• Earthquakes and Structures
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• 제19권5호
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• pp.331-345
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• 2020

The multi-story timber structure with high platform base is one of the important architectural types in the traditional Chinese buildings. To study the dynamic characteristics and seismic responses on this kind of traditional structure, the 3-D finite element models of Xi'an drum tower which included the high platform base, upper timber structure and whole structure was established considering the structural form and material performance parameters of the structure in this study. By the modal analysis, the main frequencies and mode shapes of this kind of traditional building were obtained and investigated. The three kinds of earthquake excitations included El-Centro wave, Taft wave and Lanzhou wave were separately imposed on the upper timber structure model and the overall structure model, and the seismic responses on the tops of columns were analyzed. The results of time history analysis show that the seismic response of the upper timber structure is obviously amplified by high platform base. After considering the effect of high platform base, the mean value on the lateral displacement increments of the top column in the overall structure is more than 20.478% and the increase of dynamic coefficients was all above 0.818 under the above three different earthquake excitations. Obviously, it shows that the existence of high platform base has a negative influence on the seismic responses of upper timber structure. And the high platform base will directly affect the safety of the upper timber structure. Therefore, the influence of high platform base on the dynamic response of its upper timber structure cannot be neglected.

• 한국공간구조학회논문집
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• 제14권2호
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• pp.87-94
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• 2014

In this study, a smart isolation platform has been developed for control of microvibration of high-technology facilities, such as semi-conductor plants and TFT-LCD plants. Previously, microvibration control performance of a smart base isolation system has been investigated. This study compared microvibration control performance of a smart isolation platform with that of conventional base isolation and fixed base. For this purpose, train-induced ground acceleration is used for time history analysis. An MR damper was used to compose a smart isolation platform. A fuzzy logic controller was used as a control algorithm and it was optimized by a multi-objective genetic algorithm. Numerical analysis shows that a smart isolation platform can effectively control microvibration of a high-technology facility subjected to train-induced excitation compared with other models.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.166-175
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• 2001

The high speed tracking control of a 6-6 Stewart platform manipulator (SPM) normally requires knowledge of its complex full dynamics and measurement of its base motion when the SPM operates on a motion nit. In this study, an enhanced sliding mode control scheme has been developed, which is based on the reduced dynamics, not necessitating measurement of the base motion. The enhanced sliding mode control implemented with the perturbation compensation and modified reaching phase alleviation functions has been successfully employed for high speed tacking control of the laboratory SPM, when it is subjected to a virtual base motion.

• 대한기계학회논문집A
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• 제22권2호
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• pp.372-379
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• 1998

A new 6 degrees-of-freedom micro stage, based on parallel mechanisms and actuated by using piezoelectric elements, has been developed for the application of micro positioning such as semiconductor manufacturing devices, high precision optical measurement systems, and high accurate machining. The micro stage structure consists of a base platform and an upper platform(stage). The base platform can effectively generates planar motion with yaw motion, while the stage can do vertical motion with roll and pitch motions with respect to the base platform. This separated structure has an advantage of less interference among actuators. The forward and inverse kinematics of the micro stage are discussed. Also, through linearization of kinematic equations about an operating point on the assumption that the configuration of the micro stage remains essentially constant throughout a workspace is performed. To maximize the workspace of the stage relative to fixed frame, an optimal design procedure of geometric parameter is shown. Hardware description and a prototype are presented. The prototype is about 150mm in height and its base platform is approximately 94mm in diameter. The workspace of the prototype is obtained by computer simulation. Kinematic calibration procedure of the micro stage and its results are presented.

• Smart Structures and Systems
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• 제14권4호
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• pp.617-641
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• 2014

The energy constraint is still a common issue for the practical application of wireless sensors, since they are usually powered by batteries which limit their lifetime. In this paper, a practical compound energy efficiency strategy is proposed and realized in the implementation of a real time wireless sensor platform. The platform is intended for wireless structural monitoring applications and consists of three parts, wireless sensing unit, base station and data acquisition and configuration software running in a computer within the Matlab environment. The high energy efficiency of the wireless sensor platform is achieved by a proposed adaptive radio transmission power control algorithm, and some straightforward methods, including adopting low power ICs and high efficient power management circuits, low duty cycle radio polling and switching off radio between two adjacent data packets' transmission. The adaptive transmission power control algorithm is based on the statistical average of the path loss estimations using a moving average filter. The algorithm is implemented in the wireless node and relies on the received signal strength feedback piggybacked in the ACK packet from the base station node to estimate the path loss. Therefore, it does not need any control packet overheads. Several experiments are carried out to investigate the link quality of radio channels, validate and evaluate the proposed adaptive transmission power control algorithm, including static and dynamic experiments.

