• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.871-877
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• 2012

New materials widely used for automobile related industry, aircraft, space development area are mostly high hardness materials. The hardness value of some hardened materials is over HRC45 and machining of this hardened materials is called as hard turning. Hard turning has its advantage on processing flexibility, cycle time and tool cost reduction. Also this process obtains high efficiency in processing and precise surface roughness through application of the CBN tools. In hard turning process with CBN tool, surface integrity is the important factor for considering the design of machine part and component under high stress and load conditions. A purpose of this study is to analyze optimal condition in hard turning process of AISI 52100 steel (HRC62) with high CBN and low CBN on turning characteristics, tool wear mechanism comparison and surface integrity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1210-1215
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• 2002

The spent fuel handling tool is used to handle the refuel bundle and treated by hoist rope on the bridge crane. The new developed handling tool of NPP(Nuclear Power Plant) should be conformed the structural stability under earthquake condition. In this study, the stress and seismic analysis of the handling tool are performed by finite element method. Using the Floor Response Spectrum(FRS) obtained through the time history analysis, the modal and seismic analysis under Operating Basis Earthquake(OBE) and Safe Shutdown Earthquake(SSE) load conditions are carried out. Total 4 cases of different locations of the trolly and the hook are investigated. With the spring-damper element, the tension analysis of hoist rope is conducted. The stability of handling tool under earthquake load condition is conformed with regulatory guide.

• Korean Journal of Occupational Health Nursing
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• v.23 no.2
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• pp.89-96
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• 2014

Purpose: The purpose of this study is to discover the influence of the working conditions on women workers' occupational stress. Methods: Descriptive method is used to identify women's stress depending on their general working features and conditions by conducting a survey of them in women-dominated service industries. SPSS 18.0 program is used for data analysis and descriptive statistics is presented with standard deviation, frequency and percentage. ${\chi}^2$-test is used as an analysis tool. To figure out factors that influence their stress, logistic regression analysis is used for general features and working conditions as independent variables, and occupational stress as a dependent variable. Results: As a result, among the independent variables, employment status, weekly working hours, career, shiftwork, and work-family-balance are meaningful factors that influence their stress. Temporary workers' stress is 3.65 times higher (p<.001), and workers working over 48 hours a week have 1.97 times higher stress (p<.003). Workers with over 5 years' career are under 1.73 times higher stress (p<.046) and shift workers are under 3.51 times higher stress (p<.001). Work family balance results in 1.93 times higher stress (p<.009). Conclusion: It is necessary to seek how to prevent and manage women workers' stress considering features.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.4 no.1
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• pp.54-67
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• 1993

This study is to investigate the stress and stress degree in mothers of autistic children. In order to obtain data for planning nursing strategies for mothers of autistic children The assessment tool for the stress was constructed through reviewing literatures on the stress and gathering the stress items by nonstructed face to face interviewing 14 mothers of autistic children The stress tool consists of 74 items each with five point rating scale A data collection was made front 160 mothers of autistic children from 11 institutions for autistic children in Seoul and Kyung-Ki province. The reliability coefficients by Cronbach's a test was 0.94 for the stress scale. The results are as follows : 1) The mean of stress is 3.19, in the area of the etiology, prognosis and the treatment-education, with cause of the treatment the edeucatlon and the prognosis of child's handicap. The mean of stress is 2.85 In the area of the negative of mother's self image, 2.45 in the area of the mother's ordinary life. The mean of stress was 2.05, lowest in the family and social relationship 2) The mean score for the total was 2.62 points. The items with highest stress score were 'All autistic child has not been understood by the society', 'If we die, 1'm afraid that this child will not be cared by someone', 'There is no institution that the child get the schoolibg', etc The stress item with the lowest mean score were 'Keep away the child from husband', 'Being divorced by husband', etc. 3) An analysis of relationship of stress degree to general characteristic shows a statisically significants difference in the number of children in the family and the cognition of the seventy of the child problem

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.57-63
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• 2014

