• Transactions on Electrical and Electronic Materials
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• v.10 no.2
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• pp.44-48
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• 2009

A simulation study of a 10-bit two-stage DAC was done by using a conventional current switch cell. The DAC adopts the segmented architecture in order to reduce the circuit complexity and the die area. The 10-bit CMOS DAC was designed in 2 blocks, a unary cell matrix for 6 MSBs and a binary weighted array for 4 LSBs, for fabrication in a 0.35-${\mu}m$ CMOS process. To cancel the accumulation of errors in each current cell, a symmetrical switching sequence is applied in the unary cell matrix for 6 MSBs. To ensure high-speed operation, a decoding circuit with one stage latch and a cascode current source were developed. Simulations show that the maximum power consumption of the 10-bit DAC is 74 mW with a sampling frequency of 100 MHz.

• Phonetics and Speech Sciences
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• v.4 no.3
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• pp.103-110
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• 2012

In this paper, a target signal detection method using multiple signal classification (MUSIC) algorithm is proposed. The MUSIC algorithm is a subspace-based direction of arrival (DOA) estimation method. Using the inverse of the eigenvalue-weighted eigen spectra, the algorithm detects the DOAs of multiple sources. To apply the algorithm in target signal detection for GSC-based beamforming, we utilize its spectral response for the DOA of the target source in noisy conditions. The performance of the proposed target signal detection method is compared with those of the normalized cross-correlation (NCC), the fixed beamforming, and the power ratio method. Experimental results show that the proposed algorithm significantly outperforms the conventional ones in receiver operating characteristics (ROC) curves.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.885-890
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• 2004

Strictly maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature, the change of the dynamic characteristics in the reheater. Up to the present time, PID Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on tuning of the Controller with disturbance rejection for thermal power plant using immune based multiobjective approach. An ITSE(Integral of time weighted squared error) is used to decide performance of tuning results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.1
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• pp.31-38
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• 1991

A direct digital control technique of a current source using the phase-controlled rectifier is presented. A digital firing technique without sensing the line voltage is proposed. This scheme generates firing pulses directly from error signal between command and output voltage. Thus the phase detection transformers filters and zero-crossing detector are unnecessary. The synchronism is modeled and analized. Also a software synchronization algorithm is presented without a look up table and controls the system in real time with fast dynamic characteristics. Using the single-chip microprocessor 8097BH, the direct digital control is implemented with minimal hardware structure. Using the time-weighted performance index, the optimal discrete IPM control technique is also proposed to control the current of the PCR.

• Journal of KSNVE
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• v.4 no.3
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• pp.319-325
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• 1994

The flucturation of the engine torque appears to be the major source of the torsional vibration of the automotive driveline. The reduction of this torsional vibration has become a significant problem, due to an increase in the flucturation of the torque of recent light weighted powered engines, along with the requirements of higher performance. The torsional vibration of the automotive driveline can be reduced by soothing the fluctuation by adjusting the torsional characteristics of the clutch-disc. Computer simulation of the engine- input gear train is a useful investigative tool on studying the torsional characteristics of the clutch-disc. In this paper, a dynamic model for the automotive driveline was developed, and the engine torque and drag torque of the model were evaluated withe experimental data. By executing a simulation using the model, it has become possible to obtain the clutch-disc torsional characteristics when the engine is idling and the clucth-disc torsional characteristics for reducing the torsional vibration has been suggested.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.2
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• pp.179-187
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• 1996

Sampling of precipitation occurred at Woongchon in Choongnam from the period between May 1994 and April 1995 was made, and analysis on the data was carried out on observed pH values of the precipitations. It was found that weighted mean pH values were .sim. 4.8 and that acid rain occurred at the site of the Yellow Sea's coastal area. The results agree well with the earlier observations made at other sites of a background monitoring network. The annual values observed at the background monitoring sites were too low in comparison with the mean pH values (5.3 .sim. 5.9) obtained from urban stations of the Ministry of Environment. It was observed that values of pH in rain water often changed with time during the event of precipitation, and the low values usually depended on an airflow and a cyclone that originated in the source region.

• Journal of information and communication convergence engineering
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• v.15 no.1
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• pp.7-13
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• 2017

We consider a distributed estimation where many nodes remotely placed at known locations collect the measurements of the parameter of interest, quantize these measurements, and transmit the quantized data to a fusion node; this fusion node performs the parameter estimation. Noting that quantizers at nodes should operate in a non-regular framework where multiple codewords or quantization partitions can be mapped from a single measurement to improve the system performance, we propose a low-weight estimation algorithm that finds the most feasible combination of codewords. This combination is found by computing the weighted sum of the possible combinations whose weights are obtained by counting their occurrence in a learning process. Otherwise, tremendous complexity will be inevitable due to multiple codewords or partitions interpreted from non-regular quantized data. We conduct extensive experiments to demonstrate that the proposed algorithm provides a statistically significant performance gain with low complexity as compared to typical estimation techniques.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.264-267
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• 2008

Relationship between exposure to combined noise sources and community annoyance have been investigated. Social surveys were conducted in urban spaces near the construction site with road traffics. The question relating to noise annoyance was answered on an 11-point numerical scale and 5-point verbal scale according to ISO 15666. The questionnaire also contained demographic factors, interference with daily activities, health-related symptoms, and noise sensitivity. Noise levels were measured in terms of A-weighted equivalent level ($L_{Aeq}$), and noise mapping technique was applied to predict the noise levels of urban spaces. Synthesis curves for the relationship between noise levels and percentage highly annoyed for combined noise sources were derived, and compared to the curves from a single noise source.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.923-926
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• 2003

This paper presents a novel low voltage reference circuit under the MOS threshold voltage(V$_{th}$) in standard CMOS process. It is based on the weighted difference of the gate-source voltages of an NMOS and a PMOS operating in saturation region. The voltage reference is designed for low power OLED driver ICs. The proposed circuit is designed using 0.35${\mu}{\textrm}{m}$ CMOS technology. The minimum supply voltage is 2V, and the typical temperature coefficient is 99.6ppm/ C.C.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.4
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• pp.1041-1062
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• 2012

In this paper, we propose a hybrid cooperative scheme to improve the secrecy rate for a cooperative network in presence of multiple relays. Each relay node transmits the mixed signal consisting of weighted source signal and intentional noise. The problem of power allocation, the joint design of beamforming and jamming weights are investigated, and an iterative scheme is proposed. It is demonstrated by the numerical results that the proposed hybrid scheme further improves secrecy rate, as compared to traditional cooperative schemes.