• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.473-477
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• 2008

In this paper, we introduce the positioning methods using the grid sensor network. The basic operational principle of grid sensor network can be the wireless communication using the sensor node attached on the objects. Sink node receives the environmental information (e.g., temperature, humidity and so on), and transmits the information to the core database. Since the grid sensor network basically uses wireless communication, it is necessary to observe the place where grid sensor nodes to be installed. In this sense, we carried out the practical measurement on the wireless propagation in an applicable field. In addition, link budget study and SNR estimation works were done in accordance with the results from the measurement.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.559-562
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• 2008

In this paper we propose a lock-in detection method for portable sensor systems and demonstrate with the portable detection module that has high sensitivity and robustness against the noise. The simple portable sensor module is manufactured using MCU(Micro Contorl Unit), OPAMP, MOSFET and a pair of infrared sensor. Manufactured sensor module is testified in the noisy environment caused by an external light and an white noise source. Without any type of band pass filters, we recover a signal of 33 $mV_{p-p}$ in 80 $mV_{p-p}$ white noise and get the DR(Dynamic Reserve) of 14 dB.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.53.2-53
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• 2001

The Non-Contact Optical Sensor using the Hologram Laser for CD Pickup was developed to measure a shape of transparent objects and shown a good performance. Therefore the problems caused by the contact sensor are solved by using the Non-Contact Sensor. The Non-Contact Sensor has to move toward the objects and obtain the Focus Error Signal to measure a position of transparent objects. However, if the distance between the sensor and the object is shorter than the working distance of the objective lens, the sensor will be collided against the objects. In this paper we proposed a new algorithm to estimate the start position of the Focus Error Signal to solve the problems of collision between the sensor and the objects. In addition, we verified that the algorithm is free from the collision in the real time measurement.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1302-1308
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• 2010

In this study, Zigbee Sensor Node to transmit harmful gases CO and $CO_2$ information using wireless communication within the ground and underground structures were developed. Wireless communication protocol was used Zigbee Stack included IEEE 802. 15.4 MAC protocol. For wireless transmission of detected harmful gas signal from ADC of MCU was implemented Zigbee Sensor Node that was developed protocol using Serial-Port-Profile(SPP) here. The proposed Zigbee Sensor Node was verified transmission distance from experiments. Transmission distance was into 90m in experiments. Distance experiments were measured at 10m intervals using sine & pulse wave input signal at indoors. The proposed Route Sensor Node was applied mesh routing protocol. When built up USN(Ubiquitous Sensor Network)using Route Sensor Node, transmission distance was not limited. On the experimental results, harmful gas values between direct measurements and USN measurements were consistent. The semiconductor CO sensor and N-DIR $CO_2$ sensor module as a harmful sensor was used. Therefore, the proposed Zigbee Sensor Node was verified about reliability and validity to build USN for transmission of harmful gas information.

• Journal of information and communication convergence engineering
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• v.8 no.2
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• pp.228-233
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• 2010

In this paper, the iteration localization algorithm that NLOS signal is iteratively removed to get the exact location in the wireless sensor network is proposed. To evaluate the performance of the proposed algorithm, TDOA location estimation method is used, and readers are located on every 150m intervals with rectangular shape in $300m{\times}300m$ searching field. In that searching field, the error distance is analyzed according to increasing the number of iteration, sub-blink and the estimated sensor node locations which are located in the iteration range. From simulation results, the error distance is diminished according to increasing the number of the sub-blink and iteration with the proposed location estimation algorithm in NLOS environment. Therefore, to get more accurate location information in wireless sensor network in NLOS environments, the proposed location estimation algorithm removing NLOS signal effects through iteration scheme is suitable.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.3
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• pp.144-148
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• 2001

