• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.444-447
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• 2004

A heart diagnosis system adopts hundreds of Superconducting Quantum Interface Device(SQUID) sensors for precision MCG(Magnetocardiogram) or MEG(Magnetoencephalogram) signal acquisitions. This system requires correct and real-time data acquisition from the sensors in a required sampling interval, i.e., 1 mili-second. This paper presents our hardware design and test results, to acquire data from 256 channel analog signal with 1-ksample/sec speed, using 12-bit 8-channel ADC devices, SPI interfaces, parallel interfaces, and 8-bit microprocessors. We chose to implement parallel data transfer between microprocessors as an effective way of achieving such data collection. Our result concludes that the data collection can be done in 250 ${\mu}sec$ time-interval.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.321-323
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• 2015

Monitoring crane motion in real time is the first step to identifying and mitigating crane-related hazards on construction sites. However, no accurate and reliable crane motion capturing technique is available to serve this purpose. The objective of this research is to explore a method for real-time crane motion capturing and investigate an approach for assisting hazard detection. To achieve this goal, this research employed various techniques including: 1) a sensor-based method that accurately, reliably, and comprehensively captures crane motions in real-time; 2) computationally efficient algorithms for fusing and processing sensing data (e.g., distance, angle, acceleration) from different types of sensors; 3) an approach that integrates crane motion data with known as-is environment data to detect hazards associated with lifting tasks; and 4) a strategy that effectively presents crane operator with crane motion information and warn them with potential hazards. A prototype system was developed and tested on a real crane in a field environment. The results show that the system is able to continuously and accurately monitor crane motion in real-time.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.271-274
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• 2000

Gas sensor materials capable of detecting hydrogen gases (H$_2$) or nitrogen oxides (NO$\_$x/, primarily NO and NO$_2$) with high sensitivity have attracted much interest in conjunction with the growing concern to the protection of global environments. Beside conventional sensor materials, such as semiconductors., conducting polymers and solid electrolytes, the potential of sensor materials with a new method for detecting hydrogen gases or nitrogen oxides gas has also been tested. The breakdown voltage of porous varistors shifted to a low electric field upon exposure to H$_2$ gas, whereas it shifted to a reverse direction in an atmosphere containing oxidizing gases such as O$_3$ and NO$_2$ in the temperature range of 300 to 600$^{\circ}C$. Furthermore, it was found that the magnitude of the breakdown voltage shift, i. e. the magnitude of sensitivity, was well correlated with gas concentration, and that the H$_2$ sensitivity was improved by controlling the composition of the Bi$_2$O$_3$ rich grain boundary phase. However, NO$\_$x/ sensing properties of porous varistors have not been studies in detail. The objective of the present study is to investigate the effect of the composition of the Bi$_2$O$_3$ rich grain boundary phase and other additive such as A1$_2$O$_3$ on the hydrogen gases (H$_2$) sensing properties of porous ZnO based varistors.

• Smart Structures and Systems
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• 제19권1호
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• pp.1-10
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• 2017

The operation of subway trains induces secondary structure-borne vibrations in the nearby underground spaces. The vibration, along with the associated noise, can cause annoyance and adverse physical, physiological, and psychological effects on humans in dense urban environments. Traditional tethered instruments restrict the rapid measurement and assessment on such vibration effect. This paper presents a novel approach for Wireless Smart Sensor (WSS)-based autonomous evaluation system for the subway train-induced vibrations. The system was implemented on a MEMSIC's Imote2 platform, using a SHM-H high-sensitivity accelerometer board stacked on top. A new embedded application VibrationLevelCalculation, which determines the International Organization for Standardization defined weighted acceleration level, was added into the Illinois Structural Health Monitoring Project Service Toolsuite. The system was verified in a large underground space, where a nearby subway station is a good source of ground excitation caused by the running subway trains. Using an on-board processor, each sensor calculated the distribution of vibration levels within the testing zone, and sent the distribution of vibration level by radio to display it on the central server. Also, the raw time-histories and frequency spectrum were retrieved from the WSS leaf nodes. Subsequently, spectral vibration levels in the one-third octave band, characterizing the vibrating influence of different frequency components on human bodies, was also calculated from each sensor node. Experimental validation demonstrates that the proposed system is efficient for autonomously evaluating the subway train-induced ambient vibration of underground spaces, and the system holds the potential of greatly reducing the laboring of dynamic field testing.

