• Journal of Communications and Networks
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• v.15 no.4
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• pp.422-429
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• 2013

Advances in wireless sensor network (WSN) technology have enabled small and low-cost sensors with the capability of sensing various types of physical and environmental conditions, data processing, and wireless communication. In the WSN, the sensor nodes have a limited transmission range and their processing and storage capabilities as well as their energy resources are limited. A triple umpiring system has already been proved for its better performance in WSNs. The clustering technique is effective in prolonging the lifetime of the WSN. In this study, we have modified the ad-hoc on demand distance vector routing by incorporating signal-to-noise ratio (SNR) based dynamic clustering. The proposed scheme, which is an efficient and secure routing protocol for wireless sensor networks through SNR-based dynamic clustering (ESRPSDC) mechanisms, can partition the nodes into clusters and select the cluster head (CH) among the nodes based on the energy, and non CH nodes join with a specific CH based on the SNR values. Error recovery has been implemented during the inter-cluster routing in order to avoid end-to-end error recovery. Security has been achieved by isolating the malicious nodes using sink-based routing pattern analysis. Extensive investigation studies using a global mobile simulator have shown that this hybrid ESRP significantly improves the energy efficiency and packet reception rate as compared with the SNR unaware routing algorithms such as the low energy aware adaptive clustering hierarchy and power efficient gathering in sensor information systems.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.121-127
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• 2004

A reflection type optical fiber line sensor based on the speckle detection has been developed using the optical fiber mirror with the reflectance of 72 %. Some experiments were carried on with the automobile and the 500 m length multimod fiber. When the automobile passed on the fiber sensor, two abrupt changes of the output waveform occured like the transmission type sensor based on the speckle variations. The signal to noise ratio of this sensor was about 40 dB.

• Journal of Digital Contents Society
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• v.19 no.9
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• pp.1803-1810
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• 2018

Recently, many researches related to IoT (Internet of Things) have been actively conducted. In order to improve the context aware function of smart wearable devices using the IoT, we proposed a noise reduction method for the event data of the sensor part. In thisstudy, the adoption of the low - pass filter induces the attenuation of the abnormally measured value, and the benefit was obtained from the situation recognition using the event data of the sensor. As a result, we have validated attenuation for abnormal or excessive noise using event data detected and reported by 3-axis acceleration sensors on some devices, such as smartphones and smart watches. In addition, various pattern data necessary for real - time context aware were obtained through noise pattern analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.811-816
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• 2011

This study includes investigation on sound transmission phenomena through a structural panel including structural vibration and feedback control methodology to minimize the transmission. Focus is placed on finding the relation between vibration pattern and sound transmission, and on finding optimal sensor and actuator location. A simple analog feedback control circuit is designed and implemented to verify the approach.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.189-192
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• 2009

This paper presents comparison and analysis of various CFA patterns which are used in single sensor digital camera. There are several patterns which are already used, however, images are sometimes darker or brighter than what human see in real life. Also, images show some noise and blurring. To overcome this problems, many studies on the patterns have been discussed. We carry out experiment with seven patterns including the Bayer pattern. The bilinear method is selected for a interpolation method. The experimental result indicates that image quality is not affected by individual patterns and each pattern requires its own interpolation method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.181-184
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• 2014

Loose Parts Monitoring System(LPMS) monitors loosened or detached parts and foreign parts inside the pressure boundary of a reactor coolant system (RCS). It is difficult to discriminate valid signal from LPMS alarms at full power since the signal pattern by thermal shocks and structure friction are similar to those by loose metal impacts. In addition, It is more difficult to discriminate the impact signals induced by the rod driving, sensor hard-line movement and loosened component since they have similar frequency characteristics with valid signals. This paper classifies the signal patterns by analyzing actual LPMS signal captured during nuclear power plant operation.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.2
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• pp.157-164
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• 2014

In this paper, we design a gripping force control system using tactile sensor to prevent slip when gripper tries to grasp and lift an object. We use a flexible tactile sensor for measuring uniplanar pressure on gripper's finger and develop an algorithm to detect the onset of slip using the sensor output. We also use a flexible pressure sensor to measure the normal force. In addition, various signal processing techniques are used to reduce noise included in the sensor output. A 3-finger gripper is used to grasp and lift up a cylindrical object. The tactile sensor is attached on one of fingers, and sends output signals to detect slip. Whenever the sensor signal is similar to the slip pattern, gripper force is increased. In conclusion, this research shows that slip can be detected using the tactile sensor and we can control gripping force to eliminate slip between gripper and object.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.4
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• pp.388-396
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• 2012

In this paper, a $320{\times}240$ pixel, 80 frame/s CMOS image sensor with a low power dual correlated double sampling (CDS) scheme is presented. A novel 8-bit hold-and-go counter in each column is proposed to obtain 10-bit resolution. Furthermore, dual CDS and a configurable counter scheme are also discussed to realize efficient power reduction. With these techniques, the digital counter consumes at least 43% and at most 61% less power compared with the column-counters type, and the frame rate is approximately 40% faster than the double memory type due to a partial pipeline structure without additional memories. The prototype sensor was fabricated in a Samsung $0.13{\mu}m$ 1P4M CMOS process and used a 4T APS with a pixel pitch of $2.25{\mu}m$. The measured column fixed pattern noise (FPN) is 0.10 LSB.

• Journal of Magnetics
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• v.12 no.1
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• pp.40-44
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• 2007

The Planar Hall effect in a spin valve structure has been applied as a biosensor being capable of detecting $Dynabeads^{(R)}$ M-280. The sensor performance was tested under the application of a DC magnetic field where the output signals were obtained from a nanovoltmeter. The sensor with the pattern size of $50{\times}100{\mu}m^2$ has produced high sensitivity; especially, the real-time profiles by using that sensor revealed significant performance at external applied magnetic field of around 7.0 Oe with the resolution of 0.04 beads per $\mu m^2$. Finally, a successful array including 24 patterns with the single sensor size of $3{\times}3{\mu}m^2$ has shown the uniform and stable signals for single magnetic bead detection. The comparison of this sensor signal with the others has proved feasibility for biosensor application. This, connecting with the advantages of more stable and high signal to noise of PHR sensor's behaviors, can be used to detect the biomolecules and provide a vehicle for detection and study of other molecular interaction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.10
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• pp.677-684
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• 2015

It is often necessary to predict the vibration patterns of the structures from the signals of finite number of vibration sensors. This study presents the optimal placement of vibration sensors by applying the genetic algorithm and the modal expansion method. The modal expansion method is used to estimate the vibration response of the whole structure. The genetic algorithm is used to estimate the optimal placement of vibration sensors. Optimal sensor placement can be obtained so that the fitness function is minimized in the genetic algorithm. This paper discusses the comparison of the performances of two types of fitness functions, modal assurance criteria(MAC) and condition number( CN). As a result, the estimation using MAC shows better performance than using CN.