• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.8
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• pp.1174-1181
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• 2003

The flow around a circular cylinder was controlled by attaching O-rings to reduce drag force acting on the cylinder. Four experimental models were tested in this study; one smooth cylinder of diameter D (D=60mm) and three cylinders fitted with O-rings of diameters d=0.0167 D, 0.05D and 0.067 D with pitches of PPD=2D, 1D, 0.5D and 0.25D. The drag force, mean velocity and turbulence Intensity profiles in the near wake behind the cylinders were measured for Reynolds numbers based on the cylinder diameter in the range of Re$_{D}$=7.8$\times$10$^3$~1.2$\times$10$^{5}$ . At Re$_{D}$=1.2$\times$10$^{5}$ , the cylinder fitted with O-rings of d=0.0167D in a pitch interval of 0.25D shows the maximum drag reduction of about 5.4%, compared that with the smooth cylinder. The drag reduction effect of O-rings of d=0.067D is not so high. For O-ring circulars, as the Reynolds number increases, the peak location of turbulence intensity shifts downstream and the peak magnitude is decreased. Flow field around the cylinders was visualized using a smoke-wire technique to see the flow structure qualitatively. The size of vortices and vortex formation region formed behind the O-ring cylinders are smaller, compared with the smooth cylinder.der.

• Archives of Pharmacal Research
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• v.22 no.4
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• pp.428-431
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• 1999

Seven known oleanolic acid glycosides (1-7) were isolated form the MeOH extract of Tiarella polyphylla. The structures were identified to be 3-O-($\beta$-glucopyranosyl) oleanolic acid (1), 3-O-[$\beta$-D-glucopyranosyl-(1 3)-$\beta$-D-glucopyranosyl] oleanolic acid (2), 3-O-D-[$\beta$-D-glucopyranosyl-(1 2)-$\beta$-D-glycopyranosyl] oleanolic acid (3), 3-O-[$\beta$-D-glucopyranosyl-(1 3)-$\beta$-D-glucopyranosyl] oleanolic acid 28-O-$\beta$D-glucopyranosyl ester (4), 3-O-[$\beta$-D-glucopyranosyl-(1 2)-$\beta$-D-glucopyranosyl] oleanolic acid 28-O-$\beta$-D-glucopyranosyl ester (5), 3-O-[a-L-rahmnopyranosyl-(1 3)-$\beta$-D-glucururonopyranosyl] oleanolic acid (6), and 3-O-[$\alpha$-L-rhamnopyranosyl-(1 3)-$\alpha$-D-glucuronopyranosyl] oleanolic acid 28-O-$\alpha$-D-glucopyranosyl ester (7) on the basis of physicochemical and spectral data. These triterpene glycosides were tested for the anti-complement activity and hemolytic activity. Bisdesmosidic saponins, 4, 5, and 7, showed anti-complement activity; in contrast, monodesmosidic saponins, 1-3, and 6, showed direct hemolytic activity. Methyl esterified monodesmosidic saponins showed anti-complement activity at a low concentration and hemolytic activity at a high concentration.

• YAKHAK HOEJI
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• v.39 no.3
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• pp.289-296
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• 1995

For the investigation of medicinal resources the studies were carried out to evaluated the pharmaco-constituents in the Leaves of Parthenocissus tricuspidata(Vitaceae), of which leaves have been used in Korea as folk remedies for the treatments of arthritis, jaundice, toothache, neuralgia, and etc. From 1-butanol fraction of the MeOH extract, Compound I ($C_{21}H_{18}O_{13}$, Quercetin-3-O-$\beta$-D-glucuronopyranoside), Compound II ($C_{21}H_{20}O_{12}$, Quercetin-3-O-$\beta$-D-glucopyranoside) and Compound III ($C_{25}H_{28}O_{12}$, Quercetin-3-O-(6"-n-butyl)-$\beta$-D-glucuronopyranoside) were isolated by column chromatographic separation using Sephadex LH-20 and ODS gel. Their structures were elucidated through instrumental analyses, such as $^{1}H$-NMR, $^{13}C$-NMR, IR, UV, El-Mass, FAB-Mass and GC. Especially compound III was Flavonol glycoside and named parthenosin.

