• Journal of Power Electronics
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• v.19 no.4
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• pp.907-921
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• 2019

This paper presents two advanced hybrid pulse-width modulation (PWM) strategies for multilevel inverters (MLIs) that provide both common-mode voltage (CMV) elimination and current ripple reduction. The first PWM utilizes sequences that apply one switching state at the double ends of a half-carrier cycle. The second PWM combines the advantages of the former and an existing four-state PWM. Analyses of the harmonic characteristics of the two groups of switching sequences based on a general switching voltage model are carried out, and algorithms to optimize the current ripple are proposed. These methods are simple and can be implemented online for general n-level inverters. Using a three-level NPC inverter and a five-level CHB inverter, good performances in terms of the root mean square current ripple are obtained with the proposed PWM schemes as indicated through improved harmonic distortion factors when compared to existing schemes in almost the entire region of the modulation index. This also leads to a significant reduction in the current total harmonic distortion. Simulation and experimental results are provided to verify the effectiveness of the proposed PWM methods.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.324.1-324.1
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• 2002

Human 5-reductase type II(5AR2) is an important target for the treatment of benign prostatic hyperplasia. In this study we describe the establishment of cell line which stably expressed 3X FLAG tagged human 5AR2. We used this cell line as a cell based assay tool and source for 5AR2 enzyme. First a plasmid (3XFLAGpCMVl0-5AR2) for the expression of 5AR2 was constructed by the use of the vector 3XFLAGpCMV10 and transfected into the HEK 293. By selection with G418 sulfate. ten HEK 293 single cell clones were obtained of which three stably exhibited high 5AR2 activity. (omitted)

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.133.1-133
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• 2003

Gummy stem blight, caused by Didymella bryoniae occurs exclusively on cucurbits. This fungus has been known not to produce its pycnidium in vitro unless irradiated. Through this study, we optimized cultural conditions for mass-production of pycnidiospore by Metal Halide Lamp irradiation. In brief, the mycelial was cultured at $26^{\circ}C$ on PDA, for 2 days under the darkness, and then the plate was illuminated with MH lamp continuously for 3-4 days at $26^{\circ}C$, a great number of pycnidia was simultaneously formed. Thus produced pycnidiospores were used as immunogen. From fusions of myeloma cell (v-653) with splenocytes from immunifed mice were car ried out. And, two hybridoma cell lines that recognized the immunogen Didymella bryoniae were obtained. One Monoclonal Antibody, Db1, recognized the supernatant and the other monoclonal antibody, Db15, recognized the spore. Two clones were selected which were used to produce ascite fluid two MAb Db1 and Db15, were immunotyped and identified as IgG1 and IgG2b, respectively. Titer of MAb Db1 and MAb Db15 was measured absorbance exceeded 0.5 even at a $10^{-5}$ dilution. The MAbs reacted positively with Didymella bryoniae but none reacted with other of fungi and CMV, CGMMV Sensitivity of MAb was precise enough to detect spore concentration as low as $10^{3}$ well by indirect ELISA characterization of the MAb Db1, Db15 antigen by heat and protease treatments show that the epitope recognized by the MAb Bb1, Db15 were a glycoprotein.

• Environmental Mutagens and Carcinogens
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• v.21 no.2
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• pp.164-168
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• 2001

