• KSCE Journal of Civil and Environmental Engineering Research
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• v.1 no.1
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• pp.9-19
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• 1981

Using superplasticizer or the methods of autoclave curing is the most typical and practical of the ways to make high strength concrete. In this study the high strength concrete piles by way of centrifugal forming and hand compacting, are put to the freezing and thawing test after the process of autoclave curing, water curing after steam curing, or stand water curing. And the relation of such piles to durability, the rate of strength decrease, and the rate of weight variation is shown. The durability of those test piles throughout freezing and thawing test proves to be comparatively sufficient in the above-mentioned curings when the piles contain a proper quantity of air. But it is also acknowledged that without A.E agent, the high strength concrete piles of autoclave curing is higher than those of the other curing in strength, but lower in modulus of dynamic elasticity and their durability factor after the test is much lower.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.8
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• pp.1162-1169
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• 2016

A new method based on accelerated solvent extraction (ASE) combined with response surface methodology (RSM) has been developed for optimization of the extraction of ginsenoside [Rb1, Rg1, and Rg3(20S)], total phenolics, and benzopyrene in red ginseng. The RSM method, based on a five level and two variable central composite design, was employed to obtain the optimal combination of extraction conditions. In brief, ginsenosides Rb1, Rg1, and Rg3(20S) and total phenolics with undetectable benzopyrene were optimally extracted with 50% ethanol as an extraction solvent, extraction temperature of $158^{\circ}C$, extraction time of 20 min, extraction pressure of 2,500 psi, flush volume of 60%, and one extraction cycle. The contents of ginsenosides and total phenolics in red ginseng extracted by ASE under optimum conditions were significantly higher than those extracted by sonication and reflux extraction.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.11
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• pp.753-760
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• 2019

Sparkjet actuator, also known as plasma synthetic jet actuator, which is a kind of active flow control actuator is considered as being high possibility for the supersonic flow control due to ejecting stronger jet compared to the other active flow control actuators. Sparkjet actuator generates high temperature and high pressure flow inside the cavity by using arc plasma and leads momentum by ejecting such flow through orifice or nozzle. In this research, numerical calculation of sparkjet actuator with respect to the location of electrodes which exists inside the cavity is conducted and the change of the performance of sparkjet actuator is suggested. As the location of electrodes goes closer to the bottom of the cavity, impulse is increased and the average pressure inside the cavity maintains higher. When the location of electrode is 25% and 75% of the entire cavity height, impulse is 2.515 μN·s and 2.057 μN·s, respectively. Each impulse is changed by about 9.92% and -10.09% compared to when the location of electrodes is 50% of the entire cavity height.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.403-412
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• 2018

Recently, needs for utilization of recycled aggregate have been increasing. However, its utilization has been limited due to its high alkalinity, which mostly came from the unremoved cement paste particles that were attached at the surface of recycled aggregate. Various efforts has been made to reduce its alkalinity by using $CO_2$, but currently available methods that uses $CO_2$ generate the problem with pH recovery. Considering the fact that supercritical $CO_2$ ($scCO_2$) can provide more rapid carbonation of cement paste than by normal $CO_2$, $scCO_2$ was utilized in this work. The reaction between $scCO_2$ and hydrated cement paste has been systematically evaluated. According to the results, it was found that powder type showed higher carbonation compared to that of cube specimens. It seems the carbonation by $scCO_2$ has occurred only at the surface of the specimen, and therefore still showed some amount of $Ca(OH)_2$ calcium aluminates after reaction with $scCO_2$. With powder type specimen, all $Ca(OH)_2$ was converted into $CaCO_3$. Moreover, additional calcium that came from both calcium aluminate hydrates and calcium silicate hydrates reacted with $scCO_2$ to form $CaCO_3$. After carbonation with $scCO_2$, the powder type specimen did not show pH recovery, but cube specimens did show due to the presence of portlandite.

