• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.568-571
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• 2008

The computation of moving interface by the level set method typically requires reinitializations of level set function. An inaccurate estimation of level set function ${\phi}$ results in incorrect free-surface capturing and thus errors such as mass gain/loss. Therefore, accurate and robust reinitialization process is essential to the free-surface flows. In the present paper, we pursue further development of the reinitialization process, which evaluates directly level set function ${\phi}$ using a normal vector in the interface without solving the re-distancing equation of hyperbolic type. The Taylor-Galerkin approximation and P1P1splitting FEM are adopted to discretize advection equation of the level set function and the Navier-Stokes equation, respectively. Advection equation of free surface and re-initialization process are validated with benchmark problems, i.e., a broken dam flow and time-reversed single vortex flow. The simulation results are in good agreement with the existing results.

• 한국수산과학회지
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• 제47권2호
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• pp.129-134
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• 2014

Two neuropeptides were purified from the acidified tube feet extract of the starfish Asterias amurensis by C18 reversed phase and size-exclusion high-performance liquid chromatography (HPLC). The tube feet extract and the purified peptides (AST-I and AST-II) showed potent contractile activity on dorsal retractor muscle (DRM) of the starfish Asterina pectinifera and intestine (smooth muscle) of the panther puffer Takifugu pardalis. Treatment of the purified peptides with dithiothreitol (DTT) for 60 min at $37^{\circ}C$ significantly altered their retention times, suggesting that these compounds contained disulfide bonds. The molecular weights of AST-I and AST-II were determined to be 2064.2 Da and 6137.2 Da, respectively, by MALDI-TOF mass spectrometry.

• 한국식품영양과학회지
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• 제24권4호
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• pp.578-581
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• 1995

참축나무잎 flavonoid들을 column chromatography로서 분리하여 HPLC를 이용하여 화합물을 분석하고 주성분인 quercitrin 및 afzelin을 계절별로 채집, 함유량을 정량하였다. 참죽나무잎 중의 flavonoid는 주 성분인 quercitrin은 채집 초기인 5월을 시작으로 증가되다가 7월과 8월에 7.94, 8.89%로서 최대치에 달하며 9월 부터 감소하는 경향을 보였다. Afzelin의 함유량도 6월에 0.12%로서 최고조에 달하며 7, 8월에 0.09, 0.08%로 많은 양을 함유하다가 가을철인 9월 부터 점점 감소함을 관찰할 수 있다. 따라서 참죽나무잎의 flavonoid 함유량은 여름에 최고조로 달하며 동일나무에서 그의 함량은 일정하지 않고 계절에 따라 변화함을 관찰할 수 있다.

• 분석과학
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• 제5권3호
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• pp.333-338
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• 1992

녹차 중 탄닌성분들인 에피갈로카테킨, 에피갈로카테킨 갈레이트는 세파덱스 LH-20 컬럼에서 물-아세톤의 혼합용리에 의하여 신속하게 분리되어 용출하였다. 용출액은 280nm에서 흡광도의 변화를 측정한 결과 4개의 분획으로 검출되었다. 각 분획을 그대로 고속원자충격 질량분석장치에 도입하여 탄닌성분들을 동정할 수 있었다. 에피갈로카테킨, 에피갈로카테민 갈레이트는 역상 HPLC에서 용출된 피크면적으로 계산한 결과, 70% 이상의 높은 수율로 얻을 수 있었다. 본 방법에 의하여 보고된 방법들보다 탄닌성분들을 신속하게 동정할 수 있고, 고순도로 얻을 수 있었다.

• Biomolecules & Therapeutics
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• 제16권1호
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• pp.21-27
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• 2008

Clotrimazole (CLT), a potent antifungal drug, is known to inhibit tumor cell proliferation. In the present study, we examined the role of intracellular $Ca^{2+}$ in CLT-induced cell cycle arrest of colon adenocarcinoma HT29 cells. CLT inhibited growth of HT29 cells in a concentration-dependent manner, which was associated with inhibition of cell cycle progression at the G(1)-S phase transition and an increase in the expression of cell cycle inhibitor proteins p27 and p53. CLT also suppressed the $Ca^{2+}$ overload by A23187, a calcium ionophore, suggesting its role in modulation of intracellular $Ca^{2+}$ concentration in HT29 cells. The simultaneous application of CLT and A23187 with addition of $CaCl_2$ (1mM) to the medium significantly reversed CLT-induced p27 and p53 protein level increase and growth suppression. Our results suggest that CLT induces cell cycle arrest of colon adenocarcinoma HT29 cells via induction of p27 and p53, which may, at least in part, be mediated by alteration of intracellular $Ca^{2+}$ level.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.604-609
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• 2002

