• Geophysics and Geophysical Exploration
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• v.21 no.2
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• pp.82-93
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• 2018

Resistivity monitoring data at embankment dams are affected by the seasonal temperature variation. Especially when the seasonal temperature variation is large like Korea, the temperature effects may not be ignored in the longterm resistivity monitoring. Therefore, temperature effects can make it difficult to accurately interpret the resistivity monitoring data. In this study, through analyzing the time series of ground temperature collected at an embankment dam, ground temperature variations are calculated approximately. Then, based on the calculated temperature profile with depth, the inverted resistivity model of the embankment dam is corrected to remove the temperature effects. From these corrections, it was confirmed that the temperature effects are significant in the upper, superficial part of the dam, but can be ignored at depth. However, temperature correction based only on the temperature distribution in the dam body cannot remove the temperature effect thoroughly. To overcome this problem, the effect of temperature variation in the reservoir water seems to be incorporated together with the air temperature variation.

• The Journal of Engineering Research
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• v.2 no.1
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• pp.165-174
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• 1997

It is not possible to define the earth's interior because of it complicity. However, it can be interpreted directly and/ or indirectly. Geophysics is the subject of this study. To study the possibility of construction supervision by geophysical method, geophysical prospecting was performed and studied at the SamYang pumping well area in Cheju Island, where, although underground dam was constructed, the saline water invade the pumping well area. This study focuses on the construction supervision by electrical measurements. Two electric resistivity survey lines are installed in the pumping well site, and at each line electric survey was conducted at ebb and flow tides. To increase the data quality SP (self-potential) survey was also performed. As a result the geophysical exploration methods explained the defect of construction well, and It shows that geophysical probe can be a useful tool for the construction supervision.

• Korean Journal of Agricultural Science
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• v.27 no.2
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• pp.101-106
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• 2000

A total of 181 Holstein and 73 Korean cattle were used to investigate the association of bovine leukemia virus (BLV) resistance stains with major economic traits. The frequencies of BLV resistance strain with 91bp PCR products were 60.0% and 40.0% in Holsten and Korean cattle, respectively. The association of BLV resistance and susceptibility strains with 305-d milk and 305-d milk fat yields were not significant(P>0.05) in Holstein cattle. Body weights at birth, 6-mon, and 120-mon of age were not significantly associated with the BLV resistance and susceptibility strains of Holstein and Korean cattle. It could be concluded that the alleletypers of BLV resistance were not associated with major economic traits in Holstein and Korean cattle.

• Journal of the Korean Geotechnical Society
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• v.36 no.9
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• pp.21-32
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• 2020

In this study, series of cyclic triaxial tests and shear velocity measurement were conducted using Pohang sand, which was taken from liquefaction observed area, to verify the liquefaction characteristics of Pohang. The cyclic resistance ratio(CRR) was derived based on the test results. A specimen was reconstituted into 40% and 80% relative density conditions and then a series of cyclic triaxial tests and shear-wave velocity measurement were conducted. As a result, the effect of particle distribution and relative density to liquefaction resistance was verified. The liquefaction resistance of Pohang sand was evaluated by comparing with other liquefaction resistance of sands from previous research. In addition, the liquefaction resistance curve from field observation data was used to verify the reliability of results from this study by measured shear-wave velocity.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.525-539
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• 2020

A site containing buried solid waste and treated water and oil storage containers from a leather manufacturing plant was studied through soil and groundwater pollution and electrical resistivity surveys with the aim of identifying areas polluted by leachate generated by landfilling with leather waste and leakage wastewater. It was found that TPH and Zn exceeded environmental standards for soil pollution and, for leachate and groundwater, Cr(VI) concentrations exceeded standard levels for groundwater quality. An electrical resistivity survey was used to elucidate soil and groundwater pollution characteristics and diffusion pathways. Ten survey lines were set up with an electrode spacing of 5 m in a dipole-dipole array. The hydraulic characteristics of soil determined by groundwater contamination surveys matched well the low-resistivity-anomaly zones. Electrical resistivity surveys of areas containing contaminated soil and groundwater that have irregular strata due to waste reclamation are thus useful in highlighting vertical and horizontal pollutant diffusion pathways and in monitoring contaminated and potentially contaminated areas.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.563-572
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• 2010

