• 조명전기설비학회논문지
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• 제28권3호
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• pp.78-83
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• 2014

To minimize the financial loss due to power facility malfunction, on-line diagnostic techniques are required to grasp any abnormal state of facilities in the live line as well as devices to diagnose abnormal states of power facility in an easy and prompt manner. This study aims to develop a portable UV detecting system by means of UV sensors for easier and efficient inspection of the degradation state of power facility in a long distance. Accordingly, it includes a simulation of corona discharges that may occur due to degradation of power facility and detection of ultraviolet pulse generation depending on the corona discharge intensity and measuring distance in application of UV sensors. Additionally, the optimal algorithm is determined for its application to the system's degradation diagnosis program based on the measured experiment data.

• 센서학회지
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• 제14권2호
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• pp.69-77
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• 2005

The electronic nose (e-nose) has been used in food industry and quality controls in plastic packaging. Recently it finds its applications in medical diagnosis, specifically on detection of diabetes, pulmonary or gastrointestinal problem, or infections by examining odors in the breath or tissues with its odor characterizing ability. Moreover, the use of portable e-nose enables the on-site measurements and analysis of vapors without extra gas-sampling units. This is expected to widen the application of the e-nose in various fields including point-of-care-test or e-health. In this study, a PDA-based portable e-nose was developed using micro-machined gas sensor array and miniaturized electronic interfaces. The rich capacities of the PDA in its computing power and various interfaces are expected to provide the rapid and application specific development of the diagnostic devices, and easy connection to other facilities through information technology (IT) infra. For performance verification of the developed portable e-nose system, Six different vapors were measured using the system. Seven different carbon-black polymer composites were used for the sensor array. The results showed the reproducibility of the measured data and the distinguishable patterns between the vapor species. Additionally, the application of two typical pattern recognition algorithms verified the possibility of the automatic vapor recognition from the portable measurements. These validated the portable e-nose based on PDA developed in this study.

• 전기전자학회논문지
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• 제13권2호
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• pp.208-215
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• 2009

본 논문에서는 DT-CMOS(Dynamic Threshold voltage CMOS) 스위칭 소자를 사용한 모바일 기기용 고 효율 전원 제어 장치(PMIC)를 제안하였다. 휴대기기에서 필요한 높은 출력 전압과 낮은 출력 전압을 제공하기 위하여, 부스트 변환기(Boost Converter)와 벅 변환기(Buck Converter)를 원칩(One-chip)으로 구현하였다. 그리고 높은 출력 전류에서 고 전력 효율을 얻기 위하여 PWM(Pulse Width Modulation) 제어 방식을 사용하여 PMIC를 구현하였으며, 낮은 온 저항을 갖는 DT-CMOS를 설계하여 도통 손실을 감소시켰다. Voltage-mode PWM 제어 회로와 낮은 온 저항 스위칭 소자를 사용하여 구현한 부스트 변환기와 벅 변환기는 100mA 출력 전류에서 92.1%와 95%의 효율을 구현하였으며, 1mA이하의 대기모드에서도 높은 효율을 구현하기 위하여 LDO를 설계하였다.

• 한국콘텐츠학회논문지
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• 제8권9호
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• pp.42-54
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• 2008

오늘날의 내장형 시스템은 군사 무기체계, 로봇, 인공위성 등과 같이 전통적인 내장형 시스템과 휴대폰, PMP(Portable Multimedia Player), PDAs(Personal Digital Assistants)와 같이 통신과 멀티미디어 기기가 결합된 디지털 컨버전스 시스템에서 먹는 PC, 웨어러블 컴퓨터와 같은 차세대 PC 개념으로 진화하고 있다. 차세대 PC는 문서작성 인터넷 검색 데이터 관리 등에서 사용되었던 기존의 PC에서 분기된 네트워크 기반의 인간중심 디지털 정보기기이다. 웨어러블 컴퓨터는 극히 전력과 메모리 제한적인 시스템으로, 구성 하드웨어의 제약 사항을 극복하고 사용자 서비스의 QoS를 제공하기 위해 초소형이면서 저전력 기능을 갖춘 실시간 운영체제를 사용해야만 한다. 본 논문에서는 웨어러블 컴퓨터를 위한 저전력 실시간 운영체제 eRTOS를 설계 및 구현하였다. 본 논문에서 구현한 eRTOS는 18KB의 풋프린트(footprint)로 동적 전력 관리 기법(Dynamic Power Management)과 장치 전력 관리 기법(Device Power Management)의 저전력 기법이 구현되어 있다. 웨어러블 컴퓨터의 응용프로그램을 실험하여 47%의 전력 소모 감축효과를 확인하였다.

• 신재생에너지
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• 제3권1호
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• pp.46-53
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• 2007

Direct Methanol Fuel Cell, DMFC is a potential power source for portable IT application. DMFC works at low temperature ($<100^{\circ}C$) without fuel processing. Methanol has high energy density, fuel economy, and easiness to handle. This paper focuses high efficient catalyst to increase utilization in the electrode, new membrane reducing methanol crossover, new material parts, and optimization of system integration. Lightweight and small-sized DMFC based on new materials, efficient stack, and improved system control will be applied to the 50W prototype system for the notebook computer.

