• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.186-189
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• 2010

Reflection(R($\omega$)), transmission(T($\omega$)) and loss(L($\omega$)) characteristics of multi-layer metamaterials are investigated experimentally in free space with the incident EM waves perpendicular to the substrate plane. The sample is made of split-ring resonators(SRRs) and wires which are the typical model of metamaterials. The R($\omega$) and T($\omega$) of multi-layer metamaterials have been calculated from the measured S-parameters. In this paper, we got the impedance-matched result according to the curves of R($\omega$), meanwhile the T($\omega$) decreased with increasing number of layers. At last, we attained the result that the L($\omega$) gets to nearly 98% around 8 GHz, with R($\omega$)=T($\omega$)=0. The design presented in this paper achieves experimented loss near unity.

• Proceedings of the KSR Conference
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.493-499
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• 2003

Railroad, a superior mode of public transportation provides safe, efficient, speedy, comfortable and economical service, has fundamentally different characteristics from airplanes, ships and cars. Among the unique characteristics of a railroad is the fact that it operates on fixed track with multiple car trains. The subway system was first selected as the best solution to difficult automobile traffic conditions and environmental problems. Seoul subway no.1line (Jongno line) was opened for service on August 15, 1974. Seoul city has completed and now operates eight subway lines (286.7km) since 1974. At present the subways operate in Busan, Daegu and Incheon city, and are under construction in Gwangju and Daejeon city. The power source for subway trains has been electricity since 1896, and power supply systems are the third rail type and/or the catenary system. The typical catenary system is the rigid bar type. R-bar and T-bar are used in the rigid bar type of catenary system, and the two types of R-bar and T-bar are uesd in Korea also. R-bar is used only for AC 25kV power supply and T-bar for DC 1,500V. From 30 years of subway experience I would like to suggest the most economic catenary system to ensure of safety, reliability and expediency for the railway lines to be constructed and the forthcoming replacement due to the life cycle after studying and analysing the characteristics, advantages and disadvantages of R-bar and T-bar.

• Journal of Korean Academy of Nursing Administration
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• 제9권2호
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• pp.233-241
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• 2003

Purpose : This comparative study was designed to compare job characteristics and job satisfaction in correctional nurses and hospital nurses. Methods : The participants for this study were 96 nurses (46 correctional nurses, 50 hospital nurses). The survey instruments included Job Diagnostic Survey(JDS) developed by Hackman & Oldman (1980) and amended by Lee(1997) and Index of Work Satisfaction(IWS) developed by Stamps and Piedmonte (1978) and amended Park & Yun (1992). Data were analyzed using of means, percentages, $x^2$ - test, t-test, Pearson correlation coefficient with SPSS program. Results : 1) Differences in job characteristics between correctional nurses and hospital nurses were not significant, but the mean score for correctional nurses' skill variety was significantly higher (t=-1.99, p<0.05) than hospital nurses 2) Differences in job satisfaction between two group were not significant, but the mean score for correctional nurses' pay satisfaction was significantly lower (t=-3.67, p<0.01.) than hospital nurses 3) There were significant negative correlations(r=-.544, p<.01) between correctional nurses' job characteristics and job satisfaction related to pay, but significant positive correlations (r=.331, p<.05) between job characteristics and professional status of job 4) There were significant positive correlations (r=.283, p<.05) between hospital nurses' job characteristics and job satisfaction, job characteristics and professional status of job (r=.530, p<.O1), and positive correlations between autonomy of job characteristics and job satisfaction (r=.522, p<.01). Conclusion : The results suggest a redesign of correctional nurses' job and improvement of outcomes. it is also recommended that job be done toward expanding and improving the reward system

• Journal of the Korean Mathematical Society
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• 제33권2호
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• pp.249-258
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• 1996

Analysis by the method of characteristics shows that if f and $u_0$ are smooth and $u_0$ has compact support, then the Hamilton-Jacobi equation $$ (H-J) ^{u_t + f(u_x) = 0, x \in R, t > 0, } _{u(x, 0) = u_0(x), x \in R, } $$ has a unique $C^1$ solution u on some maximal time interval $0 \leq t < T$ for which $lim_{t \to T}u(x, t) exists uniformly; but this limiting function is not continuously differentiable.

