• Journal of the Korean Mathematical Society
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• v.48 no.6
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• pp.1285-1325
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• 2011

We solve the isoperimetric problem, the least-perimeter way to enclose a given area, on various Euclidean, spherical, and hyperbolic surfaces, sometimes with cusps or free boundary. On hyperbolic genus-two surfaces, Adams and Morgan characterized the four possible types of isoperimetric regions. We prove that all four types actually occur and that on every hyperbolic genus-two surface, one of the isoperimetric regions must be an annulus. In a planar annulus bounded by two circles, we show that the leastperimeter way to enclose a given area is an arc against the outer boundary or a pair of spokes. We generalize this result to spherical and hyperbolic surfaces bounded by circles, horocycles, and other constant-curvature curves. In one case the solution alternates back and forth between two types, a phenomenon we have yet to see in the literature. We also examine non-orientable surfaces such as spherical M$\ddot{o}$obius bands and hyperbolic twisted chimney spaces.

• Communications for Statistical Applications and Methods
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• v.23 no.4
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• pp.321-334
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• 2016

In this paper, we propose power t distribution based on t distribution. We also study the properties of and inferences for power t model in order to solve the problem of real data showing both skewness and heavy tails. The comparison of skew t and power t distributions is based on density plots, skewness and kurtosis. Note that, at the given degree of freedom, the kurtosis's range of the power t model surpasses that of the skew t model at all times. We draw inferences for two parameters of the power t distribution and four parameters of the location-scale extension of power t distribution via maximum likelihood. The Fisher information matrix derived is nonsingular on the whole parametric space; in addition we obtain the profile log-likelihood functions on two parameters. The response plots for different sample sizes provide strong evidence for the estimators' existence and unicity. An application of the power t distribution suggests that the model can be very useful for real data.

• Korean Management Science Review
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• v.22 no.2
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• pp.51-76
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• 2005

The purpose of this study is to investigate the influence of four influencing variables (brand diversity. product information, entertainment, and trust) on purchase Intention and to .examine whether this relationship varies according to the buyer's perceived level of Product involvement. Analysis of 264 responses using the hierarchical regression indicated that all four independent variables were found positively influencing purchase intention. Furthermore, the effects of brand diversity, product information, and trust on purchase intention were revealed to be moderated by perceived product involvement. However, the moderating effect of product involvement on the relationship between entertainment and purchase intention was not statistically significant. Discussions for research findings and managerial implications are discussed.

• Journal of Nutrition and Health
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• v.40 no.6
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• pp.493-499
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• 2007

Celastrus orbiculatus (CO) has been used as a traditional herb medicine to treat fever, chill, joint pain, edema, rheumatoid arthritis and bacterial infection in China and Korea. In this study, we investigated anticarcinogenic effects of Celastrus orbiculatus (CO). CO was extracted with methanol (COM), and then further fractionated into four different types: methanol (COMM), hexane (COMH), butanol (COMB) and aqueous (COMA) partition layers. We determined the cytotoxicity of these four partitions in four kind of cancer cell lines, such as HepG2, MCF-7, HT29 and B16F10 Cells by MTT assay. Among various partition layers of CO, the COMM showed the strongest cytotoxic effects on cancer cell lines we used. We also observed quinone reductase (QR) induced effects in all partition layers of CO on HepG2 cells. The QR induced effects of COMM on HepG2 cells at 80 ${\mu}$ g/mL concentration indicated 3.28 to a control value of 1.0. The COMM showed the highest induction activity of quinone reductase on HepG2 cells among the other partition layers. Although further studies are needed, the present work suggests that CO may be a chemopreventive agent for the treatment of human cells.

• Journal of Chest Surgery
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• v.24 no.11
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• pp.1149-1153
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• 1991

A modified procedure for the operative management of the corrected transposition of the great arteries with ventricular septal defect and pulmonary stenosis or atresia was performed in 4 patients. (age ; 18 months-9 years). The operation consists of a venous switch procedure (Senning), intraventricular baffling directing the blood flow from the morphologic left ventricle into the aorta via ventricular septal defect through the right ventriculotomy, and insertion of valved conduit between the morphologic right ventricle and the pulmonary artery. All the four patients had large non-restrictive ventriular septal defects and no evidence of significant mitral valve regurgitation. Both ventricles were well-developed. Three cases had pulmonary atresia, and the remainder had severe subpulmonic stenosis. Postperatively, all patients showed no findings of systemic or pulmonary venous obstruction withnormal sinus rhythm. One patient died of sepsis due to infection by Methicillin-resistant S. aureus on the thirteenth postoperative day. Follow-up is done on the survivors, and all of them are dong well with regular sinus rhythm, with their functional class I or II at 2 to 8 months after the operation.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.92.6-92
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• 2001

MSC is being developed to be installed on KOMPSAT(Korea Multi-Purpose Satellite-II and to provide high resolution multi-spectral. MSC consists of three main subsystems. One is EOS(Electro-Optics Subsystem), another is PMU(Payload Management Unit) and the other is PDTS(Payload Data Transmission Subsystem). There is an SBC(Single Board Computer) in the PMU to control all MSC subsystems. SBC incorporates Intel 80486 as a main processor and VxWorks as a real-time operating system. SBC software consists of four main tasks and several modules to deal with all control information for imaging and all the state of health telemetrv data, and to perform interface with another MSC units. SBC software also has to handle a lot of commands in order for MSC to perform his mission. One mission command consists of a series of related commands, which are In be executed in the designated sequence, with a specified time ...

