• Journal of the Korean Geotechnical Society
• /
• v.29 no.12
• /
• pp.25-34
• /
• 2013

This paper presents the results of a reduced-scale physical model investigation into the behavior of retaining walls subject to cycles of wetting and drying due to rainfall infiltration. Reduced-scale model walls equipped with a water spraying system that can simulate the wetting process were first constructed and a series of tests were conducted with due consideration of different rainfall intensities and backfill soil types. The results indicate that cycles of wetting and drying process have adverse effects on the wall behavior, increasing wall deformation as well as earth pressure acting on the wall, and that the first cycle of wetting and drying process has more pronounced effect on the wall performance than the ensuing cycles. It is also shown that the degree to which the wetting and drying cycles affect the wall behavior depends greatly on the backfill soil type, and that the larger the fine contents, the greater is the effect of cycles of wetting and drying on the wall behavior. Practical implications of the findings from this study are discussed in great detail.

• Journal of Electrical Engineering and Technology
• /
• v.7 no.2
• /
• pp.225-229
• /
• 2012

This paper proposes a reduced-scale simulator that can replace numerical analytic methods for the estimation of potential distribution caused by ground faults in various grounding systems. The simulator consists of a hemispherical electrolytic tank, a three-dimensional potential probe, a grounding electrode, and a data acquisition module. The potential distribution is measured using a potentiometer with a position-tracing function when a test current flows to the grounding electrode. Using the simulator, we could clearly analyze the potential distribution for a reduced- scale model by one-eightieth of the buried depth and length of the grounding rod and grounding grid. Once both the shape of the grounding electrode and the fault current are known, the actual potential distribution can be estimated.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.1
• /
• pp.121-133
• /
• 2013

This paper presents the results of an investigation into the pull-out capacity characteristics of screw anchor piles. Theoretical background of screw anchor pile (SAP) was first discussed. A series of reduced-scale model tests were performed on a number of cases with different SAP geometries such as pitch and diameter of screw as well as relative density of the model ground. The applicability of the pull-out capacity prediction equations were also examined based on the test results. It was shown that the pitch of screw has negligible effect on the pull-out capacity, while the diameter of screw has relatively large effect on pull-out capacity under a given condition. Practical implications of the findings from this study are discussed in great detail.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.9 no.4
• /
• pp.331-341
• /
• 2007

Pre-loads could be imposed on the braced wall to prevent the horizontal displacements during the ground excavation adjacent to the existing tunnel. For this purpose, new pre-loading system through which large pre-loads could be applied to the braced wall was used in the model tests. Large scale model tests were performed in the real scale test pit which was 2.0 m in width and 6.0 m in hight and 4.0 m in length. Test ground was constructed by sand. Model tunnel in 1.2 m diameter was constructed before test ground excavation. Test ground was excavated adjacent to existing tunnel and was braced. To investigate the effect of pre-loading, tests without pre-load were also performed. During the ground excavation were the behavior of braced wall, test tunnel, and ground measured. Model tests were also numerically analysed and their results were compared to that of the real scale tests. As a result, it was found that the stability of the existing tunnel was greatly enhanced when the horizontal displacements of braced wall was reduced by applying pre-load larger than the design load.

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.2046-2048
• /
• 2005

This paper deals with ground potential rise of structure grounding electrode when a test current flows through grounding electrode. In order to analyze the potential gradient of ground surface on structure grounding electrode, the reduced scale model has been used. The structures were designed through reducing real buildings and fabricated with four types on a scale of one-one hundred sixty. The supporter was made to put up with weight of structure and could move into vertical, horizontal, rotary direction. When a test current flowed through structure grounding electrodes, ground potential rise was the lowest value at electric cage type(type B). According to resistivity and absorption percentage in concrete attached to structure, the potential distribution of ground surface appeared differently.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.13 no.4
• /
• pp.266-273
• /
• 2003

The purpose of this study is to obtain the effects of the parameters of the suspension system in railway rolling-stock for KT-23 type Passenger vehicle. According to the analysis and the small scale model car test. optimal condition was obtained for the stiffness ratio of secondary spring to primary spring of the suspension system and the mass ratio of the bogie frame to the car body. The analysis of the study shows that if the car body mass is increased or secondary stiffness Is lowered, the vertical vibration level is reduced and the passenger comfort can be improved. Especially, strong peaks are occurred in the frequencies corresponding to the rotational speed of driving axle and vehicle wheel. Hence, in order to obtain the dynamic characteristics through the small scale model car, the driving method of the vehicle on the test bench, rotational characteristics of the wheel and the natural modes of vehicle should be investigated and be modified.

