• Bulletin of the Korean Chemical Society
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• 제29권7호
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• pp.1359-1363
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• 2008

Second-order rate constants have been determined spectrophotometrically for reactions of 2,4-dinitrophenyl 2- thiophenecarboxylate (2) with a series of alicyclic secondary amines in 80 mol % $H_2O$/20 mol % DMSO at 25.0 ${\pm}$ 0.1 ${^{\circ}C}$. The Brønsted-type plot exhibits a downward curvature, i.e., the slope decreases from 0.74 to 0.34 as the amine basicity increases. The $pK_a$ at the center of the Brønsted curvature, defined as $pK_a^o$, has been determined to be 9.1. Comparison of the Brønsted-type plot for the reactions of 2 with that for the corresponding reactions of 2,4-dinitrophenyl 2-furoate (1) suggests that reactions of 1 and 2 proceed through a common mechanism, although 2 is less reactive than 1. The curved Brønsted-type plot has been interpreted as a change in RDS of a stepwise mechanism. The replacement of the O atom in the furoyl ring by an S atom (1 $\rightarrow$ 2) does not alter the reaction mechanism but causes a decrease in reactivity. Dissection of the apparent second-order rate constants into the microscopic rate constants has revealed that the $k_2/k_{-1}$ ratio is not influenced upon changing the nonleaving group from furoyl to thiophenecarbonyl. However, $k_1$ has been calculated to be smaller for the reactions of 2 than for the corresponding reactions of 1, indicating that the C=O bond in the thiophenecarboxylate 2 is less electrophilic than that in the furoate 1. The smaller k1 for the reactions of 2 is fully responsible for the fact that 2 is less reactive than 1.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.435-440
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• 2009

19 Aromatic ring and L-amino acid ester contained rupestonic acid amide derivatives 2a~2l, 3a~3g were synthesized and preliminarily evaluated in vitro against influenza virus $A_3$,B and herpes simplex virus type 1 (HSV-1), 2(HSV-2) by the national center for drug screening of China. The rusults showed that 2i possessed the highest inhibition against both influenza virus $A_3\;(TC_{50}\;=\;120.6\;{\mu}mol/L,\;IC_{50}=\;19.2\;{\mu}$mol/L, SI = 6.3) and B (T$C_{50}\;=\;120.6\;{\mu}mol/L,\;IC_{50}=\;29.9\;{\mu}$mol/L, SI = 4.0); 2g was more active against influenza $A_3$ virus at very low cytotoxicity ($TC_{50}\;>\;2092.1\;{\mu}mol/L,\;IC_{50}=\;143.7\;{\mu}mol/L,$ SI > 14.6) than the parent compound; Compounds 2b, 2c, 2f showed higher activities both against HSV-1 and HSV-2 than that of the parent compound, and 2f was the most potent inhibitor of HSV-1 ($TC_{50}\;=\;200.0\;{\mu}mol/L,\;IC_{50}\;=\;11.3\;{\mu}mol$/L, SI = 17.7 ) and HSV-2 ($TC_{50}\;=\;200.0\;{\mu}mol/L,\;IC_{50}\;=\;20.7\;{\mu}mol$/L , SI = 9.7).

• 대한화학회지
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• 제41권2호
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• pp.69-76
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• 1997

메탄올-아세토니트릴 혼합용매에서 벤조산 무수물의 아닐린에 의한 친핵성 치환반응을$35.0{\circ}C$에서 속도론적으로 연구하여 반응 메카니즘을 밝혔다. 벤조산 무수물에 있는 두 개의 카르보닐 탄소에서 경쟁적으로 치환반응이 일어나므로 반응 생성물의 비율로부터 각각의 반응속도$k_{XY}$와$k_{XZ}$를 구하였다. Hammett$p_i$값과 교차작용상수$p_{ij}$를 이용하여 전이상태구조 및 반응메카니즘을 규명하였다. 현저히 큰$p_X,\;p_{XY},\;p_{XZ}$및 양의값을 갖는$p_Y$의 크기로부터, 본 반응이 사각고리 전이상태를 갖는 전면공격$SN_2$메카니즘으로 진행됨을 알았다.

