• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.122-125
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• 2005

A novel torque ripple reduction scheme of single-phase SRM with high power factor is presented. The proposed SRM drive has one additional active switches in the conventional asymmetric inverter. In order to get a higher power factor, the source current is controlled sinusoidal, And additional excitation current is added from charge capacitor due to torque ripple reduction. The switching period of source and charged voltage is controlled properly to get unity power factor and torque ripple reduction. The characteristics and validity of the proposed scheme is discussed with some simulation results.

• 한국소음진동공학회논문집
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• 제26권3호
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• pp.235-241
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• 2016

Underwater weapon system is required to structurally strong material, since as it is directly exposed to external shock. It should also be using the lightweight material in order to take advantage of buoyancy. Composite materials meet these requirements simultaneously. Particularly in the case of submarine, composite materials are widely used. It is important to have a high strength enough to be able to withstand external shock, but it is also important to attenuate it. In a method for the shock damping, viscoelastic damping materials are inserted between the high strength composite material as a sandwich structure. Shock attenuation can be evaluated in the loss factor. In ASTM(American Society of Testing Materials), evaluation method of the loss factor of cantilever specimens is specified. In this paper, mode tests of the cantilever are performed by the ASTM standard, in order to calculate the loss factor of the viscoelastic damping material by the specified expression. Further, for verifying of the calculated loss factor, mode test of compound beams is carried out. In addition, the characteristics of the material were analyzed the effect on the loss factor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.130-132
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• 2007

Recently, regulation for THD(Total Harmonic Distortion) such as IEC 61000-3-2, IEEE 519 is being reinforced about a product which directly connects to AC line in order to prevent distortion of common power source in electronic equipment and electrical machinery. In order to satisfy these regulations, conventional circuits were used two-stage structure attached power factor correction circuit at ahead of converter but this method complicate the circuit and then a number of element increases thereupon the cost of production rises. In this paper, we propose a high efficiency single-stage 300W PFC flyback converter, that improved power factor and efficiency than conventional two-stage power module.

• 전기학회논문지
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• 제56권11호
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• pp.2010-2016
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• 2007

PID control is windely used to control stable processes, However, its application to integrating processes is less common. In this paper, we proposed a stable PID controller tuning method for integrating processes with time delay using model reduction method. For proposed model reduction method, it disconnect an integrating factor from integrating processes and reduces separate process using reduction method. and it connect an integrating factor to reduced model. We can obtain stable integrating processes using P controller in inner feedback loop and PID tuning is then used to cancel the pole of the feedback loop. This guarantees both robustness and performance. Simulation examples are given to show the good performance of the proposed tuning method comparing with other methods.

• 한국학교수학회논문집
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• 제15권3호
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• pp.487-509
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• 2012

본 연구는 수학 교육의 가장 큰 이슈 중 하나인 수학에 관한 정의적 영역에서의 향상에 기여하고자 중 고등학교 학생들의 수학 불안에 영향을 미치는 배경 변인에 관한 연구를 실시하였다. 연구 결과 중학교 학생들은 고등학생들보다 더 높은 수학 불안을 나타냈는데, 특히 '외적 요인'과 '학습 방법 요인'에 따른 불안 수준이 높았다. 또한, 여학생보다는 남학생들에게 전반적으로 높은 수학 불안이 나타났으며, 두 집단의 학생들 모두 '외적 요인'과 '학습 방법 요인'에 따른 불안 수준이 더 높게 나타났다. 그 외에도 사교육 시간이 증가할수록 학생들의 수학 불안 수준은 증가하였으며, '시험 및 성적 요인'에서는 자기주도적 학습 시간이 낮은 집단이 나머지 두 집단에 비해 수학 불안의 수준이 높게 나타났다. 수학 불안검사의 4가지 하위 요인 중 학생들은 전반적으로, '시험 및 성적 요인'에 대한 불안이 가장 낮게 나타났고, '수학 외적 요인'에 대한 불안이 가장 높은 것으로 나타났다.

• 한국조리학회지
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• 제14권3호
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• pp.123-135
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• 2008

The purpose of this study is to investigate the priority order in the factors influencing college choice of students who are majoring in culinary art in Chungcheong-do. For the study, we set the decision-making factors of upper hierarchies and nineteen bottom hierarchies based on the literature review and employed the analytical hierarchical process(AHP). As a result, the first considering factor among 4 upper hierarchies for college choice was the educational environments of the department(0.378). The next came in the order named as follows: college and university grade(0.263), the educational environments of colleges or universities(0.244), recommendation(0.115). The first considering factor among the educational environments of the department was the aptitude for the major(0.323). The first considering factor in college and university grade was the entrance competitive rate(0.397). The first considering factors among the educational environments of the colleges or universities were scholarships and tuition fees(0.325). The first considering factor in recommendation was the recommendation of a high school teacher(0.295). This results of this study will contribute to the development of colleges and universities under the turbulent changes of educational environments.

