• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.10-19
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• 2013

Recently, researches related to precast modular construction have been actively conducted for nuclear power plant, LNG gas tank, and small-medium PCCV as well as bridges and buildings. In this study, the precast panel cast with steel mesh reinforced mortar (SRM) which is similar reinforced ferrocement was developed for efficient precast construction, construction time reduction, and easy transportation. Mortar mixture with high strength and flowability was obtained from various case studies using silica fume and GGBS. Also, $1,200{\times}600{\times}150mm$ SRM and reinforced concrete (RC) panels were manufactured with reinforcing ratio of 2% and 4%. To verify structural performance of the SRM specimen, the basic material tests, free shrinkage test, and 3-point flexural test with a line loading were carried out. From the test results, it was determined that SRM specimens showed outstanding flexural capacity and ductility. However, the 4% reinforced SRM specimens must consider shear reinforcing to be used as a precast modular member.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.240-246
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• 1992

Preparation of soybean oil fatty acid methyl esters (soybean oil FAME) through the transesterification of soybean oil with alkaline catalyst was optimized in terms of contents of residual free fatty acids (FFA) in soybean oil FAME and yield of soybean oil FAME due to the inhibitory effect of FFA on sucrose polyesters synthesis. Soybean oil FAME and residual FFA were analyzed quantitatively by simultaneous gas chromatography on a fused silica capillary column after converting the FFA in soybean oil FAME to tert.-butyldimethylsilyl (TBDMS) derivatives. Transesterification of soybean oil was successfully performed with alkaline catalyst (NaOH, 95%), which resulted in 99.1% yield of soybean oil FAME and less than 0.1% residual FFA contents under the conditions such as $30^{\circ}C$, 20min. and 6:1 molar ratio of anhydrous methanol to soybean oil.

• Journal of fish pathology
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• v.20 no.2
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• pp.139-145
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• 2007

To decrease stress in eel (Anguilla japonica) during its culture or transportation, aspirin (ASA) known as analgesic, antiinflammatory and antithrombic agent was administrated by dipping or oral routes. Concentrations of aspirin (ASA) and salicylic acid (SA) in eel plasma were simultaneously measured by a high performance liquid chromatography (HPLC). The plasma was acidified with 0.2 M HCl and 0.2 M orthophosphoric acid, and mixed with acetonitrile. ASA and SA extracted with acetonitrile were analyzed by the HPLC equipped with reversed phase Novapak C18 column (4 ㎛ silica, 150×4 mm) and UV detector(237 nm). The mobile phase consisted of 740 ㎖ water, 900 ㎕ orthophosphoric acid (85%) and 180 ㎖ acetonitrile. The retention times of ASA, SA and 2-methylbenzoic acid(MBA) were 4.8 min, 8.4 min and 11.5 min, respectively. The limit of quantification was 0.01 ㎍/㎖ for SA and 0.05 ㎍/㎖ for ASA. The mean recovery from eel plasma was 70.8～99.6% for ASA and 95.2～100.3% for SA. This HPLC method was applied to analyze ASA and SA of eel plasma after either dipping in a concentration of 20 ppm or feeding the feed supplemented with 50 ㎎/kg BW. Only SA was detected in eel plasma after the administration of ASA by dipping or oral routes because the drug was quickly decomposed into SA in eel plasma. The amount of SA in eel plasma reached the highest value at 3hr in dipping and 7 days in oral administration. When the ASA-administrated eel were kept in ASA free aquaria, 0.02-0.03 ㎍/㎖ of SA were detected 48 hr after the administration in both routes.

• Journal of the Korean Electrochemical Society
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• v.4 no.1
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• pp.6-9
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• 2001