• Archives of Pharmacal Research
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• v.22 no.1
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• pp.81-85
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• 1999

Nine flavonoids (1-9) were isolated from the leaves of Morus alba (Moraceae). The structures of compounds were determined to be kaempferol-3-O-$\beta$-glucopyranoisde (astragalin, 1) kaempferol-3-O-(6"-O-acetyl)-$\beta$-D-glucopyranoside (2), quercetin-3-O-(6"-O-acetyl)-$\beta$-D-glucopyranoside (3), quercetin-3-O-$\beta$-D-glucopyranoside (4), kaempferol-3-O-$\alpha$-L-rhamnopyranosyl-(1 6)-$\beta$-D-glucopyranoside (5), quercetin-3-O-$\alpha$-L-rhamnopyranosyl-(1 6)-$\beta$-D-glucopyranoside (rutin, 6), quercetin-3-O-$\beta$-D-glucopyranosyl-(1 6)-$\beta$-D-glucopyranoside (7), quercetin-3,7-di-O-$\beta$-D-glucopyranoside (8) and quercetin (9) on th basis of spectroscopic and chemical studies. Compounds 7 and 9 exhibited significant radical scavenging effect on 1,1-diphenyl-2-picryl-hydrazyl radical.

• Applied Biological Chemistry
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• v.3
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• pp.25-48
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• 1962

The polysaccharide C prepared from gum tragacanth powder (U. S. P. grade) by the precipitation method with 85% ethanol was a neutral polysaccharide, $[{\alpha}]^{30}_D-72.2$. The polysaccharide C consisted of L-rhamnose, D-xylose, L-arabinose and D-galactose in the molar ratio 2:1:17:9 (Table 1, 2, 3, ). The polysaccharide C was methylated with dimethylsulphate and 40% NaOH, and Purdies regent. The hydrolyzate of fully methlated product ($[{\alpha}]^{22}_D-102$ in chloroform, the methoxy content 40.6%) was composed of 2, 3, 5-tri-O-methyl-L-arabofuranose (I), 3,4-di-O-methyl-L-rhamnopyranose (II), 2,3-di-O-methyl-D-xylose (III), 2,3,4-tri-O-methyl-D-galactopyranose (IV), 2,4-di-O-methyl-L-arabopyranose (?), 2,4-di-O-methyl-D-galactose(VI), 2-O-methyl-D-arabinose (VII), and L-arabopyranose(VIII) (Table 4, 5, and Fig. 4). The first partial hydrolysis (A) of the polysaccharide C with 0.05N-HCl for 4.5 hours at $80-85^{\circ}C$ released only L-arabinose: the second hydrolysis (B) with 0.1N-HCl for 5 hours at $80-85^{\circ}C$, L-arabinose and D-galactose; and the third hydrolysis (C) with 0.3N-HCl at $90-95^{\circ}C$ in sealed tube, L-rhamnose, D-xylose, L-arabinose and D-galactose. From the unhydrolyzate A' were found L-rhamnose, D-xylose, L-arabinose, and D-galactose; from B' L-rhamnose, d-xylose, L-arabinose and D-galactose; and from C' D-xylose and D-galactose respectively (Table 6). The periodate consumption and formic acid production of the polysaccharide C were measured at various time intervals. After 120 hours periodat was consumed by 1.23 mole per $C_5H_8O_4$ and formic acid was produced 0.78 mole per $C_5H_8O_4$ (Table 7). Although a definite chemical structure for this polysaccharide C may not be formulated, experimental data, especially, from methylation, partial hydrolysie and determination of its molar ratio, and periodate analysis showed that the polysaccharide C is a highly branched polysaccharide and would be constructed of galactoaraban as a main chain residue and L-arabofuranose, D-galactopyranosyl $(1{\rightarrow}1)$-L-arabofuranose, D-xylopyranosyl $(1{\rightarrow}2)$-L-rhamnopyranosyl $(1{\rightarrow}1)$-L-arabofuranose, and L-rhamnopyranosyl $(1{\rightarrow}1)$-arabofuranose, and D-galactopyranosyl-$(1{\rightarrow}2)$-L-arabopyranosyl-$(1{\rightarrow}1)$-I-arabofuranose as a branch chain or end group (page 21).

