• 전력전자학회논문지
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• 제28권1호
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• pp.59-67
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• 2023

This paper explores the variation of DC-Link current ripple analysis in terms of duty cycle and phase angle of Multi-phase/Multi-stage boost converter. A 2-Stage/1-Stage boost converter DC-Link current is used to determine the difference between the 1st stage diode current and the 2nd stage inductor current. Each stage boost converter diode and inductor current is subordinate to the phase angle and duty cycle. The magnitude of the ripple current is variable according to phase angle and duty cycle. The analysis results are verified by variation of DC-Link current ripple using a 1kW typical 2-stage/1-stage boost converter.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.635-640
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• 2000

This paper presents the analysis method of the instantaneous screw axis using line geometry in bump and rebound motion of 5-SS multi-link suspensions. Instantaneous screw axis is based on screw motion, and screw motion of zero pitch can be expressed as $Pl{\ddot{u}}cker$ line coordinates of line geometry instead of screw coordinates. In screw coordinates, twist and wrench are described by components of instantaneous screw axis. For instantaneous motion of wheel assembly, the principle of virtual work with twist and wrench is applied to 5-SS multi-link suspension, and it makes 5 linear equations. Therefore, it is possible to find instantaneous screw axis by solving these equations. This analysis by line geometry demands geometric values only, such as the locations of spherical joints in the case of multi-link suspensions.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.848-857
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• 2021

This paper proposes an efficient approach based on a machine learning technique to predict the local stresses on mooring chain links. Three-link and multi-link finite element analyses were conducted for a target chain link of D107 with steel grade R4; 24,000 and 8000 analyses were performed, respectively. Two serial Artificial Neural Network (ANN) models based on a deep multi-layer perceptron technique were developed. The first ANN model corresponds to multi-link analyses, where the input neurons were the tension force and angle and the output neurons were the interlink angles. The second ANN model corresponds to the three-link analyses with the input neurons of the tension force, interlink angle, and the local stress positions, and the output neurons of the local stress. The predicted local stresses for the untrained cases were reliable compared to the numerical simulation results.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1436-1439
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• 2002

In this paper, based on the data link model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath.

• 한국해양공학회지
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• 제32권5호
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• pp.297-309
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• 2018

After an accident involving mooring link failures in an offloading buoy, verification of the fatigue safety in terms of the out-of-plane bending (OPB) and in-plane bending (IPB) moments has become a key engineering item in the design of various floating offshore units. The mooring links for an 8 MW floating offshore wind turbine were selected for this study. To identify the OPB stiffness (OPB moment versus interlink angle), a numerical simulation model, called the 3-link model, is usually composed of three successive chain links closest to the fairlead or chain hawse. This paper introduces two numerical simulation techniques for the 3-link analyses. The conventional and advanced approaches are both based on the prescribed rotation approach (PRA) and direct tension approach (DTA). Comparisons of the nominal stress distributions, OPB stiffnesses, hotspot stress curves, and stress concentration curves are presented. The multiple link analyses used to identify the tension angle versus interlink angle require the OPB stiffness data from the 3-link analyses. A convergence study was conducted to determine the minimum number of links for a multi-link analysis. It was proven that 10 links were sufficient for the multi-link analysis. The tension angle versus interlink angle relations are presented based on multi-link analyses with 10 links. It was found that the subsequent results varied significantly according to the 3-link analysis techniques.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.194-202
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• 2014

Steering axis of suspensions is an important factor that affects ride and handling quality in the vehicle chassis development. Macpherson strut and double wishbone's steering axis are defined geometrically, but multi-link suspensions can not be geometrically analyzed. In this case instant axis theory is commonly used to find a steering axis. Since the steering axis is moving with varying caster and kingpin inclination angle, this method approximately corresponds with exact solution. In this paper, we propose a velocity analysis method to find a pure rotational axis of the wheel relative to suspension arms, that is exact solution of the steering axis. This paper extends the method to analyze the steering axis of multi-link suspensions with bushing compliance. The analysis results applied to double wishbone and multi-link suspensions demonstrate validity and accuracy of the proposed method.

• 한국통신학회논문지
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• 제31권5A호
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• pp.469-474
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• 2006

본 논문에서는 High Speed Data Packet Access(HSDPA) 시스템의 평균 sector throughput 분석 방법을 개발하였다. 제안하는 성능 분석 방법은 Adaptive Modulation and Coding(AMC)와 scheduling 기법, multi-code 전송의 영향을 반영할 수 있으며, link budget을 응용한 간단한 계산 과정들을 통해, HSDPA의 성능을 분석할 수 있다. 일반적으로, link budget은 셀 coverage를 산출하는 목적으로 사용되었으나, 본 논문에서는 AMC가 적용되는 CDMA 시스템 환경에서 특정 위치에 있는 사용자의 C/I를 계산할 수 있도록 변형하였다. 또한, 개발된 분석 방법을 활용하여, scheduling 기법과 multi-code 전송이 HSDPA 시스템 성능에 미치는 영향을 분석하였다.

• 전자공학회논문지A
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• 제32A권9호
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• pp.1167-1176
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• 1995

This paper suggests a method for optimal power assignment of the satellite transponder input carriers in the Multi-level & Multi-bandwidth system. The interference and the noise effects analyzed for the optimal power assignment are intermodulation product caused by the nonlinear transponder characteristics, adjacent channel interference, co-channel interference, and thermal noise in the satellite link. The Fletcher- Powell algorithm is used to determine the optimal input carrier power. The performance criteria for optimal power assignment is classified into 4 categories according to the CNR of destination receiver earth station to meet the requirement for various satellite link environment. We have performed mathematical analysis of objective functions and their derivatives for use in the Fletcher-Powell algorithm, and presented various simulation results based on mathematical analysis. Since the satellite link, it is meaningful to model and analyze these effects in a unified manner and present the method for optimal power assignment of transponder input carriers.

• Journal of electromagnetic engineering and science
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• 제2권1호
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• pp.39-44
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• 2002

A high speed data link capability is one of the critical factors in determining the performance of the spaceborne SAR system with high resolution because of the strict requirement far the real-time data transmission of the massive SAR data in a limited time of mission. In this paper, based on the data lint model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.159-164
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• 1998

This paper proposes a SVPWM (space vector pulse width modulation) strategy for a multi-level voltage source inverter. This strategy is easily implemented as SPWM (sinusoidal pulse width modulation) and has the same DC-link voltage utilization as general SVPWM. The method to keep the voltage balancing of DC-link also is proposed by the analysis model of DC-link voltage fluctuation. The usefulness of the proposed SVPWM is verified through the simulation.