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동적 주파수 분할기의 변조신호 전송 조건을 위한 입출력 전달 특성 분석과 설계에 대한 연구
류성헌(Sungheon Ryu),박영철(Youngcheol Park) 한국전자파학회 2016 한국전자파학회논문지 Vol.27 No.2
본 논문은 주파수 분할기를 통한 변조신호 전달시스템의 구현에 있어, 동적 주파수분할기의 출력 유지 조건 및 동작 주파수의 관계식을 활용하여 반송주파수가 분할된 변조신호의 전달함수를 도출하였다. 이러한 분석으로부터, 동적 주파수 분할기의 전달함수는 크기 신호에 대하여 곱셈기의 이득과 입력 전압의 일차 선형 함수로 결정되며, 위상은 입력위상에 대역필터의 군지연이 합산되는 관계로 파악되었다. 이에 따라 1,400 MHz 대역에서 동작하는 동적 주파수 분할기를 설계하였으며, 이를 통해 700 MHz 대역으로의 변조신호 전달 가능성을 확인하기 위한 모의실험을 수행하였다. 설계된 회로는 0.9~3.2 GHz에서 동작하며, 2.3 GHz의 대역폭을 가지고 입력 주파수 1.4 GHz에서 —14.5 dBm의 입력 전력으로 동작하도록 설계되었다. 바이어스 전압 VDD=2.5 V에서 입력 파형 VPP=136 mV일 때 20 mW의 전력을 소모하며, 변조지수 0.9인 진폭변조신호를 1.4 GHz에서 700 MHz로 성공적으로 전송하는 것을 확인하였다. In order to transmit baseband signals through frequency dividing devices, we studied the transfer function of the device in the term of the baseband signal distortion. From the analysis, it is shown that the magnitude of the envelope signal is related to the mixer gain and the insertion loss of the low pass filter whilst the phase is the additional function with the 1/2 of the phase delay. For the purpose of the verification of the study, we designed a dynamic frequency divider at 1,400 MHz. The operating frequency range of the device is closely related to the conversion gain of mixers and the amplitude of input signal, and becomes wide as the conversion gain of mixers increases. The designed frequency divider operates between 0.9 GHz and 3.2 GHz, for-14.5 dBm input power. The circuit shows 20 mW power dissipation at VDD=2.5 V, and the simulation result shows that an amplitude modulated signal at 1,400 MHz with the modulation index of 0.9 was successfully downconverted to 700 MHz.
Landing impact analysis of sports shoes using 3-D coupled foot-shoe finite element model
조진래,박승범,류성헌,김성호,이시복 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.10
The rapid spread of various sports games has changed the role of shoes from the simple protection of human feet to more advanced ones like competency improvement. Accordingly, intensive research efforts are being focused on the development of high-competency sports shoes by taking kinesiology and biomechanics into consideration. However, the success of this goal depends definitely on the reliable evaluation of the main functions required for sports shoes. As the first part of our study on the landing impact analysis of court sports shoes, this paper introduces a coupled foot-shoe finite element model in order to fully reflect the mutual interaction between the foot and the shoe, not relying on traditional independent field experiments any more. Through illustrative numerical experiments, we assess the reliability of the proposed coupled FEM model by comparing with the experimental results and investigating the fundamental landing impact characteristics of sports shoes.
유한요소 해석을 통한 코트 스포츠화의 런닝시 충격력 평가
김성호(Seong-Ho Kim),조진래(Jin-Rae Cho),류성헌(Sung-Heon Ryu),최주형(Joo-Hyung Choi) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
A fundamental function of court sport shoes has been considered as the protection of human feet from unexpected injuries. But, recently its role for improving the playing competency is being regarded as a more important function. In connection with this situation, intensive efforts are being world-widely forced on the development of court sport shoes proving the excellent playing competency, by taking kinesiology and biomechanics into consideration. However, the success of this goal depends definitely on the shoes design based upon the reliable evaluation of shoes functional parts. This paper addresses the application of finite element method to the evaluation of landing impact force of court sport shoes. In order to reflect the coupling effect between leg and shoes accurately and effectively, we construct a fully coupled shoes-leg FEM model which does not rely on the independent experimental data any more. Through the numerical experiments, we assess the reliability of the coupled FEM model by comparing with the experimental results and investigate the landing impact characteristics of court sport shoes.
김성호(Seong-Ho Kim),조진래(Jin-Rae Cho),류성헌(Sung-Heon Ryu),최주형(Joo-Hyung Choi) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Court sport shoes is consisted of several functional parts such as soles, upper and midfoot reinforcements. Currently, intensive research for court sport shoes considering functional parts is in progress world widely, but the shoes design relies only on the view point of kinesilogy and biomechanics until now. Thus, more scientific and reliable evaluation of shoes characteristics is definitely required. In this paper, we evaluate the landing impact of court sport shoes by using finite element method. We construct a shoes-leg coupled FEM model which can simulate effectively impact in running mode. From the numerical analysis results, the designer can establish the advanced design concepts and build up the detailed design standard for the specific court sport shoes under consideration.
윤활-구조물 연계해석을 이용한 왕복동형 압축기의 피스톤 거동해석
문승주(Seung-Ju Moon),조진래(Jin-Rae Cho),류성헌(Sung-Hyon Ryu) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
The piston slap phenomenon is one of the major noise source of reciprocating compressors used in household electric appliances. In response to public demand, strict regulations are increasingly being imposed on the allowable moise level which is caused mostly by household electric appliances. In this paper, the dynamic behavior of suction and discharge valves are analytically calculated and the lubricant behavior between piston and cylinder are investigated using two-dimensional Reynolds equation. And the piston slap caused by the piston secondary motion is investigated by the finite element method.