• The Journal of the Acoustical Society of Korea
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• v.16 no.4
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• pp.76-84
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• 1997

In this paper, one of the core components of a mobile communication system, VCO(Voltage Controlled Oscillator) IC is designed. The VCO IC was designed, have realized as LC turned oscillator using varicap. LC sinusoidal tuned oscillator generally requires external inductors and thus remainding circuit is implemneted in monolithic IC. The circuit is fabricated using an 15 mask IC process and has a die size of 1150um${\times}$780um. The tests showed that VCO was operated at frequencies in the regions between 880MHz-915MHz in the control voltage range of 1V to 3V at 5V supply voltage and as the power supply was varied from 4.5V to 5.5V, the frequency varied 425KHz/V. The VCO IC has frequency shift of 1.97MHz/T, carrier level of -7dBm and power consumption of 16.7mA. Also it has phase noise of -80dBc/Hz, offset at 50KHz and harmonic response of center frequency is -41dBm. For the future development of the transceiver 1 chip, the previously mentioned external devices need to be incorporated into Si MMIC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.925-932
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• 2009

Precise temperature monitoring is the major preconditioning to supervise quality losses within the transport chain for fresh products. ISO/IEC18000-6REV1 defines new protocols supporting BAP(Battery Assisted Passive) RFID tag which is completely compatible with EPCglobal Class1 Generation2 specification. In this paper, we designed a modem supporting BAP RFID tag with FPGA(Field Programmable Gate Array) and implemented sensor data processing function defined in ISO/IEC18000-6REV1. The transmit block of the modem supports pulse shaping filter and the output signal of the implemented RFID reader is satisfied with the spectrum mask defined in the standard. The receive block of the modem uses Gardner TED to synchronize timing of symbol. In this paper, we designed a modem supporting ISO/IEC18000-6REV1 standard and developed a RFID reader sndard. The developed RFID reader sndard can recognize sensor tag and passive tag in the wireless environment and supports real-time processing of the sensor data in the embedded linux platform.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.510-518
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• 2010

In this paper, the designed and implemented results of CFL linearization chip which can be used in mobile radio and TRS terminal of UHF band(380~910 MHz), using $0.6\;{\mu}m$ BiCMOS process based on Si, are shown. As gain control circuits for modifying transmit power are inserted not only in feedback path but also in forward path, the stability of CFL is maintained. And, DC-offset correction function of S/H structure, which is suitable for walkie-talkie PTT operation and is easily implemented, is realized. The performance test results of transmitter show that the regulation of FCC emission mask at PEP 3 W(34.8 dBm) is satisfied when the CQPSK modulated signal is fed and more than 30 dBc improvement of 3rd order IMD is achieved when two-tone signal is inputted.

• The Journal of the Acoustical Society of Korea
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• v.20 no.7
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• pp.37-46
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• 2001

This paper proposes a new noise suppression method using the Wavelet transform analysis. The noise suppressor using the Wavelet transform shows the more effective advantages in a babble noise than one using the short-time Fourier transform. We designed a new channel structure based on spectral subtraction of Wavelet transform coefficients and used the Wavelet mask pattern with more higher time resolution in high frequency. It showed a good adaptation capability for babble noise with a non-stationary property. To evaluate the performance of proposed noise canceller, the informal subjective listening tests (Mos tests) were performed in background noise environments (car noise, street noise, babble noise) of mobile communication. The proposed noise suppression algorithm showed about MOS 0.2 performance improvements than the suppression algorithm of EVRC in informal listening tests. The noise reduction by the proposed method was shown in spectrogram of speech signal.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.79-85
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• 2004

We report on a transmittance controlled photomask with phase patterns on the back quartz surface. Theoretical analysis for changes in illumination pupil shape with respect to the variation of size and density of backside phase patterns and experimental results for improvement of critical dimension uniformity on a wafer by using the transmittance controlled photomask are presented. As phase patterns for controlling transmittance of the photomask we used etched contact-hole type patterns with 180" rotative phase with respect to the unetched region. It is shown that pattern size on the backside of the photomask must be made as small as possible in order to keep the illumination pupil shape as close as possible to the original pupil shape and to achieve as large an illumination intensity drop as possible at a same pattern density. The distribution of illumination intensity drop suitable for correcting critical dimension error was realized by controlling pattern density of the contact-hole type phase patterns. We applied this transmittance controlled photomask to a critical layer of DRAM (Dynamic Random Access Memory) having a 140nm design rule and could achieve improvement of the critical dimension uniformity value from 24.0 nm to 10.7 nm in 3$\sigma$.TEX>.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.948-953
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• 2017

