• Korean Journal of Remote Sensing
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• v.22 no.5
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• pp.313-323
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• 2006

Forest Canopy Density is a dynamic process mediated by various natural and anthropogenic factors. It can be changed over time and locations in the same forest type and landscape. However, human dimensions are considered as the primary force of landscape change and subsequent forest canopy loss in tropical regions of the world. Many studies have been indicated that roads have a far greater impact on forests than simply allowing access for human use. Similarly, rivers have been used as means of transportation, hence illegal logging and felling further deplete forest canopy density. The main objective of this study was to investigate the spatio-temporal dynamic alterations of Forest Canopy Density (FCD) across with site associated factors such as biophysical, physical and human interferences in tropical region of Nepal from 1988 to 2001. Landsat TM and ETM+ of 1988 and 2001 were used to assess the spatial and temporal dynamic alterations of FCD. This analysis revealed that distance to human settlements at P=<0.01, rivers, human interferences (path and fire) and species composition had a statistically significance at P=<0.05 level. However, other factors did not show any significant relation. So, we concluded that understanding of dynamic alterations of FCD with respect to factors was quite complex phenomena. Other surrounding environment could also playa significant role. A comprehensive analysis could be required to understand such complexities. Therefore, additional factors such as climatic, biophysical, social, and institutional with respect to spatio-temporal variability should be considered for the better understanding of canopy dynamic.

• Journal of Wind Energy
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• v.4 no.1
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• pp.60-67
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• 2013

A web-based program was developed for analyzing weather and structure data from the HeMOSU-1 offshore meteorological mast installed by the KEPCO Research Institute, and 35 km west-southwestward away from Gyeokpo located in Jeonbuk province. All of the measured data are obtained through the data transmitter and the server systems equipped on the HeMOSU-1 and the aerodynamic laboratory in Chonbuk National University respectively. The dualised server system consists of two servers, one is for logging the 1 second based raw data with 10 minute averaged values, and the other is for managing web page with processed weather data. Daily or weekly 10-min averaged data can be provided based on the input date by users. Processed weather data such as wind rose, Weibull distribution, diurnal distribution, turbulence intensity according to wind speed, wind energy density, and so forth are visualized through the web page which would be both useful and informative for developing the wind farm or designing a wind blade for the wind farm nearby southwest sea around the Korean Peninsula. The URL for this web page is http://www.hemosu.org/.

• Journal of Soil and Groundwater Environment
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• v.8 no.1
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• pp.48-56
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• 2003

A geophysical conductivity logging technique has been adopted to determine hydraulic constants using a simplified physical model that depicts the borehole condition. An experiment has been made by monitoring the conductivity change within the model hole using borehole environment water and incoming-outgoing water of different salinity, under the state of constant flow rate by maintaining balance between inflow and outflow. Conductivity variation features were observed that depended on flow rate, salinity contrasts between fluid within the hole and incoming-outgoing fluid, and density contrasts between fluid conductivity within the hole and incoming fluid. The results of the experiment show the uniform change of fluid conductivity within the hole with time, a fairly good correlation between the flow rate and the conductivity change rate. The geophysical conductivity logging technique can be an efficient tool for determining hydraulic constants if the model equation is verified by henceforward experiments.

• Journal of Korean Society of Forest Science
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• v.99 no.1
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• pp.1-8
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• 2010

The optimum forest road density was calculated with the method which is used in Europe on the investigation site in Korea. The economical optimum forest road density at the minimum total transport cost was 10.51 m/ha. The total transport cost was calculated 235,354 won/ha per year. The forest road construction cost amounted to 99,693 won/ha per year in case of the depreciation period of 30 years and the interest rate of 3%, the forest road maintenance cost amounted to 14,502 won/ha per year, the logging cost amounted to 99,564 won/ha per year, the cost of footpaths amounted to 18,142 won/ha per year, the cost by the loss of the production area amounted to 3,454 won/ha per year.

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.457-465
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• 2013

We integrated and correlated datasets from surface and subsurface geophysics, drilling cores, and engineering geology to identify geological interfaces and characterize the joints and fracture zones within the rock mass. The regional geometry of a geologically weak zone was investigated via a fence projection of electrical resistivity data and a borehole image-processing system. Subsurface discontinuities and intensive fracture zones within the rock mass are delineated by cross-hole seismic tomography and analyses of dip directions in rose diagrams. The dynamic elastic modulus is studied in terms of the P-wave velocity and Poisson's ratio. Subsurface discontinuities, which are conventionally identified using the N value and from core samples, can now be identified from anomalous reflection coefficients (i.e., acoustic impedance contrast) calculated using a pair of well logs, comprising seismic velocity from suspension-PS logging and density from logging. Intensive fracture zones identified in the synthetic seismogram are matched to core loss zones in the drilling core data and to a high concentration of joints in the borehole imaging system. The upper boundaries of fracture zones are correlated to strongly negative amplitude in the synthetic trace, which is constructed by convolution of the optimal Ricker wavelet with a reflection coefficient. The standard deviations of dynamic elastic moduli are higher for fracture zones than for acompact rock mass, due to the wide range of velocities resulting from the large numbers of joints and fractures within the zone.