For the purpose of developing capacitive humidity sensor having interdigit electrodes, interdigit electrode was modeled and simulated to obtain capacitance and sensitivity as a function of geometric parameters like the structural gap and thichness. For the development of ASIC, switched capacitor signal conditioning circuits for capacitive humidity sensor were designed and simulated by cadence using 0.25um CMOS process parameters. The signal conditioning circuits are composed of amplifier for voltage gain control, and clock generator for sensor driving and switch control The characteristics of the fabricated sensors are; 1) sensitivity is 9fF/%R.H., 2) temperature coefficient of offset(TCO) is 0.4%R.H./$^{\circ}C$, 3) nonlinearity is 1.2%FS, 4) hysteresis is 1.5%FS in humidity range of 3%R.H. ${\sim}$ 98%R.H.. The response time is 50 seconds in adsorption and 70 seconds in desorption. Fabricated process used in this capacitive humidity sensor having interdigit electrode are just as similar as conventional IC process technology. Therefore this can be easily mass produced with low cost, simple circuit and utilized in many applications for both industrial and environmental measurement and control system, such as monitoring system of environment, automobile, displayer, IC process room, and laboratory etc..

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.1
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• pp.384-398
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• 1996

An improved multi-channel Impedance Void Meter (IVM) is developed to measure an area-averaged void fraction. It consists of a main sensor, a reference sensor and a signal processor. The sensor was designed to be flush-mounted to the inner wall of the test section to avoid the flow disturbances. Guard electrodes are used to obtain evenly distributed electrical field in a measuring volume. A reference sensor is also installed to eliminate the drift in void signal caused by the changes in electrical properties of working fluid. The signal processor with three channels is specially designed so as to minimize the inherent error due to the phase difference between channels. As an example of applications, the mean and fluctuating components of void fraction are measured for bubbly and slug flow regime, and it is shown that IVM has good dynamic resolution which is required to investigate the structural developments of bubbly flow and the propagation of void waves in a flow channel.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.1056-1060
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• 2012

Online monitoring system is becoming an essential element of railway traction system for utilized to condition based malignance management and various techniques currently employed in railway traction system. Among the various techniques, it is efficient to detect partial discharge signals by electromagnetic wave detection in order to detect insulation fault of rectifier. Although VHF (Very High Frequency), UHF (Ultra High Frequency) sensors were adopted to detect partial discharge of power facilities, due to characteristics of urban railway, excessive noise occurs from 500 MHz to 1.5 GHz on UHF bandwidth. In this paper a new measurement system able to monitoring the conditions of power facilities on DC substation in metro was studied and set up. The system uses UHF sensors to measure the partial discharge of the rectifier due to electric faulting and dielectric breakdown. Comparison and estimation for performance of SHF sensor which had devised to detect partial discharge signal of urban railway rectifier has conducted. In order to estimate performance of SHF sensor, we have compared the sensor with existing UHF sensor on sensitivity upon frequency bandwidth generated by pulse generator, and also we have verified performance of the SHF sensor by detection results of partial discharge signal from urban railway rectifier.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.4
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• pp.285-290
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• 2007

A wavelength-demodulation algorithm for FBG sensor is proposed by using a double-pass Mach-Zehnder interferometer. Zero-crossing points of double-passed interference signal are used to trigger the accurate $90^{\circ}C$ phase difference positions in the sensor signal, which is an essential condition in the subsequent arctangent and phase unwrapping signal processing. With the proposed method, we could efficiently measure various measurands, such as dynamic-, static-strain, and temperature, and ${\sim}8pm$ of wavelength resolution was obtained.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9B
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• pp.811-820
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• 2006

In this paper, The correlation of the power consumption of sensor node is analyzed according to the analyze parameter in IEEE 802.15.4 star sensor network. And It is studied the influence on analysis parameter. The power consumption of sensor network in transmission process and average transmission power consumption drives to numerical formula. And CSEM WiseNET system measurement value is used. As a simulation result, The power consumption of sensor node in star network consist of 10 sensor nodes is more than 20 % that in single network in average. When beacon signal interval is 0.1 second in all frequency bands, the power consumption of sensor node in up-link is more than 2.5 times that in down-link in average. When beacon signal interval is 1 second and the number of sensor nodes increases to 100 and sensing data increases to 100 byte, the power consumption of sensor node increases to 2.3 times. And The superior performance of 2.4 GHz frequency band has than 868/915 MHz frequency band up to $6{\sim}12$ times.