• 한국통신학회논문지
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• 제39C권9호
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• pp.861-869
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• 2014

본 논문은 long term evolution (LTE) 기반 macro 기지국 platform 구조 연구에 관한 것으로, codeword별 기저 대역 신호 (baseband signal)와 중간 주파수 (intermediate frequency; IF)에 대한 인터페이스 구조를 제안한다. 제안한 구조를 이용하여 massive multiple input multiple output (MIMO) 기술과 같이, 많은 수의 안테나를 사용하는 기지국에 있어서, 안테나수와 상관없이 대용량의 데이터를 원활히 송수신 할 수 있다. 본 논문에서는 LTE 표준 기술 발전 및 그에 따른 시스템의 개발 동향을 분석하고, 종래의 일반적인 구조와 본 논문에서 제안하는 구조에 대하여 비교하여, 데이터 인터페이스 전송량 측면에서 제안 구조가 훨씬 더 좋은 구조임을 확인하였다. 이러한 구조를 제시함으로서 massive MIMO, carrier aggregation (CA), coordinated multi point (CoMP) 기술과 같이 발전하고 있는 LTE 기반 기지국의 플랫폼 (platform) 설계 및 구현에 대하여 새로운 기반을 제공하고자 한다.

• 정보처리학회논문지C
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• 제17C권2호
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• pp.181-189
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• 2010

HAP(High Altitude Platform)은 지표면 17~22km위에 있는 성층권 영역에서 운행하는 정지 궤도 공중 플랫폼으로 공중에서의 MBS(Mobile Base Station)로서의 역할이 가능하다. HAP 기반 네트워크는 인공위성 시스템과 지상통신 시스템의 장점들을 가지고 있다. 본 논문에서는 HAP 기반망의 구성 및 그 유지를 위한 HAP MBS의 배치에 대해 연구한다. 이 연구를 위해 지상 이동 노드들을 클러스터링하기 위한 클러스터링 알고리즘이 사용되는데, 본 논문에서는 EM(Expectation Maximization) 클러스터링 알고리즘을 사용한다. 본 논문의 목표는 이동 통신 단말기들 간의 거리와, 각 단말기들의 이동속도를 고려하여 단말기들이 효율적으로 클러스터링 되어 HAP의 배치가 효율적일 수 있도록 EM 알고리즘을 적용 및 개선하고, 이 EM 알고리즘을 이용한 HAP MBS 배치기법을 인구밀도에 기반을 둔 RWP(Random Waypoint) 노드 모빌리티를 이용하여 그 성능을 평가한다.

• 패션비즈니스
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• 제27권4호
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• pp.38-49
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• 2023

Fashion vertical platforms offer various content and events to consumers and have established a strong customer base. Especially, they cater to the sensibilities of young customers. This study analyzed the characteristics of a sensuous fashion vertical platform, which enhances expertise and provides customized services. In addition, this study aimed to find out whether consumer innovation modulates the relationship between fashion vertical platform, platform satisfaction, and continuous shopping intention. An online survey was conducted targeting consumers in their 20s and 30s who had experience using fashion vertical platforms, and 222 samples were analyzed. Factor analysis and structural equation model were analyzed using the SPSS 29.0 and Smart-PLS. Smart-PLS analysis results showed that exclusivity, convenience and informativeness did not directly affect continuous shopping intention but showed a complete mediating effect through platform satisfaction. Both the high and low innovative groups demonstrated significant effects of exclusivity on platform satisfaction, and platform satisfaction showed significant effects on continuous shopping intention. A high level of innovation among the consumers showed significant mediating effects on exclusivity, personalization, and continuous shopping intention, as reflected by information on platform satisfaction, and low level of innovation among the consumers showed significant effect on convenience. This study's findings highlight the importance of enhancing exclusivity, convenience, informativeness, and esthetics in fashion vertical platforms, and improving platform satisfaction. These findings will be used to develop marketing strategies that can lead to continuous shopping intentions and provide opportunities for the industry.

• 제어로봇시스템학회논문지
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• 제8권8호
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• pp.639-648
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• 2002

The stewart platform manipulator is a manipulator that has the closed-loop structure with an upper plate end-effector and a base frame. The stewart platform manipulator has the merit of high working accuracy and high stiffness compared with a serial manipulator. However, this is a complex structure, so controllability of the system is not so good. In this paper, we introduce a new robust motion control algorithm using partial state feedback for a class of nonlinear systems in the presence of modelling uncertainties and external disturbances. The major contribution of this work introduces the development and design of robust observer for the state and the perturbation, which is integrated into a variable structure controller(VSC) structure. The combination of controller/observer improves the control performance, because of the robust routine called sliding mode control with sliding perturbation observer(SMCSPO). Simulation and experiment are performed to apply to the manipulator. And their results show a high accuracy and a good performance.

• Journal of Communications and Networks
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• 제13권1호
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• pp.70-76
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• 2011

This paper presents the unified user equipment (UE) baseband modulation and demodulation (modem) hardware platform architecture to support multiple radio access technologies. In particular, this platform selectively supports two systems; one is HEDGE system, which is the combination of third generation partnership project (3GPP) Release 7 high speed packet access evolution (HSPA+) and global system for mobile communication (GSM)/general packet radio service (GPRS)/enhanced data rates for GSM evolution (EDGE), while the other is LEDGE system, which is the combination of 3GPP Release 8 long term evolution (LTE) and GSM/GPRS/EDGE. This is done by applying the flexible pin multiplexing scheme to a hardwired pin mapping process. On the other hand, to provide stable connection, high portability, and high debugging ability, the stacking structure is employed. Here, a layered board architecture grouped by functional classifications is applied instead of the conventional one flatten board. Based on this proposed configuration, we provide a framework for the verification step in wireless cellular communications. Also, modem function/scenario test and inter-operability test with various base station equipments are verified by system requirements and scenarios.