• Journal of the Korean Society for Precision Engineering
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• v.12 no.9
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• pp.86-94
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• 1995

Bead shape in high frequency electric resistance (HER) pipe welding gives useful information on judging current welding conditon. In most welding process, heat input is controlled by skilled operators observing color and shape of bead. In this paper, a visual monitoring system is designed to observe bead shape in HERW pipe welding process by using structured light beam and a C.I.D(Charge injection device) camera. To avoid some difficul- ties arising in extracting stable features of stripe pattern and classifying the extracted features, Kohonen neural network is used to classify such bead shapes. The experimental results show accurate classification performance of the proposed method.

• Proceedings of the KSLP Conference
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• 2002.04a
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• pp.75-82
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• 2002

Botulinum toxin-A, a neurotoxin derived from Clostridia Botulinum, has been injected into the laryngeal muscle(s) for the treatment of the spasmodic dysphonia at the Voice Clinic, Yonsei Institute of Logopedics and phoniatrics since December 1995. We analyzed 355 patients with spasmodic dysphonia, using Botox register review. In the 355 patients, female is 86.8%. male is 13.2%. 305 patients (85.9%) had adductor type of spasmodic dysphonia and 35 patients (9.9%) were vocal tremor type and 15 patients were abduction and mixed type. Botulinum toxin type-A (Botox) injection using EMG was most frequently conducted as 587 cases, comparing with flexible nasopharyngoscopy gudied injection (68cases) and tele- laryn-goscopy guided injection (31cases). In the respect of frequency of Botox injection, 137 patients(38.6%) were injected one time but 1 patient was injected 17times. The mean dose of Botox is 6.2U. Clinically, initial dose of Botulinum toxin-A was high dose (7-8U) but current dose is small dose (3U). And the mean duration of Botox injection is 6.4 month. In conclusion, to optimize effect of the treatment for spasmodic dysphonia, Botulinum toxin-A injection is combined with voice therapy.

• Journal of IKEEE
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• v.26 no.1
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• pp.95-103
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• 2022

In this paper, the efficiency of a sensorless method with square-wave injection for a low-cost inverter, so called B4 inverter is presented. This inverter comprises only 4 switches to reduce system cost. It is distinguished from the conventional B6 inverter that has 6 of switching elements. The B4 inverter, injected a 1 kHz of harmonic wave, has been modelled using the functions and library in Matlab/Simulink. This paper described each component of sensorless algorithm. Among them, the Notch Filter is used to extract the harmonic component of the phase current and a second-order low-pass filter was used to reduce the ripple of the estimated speed. It is shown through simulation that the rotor angle of a permanent magnet synchronous motor is detected by multiplying the current waveform extracted using the notch filter by the harmonic voltage. The feasibility of the proposed method is shown through Simulink simulation.

• Journal of the Korean Society of Combustion
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• v.3 no.1
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• pp.71-78
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• 1998

The flame stabilization and the combustion characteristics of diffusion flame formed in the wake of a cylindrical bluff body with fuel injection are studied. With the turbulence generator, the flame stability limits and ion currents were measured and analyzed. The results from this experimental study are summarized as follows. The region with highest average value of ion currents in the middle of flame is moved to the upstream side by the turbulent components of main stream. The flame mass with partially active reaction is moved fast for uniform flow and turbulence generator G3, but the flame mass with relatively slow reaction is moved slowly for turbulence generator G1. If the turbulence generator with strong turbulent component is installed, the turbulent time scale is increased with movement from main stream side to recirculation zone as well as the flame stability limits is deteriorated. Though the special dominant frequency is not appeared in the eddy which exists in flame, high frequency characteristics are appeared in uniform flow and turbulence generator G3, and low frequency characteristics are appeared in uniform flow, turbulence generator G3 and G1.

