• Journal of Korea Water Resources Association
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• v.49 no.2
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• pp.121-132
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• 2016

The DAMBRK is applied to Janghyeon and Dongmak reservoirs in Namdaecheon basin, where two reservoirs were failed due to Typhoon Rusa in 2002. Relaxation scheme is added to DAMBRK to consider the tributary cross-section because two reservoirs are in tributary valleys. In addition, this study suggests the method to utilize the reservoir breach formation time of ASDSO (2005) and empirical formulas for peak break outflow from dam to reduce the uncertainty of reservoir breach formulation time. The single break of Janghyeon reservoir and consecutive break of Janghyeon and Dongmak reservoirs with the suggested method are considered. While the breach discharge from reservoirs rushes down, the discharge and water surface elevation along the river are predicted, and the predictions show the attenuation phenomena of reservoir break floodwave. The applicability of the model is validated by comparing the predicted height with field surveyed data, and showing good agreements between predictions and measurements.

• Journal of the Korean GEO-environmental Society
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• v.11 no.2
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• pp.13-21
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• 2010

The unsaturated slope usually is stable for a long time, but fails during heavy rainfall. And the factors of the rainfall intensity exhibit significant roles because the water content and the shear stress developed along the potential failure surface will be changed by the rainfall intensity. The objective of the study presented in this paper is to analyze the relationship between rainfall intensity and shear stress of the soil slopes by applying the laboratory slope model apparatus and undrained direct shear test with rainfall intensity controlled. The soil sample was taken from the field slope of Youngdong, and particle size analysis was done. To look over the relationship between rainfall intensity and shear strength of slope, the three-dimensional relationships among shear strength, normal stress and water content of the slope soil samples are examined; those are based on the data from the TDR sensor and undrained direct shear test.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.45-53
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• 2015

This study has obtained Soil Water Retention Curve (SWRC) of the unsaturated soil from the volumetric pressure plate extractor test and the triaxial compression tests was also conducted. By using the rainfall data measured in the site the seepage analysis of unsteady flow was performed with the program of SEEP/W in Geostudio 2007 and stability of the slope was analyzed with SLOPE/W program. Results of analyses show that shear strength of the unsaturated soil increases with the increase of matric suction. And it was also found that the net volumetric stress and the apparent cohesion increased with the matric suction. The seepage analysis of rainfall represents that the increasing rate of negative pore pressure at the zone of large negative pore pressure is appeared to be high even though lower rainfall intensity, but this tendency declines with ground depth. The stability analysis of slope was carried out for the actual plane of failure with the data representing the field condition. The factor of safety thus calculated was about unity (1.0) or just below, which means that the adopted method of analysis is in good agreement with the field condition.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.480-488
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• 2016

For the development of areas around railway lines, subsurface construction using the non-open cut method under the railway has recently been increased. However, when a structure under a railway is constructed, the stress release of the ground is not considered an important factor in the design. In this study, laboratory tests were conducted to determine a zone of stress relaxation. Field tests using an inclinometer were performed to measure the horizontal displacement of the ground during non-open cut construction. The stress release zone and the subgrade stiffness were investigated by numerical analysis. The results of the laboratory tests indicated that the failure zone in the ground was similar to a Rankine's active earth pressure zone. The measured data from the inclinometer in the field tests showed that displacements started when a steel pipe was pushed into the ground. The results of numerical analysis show that lateral earth pressure was also close to Rankine's active earth pressure. The roadbed support stiffness of the soil around the structure decreased to 40% of the original value. The ground around the subsurface structure constructed using nonopen cut methods should be reinforced to maintain the running stability of train.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.932-939
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• 2005

Recently, the lateral displacement of the passive piles which installed under the revetment on soft ground is very important during the land reclamation work along the coastal line. The revetment on the soft clay develops the lateral displacement of the ground when the revetment loading is exceeded a certain limit. The lateral displacement of ground causes an excessive deformation of under structure itself and develops lateral earth pressure against the pile foundation as well. Especially passive piles subjected to lateral earth pressures are likely to have excessive horizontal displacement and large bending moment, which induces structural failure of pile foundation and harmful effects on superstructure. The subject of study is to investigate the later displacement of pile foundation during the construction of container terminal at the south port of Incheon. Actual field measurement data and finite element method(FEM) by AFFIMEX Ver 3.4 were used to analyze the displacement of pile and the vertical settlement of soft ground. This analysis was carried out at each sequence of construction work.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.2
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• pp.103-108
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• 2017

The amount of delivered parcels have been increasing according to the change and expansion of consumption pattern through e-commerce, and they are required to minimize breakout or failure under the delivery. In this study, we measured and analyzed the distribution environment data (vibration and impact) occurred in the packaging, which were prepared with 5 types by the weight and dimension, distributed from Seoul to Busan in Korea by 2 parcel delivery service companies through e-commerce order. Date showed the parcels had 3-5 times of drop impact and 0.3-0.7 m of drop height on average, and 0.8 Grms of vibration acceleration from equivalent equation to the vertical direction. The significant gap in service quality was not found between 2 parcel delivery service companies. This study is expected to be useful for designing the suitable packaging in order to enhance safe transportation of the delivered packaging, and furthermore useful for developing Korean testing method for Field-to-Lab simulation.

