• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.2
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• pp.189-197
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• 2014

This work proposes a 12b 100 MS/s $0.11{\mu}m$ CMOS three-step hybrid pipeline ADC for high-speed communication and mobile display systems requiring high resolution, low power, and small size. The first stage based on time-interleaved dual-channel SAR ADCs properly handles the Nyquist-rate input without a dedicated SHA. An input sampling clock for each SAR ADC is synchronized to a reference clock to minimize a sampling-time mismatch between the channels. Only one residue amplifier is employed and shared in the proposed ADC for the first-stage SAR ADCs as well as the MDAC of back-end pipeline stages. The shared amplifier, in particular, reduces performance degradation caused by offset and gain mismatches between two channels of the SAR ADCs. Two separate reference voltages relieve a reference disturbance due to the different operating frequencies of the front-end SAR ADCs and the back-end pipeline stages. The prototype ADC in a $0.11{\mu}m$ CMOS shows the measured DNL and INL within 0.38 LSB and 1.21 LSB, respectively. The ADC occupies an active die area of $1.34mm^2$ and consumes 25.3 mW with a maximum SNDR and SFDR of 60.2 dB and 69.5 dB, respectively, at 1.1 V and 100 MS/s.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.10 s.101
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• pp.1043-1049
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• 2005

In OFDM system suitable for high capacity high speed broadband transmission, ICI caused by phase noise degrades system performance seriously by destroying the orthogonality among subcarriers. In this paper, a new STFBC method combining ICI self cancellation scheme and antenna, time, frequency diversity is studied to reduce ICI effectively. CPE and ICI are analyzed by the phase noise linear approximation method in the proposed STFBC OFDM system. CIR, PICR and BER are discussed to compare the system performance degraded by phase noise of PLL. As results, STFBC method significantly reduces ICI. Furthermore, the SCI that usually happens in the traditional STBC, SFBC diversity coding method can be easily avoided.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.541-545
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• 2014

Rec. ITU-R M.1842-1 is international recommendation for VHF band communication guideline in maritime mobile service RR Appendix 18 channels. In this paper, we simulate 28.8 kbps VHF ${\pi}$/4-DQPSK digital baseband modem compatible with the recommendation, then it is designed and implemented with FPGA. Cazac sequence is used as a preamble since packet format is not defined untill now in the recommendation. Baseband modem is designed by VHDL language and implemented on NEXYS4 development platform having Atrix7 FPGA chip from Xilinx. For wireless communication test of total prototype system, ADC/DAC board is implemented and EV9730 RF module is utilized. From the experimental results, implemented FPGA modem shows spectral bandwidth of 25 kHz and successful data exchanges between tx and rx communication platform.

• Journal of KIISE:Information Networking
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• v.31 no.2
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• pp.188-195
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• 2004

We have analyzed the performance of TCP in the CDMA mobile communications systems with the adaptive modulation and coding(AMC). The wireless channel using AMC is characterized with not high error rate but highly varying bandwidth. Due to time-varying bandwidth, timeout events of TCP occurs more frequently, which leads to the throughput degradation. The analysis model is composed of the two parts. In the first part, we divide TCP packet stream into ‘packet groups’and derive the probability distribution of the wireless transmission time of each Packet group that reflects the time varying characteristics of AMC. In the second part, we formulate embedded Markov chain by making use of the results of the first part to model TCP timer mechanism and wireless transmission. Since our system model is characterized by the forward link high speed data transmission using AMC, the results reported in this paper can be used as a guideline for the design and operation of HSDPA, 1xEV-DO, and 1xEV-DV.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.11
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• pp.9-16
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• 2011

We need to establish standard for the ICT based on train control system. In order to solve the ISI problem, this paper evaluate the performance of OFDM and FDE system. We seem that OFDM system is better than FDE system. In order to solve ISI problem, SC System is needed a equalizer. And another method is OFDM System. If system is used SC with a equalizer, It is better than OFDM in terms of PAPR, but this system is not easy to use Multi-Antenna technique, i.e., beam-forming and MIMO-multiplexing. And If system is used high-order modulation, BER performance is worse than OFDM. If we think about in terms of PAPR problem, considerations are considered not significant because the size of relays is not considered in the communication between trains and ground.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3727-3734
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• 2012

An analytical method has been developed for the rapid determination of perfluorinated compounds (PFCs) in human serum samples. The extraction and purification of PFCs from human serum were performed by the modified method of previous report. Ten PFCs were rapidly separated within 3.3 min by C18-monolithic column liquid chromatography (LC) and detected by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) in negative ion mode. The runtime of PFCs on monolithic column LC was up to 4-fold faster than that on conventional column LC. The effect of triethylamine (TEA) to the mobile phase has investigated on the overall MS detection sensitivity of PFCs in ESI ionization. Quantification was performed by LC-MS/MS in multiple-ion reaction monitoring (MRM) mode, using $^{13}C$-labeled internal standards. Method validation was performed to determine recovery, linearity, precision, and limits of quantification, followed by, the analysis of a standard reference material (SRM 1957 from NIST). The overall recoveries ranged between 81.5 and 106.3% with RSDs of 3.4 to 16.2% for the entire procedure. The calibration range extended from 0.33 to 50 $ng\;mL^{-1}$, with a correlation coefficient ($R^2$) greater than 0.995 and the limits of quantification with 0.08 to 0.46 $ng\;mL^{-1}$. This approach can be used for rapid and sensitive quantitative analysis of 10 PFCs in human serum with high performance and accuracy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.174-174
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• 2008

