• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.277-284
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• 2020

To increase the utilization of the intelligent methodology of smart farm management, estimation modeling techniques are required to assess prior examination of crops and environment changes in realtime. A mandatory environmental factor such as CO₂ is challenging to establish a reliable estimation model in time domain accounted for indoor agricultural facilities where various correlated variables are highly coupled. Thus, this study was conducted to develop an artificial neural network for reducing time complexity by using environmental information distributed in adjacent areas from a time perspective as input and output variables as CO₂. The environmental factors in the smart farm were continuously measured using measuring devices that integrated sensors through experiments. Modeling 1 predicted by the mean data of the experiment period and modeling 2 predicted by the day-to-day data were constructed to predict the correlation of CO₂. Modeling 2 predicted by the previous day's data learning performed better than Modeling 1 predicted by the 60-day average value. Until 30 days, most of them showed a coefficient of determination between 0.70 and 0.88, and Model 2 was about 0.05 higher. However, after 30 days, the modeling coefficients of both models showed low values below 0.50. According to the modeling approach, comparing and analyzing the values of the determinants showed that data from adjacent time zones were relatively high performance at points requiring prediction rather than a fixed neural network model.

• Korean Journal of Environmental Agriculture
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• v.26 no.2
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• pp.179-185
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• 2007

A new technology that utilizes a microbial fuel cell (MFC) has been developed to generate electricity directly from the oxidation of organic matters such as carbohydrates or complex organics in wastewater. Fermentation of these organic matters results in production of volatile fatty acids (VFAs), alcohols, $CO_2$ and $H_2$. We investigated the electricity-producing potential of the VFAs and actual food processing wastewater using a two-chambered MFC. The electrons produced by acetate degradation were proportional to acetate concentration in the medium. Acetate concentration and generated power were linearly correlated at a low range or acetate concentration (< 8 mg/L), but at above 8 mg/L of acetate the power produced was maintained at 0.1 mW. When butyrate was added to the anode acclimated to acetate, there was a lag period of 30 hr for electricity generation. However, when propionate was added to the same anode bottle, lag periods were not existed. The wastewater from baby food processing generated the maximum power density of $81{\pm}7\;mW/m^2$ of electricity and exhibited the Coulombic efficiencies of 27.1% and 40.5% based on TCOD and SCOD, respectively. Sugars in the food processing wastewater were reduced within 50 h from 230 mg/L < 30 mg/L.

• Korean Journal of Crystallography
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• v.13 no.3_4
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• pp.165-171
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• 2002

Single phase $Pb(Fe_{1/2}Ta_{1/2})O_3$, ceramics were successfully synthesized from the powders prepared by solid state reaction (sintering temperature: $1100^{\circ}C$, density: $9.3g/cm^3$, average grain size: $5.1{\pm}1.2mm$, space group: Pm3m). Their dielectric properties measured at $-150{\sim}50^{\circ}C$ showed the maximum relative dielectric constant of 31000 at $-41^{\circ}C$. 1 kHz, and typical relaxor ferroelectrics characteristics such as diffuse phase transition and dielectric relaxation phenomena. However, the diffuseness of phase transition decreased and the dielectric properties became more normal ferroelectrics as the time of annealing at $1000^{\circ}C$ increased. By using Raman spectroscopy, it was revealed that the $Fe^{3+}$ and $Ta^{5+}$ ions in the as-sintered $Pb(Fe_{1/2}Ta_{1/2})O_3$, are stoichiometrically 1 : 1 ordered within the short-range that can not be probed even by transmission electron microscopy, and this stoichiometric 1 : 1 ordering is enhanced by the annealing. The relaxor ferroelectric characteristics in the as-sintered $Pb(Fe_{1/2}Ta_{1/2})O_3$, could be correlated with the stoichiometric 1 : 1 short-range ordering of B-site cations, and the decrease of relaxor ferroelectric characteristics in the annealed $Pb(Fe_{1/2}Ta_{1/2})O_3$ could be correlated with the enhanced stoichiometric 1 : 1 short-range ordering of B-site cations.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.3
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• pp.207-213
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• 2009

The quality of tap water on the whole water-supply system, from a large filtration plant to a private faucet, has to be guaranteed the standards of drinking water. At this point in time, however, the supply process of the tap water has not been monitored and managed scientifically. The piped water, especially the most small-scale reservoirs(underground or overhead type) are always exposed to various contaminations and impurities. Recently monitoring systems of water-quality were spread on some large filtration plants or distributing reservoirs. In particular, the water quality monitoring method using the internet is adopted into some local government whose inhabitants can check up the water quality anytime and anywhere. The construction of this system that has to apply a large scale needs, and has a limitation on the small water-supply system, such as apartments, public facilities and small-scale underground or overhead reservoirs. In this work, we suggest the integration system of individual water-quality sensor modules that have a low price. By using the developed integration system and online monitoring program operated on the internet, the system managers of reservoirs can monitor and manage water-quality characteristic values of drinking water in online. Since the proposed system was modularized, the system can be applied easily into various reservoirs with a low cost and regardless of its scale, small or large.

