• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.158-161
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• 1998

A precision high voltage generator for ion injection is implemented on HFZVS-PSCI (High Frequency Zero-Voltage-Switching Phase-Shift-Controlled Inverter). Some practical aspects of implementing precision high voltage generator with HFZVS-PSCI, such as a HFHV transformer, multiflier, and precision CR divider are discussed. The results show that the generator under the Phase-Shift-Controller has a fast dynamic response, low ripple voltage, and high accuracy.

• Journal of Electrical Engineering and Technology
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• 제3권3호
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• pp.422-429
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• 2008

This paper presents compact low frequency ultra-wide band (UWB) sensor design and study of the partial discharge diagnosis by sensing electromagnetic pulse emitted from the partial discharge source with the newly designed UWB sensor. In this study, we designed a new type of compact low frequency UWB sensor based on microstrip antenna technology to detect both the low frequency and high frequency band of the partial discharge signal. Experiments of offline PD testing on medium voltage (22.9kV) underground cable mention the comparative results with the traditional HFCT as a reference sensor in the laboratory. In the series of comparative tests, the calibration signal injection test provided with the conventional IEC 60270 method and high voltage injection testing are included.

• 대한기계학회논문집
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• 제11권2호
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• pp.271-278
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• 1987

본 논문에서는 공기밸브형 진동연소기에 관한 이해를 더 증진시키기 위해서 기본적인 공기밸브형 진동연소기를 제작해서 압력진동 및 발생되는 소음특성, 작동주 파수, 그리고 연소특성에 관해 실험적 고찰을 행했다.

• 소성∙가공
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• 제19권3호
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• pp.152-159
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• 2010

Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. High-frequency induction is an efficient way to heat mold surface by electromagnetic induction in a non-contact manner, and has been recently applied to the injection molding due to its capability of rapid heating and cooling of mold surface. The present study covers a three-dimensional finite element analysis to investigate heating efficiency and structural safety of the induction heating process of an injection mold. To simulate the induction heating process, an integrated simulation method is proposed by effectively connecting an electromagnetic field analysis, a transient heat transfer analysis and a thermal stress analysis. The estimated temperature changes are compared with experimental measurements for various types of induction coil, from which heating efficiency according to the coil shape is discussed. The resulting thermal stress distributions of the mold plate for various types of induction coils are also evaluated and discussed in terms of the structural safety.

• Journal of Power Electronics
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• 제15권6호
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• pp.1567-1576
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• 2015

Offline inductance identification of a permanent magnet synchronous motor (PMSM) is essential for the design of the closed-loop controller and position observer in sensorless vector controlled drives. On the base of the offline inductance identification method combining direct current (DC) offset and high frequency (HF) voltage injection which is fulfilled at standstill, this paper investigates the inverter nonlinearity effects on the inductance identification while considering harmonics in the induced HF current. The negative effects on d-q axis inductance identifications using HF signal injection are analyzed after self-learning of the inverter nonlinearity characteristics. Then, both the voltage error and the harmonic current can be described. In addition, different cases of voltage error distribution with different injection conditions are classified. The effects of inverter nonlinearities on the offline inductance identification using HF injection are validated on a 2.2 kW interior PMSM drive.

• The Journal of Korean Physical Therapy
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• 제13권2호
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• pp.335-346
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• 2001

This study was performed, using c-fos, to investigate the effect of TENS on pain model induced by capsaicin in spinal level. Twelve rats with 200-250g body weight were randomly divided into three groups: One group which induced by capsaicin, another group which applicated TENS with low frequency(4Hz. 200${\mu}$s, 20min) and the other group which applicated TENS with high frequency(100Hz, 50${\mu}$s, 20 min). The results of this study were as follows: 1. The number of c-fos immunoreactive neurons in superficial dorsal horn was increased markedly 2 hours after capsaicin injection, and decreased gradually from 4 hours to 16 hours after injection. 2. At 2hours after capsaicin injection, both low frequency and high frequency TENS decrease the number of c-fos immunoreactive neurons in superficial dorsal horn .3. In acute pain model, low frequency TENS greatly decrease c-fos expression than high frequency TENS. Therefore. decreasing the number of c-fos immunoreactive neurons which increased after capsaicin injection with application of TENS indicate that both of the TENS have inhibitory effect. In addition. low frequency TENS greatly decreased the number of neurons explains low frequency TENS is more effective than high frequency TENS in acute pain. This study also can become a part of scientific evidence on electrotherapy through measuring quantitively effects of TENS in pain model.