• 건축역사연구
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• 제16권1호
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• pp.9-28
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• 2007

We investigated the changes in the species of the woods used for Korean ancient and historic architectures, which include prehistoric excavated relics and existing wooden buildings in South Korea. The species data were collected from various sources such as excavation and repair reports, journal papers, and a few unpublished documents. We divided the building Periods as Paleolithic, Neolitic, Bronze Ages, Iron Age/Three Kingdoms, Koryo, Joseon (early, middle, late) and modem periods. In prehistoric periods, hardwoods were major species. Oak (Quercus spp.) woods dominated (94 percent in average); the others (5%) were Juglans mandshurica, Platycarya strobilacea, Castanea crenata, and few softwoods(1%). During Iron Age and Three Kingdom periods, oaks remained as a major species (57%) and others Platycarya strobilacea(21%), Castanea crenata(13%), and Pinus spp. (6%). The oak woods decreased in Koryo period and they occupied only 1.1%. Instead of oaks, pine (Pinus spp., 71%) and Zelkova serrata (22%) dominated in Koryo. In early and middle Joseon periods, pine woods (73%) remain as a major species and the others were oaks (14%) and Zelkova serrata (9%). As late Joseon came, the pine woods occupied more than 88%. In the late 19th and early 20th centuries, a few boreal species such as larch (Larix spp.) and spruce (Picea spp.), which grow in cold area, were found. We believe they were transported from northern Korea. The existing buildings in Korea are mainly from Joseon period and a few from late Koryo periods. During these periods, pine woods were used for most buildings. For such reason, pine woods were known as 'representative materials for historic buildings'. but earlier times, broad-leaved trees, i.e., oak and Zelkova woods were major materials. The changes in building materials resulted from both climate and human impacts. The dry climate and disturbed forests induce more pines in the mountains. We also compared the wood qualities of the species and found that Zelkova woods were superior ones and deserved more planting for future demands in the repair for historic buildings.

• 한국수소및신에너지학회논문집
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• 제25권4호
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• pp.378-385
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• 2014

In this research, we investigate electrical performance and electrochemical properties of graphene supported Pt (Pt/G) and PtM (M = Ni and Y) alloy catalysts (PtM/Gs) that are synthesized by modified polyol method. With the PtM/Gs that are adopted for oxygen reduction reaction (ORR) as cathode of proton exchange membrane fuel cells (PEMFCs), their catalytic activity and ORR performance and electrical performance are estimated and compared with one another. Their particle size, particle distribution and electrochemically active surface (EAS) area are measured by TEM and cyclic voltammetry (CV), respectively. On the other hand, regarding ORR activity and electrical performance of the catalysts, (i) linear sweeping voltammetry by rotating disk electrode and rotating ring-disk electrode and (ii) PEMFC single cell tests are used. The TEM and CV measurements demonstrate particle size and EAS of PtM/Gs are compatible with those of Pt/G. In case of PtNi/G, its half-wave potential, kinetic current density, transferred electron number per oxygen molecule and $H_2O_2$ production % are excellent. Based on data obtained by half-cell test, when PEMFC singlecell tests are carried out, current density measured at 0.6V and maximum power density of the PEMFC single cell employing PtNi/G are better than those employing Pt/G. Conclusively, PtNi/Gs synthesized by modified polyol shows better ORR catalytic activity and PEMFC performance than other catalysts.