In development of an advanced bicycle simulator, the investigation of the interactions between bicycle and rider during cycling is paramount important because bicycle is a two-wheeled human-powered vehicle. Tn this work, the tilt stability. among various interactions, of bicycling is investigated experimentally, In the experiments, the tilt angles of the bicycle, riders body and head are measured, as the riding p;1th and the speed are varied. Subjects are asked to ride along four typical paths on rigid flat ground : the straight, C-curved, S-curved and circle paths. The results from extensive experiments with different subjects can be summarized as : 1) The tilt angles of bicycle and rider are almost out of phase during pedaling along the straight path. 2) The bicycle tilt angle is nearly proportional to the square of bicycle speed for the straight and curved paths, and to the curvature for the curved paths. The head tilt angle is the biggest and the body tilt angle is the smallest for the straight path, but the tendency is reversed for the C-curved path. During the curve maneuvering, the rider's head tends to tilt by less than 40% of the bicycle tilt angle.

• 한국식품조리과학회지
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• 제30권5호
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• pp.573-578
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• 2014

The objective of this study was to investigate the antioxidant activities and anthocyanin profiles in the anthocyanin rich fraction (ARFAM) of Aronia melanocarpa, which are considered functional substances and are available as food coloring agents in Korea. Anthocyanins were identified by reversed-phase C18 column chromatography and HPLC-DAD-ESI/MS analysis. The antioxidative activity of the acidic ethanol extract (AME) and the anthocyanin-rich fraction (ARFAM) was determined by scavenging of the diphenylpicrylhydrazyl (DPPH) radical, the hydroxy radical, and the superoxide anion in addition to reducing power using a commercial antioxidant as a reference.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.123-123
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• 1998

A number of uracil derivatives have been developed as anti-AIDS drugs having a mechanism of inhibiting cellular reverse transcriptase. A simple and rapid assay technique for recently synthesized KR-V analogues was developed using a high-performance liquid chromatography, and oral pharmacokinetics was examined for assessing their oral bioavailabilites. Plasma samples were analyzed by reversed-phase HPLC using an ODS column with an ultraviolet detection system. All the analogues were eluted within 12 min and the LOQ was 15-30 ng/$m\ell$. The extraction recoveries were higher than 85%, except KR-V1039, 1068 and 1720 having ester group. This chromatic method was well applied to the kinetic studies for KR-V analogues. Among 16 analogues tested in the present work, the 6 compounds including KR-V1123, 1122, 1784, 1783, 1736 and 1700 were found to be bioavailable for oral administration to rats.

• 한국식품영양학회지
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• 제19권3호
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• pp.267-270
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• 2006

한국에서 옻나무(Rhus verniciflua)는 전통적으로 약용식물로 오랫동안 사용되어 왔다. 민간요법으로 위장병 치료를 목적으로 옻나무껍질을 닭과 함께 넣어 끊여서 백숙형태로 옻닭으로 식용하였다. 그러나 일부 사람에게서 피부발진이 발생하는 극심한 알러지 반응을 일으키는 나무로 인식되어 왔다. 알러지 발생을 유발시키는 우루시올은 옻나무의 수지상 옻칠 액의 주성분이다. 이 성분의 화학적 구조는 카테친의 기본구조에 알킬기인 불포화지방산(C$_{15}_{\sim}_{17}$)이 곁사슬로 붙어 있다. 곁사슬의 불포화지방산 성분은 칠기의 고분자화 및 경화과정에 중요한 역할을 하며, 옻칠공예품의 색상 및 품질에 커다란 영향을 미친다. 한국에서 생산되는 원주산 옻칠액의 우루시올성분은 역상 컬럼을 사용하여 고속 액체 크로마토그라피 (HPLC)법으로 정제하여 ESI(-), FAB(+) 질량분석기(MS)로 분석한 결과 분자량 340인 Hetadecatetetraenyl catechol 이었다.

• Mass Spectrometry Letters
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• 제2권1호
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• pp.8-11
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• 2011

Two types of glycerolipids [monoacylglycerols (MAG) and cyclitols] were isolated by reversed phase high-performance liquid chromatography from the methanol extracts of a marine sponge, and analyzed by fast atom bombardment mass spectrometry (FAB-MS) in positive-ion mode. FAB mass spectra of these compounds yielded protonated molecules $[M + H]^+$ and abundant sodiated molecules $[M + Na]^+$ from a mixture of 3-nitrobenzyl alcohol and NaI. The structures of these compounds were elucidated by FAB-collisional-induced dissociation (CID)-tandem mass spectrometry. We carried out collision-indused dissociation (CID) of these lipids in B/E-linked scan mode. The CID B/E-linked scan of $[M + H]^+$ and $[M + Na]^+$ precursor ions resulted in the formation of numerous characteristic product ions through a series of dissociative processes. The product ions formed by charge-remote fragmentation (CRF) provided important information for the identification of the acyl chain structure substituted at the glycerol backbone. Some of the product the ions were diagnostic for the presence of a glycerol backbone or acyl chain structure.