• Journal of the Optical Society of Korea
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• 제17권6호
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• pp.525-532
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• 2013

Contrary to the academic interests of other existing studies elsewhere, this study deals with how the alignment algorithms such as sensitivity or Differential Wavefront Sampling (DWS) can be better used under effects from field, compensator positioning and environmental errors unavoidable from the shop-floor alignment work. First, the influences of aforementioned errors to the alignment state estimation was investigated with the algorithms. The environmental error was then found to be the dominant factor influencing the alignment state prediction accuracy. Having understood such relationship between the distorted system wavefront caused by the error sources and the alignment state prediction, we used it for simulated and experimental alignment runs for Infrared Optical System (IROS). The difference between trial alignment runs and experiment was quite close, independent of alignment methods; 6 nm rms for sensitivity method and 13 nm rms for DWS. This demonstrates the practical usefulness and importance of the prior error analysis using the alignment algorithms before the actual alignment runs begin. The error analysis methodology, its application to the actual alignment of IROS and their results are described together with their implications.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.193-200
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• 1999

Since Broms and Bennermark(1967) suggested the face stability criterion based on laboratory extrusion tests and field observations, the face stability of a tunnel driven in cohesive material has been studied by several authors. And recently, more general solution for the tunnel front is given by Leca and Panet(1988). They adopted a limit state design concept to evaluate the face stability of a shallow tunnel driven into cohesionless material and showed that the calculated upper bound solution represented the actual behavior reasonably well. In this study, two factors are simultaneously considered for assessing tunnel face stability: One is the effective stress acting on the tunnel front calculated by upper bound solution; and the other is the seepage force calculated by numerical analysis under the condition of steady state ground water flow. The model tests were performed to evaluate the seepage force acting on the tunnel front and these results were compared with results of numerical analysis. Consequently, the methodology to evaluate the stability of a tunnel face including limit analysis and seepage analysis is suggested under the condition of steady state ground water flow.

• 가정과삶의질연구
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• 제24권5호
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• pp.223-237
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• 2006

This study explores how well parents and their children recognize the social attitudes of one another. Mothers, fathers and youths were asked to state their own opinion on various social issues then predict their children's, fathers' and mothers' responses(attributed attitudes). Empirical evaluation of the possible socialization consequences of actual versus attributed attitudes leads to a series of hypotheses. The data were collected from single students at a university in Seoul and their parents. Included in the seven social attitude were sexuality, educational, economic, political, ecological, religious and family issues. Analysis of the responses 98-110 triads, each consisting a mother, a father and a young adult child showed that both mothers and fathers were limited in their ability to gauge the attitudes of their children. Guided by attribution theory, this study tested several hypothesized relationships between the actual response of mother, the actual response of the father, the perceived response of the mother, the perceived response of the father and the actual response of the child. The theoretical model was tested with AMOS 5.0, utilizing path analysis, which is a form of structural equation modeling with manifest variables. Overall model fit was assessed by examining GFI, NFI, TLI, CFI and RMR. Results of the data analysis can be summarized as follows. First, the children perceived their mothers and fathers to be highly similar in their opinions and the actual responses of the mothers and the fathers were considerably correlated. Second, the fathers' responses whether attributed or actual were more predictive than the mothers' responses to their children's opinions. The alternative model suggests considerable support for the attribution theory. Indeed, within a family, the actual opinions of parents appear to have little direct bearing on the child's orientations, except when the actual orientations are perceived and reinterpreted by the children. It is not what parents think, but what their children think they think that predicts their offsprings' attitudes.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2240-2248
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• 2015

The integration of the large-scale wind power brings great challenge to the stability of the power grid. This paper investigates and studies the fault on May 14, 2012 of the large-scale cascading trip-off of wind turbines in North China. According to the characteristics of the voltage variation, the fault process is divided into three stages: the pre-event stage, the critical stage before cascading, and the cascading stage. The scenes in the fault are reproduced, using the full-size actual power system model. Simulation models of double-fed induction generators (DFIGs) and SVCs including protection settings and controller strategies are carefully chosen to find out the reason of voltage instability in each stage. Some voltage dynamic that have never been observed before in the faults of the same kind are analyzed in detail, and an equivalent voltage sensitive dynamic model of DFIG is proposed for the fast computation. The conclusions about the voltage dynamics are validated by the actual PMU observation evidence.

• 한국컴퓨터정보학회논문지
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• 제24권2호
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• pp.179-184
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• 2019

As the tendency of children's overdependence on smart phones increased, it was obligatory to carry out preventive education more than once a year in kindergarten and day care center, but there is no specific guidance on contents and method of preventive education. This is due to the lack of prior studies on the actual use of smartphones and the influence variables of infants and young children. The purpose of this study was to investigate the effects of use time, frequency of use, and sociological background variables on the actual situation of smartphone usage and overdependency on smartphone among 3-5 year old children nationwide. For the analysis, the frequency of the use of smartphone for 3-5 year old children was analyzed by frequency analysis, and the influence variables were correlated and multiple regression analysis. Research shows that smartphone overdependence of 3-5 year old children have an influence on the use time and frequency of use. The results should include content that restricts the use time and frequency of use of smartphones and prevention education programs for 3-5 year olds and young children. Suggesting a need for a transition to the educational method used.

