• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.3
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• pp.233-243
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• 2008

A tunnel behavior predicted in the investigation and design stage is often different from its actual behavior due to mainly the complexity of ground conditions. In a tunnel construction, therefore, it is necessary to ensure the stability of the tunnel by predicting the behaviors of the ground and the supports through observations and measurements, and modifying immediately excavation and reinforcing methods when necessary. To do so, it is important to be able to predict the final tunnel behavior based on the initial tunnel behavior as early as possible. In this study, the correlations were obtained between the initial and the final convergence by analyzing statistically the convergence measurement data, collected from two domestic road tunnels under construction using NATM. In order to estimate the unknown displacements, occurred during the period between the excavation and the first measurement, two methods were used - one is the method by means of regression analysis using a modified exponential function and the other the method by a simple linear regression analysis using the data measured within the distance from tunnel face equal to the tunnel diameter (D). Finally, the relationships were obtained between the initial and final convergence, including the non-measured displacements estimated from the two different methods, by performing linear regression analyses. The regression analysis results showed that there are clear linear relationships between the initial and final convegence and the difference between the two linear regression equations was not that large for when using the exponential function and the simple linear function to estimate the non-measured displacements.

• Journal of Forest and Environmental Science
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• v.15 no.1
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• pp.1-9
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• 1999

Noticing the intrinsic growing habit variations of hardwood species which is indigenous to the natural deciduous forest, eighteen tree species in overstory were selected for comparative evaluating tree form so as to develop the tree form index (TFI). Selected six tree form attributes were arbitrarily divided four assessment criteria and given appropriate scores. Eighteen tree species were undergone corresponding scores, converted to percentage base, and estimated TFI by the summation of the six scoring values. Cluster analysis was carried out to review which attribute would have been shared among species based on dissimilarity of scores for each pair of species in $18{\times}6$ data matrix. The result showed that Populus davidiana had the highest TFI value of 80.8 and Carpinus cordata had the lowest TFI va1ue of 46.3. The species which received more than 70 of TFI are Populus davidiana, Betula costata, Fraxinus mandshurica, and Ulmus davidiana var. japonica, characterized by the advantage of straight and longer bole, the narrower crown, and the thinner branch. On the contrary, such species as Sorbus alnifolia. Prunus sargentii, Acer mandshuricum, Juglans mandshurica, and Carpinus cordata received less than 60 of TFI, characterized by the disadvantage of the crooked or forked stem. the wider or deeper crown. and the thicker branch. In the dendrogram produced by cluster analysis, arbitrary value of Euclidean distance 10 divided eighteen species into four distinctive groups. and the typical characteristics of each group were discussed.

• Korean Journal of Environment and Ecology
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• v.1 no.1
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• pp.46-65
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• 1987

This study was excuted to measure the user's impact area of the Bukhan Mountain National Park. Eighteen sites of the campsite and the picnic area were sample to measure the impact rating of soil and vegetation. And three belt transects were sampled to analyze soil properties and vegetational change by the user's impact. Also user's psychology was investigated through questionnaires with the visitor and 726 answers were collected from May to June in 1987. The regression equation was significant between the distance and the soil hardness. individual number per 100$m^2$, herb coverage and similarity index from the center of picnic area to the non-use site. The tolerant tree against user's impact are Lespedza maximowiczii. Stephanandra insica, Actinidia arguta Symplocos chinensis for. pilosa and the sensitive trees were Fraxinus rhy chophylla Sorbus alnifolia. and Rhodadendron mucronulatun. The facilities factor and social factor are the most affecting factors to User's psychology by the varimax rotated factor analysis. The carrying capacity of the picnic area was 25$m^2$ per man by the degree of psychological satisfaction.

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.7-16
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• 2004

The homogeneous road section is defined as one consisted of similar traffic characteristics focused on demand and supply. The criteria, in the aspect of demand, are the diverging rate and the ratio of green time to cycle time at signalized intersection, and distance between the signalized intersections. The criteria, in that or supply, are the traffic patterns such as traffic volume and its speed. In this study, the effective method to generate valuable data, pointing out the problems of removal method of obscure data, is proposed using data collected from Gonjiam IC to Jangji IC on the national highway No.3. Travel times are collected with licence matching method and traffic volume and speed are collected from detectors. Futhermore, the method of selecting homogeneous road section is proposed considering demand and supply aspect simultaneously. This method using outlier filtering algorithm can be applied to generate the travel time forecasting model and to revise the obscured of missing data transmitting from detectors. The point and link data collected at the same time on the rational highway can be used as a basis predicting the travel time and revising the obscured data in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.581-588
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• 2020

This study examined a brake pad wear compensation method for an Electro-Mechanical Brake (EMB) using the braking test device. A three-phase Interior Permanent Magnet Synchronous Motor (IPMSM) was applied to drive the actuator of an EMB. Current control, speed control, and position control were used to control the clamping force of the EMB. The wear compensation method was performed using a software algorithm that updates the motor model equation by comparing the motor output torque current with a reference current. In addition, a simple first-order motor model equation was applied to estimate the output clamping force. The operation time to the maximum clamping force increased within 0.1 seconds compared to the brake pad in its initial condition. The experiment verified that the reference operating time was within 0.5 seconds, and the maximum value of the clamping force was satisfied under the wear condition. The wear compensation method based on the software algorithm in this paper can be performed in the pre-departure test of rolling stock.