Non-volatile memories using ferroelectric-gate field-effect transistors (Fe-FETs) with a metal/ferroelectric/semiconductor gate stack (MFS-FETs) make non-destructive read operation possible. In addition, they also have features such as high switching speed, non-volatility, radiation tolerance, and high density. However, the interface reaction between ferroelectric materials and Si substrates, i.e. generation of mobile ions and short retention, make it difficult to obtain a good ferroelectric/Si interface in an MFS-FET's gate. To overcome these difficulties, Fe-FETs with a metal/ferroelectric/insulator/semiconductor gate stack (MFIS-FETs) have been proposed, where insulator as a buffer layer is inserted between ferroelectric materials and Si substrates. We prepared $SrBi_2Ta_2O_9$ (SBT) film as a ferroelectric layer and $LaZrO_x$ (LZO) film as a buffer layer on p-type (100) silicon wafer for making the MFIS-FET devices. For definition of source and drain region, phosphosilicate glass (PSG) thin film was used as a doping source of phosphorus (P). Ultimately, the n-channel ferroelectric-gate FET using the SBT/LZO/Si Structure is fabricated. To examine the ferroelectric effect of the fabricated Fe-FETs, drain current ($I_d$) versus gate voltage ($V_g$) characteristics in logarithmic scale was measured. Also, drain current ($I_d$) versus drain voltage ($V_d$) characteristics of the fabricated SBT/LZO/Si MFIS-FETs was measured according to the gate voltage variation.

• Journal of radiological science and technology
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• v.28 no.2
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• pp.129-135
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• 2005

IT communication industries of current society are developed in enormous growth, our country leading the world in the number of super high speed internet equipments in use. In the pride oneself on communication network of those, mobile terminal technology and wireless phone production hold a high rank. Data communication and networking may be the fastest growing technologies in our culture today. In this way, IT fields conjugated in the daily quick, the fact that department of radiological science didn't discharged one's duties on current IT education. The curriculum of radiological technologists that play an important part between skill and occupation's education as major and personality didn't performed one's part most effectively on current IT environments and digital radiological equipments interface. Therefore, in this paper current curriculum of radiological science are catched hold of trend and problems on digital radiology environments, on fact the present state of problems, for radiological engineering and HIS manager, new curriculum course are suggested a reform measure of culture and major education curriculum introduction.

• Korean Journal of Pharmacognosy
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• v.34 no.3 s.134
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• pp.201-205
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• 2003

This paper is intended as an investigation of the analysis of high-performance liquid chromatography and the method of extraction of decursin and decursinol angelate in Angelica gigas roots. There are three kinds of extraction methods: distilled water, 50% EtOH and 100% EtOH. The condition of HPLC was obtained on a reversed-phase column $(Polarity\;dC_{18},\;4.6{\times}250 mm,\;5\;{\mu}m)$ using a phosphate buffer-acetonitrile-sodium lauryl sulfate as the mobile phase. Under these chromatographic conditions, UV detector was 230 nm, column temperature $30^{\circ}C$ and the speed of a current 1.0 ml/min, respectively. The results of extraction with distilled water, 50% EtOH and 100% EtOH in Angelica gigas roots were as follows. The concentrations of decursin and decursinol angelate were 182 and 153 ppm (distilled water), 3,142 and 2,547 ppm (50% EtOH) and 3,341 and 2,778 ppm (100% EtOH). There were high positive correlations between the concentrations of decursin and EtOH (r=0.8928, p<0.01) and decursinol angelate and EtOH (r=0.9009, p<0.01).

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.107-113
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• 2013

Mobile mobility and data reliability should be guaranteed as well as amounts of data services are essential in the era of smart media. In order to improve the reliability of high-speed data, strong channel coding and modulation techniques are required. In this paper, the structure of Turbo TCM decoder, applying high-order modulation techniques and the DPSAM method which improves performances in time-selective fading channels in the case of burst errors are suggested through the optimal decoding method and iteration decoding so as to improve bandwidth efficiency in Turbo Codes with excellent encoding gain. The proposed method in comparison with the existing method is that 3dB is superior in case that BER is $10^{-2}$ and the number of iterations is 3. In addition, the function is improved at approximately 6dB in case that BER is $10^{-3}$ and the number of iterations is 7. The proposed method requires additional bandwidth; however, the bandwidth loss can be overcome through Turbo TCM technology on the additional bit rate from the bandwidth loss.