• Journal of Sensor Science and Technology
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• v.13 no.5
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• pp.383-391
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• 2004

In this study, we implemented the pulse transit time (PTT) system to examine usefulness of the monitoring method of distensibility and elasticity using photoplethysmography sensor in vivo. PTT is defined as the time interval between the peak of QRS complex in ECG signal and the maximum slope point of photoplethysmography. these two signals were converted to digital data by means of AID converter, then PTT was evaluated by heartbeat using PC. Results of analysis were displayed as a graph using spline interpolation method. The variance of PTT was measured repetitiously to verify efficiency of PTT system in resting state and hyperemic state. Repeated measurement of PTT was not same value but showed that coefficients of correlation were related with each other as 0.8302 (P<0.01) in resting state. And also repeated measurement of PTT showed significant correlation as 0.868 (P<0.01) in the hyperemic state. These result showed that PTT is reflect on transient pressure variance in the artery and is very useful method for the evaluation of prognosis of the hypertension and arteriosclerosis.

• Research in Plant Disease
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• v.21 no.4
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• pp.268-272
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• 2015

Bacterial leaf blight caused by Pseudomonas syringae pv. porri is one of the major bacterial diseases of garlic (Allium sativum). In South Korea, the disease has only been observed in garlic-growing regions of Jeju island. The spatial distribution pattern of the disease was analyzed by binary power law, in which the natural logarithm of the observed variance is regressed on the natural logarithm of the binomial variance. The estimated slope (b=1.361) of the regression was greater than 1 which meant that the diseased plants were aggregated. The sequential sampling plans were developed for estimating the mean incidence rate ($p_m$) and classifying the mean incidence as being below or above the critical incidence rate ($p_t$). These results could be used on more efficient and higher precisive sampling for bacterial blight of garlic compared to fixed sample sized sampling.

• Journal of the Korean Professional Engineers Association
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• v.25 no.4
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• pp.102-108
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• 1992

This study was carried to find out the soil characteristics of landslide site and to develope landslide prediction method by seismic refraction prospecting. For these aims, landslide condition and travel time were investigated at 68 Landslide sites over the country during 1990 to 1991. The results were as follows. 1. The surface of rupture was included mainly in C layer. Its Hardness was less than 3kg / $\textrm{cm}^2$ at the upper pare of landslide. 2. When the profile line length was 20m, the range of travel time was 40 to 90 msec. The travel time did not differ between bedrocks. 3. Refraction distance ranged from 1 to 7m and mean of that was 2.5m. Travel time was increased according to receiving distance without large variance in the refraction distance but that was appeared large variance out of the refraction distance on slope that has shallow soil depth and discontinuous ground surface. Therefore, the spread distance must be shorten to 10-l5m. 4. The seismic velocity at the first layer(layer of rupture) was less than 500m1sec by degree of weathering and the velocity at the second layer decreased in order of Granite> Granitic gneiss >Sedimentary rock. 5. The first layer observed by seismic refraction was contained C layer that has parent material and weathered rocks of hardness 10-20kg/$\textrm{cm}^2$. 6. Among the range of seismic velocity was less than 200m/sec in 63% of the total plots, 200-300m/sec in 34% and 300-500m /sec in 3%. 7. There was a proportional relationship between seismic prospecting soil depth and executive soil depth, and seismic propection soil depth was about 10 to 20cm deeper than the order.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.175-190
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• 1994

