• Transactions on Control, Automation and Systems Engineering
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• v.1 no.1
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• pp.22-31
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• 1999

In this paper, a robust observer design method for nonlinear multi input multi-output(MINO) plants is presented. This method enables the extension of the time delay observer (TDO) for nonlinear SISO plants in the phase variable form to MIMO plants. The designed TDO reconstructs the states of the plant expressed in the generalized observability canonical form (GOBCF), yet requiring neither the transformation of a plant, nor the real time computation coordinates, the observer turned out to be computationally efficient and easy to design for nonlinear MIMO plants. In a simulation of a two-link manipulator with flexible joints, the control performances using TDO appeared to be similar to those using actual states and superior to those using numerical differentiation. Finally, in an experiment with a robot, it was confirmed that the TDO reconstructs the states reliability and TDO can be effectively used in a real closed-loop system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.983-987
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• 2001

This paper deals with an automated computer-aided process planning system by which designer can determine operation sequences even if they have little experience in process planning of wheel bolt products by a multi-stage former. The approach to the system is based on knowledge-based rules and a process knowledge base consisting of design rules is built. Knowledge for the system is formulated from plasticity theories, empirical results and the empirical knowledge of field experts. Programs for the system have been written in AutoLISP for the AutoCAD using a personal computer and are composed of two main modules. An attempt is made to link programs incorporationg a number of expert design rules to form a useful package. Results obtained using the modules enable the designer and manufacturer of wheel bolt product to be more efficient in this field.

• Advances in Energy Research
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• v.2 no.1
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• pp.47-59
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• 2014

Back-to-back STATCOM configuration is an extension of STATCOM in which the reactive power at two-sides and the real power flow through the DC link can be controlled concurrently and independently. This flexible operation brings many advantages to the micro-grids, distributed generation based systems, and deregulated power systems. In this paper, the dynamic control characteristics of the back-to-back STATCOM is investigated by simulating the detailed converter-level model of the converters in PSCAD. Various case studies in a single-machine test system are studied to present that the real power control feature of the BtB-STATCOM, even with a simple controller design, can enhance the transient stability of the machine under different fault scenarios.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.61.1-61.1
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• 2018

Outflows are common among local AGNs. Woo et al. (2017) suggested that AGN feedback through outflows is delayed by a dynamical time scale before the suppression of SFR is observationally detected. However, these SFR have large uncertainties because they were estimated by Artificial Neural Network (ANN) method (Ellison et al. 2016). We measured the SFR of 21 far-IR matched sources (z < 0.1) with total IR luminosity from multi-wavelength SED fitting from UV to radio. 15 out of 21 sources were observed with JCMT SCUBA-2 450 and 850um and 4 and 2 sources were matched with archival data of JCMT SCUBA-2 and Herschel SPIRE, respectively. We compared the true SFR by SED fitting with ANN-based one. In addition, we confirmed that sub-mm data are important to determine the SFR with total IR luminosity from SED fitting. Finally, we discuss the significance of true SFR and further the AGN-SF link.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.5
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• pp.2346-2361
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• 2017

A major challenge in cloud infrastructure is the efficient allocation of virtual network elements on top of substrate network elements. Path algebra is a mathematical framework which allows the validation and convergence analysis of the mono-constraint or multi-constraint routing problems independently of the network topology or size. The present study proposes a new heuristic approach based on mathematical framework "paths algebra" to map virtual nodes and links to substrate nodes and paths in cloud. In this approach, we define a measure criterion to rank the substrate nodes, and map the virtual nodes to substrate nodes according to their ranks by using a greedy algorithm. In addition, considering multi-constraint routing in virtual link mapping stage, the used paths algebra framework allows a more flexible and extendable embedding. Obtained results of simulations show appropriate improvement in acceptance ratio of virtual networks and cost incurred by the infrastructure networks.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.1
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• pp.18-25
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• 2006

In mobile ad-hoc networks(MANETs), nodes are mobile and network topology changes very frequently. The mobility of nodes does affect the system performance. There has been considerable attention on the mobility models, however, most work is confined to the simulation or test-bed. In this paper, we propose an analytical method to evaluate the performances of MANETs such as the average radio range dwell time of mobile nodes, link holding time, and transmission failure probability considering the node's mobility. In the proposed model, MANETs consist of the multi-hop and multicasting routing paths. A simulation is done to validate our proposed analytical model.