• 대한간호학회지
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• 제35권6호
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• pp.1091-1100
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• 2005

Purpose: The purpose of this study was to develop an instrument to measure nursing professional values. Method: Forty preliminary items were selected by classifying 223 basic items extracted via a literature study and in-depth interviews of subjects and testing the relevance of their contents. In order to verify the reliability and relevance of the preliminary instrument, data was collected from 504 nurses in 3 general hospitals. Result: As a result of the item analysis, 29 items were selected from a total of 40 items. Five factors were extracted by factor analysis, and the total variance was $51.5\%$. For the explanation of variances by factors, the 1 st factor, 'self-concept of the profession' accounted for $14.8\%$, the 2nd factor, 'social awareness' $12.1\%$, the 3rd factor, 'professionalism of nursing' $9.8\%$, the 4th factor, 'the roles of nursing service' $9.1\%$, and the 5th factor, 'originality of nursing', $5.6\%$. Cronbach's Alpha of those 29 items was .9168, which was high. Conclusion: This paper is meaningful in a way that it developed a tool capable of measuring nursing professional values, which reflects the characteristics of our country. In order to re-verify the relevance and stability of this tool, it is necessary that comparative studies should be conducted.

• 한국식품영양학회지
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• 제21권1호
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• pp.97-105
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• 2008

An IPA model was used to evaluate customer service encounters at a large food court; also the gaps between importance and performance from were also evaluated from both perspectives. The findings of this study will be applied in order to improve service quality at various large food service operations. A total of 298 customers from a large shopping mall food court completed the study questionnaire, asking them to evaluate the important and performance attributes of service. Seven underlying dimensions were identified and labeled by factor analysis: factor 1 was "safety": factor 2 "time": factor 3 "atmosphere": factor 4 "quality of food": factor 5 "menu attributes": factor 6 "comfort": and the last and seventh factor was "comprehension". As a result of IPA analysis the overall mean scores between the importance attributes and performance attributes showed significant differences by independent t-tests(p<0.001). Quadrant I was classified with unnecessary items including interior design, proper lighting, suitable chairs, and proper room temperature. In quadrant II thirteen variables showed high scores for both importance and performance, such as various menu choices, hygienic food, dishes, chairs, food court, kitchen, and employees; proper ventilation, employee kindness, waiting time to order, and received food; automatic system for ordering-serving. Quadrant III included eight variables identified as low priority, including appearance of food, nutrient content of food, proper portions, new menu, proper music, proper location of cashier, services for children and efficiency of movement. In quadrant IV six variables were included as areas to focus management's efforts, such as food taste, proper food temperature, use of safe food materials, maintenance of food quality, existence of preferred foods, and proper food prices. These results suggest that food court customers have interests that are distinct from restaurant customers and may need to be treated differently. It is anticipated that this data will be useful to the foodservice industry in order to segment customer characteristics by different dinning behaviors.

• 한국의류산업학회지
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• 제4권6호
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• pp.534-543
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• 2002

The purpose of this study was to identify the body proportions of girls in middle and high school who have been a major sales target of clothing manufacturers and thus to provide the basic information on the proportion of human body, which is essential for manufacturer to produce clothing and for individual consumers to select right apparels to wear and purchase. The subjects were 133 girls in middle school and 141 girls in high school. As measuring instruments, the Martin's anthropometer, tapelines, and belts for marking waistline were used. In order to analyze the data, t-test and factor analysis were used. The measurement of vertical distance between vertex and measuring points, showed a significant difference between the high school group and middle school group in every item. In the comparison of eight head proportion between the two groups, middle school students had 7.2 head proportion while girls in high school had 6.9 head proportion in detail. The factor analysis of major divided body parts of the two groups indicated that waist-hip and hip-crotch, constituting lower trunk together, vertex-apex nasi, and apex nasi-back neck point, constituting head together, back neck point-spina scapula and spina scapula-waist, constituting posterior of upper body together, and mentum-bust point and bust point-waist, constituting anterior of upper body together, were in inverse proportion.

• Journal of the Optical Society of Korea
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• 제17권5호
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• pp.415-422
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• 2013

White-light phase-shifting interferometry (WLPSI) is widely recognized as a standard method to measure shapes with high resolution over a long distance. In practical applications, WLPSI, however, is associated with some degree of ambiguity of its phase, which occurs due to a phase delay, which is the offset between the phase of the fringes and the fringe envelope peak position. In this paper, a new algorithm is proposed for the determination of a fringe order suitable for samples in which the phase delay mainly occurs due to noise, diffraction and a steep angle. The concepts of the decouple factor and the connectivity are introduced and a method for calculating the decouple factor and the connectivity is developed. With the phase-unwrapping procedure which considers these values, it is demonstrated that our algorithm determines the correct fringe order. To verify the performance of the algorithm, a simulation was performed with the virtual step height under noise. Some specimens such as step height standard and a column spacer with a steep angle are also measured with a Mirau interference microscope, after which the algorithm is shown to be effective and robust.