• Progress in Medical Physics
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• v.16 no.3
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• pp.148-154
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• 2005

Since the output of retina for visual stimulus is carried by neurons of very diverse functional properties, it is not adequate to use conventional single electrode for recording the retinal action potential. For this purpose, we used newly developed multichannel recording system for monitoring the simultaneous electrical activities of many neurons in a functioning piece of retina. Retinal action potentials are recorded with an extra-cellular planar array of 60 microelectrodes. In studying the collective activity of the ganglion cell population it is essential to recognize basic functional distinctions between individual neurons. Therefore, it is necessary to detect and to classify the action potential of each ganglion cell out of mixed signal. We programmed M-files with MATLAB for this sorting process. This processing is mandatory for further analysis, e.g. poststimulus time histogram (PSTH), auto-correlogram, and cross-correlogram. We established MATLAB based protocol for waveform classification and verified that this approach was effective as an initial spike sorting method.

• Journal of the Korean Society of Radiology
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• v.10 no.8
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• pp.565-569
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• 2016

Recently, a use of linear accelerator with a multi-leaf collimator(MLC) for radiation therapy is increasing. The importance of quality assurance (QA) for the linear accelerator is emphasized as the side effects of the inaccurate delivery of the radiation beam has been increased according to the high dose irradiation technique. In this study, The $HgI_2$ and $PbI_2$ photoconductor layer samples of $400{\mu}m$ thickness were fabricated using sedimentation method among particle-in-binder technology. From the fabricated samples, the electrical properties(dark current, output current, response properties and linearity) were investigated. From the experimental results, $HgI_2$ has good charge signal generation and linearity. Finally, from the signal response results about various thickness of $HgI_2$ sensor, the signal creation efficiency of $400{\mu}m$ thickness of $HgI_2$ sensor has the highest value and the excellent reproducibility below ${\pm}2.5%$.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.177-181
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• 2012

Dye-sensitized solar cells(DSSCs) based on $TiO_2$ film photo anode incorporated with different amount of grapheme nanosheet(GNS) are fabricated and their photovoltaic performance are investigated. The $TiO_2$-GNS composite electrode has been prepared by a direct mixing method. The DSSC performance of this composite electrode was measured using N3 dye as a sensitizer. The performance of DSSCs using the $TiO_2$-GNS composite electrodes is dependent on the GNS loading in the electrodes. The results show that the DSSCs incorporating 0.01 wt% GNS in $TiO_2$photo anode demonstrates a maximum power conversion efficiency of 5.73%, 26% higher than that without GNS. The performance improvement is ascribed to increased N3 dye adsorption, the reduction of electron recombination and back transport reaction as well as enhancement of electron transport with the introduction of GNS. The presence of both $TiO_2$(anatase) and GNS has been confirmed by FieldEmission Scanning Electron Microscopy(FE-SEM). The decrease in recombination due to GNS in DSSCs has been investigated by the Electrochemical Impedance Spectroscopy.

• Journal of Fisheries and Marine Sciences Education
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• v.18 no.3
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• pp.293-301
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• 2006

This study was undertaken to prolonging the freshness in Squid(Todarodes pacificus) on the effects of ice storage methods(tap water ice, electrolytic water ice) using stainless diaphragm electrolytic instrument and also test an efficiency of instrument. Basically, stainless diaphragm electrolytic instrument studied for changes of pH on difference water flow and ampere. The lower water flower and higher ampere made low pH on acid part of electrolytic instrument. Squid samples were stored in tap water ice, acid part of electrolytic water and base part of electrolytic water and used in studying the changes of VBN and skin color through storage. Acid water had strong sterilization effects and VBN was lower levels of acid water than the others. Base water had not sterilization effects. Tap water ice storage was more sterilizing effects than base water ice storage but less effects than acid water ice storage. Lightness of Squid skin showed getting decrease at storage of ice water of all storage methods but acid water ice storage showed more retarding than the other two storage. From these results, it could be suggested that acid electric water ice storage is effective in extendance the shelf-life of squid at chilled storage.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.450-458
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• 2019

Passive cavitation imaging method is used to observe the ultrasonic waves generated when a group of bubbles collapses. A problem with passive cavitation imaging is a low resolution and large side lobe levels. Since ultrasound signals generated by passive cavitation take the form of a pulse, the amplitude distribution of signals received across the receive channels varies depending on the direction of incidence. Both the centroid and flatness were calculated to determine weights at imaging points in order to discriminate between the main and side lobe signals from the signal amplitude distribution of the received channel data and to reduce the side lobe levels. The centroid quantifies how the channel data are distributed across the receive channel, and the flatness measures the variance of the channel data. We applied the centroid weight and the flatness to the passive cavitation image constructed using the delay-and-sum focusing and minimum variance beamforming methods to improve the image quality. Using computer simulation and experiment, we show that the application of weighting in delay-and-sum and minimum variance beamforming reduces side lobe levels.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1195-1206
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• 2011

