• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.9
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• pp.71-80
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• 2007

This paper presents a new push-push VCO technique that extracts a second harmonic output signal from a capacitive commonnode in a negativegm oscillator topology. The generation of the $2^{nd}$ harmonics is accounted for by the nonlinear current-voltage characteristic of the emitter-base junction diode causing; 1) significant voltage clipping and 2) different rising and falling time during the switching operation of core transistors. Comparative investigations show the technique is more power efficient in the high-frequency region that a conventional push-push technique using an emitter common node. Prototype 12GHz and 17GHz MMIC VCO were realized in GaInP/GaAs HBT technology. They have shown nominal output power of -4.3dBm and -5dBm, phase noise of -108 dBc/Hz and -110.4 dBc/Hz at 1MHz offset, respectively. The phase noise results are also equivalent to a VCO figure-of-merit of -175.8 dBc/Hz and -184.3 dBc/Hz, while dissipate 25.68mW(10.7mA/2.4V) and 13.14mW(4.38mA/3.0V), respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.2
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• pp.107-115
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• 1997

In this paper, a 23 GHz push-push oscillator was designed and fabricated for 23 GHz point-to-point communication using split ring resonator. The split ring resonator was equivalent circuit and numerical method of MPIE(Mixed Potential Integral Equation). The analysis of split ring resonator which coupled between microstrip lines was carried out with transmission-mode using this results. The fabricated oscillator showed the output power of 4 dBm, the 1'st harmonic suppression of -20 dBc, the 3rd harmonic suppression of -34 dBc, a SSB phase noise of -109 dBc / Hz at 1MHz offset frequency from the carrier was achieved and 1.4 percents efficiency at 23 GHz. The experimental outputs were in good results with the theoretical and simulated results.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.131-135
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• 2002

Acetobacter xylinum KJ1 efficiently producing bacterial cellulose(BC) in shaking culture was isolated from a rotten grape. The strain was used to investigate optimum operating conditions for increasing BC production and factorial design model was employed for the optimization. The results of experiments were statistically analyzed by SAS program. Reciprocal effects of each factors(carbon source concentration, shaking speeds(rpm), oxygen pressure, and CSL concentration) and culture condition of BC production were examined by getting regression equation of the dependent variable. Comparisons between experimental results and predicted results about BC concentration were done in total 24 experiments by combination of each factors using SAS program, and the correlation coefficients of BC concentration and BC yield were 0.91 and 0.81, respectively. The agitated cultures were performed in various operation conditions of factors which affected considerably to BC production in jar fermentor. The results showed that BC concentration was 11.67g/ L in 80 hours cultivation under the condition of carbon source concentration shaking speeds(rpm) : oxygen pressure: CSL concentration = 4% : 460rpm : 0.28 : 6%. On the other hand BC yield was 0.42g/g in 80 hours cultivation under the condition of carbon source concentration shaking speeds(rpm) : oxygen pressure: CSL concentration = 4% : 564rpm : 0.21 : 2%. The BC production could be enhanced up to more than 65.3% by factorial design. The result of a verifying experiment under the optimal conditions determined by the factorial design to the BC production showed that the model was appropriate by obtaining BC concentration of 11.02g/L in the optimum condition

• Korean Journal of Microbiology
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• v.29 no.4
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• pp.243-249
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• 1991

The chromatophore from the chemotrophically grown facultative anaerobic photosynthetic bacterium, Rhodopseudomonas gelatinosa ATCC 17013 was isolated through stepwise sucrose gradient centrifugation. The isolated chromatophore showed high activities of the cytochrome $bc_{1}$ complex and cytochrome c oxidase. The activity of cytochrome $bc_{1}$ complex was completely inhibited by .5$\mu$M antimycin A,10$\mu$M myxothiazol, and that of cytochrome c oxidase was completely inhibited by .$50\mu$M KCM and $100\mu$M $NaN_{3}$but not inhibited by carbon monoxie. The activity of cytochrome c oxidase of th chromatophore was increased by addition of ionophores or protonophores. The reduced-oxidised difference sspectrum of cytochrome $bc_{1}$ complex isolated by affivity chromatography showed the absorption maxima at 553 nm(shoulder at 547 nm), 520 nm, and 418.5 nm, on the other hand, that of cytochrome c oxidase showed .alpha., .betha. and soret peaks at 554 nm, 523 nm, and 421 nm, respectively. The cytochrome c oxidase from chemotrophically grown Rhodopseudomonas gelatinosa seems to be a b-type cytochrome c oxidase.

• Korean Journal of Food Science and Technology
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• v.23 no.1
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• pp.31-36
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• 1991

Cellulase genes from thermophilic alkalophilic Bacillus sp. F204 a potent cellulase complex-producing bacterium, were cloned in Escherichia coli with pUC 19. Plasmids pBC191 and pBC192, isolated from transformants forming yellow zone around colony on the LB agar plate containing 0.5% carboxymethyl cellulose and ampicillin, contained 4.6 Kb and 5.8 Kb HindIII fragments, respectively. The 4.6 Kb insert of pBC191 had single sites for BamHI EcoRI, KpnI and pvuII. DNA hybridization and immunodiffusion studies showed that pBC191-encoded cellulase gene was homologous with that of host strain. pKC231, constructed by inserting 4.6 Kb insert of pBC191 at the HindIII site of pKK223-3, E. coli expression vector, and pGC711, constructed by inserting 4.6 Kb insert of pBC191 at the HindIII site of pGR71, E. coli and B. subtilis shuttle vector, had 3.2 times and 2.8 times as much cellulase activity as pBC191, respectively. Substrate specificity analysis showed that cellulases cloned were CMCase.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.3
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• pp.410-415
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• 2010

