• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1246-1247
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• 2008

With recent advanced in portable electric devices, wireless sensor, MEMS and bio-Mechanics device, the new typed power supply, not conventional battery but self-powered energy source is needed. Particularly, the system that harvests from their environments are interests for use in self powered devices. For very low powered devices, environmental energy may be enough to use power source. Therefore, in other to made piezoelectric energy harvesting device, PMN-PZT thick film was formed by the screen printing method on the Ag/Pd coated alumina substrate. The layer was 8 layers and slurry where a-terpineol, ethycellulose, ferro B-75001 as Vehicle, PMN-PZT powder used are fabricated by ball mill. The output power quality was be also investigated by changing the load resistance, weight and frequency. The made piezoelectric energy harvesting device was resulted from the conditions of 33$k{\Omega}$, 0.25g, 197Hz respectively. The thick film was prepared at the condition of 2.75Vrms, and its power was 230${\mu} W$ and its thickness was 56${mu}m$. The piezoelectric energy harvesting device output voltage was increased, when the load weight, load resistance was increasing and resonance frequency was diminishing. The other side, resonance frequency was diminished, when the weight was increasing. And output power was continuously it changed by load resistance, output voltage, weight and resonance frequency.

• 한국정보전자통신기술학회논문지
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• 제10권2호
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• pp.161-167
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• 2017

본 논문에서는 효율적인 손목시계형 PPG 측정 장치의 구현에 관하여 연구하였다. PPG는 반사형 또는 투과형으로 측정이 가능하며, 일반적으로 손목시계의 형태의 PPG 측정 장치는 반사형으로 구현되기 때문에 동잡음에 취약하다는 단점이 있다. 또한 반사형의 경우 한쪽 손을 고정한 상태에서 다른 손을 사용하여 측정을 해야 하기 때문에 활동성에도 제약이 따른다. 본 논문에서는 기존에 개발된 장치에 클립형의 투과형 센서를 추가하여 손가락에 고정시킴으로써 측정 시 움직임을 최소화하도록 동잡음에 강건하도록 하였고, 한 손으로 측정이 가능할 뿐만 아니라 탈부착이 가능하도록 구현하여 활동성에 영향이 없도록 하였다. 제안된 장치는 측정된 신호를 실시간으로 전송이 가능하기 때문에 스마트 헬스케어 분야에 적합하며 제안된 장치의 성능을 판단하기 위해 기존의 장치와 같은 조건하에서의 측정된 신호를 비교 실험하였다. 실제 심박수 측정이 가능한 파형을 확인한 결과, 제안된 측정 장치는 기존의 장치에 비해 20%의 성능향상이 있음을 확인하였다.

• Tribology and Lubricants
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• 제30권3호
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• pp.168-176
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• 2014

This paper presents an engine oil change warning algorithm based on the test results of a small dip-stick-gage-type engine-oil-deterioration-detection sensor, software to realize the algorithm and a display device to apply the software. The algorithm determines the engine oil deterioration condition from the rate of change in the dielectric constant based on the average measured capacitance at $80^{\circ}C$ after the engine stops. The rate of change in the dielectric constant at the time for oil change correlates with the time that one of recommended warning limits for engine oil physical properties such as TAN (Total Acid Number), TBN (Total Base Number) and viscosity is first reached. At this point, a warning signal for oil change appears on the display device like a smart-phone or individual display device. The frames of smartphone app have three stages. The user can directly input all of the thresholds into the frame of the smartphone app. The screen of the display device comprises one frame for each warning signature with the related message. The user can input the thresholds to the device through a USB cable connected to a personal computer.

• Journal of Computing Science and Engineering
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• 제10권1호
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• pp.32-38
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• 2016

Navigating a large 3D virtual environment using a generic haptic device can be challenging since the haptic device is usually bounded by its own physical workspace. On the other hand, mouse interaction easily handles the situation with a clutching mechanism-simply lifting the mouse and repositioning its location in the physical space. Since the haptic device is used for both input and output at the same time, in many cases, its freedom needs to be limited in order to accommodate such a situation. In this paper, we propose a new mechanism called Z-Clutching for 3D navigation of a virtual environment by using only the haptic device without any interruption or sacrifice in the given degrees of freedom of the device's handle. We define the clutching state which is set by pulling the haptic handle back into space. It acts similarly to lifting the mouse off the desk. In this way, the user naturally feels the haptic feedback based on the depth (z-direction), while manipulating the haptic device and moving the view as desired. We conducted a user study to evaluate the proposed interaction technique, and the results are promising in terms of the usefulness of the proposed mechanism.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.334-337
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• 2002

The Quantum Hall Resistance(QHR) device which consists of GaAs/AlGaAs heterojunction structure is used for the realization of QHR Standard based on QHE. In order to characterize electrical contact resistances and dissipations of the device, it is slowly cooled down for eliminating thermal shock and unwanted noise. Then, the two properties are measured under 1.5 K and 5.15 T. Contact resistances are all within 1.2 Ω and longitudinal resistivities are all within 1 mΩ up to DC 90${\mu}$A. The results mean the device is operated well to realize the QHR Standard. To confirm it, the QHR Standard having the device is compared using a direct current comparator bridge with a 1 Ω resistance standard which the calibrated value is known from QHR standards maintained by other countries. The difference between them is agreed well within measurement uncertainty. It is thus considered that the properties of the device is estimated well and has good performance.

