• Journal of the Korean Society of Industry Convergence
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• v.15 no.1
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• pp.13-19
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• 2012

Due to a low stiffness of cranktrain and a failure experience from a history within short development time, a viscous torsional vibration damper was applied in order to reduce the torsional vibration and keep the high reliability for the durability of cranktrain system in the direct injection diesel engine. As an improvement of the crankshaft stiffness by increasing the diameter of main and pin journal, a rubber type damper could be considered. In this study, the control factors of rubber damper, the moment of inertia ring, stiffness of damper and damping coefficient of ring, were investigated by DFSS method through the analysis work and the measurement in the real engine condition.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.10
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• pp.996-1002
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• 2009

Elimination of squeal noise occurred during brake application is an important task for the improvement of comforts in an industrial forklift. In this paper, a test rig was developed which was possible for testing of brake noise and an experimental measurement on squeal noise was performed. The causes of the brake noise are identified by experimenting how the factors such as automatic transmission fluid and rpm of drive axle affect the squeal. In order to identify the squeal characteristics, the signal analyses for noise are performed by using frequency spectrums. Also, brake test using a forklift was carried out to confirm the reliability of test results by using a test rig comparing with the occurrence of squeal noise. Experimental results showed that the tendencies of occurrence of squeal noise are well agreed at two test methods by using the test rig and forklift.

• Journal of Korean Academy of Nursing
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• v.45 no.5
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• pp.650-660
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• 2015

Purpose: The purpose of this study was to develop an instrument to measure the parenting behavior of primary caregivers of children in early childhood. Methods: An instrument was developed according to Devellis's instrument development process. The participants in this study who completed the main survey were 370 mothers and grandmothers. The survey was conducted from June 1 to July 30, 2014, and collected data were analyzed using item analysis, half-split reliability and Cronbach's ${\alpha}$ coefficient, exploratory and confirmatory factor analysis, convergent validity. Results: The factor structure of the instrument showed the cumulative variance as 55.7% in the factor analysis. As a result of a confirmatory factor analysis, a four-factor structure was found to be appropriate, and the construct validity and convergent validity of the instrument were thereby confirmed. The finalized parenting behavior instrument consisted of 26 items and four independent factors: affectionate, laissez-faire, educational and impulsive. A five-point Likert scale was employed, and a higher score in a particular factor showed that most of the behaviors belonged to the factor. Conclusion: The instrument developed in this study was found to be reliable and valid, and can be used to develop parent-child relationship building.

• The Korean Journal of Emergency Medical Services
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• v.22 no.2
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• pp.35-49
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• 2018

Purpose: This study aimed to develop a resilience measurement scale and verify its validity and reliability. Methods: This was a methodological study. The preliminary items of the scale were derived from literature reviews and in-depth interviews. The data were collected from October 30, 2017 to January 20, 2018, and paramedics working in hospitals or fire departments were selected using convenience sampling. A self-reported questionnaire was completed by 213 paramedics in Korea. Results: Through content validity, item analysis and exploratory factor analysis, a total of 6 factors and 26 items were extracted, and the total variance was 67.12%. Factor 1 was "self-efficacy" (11 items), factor 2 was "internal control" (5 items), factor 3 was "empowerment" (2 items), factor 4 was "interpersonal capability", (3 items), factor 5 was "social support" (2 items), and factor 6 was "adaptation and coping" (3 items). Conclusion: This is the first scale developed in Korea to measure the resilience of paramedics. In future, this scale of this study will contribute to developing a resilience improvement program based on understanding the resilience level of paramedics.

• Wind and Structures
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• v.11 no.6
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• pp.427-440
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• 2008

Estimates of wind-induced wind effects on tall buildings are based largely on 1980s technology. Such estimates can vary significantly depending upon the wind engineering laboratory producing them. We describe an efficient database-assisted design (DAD) procedure allowing the realistic estimation of wind-induced internal forces with any mean recurrence interval in any individual member. The procedure makes use of (a) time series of directional aerodynamic pressures recorded simultaneously at typically hundreds of ports on the building surface, (b) directional wind climatological data, (c) micrometeorological modeling of ratios between wind speeds in open exposure and mean wind speeds at the top of the building, (d) a physically and probabilistically realistic aerodynamic/climatological interfacing model, and (e) modern computational resources for calculating internal forces and demand-to-capacity ratios for each member being designed. The procedure is applicable to tall buildings not susceptible to aeroelastic effects, and with sufficiently large dimensions to allow placement of the requisite pressure measurement tubes. The paper then addresses the issue of accounting explicitly for uncertainties in the factors that determine wind effects. Unlike for routine structures, for which simplifications inherent in standard provisions are acceptable, for tall buildings these uncertainties need to be considered with care, since over-simplified reliability estimates could defeat the purpose of ad-hoc wind tunnel tests.