In order to get fundamental information for prediction of landslide hazard, both forest and site factors affecting slope stability were investigated in many areas of active landslides. Twelve descriptors were identified and quantified to develop the prediction model by multivariate statistical analysis. The main results obtained could be summarized as follows : The main factors influencing a large scale of landslide were shown in order of precipitation, age group of forest trees, altitude, soil texture, slope gradient, position of slope, vegetation, stream order, vertical slope, bed rock, soil depth and aspect. According to partial correlation coefficient, it was shown in order of age group of forest trees, precipitation, soil texture, bed rock, slope gradient, position of slope, altitude, vertical slope, stream order, vegetation, soil depth and aspect. The main factors influencing a landslide occurrence were shown in order of age group of forest trees, altitude, soil texture, slope gradient, precipitation, vertical slope, stream order, bed rock and soil depth. Two prediction models were developed by magnitude and frequency of landslide. Particularly, a prediction method by magnitude of landslide was changed the score for the convenience of use. If the total store of the various factors mark over 9.1636, it is evaluated as a very dangerous area. The mean score of landslide and non-landslide group was 0.1977 and -0.1977, and variance was 0.1100 and 0.1250, respectively. The boundary value between the two groups related to slope stability was -0.02, and its predicted rate of discrimination was 73%. In the score range of the degree of landslide hazard based on the boundary value of discrimination, class A was 0.3132 over, class B was 0.3132 to -0.1050, class C was -0.1050 to -0.4196, class D was -0.4195 below. The rank of landslide hazard could be divided into classes A, B, C and D by the boundary value. In the number of slope, class A was 68, class B was 115, class C was 65, and class D was 52. The rate of landslide occurrence in class A and class B was shown at the hige prediction of 83%. Therefore, dangerous areas selected by the prediction method of landslide could be mapped for land-use planning and criterion of disaster district. And also, it could be applied to an administration index for disaster prevention.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.1
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• pp.25-31
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• 2008

Information on daily maximum air temperature is important in predicting the status of plants and insects, but the uneven and sparse distribution of weather stations prohibits timely access to the data in regions with complex topography. Since cumulative solar irradiance plays a critical role in determining daily maximum temperature on any sloping surfaces, derivation of a quantitative relationship between cumulative solar irradiance and the resultant daily maximum temperature is a prerequisite to development of such estimation models. Air temperatures at 8 sideslope locations with similar elevation and slope angle but aspect, circumventing a cone-shaped, grass-covered parasitic volcano (c.a., 570 m diameter for the bottom circle and 90m bottom-to-top height), were measured from June to December in 2007. Daily maximum temperatures from each location were compared with the average of 8 locations (assumed to be the temperature measured at a "horizontal reference" position). The temperature deviation at all locations increased with the day of year (or sun elevation) from summer solstice to winter solstice. Averaged over the entire period, the south facing location was warmer by $1^{\circ}C$ in daily maximum temperature than "horizontal reference" and the north facing location was cooler by $0.8^{\circ}C$ than the reference, resulting in the year round average south-north temperature difference of $1.8^{\circ}C$. In November, both south and north facing slopes showed the greatest deviation of $+2.0^{\circ}C$ and $-1.3^{\circ}C$, respectively in daily maximum temperature at monthly scale. On a daily scale, the greatest deviation was +3.8 and $2.7^{\circ}C$ at the south and north slope, respectively. The cumulative solar irradiance (on the slope for 4 hours from 11:00 to 15:00 TST) explained >60% of the variance in daily maximum temperature deviations among 8 locations, suggesting a feasibility of developing an estimation model for daily maximum temperature over complex topography at landscape scales.

• Journal of the Korean Society of Child Welfare
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• no.40
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• pp.41-71
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• 2012

The purpose of this study is to examine longitudinal impacts of various factors on happiness in primary school children. Specifically, attachment theory and ecosystems perspective were utilized for the purpose of this study. We used Korea Youth Panel Survey, which is a 5-year longitudinal data collected from fourth grade in elementary school to second grade in middle school Latent growth model was employed as the analytic method. The findings of this study are as follow: first, academic achievement, self-esteem, parent attachment, peer attachment, teacher attachment, and community attachment all decreased over the 5-year study period. Also, the intercept and the slope variance of variables were found to be statistically significant. This means that there are significant differences in the intercept and the slope of individuals. Second, self-esteem, parent attachment, and peer attachment were found to have cross-sectional influences on happiness. This means that self-esteem, parent attachment, and peer attachment are positively associated with happiness at the intercept. Also, self-esteem, parent attachment, teacher attachment, and community attachment were found to have longitudinal influences on happiness. This means that the higher levels of community attachment at the intercept is associated with slower the rate of decrease in happiness at the slope. In addition, faster rates of decrease in self-esteem, parent attachment, teacher attachment, and community attachment are associated with faster the rate of decrease in happiness. Third, this study conducted multiple group analysis with gender. The findings of this analysis revealed no significant differences in analytic models between males and females. Based on these findings, theoretical and practice implications with regard to happiness in primary school children are discussed.

