• Journal of Sensor Science and Technology
• /
• v.17 no.3
• /
• pp.168-177
• /
• 2008

An indoor environmental monitoring system using IEEE 802.15.4 based wireless sensor network is proposed to monitor the amount of pollutant entering to the room from outside and also the amount of pollutant that is generated in indoor by the building materials itself or human activities. Small-size, low-power wireless sensor node and low power electrochemical sensor board is designed to measure the condition of indoor environment in buildings such as home, offices, commercial premises and schools. In this paper, two query models, the broadcasting query protocol and flooding query protocol, were designed and programmed as a query-based routing protocol in wireless sensor network for an environment monitoring system. The flooding query routing protocol in environment monitoring is very effective as a power saving routing protocol and reliable data transmission between sensor nodes.

• Journal of Sensor Science and Technology
• /
• v.25 no.6
• /
• pp.423-430
• /
• 2016

This study used a single metal oxide semiconductor (MOS) sensor to classify the major odorous gases hydrogen sulfide ($H_2S$), ammonia ($NH_3$) and toluene ($C_6H_5CH_3$). In order to classify these odorous substances, the voltage on the MOS sensor heater was gradually reduced in 0.5 V steps 5.0 V to examine the changes to the response by the cooling effect on the sensor as the voltage decreased. The hydrogen sulfide gas showed the highest sensitivity compared to odorless air under approximately 2.5 V and the ammonia and toluene gases showed the highest sensitivity under approximately 5.0 V. In other words, the hydrogen sulfide gas reacted better in the low temperature range of the MOS sensor, and the ammonia and toluene gases reacted better in the high-temperature range. In order to analyze the response characteristics of the MOS sensor by temperature in a pattern, a two-dimensional (2D) x-y pattern analysis was introduced to clearly classify the hydrogen sulfide, ammonia, and toluene gases. The hydrogen sulfide gas was identified by a straight line with a slope of 1.73, whereas the ammonia gas had a slope of 0.05 and the toluene gas had a slope of 0.52. Therefore, the 2D x-y pattern analysis is suggested as a new way to classify these odorous substances.

• Structural Monitoring and Maintenance
• /
• v.1 no.2
• /
• pp.183-195
• /
• 2014

Scour is one of the leading causes of overwater bridge failures worldwide. While monitoring systems have already been implemented or are still being developed, they suffer from limitations such as high costs, inaccuracies, and low reliability, among others. Also, most sensors only measure scour depth at one location and near the pier. Thus, the objective is to design a simple, low cost, scour hole topography monitoring system that could better characterize the entire depth, shape, and size of bridge scour holes. The design is based on burying a robust, waterproofed, piezoelectric sensor strip in the streambed. When scour erodes sediments to expose the sensor, flowing water excites it to cause the generation of time-varying voltage signals. An algorithm then takes the time-domain data and maps it to the frequency-domain for identifying the sensor's resonant frequency, which is used for calculating the exposed sensor length or scour depth. Here, three different sets of tests were conducted to validate this new technique. First, a single sensor was tested in ambient air, and its exposed length was varied. Upon verifying the sensing concept, a waterproofed prototype was buried in soil and tested in a tank filled with water. Sensor performance was characterized as soil was manually eroded away, which simulated various scour depths. The results confirmed that sensor resonant frequencies decreased with increasing scour depths. Finally, a network of 11 sensors was configured to form a distributed monitoring system in the lab. Their exposed lengths were adjusted to simulate scour hole formation and evolution. Results showed promise that the proposed sensing system could be scaled up and used for bridge scour topography monitoring.

• Smart Structures and Systems
• /
• v.12 no.1
• /
• pp.73-95
• /
• 2013

Nine deoxyribonucleic acid (DNA) sequences were used to functionalize single-walled carbon nanotube (SWNT) sensors to detect the trace amount of methanol, acetone, and HCl in vapor. DNA 24 Ma (24 randomly arranged nitrogenous bases with one amine at each end of it) decorated SWNT sensor and DNA 24 A (only adenine (A) base with a length of 24) decorated SWNT sensor have demonstrated the largest sensing responses towards acetone and HCl, respectively. On the other hand, for the DNA GT decorated SWNT sensors with different sequence lengths, the optimum DNA sequence length for acetone and HCl sensing is 32 and 8, separately. The detection of methanol, acetone, and HCl have identified that DNA functionalized SWNT sensors exhibit great selectivity, sensitivity, and repeatability with an accuracy of more than 90%. Further, a sensor array composed of SWNT functionalized with various DNA sequences was utilized to identify acetone and HCl through pattern recognition. The sensor array is a combination of four different DNA functionalized SWNT sensors and two bare SWNT sensors (work as reference). This wireless sensing system has enabled real-time gas monitoring and air quality assurance for safety and security.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.16 no.1
• /
• pp.81-88
• /
• 2013

This paper describes the fundamentals, design, realization and test results of a BPSK(Bi Phase Shift Keying) transceiver for the direction finding proximity fuze sensor for anti-aircrafts or air missiles. The BPSK transceiver for the direction finding fuze sensor has been designed to detect a moving target by Doppler signal processing with the code correlation method and to distinguish direction by comparing received powers of each Doppler signal from adjacent three receiving antennas. The electrical and ESS(Environmental Stress Screening) tests of the BPSK transceiver showed satisfactory results and target detection and direction finding performances proved to be successful through dynamic operation tests by 155 mm gun firing.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.46 no.4
• /
• pp.28-38
• /
• 2009

