• Structural Engineering and Mechanics
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• 제57권3호
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• pp.507-528
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• 2016

Reduced beam section (RBS) moment resisting connections are among the most economical and practical rigid steel connections developed in the aftermath of the 1994 Northridge and the 1995 Kobe earthquakes. Although the performance of RBS connection has been widely studied, this connection has not been subject to in the skewed conditions. In this study, the seismic performance of dogbone connection was investigated at different angles. The Commercial ABAQUS software was used to simulate the samples. The numerical results are first compared with experimental results to verify the accuracy. Nonlinear static analysis with von Mises yield criterion materials and the finite elements method were used to analyze the behavior of the samples The selected Hardening Strain of materials at cyclic loading and monotonic loading were kinematics and isotropic respectively The results show that in addition to reverse twisting of columns, change in beam angle relative to the central axis of the column has little impact on hysteresis response of samples. Any increase in the angle, leads to increased non-elastic resistance. As for Weak panel zone, with increase of the angle between the beam and the column, the initial submission will take place at a later time and at a larger rotation angle in the panel zone and this represents reduced amount of perpendicular force exerted on the column flange. In balanced and strong panel zones, with increase in the angle between the beam and the central axis of the column, the reduced beam section (RBS), reaches the failure limit faster and at a lower rotation angle. In connection of skewed beam, balanced panel zone, due to its good performance in disposition of plasticity process away from connection points and high energy absorption, is the best choice for panel zone. The ratio of maximum moment developed on the column was found to be within 0.84 to 1 plastic anchor point, which shows prevention of brittle fracture in connections.

• 대한원격탐사학회지
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• 제29권2호
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• pp.235-241
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• 2013

본 연구에서는 2007년과 2008년 봄 기간 중 동북아 지역의 주요 메가시티 중 하나인 서울에서 Multi-Axis Differential Optical Absorption Spectroscopy(MAX-DOAS) 관측을 처음으로 수행하고, 측정된 스펙트럼의 차등흡수분광 분석을 통하여 이산화질소의 수직층적분농도를 산출 하였다. MAX-DOAS로부터 산출된 값들과 Ozone Monitoring Instrument(OMI) 위성센서로부터 산출된 서울지역의 대류권 이산화질소 산출물과의 비교를 통하여 OMI로부터 산출된 이산화질소 수직층적분농도의 상대적 정확성 규명을 수행하였다. MAX-DOAS로부터 산출된 이산화질소는 $1.0{\times}10^{15}molec{\cdot}cm^{-2}$에서 $6.0{\times}10^{16}molec{\cdot}cm^{-2}$ 정도 분포로 보였으며, OMI의 대류권 수직층적분농도는 $1.0{\times}10^{15}molec{\cdot}cm^{-2}$에서 $7.0{\times}10^{16}molec{\cdot}cm^{-2}$ 정도 분포로 보였다. 관측전체기간인 6개월 동안 두 관측결과의 상관관계를 보여주는 상관계수(R)는 0.73으로 비교적 양호한 상관 관계를 보였다. 구름이 없는 기간 동안에는 상관계수가 0.85로 두 관측결과의 높은 상관관계는 확인 할 수 있었다. 두 센서의 산출알고리즘 모두 구름이 있을 경우 대기질량인자의 계산에 있어서 높은 불확실성으로 인해 이산화질소농도의 산출오차가 높은 것으로 판단된다.

• 대한원격탐사학회지
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• 제22권2호
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• pp.141-151
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• 2006

태양광을 광원으로 하고 천정방향을 포함한 다양한 고도각을 이용하는 자외선/가시광선영역에서의 흡수분광학이 최근에 지상용 대기원격 측정에 개발되어오고 있다. 이를 이용하여 지표부근에 존재하는 대기 미량 물질의 공간적 분포가 유추될 수 있다. 대기질 측정기술 중 하나인 MAX-DOAS (Multi-axis Differential Optical Absorption Spectroscopy) 기술은 광원으로서 태양산란광을 이용하고, 다양한 고도각에서 태양산란광을 기록하고 분석을 통하여 대기 중 미량 물질을 측정한다. 광주과학기술원 환경모니터링 신기술 연구센터에서 개발된 MAX-DOAS 시스템은 9004년 1월, 5월, 10월에 각각 도시대기, 화산플룸, 화력발전소 플룸의 측정에 적용되었다. 각각의 경우에 $SO_2,\;NO_2,\;BrO,\;O_4$를 정량분석하기 위하여 기록된 MAX-DOAS 스펙트럼은 자외선/가시광선 영역에서의 고유 흡수스펙트럼을 이용한 DOAS 기술을 이용하여 분석 되었다. 그 결과는 Slant Column Density (SCD)로 표현되었다. 플룸 측정의 경우에서는 플룸 속에 포함된 $NO_2,\;SO_2$의 공간적 분포를 파악하기 위하여 플룸의 진행방향과 수직적인 방향에서 MAX-DOAS 스캔이 이루어졌다. 이를 통하여 얻은 단면적을 토대로 $SO_2,\;NO_2$ 농도가 계산되었다. 화산플룸에서 $SO_2$는 580ppbv, 화력발전소 플룸에서 $NO_2$는 337ppbv, $SO_2$는 227ppbv 로 계산되었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.509-511
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• 2000

