• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1042-1049
• /
• 2007

Recently, a theoretically-sound design approach, using an elastic multilayer model, is attempted in trackbed designs for the construction of high speed railways and new lines of conventional railways. In the elastic multilayer model, the stress-dependent resilient modulus($E_R$) is an important input parameter, that is, reflects substructure performance under repeated traffic loading. However, the evaluation method for resilient modulus using repeated loading triaxial test is not fully developed for practical purpose, because of costly equipment and the significantly fluctuated values depending on the testing equipment and laboratory personnel. In this study, the paper will present an indirect method to estimate the resilient modulus using dynamic properties. The resilient modulus of crushed stone, which is the typical material of sub-ballast, was calculated with the measured dynamic properties and the range of stress level of the sub-ballast, and approximated with the power model combined with bulk and deviatoric stresses. The resilient modulus of coarse grained material decreases with increasing deviatoric stress at a confining pressure, and increases with increasing bulk stress. Sandy soil(SM classified from Unified Soil Classification System) of subgrade was also evaluated and best fitted with the power model of deviatoric stress only.

• Structural Engineering and Mechanics
• /
• v.42 no.1
• /
• pp.73-93
• /
• 2012

With an active structural involvement in spiral case structure (SCS) that is always the design and research focus of hydroelectric power plant (HPP), the compressible membrane sandwiched between steel spiral case and surrounding reinforced concrete was often assumed to be linear elastic material in conventional design analysis of SCS. Unfortunately considerable previous studies have proved that the foam material serving as membrane exhibits essentially nonlinear mechanical behavior. In order to clarify the effect of membrane (foam) material's nonlinear stress-strain behavior on SCS, this work performed a case study on SCS with a compressible membrane using the ABAQUS code after a sound calibration of the employed constitutive model describing foam material. In view of the successful capture of fitted stress-strain curve of test by the FEM program, we recommend an application and dissemination of the simulation technique employed in this work for membrane material description to structural designers of SCS. Even more important, the case study argues that taking into account the nonlinear stress-strain response of membrane material in loading process is definitely essential. However, we hold it unnecessary to consider the membrane material's hysteresis and additionally, employment of nonlinear elastic model for membrane material description is adequate to the structural design of SCS. Understanding and accepting these concepts will help to analyze and predict the structural performance of SCS more accurately in design effort.

• Journal of People, Plants, and Environment
• /
• v.22 no.1
• /
• pp.99-107
• /
• 2019

The purpose of this study was to find out the effects of five senses activities in forests on the reduction or mitigation of daily stress using various forest healing factors such as water, sunlight, topography, phytoncide, landscape, sound, fragrance, etc. The subjects of this study were 40 young children aged 5 in an early childhood education institution located in Cheongju. The children were divided into two groups: 20 in the experimental group and 20 in the control group. The experimental group participated in the program of five senses activities in the forest in total of 12 sessions (1-2 sessions a week), with each session lasting 60 minutes from May 8 to June 16, 2017. The control group, who did not participate in the five senses activities in the forest, participated in the Nuri Curriculum operated by the educational institution. Before and after the program, tests to measure daily stress in three different situations (encountering blame-aggression situation, experiencing anxiety-frustration, and losing self-respect) were conducted on young children and the data were analyzed using SPSS 21.0. As a result, daily stress of the young children decreased in all three situations with statistical significance. Through the five senses activities in the forest, young children could feel the nature by observing and exploring it in the forest, so which reduced their daily stress compared to the activities carried out in the classroom.

• Journal of Digital Convergence
• /
• v.6 no.3
• /
• pp.131-138
• /
• 2008

The Film-making industry in Korea has significantly expanded during last decade. However, the development didn't necessarily mean there's improvement in terms of the quality of life for the film staffs. In post-production stages, especially, any workers involved in the production can get tremendous amount of mental pressure and stress due to the deadline. Thus, in this period, most labor issues are found and often ignored. In this research, compared to Hollywood, Korean domestic film industry will be analyzed with focus on labor organizations. Their role will be explored and examined in terms of improving the qualify of life as well as of the film itself.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.12 no.1
• /
• pp.72-77
• /
• 2003

