• Korean Journal of Materials Research
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• v.23 no.4
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• pp.211-214
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• 2013

The effects of a Ni coating on the sensing properties of nano ZnO:Ni based gas sensors were studied for $CH_4$ and $CH_3CH_2CH_3$ gases. Nano ZnO sensing materials were prepared by the hydrothermal reaction method. The Ni coatings on the nano ZnO surface were deposited by the hydrolysis of zinc chloride with $NH_4OH$. The weight % of Ni coating on the ZnO surface ranged from 0 to 10 %. The nano ZnO:Ni gas sensors were fabricated by a screen printing method on alumina substrates. The structural and morphological properties of the nano ZnO : Ni sensing materials were investigated by XRD, EDS, and SEM. The XRD patterns showed that nano ZnO : Ni powders with a wurtzite structure were grown with (1 0 0), (0 0 2), and (1 0 1) dominant peaks. The particle size of nano ZnO powders was about 250 nm. The sensitivity of nano ZnO:Ni based sensors for 5 ppm $CH_4$ gas and $CH_3CH_2CH_3$ gas was measured at room temperature by comparing the resistance in air with that in target gases. The highest sensitivity of the ZnO:Ni sensor to $CH_4$ gas and $CH_3CH_2CH_3$ gas was observed at Ni 4 wt%. The response and recovery times of 4 wt% Ni coated ZnO:Ni gas sensors were 14 s and 15 s, respectively.

• Journal of Biosystems Engineering
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• v.32 no.6
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• pp.448-454
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• 2007

This study was conducted to develop a 100 kPa soil tensiometer mainly consisted of a porous ceramic cup, water-holding tube, and a digital vacuum gauge, through theoretical design analysis and experimental performance evaluation. Major findings were as follows. 1. Theoretical analysis showed that air entry value of a porous media decreased as the maximum effective size of the pore increased, and the maximum diameter of the pores was $2.9\;{\mu}m$ for measuring up a 100 kPa of soil-water tension. 2. Property analysis of tensiometer porous cups supplied in Korean domestic market indicated that main components were $SiO_2$ and $Al_2O_3$ with a porosity range of $33.8{\sim}49.3%$. 3. The porous cup selected through sample fabrication and air-permeability tests showed weight ratios of 87% and 11% for $Al_2O_3$ and $SiO_2$. The analysis of SEM (scanning electron microscope) images showed that the sample was sintered at temperatures of about $1150^{\circ}C$, which consisted of pores with sizes of up to 25% of those for commercial porous cups. 4. The prototype soil tensiometer was fabricated using the developed porous cup and a digital vacuum gauge that could measure water tension with a pressure of 85 kPa in air tests. 5. In-soil tests of the prototype conducted during a period of 25-day drying showed that soil-water tension values measured with the prototype and commercial units were not significantly different, and soil-water characteristic curves could be established for different soils, confirming accuracy and stability of the prototype.

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.285-292
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• 2016

Objective: This study collected data on muscle fatigue and ground reaction force during walking to provide a basis for development of custom-fitted outdoor walking shoes. The study analyzed an upright body exercise program using spine stabilization technique to determine the effect on foot plantar pressure in archers, demonstrate the effectiveness of upright body exercise, and develop a new, effective, and efficient training program. Method: A 12-week upright body exercise program was evaluated for the effect on plantar pressure in archers. Ten prize-winning archers (3 men, 7 women) in B metropolitan city, each with ${\geq}10years$ of experience, were given an explanation of the content and purpose of the program, and provided informed consent. Upright body exercise was performed 3 times a week for 12 weeks. A resistive pressure sensor was used to measure foot plantar pressure distribution and analyze quantitative information on variation in postural stability and weight shifting in dynamic balance during shooting, as well as plantar pressure in static balance with the eyes open and closed. Results: There were no significant differences in foot plantar pressure before and after participation in the exercise program. There was no statistically significant difference in foot plantar pressure in static balance with the eyes open or closed, or in foot plantar pressure in dynamic balance during shooting. Conclusion: An upright body exercise program had positive effects on foot plantar pressure in static and dynamic balance in archers by reducing body sway and physical imbalance during shooting and with eyes closed. This program is expected to help archers improve their posture and psychological state, and thereby improve performance.