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.552-555
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• 1995

The magnetic properties of Mg-Mn ferrites were investigated in the composition range of $Mg_{a}Mn_{b}Fe_{c}O_{4\pm\delta}$ (a+b+c=3) with the addition of $Al_{2}O_{3}$. In $MgO-MnO-Fe_{2}O_{3}$ ternary system, the spinel single phase existed within the composition range of MgO-50 mol%, MnO-70 mol% and $Fe_{2}O_{3}-60\;mol%$. The saturation magnetic flux density increased with the increase of $Fe_{2}O_{3}$ content and showed the maximum at the stoichiometric composition of $(Mg,Mn)Fe_{2}O_{4}$. In $Mg_{x}Mn_{1-x}Fe_{2}O_{4}(x=0.2~0.8)$ system, the saturation magnetic flux density showed the maximum at $Mg_{0.2}Mn_{0.8}Fe_{2}O_{4}$. The addition of $Al_{2}O_{3}$ resulted in the decrease of saturation magnetic flux density but increased the electrical resistivity.

• Journal of the Korean Society of Food Culture
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• v.3 no.2
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• pp.153-162
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• 1988

$D{\acute{o}}ck$ (Korean rice cake) is a peculiar food of Korea made of grain. By means of cooking from, it is defined as 'Pulvberzed food of grain' $D{\acute{o}}ck$ was one of the daily food, but development of boild rice had narrowed it's use to the food of festive days and ceremonies. $D{\acute{o}}ck$ is used as a main food of all Kinds of ceremonies from one's birth to death, such as the Three seven day(a baby's twenty-first day of life), one hunderdth day, birthday, wedding, both brithday, funeral and sacrifical rites, vocational ceremonies, such as a sacrifice to spirits and a srevics for a big catch of fish. It is also used as a present and seasonal food. A large variety of $D{\acute{o}}ck$ is available and its recipe is scientific and reasonable. In this treatise, the Kinds of $D{\acute{o}}ck$ and the frequency of them, the material, the recipe, the measuring unit of material, cooking kitchen utensils and the cooking terms are studied from the books published in Korea from 1670 to 1943. 1. $D{\acute{o}}ck$ was classified as Tcbin $D{\acute{o}}ck$(steamed), Chin $D{\acute{o}}ck$(strikn), Chijin $D{\acute{o}}ck$(fried) and Salmun $D{\acute{o}}ck$(boiled), according to its way of cooking. 2. There were 122 Kinds of $D{\acute{o}}ck$, 57 were Tchin $D{\acute{o}}ck$, 35 Chin $D{\acute{o}}ck$, 20 Chijin $D{\acute{o}}ck$, and 10 Salmun $D{\acute{o}}ck$. 3. There were 34 Kinds of measuring units. Of them, 13 for volume, 4 for weight, 9 for quantity, 4 for length and 4 for the rest. 4. There were 55 Kinds of cooking Kitchen utensils but now many of them are not used because of mechanization or automation of tools of living. 5. There were 143 Kinds of cooking terms. Of them 49 for the preparing process, 25 for the mixing process, 27 for well-forming process 10 for process of getting ready to cook, 14 for heating process, 10 for cutting process, 5 for dishin process and 3 for process of soaking in sugar or honey.