• Transactions of the Korean Society of Automotive Engineers
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• 제1권3호
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• pp.1-11
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• 1993

An experimental study was carried out to evaluate the characteristics of transient performance of carburettered gasoline engine under rapid accelerating transient driving conditions. In order to evaluate the characteristics of transient performance quantitatively, the concept of dead time $t_d$ response delay time $t_r$ are introduced. Performance parameters such as air mass fiowrate Gat, engine speed N, manifold boost pressure Pb, and output torque T are measured simultaneously during the rapid opening of the throttle valve by the stepping motor. During the rapid opening of the throttle valve, air mass fiowrate Gat is increased immediately without delay time, but response of engine revolution N, and output torque T are delayed. Therefore hesitation, and stumble phenomena are occurred. Dead time $t_d$ and response delay time $t_r$ of engine revolution N, which is extremely delayed comparing to other performance parameters, are respectively 0.2-0.3sec., 3.0-4.6sec., and dead time rate $t_d/{\Delta}t$ and response delay time rate $t_r/{\Delta}t$ are linearly increased with the throttle valve opening rate ${\theta}$ during the acceleration from 12 degree to 20 degree at 1250rpm.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.190-196
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• 2014

In this paper, the characteristics of a defective elliptical aluminum plate are analyzed by three different eddy current testing probes; T/R, T/T, and Impedance probes. The analysis was done by 3D finite element method, and the impedance change of real and imaginary voltage values were analyzed.

• Research in Community and Public Health Nursing
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• 제8권2호
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• pp.250-261
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• 1997

In Korea, visiting nursing services in pubic health centers have been in place since 1991. The purpose of this study is to compare the job characteristics, job motivation and job performance between visiting nurses and other public health nurses. 196 subjects were sent mailed questionnaires from Aug. to Sep., 1997. The response rate was 65.3%. Data were analyzed by a SPSSWIN program with a t-test, $X^2-test$, ANCOVA. The results were as follows : 1. The level of job ability in visiting nurses was higher than that of other public health nurses, but it was an insignificant difference(t=1.5975, p=.2078). Among job characteristics, skill variety was significantly higher in other public health nurses(t=8.2121, p=.0046); autonomy and feedback were significantly higher in visiting nurses(t=8.1877, p=.0047/t=7.7026, p=.0085). 2. There was no significant difference in the level of job motivation(t=.6485, p=.4216) and in job performance between the two groups (t=2.7393, p=.0995). In job performance, general nursing and organizational jobs were significantly higher in other public health nurses (t=4.8486, p=.1288/t=9.4237, p=.0024). 3. It was reconfirmed that there was, a significant difference in the level of skill variety, autonomy and feedback in analyzing age and career as covariates. 4. Significant positive relationship was found in job characteristics and job motivation(r=.5488, p=.0000). No significant relationship was found in job characteristics and job performance(r=.0486, p=.498). Through these results, it was supported that there were differences in some of the job characteristics and job performance between visiting nurses and other public health nurses. Therefore, it is requested to redesign job standards, training programs and management styles focusing on the job characteristics of visiting nurses.

