• Proceedings of the KSMRM Conference
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• 1996.10a
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• pp.14-14
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• 1996

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.1121-1133
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• 1998

In this paper, a new method is proposed for a simple andaccurate design of larage-sigal power amplifier using the output current- and volage- waveform analysis. An existing high-efficiency theory, Harmonic Loading, is modified to apply to a real device, and the notion of "actual bias point at large-signal input" is proposed. Based on the proposed theory, 2GHz band poweramplifier is implemented using HEMT device, and the implemented amplifier shows 14dBm output power, 46% drain efficienty, 38% power-added efficiency and 7.8dB gain at 2V bias voltage.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1120-1127
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• 2013

In this paper, novel chip-on-chip(CoC) flip-chip bump structures using chip-on-wafer(CoW) process technology are proposed, designed and fabricated, and their microwave frequency responses are analyzed. With conventional bumps of Cu pillar/SnAg and Cu pillar/Ni/SnAg and novel Polybenzoxazole(PBO)-passivated bumps of Cu pillar/SnAg, Cu pillar/Ni/SnAg and SnAg with the deposition option of $2^{nd}$ Polyimide(PI2) layer on the wafer, 10 kinds of CoC samples are designed and their frequency responses up to 20 GHz are investigated. The measurement results show that the bumps on the wafers with PI2 layers are better for the batch flip-chip process and have average insertion loss of 0.14 dB at 18 GHz. The developed bump structures for chips with fine-pitch pads show similar or slightly better insertion loss of 0.11~0.14 dB up to 18 GHz, compared with that of 0.13~0.17 dB of conventional bump structures in this study, and we find that they could be utilized in various microwave packages for high integration density.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.4
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• pp.476-483
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• 1993

The moisture sorption characteristics of commercially produced seasoned dried layer (Porphyra yezoensis) was investigated by measuring sorption isotherms. The laver and two kinds of desiccant (silica gel and zeolite based desiccant) were used at temperatures of 30, 40 and 5$0^{\circ}C$ respectively using the method of saturated salt solution. Time to reach the equilibrium moisture content at each temperature and relative humidity varied from 4~6hr for the laver to 20~25hr for the silica gel and 43~46hr for the zeolite. The isotherms of the layer and the desiccants showed the characteristic sigmoidal curve. Monomolecular layer moisture content calculated using the BET equation at each temperature (30, 40, 5$0^{\circ}C$) were 5.26, 4.46 and 3.49% (d.b.) for the laver, 17.32, 15.24 and 12.89% (d.b.) for the silica gel, 16.89, 14.92 and 14.44% (d.b.) for the zeolite, respectively, Both desiccants showed higher values of the monomolecular layer moisture content than the laver. In all cases, the monomolerular layer moisture contents were decreased linearly as the temperature was increased in the experimental ranges. Water vapor transmission rate of the packaged material was also influenced by the temperature, which could be explained by the Arrhenius equation.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.51-57
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• 2015

In this paper, in order to design the A / D converter with a high resolution of 14 bits or more for the biological signal processing, CMOS delta sigma modulator that is a 1.8V power supply voltage - were designed. we propose a new structure of The fourth order delta-sigma modulator that needs four op amps but we use only two op amps. By using a time -interleaving technique, we can re-construct the circuit and reuse the op amps. Also, we proposed a KT/C noise reduction circuit to reduce the thermal noise from a noisy resistor. We adjust the size of sampling capacitor between sampling time and integrating time, so we can reduce almost a half of KT/C noise. The measurement results of the chip is fabricated using a Magna 0.18um CMOS n-well1 poly 6 metal process. Power consumption is $828{\mu}W$ from a 1.8V supply voltage. The peak SNDR is measured as a 75.7dB and 81.3dB of DR at 1kHz input frequency and 256kHz sampling frequency. Measurement results show that KT/C noise reduction circuit enhance the 3dB of SNDR. FOM of the circuit is calculated to be 142dB and 41pJ / step.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.3
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• pp.404-413
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• 2008

Major objectives were to evaluate effects of three schemes of bST-supplementation of Holstein cows (142.8 mg/14 d, POSILAC) during the prepartum and/or postpartum periods through 63 d (${\pm}3d$) of lactation. Measures evaluated the potential of treatments to improve body weight (BW) and body condition score (BCS), provoke changes in plasma concentrations of somatotropin (ST) and IGF-I, and improve milk yield, milk composition (percentages of protein and fat, and somatic cell counts), and several calving variables. Multiparous Holstein cows were randomly assigned to a $2{\times}2$ factorial arrangement of treatments (TRT) to give four groups (I = no bST, n = 26; II = bST postpartum, n = 25; III = bST prepartum, n = 27; IV = bST prepartum and postpartum, n = 25). During the prepartum period, cows in groups I and II were not supplemented but those in groups III and IV were supplemented every 2-wk beginning 21 d before expected calving date through calving. During the first 63 DIM only cows in groups II and IV were supplemented with bST. From 64 DIM through the end of lactation cows in all groups were supplemented with the full lactation dose of bST (500 mg/14 d). The BW and BCS were recorded weekly throughout the prepartum and postpartum periods and every 2-wk beyond 70 DIM. Blood samples were collected 3-times a week for analyses of ST and IGF-I. Milk yields were recorded daily though 150 DIM. Prepartum supplementation of bST did not affect BW or BCS, but mean concentrations of ST were increased 12.2% and were 15.5% greater at calving. Overall, mean concentration of IGF-I was not affected by treatment but concentrations were greater at 1 and 2 wk before calving in bST-supplemented cows. During the first 63 DIM the BW and BCS were not affected by treatment. Significant effects of bST-supplementation were detected on concentrations of ST, IGF-I and on milk yield compared to non-supplemented cows in group I. Postpartum concentrations of ST were greater in bST-supplemented cows (TRT II and IV; +41.9 and 54.6%). However, concentrations of IGF-I were greater only in cows in group IV (+25.9%) during the postpartum period. Overall, the three bST-supplemented groups had greater actual milk yield than the control group (I) during the first 63 and 150 DIM. The actual milk yields during 63 and 150 DIM were 6.5 and 4.6 kg/d greater for cows in group IV than cows in group I and the 305-d ME milk yield also was 15.6% greater. No adverse effects of TRT were observed on calf birth weight, colostrum immunoglobulins, ease of calving or other measures evaluated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.635-642
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• 2000

