• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.2099-2106
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• 2003

In this paper, a novel fast response NDIR analyzer (FRNDIR), which uses an electrically pulsed semiconductor emitter and dual type PbSe detector for the PPM-level detection of carbon dioxide (CO$_2$) at a wavelength of 4.28 $\mu\textrm{m}$, is described. Modulation of conventional NDIR energy typically occurs at 1 to 20 Hz. To achieve real time high-speed measurement, the new analyzer employs a semiconductor light emitter that can be modulated by electrical chopping. Updated measurements are obtained every one millisecond. The detector has two independent lead selenide (PbSe) with IR band pass filters. Both the emitter accuracy and the detector sensitivity are increased by thermoelectric cooling of up to -20 degrees C in all semiconductor devices. Here we report the use of semiconductor devices to achieve improved performance such that these devices have potential application to CO$_2$ gas measurement and, in particular, the measurement of fast response CO$_2$ concentration at millisecond level.

• Fire Science and Engineering
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• v.22 no.4
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• pp.50-53
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• 2008

This study has been conducted for the purpose of considering the problems expected when checking the smoke detector at site and how to improve the smoke detector. We have conducted this study focused on checking the problems expected upon site inspection and finding out the way of improving the site inspection by analyzing the reliability and performance of instrument used upon site inspection. The test results show that some problems exist in the reliability and performance of instrument used for the site inspection of smoke detector way of inspecting the inspection instrument.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.83-91
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• 2012

An RF energy detector for spectrum sensing in TV white space transceiver is presented. It is based on an RF active filtering technique that comprises a low-noise amplifier with a frequency-translation high-pass filtering feedfoward loop, which attenuates the unwanted sideband energy and only passes the wanted band energy. Unlike the conventional architecture, a new architecture that can attenuate both sidebands at the same time is proposed. A simplified system modeling method is presented to assess the non-ideality effects on the RF energy detector performances. System behavioral simulations demonstrate that the proposed architecture can be instrumental for realizaing a RF energy detector circuit in CMOS.

• Journal of Sensor Science and Technology
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• v.17 no.1
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• pp.75-80
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• 2008

In this work, we optimized a microbolometer for application of a $CO_2$ detector by using MEMS technology. We fabricated a stable thermal isolation structure by varying the lengths of supporting legs which affect bolometer performance. We could fabricate more stable thermal isolation structure for the microbolometer through the results of ANSYS simulations, and minimize the fabrication processes by using bulk micromachining to use a $CO_2$ detector. The microbolometer shows a detectivity of $2.5{\times}109$ cmHz$^{1/2}$/W at a chopper frequency of 8 Hz and a bias current of $6.25\;{\mu}A$ with a vacuum package of about $3.0{\times}10.3$ torr. Therefore, we put to conclusion that the microbolometer optimized in this experiment could be useful for the application of a $CO_2$ detector.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.773-782
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• 2018

A frequency-locked loop(FLL) is a negative-feedback system that uses a frequency detector to improve the phase noise of a voltage-controlled oscillator(VCO). In this work, a theoretical analysis of the phase noise of a VCO in an FLL is presented. The analysis shows that the phase noise of the VCO follows the phase noise determined by the frequency detector and the loop filter within the FLL loop bandwidth, while the phase noise of the VCO appears outside the loop bandwidth. Therefore, it is possible to design an FLL that minimizes the phase noise of the VCO based on the theoretical analysis results. The theoretical phase noise results were verified through experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.696-699
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• 2001

In these days, there are explosive growths of Internet users. But the damages of hacking are on the increase lately too. Currently, many researches for detection of hacking are studying, and there are many Hacking detection tools. In this thesis, We designed and implemented Sniffing detection and Management Tool, Which ran search an invasion by sniffing in Local LAN environment. The Implementation of Sniffing Detector and Management Tool are composed of two modules. In other words, They are Sniffing Detector Tool and Sniffing Management Tool. The Sniffing Detector Tool discovers implementation of the Sniffing from optional host to Sniffing Detector host. And The Sniffing Management Tool displays information of Sniffer on Web_Browser.

• Journal of Communications and Networks
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• v.16 no.6
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• pp.639-644
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• 2014

In low-density parity-check (LDPC) coded multiple-input multiple-output (MIMO) communication systems, probabilistic information are exchanged between an LDPC decoder and a MIMO detector. TheMIMO detector has to calculate probabilistic values for each bit which can be very complex. In [1], the authors presented a class of linear block codes named low-density MIMO codes (LDMC) which can reduce the complexity of MIMO detector. However, this code only supports the outer-iterations between the MIMO detector and decoder, but does not support the inner-iterations inside the LDPC decoder. In this paper, a new approach to construct LDMC codes is introduced. The new LDMC codes can be encoded efficiently at the transmitter side and support both of the inner-iterations and outer-iterations at the receiver side. Furthermore they can achieve the design rates and perform very well over MIMO channels.

• The Korean Journal of Applied Statistics
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• v.20 no.1
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• pp.147-157
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• 2007

Edge detection has been widely used in computer vision and image processing. We describe a new edge detector based on the robust rank-order test which is a useful alternative to Wilcoxon test. Our method is based on detecting pixel intensity changes between two neighborhoods with a $r{\times}r$ window using an edge-height model to perform effectively on noisy images. Some experiments of our robust rank-order detector with several existing edge detectors are carried out on both synthetic images and real images with and without noise.

• Fire Science and Engineering
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• v.28 no.6
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• pp.58-61
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• 2014

Flame detectors has been used more than heat & smoke detector, because this is more effective to catch fire and ceiling height in spite of high price. For upgrade to flame detector, Compare to national or abroad standard about performance test, sensitivity test, sectioning indoor or outdoor, after service and management. As a result, Europe and America have only sensitivity test, no have not operation test and sectioning indoor & outdoor. In performance test, action is put to focus to credit and durability, Not operation test is to be able to tune the sensitivity to match the environment of the site. Also, we need code about aftercare, quality assurance responsibility and implement special detector institution by Certificate Authority implement.

• Journal of Animal Environmental Science
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• v.20 no.4
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• pp.177-182
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• 2014

This research was conducted to grasp the present condition of environmental management relating to Korea detector dogs that performed their duties such as detection and lifesaving. We directly conducted a survey throughout visit to five government agencies. In environmental management case, average length and width of kennels were 1.78 m and 3.50 m, respectively. Types of floor were searched as coating cement, tile, ucrete and concrete. Most of government agencies ventilated kennels using ventilation fan systems with natural ventilation. But there were differences between government agencies in frequencies of the sanitary management items. On the other side, major diseases of the German shepherd breed as a major detector dog were in order of arthritis, measles, earache, and dermatosis. And their daily training time was average 4 hours. Finally, it is thought that these results could be used as a basic data of standard breeding management manual of Korea detector dog.