• Journal of Industrial Technology
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• v.18
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• pp.87-95
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• 1998

Cracking is considered to be one of the important factors in determining the durability of reinforced concrete structures. When the bending stress exceeds the modulus of rupture of the concrete, cracking form along the length of members. The total load is transferred across these cracks by the reinforcement, but the concrete between cracks is still capable of carrying stresses due to the bond between steel and concrete. This phenomenon is called the tension stiffening effect. The tension stiffening effect is affected by many variables, such as the bond stress, strength of concrete, interrocking of aggregate, type of steel, and dowel action of steel. Also, this tension stiffening effect is usually quite significant in beams under service loading, and must be taken into account in the calculation of deflection and crack widths. In this study, the experiment was carried out on types of specimen, strength of concrete, and steel ratio and finite element analysis were compared in terms of load-deflection relationship, crack pattern.

• Steel and Composite Structures
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• v.43 no.5
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• pp.603-623
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• 2022

This article is dedicated to predict the natural frequencies of joined conical shell structures made of Functionally Graded Material (FGM). The structure includes two conical segments. The equivalent material properties are found by using the rule of mixture based on Voigt model. In addition, three well-known patterns are employed for distribution of material properties throughout the thickness of the structure. The main objective of the present research is to propose a novel exponential pattern and obtain the related equivalent material properties. Furthermore, the Donnell type shell theory is used to obtain the governing equations of motion. Note that these equations are obtained by employing First-order Shear Deformation Theory (FSDT). In order to discretize the governing system of differential equations, well-known and efficient semi-analytical scheme, namely Generalized Differential Quadrature Method (GDQM), is utilized. Different boundary conditions are considered for various types of single and joined conical shell structures. Moreover, an applicable modification is considered for the continuity conditions at intersection position. In the first step, the proposed formulation is verified by solving some well-known benchmark problems. Besides, some new numerical examples are analyzed to show the accuracy and high capability of the suggested technique. Additionally, several geometric and material parameters are studied numerically.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.598-606
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• 2020

This study analyzed the factors of stress perception and their patterns depending on the high school students from different types of high school, which include academic high schools and vocational high schools. The data reflected the degree of stress perception according to several factors, which are considered to be related to stress perception, and the study analyzed how differently these factors affected students in each school type. The subjects were 29,380 students from the 14th Korea Youth Health Behavior Survey who meet the purpose of this study. The factors related to stress perception were classified into general characteristics, health behavior characteristics, and health status characteristics. The factors of the study were compared in each group and between the groups. In both school types, stress perception was associated with a number of common factors and some group specific factors. The common main factors related to stress perception were depressive experience, subjective recognition of their health status, subjective recognition of sleep satisfaction, and gender. However, the pattern in which each factor was related to stress perception differed according to the school types. Therefore, efforts should be made to reflect the characteristics of each school type while considering the common factors related to stress perception when making policies for managing high school students' stress.

• Korean Journal of Psychosomatic Medicine
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• v.8 no.2
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• pp.165-171
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• 2000

Objectives : Alopecia areata has been known to be closely related to stress. The purpose of this study is to examine the relationship between stress and alopecia areata investigating how life events(which alopecia areata patients experience), amount of stress, coping strategy, and their personality type affect the oneset and aggravation of the disease. Methods : The subjects were 43 alopecia areata patients who visited the department of dermatology outpatients clinic, and 36 fungal infection diseases patients as the control group. They all completed Scale of Life Events, Coping Style Cheklist, Eysenck A-type Personality Inventory. The analysis of covariance with the age as covariate was carried out. Results : Compared to the control group, alopecia areata patients had significantly more stressful life events, and higher amount of stress, but there was no significant difference in coping strategy. Type A Personality is also resulted to have no significant relationship to alopecia areata. Conclusions : Alopecia areata patients had significantly higher amount of stress than the control group, and this result is consistent with the previous studies which suggest that stress contributes to the oneset of alopecia areata. The causual relationship between stress and alopecia areata should be further examined in order to be applied in clinical setting.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.1-9
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• 2015

In this paper, the RC column-based joint connection part carry out loading test by reinforced hollow or extended Base Plate in order to confirm that RC joint punching shear reinforcement effect of applying the Base Plate. Base Plate thickness, extension length, size, and type as the variable, Base Plate suitable for the stress distribution and shape and dimensions confirmed through experiment and then reinforcing effect was analyzed. Experimentally, vertical load transmitted to the Base Plate from column to foundation is effective to stress distribution and then, type of hollow reinforcement more efficient than a closed. Through experiment, improve performance and ductility due to reinforcement and relative to the thickness of the existing foundation reduced even showed better performance than the existing. The behavior of the reinforced specimens be able to induce from brittle to ductile. Experiment on loading to destroy performed the pattern of cracks, destruction aspect before and after reinforcement.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.1-6
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• 2017

