• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.60-68
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• 2009

This work proposes a 10b 200MS/s 65nm CMOS ADC for high-definition video systems such as HDTV requiring high resolution and fast operating speed simultaneously. The proposed ADC employs a four-step pipeline architecture to minimize power consumption and chip area. The input SHA based on four capacitors reduces the output signal range from $1.4V_{p-p}$ to $1.0V_{p-p}$ considering high input signal levels at a low supply voltage of 1.2V. The proposed three-stage amplifiers in the input SHA and MDAC1 overcome the low output resistance problem as commonly observed in a 65nm CMOS process. The proposed multipath frequency-compensation technique enables the conventional RNMC based three-stage amplifiers to achieve a stable operation at a high sampling rate of 200MS/s. The conventional switched-bias power-reduction technique in the sub-ranging flash ADCs further reduces power consumption while the reference generator integrated on chip with optional off-chip reference voltages allows versatile system a locations. The prototype ADC in a 65nm CMOS technology demonstrates a measured DNL and INL within 0.19LSB and 0.61LSB, respectively. The ADC shows a maximum SNDR of 54.BdB and 52.4dB and a maximum SFDR of 72.9dB and 64.8dB at 150MS/S and 200MS/s, respectively. The proposed ADC occupies an active die area of $0.76mm^2$ and consumes 75.6mW at a 1.2V supply voltage.

• The Journal of the Acoustical Society of Korea
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• v.30 no.3
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• pp.158-166
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• 2011

In the present study, copper and nickel foams with an open-celled structure as trabecular-bone-mimicking phantoms were used to investigate the dependencies of group velocity and attenuation coefficient on structural properties such as trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp) in trabecular bone. The group velocity and attenuation coefficient of the copper and nickel foams were measured by a through-transmission method in water, using a pair of broadband, unfocused transducers with a diameter of 12.7 mm and a center frequency of 1.0 MHz. The separation of the Biot's fast and slow waves was consistently observed in the ultrasonic signals transmitted through the copper and nickel foams. The group velocities of the copper and nickel foams showed highly positive correlations with Tb.Th and Tb.Sp. The attenuation coefficient of the copper foam showed a highly negative correlation with Tb.Th and Tb.Sp, whereas that of the nickle foam showed a highly positive correlation with Tb.Th and Tb.Sp. These results advance our understanding of those previously reported by other researchers using trabecular bone samples or phantoms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.624-629
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• 2018

The current study was conducted to develop a portable composite gas detector allowing the detection of both $CO_2$ and $CH_4$ gases by means of the Non Dispersive Infra-Red (NDIR) method. The gas detector is configured to radiate infrared waves using infrared lamps, where the wavelength of the infrared light is reduced due to absorption throughout the chamber, and this reduction (absorption) is detected by the absorption detector, before being converted and amplified to a 3.5V~6V electrical signal, providing as accurate a measurement as possible. The conventional singe sensor method measures the relative measurement by absorbing only specified wavelengths of infrared radiation, which in the case of gas detection leads to problems with accuracy due to the lack of a reference sensor when detecting light with a wavelength of only $4.26{\mu}m$. The dual sensor employed in this study provides a comparative measurement between the reference value derived from the wavelength of $3.91{\mu}m$, which is not influenced by other gas sources, and the measurement value derived from the wavelength of $4.26{\mu}m$, in order to reduce the errors and enhance the reliability, thereby allowing low power consumption for portable devices and multi-gas detection for both $CO_2$ and $CH_4$ gases. The portable composite gas detector developed herein provides a measurement rage of 0ppm~5,000ppm for $CO_2$ gas, and 0.5%vol for $CH_4$, which allows the determination of whether the $CO_2$ and $CH_4$ contents in indoor air are less than 1,000ppm or not. The current study established that the composite gas detector can be interlinked with firefighting appliances through portable devices or home automation, and is anticipated to be very effective in fire prevention.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.2
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• pp.105-114
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• 2007

Two-dimensional imaging of $V_s$ profile becomes more important in Korea because of the large horizontal variation of soil stiffness. To obtain a shear-wave velocity profile in geotechnical practice, various seismic nondestructive investigation methods are being frequently used. In this study, harmonic wavelet analysis of wave (HWAW) method is applied to the determination of $V_s$ profile to overcome some of weaknesses in the existing surface wave methods. HWAW method which is based on time-frequency analysis using harmonic wavelet transform has been developed to determine phase and group velocities of waves. Field testing of this method is relatively simple and fast because one experimental setup which consists of one pair of receivers is needed to determine $V_s$ profile of site. The proposed method uses the signal portion of the maximum local signal/noise ratio to evaluate the phase velocity to minimize the effects of noise, and uses single array inversion which considers receiver locations. Field tests were performed in 2 sites in order to evaluate accuracy of test method and estimate the applicability of 2-D imaging by HWAW method. Through field applications and comparison with other test results, the good accuracy and applicability of the proposed method were verified.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.93-100
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• 2009

