• Structural Engineering and Mechanics
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• 제54권3호
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• pp.597-605
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• 2015

In this study, linear vibrations of an axially moving beam under non-ideal support conditions have been investigated. The main difference of this study from the other studies; the non-ideal clamped support allow minimal rotations and non-ideal simple support carry moment in minimal orders. Axially moving Euler-Bernoulli beam has simple and clamped support conditions that are discussed as combination of ideal and non-ideal boundary with weighting factor (k). Equations of the motion and boundary conditions have been obtained using Hamilton's Principle. Method of Multiple Scales, a perturbation technique, has been employed for solving the linear equations of motion. Linear equations of motion are solved and effects of different parameters on natural frequencies are investigated.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.990-993
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• 2005

This paper presents new results on designing a robust adaptive direct controller for a class of non-linear first order systems. The designing method based on the use of dead zone in the parameters' update law. It is shown that the size of the dead zone does not depend on the upper bounds of the disturbances. That means that even if the bounds are large, the tracking error will always converge to a set of the dead zone size. However, in the ideal case, when the exogenous signal functions and the function represents un-modeled dynamics of the systems equal to zero, the proposed controller does nt mean the convergence to zero of the tracking error. Computer simulation results show the effectiveness of the controller in dealing with the stated problems.

• Nuclear Engineering and Technology
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• 제46권5호
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• pp.719-724
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• 2014

During the development process of a thermal-hydraulic system code, a non-regression test (NRT) must be performed repeatedly in order to prevent software regression. The NRT process, however, is time-consuming and labor-intensive. Thus, automation of this process is an ideal solution. In this study, we have developed a program to support an efficient NRT for the SPACE code and demonstrated its usability. This results in a high degree of efficiency for code development. The program was developed using the Visual Basic for Applications and designed so that it can be easily customized for the NRT of other computer codes.

• Structural Engineering and Mechanics
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• 제44권5호
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• pp.681-704
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• 2012

The dynamic response of Euler-Bernoulli beams to resonant harmonic moving loads is analysed. The non-dimensional form of the motion equation of a beam crossed by a moving harmonic load is solved through a perturbation technique based on a two-scale temporal expansion, which permits a straightforward interpretation of the analytical solution. The dynamic response is expressed through a harmonic function slowly modulated in time, and the maximum dynamic response is identified with the maximum of the slow-varying amplitude. In case of ideal Euler-Bernoulli beams with elastic rotational springs at the support points, starting from analytical expressions for eigenfunctions, closed form solutions for the time-history of the dynamic response and for its maximum value are provided. Two dynamic factors are discussed: the Dynamic Amplification Factor, function of the non-dimensional speed parameter and of the structural damping ratio, and the Transition Deamplification Factor, function of the sole ratio between the two non-dimensional parameters. The influence of the involved parameters on the dynamic amplification is discussed within a general framework. The proposed procedure appears effective also in assessing the maximum response of real bridges characterized by numerically-estimated mode shapes, without requiring burdensome step-by-step dynamic analyses.

• 대한수학회보
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• 제50권2호
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• pp.649-657
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• 2013

Let R be a commutative Noetherian ring, I an ideal of R and T be a non-zero I-cofinite R-module with dim(T) ${\leq}$ 1. In this paper, for any finitely generated R-module N with support in V(I), we show that the R-modules $Ext^i_R$(T,N) are finitely generated for all integers $i{\geq}0$. This immediately implies that if I has dimension one (i.e., dim R/I = 1), then $Ext^i_R$($H^j_I$(M), N) is finitely generated for all integers $i$, $j{\geq}0$, and all finitely generated R-modules M and N, with Supp(N) ${\subseteq}$ V(I).

• 한국정밀공학회지
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• 제12권3호
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• pp.23-31
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• 1995

The sending characteristics of the non-contact type displacement transducers can affect the performances of the magnetic bearing systems when they support the rotating shaft. The probe type displacement sensor detects not only the displacement of the rotor at the sensing position but also the surface irregularitis of the rotor such as surface roughnessand roundness errors. If there exist such measuring errors, the magnetic bearing can not apply proper force against the rotor displacements for the detected signal is the input to the magnetic bearing controllers. The cylindrical shape capacitive transducer can detect the rotor displacement by the integral sum of the charges which are formed between the sensor plates and rotor so that it can reduce the detecting errors induced by the surface irregularities of the rotor. By theore- tical analysis, we compared the sensing characteristics of the cylindrical shape capacitive transducers for the rotors that have some sinusoidal irregularities with that of the ideal probe type displacement transducers.

• 센서학회지
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• 제8권5호
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• pp.368-376
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• 1999

본 논문에서는 머리빗형 액튜에이터의 제작 공정 중에서 RIE 식각 공정시 발생하는 식각의 비등방도의 변화에 의해서 머리빗형 액튜에이터의 스프링 상수, 공진 주파수, 정전 구동력 과리고 진동자 변위 등에서 발생하는 동작 특성이 설계 값으로부터 변화되는 것을 예측하였다. 이를 위해 $6\;{\mu}m$ 두께의 폴리실리콘에 대한 RIE 식각 실험을 수행하여 RF power, $Cl_2$ 유량 그리고 챔버내 압력에 따른 비등방도를 측정하였다. 실험 결과에서 RF Power, $Cl_2$ 유량, 그리고 챔버내 압력이 증가할수록 비등방도 감소하였다. 이러한 비등방도 감소에 따른 머리빗형 구조물의 동작 특성을 세 가지 다른 지지빔의 경우에 대해 예측하였는데 세 가지는 fixed-fixed, crab-leg, 그리고 double crab-leg 구조이다. 비등방도가 감소함에 따라 즉, 지지빔의 단면이 직사각형이 아니고 사다리꼴이 되면서, 머리빗형 액튜에이더의 스프링 상수, 공진 주파수, 그리고 정전 구동력은 감소하였지만 질량체의 변위는 증가하였다. 그리고 세 가지 구조물 중에서 double crab-leg 지지빔을 갖는 머리빗형 액튜에이터의 특성이 비등방도에 의해 가장 큰 영향을 받는 것으로 나타났다.

