• Korean Journal of Remote Sensing
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• v.34 no.1
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• pp.25-43
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• 2018

The effects of hydro-meteorological and surface variables on the frequency of Asian dust events (FAE) were investigated using ground station and satellite-based data. Present weather codes 7, 8, and 9 derived from surface synoptic observations (SYNOP)were used for counting FAE. Surface wind speed (SWS), air temperature (Ta), relative humidity (RH), and precipitation were analyzed as hydro-meteorological variables for FAE. The Normalized Difference Vegetation Index (NDVI), land surface temperature (LST), and snow cover fraction (SCF) were used to consider the effects of surface variables on FAE. The relationships between FAE and hydro-meteorological variables were analyzed using Z-score and empirical orthogonal function (EOF) analysis. Although all variables expressed the change of FAE, the degrees of expression were different. SWS, LST, and Ta (indices applicable when Z-score was < 0) explained about 63.01, 58.00, and 56.17% of the FAE,respectively. For NDVI, precipitation, and RH, Asian dust events occurred with a frequency of about 55.38, 67.37, and 62.87% when the Z-scores were > 0. EOF analysis for the FAE showed the seasonal cycle, change pattern, and surface influences related to dryness condition for the FAE. The intensity of SWS was the main cause for change of FAE, but surface variables such as LST, SCF, and NDVI also were expressed because wet surface conditions suppress FAE. These results demonstrate that not only SWS and precipitation, but also surface variables, are important and useful precursors for monitoring Asian dust events.

• Journal of the Korean Geographical Society
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• v.33 no.3
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• pp.365-376
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• 1998

The goal of this study is to find the geomorphic variables contolling gully development on hillslopes following deforestation. Two possible geomorphic processes, surface erosion and mass movement were reviewed to compare the characteristics and geomorphic variables involved. The research objective in this paper is to find the variables and the statistical model which can explain gully density in the study area. Gully density was selected as a response variable. For log gully density, the best subset regression was found to have the variables such as area, surface length, and surface width. Log area is the most significant predictor. Even with several outliers, the normal probability plot of the residuals from this regression looks straight. So, area, surface length, and surface width explain half of the variance in gully density.

• Culinary science and hospitality research
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• v.20 no.5
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• pp.71-75
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• 2014

The purpose of this study is to verify antecedent variables that affect emotional labor. The results are as follows. First, display rules positively affected deep acting and negatively affected surface acting. Second, customer contact time positively affected deep acting but did not affect surface acting. Third, the interaction between display rules and customer contact time did not have significant effects on surface acting but negatively affected deep acting. The implications based on these results are as follows. First, theoretically, this study extends the range of leading variables that affect emotional labor and verifies the moderation effects between these variables. Next, practically, this study suggests that presenting harmonious criteria with regards to display rules and customer contact time that fit well into the concept of food service company is a very useful tool to manage emotional labor of the employees. The limitation of this study is that the causal relationship between variables demonstrated in this study cannot be generalized due to convenience sampling and cross sectional research.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.1
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• pp.124-130
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• 2018

The EMG amplitude estimator, which has been investigated as an indicator of muscle force, is of high relevance not only in biomechanical studies but also more and more in clinical applications. This paper presents a new approach to estimate surface EMG amplitude by using the mean spike and mean turn amplitude(MSA and MTA) variables. Surface EMG signals, a total of 198 signals, were recorded from biceps brachii muscle over the range of 20-80%MVC isometric contraction and performance of the MSA and MTA variables applied to amplitude estimation of the EMG signals were investigated. To examine the performance, a SNR(signal-to-noise ratio) was computed from each amplitude estimate. The results of the study indicate that MSA and MTA amplitude estimations with first order whitening filter and 300[ms]-350[ms] moving average window length are optimal and show better performance(mean SNR improvement of 6%-15%) than the most frequently used variables(ARV and RMS).

• Journal of the Korean Institute of Landscape Architecture
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• v.13 no.2
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• pp.37-70
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• 1985

The purpose of this study is to present objective basic data for environmental design by the quantitative analysis of visual quality emboded in physical environment. For this, as for the front garden of high schools, the spatial image was measured by the S.D. Scale Method, Factor Analysis was proceeded by the principal component analysis and the visual preference was investigated by the Paired Comparision Method. The scale values of plain and unpleasant road surface and external appearance of buildings, which are related to emotions of simpleness fell from straightness and stability, were found to be high. But, except for the road surface of Kyunggi High School, scale values of variables explaining the variation of the quality of materials, level of floor and rythm were generally low. For all green spaces, scale values of variables explaining the degree of pleasantness was found to be generally high. And, those explaining tidiness and characteristics of green spaces were not in the same tendency. But, the green spaces of Youngdong High school can be considered to the space with plenty of visual absorption uniqueness were high. As for the correlation between variables, variables for green spaces(12 and 26) and those for overall view of front garden( 1 and 4) revealed high positive correlation. Also, "order - disorder" and "convenient- incovenient" included in road surface variable can be regarded to have the same meaning since the correlation coefficient between them is very high, 0.7045. Image variables including road surface, external appearance of buildings, green spaces and overall view of front garden showed 91.21~61.08% of total variance. Thus, the remains can be considered to be the error valiance or specific variance. In Fctor I, II and III, main components explaining the road surface image of front gardens are order, hardness, texture, color, gradient and rythm. As for the external appearance of b wilding, variables of color, hardness, stability, peculiality and shape revealed high values of factor load. For all variables, communality was drastically high and ellen values and common variance were found to be very high in Factor I. As for the front gardens, variables explaining volume and peculiarity were found to be the main components of Factor I. In Factor II and III, variables of factor load were tidiness, pleasantness.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1246-1254
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• 2009