• Journal of Korean Society of Forest Science
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• v.96 no.6
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• pp.667-675
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• 2007

The genetic diversity and the spatial structure in two populations of Abelia tyaihyoni in Yeongwol region were studied by employing I-SSR markers. In spite of the limited distribution and small population sizes of Abelia tyaihyoni, the amount of genetic diversity estimated at the individual level was comparable to other shrub species (S.I.=0.336, h=0.217). Genetic diversity at the genet level was very similar to that at individual level. (S.l.=0.339, h=0.219). About 18.7 percent of total variation was allocated between two populations, which was slightly higher or similar level as compared with other shrub species. Genotypic diversity estimated by the ratio of the number of genets ($N_G$) over the total number of individuals (N) and a modified Simpson's index ($D_G$) were also higher than those of other shrubs. The maximum diameter of a genet did not exceed 5.5 m. The high level of gene and genotypic diversity, and the relatively limited maximum diameter of a genet suggested that the clonal propagation is not the most dominant factor in determining the population structure of Abelia tyaihyoni. Spatial autocorrelation analysis revealed significant spatial genetic structure within 12 m and 18 m distances in two populations A and B, respectively. Autocorrelations among individuals at the both individual and genet levels in each population didn't show any considerable differences. As a sampling strategy for ex-situ conservation of populations showing continuous distribution, a minimum distance of 18 m between individuals was recommended. For the populations with many segments, it was considered very crucial to sample materials from as many segments as possible.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.4
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• pp.43-48
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• 2015

We studied on pseudo-range correction(PRC) modeling in order to improve differential GNSS(DGNSS) accuracy. The PRC is the range correction information that provides improved location accuracy using DGNSS technique. The digital correction signal is typically broadcast over ground-based transmitters. Sometimes the degradation of the positioning accuracy caused by the loss of PRC signals, radio interference, etc. To prevent the degradation, in this paper, we have designed a PRC model through polynomial curve fitting and evaluated this model. We compared two quantities, estimations of PRC using model parameters and observations from the reference station. In the case of GPS, the average is 0.1m and RMSE is 1.3m. Most of GPS satellites have a bias error of less than ${\pm}1.0m$ and a RMSE within 3.0m. In the case of GLONASS, the average and the RMSE are 0.2m and 2.6m, respectively. Most of satellites have less than ${\pm}2.0m$ for a bias error and less than 3.0m for RMSE. These results show that the estimated value calculated by the model can be used effectively to maintain the accuracy of the user's location. However;it is needed for further work relating to the big difference between the two values at low elevation.

• Environmental and Resource Economics Review
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• v.21 no.2
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• pp.321-340
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• 2012

Korean government recently announced that new passenger cars sold within South Korea in 2009 ran an average of 12.27 kilometers per liter of fuel, which is an 7% point increase of the fuel efficiency. The government interpreted these improvements in the fuel economy as energy savings of 60,000 toe and as a reduction of 160,000 ton $CO_2$ emissions. However, improvements in energy efficiency make energy services cheaper, which is known as rebound effect. If this rebound effect exists, and the size of the effect is not negligible, ignoring this could result in overestimating the energy savings achieved by the fuel efficiency increase. Using detailed data on household and vehicle characteristics, our results suggest that there exist a short-run rebound effect of 0.299(29.9%) for the Korean automobile industry. This is notably smaller than the estimates of West (2004), which finds an estimate of 87% using cross-section data for the US. Furthermore our results highlight the importance of rebound effect on energy savings and the $CO_2$ emissions reduction. Our estimates suggest that the report from Korean government overestimates the energy savings and related $CO_2$ emissions by 29.9% point.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.1
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• pp.41-46
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• 2011

Reliable information on the surface solar radiation is indispensable for rebuilding food production system in the famine plagued North Korea. However, transfer of the related modeling technology of South Korea is not possible simply because raw data such as solar radiation or sunshine duration are not available. The objective of this study is restoring solar radiation data at 27 synoptic stations in North Korea by using satellite remote sensing data. We derived relationships between MODIS radiation estimates and the observed solar radiation at 18 locations in South Korea. The relationships were used to adjust the MODIS based radiation data and to restore solar radiation data at those pixels corresponding to the 27 North Korean synoptic stations. Inverse distance weighted averaging of the restored solar radiation data resulted in gridded surfaces of monthly solar radiation for 4 decadal periods (1983-1990, 1991-2000 and 2001-2010), respectively. For a direct application of these products, we produced solar irradiance estimates for each sub-grid cell with a 30 m spacing based on a sun-slope geometry. These products are expected to assist planning of the North Korean agriculture and, if combined with the already prepared South Korean data, can be used for climate change impact assessment across the whole Peninsula.

• Journal of Korea Water Resources Association
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• v.49 no.8
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• pp.645-656
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• 2016

The study performed a regional flood frequency analysis and proposed a regression equation to estimate design floods corresponding to return periods for ungauged basins in Geum-river basin. Five preliminary tests were employed to investigate hydrological independence and homogeneity of streamflow data, i.e. the lag-one autocorrelation test, time homogeneity test, Grubbs-Beck outlier test, discordancy measure test ($D_i$), and regional homogeneity measure (H). The test results showed that streamflow data were time-independent, discordant and homogeneous within the basin. Using five probability distributions (generalized extreme value (GEV), three-parameter log-normal (LN-III), Pearson type 3 (P-III), generalized logistic (GLO), generalized Pareto (GPA)), comparative regional flood frequency analyses were carried out for the region. Based on the L-moment ratio diagram, average weighted distance (AWD) and goodness-of-fit statistics ($Z^{DIST}$), the GLO distribution was selected as the best fit model for Geum-river basin. Using the GLO, a regression equation was developed for estimating regional design floods, and validated by comparing the estimated and observed streamflows at the Ganggyeong station.