When using a high-power amplifier(HPA) for high-speed communication, the nonlinear characteristics of the HPA deteriorate power efficiency, bit error rate(BER) performance, and spectral efficiency. Because it is inevitable to use the HPA to obtain sufficient transmission power for high-speed communication, it is necessary to compensate for nonlinearity of the HPA by using a predistorter. In this study, a predistorter was used to compensate for the nonlinearity of the HPA, and the nonlinear distortion was compensated using the predistorter. Simulation results show that the compensation of the nonlinearity of the HPA using the predistorter achieves a BER performance similar to that of an ideal linear amplifier, and that the spectral mask is also satisfied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2335-2341
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• 1999

The $2\times32$ coupler consists of Mach-Zehnder interferometer and Y branch coupler. For the designs of this coupler, three dimensional rectangular core waveguide decomposed to two-dimensional structure by the effective index method. To optimize the waveguide structure, the confinement factor was investigated with two-dimensional finite difference Beam Propagation Method. The $2\times32$ coupler fabricated by simulation with height between Mach-Zehnder arms, H=$43.6\mu\textrm{m}$(path difference $0.668\mu\textrm{m}$) was showed best characteristics. In the results of dry etching of core layer, the etching rate of core layer was above 2600${\AA}$/min, the etching ratio of SiO2 to Al mask was 30:1 and the uniformity of etching was $\pm$5%. The maximum insertion loss and the uniformity of $2\times32$ coupler were below 19.2dB, 2dB respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.384-390
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• 2008

Chaotic OOK modulation method can be used in LDR(Low Data Rate) UWB systems. In this paper, UWB chaotic-OOK transmitter system is designed and verified using TSMC 0.18 um CMOS process. A transmitter system is composed of Quasi-chaotic signal generator, OOK Modulator, and driving amplifier. The traditional chaotic signal generators using analog feedback method is weak to process variation. In order to solve this problem, a quasi-chaotic signal generator using digital feedback technique is get wide band signal and OOK Modulator using T-type switching structure is used to enhance the isolation characteristic. A driving amplifier has differential to single structure to avoid an external balun for low cost communication. The measured output power spectrum of the transmitter meet the FCC regulation and the result of the modulation test at data rate of 20 Kbps, 200 Kbps, 2 Mbps, and 10 Mbps is conformed to LDR UWB system. It is shown that the transmitter in this paper can be used for the UWB chaotic-OOK system.

• Journal of Korean Biological Nursing Science
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• v.18 no.4
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• pp.257-263
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• 2016

Background: This study purposed to examine how the incidence of the central line-associated bloodstream infection (CLABSI) in a operating room (OR) is affected by bundle application on central line insertion (CLI) practice. Methods: The study design was a pretest-posttest experimental trial. The subjects were 83 patients before the bundle application on CLI and 70 patients after. Results: The compliance(%) of bundle on CLI of among those who observed all of the five items increased from 7.2% before the intervention to 72.9% after. By items, compliance with the maximal barrier precaution was 100% for the use of a mask and cap before and after the intervention, but increased from 73.5% before the intervention to 88.6% after for the hand hygiene, from 73.5% to 88.6% for the use of a sterile gown, and from 9.6% to 75.7% for the use of a sterile large drape covering the whole body. CLABSI did not happen on CLI either before or after the application of the bundle intervention. Conclusion: Bundle application increased compliance with the use of a sterile gown and the use of a sterile large drape. However, its effect in the prevention of CLABSI was not clear probably due to the short period of intervention in a single hospital.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.5
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• pp.21-28
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• 1999

A new method of making high speed self-aligned ESD (Elevated Source/Drain) MOSFET is proposed. Different from the conventional LDD (Lightly-Doped Drain) structure, the proposed ESD structure needs only one ion implantation step for the source/drain junctions, and makes it possible to modify the depth of the recessed channel by use of dry etching process. This structure alleviates hot-carrier stress by use of removable nitride sidewall spacers. Furthermore, the inverted sidewall spacers are used as a self-aligning mask to solve the self-align problem. Simulation results show that the impact ionization rate ($I_{SUB}/I_{D}$) is reduced and DIBL (Drain Induced Barrier Lowering) characteristics are improved by proper design of the structure parameters such as channel depth and sidewall spacer width. In addition, the use of removable nitride sidewall spacers also enhances hot-carrier characteristics by reducing the peak lateral electric field in the channel.