corrosion tests were conducted to examine the corrosion properties of HYBRID (HYdrazine Base Reductive metal Ion Decontamination) which was developed to decontaminate the PWR primary coolant system. To compare the corrosion properties of HYBRID with commonly existing decontamination agents, oxalic acid (OA) and citric oxalic acid (CITROX) were also examined. Type 304 Stainless Steel (304 SS) and Alloy 600 which are major components of the primary coolant system in Pressurized Water Reactor (PWR) were evaluated. Crevice corrosion tests were conducted under very aggressive conditions to confirm quickly the corrosion properties of primary coolant system structure components which have high corrosion resistance. Pitting and IGA were occurred in crevice surface under OA and CITROX conditions. But localized corrosion was not observed under HYBRID condition. Very low corrosion rate of less than $1.3{\times}10^{-3}{\mu}m/h$ was observed under HYBRID condition for both materials. On the other hand, under OA condition, Alloy 600 indicated comparatively uniform corrosion rate of $4.0{\times}10^{-2}{\mu}m/h$ but 304 SS indicated rapid accelerated corrosion in lower case than pH 2.0. In case of HYBRID condition, general corrosion and crevice corrosion were scarcely occurred. Therefore, material integrity of HYBRID in decontamination of primary coolant system in pressurized water reactor (PWR) reactor was conformed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.310-313
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• 2009

Several high nitrogen stainless steel ingots(100kg) were fabricated with changing Ni and $[N]_2$ contents by Pressurized Vacuum Induction Melting(P_VIM). After free forging process, chemical compositions, microstructure and mechanical properties were estimated. Hardness was increased with the increase of $[N]_2$ content. Furthermore, microstructure including a lot of tempering twins was observed with optical microscope. Mechanical properties were estimated as function of solution treatment temperature and cooling method(air/water) under duration time of 1 hr on sample that were fabricated with Ni content under the atmospheric $[N]_2$ pressure. At solution treatment range of $1050{\sim}1100^{\circ}C$, hardness was decreased with the increase of solution temperature and there were little discrepancy of microstructure and hardness with cooling method. Computer simulation was carried out in order to inspect pass schedule in cold rolling process. When the condition of simulation was roll speed of 2.5mpm, rolling rate $15{\sim}17%$ per pass, it was ascertained that the formation such as deformation by sticking and lamellar sliver etc. was restricted from a simulation.