• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.137-142
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• 2003

Two existing continuous-time models for the current-mode control have presented noticeable differences in their small-signal predictions. As an attempt to clarify the origin of these disparities, this paper presents an alternative way of deriving a continuous-time model for the current-model control. The results of this paper would provide insights to comprehend the dissimilarity in the modeling method and final results of the earlier models of current-mode control models.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1929-1932
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• 2002

In this paper, some parameters are studied for the performance improvement of a bulk optical current sensor. The performance of optical current sensor is influenced by current measuring range, Verdet constant change due to temperature change, temperature variation of wave plate, signal to noise ratio of optical transmitter/receiver, optical bias mismatch. Two types of optical current sensors are implemented and tested in the current range from 10 ampere to 200 ampere.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.187-192
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• 2000

We analyze the parametric amplification by the nonlinear characteristics in a semiconductor laser using a perturbation theory and discuss its result. The parametric gain increases with increase of the pump modulation current. It is due to shift of the resonance frequency as the pump modulation current increases. However, it decreases with increase of the bias current and damping constant. Also, it needs phase matching between the pump modulation current and signal modulation current to maximize the parametric gain. The gain decreases for a large signal modulation current due to the saturation of the amplified power. power.

• Proceedings of the KWS Conference
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• 1990.11a
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• pp.82-86
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• 1990

A new method was investigated to measure the high current in resistance welding processes. A measuring unit was developed by using a strain gage attached on the outer surface of a steel ring. The steel ring was placed around a section of the secondary loop of the welding machine, and was deformed by electro-magnetic forces induced by the high welding current. The circumferential constituent of the ring deformation was then used to obtain a signal voltage proportional to the secondary welding current. The strain gage signal of ring deformation is enough to determine the welding current in resistance spot welding, especially when welded with direct current.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1146-1151
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• 2011

There are two methods for train control in information transmission by using track circuit system and installing wayside transmitter. Information signal is transmitted to the on-board antenna by using rails. Continuous information about train intervals, speed and route is received by on-board antenna in AF track circuit system. The information signal is included with carrier wave and received by magnetic coupling in the on-board antenna. Therefore, it is important to define standard current level in the AF track circuit system. When current flowed to rails is low, magnetic sensors are not operated by decreasing magnetic field intensity. Hence, SNR is decreased because electric field intensity is decreased. When the SNR is decreased, there is the serious influence of noise upon demodulation. So, the frequency of information signal is not extracted in frequency response. Thus, it is possible to happen to train accident and delay as the information signal is not analyzed in the on-board antenna. In this paper, standard energy density is calculated by using Parseval's theory in UM71c track circuit. Hence, detection time of information signal is presented.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1254-1258
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• 2004

This paper presents of position control of Permanent Magnet Synchronous Motor (PMSM) the implementation with Field Programmable Gate Array (FPGA) is proposed. Cascade control with inner loop as a current control and an outer loop as a position control is chosen for simplicity and fast response. FPGA is a single chip (single processing unit), which will perform the following tasks: receive and convert control signal, create a reference current signal, control current and create switch signal and act as position controller in a addition of zero form. The 10 kHz sampling frequency and 25 bit of floating point data are defined in this implementation.The experimental results show that the performance of FPGA based position control is comparable with the hardware based position control, with the advantage of control algorithm flexibility

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.901-904
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• 2005

Testing of mixed-signal circuit has become a difficult task for test engineers and efficient test solution to these problems are needed. In this paper a new specification-based mixed-signal test method called TSS(Time Slot Specification) using high performance current sensors and a novel test point selection technique without heavy computational overhead are proposed. External output and power nodes are used for test points and accessed by the current sensors in the ATE.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.12
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• pp.60-69
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• 1997

We present an average method based on the multirate signal processing and dynamic allocation average for the purpose of monitoring event-related potentials(ERP) and continuously and dynamically. In the proposed method, first, latency shifts are detected through the cross correlation between a current response and the reference response. Then, the multirate signal processing which is composed of up-sampler, lowpass filter, and down sampler is performed to compensate the latency shifts of the reference response, therefore we obtain the reference response with a peak latencies compenated by those of a current response. Finally, the single response is obtained by averaging the compensated reference response and a current response. In the simulation, the results of quantitative evaluation by simulation and the results using linical data are presented. From the result, the proposed method reflects dynamic time-varying ERP more exactly than previous methods and is also effective in consecutive monitoring of ERP.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.35-38
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• 2000

In this study, the rise throughput and the stability in fabrication of device can be obtained by applying of CMP process to STI structure in 0.l8um semiconductor device. Through reverse moat pattern process, reduced moat density at high moat density, STI CMP process with low selectivity could be to fit polish uniformity between low moat density and high moat density. Because this reason, in-situ motor current end point detection method is not fit to the current EPD technology with the reverse moat pattern. But we use HSS without reverse moat pattern on STI CMP and take end point current sensing signal.[1] To analyze sensing signal and test extracted signal, we can to adjust wafer difference within $110{\AA}$.

• KIEE International Transactions on Electrophysics and Applications
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• v.2C no.5
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• pp.262-267
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• 2002

In this paper, we first studied the factors affecting the motor current (MC) signal, which was strongly affected by the systematic hardware noises depending on polishing such as pad conditioning and arm oscillation of platen and recipe, head motor. Next, we studied the end point detection (EPD) for the chemical mechanical polishing (CMP) process of shallow trench isolation (STI) with reverse moat structure. The MC signal showed a high amplitude peak in the fore part caused by the reverse meal. pattern. We also found that the EP could not be detected properly and reproducibly due to the pad conditioning effect, especially when conventional low selectivity slurry was used. Even when there was no pad conditioning effect, the EPD method could not be applied, since the measured end points were always the same due to the characteristics of the reverse moat structure with an open nitride layer.