• The Journal of the Korean Society for Microbiology
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• v.11 no.1
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• pp.69-78
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• 1976

There have been increasing reports of mycobacterioses in man and animals caused by "atypical" or "opportunist" mycobacteria. At the presnt, "opportunist mycobacterioses" are not generally responsive to antituberculosis drugs, and therefore, create considerable problems with regard to chemotherapy and control measures. In recent years studies have been made to isolate opportunist mycobacteria from soil, house-dusts and tap-water. It seemed quite interesting to define the extent of circumstantial presence of "opportunist" mycobacteria and nocardia in the soils of school-ground of primary schools and middle-high schools. This communication is the results of pilot study to isolate and identify "opportunist" mycobacteria and nocardia from 504 soil specimens of 72 schools in Seoul City. 1. Of a total of 59 isolates from 504 soil specimens tested, 32 strains were identified as opportunist mycobacteria and 27 strains as nocardia. 2. Isolation rates of opportunist mycobacteria by the areas(of specimen collection) were as follows: 36.4% in the southern area of Han-River, 33.3% in the central area, 22.7% in the outskirt area and 16.6% in the intermediate area. There observed no apparent difference in the isolation rates both-between the areas and between primary schools and middle-high schools. However, a significant difference was noted in the isolation rates between the places of soil sampling in a given school(P<0.05), i.e., the highest was the soil of refuge heaps(15.2%), and tap-water pole area(11.1%), the school-lavatory entrance(9.7%), the school gate entrance(5.5%), and iron-bar play ground(2.7%). The soil specimens from the center of school ground and from school building entrance yielded none of mycobacterial isolates. 3. Isolation rates of nocardia by the areas were as follows: 33.3% in the central area, 31.8% in the outskirt area, 27.3% in the southern ares of Han-River and 11.1% in the intermediate area. As in the case of mycobacteral isolates, there observed no apparent differences in the isolation rates both between the areas and between primary schools and middle-high schools, but a significant difference was noted between the places of soil sampling(P<0.05), i.e., the highest was the soil of school building entrance(15.2%), and of school gate entrance(6.9%), refuge heaps(5.5,%), iron-bar play ground(4.1%), the school-lavatory entrance(2.7%) and tap-water pole area(2.7%), respectively. The soil specimens from the center of, school ground yielded none of nocardia isolates. 4. Of the 32 strains of isolated mycobacteria. 15 strains were slow-growing mycobacteria and the remaining 17 strains belonged to the rapid growers. Of the 15 slow-growers. 4 strains were M. scrofulaceum-szulgai complex, 3 M. gordonae, 4 M. terrae-triviale complex, 2 M. avium-intracellulare-xenopi complex, and 2 unclassified schotochromogens. Of the 17 strains of rapid growers, 12 were M. diernhoferi, 2 M. fortuitum-peregrinum complex, 2 M. vaccae and one M. flavescens. 5. Of the 27 strains of nocardia isolated, 11 strains were N. transvalensis, 5 N. convoluta, 5 N. erythropolis, one N. vaccinii, one N. polychromogens-paraffinae complex and 4 untypable strains of orange-pigmented nocardia spp.

• The Journal of Korean Association of Computer Education
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• v.7 no.6
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• pp.117-128
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• 2004

Compared with traditional face-to-face instruction, online learning causes learners to experience more severe feeling of isolation and results in higher dropout rate. This is due to the lack of interaction, sense of belonging, membership, interdependency, cooperation among members and social environment that enables persistence in online learning. Therefore, it is very important for grouping e-learning community to lower the dropout rate and eliminate feeling of isolation. In this paper, the research has been done on the inclination test list to be applied for grouping the desirable learning community. And on the basis of this research, the grouping system for e-learning community(GSE) based on intelligent multi agents for an inclination test using homogeneous and heterogeneous items has been developed. GSE system has such properties that construct a personalized user profile by an agent, and then make groupings according to users' inclination. When this system was evaluated, about 88% of learners were satisfied, and they wanted the group not to be disorganized but to be maintained.

