• 조명전기설비학회논문지
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• 제15권6호
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• pp.43-48
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• 2001

본 논문에서는 지중의 노이즈들로부터 영향을 받지않는 접지저항 측정시스템을 설계하였다. 일반적으로 기존 의 접지저항 측정기는 지중에 노이즈가 잠재되어 있을 경우, 접지저항 측정신호가 영향을 받아 정확한 접지저항을 측정하기 어렵다. 따라서 본 논문에서는 L-C공진필터와 마이크로프로세서를 이용하여 지중의 잡음환경에서도 정확히 접지저항을 측정할 수 있는 접지저항 측정기를 설계하였다. 또한 현장시험을 통해 설계된 접지저항측정기가 지중의 노이즈로부터 영향을 받지않음을 입증하였다.

• 대한기계학회논문집A
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• 제25권1호
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• pp.16-24
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• 2001

This paper presents an electromagnetic microactuator using the copper coil electroplated on the p+silicon diaphragm. The microactuator generates a vertical motion of the diaphragm using the radial direction, we propose a new actuator structure with twin magnets. The microactuator field in the radial direction, we propose a new actuator structure with twin magnets. The microactator shows a values of resonant frequency and quality factor in the ranges of 10.51${\pm}$0.22kHz and 46.6${\pm}$3.3, respectively. The twin magnet microactuator generates the maximum peak-to-peak amplitude of 4.4$\mu\textrm{m}$ for the AC rms current of 26.8mA, showing 2.4 times larger amplitude than the single magnet microactuator.

• 한국산학기술학회논문지
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• 제10권4호
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• pp.740-746
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• 2009

본 논문에서는 공진형 유도가열기를 이용한 2단 직렬 부하형 유도가열 과열증기 발생장치를 제안하였다. 발열방식은 외부의 가열코일로부터 특수 합금 발열체에 비접촉 상태로 전자유도 와전류를 구조체에 흐르게 하였다. 인버터는 풀-브리지 고주파 직렬 부하 공진형 이며, LC 공진 설계에서 부하자체를 인덕터로 선정하여 효율을 최대화 하였다. 개발된 장치는 전자유도가열 발열체와 유체이동에 의한 새로운 열교환 방식으로 일체의 연소과정 없이 기체, 액체 및 증발체 등을 상온에서 고온에 이르기까지 고정도의 가열이 가능하다.

• 조명전기설비학회논문지
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• 제22권7호
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• pp.7-15
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• 2008

A single active capacitor snubber-assisted soft-switching sinewave pulse modulation utility-interactive power conditioner with a three-winding flyback high frequency transformer link and a bidirectional active power switch in its secondary side has been proposed. With the aid of the switched-capacitor quasi-resonant snubber cell, the high frequency switching devices in the primary side of the proposed DC-to-AC sinewave power inverter can be turned-off with ZVS commutation. In addition to this, the proposed power conditioner in the DCM can effectively take the advantages of ZCS turn-on commutation. Its output port is connected directly to the utility AC power source grid. At the end, the prototype of the proposed HF-UPC is built and tested in experiment. Its power conversion conditioning and processing circuit with a high frequency flyback transformer link is verified and the output sinewave current is qualified in accordance with the power quality guidelines of the utility AC interactive power systems.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.475-477
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• 2008

LLC 공진형 컨버터는 주스위치의 ZVS와 출력정류단의 ZCS가 가능하여 높은 효율로 동작하고, 출력단에 인덕터를 사용하지 않는 장점으로 널리 사용되고 있다. LLC 공진형 컨버터의 출력단 구조는 크게 변압기의 센터탭(Center Tap) 방식과 출력정류기를 Full Bridge로 구성하는 방식이 있는데, 정류기 손실과 재료비 측면을 고려하면 센터탭 방식이 유리하다. 그러나 센터탭으로 분리된 2차측 권선간의 누설 인덕턴스 차이로 인하여 컨버터 동작의 반주기 마다 공진이 어긋날 수 있고, 출력정류단에 흐르는 전류의 RMS 크기도 매 반주기마다 달라져서 동작효율의 감소를 가져올 수 있다. 따라서 본 논문에서는 LLC 공진형 컨버터의 수학적 모델로부터 2차측 권선의 누설 인덕턴스 차이의 영향을 예측하고, 그 영향을 최소화할 수 있는 권선법을 제안한다. 또한 400W급 컨버터에서 실험을 통하여 제안한 방식을 실증하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1703-1705
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• 2001

