• ETRI Journal
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• v.31 no.6
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• pp.749-754
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• 2009

The design and performance of an InGaAs/InP transimpedance amplifier and post amplifier for 40 Gb/s receiver applications are presented. We fabricated the 40 Gb/s transimpedance amplifier and post amplifier using InGaAs/InP heterojunction bipolar transistor (HBT) technology. The developed InGaAs/InP HBTs show a cut-off frequency ($f_T$) of 129 GHz and a maximum oscillation frequency ($f_{max}$) of 175 GHz. The developed transimpedance amplifier provides a bandwidth of 33.5 GHz and a gain of 40.1 $dB{\Omega}$. A 40 Gb/s data clean eye with 146 mV amplitude of the transimpedance amplifier module is achieved. The fabricated post amplifier demonstrates a very wide bandwidth of 36 GHz and a gain of 20.2 dB. The post-amplifier module was fabricated using a Teflon PCB substrate and shows a good eye opening and an output voltage swing above 520 mV.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.553-554
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• 2006

In this paper, 77 GHz CPW power amplifier MMIC, which are consisted of a 2 stage driver stage and a power stage employing $8{\times}50um$ gate width, have been successfully developed by using 120nm $In_{0.4}AlAs/In_{0.35}GaAs$ Metamorphic high electron mobility transistors (MHEMTs). The devices show an extrinsic transconductance $g_m$ of 660 mS/mm, a maximum drain current of 700 mA/mm, and a gate drain breakdown voltage of -8.5 V. A cut-off frequency ($f_T$) of 172 GHz and a maximum oscillation frequency ($f_{max}$) of over 300 GHz are achieved. The fabricated PA exhibited high power gain of 20dB only with 3 stages. The output power is measured to be 12.5 dBm.

• Archives of Pharmacal Research
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• v.27 no.2
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• pp.254-258
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• 2004

The purpose of this study was to investigate the pharmacokinetic alteration of diltiazem and its main metabolite, deacetyldiltiazem, after oral administration of diltiazem in rabbits with or with-out cimetidine co-administration. The area under the plasma concentration-time curve (AUC) of diltiazem was significantly elevated in rabbits pretreated with cimetidine, suggesting that the oral clearance, an index of intrinsic clearance, may be decreased by the cimetidine treatment. Consistent with the increased AUC by the treatment, peak plasma concentration ($C_{max}$) for diltiazem was also elevated. Apparent volume of distribution normalized by the bioavailability (($V_{d}$/F) of diltiazem increased sigrificantly in rabbits pretreated with cimetidine increased. Taken together with the fact that the first pass metabolism for diltiazem is the primary determinant for the oral bioavailability, these observations indicate that increases in the oral clearance and (($V_{d}$/F may be a manifestation of the decreased first pass metabolism. Consistent with the hypothesis, the AUC of deacetyldiltiazem was significantly decreased in rabbits with cimetidine treatment. Ratio of deacetyldiltiazem to total diltiazem in the plasma was significantly decreased in rabbits with cimetidine treatment. These observations suggested that the metabolism of diltiazem to deacetyldiltiazem was reduced by cimetidine treatment and that the dosage of diltiazem should be adjusted when the drug is co-administered chronically with cimetidine in a clinical setting.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.780-781
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• 2014

본 논문에서는 차량 추돌 방지 단거리 레이더용 고 변환이득 및 저전력 24GHz CMOS 믹서를 제안한다. 이러한 회로는 2볼트 전원전압에서 동작하며, 저 전압 전원 공급에서도 높은 변환 이득과 낮은 잡음지수를 가지도록 설계되어 있다. 제안한 회로는 TSMC $0.13{\mu}m$ 혼성신호/고주파 CMOS 공정($f_T/f_{MAX}=120/140GHz$)으로 설계하였다. 전체 칩 면적을 줄이기 위해 실제 수동형 인덕터 대신 전송선을 이용하였다. 제안한 회로는 최근 발표된 연구결과에 비해 가장 높은 10.96dB의 변환이득, 7.6dBm의 IIP3를 보였고, 가장 적은 5mW의 소비전력 및 $0.2{\times}0.2m^2$의 칩 크기 특성을 보였다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.357-365
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• 2016

