• 한국전자파학회논문지
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• 제19권9호
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• pp.1045-1050
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• 2008

본 논문에서는 IR-UWB 통신에 적합한 저 전력, 저복잡도의 CMOS RF 수신기를 제작하였다. 제안된 IR-UWB 수신기는 비교적 구조가 간단한 non-coherent demodulation 방식으로 설계, 제작되었다. 설계된 IR-UWB 수신기는 LNA, envelop detector, VGA, comparator로 구성되어 있으며, envelop detector, VGA, comparator는 $0.18{\mu}m$ CMOS 공정 기술을 이용하여 단일 칩으로 설계, 제작하였다. 측정 결과 data rate이 1 Mbps일 때 sensitivity가 -70 dBm이며, 이때 BER은 $10^{-3}$의 값을 가진다. 외부의 LNA를 제외한 단일 칩 CMOS IR-UWB 수신기의 전류 소모는 전압이 1.8 V일 때 5 mA이다.

• 한국전자파학회논문지
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• 제19권5호
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• pp.547-555
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• 2008

본 논문에서는 linear amplification with nonlinear components(LINC) 시스템의 두 신호 경로에 발생하는 크기와 위상 오차를 자동으로 검출하여 보상하는 알고리즘을 제안하였다. LINC 시스템은 첨두 대 평균 전력비가 큰 non-constant envelop 신호를 constant envelop 신호로 바꿔주어 고효율 전력 증폭기를 사용할 수 있는 장점이 있다. 그러나 LINC 시스템은 두 전력 증폭기의 경호에서 발생하는 매우 작은 경로 오차에 민감하게 성능이 열화된다는 단점이 있다. 본 논문에서는 4개의 테스트 신호를 이용하여 두 경로의 크기와 위상 오차를 검출하는 알고리즘을 제안하였다. 제안된 오차 검출 기법은 닫힌 해(closed form solution)를 가지며, 반복 계산이 필요하지 않아, 빠르고 효율적으로 오차를 검출할 수 있다. 본 논문에서는 제안된 기법을 적용하여 오차 검출과 검출된 결과를 반영하여 신호의 왜곡을 보상하는 digital-IF 형태를 갖는 LINC 시스템을 구현하였다. 구현된 LINC 시스템은 7 MHz 채널 대역을 갖고 16-QAM으로 변조된 IEEE 802.16 WiMAx 기저 대역 신호를 이용하여 성능을 분석하였으며, 제안된 기법을 이용하여 EVM이 -37.37 dB까지 개선되었으며, 이로서 LINC 시스템 구현시 제안된 오차 검출 및 보상 기법의 적용 타당성을 확인하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.637-644
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• 2006

Acceleration time history used in the seismic analysis of nuclear porter plant structure should envelop a target power spectral density (PSD) function in addition to design response spectrum. Current regulation guide defines the target PSD function only for the U.S. URC RG 1.60 Design Response Spectrum. This paper proposes a technical scheme to obtain the target PSD function compatible with generally defined design response spectrum. The scheme includes the methodology for design-spectrum compatible motion history in order to minimize the variation of the derived target PSD function. The PSD calculation procedure follows simple and practical methods allowed within regulation. Effectiveness of the proposed scheme is identified through an example problem. The design response spectrum In the example is based on U.S. NRC RG 1.60 but amplifies the spectral acceleration amplitudes above 9Hz. The target PSD function with little variation can be constructed with the reduced time history ensemble.

• 한국주거학회논문집
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• 제13권4호
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• pp.61-66
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• 2002

The objectives of this study are to clarify the impacts of stack effect in high-rise residential buildings and to present technical methods to reduce stack effect. For the evaluation of stack effect, architectural design guidelines were used and computer program simulations based on network model were performed. The evaluation shows that problems due to stack effect may be reduced by appropriate architectural designs, such as increase in air-tightness of building envelop, and provision of vestibules around entrance and elevator hall doors.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.224-227
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• 2002

