• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.2
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• pp.13-23
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• 2016

Many traffic centers are highly hesitant in employing existing Automatic Incident Detection Algorithms due to high false alarm rate, low detection rate, and enormous effort taken in maintaining algorithm parameters, together with complex algorithm structure and filtering/smoothing process. Concerns grow over the situation particularly in Freeway Incident Management Area This study proposes a new algorithm and introduces a novel concept, the Displaced Flow Index (DiFI) which is similar to a product of relative speed and relative occupancy for every execution period. The algorithm structure is very simple, also easy to understand with minimum parameters, and could use raw data without any additional pre-processing. To evaluate the performance of the DiFI algorithm, validation test on the algorithm has been conducted using detector data taken from Naebu Expressway in Seoul and following transferability tests with Gyeongbu Expressway detector data. Performance test has utilized many indices such as DR, FAR, MTTD (Mean Time To Detect), CR (Classification Rate), CI (Composite Index) and PI (Performance Index). It was found that the DR is up to 100%, the MTTD is a little over 1.0 minutes, and the FAR is as low as 2.99%. This newly designed algorithm seems promising and outperformed SAO and most popular AIDAs such as APID and DELOS, and showed the best performance in every category.

• Korean Journal of Construction Engineering and Management
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• v.14 no.1
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• pp.101-114
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• 2013

This paper presents the findings relative to the influence factors on the safety of construction worker's actions. It identifies the factors which are involved in the safety behavior exercised by construction worker. They are compiled from existing studies that investigates the factors relative to the safety behavior. This study finds some factors which have powerful direct effects on safety behavior of construction workers. In addition, a model which defines the relationship between the factors and the behaviors of workers is established to analyze the effects. This study contributes to designe a theoretical model that shows workers' behaviors and analyzes the effects attributed to these factors: i.e., organizational commitment, stress reaction, safety motivation, safety knowledge, and safety climate. Survey questionaries are administered to the workers on the construction job sites located in Daegu metropolitan city. using SPSS18.0 and AMOS18.0, Exploratory Factor Analysis, Cronbach's alpha, Confirmatory Factor Analysis, Structural Equations Model analysis were performed. The research findings are as follows; The communication and educational training have the direct effect on the safety behavior. The factors of the safety climate constraints and/or contributes to the safety motivation, safety knowledge, and organizational commitment.

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.361-365
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• 2007

The precipitation reaction of some rare earth chlorides ($Ce/Nd/GdCl_3$) in a LiCl-KCl molten salt has been carried out by reaction with oxygen. Identification of rare earth precipitates by reaction with oxygen and effects of oxygen sparging time (max. 420 min) and molten salt temperature ($450{\sim}750^{\circ}C$) on conversion were investigated. In this study, regardless of the oxygen sparging time and the molten salt temperature, oxychlorides (REOCl) for $NdCl_3$ and $GdCl_3$, and an oxide ($REO_2$) for $CeCl_3$ are formed as a precipitate, which are identical with the estimation results of Gibbs free energy of reaction (${\Delta}G_r$). The conversion of rare-earth chlorides into insoluble precipitates was described by using a conversion ratio. The conversion ratio increased exponentially with the oxygen sparging time and finally showed asymptotic value, over 0.999 at $750^{\circ}C$ of the molten salt temperature and over 300 min of sparging time conditions. The conversion ratios were increased with the molten salt temperature. In case of $CeCl_3$, when the sparging time exceed 60 min, the values of the conversion ratio were nearly constant over 0.999 in all experimental temperature conditions.

