• 한국농공학회지
• /
• 제24권2호
• /
• pp.67-75
• /
• 1982

A study on the effect of water reducing agent on the various characteristics of concrete has been conducted. The experimental results of the study are summarized as follows. 1. Slump test for the concrete added water reducing setretarding agent in proper quantity have been conducted. According to the test results, the decreasing rate of slump value become bigger than plain concrete with increase of the unit weight of cement and elapse of time 2. In case the proper quantity content of maximum compressive strength in Fig. 5 of water reducing set retarding agent is added, unit weight of water is decreased about 15% or so as compared with plain concrete. with the increase of water reducing set accelerating agent content unit weight of water is decreased much more, And other hand, amount of air entraining shows the increasing tendency with the increase of water reducing agent content. 3. The adding rate of water reducing agent which produce maximum strength shows that WR-CH and WR-SA which is water reducing set-starding agent is 0.2% and WR-CO is 0.5% and that WS-PO which is water reducing set accelerating agent is 0.5 4. compressive strength jof the concrete made of sulfate resistant cement shows less than the strength of normal portland cement at initial strength but the strength of both cement shows almost same at curing age of 28 days. 5. when proper quantity of water reducing set retarding agent is used, boned strength is increased about 15% at curing age of 28days. 6. According to the result of durability test, dynamic young's mudulus of elasticity at plain concrete is decreased about 50% as compared with initial step at 300 cycle of freezing and thawing after curing age of days. on the contarary the concrete used water reducing agent is decreased less than 7%.

• 청정기술
• /
• 제29권4호
• /
• pp.327-332
• /
• 2023

본 연구에서는 바이오가스 수증기 개질을 통한 합성가스 생산에 관해 연구했다. Ni-Al₂O₃ 및 Ni-CeO₂ 촉매는 공침법으로 제조되었으며 침전제 주입 속도가 조절되었다. 온도에 따른 촉매 성능 테스트는 CH₄:CO₂:H₂O = 1:0.67:3의 가스 조성비와 647,000 mL h^-1 gcat^-1의 공간속도에서 진행하였다. 침전제 주입 속도는 촉매 특성에 영향을 미쳤으며, 지지체 종류에 따라 결과를 보였다. 온도가 증가함에 따라 이산화탄소 개질 반응과 reverse water gas shift 반응이 일어났다. 수증기가 충분히 공급되는 조건에서는 침전제를 한 번에 투입하여 제조된 Ni-Al₂O₃ 촉매가 높은 Ni 분산도에 기인하여 가장 우수한 성능을 보였다.

• 폴리머
• /
• 제30권4호
• /
• pp.286-292
• /
• 2006

Super water-absorbent resins were prepared by inverse suspension copolymerization of sodium acrylate, acrylamide and 2-hydroxyethyl acrylate using N, N'-methylene-bis-acrylamide as cross-linker. For the suspension copolymerization, monohexadecyl phosphate was employed as the dispersing agent, cyclohexane as the dispersing medium and potassium persulfate as the initiator. The dependence of water-absorption capacity on the amount of crosslinking agent, oil/water ratio, degree of neutralization and the composition of the copolymer were systematically investigated. Furthermore, the swelling kinetics of the super water-absorbent copolymer was carried out. The absorption of the resins is more than 1800 g/g for deionized water and 100 g/g for 0.9% NaCl solution, respectively. The copolymers showed an increased salt resistance and enhanced water retention of soil.

• Journal of Microbiology and Biotechnology
• /
• 제15권4호
• /
• pp.887-890
• /
• 2005

To evaluate the hepatoprotective activity of lactic acid bacteria, their effects on tert-butylperoxide (t-BHP)-induced hepatotoxicity in mice were measured. When lactic acid bacteria at doses of 0.5 and 2 g (wet weight)/kg were orally administered to mice with t-BHP-induced liver injury, these bacteria significantly inhibited the increase of plasma alanine aminotransferase and aspartate aminotransferase activities by $17-57\%$ and $57-66\%$ of the t-BHP control group, respectively. However, these lactic acid bacteria did not protect cytotoxicity induced by t-BHP against HepG2 cells. The inhibitory effects of these lactic acid bacteria at a dose of 15 g/kg were comparable with that of diphenyl dimethyl bicarboxylate at a dose of 0.2 g/kg, which has been used as a commercial hepatoprotective agent. Among these lactic acid Jacteria, Bifidobacterium longum HY8001 exhibited the most potent hepatoprotective effect. These orally administered lactic acid bacteria inhibited liver lipid peroxidation on t-BHP-induced hepatotoxicity of mice. We suggest that lactic acid bacteria may be an effective agent against liver injury.

• Journal of Pharmaceutical Investigation
• /
• 제27권1호
• /
• pp.23-27
• /
• 1997

To investigate the effect of L-arginine as stabilizing agent for omeprazole, the degradation rate constant of omeprazole in aqueous solution was determined at 30, 40 and $50^{\circ}C$ with various ratios of L-arginine to omeprazole. The pH of omeprazole solutions was also determined. As the amount of L-arginine increased, the pH of omeprazole solution also increased, and the solution appeared to be more stable. The omeprazole in aqueous solution could be stabilized by more than 15:1 molar ratio of L-arginine to omeprazole. The stability of omeprazole in commercial products using L-arginine or sodium phosphate dibasic as stabilizing agent was investigated. Among the commercial products, the omeprazole product prepared with L-arginine (molar ratio of L-arginine to omeprazole, 20:1) was most stable.