• Journal of Korean Academy of Nursing
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• v.22 no.3
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• pp.316-324
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• 1992

The purpose of this study was to develop a ratio scale to measure job satisfaction of nurses and health workers in health centers. Of the 224 health centers in Korea, 105 were drawn as the sample using disproportion리 stratified random sampling. The data collection period was from May 1 to June 30, 1990 and 771 nurses and health workers working at 75 health centers participated. Subjects were instructed to rate, according to the level of satisfaction, from one to four points, 42 items revised from the tool made by Stamps et. al. (1978). The internal consistency reliability of the tool was measured by Cronbach $\alpha$ and the corrected item-total correlation coefficient. As a result of the item analysis, one item was excluded since the item had negative correlation with total items. As a result of factor analysis on the 41 items with varimax or above. Labeling and numbering of 6 factors were as follows ; factor 1 (8 items) ; Professional status of job. factor 2 (6 items) ; Interaction. factor 3 (8 items) ; Autonomy. factor 4 (8 items) ; Administration. factor 5 (7 items) ; Pay. factor 6 (4 items) ; Job(Task). Further studies are needed to identify the relationship between this tool and the effectiveness of the health center and more research is needed for generalization.

• Journal of Korean Academy of Nursing
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• v.43 no.2
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• pp.256-266
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• 2013

Purpose: The purpose of this study was to develop a measurement tool of nurse's turnover intention. Methods: Data were collected from questionnaires completed by 678 nurses who worked in 3 university hospitals in South Korea and analyzed using the SPSS 18.0 and AMOS 18 programs. Thirty-seven preliminary items were selected from 161 basic items extracted via a literature review and in depth interviews with 6 hospital nurses. Three steps with factor analysis were undertaken to verify the reliability and validity of the preliminary instruments. Finally, confirmative factor analysis was carried out. Results: As a result of the analysis, 3 factors including 10 items were selected. Cronbach's Alpha for the 10 items was .83, for job satisfaction (4 items), .78, for interpersonal relationships (3 items), .80, and for work performance (3 items), .74, which was stable. Conclusion: This study is meaningful because through it a scale reflecting Korean culture was developed to measure turnover intention in nurses. Further studies that test the psychometrics of this scale in more diverse samples are warranted.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.1
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• pp.1-5
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• 2013

The two major problems related to the blood flow in replaced prosthetic heart valve are thrombus formation and hemolysis. Reliability of prosthetic valve is very important because its failure means the death of patient. There are many factors affecting the valvular failures and their representatives are mechanical failure and thrombosis, so early noninvasive detection is essentially required. The purpose of this study is to detect the various thromboses formation by using acoustic signal acquisition and its spectral analysis on the frequency domain. We made the thrombosis models using Polydimethylsiloxane (PDMS) and they are thrombosis model on the disc, around the sewing ring and fibrous tissue growth across the orifice of valve. Using microphone and amplifier, we measured the acoustic signal from the prosthetic valve, which is attached to the pulsatile mock circulation system. A/D converter sampled the acoustic signal and the spectral analysis is the main algorithm for obtaining spectrum. Then the spectrum of normal and 5 different kinds of abnormal valve were obtained. Each spectrum waveform shows a primary and secondary peak. The secondary peak changes according to the thrombus model. To quantitatively distinguish the frequency peak of the normal valve from that of the thrombosed valves, analysis using a neural network was employed. Acoustic measurement has been used as a noninvasive diagnostic tool and is thought to be a good method for detecting possible mechanical failure or thrombus.

• Journal of Welding and Joining
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• v.19 no.3
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• pp.311-316
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• 2001

This paper presents that the affecting factors to the solderability and initial reliability. It is the factor that the coefficient of thermal expansion between package and PCB(Printed Circuit Board), the quantity of solder paste and reflow condition, and Au thickness of the solder ball pad on polyimide tape. As the reflow soldering condition for 48 ${\mu}BGA$ is changed, it is estimated that the quantity of Au diffusion at eutectic Sn-Pb solder surface and initial bonding strength of eutectic Sn-Pb solder and lead free solder. It is the result that quantitative measurement of Au diffusion quantity is difficult, but the shear strength of eutectic Sn-Pb solder joint is 842 mN at first reflow and increases 879 mN at third reflow. The major failure mode in solder is judged solder fracture. So, Au diffusion quantity is more affected by reflow temperature than by the reflow times.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.1 s.106
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• pp.50-56
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• 2006

Since most of small form-factor drives have a load/unload mechanism and the flying height of the head is getting lower as the capacity of disk drives increases, the load/unload velocity becomes one of the important factors to ensure the reliability of the load/unload mechanism. To control the load/unload velocity accurately, velocity sensing is essential. In this paper, we introduce a very practical method that acquires the load/unload velocity from the back electromotive force (BEMF) of a voice coil motor (VCM) and propose a calibration method for measuring the BEMF from a given circuit. Moreover, the effect of calibration error and temperature variation on the measurement of BEMF is shown by simulation. Then, this present method is applied to the load/unload velocity controller and is verified from the experimental result.