• 한국수학교육학회지시리즈D:수학교육연구
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• 제14권3호
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• pp.211-218
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• 2010

It is a truism that mathematics is about relations (cf. [Halford, G. S. (1999). The properties of representations used in higher cognitive processes: Developmental implications. In: Sigel, I. E. (Ed.), The Development of Mental Representation: Theories and Applications (pp. 147-168). Mahwah, New Jersey: Erlbaum]). In this article we are considering few problems related to the Viviani's and Routh's Theorems. All Problems are connected by the relation which exists between the distances of the point inside the triangle to it sides. We show how reasoning about the relations could lead the student's problem solving process and give easy to understand solutions of the problems. Among the problems being considered are the proof of the Converse to Viviani's Theorem, the formulas for areas of all figures formed by the sides of triangle and its cevians.

• 소음진동
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• 제10권2호
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• pp.319-324
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• 2000

This paper shows hot to model the submerged elastic structures and adequate analysis tools for modal behavior when using finite element and boundary element method. Four different cases are reviewed depending on the location of the water and air. First case is that structures are filled with air and water is located outside. Second case is opposite to case one. These cases are solved by direct approach using collocation procedure. Third case is that water is located both sides of structures. Last case is that air is located both sides. These cases are solved by indirect approach using variational procedure. As analysis tools harmonic frequency sweep analysis and eigenvalue iteration method are selected to obtain the natural frequencies of vibrating submerged structures depending on the cases. Results are compared with closed form solutions of submerged spherical shell.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.960-963
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• 2007

In this paper, development of the noise barrier analysis program is described. The upper part of barriers may have complicated shapes like "Y", "T", inverted L, and other shapes. The insertion loss of the barrier is predicted by summation of multiple diffractions occurring at top edge points. In addition, the program considers diffractions occurring at both vertical sides, while reflections from ground due to mirror images are also included. In case of two barriers at both sides of the road, reflections from the other side of barriers are considered, in which magnitudes are decreased by the ratio of absorption coefficient.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.42-47
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• 2007

An analytical method for the free vibration of a flexible rectangular plate in contact with water is developed by the Rayleigh.Ritz method. The plate clamped along the edges is partially contacted with water at both sides. It is assumed that the water bounded by rigid walls is incompressible and inviscid. The wet mode shape of the plate is assumed as a combination of the dry mode shapes of a clamped beam. The liquid motion is described by using the liquid displacement potential and determined by using the compatibility conditions along the liquid interface with the plate. Minimizing the Rayleigh quotient based on the energy conservation gives an eigenvalue problem. It is found that the theoretical results can predict excellently the fluid.coupled natural frequencies comparing with the finite element analysis result.

• 한국가시화정보학회지
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• 제5권1호
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• pp.37-42
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• 2007

Reverse flow occurs in a channel when there is an obstruction at the entry. However it has been shown recently that reverse flow can be realized without an obstruction, by staggering the sides of the channel and placing it at an angle of attack to the oncoming flow. In this study the latter flow is computationally investigated. Studies have been carried out for different widths (gap between the two walls forming the channel), and at an angle of attack of 30. The results have captured all the essential features of this complex phenomenon and show the time dependent pumping mechanism which leads to the occurrence of reverse flow.

• Journal of Korean Neurosurgical Society
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• 제54권3호
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• pp.265-267
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• 2013

We report a case of bilateral chronic subdural hematoma (CSDH) in a 75-year-old man after exercise using a vibrating belt machine on the head. He suffered from headache and intermittent left side numbness for ten days. He denied any head injuries except eccentric exercise using a vibrating belt on his own head for 20 days. An MRI revealed bilateral CSDH. The hematoma was isodense on the CT scan. We made burr-holes on the both sides under local anesthesia. We identified the neomembrane and dark red subdural fluid on both sides. In the postoperative CT scan, we found an arachnoid cyst on the left temporal pole. Although the arachnoid cyst itself is asymptomatic, trivial injury such as vibrating the head may cause a CSDH.

• Steel and Composite Structures
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• 제15권2호
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• pp.131-150
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• 2013

This paper presents the experimental results of axially loaded stub columns of slender steel hollow square section (SHS) strengthened with carbon fiber reinforced polymers (CFRP) sheets. 9 specimens were fabricated and the main parameters were: width-thickness ratio (b/t), the number of CFRP ply, and the CFRP sheet orientation. From the tests, it was observed that two sides would typically buckle outward and the other two sides would buckle inward. A maximum increase of 33% was achieved in axial-load capacity when 3 layers of CFRP were used to wrap HSS columns of b/t = 100 transversely. Also, stiffness and ductility index (DI) were compared between un-retrofitted specimens and retrofitted specimens. Finally, it was shown that the application of CFRP to slender sections delays local buckling and subsequently results in significant increases in elastic buckling stress. In the last section, a prediction formula of the ultimate strength developed using the experimental results is presented.

• 한국콘텐츠학회논문지
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• 제2권1호
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• pp.46-51
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• 2002

인터넷의 발전과 더불어 많은 기업이 생산성을 향상하고 경쟁적 우의를 제고하는 한편 전세계적으로 고객의 저변확대를 하고 있다. 전자상거래의 도입 .확산과 관련하여 정부가 개입해야 할 필요성은 전자상거래가 미치는 파급효과에서 찾을 수 있다. 전자상거래가 경제적으로 미치는 가장 큰 파급효과는 일반적으로 사회 전반적인 거래비용의 절감으로 보고 있다. 이러한 시점에서, 본 연구는 기업간 전자상거래의 활성화에 영향을 주는 주요성공요인 분석을 통해 정부의 주도적인 역할이 필요한 세 가지 측면의 주요성공요인을 도출하고, 각 측면에서의 정부의 역할 및 정책 방안을 제안하고 있다.

• 산경연구논집
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• 제3권2호
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• pp.23-27
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• 2012

Purpose - The objective of the paper is to explain the economy and trade development between South Korea and Shandong, strengthening logistics Industry cooperation of both sides increasingly important. Research design, data, methodology - The study conducted a survey on Shandong is the earliest economy and trade exchanges with South Korea in China. Shandong and South Korea share the similar geopolitical, the same culture and long exchange history etc. Results - This study explores current situation and existing problems the logistics cooperation between Korea and Shandong, and recommendations so as to further trade between two sides. Conclusions - Logistics cooperation of China and South Korea is an important part of the international logistics cooperation in Northeast Asian Economic Circle, and the logistics cooperation between Shandong and South Korea occupies an important position in logistics cooperation of China and South Korea.

• 대한전기학회논문지
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• 제43권6호
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• pp.906-915
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• 1994

Line-Current harmonics resulting from ac to dc power conversion interfere with power system operation and reduce power factor, hence resulting in increasing power source unnecessarily. This study describes a 3 phase phase-controlled converter eliminating low frequency harmonics in the output by inserting notches. Notch points are calculated by Newton-raphson method, The impacts of the choppings on ac and dc sides are analyzed in the steady state. Potential applications of the study are dc motor controls, high power dc power supplies for telecommunications, static var compensators and HVDC.