The effects of elevated atmospheric $CO_2$ on photosynthesis and growth of Chinese cabbage (Brassica campestris subsp. napus var. pekinensis) were investigated to predict productivity in highland cropping in an environment where $CO_2$ levels are increasing. Vegetative growth, based on fresh weight of the aerial part, and leaf characteristics (number, area, length, and width) of Chinese cabbage grown for 5 weeks, increased significantly under elevated $CO_2$ ($800{\mu}mol{\cdot}mol^{-1}$) compared to ambient $CO_2$ ($400{\mu}mol{\cdot}mol^{-1}$). The photosynthetic rate (A), stomatal conductance ($g_s$), and water use efficiency (WUE) increased, although the transpiration rate (E) decreased, under elevated atmospheric $CO_2$. The photosynthetic light-response parameters, the maximum photosynthetic rate ($A_{max}$) and apparent quantum yield (${\varphi}$), were higher at elevated $CO_2$ than at ambient $CO_2$, while the light compensation point ($Q_{comp}$) was lower at elevated $CO_2$. In particular, the maximum photosynthetic rate ($A_{max}$) was higher at elevated $CO_2$ by 2.2-fold than at ambient $CO_2$. However, the photosynthetic $CO_2$-response parameters such as light respiration rate ($R_p$), maximum Rubisco carboxylation efficiency ($V_{cmax}$), and $CO_2$ compensation point (CCP) were less responsive to elevated $CO_2$ relative to the light-response parameters. The photochemical efficiency parameters ($F_v/F_m$, $F_v/F_o$) of PSII were not significantly affected by elevated $CO_2$, suggesting that elevated atmospheric $CO_2$ will not reduce the photosynthetic efficiency of Chinese cabbage in highland cropping. The optimal temperature for photosynthesis shifted significantly by about $2^{\circ}C$ under elevated $CO_2$. Above the optimal temperature, the photosynthetic rate (A) decreased and the dark respiration rate ($R_d$) increased as the temperature increased. These findings indicate that future increases in $CO_2$ will favor the growth of Chinese cabbage on highland cropping, and its productivity will increase due to the increase in photosynthetic affinity for light rather than $CO_2$.

• Journal of Ginseng Research
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• v.36 no.4
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• pp.418-424
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• 2012

This study focused on the enzymatic biotransformation of the major ginsenoside Rb1 into Rd for the mass production of minor ginsenosides using a novel recombinant ${\beta}$-glucosidase from Flavobacterium johnsoniae. The gene (bglF3) consisting of 2,235 bp (744 amino acid residues) was cloned and the recombinant enzyme overexpressed in Escherichia coli BL21(DE3) was characterized. This enzyme could transform ginsenoside Rb1 and gypenoside XVII to the ginsenosides Rd and F2, respectively. The glutathione S-transferase (GST) fused BglF3 was purified with GST-bind agarose resin and characterized. The kinetic parameters for ${\beta}$-glucosidase had apparent $K_m$ values of $0.91{\pm}0.02$ and $2.84{\pm}0.05$ mM and $V_{max}$ values of $5.75{\pm}0.12$ and $0.71{\pm}0.01{\mu}mol{\cdot}min^{-1}{\cdot}mg$ of $protein^{-1}$ against p-nitrophenyl-${\beta}$-D-glucopyranoside and Rb1, respectively. At optimal conditions of pH 6.0 and $37^{\circ}C$, BglF3 could only hydrolyze the outer glucose moiety of ginsenoside Rb1 and gypenoside XVII at the C-20 position of aglycon into ginsenosides Rd and F2, respectively. These results indicate that the recombinant BglF3 could be useful for the mass production of ginsenosides Rd and F2 in the pharmaceutical or cosmetic industry.

• Food Science and Preservation
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• v.24 no.6
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• pp.778-785
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• 2017

This study was conducted to develop a predictive model for the growth of Escherichia coli strain RC-4-D isolated from red kohlrabi sprout seeds. We collected E. coli kinetic growth data during red kohlrabi seed sprouting under isothermal conditions (10, 15, 20, 25, and $30^{\circ}C$). Baranyi model was used as a primary order model for growth data. The maximum growth rate (${\mu}max$) and lag-phase duration (LPD) for each temperature (except for $10^{\circ}C$ LPD) were determined. Three kinds of secondary models (suboptimal Ratkowsky square-root, Huang model, and Arrhenius-type model) were compared to elucidate the influence of temperature on E. coli growth rate. The model performance measures for three secondary models showed that the suboptimal Huang square-root model was more suitable in the accuracy (1.223) and the suboptimal Ratkowsky square-root model was less in the bias (0.999), respectively. Among three secondary order model used in this study, the suboptimal Ratkowsky square-root model showed best fit for the secondary model for describing the effect of temperature. This model can be utilized to predict E. coli behavior in red kohlrabi sprout production and to conduct microbial risk assessments.

