• Journal of Welding and Joining
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• v.16 no.3
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• pp.95-101
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• 1998

Waveforms of $CO_2$ gas shielded arc welding in short circuit transfer mode was studied with the waveform analysis program, which can calculate various waveform factors such as number of short circuit event, mean and standard deviation of short circuit time and arc time. The calculated values of these factors were correlated independently or in combination with the spatter generation rate to figure out the most reliable index for evaluating spatter generation and further for arc stability. As a result this study, it was confirmed that the spatter generation tends to decrease with the increase of short circuit frequency. Further to this, it was also found that as the short circuit frequency increases the short circuit event becomes more uniform resulting in the decrease of standard deviations ($\sigma$values) of short circuit time and arc time. This result demonstrated that these factors are strongly correlated with each other and thus any one of these factors can be used for the evaluation index. In the discussion, however, short circuit frequency was proposed for the most practical index in evaluating the arc stability of short circuit transfer mode since it is the one which could be monitored in-process condition without any complex caculation process.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.365-373
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• 2012

This study purposed to extract and assess the accuracy of assessment for deforestation area in Wonju city using medium resolution satellite image. The total size of deforestation area during the last nine years (2000-2008) was about 467 ha, and it was occurred annually about 52 ha. The most frequent form of deforestation was settlements (72%). Ninety percent of the size of deforestation was less than 2 ha in size. In addition, 79 percent of deforestation area was found within 500 m from the road network and within 100 m of the Forest/Non-forest boundary. This study compared the deforestation based on the administrative information (GIS deforestationI) with the deforestation (RS deforestation) extracted from the satellite imagery by vegetation indices (NDVI, NBR, NDWI). Extraction accuracy, mean-standard deviation${\times}1.5$ applied 3 by 3 filtering, showed reliable accuracy 35.47% k-value 0.20. However, error could be occurred because of the difference of land-use change and land-cover change. The actual rate of land-cover change deforestation area was 32% on administrative information. The 7.52% of forest management activities area was misjudged as deforestation by RS deforestation. Finally, the comparison of land-cover change deforestation (GIS deforestationII) with the RS deforestation accuracy, as a result NDVI mean-standard deviation${\times}2$ applied 3 by 3 filtering, showed improved accuracy 61.23%, k-value 0.23.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.1
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• pp.107-114
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• 1996

The in situ target strength for the anchovy (Engraulis japonica) were measured by the split beam echo sounder system at 38 kHz. This study allowed us to detect the single echos from anchovy shoals which were dispersed during trawling operation in day time. The results of our study were as fellows: We found that the anchouy occupied about $95\%$ of the total catch from the detected shoals from which target strength data were collected. Length distribution of anchovy showed a mode and ranged from 13.6 to 15.4cm with a mean of 14.4cm and a standard deviation of 0.45cm, and weight distribution showed a mode and ranged from 16 to 28 g witha mean of 21.9 g and a standard deviation of 2.7 g. The target strength distribution of anchovy ranged from -40.7 dB to -69.2 dB in the water layer of ,$10\~30\;m$ -42.19 to -67.7 dB in the $30\~50\;m$ and -42.2 to -67.7 dB in $10\~50\;m$, showing 2 modes in each layer, respectively. Overall mean target strengths were -49.7 dB/fish and -33.1 dB/kg, averaged by area backscattering cross section $(\sigma)$, and the confidence interval for target strength was less than 1 dB. With the mean total length and the mean target strength, we drived the target strength-length relationship as $TS(\sigma)=20\;Log\;L-72.9$.

• Progress in Medical Physics
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• v.23 no.1
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• pp.8-14
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• 2012

In order to develop a Patient respiratory management system includinga biofeedback function for4-dimentional radiation therapy, this study investigated anoptimal tracking algorithmfor moving target using IR (Infra-red) camera as well as commercial camera. A tracking system was developed by LabVIEW 2010. Motion phantom images were acquired using a camera (IR or commercial). After image process were conducted to convert acquired image to binary image by applying a threshold values, several edge enhance methods such as Sobel, Prewitt, Differentiation, Sigma, Gradient, Roberts, were applied. The targetpattern was defined in the images, and acquired image from a moving targetwas tracked by matching pre-defined tracking pattern. During the matching of imagee, thecoordinateof tracking point was recorded. In order to assess the performance of tracking algorithm, the value of score which represents theaccuracy of pattern matching was defined. To compare the algorithm objectively, we repeat experiments 3 times for 5 minuts for each algorithm. Average valueand standard deviations (SD) of score were automatically calculatedsaved as ASCII format. Score of threshold only was 706, and standard deviation was 84. The value of average and SD for other algorithms which combined edge detection method and thresholdwere 794, 64 in Sobel, 770, 101 in Differentiation, 754, 85 in Gradient, 763, 75 in Prewitt, 777, 93 in Roberts, and 822, 62 in Sigma, respectively. According to score analysis, the most efficient tracking algorithm is the Sigma method. Therefore, 4-dimentional radiation threapy is expected tobemore efficient if threshold and Sigma edge detection method are used together in target tracking.

