• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.67-72
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• 2006

Injection of $CO_2$ into underground saline formations, due to their large storage capacity, is probably the most promising approach for the reduction of $CO_2$ emissions into the atmosphere. $CO_2$ storage must be carefully planned and monitored to ensure that the $CO_2$ is safely retained in the formation for periods of at least thousands of years. Seismic methods, particularly for offshore reservoirs, are the primary tool for monitoring the injection process and distribution of $CO_2$ in the reservoir over time provided that reservoir properties are favourable. Seismic methods are equally essential for the characterisation of a potential trap, determining the reservoir properties, and estimating its capacity. Hence, an assessment of the change in seismic response to $CO_2$ storage needs to be carried out at a very early stage. This must be revisited at later stages, to assess potential changes in seismic response arising from changes in fluid properties or mineral composition that may arise from chemical interactions between the host rock and the $CO_2$. Thus, carefully structured modelling of the seismic response changes caused by injection of $CO_2$ into a reservoir over time helps in the design of a long-term monitoring program. For that purpose we have developed a Graphical User Interface (GUI) driven rock physics simulator, designed to model both short and long-term 4D seismic responses to injected $CO_2$. The application incorporates $CO_2$ phase changes, local pressure and temperature changes. chemical reactions and mineral precipitation. By incorporating anisotropic Gassmann equations into the simulator, the seismic response of faults and fractures reactivated by $CO_2$ can also be predicted. We show field examples (potential $CO_2$ sequestration sites offshore and onshore) where we have tested our rock physics simulator. 4D seismic responses are modelled to help design the monitoring program.

• Journal of Environmental Science International
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• v.21 no.2
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• pp.217-231
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• 2012

Hourly concentrations of $PM_1$, $PM_{2.5}$ and $PM_{10}$, were investigated at Gangneung city in the Korean east coast on 0000LST October 26~1800LST October 29, 2003. Before the intrusion of Yellow dust from Gobi Desert, $PM_{10}$($PM_{2.5}$, $PM_1$) concentration was generally low, more or less than 20 (10, 5) ${\mu}g/m^3$, and higher PM concentration was found at 0900LST at the beginning time of office hour and their maximum ones at 1700LST around its ending time. As correlation coefficient of $PM_{10}$ and $PM_{2.5}$($PM_{2.5}$ and $PM_1$, and $PM_{10}$ and $PM_1$) was very high with 0.90(0.99, 0.84), and fractional ratios of $(PM_{10}-PM_{2.5})/PM_{2.5}((PM_{2.5}-PM_1)/PM_1)$ were 1.37~3.39(0.23~0.54), respectively. It implied that local $PM_{10}$ concentration could be greatly affected by particulate matters of sizes larger than $2.5{\mu}m$, and $PM_{2.5}$ concentration could be by particulate matters of sizes smaller than $2.5{\mu}m$. During the dust intrusion, maximum concentration of $PM_{10}$($PM_{2.5}$, $PM_1$) reached 154.57(93.19, 76.05) ${\mu}g/m^3$ with 3.8(3.4, 14.1) times higher concentration than before the dust intrusion. As correlation coefficient of $PM_{10}$ and $PM_{2.5}$(vice verse, $PM_{2.5}$, $PM_1$) was almost perfect high with 0.98(1.00, 0.97) and fractional ratios of $(PM_{10}-PM_{2.5})/PM_{2.5}((PM_{2.5}-PM_1)/PM_1)$ were 0.48~1.25(0.16~0.37), local $PM_{10}$ concentration could be major affected by particulates smaller than both $2.5{\mu}m$ and $1{\mu}m$ (fine particulate), opposite to ones before the dust intrusion. After the ending of dust intrusion, as its coefficient of 0.23(0.81, - 0.36) was very low, except the case of $PM_{2.5}$ and $PM_1$ and $(PM_{10}-PM_{2.5})/PM_{2.5}((PM_{2.5}-PM_1)/PM_1)$ were 1.13~1.91(0.29~1.90), concentrations of coarse particulates larger than $2.5{\mu}m$ greatly contributed to $PM_{10}$ concentration, again. For a whole period, as the correlation coefficients of $PM_{10}$, $PM_{2.5}$, $PM_1$ were very high with 0.94, 1.00 and 0.92, reliable regression equations among PM concentrations were suggested.

