• Journal of Sensor Science and Technology
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• v.24 no.1
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• pp.6-9
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• 2015

Conventional leak detectors are widely based on helium gas sensors. However, the usage of hydrogen sensors in leak detectors has increased because of the high prices of helium leak detectors and the dearth in the supply of helium gas. In this study, a hydrogen leak detector was developed using solid-state hydrogen sensors. The hydrogen sensors are based on Park-Rapp probes with heterojunctions made by oxygen-ion conducting Yttria-stabilized zirconia and proton-conducting In-doped $CaZrO_3$. The hydrogen sensors were used for determining the potential difference between air and air balanced 5 ppm of $H_2$. Even though the Park-Rapp probe shows an excellent selectivity for hydrogen, the sensitivity of the sensor was low because of the low concentration of hydrogen, and the oxygen on the surface of the sensor. In order to increase the sensitivity of the sensor, the sensors were connected in series by Pt wires to increase the potential difference. The sensors were tested at temperatures ranging from $500-600^{\circ}C$.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5574-5591
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• 2017

Inspired by the idea of Artificial Immune System, many researches of wireless sensor network (WSN) intrusion detection is based on the artificial intelligent system (AIS). However, a large number of generated detectors, black hole, overlap problem of NSA have impeded further used in WSN. In order to improve the anomaly detection performance for WSN, detector generation mechanism need to be improved. Therefore, in this paper, a Differential Evolution Constraint Multi-objective Optimization Problem based Negative Selection Algorithm (DE-CMOP based NSA) is proposed to optimize the distribution and effectiveness of the detector. By combining the constraint handling and multi-objective optimization technique, the algorithm is able to generate the detector set with maximized coverage of non-self space and minimized overlap among detectors. By employing differential evolution, the algorithm can reduce the black hole effectively. The experiment results show that our proposed scheme provides improved NSA algorithm in-terms, the detectors generated by the DE-CMOP based NSA more uniform with less overlap and minimum black hole, thus effectively improves the intrusion detection performance. At the same time, the new algorithm reduces the number of detectors which reduces the complexity of detection phase. Thus, this makes it suitable for intrusion detection in WSN.

• Journal of Welding and Joining
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• v.23 no.4
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• pp.66-72
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• 2005

An electromagnetic inductive sensor consisted of one exciter and three separated (triple) detectors has been developed for both tracking the weld seam of a workpiece and controlling the sensor-to-workpiece distance (height) simultaneously. The left and right detectors are used to track the seam, while the fore and the other two detectors allow the sensor to determine the height and the gap width by being coupled their outputs together. A series of experiments with the proposed sensor located above a mild steel plate containing a weld seam of gap are carried out to examine the feasibility of the sensor. The results revealed that the proposed sensor could fairly well track the desired seam and also well control the height to be constant even when the gap width of the seam varied. The gap width can be also determined during the seam tracking by using the sensor outputs. As a consequence, these can provide the developed sensor with substantial improvement for industrial uses with respect to the previous electromagnetic sensors being used for the weld seam tracking.

• Fire Science and Engineering
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• v.23 no.4
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• pp.98-103
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• 2009

In this paper, in order to analyze the response characteristics of the smoke detectors which is suitable with the residential fire detector, the paper fire and flammable liquid fire experiment came to be accomplished according to UL Standard for safety for smoke detector for fire alarm signaling systems, UL 268. Also Photoelectric smoke detector, the Analog smoke detector and the single station alarm device came to be used with the specimen and the response characteristics of the smoke detectors which follows in these two types(paper, flammable liquid) test fire came to be analyzed. As a result, according to test fire there was some difference to response characteristics of the smoke detectors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7964-7970
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• 2015

In enclosed areas such as railway tunnels, the heat and smoke generated by a fire can pose a tremendous risk to the life of passengers. To prevent or mitigate such scenarios, fire detectors are installed for early fire detection. This numerical study is preformed for establishing the method of detecting performance of fire detectors installed on railway tunnels. Numerical analysis are conducted using the fire dynamics simulator, developed by the NIST. The temperature of the tunnel walls is determined using the assumed exterior structure of the tunnel. In addition, the detection times of detectors installed at different locations in the tunnel are obtained for different sizes of the fire source, and the results are compared and analyzed.

