• Journal of Advanced Navigation Technology
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• v.13 no.4
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• pp.503-508
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• 2009

In this paper, we have designed the auxiliary input device which based on hand-motion recognition. It is aimed at some individually specified person such as the disabled, rehabilitation patient, and the aged. The gyro sensor is used to recognize the hand-motion in 3D space, and communication bandwidth for transceiver is also set to the 2.4GHz. Prototype board includes a set of modules; Gyro sensor, RF transmitter/receiver, MCU for signal processing and USB connector etc. Some experiments are conducted so as to verify the prototype, and as a result, mouse-based curser motion as well as program control are well operated just same as the design specification.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.271-274
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• 1998

Ultrasonic sensors are becoming indispensable components in every sector of automation equipments due to many advantages. But the main purposes of the noncontact sensing device are rather narrowly confined within object detection and distance measurement. To widen the realm of the applications to object recognition, ultrasonic sensors need to improve the recognition resolution to a certain amount. To resolve the problem of spatial resolution restriction, an increased number of the sensors in the forms of a linear array or 2-dimensional array of the sensor has been used. Also better resolution has been obtained by shifting the array in several steps using mechanical actuators. For an object recognition using ultrasonic sensors, measurements of distance, shift, oblique angle in certain ranges should be obtained. But a little attention has been paid to the measurement of angles. In this paper we propose a practical method for an object angular value detection in addition to distance measurement in ultrasonic sensor array system with little additional hardware burden. Using the established measurement look-up table for the variations of distance, shift, angle and transmitter voltages for each sensor characteristics, a set of different return echo signals for adjacent receivers are processed to provide enhanced angular value reading for an object.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.57-66
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• 2001

In order to measure steel corrosion in mortar by a transient electro-magnetic (TEM) Method, the development of the sensors have been studied. The sensors were made of enamelled wire with diameter of 0.25mm and Acril. The sensor configuration was used as a coincident loop type. The secondary electro motive force(EMF) was measured with SIROTEM III. The accelerator was equipped with the SIROTEM III. The accelerator permits the transmitter to turn off approximately 10~15 times faster than normal. The high resolution time series used for very shallow or high resistivity investigation was selected. The steels were embedded in mortar which were made from sand : cement : water ratio of 2 : 1: 0.5. The mortar specimen was 50cm long, 20cm wide and 10cm thick. To investigate steel corrosion in mortar, the sensors used were with 2$\times$2$cm^2$(3, 6, 9$\Omega$), 3$\times$3$cm^2$(3, 6, 9$\Omega$) and 6$\times$6$cm^2$(3, 6, 9$\Omega$). The obtained result obtained showed that the sensor 8(6$\times$6$cm^2$, 6$\Omega$) was the proper sensor for the measurement of steel corrosion in mortar.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.592-595
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• 2013

Advent of Wireless Sensor Networks (WSN) has provided potentials to a variety of construction applications. It is well appreciated that WSNs have advantages over traditional wired system, such as ease of installation and maintenance with increased cost savings and efficiencies. However, the obstruction of wireless signal from physical objects in the heterogeneous construction environment often brings challenges to WSN measurement system. This paper analyzed the obstruction characteristic of construction environment where construction materials, equipment, and built structures obstruct the wireless signal yielding negative effect of measurement system. By adopting evaluation criteria, such as packet reception rate, field experiments have been implemented to quantitatively identify the interference of wireless signal from penetration, reflection, and network traffic under the construction environment. The results show that reliable performance of wireless sensor in construction environment depends on the optimal separation distance between a receiver and a transmitter, obstruction types, obstruction thickness, and transmission interval. In addition, the methodology and experimental results of this paper could be used in the practical design of network topology when hundreds of sensor nodes form a mesh network in the large scale construction applications.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.1
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• pp.8-13
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• 2022

This paper investigates the method to implement a RF (Radio Frequency) energy harvesting sensor node and to build a sensor network using a CATV network and a leaky coaxial cable. The power supply of a sensor node is designed with the WPTS (Wireless Power Transfer System) receiver operating at 915MHz. A sensor network has limited coverage by the loss of RF signal at a wireless transmission link. The paper proposes to build a sensor network that the BLE signal of a sensor and the signal of a WPTS power transmitter are transmitted through a coaxial cable of a CATV network by utilizing WOC (WiFi over Coax) technology and radiates at a leaky coaxial cable. The length of a leaky coaxial cable and the total loss of a wire link are allowed to the point that the RSSI of a sensor node is more than the minimum value (-78dBm) and lead to extend wireless coverage.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.411-414
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• 2004

This paper introduces a modulation method for digital wireless communication based on general DS-QPSK. The design and fabrication is for home networking application to a typical RF transmitter with DS-QPSK modulator. This modulator implemented using VHDL hardware programming language, the fabrication of IC chip $5{\times}5 mm^2$ was carried by 27th IDEC MPW(Multi Project Wafer) process in 0.35${\mu}m$ rule at Samsung Inc. This paper presented the important of this technology for the future application in wireless sensor. This module can be efficient usage for home network to transmit the RF wireless sensor system.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.286-288
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• 2003

Accidents at level crossing where railways and roads cross cause many casualties because of collision of cars etc and it also has a risk of the 2nd accident of trains. it is the most vulnerable point in the railway safety. Fundamental solution for accidents at level crossing is making the crossings cubic. but it can't be easily progressed because of environmental and financial difficulties. every kind of anti-accident measures are being strived for. one of the strived results is level crossing obstacle detector which automatically detects obstacles like defected cars etc in the middle of level crossing and transmits the information of obstacles to the approaching train. However present level crossing obstacle auto detector needs high expenses to be installed and has difficulties that lenses of beam transmitter, beam receiver should be cleaned in snowing winter. this document reviews level crossing obstacle auto detector using ultrasonic sensor to measure these difficulties.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1782-1783
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• 2011

실내공간상에서 3차원 실시간 위치를 결정하는 다양한 측지기법들이 존재하지만 $100{\mu}m$ 이하 계측기 수준의 정밀도를 측정하는 방법은 여전히 Laser Theodolite 신호를 사용할 수밖에 없다. Rotary-Laser Automatic Theodolite(R-LAT)는 Fan Laser Beam을 주사하면서 회전시킨 후 주어진 공간의 수직과 수평을 계측하는 Laser Transmitter의 한 종류이다. 본 논문에서는 R-LAT에서 발생되는 Fan Laser Beam 신호를 취득할 수 있는 센서와 증폭회로의 개발을 통하여 3차원 공간좌표에 대한 회전변환행렬로 이루어진 알고리즘을 제안하고 실험을 통하여 기존 Laser Tracker에서 구해지는 공간좌표와 상호 비교하였다.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1929-1932
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• 2002

In this paper, some parameters are studied for the performance improvement of a bulk optical current sensor. The performance of optical current sensor is influenced by current measuring range, Verdet constant change due to temperature change, temperature variation of wave plate, signal to noise ratio of optical transmitter/receiver, optical bias mismatch. Two types of optical current sensors are implemented and tested in the current range from 10 ampere to 200 ampere.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2439-2441
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• 1998

In this research, the sensor and control system for self detecting masticatory muscle relaxation appliances. A strain gauge is used to measure a strength of tooth clenching force. A bridge circuit and voltage amplifier is designed to amplify measured signals and RF transmitter and receiver is also designed to communicate inner and outer mouth device. The experiments are performed to show the effectiveness of designed system.