• Water for future
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• v.14 no.4
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• pp.53-72
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• 1981

In this study, South Korea is divided into 5 zones and is studied about the analysis of time-regional distribution of previpitation frequency and rainfall intensity in Korea. In the previpitation frequency analysis, the basic data groups of 39 stations were selected. The diagram of previpitation frequency was drawn, and the time-regional distribution of precipitation frequency was analized. In the rainfall intensity analysis, the basic data groups of 36 stations were selected. The probable rainfall, I-D-F curve, and regression equation between 24hr. and 10min.-18hr. areal depth were obtained. The results of this study are following; 1) The precipitation class of max. recurrence probability in every season except summer was commonly (1) 1-5mm, (2) 0.1-1mm, (3) 5-10mm in order. 2) The zone of max. recurrence frequency owing to the precipitation class was zone II in precipitation frequency of below 20mm, zone IV in precipitation frequency of 30-40mm, zone I in precipitation frequency of above 70mm for a year. 3) The recurrence probability of precipitation in Korea can be represented to the equation of exponential function; $$W(x)=e^{\alpha+\beta}$$ 4) The first and third zones were expected heavy rain for the short and long duration. 5) The I.D.F. curves were drawn, and established that the time interval for the least deviation of I.D.F curve is 10~40min., 40min. -4hr., 4~24hr. 6) The regression equations of areal mean depth between 24hr. and 10min.-18hr. for each zone were obtained. 7)The probable rainfall of 36 points were calculated.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.10
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• pp.33-46
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• 2015

In this paper, we predicts the analog and digital circuit performance of FinFETs that are scaled down following the ITRS(International technology roadmap for semiconductors). For accurate prediction of the circuit performance of scaled down devices, accurate parasitic resistance and capacitance analytical models are developed and their accuracies are within 2 % compared to 3D TCAD simulation results. The parasitic capacitance models are developed using conformal mapping, and the parasitic resistance models are enhanced to include the fin extension length($L_{ext}$) with respect to the default parasitic resistance model of BSIM-CMG. A new algorithm is developed to fit the DC characteristics of BSIM-CMG to the reference DC data. The proposed capacitance and resistance models are implemented inside BSIM-CMG to replace the default parasitic model, and SPICE simulations are performed to predict circuit performances such as $f_T$, $f_{MAX}$, ring oscillators and common source amplifier. Using the proposed parasitic capacitance and resistance model, the device and circuit performances are quantitatively predicted down to 5 nm FinFET transistors. As the FinFET technology scales, due to the improvement in both DC characteristics and the parasitic elements, the circuit performance will improve.

• Korean Journal of Environment and Ecology
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• v.35 no.6
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• pp.632-643
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• 2021

The objective of this study was to examine vegetation community structure and distribution of Fraxinus chiisanensis in Mt.Minjuji of Chungcheongbuk-do by setting up and surveying 8 plots (400 m² each). Mean Importance Value (MIV) of Fraxinus chiisanensis in 8 plots was 35.19% in average (ranging from 26.07~42.74%). Since it is the dominant species in all plots, it is expected to maintain the present vegetation structure. The analysis of the DBH (diameter at breast height) showed that the diameter of Fraxinus chiisanensis in Mt.Minjuji ranges from 2 to 43cm. The majority of Fraxinus chiisanensis is expected to maintain current state unless disturbance or rapid environmental change occurs. The Species Diversity (H') was 0.8498~1.0261, Evenness (J') was 0.8160~0.9256, Dominance Index (D) was 0.0789~0.1840, Maximum Diversity (H'max) was 1.0414~1.2041. The analysis of annual ring and radial growth showed that the average age of Fraxinus chiisanensis in Mt.Minjuji was 29.1years(ranging from 22~58years). The average annual radial growth of Fraxinus chiisanensis was the highest in community G with 5.84mm and the lowest in community B with 2.80mm. The similarity index analysis revealed that the similarity index between community B and E, C and F, H was the highest with 69.0%, and the similarity index between community E and F was the lowest with 29.6%. Both the area of Fraxinus chiisanensis community of Mt.Minjuji and its population size are very small. Therefore, this area needs to be designated as Forest Genetic Resource Reserve.