Both multi-channel temperature monitoring and geophysical electric survey were performed together for an embankment to assess the leakage zone. Temperature variation according to space and time on the inner parts of engineering constructions (e.g.: dam and slope) can be basic information for diagnosing their safety problem. In general, as constructions become superannuated, structural deformation (e.g.: cracks and defects) could be generated by various factors. Seepage or leakage of water through the cracks or defects in old dams will directly cause temperature anomaly. This study shows that the position of seepage or leakage in dam body can be detected by multi-channel temperature monitoring using thermal line sensor. For that matter, diverse temperature monitoring experiments for a leakage physical model were performed in the laboratory. In field application of an old earth fill dam, temperature variations for water depth and for inner parts of boreholes located at downstream slope were measured. Temperature monitoring results for a long time at the bottom of downstream slope of the dam showed the possibility that temperature monitoring can provide the synthetic information about flowing path and quantity of seepage of leakage in dam body. Geophysical data by electrical method are also added to help interpret data.

• The Korean Journal of Mycology
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• v.31 no.2
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• pp.98-102
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• 2003

Metalaxyl sensitivity related with distribution feature of mating type was characterized far Phytophthora capsici population, totally 433 isolates of the red-pepper pathogen collected from 75 pepper fields in Korea from 1995 to 1998. At the concentration of metalaxyl $2{\mu}g/ml$, inhibition rate of mycelial growth of P. capsici isolates was 68.2% in average compared to control, and 28.6% isolates in average were estimated as resistance to the chemical. Isolates of field unit with a single mating type revealed similar level of sensitivity to metalaxyl and showed sensitive or resistant in most field units. However, isolates of field units with both mating types revealed diverse sensitivity level to the chemical and various occurrence ratio of metalaxyl sensitive : resistant in each field unit. Results indicated that different levels of metalaxyl sensitivity of P. capsici population in Korea seem to be closely related with occurrence ratio of A1 : A2 mating type of each field.

• Journal of Navigation and Port Research
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• v.38 no.4
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• pp.335-341
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• 2014

Faced with global agenda of greenhouse abatement program including regulations and $CO_2$ emission trading scheme, shipping companies are enforced to a high level of efficiency in fuel consumption. Accordingly shipbuilding companies worldwide are required to develop fuel-efficient ships which otherwise traditionally consume a great amount of fossil fuels. In this dissertation, relevant to the improvement of fuel efficiency for commercial ships, design methodology through the numerical simulations are intensively described. This work consists of derivation of effective hydrodynamic design practice based on the application of longitudinal grooves to effectively improve the pressure distribution around ship hull. The primary objective of the present study is to improve ship resistance performance using longitudinal grooves which originate from long strips on the abdomen of humpback whale. Several groove shapes have been extensively investigated and the proposed shape efficiently controlled the variation of pressure distributions acting on the hull surface.

• Journal of the Korean Geosynthetics Society
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• v.4 no.2
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• pp.39-45
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• 2005

New concept called the pullout resistance angle has been used to express the friction, cohesion and passive resistance by pullout test at geosynthetics reinforced soil. And also in order to calculate the pullout area, the distribution area method has been used, which is a method of using the curve of tensile force exerted in geogrid. The distribution area ratio showed nearly the same result in the two kind of soils, the granite soil and the standard soil. The pullout resistance angle showed the greater value than friction angle of soil in case of low confining stress of $0.2kg/cm^2$, while it showed the smaller angle than friction of soil in case of high confining stress of $0.8kg/cm^2$.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.114-120
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• 2006

The main purpose of this study is to apply spatial analysis using semivariograms to small-loop electromagnetic survey data to assess the extent of seawater intrusion in an experimental watershed. To indicate the extent of seawater intrusion over the study area, vertical electrical soundings at 33 points and electrical conductivity logging in two wells were conducted. From the correlation between resistivities obtained by inversion and the depth of the aquifer at the two wells, the region of seawater intrusion was identified and demonstrated by electrical conductivity logging results obtained over two years. To measure the variation of apparent conductivity with depth, an electromagnetic survey in six frequency bands was adopted. Apparent conductivity mapping with spatial analysis using semivariograms is an effective technique for identifying the region of seawater intrusion at shallow depth.