• The Journal of Engineering Geology
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• v.30 no.1
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• pp.31-42
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• 2020

Electrical resistivity and downhole seismic surveys were conducted together with bore investigations and well-logging to examine subsurface structures in small-scale landslides at Sinjindo-ri, Geunheung-myeon, Taean-gun, Chungcheongnam-do, Republic of Korea in 2014. On the basis of the low N-values at depths of 5~7 m in borehole BH-2, downhole seismic and electrical dipole-dipole resistivity surveys were performed to delineate geological weak zones. The low-resistivity zones (<150 Ω·m) measure ~8 m in thickness and show a close depth correspondence to weathered soils consisting mainly of silty clays as identified from the bore investigations and well-logging data. Compared with weak zones in borehole BH-1, weak zones in BH-2 are characterized by lower densities (1.6~1.8 g/㎤) and resistivities (<150 Ω·m) and greater variation in Poisson's ratio. These observations can be explained by the presence of wet silty clays rich in weathered soil material that have resulted from heavy rainfall and rises in groundwater level. Downslope movements are probably caused by the sliding of wet clay that acts to reduce the strength of the weathered soil.

• Journal of radiological science and technology
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• v.25 no.1
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• pp.63-71
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• 2002

The aim of this study Is to develop a simple and fast method which computes in-vivo doses from transmission doses measured doting patient treatment using an ionization chamber. Energy fluence and the dose that reach the chamber positioned behind the patient is modified by three factors: patient attenuation, inverse square attenuation. and scattering. We adopted a straightforward empirical approach using a phantom transmission factor (PTF) which accounts for the contribution from all three factors. It was done as follows. First of all, the phantom transmission factor was measured as a simple ratio of the chamber reading measured with and without a homogeneous phantom in the radiation beam according to various field sizes($r_p$), phantom to chamber distance($d_g$) and phantom thickness($T_p$). Secondly, we used the concept of effective field to the cases with inhomogeneous phantom (patients) and irregular fields. The effective field size is calculated by finding the field size that produces the same value of PTF to that for the irregular field and/or inhomogeneous phantom. The hypothesis is that the presence of inhomogeneity and irregular field can be accommodated to a certain extent by altering the field size. Thirdly, the center dose at the prescription depth can be computed using the new TMR($r_{p,eff}$) and Sp($r_{p,eff}$) from the effective field size. After that, when TMR(d, $r_{p,eff}$) and SP($r_{p,eff}$) are acquired. the tumor dose is as follows. $$D_{center}=D_t/PTF(d_g,\;T_p){\times}(\frac{SCD}{SAD})^2{\times}BSF(r_o){\times}S_p(r_{p,eff}){\times}TMR(d,\;r_{p,eff})$$ To make certain the accuracy of this method, we checked the accuracy for the following four cases; in cases of regular or irregular field size, inhomogeneous material included, any errors made and clinical situation. The errors were within 2.3% for regular field size, 3.0% irregular field size, 2.4% when inhomogeneous material was included in the phantom, 3.8% for 6 MV when the error was made purposely, 4.7% for 10 MV and 1.8% for the measurement of a patient in clinic. It is considered that this methode can make the quality control for dose at the time of radiation therapy because it is non-invasive that makes possible to measure the doses whenever a patient is given a therapy as well as eliminates the problem for entrance or exit dose measurement.

• Journal of Korean Society of Steel Construction
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• v.18 no.6
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• pp.793-804
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• 2006

Various PSC and steel-concrete composite railway bridges are being developed for short-medium spans with structural and economic efficiency. According to the design concept, the prestressed composite girder bridge has the advantages of being lightweight and having low girder depth, with the capacity for long spans. However, the dynamic behavior under a passing train is one of the critical issues concerning these railway bridges designed with more flexibility. Therefore, it is very important to evaluate the modal parameters before performing dynamic analyses. In this paper, real-scale prestressed composite girders were fabricated as a test model and modal testing was carried out to evaluate modal parameters including natural frequency and modal damping ratio. During the modal testing, a digitally controlled vibration exciter as well as an impact hammer was applied to obtain frequency-response functions, and the modal parameters were also evaluated after the fracture of test models. With application of reliable properties from modal tests, the estimation of dynamic performances of prestressed composite girder railway bridges can be obtained from various parametric studies on dynamic behavior under the passage of a moving train.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.121-121
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• 2004