Abel et al. in Germany discovered a new dioxin-responsive gene, which has later been identified as rpt-1 (regulatory protein T-lymphocyte 1). While it is speculated that rpt-1 may play a role in signal transduction and carcinogenesis, its roles and functions remain unknown. The present study attempted to analyze functions of rpt-1 in human epithelial cells following the xenobiotic exposures. While German counterpart analyzed expressionn of rpt-1 in spleen and thymus cells from mouse and rat and characterizes molecular properties of the gene, our work mainly focused on analyzing function of rpt-1 in human skin cells. Expression of rpt-1 in human cells were analyzed by western and northern blot RT-PCR analysis. Expression of rpt-1 as well as Staf-50 in human cells with or without exposure to environmental pollutants were also analyzed by northern blot analysis, since Staf-50 is homologous with rpt-1 and found in human cells. To help study roles of rpt-1 in human cell system, retroviral vector system carrying rpt-1 gene under the CMV promoter were constructed and transfected. Cells overexpressing the gene after the transfection showed an increase of cell density and soft agar colony formations, as compared to the control cells, suggesting that rpt-1 may play a certain role in the transformation processes of human cells. While the expression of rpt-1 in spleen and thymus is known to be strong in the laboratory animals, both the basal and TCDD-induced expression of rpt-1 in the current cellular system remained insignificant. It is speculated that the expression pattern of rpt-1 may be tissue- and species-specific. The present study demonstrated a strong expression of rpt-1 protein in the brain of SD rat model. Since there is no previous report on the expression of rpt-1 in the brain tissue, the result may play a significant role in understanding dioxin-induced neurotoxicities in the future. The present study provides an opportunity to understand a role of rpt-1 in human cell system and suggest a possible lead and basis for the future study of dioxin-induced neurotoxicities.

• Development and Reproduction
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• v.17 no.4
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• pp.379-387
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• 2013

Embryonic stem (ES) cells can self-renew and differentiate to various cells depending on the culture condition. Although ES cells are a good model for cell type specification and can be useful for application in clinics in the future, studies on ES cells have many experimental restraints including low transfection efficiency and transgene expression. Here, we observed that transgene expression after transfection was enhanced by treatment with histone deacetylse (HDAC) inhibitors such as trichostatin A, sodium butyrate, and valproic acid. Transfection was performed using conventional transfection reagents with a retroviral vector encoding GFP under the control of CMV promoter as a reporter. Treatment of ES cells with HDAC inhibitors after transfection increased population of GFP positive cells up to 180% compared with untreated control. ES cells showed normal expression of stem cell markers after treatment with HDAC inhibitors. Transgene expression was further enhanced by modifying transfection procedure. GFP positive cells selected after transfection were proved to have the stem cell properties. Our improved protocol for enhanced gene delivery and expression in mouse ES cells without hampering ES cell properties will be useful for study and application of ES cells.

• Reproductive and Developmental Biology
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• v.29 no.1
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• pp.49-55
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• 2005

We cloned cDNA of the PGH(porcine growth hormone) gene and constructed retrovirus vector designed to express PGH gene under the regulation of CMV (cytomegalovirus) promoter. To maximize the expression, WPRE(woodchuck hepatitis virus posttranscriptional regulatory element) sequence was placed at the downstream of the PGH gene. After infection with recombinant viruses, approximately 1×10/sup 6/ PFF(porcine fetal fibroblast) cells released PGH protein into the media as much as 1,400 ng. In a subsequent experiment, a modifications of the retrovirus vector was made to express the PGH gene in a teracycline-inducible manner. In PFF cells carrying these viral vector sequences, addition of doxycycline to the media resulted in 2∼6 fold increase in PGH synthesis. In the modified retrovirus vectors, the WPRE sequence also played a role in boosting the effect of the tetracycline induction. This result indicates that our tetracycline-inducible expression system might be a promising candidate in alleviating the complicate physiological problems caused by constitutive expression of the exogenous genes in the transgenic animals.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.37-37
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• 2005

Human chorionic gonadotropin (hCG) is a heterodimeric glycoprotein hormone consisting of non-covalently linked two subunits, the ${\alpha}$ and ${\beta}$ subunit. It has been used as a infertility drug for ovulation to mimic luteinizing hormone $(LH).^{1)}$ A stable cell line was established by transfection of Rc/CMV-i-dhfr-hCG, expression vector containing hCG ${\alpha}-$ and ${\beta}-genes$, into dihydrofolate reductase-deficient CHO cells and subesquent methotrexate-mediated gene amplification. Anchorage-dependent CHO cells were adapted into a serum-free and/or animal component-free suspension medium through gradual serum weaning for the hCG production. The established cell line showed typical morphological characteristics and growth profile of CHO cells, and could produce FSH with passage-to-passage consistency. The high density perfusion culture of the CHO cells was carried out in Celligen Plus bioreactor equipped with a spin-filter as a internal cell retention device. The cell density reached up to $>1x10^{7}$ cells/ml in less than 7 days and a perfusion-control strategy based on cellular consumption rates of glucose was $established.^{2)}$ Biologically active recombinant hCG was purified by a series of chromatographic steps including anion exchange chromatography and hydrophobic interaction chromatography to homogeneity. The highly purified recombinant hCG was characterized for physicochemical, immunological and biological properties.

