• Journal of Sensor Science and Technology
• /
• v.11 no.4
• /
• pp.209-217
• /
• 2002

The developing of buried fiber optic sensor with high sensitivity and broad-area detecting intruders is carried out using fiber optic ROTDR(Rayleigh Optical Time Domain Reflectometry). The sensing part was designed to be able to broad-area detect intrusion effect per optical fiber length under ground. The bending light losses in optical fibers are investigated by commercial mini ROTDR with wavelength $1.55{\mu}m$, distance range 5km, pulse width 20ns, SNR=5.7. The sensing fibers are selected as the common telecommunication fibers are the 1.5mm, 3.5 mm outer diameter, 4km each length fiber products. Experiments were investigate the characteristics of signal sensitivity according to applied intrusion weight. The relation between the applied weight and the bending loss was almost linear, and broad-area detect intrusion effects are the 2m resolution and $1.3m^2$ per optical fiber length respectively. The light loss by the applied weight on fiber was 0.17 dB/kg. that the sensitivity of the optical fiber sensor was sufficient to detect intruders passing over the buried optical fiber.

• Journal of the Korean Geotechnical Society
• /
• v.34 no.2
• /
• pp.33-42
• /
• 2018

In this study, the EMI (electro-mechanical impedance) of a small piezoelectric sensor was applied for measuring a unit weight and cementation (strength) of sand. Three different sizes of uncemented Nakdong River sand were filled loosely or densely into a compaction mold. A piezoelectric sensor with 20 mm in diameter was installed within sand for impedance measurement. A small Nakdong River sand was mixed with cement ratios of 4, 8 12, 16% and then compacted into a specimen with 50 mm in diameter and 100 mm in height. The specimen consisted of 6 layers with a sensor at the third layer. The impedance signals for 3 days and unconfined compressive strength at the 3rd day were measured. As the unit weight of uncemented sand increased, the resonant frequency increased slightly from 102 to 105 kHz but a conductance at resonant frequency decreased. For cemented sands, as the curing time and cement ratio increased, the resonant frequency increased significantly from 129 to 266 kHz but the conductance at resonant frequency decreased. The unconfined compressive strength (UCS) of cemented sands was between 289 and 1,390 kPa for different cement ratios. The relationship of UCS and resonant frequency linearly increased but one with a conductance at resonant frequency was in inverse proportion.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.2
• /
• pp.370-376
• /
• 2009

Recently, Study for routing protocol is gone vigorously in the Ubiquitous Sensor Network. A hierarchical routing protocol is being practical and received interest among them. Therefore we analyze a weak point of HEED. And I suggest the new protocol that solved a weak point of HEED. The new protocol that we propose puts weight in the energy remainder amount than HEED and elect CH. And elected CH is designed to change by new node when quantity of energy leftover becomes less than 50%. Therefore all nodes come to use energy fairly. The protocol that we proposed can prove the cluster survival rate about 30%. And CH is more effective because when elect CH replace, response time selects small node.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.393-396
• /
• 2008

Propellant consumption control for space launch vehicle can be achieved by propellant utilization system (PUS) and tank depletion system (TDS). In the course of developing new space launch vehicles, the main target of design is on reducing of space launch vehicle weight, which results in increasing both specific impulse and payload weight. The weights of space launch vehicles are generally allocated to structure, propulsion system, and propellants loaded. The quantity of propellants filled in propellant tanks may be estimated with the propellants actually consumed by propulsion system to complete its mission and the propellants left on-board at the time of engine shut-off. To minimize the remaining quantity of propellants on-board the supplying propellants' O/F ratio should be controlled from the certain time before engine shutdown. To control an O/F ratio, a control system, which accurately measures and compares the remainder of propellants in tanks and pipes, should be needed. This paper solely dedicates its contents to explore the merits and demerits of various level sensor, which is one of the important elements for PUS and TDS, and the transmission and control of signals within space launch vehicle.