The pulsed Nd:YAG laser is used widely for materials processing and medical instrument etc. It is important to control the laser energy in those fields using a pulsed Nd:YAG laser. In this paper, constant-frequency current resonant half-bridge inverter and Cockcroft-Walton circuit are used to charge the energy storage capacitor variably. This laser power supply is designed and fabricated which has no high-voltage transformer, less switching losses, compact size and capability in varying the laser output power. Also, the output characteristics of this Nd:YAG laser system are investigated. The tested results are described.

• 한국전기전자재료학회논문지
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• 제21권8호
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• pp.719-726
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• 2008

In this paper, we designed driving IC for 500 V resonant half-bridge type power converter, In this single-ended level shifter, chip area and power dissipation was decreased by 50% and 23.5% each compared to the conventional dual-ended level shifter. Also, this newly designed circuit solved the biggest problem of conventional flip-flop type level shifter in which the power MOSFET were turned on simultaneously due to the large dv/dt noise. The proposed high side level shifter included switching noise protection circuit and schmmit trigger to minimize the effect of displacement current flowing through LDMOS of level shifter when power MOSFET is operating. The designing process was proved reasonable by conducting Spectre and PSpice simulation on this circuit using 1${\mu}m$ BCD process parameter.

• Advances in nano research
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• 제3권1호
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• pp.29-37
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• 2015

In the current study, the nonlinear vibration properties of an embedded zigzag single-walled carbon nanotube (SWCNT) are investigated. Winkler-type model is used to simulate the interaction of the zigzag SWCNTs with a surrounding elastic medium. The relation between deflection amplitudes and resonant frequencies of the SWCNT is derived through harmonic balance method. The equivalent Young's modulus and shear modulus for zigzag SWCNT are derived using an energy-equivalent model. The amplitude - frequency curves for large-amplitude vibrations are graphically illustrated. The simulation results show that the chirality of zigzag carbon nanolube as well as surrounding elastic medium play more important roles in the nonlinear vibration of the single-walled carbon nanotubes.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.464-467
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• 2003

In this paper, to reduce the patch size of microstrip antenna, folded surface-type patch antenna is designed and fabricated. Size reduction could be achieved because of the downed resonant frequency by the extended current path passing along below the transformated patch surface. Comparison of the patch size at the 1.575 GHz between plane type(length 82 mm${\times}$width 90 mm) and "ㄷ"-shaped folded type is carried and comparision of frequency variation at the same patch size is carried. The result is like that the patch size was reduced than the plane type by 60 mm(73.17 %) at the same frequency. Therefore, it could be checked that "ㄷ"-shaped folded type antenna is advantageous than the plane type in size reduction.

• BMB Reports
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• 제53권7호
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• pp.357-366
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• 2020

Currently, most biological research relies on conventional experimental techniques that allow only static analyses at certain time points in vitro or ex vivo. However, if one could visualize cellular dynamics in living organisms, that would provide a unique opportunity to study key biological phenomena in vivo. Intravital microscopy (IVM) encompasses diverse optical systems for direct viewing of objects, including biological structures and individual cells in live animals. With the current development of devices and techniques, IVM addresses important questions in various fields of biological and biomedical sciences. In this mini-review, we provide a general introduction to IVM and examples of recent applications in the field of immunology, oncology, and vascular biology. We also introduce an advanced type of IVM, dubbed real-time IVM, equipped with video-rate resonant scanning. Since the realt-ime IVM can render cellular dynamics with high temporal resolution in vivo, it allows visualization and analysis of rapid biological processes.