• Journal of the Korean Wood Science and Technology
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• v.41 no.4
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• pp.269-275
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• 2013

Antifungal and insecticidal activity of Korean traditional medicinal plants was carried out to develop natural material for the development of organic cultural heritage conservation. As a result, Phellodendron amurense fruit was finally selected as a candidate of antifungal and insecticidal natural material. An novel active compound was purified from the ethylacetate fraction of Phellodendron amurense fruits using silica gel and Sephadex LH-20 column chromatography and PTLC. The compound was obtained as yellow oil form; UV ${\lambda}_{max}$(MeOH): 260 nm. The chemical structure of novel compound was determined as (4'-ethyl-2'-methylfuranyl)-6-methoxy-7-methylnona-2E,4E,6Z,8E-tetraenoic acid on the basis of various NMR experiments including $^1H$- and $^{13}C$-NMR, HMQC, HMBC and ESI-mass spectrum.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.606-610
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• 2001

Voltage harmonics resulting from current harmonics produced by the nonlinear loads have become a serious problem in many systems. Moreover momentary interruptions and voltage sags are responsible for many of the power quality problems found in typical industrial plants. In this paper, proposed power system using series active power filter is not only harmonic compensation but also harmonic isolation between supply and load, and voltage regulation and unbalance compensation. The effectiveness of the proposed system is verified through computer simulations and experiments

• Journal of the Korean Wood Science and Technology
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• v.29 no.4
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• pp.97-102
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• 2001

EtOAc extract from the bark of Pinus koraiensis Sieb. et Zucc was isolated by column chromatography which was packed with Sephadex LH-20 or TSK-gel HW-40F. Several stilbene glycosides were identified by $^1H{\cdot}^{13}C$-NMR, HMQC, HMBC and $FAB^+$ MS. Three stilbene glycosides, Z-pinostilbenoside, E-desoxyrhaponticin, and E-resveratroloside, were identified.

• Journal of Korea Water Resources Association
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• v.55 no.spc1
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• pp.1211-1222
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• 2022

Abnormal condition inevitably occurs during operation of water distribution system (WDS) and requires the isolation of certain areas using isolation valves. In general, the determination of the optimal location of isolation valves considered minimization of hydraulic failures as isolation of certain areas causes a change in hydraulic states (e.g., flow direction, velocity, pressure, etc.). Water quality failure can also be induced by changes in hydraulics, which have not been considered for isolation valve system design. Therefore, this study proposes a new isolation valve system design methodology to prevent unexpected water quality failure events. The new methodology considers flow direction change ratio (FDCR), which accounts for flow direction changes after isolation of the area, as a constraint while reliability is used as the objective function. The optimal design model has been applied to a synthetic grid network and the results are compared with the traditional design approach. Results show that considering FDCR can eliminate flow direction changes while average pressure and coefficient of variation of pressure, velocity, and hydraulic geodesic index (HGI) outperform compared to the traditional design approach. The proposed methodology is expected to be a useful approach to minimizing unexpected consequences by traditional design approaches.

• Journal of Digital Convergence
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• v.16 no.12
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• pp.109-122
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• 2018

This study investigates factors to disturb the e-Learning persistence of adult learners based on a case study of Cyber University students located in Seoul Korea. Main findings of our research show that economic burden, shortage of studying hours, digital literacy problem, perceived isolation, inefficient interaction between lecturer and student, and support of family are primary factors to influence the persistence of online education in a Cyber university. From our case study, we recommend to improve the scholarship system, and supplement the offline special lectures at weekends in order to alleviate perceived isolation. A novelty of this paper is that economic burden is highlighted to influence the persistence of adult learners.

• Journal of the korean veterinary medical association
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• v.8 no.2
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• pp.3-16
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• 1964

For the purpose of researching the Erysipelothrix rhusiopathiae(E.r) organisms isolated from fish body surface and pathogenicity of domestic animals, I made practical isolation tests of the E. r. organisms for market fishes(Sea-fishes) at the market, and

• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.388-391
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• 1992

A chemical investigation of the fruits of Piper retrofractum (Piperaceae) has led to the isolation and characterization of a novel piperidine alkaloid, piperoctadecalidine together with three known alkaloids piperine, pipernonaline and guineensine. The structure of the new compound was detemined to be (2E,4E,14Z)-N-(2,4,14-Octadecatrienoyl) piperidine by spectral and synthetic methods.

• KSBB Journal
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• v.24 no.6
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• pp.508-514
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• 2009

This study investigated the production of catalase from Bul-kyo soil bacteria through fermentation process. Isolation and selection of bacteria was performed through chemical and physiological analysis. Catalases were produced from bacteria which belong to 3 different species (Bacillaceae bacterium BKBChE-1, Bacillus sp. BKBChE-2, Bacillus flexus BKBChE-3) confirmed by using 16S rDNA sequence method. The catalases were found to be stable in the temperature range of $30^{\circ}C-60^{\circ}C$ for BKBChE-1, BKBChE-2 and BKBChE-3 and also in the pH range of 9.0-12.0 for BKBChE-1 and BKBChE-3. Long-term stability of the catalases was about 20 days at $4^{\circ}C$. However, BKBChE-2 has kept its activity over 30 days at $4^{\circ}C$.