• 한국전자파학회논문지
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• 제29권10호
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• pp.766-772
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• 2018

본 논문에서는 InGaAs enhancement mode $0.15{\mu}m$ pHEMT를 이용하여 6~10 GHz 대역에서 동작하는 wide-band 전력증폭기를 설계하였다. Enhancement 소자는 gate 바이어스를 양전압으로 사용하며, 음전압을 위한 추가회로 구성이 없어지며 모듈의 크기를 줄일 수 있다. 또한, 본 설계에서는 3D-EM(electromagnetic) 시뮬레이션을 통해 패키지 본드와이어의 인덕턴스 및 기판 손실을 예측하여 설계하였다. 광대역을 위해 lossy matching을 사용하고, 전력, 효율 관점에서 최적의 바이어스를 선정하여 설계하였다. 제안한 전력증폭기의 패키지 칩은 6~10 GHz 대역에서 20 dB 이상의 평탄 이득, 8 dB 이상의 입출력 반사손실, 출력전력은 27 dBm 이상, 전력부가효율은 35 % 이상으로 측정되었다.

• 한국세라믹학회지
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• 제48권3호
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• pp.217-221
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• 2011

Glass-ceramic materials, which consist of glass matrix phase containing crystalline ${\beta}-Ca_3(PO_4)_2$ and ${\beta}-Ca_2P_2O_7$, have been prepared by heating at $750-900^{\circ}C$ of calcium phosphate invert glasses in the silica-free $CaO-P_2O_5-TiO_2-Na_2O$, system. With increasing heating temperature from 750 to $900^{\circ}C$, the crystallite size of precipitated ${\beta}-Ca_3(PO_4)_2$ in glass with $55CaO{\cdot}35P_2O_5{\cdot}3TiO_2{\cdot}7Na_2O$ (mol%) composition increased from 48 to 91 nm. With the extension of the immersion time in dilute acetic acid solution (pH = 5) to ${\geq}$200 min, the degree of dissolution of $Ca^{2+}$ and $P^{5+}$ ions in the glass-ceramics was linearly increased and the solution was constantly maintained at pH = ~7. Biomimetic nanostructured (62-88 nm in average dia.), sphere-shaped hydroxyapatite was homogeneously formed on the surface of the glass-ceramics when socked for 7-14 days in a Hanks' solution, indicating bioactivity of the prepared glass-ceramics.

• 한국축산식품학회지
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• 제37권1호
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• pp.18-28
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• 2017

Pastirma is a dry-cured meat product, produced from whole beef or water buffalo muscles. This study was carried out to investigate the effect of production stages (raw meat, after curing, after $2^{nd}$ drying and pastirma) on the total lipid, neutral lipid, phospholipid and fatty acid composition of phospholipid fraction of pastirma produced from beef M. Longissimus dorsi muscles. The pH and colour ($L^*$, $a^*$ and $b^*$) analyses were also performed in raw meat and pastirma. It was found that pastirma production stages had significant effects (p<0.01) on the total amounts of lipid, neutral lipid and phospholipid, and the highest amounts of lipid, neutral lipid and phospholipid were detected in pastirma. In pastirma, neutral lipid ratio was determined as $79.33{\pm}2.06%$ and phospholipid ratio as $20.67{\pm}2.06%$. Phospholipids was proportionately lower in pastirma than raw meat. Pastirma production stages affected pentadecanoic acid (15:1) (p<0.01), linoleic acid (18:2n-6) (p<0.05), ${\gamma}-linoleic$ acid (18:3n-6) (p<0.05), erucic acid (22:1n-9) (p<0.05), docosapentaenoic acid (22:5n-6) (p<0.05), total unsaturated fatty acid (${\Sigma}USFA$) (p<0.05) and total saturated fatty acid (${\Sigma}SFA$) (p<0.05) ratios of phospholipid fraction and also the moisture content (p<0.01). Pastirma process also affected pH and colour ($L^*$, $a^*$ and $b^*$) values (p<0.01), and these values were higher in pastirma than raw meat.

