• 대한기계학회논문집A
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• 제20권7호
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• pp.2174-2181
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• 1996

Equations of chordwise and flapwise bending motions of pretwisted rotatin cantilever beams are derived. The two motions are coupled to each other due to the pretwist angle of the beam cross section. As the angular speed, hub radius ratio, and pretwist angle vary, the vibration characteristics of the beam change. It is found that engenvalue loci veering phenomena and associated mode shape variations occur between two vibration modes due to the pretwist angle. The effect of the pretwist angle on the critical angular speed is also investigated.

• Structural Engineering and Mechanics
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• 제2권1호
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• pp.17-34
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• 1994

This paper proposes a new four node degenerated shell element. In the formulation of the new element, the assumed covariant shear strains are used to avoid the shear locking problem, and the assumed covariant membrane strains are applied to alleviate the membrane locking problem and also to improve the membrane bending performance. The assumed covariant strains are obtained from the covariant strain field defined with respect to the element natural coordinate system. This formulation enables us to obtain a shell element, which does not produce spurious singular modes, avoids locking phenomena, and excels in calculation efficiency. Several examples in this paper indicate that, despite its simplicity, the achieved accuracy and convergence are satisfactory.

• 자연과학논문집
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• 제18권1호
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• pp.77-90
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• 2007

This study aims to discussion the characteristics of location and spatial organization of the Byeong San confucian academy. To do this, we studied in two ways; analysis of the present conditions and photographing, research materials about the form of physical structure and review of historical documents. The result of analysis in the sight of the location and spatial structure was good matched. The spatial organization of the Byeong San confucian academy was divided into lecturing space and sacrificial space. In the Mandaeru on Byeong San confucian academy was imported borrowed scenery of surrounding landscape and while placed arranging various constituent elements of the small-scale pond and visual perception in trying to formalize the landscape. The result of this study, analysis of axis and terrace shows backgrounds of these locations shows that the political and social, economical phenomena were influenced to the locations and spatial organization of the Byeong San Confucian Academy.

• 대한한방내과학회지
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• 제19권2호
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• pp.208-218
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• 1998

To clarify the activating effects of Buthus martensi Karsch on immunological function, its effect on primary and secondary antibodies production in mice of various ages was investigated. Buthus martensi Karsch increased the number of both antibody producing cells(anti-IgM and anti-IgG producing plaque forming cells, PFC) and phagocytic activity of peritoneal macrophage. Futhermore, these phenomena were significantly increased with aging in mice. Buthus martensi Karsch also increased natural killer cell activity concerning to cancer immunology. These results suggest that Buthus martensi Karsch markedly increases the reduced activity in the elderly and activates the immune response in senescence mice.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.655-658
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• 2002

The present paper investigated the effect of ultrasonic vibrations on the melting process of a phase-change material (PCM). Furthermore, the present study considered constant heat-flux boundary conditions unlike many of the previous researches, which had adopted constant wall-temperature conditions. Therefore in the study, modified dimensionless numbers such as Stefan and Rayleigh were adopted to represent heat transfer results. The experimental results revealed that ultrasonic vibrations accompanied the effects like agitation, acoustic streaming, cavitation, and oscillating fluid motion, accelerating the melting process as much as 2.5 times, compared with the result of natural melting (i. e., the case without ultrasonic vibration). Such effects are believed to be a prime mechanism in the overall melting process when ultrasonic vibrations were applied. Subsequently, energy could be saved by applying the ultrasonic vibrations to the natural melting In addition, various time-wise dimensionless numbers provided a conclusive evidence of the important role of the ultrasonic vibrations on the melting phenomena of the PCM.

• 펄프종이기술
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• 제31권2호
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• pp.64-69
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• 1999

Drainage phenomena on the conventional fourdrinier table can be divided into two distinct zones based on the drainage mechanisms involved. In the forming zone, natural drainage is the principal water removal mechanism, while in the vacuum zone vacuum dewatering displaces water in the wet sheet with air. In this study to investigate the influence of polyelectrolyte addition on natural and vacuum dewatering a vacuum drainage tester was developed and used. Addition of PAM decreased the dryness of the wet sheet after vacuum dewatering since substantial reduction in vacuum level occurred due to flocculation of fibers. Addition of PAM, however, increased the wet web dryness when the fines content of the stock is greater than 35% indicating the presence of fines reduced the air permeability of the wet web to increase its response to vacuum dewatering. On the other hand, PEI, which flocculates the fibers and fines via patch formation, showed little impact on the drainage characteristics of the stocks.

• 대한기계학회논문집
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• 제18권2호
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• pp.372-379
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• 1994

In this study, the describing function is adopted to represent nonlinearity in the system equations. The compliance can be obtained by solving nonlinear simultaneous algebraic quations for multi-degrees-of-freedom system with multinonlinearities. When the technique is applied, the nonlinearity of the system can be identified from the compliance which is obtained from the sinusoidal excitation of the system. By employing the describing function in the Building Block Analysis, we can extensively develop the BBA into investigation of the continuous systems with nonlinearities. The evaluated compliance can quantitatively show the effects of nonlinearity such as the transfer of the natural frequency, the variance of the compliance at the natural frequency, and the jump phenomena which occur during sweeping of the excitation frequency.

• The International Journal of Costume Culture
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• 제9권2호
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• pp.83-93
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• 2006

This study aims to analyze the hair styles featured in the collections from S/S season of 1995 to F/W season of 2004 both qualitatively and quantitatively by using content-analytical methods. This study was able to form a classifying system that divides hair styles into those artificial and those natural through systematic and scientific research. The resulting system, in turn, broadened the basis for understanding modern fashion and hair style expressions. In addition, by analyzing design-related characteristics, certain expressive techniques employed, and trends in detail, this study contributed to establishing the hair styles, which form part of socio-cultural phenomena, as an academic subject.

• 한국초등과학교육학회지:초등과학교육
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• 제18권2호
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• pp.35-46
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• 1999

The most of elementary school science textbook contents are composed of observation and experiment activities. When students study natural phenomena, observation and experiment are st rongly emphasized to improve understanding of scientific concepts and inquiry abilities. The purpose of this study is deep understanding about experimental science classes. This ethnographic study is conducted by observations of experimental science classes in natural setting and interviews of teachers, students of the 5th grade. The conclusions of this study are as follows: First, the general process of the elementary science experimental classes is 'identifying learning purposes -1 planning experiments -1 predicting the results -1 experimenting-t summarizing the results.' The experiments are conducted by group activities and the teachers conceived that the me st difficult step considered by students is 'planning experiments'. Second, students like hands-on activities, but they feel difficulty on less guided experiments. Students perform results oriented-activities. Third, in group activities, students prefer to work with the same gender or collaborative peers.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 추계학술대회
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• pp.474-476
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• 2018

현재 기후 변화를 비롯한 여러 자연재해 및 여러 재해로 인해 막대한 손실을 가져오고 있으며, 이러한 자연재해는 원천적 차단은 어렵다. 그러나 이런 재난 현장의 정보를 실시간으로 수집하여 빠른 시간내에 피해를 줄이기 위한 방안으로 본 연구에서는 ICT 기술을 접목하여 대응전략을 구사하며, 미래 유비쿼터스 사회를 대비하기 위한 USN 기술을 응용한 모델이 필요하여 제안하고자 한다.