• 복합신소재구조학회 논문집
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• 제3권4호
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• pp.27-37
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• 2012

The construction of a moment connection for a rectangular hollow section (RHS) column and a H-shaped beam is difficult because the RHS is a closed section. When a inner diaphragm is used for such a connection, in general, it is installed after cutting the HSS columns, which results in increased construction work. This paper suggests a new fabrication method to overcome such problems: An inner diaphragm is welded to inside a C-shaped section first, and then a column is fabricated by welding two C-shaped sections. This fabrication method is superior to a classic method in terms of constructibility. An experimental and a numerical study using Ansys 9.0 were performed in order to compare the strength of connections with respect to the presence of concrete, the corner shape of diaphragm, and the axis of loading. The experimental results including initial stiffness and ultimate loads are reported and the analytical results including load transfer mechanism, degree of stress concentration, and strain distribution are also reported.

• Structural Engineering and Mechanics
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• 제7권2호
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• pp.127-145
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• 1999

This paper deals with the development of an approach for evaluating the squash load and rigidity of unprotected concrete filled steel columns at elevated temperatures. The current approach of evaluating these properties is reviewed. It is shown that with a non-uniform temperature distribution, over the composite cross-section, the calculations for the squash load and rigidity are tedious in the current method. A simplified approach is proposed to evaluate the temperature distribution, squash load, and rigidity of composite columns. This approach is based on the model in Eurocode 4 and can conveniently be used to calculate the resistance to axial compression of a concrete filled steel column for any fire resistance time. The accuracy of the proposed approach is assessed by comparing the predicted strengths against the results of fire tests on concrete filled circular and square steel columns. The applicability of the proposed approach to a design situation is illustrated through a numerical example.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2008년도 공동학술대회
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• pp.137-140
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• 2008

2003년, 2006년과 2007년, 사할린 북동사면 $53^{\circ}56'\;N$, $143^{\circ}52'\;E$ to $54^{\circ}40'\;N$, $144^{\circ}32'\;E$ 지역에서 음향측심, side-scan sonar (SSS), 고해상도 스파커 탄성파 탐사를 포함한 다양한 주파수 대역의 음향탐사를 실시하였다. 높은 후방산란강도를 가진 약 130여개의 메탄분출구들이 해저면에 발달해 있는 SSS 영상도를 획득하였다. 음향측심탐사에서의 수층 가스분출구조와 탄성파탐사에서의 해저지층 가스기둥구조들이 이 해저면 구조들과 잘 부합하여 나타난다. 이런 메탄분출구조들은 북서 주향을 갖는 Lavrentiev 단층과 평행한 구조선을 따라 배열하는 것처럼 보인다.

• Steel and Composite Structures
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• 제33권4호
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• pp.489-507
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• 2019

In order to obtain high bearing capacity and good ductility simultaneously, a structural column with hybrid normal and high strength steel (HNHSS) welded box section has been developed. Residual stress is an important factor that can influence the behaviour of a structural member in steel structures. Accordingly, the magnitudes and distributions of residual stresses in HNHSS welded box sections were investigated experimentally using the sectioning method. In this study, the following four box sections were tested: one normal strength steel (NSS) section, one high strength steel (HSS) section, and two HNHSS sections. Based on the experimental data from previous studies and the test results of this study, the effects of the width-to-thickness ratio of plate, yield strength of plate, and the plate thickness of the residual stresses of welded box sections were investigated in detail. A unified residual stress model for NSS, HSS and HNHSS welded box sections was proposed, and the corresponding simplified prediction equations for the maximum tensile residual stress ratio (${\sigma}_{rt}/f_y$) and average compressive residual stress ratio (${\sigma}_{rc}/f_y$) in the model were quantitatively established. The predicted magnitudes and distributions of residual stresses for four tested sections in this study by using the proposed residual stress model were compared with the experimental results, and the feasibility of this proposed model was shown to be in good agreement.

