• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.519-524
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• 2005

Due to the low C/N ratio of domestic wastewater characteristic, addition of external carbon source for the effective N and P removal is necessary. High organic content of food waste can be used for the external carbon source in biological nutrient removal processes, The applicability of condensate of food waste (CFW), which is produced during the high-rate fermentation process, was examined in membrane bioreactor for the nutrient removal. Under the various operating conditions, nutrient removal efficiencies and membrane fouling characteristics were evaluated using synthetic wastewater. From nitrate utilization rate (NUR) test, denitrification rate was 0.19 g $NO_3-N/g$ VSS/day. With the addition of CFW increased, average removal efficiencies of T-N and T-P could be increased up to 64% and 41%, respectively. Also the optimal retention time was 3 hr/5 hr for anoxic/aerobic reactor. When applied to real sewage, membrane fouling resistance was increased up to 60%, which could be reduced from $10.4{\times}10^{12}m^{-1}$ to $5.9{\times}10^{12}m^{-1}$ with the control of influent suspended solid concentration. In summary, it was suggested that CFW could be used as an economical and effective carbon source for membrane assisted biological N and P removal.

• Journal of the Ergonomics Society of Korea
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• v.32 no.6
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• pp.481-487
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• 2013

Objective: The present study aims to evaluate the visual reactions of users when they are playing games of different flow levels, and to explore the visual variables that can sensitively reflect the different flow levels. Background: The flow is defined as a psychological state where interface users feel their actions in a virtual setting identical to those in real environment. To measure the flow states of users, the questionnaire-based FSS(Flow State Scale) has mostly been used. However, this method is a qualitative test that has limits in terms of the accuracy of users' flow experiences. Therefore, more accurate methods to measure users' flow experiences are required. Method: Ten subjects participated in the experiment, where the independent variables were three games with different flow levels(puzzle games, dot drawing and coloring) and the time frame(the first and last 10 seconds in game playing), whereas the dependent variables included the pupil size and the frequency and duration of eye blinking. This study was a within-subject design. Each participant performed three types of games with different flow levels 3 times for each for 10 minutes, and their visual reactions to each game were measured. Results: The higher the flow cause the bigger pupil size(p<0.01) and the lower eye blinking frequency(p<0.1), indicating that different types of games lead to different flow levels. The pupil size during the last 10 seconds when the flow level was higher was bigger by 2.1% compared with that during the first 10 seconds in game playing(p<0.1), and the eye blinking frequency decreased by 12%(p<0.01). Conclusion: It was found out that the pupil size and the frequency and duration of eye blinking were psychophysiological indices for evaluating users' flow experiences, which could quantify the flow states users go through. The psychophysiological variables capable of measuring diverse aspects of the flow need diversifying to be applicable to precise measurement of the flow. Application: These studies are warranted for both quantitative analysis of flow levels and qualitative improvement of cyber leisure in line with development of healthy games.

• Composites Research
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• v.24 no.6
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• pp.56-63
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• 2011

The objective of this study is to investigate appropriate bonding methods of solar cells in order to apply solar cells, which have been receiving particular attention as a renewable energy due to fossil energy depletion and environment issues, to composite structures. Back-contact solar cells with approximately 24.2% energy conversion efficiency were used in this study. Since silicon-based solar cells are mechanically fragile, the secondary-bonding methods using adhesive were examined in this study. The experiment was conducted with three kinds of bonding materials such as EVA film, Resin film and elastic adhesive. The performance of solar cells for three types of adhesives under mechanical loading on test specimens is conducted. In addition, the measuring equipment was designed to evaluate the performance of the solar cells under mechanical loading in real time and the fracture characteristics depending on bonding materials were evaluated. The reason decreasing solar cells efficiency were analyzed and considered by Fractography. The results show that the solar cell performance is largely affected by bonding techniques. Moreover, the bonding method using elastic adhesive shows best solar cell efficiency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1655-1665
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• 2014

