• Nuclear Engineering and Technology
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• v.27 no.2
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• pp.234-247
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• 1995

Trace elements in airborne particulates were analyzed by instrumental neutron activation analysis (INAA) under the optimum analytical condition. Neutron irradiation for sample was done at the irradiation hole(neutron flux 1$\times$10$^{13}$ n/$\textrm{cm}^2$.s) of TRIGA MARK-III research reactor in the Korea Atomic Energy Research Institute. For the verification of the analytical method, NIST SRM-1648 and NIES CRM No.8 ore chosen and analyzed. The accuracy and precision of the analysis of 40 and 24 trace elements in the samples were compared with the certified and reported values, respectively. The analytical method was found to be reliable enough when the analytical data of NIES sample were compared with those of different counties. In the analytical result of two or both of standard reference materials, relative standard deviation wes within the 15％ except a few elements and the relative error was within the 10％. We used this method to analyze 30 trace elements in airborne particulates collected with the high volume air sampler(PM-10) at too different locations and also confirmed the possibility to use this method as a routine monitoring tool to find out environmental pollution sources.

• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.16-25
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• 2007

In a companion paper, a rational mechanical model to predict the entire behavior of point-loaded RC slender beams (a/d > 2.5) without shear reinforcement was developed. This paper presents the test results of 9 slender shear beams and compares them with analytical results performed by the proposed model. They are grouped by two parameters, which are shear span ratio and concrete strength. Three kinds of concrete strength the 26.5, 39.2, and 58.8 MPa were included as a major experimental parameter together with different shear span ratios ranging from 3 to 6 depending on the test series. Tests were set up as a traditional 3 point bending test. Various measurements were taken to monitor abrupt shear failure. Test results were not only compared with analytical results from the proposed model, but also other formulas, to consider the various aspects of shear failure such as kinematical conditions or shear capacity. Finally, a review of the proposed model is presented with respect to the shear transfer mechanisms and the effect of test parameters. Results show that several assumptions and proposals adopted in the proposed model are rational and reasonable.

• Computers and Concrete
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• v.27 no.2
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• pp.153-162
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• 2021

This paper aims to simulate the isotropic elastic damage theory of Liu Jun (2012) using the self-programmed UMAT subroutine in the interface of ABAQUS. Liu Jun (2012)'s method based on the mechanic theory can not be used interactively with the currently commonly used finite element software ABAQUS. The advantage of this method in the paper is that it can interact with ABAQUS and provide a constitutive program framework that can be modified according to user need. The model retains the two scalar damage variables and the corresponding two energy dissipation mechanisms and damage criteria for considering the tensile and compressive asymmetry of concrete. Taking C45 concrete as an example, the relevant damage evolution parameters of its tensile and compressive constitutive model are given. The study demonstrates that the uniaxial tensile stress calculated by the subroutine is almost the same as the Chinese Concrete Design Specification (GB50010) before the peak stress, but ends soon after the peak stress. The stress-strain curve of uniaxial compression calculated by the subroutine is in good agreement with the peak stress in Chinese Concrete Design Specification (GB50010), but there is a certain deviation in the descending stage. In addition, this paper uses the newly compiled subroutine to simulate the shear bearing capacity of the shear key in a new structural system, namely the open-web sandwich slab. The results show that the damage constitutive subroutine has certain reliability.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.93-116
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• 2005

SPT-Uphole tomography method was introducedand verified in this paper. In SPT-Uphole method, SPT (Standard Penetration Test) which is common in site investigation, was used as a source and several surface geophones in line were used as receivers. Shear wave velocity (Vs) distribution map which has triangular shape around the boring point can be obtained by tomography inversion. The factors for obtaining reliable result of SPT-Uphole tomography are exact travel time information and accurate inversion method. To establish of the SPT-Uphole tomography procedure, the most reliable method for obtaining exact travel time information and verification of tomography inversion method were studied by using theoretical travel time information and finite element method (FEM) analysis. finally, SPT-Uphole tomography method was performed at the weathered soil site in Kimje. By comparing with several boring data including SPT-N value, feasibility of this method was verified in the field.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11a
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• pp.237-246
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• 2005

A tip-over test of the 1/3 scale model is conducted to verify the tip-oner analysis of a dry concrete storage cask under a hypothetical accident condition. The tip-oner analysis is executed using the velocity at each point which are determined from the initial angular velocity as the initial conditions of the model just before the impact. To confirm the structural integrity of the canister of a dry concrete storage cask, the non-detective testing such as Liquid Penetrants testing and Ultrasonic Testing are conducted. The strains and tile accelerations acquired by the tip-over test are compared with those by the analysis to verify the tip-over analysis. The lid of a storage calk are plastically deformed at the impact point. Liquid

• Journal of the Korean GEO-environmental Society
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• v.22 no.3
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• pp.37-43
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• 2021