The reproducibility of initial value and change over time of surface EMG spike variables(MSA, MSF, MSS, MSD) was investigated in the biceps brachii muscle of 11 healthy subjects. Surface EMG signals were recorded during sustained isometric voluntary contractions for 30 seconds at three contraction levels, 20%, 50%, and 80%MVC, respectively. Each contraction was repeated three times in each of three different days for a total of nine contractions and 99 contractions per %MVC level across the eleven subjects. A total of 297 EMG signals across the different trials, days, subjects, and %MVC levels was saved for the subsequent analysis. The degree of reproducibility was investigated using the intraclass correlation coefficient(ICC) and the standard error of the mean(SEM) based upon the analysis of variance(ANOVA), Results for intercept showed higher reproducibility of the spike variables with about 60%-98% ICC than the variable(ARV, MNF) which had been analyzed before in other researches. And results for slope showed poor reproducibility of the spike variables with about 30%-70% ICC and they were comparable with the variables of other researches.

• Transactions of Materials Processing
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• v.19 no.5
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• pp.290-295
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• 2010

Shaving technology is one of the significant metal forming technologies which can make the smooth and fine sheared surface of products after shearing process. The sheared surface on the side wall of the cutting edge is very important because it functions as a basic surface for measuring the dimensions of product. Effective sheared surface after shaving can be influenced by several working variables such as shaving allowance, shaving clearance, type of material and profile of cutting edge. The influence of these variables on shaving characteristics was investigated in this study. A cut-off die to make the simplified gear-shaped products was manufactured. Three kinds of sheet metals (AL5052, SPCC and SAPH440) of 3mm thickness were firstly sheared and then shaved for four shaving allowances and three sharing clearances. It was shown through experiments that the optimum working condition to give the maximum effective sheared surface in shaving was found ; Shaving allowance is 0.2mm and Shaving clearance is 0.01mm.

• Journal of the Korean institute of surface engineering
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• v.43 no.3
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• pp.159-164
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• 2010

Surface roughness of deposited or etched film strongly depends on ion bombardment. Relationships between ion bombardment variables and surface roughness are too complicated to model analytically. To overcome this, an empirical neural network model was constructed and applied to a deposition process of silicon nitride (SiN) films. The films were deposited by using a pulsed plasma enhanced chemical vapor deposition system in $SiH_4$-$NH_4$ plasma. Radio frequency source power and duty ratio were varied in the range of 200-800 W and 40-100%. A total of 20 experiments were conducted. A non-invasive ion energy analyzer was used to collect ion energy distribution. The diagnostic variables examined include high (or) low ion energy and high (or low) ion energy flux. Mean surface roughness was measured by using atomic force microscopy. A neural network model relating the diagnostic variables to the surface roughness was constructed and its prediction performance was optimized by using a genetic algorithm. The optimized model yielded an improved performance of about 58% over statistical regression model. The model revealed very interesting features useful for optimization of surface roughness. This includes a reduction in surface roughness either by an increase in ion energy flux at lower ion energy or by an increase in higher ion energy at lower ion energy flux.

• Geomechanics and Engineering
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• v.12 no.2
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• pp.313-326
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• 2017

Based on the reliability theory and limit analysis method, the roof stability of a shallow tunnel is investigated under the condition of surface settlement. Nonlinear Hoek-Brown failure criterion is adopted in the present analysis. With the consideration of surface settlement, the internal energy and external work are calculated. Equating the rate of energy dissipation to the external rate of work, the expression of support pressure is derived. With the help of variational approach, a performance function is proposed to reliability analysis. Improved response surface method is used to calculate the Hasofer-Lind reliability index and the failure probability. In order to assess the validity of the present results, Monte-Carlo simulation is performed to examine the correctness. Sensitivity analysis is used to estimate the influence of different variables on reliability index. Among random variables, the unit weight significantly affects the reliability index. It is found that the greater coefficient of variation of variables lead to the higher failure probability. On the basis of the discussions, the reliability-based design is achieved to calculate the required tunnel support pressure under different situations when the target reliability index is obtained.

• The Journal of Korean Physical Therapy
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• v.23 no.2
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• pp.7-15
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• 2011

Purpose: We investigated the relationship between the muscle activity and kinematic variables of the upper extremity during a push-up task on stable and unstable surfaces. Methods: We recruited 15 healthy subjects. Subjects completed the push-up task on stable and unstable surfaces. Surface electromyograms were recorded from the serratus anterior, upper trapezius, latissimus dorsi, infraspinatus to monitor changes in muscle activity. Markers for kinematic changes of elbow flexion, shoulder extension, shoulder retraction and scapular adduction were attached at C7, the T7 spinous process, both acromions, the scapula superior and inferior angle, the humerus lateral epicondyle, and the ulnar styloid process. Correlation coefficients between muscle activity and kinematic variables were analyzed by SPSS for Windows, version 15.0. Results: On the unstable surface, elbow flexion and shoulder extension increased with increasing muscle activity of serratus anterior, upper trapezius and infraspinatus. On the stable surface, shoulder retraction decreased with increasing muscle activity of serratus anterior and infraspinatus. Scapular adduction decreased with all types of increasing muscle activity, regardless of the support surface. Conclusion: Correlations between muscle activity and kinematic variables were observed on stable and unstable surfaces during a push-up task, while correlations between right and left variables were not clear. These finding suggest that it may be used to develop a rehabilitation program which could be effective in improving shoulder function in patients with shoulder problems.