• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.2
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• pp.62-71
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• 2000

The abandoned mines causing settlement of the surface above and collapse of the cavities are the major influencing factor on the stability of the nearby underground structures. To prevent the harmful effect, the backfill methods are commonly applied to the cavities although the design criteria and the analysis method are not properly addressed in some cases. An approximate analytical method together with the numerical technique is considered in this study to simulate the gradual deterioration of the rock masses around the cavities and, therefore, the influential zone to the underground structures passing through the cavities. Also considered in this study is the backfill effect on the stability of the rock masses around the cavities. Specifically, the incomplete backfill effect is compared with that of the idealized backfill method by adopting elasto-plastic analysis involving a strain softening material law.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.9
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• pp.2894-2900
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• 1996

The stream generator tubes represent an integral part of a major barrier against the fission product release to the environment. So, the rupture of these tubes could permit flow of reactor coolant into the secondary system and injure the safety of reactor coolant system. Therefore, if the crack was detected during In-Service Inspection of tubes the cracked tube should be evaluated by the pulgging criteria and plugged or not. In this study, the fracture mechanics evaluation is carried out on the thru-wall axial crack due to Primary Water Stress Corrosion Cracking in the roll transition aone of steam generator tube to help the assurence the integrity of tubes and estabilish the plugging criteria. Due to the Inconel which is used as tube material is more ductile than others, the plastic instability repture theory was used to calculate the critical and allowable crack length. Based on Leak Before Break concept the leak rate for the critical crack length and the allowable leak rate are compared and the safety of tubes was given.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.77-83
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• 2018

Thermoplastic elastomers are being used increasingly throughout industry owing to their superior properties, such as superior elasticity, formability, and recoverability. Currently, research related to thermoplastic elastomers is focused on the development of composite elastomers by combining with various materials and the development of equipment. On the other hand, in the field of small and medium sized companies, it is necessary to study not only the application of these new materials, but also the process conditions that enable the extrusion of thermoplastic elastomers in inexpensive uniaxial screwing equipment. If extrusion is performed in a single screw extruder, it is important to maintain a uniform thickness through process control of the extruder. This study examined the effects of the processing temperature, which is an extrusion process variable, on the formability of a tube in the thermoplastic elastomer TPE-800L uniaxial extrusion process. The nozzle zone temperature is the most important factor in the extrusion of thermoplastic elastomer TPE-800L; the most excellent moldability was confirmed at $165-170^{\circ}C$.

• Korean Journal of Community Nutrition
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• v.14 no.5
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• pp.576-589
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• 2009

The purpose of this study was to analyze the status of school foodservice facilities, utilities and equipment & sanitary education in provinces, This study was carried out from September 2008 until December 2008 and is targeted towards schools' dietitians that work at schools with school foodservice. 1,623 schools participated in this research and Kangwondo, Choongchungdo including the metropolitan area with frequent occurrence of food bone disease were the targets of this research. The regional distribution of this research is as follows; 377 schools in Seoul, 648 schools in Gyeonggido, 160 schools in Kangwondo, 438 schools in Choongchungdo equaling 1,623 schools in total. And out of the total 1,623 schools, 815 (50.2%) were elementary schools and 808 (48.8%) were middle and high schools (p < 0.001). Most of the elementary schools, excluding 4 schools, were self-operated. In the case with middle and high schools, 81.5% (513 schools) were self-operated and 18.4% (295 schools) were contracted. When dealing with the sanitation management of school foodservice in Kangwondo and Seoul, elementary schools were less equipped with equipment and facilities than middle and high schools which proved that they were in need of improvements (p < 0.01). Schools with self-operated foodservice, in particular, were in need of preparation zone improvements. 52.3%~88.0% of stainless equipment such as utensils, spoons/chopsticks, subsidiary food tray, and food trays were sterilized by dryers. Work tables, vegetable slicers, and mincers were chemically sterilized and plastic materials were sterilized by ultraviolet rays. Data from newspapers, Internet and TV are collected beforehand and then an annual hygiene educations plan for employees are put together. Hygiene education for employees are carried out monthly through oral method.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.57-64
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• 2001

The high speed in the wire-drawing process to meet the demands for the increased productivity has a great effect on the heat generated due to plastic deformation and friction between the wire and the drawing dies. During the high carbon steel wire drawing process, the temperature rise gives a great influence to the fracture of wire. In this paper, to control the temperature rise in the wire after the deformation through the drawing die, the calculation method of the wire temperature, which includes the temperature rise in the deformation zone as well as the temperature drop in the block considering the heat transfer among the wire, cooling water and surrounding air, is proposed. These calculated results of the wire temperature at the inlet and exit of the drawing die at each pass are compared with the measured wire temperatures and verified its efficiency. So, using the program to predict the wire temperature, the isothermal pass schedule program was developed. By applying this isothermal pass schedule program to the conventional process condition, a new isothermal pass schedule is redesigned through all passes. As a result, the possibility of wire fracture could be considerably reduced and the productivity of final product could be more increased than before.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.400-413
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• 2016