• Journal of Korean Society of Forest Science
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• v.70 no.1
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• pp.28-37
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• 1985

In order to estimate breast-height form factors of Pinus thunbergii and Cryptomeria japonica, 8 models based on tree age, diameter at breast height and tree height were suggested and evaluated. It was the following equations that turned out to be most fit for estimating them; for Pinus thunbergii, $F=0.553-4.567\;1/A+71.409\;1/A^2$ ($R^2=0.928$), based on tree age, ($6.727^{**}$) ($14.100^{**}$) $F=0.356+1.774\;1/D-0.770\;1/D^2$ ($R^2=0.944$), based on diameter at breast height, ($15.102^{**}$) ($2.908^{**}$) $F=0.316+1.546\;1/H+0.397\;1/H^2$ ($R^2=0.941$), based on tree height, ($8.380^{**}$) ($3.896^{**}$) for Cryptomeria japonica, $F=0.400+2.348\;1/A+17.053\;1/A^2$ ($R^2=0.889$), based on tree age, ($3.501^{**}$) ($3.298^{**}$) $F=0.353+2.118\;1/D-1.462\;1/D^2$ ($R^2=0.923$), based on diameter at breast height, ($14.873^{**}$) ($3.545^{**}$) $F=0.403+0.427\;1/H+2.843\;1/H^2$ ($R^2=0.887$), based on tree height. ($3.254^{**}$) ($5.742^{**}$) The above estimated breast-height form factors proved to be overestimated for young trees and small diameter trees, and to be underestimated for old trees and large diameter trees, in comparison to generally accepted figure in Korea, that is, the form factor of 0.45.

• Journal of the Korea Concrete Institute
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• v.26 no.5
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• pp.651-660
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• 2014

Structural members using ultra high strength concrete which usually used with steel fiber is designed with guidelines based on several investigation of SF-RPC(steel fiber reinforced reactive powder concrete). However, there are not clear design method yet. Especially, SF-RPC member should be casted with steam(90 degree delicious) and members with SF-RPC usually used with precast members. Although the most important design parameter is development method between SF-RPC and steel reinforcement(rebar), there are no clear design method in the SF-RPC member design guidelines. There are many controversial problems on safety and economy. Therefore, in order to make design more optimum safe design, in this study, we investigated bond stress between steel rebar and SF-RPC according to test. Test results were compared with previously suggested analysis method. Test was carried out with direct pull out test using variables of compressive strength of concrete, concrete cover and inclusion ratio of steel fiber. According to test results, bond stress between steel rebar and SF-RPC increased with increase of compressive strength of concrete and concrete cover. Increasing rate of bond stress were decrease with increase of compressive strength of SF-RPC and concrete cover significantly. 1% volume fraction inclusion of steel fiber increase the bond stress between steel rebar and SF-RPC with two times but 2% volume fraction cannot affect the bond stress significantly. There are no exact or empirical equations for evaluation of SF-RPC bond stress. In order to make safe bond design of SF-RPC precast members, previously suggested analysis method for bond stress by Tepfers were evaluated. This method have shown good agreement with test results, especially for steel fiber reinforced RPC.

• Journal of Korean Society of Forest Science
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• v.84 no.2
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• pp.226-238
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• 1995

This research was conducted to investigate the influential factors of the runoff of water and hillslope erosion caused by the large-scale harvesting operation. It was carried out on harvested sites (13ha) and non-harvested sites(13ha) in Seoul National University Research Forest [(Mt.) Paekunsan], from 1993 to 1994. 1. The amount of runoff of water was increased as the unit of rainfall increases, and the amount of runoff on harvested sites was larger than that of non-harvested sites by 28% in the first year and 24.5% in the second year after harvesting. According to the multiple regression equation for surface runoff, unit and number of rainfall, amount of hillslope erosion and soil bulk density showed statistically significance($R^2$=0.91). 2. The amount of hillslope erosion on harvested sites was larger than that of non-harvested sites by 7 times during the first year of harvesting and 2 times during the second year. 3. The multiple regression equations for hillslope erosion showed that soil bulk density, surface runoff of water and unit of rainfall(these factors were not controllable) had statistically significance($R^2$=0.74). 4. Soil runoff in harvested and non harvested sites were maximum 6.7% and 1% of the amount of hillslope erosion, respectively during the first year of harvesting. And the second year of harvesting soil runoff in harvested and non harvested cites were maximum 5.7% and 1.9%of the amount of hillslope erosion. From the above results, when in planning for timber harvesting, the buffer strip-woods zone must be remained to diminish soil and water runoff and to preserve water quality.

