• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.382-385
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• 1995

Electrical properties such as tracking resistance, dielectric constant, $tan\delta$, and volume resistivity, and mechanical properties such as tensile, and strength, and % elongation were measured with the alumina trihydrate filled with EPDM. The results were dicussed in terms of the effect of hydroxyl group. The test results show that the tracking resistance of EPDM improves with the increase in ATH content, whereas volume resistivity, dielectric constant, $tan\delta$ decrease wi th increasing ATH content due to polar nature of ATH. In the charge accumulation characteristics, the homocharge is formed in pure EPDM, and as the ATH content increases in the EPDM compound, the amount of homocharge decrease.

• Ocean and Polar Research
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• 제38권4호
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• pp.287-294
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• 2016

Marine sponges have been a remarkably rich source of pharmacologically active and structurally diverse natural products. As a part of our continuing search for novel secondary metabolites of biomedical importance from marine invertebrate, we encountered the sponge Lipastrotethya sp. from Chuuk, Micronesia. The crude organic extract of this animal exhibited considerable cytotoxicity against the K562 cell line. Guided by the $^1H$ NMR analysis, flash chromatography of the crude extract followed by HPLC yielded a new triterpene glycoside, along with ten known saponins of the sarasinoside class. The structure of this new compound was determined by combined spectroscopic methods such as COSY, HSQC and HMBC experiment. Among these metabolites, six compounds exhibited moderate cytotoxicity against ACHN, MDA-MB-231, NCI-H23 and NUGC-3 cell lines.

• Archives of Pharmacal Research
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• 제18권6호
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• pp.454-457
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• 1995

To improve the yield of genuine aglycones from glycosides, the conditions of alkaline hydrolysis were investigated, and a modified method was established. The modified method empolyed pyridine as an aprotic solvent. To complete the hydrolysis and obtain 20(S)-protopanaxadiol (1) and 20(S)-protopanaxatriol(2), which are the genuine aglycones of ginsenosides, total ginsenosides were refluxed with sodium methoxide in pyridine. Addition of methanol, a protic polar solvent to the reaction miuxture, led partial hydrolysis yielding a mixture of the genuine prosapogenols. Of the prosapogenols compound 3 and 6 characteristically possessed D-glucopyranosyl moiety attached at the sterically hindered C-20 hydroxyl group. 3 and 6 were not obtaijned by other hydrolysisw methods except by the soil bacterial hydrolysis.

• Archives of Pharmacal Research
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• 제22권6호
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• pp.575-578
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• 1999

Derivatives of elema-1,3-diene were synthesized in several steps as polar analogs of $\beta$-elemene, antitumor agent under clinical phase. The lactone ring of compound 1 was opened by LiAlH4 to give diol 2 which was selectively protected by TBDPSCI. After acetylation of the secondary alcohol, the acetylated product was ozonolyzed and reduced to give elemene derivative 4 which was converted to diolefin 8 via selenides subsequent deprotection by tetrabutylammonium fluoride gave two compounds 9, 10.

• 생약학회지
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• 제48권2호
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• pp.113-118
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• 2017

Bioassay guided fractionation and isolation of the $CH_2Cl_2$ extract from the apical bud of Gardenia sootepensis (Rubiaceae) led to the isolation of five known flavonoids (1-5). The structures of the compounds were determined by 1D and 2D NMR, and MS experiments, as well as by comparison of their data with published values. Compounds 1-5 were isolated for the first time from this plant source. The isolated compounds were evaluated for their cancer chemopreventive potential based on their ability to inhibit nitric oxide (NO) production. Among the isolates, compound 4 exhibited considerable NO inhibitory activity with an $IC_{50}$ value of $13.8{\mu}M$.

• Food Science and Biotechnology
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• 제15권3호
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• pp.404-408
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• 2006

Feasibility of surface plasmon resonance (SPR) method to evaluate soybean frying oil quality was evaluated. Free fatty acid value, p-anisidine value, conjugated dienoic acid content, conjugated trienoic acid content, peroxide value, iodine value, total polar compound (TPC), ratio of unsaturated fatty acid to saturated fatty acid, refractive index, dielectric constant, smoking point, and L, a, and b of Hunter color system were selected as parameters related to conventional evaluation of soybean frying oil quality. SPR scale mapped with conventional quality parameters well described free fatty acid value, conjugated dienoic acid content, dielectric constant, TPC, and b of Hunter color system, as shown by correlation and linear regression analyses.

• 한국자기공명학회논문지
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• 제26권4호
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• pp.40-45
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• 2022

A small cage-like molecule (2) composed of three aminomethyl pyrroles and two hexa-substituted benzenes has been prepared by reduction of its iminopyrrole analogue (1) using NaBH₄. It was revealed by ¹H NMR spectroscopic analyses that cage molecule 2 strongly binds the fluoride anion in polar DMSO-d₆ relative to CDCl₃. Compared to that of compound 1, the lowered affinity of 2 for the fluoride anion is attributable to its increased electron density resulting from the production of thesecondary amine groups.