• Journal of Korean Society of Disaster and Security
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• v.16 no.4
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• pp.1-7
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• 2023

The purpose of this study is an experimental research to investigate the effectiveness of debris flow reduction structures when a debris flow disaster occurs on a steep slope. The control structure for debris flow took the form of baffle, and the soil deposition area and soil runout distance due to debris flow from the downstream were investigated according to the installation number of baffle and each specification. As the slope of the channel became steeper, the sediment deposition area and runout distance increased, and as the sediment volume concentration decreased, the sediment deposition area and runout distance increased. When the sediment concentration was low, differences appeared depending on the slope of the channel because the debris flow had a high liquid content. Overall, the larger the sediment volume concentration, the greater the decrease in sediment deposition area and soil runout distance. As the number of baffles increases, the soil deposition area and runout decrease, showing that the baffles have the ability to control debris flows. The results of this research will provide good information when installing attenuation or control structures when sediment disasters occur in steep slopes.

• Journal of Korean Society of Forest Science
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• v.98 no.6
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• pp.639-645
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• 2009

The objective of this research was to introduce the TPI approach for interpreting land-forms of mountain forests in South Korea. We develop an objective procedure to decide the scale factor as a basic analytical unit in land-form classification of rugged mountain areas using TPI. In order to determine the scale factor associated with the pattern of slope profiles, the gradient variance curve was derived from a revised hypsometric curve developed using the relief energy of topographic profiles. Using the gradient variance curve, found was the grid size with which the change in relief energy got the peak point. The grid size at the peak point was determined as the scale factor for the study area. In order to investigate the performance of the procedure based on the gradient variance curve, it was applied to determination of the site-specific scale factors of 3 different terrain conditions; highly-rugged, moderately-rugged and relatively less-rugged. The TPI associated with the corresponding scale factors by study site was, then, determined and used in classifying the land-forms. According to the results of this study, the scale factor gets shorter with more rugged terrain conditions. It was also found that the numbers of valleys and ridges estimated with TPI show almost the same trends as those of the observed and the scale factors tends to approach to the mean distance of ridges.

• 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.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.3
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• pp.315-320
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• 2002

Test-day records (n=13677) sampled from 896 ewes in 5-9 (${\mu}$=7.5) monthly test-days were used to estimate genetic and phenotypic parameters of test-day yields, lactation milk yield (TMY), length of the milking period (DAYS) and three measures of persistency of milk yield in Boutsico dairy sheep. Τhe measures of persistency were the slope of the regression line (${\beta}$), the coefficient of variation (CV) of the test-day milk yields and the maximum to average daily milk yield ratio (MA). The estimates of variance components were obtained under a linear mixed model by restricted maximum likelihood. The heritability of test-day yields ranged from 0.15 to 0.24. DAYS were found to be heritable ($h^2$=0.11). Heritability estimates of ${\beta}$, CV and MA were 0.15, 0.13, 0.10, respectively. Selection for maximum lactation yields is expected to result in prolonged milking periods, high rates of decline of yields after peak production, variable test-day yields and higher litter sizes. Selection for flatter lactation curves would reduce lactation yields, increase slightly the length of the milking period and decrease yield variation as well as litter size. The most accurate prediction of TMY was obtained with a linear regression model with the first five test-day records.