• 보존과학회지
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• 제36권1호
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• pp.1-14
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• 2020

This study investigates the crystallinity distribution of ancient silk. Owing to the inherent multi-hierarchical structure of silk protein and the complicated structural changes that occur due to various burial environments, it is challenging but worthwhile to study ancient silk ageing behavior, which is based on the fact that ageing begins with a single fiber and then spreads to a whole fabric. Crystallinity was one of the most effective indicators found to reveal the ageing status of silk. Therefore, a synchrotron radiation-based X-ray diffraction(SR-XRD) method was employed to study the crystallinity distribution of single fibers of ancient silk unearthed from seven archaeological sites in China from historical periods including the warring states, Han dynasty, Song dynasty, and Ming dynasty. In comparison, the conventional X-ray diffraction method, which uses large amounts of samples, was also performed to determine the integral crystallinity of ancient silk. Thermal stability experiments by thermogravimetry(TG) as well as morphology observations by scanning electron microscopy(SEM) and optical microscopy(OM) all confirmed the deterioration of ancient silk. Moreover, the ageing mechanism of ancient silk was proposed with the assistance of an artificial ageing study. The results confirmed the effectiveness of SR-XRD as an ageing indicator, revealing the crystallinity distribution. This research could provide motivation to determine the deterioration status of ancient silk, and would also aid in explaining the fragility of ancient silk due to ageing.

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.2077-2081
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• 2005

A symmetry breaking nonlinear fluid flow in a two-dimensional wall-driven square cavity taking symmetric boundary condition after some transients has been investigated numerically. It has been shown that the symmetry breaking critical Reynolds number is dependent on the time history of the boundary condition. The cavity has at least three stable steady state solutions for Re=300-375, and two stable solutions if Re>400. Also, it has also been showed that a particular solution among several possible solutions can be obtained by a controlled boundary condition.

• 한국군사과학기술학회지
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• 제8권3호
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• pp.73-82
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• 2005

This paper describes shock waveform synthesis methods for a shock response spectnlm over a short time interval with which intereference between parts within a test item is increased to perform a sufficient shock test for damage or malfunction which may be caused by the interference between parts, and a digital filter for obtaining a shock response history required for the shock waveform synthesis and a digital inverse filter for restoration by inversely using the digital filter. The time at which the maximax value occurs in the response history is detected in order to establish a delay time which is one of the parameters in the wavelet, on the condition that the natural frequency of SDOF system with a Q (quality factor) of 10 equals to the wavelet frequency of the zero delay wavelet input. A shock response spectrum over a short time interval and an abrupt change in the acceleration for an instant are illustrated as features of the synthesized waveform.

• Journal of Dairy Science and Biotechnology
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• 제23권2호
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• pp.167-178
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• 2005

• 과학교육연구지
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• 제41권1호
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• pp.60-79
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• 2017

본 연구는 공업계열 특성화고 학생들을 위한 과학기술사 수업 프로그램을 개발하고 적용함으로써 과학의 본성에 대한 이해에 미치는 교육적 효과를 조사하였다. 프로그램은 고등학교 융합 과학 및 물리 I의 교육과정을 바탕으로 6개의 과학기술사 주제로 개발되었으며, 경기도에 위치한 공업계열 특성화고 학생 290명을 대상으로 적용되었다. 본 연구의 방법은 단일 그룹 사전-사후 검사로 설계되었으며. 학생들의 과학의 본성에 대한 이해를 조사하고자 프로그램 적용 전후에 설문을 실시하여 그 검사 결과를 SPSS 23을 이용하여 통계 분석을 실시하였다. 과학의 본성에 대한 설문도구는 선행연구에서 개발된 4가지 영역의 과학의 본성 개념 틀(Lee, 2014)을 수정 보완하여 사용하였다. 본 연구의 결과는 다음과 같다. 첫째, 공업계열 특성화고 학생들의 과학의 본성에 이해에 대한 사전 사후 비교 결과, 과학기술사 수업 프로그램이 학생들의 이해에 효과가 있는 것으로 나타났다. 둘째, 과학기술사 수업 프로그램의 효과는 특성화고 학생들의 성별 및 전공에 따른 차이는 없는 것으로 나타났다. 셋째, 과학의 본성 4가지 영역간의 상관관계 분석에 의하면, 4가지 영역들은 모두 상호 높은 상관관계가 있는 것으로 나타났으며, 특히 각 개별 영역들은 모두 과학과 기술, 그리고 사회와의 상호작용에 대한 과학의 본성 측면과 상관관계가 있는 것이 발견되었다. 한편, 과학기술사 수업 프로그램은 구체적으로 어떻게 학생들의 과학의 본성에 대한 이해에 효과가 있는지에 대한 후속 연구가 필요하다.

