• 한국수학사학회지
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• 제19권1호
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• pp.79-90
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• 2006

본 논문은 중$\cdot$고등학교에서 특수각의 삼각비를 삼각비의 원래 기원인 기하학적 의미가 아닌 지나친 대수적 접근방법으로 지도하고 있다는 문제점으로부터 출발하여 특수각의 삼각비를 유클리드 <원론>에 기초한 정오각형과 정십각형의 작도법으로부터 유도하고자 한다. 이를 위하여 정오각형과 정십각형의 작도법을 고찰하고 이로부터 다양한 특수각을 기하적으로 유도하고 있다. 이런 기하학적 방법을 통하여 특수각의 삼각비의 기하학적 의미를 재조명하고 수학사를 활용한 삼각비의 교수방법을 제시하고자 한다.

• Steel and Composite Structures
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• 제44권6호
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• pp.789-801
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• 2022

In order to study the influence of loading angles on seismic performance of steel reinforced concrete (SRC) special-shaped columns, cyclic loading tests and finite element analysis (FEA) were both carried out. Seven SRC special-shaped columns, including two L-shaped columns, three T-shaped columns and two cross-shaped columns, were tested, and the failure patterns of the columns with different loading angles were obtained. Based on the tests, the FEA models of SRC special-shaped columns with different loading angles were established. According to the simulation results, hysteretic curves and seismic performance indexes, including bearing capacity, ductility, stiffness and energy dissipation capacity, were analyzed in detail. The results showed that the failure patterns were different for the columns with the same section and different loading angles. With the increasing of loading angles, the hysteretic curves became fuller and the bearing capacity and initial stiffness appeared increasing tendency, but the energy dissipation capacity changed insignificantly. When the loading angle changed, the ductility got better with the larger area of steel at the failure side for the unsymmetrical section and near the neutral axis for the symmetrical section, respectively.

• Kyungpook Mathematical Journal
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• 제60권2호
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• pp.375-385
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• 2020

Minkowski spaces have long been investigated with respect to certain properties and substructues such as hyperbolic curves, hyperbolic angles and hyperbolic arc length. In 2009, based on these properties, Chung et al. [3] defined the basic concepts of special relativity, and thus; they interpreted the geometry of the Minkowski spaces. Then, in 2017, E. Nesovic [6] showed the geometric meaning of pseudo angles by interpreting the angle among the unit timelike, spacelike and null vectors on the Minkowski plane. In this study, we show that hyperbolic angle depends on time, t. Moreover, using this fact, we investigate the angles between the unit timelike and spacelike vectors.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.63-68
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• 1996

In this study, the effect of tool rake angles and the change of cutting conditions on specific cutting pressure in face milling is investigated. The cutting force in face milling is predicted from the double cutting edge model in 3-dimensional cutting. Conventional specific cutting pressure model is modified by considering the variation of tool rake angles. Effectiveness of the modified cutting force model is verified by the experiments using special face milling cutters with different cutter pockets and various rake angles. From the comparison of the pressented model and the specific cutting pressure, it is shown that the axial force can be predicted by the tangential and redial forces without the knowledge of friction angle and shear angle. Also, the relation between specific cutting pressure and cutting cindition including feedrate, cutting velocity and depth of cut is studied.

• 한국정밀공학회지
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• 제14권2호
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• pp.169-177
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• 1997

In this study, investigated are the effects of tool rake angles and the change of cutting conditions on the specific cutting pressure in face milling. The cutting force in face milling is predicted from the double cutting edge model in3-dimensional cutting. Conventional specific cutting pressure model is modified by considering the variation of tool rake angles. Effectiveness of the modified cutting force model is verified by the experiments using special face milling cutters with different cutter pockets and various rake angles. From the comparison of the presented model and the specific cutting pressure, it is shown that the axial force can be predicted by the tangential force, radial force and geometric conditions. Also, the rela- tionship between specific cutting pressure and cutting conditions including feedrate, cutting velocity and depth of cut is studied.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1754-1759
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• 2007

Propagation of a mixed-mode crack in Soda-Lime silica glass using Movable Cellular Automata (MCA) method is demonstrated in this study. In MCA method, special fracture criterion is used to describe the process of crack initiation and propagation. Comparison between MCA and other crack initiation criteria results are made. The crack resistance curves and bifurcation angles under different loading angles are found. In comparisons with results of maximum circumferential tensile stress criterion, MCA result showed the sufficient agreement.

