• 설비공학논문집
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• 제23권7호
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• pp.513-519
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• 2011

The object of this study is to investigate the performance characteristics of refrigerators using a single-circuit multi cycle and a bypass two-circuit multi cycle. Each refrigeration cycle was tested by varying secondary fluid mass flow rate and temperature. Based on the experimental data, the optimum refrigerant charge was 48 g and the COP at the optimum secondary fluid mass flow rate was 1.53 for the single-circuit multi cycle. For freezer(F)-only mode, both the single-circuit multi cycle and the bypass two-circuit multi cycle were operated at overcharge conditions, resulting in an increase of the secondary fluid mass flow rate. The maximum COPs of the single-circuit multi cycle and the bypass two-circuit multi cycle were 1.22 and 1.35, respectively. The COP increased by 10.7% with the application of the bypass two-circuit multi cycle.

• 대한전자공학회논문지TE
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• 제39권3호
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• pp.1-7
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• 2002

본 논문에서는 다중 PFD(Phase Frequency Detector)와 적응 전하펌프 회로를 설계하여 지터 잡음 특성과 주파수 획득 과정을 향상시킨 새로운 PLL 클럭 발생기를 제안한다. 기존의 PLL은 넓은 데드존과 듀티 사이클 특성을 갖고 있기 때문에 지터잡음을 발생하고, 긴 지연시간 때문에 고속 동작에는 부적합하다. 본 논문에서는 이러한 문제를 해결하기 위하여, TSPC(True Single Phase Clocking) 회로를 이용하여 다중 구조를 갖는 PFD를 설계하였다. 데드존 특성, 듀티 사이클의 제한조건을 개선할 수 있도록 회로를 설계하였으며, 탁월한 지터잡음 성능을 향상시킬 수 있었다. 또한 적응 전하펌프 회로를 사용하여 PLL을 설계하였으며 루프필터의 전하펌프 전류를 증가시킴으로써 주파수 획득 특성을 개선 할 수 있었다. Hspice 시뮬레이션을 수행한 결과, 제안한 PLL은 데드존이 0.01ns 미만이고, 입력신호의 듀티 사이클에 무관하며, 50ns의 빠른 획득시간을 갖는 것을 확인할 수 있었다. 따라서 제안된 회로는 고성능 마이크로프로세서 및 디지털시스템에 적용될 수 있다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.518-521
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• 2003

LCA (Life Cycle Assessment), that unifies the scale of various environmental impacts, and simulated annealing are applied to optimizing electrolysis of wastewater from PCB (Printed Circuit Board) production. The changes of environmental impact can be quantified with LCA and the total changes of environmental impacts can be expressed as a function of power consumed, Cu recycled, $Cl_2$, NOx and SOx discharged through restriction of feasible reactions. In a single-variate condition, the environmental optimum can be easily obtained through plotting and comparing each environmental impact value. In 8V potentiostatic electrolysis, the lowest environmental impact can be achieved after 90min. To optimize a multi-variate conditional system, simulated annealing can be applied and this can give the quick and near optimum in complex systems, where many input and output materials are involved, through experimentally measured values without a theoretical modeling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.125-128
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• 2006

This paper presents a novel type soft switching PWM power frequency AC-AC converter using bidirectional active switches or single phase utility frequency AC-high frequency AC matrix converter. This converter can directly convert utility frequency AC (UFAC, 50Hz/60Hz) power to high frequency AC (HFAC) power ranging more than 20kHz up to 100kHz. A novel soft switching PWM prototype of high frequency multi-resonant PWM controlled UFAC-HFAC matrix converter using antiparallel one-chip reverse blocking IGBTs manufactured by IXYS corp. is based on the soft switching resonance with asymmetrical duty cycle PWM strategy. This single phase UFAC-HFAC matrix converter has some remarkable features as electrolytic capacitor DC busline linkless topology, unity power factor correction and sine-wave line current shaping, simple configuration with minimum circuit components, high efficiency and downsizing. This series load resonant UFAC-HFAC matrix converter, incorporating bidirectional active power switches is developed and implemented for high efficiency consumer induction heated food cooking appliances in home uses and business-uses. Its operating performances as soft switching operating ranges and high frequency effective power regulation characteristics are illustrated and discussed on the basis of simulation and experimental results.

• Journal of Semiconductor Engineering
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• 제2권1호
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• pp.99-108
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• 2021

Successive Approximation Register (SAR) Analog-to-Digital Converters (ADC) seem to become the hottest ADC architecture during the past decade in implementing energy-efficient high performance ADCs. In this overview, we will review what kind of circuit techniques and architectural advances have contributed to place the SAR ADC architecture at its current position, beginning from a single SAR ADC and moving to various hybrid architectures. At the end of this overview, a recently reported compact and high-speed SAR-Flash ADC is introduced as one design example of SAR-based hybrid ADC architecture.

• 전자공학회논문지
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• 제52권5호
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• pp.58-65
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• 2015

본 논문에서는 신경 관련 인공 전자기기를 위한 신경 자극 집적회로를 $0.18-{\mu}m$ 표준 CMOS 반도체 공정을 이용하여 설계하였다. 제안 된 신경 자극 회로는 12.8-V 전원을 사용하면서 $10-k{\Omega}$의 부하에 최대 1 mA의 전류까지 전달이 가능하다. 표준 CMOS 공정 기술로 구현을 위해서 저전압 트랜지스터만을 이용하여 설계를 하였고, 고전압에서의 안정적인 동작을 위하여 트랜지스터 스태킹 기술을 적용하였다. 또한, 신경 자극 동작 후 전하 잔여량이 남아 있지 않도록 active charge balancing회로를 포함하였다. 제안 된 단일 채널 자극 집적회로의 경우 디지털-아날로그 변환기, 전류 출력 드라이버, 레벨 시프터, 디지털 제어 부분, 그리고 active charge balancing 회로까지 모두 포함하여 전체 칩 레이아웃 면적은 $0.13mm^2$을 차지하며, 다중 채널 방식의 신경 자극 기능의 체내 이식용 인공 전자기기 시스템에 적용을 하는데 적합하다.