• Composites Research
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• v.27 no.4
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• pp.146-151
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• 2014

In this study, the experimental study has been performed by varying the polarization of the electric field and impact force to check the piezoelectric characteristics of piezoelectric paint sensor. Piezoelectric paint sensor used in this study is composed of epoxy resin with a hardener and PNN-PZT powder in 1:1 weight ratio. The dimensions of the paint sensor specimen are $40{\times}40{\times}1mm^3$ and regular specimens were made using a mold. The voids are removed from the specimen in the vacuum desiccator. Both upper side and bottom side of the paint sensor were coated with silver paste for making an electrode and then dried at room temperature for a day. The poling treatment has been carried out under controlled conditions of the electric field in order to check the effect of piezoelectric sensitivities, while the poling temperature was fixed at room temperature and the poling time was set to 30 min. The piezoelectric sensitivities have been measured by comparing output voltage from paint sensor with output force from impact hammer when the impact hammer hits the paint sensor. In result, the effect of the electric field has been evaluated for the sensitivity and describe the result.

• Composites Research
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• v.33 no.4
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• pp.228-233
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• 2020

In this paper, a single lap shear test was performed using a glass fiber reinforced composite material (GFRC). Pencil lead drawn paper sensor (PLDPS) was applied for single lap shear test being performed. Bisphenol-A epoxy and amine hardener were used as adhesives combining with composite materials. To make a difference in adhesive properties, the adhesive was cured under different conditions. PLDPS was made of a 4B pencil on A4 paper. Because graphite in a pencil was an electrically conductive substance, electric resistance (ER) could be measured. A change in ER was observed by a position where a PLDPS was attached to single lap shear specimens. It was confirmed that the change in ER was different depending on two attached positions and was observed by lap shear strain as well. In case the lap shear strain was large, the change in ER of PLDPS was high. This was because the larger the extension of the adhesive part, the larger the degree of bending of the specimen and thus the larger the distance change between two electrodes.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.123-132
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• 2012

Gas sensors has been used very differently that depending on following purposes; Automotive (exhaust gas, fuel mixture gas, oxygen, particulates), agriculture / food industry (fresh, stored, CO2, humidity, NH3, nitrogen oxide gas, organic gas, toxic gas emitted from pesticides and insecticides), industrial / medical (chemical gas, hydrogen, oxygen and toxic gases), military (chemical weapon), environmental measurements (CO and other air pollution consisting of sulfur and nitrogen gas), residential (LNG, LPG, butane, indoor air, humidity). The types of industrial toxic substances are known about 700 species and many of these exist in gaseous form under normal conditions. he multi-gas detection sensors will be developed for casualties that detect the most important and find easy three kinds of gases in marine plant; carbon dioxide(CO2), carbon(CO), ammonia(NH3). Package block consists of gas sensing device minor ingredient, rf front end, zigbee chip. Develope interworking technology between the sensor and zigbee chip inside a package. Conduct a performance test through test jig about prototype zigbee sensor module with rf output power and unwanted emission test. This research task available early address when poisonous gas leaked from large industrial site and contribution for workers' safety at the enclosed space.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.37-44
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• 1998

Lean burn combustion is an important concept for improving the fuel consumption and exhaust emissions. However, the lean burning is associated with increased cycle-to-cycle combustion variations due to the ignition instabilities and redu- ced flame propagation rates. Engine stability under lean mixture conditions could be improved by increasing flame speed through enhanced flow characteristics and by securing ignitability with improvement of ignition systems. The effects of flow motion and ignition characteristics on the combustion performances were investigated in a 4-valve SI engine. Flow motions of tumble-swirl were varied with a swirl control valve attached at the inlet ports, while ignition energy and its distribution were controlled in a high -frequency ignition system by changing spark duration and spark frequency. The improvement of lean burn performance by the optimum flow motion and ignition characteristics is discussed.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2075_2076
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• 2009

전력계통의 가장 중요한 설비인 전력용 유입변압기를 감시 진단하는 장치로서 유중가스 분석과 AE(Acoustic Emission) 센서를 이용한 PD 분석기능을 동시에 탑재한 진단 장치를 개발하였다. 두가지의 유입 변압기 진단 솔루션이 만났을때 얻어지는 시너지 효과에 대하여 분석하고 장치의 여러 가지 기능 및 활용방안에 대하여 논하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.73-74
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• 2015