• Reproductive and Developmental Biology
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• v.41 no.3
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• pp.51-55
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• 2017

The production of therapeutic protein from transgenic domestic animal is the major technology of biotechnology. Insulin-like growth factor-1 (IGF-1) is known to play an important role in the growth of the animal. The objective of this study is construction of knock-in vector that bovine IGF-1 gene is inserted into the exon 7 locus of ${\beta}$-casein gene and expressed using the gene regulatory DNA sequence of bovine ${\beta}$-casein gene. The knock-in vector consists of 5' arm region (1.02 kb), bIGF-1 cDNA, CMV-EGFP, and 3' arm region (1.81 kb). To express bIGF-1 gene as transgene, the F2A sequence was fused to the 5' terminal of bIGF-1 gene and inserted into exon 7 of the ${\beta}$-casein gene. As a result, the knock-in vector is confirmed that the amino acids are synthesized without termination from the ${\beta}$-casein exon 7 region to the bIGF-1 gene by DNA sequence. These knock-in vectors may help to create transgenic dairy cattle expressing bovine bIGF-1 protein in the mammary gland via the expression system of the bovine ${\beta}$-casein gene.

• Korean Journal of Poultry Science
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• v.42 no.3
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• pp.239-245
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• 2015

Transgenic animals have been widely used for developmental biology studies, as disease models, and even in industry such as transgenic bioreactor animals. For transgenic birds, quail has the great advantages of small body size, short generation time, and frequent egg production. To date, retroviral or lentiviral transduction has been used to generate transgenic quail for various purposes. However, the efficiency of transgenic offspring production with these methods is relatively low and viral vector usage has safety issues. Unfortunately, non-viral transgenesis has not been established in quail due to a deficiency of stem cell and germ cell culture systems. In this study, we established a direct in ovo lipofection method that could be used to create transgenic quail without germline-competent cells or viruses. To optimize the injection stage during embryo development, the liposome complex (containing piggyBacCMV-GFP and transposase plasmids) was introduced into an embryonic blood vessel at 50 hr, 55 hr or 60 hr. GFP expression was detected in various tissues (heart, kidney, liver and stomach) on day 12 of incubation under a fluorescence microscope. Additionally, GFP-positive cells were detected in the recipient embryonic gonads. In conclusion, the direct in ovo lipofection method with the piggyBac transposon could be an efficient and useful tool for generating transgenic quail.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.141.2-142
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• 2003

A flexuous rod-shaped virus was isolated from Cucurbita pepo leaves showing green mosaic and puckering symptoms at Anseong, Korea. Based on the biological tests, electron microscopy, and reverse transcription-polymerase chain reaction (RT-PCR), the isolate was identified as Papaya ringspot virus type Watermelon (PRSV-W). In the biological test, host range of PRSV-W was limited in the families Cucurbitaceae and Chenopodiaceae. Most susceptible cucurbit species, such as Cucurmis lanatus, Cucurmis sativus, Cucurbita pepo, and Citrullus lanatus, responded to mechanical inoculation by PRSV-W that induce green mosaic, malformation, puckering, and narrow laminae. The local lesion symptoms were produced on the inoculated leaves of Chenopodium maranticolor and C. quinoa PRSV specific primers which amplifies the part of the coat protein (CP) genes, generated a 648 bp product from 6 isolates of PRSV-W, but no amplification had been detected in other viruses including CMV, CGMMV, KGMMV, ZYMV and WMV. In electron microscopy, PRSV particles were flexuous, approximately 780 nm in length and 12 nm in width. PRSV-W is one of the worldwide viruses which has the great economic importance in cucumber, melon, squash, watermelon, and other cultivated cucurbits with ZYMV and WMV. This is the first report of PRSV-W on cucurbits in Korea.