• Development and Reproduction
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• v.7 no.2
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• pp.113-118
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• 2003

Follicular fluid(FF) of mammalian Graafian follicles contains various kinds of proteins and proteinases that are believed to play important roles during follicular growth oocyte maturation and ovulation of mature oocytes. Previous studies of human FF(hFF) demonstrated the presence of many serine/threonine proteinases and matrix metalloproteinases such as gelatinases, however, little is known about the caseinases. Present study was aimed to examine the presence and the property of caseinolytic enzyme in hFF. Using casein zymographic method, it was found that hFF, human adult serum and cord serum exhibited one intense 80 kDa and another weak 78 kDa bands having caseinolytic activity. When inhibitors were added to the zymographic substrate buffer, caseinolytic activity of both 80 kDa and 78 kDa proteins were inhibited by othylenediarnine tetraacetic acid(EDTA) or soybean trypsin inhibitor(SBTI), but not by E-64, phenylmethylsulfonyl fluoride(PMSF) or 1,10-phenanthroline. Thus both enzymes appear to belong to a family of trypsin-like enzyme. Addition of EDTA to the zymographic substrate buffer almost abolished the caseinolytic activity of both enzymes. However, further addition of a divalent metal ion such as CaC $l_2$, MgC $l_2$, MnC $l_2$ or ZnC $l_2$ to the same buffer fully restored the enzyme activity at 5 mM concentration despite the presence of EDTA. Based upon these observations, 80 kDa and 78 kDa caseinolytic enzymes are present in human follicular fluid and they appear to be trypsin-like enzymes of which caseinolytic activity needs the presence of $Ca^{++}$, aM $g^{++}$, M $n^{++}$ or Z $n^{++}$././././.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.162-162
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• 1999

초고주파 집적회로의 핵심소자로 각광을 받고 있는 GaAs MESFET(MEtal-emiconductor)은 게이트 형성 공정이 가장 중요하며, WNx 내화금속을 이용한 planar 게이트 구조의 경우 임계전압(Vth:threshold voltage)의 균일도가 우수할 뿐만 아니라 특히 Side-wall을 이용한 self-align 게이트는 소오스 저항을 줄일 수 있어 고성능의 소자 제작을 가능하게 한다.(1) 본 연구의 핵심이 되는 Side-wall을 형성하기 위하여 PECVD법에 의한 SiOx 박막을 증착하고, 건식식각법을 이용하여 SiOx side-wall을 형성하였다. 이 공정을 이용하여 소오스 저항이 낮고 임계전압의 균일도가 우수한 고성능의 self-aligned gate MESFET을 제작하였다. 3inch GaAs 기판상에 이온주입법에 의한 채널 형성, d.c. 스퍼터링법에 의한 WNx 증착, PECVD법에 의한 SiOx 증착, MERIE(Magnetic Enhanced Reactive Ion Etcing)에 의한 Side-wall 형성, LDD(Lightly Doped Drain)와 N+ 이온주입, 그리고 RTA(Rapid Thermal Annealing)를 사용하여 활성화 공정을 수행하였다. 채널은 40keV, 4312/cm2로, LDD는 50keV, 8e12/cm2로 이온주입하였고, 4000A의 SiOx를 증착한 후 2500A의 Side-wall을 형성하였다. 옴익 접촉은 AuGe/Ni/Au 합금을 이용하였고, 소자의 최종 Passivation은 SiNx 박막을 이용하였다. 제작된 소자의 전기적 특성은 hp4145B parameter analyzer를 이용한 전압-전류 측정을 통하여 평가하였다. Side-wall 형성은 0.3$\mu\textrm{m}$ 이상의 패턴크기에서 수직으로 잘 형성되었고, 본 연궁에서는 게이트 길이가 0.5$\mu\textrm{m}$인 MESFET을 제작하였다. d.c. 특성 측정 결과 Vds=2.0V에서 임계전압은 -0.78V, 트랜스컨덕턴스는 354mS/mm, 그리고 포화전류는 171mA/mm로 평가되었다. 특히 본 연구에서 개발된 트랜지스터의 게이트 전압 변화에 따른 균일한 트랜스 컨덕턴스의 특성은 RF 소자로 사용할 때 마이크로 웨이브의 왜곡특성을 없애주기 때문에 균일한 신호의 전달을 가능하게 한다. 0.5$\mu\textrm{m}$$\times$100$\mu\textrm{m}$ 게이트 MESFET을 이용한 S-parameter 측정과 Curve fitting 으로부터 차단주파수 fT는 40GHz 이상으로 평가되었고, 특히 균일한 트랜스컨덕턴스의 경향과 함께 차단주파수 역시 게이트 바이어스, 즉 소오스-드레스인 전류의 변화에 따라 균일한 값을 보였다. 본 연구에서 개발된 Side-wall 공정은 게이트 길이가 0.3$\mu\textrm{m}$까지 작은 경우에도 사용가능하며, WNx self-align gate MEESFET은 낮은 소오스저항, 균일한 임계전압 특성, 그리고 높고 균일한 트랜스 컨덕턴스 특성으로 HHP(Hend-Held Phone) 및 PCS(Personal communication System)와 같은 이동 통신용 단말기의 MMICs(Monolithic Microwave Integrates Circuits)의 제작에 활용될 것으로 기대된다.

