• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.4
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• pp.26-34
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• 2003

In this paper, a novel technique is proposed to arbitrarily activate the nodal points in finite element model through the meshless approximation methods such as MLS(moving least squares method), and theoretical investigations are carried out including the consistency and boundeness of numerical solution to prove the validity of the proposed method. By using the proposed node activation technique, one can activate and handle only the concerned nodes as unknown variables among the large number of nodal points in the finite element model. Therefore, the proposed technique has a great potential in design and reanalysis procedure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.271-280
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• 2003

The purpose of the study presented in this paper is to develope the general model for capture of the linear and nonlinear response of a flexible diaphragm building in which there are significant contributions from the out-of-plane walls. Two single-story single-diaphragm half scale reinforced masonry buildings were tested by researchers at the United States Army Construction Engineering Research Laboratory (CERL). The first had a metal deck diaphragm. The second specimen had a diaphragm with a single layer of diagonal lumber sheathing, A multiple degree of freedom (MDOF) approach is adopted in this paper. The required stiffnesses and strengths of the components within this model are determined.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.1
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• pp.1-6
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• 2008

In this paper, we present the robust fuzzy algorithm for variable speed control of wind turbines. Generally, the plants of wind turbines are consisted of complex nonlinearities, and the parameters of variable speed of wind turbines are represented as uncertain terms. For solving these complexity, we propose the robust fuzzy algorithm. At first, the exact fuzzy modeling are performed for variable speed of wind turbines. Next, we design the fuzzy controller for reanalyzed T-S fuzzy model of the wind turbines, then, we prove the stability of the plant through the Lyapunov stability theorem. At last, an example is included for visualizing the efficiency of the proposed technique.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.93.1-93.1
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• 2012

세종대 간의대(簡儀臺)는 우리나라 역사상 가장 대규모로 수행된 천문 관련 국책사업의 일환으로 축조된 조선시대의 국립천문대이다. 지금까지 세종대 간의대에 대한 선행 연구는 주로 궁내 위치 및 변화, 개보수 상황 및 중수 여부, 규모와 관련한 주척(周尺) 또는 영조척(營造尺)에 대한 논의 등에 천착하고 있으나 간의대의 외형, 구조, 기능, 역할 등에 대한 연구는 미진한 편이다. 이 중 간의대의 외형에 대한 선행 연구들에서는 원대(元代) 북경 사천대(北京 司天臺, 1279년 전후 축조) 또는 명대(明代) 북경 관성대(北京 觀星臺, 1442년 축조, 現 古觀象臺) 등을 간의대의 원형으로 추정하고 있다. 이 연구에서는 간의대 복원을 위하여 외형에 대한 재해석을 시도하였으며, 이를 위하여 1997년 소더비(Sotheby) 경매 출품본 "경복궁도(景福宮圖)"를 비롯한 각종 경복궁 궁궐도(宮闕圖)를 분석하였다. 또한 구조와 축조 방식의 규명을 위하여 제단(祭壇) 등의 각종 석축물(石築物)을 분석하였으며, 이와 함께 "조선왕조실록"을 비롯한 각종 사료(史料)에 대한 조사를 병행하였다. 이와 같은 연구를 통하여 원대 북경 사천대 또는 명대 북경 관성대와는 다른 세종대 간의대의 독자적인 모델을 제시하였다.

• Journal of Korea Game Society
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• v.21 no.6
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• pp.63-74
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• 2021

Metaverse fits well with the lifestyle of MZ generation who carries smart-phones at all times and value their identity. This study proposes a planning model that develops Minhwa, traditional Korean culture and arts, into art galleries on Zepeto, a metaverse platform. To this end, the characteristics of the metaverse platform, open world, sandbox, creator economy, and avatar, are analyzed and developed into a planning to open a Minhwa museum on Zepeto. While reinterpreting traditional Korean art in a modern way, it is worth researching as a metaverse planning and development model suitable for the new-tro sensibility of the MZ generation.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.326-326
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• 2022

