• Journal of Biomedical Engineering Research
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• v.24 no.4
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• pp.347-354
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• 2003

In this paper, a computational method of an action potential including the effect of extremely low frequency and mobile phone (external) electromagnetic fields is Proposed. The method is based on the Hodgkin and Huxley model, applies the effect of the electromagnetic fields on the action Potential in terms of a binding factor into the injection current of the model, and calculates the Strength-Duration curve from numerical experiments for a frequency range of electromagnetic fields. In the numerical experiments, the coupled ordinary differential equations of the action potential and the state variables are solved solf-consistently by using Runge-Kutta Fehlberg method. The range of the frequency considered is from 1Hz through 100Hz and of 900MHz, which is specific for a mobile Phone. The Strength-Duration curves resulted showed good agreements with the equation suggested by Hodgkin and Huxley.

• Korean Journal of Rural Living Science
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• v.4 no.2
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• pp.127-137
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• 1993

This survey was carried out in order to find out the education needs of rural women in home improvement. The data were collected from 500 samples who were conjugal women under 65 years old by adminitrating the researcher developed questionaire through interview method. This interview was intensively focused in education fee, free or charged. The major findings of the survey were summerized as follows ; 1) In the educational fee is free, $\ulcorner$fatigue recovery$\lrcorner$ is demanded highest(61.7%) and $\ulcorner$wrighting art$\lrcorner$ is lowest among 30 items. The needs of education are devided 7 fields of the home improvement $\ulcorner$dietary life$\lrcorner$ is the highest demand fields among them. 2) If educational fee is charged, the item of $\ulcorner$technique for side job$\lrcorner$ was highest(42.2%) but $\ulcorner$selecting clothes$\lrcorner$ was lowest, And the field of $\ulcorner$home management$\lrcorner$ was highest demands. 3) On the overall needs of education, charged and free, they want the item of $\ulcorner$family nutrition management$\lrcorner$ and the field of $\ulcorner$dietary life$\lrcorner$ was selected highest. 4) In the relationship between needs of education items and individual/household variables, i.e. age, degree of education, life philosophy, hobby, social activity, experience of home improvement education, and transportation convenience, had significant relationship at 5% level. And the relationship of $\ulcorner$dietary life$\lrcorner$ and $\ulcorner$home management$\lrcorner$ fields are higher significant with individual/household variables.

• Steel and Composite Structures
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• v.22 no.1
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• pp.161-182
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• 2016

A state space differential reproducing kernel (DRK) method is developed for the three-dimensional (3D) analysis of functionally graded material (FGM) axisymmetric circular plates with simply-supported and clamped edges. The strong formulation of this 3D elasticity axisymmetric problem is derived on the basis of the Reissner mixed variational theorem (RMVT), which consists of the Euler-Lagrange equations of this problem and its associated boundary conditions. The primary field variables are naturally independent of the circumferential coordinate, then interpolated in the radial coordinate using the early proposed DRK interpolation functions, and finally the state space equations of this problem are obtained, which represent a system of ordinary differential equations in the thickness coordinate. The state space DRK solutions can then be obtained by means of the transfer matrix method. The accuracy and convergence of this method are examined by comparing their solutions with the accurate ones available in the literature.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.207-216
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• 1997

We developed the durability estimation and design systems to minimize the volume, considering the durability, efficiency, and design requirements of worm gears. That is, we consider each kind of factors affecting on durability on the basis of AGMA Standard for the cylindrical and double-enveloping worm gears. We also estimate input power on the basis of wear and durability, bending strength and deflection of worm shaft, and we developed the durability estimation and design systems of power transmission worm gears introducing the optimal design method on the personal computer to be easily used in field. Also, we developed a method which converts the design variables obtained from the optimal design method to integer values(number of worm threads, number of worm threads, number of worm wheel teeth, etc.,) to be used in real design and production. The developed durability estimation and design method can be easily applied to the design of worm gears used as power transmission devices in machineries and is expected to be used for weight minimization of worm gear unit.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.125-127
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• 2001

Switched reluctance motor (SRM) has some advantages such as low cost, high torque density etc. However SRM has inevitably high torque ripple due to the double salient structure. To apply SRM to industrial field, we have to minimize torque ripple, which is the weak-Point of SRM. This paper presents optimal design process of SRM using numerical method such as 2D finite element method (FEM) and 3D equivalent magnetic circuit network method (EMCNM). The electrical and geometrical design parameters have been adopted as 2D design variables. The overhang structure of rotor has been also adopted as 3D design variable. From this work, we can obtain the optimal design, which minimize the torque ripple and maximize energy conversion loop.