• Fire Science and Engineering
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• v.23 no.3
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• pp.67-72
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• 2009

This paper is for response feature of fire detectors not only to analysis response feature of fire detector, but also to observe flame spread of inside-building and fire enlargement by using the row house which is supposed to be broken up. Many kinds of popular detectors such as heat type detector(differential type, fixed temperature type, Analogue type)and smoke type(light scattered type, Analogue type, single alarm type) were installed in the house in order to check for the change of temperature by installing of thermocouples. As a result, smoke detectors are better than heat detectors when it comes to making effective fire-detect system in the row house.

• Nuclear Engineering and Technology
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• v.35 no.2
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• pp.165-170
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• 2003

We developed an improved 3-PM liquid scintillation counting (3-PM LSC) method in which three detectors can be displaced to back and forth directions, and a data acquisition system being able to provide the values for all parameters required for the method. The detectors are entirely located in a 20-mm lead chamber of an inner diameter of 500 mm. A saw-toothed gear ties up all detectors so as to move them uniformly, up to 50 mm with unit of 1 mm. The data acquisition system was designed in an integrated circuit to perform the necessary works such as fast amplification, discrimination, coincidence and logic analysis. It generates values of nine parameters among twelve's generated in the 3-PH LSC method. The dead time of each counting channel is of extending type, valving from 10 to 100 $mutextrm{s}$. We measured the TDCR values with an unquenched liquid scintillation source 1"C by displacing the detectors with a step of 2.5 mm away from counting vial. Their values were derived on the range from 0.9 to 0.6. The extent is three times wider than those regions observed by applying the defocalization technique.ique.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.5
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• pp.253-263
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• 2021

Traffic data collected using advanced equipment are highly valuable for traffic planning and efficient road operation. However, there is a problem regarding the reliability of the analysis results due to equipment defects, errors in the data aggregation process, and missing data. Unlike other detectors installed for each vehicle lane, radar detectors can yield different error types because they detect all traffic volume in multilane two-way roads via a single installation external to the roadway. For the traffic data of a radar detector to be representative of reliable data, the error factors of the radar detector must be analyzed. This study presents a field survey of variables that may cause errors in traffic volume collection by targeting the points where radar detectors are installed. Video traffic data are used to determine the errors in traffic measured by a radar detector. This study establishes three types of radar detector traffic errors, i.e., artificial, mechanical, and complex errors. Among these types, it is difficult to determine the cause of the errors due to several complex factors. To solve this problem, this study developed a radar detector traffic volume error analysis model using a multiple linear regression model. The results indicate that the characteristics of the detector, road facilities, geometry, and other traffic environment factors affect errors in traffic volume detection.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.4
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• pp.543-558
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• 2023

Currently, Japan is undertaking a nationwide project to measure and map radioactive contamination around Fukushima, as part of the efforts to restore normalcy following the nuclear accident. The Japan Atomic Energy Agency (JAEA) manages the Fukushima Environmental Safety Center, located approximately 20 km north of the Fukushima Daiichi nuclear power plant in Minamisōma City, Fukushima Prefecture. In collaboration with the JAEA, this study involved conducting comparison experiments and analyses with radiation detectors in high radiation environments, a challenging task in Korean environments. Environmental radiation surveys were conducted using three types of detectors: CZT, NaI(Tl), and LaBr₃(Ce), across two contaminated areas. Dose rate values were converted using dose rate conversion factors for each detector type, and dose rate maps were subsequently created and compared. The detectors yielded similar results, demonstrating their feasibility and reliability in high radiation environments. The findings of this study are expected to be a crucial reference for enhancing the verification and supplementation of procedures and methods in future radiation measurements and mobile surveys in high-radiation environments, using these three types of radiation instruments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.2
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• pp.69-80
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• 2002

In this paper, signed-rank based nonparametric detectors are used for direct sequence code division multiple access pseudo-noise code acquisition systems in frequency-selective Rician fading channels. We first derive the locally optimum rank detector, and then propose the locally suboptimum rank (LSR) and k-th order modified signed-rank (MSRk) detectors using approximate score functions. We compare the serial and hybrid parallel double-dwell schemes using the LSR and MSRk detectors with those using the conventional squared-sum (SS) using the cell averaging constant false alarm rate processor and modified sign detectors. From the simulation results, it is shown that the LSR and MSRk detectors perform better than the SS detector using the cell averaging constant false alarm rate processor.