기후 변화 시나리오는 온실가스, 에어로졸, 토지이용 변화 등 인위적인 원인으로 발생한 복사강제력 변화를 지구시스템 모델에 적용하여 산출한 미래 기후 전망정보(기온, 강수량, 바람, 습도 등)를 생산하는데 활용된다. 또한, 미래에 기후변화로 인한 영향을 평가하고 피해를 최소화하는데 활용할 수 있는 선제적인 정보로 활용된다. GCM과 RCM은 구조 및 모수화 과정, 불확실성 등의 한계로 인하여 상대적으로 큰 시공간적 규모를 가지며, 실제 관측된 기상인자들을 재현하는데 시공간적 차이 즉 편의(bias)가 발생하며. 실제 관측된 기상인자의 시간적 변화 특성을 재현하지 못하는 문제점을 내재하고 있는 것으로 보고되고 있다. 이러한 점에서 기후모델에서 생산된 정보를 수문학적으로 적용하기 위해서는 시공간적 상세화와 편의 보정은 필수적이다. 본 연구에서는 관측자료를 사용하여 재해석 자료를 편의보정 한 뒤. 기후 변화 시나리오를 합성곱 신경망(CNN)을 기반으로 상세화 과정을 진행하여 고해상도 자료를 생산하였으며, CNN 기반 상세화 기법 적용성은 지상 관측자료 대상으로 평가하였다.

• Journal of Technology Innovation
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• v.22 no.4
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• pp.57-88
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• 2014

The 'Grand Challenge' in the global level raises fundamental questions on the role of private firm as a profit maximizer. From the new perspective, firms are recognized as a social entity with social and environmental responsibility. Particularly, the importance of transition-orineted firms, which pursue an objective of socio-technological system transition, have increased. These environmental changes request a new understanding on the identification of firms and the evolution of sustainable business model from the technological innovation perspectives. This paper aims on the new understanding on the motivation of firms who participated on the sustainable system transition and the proposal of 'transition-oriented firms' concept. Based on literature survey, this paper reviews the role of firms in the process of socio-technological system transition, the cases of transition-oriented firm, the types of sustainable business models and their strategies.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.1-8
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• 2012

Acoustic-pressure response of diluted hydrogen-air diffusion flames is investigated numerically by adopting a fully unsteady analysis of flame structures in low and high pressure regimes. As acoustic frequency increases, finite-rate chemistry is enhanced through a nonlinear accumulation of heat release rate for any pressure regime, leading to a high amplification index. Same numerical results are analyzed with application of a pressure-sensitive time lag model, and thereby, interaction index and time lag are calculated for each pressure regime. The interaction index has the largest value in each pressure regime at an acoustic frequency near 1000 Hz. In a high-pressure regime, flames are more unstable than in a low-pressure regime. The interaction index shows a good agreement with the amplification index.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.3
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• pp.267-272
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• 2012

This paper propose the implementation of robust fuzzy controller for controlling an active magnetic bearing (AMB) system with 6 degree of freedom (DOF). A basic model with 6 DOF rotor dynamics and electromagnetic force equations for conical magnetic bearings is proposed. The developed model has severe nonlinearity and uncertainty so that it is not easy to obtain the control objective. For solving this problem, we use the Takagi-Sugeno (T-S) fuzzy model which is suitable for designing fuzzy controller. The control object in the AMB system enables the rotor to rotate without any phsical contact by using magnetic force. In this paper, we analyze the nonlinearity of the active magnetic bearing system by using fuzzy control algorithm and desing the robust control algorithm for solving the parameter variation. Simulation results for AMB are demonstrated to visualize the feasibility of the proposed method.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.135-144
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• 2022

Electromagnetic topology (EMT) technique is a method to analyze each component of the electromagnetic propagation environment and combine them in the form of a network in order to effectively model the complex propagation environment. In a typical commercial communication channel model, since the propagation environment is complex and difficult to predict, a probabilistic propagation channel model that utilizes an average solution, although with low accuracy, is used. However, modeling techniques using EMT technique are considered for application of propagation and coupling analysis of threat electromagnetic waves such as electromagnetic pulses, radio wave models used in electronic warfare, local communication channel models used in 5G and 6G communications that require relatively high accuracy electromagnetic wave propagation characteristics. This paper describes the effective implementation method, algorithm, and program implementation of the electromagnetic topology (EMT) method analyzed in the frequency domain. Also, a method of deriving a response in the time domain to an arbitrary applied signal source with respect to the EMT analysis result in the frequency domain will be discussed.