• 대한화장품학회지
• /
• 제24권3호
• /
• pp.65-72
• /
• 1998

In this study, we demonstrated the whitening effect of Lagenaria leucantha through the melanin biosynthesis of S bikiniensis and inhibition of melanogenesis in cultured Bl6 melanocytes. And we confirmed the whitening effect of Lagenaria leucantha through the depigmentation of gold fish in vivo. The melanogenesis of B$_{16}$ melanocytes was founded to be activated dose and time dependently by the treatment of u- MSH. When the B$_{16}$ melanocytes was treated with 200nM of $\alpha$-MSH, the morphology of melanocytes was remarkably changed. The melanin content and the synthesis of tyrosinase were strikingly increased. Lagenaria ieucantha inhibited the melanin formation stimulated by $\alpha$-MSH without affection of cell viability. However, Lagenaria leucantha didn't inhibit tyrosinase activity and showed weak suppression on the synthesis of tyrosinase. These results suggest Lagenaria leucantha might inhibit melanin formation with tyrosinase independent manner. Lagenaria ieucantha also inhibition melanin biosynthesis with 18mm inhibition zone in S.bikiniensis. To evaluate the inhibitory activity of melanogenesis of Lagenaria leucantha in vivo, we examined its effect on depigmentation of gold fish. Lagenaria ieucantha remarkably reduced the size and density of melanophores in gold fish. These results suggest that Lagenaria ieucantha can be used as a whitening agent in cosmetics.ics.s.

• 대한화학회지
• /
• 제58권1호
• /
• pp.92-99
• /
• 2014

The pH sensitive hydrogels composed of N-isopropylacrylamide (NIPA) and acryloyl phenylalanine (APA) were prepared by redox polymerization using N,N'-methylenebisacrylamide (MBA) as a crosslinker. Anti-inflammatory and analgesic agent, Keterolac Tromethamine (KT), was loaded successfully into poly(NIPA-co-APA) copolymeric hydrogels by swelling equilibrium method. To understand the nature of drug in the polymeric matrix, the newly synthesized drug loaded poly(NIPA-co-APA) copolymeric hydrogels were characterized by using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The scanning electron microscopy (SEM) technique result indicates the spherical smooth surface of the hydrogels. The drug (KT) releasing nature of the poly(NIPA-co-APA) hydrogels was studied in pH 1.2 and 7.4. Effects of drug loading, crosslinking agent, pH and the ionic strength of the external medium on swelling of hydrogels were also investigated.

• ETRI Journal
• /
• 제37권5호
• /
• pp.1032-1043
• /
• 2015

ETRI's Co-Pilot project is aimed at the development of an automated vehicle that cooperates with a driver and interacts with other vehicles on the road while obeying traffic rules without collisions. This paper presents a core block within the Co-Pilot system; the block is named "Co-Pilot agent" and consists of several main modules, such as road map generation, decision-making, and trajectory generation. The road map generation builds road map data to provide enhanced and detailed map data. The decision-making, designed to serve situation assessment and behavior planning, evaluates a collision risk of traffic situations and determines maneuvers to follow a global path as well as to avoid collisions. The trajectory generation generates a trajectory to achieve the given maneuver by the decision-making module. The system is implemented in an open-source robot operating system to provide a reusable, hardware-independent software platform; it is then tested on a closed road with other vehicles in several scenarios similar to real road environments to verify that it works properly for cooperative driving with a driver and automated driving.

• Applied Microscopy
• /
• 제51권
• /
• pp.13.1-13.7
• /
• 2021

The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has arisen as a global pandemic affecting the respiratory system showing acute respiratory distress syndrome (ARDS). However, there is no targeted therapeutic agent yet and due to the growing cases of infections and the rising death tolls, discovery of the possible drug is the need of the hour. In general, the study for discovering therapeutic agent for SARS-CoV-2 is largely focused on large-scale screening with fragment-based drug discovery (FBDD). With the recent advancement in cryo-electron microscopy (Cryo-EM), it has become one of the widely used tools in structural biology. It is effective in investigating the structure of numerous proteins in high-resolution and also had an intense influence on drug discovery, determining the binding reaction and regulation of known drugs as well as leading the design and development of new drug candidates. Here, we review the application of cryo-EM in a structure-based drug design (SBDD) and in silico screening of the recently acquired FBDD in SARS-CoV-2. Such insights will help deliver better understanding in the procurement of the effective remedial solution for this pandemic.

• 한국입자에어로졸학회지
• /
• 제10권3호
• /
• pp.109-117
• /
• 2014

In Korea, permeable protection clothes for chemical agent is being developed and distributed. But permeable protection clothes are vulnerable for biological agent of particle type. Therefore selective permeable membranes are being developed to protect chemical agent and biological agent simultaneously. In this study, aerosol collection efficiency test was performed to validate the protection performance of permeable clothes and selective permeable membranes. Aerosol collection efficiency test was performed by using the aerosol test equipment that could test aerosol particle diameter from $0.005{\mu}m$ to $3.0{\mu}m$. This study shows the test method and performance test results for collection efficiency by using the aerosol test equipment.