Dynamic displacements of structures shows general behavior of structures. Generally, It is used to estimate structure condition and trustworthy physical quantity directly. Especially, measuring vertical displacement which is affected by moving load is very important part to find or identify a problem of bridge in advance. However directly measuring vertical displacement of the bridge is difficult because of test conditions and restriction of measuring equipment. In this study, Artificial Neural Network (ANN) is used to suggest estimation method of bridge displacement to overcome constrain conditions, restriction and so on. Horizontal strain and vertical displacement which are measured by appling random moving load on the bridge are applied for learning and verification of ANN. Measured horizontal strain is used to learn ANN to estimate vertical displacement of the bridge. Numerical analysis is used to acquire learning data for axis strain and vertical displacement for applying ANN. Moving load scenario which is made by vehicle type and vehicle distance time using Pearson Type III distribution is applied to analysis modeling to reflect real traffic situation. Estimated vertical displacement in respect of horizontal strain according to learning result using ANN is compared with vertical displacement of experiment and it presents vertical displacement of experiment well.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.405-413
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• 2000

This study was conducted to develop an on-line monitoring system for a forest hydrological environment and its meteorological condition, such as temperature, wind direction and speed, rainfall and water level on V-notch, electrical conductivity(EC), potential of hydrogen(PH) by the motor drive sensor unit and measurement with a single-chip microprocessor as controller. These results are summarized as follows ; 1. The monitoring system consists of a signal process unit, motor drive sensor unit, radio modem unit and power supply. 2. The motor drive sensor unit protects the sensor from swift current or freezing and can constantly maintain fixed water level during measurements. 3. This monitoring system can transfer the data by radio modem. Additionally, this system can monitor hydrological conditions in real time. 4. The hardware was made of several modules with an independent CPU. They can be mounted, removed, repaired and added to. Their function can be changed and expanded. 5. These are the result of an accuracy test, the values of temperature, EC and pH measured within an error range of ${\pm}0.2^{\circ}C$, ${\pm}1{\mu}S$ and ${\pm}0.1pH$ respectively. 6. This monitoring system proved to be able to measure various factors for a forest hydrological environment in various experimental stations.

• Journal of Adhesion and Interface
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• v.11 no.2
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• pp.57-62
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• 2010

Photo-curable material can be crosslinked among molecules by light source such as UV and visible light materials. Material properties are controlled by crosslink reaction. Shrinkage is occured during the curing reaction of material structure. Phenomenon of shrinkage stress occurs inside the product and reduce the stability of the product causes problems. Heat shrink the evaluation of the phenomenon has been formalized. But the evaluation of photo shrink is not enough. In this experiment, real-time contract with shrinkage tester phenomena and analysis degree of shrinkage of the material differences. According to the research, experimental results and theoretical analysis of the results were big differences. Shrinkage, especially for a number of different functional groups that were very different theory. These differences are occurred by the molecular structure different and not enough reaction.

• Journal of the Korean Solar Energy Society
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• v.30 no.6
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• pp.73-80
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• 2010

This study was conducted to estimate the relative performance of modules with changed characteristics due to long term exposure to the outdoor environment, with a specially made test device for simultaneous measurement of real time power output from the photovoltaic array, taking into account the inclined panel, direct irradiation, power being generated, temperature as well as the optimal analysis timing. In terminology description, M is an abbreviation of module and Group A, Group B are 10 modules series connection (1~10 of M), (11~20 of M) for each of them respectively. The overall mean voltage difference of M-18 with the lowest power output and M-14 with the highest output is-2.13V and it was identifiable that voltage difference was more concentrated to Group B. In addition, in case of M-2 and M-7, M-8, when compared with M-14, the overall mean voltage difference was -0.92V, -1.56 and -0.91V respectively showing the more concentration to Group A. When the temperature of module went up by $1^{\circ}C$, the mean voltage was reduced by 0.35V. For current, Group A was lower than Group B by-0.022A and the ratio of each group was 49.68% and 50.32% respectively, presumably the module with deteriorated properties were more concentrated to Group A relatively. From the comparison of relations with the comprehensive accumulation, M-2, M-7, M-8, M-16 and M-18 were those with deterioration of performance to the worst, thereby requiring precision examination. In comparative efficiency, M-14 was the most excellent one as 12.19% while M-18 as 10.53% was identified that its efficiency was comparatively rapidly reduced.