[ $SiO_2$ ] effect on the electrochemical properties of polymeric gel electrolytes(PGEs) reinforced with glass fiber cloth(GFC) was investigated . PGEs were composed of polyacrylronitrile(PAN), poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)), $LiClO_4$ and three kind of plasticizer(ethylene carbonate, dietyl carbonate, propylene carbonate). $SiO_2$ was added to PGEs in the weight fraction of 10, 20, $30\%$ respectively. PGEs containing $SiO_2$ showed conductivity of over $10^{-3}S/cm\;at\;23^{\circ}C$ and electrochemical stability window to 4.8V. In the impedance spectra of the cells, which were constructed by lithium metals as electrodes, interfacial resistance increased due to growth of passivation layer during storage time and remarkable difference was not observed with content of $SiO_2$. In the impedance spectra of the lithium ion polymer batteries consisted of $LiClO_2$ and mesophase pitch-based carbon fiber(MCF), ohmic cell resistance of $SiO_2-free$ PGE was changed continuously with number of cycle, but those of $SiO_2-dispersed$ PGEs were not. Discharge capacity of the PGE containing $20wt\%\;SiO_2$ showed 132 mAh/g at 0.2C rate and $85\%$ of discharge capacity was retained at 2C rate.

• Journal of Life Science
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• v.25 no.11
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• pp.1298-1303
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• 2015

Machilus thunbergii (Lauraceae) is an evergreen tree cultivated in Korea and Japan. M. thunbergii has long been used as a traditional medicine in Korea, China, and Japan to treat various diseases, including edema, abdominal pain, and abdominal distension. In this study, dried stem bark of M. thunbergii extracted in methanol and extract was partitioned into n-hexane, CHCl₃, and BuOH. The CHCl₃-soluble extracts chromatographed on silica gel column using a CHCl₃/acetone and n-hexane/EtOAc mixture to afford Compound 1 and 2. Two dibenzylbutane lignans, macelignan (1) and meso-dihydroguaiaretic acid (2), were isolated from the CHCl₃-soluble extract of M. thunbergii stem bark. The structures of 1 and 2 were determined by ¹H- and ¹³C-NMR spectroscopic data analyses and a comparison with literature data. The tyrosinase inhibitory activity of the isolated compounds was evaluated. Among these compounds, Compound 2 strongly inhibited the monophenolase (IC₅₀=10.2 μM) activity of tyrosinase. A kinetic analysis showed that Compound 2 was a competitive inhibitor. The apparent inhibition constant (K_i) for Compound 2 binding to free enzyme was 4.8 μM. Based on these results, it can be concluded that meso-dihydroguaiaretic acid (2) is a potential candidate for the treatment of melanin biosynthesis-related skin diseases.

• Journal of dental hygiene science
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• v.13 no.1
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• pp.83-90
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• 2013

The aim of this study was to evaluate the abrasive effect and cleaning power of toothpaste containing tetrasodium pyrophosphate and cellulose. The relative dentin abrasivity, cleaning power by modified Stookey method, dentin abrasivity of brushing after Cola treatment and consumer survey were investigated with control toothpaste containing dental type silica as an abrasive. The results obtained were as follows: 1. Experimental toothpaste hardly influenced dentin abrasivity, but control toothpaste had an effect on dentin abrasivity significantly (p<0.05). 2. There was no significant difference in cleaning power between experimental and control toothpaste (p>0.05). 3. Experimental toothpaste hardly influenced dentin abrasivity, despite 100 or 1,000 times of brushing after Cola treatment, but control toothpaste showed a big increase in dentin abrasivity as the number of brushing has been increased (p<0.05). 4. According to the consumer survey results, there was no difference between control and experimental toothpaste in the satisfaction rate of refreshing sensation, the satisfaction rate of the lasting effect of refreshing sensation and the overall satisfaction rate of the toothpaste (p>0.05). These results showed a possibility to make abrasive free toothpaste having cleaning power without dentin abrasivity.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.27 no.1
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• pp.133-150
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• 2001