The purpose of this study was to investigate the anti-inflammatory effects of aqueous extract from Belamcanda chinensis (BC) on the RAW 264.7 cells. To evaluate the anti-inflammatory effects of BC, we examined the cytokine productions including nitric oxide (NO), interleukin (IL)-1b, IL-6 and tumor necrosis factor-a (TNF-a) in lipopolysaccharide (LPS)-induced RAW 264.7 cells and also inhibitory mechanisms such as mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-kB) using Western blot. BC inhibited LPS-induced production of NO, IL-6 and TNF-a but not of IL-1b in RAW 264.7 cells. BC respectively inhibited the activation of MAPKs such as c-Jun NH2-terminal kinase (JNK) and p38 but not of extracelluar signal-regulated kinase (ERK 1/2) and NF-kB in the LPS-stimulated RAW 264.7 cells. Taken together, Our results showed that BC down-regulated LPS-induced NO, IL-6 and TNF-a productions mainly through JNK and p38 MAPK pathway.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.213-218
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• 2010

Lactate dehydrogenases (LDHs) have been highly focused for long time, due to their important roles in biochemical and metabolic pathways of cells. On the basis of genome-wide searching results, three putative LDH genes from Bacillus cereus ATCC 14579 genome have been PCR-amplified, cloned, and well-expressed in E. coli. All three BcLDH isozymes are supposed to share highly conserved catalytic amino acid residues in common $NAD^+$-dependent LDHs. Meanwhile, BcLDH1 consisting of 314 amino acids shares 86 and 49% of identities with BcLDH2 and 3, respectively. Interestingly, only BcLDH1 showed the converting activities between L-lactate and pyruvate in the presence of $NAD^+$ coenzyme, while the other isozymes are likely to have almost no activity. As a result, it was revealed that BcLDH1 can be a typical $NAD^+$-dependent L-lactate-specific dehydrogenase.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.6
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• pp.339-346
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• 2023

Objectives: This analysis details the characteristics of dental trauma in South Korea during the coronavirus disease 2019 (COVID-19) (DC) pandemic and compares them in patients before and after COVID-19 (BC and AC, respectively). Materials and Methods: Data were collected from medical records of patients who visited Seoul National University Bundang Hospital's Emergency Dental Care Center during three 12-month periods: BC, DC, and AC (BC from March 1, 2019 to February 29, 2020; DC from March 1, 2020 to February 28, 2021; AC from March 1, 2022 to February 28, 2023). A retrospective review was conducted to investigate patient age, sex, time of visit, cause, and diagnosis. The study included 1,544 patients: 660 BC, 374 DC, and 510 AC. Results: Significant difference in age and sex was not observed among the three periods; 1-9 years of age was the largest group (38.3% in BC, 29.6% in DC, and 27.8% in AC), and the percentage of male patients was greater than of female patients (male proportion as 63.5% in BC, 67.4% in DC, and 64.9% in AC). The number of patients generally peaked at a Saturday night in spring (for BC: May, Saturday, 18:00-19:59; for DC: March, Saturday, 18:00-19:59; for AC: April as the second most (October as the most peaked), Saturday, 20:00-21:59). The primary etiology of the dental trauma was identical in the three periods: falls, followed by sports. The most frequent diagnosis was laceration, followed by tooth avulsion and jaw fracture. Conclusion: Significant differences were not found between the characteristics and patterns of dental trauma in the BC, DC, and AC periods. However, due to the pandemic and social distancing, activities decreased and associated dental trauma-related incidents declined.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.122-128
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• 2023

This paper proposes two kinds of single-balanced direct conversion quadrature receivers using selfoscillating LMVs in which the voltage-controlled oscillator (VCO) itself operates as a mixer while generating an oscillation. The two LMVs are complementary coupled and series coupled to generate the quadrature oscillating signals, respectively. Using a 65 nm CMOS technology, the proposed quadrature receivers are designed and simulated. Oscillating at around 2.4 GHz frequency, the complementary coupled quadrature receiver achieves the phase noise of -28 dBc/Hz at 1KHz offset and -109 dBc/Hz at 1 MHz offset frequency. The other series coupled receiver achieves the phase noise of -31 dBc/Hz at 1KHz offset and -109 dBc/Hz at 1 MHz offset frequency. The simulated voltage conversion gain of the two single-balanced receivers is 37 dB and 45 dB, respectively. The double-sideband noise figure of the two receivers is 5.3 dB at 1 MHz offset. The quadrature receivers consume about 440 μW dc power from a 1.0-V supply.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.388-393
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• 2013

The study was focused to evaluate the possibility for combination membrane of bacterial cellulose (BC) and graphene with high electrical properties. BC with natural polymer matrix was known to have strong physical strength. For the combination of graphene with BC, the surface of graphene was modified with oxygen plasma by changing strength and time of radio waves in room temperature. Water contact angle of modified graphene grew smaller from $130^{\circ}$ to $12^{\circ}$. XPS analysis showed that oxygen content after treatment increased from 2.99 to 10.98%. Damage degree of graphene was examined from $I_D/I_G$ ratio of Raman analysis. $I_D/I_G$ ratio of non-treated graphene (NTG) was 0.11, and 0.36 to 0.43 in plasma treated graphene (PTG), increasing structural defects of PTG. XRD analysis of PTG membrane with BC was $2{\theta}$ same to BC only, indicating chemically combined membrane. In FT-IR analysis, 1,000 to 1,300 $cm^{-1}$ (C=O) peak indicating oxygen radicals in PTG membrane had formed was larger than NTG membrane. The results suggest that BC as an alternation of plastic material for graphene combination has a possibility in some degree on the part like transparent conductive films.