• 대한전자공학회논문지SD
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• 제46권4호
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• pp.1-9
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• 2009

본 논문에서는 디스플레이 시스템을 위한 소면적 12-bit 300MSPS의 D/A 변화기(DAC)를 제안한다. 최근 SoC(System-On-Chip) 경향에 맞는 소면적 DAC를 구현하기 위한 전체적인 구조는 6-MSB(Most Significant Bit) + 6-LSB(Least Significant Bit)의 full matrix 구조로 설계 하였다. 고해상도 동작에 요구되는 output impedance을 만족하는 monitoring bias 구조, 고속 동작 및 소면적 디지털 회로 구성을 위하여 logic과 latch 및 deglitching 역할을 동시에 할 수 있는 self-clocked switching logic을 각각 제안하였다. 설계된 DAC는 Samsung $0.13{\mu}m$ thick gate 1-poly 6-metal N-well CMOS 공정으로 제작되었다. 제작된 DAC의 측정결과 INL (Integrated Non Linearity) / DNL (Differential Non Linearity)은 ${\pm}3LSB$ / ${\pm}1LSB$ 이하로 나타났으며, 300MHz 샘플링 속도와 15MHz의 출력신호에서 SFDR은 약 70dB로 측정되었다. DAC의 유효면적은 $0.26mm^2$ ($510{\mu}m{\times}510{\mu}m$)로 기존의 DAC에 비하여 최대 40% 감소된 초소면적으로 구현되었으며, 최대 전력 소모는 100mW로 측정되었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.677-680
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• 2003

The control of the SRM(Switched Reluctance Motor) is usually based on the non-linear inductance profiles with positions. So determination of optimal switching angle is very different. we present self-tuning control of SRM for maximum torque and efficiency with phase current and shaft position sensor During the sample time, micro-controller checks the number of pre-checked pulse. After micro-controller calculates between two data, it move forward or backward turn-off angle. When the turn-off angle is fixed optimal turn-off angle, turn-on angle moves forward or backward by a step using self-tuning control method. And then, optimal turn-off angle is searched once again. As such a repeating process, turn-on/off angle is moves automatically to obtain the maximum torque and efficiency. The experimental results are presented to validate the self-tuning algorithm.

• Journal of Power Electronics
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• 제14권5호
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• pp.908-917
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• 2014

For the purpose of designing an intrinsic safety Flyback converter with minimal output voltage ripple based on a specified output current, this paper first classified the energy transmission modes of the system into three sorts, namely, the Complete Inductor Supply Mode-CCM (CISM-CCM), the Incomplete Inductor Supply Mode-CCM (IISM-CCM) and the Incomplete Inductor Supply Mode-DCM (IISM-DCM). Then, the critical secondary self-inductance assorting the three modes are deduced and expressions of the output voltage ripples (OVR) are presented. For a Flyback converter with constant loads and switching frequency, it is shown that the output voltage ripple in the CISM-CCM is the smallest and that it has no relationship with the secondary self-inductance. Otherwise, the OVR of the other two modes are bigger than the previously mentioned one. It is concluded that the critical inductance between the CISM-CCM and the IISM-CCM is the minimal secondary self-inductance to ensure the smallest output voltage ripple. At last, a design method to guarantee the minimum OVR within the scales of the input voltage and load are analyzed, and the minimum secondary self-inductance is proposed to minimize the OVR. Simulations and experiments are given to verify the results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.243-246
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• 2001

The control of the SRM(Switched Reluctance Motor) is usually based on the non-linear inductance profiles with positions. So determination of optimal switching angle is very different. This paper proposed that the determination method of turn-on/off angle in the SRM drives is to maintain the high torque, which is realized by using self-tuning control method. During the sampling time, a number of pulses from the encoder are checked by using micro-controller. And compared with pre-checked a number of pulses. After calculating difference between two data, turn-on/off angle moves forward or backward direction by using self-tuning method. The optimal turn-on/off angle is determined by iterating such a process and the maximum torque is maintained. Experimental results are provided to demonstrate the validity of the self-tuning controller.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1145-1148
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• 1998

New capacitance modeling and transient analysis for multi-layer interconnects with shielding effect are presented. The upper layer capacitances with under-layer shielding lines are represented by introducing a filling factor η which can be defined as the ratio of upper-layer line length to the total under-layer line width. The upper-layer effective self capacitances considering two extreme cases which the underlayer metals are assumed as a ground or as a Vdd are modeled. The signal transient analysis with shielding effect model is performed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.299-306
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• 1999

The ${\mu}$-processor based-controlled system is widely used in railway signaling system. The railway signaling systems are highly required safety and reliability. It is necessary to have a fault-tolerant and fail safe concept in ${\mu}$-processor based railway signaling system. In this paper, several architectures and circuits of fault-tolerant computer system is reviewed. The basic concept of the fault-tolerant computer system will be adapted total self checking, strong fail safe, fault display circuit, logic testing circuit and system switching concepts.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.150-152
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• 1998

ZVS Half-Bridge converter is proposed. This converter is operating in fixed switching frequency to regulate output voltage. The ZVS is maintained by Partial resonance during the OFF interval of both switches. Using self-driven synchronous rectifier, this circuit minimizes the Power loss in the rectification circuit. 50[W] ZVS Half-Bridge converter is simulated and built. Two results has been compared.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.319-322
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• 1990

Self-controlled permanent magnet synchronous motor (PMSM) has similar operating characteristics as seperately excited dc motor. It is favored in servo applications due to its improvement of efficiency and maintenance. This paper presents completely digitalized controller using microprocessor and voltage fed inverter. The speed control system for PMSM is implemented. To control the motor speed, the control system regulates the magnitude of Inverter output voltage by regular-sampled PWM method to generate sinusoidal PWM wave with microprocessor. And to keep the range of inverter switching frequency, it varies the number of pulse train according to the speed.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.249-249
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• 2006

We have prepared an amphiphilic wedge-coil molecule consisting of a hydrophobic wedge-like segment and a hydrophilic poly(ethylene oxide) (PEO) segment. The wedge-coil block molecule self-assembles into cylindrical nanofibers in both polar as well as nonpolar solvents. Remarkably, the resulting nanofibers, as solvent polarity change from water to n-hexane, change from highly flexible coil-like to stiff rod-like characteristics. This dynamic switching in the stiffness of the nanofibers in response to solvent polarity is attributed to the structural inversion of cylindrical core from bulky dendritic segments with amorphous nature to crystallizable linear PEO segments.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.308-308
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• 2006

We have demonstrated that the cylindrical micelles self-assembled from coil-rod-coil molecules can be interconnected by addition of a small amount of rod-coil-rod molecule as a bridging agent. Subsequently, these dynamic interconnections lead to stiff bundles composed of cylindrical micelles that are responsible for the formation of a reversible nematic gel. The results described here represent a significant example that dynamic bridging of supramolecular cylinders in aqueous solution can provide a useful strategy to construct one-dimensional nematic structure with three dimensional elastic properties.