• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1559-1566
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• 2017

Recently in the IoT(Internet of Things) environment, a data collection in real-time through device's sensor has increased with an emergence of various devices. Collected data from IoT environment shows a large scale, non-uniform generation cycle and atypical. For this reason, the distributed processing technique is required to analyze the IoT sensor data. However if you do not consider the optimal scheduling for data and the processor of IoT in a distributed processing environment complexity increase the amount in assigning a task, the user is difficult to guarantee the QoS(Quality of Service) for the sensor data. In this paper, we propose APQTA(Adaptive Priority Queue-driven Task Allocation method for sensor data processing) to efficiently process the sensor data generated by the IoT environment. APQTA is to separate the data into job and by applying the priority allocation scheduling based on the deadline to ensure that guarantee the QoS at the same time increasing the efficiency of the data processing.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.154-161
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• 2000

As a mass flow controller is widely used in many manufacturing processes for controlling a mass flow rate of gas with accuracy of 1%, several investigators have tried to describe the heat transfer phenomena in a sensor tube of an MFC. They suggested a few analytic solutions and numerical models based on simple assumptions, which are physically unrealistic. In the present work, the heat transfer phenomena in the sensor tube of the MFC are studied by using both experimental and numerical methods. The numerical model is introduced to estimate the temperature profile in the sensor tube as well as in the gas stream. In the numerical model, the conjugate heat transfer problem comprising the tube wall and the gas stream is analyzed to fully understand the heat transfer interaction between the sensor tube and the fluid stream using a single domain approach. This numerical model is further verified by experimental investigation. In order to describe the transport of heat energy in both the flow region and the sensor tube, the Nusselt number at the interface between the tube wall and the gas stream as well as heatlines is presented from the numerical solution.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.12
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• pp.1173-1178
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• 2007

Ubiquitous sensor network (USN) is composed of many sensor nodes which are one of the simplest form of embedded system. In developing the sensor network system, a debugging tool is necessary to test and verify the system. Recently, a so-called packet analyzer has been developed for this purpose, and it supports IEEE 802.15.4 which is considered as the standard for the sensor network protocols. The major function of the packet analyzer is to take RF packets from sensor nodes and show the structure and the data of the packets graphically to the user. However, the conventional packet analyzers do not support remote control because they require a USB interface along with a personal computer. To make it available for remote control, we propose a new packet analyzer based on a server-client scheme in which a server program is implemented on embedded Linux and a client program is implemented on Windows for convenient use.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.151-162
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• 2010

In order to build up the ubiquitous computer environment, there are many researches on automatic identification, sensor networks, and home networks etc. EPCIS (EPC Information Services), which is proposed by EPCglobal, is a standard on the repository managing tag data that is needed to develop RFID application system. In this paper, the EPCIS repository is designed and implemented. It is able to search the object dependent upon general object recognition and environment information variation. And sensor data, which is also massive data and is changed with position, is integrated into RFID data in the system. By doing so, it is possible to do the convergence managements of object recognition with variations of USN (Ubiquitous Sensor Network) environment.

• Journal of Information Processing Systems
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• v.14 no.4
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• pp.926-940
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• 2018

In clustering-based approaches, cluster heads closer to the sink are usually burdened with much more relay traffic and thus, tend to die early. To address this problem, distance-aware clustering approaches, such as energy-efficient unequal clustering (EEUC), that adjust the cluster size according to the distance between the sink and each cluster head have been proposed. However, the network lifetime of such approaches is highly dependent on the distribution of the sensor nodes, because, in randomly distributed sensor networks, the approaches do not guarantee that the cluster energy consumption will be proportional to the cluster size. To address this problem, we propose a novel approach called CACD (Clustering Algorithm Considering node Distribution), which is not only distance-aware but also node density-aware approach. In CACD, clusters are allowed to have limited member nodes, which are determined by the distance between the sink and the cluster head. Simulation results show that CACD is 20%-50% more energy-efficient than previous work under various operational conditions considering the network lifetime.

• Journal of Sensor Science and Technology
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• v.14 no.2
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• pp.116-124
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• 2005

In this paper range measurement systems are designed using an ultrasonic sensor and a camera. An ultrasonic sensor provides the range measurement to a target quickly and simply but its low resolution is a disadvantage. We tackle this problem by employing a camera. Instead using a stereoscopic sensor, which is widely used for 3D sensing but requires a computationally intensive stereo matching, the range is measured by focusing and structured lighting. In focusing a straightforward focusing measure named as MMDH(min-max difference in histogram) is proposed and compared with existing techniques. In the method of structure lighting, light stripes projected by a beam projector are used. Compared to those using a laser beam projector, the designed system can be constructed easily in a low-budget. The system equation is derived by analysing the sensor geometry. A sensing scenario using the systems designed is in two steps. First, when better accuracy is required, measurements by ultrasonic sensing and focusing of a camera are fused by MLE(maximum likelihood estimation). Second, when the target is in a range of particular interest, a range map of the target scene is obtained by using structured lighting technique. The systems designed showed measurement accuracy up to 0.3[mm] approximately in experiments.

• Journal of Sensor Science and Technology
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• v.15 no.4
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• pp.231-236
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• 2006

Single-mode planar waveguide type UV sensor was fabricated using SU-8 and photochromic dye. Polymer waveguide was fabricated $10{\mu}m$ width and $2{\mu}m$ thickness for single-mode operation. The UV sensor had an absorbance with $0.0396{\sim}0.114$ absorbance/mW respectively when the 5 mm sensing area was irradiated with UV for 3 sec. And sensor had a linear properties by sensing area variation. Proposed single-mode sensor had more excellent properties of UV sensitivity than other UV sensors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.768-774
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• 2007

This paper proposes how to reduce the amount of data transmitted in each sensor and cluster head in order to lengthen the lifetime of sensor network. This study proposes hierarchical filtering for reducing the sensor's energy dissipation. Hierarchical filtering is to divide sensor network by two tiers when filtering it. First tier performs filtering when transmitting the data from cluster member to cluster head, and second tier performs filtering when transmitting the data from cluster head to base station. This should increase the efficiency of filtering and decrease the inaccuracy of the data compared to the methods which enlarge the filter width to do more filtering.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.09a
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• pp.387-389
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• 2010

무선센서네트워크(Wireless Sensor Network) 기술이 전 산업에 널리 사용되면서, 텔레매틱스(Telematics), 지능형교통시스템 등과 무선센서네트워크와의 융합 서비스에 대한 수요가 높아지고 있다. 본 논문에서는 텔레매틱스, 지능형교통시스템 분야에 USN을 적용하기 위한 시스템 아키텍처를 제시한다. 그리고 이를 적용한 안전운전 서비스를 보여준다.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.595-597
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• 2004

In this paper range measurement systems using ultrasonic and visual sensors are designed. By varying the focus of a camera, the range to a target pattern is computed. Pour different methods are tested for the focusing-based range measurement. The best result is obtained when counting edge pixels found by Laplacian operator. Higher accuracy can be obtained by fusing the measurement of camera focusing with that of ultrasonic sensor. The system designed is experimented within the range of 300-450mm.