3 차원 컨텐츠 제작은 많은 관심을 받고 있는 분야이다. 변위 지도로 표현 가능한 깊이 정보는 3 차원 컨텐츠를 생성하는데 필수적이다. 본 논문에서는 깊이 카메라 및 스테레오 카메라를 이용하여 정확한 변위 지도를 생성하는 방법을 제안한다. 제안하는 방법은 스테레오 영상 사이의 변위를 예측하기 위해서 깊이 카메라 정보를 3 차원 워핑 방식에 의해서 좌우 카메라 위치로 투영한다. 투영된 깊이 정보는 스테레오 영상의 크기에 맞춰서 업샘플링된다. 최종적으로 업샘플링된 깊이 카메라 정보와 스테레오 정보가 결합되어 정확한 변위 지도를 생성한다. 실험 결과는 제안하는 방법이 기존의 단일 센서를 이용한 방식에 비해서 좀더 정확한 결과를 생성함을 보여준다.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.138-140
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• 2005

A fuzzy ARTMAP neural network and a fuzzy ART neural network are proposed to identify $H_2S$, $NH_3$ and their mixtures and to estimate their concentrations, respectively. Features are extracted from a micro gas sensor array operated in a thermal modulation plan. After dimensions of the features are reduced by a preprocessing scheme, the features are fed into the proposed fuzzy neural networks. By computer simulations, the proposed methods are shown to be fast in learning and accurate in concentration estimating. The results are compared with other methods and discussed.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.130-132
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• 2005

This paper presents two ART-based neural networks for the identification of gas mixtures subject to the drift. A fuzzy ARTMAP neural network is used for classifying $H_2S$, $NH_3$ and their mixture gases including a reference gas. The other fuzzy ART neural network is utilized to detect the drift of a tin oxide gas sensor by tracking a cluster center of the reference gas. After detecting the drift, the previous cluster center of each gas is updated as much as the drift of the reference gas. By the simulations, the proposed method is shown to compensate the drift on-line without making many categories of target gases compared with the previous studies.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.252-254
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• 2009

본 논문에서는 저고도 탐지레이다 센서체계의 주파수 합성기는 송수신 장치의 기준 주파수원으로 이용될 국부 발진 주파수들을 생성해 내는 주파수 합성부에 대해 설명되었다. 주파수 합성기의 성능을 평가하기위하여 각 주파수 원들의 위상잡음 특성과 주파수 합성기의 스위칭 시간을 신호 혼합기를 이용하여 측정 하였으며, 그 결과 설계 시 제시한 30(usec)이하인 약18usec의 스위칭 시간이 대부분을 차지함을 알 수 있었다. 주파수 합성기에서 생성된 최종 출력 주파수는 저고도 탐지 레이다의 송수신 장치의 국부발진 주파수로 이용되므로 출력 레벨의 flatness를 측정하여 분석한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.579-582
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• 2005

현재는 정보화 시대를 뛰어넘어 유비쿼터스 시대를 맞이하고 있다. 센서 네트워크, 홈 네트워킹 기술과 텔레매틱스 등 각 분야에서 연구와 개발이 이루어지고 있다. 이렇게 유무선 네트워크 시스템이 통합적이고 유기적으로 제공되는 시대를 위한 프로그램으로 이동성을 지니고 서비스 형태의 행동을 지닐 수 있는 형태의 에이전트 시스템이 요구되고 있다. 다양해지는 서비스의 기능을 추가하거나 수정을 하기 위해서는 응용 프로그램 전체를 수정해야 하고 이러한 서비스들이 많아 질수록 프로그램은 이러한 서비스를 지니고 있어야 함은 물론이고 서비스를 제공하는 서버로서의 컴퓨터에 대한 신뢰성을 제공하기 어려운 실정이다. 이러한 문제를 해결하기 위해 혼합형인 P2P 시스템을 기반으로 그룹의 서비스를 제공을 위해 동작하는 관리 에이전트를 개발하는데 있어서의 시스템 자원의 감시모듈과 계정관리 시스템을 설계하고 동작 과정을 제시한다.