We have been derived theoretically the SER's and CLP's of Wireless ATM (WATM) cells employing an OFDM/16QAM modulation scheme in wireless channel modeled as a frequency selective Rayleigh fading channel. The amount of the performance improvement of WATM- OFDM/16QAM systems adopting various coding techniques has been evaluated. In frequency selective Rayleigh fading channel, considering CLP : $10^{-3}$ as a criterion, it is observed that the performance improvement of about 14 dB is obtained in terms of $E_b/N_o$ by employing an OFDM scheme. It is also confirmed that convolutional coding technique gives better performance than the other coding techniques. Especially, when the convolutional codes are adopted to WATM-OFDM/16QAM systems, voice transmission services are sufficiently available with 5 dB of $E_b/N_o$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.1-9
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• 2006

In this paper, a couple of 10Gb/s transimpedance amplifiers are realized in a 0.18um standard CMOS technology for optical communication applications. First, the voltage-mode inverter TIA(I-TIA) exploits inverter input configuration to achieve larger effective gm, thus reducing the input impedance and increasing the bandwidth. I-TIA demonstrates $56dB{\Omega}$ transimpedance gain, 14GHz bandwidth for 0.25pF photodiode capacitance, and -16.5dBm optical sensitivity for 0.5A/W responsivity, 9dB extinction ration and $10^{-12}$ BER. However, both its inherent parasitic capacitance and the package parasitics deteriorate the bandwidth significantly, thus mandating very judicious circuit design. Meanwhile, the current-mode RGC TIA incorporates the regulated cascade input configuration, and thus isolates the large input parasitic capacitance from the bandwidth determination more effectively than the voltage-mode TIA. Also, the parasitic components give much less impact on its bandwidth. RGC TIA provides $60dB{\Omega}$ transimpedance gain, 10GHz bandwidth for 0.25pF photodiode capacitance, and -15.7dBm optical sensitivity for 0.5A/W responsivity, 9dB extinction ration and $10^{-12}$ BER. Main drawback is the power dissipation which is 4.5 times larger than the I-TIA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1089-1097
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• 2002

In this paper, the novel shipboard Active Phased Array Antenna(APAA) system for maritime mobile satellite communications is introduced. The antenna uses novel technologies like wide range hybrid tracking, single antenna elements with both of Rx and Tx, asymmetrical array structure, interference isolation between Rx and Tx, and error correction method from frequency scan effect. The antenna has single aperture for both of Rx and Tx with 32 $\times$ 4 two-dimensional array. The antenna has two beams. Its frequencies are 7.25 ~ 7.75 GHz for Rx and 7.9 ~ 8.4 GHz for Tx. The antenna gains are 35.4 dBi for Rx and 35.7 dBi for Tx, those are 54 % of efficiency. The electrically steering ranges are $\pm$35$^{\circ}$ of elevation direction and $\pm$4$^{\circ}$ of azimuth direction. The mechanical control ranges at hybrid tracking capability are continuous 360$^{\circ}$ of azimuth direction and $\pm$10$^{\circ}$ of elevation direction. The antenna has 2.2$^{\circ}$ of 3 dB beamwidth, -14 dB of sidelobe level, and 21 dB of cross-pol suppression. The antenna performance was measured by near field measurement set. Its system performance was tested on the ship motion simulator and with the satellite transponder simulator. The test result showed that its tracking error was within -3 dB from its peak gain under motion condition. The antenna system was tested by real modulated Direct Broadcasting Satellite(DBS) signals to check its communication processing function.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.2
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• pp.147-155
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• 2002

This paper describes RF front-end transceiver chipset for the dual-mode operation of PCS-Korea and IMT-2000. The transceiver chipset has been implemented in a $0.25\mutextrm{m}$ single-poly five-metal CMOS technology. The receiver IC consists of a LNA and a down-mixer, and the transmitter IC integrates an up-mixer. Measurements show that the transceiver chipset covers the wide RF range from 1.8GHz for PCS-Korea to 2.1GHz for IMT-2000. The LNA has 2.8~3.1dB NF, 14~13dB gain and 5~4dBm IIP3. The down mixer has 15.5~16.0dB NF, 15~13dB power conversion gain and 2~0dBm IIP3. The up mixer has 0~2dB power conversion gain and 6~3dBm OIP3. With a single 3.0V power supply, the LNA, down-mixer, and up-mixer consume 6mA, 30mA, and 25mA, respectively.