This paper presents a step up four channel DC-DC converter using charge pump voltage doubler structure. Our goal is to design and implement DC-DC converter for capacitive SP4T RF MEMS switch in front end module in wireless transceiver system. Charge pump structure is small and consume low power 3.3V input voltage is boosted by DC-DC Converter to $11.3{\pm}0.1V$, $12.4{\pm}0.1V$, $14.1{\pm}0.2V$ output voltage With 10MHz switching frequency. By using voltage level shifter structure, output of DC-DC converter is selected by 3.3V four channel selection signals and transferred to capacitive MEMS devices. External passive devices are not used for driving DC-DC converter. The total chip area is $2.8{\times}2.1mm^2$ including pads and the power consumption is 7.52mW, 7.82mW, 8.61mW.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.10
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• pp.39-50
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• 1998

Wide-band sharp-transition filters are widely used in applications such as wireless CODEC design or medical systems. Since these filters suffer from large sensitivity and roundoff noise, large word-length is required for the VLSI implementation, which increases the hardware size and the power consumption of the chip. In this paper, a low-power implementation technique for digital filters with wide-band sharp-transition characteristics is proposed using CPL (Complementary Pass-Transistor Logic), LWDF (Lattice Wave Digital Filter) and a modified DIFIR (Decomposed & Interpolated FIR) algorithm. To reduce the short-circuit current component in CPL circuits due to threshold voltage reduction through the pass transistor, three different approaches can be used: cross-coupled PMOS latch, PMOS body biasing and weak PMOS latch. Of the three, the cross-coupled PMOS latch approach is the most realistic solution when the noise margin as well as the energy-delay product is considered. To optimize CPL transistor size with insight, the empirical formulas for the delay and energy consumption in the basic structure of CPL circuits were derived from the simulation results. In addition, the filter coefficients are encoded using CSD (Canonic Signed Digit) format and optimized by a coefficient quantization program. The hardware cost is minimized further by a modified DIFIR algorithm. Simulation result shows that the proposed method can achieve about 38% reductions in power consumption compared with the conventional method.

• Annual Conference on Human and Language Technology
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• 1994.11a
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• pp.57-63
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• 1994

인간의 정보처리 과정의 특성을 알아보기 위하여 반구별로 색채와 단어의 처리과정을 분석하였다. 단어와 색깔이라는 두가지 자극 속성이 있는 한 개의 자극에 대하여 각 자극 속성에 대한 판단과정을 반응키를 이용하여 반구별로 알아보았다. 단어에 대한 판단과 색깔에 대한 판단을 반구별로 분석한 결과, 색깔처리나 단어처리에 있어서 반구간 비대칭성은 나타나지 않았으나 색깔에 대한 판단이 단어에 대한 판단보다 신속하게 이루어지는 것으로 나타나 색채가 단어보다 기초적인 자극 속성임을 확인하였다. 단어와 색깔이라는 두가지 자극 속성을 이용한 경우에 한가지 자극속성을 처리할 때 다른 자극속성이 자동적으로 영향을 주는 것으로 나타났으나 그 정도에 있어서 반구간의 차이는 없었다. 그러나 색채가 단어처리를 간섭하는 정도가 단어가 색채처리를 간섭하는 정도보다 큰 것으로 나타나 기존의 스트룹 연구결과들과는 상반되는 결과를 얻었는데 이는 과제의 특성이라는 측면으로 기술되었다. 단어 처리에서 반구간 차이가 발견되지 않은 것은 한글의 시각적 특성과 관련지어 논의되었다. 자극의 한 속성이 자동적으로 다른 속성에 영향을 주지만 그 효과의 크기도 반구별로 차이가 없다는 것은 이전의 반구별 스트룹 효과를 알아본 연구들과 상반되는 결과이다. 따라서 자극속성이 상호영향을 줄 수 있는 좀더 일반적인 상황에서는 한 자극 속성이 다른 자극 속성의 처리에 자동적으로 영향을 주는 효과에서 반구 비대칭성이 발견되지 않으며 스트룹 효과는 두 자극 속성의 관계가 밀접한 특별한 경우에 나타나는 반구비대칭성 효과인 것으로 논의되었다.양 발생과 유의적으로 상관관계가 있었다. 본 연구의 결과는 phenol의 종류에 상관없이 식이 phenol에 조직의 항산화(산화억제)를 통해 암 예방(cancer prevention)에 영향을 미친다는 것을 제시해준다.물을 첨가하여 물내리기를 한 후 김이 오른 후 물내린 쌀가루에 15% 이상의 설탕을 첨가하여 20분간 쪄서 만든 백설기가 가장 바람직하다는 것을 알 수 있었다. 이 실험 중 가장 중요한 조건은 첨가하는 물의 양이 10%이며 첨가하는 당이 설탕일 경우는 김이 오른 후 설탕을 섞어 바로 쪄야 하며 설탕의 양이 15% 이상이라는 것이다. 이 조건은 대체적으로 hardness, adhesiveness, gumminess가 큰 수치를 나타낸다.순구조의 Tonpilz형 초음파 변환기와 비교하여 비록 송파전압감도에 있어서는 약 5 dB 정도의 음향출력의 손실이 불가피하지만, 그 대신 주파수 대역폭을 약 5 재 정도 확대시킬 수 있는 장점이 있기 때문에 이 넓은 주파수 대역을 효과적으로 활용하면 어종식별을 위한 음향산란신호를 정량적으로 수집 및 평가하는 것이 가능하다고 판단된다.n A was 11 ug.이, 0.9 ug/g and 3.7 ug/g in the blood, liver and kidney, respectively.sional-managerial who secure the higher autonomy and stability in their work have the highest life chance in the labor and health, and leisure life