• Steel and Composite Structures
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• 제26권5호
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• pp.583-594
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• 2018

Although a lot of experimental and analytical investigations have been carried out for steel bridge piers made of SS400 and SM490, the formulas available for SS400 and SM490 are not suitable for evaluating ultimate load and deformation capacities of steel bridge piers made of high strength steel (HSS) SM570. The effect of various parameters is investigated in this paper, including plate width-to-thickness ratio, column slenderness ratio and axial compression force ratio, on the ultimate load and deformation capacities of steel bridge box piers made of SM570 steel subjected to cyclic loading. The elasto-plastic behavior of the steel bridge piers under cyclic loads is simulated through plastic large deformation finite element analysis, in which a modified two-surface model (M2SM) including cyclic hardening is employed to trace the material nonlinearity. An extensive parametric study is conducted to study the influences of structural parameters on the ultimate load and deformation capacities. Based on these analytical investigations, new formulas for predicting ultimate load and deformation capacities of steel bridge piers made of SM570 are proposed. This study extends the ultimate load and deformation capacities evaluation of steel bridge piers from SS400, SM490 steels to SM570 steel, and provides some useful suggestions.

• Mass Spectrometry Letters
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• 제13권4호
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• pp.158-165
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• 2022

Many therapeutic class drugs such as beta-blocker, corticosteroids, NSAIDs, etc are prohibited substances in the horse racing industry. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology makes it possible to isolate drugs from interference, enables various drug analyses in complex biological samples due to its sensitive sensitivity, and has been successfully applied to doping control. In this paper, we describe a rapid and sensitive method based on solid-phase extraction (SPE) using solid phase cartridge and LC-MS/MS to screen for different class's 35 drug targets in equine plasma. Plasma samples were pretreated by SPE with the NEXUS cartridge consisted non-polar carbon resin and minimum buffer solvent. Chromatographic separation of the analytes was performed on ACQUITY HSS C18 column (2.1 × 150 mm, 1.8 ㎛). The elution gradient was conducted with 5 mM ammonium formate (pH 3.0) in distilled water and 0.1% formic acid in acetonitrile at a flow rate of 0.25 mL/min. The selected reaction monitoring (SRM) mode was used for drug screening with multiple transitions in the positive ionization mode. The specificity, limit of detection, recovery, and stability was evaluated for validation. The method was found to be sensitive and reproducible for drug screening. The method was applied to plasma sample analysis for the proficiency test from the Association of Racing Chemist.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2022년도 추계학술대회
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• pp.100-100
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• 2022

Hovenia dulcis is a herbal plant, which belongs to the Rhamnaceae family and is a native of Japan, China and Korea. Its fruit stalk is called 'Jiguja' in Korea. It has been traditionally used as a medicinal plant in East Asia. It was reported to have detoxification effects on alcohol poisoning, and antioxidant, antidiabetic etc. Sample of 5 g was extracted with 50 mL of 70% EtOH. The supernatant was filtered by 0.45 ㎛ membrane filter before analysis. The UPLC system was performed on Waters alliance UPLC HSS T3 column (2.1 × 100 mm, 1.7 ㎛) with a UV detector. The gradient system was a binary eluent of 0.1% formic acid in water(A) and 0.1% formic acid in acetonitrile(B) with gradient conditions as follows: Initial, 10% B; 1 min, 10% B; 4 min, 20% B; 10 min, 25% B; 12 min, 30% B; 14 min, 90% B; 17 min, 90% B; flow rate of 0.2 mL/min. The samples were injected by 2 µL and were detected at UV 355 nm. As a result of analysis, chromatographic patterns appeared in two cases: samples analyzed for ampelopsin and myricetin, and samples analyzed for taxifolin and quercetin. Among the four compounds, the largest regional difference was found to be taxifolin.