자유라디칼은 반응성이 커서 세포의 구성 물질인 단백질, 지질, 당, DNA등과 반응하여 세포 및 조직을 손상시킴으로서 노화를 가져온다. 이러한 자유라디칼들은 자외선, 일반 대사, 스트레스, 질병, 흡연 등에 의해 생성되고 특히, 활성 산소 종인 hydroxyl radical, superoxide radical, lipid peroxide radical등은 피부 노화를 발생시키는 원인이 된다. 따라서 본 연구에서는 한방 식물로부터 유해한 활성 산소종을 소거하는 활성을 가진 물질을 기 위해 1차 스크리닝 하였고, 이중 육두구, 관중, 초두구, 빈랑, 금은화, 포공영, 우롱차, 황금, 녹차 추출물이 효과가 높게 나타났으며, 그중 초두구와 빈랑 90% 메탄올 추출물에서 가장 우수한 소거 활성을 나타냄으로써 이 추출물에 대하여 자유라디칼 소거 활성에 대하여 여러 가지 생물학적 활성을 조사하였다. 초두구와 빈랑추출물에 대한 hydroxyl radical, superoxide radical, lipid peroxide radical을 소거하는 활성을 핵산, 클로로포름, 에틸아세테이트, 물층으로 분획하여 조사한 결과 에틸아세테이트층에서 가장 우수한 활성을 보였다. 에틸아세테이트 분획에 대한 lipid peroxide radical 소거에 있어서 빈랑 추출물이 $IC_{50}$/ 값 50 $\mu\textrm{g}$/ml, 초두구 추출물은 $IC_{50}$/ 값 59 $\mu\textrm{g}$/ml로서 기준물질로 사용되는 vitamic C (120 $\mu\textrm{g}$/ml)나 butylated hydroxyl toluene (80 $\mu\textrm{g}$/ml) 보다 더 우수한 소거 효과를 보여주었고, hydroxyl radical을 소거하는 능력은 25 $\mu\textrm{g}$/ml와 150 $\mu\textrm{g}$/ml로 hydroxyl radical의 소거 능이 좋은 vitamin C (180 $\mu\textrm{g}$/ml) 보다 뛰어난 소거 활성을 나타내었다. Superoxide radical을 소거하는 효과는 초두구 추출물의 $IC_{50}$/ 값 10 $\mu\textrm{g}$/ml, 빈랑 추출물이 15 $\mu\textrm{g}$/ml을 나타냈고, 이는 기준 물질인 vitamin C (35 $\mu\textrm{g}$/ml)보다 좋은 소거 활성을 보여주었으며, gallic acid 9 $\mu\textrm{g}$/ml과 유사한 효과를 나타내었다. 사람 섬유아세포를 배양하여 hydroxyl radical과 superoxide radical를 발생시킨 후 초두구와 빈랑 추출물의 세포 보호 효과를 실험한 결과 25 $\mu\textrm{g}$/ml의 농도로 처리하였을 때 각각 85% 이상의 우수한 세포 보호 효과를 나타내었다. 초두구로부터는 자유라디칼 소거 활성이 있는 물질을 분리하기 위하여 분획한 후 가장 높은 소거 활성을 보인 에틸아세테이트 층에 대하여 silica column chromatography, preparative TLC를 수행하였다. 초두구로부터 분리된 물질은 HPLC를 이용한 분리에서 phenol성 물질인 gallic acid와 동일한 retention time을 보여줌으로써 초두구로부터 분리된 물질은 gallic acid와 유사한 phenol성 물질이거나 그의 유도체일 것으로 추측된다. 따라서, 초두구와 빈랑 추출물은 피부 노화의 주요인이 되고 있는 lipid radical, hydroxyl radical, superoxide radical을 소거하는 활성이 뛰어나 자유라디칼에 의하여 발생되는 피부노화를 방지할수 있는 물질로서의 효과가 기대된다.가 기대된다.

• The Journal of Advanced Prosthodontics
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• v.10 no.5
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• pp.374-380
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• 2018

PURPOSE. The effect of silica-based glass-ceramic liners on the tensile bond strength between zirconia and resin-based luting agent was evaluated and compared with the effect of 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing primers. MATERIALS AND METHODS. Titanium abutments and zirconia crowns (n = 60) were fabricated, and the adhesive surfaces of the specimens were treated by airborne-particle abrasion. The specimens were divided into 5 groups based on surface treatment: a control group, 2 primer groups (MP: Monobond Plus; ZP: Z Prime Plus), and 2 liner groups (PL: P-containing Liner; PFL: P-free Liner). All specimens were cemented with self-adhesive resin-based luting agent. After 24-hour water storage and thermocycling (5,000 cycles, $5^{\circ}C/55^{\circ}C$), the tensile bond strength was measured using a universal testing machine. Failure mode analysis and elemental analysis on the bonding interface were performed. The data were analyzed using Kruskal-Wallis test, Dunn's post hoc test, and Fisher's exact test. RESULTS. The liner groups and primer groups showed significantly higher tensile bond strengths than that of the control group (P<.05). PFL showed a significantly higher tensile bond strength than the primer groups (P<.05). The percentage of mixed failure was higher in the primer groups than in the control group (P<.001), and all the specimens showed mixed failure in the liner groups (P<.001). A chemical reaction area was observed at the bonding interface between zirconia and liner. CONCLUSION. The application of liner significantly increased the tensile bond strength between zirconia and resin-based luting agent. PFL was more effective than MDP-containing primers in improving the tensile bond strength with the resin-based luting agent.