• Journal of Acupuncture Research
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• v.30 no.3
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• pp.155-163
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• 2013

Objectives : This study was designed to evaluate the effect of Jung-an acupuncture on the sequelae of peripheral facial palsy. Methods : Four patients suffering from sequelae of peripheral facial palsy were treated with Jung-an acupuncture. Yanagihara's total scores, the scale of Peitersen grades and picture, before and after the Jung-an acupuncture treatment were compared to evaluate its treatment efficacy. Results : Yanagihara's total score of all subjects were increased. Peitersen grades of all subjects were decreased. Conclusions : As indicated by unequivocal increase in all subjects' Yanagihara and Peitersen scores, Jung-an Acupuncture treatment is effective in alleviating the sequelae of peripheral facial palsy. Randomized-controlled trial for further evaluation is necessary to verify the results and findings of this study.

• Current Research on Agriculture and Life Sciences
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• v.30 no.2
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• pp.115-123
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• 2012

Whiteflies harbor several secondary endosymbionts, which are maternally inherited from mother to offspring, that have major effects on host preferences, biology, and evolution. Here, we identified Wolbachia bacteria in sweetpotato whitefly (Bemisia tabaci) as well as whitefly popluations from other countries by comparison of 16S rDNA sequences. Wolbachia were detected in all tested indigenous B. tabaci populations (Bangladesh, Myanmar, Nepal, and the Philippines) as well as Q1 biotype of Korea, whereas they were absent from B biotype of Korea and Q biotype of China. Wolbachia were also detected in all five tested Aleurodicus dispersus populations as well as Tetraleurodes acaciae, whereas they were not detected in all seven Trialeurodes vaporariorum populatuions. In addiiton, Wolbachia were detected in parasitic wasp (Encarsia formosa) of B. tabaci as well as honeybee (Apis mellifera). Among the 19 whitefly populations from different countries, our analysis identified four phylogenetic groups of Wolbachia, thereby demonstrating the high diversity of this genus. Wolbachia phylogeny suggests a correlation of geographical range with ecological variation at the species level.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.32-32
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• 2015

Electrophoretic paint (E-paint) was investigated on four different magnesium substrates: as-extruded AZ61 (AZ61), heat-treated AZ61 (AZ61-H), as-extruded TZ61 (TZ61) and heat-treated TZ61 (TZ61-H), to elucidate the effect of heat treatment and alloying elements on the deposition and corrosion resistance of E-paint. It was found that, a rapid increase of voltage, indicating that the deposition of E-paint had started, was observed after an induction time of 0.39 min for AZ61-H, 0.43 min for AZ61, 0.51 min for TZ61-H and 0.58 min for TZ61. The amount of E-paint deposited on the four samples was approximately similar, but the electrical charge used for the deposition process on the heat-treated samples was smaller than that on the as-extruded samples. The current efficiencies of E-paint on AZ samples (AZ61 and AZ61-H) were higher than those of TZ samples (TZ61 and TZ61-H), and on the heat-treated samples were higher than on as-extruded samples. All E-paintings on the four magnesium substrates had an excellent adhesion without any paint detached by tape peel-test. However, many large blisters were formed on the surface of AZ samples, and none, or very small blisters were observed on TZ samples after immersion test in DI-water for 500 h at $40^{\circ}C$. Under salt spray test (SST) conditions, E-paint on AZ samples showed blistering adjacent to scribes, while blistering of E-paint occurred on intact areas of TZ samples. The E-paint on heat-treated samples showed much better corrosion resistance than that on as-extruded samples. The ranking of greater to lesser corrosion resistance of the E-paint on these four different magnesium substrates is indicated by the order: AZ61-H > AZ61 > TZ61-H > TZ61.

• Journal of the Korean Society of Safety
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• v.25 no.4
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• pp.13-18
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• 2010

To investigate electrostatic ignition hazards of commercial gasoline used in the gas station, experiments were conducted dealing with the minimum ignition energy(MIE) of several kinds of gasoline under the various temperature. The conductivity of gasoline that was required for an accurate risk assessment as well as the MIE were also examined. The solvent ignitability apparatus which can heat up the inside of the vessels up to $210^{\circ}C$ was used in this study. Four kinds of premium gasoline and four kinds of regular gasoline, differing with respect to the companies, were used as test specimens. The following results were obtained: (1) all gasoline specimens were so sensitive that even an electrostatic discharge with a very low energy, such as about 0.5mJ, could ignite them. The ignitability of premium gasoline was constant irrespective of the companies. On the other hand, the ignitability of regular gasoline was variable depending on the company. (2) The MIE of all specimens depended markedly on the temperature; in other words, an increase in temperature decreases the ignition energy value. (3) The conductivity values of all specimens were low. Those must be taken into consideration in electrostatic risk assessment.