The groundwater in the Pocheon area occurs from both a fractured bedrock aquifer in igneous and metamorphic rocks and an alluvial aquifer with a thickness of <50 m, and forms a major source of domestic and agricultural water supply. In this study, we performed a hydrogeochemical study in order to identify the control of geochemical processes on groundwater quality. For this study, groundwater level and physicochemical parameters (EC, Eh, pH, alkalinity) were monitored once a month from a total of 150 groundwater wells between June 2003 to August 2004. A total of 153 water samples (13 surface water, 66 alluvial groundwater, 74 bedrock groundwater) were also collected and analyzed in February 2004. Groundwater chemistry in the study area is very complex, depending on a number of major factors such as geology, degree of chemical weathering, and quality of recharge water. Hydrochemical reactions such as the leaching of surficial and near-solace soil salts, dissolution of calcite, cation exchange, and weathering of silicate minerals are proposed to explain the chemistry of natural groundwater. Alluvial groundwaters locally have very high TDS concentrations, which are characterized by their chloride(nitrate)-sulfate-bicabonate facies and low Na/Cl ratio. Their grondwater levels are highly fluctuated according to rainfall event. We suggest that high nitrate content and salinity in such alluvial groundwaters originates from the local recharge of sewage effluents and/or fertilizers. Likewise, high concentrations of nitrate were also locally observed in some bedrock groundwaters, suggesting their effect of anthropogenic contamination. This is possibly due to the bypass flow taking place through macropores. Tile degree of the weathering of silicate minerals seems to be a major control of the distribution of major cations (sodium, calcium, magnesium, potassium) in bedrock groundwaters, which show a general increase with increasing depth of wells. Thermodynamic interpretation of groundwater chemistry shows that the groundwater in the study area is in chemical equilibrium with kaolinite and Na-montmorillonite, which indicates that weathering of plagioclase to those minerals is a major control of hydrochemistry of bedrock groundwater. The interpretation of the molar ratios among major ions, as well as the mass balance calculation, also indicates the role of both dissolution/precipitation of calcite and Ca-Na cationic exchange as bedrock groundwaters evolves progressively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.1
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• pp.42-46
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• 2017

$SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ phosphorescent phosphors were synthesized by skull melting method. The molar ratio of oxides in the phosphors synthesized by the skull melting technique was $SrCO_3$ : $Al(OH)_3$ : $Eu_2O_3$ : $Dy_2O_3$= 1 : 2 : 0.015 : 0.02. Crystal structure and surface morphology were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Optical properties of the synthesized $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ were measured by photoluminescence (PL) spectrometer for in-depth study on the excitation, emission and afterglow properties. From the PL measurements, it was found that excitation occurred in the wavelength range from 300 to 420 nm with peak position at 360 nm. The emission spectrum showed a broad curve in the wavelength from 450 to 600 nm with peak position at 530 nm. $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ phosphors exhibited afterglow properties with emission that lasted for a long period.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.615-623
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• 2015

The previous strut-and-tie models (STMs) to evaluate the shear strength of squat shear walls with aspect ratio less than 2.0 do not consider the axial load transfer of concrete strut and individual shear transfer contribution of horizontal and vertical shear reinforcing bars in the web. To overcome the limitation of the existing models, a simple STM was established based on the crack band theory of concrete fracture mechanics. The equivalent effective width of concrete strut having a stress relief strip was determined from the neutral axis depth and effective factor of concrete strength. The shear transfer mechanism of shear reinforcement at the extended crack band zone was calculated from an internally statically indeterminate truss system. The shear transfer capacity of concrete strut and shear reinforcement was then driven using the energy equilibrium in the stress relief strip and crack band zone. The shear strength predictions of squat shear walls evaluated from the current models are in better agreement with 150 test results than those determined from STMs proposed by Siao and Hwang et al. Furthermore, the proposed STM gives consistent agreement with the observed trend of the shear strength of shear walls against different parameters.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.683-691
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• 2013

Failure behaviour of deep beams is largely depend on shear span to effective depth ratio(a/d). For deep beams with $a/d{\leq}1.0$, the diagonal splitting of the web and local crushing of concrete near applied loads or supports is the most common failure mode. If the beam contains sufficient web reinforcement, area of local crushing will be increased while area of diagonal splitting is decreased. When web reinforcement above purpose, web should be reinforced both in the horizontal and vertical directions or be reinforced in perpendicular direction to diagonal cracks. For deep beams with 1.0${\leq}2.5$, the increment of shear strength by the horizontal web reinforcement are hardly expected unless amount of main bars very small that the main bars should be reached yielding state when shear failure occurs. In contrast, the vertical web reinforcement prevent the beam from being transferred to tied arch mechanism, and as a result th shear strength of beam increase. In this study, formulas based on upper bound theorem of plastic theory are proposed to predict the shear strength of reinforced concrete deep beams with $a/d{\leq}1.0$. Comparisons with other experiment results are performed, and good agreement between measured and predicted value by proposed formulas is obtained.

