• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.405-406
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• 2012

A sensor network is composed of a large number of sensor nodes which have sensing, computation and wireless communication capabilities. The sensor node sends such collected data, usually via radio transmitter, to a command center (sink) either directly or through a data concentration center (a gateway). These sensor networks can be used for various application areas such as health, military, home network, managing inventory, monitoring disaster areas and so on. Moreover, owing to the rapid growth of mobile technology, high-performance smartphones are widespread and in increasing cases are utilized as a terminal device. In this paper, we propose a home management system using smartphone and sensor networks.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.205-207
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• 2005

센서 네트워크는 않은 수의 센서 노드들로 구성된 네트워크로 센서를 통한 주변 정보 감지 및 감지된 정보를 처리하는 기능을 수행한다. 최근 유비쿼터스 컴퓨팅 개념의 도입과 함께 이를 실생활에 구현하기 위한 기반 기술로 큰 관심을 모으고 있다. 그러나 센서 네트워크의 일상 생활 시스템에서의 의존도가 높아질수록 이로 인한 위험성 또한 높아 질 수밖에 없다. 본 논문에서는 센서 네트워크에서의 보안 서비스를 제공하기 위하여 필수적인 키 관리 기술을 고찰하고 효율적인 키 관리 방법을 제안하고자 한다. 센서 네트워크의 구축 시 센서 노드들의 배치 특성을 고려하여 키 스트링 풀을 설정하고, 배치된 센서 노드의 위치에 따라 필요한 키를 집중적으로 분배하여 센서 네트워크 내의 공통 키 설정 확률을 높이고 센서 노드의 메모리 소모량을 줄이는 키 관리 방법을 고안하였다.

• Proceedings of the Safety Management and Science Conference
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• 2013.11a
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• pp.539-546
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• 2013

본 연구는 승마용 안전모의 신뢰성 확보를 위해 안전기준을 정립하기 위한 연구이다. 국내 외 레저 스포츠 안전모 관련 안전기준을 비교 분석하여 도출한 주요 시험평가방법을 현재 국내에 유통 중인 중저가 승마용 안전모를 대상으로 성능시험을 하였다. 충격흡수성 시험 시 1축과 3축 가속도 센서를 이용한 시험방법에 대해서 성능평가 데이터를 통해 1축 가속도 센서를 이용한 충격흡수성 시험으로 선정하였다. 유지시스템의 강도시험에서 헤드 폼 서포트 방식과 후크 서포트 방식으로 구분되던 것을 시료에 손상 없이 시험 가능한 헤드 폼 서포트 방식으로 결정하였다. 이와 같이 승마용 안전모의 안전기준을 정립하여 제품의 안전성 및 신뢰성을 확보하고 나아가 "품질경영 및 공산품 안전 관리법"에 규정함으로써 자국민의 안전을 확보하고 중국산 저가 제품에 대한 시장진입장벽을 구축하여 경쟁력 있는 안전모 시장을 구축하기를 기대한다.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1445-1462
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• 2022

Compact Advanced Satellite 500-4 (CAS500-4), which is scheduled to be launched in 2025, is a mid-resolution satellite with a 5 m resolution developed for wide-area agriculture and forest observation. To utilize satellite images, it is important to establish a precision sensor model and establish accurate geometric information. Previous research reported that a precision sensor model could be automatically established through the process of matching ground control point (GCP) chips and satellite images. Therefore, to improve the geometric accuracy of satellite images, it is necessary to improve the GCP chip matching performance. This paper proposes an improved GCP chip matching scheme for improved precision sensor modeling of mid-resolution satellite images. When using high-resolution GCP chips for matching against mid-resolution satellite images, there are two major issues: handling the resolution difference between GCP chips and satellite images and finding the optimal quantity of GCP chips. To solve these issues, this study compared and analyzed chip matching performances according to various satellite image upsampling factors and various number of chips. RapidEye images with a resolution of 5m were used as mid-resolution satellite images. GCP chips were prepared from aerial orthographic images with a resolution of 0.25 m and satellite orthogonal images with a resolution of 0.5 m. Accuracy analysis was performed using manually extracted reference points. Experiment results show that upsampling factor of two and three significantly improved sensor model accuracy. They also show that the accuracy was maintained with reduced number of GCP chips of around 100. The results of the study confirmed the possibility of applying high-resolution GCP chips for automated precision sensor modeling of mid-resolution satellite images with improved accuracy. It is expected that the results of this study can be used to establish a precise sensor model for CAS500-4.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1658-1661
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• 2010