• Journal of Digital Convergence
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• v.18 no.3
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• pp.163-169
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• 2020

A smart key has been used in a variety of embedded environments and there also have been attacks from a remote place by amplifying signals at a location of a user. Existing studies on defence techniques suggest multiple sensors and hash functions to improve authentication speed; these, however, increase the electricity usage and the probability of type 1 error. For these reasons, I suggest an embedded security controller based on client authentication and user movement information improving the authentication method between a controller and a host device. I applied encryption algorithm to the suggested model for communication using an Arduino board, GPS, and Bluetooth and performed authentication through path analysis utilizing user movement information for the authentication. I found that the change in usability was nonsignificant when performing actions using the suggested model by evaluating the time to encode and decode. The embedded security controller in the model can be applied to the system of a remote controller for a two-wheeled vehicle or a mobile and stationary host device; in the process of studying, I found that encryption and decryption could take less then 100ms. The later study may deal with protocols to speed up the data communication including encryption and decryption and the path data management.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.28-34
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• 2000

Pyroelectric properties of the $Pb(Zr_{0.9}Ti_{0.1})O_3$ ceramics having the rhombohedral structure have been studied by using the dynamic measurement method. The pyroelectric responses of the $Pb(Zr_{0.9}Ti_{0.1})O_3$ ceramics are characterized in both low and high medulation frequency regions and their frequency depences are observed. In the low frequency region (2~200Hz), the change of polarization increases and shows the maximum since the reorientation rate of domains is higher than the modulation frequency. Inthe high frequency region (200~2000Hz), the pyroelectrci response decreases as the frequency increases, because the reorientation of domains is suppressed and so the change of polarization decreases. Pyroelectric coefficient, figure of merit, noise equivalent power and detectivity of the $Pb(Zr_{0.9}Ti_{0.1})O_3$ ceramics are measured as $1.6{\times}10^{-8}C/cm^2{\cdot},\;1.6{\times}10^{-11}C{\cdot}cm/J,\;2.4{\times}10^{-7}W/Hz^{1/2}\;and\;4.17{\times}10^6cm{\cdot}Hz^{1/2}/W$, respectively.

• Journal of Korean Society of Forest Science
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• v.94 no.6
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• pp.468-475
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• 2005

To understand spatiotemporal changes of temperature and humidity in Lentimula edodes cultivation sheds, temperature, relative humidity were measured with HOBO H8 series sensors in log cultivation sheds and sawdust cultivation sheds. The results obtained from October in 2003 to October in 2004 were as follows; 1. Horizontal temperature changes were smaller at center of cultivation shed inside than comer of cultivation shed inside, while relative humidity changes were greater about 3% at center of cultivation shed inside than corner of cultivation shed inside. 2. Vertical temperature changes showed that the temperature was higher at above than at below when the temperature rises, while the temperature was lower at above than at below when the temperature falls. Thus close to soil surface temperature showed a little fluctuation. Vertical relative humidity changes showed that the relative humidity was lower at above than at below when the temperature rises, while the relative humidity was higher at above than at below when the temperature falls. After all temperature and relative humidity was the opposite in cultivation shed. 3. It's showed in log cultivation shed that the minimum temperature was a subzero temperature until the end of April, while the minimum temperature did above zero after the beginning of the May. Besides a winter was the greatest at daily temperature range during the four season, about $30^{\circ}C$. On the other hand the minimum relative humidity was less than 20% at April, May and June but more than 40% after May.

• Journal of Navigation and Port Research
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• v.27 no.1
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• pp.97-102
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• 2003

Wire ropes are used in a myriad of various industrial applications such as elevator, mine hoist, construction machinery, lift, and suspension bridge. Especially, the wire rope of crane is important component to container transfer. If it happens wire rope failures during the operation, it may lead to safety accident, economic loss by productivity decline and so on. To solve this problem, we developed remote wire rope fault detecting system, and this system is consisted of 3 parts that portable fault detecting part, signal processing part and remote monitoring part. All detected signal has external noise or disturbance according to circumstances. So, we applied to discrete wavelet transform to extract a signal from noisy data. It is verified that the detecting system by de-noising has good efficiency for inspecting faults of wire ropes in service. As a result, by developing this system, container terminal could reduce expense because of extension fo wire ropes exchange period and could competitive power. Also, this system is possible to apply in several field such as elevator, lift and so on.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.863-870
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• 2015

A Compensation Algorithm for The Position of the User Hands based on the Moving Mean-Shift ($CAPUH_{MMS}$) in Human Robot Interface (HRI) System running the Kinect sensor is proposed in order to improve the performance of the gesture recognition is proposed in this paper. The average error improvement ratio of the trajectories ($AEIR_{TJ}$) in left-right movements of hands for the $CAPUH_{MMS}$ is compared with other compensation algorithms such as the Compensation Algorithm based on the Compensation Algorithm based on the Kalman Filter ($CA_{KF}$) and the Compensation Algorithm based on Least-Squares Method ($CA_{LSM}$) by the developed realtime performance simulator. As a result, the $AEIR_{TJ}$ in up-down movements of hands of the $CAPUH_{MMS}$ is measured as 19.35%, it is higher value compared with that of the $CA_{KF}$ and the $CA_{LSM}$ as 13.88% and 16.68%, respectively.

• Journal of the Korean Society for Railway
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• v.18 no.5
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• pp.401-409
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• 2015

Defects generated in a railroad track that guides the railroad vehicle have the characteristic of growing fast; as such, the detection technology for railroad track defects is very important because defects can eventually cause mass disasters like derailments. In this study, a speed-up test facility was fabricated to investigate the feasibility of using magnetic flux leakage (MFL) technology for defect detection in a railroad track under speed-up condition; a test was conducted using a railroad track specimen with defects. For this purpose, an MFL sensor head dedicated to the configuration of the railroad was designed and test specimens with artificial defects on their surfaces were manufactured. Using the test facility, a speed-up test ranging from 4km/h to 12km/h was performed and defects including locations were successfully detected from MFL signals induced by defects with enhanced visibility by differentiating raw MFL signals. In the future, it should be possible to apply this system to a high-speed railroad inspection car by improving the lift-off stability that is necessary for speed-up of the developed MFL sensor system.