• International Journal of Computer Science & Network Security
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• 제24권2호
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• pp.53-58
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• 2024

This paper presents a novel miniaturized 3-D cubic antenna for use in wireless sensor network (WSN) application. The geometry of this antenna is designed as a cube including a meander dipole antenna. A truly omnidirectional pattern is produced by this antenna in both E-plane and H-plane, which allows for non-intermittent communication that is orientation independent. The operating frequency lies in the ISM band (centered in 2.45 GHz). The dimensions of this ultra-compact cubic antenna are 1.25*1.12*1cm3 which features a length dimension λ/11. The coefficient which presents the overall antenna structure is Ka=0.44. The cubic shape of the antenna is allowing for smart packaging, as sensor equipment may be easily integrated into the cube hallow interior. The major constraint of WSN is the energy consumption. The power consumption of radio communication unit is relatively high. So it is necessary to design an antenna which improves the energy efficiency. The parameters considered in this work are the resonant frequency, return loss, efficiency, bandwidth, radiation pattern, gain and the electromagnetic field of the proposed antenna. The specificity of this geometry is that its size is relatively small with an excellent gain and efficiency compared to previously structures (reported in the literature). All results of the simulations were performed by CST Microwave Studio simulation software and validated with HFSS. We used Advanced Design System (ADS) to validate the equivalent scheme of our conception. Input here the part of summary.

• 환경영향평가
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• 제27권5호
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• pp.475-488
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• 2018

현재 도심 소하천의 식생조사는 주로 현장조사에 의존하여 이루어진다. UAV NIR(Unmanned Aerial Vehicle Near Infrared) 영상은 매우 낮은 고도에서 취득할 수 있어 도심 소하천과 같이 폭이 매우 좁은 표적(10m 내외)에 필요한 정보를 효율적으로 제공할 수 있다. 하지만 UAV NIR영상이 도심소하천의 식생 조사도구로서 검증되지 않아, UAV NIR 영상과 현장사진을 통합한 선행연구는 존재하지 않는다. 따라서 본 연구에서는 전통적인 원격탐사의 영역이 아니었던 국부적인 대상인 도심소하천 식생조사에서 UAV NIR 영상과 현장사진의 비교평가를 실시하였다. 하천 식생조사 결과를 실무에서 활용하는데 필요한 요구 사항을 고려하여 광역공간정보, 미시적인 정보 및 정량적인 데이터 확보 등 다양한 측면에서 분석이 수행되었다. UAV NIR 영상은 전통적인 현장조사에서 취득할 수 없었던 거시적인 주변 환경(예: 인공적인 토지 이용에 따른 영향)에 따른 식생군집패턴의 변화를 추적할 수 있었다. 현장조사는 전세계적으로 도심 소하천 식생 모니터링 방법으로 정착되었지만, 거시적인 정보의 취득에서 상당한 한계를 노출하였으며 정량적인 정보를 확보하는 과정에서도 신뢰성에 한계를 노출하였다. 본 연구가 도심 소하천의 식생조사에서 거시적이고 정량화되고 객관적인 데이터가 부재하여 직면하였던 한계를 극복할 수 있는 계기가 되어 향후 UAV NIR 원격탐사에서 확보할 수 있는 정보의 수준을 파악할 수 있는 중요한 참고자료가 될 수 있을 것으로 사료된다.

• 한국정보통신학회논문지
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• 제12권9호
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• pp.1575-1583
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• 2008

기존의 유선 네트워크에 비하여 무선 네트워크는 저전력, 저비용, 자율 네트워크 구성 등의 장점을 가지고 있어 이를 대체하는 연구가 많이 진행되고 있다. 건축물 인상/기초보강 공사는 고도의 정밀한 계측이 병행되어야 하기 때문에 건축물에 각종 센서를 설치하고 그 센서를 데이터 로거에 연결하여 센서 데이터를 모니터링 하면서 작업한다. 그러나 이러한 유선 데이터 로거 방식은 배선에 많은 시간이 소요되고 설치된 배선은 공사에 방해가 된다. 또한 유선 데이터 로거 방식에서는 단순히 수치와 그래프 형태만으로 표시되는 한계성 때문에 공사 진행에 필요한 신속한 의사 결정을 효과적으로 지원하는 데에는 한계가 있다. 이러한 유선 데이터 로거 방식의 배선 관련 문제점을 해결하고 신속한 의사 결정을 지원하기 위하여 무선 센서 네트워크 기반의 모니터링 시스템을 설계 및 구현하였다. 이 시스템의 성능, 정확성, 유용성을 검증하기 위하여 시뮬레이션과 현장 실험을 실시하였다. 그 결과로 본 연구의 무선 센서 네트워크 방식이 기존 유선 데이터 로거 방식보다 설치와 배포가 용이하고, 건축물과 센서가 3D로 표현되고 움직임으로써 사용자가 직관적이고 전체적인 모니터링이 가능하고, 유선 방식만큼의 정밀도를 제공할 뿐만 아니라 다수의 센서에 대해서도 실제로 적용 가능한 성능을 보임을 검증하였다.