비행선 기낭을 개발하기 위한 막재 요구조건과 이를 만족하기 위한 막재(membrane)의 구성을 살펴보고, 실제 연구에 사용된 기낭재료의 조성과 소재 기본 물성시험 그리고 접착강도, 패치강도 등과 같은 설계개발시험을 수행한 결과 및 향후 계획을 소개한다.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.257-259
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• 2008

Acceleration time history (ATH) used in the seismic analysis should envelop a target power spectral density (PSD) function in addition to the design response spectrum in order to have sufficient energy at each frequency for the purpose of ensuring adequate load. Even though design regulations require the ATH used in seismic analysis to meet a target PSD function, the reason that ATHs meet to a target PSD function is not described. Thus, artificial ATHs for high PSD function and artificial ATHs for low PSD function are generated. And then elastic and inelastic single-degree-of-freedom (SDOF) systems are loaded with these artificial time histories as the earthquake load. As a result, linear response and inelastic response of SDOF systems are affected by PSD function.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.133-140
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• 2006

This paper addresses a fundamental research subject to complement and improve current domestic design specifications for the strong motion duration criterion and the envelop function of artificial accelerograms that can be applied to the earthquake-proof design of nuclear structures. The criteria for design response spectra and strong motion duration suggested by WRC RG 1.60 and ASCE Standard 4-98 are commonly being used in the profession, and they are first compared with each other and reviewed. By applying 152 real strong earthquake records that are over magnitude of 5 in the rock sites to the strong motion duration criterion in ASCE 4-98, an empirical regression model that predicts the strong motion duration as a function of earthquake magnitude is then developed. Using synthetically generated earthquake time histories for the five cases whose strong motion durations vary from 6 to 15 seconds, a seismic analysis is conducted to identify effects of the strong motion durations on the seismic responses of nuclear structures.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.24.1-24
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• 1996

The development of future aircraft that involves the expanded flight envelop will place increased performance requirements on the design of the flight control system. Maneuvering areas are expanding into flight envelopes characterized by significantly larger levels of modeling uncertainty than encountered in present flight control designs. Conventional flight control techniques that ignore the effects of large parameter variations, modeling uncertainties and nonlinearities, will likely produce designs with poor performance and robustness. Recent advances in modern control theories called advanced control theories, most notably the H$\_$.inf./ synthesis technique, adaptive control and neural network application, offer the promise of a design technique that can produce both high performance and robust controllers for next generation aircraft. This special lecture will survey the recent development in advanced flight control and review the possible application of advanced control theories.

• 건축역사연구
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• 제14권3호
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• pp.89-102
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• 2005

Frank Lloyd Wright and Mies van der Rohe are two of the most influential architects in modern architecture. In spite of the different values in their architectural lives, the design of high-rise building had been a continuous matter of primary concern for them. The purpose of this study is to compare the architectural characteristics of the two master architects in terms of building form, structure, function, and envelop skin. glass. Both of them shared with the principle of organic architecture even in the design of high-rise buildings. However, the specific approaches to realize it in high-rise buildings are significantly different. Although they emphasized the integration of building form and structure, Wright regarded the reinforced concrete structure as an organic form-giver, while Mies introduced the steel skeleton structure only as an efficient and flexible building frame. As primary finishing materials for high-rise buildings, glass was used for functional purpose by Wright, but for visual purpose by Mies.

• International Journal of Aeronautical and Space Sciences
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• 제15권2호
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• pp.153-162
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• 2014

A novel robust $H_{\infty}$ switching tracking control design method with disturbance observer is proposed for the near space interceptor (NSI) with aerodynamic fins and reaction jets. Initially, the flight envelop of the NSI is divided into small subregions, and a slow-fast loop polytopic linear parameter varying (LPV) model is proposed, to approximate the nonlinear dynamic of the NSI, based on the Jacobian linearization and Tensor-Product (T-P) model transformation approach. A disturbance observer is then constructed, to estimate the modeled disturbance. Subsequently, based on the descriptor system method, a robust switching controller is developed, to ensure that the closed-loop descriptor system is stable with a desired $H_{\infty}$ disturbance attenuation level. Furthermore, the outcome of the proposed switching tracking control problem is formulated as a set of linear matrix inequalities (LMIs). Finally, simulation results demonstrate the effectiveness of the proposed design method.