• 폴리머
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• 제38권4호
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• pp.411-416
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• 2014

극성을 띠고있어 응집되는 성향이 카본블랙에 비해 강한 실리카의 분산도는 고무 복합소재의 물성을 좌우하는 중요한 요소이다. Wolff는 입자간 상호계수(${\alpha}_F$)를 도입하여 충전제간의 구조발달을 최초로 표현하였다. 하지만, 양기능성 실란의 도입에 따라 형성되는 3차원 구조발달은 표현할 수 없었다. 후에 이를 보완하기 위하여 Wolff의 표현은 복합소재 내 ${\alpha}_F$를 포함하는 구조발달 상호계수 ${\alpha}_C$로 확장되어 표현되었지만, 실험적으로 이 표현을 증명한 연구는 없었다. 이 논문은 구조발달 상호계수인 ${\alpha}_C$를 ${\alpha}_F$(실리카-실리카간 구조발달 상호계수), ${\alpha}_{FP}$(실리카-실란-고무간 구조발달 상호계수), ${\alpha}_P$(고무-고무간 구조발달 상호계수)로 고려하여 단기능성 및 양기능성 실란으로 처리된 실리카가 함유된 복합소재를 실험에 의해 최초로 표현하였다. 구조가 다른 실란들(PTES, OTES, TESPD, TESPT)을 이용하여 구조발달 상호계수 ${\alpha}_C$를 구성하는 ${\alpha}_F$, ${\alpha}_{FP}$, ${\alpha}_P$의 수치들을 측정하고 계산하였다. TESPT가 첨가된 복합소재의 ${\alpha}_C$의 값은 1.64이며, 이를 구성하고 있는 ${\alpha}_F$, ${\alpha}_{FP}$, ${\alpha}_P$는 각각 0.99, 0.31, 0.34로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제13권3호
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• pp.268-274
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• 1992

An attempt to improve the second harmonic generation (SHG) efficiency of MAP (methyl (2,4-dinitrophenyl)aminopropanoate) by modifying the substituents on the amino group of MAP is described. Several MAP analogues have been prepared using optically active amino acids alanine, phenylalanine and serine, and their SHG efficiencies measured. None of the MAP analogues exhibited SHG efficiencies as high as that of MAP. X-ray crystal structures of three MAP analogues have been determined. In the crystal structures of two of them, which were the derivatives of phenylalanine, two crystallographically-independent molecules existing in the asymmetric unit are aligned almost antiparallel. These structures are consistent with the very low SHG efficiencies of these compounds. On the other hand, the crystal structure of a serine derivative reveals substantial alignment of the dinitroaniline chromophore along the polar axis. However, the angle of 86.2° between the molecular charge tranfer axis and the polar axis of the crystal is still far away from the optimum value of 54.74° for the phase-matchable SHG. The structure is consistent with the SHG efficiency of this compound which is much higher than those of the phenylalanine derivatives but still lower than that of MAP. This study demonstrates the importance of the orientation of molecules in the crystal lattice in determining secod-order nonlinear optical properties of crystalline materials.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.327.1-327.1
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• 2014

Nitrides-on-silicon structures are considered to be an excellent candidate for unique design architectures and creating devices for high-power applications. Therefore, a lot of effort has been concentrating on growing high-quality III-nitrides on Si substrates, mostly Si(111) and Si(001) substrates. However, there are several fundamental problems in the growth of nitride compound semiconductors on silicon. First, the large difference in lattice constants and thermal expansion coefficients will lead to misfit dislocation and stress in the epitaxial films. Second, the growth of polar compounds on a non-polar substrate can lead to antiphase domains or other defective structures. Even though the lattice mismatches are reached to 16.9 % to GaN and 19 % to AlN and a number of dislocations are originated, Si(111) has been selected as the substrate for the epitaxial growth of nitrides because it is always favored due to its three-fold symmetry at the surface, which gives a good rotational matching for the six-fold symmetry of the wurtzite structure of nitrides. Also, Si(001) has been used for the growth of nitrides due to a possible integration of nitride devices with silicon technology despite a four-fold symmetry and a surface reconstruction. Moreover, Si(110), one of surface orientations used in the silicon technology, begins to attract attention as a substrate for the epitaxial growth of nitrides due to an interesting interface structure. In this system, the close lattice match along the [-1100]AlN/[001]Si direction promotes the faster growth along a particular crystal orientation. However, there are insufficient until now on the studies for the growth of nitride compound semiconductors on Si(110) substrate from a microstructural point of view. In this work, the microstructural properties of nitride thin layers grown on Si(110) have been characterized using various TEM techniques. The main purpose of this study was to understand the atomic structure and the strain behavior of III-nitrides grown on Si(110) substrate by molecular beam epitaxy (MBE). Insight gained at the microscopic level regarding how thin layer grows at the interface is essential for the growth of high quality thin films for various applications.