• Particle and aerosol research
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• v.18 no.4
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• pp.109-127
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• 2022

Recently, low-cost particulate matter (PM) sensors have been widely used in monitoring mass concentration. Maintaining the accuracy of the sensors is important and requires rigorous performance evaluation and calibration. In this study, two commercial low-cost PM sensors(LCS), Plantower PMS3003 and Plantower PMS7003, were evaluated in the laboratory and field with a reference-grade PM monitor (GRIMM 11-D). Laboratory evaluation was conducted with single/mixed particles of PSL (Poly Styrene Latex) in an acrylic chamber at 20℃ and relative humidity of 20%. Field evaluation was conducted inside a building of Yonsei University (Shinchon) from February 12 to March 31, 2022. In both evaluations, LCS measured values became different from reference measured values when the relative humidity was high or the outdoor air PM10/PM2.5 ratio was high. Based on the field evaluation, the LCS measured values were corrected through four different regression analysis models. As a result, the multivariate polynomial regression analysis model showed highest matching with the reference PM monitor (PM2.5 >0.9, PM10 >0.85). In this model, the PM10/PM2.5 ratio and relative humidity were chosen as independent variables.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.506-509
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• 2006

Shaped Sound Focusing is defined as the generation of acoustically bright shape in space using multiple sources. The acoustically bright shape is a spatially focused region with relatively high acoustic potential energy level. In view of the energy transfer, acoustical focusing is essential because acoustic energy is very small to use other type of energy. Practically, focused sound shape control not a point is meaningful because there are so many needs to enlarge the focal region especially in clinical uses and others. If focused sound shape can be controlled, it offers various kinds of solutions for clinical uses and others because a regional focusing is essentially needed to reduce a treatment time and enhance the performance of transducers. For making the shaped-sound field, control variables, such as a number of sources, excitation frequency, source positioning, etc., should be taken according to geometrical sound shape. To verify these relations between them, wavenumber domain matching method is suggested because wavenumber spectrum can provide the information of control variables of sources. In this paper, the procedures of shaped sound focusing using wavenumber domain matching and relations between control variables and geometrical sound shape are covered in case of an acoustical ring.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.13 no.1
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• pp.96-106
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• 2006

Purpose: This study was dont: to evaluate the factors that influence secondary traumatic stress, burnout, and physical symptoms experienced by firefighters. In addition, a hypothetical model was developed. Method: The data were collected using self-reported questionnaires from 410 field service firefighters. Data analysis was done with the SPSSWIN 10.0 program for descriptive statistics and Windows LISREL program to determine the causal relationship between the measurement variables. Results: The hypothetical model which was developed fits well with actual data(${\chi}^2$=3.16, p=0.99, GFI=1.00, AGFI=0.99, NFI=0.99, and NNFI=1.06). The variable, personality type, social support, and impact mobilization frequency had a significant effect and accounted for 7% of the secondary traumatic stress in firefighters. The variables, career, social support, and secondary traumatic stress had a significant effect and accounted for 24% of the burnout in firefighters. Social support, impact mobilization frequency, and secondary traumatic stress were important variables and accounted for 31% of the physical symptoms in firefighters. Conclusion: It is necessary for firefighters to manage themselves according to their personality types. Strategies that can increase the firefighters' social support and decrease their perceived secondary traumatic stress also need to be developed to minimize or prevent a negative effect on their health.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.8
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• pp.577-588
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• 2020

The study investigates by empirical methods the effect of motivation, leadership, and organizational culture on job satisfaction, and employee performance at Wahana Resources Ltd North Seram District, Central Maluku Regency, Indonesia. This examination intends to be a critical review for academics researching the field of human resources management (HRM). The study's sample consisted of 155 employees who were selected using the Proportionate Stratified Random Sampling method. At the same time, data were collected using a questionnaire and then analyzed using the Structural Equation Modeling on Amos. The results of data analysis showed that work motivation and organizational culture had a positive and significant effect on performance, but did not significantly influence employee job satisfaction. While leadership has a substantial impact on employee job satisfaction, it does not affect performance. The results of testing the coefficient of determination show that job satisfaction is influenced for 57.4% by motivation, leadership, and culture variables, while employee performance variables are influenced for 73.5% by motivation, leadership, culture, and job satisfaction variables. Other factors outside this study influence the rest. Motivation, leadership, and organizational culture of employees need to be improved to increase job satisfaction. Invariably, if employee job satisfaction increases, employee performance will also increase.

• Journal of the Korean Institute of Landscape Architecture
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• v.23 no.2
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• pp.213-222
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• 1995

To increase the night use level, this study was analyzed perception of users about the public safety, and extracted main variables which were influencing public safety. The public safety was evaluated by the actual (on site) and nonactual users (off site) and the Delphi method. The night users of female and the elders were relatively more than male and the young respectively as compared with day. Walking was predominant in approaching means. In public safety ratings, $\boxDr$vuknerability to violence$\boxUl$varied accoding to sex, income, education, marriage, job, age. $\boxDr$crowding, $\boxDr$noise$\boxUl$ were important variables in satisfying users at night. $\boxDr$Lack of surveillance, $\boxDr$harassment of other person$\boxUl$, $\boxDr$rowdy behavior in poorer visibility$\boxUl$, $\boxDr$fear in lower intensity of light$\boxUl$ and $\boxDr$vulnerability to violence$\boxUl$stood high , so it is required guarantee of security guard to enhance the park use at night Although the ratings between field and indoor evaluation were somewhat different the variables had so similiar rant.