• Journal of Semiconductor Engineering
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• 제1권1호
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• pp.1-12
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• 2020

Handling precise timing in high-speed transceivers has always been a primary design target to achieve better performance. Many different approaches have been tried, and one of those is utilizing the beneficial nature of injection locking. Though the phenomenon was not intended for building integrated circuits at first, its coupling effect between neighboring oscillators has been utilized deliberately. Consequently, the dynamics of the injection-locked oscillator (ILO) have been explored, starting from R. Adler. As many aspects of the ILO were revealed, further studies followed to utilize the technique in practice, suggesting alternatives to the conventional frequency syntheses, which tend to be complicated and expensive. In this review, the historical analysis techniques from R. Adler are studied for better comprehension with proper notation of the variables, resulting in numerical results. In addition, how the timing jitter or phase noise in the ILO is attenuated from noise sources is presented in contrast to the clock generators based on the phase-locked loop (PLL). Although the ILO is very promising with higher cost effectiveness and better noise immunity than other schemes, unless correctly controlled or tuned, the promises above might not be realized. In order to present the favorable conditions, several strategies have been explored in diverse applications like frequency multiplication, data recovery, frequency division, clock distribution, etc. This paper reviews those research results for clock multiplication and data recovery in detail with their advantages and disadvantages they are referring to. Through this review, the readers will hopefully grasp the overall insight of the ILO, as well as its practical issues, in order to incorporate it on silicon successfully.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.73-78
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• 1990

1.3${\mu}{\textrm}{m}$ DFB with absorption grating of 1.55${\mu}{\textrm}{m}$ InGaAsP layer was fabricated. This new type of DFB laser shows self-plusation for DC operation. At low level of injection the relation between the pulsation frequency and the injection current shows similar behavior with the relaxation oscillation of ordinary laser and at high level of injection the pulsation frequency decreases compared to the relaxation oscillation. Period doubling, period 3 and 4 were observed for AC modulation. In case of period doubling the waveform shows only one pulse within a period without any accompanying subsidiary pulses and the oscillation frequency was quite stable. The pulse widths as short as 58.5 ps was achieved with AC modulation. We propose the time division multiplexing application of this kind of DFB laser.

• 전자공학회논문지
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• 제51권11호
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• pp.107-113
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• 2014

60GHz 무선 통신 시스템에 적용 가능한 전압 제어 발진기와 고속 4분주기를 65nm CMOS 공정을 사용하여 설계했다. 전압제어 발진기는 전류소스와 NMOS 차동쌍 LC구조로 설계하였으며 분주기는 차동 인젝션 록킹 구조에 베렉터를 추가하여 동작주파수 범위를 조절할 수 있는 구조로 설계했다. 전압 제어 발진기와 분주기에 모두 전류소스를 추가하여 전원잡음에 따른 위상잡음 특성을 개선하였다. 전압 제어 발진기는 64.36~67.68GHz의 동작범위가 측정됐고, 고속 4분주기는 전압 제어 발진기의 동작범위에 대해 정확한 4분주가 가능하며 5.47~5.97dBm의 높은 출력전력이 측정됐다. 분주기를 포함한 전압제어 발진기의 위상잡음은 1MHz 오프셋 주파수에서 -77.17dBc/Hz이고 10MHz 오프셋 주파수에서 -110.83dBc/Hz이다. 소모전력은 전원전압 1.2V에서 38.4mW 이다 (VCO 포함).

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1124-1128
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• 2008

Thin-wall injection molding is associated with many advantages, including increased portability, the conserving of materials, and the reduction of the molding cycle times. In the application of the thin-wall molding, a considerable reduction of the effective flow thickness results in filling difficulty. High-frequency induction is an efficient way to overcome this filling difficulty by means of heating the mold surface by electromagnetic induction. The present study applies the induction heating to the injection molding of thinwalled micro structures with high aspect ratio. The feasibility of the proposed heating method is investigated through a numerical analysis. The estimated filling characteristics of the micro-features are investigated with variations of mold temperature and part thickness, of which results are also compared with experimental measurements.