• Research in Community and Public Health Nursing
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• 제1권1호
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• pp.503-517
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• 1989

This study is to analyze factors affecting the school nurse's activities. The survey was undertaken during Sept. 1-Nov. 30, 1986. The subjects were 137 school nurses from elementary, junior-high, and senior-high schools in Daegu City and Kyungppk Province. The results are as follows: 1. Correlational findings between school nurse's self-confidence and their general characteristics 1) Program Planning & Evaluation: Health Experinece(r=-0.1803, p<0.05) Salary Step(r=-0.1741, p<0.05) 2) Clinic Management: Salary STep(r=-0.2580, p<0.01) 3) Health Education: Salary Step(r=-0.1929, p<0.05) 4) Management of School Environment: Salary Step(r=-0.2501, p<.05) 5) Health Care Services: Health Experience(r=0.1901, p<0.05) Salary Step(r=-0.2424, p<0.05) 2. The degrees of school nurse's self-confidence(high: 4 point, low: 1 point) 1) Clinic Management: 2.92 2) Health Education: 2.86. 3) Program Planning & Evaluation: 2.74 4) Health Care Services: 2.73 5) Management of School Environment: 2.67 6) Operating of School Health Organization: 2.42 3. Significances to self-confidence on school nurse's activities 1) Program Planning as Evaluation: Expending Times for Health Care Services (r=-0.2262, p<0.05) Expending Times for Health Education (r=0.2943, p<0.05) Size of Clinic(r=0.2163, p<0.05) Location of Clinic(t=2.43, gH0.047) Use of Clinic(t=2.06, p<0.007) 2) Clinic Management: Location of Clinic (t=3.36, p<0.010) 3) Health Education: Purchase of Medicine(r=-0.1736, p<0.05) No, of Classes (r=-0.1794, p<0.05) (4) Management of School Environment: School Health Budget(r=0.1731, p<0.05) Home Message(r=0.1805, p<0.05) Location of Clinic(t=4.46, p<0.0001) 5) Operating of School Health Organization: School Health Budget(r=0.1878, p<0.05) Use of Clinic(t:1.90, p<0.018) 6) Health Care Services: School Health Budget(r=1.90, p<0.018) Expending Times for Health Education(r=0.2577, p<0.05) Size of Clinic(r=0.4336, p<0.001) Location of Clinic(t:5.10, p<0.001)

• The Korean Journal of Emergency Medical Services
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• 제5권1호
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• pp.23-35
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• 2001

This study was done to examine the relationship between stress and coping methods of 86 emergency medical technicians with the 1st or 2nd grade qualifications who serve at 36 fire stations in Gwangju and Jeonnam region from Aug. 1 to Aug. 31, 2001. Data collection was done by questionnaire. The research instruments used the stress measure tool developed by Cho Hee et al.(1999) and revised and complemented by the researcher to measure firemen's stress, and health instrument revised by Suh Mi Hye et al(1993). Data were analyzed by t-test, ANOVA, and Pearson's correlation using SPSS. The results of this study were as follows : 1. The mean score of perceived stress was 3.4. The mean score of coping methods was 2.11. 2. The levels of stress according to the general characteristics of subjects were significantly different at marital status(t=7.054, p=.009) and in relation with organization(t=3.989, p=.049). 3. The relationship between levels of stress and health status was significantly correlated(r=.325, p=.000), and so the hypothesis of this research, "the less levels of stress, the better health status is." was supported. 4. The relationship between stress and health status was significantly different at crisis status(r=.393, p=.000), relation with organization(r=.348, p=.001), the characteristics of subjects(r=.387, p=.000), special knowledge and technology(r=.337, p=.001), and the roll complication as a professional(r=.343, p=.001).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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• pp.355-358
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• 2006

A linear acoustic analysis is conducted to examine bituning of acoustic resonators for acoustic damping in a combustion chamber of liquid rocket engine. Bituned resonators are tuned to the two principal modes, the first tangential(1T) and the first radial(1R) modes. First, the acoustic-damping effect of monotuned resonators is investigated. The damping capacity is quantified by damping factor as a function of the number of the resonators monotuned to 1T or 1R mode. Next, the damping characteristics of the bituned resonators are investigated. From the numerical data, the number of resonators, to be tuned to 1T and 1R modes, respectively, can be selected properly.