• Progress in Medical Physics
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• v.22 no.3
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• pp.131-139
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• 2011

A method to get a size of the radiation isocenter of linear accelerators using star-shot images was presented and a computer program was developed to automate the method. Accuracy of the method was verified. The developed program was used to measure sizes of the radiation isocenters for a Clinac 21EX (Varian, USA) using data of quality assurance (QA) performed from June 2008 to December 2010. To calculated the size of radiation isocenter, positions of two points on each central ray of the star-shot image were found and the equation of the central ray was determined using the positions of two points. Using the equations of central rays the radius of the minimum circle intersecting all the central rays, which is one half of the size of radiation isocenter, was calculated. The program measured x-intercepts and y-intercepts of the central rays within errors of 0.084 mm and sizes of radiation isocenters within 0.053 mm. All the errors were less than the spatial resolution of star-shot images 0.085 mm. The radiation isocenter sizes of Clinac 21EX were $0.33{\pm}0.27mm$, $0.71{\pm}0.36mm$, $0.50{\pm}0.16mm$ for collimator, gantry and couch respectively. During the measurement period all the measured sizes were less than 2.0 mm and within tolerance. The developed program could calculate the size of radiation isocenters and it would be helpful to routine QA.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.3
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• pp.71-86
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• 1983

Current R.C. retaining wall design is bared on WSD, but the reliability based design method is more rational than the WSD. For this reason, this study proposes a reliability based design criteria for the cantilever retaining wall, which is most common type of retaining wall, and also proposes the theoretical bases of nominal safety factors of stability analysis by introducing the reliability theory. The limit state equations of stability analysis and design of each part of cantilever retaining wall are derived and the uncertainty measuring algorithms of each equation are also derived by MFOSM using Coulomb's coefficient of the active earth pressure and Hansen's bearing capacity formula. The levels of uncertainties corresponding to these algorithms are proposed appropriate values considering our actuality. The target reliability indices (overturning: ${\beta}_0$=4.0, sliding: ${\beta}_0$=3.5, bearing capacity: [${\beta}_0$=3.0, design for flexure: [${\beta}_0$=3.0, design for shear: ${\beta}_0$=3.2) are selected as optimal values considering our practice based on the calibration with the current R.C. retaining wall design safety provisions. Load and resistance factors are measured by using the proposed uncertainties and the selected target reliability indices. Furthermore, a set of nominal safety factors, allowable stresses, and allowable shear stresses are proposed for the current WSD design provisions. It may be asserted that the proposed LRFD reliability based design criteria for the R.C. retaining wall may have to be incorporated into the current R.C. design codes as a design provision corresponding to the USD provisions of the current R.C. design code.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.319-327
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• 2014

Understanding and quantifying of carbon storage in ecosystem is very important factor for predicting change of global carbon cycle under the global climate change. We estimated total ecosystem carbon in Gyeryongsan National Park with naturally well preserved ecosystem in Korea. Vegetation of Gyeryongsan National Park was classified with mainly four communities with Quercus mongolica (1,743.5 ha, 38.0%), Quercus variabilis (1,174.0 ha, 25.6%), Quercus serrata (971.9 ha, 21.2%), Pinus densiflora (695.2 ha, 15.2%). Biomass and soil carbons were calculated from biomass allometric equations based on the DBH and carbon contents of soil and litter collected in quadrat in each community. The tree biomass carbon was in Quercus variabilis ($130.1tCha^{-1}$), Pinus densiflora ($111.1tCha^{-1}$), Quercus mongolica ($76.2tCha^{-1}$), Quercus serrata ($39.0tCha^{-1}$). Soil carbon storage was in Quercus mongolica ($159.7tCha^{-1}$), Quercus serrata ($121.0tCha^{-1}$), Pinus densiflora ($110.5tCha^{-1}$), Quercus variabilis ($90.8tCha^{-1}$). Ecosystem carbon storage was Pinus densiflora ($239.9tCha^{-1}$), Quercus mongolica ($235.9tCha^{-1}$), Quercus variabilis ($226.0tCha^{-1}$), Quercus serrata ($165.9tCha^{-1}$), total amount was $867.7tCha^{-1}$. The area of each vegetation carbon storage was Quercus mongolica ($411,200tCha^{-1}$), Quercus variabilis ($265,300tCha^{-1}$), Pinus densiflora ($166,800tCha^{-1}$), Quercus serrata ($161,200tCha^{-1}$) and the total ecosystem carbon amount estimated $1,045,400tCha^{-1}$ at Gyeryongsan National Park. Theses results indicate that different in naturally well preserved ecosystem.

