• Transactions of the Korean Society of Mechanical Engineers
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• 제16권9호
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• pp.1711-1721
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• 1992

A nonlinear dissipative dynamical system can often have multiple attractors. In this case, it is important to study the global behavior of the system by determining the global domain of attraction of each attractor. In this paper we study the global behavior of a forced beam with two mode interaction. The governing equation of motion is reduced to two second-order nonlinear nonautonomous ordinary differential equations. When .omega. /=3.omega.$_{1}$ and .ohm.=.omega $_{1}$, the system can have two asymptotically stable steady-state periodic solutions, where .omega./ sub 1/, .omega.$_{2}$ and .ohm. denote natural frequencies of the first and second modes and the excitation frequency, respectively. Both solutions have the same period as the excitation period. Therefore each of them shows up as a period-1 solution in Poincare map. We show how interpolated mapping method can be used to determine the two four-dimensional domains of attraction of the two solutions in a very effective way. The results are compared with the ones obtained by direct numerical integration.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제23권12호
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• pp.41-47
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• 2009

In this paper, authors performed improvement of control characteristics of an attraction type magnetic levitation system. The attraction type magnetic levitation system has an inherent instability in the system, therefore its controller must have not only proportional-integral gain but also differential gain additionally. In this paper, authors were proposed control algorithm using disturbance observer(DOB) on feedback signal. The computer simulation and experiments were performed for its verification.

• The Korean Journal of Cytopathology
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• 제5권1호
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• pp.46-51
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• 1994

Fine needle aspiration cytologic features of a case of insular carcinoma of the thyroid in a 23-year-old woman who presented a palpable neck mass is described. The aspirate showed cellular smear arranged in trabeculae, solid or loose clusters, and microfillicles in necrotic background. The tumor cells had uniform, small round, hyperchromatic nuclei. The chromatin was finely granular, and nuclear membrane was smooth. Nucleoli were not discernible. Nuclear pleomorphism was minimal. The cytoplasm was usually scanty, pale, poorly outlined, and almostly amphophilic. Sometimes paranuclear cytoplasmic vacuoles were noted. final diagnosis was confirmed by total thyroidectomy as insular carcinoma.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 한국안전학회 1997년도 추계 학술논문발표회 논문집
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• pp.245-250
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• 1997

오늘날 정전기에 의한 미립자 오염은 반도체 공정의 미세화기술에 대해 큰 장해가 되는 것은 물론이거니와 약간의 미립자에 의한 오염이라 하더라도 제품의 특성에 악영향을 주는 원인이 된다. 정전기는 공기청정화 기술의 하나로써 응용되고 있는 반면 크린룸 중에서 대전물체가 존재하면 이것에 분진이 흡인되어 부착하기 때문에 오염의 원인이 되기도 한다. (중략)

• The Journal of the Korea Contents Association
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• 제16권5호
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• pp.290-297
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• 2016

This study analyzed the features of the nodules requiring a fine needle aspiration, which were found in thyroid ultrasonography of the employee health check-up examinees. Based on the fine needle aspiration results, over 1 cm nodules or those implying malignancy on the ultrasonography were categorized into the 1st group. Whereas, regardless of the size the fine needle aspiration results implying malignancy on the ultrasonography were categorized into the 2nd group. In the 1st group, 15.8% were malignant, and in the 2nd group, 28% were malignant. The findings implying malignancy were statistically significant. However, even though the nodules were larger than 1 cm, when the nodules were not accompanied by a high risk factor and showed a spongiform structure in the ultrasonographic results, most of them were benign, and a fine needle aspiration was not required. The ultrasonographic findings are important rationales in making a decision on whether or not a fine needle aspiration is required for thyroid nodules. Currently, the fine needle aspiration for thyroid nodules is commonly performed when the size of the nodule is larger than 1 cm, even though it has a spongiform structure, to relieve the patient's anxiety. However, if ultrasonographic findings of thyroid are correctly understood in differentiating malignant from benign nodules, unnecessary fine needle aspiration can be avoided.

• 대한세포병리학회:학술대회논문집
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• 대한세포병리학회 1993년도 제7차 춘계학술대회 초록집
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• pp.20.2-21
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• 1993

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• 제13권2호
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• pp.79-90
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• 2018

A wide range of challenges and obstacles still exist for "mumpreneurs" in creating or developing their business ventures. It is important to investigate the factors regarding why many mothers choose to become self-employed and partially abandon the benefits offered by traditional employment. This study focus on the individual, but an implied positive relationship also exits between motivational factors and mumpreneurs in Korea. Thus, four factors in this study - push, pull, environmental, and financial factor - raise the practical implications regarding the motivational factors of women entrepreneurial challenges in Korea. This study's findings also consider the nature and changes of Korean mumpreneurs' motivational factors, their challenges, and attitudes as business owners in Korean labor markets. This study's findings suggest that a combination of push and pull factors could similarly trigger new business ownership. The empirical contrast in such variables as motivations or barriers to mumpreneurship, in realities provide a superior understanding of women's tendency or willingness toward business creation, as they struggle to survive in the Korean labor market. They tend to start their own businesses to gain more responsibilities in both work and their families, and want to manage their own lives to contribute as capable members of society. Therefore, any Korean mother, regardless of any industry-specific experience, wants to use entrepreneurship as a shortcut to satisfy her need for self-fulfillment. The general motivational factors for becoming a mumpreneur exist among both external and internal situations. The circumstances beyond their control, such as job termination or unemployment, compel these mothers into the workforce due to their responsibility toward their families, but they simultaneously dream of self-achievement and development. Most mumpreneurs in Korea also want to demonstrate their potential and achieve societal recognition as well as increase in property.

• 대한세포병리학회:학술대회논문집
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• 대한세포병리학회 1991년도 제5차 춘계학술대회 초록집
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• pp.10.2-11
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• 1991

• Journal of the Korean Society for Precision Engineering
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• 제20권4호
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• pp.76-83
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• 2003

To cope with stringent performance targets requested in many fields spanning the whole range of industry, the driver is necessary to realize large dynamic range as well as nano resolution, manipulate the mover orientation without additional driver, and be suitable for clean environment. As one of those purposes, authors have developed the planar precision stages with the integrated operating principle of levitation and propel. In this paper, we discuss potential of magnetic suspension technology by comparing various features of non-contact planar stages, that is, repulsive type of surface actuator and attractive type of surface actuator.

• Proceedings of the KIEE Conference
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.917-919
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• 2002

가동자를 중간에 두고 양측의 고정자에서 발생하는 흡인력을 서로 상쇄시킬 수 있는 기계적 구조인 양측식 리니어 펄스 모터(double side linear pulse motor)는 편측식 리니어 펄스 모터(single side linear pulse motor)에 비해 구동시 지지기구의 부담을 경감시키고, 발생 추력을 증대시킬 수 있다. 이러한 양측식 리니어 펄스 모터는 가동자를 사이에 두고 상부와 하부의 고정자를 각각 교대로 여자시키는 1상 바이폴러 여자방식과 두 고정자를 동시에 여자시키는 2상 바이폴러 여자방식이 가능한데 보다 제어정밀도를 향상시키는 위치제어 시스템을 구성하기 위해서는 두 여자방식에 의한 특성 비교가 필요하다. 따라서 본 연구에서는 양측식 리니어 펄스 모터의 1상 바이폴러 여자와 2상 바이폴러 여자시, 자로 분포의 특성을 3차원 유한요소법으로 해석하여 그 특성을 비교 검토하였다.