• Journal of Magnetics
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• 제20권4호
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• pp.413-420
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• 2015

In this study, we present a comparison of multistage axial flux permanent-magnet machines (AFPMs) with different topologies for use as 100 W-class portable generating systems. Three topologies were selected, and the maximum power density and high level of efficiency were achieved by following the response surface methodology (RSM) in the design. Three-dimensional finite element analysis (FEA) was used to conduct numerical experiments to obtain the optimum design using the RSM and suggest a proper configuration of the portable generating system.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.389.1-389.1
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• 2016

The flexible solid state device has been widely studied as portable and wearable device applications such as display, sensor and curved circuits. A zero-bias operation without any external power consumption is a highly-demanding feature of semiconductor devices, including optical communication, environment monitoring and digital imaging applications. Moreover, the flexibility of device would give the degree of freedom of transparent electronics. Functional and transparent abrupt p/n junction device has been realized by combining of p-type NiO and n-type ZnO metal oxide semiconductors. The use of a plastic polyethylene terephthalate (PET) film substrate spontaneously allows the flexible feature of the devices. The functional design of p-NiO/n-ZnO metal oxide device provides a high rectifying ratio of 189 to ensure the quality junction quality. This all transparent metal oxide device can be operated without external power supply. The flexible p-NiO/n-ZnO device exhibit substantial photodetection performances of quick response time of $68{\mu}s$. We may suggest an efficient design scheme of flexible and functional metal oxide-based transparent electronics.

• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.936-941
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• 2004

In recent years, the rapid growth of portable electronic devices requires the high-energy density characteristics of batteries. Zinc air batteries have specific capacity as high as 820mAh/g. However, Zinc air batteries used for hearing aid applications only so far, because the atmosphere could affect it, and it has weakness in the rate capability. However, recent developments of electrode manufacturing technologies made us to overcome that weakness. And the efforts of applying zinc air batteries to portable electronic devices, especially in cellular phone application have been increased. In this paper, the effects of conducting material and polymer binder in cathode on the electrochemical characteristics were investigated. Our research team succeeded in producing 2.4Ah class zinc air battery for cellular phone application. Its volumetric energy density was 920 wh/l, and gravimetric energy density was 308 wh/kg. The volumetric energy density of our zinc air battery is two times higher than one of lithium secondary battery, and three times higher than that of alkaline manganese battery.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.73-77
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• 2012

Operation of liquid crystal displays (LCDs) can be improved by monolithic integration of the pixel transistors with light emitting diodes (LEDs) on a single substrate. Conventional LCDs make use of filters to control the backlighting which reduces the overall efficiency. These LCDs also utilize LEDs in series which impose failure and they require high voltage for operation with a power factor correction. The screen of small hand-held devices can operate from moderate brightness. Therefore, III-V nanowires that are grown along with transistors over Silicon substrates can be utilized. Control of nanowire LEDs with nanowire transistors will significantly lower the cost, increase the efficiency, improve the manufacturing yield and simplify the structure of the small displays that are used in portable devices. The steps to grow nanowires on Silicon substrates are described. The vertical n-type and p-type nanowire transistors with surrounding gate structures are characterized. While biased at 0.5 V, nanowire transistors with minimum radius or channel width have an OFF current which is less than 1pA, an ON current more than 1 ${\mu}A$, a total delay less than 10 ps and a transconductance gain of more than 10 ${\mu}A/V$. The low power and fast switching characteristics of the nanowire transistor make them an ideal choice for the realization of future displays of portable devices with long battery lifetime.

• 한국정보통신학회논문지
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• 제10권1호
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• pp.148-155
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• 2006

멀티미디어를 주요 처리 대상으로 하는 포터블 임베디드 시스템은 데이터에 대한 빈번한 메모리 접근으로 인하여 처리 속도가 저하되는 문제점에 직면하고 있으며, 이를 해결하기 위하여 임베디드 프로세서 설계 과정에서 데이터 선인출 기법을 채택하고 있다. 이 논문에서는 임베디드 시스템의 주요 성능 척도인 전력 소모 측면에서 데이터선인출이 시스템의 성능에 미치는 영향을 분석하였다. 이를 위하여 데이터 선인출 기법이 추가된 메모리 시스템의 전력 분석 모델을 제안하고, 응용 프로그램 수행에 소모되는 전력을 모의 측정하였다. 실험 결과, 데이터 선인출은 응용 프로그램의 처리 시간을 단축하는 반면 전력 소모를 크게 증가시키는 것을 확인하였다. 더불어 데이터 선인출을 채용한 임베디드 시스템에 대하여 처리 속도와 전력 소모를 함께 고려하는 성능 분석 모델을 제안하였다.