• Journal of the Korea Concrete Institute
• /
• v.22 no.6
• /
• pp.805-816
• /
• 2010

For earthquake simulation test it is essential to make sure the similitude in behaviors between the full scale prototype and the reduced scale model. This paper presents the test results obtained through the cyclic lateral-force test, on two-story RC wall subassemblages. A lower 2-story portion of the prototype structure was selected as subassemblages. The global behavior such as the strength and ductility, and the local behavior such as flexural, shear and uplift deformation were measured. The test results of the 3 : 5 scale specimens representing the prototype were compared with those of 1 : 7 scale models. Two types of subassemblages were used: One with lintel beams and one without lintel beams. The comparison shows that 1 : 7 scale model simulated in general successfully the global and local behaviors of the prototype.

• Nuclear Engineering and Technology
• /
• v.51 no.4
• /
• pp.968-976
• /
• 2019

This paper presents a number of verification case studies for a recently developed sensitivity/uncertainty code package. The code package, ROMUSE (Reduced Order Modeling based Uncertainty/Sensitivity Estimator) is an effort to provide an analysis tool to be used in conjunction with reactor core simulators, in particular the Virtual Environment for Reactor Applications (VERA) core simulator. ROMUSE has been written in C++ and is currently capable of performing various types of parameter perturbations and associated sensitivity analysis, uncertainty quantification, surrogate model construction and subspace analysis. The current version 2.0 has the capability to interface with the Design Analysis Kit for Optimization and Terascale Applications (DAKOTA) code, which gives ROMUSE access to the various algorithms implemented within DAKOTA, most importantly model calibration. The verification study is performed via two basic problems and two reactor physics models. The first problem is used to verify the ROMUSE single physics gradient-based range finding algorithm capability using an abstract quadratic model. The second problem is the Brusselator problem, which is a coupled problem representative of multi-physics problems. This problem is used to test the capability of constructing surrogates via ROMUSE-DAKOTA. Finally, light water reactor pin cell and sodium-cooled fast reactor fuel assembly problems are simulated via SCALE 6.1 to test ROMUSE capability for uncertainty quantification and sensitivity analysis purposes.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.53 no.4
• /
• pp.59-65
• /
• 2011

The purpose of this study was to analyze the water quality change when wastewater applied to study paddy fields. CREAMS-PADDY (Chemical, Runoff and Erosion from Agricultural Management System) model was used to estimate the field-scale water quality. Simulated results were compared with observed data monitored from Byeongjeom study paddy fields which is located near the Suwon sewage treatment plant in Gyeonggi-do. Significance analysis was performed for the three different irrigation water quality level and five fertilizer reduction scenarios using LSD (Least Significant Difference) and DMRT (Duncan's Multiple Range Test). Total nitrogen was found to be significant for both irrigation water quality level and fertilizer reduction while total phosphorus was not. Annual drainage load for total nitrogen was reduced by 66~92 % compared to irrigation load when treated wastewater irrigated to study paddy fields from 2002 to 2007. Total phosphorus was reduced by 70~86 %.

• Research in Community and Public Health Nursing
• /
• v.19 no.2
• /
• pp.247-259
• /
• 2008

Purpose: This study was conducted to develop a teacher-efficacy scale which is adequate for heath education teachers. Method: A preliminary questionnaire was made based on the hypothetical factors. A total of 364 health education teachers answered to the preliminary test, and the potential factors of teacher-efficacy were checked out by exploratory factor analysis (EFA). In the main test 378 health education teachers answered, the factor structure was drawn by EFA, and confirmatory factor analysis (CFA) was conducted to test and the fitness of the factor model. Results: Through the preliminary test, 5 potential factors were found, which were instruction, health-service, administrative task, interpersonal relationship, and community connection. Also, 48 items were reduced to 31 items. Through the main test, from the 34 items were extracted 4 factors with 24 items, And then teacher-efficacy scale was developed, which included the subscales of instruction efficacy, health-service efficacy, task-interpersonal efficacy, and community connection efficacy. Conclusion: Different from that for other subject teachers, the factor structure for health teachers had 4 factors with 24 items. The scale developed in this study is consistent with health teachers' work areas, and for this reason, has significance as a adequate and valid scale to measure teacher-efficacy of health education teachers.