• Journal of the Korean Ceramic Society
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• v.56 no.3
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• pp.325-330
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• 2019

Band convergence is known to be effective in improving thermoelectric performance by increasing the Seebeck coefficient without significantly reducing electrical conductivity. Decoupling of the Seebeck coefficient and electrical conductivity in converged bands is the key requirement. Yet, the degree of decoupling depends on the band parameters of the converging bands. Herein, we report theoretical transport properties of two valence bands as their energy difference changes from 0.25 eV to 0 eV. In order to demonstrate the effect of band parameters in transport, we first conducted calculations for the case where the two bands have the same parameters. Then, we conducted the same calculation by doubling the density-of-states effective mass of one valence band. Given that there are two bands, each band's effective mass was doubled one at a time while the other band's effective mass remained constant. We found that the decoupling was strongest when the bands participating in convergence had the same band parameters.

• Journal of Biomedical Engineering Research
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• v.15 no.3
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• pp.295-304
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• 1994

This paper describes some preliminary attempts to formulate simple mathematical models of the transmission dynamics of HIV infection in homosexual communities. In conjunction with a survey of the available epidemiological data on HIV infection and the incidence of AIDS, the model is used to assess how various processes influence the course of the initial epidemic following the introduction of the virus. Models of the early stages of viral spread provide crude methods for estimating the basic reproductive rate of the virus, given a knowledge of the incubation period of AIDS and the initial doubling time of the epidemic. More complex models are formulated to assess the influence of heterogeneity in sexual activity. This latter factor is shown to have a major effect on the predicted pattern of the epidemic.

• Korean Journal of Plant Taxonomy
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• v.52 no.4
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• pp.219-225
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• 2022

To elucidate the ancestry of the allopolyploids E. stevenii and E. boöphthona, I examined eleven isozyme loci and 24 morphological characters from 28 populations representing five related Euphorbia species from Australia. According to an analysis of genetic and morphological data, three diploid species differentiated recently, but two independent polyploid species are estimated to have differentiated a relatively long time ago. Fixed heterozygosity for most isozymes in E. stevenii and E. boöphthona strongly suggests that these two species are allopolyploids rather than autopolyploids. The isozyme profiles of E. stevenii indicate that it is an allopolyploid that evolved from interspecific hybridization between the diploid E. tannensis and unidentified or extinct tetraploid species. In addition, isozyme patterns strongly suggest that E. stevenii was one of the ancestors of E. boöphthona. However, E. boöphthona showed a large number of fixed alleles that were not detected in any other Australian Eremophyton species. The most likely hypothesis for the origin of E. boöphthona is that it was formed by hybridization and chromosomal doubling between an extinct diploid species and the hexaploid E. stevenii.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.363-371
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• 2023

To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.2
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• pp.187-193
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• 2009

The present study identified the favorable conditions for isolation, enrichment and in vitro culture of highly purified, undifferentiated pig spermatogonial stem cell (SSC) lines that proliferate for long periods of time in culture. The colonies displayed morphology similar to miceSSC and were positive for markers of SSC (PGP9.5), proliferating germ cell (PigVASA), pre-meiotic germ cell (DAZL) and pluripotency (OCT4, SSEA-1, NANOG, and SOX2) based on immuno-cytochemistry and RT-PCR. The purity of these colonies was confirmed by negative expression of markers for sertoli cell (GATA4 and SOX9), peritubular myoid cell (${\alpha}$-SMA), differentiating spermatogonial and germ cells (c-KIT). The colonies could be maintained with undifferentiated morphology for more than two months and passaged more than 8 times with doubling time between 6-7 days. Taken together, we conclude that pigSSC could be successfully isolated and cultured in vitro and they possess characteristics similar to miceSSC.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.2
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• pp.89-95
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• 1999

This study investigates the population model of the spread of HIV/AIDS which the infection is generated by an infectious individual in a population of susceptible. A mathematical model is presented for the transmission dynamics of HIV infection within the communities of homosexual males. The pattern on the epidemic character of HIV, the causative agent of AIDS, was analysed by the mathematical model of AIDS system which is derived according to the ecological relationship between five epidemilogic states of individuals. The computer simulation was performed using real data and the following conclusions are drawn on the basis of the simulations. 1. The model structure and the algorithm described n the thesis is good. 2. In proportion to increase Ro, the population of AIDS patient increases and the time of its widespread reaches earlier. 3. The AIDS patients will be maximum between 7 and 21 years after an attack of AIDS and widespread between 10 and 20 years. 4. Considering the properties of the incubation periods, the maximum number of infected person is increased, and the attack rate is decreased.

