• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.10-14
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• 2005

This report deals with a feeding system of the Coaxal grinding machine, processing optical ferrule. This report also examines the applicability of using the feeding system for the Coaxial grinding machine, by mean of conducting performance estimation. The results are as follow; Repeatability of regulating wheel is $17{\mu}m$, R/W rotation accuracy is between $30\;\~\;40{\mu}m$. This means 'Rotation accuracy' is lower than the concentricity level. Backlash generation level at the feeding system of the grinding wheel is under $1{\mu}m$, thereby positioning accuracy is controlled within $2{\mu}m$ In terms of repeatability, you can find occasional error at the returning process from the starting point. This error is resulted from the measurement tolerance of the starting point sensor. We will get the repeatability level under control by $1{\mu}m$, through improving the soft-ware used and up-grading the sensor at the starting point.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.9
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• pp.861-868
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• 2016

Dummy messages are usually generated for faking in preserving the location privacy of a sink or source against the global eavesdropping in wireless networks. In this paper, we propose a new method in which a certain number of nodes determined by considering the required privacy level are made to transit to the dormant state doing nothing so that the total number of dummy messages is reduced, while the paths from the sink to the sources are ensured. Through simulation we verify the success ratio of path establishments between the sink and a set of sources and the location privacy level of them.

• Spatial Information Research
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• v.23 no.3
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• pp.1-10
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• 2015

Due to recent improvement of various sensor technologies, indoor positioning becomes available. However, Indoor positioning technologies by Wi-Fi radio map and acceleration sensor and digital campus still have a certain level of errors and a number of researches have been done to increase the positioning accuracy of the indoor positioning. If we could provide a room level accuracy, indoor location based services with current indoor positioning methods such as Wi-Fi radio map and acceleration sensors would be possible. In this paper, we propose an indoor map matching method to provide a room level accuracy based on hidden markov model.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.4
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• pp.385-391
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• 2014

A control system for ultrasonic spray pyrolysis deposition was developed that can coat a large size glass panel with a transparent conductive oxide. It consists of several ultrasonic atomizer devices to cover a large area and a host computer for individually controlling the devices. The sub-controller in an ultrasonic atomizer device can adjust the flow rate of the atomized conductive oxide gas by setting the flow rate of the solution and regulating the level of the solution in the tank. To construct a feedback control loop for level regulation, a level sensor that utilized an infrared distance sensor and an electric circuit for adjusting the ultrasonic oscillator were developed. The host program was also developed, which can monitor and control the sub-controllers. A proportional-integral controller was developed for a simplified model, and its operation was verified through an experiment.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.439-441
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• 2007

The seoul metropolitan subway has installed 8 lines and about 500 stations to transport 5 million passengers everyday. The underground air pollution level in the subway stations is very severe status, which is very harmful to the commutators and its personals. Although subway roles as such a massive and huge transportation system, the subway doesn't adapt yet any real-time air monitoring system. They have only some hand-held type detector equipments for monitoring air pollution. Therefore subway passengers are exposed to the harmful air pollution environment. The most harmful environmental parameters among the air pollution are known as the dust and sound noise dB level in the subway station. Because the dust is consisted of very small particles, we can't see them easily in dark condition on the platform, but it is very harmful. The monitoring system for air pollution is developed using embedded system attached with 6 different environmental sensors. This system monitors air pollution of dust sound noise, gas, temperature, humidity, inflammable gas, toxic gas in the subway ?station. The sensor unit of the ARM-CPU board and sensor transmits real time environmental data to the main server using Zigbee wireless communication module and TCP/IP network. The main control server receives and displays the real-time environmental data, and it send alarms to the personals when high level value.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.933-934
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• 2006

High level perceptual tasks such as context understanding, SLAM and object recognition are essential for intelligent robot to provide services for human supports. Those intelligent robots often use camera sensor for vision information, sonar or laser sensor for range information, encoder for angular velocity of wheel and so on. The information is generated at different time intervals by the different H/W devices and S/W algorithms. The generation of high level information requires the specific mixture of low level information. And the information should be represented to be useful for robots to use in their ecological niche. In conventional robot systems, perceptual module requires the resource to use by tightly coupling whenever it is needed. So the resource and information cannot be easily shared and even could be invalid for the delayed information. In this paper, we propose a synchronization system of robot-centered information for context understanding. Our system represents information for the robot capacity and synchronizes the information that is asynchronously generated, where is employed the black-board architecture.