An antifungal antibiotic was produced from Bacillus sp. YJ-63, and antibiotic was purified to a homogeneity by butanol extraction, Silica-gel column chromatography, Sephadex LH-20 gel filtration column chromatography and HPLC. The purified antibiotic showed one spot on Thin Layer Chromatography, which was negative to ninhydrin and positive to iodine. This finding indicated that the antibiotic was a cyclopeptide structure. UV absorption spectrum of the antibiotic in methanol was maximal at 277 nm, which corresponded to the spectrum for all of the Iturin antibiotic. The antibiotic was stable up to $121^{cdot}C$ and in the range of pH $3.O{\sim}l2.0$ with a stable of ${\alpha}-amino$ acid and ${beta}-amino$ acid, and showed high activity for fungi and yeasts,

• Journal of Microbiology and Biotechnology
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• 제2권1호
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• pp.41-45
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• 1992

Shikonin production was examined in a bubble column bioreactor system with the hairy roots of Lithosphermum erythrorhizon. The volumetric productivity was higher than those obtained from other reactor configurations with free or immobilized cells of the same cell line. The productivities of the bubble column reactor, with and without a product absorption trap, were 7.4 and 4.5 mg of shikonin/l/d, respectively. This indicated the importance of the product removal in the design and operation of the shikonin production system with hairy root culture.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.251-252
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• 2006

A development of surface acoustic wave gas sensor to detecting volatile gas has been observed by monitoring output signal as function of time onto the network analyzer. The SAW sensor with a center frequency of 200MHz was fabricated on $42^{\circ}$ S-T Quartz substrates. Using the gas chromatography column has been selectivity. Experimental results, which show the phase change of output signal under the absorption of volatile gas onto sensors, were presented. The proposed sensor has the properties of high sensitivity compare to the conventional SAW gas sensor and chemical selectivity. Thus, it is thought these results are applicable for use in sensor array of an high performance electronic nose system.

• Journal of Applied Biological Chemistry
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• 제43권2호
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• pp.94-100
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• 2000

An analytical method was developed to determine abamectin and milbemectin residues in apple, pear, and citrus using HPLC with ultraviolet absorption detection. Abamectin and milbemectin were extracted with methanol from apple, pear, and citrus samples. The extract was diluted with saline water and dichloromethane partition was followed to recover the compounds from the aqueous phase. Florisil column chromatography and aminopropyl solid-phase extraction were employed as cleanup methods to remove most of co-extractives from the sample extract. Reverse-phase HPLC using an octadecylsilyl column was successfully applied to separate and quantitate abamectin and milbemectin residues in sample extracts at the wavelength of 245 nm. Recoveries of abamectin and milbemectin from fortified samples ranged 80.4~90.3% and 90.9~96.8%, respectively. Relative standard deviations of the analytical method were less than 10% for both acaricides. Detection limit of the analytical method was 0.003 mg/kg sample for all the analytes. The proposed method was reproducible and sensitive enough to evaluate terminal residues of abamectin and milbemectin in apple, pear, and citrus.

• 한국식품영양학회지
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• 제21권2호
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• pp.143-147
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• 2008

To develop a new anti-wrinkle agent from medicinal plants, this study investigated the optimal conditions for extracting elastase inhibitor from Rheum undulatum L. Maximal extraction occurred by using 70% methanol at $50^{\circ}C$ for 24 hr; the elastase inhibitory activity was 60.4%($IC_{50}:6.7{\times}10^3{\mu}g/m{\ell}$). Systematic solvent extraction, thin layer chromatography, silica gel column chromatography, Sephadex LH-20 column chromatography, and reverse-phase high performance liquid chromatography were used in the partial purification of the elastase inhibitor. The compound was soluble in dimethylsulfoxide, methanol, and ethanol, and had maximum absorption spectra at 231.5 nm and 275.5 nm.

• Journal of Applied Biological Chemistry
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• 제42권4호
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• pp.191-196
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• 1999

A multiresidue analytical method was developed for eight acaricides including benzoximate, clofentezine, fenazaquin, fenothiocarb, fenpyroximate, hexythiazox, pyridaben, and tebufenpyrad in four major fruits using high-performance liquid chromatography (HPLC). All the confounds were extracted with acetone from apple, pear, grape, and citrus samples. The extract was diluted with saline water, and n-heaxane partition was followed to recover the acaricides. Florisil column chromatography was employed to further purify the sample extract. HPLC with ultraviolet absorption detection, using an octadecylsilyl column under the isocratic mobile phase of acetonitrile/water mixture, was successfully applied to separate and quantitate all the compounds in the purified extract. Recoveries of the eight acaricides from for fortified samples ranged 86.4~97.0%. Relative standard deviations of the analytical method were all less than 10%. Detection limits of the method were in the range of 0.02~0.05 mg/kg. The proposed method was reproducible and sensitive enough to evaluate the terminal residue of the eight acaricides in the fruit harvest.

• 한국환경농학회지
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• 제23권4호
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• pp.245-250
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• 2004

An analytical method was developed to determine monocrotophos residues in apple, citrus, and soil using high-performance liquid chromatography (HPLC) with ultraviolet absorption detection. Monocrotophos was extracted with acetone from apple, citrus and moist soil samples. The extract was concentrated, added with saline water, and subjected to n-hexane washing to remove nonpolar co-extractives. Dichloromethane partition was then followed to recover monocrotophos from the aqueous phase. Silica gel column chromatography was employed to further purify the extract prior to HPLC determination. Reverse-phase HPLC using an oct-adecylsilyl column was successfully applied to separate and quantitate the monocrotophos residue in sample extracts at the wavelength of 230 nm. Overall recoveries of monocrotophos from fortified samples averaged $95.3{\pm}2.1%$ (n=6), $970{\pm}0.7%$ (n=6), and $92.8{\pm}4.3%$ (n=12) for apple, citrus, and soil, respectively. The proposed method was quite reproducible and sensitive enough to replace the troublesome gas-liquid chromatographic analysis for monocrotophos residues.