• Journal of Korean Society of Forest Science
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• v.106 no.2
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• pp.204-212
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• 2017

Soil disturbance caused by timber harvesting is widely recognized as a potential threat to forest utilization. The degree and extent of soil disturbance is believed to vary with respect to harvesting methods and logging machines. This study has conducted to assess the degree of soil disturbance associated with ground-based cut-to-length (GC) and cable yarding with whole tree (CW) harvesting methods. Soil disturbance was classified using a visual assessment of harvest unit. The properties of soils in different disturbance levels were also evaluated to understand the influence of timber harvesting on soil structure with soil core sampling method. The deep disturbance and soil compaction were observed in sites by 48% and 23% through harvesting areas for GC and CW logging methods, respectively. The results showed that logging machine and number of machine passage had significant influences on soil bulk density and porosity. Soil disturbance types such as rutted, slash cover, and compact were influenced by equipment travel trends in a GC method.

• Korean Journal of Environment and Ecology
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• v.29 no.4
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• pp.508-515
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• 2015

Post-fire restoration can affect breeding bird communities and species compositions over a long-term period by determining pot-fire succession, and a long-term monitoring is therefore required to understand its impacts on forest birds. This study aimed to document the effects of post-fire restoration methods on breeding bird communities in three areas: unburned and two burned (nonintervention and intervention with clear-cut logging and planting) stands 13 years after the stand-replacing Samcheok forest fire at Mt. Geombong in Samcheok, South Korea. According to 108 point counts during the breeding season from April to June 2013, we found that the number of individuals, observed bird species, and species diversity index in intervention stands with clear-cut logging and planting were lower than that in nonintervention and unburned control stands. Foraging and nesting guild analysis also showed a lower abundance of foliage searchers, timber drillers, primary cavity nesters and secondary cavity nesters in intervention stands than in the other stands, while no significant difference was detected between the nonintervention and unburned stands. These results imply that an interventional restoration method may deter the recovery of avian breeding communities after forest fires, and also suggest that non-interventional restoration methods may be an effective way to benefit the species diversity and density of breeding bird communities.

• The Journal of Engineering Geology
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• v.29 no.1
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• pp.1-12
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• 2019

Earthquake can change underground stress condition around the hypocenter and affect the fracture systems of the rocks. In Korea, the M5.8 Gyeongju earthquake on September 12, 2016 and M5.4 Pohang earthquake on November 15, 2017 occurred inside the Yangsan fault zone and possibly affected the fracture systems in the Yangsan fault zone and nearby rock masses. In this study, the characteristics of the fracture system (fracture orientation, number of the fractures, fracture spacing and aperture, dip angle, fracture density along depth, and relative rock strength) of the rocks in the low/intermediate level radioactive waste repository site located in the coastal area of the East Sea are analyzed by the impact of the Gyeongju and Pohang earthquakes using acoustic televiewer data taken from the boreholes at the radioactive waste repository site in 2005 and 2018. As a result of acoustic televiewer logging analysis, the fracture numbers, fracture aperture, and fracture density along depth overall increased in 2018 comparing to those in 2005. This increase tendency may be due to changes in the fracture system due to the impact of the earthquakes, or due to weathering of the wall of the boreholes for a long period longer than 10 years after the installation of the boreholes in 2005. In the borehole KB-14, on the whole, the orientation of the fractures and the average fracture spacing are slightly different between 2005 and 2018, while dip angle and relative rock strength in 2005 and 2018 are similar each other.

• Geophysics and Geophysical Exploration
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• v.5 no.4
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• pp.262-271
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• 2002

This study presents a practical procedure for the Bayesian inversion of geophysical data. We have applied geostatistical techniques for the acquisition of prior model information, then the Markov Chain Monte Carlo (MCMC) method was adopted to infer the characteristics of the marginal distributions of model parameters. For the Bayesian inversion of dipole-dipole array resistivity data, we have used the indicator kriging and simulation techniques to generate cumulative density functions from Schlumberger array resistivity data and well logging data, and obtained prior information by cokriging and simulations from covariogram models. The indicator approach makes it possible to incorporate non-parametric information into the probabilistic density function. We have also adopted the MCMC approach, based on Gibbs sampling, to examine the characteristics of a posteriori probability density function and the marginal distribution of each parameter.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.59-66
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• 2019

This study was conducted to evaluate the effect of the synthetic forest road network by calculating the optimal road density and layout of the forest road network in order to construct the systematic road network in the forested area. For this, five comparative routes were additionally planed and compared through evaluation indicators. As a result, the optimum road density of the study site was estimated to be 18.4 m/ha, and the synthetic forest road network was the best in the four indicators such as average skidding distance, standard deviation of skidding distance, development index, and circuity factor. In addition, the synthetic forest road network was comparable to the main road network by about 4 %p in the timber volume available and potential area size for logging, but the construction cost of the road was about 20 %p lower. It showed a synthetic forest road network was better in terms of economy.