• International Journal of Computer Science & Network Security
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• v.21 no.1
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• pp.6-11
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• 2021

Routing protocols play a pivotal role in the energy management and lifespan of any Wireless Sensor Network. Lower network lifetime has been one of the biggest concerns in LEACH protocol due to dead nodes. The LEACH protocol suffers from uneven energy distribution problem due to random selection of a cluster head. The cluster head has much greater responsibility compared to other non- cluster head nodes and consumes greater energy for its roles. This results in early dead nodes due to energy lost for the role of cluster- head. This study proposes an approach to balance the energy consumption of the LEACH protocol by using a semi-deterministic opportunity coefficient to select the cluster head. This is calculated in each node with the battery energy level and node ID. Ultimately, based on the opportunity cost, cluster head will be selected and broadcasted for which other nodes with higher opportunity cost will agree. It minimizes the chances of nodes with lower battery level being elected as cluster head. Our simulation experiments demonstrate that cluster heads chosen using our proposed algorithm perform better than those using the legacy LEACH protocol.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.83-90
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• 2020

A commercial flow measurement radar sensor estimates a quantity of flowed water using surface flow rate. In this way, the amount of water flowing per unit time cannot be measured accurately because of using an estimation result and it can't response environmental changes. For more accurate flow measurements we need width of waterway, water level and distance that water moved per unit time. Commonly two sensors are used to measure water level and flow rate. In this paper, we propose a method to simultaneously measure the water level and surface flow velocity using a single FMCW radar sensor and design the transmission waveform. In order to verify the waveform design, received signal is modelled based on transmission waveform. In addition, we consider phenomenons and problems that may occur in signal processing.

• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.192-206
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• 2008

Multihop is the main communication style for wireless sensor networks composed of tiny sensor nodes. Until now, most applications have treated the periodic small sized sensing data. Recently, the burst traffic with the transient and continuous nature is increasingly introduced due to the advent of wireless multimedia sensor networks. Therefore, the efficient communication protocol to support this trend is required. In this paper, we propose a novel PIGAB(Packet Interval Gap based on Adaptive Backoff) protocol to efficiently transmit the burst data in multihop wireless sensor networks. The contention-based PIGAB protocol consists of the PIG(Packet Interval Gap) control algorithm in the source node and the MF(MAC-level Forwarding) algorithm in the relay node. The PIGAB is on basis of the newly proposed AB(Adaptive Backoff), CAB(Collision Avoidance Backoff), and UB(Uniform Backoff). These innovative algorithms and schemes can achieve the performance of network by adjusting the gap of every packet interval, recognizing the packet transmission of the hidden node. Through the simulations and experiments, we identify that the proposed PIGAB protocol considerably has the stable throughput and low latency in transmitting the burst data in multihop wireless sensor networks.

• Journal of the Korea Society of Computer and Information
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• v.15 no.10
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• pp.147-156
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• 2010

There are some of the studies on sensor middleware. However the standard middleware has not yet been defined. Especially, this paper focuses on the processing an intelligent service of the main functions of middleware. Several applications in the sensor network environment support not only monitoring services, but also sensor-based context-awareness and intelligent services based on sensors. However, the previous studies about USN middleware only mentioned the need for intelligent service and did not discuss the architecture and method for supporting the intelligent service in detail. Therefore this paper designs a USN middleware for providing intelligent services and proposes the method for processing the services. For this purpose, this paper proposes the Sensor-Service ontology to define the concept of services and sensors for USN applications and the relationship between them. The Sensor-Service ontology is used to infer high-level information from low-level information. To apply a variety of environmental context to intelligent services, the paper uses the rule-based reasoning. This paper implements the proposed intelligent service middleware as a prototype and then shows that the middleware can be used for a variety of USN applications through the performance evaluation.