유비쿼터스 시대가 도래하면서 인프라 중 하나인 센서네트워크에 대한 연구가 활발하게 진행되고 있다. 배터리를 사용하는 센서들의 특성상 네트워크 수명을 최대화하는 것이 주요 이슈 중 하나인데, 모바일 싱크를 이용하여 패킷 전송에 소비되는 에너지 로드 밸런싱을 통해 효율적인 결과를 얻을 수 있었다. 전체 센서들의 잔여 에너지와 그 평균과의 편차를 싱크를 움직이는 기준으로 하는 휴리스틱 알고리즘을 제안하였고 최적에 가까운 결과를 얻었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2237-2246
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• 2012

A bias circuit required for an oral sensor is manufactured inside the oral sensor chip to reduce its size and cost. The proposed DC-DC converter supplies the required reference and bias currents for their corresponding regulators by using IREF of the reference current generator. Their target voltages of the voltage regulators are regulated by the negative mechanism by generating their reference voltages required for their corresponding regulators. In addition, a constant current IB0/IB1 is supplied by being mirrored by a current mirror ratio and then VREF is generated. It is confirmed by measurements that the average volatge, ${\sigma}$, and $4{\sigma}$ of the designed DC-DC converter for intra oral sensors with a $0.18{\mu}m$ X-ray CMOS process are within their required ranges. And the line-pair pattern image shows a high-resolution characteristic without blurring. Also, a good oral image can be obtained.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.4 s.22
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• pp.41-50
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• 2002

RPM is the one of the sensor models which is proposed by Open GIS Consortium (OGC) as image transfer standard. And it is the sensor model for end-users using IKONOS, a commercial pushbroom satellite, imagery which provide about 1m ground resolution. Parameters called RPC which is IKONOS RFM coefficients are serviced to end-users. But if some users try to make additional effort to get rigorous geo-spatial information, it is necessary to apply mathematic or abstract sensor models, because vendors don't offer any ancillary data for physical sensor models such as satellite orbit and navigation. Abstract sensor models such as pushbroom Direct Linear Transform (DLT) require many GCPs well distributed in imagery, and mathematic sensor model such as RFM, polynomials need much more GCPs. Therefore RPC modification using additional a few GCPs is the best solution. In this paper, two methods are proposed to modify RPC. One is method to use pseudo GCPs generated in normalized cubic, and another method uses parameters observations and a few GCPs. Through two methods, we get improvement of accuracy 50% and over.

• Journal of the Korean Magnetics Society
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• v.14 no.4
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• pp.138-142
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• 2004

Uncertainty and characteristics of the developed current sensor by means of two identically wound magnetic cores forming a ring like for measurement of a low DC current such as leakage current was described in this paper. This transducer consists of a sensor type of a current transformer, peak value detectors, a reference alternating low frequency voltage oscillator, precision measuring circuits to measure the output signals of sensor with harmonics, and can be measured up to 2 A at DC current. The resolution and sensitivity of the sensor were 0.1㎃ and 10㎷/㎃, respectively.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.276-277
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• 2007

본 논문에서는 미량의 세포를 포함한 용액 내에서 세포의 산소호흡량을 측정하기 위해 FEP(Fluorinated Ethylene Propylene)를 멤브레인으로 사용한 Clark-type 센서를 제안하였다. 제안된 Clark-type 센서는 3-전극 시스템을 구성하는 유리 기판, 산소를 선택적으로 투과 시키는 FEP 멤브레인과 세포를 담을 수 있는 PDMS reservoir로 구성된다. 산소 센서의 3-전극 시스템에서 작업 전극과 상대 전극으로는 Au, 기준 전극으로는 Ag/AgCl을 사용하였다. 기준 전극은 Ag 전극을 0.1M KCl/Tris-HCl 용액에서 chlorination하여 표면에 AgCl이 형성되도록 하였고, OCP(Open Circuit Potential) test를 수행한 결과 2시간 동안 안정적인 OCP 특성을 보여 좋은 내구성을 가짐을 확인하였다. 또한, 산소 유무에 따른 cyclic voltammetry 그래프의 차이를 확인하고, amperometry로 감도 및 반응 시간, 선형성을 측정/분석하였다. 제작된 산소 센서는 40초의 90% 반응 시간과 0.994의 아주 좋은 선형 상관계수를 보여주었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.452-456
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• 2002

The sensor based control system has some sensor fault while operating in the field. In this paper, a sensor fault detection and reconstruction system for a sun tracking controller has been researched by using polynomial regression and principle component analysis approach. The developed sun tracking system controls tow actuators with sensor based mechanism as on-line control and sun orbit information as off-line control, alternatively. To show the validity of the developed system, several experiments were illustrated.