• The Korean Journal of Food & Health Convergence
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• v.5 no.6
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• pp.11-16
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• 2019

The construction environment has been declared as a hazard prone area due to high number of accident and death. The study aims to identify influential factors that contribute to poor safety practices and its consequences on construction workers in Cape Coast Metropolis. Seventy respondents were taken as the sample size for the study. Descriptive analysis was used to analyze the data obtained from the field. Findings show that poor site management, working without safety gadgets, failure to use their Personal Protective Equipment (PPE) and negligence of workers were the main causes of accidents on sites. Poor site management had the highest ranking among the seven variables. Effects of poor safety practices on building construction site and delays in work execution were due to injury of workers, extra cost due to payment of compensation to injured victims, not motivated due to injury of worker and declined reputation of firm. Management team should motivate workers for safe work done, provide adequate PPE for their workers on site and have documented health and safety policy on site. Site authorities and management team should be on site regularly to ensure proper safety practices on construction site.

• Steel and Composite Structures
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• v.19 no.3
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• pp.601-614
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• 2015

The Metal Magnetic Memory (MMM) method is a non-destructive testing method based on an analysis of the self-magnetic leakage field distribution on the surface of a component. It is used for determining the stress concentration zones or any irregularities on the surface or inside the components fabricated from ferrous-based materials. Thus, this paper presents the MMM signal behaviour due to the application of fatigue loading. A series of MMM data measurements were performed to obtain the magnetic leakage signal characteristics at the elastic, pre-crack and crack propagation regions that might be caused by residual stresses when cyclic loadings were applied onto the A283 Grade C steel specimens. It was found that the MMM method was able to detect the defects that occurred in the specimens. In addition, a justification of the Self Magnetic Flux Leakage patterns is discussed for demonstrating the effectiveness of this method in assessing the A283 Grade C steel under cyclic loadings.

• Computers and Concrete
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• v.24 no.6
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• pp.561-570
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• 2019

Understanding the realistic behavior of concrete up to failure under different loading conditions within the framework of damage mechanics and plasticity would lead to an enhanced design of concrete structures. In the present investigation, QR (Quick Response) code based random speckle pattern is used as a non-contact sensor, which is an innovative approach in the field of digital image correlation (DIC). A four-point bending test was performed on RC beams of size 1800 mm × 150 mm × 200 mm. Image processing was done using an open source Ncorr algorithm for the results obtained using random speckle pattern and QR code based random speckle pattern. Load-deflection curves of RC beams were plotted for the results obtained using both contact and non-contact (DIC) sensors, and further, Moment (M)-Curvature (κ) relationship of RC beams was developed. The loading curves obtained were used as input data for material model parameters in finite element analysis. In finite element method (FEM) based software, concrete damage plasticity (CDP) constitutive model is used to predict the realistic nonlinear quasi-static flexural behavior of RC beams for monotonic loading condition. The results obtained using QR code based DIC are observed to be on par with conventional results and FEM results.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.7 no.1
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• pp.42-59
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• 2000

This study was done to analyze and develop the concept of coping in patients receiving hemodialysis. The Hybrid Model of concept development was applied to develop a conceptual structure of coping in patients receiving hemodialysis, which included a field study carried out using an in-dept interview with 18 patients in the hemodialysis room of one general hospital in Seoul. Data-analysis was done in three phases as suggested by the Hybrid Model. Finally, by summarizing the results from each case, the attributes of coping, its dimensions, definition and structure were outlined. According to the results of the study, a conceptual structure of coping which centers around stressors, stress-appraisal, strategy of coping and new definitions of coping in patients receiving hemodialysis was suggested : The coping of patients receiving hemodialysis is a process that deals with physical, emotional, inter-personal, and role stress caused by hemodialysis due to renal failure. It has a series of phases which include a phase that appraises the stressful situation based on past experience of chronic disease management, one's remaining rears, the extent of family support, the extent of economic dependency, inter-personal support. education and uncertainty, and a phase of developing coping strategies that con be affected by social support and self esteem. As a result of coping, patients adapt or not to the life situation of receiving hemodialysis.