This study was conducted to apply LCA (Life cycle assessment) methodology to lettuce (Lactuca sativa L.) production systems in Namyang-ju as a case study. Five lettuce growing farms with three different farming systems (two farms with organic farming system, one farm with a system without agricultural chemicals and two farms with conventional farming system) were selected at Namyangju city of Gyeonggi-province in Korea. The input data for LCA were collected by interviewing with the farmers. The system boundary was set at a cropping season without heating and cooling system for reducing uncertainties in data collection and calculation. Sensitivity analysis was carried out to find out the effect of type and amount of fertilizer and energy use on GHG (Greenhouse Gas) emission. The results of establishing GTG (Gate-to-Gate) inventory revealed that the quantity of fertilizer and energy input had the largest value in producing 1 kg lettuce, the amount of pesticide input the smallest. The amount of electricity input was the largest in all farms except farm 1 which purchased seedlings from outside. The quantity of direct field emission of $CO_2$, $CH_4$ and $N_2O$ from farm 1 to farm 5 were 6.79E-03 (farm 1), 8.10E-03 (farm 2), 1.82E-02 (farm 3), 7.51E-02 (farm 4) and 1.61E-02 (farm 5) kg $kg^{-1}$ lettuce, respectively. According to the result of LCI analysis focused on GHG, it was observed that $CO_2$ emission was 2.92E-01 (farm 1), 3.76E-01 (farm 2), 4.11E-01 (farm 3), 9.40E-01 (farm 4) and $5.37E-01kg\;CO_2\;kg^{-1}\;lettuce$ (farm 5), respectively. Carbon dioxide contribute to the most GHG emission. Carbon dioxide was mainly emitted in the process of energy production, which occupied 67~91% of $CO_2$ emission from every production process from 5 farms. Due to higher proportion of $CO_2$ emission from production of compound fertilizer in conventional crop system, conventional crop system had lower proportion of $CO_2$ emission from energy production than organic crop system did. With increasing inorganic fertilizer input, the process of lettuce cultivation covered higher proportion in $N_2O$ emission. Therefore, farms 1 and 2 covered 87% of total $N_2O$ emission; and farm 3 covered 64%. The carbon footprints from farm 1 to farm 5 were 3.40E-01 (farm 1), 4.31E-01 (farm 2), 5.32E-01 (farm 3), 1.08E+00 (farm 4) and 6.14E-01 (farm 5) kg $CO_2$-eq. $kg^{-1}$ lettuce, respectively. Results of sensitivity analysis revealed the soybean meal was the most sensitive among 4 types of fertilizer. The value of compound fertilizer was the least sensitive among every fertilizer imput. Electricity showed the largest sensitivity on $CO_2$ emission. However, the value of $N_2O$ variation was almost zero.

• Clinical and Experimental Pediatrics
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• v.51 no.8
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• pp.804-811
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• 2008

Purpose : Childhood obesity is a problem that places a child at great risk for becoming an obese adult. To prevent obesity, it is important to focus on early life risk factors that may contribute to childhood obesity. The aim of this study is to find obesity-causing infantile risk factors in preschool children. Methods : A total of 223 children aged 3 to 5 years old from Busan were the subjects of this study. We calculated their body mass index (BMI) and classified them into two groups (normal weight and overweight/obese children). Information regarding parental weight and height, mother's educational level and employment status, birth weight, feeding patterns, start time of weaning, duration of night feeding, and fosterer was obtained by using questionnaires. Results : There were 68 (30.5%) overweight/obese children and 155 (69.5%) normal weight children. Overweight/obese children were significantly associated with formula milk feeding, rapid weight gain during the first 6 months, and maternal obesity (P<0.05). There were no statistical differences in paternal obesity, mothers educational level and employment status, birth weight, start time of weaning, duration of night feeding, and fosterer between the normal and overweight/obese children. Conclusion : Although healthy diet and regular exercise will remain the cornerstones of weight management in obese children, our data supports the view that education about maintaining a normal weight could be introduced much earlier in families with high-risk children.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.420-428
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• 2019

This study is the heating energy saving test of the high-bed strawberry crown heating system. The system consists of electric hot water boiler, thermal storage tank, circulation pump, crown heating pipe(white low density polyethylene, diameter 16mm) and a temperature control panel. For crown heating, the hot water pipe was installed as close as possible to the crown part after planting the seedlings and the pipe position was fixed with a horticultural fixing pin. In the local heating type, hot water at $20{\sim}23^{\circ}C$ is stored in the themal tank by using an electric hot water boiler, and crown spot is partially heated at the setting temperature of $13{\sim}15^{\circ}C$ by turning on/off the circulation pump using a temperature sensor for controlling the hot water circulation pump which was installed at the very close to crown of strawberry. The treatment of test zone consisted of space heating $4^{\circ}C$ + crown heating(treatment 1), space heating $8^{\circ}C$(control), space heating $6^{\circ}C$ + crown heating(treatment 2). And strawberries were planted in the number of 980 for each treatment. The heating energy consumption was compared between November 8, 2017 and March 30, 2018. Accumulated power consumption is converted to integrated kerosene consumption. The converted kerosene consumption is 1,320L(100%) for space $8^{\circ}C$ heating, 928L(70.3%) for space $4^{\circ}C$ + crown heating, 1,161L($88^{\circ}C$) for space $6^{\circ}C$ + crown heating). It was analyzed that space $4^{\circ}C$ + pipe heating and space $6^{\circ}C$ + crown heating save heating energy of 29.7% and 12% respectively compared to $8^{\circ}C$ space heating(control).