• Korean Journal of Optics and Photonics
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• v.20 no.6
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• pp.354-360
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• 2009

We have constructed and analyzed the performance of a simple fiber bundle multi-focal microscope. The microscope had a fiber bundle substituted for micro-lens array that is the core part of MMM(multi-focal multi-photon microscope). The MMM is a type of confocal microscope. To analyze the performance and characteristics of the fiber bundle multi-focal microscope, three types of samples were used: a standard grating, USAF 1951(7, 3), and 1951(7, 6). Using two polarizers and a polarizing beam splitter, we eliminated noise and got clear images. We obtained the FWHM of fiber spot images with the standard grating using two different magnifier lenses which were 63X and 20X, and found an image of the sample as a distribution of fiber spot images. For this case we used the low magnification lens, which gives denser distribution, so that we could get clearer images. In order to test the resolution of the fiber bundle multi-focal microscopic system, we used the USAF 1951 sample which has a smaller line interval than that of the standard grating. The FWHM of the line width of the image coincides well with the real line width of the USAF 1951 sample. We confirmed the performance of a fiber bundle multi-focal microscopic system which is relatively simple but has submicron resolution and is able to get 1600 images at the same time.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.127-134
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• 2005

Lost packet robustness is an most important quality measure for voice over IP networks(VoIP). Recovery of the lost packet from the received information is crucial to realize this robustness. So, this paper proposes the lost packet recovery method from the received information for real-time communication for CELP coder. The proposed BS-PLC (Both Side Packet Loss Concealment) based WSOLA(Waveform Shift OverLab Add) allow the lost packet to be recovered from both the 'previous' and 'next' good packet as the LP parameter and the excitation signal are respectively recovered. The burst of packet loss is modeled by Gilbert model. The proposed scheme is applied to G.729 most used in VoIP and is evaluated through the SNR(signal to noise) and the MOS(Mean Opinion Score) test. As a simulation result, The proposed scheme provide 0.3 higher in Mean Opinion Score and 2 dB higher in terms of SNR than an error concealment procedure in the decoder of G.729 at $20\%$ average packet loss rate.

• Journal of Gifted/Talented Education
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• v.25 no.5
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• pp.697-709
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• 2015

This paper aims at shaping remote observatory system environment for schools, developing astronomical observation program using that system and applying it to science-gifted elementary students in order to figure out effects on their scientific investigation ability and attitude. in order to figure out effects of astronomical observation program using remote observatory program on scientific investigation ability and attitude of science-gifted elementary students, test was conducted on gifted students class of 5th grade in A Elementary School(15) and those of 5th grade in B Elementary School(20). The summary of this paper's results are as follows. First, in order to compose remote observatory system, an astronomical telescope available for remote control to transfer actual observed images in real-time was manufactured. Second, learning program for using remote observatory system wad developed by selecting contents through analysis of the curriculum. Third, in order to figure out effects of astronomical observation program using remote observatory program on scientific investigation ability and attitude of science-gifted elementary students. As a result, both of basic investigation ability and integrated investigation abilit, sub-elements of scientific investigation ability, showed significant differences and scientific investigation ability combining basic and integrated investigation abilities showed significant differences as well. Effects of astronomical observation program applying remote observatory also showed significant differences and its sub-elements, openness, collaboration, patience and creativeness did not show significant differences while curiosity, critics and volunteering showed significant differences.