• Journal of the Korean Society of Costume
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• v.62 no.8
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• pp.1-18
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• 2012

The purpose of the study was to offer in-depth understanding of the women's wear research trend in South Korea and thus to provide insights from the findings throughout the study to set appropriate directions for further development of women's wear related researches in the clothing and textile study area. The study considered research papers published by the 6 major apparel related journals listed on the KCI(Korea Citation Index) i.e. journals of the Korean Society of Clothing and Textiles(KSCT), the Korean Society of Costume(KSC), the Costume Culture Association (CCA), the Korean Society of Fashion Business(KSFB), the Korean Home Economics Association (KHEA) and the Korean Society for Clothing Industry(KSCI). A total of 380 research papers that were related with women's wear published from 2001 to 2010 were selected for the study and analyzed in the form of descriptive statistics using the SPSS Software ver. 18.0. The analysis was categorized according to the journals, years and research theme. The research themes were divided into various categories such as, clothing construction, textile science, fashion aesthetics and design, costume history and culture, apparel psychology and fashion marketing. The results derived from the research were: (1) the ratio of the research papers on the women's wear to the total papers published from 2001 to 2010 by the 6 subject journals was 380 to 6,815, i.e. 5.6% of the total papers; (2) journal of KSCT published the most women's wear research papers (N=149, 39.2%) and then the rest in order were the journal of CCA (N=69, 18.2%), the journal of KSC (N=68, 17.9%), the journal of KSFB (N=52, 13.7%), the journal of KHEA (N=39, 10.3%) and the journal of KSCI (N=3, 0.7%); (3) the proportions of the research themes for the women's wear study were in the order of the case study in marketing (N=135, 35.5%), body measurements and sizing systems in clothing construction (N=88, 23.2%), fashion design and aesthetics (N=83, 21.8%), pattern-making (N=63, 16.6%), and color study (N=11, 2.9%) and so on.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.10
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• pp.1660-1669
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• 2018

Objective: This study was conducted to evaluate the effect of probiotics (Bacillus subtilis and Enterococcus faecium) and xylo-oligosaccharide (XOS) supplementation on growth performance, nutrient digestibility, serum profiles, intestinal health, fecal microbiota and noxious gas emission in weanling pigs. Methods: A total of 240 weanling pigs ([Yorkshire${\times}$Landrace]${\times}$Duroc) with an average body weight (BW) of $6.3{\pm}0.15kg$ were used in this 28-day trial. Pigs were randomly allocated in 1 of the following 4 dietary treatments in a $2{\times}2$ factorial arrangement with 2 levels of probiotics (0 and 500 mg/kg probiotics) and XOS (0 and 200 mg/kg XOS) based on the BW and sex. Results: Administration of probiotics or XOS improved average daily gain (p<0.05) during 0 to 14 d and the overall period, while pigs that were treated with XOS had a greater average daily gain and feed efficiency (p<0.05) compared with unsupplemented treatments throughout 15 to 28 d and the whole experiment. Either probiotics or XOS treatments increased the apparent total tract digestibility of nutrients (p<0.05) during 0 to 14 d. No effects on serum profiles were observed among treatments. The XOS increased villus height: crypt depth ratio in jejunum (p<0.05). The supplementation of probiotics (500 mg/kg) or XOS (200 mg/kg) alone improved the apparent total tract digestibility of dry matter, nitrogen and gross energy on d 14, the activity of trypsin and decreased fecal NH3 concentration (p<0.05). Administration of XOS decreased fecal Escherichia coli counts (p<0.05), while increased lactobacilli (p<0.05) on d 14. There was no interaction between dietary supplementation of probiotics and XOS. Conclusion: Inclusion of XOS at 200 mg/kg or probiotics (Bacillus subtilis and Enterococcus faecium) at 500 mg/kg in diets containing no antibiotics significantly improved the growth performance of weanling pigs. Once XOS is supplemented, further providing of probiotics is not needed since it exerts little additional effects.

• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.311-318
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• 1997

Chemical properties of soil(N, P, K, Ca, Na, Mg, CEC, and pH) were studied after annual additions of $NH_4NO_3$(336kg/ha N), treble superphosphate(112kg/ha P), and KCl(224kg/ha K) fertilizers in a willow(Salix spp.) bioenergy plantation. Soil samples were collected from November through December 1992 from previously established the fertilized and non-fertilized willow plantation at Tully, New York, U.S.A. in 1987. Total fertilizer additions from 1987 through 1991 were 1,680kg/ha N and 560kg/ha P and 1.120kg/ha K. Fertilization with N, P, and K resulted in no difference in total soil N content between the fertilized and non-fertilized plots, increased soil P and K, decreased base cations ($Ca^{2+}$ and $Mg^{2+}$) and soil pH, and increased soil pH with soil depth. Strong positive correlations of soil carbon to soil N, Ca, Mg, and CEC were noted. Soil C/N ratio in the study plots ranged from 9.6 to 11.2 for all treatment combinations. Significant differences in soil P, K, Ca, and pH between the fertilized and non-fertilized plots indicate that fertilization had changed chemical properties of soil in this fertilizer trial.