• 한국수학사학회지
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• 제33권3호
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• pp.135-154
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• 2020

This paper tries to show the formation of 'Kyungpook School' that is a nickname given to mathematicians of Kyungpook National University (KNU). In the early period, the role of professor Park Jung-gi was the most important drive to set the research tradition. He made Korea's first english journal in mathematics, Kyungpook Mathematical Journal KMJ which became a cornerstone for students to join the international academic community. Professor Ki U-hang published the most amount of papers in Korea in 1970s and became a role model for young scholars. In this background, KNU's Topology and Geometry Research Center at KNU was chosen as the only Science Research Center in mathematics in 1989, and KNU's mathematicians could get a long-period support for capable mathematics researchers' community.

• Structural Engineering and Mechanics
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• 제52권1호
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• pp.137-147
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• 2014

The present paper deals with the first ply failure analysis of the laminated composite plates under various static and dynamic loading conditions. Static analysis has been carried out under patch load and triangular load. The dynamic failure analysis has been carried out under triangular pulse load. The formulation has been carried out using the finite element method and a computer code has been developed. The first order shear deformation theory has been applied in the present formulation. The displacement time history analysis of laminated composite plate has been carried out and the results are compared with those published in literature to validate the formulation. The first ply failure load for laminated composite plates with various lamination schemes under static and dynamic loading conditions has been calculated using various failure criteria. The failure index-time history analysis has also been carried out and presented in this paper.

• Parasites, Hosts and Diseases
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• 제40권4호
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• pp.177-180
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• 2002

Gangweon-do is known to be highly endemic area of sparganosis more than other provinces in Korea. A seroepidmiologic examination for the detection of anti-Spirometra erinacei plerocercoid IgG in serum was carried out in normal inhabitants in Hongcheon-gun, Gangweon-do. Sere were tested by enzyme-linked immunosrobent assay (ELISA) for the anti-sparganum antibodies. Positive rate for anti-sparganum antibody in 719 adults was 3.3%. Data of the questionnaire for 24 ELISA positive inhabitants revealed that 20 had a history of eating raw meat of snakes, 24 had a history of eating frogs, and 24 had a history of drinking stream water. Two positive cases had a past history of sparganosis. Two positive cases showed current symptoms of sparganosis. The data revealed that ELISA would be useful to find infected cases among normal inhabitants at sparganosis-endemic areas.

• 한국전산구조공학회논문집
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• 제32권1호
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• pp.7-16
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• 2019

본 논문에서는 해양플랜트용 매니폴드 구조물의 내진해석을 위해, 단순화 모델에 대해 응답스펙트럽해석(RSA) 및 시간이력해석(THA)을 여러 조건으로 진행하여 비교 검토하였다. 응답스펙트럼해석은 ISO19901-2에 따른 내진설계 절차를 이용하였다. 시간이력해석의 경우, 응답스펙트럼으로 가속도와 변위에 대한 지진이력을 인공적으로 만든뒤 Explicit와 Implicit 솔버를 사용하여 해석하였다. 단자유도 모델을 사용하여 해석방법을 검증하였으며, 매니폴드 구조물을 단순화한 모델에서 시간이력해석과 응답스펙트럼해석법의 차이를 분석하였다. 복잡한 실제 구조물에 대해서 직접적인 시간이력해석은 불가능하므로 응답스펙트럼해석법을 적용하였고, 단순화 모델에서 분석한 결과 차이를 활용하여 실제 구조물의 안전성을 판단하였다.

• 식품과학과 산업
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• 제42권1호
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• pp.49-56
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• 2009