Recently, the brittle materials such as ceramics, glass, sapphire and textile material have been widely used in semiconductors, aerospace and automobile owing to high functional characteristics. On the other hand, it has the characteristics of difficult-to-cut material relative to all materials. In this study, diamond electro-deposited band-saw machine was developed to operate stably using water-coolant type through relative motion between band-saw tool and $Al_2O_3$ material. High densified $Al_2O_3$ material was manufactured by spark plasma sintering method. The bulk density was observed by the Archimedes law and the theoretical density was estimated to be $3.88g/cm^3$ and its hardness 14.7 MPa. From the dicing sawing test of $Al_2O_3$ specimen, behavior of surface roughness and band-saw wear are dominantly affected by the increase of the band-saw linear velocity. Additionally, an continuous pattern type of diamond band-saw was a very effective due to entry impact as a one-off for brittle material.

• Journal of agricultural medicine and community health
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• v.33 no.1
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• pp.11-26
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• 2008

Objectives: We evaluated the level of psychosocial stresses and fatigue symptoms among clerical public officers and its related factors.Methods: The self-administered questionaires were performed, during the period between Dec. 5th, 2005 Metropolitan City. The survey items included subjects' socio-demographic and job-related characteristics, health-related behavior, degree of job demand, job autonomy, social support in work, type A behavior pattern, locus of control, sense of self-esteem, psychosocial distress and degree of fatigue.

• Journal of the Society of Disaster Information
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• v.19 no.1
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• pp.216-230
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• 2023

Purpose: The purpose is to prevent accidents by predicting disasters through the analysis of near-miss. Method: In this study, a near-miss literature review and data were collected at construction sites, and a questionnaire survey was conducted to use logistic regression analysis and decision tree analysis to classify the possibility of near-miss connection. Result: As a result of analyzing the effects of near-miss types on mental, physical, and safety habits and behaviors, the factor with a high influence on the body is the need for near-miss management, the type of job is electricity·information communication, and health status in order, and the mental factor is the construction scale The influence was high, and the factors with the highest influence on the habit behavior factors were analyzed in the order of experience, number of serious injuries, and occupation in order of illusion, inappropriate work instructions, and body parts. Through decision tree analysis, factors and patterns that affect the possibility of a near-miss being a surprise accident were identified. Conclusion: Construction site officials consider the observation of near-miss and mentally and physically. Specific management of the relevance of physical aspects to near-miss should be implemented, and a work environment in which serious accidents are reduced is expected through personnel allocation, work plans, work procedures and methods, and feedback so that inappropriate work instructions do not lead to near-miss.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.633-642
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• 2008

It's important to measure quantitative properties about thermal-nano behavior of polymer for producing high quality components using Nanoimprint lithography process. Nanoscale indents can be used to make the cells for molecular electronics and drug delivery, slots for integration into nanodevices, and defects for tailoring the structure and properties. In this study, formability of polymethylmetacrylate(PMMA) and polycarbonate(PC) were characterized Polymer has extreme variation in thermo mechanical variation during forming high temperature. Because of heating the polymer, it becomes softer than at room temperature. In this case it is particularly important to study high temperature-induced mechanical properties of polymer. Nanoindenter XP(MTS) was used to measure thermo mechanical properties of PMMA and PC. Polymer was heated by using the heating stage on NanoXP. At CSM(Continuous Stiffness Method) mode test, heating temperature was $110^{\circ}C,120^{\circ}C,130^{\circ}C,140^{\circ}C$ and $150^{\circ}C$ for PMMA, $140^{\circ}C,150^{\circ}C,160^{\circ}C,170^{\circ}C$ and $180^{\circ}C$ for PC, respectively. Maximum indentation depth was 2000nm. At basic mode test, heating temperature was $90^{\circ}C$ and $110^{\circ}C$ for PMMA, $140^{\circ}C,160^{\circ}C$ for PC. Maximum load was 10mN, 20mN and 40mN. Also indented pattern was observed by using SEM and AFM. Mechanical properties of PMMA and PC decreased when temperature increased. Decrease of mechanical properties from PMMA went down rapidly than that of PC.

• Korean Journal of Family Social Work
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• no.54
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• pp.225-262
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• 2016

This article reports on the analysis of the patterns and frequency of recurrences of substantiated instances of maltreatment in the Child Protective System (CPS). The data was collected from 2012 to 2014 by the CPS. Five-thousand-five-hundred-forty-two cases were substantiated in 2012 and then 323 cases were exposed recurrence during that time. Most recurrence families experienced only one recurrence. Results from survival analyses instances indicated that risk of recurrence was greatest during the first one month following a report. The prior CPS report, multiple type of abuse, physical abuse, and services type was linked the pattern of recurrence of maltreatment. Also, victim's age and the number of problematic behavior, perpetrator's stress and social isolation, intra family member as perpetrator, prior CPS report, and the number of reports was linked recurrence.