• 한국식품과학회지
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• 제47권1호
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• pp.1-5
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• 2015

본 연구에서는 UPLC를 이용하여 11종 카로티노이드(neoxanthin, capsorubin, violaxanthin, capsanthin, zeaxanthin, lutein, ${\alpha}$-cryptoxanthin, ${\beta}$-cryptoxanthin, lycopene, ${\alpha}$-carotene, ${\beta}$-carotene)를 30분 내에 분석할 수 있는 방법을 확립하였으며, 이를 이용하여 다양한 색과 품종의 파프리카 내의 카로티노이드를 정량 분석하였다. 분석에는 HSS T3 컬럼과 acetonitrile:methanol:methylene chloride 혼합 용매와 증류수의 이동상을 이용하였으며, 개발한 조건 하에서 10종 카로티노이드를 잘 분리할 수 있었다. Capsanthin에 대한 검량선은 $1-200{\mu}g/mL$ 농도범위에서 상관계수($R^2$) 0.9998의 높은 직선성을 나타내었고 각각 2.4, $7.2{\mu}g/mL$의 검출한계와 정량 한계를 나타내었다. 일내 RSD값은 1.57-3.09%, 일간 RSD값은 1.98-3.83%를 나타냈으며, 회수율은 일내와 일간에서 각각 91.86-94.98, 98.10-99.87%의 값을 나타내어 분석에 적합함을 알 수 있었다. 이후 붉은색 파프리카 3종(레드마운틴, 바이런, 시로코), 주황색 파프리카 1종(오렌지프로), 노란색 파프리카 2종(피에스타, 볼란테), 녹색 파프리카 2종(레드마운틴, 바이런)의 카로티노이드 정량 분석을 실시하여 본 연구에서 제시한 카로티노이드의 분석 조건이 다양한 색상의 파프리카를 동시에 분석할 수 있는 방법임을 확인하였다. 본 연구에서의 분석 조건을 이용하여 파프리카 이외에도 다양한 카로티노이드 함유 식품의 정량 분석을 보다 정확하고 신속하게 수행할 수 있을 것으로 판단된다.

• Natural Product Sciences
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• 제26권1호
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• pp.64-70
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• 2020

Citrus junos seeds (CS) have been traditionally used for the treatment of cancer and neuralgia. They are also used to manufacture edible oil and cosmetic perfume. A large amount of CS shells without oil (CSS) are discarded after the oil in CS is used as foods or herbal remedy. To efficiently utilize CSS as a by-products, it needs to be studied through chemical analysis. Therefore, we developed an ultra-performance liquid chromatography (UPLC)-diode array detection (DAD) method for simultaneous determination and quantitative analysis of five components (two flavonoids and threes limonoids) in CSS. A Waters Acquity UPLC HSS T3 column C18 (2.1 × 100 mm, 1.8 ㎛) was used for this separation. It was maintained at 40 ℃. The mobile phase used for the analysis was distilled water and acetonitrile with gradient elution. To identify the quantity of the five components, a mass spectrometer (MS) with an electrospray ionization (ESI) source was used. The regression equation showed great linearity, with correlation coefficient ≥ 0.9912. Limits of detection (LOD) and limits of quantification (LOQ) of the five compounds were 0.09 - 0.13 and 0.26 - 0.38 ㎍/mL, respectively. Recoveries of extraction ranged from 97.45% to 101.91%. Relative standard deviation (RSD) values of intra- and inter-day precision were 0.06 - 1.15% and 0.19 - 0.25%, respectively. This UPLC-DAD method can be validated to simultaneously analyze quantities of marker flavonoids and limonoids in CSS.

• Natural Product Sciences
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• 제18권3호
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• pp.158-165
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• 2012

A UPLC method for the simultaneous determination of seven compounds was established for the quality control in H. cordata. The UPLC was performed on a $C_{18}$ HSS T3 $2.1{\times}100$ mm, 1.8 ${\mu}m$ column during a 13 minute gradient elution of 0.2% aqueous acetic acid and acetonitrile with the flow rate of 0.2 mL/min at $30^{\circ}C$. The UPLC method was validated according to the ICH guideline of analytical procedures with respect to precision, accuracy, and linearity. The limit of determination and quantitation for the seven compounds were 0.01-0.09 and 0.03-0.28 ${\mu}g/mL$, respectively. The calibration curves of all seven compounds showed good linearity ($r^2$ > 0.999). The intra-day and inter-day the RSD values used to evaluate the precision of analysis were less than 0.9%. The recoveries of quantified compounds ranged from 98.63 to 103.85%. The developed UPLC method was found to be effective, convenient and sensitivity for quantitative analysis of seven compounds in H. cordata. This work could be provided a baseline source for quality control of H. cordata.