• 천문학회보
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• 제37권2호
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• pp.108.2-108.2
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• 2012

Recent results from microlensing surveys show that a free-floating planet or a wide-separation planet is more numerous than a main-sequence star in the Galaxy. Moreover, the detection efficiency of the planets will be improved in next-generation experiments with a high survey monitoring frequency. However, microlensing events produced by both planets appear similar light curves with a short duration timescale, thus it is difficult to distinguish them. In this paper, we investigated the detectable separation range of a wide-separation planet as the planet bound to its host star. We construct the fractional deviation maps using the magnifications of the planetary lensing and the single-lensing by planet itself for various parameters such as a mass ratio, separation, and source radius. As a result, we found that the pattern of the fractional deviation is related to the ratio of source radius to caustic size, and the ratio satisfying the detection criterion (i.e., ${\geq}5%$ in the fractional deviation) varies with a separation. Hence, we derived a fitting formula as the function of a mass ratio and a source radius to reflect the variation in the calculations of the detectable separation range of a wide-separation planet as the planet bound to its host star. In addition, we estimated the condition that a wide-separation planet can be detected as a single-lensing event under the finite source effect. We found that such a case is possible provided that the source radius is smaller than ~2.5 times of Einstein ring radius of a planet, regardless of a separation or a mass ratio.

• 자원리싸이클링
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• 제5권1호
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• pp.14-20
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• 1996

알루미늄 드로스의 처리는 드로스의 특성과 처리후 발생될 폐드로스의 용도를 고려해서 처리하여야 한다. 이 연구에서는 선정된 시료의 성분과 처리 과정중의 성분변화 등을 조사하였으며, 분급과 같은 예비처리를 하여 드로스 입자가 큰 것은 재용해를 통해서 Al 금속을 바로 회수하고, 입자가 작은 것은 배소, 침출과 같은 예비처리를 해서 드로스 중의 염과 금속성분을 분리, 제거시킴으로써 폐기해야 할 드로스의 양을 줄였다. 드로스를 분급하여 바로 재용해하기 위한 입도의 분급 기준은 $300\mu \;extrm{m}$가 적당하였다. 또, 폐드로스의 재활용을 용이하게 하기 위하여 black 드로스를 처리후 발생된 폐드로스를 배소한 결과 폐드로스에 함유된 대부분의 금속 알루미늄을 알루미나로 산화시킬 수 있었다. 이것으로 보아 폐드로스는 배소하여 함유된 성분들을 산화물 상태로 변화시켜서 알루미나시멘트, 타일과 같은 요업재료나 알루미나 제조원료로 재활용하는 것이 바람직하다.

• Journal of Chest Surgery
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• 제19권1호
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• pp.174-179
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• 1986

Augmentin is a formulation of amoxycillin trihydrate and potassium clavulanate, a fused beta-lactam molecule produced by the fermentation of Streptomyces clavuligerus. Most clinically important resistance is due to the production by bacteria of antibiotic destroying enzymes. In the case of penicillins and cephalosporins these enzymes are termed beta-lactamase as they destroy the beta-lectern ring of these antibiotics, completely inactivating them. The presence of clavulanic acid extends the spectrum of amoxycillin to include bet On clinical study of the intravenous Augmentin in the field of thoracic and cardiovascular surgical cases, we selected randomly 30 patients, 21 male and 9 female, age from 13 to 72, in the period from April to December 1985. Among the total 30 patients, 22 were preoperatively infected [11 thoracic empyema, 5 lobar pneumonia, 2 lung abscess, 2 bronchiectasis, one acute pyelonephritis with ureter stone and one rheumatic carditis], and 8 were not infected preoperatively [Table 1, 2]. Of the preoperatively infected group, 11 cases [50%] were culture positive [4 staphylococcus, 3 pseudomonas, 2 Serratia group, and one E. coli], and preoperatively non-infected group [8 cases] revealed expectedly negative findings on bacterial culture. All of the culture positive bacteria were sensitive to Augmentin on disc culture sensitivity test except one case of E. coli. Daily doses of intravenous Augmentin were 2.-1-6.0gm divided in 2-5 injections. Every injection administered [1.2gm at Augmentin dissolved in 20ml distilled water] slowly for more than 20 minutes. Duration of injection was variable according to the clinical conditions from minimum 5 to maximum 31 days. The results of antibiotic treatment with Augmentin and some other antibiotic combinations pre- and postoperatively were subgrouped as EXCELLENT, EFFECTIVE, and FAILURE. Clinical criteria of the therapeutic result were symptomatic, objective and laboratory improvement. 8 cases were excellent, 13 effective, and one failure among the preoperatively infected group, and all 8 cases of the preoperatively non-infected group were effective as pro;hylactive antibiotic therapy. Overall effective ratio was 97% in both subgroup. There was no side effect clinically and laboratory study including liver and kidney function test during and after the I.V. administration of Augmentin. Oral swallow tablets which were administered after discharge from hospital also revealed good effects with some degree of gastrointestinal trouble.