• 전기학회논문지P
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• 제66권4호
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• pp.163-168
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• 2017

This paper presented an evaluation method for the efficiency uncertainty of a three-phase induction motor using finite element analysis. The motor efficiency in the finite element analysis is calculated by the loss separation method as in the actual test. In the process of evaluating the efficiency uncertainty, the difference between the finite element analysis and the actual test is the method of calculating the type-A / B standard uncertainty of the input quantity to estimate the efficiency and each losses. For the input quantities which can confirm the instantaneous values with respect to time, the type-A standard uncertainty in the finite element analysis is calculated from the RMS values or average values having separate periods in the steady state. And, the type-B standard uncertainty in the finite element analysis is assumed to be zero. Also, this paper compared and analyzed the efficiency uncertainty evaluated by the proposed method and the efficiency uncertainty through the actual test.

• 한국생활과학회지
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• 제17권5호
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• pp.1001-1013
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• 2008

The purpose of this study were to make clear the actual state of indoor air quality by cooling in private institute classrooms and to analyze influencing factors on indoor air quality. The measurements of physical elements and observations of architectural characteristics and living conditions were carried out in each 1 classroom of 5 private institutes. Measuring elements were indoor temperature, relative humidity, $PM_{10}$, HCHO, CO, and $CO_2$ concentration. As results, the averages of indoor temperature each classroom were $21.7\sim28.1^{\circ}C$. 3 classrooms were lower than the Maintenance standard($26\sim28^{\circ}C$) of School Health Law. The means of relative humidity were 48$\sim$63%, all classrooms were ranged within the standard(30$\sim$80%). The means of $PM_{10}$ concentration were 2.1 $\sim$ 17 $\mu g/m^3$, all classrooms were kept within the standard(100 $\mu g/m^3$). The means of HCHO concentration were 0.02$\sim$0.16 ppm, 2 classrooms were exceed the standard(0.1 ppm). The means of CO concentration were 1.4$\sim$3.6 ppm, all classrooms were kept within the standard(10ppm). The means of $CO_2$ concentration were 1,593$\sim$3,819 ppm, all classrooms were exceed the standard(1,000ppm). The results of analysis on influencing factors of the physical elements are as follow; the air conditioner set of temperature, personal necessities like hair spray, teacher's smoking in corridor, windows and doors opening time, the number of students, and volume of classroom.

• 한국의류학회지
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• 제27권8호
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• pp.992-1003
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• 2003

This study analyzes the actual state of the working uniforms worn by burning waste workers to protect their body from the hazardous environment. Directions for improvement of the clothing fabrics is also suggested. We visited and interviewed those persons who worked in the burning waste plant in Seoul and in Gyunggi Province. 245 workers were surveyed by questionnaires, and 211 workers out of 245 were statistically analyzed. Frequencies and percentages were calculated and $\chi$$^2$ test, ANOVA and Scheffe Post hoc comparison methods were utilized to test some hypothesis. The working uniforms were classified as four general types: separate type, disposable-coverall. overall, and winter clothes. At present, the working uniforms are not suitable for the conditions which they are used. There is a lack of ventilation and an inability to absorb perspiration limited elasticity, and the uniforms are prone to static shock. The degree of satisfaction varied significantly, based on the worker's educational background and main work. However, only a small percentage of workers interviewed were satisfied with the appearance and the fit of the present working uniforms. The working duration had a negative impact on the satisfaction of the worker. This results suggest that materials, colors, design and size of working clothes must be improved. The suggestions are as follows: Firstly. to use disposable non-woven fabrics finished to increase moisture regain. Secondly. to use the bad air permeability fabrics to protect the skin from absorbtion of harmful gases, flying dust, heavy metals, etc.

• 영어어문교육
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• 제15권3호
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• pp.249-282
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• 2009

This study reports on the use of the trait and state cognitive/metacognitive strategy use and the difference of the trait/state strategy use according to students' proficiency level. First of all, for checking up the trait strategy use, 119 first-grade male students in a high school completed the questionnaire on strategies which they thought they used during a reading test. Secondly, to find out their state strategy use, students took a fifteen-item reading comprehension test, followed by filling out questionnaires on cognitive and metacognitive strategies used in the test. This study employed quantitative data analysis. The results suggested that (1) the cognitive and metacognitive strategy use in the trait and state conditions are used the most by the high proficiency group and they are correlated respectively; (2) these strategies are used with statistically significant difference according to students' proficiency level, especially to the lower level students. The highly successful group uses the cognitive and metacognitive strategy in the actual test situation more than the lower proficient group; there is no difference in trait and state strategy use.

• Human Ecology Research
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• 제52권2호
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• pp.151-164
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• 2014

This study was conducted to explore the relationships between the elderly's existential identity and psychological well-being in accordance with the elderly's age-identity so as to improve the quality of life in the elderly with prolonged lives. The data were collected from respondents who were more than 60 years in age who live in city Suncheon. The statistics used for the data analysis were reliability, frequency, percentage, mean, standard deviation, one way analysis of variance, and multiple regression. The results of this study were as follows: (1) A majority of the elderly (49.8%) acknowledged psychological age as actual age. (2) The degrees of the elderly's existential identity was 54.90, while the degree of the elderly's psychological well-being was 33.07. (3) The elderly's existential identity level was significantly affected by economic state, spouse, age-identity, monthly living expenses, household, religion, career, age, and health state. Further, the elderly's psychological well-being level was significantly affected by existential identity, economic state, spouse, health state, age-identity, monthly living expenses, household, education, career, and age. (4) The variables that affect the elderly's existential identity were age-identity, economic state, health state, religion, monthly living expenses, and career, indicating an explanatory power of 38%. Moreover the variables that affect the elderly's psychological well-being were existential identity, age-identity, economic state, health state, and monthly living expenses, explaining approximately 55% of the total variance.