• Journal of Sensor Science and Technology
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• v.18 no.6
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• pp.423-431
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• 2009

Standard uroflowmetry measures the urine weight using single load cell to evaluate the urinary flow rate. Impact noise should be introduced due to gravity when the urine stream falls down into the container upon the load cell. The present study placed three load cells on the three vertices of a regular triangle and the three signals were ensemble averaged to enhance the signal-to-noise ratio(SNR) regardless of how the urination was made. Simulated urination experiment was performed with three different urine collection methods. In all three methods, SNR of the averaged signal was much higher than each load cell signals. With no urine collection device, the present signal averaging technique resulted in SNR values higher by 10~15 dB than when dual funnels or upper funnel were used to guide the urine stream. Therefore, it was demonstrated that the three point measurement followed by with ensemble averaging could enable accurate uroflowmetric test without any specially made urine collection devices.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.11-15
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• 2009

Recently, a new PSC (Prestressed Concrete) bridge system, which is supported by Concrete-filled fiber-reinforced polymer (CFFRP) strut, has been introduced. This bridge is able to reduce self-weight and increase the width of traditional PSC bridges. However, no relevant research has been reported on local behavior of CFFRP strut in the bridge system. The purpose of this study is to investigate local behavior of CFFRP struts using fiber Bragg grating (FBG) sensors. Field tests were performed to examine the hoop strains and longitudinal strains of the FRP strut under various lateral positions and velocities of a test truck. It has been observed that CFFRP strut is under compression regardless of vehicle speed and location. However, the CFFRP strut is sensitive to the lateral position of vehicles in terms of strain magnitude. Results also indicated that the FBG sensors can faithfully record the hoop and longitudinal strains of the FRP strut without electro-magnetic interference.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.2
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• pp.193-201
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• 2014

The sea cage in marine aquaculture might be varied such as on the stability and shape in the open sea by environmental factors. To evaluate the stability of net cage structures in the open sea, the physical and numerical modeling techniques were applied and compared with field observations. This study was carried out to analyse the stability and the volume loss which would have an effect on the fish swimming behavior in the octagonal pillar type fish cage under the open sea. As a results, the volume loss ratio of the fish cage as measured using a depth sensor was indicated a value of the 30.3% under the current velocity (1.1m/s). The fish cage should be consisted of a concrete block with a weight over 10 tons, a mooring rope diameter over 28mm PP, and a shackle of 25mm under the current speed of 1m/sec for reasonable stability.

• Journal of Veterinary Clinics
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• v.35 no.3
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• pp.97-99
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• 2018

The aim of this study is to determine whether subcutaneous temperature (ST) was correlated with rectal temperature (RT) in cattle with inducing artificial fever. In order to determine the correlation between their temperatures, the experiment was performed as follow: Among nine Holstein steers, lipopolysaccharide (LPS) was intravenously administered at a dose of $0.5{\mu}g/kg$ of body weight to six Holstein steer, then, 6 ml of saline was administrated to three steers as a control group. After LPS injection, ST was recorded using subcutaneously implanted thermo-logger sensors at 10-min intervals, and RT was measured using a digital thermometer at 0, 1, 2, 3, 4, 8 and 12 h. In steers with LPS injection, RT was highest at 3 to 4 h and recovered to a pre-challenge temperature at 8-22 h. A similar fluctuation was shown in ST except for an unexpected decrease at 1 h, and a positive correlation between RT and ST was observed in LPS-challenged steers (r = 0.497, P = 0.04). This result suggests that ST could be utilized as an index for early detection of infectious diseases or physiological events.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.4 s.316
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• pp.1-7
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• 2007

When the sensor geometry is poor, the user position estimate obtained by of GN (Gauss-Newton) method is often diverged in radio navigation. In other to avoid divergence problem QCLS (Quadratic Correction Least Square) method using TDOA (Time Difference of Arrival) measurements is introduced, but the estimation error is somewhat large. This paper presents the modified QCLS method using weighted least square. Since the weighting matrix is influenced by the unknown user position, two-step approach is employed in the proposed method. The weighting matrix is estimated in the first step using least square, and then find user position is obtained using weighted least square. Simulation results show that the performance of the proposed method is superior to the conventional QCLS all over the workspace.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.1
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• pp.64-69
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• 1992

To examine the effects of blanching treatments on the drying of hot red pepper, the pilot scale hot-air dryer equipped with the weight sensor using strain gauge type load cell and strain amplifier was designed and manufactured. The drying characteristic curves of cut hot red pepper showed a settling down period followed by a constant rate period and falling rate period, but blanched hot red pepper showed only falling rate period. According as the blanching time and temperature rises, the drying rates and the capsanthin contents of hot red pepper fairly increased. Considering the drying rates and the color values of dried hot red pepper, we suggest the desirable blanching condition of hot red pepper should be water blanching at $80^{\circ}C$ for 3 mins.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.54-62
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• 2012

A Wi-Fi mesh network providing multi-hop wireless connections based on IEEE 802.11 PHY/MAC technology has recently received a significant attention as a network infrastructure that interconnects RFID systems and wireless sensor networks (WSNs). However, the current IEEE 802.11 contention-based MAC protocol cannot fully utilize the network capacity due to eithor frame collisions or unused network resources. In this paper, we propose a novel multi-channel scheduling MAC (MCS-MAC) protocol for Wi-Fi mesh networks. Under the secondary interference model of Wi-Fi mesh networks, the MCS-MAC protocol can maximize the network throughput via activation of collision-free links that has a maximal link weight. Through the simulations, we show that the throughput of the MCS-MAC protocol is at least three times higher than that of existing MAC protocols in Wi-Fi mesh networks.