• Journal of the Korean Applied Science and Technology
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• v.29 no.1
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• pp.108-115
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• 2012

Archaeological waterlogged woods found under the sea, in lakes, or in swamp environments are generally weak and fragile. If waterlogged wood materials were taken out of the water and left without modification, they would collapse and lose their original dimensions completely. Conservation is performed to replace the water with chemical agents and to give dimensional stabilization and durability. EDTA and PEG are the most commonly used in the preservation of wood. pH control-precipitation method is used for recovery of EDTA from waste fluid of archeological waterlogged wood conservation treatment. The black substance is eliminated from wood as Fe-EDTA complex are formed and EDTA is separated and precipitated from Fe-EDTA complexes at pH 2.68 or less. The result of analysis of the precipitated products and the commercial EDTA by FT-IR and FE-SEM showed that precipitated product by pH adjusted was not a type of Fe-EDTA complex, but pure EDTA. Waste fluid produced in PEG treatment shows the black color and has an offensive odor by organic matter extracted from wood. Color of waste fluid is decolored with oxidation reaction by peroxy hydrate. In FT-IR and SEM-EDX of PEG after freeze-drying process, no significant change of functional groups induced from oxidation is observed, and any metal ion does not exist in the solid PEG specimen. The molecular weight of PEG is measured using GPC and viscometry. Properties of PEG before and after preservation treatment, and after oxidation with $H_2O_2$ were not changed. Consequently, the peroxidation with $H_2O_2$ is a reasonable and simple method to decolor the used PEG solution.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.73-83
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• 2014

The objective of the this study was to investigate the binding capacity and removal ability of lactic acid bacterial strains obtained from Korean soybean paste for mutagenic heterocyclic amines (HCAs) formed during cooking of protein-rich food at high temperature. Among 19 strains identified by carbohydrate fermentation and 16S rRNA sequencing, the live cell or cell-free culture supernatant of Lactobacillus acidophilus D11, Enterococcus faecium D12, Pediococcus acidilactici D19, L. acidophilus D38, Lactobacillus sakei D44, Enterococcus faecalis D66, and Lactobacillus plantarum D70 inhibited the mutagenesis caused by either 3-amino-1,4-dimethyl-5H-pyrido[4,3-b] indole (Trp-P-1) or 3-amino-1-methyl-5H-pyrido[4,3-b] indole (Trp-P-2) in Salmonella typhimurium TA98 and TA100. The bacterial cells of the isolated strains showed greater binding activity than the pure cell wall, exopolysaccharide, and pepetidoglycan. The carbohydrate moieties of the cell wall or protein molecules on the cell surface have a significant role in binding Trp-P-1 and Trp-P-2, since protease, heating, sodium metaperiodate, or acidic pH treatments significantly (P<0.05) reduced the binding efficacy of the tested bacteria. Addition of metal ions or sodium dodecyl sulfate decreased the binding ability of E. faecium D12, L. acidophilus D38, and E. faecalis D66. Therefore, the binding mechanisms of these strains may consist of ion-exchange and hydrophobic bonds. Especially, the high mutagen binding by L. acidophilus D38 and L. plantarum D70 may reduce the accumulation or absorption of Trp-P-1 and Trp-P-2 in the small intestine via increased excretion of a mutagen-bacteria complex.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.319-322
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• 2003

