• 국제초고층학회논문집
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• 제8권4호
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• pp.275-281
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• 2019

The paper presents a generalization of existing analytical approaches to determine the across-wind aerodynamic damping of tall structures through the quasi-steady theory. The theory takes into account the nature of non-uniform wind, structural mode shapes and the variation of structural parameters. Numerical applications on a prototype high-rise building and a real sculptural tower point out that the common approach may be over simplified, giving rise to inappropriate predictions of the aerodynamic damping. The role of the structural mode shapes, usually being neglected for uniform structures, is then highlighted.

• 터널과지하공간
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• 제13권1호
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• pp.6-19
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• 2003

터널의 막장면 조사에서 조사결과의 객관성을 증대시키고, 지반특성에 적합한 지보패턴 및 보강공법을 제시하기 위하여 본 연구를 수행하였다. 본 연구에서는 퍼지집합이론과 뉴로퍼지기법 등을 적용한 prototype의 터널 안정성평가 시스템(NFEST)을 개발하였고, 36개의 막장관찰자료들을 대상으로 신뢰성을 평가하여 비교적 만족한 결과를 얻을 수 있었다 본 연구의 결과를 요약하면, (1) 터널 지반평가의 용이성을 위해 국내 기술자에게 익숙한 RMR분류를 근거로 12개 평가항목을 제안하였다. (2) 12개 평가항목에 의해 추론된 RMRinf값과 산술합에 의한 RMRorg값 그리고 조사자의 주관적 판단에 의한 RMRinf값 사이의 상관계수(│R│)는 각각 0.83과 0.79로 비교적 높은 상관성을 나타내었다. (3) 터널 막장면에 대한 종합적인 안정성은 RMRinf(│R│=0.7)와 암반풍화정도(│R│=0.84)에서 비교적 양호한 상관성을 나타내었다.

• 한국융합학회논문지
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• 제9권3호
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• pp.23-29
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• 2018

21세기의 새로운 지식, 기술, 능력의 요구에 따라서 새롭게 강조되고 있는 인식론적 프레임(Epistemic Frame)을 컴퓨터를 통해서 학습할 수 있는 교육프로그램에 대한 관심이 높아지고 있다. 그러나 인식론적 프레임의 이론적 모형은 컴퓨터를 활용한 교육프로그램에 적합하게 적용하기에는 아직 미비하며, 이를 교육할 수 있는 교육프로그램을 설계하기 위한 디자인이 거의 제시되지 않았다. 또한 교육프로그램을 통하여 학습한 내용을 평가할 수 있는 측정이론 혹은 학습분석에 대한 고찰이 거의 없다. 본 연구는인식론적 프레임의 개념을 학습할 수 있는 컴퓨터를 활용한 교육프로그램의 디지인의 핵심적 요소를 제시함을 목적으로 하고 교육프로그램을 통하여 학습한 내용을 측정 및 평가할 수 있는 측정이론(학습분석)의 방법을 탐색한다. 이는 추후 컴퓨터를 활용하여 인식론적 프레임 학습과 이를 평가할 수 있는 통합적 교육프로그램 개발을 위한 방법론으로 활용될 것으로 기대된다.

• Smart Structures and Systems
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• 제29권3호
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• pp.499-512
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• 2022

This work proposes a novel contactless vibration damping and thermal isolation tripod platform based on Superconducting Magnetic Levitation (SML). This prototype is suitable for cryogenic environments, where classical passive, semi active and active vibration isolation techniques may present tribological problems due to the low temperatures and/or cannot guarantee an enough thermal isolation. The levitating platform consists of a Superconducting Magnetic Levitation (SML) with inherent passive static stabilization. In addition, the use of Operational Modal Analysis (OMA) technique is proposed to characterize the transmissibility function from the baseplate to the platform. The OMA is based on the Stochastic Subspace Identification (SSI) by using the Expectation Maximization (EM) algorithm. This paper contributes to the use of SSI-EM for SML applications by proposing a step-by-step experimental methodology to process the measured data, which are obtained with different unknown excitations: ambient excitation and impulse excitation. Thus, the performance of SSI-EM for SML applications can be improved, providing a good estimation of the natural frequency and damping ratio without any controlled excitation, which is the main obstacle to use an experimental modal analysis in cryogenic environments. The dynamic response of the 510 g levitating platform has been characterized by means of OMA in a cryogenic, 77 K, and high vacuum, 1E-5 mbar, environment. The measured vertical and radial stiffness are 9872.4 N/m and 21329 N/m, respectively, whilst the measured vertical and radial damping values are 0.5278 Nm/s and 0.8938 Nm/s. The first natural frequency in vertical direction has been identified to be 27.39 Hz, whilst a value of 40.26 Hz was identified for the radial direction. The determined damping values for both modes are 0.46% and 0.53%, respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.743-748
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• 2007

This paper describes a lens transmissive type tilting actuator for a projection TV. An electromagnetic analysis and a structural analysis of the tilting actuator system is necessary to design a tilting actuator for a projection TV. The tilting actuator is composed a permanent magnet, coil and yoke as the electromagnetic components and it needs a driving hinge part as the mechanical component. The design of the tilting actuator for the projection TV is performed by the following procedure. Firstly, a magnetic flux density of the tilting actuator system is analyzed by a mathematical theory and an electromagnetic FEM. Secondary, a magnetic circuit method is used to determine tilting force. Thirdly, the structural FEM is carried out with an FE model of a lens-transmissive type tilting actuator and then the prototype of the model is manufactured. The characteristic of the prototype is experimentally observed. Finally, a design for a new hinge configuration is suggested for better performance.