• Journal of agricultural medicine and community health
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• v.10 no.1
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• pp.42-48
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• 1985

This study was carried out to obtain the basic data for epdemiological survey of hypertension in old population (60 years or more). From May, 1983 to April, 1984, 365 males and 335 females who inhabit in Ko-Chang Gun, Chonbuk Province were investigated for several factors as their socio-econmic status and laboratory examinations with blood pressure, and which factors were analysed by simple correlation and multiple regression analysis. The results are summarized as follows; 1) Sample size of this study is equivalent to 5.2%(male;6.7%, female;4.3%) of population in 60 years or more age group, and the mean age of samples is 70.6${\pm}$5.3 (yr.) in males and 71.4${\pm}$5.3 (yr.) in female (P>0.05). 2) Mean blood pressure of males are 135.9${\pm}$21.3mm Hg in systolic and 85.3${\pm}$13.4mm Hg in diastolic phase and in female, 131.0${\pm}$23.6 mm Hg and 84.1${\pm}$19.9 mm Hg (P < 0.01). Their prevalence rates of hypertension (${\geq}$ 140 mm Hg in systolic, ${\geq}$ 95 mm Hg in diastolic phases) are 33.7% in males, 40.6% in females (P < 0.01). 3) Serum cholesterol levels and other independent variables are revealed in normal ranges, and except to Vervaeck index (89.4${\pm}$5.6 in males, 87.5${\pm}$6.7 in females, p<0.01), other are not significant sexual differences (P>0.05). 4) In the simple correlation analysis, the main factors that affect to blood pressure are serum cholesterol levels (P < 0.05) and Vervaeck index (P < 0.01) in males, age (P <0.05) and Vervaeck index (P <0.01) in females. 5) In multiple regression analysis, prediction equations for blood pressure are calculated as follows; Ysm=-64.55+0.161(X1)+0.124(X2)-0.047(X3)+1.953(X4) Ydm=18.61-0.125(X1)+0.060(X2)+0.032(X3)+0.720(X4) Ysf=-0.22+0.536(X1)+0.134(X2)+0.068(X3+0.788(X4) Yaf=-14.46+0.685(X1)+0.033(X2)+0.176(X3)+0.362(X4) Ysm : Systolic blood pressure in male, Ydm : Diastolic blood pressure in male, Ysf : Systolic blood pressure in female, Ydf : Diastolic blood pressure in female. X1 : Age(year), X2 : Serum cholesterol level (mg%), X3 : Fastin blood sugar (mg% ), X4 : Vervaeck index.

• Korean Journal of Agricultural Science
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• v.11 no.1
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• pp.133-145
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• 1984

To study the effect of foaming agent on the characteristic of mortar, the tests of water-cement ratio and bulk density of mortar were done under the different mixing ratio with G. U and J foaming agents. The results obtained were summarized as follows: 1. At the mixing ratio of 1 : 4 and 0.5% of foaming agent, the highest water-cement ratio was 90% by G, 88.3% by U and 70% by J foaming agent, respectively, being lower than 91.6% of that of cement mortar. 2. At the mixing ratio of 1 : 3 and 3.0% of foaming agent, the water-cement ratio was decreased up to 22.0% by G and 24.1% by U foaming agent, respectively, but it gradually was increased in richer and poorer mixing ratio. At the mixing ratio of 1 : 4 and 3.0% of foaming agent, the water-cement ratio was decreased up to 53.1% by J foaming agent, but it gradually was increased in richer mixing ratio. 3. At the mixing ratio of 1 : 1 and 0.5% of foaming agent, the highest bulk density was $1.981g/cm^3$ by G, $1.863g/cm^3$ by U and $1.149g/cm^3$ by J foaming agent, respectively, being lower than $2.048g/cm^3$ of that of cement mortar. 4. At the mixing ratio of 1 : 2 and 3.0% of foaming agent, the bulk density was decreased up to 20.7% by G, 23.7% by U and 56.5% by J foaming agent, respectively, but it gradually was increased in richer and poorer mixing ratio. 5. The water-cement ratio and bulk density were decreased in more addition of foaming agent, respectively, multiple regression equations of water-cement ratio and bulk density were computed depending on a function of mixing ratios and addition of foaming agents.