To match the charge induced by the insulators $CeO_2$ with the remanent polarization of ferro electric SBT thin films, areas of Pt/SBT/Pt (MFM) and those of $Pt/CeO_2/Si$ (MIS) capacitors were ind ependently designed. The area $S_M$ of MIS capacitors to the area $S_F$ of MFM capacitors were varied from 1 to 10, 15, and 20. Top electrode Pt and SBT layers were etched with for various area ratios of $S_M\;/\;S_F$. Bottom electrode Pt and $CeO_2$ layers were respectively deposited by do and rf sputtering in-situ process. SBT thin film were prepared by the metal orgnic decomposition (MOD) technique. $Pt(100nm)/SBT(350nm)/Pt(300nm)/CeO_2(40nm)/p-Si$ (MFMIS) gate structures have been fabricated with the various $S_M\;/\;S_F$ ratios using inductively coupled plasma reactive ion etching (ICP-RIE). The leakage current density of MFMIS gate structures were improved to $6.32{\times}10^{-7}\;A/cm^2$ at the applied gate voltage of 10 V. It is shown that in the memory window increase with the area ratio $S_M\;/\;S_F$ of the MFMIS structures and a larger memory window of 3 V can be obtained for a voltage sweep of ${\pm}9\;V$ for MFMIS structures with an area ratio $S_M\;/\;S_F\;=\;6$ than that of 0.9 V of MFS at the same applied voltage. The maximum memory windows of MFMIS structures were 2.28 V, 3.35 V, and 3.7 V with the are a ratios 1, 2, and 6 at the applied gate voltage of 11 V, respectively. It is concluded that ferroelectric gate capacitors of MFMIS are good candidates for nondestructive readout-nonvolatile memories.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.77-77
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• 2017

Titanium and its alloys offer attractive properties in a variety of applications. These are widely used for the field of biomedical implants because of its good biocompatibility and high corrosion resistance. Titanium anodizing is often used in the metal finishing of products, especially those can be used in the medical devices with dense oxide surface. Based on SAE/AMS (Society of Automotive Engineers/Aerospace Material Specification) 2488D, it has the specification for industrial titanium anodizing that have three different types of titanium anodization as following: Type I is used as a coating for elevated temperature forming; Type II is used as an anti-galling coating without additional lubrication or as a pre-treatment for improving adherence of film lubricants; Type III is used as a treatment to produce a spectrum of surface colours on titanium. In this study, we have focused on Type II anodization for the medical (dental and orthopedic) application, the anodized surface was modified with gray color under alkaline electrolyte. The surface characteristics were analyzed with Focused Ion Beam (FIB), Scanning Electron Microscopy (SEM), surface roughness, Vickers hardness, three point bending test, biocompatibility, and corrosion (potentiodynamic) test. The Ti-6Al-4V alloy was used for specimen, the anodizing procedure was conducted in alkaline solution (NaOH based, pH>13). Applied voltage was range between 20 V to 40 V until the ampere to be zero. As results, the surface characteristics of anodic oxide layer were analyzed with SEM, the dissecting layer was fabricated with FIB method prior to analyze surface. The surface roughness was measured by arithmetic mean deviation of the roughness profile (Ra). The Vickers hardness was obtained with Vickers hardness tester, indentation was repeated for 5 times on each sample, and the three point bending property was verified by yield load values. In order to determine the corrosion resistance for the corrosion rate, the potentiodynamic test was performed for each specimen. The biological safety assessment was analyzed by cytotoxic and pyrogen test. Through FIB feature of anodic surfaces, the thickness of oxide layer was 1.1 um. The surface roughness, Vickers hardness, bending yield, and corrosion resistance of the anodized specimen were shown higher value than those of non-treated specimen. Also we could verify that there was no significant issues from cytotoxicity and pyrogen test.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.4
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• pp.32-39
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• 1986

A strain of Aspergillus niger CAD 1 which produces considerable amount of beta-galactosidase was selected from extracellular beta-galctaosidase producing fungi isolated from soil. Optimal conditions for the enzyme from Aspergillus niger CAD 1 were the growth in wheat bran supplemented with 0.5% skim milk powder at $30^{\circ}C$ for 72 hrs. The crude enzyme was purified 1,387 fold through DEAE-cellulosc and Sephadex G-100 chromatographr and its recovery was 6.2%, The optimal pH and temperature for the purified enzyme were pH 4.5 ana $45^{\circ}C$, respectively. The Km and Vmax on ONPG were $3.57{\times}10^3M$ and 33.0 unit/mg protein, whereas those on lacose were $83.3{\times}10^3M$and 15.33 unit/mg protein, respectively, The activation energy for the enzyme was 9,900 cal/mol and the enzyme had no metal ion requirement for its activity and stability. The hydrolysis of lactose in skim milk, 4.8% lactose solution and acidic whey were 65%, 70% and 78% after 10 hrs incubation at $45^{\circ}C$, when 182 units of the enzyme were used 50ml of the substrate solutions.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.189-195
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• 2009