• 한국태양에너지학회 논문집
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• 제30권5호
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• pp.85-92
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• 2010

At the beginning the 21st century, we are interested in renewable energy especially photovoltaic. So, we have been installed PV at the building roofs so that we call it building integrated photovoltaic. But strictly speaking, installing the PV on the roof is not building integrated. There are few BIPV designs especially for balcony. In the apartment building, roof is good installing place for PV, but its area was limited. Now a day, built apartment building's heights are more and more increased so that the performance of installed PV on the roof cannot be enough to use even the public use. Thereby, we need the new space in the building to install the PV except the building roof. This study suggests the building facade balcony as a new space to install the PV with building integrated PV design. Hence, in this study, we are designed the movable BIPV shading device for apartment building balcony, and verified its performance with computer simulation. Developed device in this study can works as an electronic generation device and an overhang on the side balcony. As a result, the electronic generation performance of device contributes 15~30% to each apartment unit. The more unit width increase, the better contributed device generates.

• 한국전기전자재료학회논문지
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• 제29권10호
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• pp.625-629
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• 2016

Electrical and optical properties of the AC voltage driven organic light-emitting diodes were investigated by measuring the electroluminescence of the device. Device structure of ITO(170 nm)/TPD(40 nm)/Alq3(60 nm)/LiF(0.5 nm)/Al(100 nm) was manufactured using a thermal evaporation. Sinusoidal and square-type AC voltage was applied to the device using a function generator. Amplitude of the applied voltage was 9.0 V, and a frequency was varied from 50 Hz to 50 kHz. Electroluminescence out of the device was measured in a Si photodetector simultaneously with the applied voltage together. An intensity and a delayed residual luminescence from the device were depended on the frequency of the sinusoidal voltage. It is thought to be due to a contribution of the capacitive nature in the equivalent circuit of the device. An electron mobility was estimated using a time constant obtained from the luminescence of the device driven by the square-type AC voltage.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.311-316
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• 2001

소자의 고집적을 위한 특성분석 기술은 빠른 변화를 보이고 있다. 이에 따라 고집적 소자의 특성을 시뮬레이션을 통하여 이해하고 이에 맞게 제작하는 기술을 매우 중요한 과제 중의 하나가 되었다. 소자가 마이크론급에서 나노급 이하로 작아지면서 그에 맞는 소자개발을 위해 여러 가지 구조가 제시되고 있는데 본 논문에서는 TCAD를 이용하여 여러 가지 구조 중에서 고농도로 도핑된 ground plane 위에 적층하여 만든 EFI MOSFET와 LDD구조의 단점을 개선한 newEPI MOSFET에 대해 조사하였다. 이 구조의 특성과 임팩트이온화와 전계 그리고 I-V 특성 곡선을 저 농도로 도핑된 드레인(LDD) MOSFET와 비교 분석하였다. 또한 TCAD의 유용성을 조사하여 시뮬레이터로서 적합함과 나노구조 소자에서의 스켈링이론의 적합함을 보았다.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.171-176
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• 2005

In the information storage development, the trend of the storage device is to increase the recording density. Among such an effort, near-field probe recording is spotlighted as a method of high increasing recording density. For the successfully embodiment of storage device, the actuating mechanism of near-field probe is essentially designed. In this paper, we suggest the slider similar with conventional HDDs and design the slider using near- field probe for the purpose of applying the slider in order to control gap between probe and media. The most important object of slider design is to guarantee the flying ability and stability. For achievement of these design objects, we perform two step of optimal design process. The media is mod! eled as random displacement, which is only considered roughness of disk surface. The design slider is analyzed with dynamic state in assumed media. At this process, the optimal model is confirmed to stable flying stability.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.1192-1195
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• 2017

본 논문은 엔진 시험시 엔진의 후단에 설치되어 엔진 내부의 상태를 감시하는 영상장치의 내열 특성에 관한 것으로, 엔진 시험설비에 사용되는 영상프로브 소개 및 개발에 관한 내용을 담고 있다. 엔진 후단의 영상장치는 고온고압 환경에 노출되어 있어서 장치형상 변경 및 냉각수 공급으로 장치의 안정성을 확보해야 한다. 국방과학연구소의 엔진 시험 장치의 후단에 영상프로브가 설치되어 있으며, 내열특성을 반영하여 설계하여 장치의 안정성을 확보하였다.