• Title/Summary/Keyword: regular octagon

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A Study on the Construction of Regular Polygons in 'Method of Ruler and Compass' (`자와 컴퍼스의 방법`에 제시된 정다각형의 작도 방법 연구)

  • Han, In-Ki
    • Journal for History of Mathematics
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    • v.21 no.2
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    • pp.119-134
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    • 2008
  • In this paper we study a book 'Method of Ruler and Compass' written in Russia three hundreds years ago. In this book many construction problems related with plane figures and solid figures are solved. In this study we analyze construction method of some regular polygon(square, regular pentagon, regular octagon, regular decagon) suggested in 'Method of Ruler and Compass', give mathematical proofs of these construction.

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Numerical and Experimental Study on Motion Response of 1MW OTEC Platform (1MW OTEC 구조물의 운동 응답에 대한 수치 및 모형시험 연구)

  • Kwon, Yong-Ju;Nam, Bo Woo;Kim, Namwoo;Jung, Dong-Ho;Hong, Sa Young;Kim, Hyeon-Ju
    • Journal of Ocean Engineering and Technology
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    • v.31 no.2
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    • pp.81-90
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    • 2017
  • The 1MW OTEC (Ocean Thermal Energy Conversion) platform was designed for application in equatorial seas. In this study, the OTEC platform was investigated using numerical and experimental methods. An octagon-shaped OTEC platform was investigated using the Ocean Engineering Basin of KRISO. These experiments included various tests of regular waves, irregular waves and irregular waves with current (wave+current). The responses of the platform in regular waves showed good agreement between the numerical and experimental results, including the motion RAO, wave run up, and mean drift force. The peak period of heave and pitch motions were observed around 0.5 rad/s, and the effect of the total reflection was found under short wave conditions. The standard deviation (STD) of the platform motion was checked in irregular waves of equatorial and Hawaiian seas. The STD of the pitch was less than $4^{\circ}$ different from the operability requirement under equatorial conditions and the surge STD of the wave frequency showed good agreement between the numerical and experimental results. The STD values of the surge and pitch were increased 66.6% and 92.8% by the current effects in irregular waves, but the pitch STD was less than $4^{\circ}$ under equatorial conditions. This study showed that the STD of the surge was affected by spring effects. Thus, the watch circle of the platform and tension of the mooring lines must be evaluated for a specific design in the future.

A Study on the Tableware Design using Geometric Pattern (기하학적 형태를 활용한 테이블웨어 디자인개발 연구)

  • Ryu, Yu Li
    • Journal of Digital Convergence
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    • v.12 no.8
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    • pp.475-480
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    • 2014
  • They are used as a symbol representing some meaning of an object. Geometric patterns in the formative arts have been recasted by artists and used to express modern images. Simple shapes of geometric patterns create beauty with their outward appearance and decorated patterns. The simpleness of decorated patterns go with restrained, rational, and modern concepts. The patterns decorated with geometric patterns use geometric figures such as octagon, triangle, quadrangle, etc. and they give satisfaction to modern people. They are also regular and simple, so they can create impactive visual effects and three-dimensional space can be created with these dynamic patterns. Therefore, attractiveness of shape which gives enjoyment is also found in tableware design using geometric patterns. Using geometric patterns in tableware design is not based on a chance factor, so it is possible to objectify and reproduce the patterns. These repetitive designs can influence a lot of designers working on tableware and help improve the tableware designs. It is also considered that those designs are able to create new opportunities to produce a high value product in the ceramics industry.

Characristics and Management Plans of Myeongwoldae and Myeongwol Village Groves Located in, Jeju (제주 팽림월대(彭林月臺)의 경관특성 및 관리방안)

  • Rho, Jae-Hyun;Oh, Hyun-Kyung;Chol, Yung-Hyun;Kahng, Byung-Seon;Kim, Young-Suk
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.32 no.2
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    • pp.68-81
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    • 2014
  • This study was conducted to identify the spacialty, to illuminate the existence and values of Myeongwoldae(明月臺) and Forest Myeongwol, and to suggest the sustainable usage, preservation and management plans with the purpose of ecological and cultural landscaping characteristic and value identification. The result of the study is as follows. Castle Myeongwol and Port Myeongwol shows the status of Hallim-eup Myeongwol District which is the administrative center of western Jeju as well as is the fortress. Building Wolgyejeongsa and School Woohakdang, the head temple of education and culture, located in Myeongwol District represents the spaciality of Myeonwol-ri which was the center of education. Stand Myeongwol is one of the most representative Confucian cultural landscapes in Jeju Island and the field of communion with nature where scholars enjoy poetries, nature, changgi(Korean chess), and go in the Joseon Dynasty period. It was found that the current relics of Myeongwoldae was recovered through the maintenance project conducted by Youth Group Myeongwol composed with Hongjong-si(洪鍾時) as the center during the Japanese colonial era in 1931. It seems that the stonework of Myeongwoldae composed of three levels in the order of square, octagon, and circle based on the heaven-man unity theory of Confucianism and the octagon in the middle is the messenger of Cheonwonjibang(天圓地方), in other words, between the square-shaped earth and the circle-shaped sky. It is assumed that both Grand Bridge Myeongwol and Bridge Myeongwol were constructed as arched bridges in early days. Bridge Myeongwol is the only arched bridge remaining in Jeju Island now, which has the modern cultural heritage value. In Forest Myeongwol, 97 taxa of plants were confirmed and in accordance with 'Taxonomic Group and Class Criteria of Floristic Specific Plants', eight taxa were found; Arachniodes aristata of FD IV and Ilex cornuta, Piper kadsura, Litsea japonica, Melia azedarach, Xylosma congestum, Richosanthes kirilowii var. japonica, Dichondra repens, Viburnum odoratissimum var. awabuki of FD III. Otherwise, 14 taxa of naturalized plants including Apium leptophylihum which is imported to Jeju Island only were confirmed. In Forest Myeongwol, 77 trees including 41 Celtis sinensis, 30 Aphananthe aspera, two Wylosma congestum, a Pinus densiflora, a Camellia japonica, a Melia azedarach, and an Ilex cornuta form a colony. Based on the researched data, the preservation and plans of Myeongwoldae and Forest Myeongwol is suggested as follows. Myeongwoldae, Bridge Myeongwol, and Forest Myeongwol should be managed as one integrated division. Bridge Myeongwol, an arched bridge which is hard to be found in Jeju Island is a high-standard stonework requiring long-term preservation plans. Otherwise, Grand Bridge Myeongwol that is exposed to accident risks because of deterioration and needs safety diagnosis requires measures according to the result of precise safety diagnosis. It is desirable to restore it to a two-sluice arched bridge as its initial shape and to preserve and use it as a representative local landmark with Stand Myeongwol. In addition, considering the topophsis based on the analysis result, the current name of Jeju Special Self-Governing Province Monument No. 19 'Myoengwol Hackberry Colony' should change to 'Myeongwol Hackberry-Muku Tree Colony'. In addition, the serial number system which is composed without distinction of hackberry and muku tree should be improved and the regular monitoring of big and old trees, specific plants, and naturalized species is required.