• Geotechnical Engineering
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• v.5 no.1
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• pp.7-18
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• 1989

In pile load tests on end bearing piles, generally, it is not possible to continue loading to the ultimate load. Thus, the concept of yield load has been introduced for determining design loads Iron the pile load test records. The conventional rules to determine the yield load were not available for evaluation on pile load test records obtained in 6 fields nearby westers 8r Southern Coasts in Korea. A new rule 9.as presented to determine easily the yield load, based on investigations on the pile load test records. The yield load of piles is determined at the infiection point on semi-logarithmic coordinates (P-logS), in which load is plotted in normal scale and settlement is plotted in logarithmic scale. This method may not only save much costs and times but also present safe luorking circumstances for pile load tests in field. It was found that the yield load represented the elastic limit of the pile load-settlement behalf.iota. The ultimate load, which is given at 25.4mm settlement on pile head, was 1.5 times of the yield load. The allowable long-term and short-term load capacities were, respectively, 50% and 75% of the yield load. The safety factors to get the allowable pile capacity were obtained as 2.0~4.0 for the equations to predict the static pile capacity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.68-75
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• 2021

This study performed simulating water absorption in various pre-cracked concretes. 2D-Finite Element Analysis (2D-FEA) model was developed based on experimental results on the amount of absorbed water in concrete with the exposure time. Results from the 2D-FEA showed that both crack width and crack depth strongly affect the amount of absorbed water in cracked concrete. In addition, water absorption rate is introduced and a predictive equation is suggested to estimate the rate in order to quantify the amount of absorbed water in cracked concrete. It was confirmed that water absorption in concrete having less than 150 mm crack depth was dominated as a main transport factor regardless of crack width. Therefore, considering that steel corrosion caused by chlorides dissolved in water mainly occurs in reinforced concrete structures, it is necessary that crack depth as well as crack width should be investigated in reinforced concrete structures at the time of field-inspection.

• Journal of the Korean Geotechnical Society
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• v.38 no.5
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• pp.5-17
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• 2022

A pile is a type of medium for constructing superstructures in weak geotechnical conditions. A pretensioned spun high-strength concrete (PHC) pile is composed of high-strength concrete with a specified strength greater than 80 MPa. Therefore, it has advantages in resistance to axial and bending moments and quality control and management since it is manufactured in a factory. However, the skin friction of a pile, which accounts for a large portion of the pile bearing capacity, is only approximated using empirical equations or standard penetration test (SPT) N-values. Particularly, there are some poor research results on the pile-soil interface under the seismic loads in Korea. Additionally, some studies do not consider geoenvironmental elements, such as groundwater pH values. This study performs sets of cyclic simple shear tests using submerged concrete specimens for 1 month to consider pH values of groundwater and clay specimens composed of kaolinite to generate a pile-soil interface. 0.2 and 0.4 MPa of normal stress conditions are considered in the case of pH values. The disturbed state concept is employed to express the dynamic behavior of the interface, and the disturbed function parameters are newly suggested. Consequently, the largest disturbance increase under basic conditions is observed, and an early approach to the failure under low normal stress conditions is presented. The disturbance function parameters are also suggested to express this disposition quantitatively.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.349-355
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• 2023

This study attempted to investigate the effect of competitive anxiety on injury psychology according to the athletic career of tennis athletes at Chinese universities. To study the method, 208 athletes enrolled in a four-year university (0 university, 0 university) located in A City, Hanam Province, were surveyed for a total of three weeks from the end of January to the beginning of February 2023. To verify the research model, frequency analysis, exploratory factor analysis, reliability analysis, and correlation analysis were conducted using SPSS Statistics 25. And independent sample t-test and one-way ANOVA were conducted to find out the differences in variables according to general characteristics, and multiple regression analysis was conducted to verify hypotheses through the concept of measurement. As a result of the study, first, it was found that there was a significant difference in the athletic career of tennis athletes at West China University. Second, the non-standardized coefficient of competition anxiety was found to have a positive (+) effect on exercise weaponry. Third, the non-standardized coefficient of competition anxiety was found to have a positive (+) effect on anxiety and anxiety. Therefore, it was found that other competitive anxiety in the exercise career had an effect on injury psychology. Since competition anxiety according to the athletic career of tennis athletes at Chinese universities affects injury psychology, it suggests that a psychological program that can control competition anxiety and injury psychology of athletes should be developed and introduced to athletes.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.1
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• pp.1-11
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• 2010