$\beta-Ga_{2}O_{3}$ nanorods were synthesized by chemical vapor deposition method using nickel-oxide nanoparticle as a catalyst and gallium metal powder as a source material. The average diameter of nanorods was around 160 nm and the average length was $4{\mu}m$. Also, we confirmed that the synthesis of nanorods follows the vapor-solid growth mechanism. From the results of X-ray diffraction and HR-TEM observation, it can be found that the synthesized nanorods consisted of a typical core-shell structure with single-crystalline $\beta-Ga_{2}O_{3}$ core with a monoclinic crystal structure and an outer amorphous gallium oxide layer. Li/$\beta-Ga_{2}O_{3}$ nanorods cell delivered capacity of 867 mAh/g-$\beta-Ga_{2}O_{3}$ at first discharge. Although the Li/$\beta-Ga_{2}O_{3}$ nanorods cell showed low coulombic efficiency at first cycle, the cell exhibited stable cycle life property after fifth cycle.

• Journal of Microbiology and Biotechnology
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• v.30 no.5
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• pp.785-792
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• 2020

ʟ-Theanine, found in green tea leaves has been shown to positively affect immunity and relaxation in humans. There have been many attempts to produce ʟ-theanine through enzymatic synthesis to overcome the limitations of traditional methods. Among the many genes coding for enzymes in the ʟ-theanine biosynthesis, glutamylmethylamide synthetase (GMAS) exhibits the greatest possibility of producing large amounts of production. Thus, GMAS from Methylovorus mays No. 9 was overexpressed in several strains including vectors with different copy numbers. BW25113(DE3) cells containing the pET24ma::gmas was selected for strains. The optimal temperature, pH, and metal ion concentration were 50℃, 7, and 5 mM MnCl₂, respectively. Additionally, ATP was found to be an important factor for producing high concentration of ʟ-theanine so several strains were tested during the reaction for ATP regeneration. Baker's yeast was found to decrease the demand for ATP most effectively. Addition of potassium phosphate source was demonstrated by producing 4-fold higher ʟ-theanine. To enhance the conversion yield, GMAS was additionally overexpressed in the system. A maximum of 198 mM ʟ-theanine was produced with 16.5 mmol/l/h productivity. The whole-cell reaction involving GMAS has greatest potential for scale-up production of ʟ-theanine.

• Journal of Sensor Science and Technology
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• v.23 no.3
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• pp.185-191
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• 2014

The width of depletion region in a varactor diode can be modulated by varying a reverse bias voltage. Thus, the preferred characteristics of depletion capacitance can obtained by the change in the width of depletion region so that it can select only the desirable frequencies. In this paper, the TV tuner varactor diode fabricated by hyper-abrupt profile control technique is presented. This diode can be operated within 3.3 V of driving voltage with capability of UHF band tuning. To form the hyperabrupt profile, firstly, p+ high concentration shallow junction with $0.2{\mu}m$ of junction depth and $1E+20ions/cm^3$ of surface concentration was formed using $BF_2$ implantation source. Simulation results optimized important factors such as epitaxial thickness and dose quality, diffusion time of n+ layer. To form steep hyper-abrupt profile, Formed n+ profile implanted the $PH_3$ source at Si(100) n-type epitaxial layer that has resistivity of $1.4{\Omega}cm$ and thickness of $2.4{\mu}m$ using p+ high concentration Shallow junction. Aluminum containing to 1% of Si was used as a electrode metal. Area of electrode was $30,200{\mu}m^2$. The C-V and Q-V electric characteristics were investigated by using impedance Analyzer (HP4291B). By controlling of concentration profile by n+ dosage at p+ high concentration shallow junction, the device with maximum $L_F$ at -1.5 V and 21.5~3.47 pF at 0.3~3.3 V was fabricated. We got the appropriate device in driving voltage 3.3 V having hyper-abrupt junction that profile order (m factor) is about -3/2. The deviation of capacitance by hyper-abrupt junction with C0.3 V of initial capacitance is due to the deviation of thermal process, ion implantation and diffusion. The deviation of initial capacitance at 0.3 V can be reduced by control of thermal process tolerance using RTP on wafer.