• Journal of the Korean Society of Industry Convergence
• /
• v.17 no.4
• /
• pp.203-210
• /
• 2014

In this study, we present a method for correcting unbalanced sitting posture alignment to its optimal position, by designing a chair equipped with pressure sensor. With increasement in sedentary work, such as office work or study, people are now spending more time in chair. To accommodate sedentary life styles, many chairs are being designed for a comfortable sitting condition. However, without awareness and efforts for correct sitting posture, it may not be possible to achieve such condition. When the weight is not distributed evenly while sitting, it may cause various diseases such as scoliosis and a herniated disc. Being inspired by such facts, we have progressed basic researches to maintain the correct sitting posture. To demonstrate the proof-of-concept validation, we installed a series of sensors to a chair and then measured the changes in pressure distribution in various postures. The results show that this approach can be potentially helpful for understanding how fundamental problems due to unbalanced sitting posture can be corrected and maintained properly.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2018.07a
• /
• pp.39-40
• /
• 2018

본 논문에서는 IIoT(Industrial IoT) 환경의 분산 게이트웨이 시스템(Distributed-gateway System)에서 하위의 수 천 개 이상의 센서로부터 데이터를 전송받는 각 게이트웨이의 작업부하(Workload)를 감소시키고 데이터 처리 속도를 향상시키기 위하여 신경망(Neural network) 알고리즘을 이용한 센서 데이터 할당 기법을 소개한다. 각 센서의 중요도에 따른 Weight와 측정 간격에 따른 Bias를 설정하고 학습과정을 통해 Output weight를 산출하여 데이터를 효율적으로 게이트웨이에 할당시킴으로써 신뢰성과 정확성, 신속성을 확보한다.

• Proceedings of the KIEE Conference
• /
• 1993.07a
• /
• pp.383-386
• /
• 1993

In this paper, we propose a sensory data combination method by a fuzzy number approach for multisensor data fusion. Generally, the weighting of one sensory data with respect to another is derived from measures of the relative reliabilities of the two sensory modules. But the relative weight of two sensory data can be approximately determined through human experiences or insufficient experimental data without difficulty. We represent these relative weight using appropriate fuzzy numbers as well as sensory data itself. Using the relative weight, which is subjective valuation, and a fuzzy-numbered sensor data, the fuzzy weighted average method is used for a representative sensory data. The manipulation and calculation of fuzzy numbers can be carried out using the Zadeh's extension principle which can be approximately implemented by the $\alpha$-cut representation of fuzzy numbers and interval analysis.

• Journal of Sensor Science and Technology
• /
• v.16 no.6
• /
• pp.413-418
• /
• 2007

Uroflowmetry is of great convenience to diagnose benign prostate hypertrophy common in aged men. The urinary flow rate is obtained by weight measurement using load cell, however, sensitive to impact noise. An alternative technique was recently proposed to measure hydraulic pressure instead of weight and demonstrated to introduce significantly reduced noise. In this paper, we described the measured diagnostic parameters between the weight and pressure measuring techniques in 10 normal men. The weight and pressure signals were simultaneously acquired during urination, converted into urine volumes, then differentiated to obtain flow rate signals, which showed very similar waveforms. Diagnostic parameters evaluated by pressure measuring technique were well correlated with the standard weight measuring technique (correlation coefficient > 0.99). Therefore, the new uroflowmetry based on hydraulic pressure measurement can provide accurate diagnostic parameters, which would be clinically valid.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.5
• /
• pp.31-37
• /
• 2010

This study was developed the home network system for the home stay care by bio-sensor system to translate the physical signal algorithm. The composition algorithm has five functions for a input function, frequency variable, displacement point input function, axial Variable, axial Sway Displacement to search a max and min point with adjustment of 0.01 unit in the reference level. There were checked physical condition of body balance to compounded a measurement such as a heart rate, temperature, weight. The algorithm of home network system can be used to support health care management system through health assistants in health care center and central health care system. It was expected to monitor a physical parameter for health management system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.11
• /
• pp.2143-2148
• /
• 2016

Recently due to development of IT technology, ideas and technology that blend with environment have evolved. This technology can help people's living environment and in the future it is an essential component of the connected society. In this paper, we propose WiT(WiFI Trashcan) which takes advantage of the IT technology fusion and environmental factors at the same time to create a more pleasant environment. WiT provides a free WiFi when trash is disposed in the trash can. WiT detects whether a user disposes trash, determines the volume of the trash and provides free WiFi. To detect trash we use ultrasonic sensor and trash weight is measured by using weight sensor. Also by using Phython programming the measured sensor value is transmitted to Raspberry Pie and WiFi delivery time is determined. We used Arduino and Raspberry Pi to design and implement WiT.