• 한국음향학회지
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• 제43권4호
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• pp.414-421
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• 2024

본 논문에서는 누설에 의한 플랜트 대형사고 방지를 위한 기술로써, 다채널 음향 센서 모듈을 활용해 잔향 및 반향 영향이 큰 환경에서 배관 누설 소음을 탐지할 수 있는 시스템을 설계하고 검증한다. 정사면체 형태로 배열한 4채널 마이크로폰을 하나의 센서 모듈로 설계해, 3차원 음향 인텐시티 벡터를 측정한다. 잔향 및 반향 영향이 큰 환경에서는 센서 모듈 각각의 인텐시티 벡터 측정 오차가 평균적으로 증가하기 때문에, 다수의 센서 모듈을 현장에 배치하여 실제 음원 위치를 추정해야 한다. 따라서, 여러 쌍의 센서 모듈로부터 얻은 3차원 벡터 간 교점을 이용해 음원이 위치한 지점들을 추정해내고, 해당 지점들 중 이상치(예, 반사의 영향으로 현장 외부로 추정된 지점, 주변 구조물에 의한 회절 영향으로 평균 지점에서 먼 지점으로 추정된 지점 등)를 검출해 제외하는 알고리즘을 제안하였다. 현장의 도면상에 누설음 추정 위치 좌표를 1 s 이내에 가시화해 실시간으로 누설음이 발생한 위치를 발견해 즉각적인 대응이 가능한 시스템을 구성하고 검증한다. 본 연구는 대형 플랜트의 사고 대응 능력 향상 및 안전성 확보에도 기여할 수 있을 것으로 기대된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.549-549
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• 2012

Early detection of cancer biomarkers in the blood is of vital importance for reducing the mortality and morbidity in a number of cancers. From this point of view, immunosensors based on nanowire (NW) and carbon nanotube (CNT) field-effect transistors (FETs) that allow the ultra-sensitive, highly specific, and label-free electrical detection of biomarkers received much attention. Nevertheless 1D nano-FET biosensors showed high performance, several challenges remain to be resolved for the uncomplicated, reproducible, low-cost and high-throughput nanofabrication. Recently, two-dimensional (2D) graphene and reduced GO (RGO) nanosheets or films find widespread applications such as clean energy storage and conversion devices, optical detector, field-effect transistors, electromechanical resonators, and chemical & biological sensors. In particular, the graphene- and RGO-FETs devices are very promising for sensing applications because of advantages including large detection area, low noise level in solution, ease of fabrication, and the high sensitivity to ions and biomolecules comparable to 1D nano-FETs. Even though a limited number of biosensor applications including chemical vapor deposition (CVD) grown graphene film for DNA detection, single-layer graphene for protein detection and single-layer graphene or solution-processed RGO film for cell monitoring have been reported, development of facile fabrication methods and full understanding of sensing mechanism are still lacking. Furthermore, there have been no reports on demonstration of ultrasensitive electrical detection of a cancer biomarker using the graphene- or RGO-FET. Here we describe scalable and facile fabrication of reduced graphene oxide FET (RGO-FET) with the capability of label-free, ultrasensitive electrical detection of a cancer biomarker, prostate specific antigen/${\alpha}$ 1-antichymotrypsin (PSA-ACT) complex, in which the ultrathin RGO channel was formed by a uniform self-assembly of two-dimensional RGO nanosheets, and also we will discuss about the immunosensing mechanism.

• Journal of Animal Science and Technology
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• 제65권3호
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• pp.638-651
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• 2023

The objective of this study was to quantitatively estimate the level of grazing area damage in outdoor free-range pig production using a Unmanned Aerial Vehicles (UAV) with an RGB image sensor. Ten corn field images were captured by a UAV over approximately two weeks, during which gestating sows were allowed to graze freely on the corn field measuring 100 × 50 m². The images were corrected to a bird's-eye view, and then divided into 32 segments and sequentially inputted into the YOLOv4 detector to detect the corn images according to their condition. The 43 raw training images selected randomly out of 320 segmented images were flipped to create 86 images, and then these images were further augmented by rotating them in 5-degree increments to create a total of 6,192 images. The increased 6,192 images are further augmented by applying three random color transformations to each image, resulting in 24,768 datasets. The occupancy rate of corn in the field was estimated efficiently using You Only Look Once (YOLO). As of the first day of observation (day 2), it was evident that almost all the corn had disappeared by the ninth day. When grazing 20 sows in a 50 × 100 m² cornfield (250 m²/sow), it appears that the animals should be rotated to other grazing areas to protect the cover crop after at least five days. In agricultural technology, most of the research using machine and deep learning is related to the detection of fruits and pests, and research on other application fields is needed. In addition, large-scale image data collected by experts in the field are required as training data to apply deep learning. If the data required for deep learning is insufficient, a large number of data augmentation is required.