• Natural Product Sciences
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• v.5 no.3
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• pp.113-120
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• 1999

Nitric oxide (NO) is a free radical synthesized from L-arginine by nitric oxide synthase (NOS). It is believed that NO is an important mediator in numerous physiological and inflammatory responses. Particularly, a large amount of NO released from the inducible nitric oxide synthase (iNOS) is mostly associated with inflammatory processes. Overproduction of NO in these processes including sepsis and autoimmune diseases can have deleterious consequences and pathophysiologic relevance. Therefore, for the discovery of new inhibitory agents against iNOS activity, we have evaluated about 100 kinds of natural products after partition into three layers (n-hexane, ethyl acetate and aqueous) from 100% methanol extracts to study inhibitory effects on iNOS activity induced by lipopolysaccharide (LPS) in RAW264.7 cells culture system. As a positive control, curcumin, which is known as an anti-tumor promoter, anti-inflammatory agent as an iNOS inhibitor, was used and showed the dose-dependent inhibitory effect $(IC_{50},\;2.5\;{\mu}g/ml)$. Among tested fractions, the n-hexane fraction of Cimicifuga heracleifolia $(IC_{50}:\;9.65\;{\mu}g/ml)$, Forsythiae fructus $(IC_{50}:\;6.36\;{\mu}g/ml)$, Saposhnikovia divaricata $(IC_{50}:\;5.92\;{\mu}g/ml)$, and the ethyl acetate fraction of Chrysanthemum sibiricum $(IC_{50}:\;2.56\;{\mu}g/ml)$, Gastrodia elata $(IC_{50}:\;3.46\;{\mu}g/ml)$, and the aqueous fraction of Dianthus chinensis $(IC_{50}:\;6.73\;{\mu}g/ml)$, Euonymus alatus $(IC_{50}:\;6.78\;{\mu}g/ml)$, Mechania urticifoloria $(IC_{50}:\;8.01\;{\mu}g/ml)$ showed strong inhibitory activity against LPS-stimulated iNOS. Especially, the ethyl acetate fraction of Chrysanthemum sibiricum $(IC_{50}:\;2.56\;{\mu}g/ml)$, which exhibited the strongest inhibition against iNOS, was fractionated with silica-gel column chromatography. These subfractions exhibited dose-dependent inhibition against iNOS activity in the range of $2.59-5.6\;{\mu}g/ml$ except for fraction No. 3, 4, 5, 6, 8, 9, and 16. Our study shows that Chrysanthemum sibiricum has the strongest inhibitory effect against iNOS activity and has similar effect to curcumin. Therefore, further studies for the identification of active principles from Chrysanthemum sibiricum and investigation for the mechanism of the inhibition of iNOS by active principles will be performed.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.255-260
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• 1992

A procedure for spectrophotometric determination of traces of phosphorus(P) in high-purity trichlorosilane(TCS) is proposed using an adsorptive separation. $PCl_3$, which is a dominant P impurity within TCS, is first oxidized by oxygen to a stable form as $POCl_3$. $AlCl_3$ is selected as an adsorbent which forms a thermally stable complex with $POCl_3$ in TCS and can be well dissolved in aqueous ethanol solution. The proposed adsorptive separation method is free from the formation of silica gel and gas bubbles during the colorimetric analysis of TCS. The method reveals that the P concentration in a semiconductor-grade TCS is 5.32 ${\mi}g/l$ within the standard deviation of ${\pm}$ 17%. On the other hand, the P concentration of the purified TCS which is separated from the $AlCl_3$${\cdot}$$POCl_3$ complex is reduced to be less than 0.15 ${\mi}g/l$, showing the efficient applicability of $AlCl_3$ to the wet chemical analysis. The proposed method is also tested to verify the effectiveness of other well-known adsorbents.