• 종양간호연구
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• 제9권2호
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• pp.95-103
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• 2009

Purpose: The purpose of this study was to examine nursing students' attitude toward death and perception on hospice care. Methods: The survey was performed with 277 nursing students in three universities in Daegu and Busan. The data was collected by questionnaires and were analyzed using descriptive statistics. Results: Regarding the attitude on death, 93.9% of the subjects had ever thought about death. They worried about separation and sadness with family (39.7%). About half (48.7%) of the subjects considered death as a final process of the life. With regard to the perception of hospice, 93% of the subjects heard about hospice through books or nursing courses (83.8%). The best hospice management institution was considered the one run by religious groups or non-profit organizations with government support (33.9%). Ideal model of hospice setting in Korea was hospital or institution specialized with hospice care (47.7%). The barriers the subjects thought to effective hospice care in Korea was the lack of the public consensus on the need for hospice program (37.9%). The average perceptions about the purpose of hospice care was 4.38, whereas, the average of the need of hospice care was 4.06. Conclusion: The findings of the study provides the basis for expanding nursing practice and education related to hospice care.

• 한국응급구조학회지
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• 제14권3호
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• pp.29-40
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• 2010

Purpose: We investigated the motivation of selecting major, the satisfaction of major and the view on occupation of emergency medical technology (EMT) students. The results of study will be used to increase the satisfaction of major of university students. Also, it can be used to support decision of major for high school students. Method: We conducted 1,586 surveys from 665 students at six four-year colleges and 921 students at seven three-year colleges. Our research period was from Aug. 27th to Oct. 31st in 2010. The surveys were analyzed by SPSS 18.0 using description statistics, t-test, ANOVA, Scheffe and Pearson correlation coefficient. Result: In our study, the motivation of selecting major is 35.8% of students selected 'good employment prospects', satisfaction of major's $M{\pm}SD$ is $3.15{\pm}.486$, adaptation of major's $M{\pm}SD$ is $3.11{\pm}.472$. The satisfaction of major show difference (t = 4.548 p = .000) by sex, also the adaptation of major show difference (t = 2.279, p = .023) by sex. The satisfaction of major show first grade students higher (F = 3.605, p = .013) than fourth grade students at four-year colleges. If satisfaction of major is high, accumulation evaluation score is high (F = 3.276, p = .011), too. Clinical practice experienced students was higher (t = -2.878, p = .004) than non experienced it satisfaction. In view of occupation, ideal job's factors and actual job's factors a lot of students selected 'aptitude'. Also, there is a statistically significant correlation (r = .618, p = .000) between the satisfaction of major and the adaptation of major. High satisfaction indicates high adaptation of major. Conclusion: In our study satisfaction of major and adaptation of major was very high score. EMT students concern about employment prospects at most. It is inferred that they select job which match with one's aptitude. We can suppose that students select major as a tool for employment by seeing result that a lot of students consider employment prospects at most when they select major. A method to improve the satisfaction and adaptation of major should be developed by realizing problems which occur the dissatisfaction of major. Also, there as on why students conflict between ideal and actual job should be revealed. There as on seems students want stable occupation in unstable job market situation. Therefore, the expansion of job matching aptitude and being stable should be processed. Finally, university should actively support the method that help to finding jobs for student by identifying job preparation of students.

• 대한가정학회지
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• 제40권5호
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• pp.195-210
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• 2002

The purpose of this study were to find out the difference of needs of caring between care-givers and non care-givers, and to suggest the way of lessening vigorous task of care-givers for the elderly with dementia. Data were collected from 130 nationwide respondents intentionally divided into two groups; care-givers and non care-givers in the middle aged with middle and upper income. Collected data were analyzed by frequency, percentage, t-test using SPSS package. Since the result of survey, unexpectedly, showed no difference between two groups, it could be explained as that these two groups commonly had same needs of caring for the elderly with dementia. Major findings were as follow; 1) Most Koreans stiff thought family should be the main care-giver for the elderly with dementia prior to nation or society. 2) Responsibility of caring for the elderly with dementia would be better to be shared with children instead of focusing to a child. 3) They thought ideal residential facilities for the elderly with dementia were small-scale professional dementia facility(group home) rather than home or general elderly housing. 4) Professional dementia care hospital was one of the most needed facilities for the elderly with dementia, followed by short-stay and dar-care center. 5) It was revealed care-giving task was vigorous showing that most care-givers spent 1-5 hours a day for caring, while 13% of respondents spent 11-24 hours a duty. 6) 90% of care-givers took the responsibility of main care-giver because of duty of offsprings or spouses, and wanted to be free from their current circumstances. From the result of this survey researchers would like to suggest the establishment of diverse facilities for professional dementia care to lessen the caring burden for the elderly with dementia: group home, chronic hospital, short-stay, day-care center. Financial support from the government for the housing renovation of the caring families should be considered seriously afterward. It is needed to give the opportunity to select proper paid dementia care facilities according to their income and situation of household.