• Journal of the Korean Applied Science and Technology
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• v.37 no.1
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• pp.83-90
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• 2020

Plate heat exchangers(PHE) have been commercialized since the 1920s. Since then, although the basic concept of PHEs has changed little, its design and construction have progressed significantly to accommodate higher temperatures, higher pressures, and large heat exchanging capacities. The development trend of PHEs is consistent with heat plate developments with better thermal efficiency, lower pressure drop, and good flow distribution. The purpose of this paper is to introduce the main development processes of a plate cooler for medium-speed engine lubricant oil cooling in vessels which is in line with the development trend of PHEs and to provide its thermal performance data that were found out during experimental tests. The plate cooler in this study cannot measure the wall temperatures directly due to its structural characteristics, so the heat transfer coefficients were calculated using the modified Wilson Plot method. The water-to-water tests were first conducted experimentally to figure out the characteristics of heat transfer coefficients and pressure drops on the water side and then the water-to-oil tests followed to obtain the heat transfer coefficients on the oil side. The test results showed that heat transfer coefficients and pressure drops on both water and oil side increased with flow rates, and it was also found that all the development targets of the plate cooler in this study were achieved successfully.

• Journal of Life Science
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• v.26 no.12
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• pp.1477-1486
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• 2016

Lactulose (4-O-${\beta}$-D-galactopyranosyl-D-fructose) is a non-digestible synthetic ketose disaccharide which can used in food and pharmaceutical fields due to its useful functions for encephalopathy, chronic constipation, hyperammonemia, etc. Therefore, the lactulose is regarded as one of the most important disaccharides and have been concentrated much interesting as an attractive functional material in the current industry. From this reason, the research related on the production of lactulose has been carried out various academic and industrial research groups. To produce lactulose, two main methods, chemical production and enzymatic production have been used. Commercially lactulose produced by alkaline isomerization of lactose as chemical production method but it has many disadvantages such as rapid lactulose degradation, purification, and waste management. From these reasons, lactulose produced by enzymatic method which solves these problems has been suggested as a proper method for lactulose production. Two different enzymatic methods have been reported as methods for lactulose production. Lactulose can be obtained through hydrolysis and transfer reaction catalyzed by a ${\beta}$-galactosidase which requires fructose as co-substrate and exhibits a low conversion. Alternatively, lactulose can be produced by direct isomerization of lactose to lactulose catalyzed by cellobiose 2-epimerase which requires lactose as a single substrate and achieves a high lactulose yield. This review summarizes the current state of lactulose production by chemical and biological methods.

• Fire Science and Engineering
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• v.29 no.6
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• pp.40-44
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• 2015

National and international standards for curtain wall glass are focused on wind pressure and insulation performance, but disasters such as fires and earthquakes are not considered. Failure of curtain wall glass during a fire in a skyscraper increases the loss of lives and property due to the spread of fire. Therefore, the fire resistance of curtain wall glass should be investigated, and technology to prevent glass failure should be developed to prevent fire damage due to spreading fire. It is important to predict the starting point of cracks and the cause of glass failure to prevent it effectively using the limited water in a skyscraper. In this study, double glazed glass was exposed to a radiator in an experiment performed to analyze the thermal characteristics. The results show that glass that was not directly exposed to high temperature and pressure was broken. To identify this failure case, numerical analysis was performed. Three glass specimens were installed in an ISO 9705 room and exposed to radiation using a radiator, and a thermocouple was used to measure the temperature on the surface of the glass. Widely used double glazed glass was analyzed for weakness to fire.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.112.1-112.1
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• 2011