• Journal of IKEEE
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• v.20 no.2
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• pp.167-170
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• 2016

Replica bit-line technique is used for making enable signal of sense amplifier which accurately tracks bit-line of SRAM. However, threshold voltage variation in the replica bit-line circuit changes the cell current, which results in variation of the sense amplifier enable time, $T_{SAE}$. The variation of $T_{SAE}$ makes the sensing operation unstable. In this paper, in addition to conventional replica bit-line delay ($RBL_{conv}$), dual replica bit-line delay (DRBD) and multi-stage dual replica bit-line delay (MDRBD) which are used for reducing $T_{SAE}$ variation are briefly introduced, and the maximum possible number of on-cell which can satisfy $6{\sigma}$ sensing yield is determined through simulation at a supply voltage of 0.6V with 14nm FinFET technology. As a result, it is observed that performance of DRBD and MDRBD is improved 24.4% and 48.3% than $RBL_{conv}$ and energy consumption is reduced which 8% and 32.4% than $RBL_{conv}$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3925-3932
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• 2013

Emotion is closely related to the life of human, so has effect on many parts such as concentration, learning ability, etc. and makes to have different behavior patterns. The purpose of this paper is to extract important features based on physiological signals to recognize negative emotion. In this paper, after acquisition of electrocardiography(ECG), electroencephalography(EEG), skin temperature(SKT) and galvanic skin response(GSR) measurements based on physiological signals, we designed an accurate and fast algorithm using combination of linear discriminant analysis(LDA) and genetic algorithm(GA), then we selected important features. As a result, the accuracy of the algorithm is up to 96.4% and selected features are Mean, root mean square successive difference(RMSSD), NN intervals differing more than 50ms(NN50) of heart rate variability(HRV), ${\sigma}$ and ${\alpha}$ frequency power of EEG from frontal region, ${\alpha}$, ${\beta}$, and ${\gamma}$ frequency power of EEG from central region, and mean and standard deviation of SKT. Therefore, the features play an important role to recognize negative emotion.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.3
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• pp.159-165
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• 2012

In this study, a series of deposition tests have been performed using an annular flume and depositional parameters of natural cohesive sediments have been estimated domestically for the first time. The natural cohesive sediments for deposition tests have been collected from Kwangyang Bay and total 18 deposition tests have been carried out on different bed shear stress respectively but with the same initial concentration. Test results for natural cohesive sediments of Kwangyang bay show that minimum bed shear stress ${\tau}_{bmin}$, standard deviation ${\sigma}_1$, and time scale parameter $({\tau}_b^*-1)_{50}$ are $0.11N/m^2$, 0.68 and 0.85, respectively. Through the comparison with results of previous studies for other sediments, the results of this study are shown to be good enough to verify.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.51-60
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• 2002

The Monte-Carlo simulation of statistical analysis is used to investigate the final conditions of states as well as the footprint boundaries resulting from the atmospheric re-entry dispersions. The re-entry dispersions in this paper are specified by a $7\times7$ covariance matrix of latitude, longitude, altitude, bank angle, flight path angle, heading error, and range at entry velocity. The error sources that affect these at re-entry for a deboost are the uncertainties associated with atmospheric density and temperature, initial errors, wind, and estimation error of aerodynamic coefficients. Using $3{\sigma}_n$ deviations of these errors and a nominal flight trajectory, the covariance matrix of state variables can be determined by performing a trajectory error analysis. Major considerations in the application of the Monte-Carlo method are the simulation of perturbed trajectories, bank reversal, and determination of the impact points for each of these trajectories. This paper analyzes the results of uncertainties from the viewpoint of aero-coefficients and bank reversal.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.6
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• pp.434-442
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• 2015

In this study, a series of deposition tests have been performed using an annular flume in order to estimate depositional parameter of natural sediments. The sediment of Masan Port has been collected for deposition tests, and total 18 deposition tests have been carried out on different bed shear stress respectively but with the same initial concentration. As the results, the minimum bed shear stress ${\tau}_{bmin}$, standard deviation ${\sigma}1$ and time scale parameter $({\tau}_b^*-1)_{50}$ are found to be $0.10N/m^2$, 0.54 and 0.87 respectively. Through comparing with results from previous studies for other sediments, the results of this study are shown to be good enough to verify.

• Analytical Science and Technology
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• v.20 no.6
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• pp.508-515
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• 2007

Age determination was carried out with the bricks relating to Muryong Royal Tomb of the Baekje Kingdom, for which there is no information on the external gamma dose rate, by using the subtraction method of luminescence dating. In the subtraction method, each paleodose for fine grain and for quartz inclusion is required for the sample to be dated. In this study, the paleodose for the fine grain was estimated by thermoluminescence measurement and the paleodose for the quartz inclusion was determined using optically stimulated luminescence. The resultant ages among the bricks showed good agreement with standard deviation of 6 % error. Finally the bricks relating to Muryong Royal Tomb were evaluated as AD $530{\pm}50yrs$($1{\sigma}$ SD).