• Journal of the Optical Society of Korea
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• v.14 no.2
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• pp.137-141
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• 2010

We report, for the first time to our knowledge, observation of polarization bistability from 1.55-${\mu}m$ wavelength single-mode VCSELs of a conventional cylinder-shape under control of their driving current, and demonstration of all-optical flip-flop (AOFF) operations based on the bistability with optical set and reset pulse injection at a 50 MHz switching frequency. The injection pulse energy was less than 14 fJ. The average on-off contrast ratio of the flip-flopped signals was about 7 dB. These properties of the VCSELs will be potentially useful for future high-speed all-optical signal processing applications.

• Journal of Surface Science and Engineering
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• v.29 no.5
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• pp.357-362
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• 1996

Several applications of radio-frequency (RF) thermal plasma to film formation are reviewed. Three types of injection plasma processing (IPP) technique are first introduced for the deposition of materials. Those are thermal plasma chemical vapor deposition (CVD), plasma flash evaporation, and plasma spraying. Radio-frequency (RF) plasma and hybrid (combination of RF and direct current(DC)) plasma are next introduced as promising thermal plasma sources in the IPP technique. Experimental data for three kinds of processing are demonstrated mainly based on our recent researches of depositions of functional materials, such as high temperature semiconductor SiC and diamond, ionic conductor $ZrO_2-Y_2O_3$ and high critical temperature superconductor $YBa_2Cu_3O_7-x$. Special emphasis is given to thermal plasma flash evaporation, in which nanometer-scaled clusters generated in plasma flame play important roles as nanometer-scaled clusters as deposition species. A novel epitaxial growth mechanism from the "hot" clusters namely "hot cluster epitaxy (HCE)" is proposed.)" is proposed.osed.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.189-195
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• 2005

This paper presents a new velocity estimation strategy for a non-salient permanent magnet synchronous motor drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system, which contains the rotor position error information. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error at zero. For zero and low speed operation, the PI gain of the rotor position tracking controller has a variable structure according to the estimated rotor velocity. Then, at zero speed, the rotor position and velocity have sluggish dynamics because the varying gains are very low in this region. In order to boost the bandwidth of the PI controller during zero speed, the loop recovery technique is applied to the control system. The PI tuning formulas are also derived by analyzing this control system by frequency domain specifications such as phase margin and bandwidth assignment.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.147-149
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• 2004

This paper presents a new velocity estimation strategy of a non-salient permanent magnet synchronous motor(PMSM) drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system which has the information of rotor position error. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error to zero. For zero and low speed operation, the PI gains of rotor position tracking controller have a variable structure. The PI tuning formulas are derived by analyzing this control system using the frequency domain specifications such as phase margin and bandwidth assignment.

• Electrical & Electronic Materials
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• v.11 no.10
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• pp.94-99
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• 1998

Suitable replacement materials for ultrathin SiO2 in deeply scaled MOSFETs such as lattice polarizable films, which have much higherpermittivities than SiO2, have bandgaps of only 3.0 to 4.0 eV. Due to these small bandgaps, the reliability of these films as a gate insulator is a serious concern. Ramped voltage, time dependent dielectric breakdown, and hot carrier effect measurements were done on 190 layers of TiO2 which were deposited through the metal-organic chemical vapor deposition of titanium tetrakis-isopropoxide (TTIP). Measurements of the high and low frequency capacitance indicate that virtually no interface state are created during constant current injection stress. The increase in leakage upon electrical stress suggests that uncharged, near-interface states may be created in the TiO2 film near the SiO2 interfacial layer that allow a tunneling current component at low bias.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.167-168
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• 2013

신호 주입 센서리스 구동 시, 인버터의 비선형성으로 인한 주입 전압 왜곡현상은 전류 신호 정보의 SNR을 떨어뜨리게 된다. 이로 인하여 회전자 위치를 추정하는 과정에서 오차가 발생하는 문제점이 발생한다. 본 논문에서는 인버터의 비선형성이 주입 전압에 미치는 영향을 분석하고, 전류 신호 정보의 SNR을 개선하기 위하여 고주파 전류 맥동의 크기를 일정하게 제어하는 주입 전압을 인가하는 방법을 제안한다. 실험을 통하여, 제안된 방법의 성능을 검증하였다.