• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.489-492
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• 1997

Partial discharge characteristics of normal butyl acrylate grafted low density polyethylenes were investigated by an ultrasonic sensor made of ceramic piezoelectric material. It was found that the partial discharging activities in normal butyl acrylate grafted low density polyethylenes were considerably suppressed compared to those in plain low density polyethylene. It was found that acrylic acid grafted polyethylene was more effective than normal butyl acrylate grafted low density polyethylene.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.527-532
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• 2001

In this paper, we will propose the new method that estimates the sensing ability of HH smart sensor. We have developed a new signal processing method that can distinguish among different materials relatively. The HH smart sensor was developed for recognition of materials. We made the HH smart sensor in our experiment. Then, we estimated the ability to recognize objects according to acceleration value. We estimated the sensing ability of HH smart sensor with the $R_{SAI}$ method. Experiments and analysis were executed to estimate the ability to recognize objects according to acceleration value changing. Dynamic characteristics of HH smart sensor were evaluated relatively through a new $R_{SAI}$ method that uses the power spectrum density. Applications of this method are for finding abnormal conditions of objects (auto-manufacturing), feeling of objects (medical product), robotics, safety diagnosis of structure, etc.

• 한국공작기계학회논문집
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• 제13권1호
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• pp.22-27
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• 2004

A new method that estimates the sensing ability of HH smart sensor is proposed. The new signal processing method have been developed that can distinguish among different materials relatively. The HH smart sensor was developed far recognition of materials. The HH smart sensor was made for experiment. Then, it was estimated the ability to recognize objects according to acceleration value. The sensing ability of HH smart sensor has been estimated with the $R_{SAI}$ method. Experiments and analysis were executed to estimate the ability to recognize objects according to acceleration value changing. Dynamic characteristics of HH smart sensor were evaluated relatively through a new $R_{SAI}$ method that uses the power spectrum density. Applications of this method are for finding abnormal conditions of objects (auto-manufacturing), feeling of objects (medical product), robotics, safety diagnosis of structure, etc.

• 로봇학회논문지
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• 제16권3호
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• pp.189-198
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• 2021

In this paper, we introduce the software/hardware system that can reliably calculate the distance from sensor to the model regardless of point cloud density. As the 3d point cloud map is widely adopted for SLAM and computer vision, the accuracy of point cloud map is of great importance. However, the 3D point cloud map obtained from Lidar may reveal different point cloud density depending on the choice of sensor, measurement distance and the object shape. Currently, when measuring map accuracy, high reflective bands are used to generate specific points in point cloud map where distances are measured manually. This manual process is time and labor consuming being highly affected by Lidar sparsity level. To overcome these problems, this paper presents a hardware design that leverage high intensity point from three planar surface. Furthermore, by calculating distance from sensor to the device, we verified that the automated method is much faster than the manual procedure and robust to sparsity by testing with RGB-D camera and Lidar. As will be shown, the system performance is not limited to indoor environment by progressing the experiment using Lidar sensor at outdoor environment.

• 센서학회지
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• 제30권6호
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• pp.364-368
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• 2021

We developed a highly efficient organic photovoltaic (OPV) cell with a poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)]:[6,6]-phenyl-C71-butyric acid methyl ester active layer for harvesting lower-intensity indoor light energy to power various self-powered sensor systems that require power in the microwatt range. In order to achieve higher power conversion efficiency (PCE), we first optimized the thickness of the active layer of the OPV cell through optical simulations. Next, we fabricated an OPV cell with optimized active layer thickness. The device exhibited a PCE of 12.23%, open circuit voltage of 0.66 V, short-circuit current density of 97.7 ㎂/cm², and fill factor of 60.53%. Furthermore, the device showed a maximum power density of 45 ㎼/cm², which is suitable for powering a low-power (microwatt range) sensor system.