This study aimed to calculate the amount of change in soil carbon due to changes in land cover. Among the various soil carbon models, the InVEST Carbon Storage and Sequestration module was used. LULC is one of the leading factors affecting soil carbon. Therefore, this study compared the total amount of soil carbon due to changes in LULC in 2000 and 2010 across the Republic of Korea, and calculated the changes in each administrative district (city). Changes in LULC in Korea were mainly due to the increase in developed and dry areas and the decrease in grassland, indicating changes in soil carbon. The total amount of soil carbon changes in South Korea has been reduced by 11.48 (millions) in 10 years. The amount of soil carbon by administrative region decreased in most cities and provinces, but Jeju Island, in exception, showed an increase in soil carbon. Among the cities and provinces except Jeju Island, Seoul showed the smallest decrease, with a decrease of 0.033 (million t). On the contrary, the largest number of attempts to decrease was to Gyeongsangbuk-do, which saw a total decrease of 2.893 (million t). Jeju Island is the only soil carbon-increasing area with an increase of 0.547 (millions) and the agricultural area has increased 2.1 times in 10 years. In the case of soil carbon, the construction of ground observation data at the national unit is insufficient, and verification will need to be carried out through linked analysis using multiple models in the future.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.589-597
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• 2019

The purpose of this study was improve accuracy the IOPs inversion model(IOPs-IM) developed in 2016 for phycocyanin(PC) concentration estimation in the Nakdong River. Additionally, two optimum models were developed and evaluated with 2017 measurement field spectral data for the Geum River and the Yeongsan River. The used measurement data for IOPs-IM analyzation was randomly classified as training and verification materials at the ratio of 2:1 in all data sets. Using the training data set from 2015-2017, accuracy results of the IOPs-IM generally improved for the Nakdong River. The RMSE(Root Mean Square Error) decreased by 14 % compared to 2016. For the GeumRiver, the results of the IOPs-IM were suitable, except for some point results in 2016. Results of the IOPs-IM in the Yeongsan River followed the overall 1:1 line and MAE(Mean Absolute Error) was lower than other rivers. But the RMSE and MAE values were higher. As a result of applying the validation data to the IOPs-IM, the accuracy of the Nakdong River was reduced to RMSE 17.7 % and MRE 16.4 %, respectively compared with 2016. However, the MRE(Mean Relative Error) was estimated to be higher by 400 % in the Geum River, and the RMSE was more than 100 mg/㎥ of the Yeongsan River. Therefore, it is necessary to get the continuously data with various sections of each river for obtain objective and reliable results and the models should be improved.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.12
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• pp.689-695
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• 2015

A biofilm filtration for the removal of gaseous pollutants has been recognized as a process with a complex interaction between the gas flow characteristics and the process operating variables. This study aims to develop an one dimensional dynamic numerical model which can be utilized as a tool for the analysis of biofilm filtration process operated in plug flow mode. Since, in a plug flow system, minor environmental changes in a gaseous unit process cause a drastic change in reaction and the interaction between the pollutants is an influencing factor, plug flow system was generalized in developing the model. For facilitation of the model development, dispersion was simplified based on the principles of material balance. Several reactions such as competition, escalation, and control between the pollutants were included in the model. The applicability of the developed model was evaluated by taking the calibration and verification steps on the experimental data performed for the removal of BTX at both low and high flow concentration. The model demonstrated a correlation coefficient ($R^2$) greater than 0.79 under all the experimental conditions except for the case of toluene at high flow condition, which suggested that this model could be used for the generalized gaseous biofilm plug flow filtration system. In addition, this model could be a useful tool in analyzing the design parameters and evaluating process efficiency of the experiments with substantial amount of complexity and diversity.

• Journal of the Korea Safety Management & Science
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• v.11 no.4
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• pp.201-211
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• 2009

The types and quantities of Hazmat and Hazmat transportation are gradually increasing, keeping pace with industrialization and urbanization. At present the safety management for Hazmat transportation only considers reducing accident probability, but even when an accident involving Hazmat-carrying vehicles occurs, that is not regarded as a Hazmat-related accident if the Hazmats do not leak out from the containers carrying them. Thus the methods to reduce risk (Risk=Probability$\times$Consequence) have to be developed by incorporating accident probability and consequence. By using Geographic Information System (GIS), a technical method is invented and is automatically able to evaluate the consequence by different types of Hazmat. Thus this study analyzed the degree of risk on the links classified by the Hazmat transport pathways. In order to mitigate the degree of risk, a method of 7-step risk management on Hazmat transportation in railway industries can be suggested. (1st step: building up GIS DB, 2nd step: calculating accident probability on each link, 3rd step: calculating consequence by Hazmat types, 4th step: determination of risk, 5th step: analysis of alternative plans for mitigating the risk, 6th: measure of effectiveness against each alternative, and 7th step: action plans to be weak probability and consequence by the range recommended from ALARP). In conclusion, those 7 steps are used as a standardization method of optimum transportation routing. And to increase the efficiency of optimum transportation routing, optional route can be revise by verification.

• The Journal of Engineering Geology
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• v.24 no.3
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• pp.343-351
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• 2014

Tunnel face mapping plays an important role in risk analysis and infrastructure support decisions during tunnel construction. In this study, a digital mapping system using a mobile device is employed instead of existing face-mapping methods that rely upon face mapping sheets. The mobile device is then connected to the main server in the field, where a tunnel-specific database is compiled automatically. This information provides real-time feedback on the tunnel face to construction personnel and engineers, thus allowing for rapid assessment of tunnel face stability and infrastructure needs. The Douglas-Peucker algorithm, among others, is employed to resolve problems arising from the detailed mapping and speed problem by data accumulation. This system is expected to raise program optimization through field verification and additional functional improvements.