• Journal of Digital Convergence
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• v.15 no.1
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• pp.77-84
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• 2017

This study investigates the association between financial reporting strategy and the directors' and officers' liability insurance. Since D&O insurance protects officers and directors against the risks of shareholder litigation, it is possible that, because of moral hazard, managers will be more willing to participate in opportunistic financial reporting such as earnings manipulation when they are covered by a generous D&O insurance policy. This paper examines the association between D&O insurance and financial reporting, specifically whether the purchase of D&O insurance affects earnings manipulation. On the other side, the firms engage earnings management are willing to purchase D&O insurance, this study tests whether earnings manipulation affects D&O purchases using listed firms in Korean stock market from 2006 to 2008. This paper finds that firms with higher discretionary accruals are less likely to purchase D&O insurance implies that managers who are participating in earnings manipulation are not willing to purchase D&O insurance. The relation between discretionary accruals and D&O is significantly negative which indicate D&O insurance purchase does not trigger earnings manipulation rather it alleviates opportunistic reporting behavior.

• Journal of Korean Society of Transportation
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• v.15 no.1
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• pp.45-62
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• 1997

이 논문은 O-D 접근방법과 P-A 접근방법을 이론적으로 서로 비교한 연구이다. O-D 접근방법은 전통적인 교통수요 4단계 분석기법의 모든 과정에서 통행수 산출을 통행 유출과 통행유인의 개념을 적용하여 O-D 통행량을 사용한 기법으로 정의되었다. 이러한 O-D 접근방법은 우리 나라에서 보편적으로 사용되고 있는 기법이다. P-A 접근방법은 통행 발생, 통행분포, 교통수단선책 분석과정까지 통행생성과 통행유인의 개념을 적용하여 P-A 통행량을 사용한 기법으로 정의되었으며, 노선배경 분석단계에 앞서 P-A 통행량을 O-D 통 행량으로 전환되어져야 한다. P-A 접근방법은 구미국가들에서 보편적으로 사용되는 기법이 다. 이러한 두 접근방법은 통행목적 분류에서 귀가통행이 별도로 분류되어있는가 혹은 아닌 가에 따라 쉽게 구분되어 질 수 있다. 만일 귀가통행이 통행목적의 분류에서 별도로 구분되 어 있으면 O-D 접근방법이 적용되고 있음을 의미하는 것이다. 이 연구는 전통적 교통수요 4단계 분석과정 중 통행발생, 통행분포 및 교통수단선택의 각 분석과정에서 두 접근방법간 의 이론적 차이점을 명확히 비교 분석하고자 하였다. 그러므로써 형태적 통행패턴을 상대적 으로 잘 설명하며 또한 집합적 오차를 상대적으로 초 lth화할 수 있는 기법이 어느 것인가 를 이론적으로 찾고자 하였다. 이 연구에서는 행태적 측면에서 통행패턴을 P-A 접근방법이 더 잘 표현하고 있으며 또한 집합화 오차도 P-A 접근방법이 더 적으므로 P-A 접근방법이 O-D 접근방법보다 이론적으로 더 우수하다고 결론지었다. 또한 이 연구는 통행발생, 통행 분포, 교통수단선택 분석과정이 끝난 후 P-A 통행량에서 O-D 통행량으로 전환하는 것이 통행발생, 통행분포의 분석과정이 끝난 후에 O-D 통행량으로 전환하는 것보다 더 바람직하 다고 추천하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.2
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• pp.55-60
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• 2024

Two-dimensional (2D) RuO₂ nanosheets with nanometer thickness were synthesized using a chemical exfoliation method. The synthesized 2D-RuO₂ was hybridized with Ag-nanowire (NW), which is attracting attention as a next-generation transparent electrode material. After coating Ag-NW on the substrate, 2D-RuO₂ was subsequently coated on the Ag-NW. Although there was a decrease in optical transmittance, the hybridization of 2D-RuO₂ confirmed the effect of reducing sheet resistance. Furthermore, the flexibility of the fabricated transparent electrodes was also studied. It was confirmed by the change in sheet resistance after bending. The additional coating of 2D-RuO₂ improved the flexibility of the transparent electrodes.