• 한국콘텐츠학회논문지
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• 제8권7호
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• pp.112-119
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• 2008

오늘날 지식정보화 사회로 변화하면서 창의성의 중요성이 더욱 강조됨에 따라 각 교육기관의 창의력 교육이 중시되고는 있으나, 대부분 교과목과 연계된 진학교육에 치중한 지능 계발에 더욱 초점이 맞춰져 있는 실정이다. 따라서 본 논문은 학습자의 자발적인 흥미와 참여를 통한 창의력 향상 및 종합적인 문제해결능력을 키울 수 있는 학습게임 개발의 방향을 제시하고자 하였다. 그 결과 선행연구인 창의력의 개념과 다중지능 이론을 바탕으로 한 창의력 계발을 위한 학습설계를 토대로 하여 학습게임의 재미요소 및 스토리텔링의 구성요소를 도출하였고, 이에 따라 게임구조도를 설계한 후 학습게임의 프로토타입 제작을 위한 스토리보드와 인터페이스 설계 및 그래픽 요소를 개발 사례로 제시하였다.

• 건축역사연구
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• 제21권6호
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• pp.45-52
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• 2012

"Ohju Yeonmun Jangjeon Sango" written by Lee, Gyu-gyeng is one of the most important encyclopedias in the period of Chosun-Dynasty. There are two chapters related to architecture in this book, one is "ancestral rite governance·human"chapter, and the other is "architecture·human" chapter. Both of them are hard to understand because they are written in ancient Chinese and consist of various quotations in ambiguous way. This paper as a partial study is deal with the former. It makes difference between writter's original texts and quotations through textual research, and translates to modern Korean, and analyze information about ancient architecture in texts. The texts can divide to three sections. The first introduces three Chinese architectural theory books as "Gogonggi(考工記)", "Yeongjo Beopsik(營造法式)" and "Mokgyeng(木經)", and mentions about the prototype of the royal ancestral ritual building in "Gogonggi Toju(考工記圖注)". The second quotes "Seoyeong(書影)" to introduce "Yeongjo Beopsik". The third quotes "PaePyeon(稗編)" to introduce "Yeongjo Beopsik" and "Mokgyeng", and mentions about the counting unit of columns of the royal ancestral ritual building. Although the purpose for these quotations is not directly mentioned, but we can find it is intended to explain the architectural prototype and lay-out of the royal ancestral ritual building.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.802-811
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• 1996

Farmers need alternatives for weed control due to the desire to reduce chemicals used in farming. However, conventional mechanical cultivation cannot selectively remove weeds located in the seedline between crop plants and there are no selective heribicides for some crop/weed situations. Since hand labor is costly , an automated weed control system could be feasible. A robotic weed control system can also reduce or eliminate the need for chemicals. Currently no such system exists for removing weeds located in the seedline between crop plants. The goal of this project is to build a real-time , machine vision weed control system that can detect crop and weed locations. remove weeds and thin crop plants. In order to accomplish this objective , a real-time robotic system was developed to identify and locate outdoor plants using machine vision technology, pattern recognition techniques, knowledge-based decision theory, and robotics. The prototype weed control system is composed f a real-time computer vision system, a uniform illumination device, and a precision chemical application system. The prototype system is mounted on the UC Davis Robotic Cultivator , which finds the center of the seedline of crop plants. Field tests showed that the robotic spraying system correctly targeted simulated weeds (metal coins of 2.54 cm diameter) with an average error of 0.78 cm and the standard deviation of 0.62cm.

• Journal of Biosystems Engineering
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• 제14권3호
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• pp.158-167
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• 1989

This study was conducted to investigate the applicability of true model theory in a powered lugged wheel-soil system and to examine the possibility of using principles of similitude in investigating the dimensions of soil parameters pertinent to a powered lugged wheel-soil system concerning the sinkage prediction. The following conclusions were derived from the study; 1) The sinkage of prototype wheels proved to be predicted by those of the model wheels for the range of the dynamic weight tested. 2) A conditional equation which can be used for the prediction of sinkage of prototype by model test was derived as $n_f=n{_\ell}{^{-b}}$. The range of the numerical value of b, which is the exponent on the length dimension of the soil property ${\alpha}$, was found to be -1.48~-2.54. 3) Considering a relatively wide variation of b values, it was concluded that there are several soil properties which are pertinent to the powered lugged-wheel soil system concerning the sinkage prediction.

• 풍력에너지저널
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• 제10권4호
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• pp.20-27
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• 2019

High-speed shaft coupling in a wind power system transmits power and absorbs variations in length and spindle dislocation between the gearbox and generator. Furthermore, the coupling has an insulation function that prevents electrical corrosion caused by the flow of the generator's current into the gearbox and prevents overload resulting from sudden power failure from being transferred to the gearbox. Its design, functions, and part verification are described in the IEC61400 and GL Guidelines, which specify that the part must have a durability life of 20 years or longer under distance variation and axial misalignment between the gearbox and the generator. This study presents the design of a high-speed coupling through composite stiffness calculation, structural analysis, and comparative analysis of test and theory to identify the characteristics of high-speed coupling for a large-capacity 6 MW wind power generator. A prototype was fabricated by optimizing the manufacturing process for each part based on the design, and the reliability of the fabricated prototype was verified by evaluating the performance of the target quantitative evaluation items.