In this study, a remote air quality monitoring system for underground spaces was developed by using NDIR-based CO$_2$ sensor. And the remote monitoring system based on wireless sensor networks was installed practically on the subway station platform. More than 6.5 million citizens commutate everyday by the Seoul subway transportation that is the most typical public transportation. They concern about air quality with increasing interest on public health or many workers in subway stations or underground shopping centers. Recently, the Korean Ministry of Environment has operated the air quality monitoring system in some subway stations for testing phase. However, it showed many defects which are large-scale, high-cost and maintenance of precision sensors imported from abroad. Therefore this research includes the reliability test and a theoretical study about the inexpensive commercialized CO$_2$ sensor for reliable measurement of air quality which changes rapidly by the surrounding environments. And then we develop the wireless sensor nodes and the gateway applied for remote air quality monitoring. In addition, web server program was realized to manage air quality in the subway platform. This result will be valuable for a basic research for air quality management in underground spaces for future study.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.31 no.3
• /
• pp.160-164
• /
• 2018

We have proposed a hydrogen detection sensor based on a Pd (palladium)-coated, single-mode, optical fiber. The experimental results demonstrated that the sensor could detect hydrogen in air as well as in insulation oil. The influence of Pd film thickness and environmental temperature on response time and sensitivity was analyzed. The reflected optical power at the optical-fiber/Pd interface decreased as the concentration of hydrogen increased, in both air and the insulation oil. The sensor showed 0.75 dB of optical power variation when the concentration of dissolved hydrogen was saturated in the insulation oil.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.807-810
• /
• 2011

The sensor network technology for core technology of ubiquitous computing is in the spotlight recently, the research on sensor network is proceeding actively which is composed many different sensor node. USN(Ubiquitous Sensor Network) is the network that widely applies for life of human being. It works out to sense, storage, process, deliver every kind of appliances and environmental information from the stucktags and sensors. And it is possible to utilize to measure and monitor about the place of environmental pollution which is difficult for human to install. It's studied constantly since it be able to compose easily more subminiature, low-power, low-cost than previous one. And also it spotlights an important field of study, graft the green IT and IT of which the environment and IT unite stragically onto the Network. The problem for the air pollution in the office or the indoor except a specific working area is the continuously issue since the human beings have lived in the dwelling facilities. Measures for that problem are urgently needed. It's possible to solve for the freshair of outside with enough ventilation but that is the awkward situation to be managed by person. This study is the system engineering to management for indoor air condition under the sensor network. And research for efficiently manage an option.

• Proceedings of the Korean Environmental Health Society Conference
• /
• 2004.06a
• /
• pp.139-141
• /
• 2004

Emission of volatile organic compounds (VOCs) are one of the popular issues of air pollution in Korea, especially in Ulsan city, where much chemical plants are located. It is necessary to detect the VOCs precisely in order to control the air pollution during the plant operation. In general, to examine the concentration of VOCs, gas chromatography (GC) is used. However, most plant operators are using the easy operating handy VOCs detector, which is imported, because GC is difficult to treat and the installation price is high although it is very useful equipment. Therefore, the development of the VOCs detector becomes one of the urgent issues. In this study, sensing characteristics of selected VOCs for the development of VOCs detector was investigated. Semiconductor sensor and several VOCs such as aliphatic, aromatic, and non-homogeneous hydrocarbons were used for the experiment. Through the various experiments, sensor used in the experiment has shown high linearity and sensitivity for most VOCs in the range of 1 -500 ppm concentration.

• Journal of Sensor Science and Technology
• /
• v.23 no.4
• /
• pp.266-271
• /
• 2014

Chemical sensors are used in various industrial facilities such high-risk and prevent the leakage of substances, important in life and environmental protection and the safe use of industry, used for management. In particular, high-temperature environments such as power generation equipment of the rotating part due to leakage generated by the various oil, power plants Shut Down, fire, work environment (exposure to various chemical solution and gas leak) and various water, air and soil pollution causes. Thus, over the long term through various channels such as crops and groundwater contamination caused by the slow, serious adverse effect on the ecosystem. In this paper, synthetic lube oil and high pressure hydraulic fluid leakage and immediately detect a new Printed Electronic implementation of technology-based film-type sensors, and its performance test. Thus, industrial accidents and environmental pollution and for early detection of problems, large accidents can be prevented. Experimental results of the synthetic lube oil and high pressure hydraulic fluid solution after the contact time depending on the experiment and the oil solution of the sensor material of the conductive porous PE resistance value by a chemical reaction could be confirmed that rapid increase. Also implemented in the film-type oil sensor electrical resistance change over time of the reaction rate and the synthetic lube oil is about 2 minutes or less, the high pressure hydraulic fluid is less than about 1 minute was. Therefore, more high-pressure hydraulic fluid such as a low volatility synthetic lube oils are the resistance change and the reaction rate was confirmed to be the slowest.