• Korean Journal of Plant Resources
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• v.26 no.2
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• pp.284-288
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• 2013

This study aimed to get the basic data on the breeding of good varieties in Hypericum patulum Thunberg. The optimum materials, concentration and soaking time were examined to identify the effective approach to induce tetraploid plant by colchicine treatment to cultivate the varieties. For the seed germination rate of seed by colchicine treatment, the higher colchicine concentration was and the longer soaking time was, the more the germination rate decreased. While individuals were germinated in 16 test groups except control group (no treatment group), all the plants were diploid and no tetraploid was induced. For the plant regeneration rate by colchicine treatment on the explant of Hypericum patulum Thunberg that was under in vitro culture, the higher the colchicine concentration increased, the ress the regeneration rate. While total 147 individuals were regenerated in all treatment, when the explant was soaking treatment in more than 0.05% for over 6 hours, tetraploid could be obtained. In the soaking treatment of 0.05% for over 6 hours, tetraploid could be obtained. In particular, for the soaking treatment in 0.05% for 12 hours, 8 tetraploids were induced, which was about 47.1% of the number of plant regenerated. In accordance with the observation on doubling of DNA contents in leaf in order to identify polyploidy, the peak DNA content of G1 phase was 94.5 for diploid and 192.5 for tetraploid. It confirmed doubling of DNA content. Furthermore, the number of chloroplasts per guard cell depending on polyploid was around 10 in diploid and 17 to 19 in tetraploid, which were around 1.7 to 1.9 times as much as diploid.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.3
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• pp.214-220
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• 2014

The aim of this study is to optimize the efficiency of a photobiorector on the growth rate of Chlorella vulgaris (C. vulgaris) by varying distance of optical panel (OP). The round shaped C. vulgaris (FC-16) having the size of $3-8{\mu}m$ is employed in this study. The cells of C. vulgaris are cultured in the Jaworski's Medium with deionized water at $22^{\circ}C$ for 15 days. The OP is placed at four different distances i.e., at 225 mm distance (Run 1), 150 mm distance (Run 2), 112.5 mm distance (Run 3) and 90 mm distance (Run 4) having a LED (Light Emitting Diode) source. The diffuse rate is achieved to 86%, 90%, 92% and 94% for Run 1, Run 2 Run 3 and Run 4, respectively. A narrower distance of OP caused to effectively to increase the efficiency of diffuse light rate. For mass cultivation of this biomass, medium is changed according to distance of OP after attaining a maximum biomass concentration; Run 1 in 8 days, Run 2 in 6 days, Run 3 in 4 days and Run 4 in 3 days. In addition, the amount of maximum biomass rate for Run 4 was reached 3 times higher than that of Run1. However, growth rate, chlorophyll per cell, cell volume and doubling time are found to be Run 3 and Run 4 higher than that of Run 1 and Run 2 samples. However, Run 3 and Run 4 are having a slight difference in all these measurements. These findings suggest that in terms of economic consideration and efficiency towards simultaneous mass cultivation of biomass, Run 3 was found to be more effective than other samples.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.3
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• pp.314-323
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• 2015

Black ginseng was made by steaming raw white ginseng nine times at $100^{\circ}C$ for 2 h and drying. We then performed pilot experiments using the nine black ginseng extracts for different steaming and drying times to determine their anti-obesity effects. Two ginseng extracts, steaming and drying five times (FSFD) and steaming and drying nine times (NSND), prepared in water or ethanol solution decreased lipid accumulation of 3T3-L1 cells. FSFD in water and ethanol extracts showed higher levels of ginsenosides, in particular, Rh1, Rg2, and Rb1 than NSND, and levels of the three ginsenosides were higher in ethanol extracts than in water extracts. Treatment with FSFD and/or NSND in ethanol extracts significantly regulated $PPAR{\gamma}$, C/$EBP{\alpha}$ and AMPK phosphorylation in 3T3-L1 cells. We verified doubling time of stem cells from both abdominal fat and subcutaneous fat after FSFD and NSND in ethanol and water extracts were added. Although addition of FSFD and NSFD in water extracts had no effects on proliferation, ethanol extracts with FSFD and NSND increased doubling time of stem cells in subcutaneous fat. FSFD and NSND in ethanol extracts more effectively reduced adipogenesis compared to those in water extracts. FSFD in ethanol extracts promoted secretion of anti-inflammatory cytokine such as IL-10 and depressed MCP-1 infiltration in 3T3-L1 preadipocytes co-cultured with RAW264.7 cells. We concluded that FSFD and NSND ethanol extracts may be developed as a functional food for its anti-obesity effect, but anti-inflammatory effect was shown in ethanol extracted FSFD rather than in NSND.

• Journal of Veterinary Clinics
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• v.27 no.3
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• pp.232-239
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• 2010

Two cell lines derived from spontaneous canine mammary gland tumors were established and characterized. Mammary gland tumors from 9 years old pug and 9 years old toy-poodle dogs were collected by aseptic surgical resection and primary culture was performed. The histopathologic examination of tumors revealed adenocarcinoma and complex carcinoma and two dogs died from metastasis of the tumors. The tumor cells were subcultured over 60 times for more than 1 year and morphological consistency maintained. Light microscopic examination, growth curve, doubling time calculation, xenotransplantation to female nude mice, immunohistochemistry for wide spectrum keratin, vimentin, $\alpha$-smooth muscle actin and cytokeratin 8 was performed for characterization. The cell lines exhibited polygonal, elongated cell shape and cytoplasmic bridge and doubling time of 47.1 hrs and 18.6 hrs, respectively. Subcutaneous xenotransplantation to nude mice of the cells produced localized palpable mass within 4 weeks in 4 of 5 and 5 of 5 nude mice, respectively. In immunohistochemical examination one cell line showed strong positive against wide spectrum keratin and cytokeratin 8 and the other cell line showed strong positive against smooth muscle actin and cytokeratin 8. Additional characterization would be possible by investigator's needs and the cell lines may be useful for in vivo and in vitro studies of canine mammary tumor and adjuvant therapies.