At present, a high-speed swivel tool head of a small size is required to improve the productivity of CNC automatic lathes. Hence, there is growing interest in shorter machining times with higher cutting speeds. However, an increase in the rotation speed of a swivel tool head also has adverse effects, such as vibration and noise caused by the swivel tool head system. In this work, the fatigue life and contact pressure of a swivel tool head bearing system driven by gears were calculated. Based on the calculated results, a prototype swivel tool head was manufactured and its static and dynamic characteristics, i.e., the vibration, noise and precision, were measured using a reliability testing device which allows the application of cutting force to the end of the swivel tool head.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.89-95
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• 2001

Ceramic tool has to equip with not only high toughness and strength but also low thermal expansion and good thermal conductivity which leads to the high thermal shock resistance. These characteristics make it have longer tool life under thermal stress condition. In this study, commercial Si$_3$N$_4$ceramic cutting tool and home-made SiC based ceramic cutting tools which have different sintering time and chemical composition are tested under various cutting speed and the feed rate increase, the cutting force and the flank wear growth ratio increase, too. The performance of home-made SiC based ceramic cutting tool shows the possibility to be a new ceramic tool.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.701-708
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• 2004

This paper discusses applicability of the enhanced reference stress method to estimate J-integral along the semi-elliptical surface crack front. It is found that angular variations of normalized J­integral are strongly dependent on the geometry, loading mode and loading magnitude. As application of the reference stress approach to semi-elliptical surface cracks implies proportional increases in the normalized J-integral, the present results pose a question in applicability of the reference stress approach. However, investigation of the error in the estimated J-integral in the present work suggests that the enhanced reference stress approach, recently proposed by authors, provides an effective engineering tool fur estimating crack driving force along the semi-elliptical surface crack front.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.119-125
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• 2004

Generally, it is used the compensation spring to compensate the inaccuracy of screen image induced by thermal deformation in CRT monitor. Its mechanism is bi-metallic system made of heterogeneous metals and these is bonded by laser welding. But laser welding induces the non-uniform temperature distribution and locally residual stress is yielded by these temperature deviation. This paper studies residual stress of laser weldment using FEA and hole drilling method. The results are followed. In the case of heterogeneous materials weldment, higher residual stress induced in the weldment region of SUS 304 which have larger CTE than Ni 36 and residual stress on the middle of specimen is higher by 10.9% than that of its surface Measured residual stress of SUS 304 yield 481MPa and that of Ni 36 is 140.5MPa in the vicinity of the welding region. And the residual distribution is very similar in comparison with FEA result.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.1
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• pp.32-37
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• 2002

The use of hexagonal ceramic inserts for copper extrusion dies offers significant technical and economic advantages over other forms of manufacture. In this paper the data on the loading of the tools is determined from a commercial FEM package as the contact stress distribution on the die-workpiece interface and as temperature distributions in the die. This data can be processed as load input data for a finite element die-stress analysis. Process simulation and stress analysis are thus combined during the design and a data exchange program has been developed that enables optimal design of the dies taking into account the elastic deflections generated in shrink fitting the die inserts and that caused by the stresses generated in the process. The stress analysis of the dies is used to determine the stress conditions on the ceramic insert by considering contact and interference effects under both mechanical and thermal loads.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.194-197
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• 1996

The high-strength aluminum alloy 7075-T651 was used to observe the fatigue-crack-propagation behavior for the various stress ratios with constant amplitude loading and thus to predict the fatigue life. With a chevron notch in the specimen the fatigue-crack-propagation behavior of through crack was investigated. Crack propagation behavior of through crack in the depth direction and crack growth of weldments were experimentally studied. Base material heat affected zone and weld material were considered in the fracture of weldments. The change of crack-propagation length with respect to several parameters such as stress intensity factor range(ΔK) effective stress intensity factor range(ΔKeff)ration of effective stress intensity factor range(U) stress intensity factor of crack opening point(K op) maximum stress intensity factor(K max) and number of cycles(Nf)was determined. The crack length of through crack of weldments was 2.4mm and the remaining part was a base material. The experiment was accomplished by making the crack propagate near the base material.