The horizontal shear capacity when the flange of a steel girder is replaced with 80 MPa concrete is important for its structural safety. In this study, 6 specimens with different interface conditions were designed and fabricated based on the Limit State Design Code on Korean Highway Bridges and static tests were performed to measure the horizontal shear capacity. Not only the resistance factors of the stud shear connector, concrete and reinforcement, but also the surface conditions of the casing concrete and spacing of the horizontal shear reinforcements were used as the experimental variables. The experiments showed that the interfaces between the steel girder and the concrete flange have stronger joint performance than those between the concrete flange and deck slab. To ensure the composite action in the plastic zone, the conservative horizontal shear reinforcement is more important than the roughness in the concrete face.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.58-68
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• 2014

Transverse steel bars are used in the plastic hinge zone of columns to insure adequate confinement, prevention of longitudinal bar buckling and ductile behavior. Fabrication and placement of rectangular hoops and cross-ties in columns are difficult to construct and require larger amount of transverse steels. In this paper, to solve these problems, the new lateral confinement method using oblong hoop is proposed for the transverse confinement of columns of the oblong cross-section and flared column. The experimental study for octagonal oblong cross-section was carried out by the flared columns test in strong axis. The lateral confinement method using proposed oblong hoop detail showed satisfactory performance of lateral confinement. Therefore it can be the alternative for oblong cross-section and flared column with improved workability and cost-efficiency.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.1-9
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• 2015

Transverse steel bars are used in the plastic hinge zone of columns to insure adequate confinement, prevention of longitudinal bar buckling and ductile behavior. Fabrication and placement of rectangular hoops and cross-ties in columns are difficult to construct. Details of reinforcement for rectangular section require a lot of rectangular hoops and cross-ties. In this paper, to solve these problems, the new lateral confinement method using oblong hoop is proposed for the transverse confinement of the flared column. It can be the alternative for oblong cross-section and flared column with improved workability and cost-efficiency. The final objectives of this study are to suggest appropriate oblong hoop details and to provide quantitative reference data and tendency for seismic performance or damage assessment based on the drift levels such as residual deformation, elastic strain energy. This paper describes factors of seismic performance such as ultimate displacement/drift ratio, displacement ductility, response modification factor, equivalent viscous damping ratio and effective stiffness.

• Perspectives in Nursing Science
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• v.10 no.1
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• pp.65-76
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• 2013

Purpose: To identify an associations between health care workers' uniforms and health care-associated infection. Methods: Electronic databases, including Ovid-Medline, the Cochrane Library, CINAHL, EMBASE, KMbase, and KoreaMed, were searched. The search terms included doctor, nurse, health care worker/staff/assistant, clothing, (white) gown, uniform, (neck)tie, and attire. Only papers published in English and Korean were included. Results: 16 studies were selected from 1,900 references screened. All of the studies were non-comparative studies except for one. Four were conducted with doctors, six with nurses, one with health care workers including physiotherapists and one for medical staff plus visitors in a neonatal intensive care unit. Doctors more frequently changed their uniforms than neckties; therefore, the degree of contamination was more serious in neckties. The cuff zone was more likely to be heavily contaminated than other areas of long-sleeve gowns. Coats become contaminated quickly once worn, and colony counts reached a similar level within the first few hours after wearing them. Wearing a plastic apron or protective clothing did not prevent the bacterial contamination of nurses' uniforms, and the best way to decrease the contamination was changing to newly laundered uniforms before starting every duty. Conclusion: Healthcare workers' uniforms are a potential source of health care-associated infection although there was no robust evidence. The government must establish standards for laundering of uniforms or a requirement for institutions to provide a laundering service for healthcare workers' uniforms.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.51-61
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• 2002

In this research, a numerical algorithm is developed for the response analysis of burined pipelines considering longitudinal permanent ground deformation(PGD) due to liquefaction induced lateral spreading. Buried pipelines and surrounding soil are modeled as continuous pipelines using the beam elements and a series of elasto-plastic springs represented for equivalent soil stiffness, respectively. Idealized various PGD patterns based on the observation of PGD are used as a loading configuration and the length of the lateral spread zone is considered as loading parameter. Numerical results are verified with other research results and efficient applicability of developed procedure is shown. Analyses are performed by varying different parameters such as PGD pattern, pipe diameter and pipe thickness. Through these procedures, relative influences of various parameters on the response of buried pipeline subject to longitudinal PGD are investigated.