• 한국ITS학회 논문지
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• 제21권2호
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• pp.17-32
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• 2022

본 연구에서는 개별 차량의 차두 시간(time headway) 정보를 활용하여 고속도로 환경에서의 단일 링크에 대한 교통류 모형(flow-density diagram)을 추정하는 방법에 대해 탐구한다. 차두 시간 기반 교통류 모형(empirical flow-density diagram) 연구를 위해 차량용 비전 센서가 탑재된 실험 차량에서 9개월동안 수집된 데이터의 전처리 및 GIS 기반 맵 매칭을 수행한다. 기존의 교통류 모델식을 활용한 차두 시간 기반 교통류 모형(empirical flow-density diagram)의 검증을 위해, 차량 검지기 기반의 VDS(Vehicle Detection System) 데이터(loop detection traffic data) 기반 교통류 모형과 결과 비교 및 분석을 수행한다. 차두 시간 기반 교통류 모형의 추정 오차 원인을 분석하기 위해 각 교통류 모형의 차두 시간 및 차두 거리의 확률분포와 단위시간 교통량과 차량 밀도의 표준편차를 활용하였다. 분석 결과 링크 내 제한된 샘플 차량 대수 및 수집 데이터에 대한 주행환경 편향성이 추정 오차의 주된 요인이며. 이에 따른 추정 오차 개선을 위한 방법에 대해 제안한다.

• Agricultural and Biosystems Engineering
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• 제1권1호
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• pp.49-53
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• 2000

A magnet assembly is a critical element of a nuclear magnetic resonance(NMR) based sensor. Magnetic flux density and homogeneity are essential to its optimum performance. Geometry and magnet material properties determine the magnetic flux density and homogeneity of the assembly. This study was carried out to develop the design for a magnet assembly. A 2-D finite element model for the magnetic assembly was developed using ANSYS and evaluated the effects of adding shimming frames and steel bars in the corners of the rectangular steel cover which surrounded the magnet. The assembly was manufactured and evaluated. According to the ANSYS model, modified pole frames increased magnetic flux density by 8.3% and increased homogeneity by 83%. Addition of steel bars in the corners increased the magnetic flux density by 1%, and improved homogeneity up to three times. The difference between simulated and measured magnetic flux densities at the center point of the air gap was within 2.4%.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.207-211
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• 2004

The performance of an inductive position sensor has approved by previous research papers. In this paper, magnetic circuit model of a ring-type multi-pole insuctive position sensor is described. The magnetic circuit model is required to design in ductive position sensor as well as draw a fault tolerance algorithm. Using the magnetic circuit theory, we derived the relationship between voltage applied and flux density in the normal air-gap. By idealizing the modulation/demodulation processes of signal processing circuit, sensor gain with respect to change of displacement is theoretically calculation using the magnetic circuit model, which validate the theoretical derivation.

• Journal of information and communication convergence engineering
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• 제5권4호
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• pp.300-304
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• 2007

Wireless sensor networks represent a new and exciting communication paradigm which could have multiple applications in future wireless communication. Therefore, performance analysis of such a wireless sensor network paradigm is needed in complex wireless channel. Wireless networks could be an important means of providing ubiquitous communication in the future. In this paper, the BER performance of uniform distributed wireless sensor networks is evaluated in non-Gaussian noise channel. Using an analytical approach, the impact of Av. BER performance relating the coherent BPSK system at the end of a multi-hop route versus the spatial density of sensor nodes and impulsive noise parameters A and $\Gamma$ is evaluated.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.165-170
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• 1995

This paper describes the fabrication and characteristics of a Si Hall sensor fabricated on a SOI (Si-on-insulator) structure. The SOI structure was formed by SDB(Si-wafer direct bonding) technology and the insulator of the SOI structure was used as the dielectrical isolation layer of a Hall sensor. The Hall voltage and sensitivity of the implemented SDB SOI Hall sensors showed good linearity with respect to the applied magnetic flux density and supplied current. The product sensitivity of the SDB SOI Hall sensor was average 600V/A.T and its value has been increased up to 3 times compared to that of bulk Si with buried layer of 10.mu.m. Moreover, this sensor can be used at high-temperature, high-radiation and in corrosive environments.