• Agribusiness and Information Management
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• 제2권1호
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• pp.15-29
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• 2010

Recently, IPTV population is growing by leaps and bounds. and We performed FGI(Focus Group Interview) with various experts related to agriculture field to establish Agriculture and Fisheries special channel. this growth has social background that is change of paradigm caused by the convergence of broadcasting, demand for Agriculture and Fisheries special channel using new media thanks to interests in Wellbeing, Green food. so we think that we need to consider the way to establish Agriculture and Fisheries special channel and its validity from all angles. that is why we are having a heated discussion with Agriculture and Fisheries marketing experts, farmer, fisher(Korean Cyber Farmer Association), broadcasting experts. Concretely, government budget is needed to establish Agriculture and Fisheries special channel, so we are just about to examine its validity and find business model. to make this discussion detailed, we made 4 subjects. First, Do we need agro-fishery products distribution channel using media? Second, After establishing of Agriculture and Fisheries special channel, how many demands will occur? Third, Should we make Agriculture and Fisheries special channel public channel? Fourth, What would be profit model of Agriculture and Fisheries special channel?

• 한국생산제조학회지
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• 제23권6호
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• pp.569-575
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• 2014

In this study, the effect of cutting edge geometry, such as helix and rake angles, on surface roughness in ball-end milling is investigated by using the Taguchi method. A set of experiments adopting the $L_{27}(3^{13})$ design with an orthogonal array are conducted with special WC ball-end mills having different helix and rake angles. Analysis of variance (ANOVA) is performed to analyze the effects of tool geometry and machining parameters, such as cutting speed, feed per tooth, and depth of cut, on surface roughness. The ANOVA results reveal that helix and rake angles are critical factors affecting surface roughness; the interaction of helix angle and cutting speed is also important. This research can contribute to novel cutting edge designs of ball-end mills and optimization of cutting parameters.

• 한국안전학회지
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• 제31권3호
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• pp.1-7
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• 2016

In this study, static and fatigue tests on the self-piercing riveted (SPR) joint were conducted using cross-shaped specimens with aluminum alloy (Al-5052) sheets. Mixed mode loading was achieved by changing the loading angles of 0, 45, and 90 degrees using a special fixture to evaluate the static and fatigue strengths of the SPR joints under mixed mode loading conditions. Simulations of the specimens at three loading angles were carried out using the finite element code ABAQUS. The fatigue specimens failed in an interfacial mode where a crack initiated at the upper sheet and propagated along the longitudinal direction and finally fractured Maximum principal stress, von-Mises effective stress failed to correlate the fatigue lifetimes at three loading angles. However, the equivalent stress intensity factor was found to be appropriate to correlate the fatigue lifetimes at three loading angles.

• 한국비블리아학회지
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• 제32권2호
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• pp.25-47
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• 2021

본 연구에서는 국가도서관통계시스템에 나타난 자료를 활용하여 다양한 각도에서 현황을 파악하고 문제점을 도출하며, 이를 기반으로 발전방안을 모색해 보고자 하였다. 첫째, 전문도서관통계를 알 수 있는 전수조사가 필요하다. 둘째, 전문도서관에 사용되는 명칭의 통일이 어느 정도 이루어져야 한다. 셋째, 전문도서관에 대한 주제분류를 제시해야 한다. 넷째, 전문도서관이 통계조사에 참여할 수 있는 적극적인 홍보와 인센티브가 필요하다. 다섯째, 전문도서관이 기타 통계로 분류되어 있는 문제의 해결이 필요하다. 여섯째, 법원도서관, 헌법재판소 도서관, 한국과학기술정보연구원 등 국가도서관 및 대형 전문도서관의 통계는 어디에서도 찾을 수 없다. 이러한 문제점을 해결하지 않는 이상 전문도서관에 대한 전체적인 평가와 국가차원의 정책제안은 의미가 없을 것으로 보인다.