쌀을 주식으로 하는 우리나라의 여건상 연간 추정치로 싸라기 약 12만톤, 미강 약 49만톤, 왕겨 약 79만톤의 벼 도정 부산물이 발생하고 있다. 본 연구에서는 벼 도정 부산물 중 비식량 자원인 왕겨를 대상으로 고효율 효소 당화를 위한 바이오매스 전처리 방법을 탐색하였다. 왕겨 원시료의 초기 조성은 셀룰로스 34.5%, 헤미셀룰로스 20.5%, 리그닌 25.3%, 회분 14.6%로 나타났는데, 억새 등 초본계 바이오매스와 비교하여 특이하게 높은 성분은 회분으로 이는 벼에 대한 규산질 비료의 시용에서 기인한 것이다. 바이오매스 전처리에 많이 사용되는 암모니아, 희황산 용매와 규산염에 침식성을 가지는 가성소다 용매를 이용하여 각 용매별 단독 및 알칼리-산 복합 처리 하였을 때 효소 가수분해 효율, 고상시료 성분변화 등을 상호 비교하였다. 예비실험을 통하여 암모니아 처리조건은 15%(w/w) $150^{\circ}C$ 20분, 가성소다 처리조건은 1.5%(w/w) $150^{\circ}C$ 20분, 희황산 처리조건은 1.0%(w/w) $150^{\circ}C$ 10분으로 설정하였다. 암모니아 단독, 희황산 단독, 암모니아-희황산 복합 처리 시료의 효소 가수분해 효율은 각각 37.8%, 39.1%, 42.8%로 약 40%선에서 큰 차이가 없었다. 반면 가성소다 단독, 가성소다-희황산 복합 처리시료의 효소 가수분해 효율은 각각 62.7%, 82.8%로 나타나 앞선 3가지 처리방법 대비 50%, 100%에 가까운 효소 가수분해 효율 향상을 보였다. 이 때 전처리 고상시료의 성분 변화를 살펴보면 회분 함량에서 큰 차이를 보였는데 암모니아 단독, 가성소다 단독, 희황산 단독, 암모니아-희황산 복합, 가성소다-희황산 복합 처리에서 각각 47.8%, 77.1%, 43.5%, 55.8%, 94.7%의 회분 성분 기각률(rejection rate)을 나타냈다. 이는 왕겨 효소 가수분해 효율의 최대 저해요인이 회분임을 추정할 수 있다. 왕겨 전처리 알칼리 용매는 암모니아보다 가성소다가 더 효과적이었고 희황산 복합 처리시 그 효과가 크게 상승하였다. 따라서 규산염(회분) 함량이 높은 바이오매스는 고온 고압 조건에서 가성소다 용액으로 처리한 후 그 고상분을 희황산 용액으로 복합 처리하는 시스템이 효소 당화 증진에 매우 유리함을 확인하였다.

• Korean Journal of Microbiology
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• v.40 no.4
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• pp.334-341
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• 2004

Polysaccharides were prepared from Orostachys japonicus by extration with hot steam water (OJPl). The OIPl fraction was further purified by Sephadex G-50 gel filtration chromatography to produce FI (polysaccharides) and FII (oligosaccharides) fraction. The average molecular masses o fFI and FII fraction were determined to be 3050 kDa and 13 kDa, respectively. The antimicrobial activity of OIPl was tested against 8 strains of bacteria and one strain of yeast by the disc diffusion method, fluorescein diacetate (FDA) method and broth dilution method. The OIPl exhibited a very strong growth inhibition to Candida albicans. The OIPl remarkably sup­pressed the growth of Salmonella typhimurium and Staphylococcus aureus. The OIPl showed higher growth inhibition to Escherichia coli and Pseudomonas aeruginosa than propolis, positive control. When the anticancer activity of the OIPl, FI or FII was examined against human cancer cell lines and the Sarcoma 180 cells, these widely suppressed the proliferation of cell lines in the MTT assay and morphology study. Especially, they remarkably inhibited the growth of A549, HeLa and AGS cells. Also treatment of cancer cells with OJPl, FI or FII induced apoptotic cell death characterized by DNA fragmentation. The OJPl, FI or FII exhibiting various biological activities such as antimicrobial activity and anticancer activity is expected to be developed as new biohealth products.

• Analytical Science and Technology
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• v.23 no.6
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• pp.544-550
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• 2010

Mistaking pink colored thermal oil for grape wine, a victim drank the oil to death which was analyzed to contain 39% of ethylene glycol. Thermal oil could be used for heat transfer to prevent the malfunction due to the high pressure in the boiler operated at high temperature when using water. Main component of thermal oil is known to be mineral oil or ethylene glycol. From the blood and other tissue of the victim from autopsy, ethylene glycol and its metabolite were simultaneously analyzed by GC/MS after extraction under acidic condition with acetonitrile followed by derivatization with BSTFA. About 0.2 g of the specimens were pretreated with 50 uL of 0.5 M HCl solution to keep acidic condition, then dehydrated with anhydrous sodium sulfate followed by concentration under nitrogen stream. Ethylene glycol and glycolic acid concentration in blood was measured to be $2,755\;{\mu}g/mL$ and $174\;{\mu}g/mL$ respectively. In other specimen, the concentration of ethylene glycol and glycolic acid was $860\;{\mu}g/g\sim1,290\;{\mu}g/g$ and $93\;{\mu}g/g\sim134\;{\mu}g/g$. Especially, crystal appeared in kidney which was supposed xalate from the metabolite of ethylene glycol.