The purpose of this paper is to evaluate supply factors of urban parks to answer the research question: What are the causal effects of supply factors of urban parks on visitor satisfaction? After reviewing the literature and the Korean park planning process, we constructed a conceptual framework and have formulated the hypothesis of this research. We had obtained data through a questionnaire, which surveyed 452 visitors at 8 urban parks in Daegu Metropolitan City in 2008, based on a stratified sampling method. After the elimination of 96 unsuitable samples, we have analyzed the data using descriptive statistical methods, Pearson's correlation analysis and a path analysis method. We have found that: 1) While the direct and indirect effect of accessibility(ACC) on visitor satisfaction(VS) turned out to be 0.184 and 0.220, respectively, the indirect effect of information(IFM) and promotion(PRM) on VS turned out to be 0.101 and 0.177, respectively. 2) While the direct and indirect effect of service(SVR) on VS turned out to be 0.130 and 0.236, respectively, the direct effect of ACC turned out to be 0.698. 3) While the direct effect of ACC, SVR and attraction(ATT) on VS turned out to be 0.184, 0.130 and 0.698, respectively, composing 67.96% of causal effect, the indirect effect of ACC, IFM, PRM and SVR on VS turned out to be 0.220, 0.101, 0.177 and 0.236, respectively, composing 42.04% of causal effect. 4) The magnitude of causal effect of supply factors on VS turned out to be ATT(39.98%), ACC(23.14%), SVR(20.96%), PRM(10.14%) and IFM(5.78%) in order, and 5) the causal effect of external supply factors of ACC, IFM and PRM compose 39.06% of the causal effect while that of the internal supply factors of SVR and ATT is 69.94%. The research results suggest that: 1) Planning for park marketing strategy and remedial directions for existing urban parks, in order to increase visitor satisfaction, be focused on IFM and PRM, especially. 2) The research approach and path analysis method adopted by this research be valid and highly useful for planning and evaluation of other recreation areas. It is recommended that: 1) Structural Equation Model on supply factors of urban parks be established in the future. 2) Evaluation of supply factors by type of urban park be performed.

• Magazine of the Korea Concrete Institute
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• v.7 no.3
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• pp.139-148
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• 1995

The test results from three one fourth scale models using high strength Reinforced Concrete $f_x=704\;kg/cm^2,\;f_y=5.830\;kg/cm^2$ are presented. Such specimens are considered to represent the critical 3 storics of 60-story tall building of a structural wall system in area of high seismicity respectively. They are tested under inplane vertical and horizontal loading. The main varlable is the level of axial stress. The amounts of vertical and horizontal reinforcement are identical for the three walls testcd. The cross-section of all walls is barbell shape. The aspectratio($h_w/I_w$) of test specimen is 1.8. The aim of the study is to investigate the effects of levels of applied axial stresses on the inelastic behavior of high-strength R /C tall walls. Experimental results of high strength R /C tall walls subjected to axial load and simulated sels rnic loading show that it is possible to insure a ductlle dominant performance by promotmg flex ural yielding of vertical reinforcement and that axial stresses within $O.21f_x$ causes an increase in horizontal load-carrying capacity, initial secant st~ffness characteristics, but an decrease in displacement ductility. energy dissipation index and work damage index of high strength K /C tall walls

• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.687-694
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• 2014

This study established a displacement ductility ratio model for ductile design for the boundary element of shear walls. To determine the curvature distribution along the member length and displacement at the free end of the member, the distributions of strains and internal forces along the shear wall section depth were idealized based on the Bernoulli's principle, strain compatibility condition, and equilibrium condition of forces. The confinement effect at the boundary element, provided by transverse reinforcement, was calculated using the stress-strain relationship of confined concrete proposed by Razvi and Saatcioglu. The curvatures corresponding to the initial yielding moment and 80% of the ultimate state after the peak strength were then conversed into displacement values based on the concept of equivalent hinge length. The derived displacement ductility ratio model was simplified by the regression approach using the comprehensive analytical data obtained from the parametric study. The proposed model is in good agreement with test results, indicating that the mean and standard deviation of the ratios between predictions and experiments are 1.05 and 0.19, respectively. Overall, the proposed model is expected to be available for determining the transverse reinforcement ratio at the boundary element for a targeted displacement ductility ratio.