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.1-11
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• 2008

This work proposes a 15b 50MS/s CMOS pipeline ADC based on digital code-error calibration. The proposed ADC adopts a four-stage pipeline architecture to minimize power consumption and die area and employs a digital calibration technique in the front-end stage MDAC without any modification of critical analog circuits. The front-end MDAC code errors due to device mismatch are measured by un-calibrated back-end three stages and stored in memory. During normal conversion, the stored code errors are recalled for code-error calibration in the digital domain. The signal insensitive 3-D fully symmetric layout technique in three MDACs is employed to achieve a high matching accuracy and to measure the mismatch error of the front-end stage more exactly. The prototype ADC in a 0.18um CMOS process demonstrates a measured DNL and INL within 0.78LSB and 3.28LSB. The ADC, with an active die area of $4.2mm^2$, shows a maximum SNDR and SFDR of 67.2dB and 79.5dB, respectively, and a power consumption of 225mW at 2.5V and 50MS/s.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.319-325
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• 2004

FHMA(frequency hopping multiple access) communication system has good performance for the LPI and AJ(low probability of intercept and anti-jamming) application. However, high PAPR(peak to average power ratio) happens in the base-station or the repeater system because of a large number of users. In general, predistorter is used to complete the HPA(high power amplifier) nonlinear characteristics. This paper analyzes BER performance when magnitude of IBO(input back oft) and the number of user are considered as the system parameters. In case of the SSPA(solid state power amplifier), the predistorter does not always work as a complete nonlinear compensator. We find that there is a minimum value of IBO for the predistorter to compensate for the nonlinear SSP A, which is changed as the number of user. If IBO is lower than 6 ㏈ at the user number of 16 and p=1, the system with predistorter is poorer than the one without predistorter. Only when the IBO is over 6 ㏈, predistorter does work as a nonlinear compensator. We call it as cross-over IBO value. TWTA improves the more compensation performance than SSPA because characteristic AM/AM of TWTA has more nonlinear than SSPA. At the BER=10$\^$-3/, there are SNR power gains of about 2.5 ㏈ and 3 ㏈ due to the predistorter when the numbers of users are 16 and 32, respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.3
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• pp.263-273
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• 2008

The precision of sensors' position is particularly important in the application of road extraction or digital map generation. In general, the various ranging solution systems such as GPS, Total Station, and Laser Ranger have been employed for the position of the sensor. Basically, the ranging solution system has problems that the signal may be blocked or degraded by various environmental circumstances and has low temporal resolution. To overcome those limitations a IMU/range integrated system could be introduced. In this paper, after pointing out the limitation of extended Kalman filter which has been used for workhorse in navigation and geodetic community, the two sampling based nonlinear filters which are sigma point Kalman filter using nonlinear transformation and carefully chosen sigma points and particle filter using the non-gaussian assumption are implemented and compared with extended Kalman filter in a simulation test. For the ranging solution system, the GPS and Total station was selected and the three levels of IMUs(IMU400C, HG1700, LN100) are chosen for the simulation. For all ranging solution system and IMUs the sampling based nonlinear filter yield improved position result and it is more noticeable that the superiority of nonlinear filter in low temporal resolution such as 5 sec. Therefore, it is recommended to apply non-linear filter to determine the sensor's position with low degree position sensors.