• Journal of Chest Surgery
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• 제21권4호
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• pp.649-655
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• 1988

One hundred and one patients with tetralogy of Fallot who were older than 16 years of age underwent a total correction of the anomaly between May, 1964 and July, 1987. This group comprised 14.9% of the 679 consecutive patients who had repair of the tetralogy at our institution during the same period. Of the 101 patients, 8 had a previous shunt procedure for palliation. The preoperative mean hemoglobin value was 16.9*1.0% and the mean systemic oxygen saturation, 84.4*0.9%. In 76 patients[75.2%], a type II ventricular septal defect was seen whereas in 14 patients[13.9%], the defect was type I. In 72 patients[71.3%], other cardiac anomalies were present which included patent foramen ovale in 37.6%, atrial septal defect in 8.99b, vegetations in 6.9%, right sided aortic arch in 5.9% and coronary artery anomaly in 5.0%. The right ventricular outflow obstruction was caused most commonly by combination of infundibular and valvular stenosis[74.3%], followed by isolated infundibular stenosis[19.8%] and valvular stenosis [5.9%] alone in order. The preoperative mean diameter of the pulmonary valve ring size was 10.2*0.5 mm in diameter. A transannular patch enlargement of the right ventricular outflow tract was performed in 28 patients and, in 12 a pericardial monocusp was utilized. Major anomalous aorto-pulmonary vessels were encountered in 5 patients which were detected before or during the operation. In 3 patients, they were ligated beforehand to control the flooding of the operative field. Postoperatively, the mean systolic pressure gradient between the right ventricle and the main pulmonary artery was 16.2*2.3 mmHg and the mean systolic pressure- ratio between the right and the left ventricle was 45.3*2.0%. Perioperative complications including bleeding in 8.9%, pleural effusion in 7.9%, dysrrhythmia in 4.9%, and residual VSD in 4.0%. Operative mortality was 8.9%. There has been no operative death in the recent 65 cases since 1981. There were 2 late deaths, 68 and 113 months after surgery. There were 2 late detachment of the VSD patch during the follow-up period. Of the 6 patients with patch detachment found during the postoperative period, 3 had subacute bacterial endocarditis before or after the operation indicating The serious nature of this complication. Two of these patients subsequently underwent a successful reoperation.

• 한국균학회지
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• 제29권2호
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• pp.123-126
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• 2001

국내 남부지역의 논, 밭, 산, 시설재배지 토양 총 43점에서 선충잡이곰팡이를 조사하여, 9종의 포식성곰팡이와 2종의 기생성곰팡이를 분리하였다. 논 토양에서는 1종이 분리되어 선충잡이곰팡이의 검출률이 가장 낮았고(17%), 산에서는 38%의 검출율을 보여 두 번째였으며, 밭과 시설재배지에서는 거의 100% 선충잡이곰팡이가 검출되었다. 우점종은 Arthrobotrys oligospora로 국내 토양 4곳 중 1곳에 서식하며, 시설재배지 토양에서는 2곳 중 1곳에 서식하고 있었다. 선충잡이 도구 중에서는 끈끈이그물(Adhesive nets)을 이용하여 선충을 포식하는 종류가 전체의 72.5%로 가장 많았으며, 다음은 수축성올가미를 가진 A. dactyloides (10.0%), 끈끈이균사를 가진 Cystopage lateralis 7.8%, 내부기생성곰팡이 5.0%, 끈끈이봉을 가진 Monacrosporium ellipsosporum 4.8% 순이었다. 선충잡이곰팡이의 종이나 밀도는 서식 지역에 따라 다르며 토양이 비옥한 시설재배지 토양에서 선충잡이곰팡이의 종과 밀도가 높은 경향이었다.