• KSBB Journal
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• 제24권4호
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• pp.341-346
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• 2009

본 연구에서는 Candida antarctica로부터 genomic DNA을 추출하여 lipase A(CalA) 유전자를 PCR 증폭하였고, 재조합 pColdIII/CalA, $pPICZ{\alpha}A$/CalA, $pPICZ{\alpha}A$/CalA$his{\times}6$을 구축하였다. 재조합 CalA 유전자의 기능적 발현을 위해 최적화된 시스템을 구축하고자 Escherichia coli와 Pichia pastoris 시스템에서 각각 수행하여 비교, 분석하였다. SDS PAGE gel을 통해 CalA의 발현의 여부 및 발현양을 확인하였고, pNPP를 기질로 한 가수분해 반응을 통해 활성을 측정하였다. E. coli 발현 시스템은 형질전환 방법이 간단하고, 미생물의 성장 속도가 빠르다는 장점을 갖지만 CalA의 활성이 0.02 Unit/ml으로 비교적 낮았으며 세포질 (cytoplasm)에서 발현되므로 비목적 단백질과의 분리 및 정제과정이 필요하다. 재조합 $pPICZ{\alpha}A$/CalA을 P. pastoris 시스템에서 발현한 경우 높은 발현양 뿐만 아니라 분비작용으로 인해 고순도 발현이 용이하였고, 활성 또한 약 0.7 Unit/ml으로 가장 높았다. 결론적으로 CalA의 기능적 발현을 위해 P. pastoris 시스템을 구축하는 것이 가장 적합함을 확인하였다.

• 한국응용과학기술학회지
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• 제8권1호
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• pp.9-20
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• 1991

In the preparation of acrylic water repellent(EDLWC). quaternized 2-diethylarrunoethylmethacrylate-stearylmethacrylate copolymer (DSACC) and quaternized 1-Iaurovlbis(aminoethyl)-2-dodecylimidazoline(LDDIC) were selected as a basic resin and the improving agent such as softening effect and hydrostatic pressure of the water repellent. EDLWC was prepared by blending waxes and emulsifier for waxes with various ratio to DSACC and LDDIC. As the results of the measurement of water repellency, washable, tear strength and crease recovery to polyester-cotton(P/C) blended fabrics treated with EDLWC only or addition of textile finishing resin, the physical properties were increased. Sodium acetate was the most effective catalyst in the water repellency among the various kinds of catalyst. and the reasonable concentration of the catalyst was 1. 4 wt%. EDLWC was confirmed as durable water repellent with the results of making little difference of water repellency as ${\pm}5$ point after and before washing. The reaction mechanism between P/C blended fabrics and EDLWC in the presence of catalyst was proposed. And also, the longitudinal view of the P/C blended fabrics treated with water repellent was observed with scanning electron microscope.

• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.128-134
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• 2008

The kinetics of cell growth and Cyclosporin A (Cyc A) production by Tolypocladium inflatum were studied in shake flasks and bioreactors under controlled and uncontrolled pH conditions. In the case of the shake flask, the production time was extended to 226 h and the maximal antibiotic concentration was 76 mg/l. When scaling up the cultivation process to a bioreactor level, the production time was reduced to only 70h with a significant increase in both the cell growth and the antibiotic production. The maximal dry cell weights in the case of the controlled pH and uncontrolled pH cultures in the bioreactor were 22.4g/l and 14.2g/l, respectively. The corresponding maximal dry cell weight values did not exceed 7.25g/l with the shake flask cultures. The maximal values for Cyc A production were 144.72 and 131.4 mg/l for the controlled and uncontrolled pH cultures, respectively. It is also worth noting that a significant reduction was observed in both the dry cell mass and the antibiotic concentration after the Cyc A production phase, whereas the highest rate of antibiotic degradation was observed in the stirred tank bioreactor with an uncontrolled pH. Morphological characterization of the micromorphological cell growth (mycelial/pellet forms) was also performed during cultivation in the bioreactor.