The stable driving condition of high speed gear is approached by shape modifications of a gear tooth. Recently, many gear designers are using FEM for the design and the manufacture of a high precision gear. In this paper, it is aimed to drive in stable sound level through the modification of the tooth and the shape of a gear. The simulation is used to understand the effect of holes for the decrement of weight and the stress variation for the tooth modification. Beam elements used to simulate the same condition as a real gear drive by FEM. The driven gear is simulated to 60,000rpm for the tooth modification.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2002.10a
• /
• pp.33-36
• /
• 2002

The purpose of this study is to develope a indicator for agricultural water use. Agricultural water is challenged by the increase of water use in the sectors of urbanization and industry and social pressure to use water in sustainable and environmentally sound way. The development of agricultural environment indicators is divided into 13 sectors, among which agricultural water use indicators include amount and intensity of agricultural water use, efficiency of agricultural water use, shortage or surplus of water use, water stress, etc.. Agricultural water use indicators provide basic data for sustainable and environmentally sound agricultural development, and also help policy decision makers to solve water shortage problems through water policy and water management measures by making the most of the total available water resources.

• Korean Journal of Child Studies
• /
• v.24 no.4
• /
• pp.89-102
• /
• 2003

A model for teaching traditional Korean rhythmic patterns using Orff's ear training approach was developed and implemented with aim that it could be used as basic data for the operation of Korean music education. Children's rhythmic sense improved through teaching of sound searching, body rhythm, playing instruments, and improvising. Teaching the order of connective rhythmic patterns and a basic patterns-centered approach was more effective than teaching modified rhythmic patterns. With ear training, children perceived the stress of rhythmic patterns in advance and they perceived the length of sound. These results show that this model can be used as a basic approach in the operation of Korean music education.

• Korean Journal of Adult Nursing
• /
• v.20 no.3
• /
• pp.461-469
• /
• 2008

Purpose: This study was conducted to identify the personality type, problematic drinking pattern, and stress coping style of the nasal bone fracture patients by comparing those with general fracture patients. Methods: 50 nasal bone fracture patients due to violence and 50 general fracture patients due to simple trauma, such as fall and traffic accident were conveniently selected. Results: The study results showed that nasal bone fracture patients due to violence significantly presented higher level of A type personality and more problematic drinking pattern than general fracture patients due to simple trauma. Stress coping style, however, did not show significant difference between two groups. Conclusion: In order to prepare prevention strategies for basal bone fracture in the future, health education alter problematic drinking habit to sound drinking pattern may be offered and provided nursing interventions tailored to A type personality.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.15 no.1
• /
• pp.28-32
• /
• 2019

In nuclear power plant operation and spent fuel canisters, it is necessary to provide a sound technical basis for the safety and security of long-term operation and storage respectively. Recently, the peening technology is being discussed and the technology will be adopted to ASME Section III, Division 1, Subsection NX (2019 Edition). The peening is prohibited in current edition, but it will be approved in 2019 Edition and adopted. However, Surface stress improvement techniques such as the peening is used to mitigate SCC susceptible in operating nuclear plants. Although the peening will be approved to ASME CODE, there are no performance criteria listed in the 2019 edition. The Korean International Working Group (KIWG) formed a new Task Group named "Advanced Surface Stress Improved Technology". The task group will develop a CODE CASE to address PWSCC(Primary Water Stress Corrosion Cracking) and CISCC(Chloride Induced Stress Corrosion Cracking) for new ASME Section III components. TG-ASSIT was started to make peening performance criteria for ASME Section III (new fabrication) applications. The objective of TG-ASSIT is to gain consensus among the relevant Code groups that requirements/mitigation have been met.

• Journal of the Korean Society for Precision Engineering
• /
• v.10 no.3
• /
• pp.182-190
• /
• 1993

In manufacturing process of semiconductor package, the thermal stress owing to high temperature in moulding and the bubbles generated in chip bonding process become main causes to produce void. On this study we evaluated quantitatively void size by use of ultrasonic spectroscopy method which analyze the reflective pulses with broad band frequency in frequency domain, and after destructive testing we verified effectiv- eness of sizing void by use of ultasonic spectroscopy.