• Korean Chemical Engineering Research
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• 제51권2호
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• pp.257-262
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• 2013

부영양화 방지를 위하여 규제되는 총인(Total-phosphorous, T-P) 농도가 0.2~2 mg/L 이하로 변경됨에 따라, 응집 처리 과정에서 인의 제거를 시도하게 되었다. 따라서 본 연구는 실제 하수종말처리장의 생물학적 처리수를 시료로 하여 티탄염 농도, pH 등의 인자가 인 제거에 미치는 특성에 대하여 검토하였다. 또한 실제 현장에서 가장 많이 사용되는 침강식 침전조와 가압부상식 침전조에 티탄염을 적용하여 인 제거 효율 및 슬러지 활용 가능성을 조사하였다. 응집제로 티탄염을 사용하는 경우 인 제거효율이 기존에 사용하는 황산 알루미늄($Al_2(SO_4)_3$, Alum)과 유사하였다. 하향 침강방식의 침전조와 가압부상방식의 침전조 모두 기준치 이하로 모두 현장 적용이 가능하였다. 생성된 산화티탄의 성분은 원수에 포함된 무기물과 투입된 티탄염 성분으로 구성되었다. 티탄염 응집 후 생성된 슬러지를 소성하여 산화티탄을 제조하였다. 시판되고 있는 P-25 제품과 유사한 광촉매 활성을 가지고 있어 슬러지에서 생성된 산화티탄도 기존에 사용하는 제품시장에 대체 사용이 가능할 것으로 판단된다.

• 한국표면공학회지
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• 제19권4호
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• pp.133-139
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• 1986

The effects of alternating voltage, $Cl^-$ ion and pH on the corrosion of Zn and Zn-Fe alloys have been investigated by using electrochemical techniques in $Ca(OH)_2$ solutions. The passive film $Zn(OH)_2$ was initially formed on the Zn surface and gradually transformed to $Ca(Zn(OH)_3)_2{\cdot}2H_2O$, which was identified with the X-ray diffraction method, SEM micrograph and EPMA. The passivity current increased with increasing alternating voltage and decrease AC frequency. ${\xi}$ phase in Zn-Fe alloys reduced the effects of AC. The effect of $Cl^-$ ion on the passivity current of Zn was similar to the AC effect, resulting in pits on Zn. It was also found that the passive region of Zn decreased rapidly below pH 10.3 of the solution.

• 공업화학
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• 제33권4호
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• pp.425-430
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• 2022

L-alanine (LA, as an amino acid residue) pentamer model was used to investigate changes in the dihedral angle, intramolecular hydrogen bonding and formation energies during structural optimization. LA pentamers having four conformation types [𝛽: 𝜑/𝜓=t-/t+, 𝛼: 𝜑/𝜓=g-/g-, PP_II: 𝜑/𝜓=g-/t+ and P-like: 𝜑/𝜓= g-/g+] were carried out by quantum chemical calculations (QCC) [B3LYP/6-31G(d,p)]. In LA, 𝛽, 𝛼, and P-like types did not change by optimization, having an intra-molecular hydrogen bond: NH⋯OC (H-bond), and PP_II types in the absence of H-bond were transformed into P-like at the designated 𝜓 of 140°, and to 𝛽 at that of 160° or 175°. P-like and 𝛼 were about 0.5 kcal/mol/mu more stable than 𝛽. In order to understand the processes of the transformations, the changes of 𝜑/𝜓, distances of NH-OC (d_NH/CO) and formation energies (𝜟E, kcal/mol/mu) were examined.

• 통합자연과학논문집
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• 제16권1호
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• pp.39-45
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• 2023

P2X receptors are ATP-activated ion channels in the plasma membrane. P2X receptors have a role in a diverse range of disorders, making them a valuable therapeutic target. Hence, the present investigation employed homology modelling of the P2X receptor based on the crystal structure of 5SVJ, 6AH4, 5YVE and 5SVL. Twenty models, using both single- and multiple template-based methods, were developed, and the best model was chosen based on the validation result. We observed that a strategy based on multiple templates provided greater accuracy. Future studies involving binding site and docking analysis can make use of the produced structures.