• Electronics and Telecommunications Trends
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• v.30 no.3
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• pp.95-104
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• 2015

모바일 빅뱅이라고 불리는 모바일 데이터 전송량의 폭발적인 증가로 촉발된 5G 이동통신에 대한 논의는 현재 ITU-R(International Telecommunication Union-Radio-communication)에서 5G 이동통신 네트워크 서비스 비전에 대한 직업을 진행 중이다. 5G 이동통신의 면적당 전송용량을 만족하기 위해서는 소형셀 형태로의 진화는 필연적이다. 본고에서는 5G 이동통신망 구성의 한 축을 담당할 것으로 예상되는 고정 무선링크 기술에 대한 개발동향을 소개한다. 고정 무선링크에 대한 사용 용도, 시장전망 그리고 현재 고정 무선링크 용도로 사용이 가능한 주파수 분배 현황에 대하여 살펴보고, 최근 고정 무선링크와 관련하여 시스템에 적용 중인 기술들과 새롭게 연구 중인 LOS(Light of Sight)-MIMO(Multi-Input Multi-Output), OAM(Orbital Angular Momentum) 등 관련 기술에 대한 개발동향을 소개한다.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.1
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• pp.66-73
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• 2016

An Inertial Measurement Unit (IMU)-based Attitude and Heading Reference System (AHRS) can calculate attitude and heading information with long-term accuracy and stability by combining gyro, accelerometer, and magnetic compass signals. Motivated by this characteristic of the AHRS, this paper presents a Motion-Tracking and Localization (MTL) method for a person or walking robot using multi-AHRSs. Five AHRSs are attached to the two calves, two thighs, and waist of a person/walking robot. Joints, links, and coordinate frames are defined on the body. The outputs of the AHRSs are integrated with link data. In addition, a supporting foot is distinguished from a moving foot. With this information, the locations of the joints on the local coordinate frame are calculated. The experimental results show that the presented MTL method can track the motion of and localize a person/walking robot with long-term accuracy in an infra-less environment.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.91-96
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• 2000

차세대 무선 통신 서비스의 응용은 다양한 형태로 발전하고 있다. 그 중에서 응급상황이나 학내망 같이 특수한 경우에 제공될 수 있는 시나리오로 다중 홉(Multi-hop) 다중 링크(Multi-link) ad-hoc 망을 들 수 있다. Ad-hoc망은 한정된 자원 문제와 변화가 심한 링크 용량문제가 있으며, 다중 홉상의 노드가 이동함으로 토폴로지의 동적 변화문제도 발생한다. 이러한 망의 노드는 송·수신단 역할을 할 뿐만 아니라 패킷을 전달하는 중간 노드의 역할도 하기 때문에 파워의 절약 매카니즘이 절실히 필요하게 된다. 본 논문은 PAMAS에 기반하여, 별도의 제어 채널에 버퍼를 두어 송·수신자 주소와 전송할 데이터의 크기의 정보를 버퍼에 기록하여 예약하고 제어 채널에서 데이터 채널의 파워를 제어할 수도 있으므로 데이터 전송에서 충돌을 예방하고 효율적으로 파워를 절약할 수 있다. 데이터 전송 발생율을 바꿔가며 시뮬레이션 결과 일반적인 방법을 사용한 노드들보다 훨씬 좋은 파워 절약을 이루고 있음을 알 수 있었다.

• Wind and Structures
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• v.4 no.6
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• pp.495-504
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• 2001

With a newly developed multi-force-balance system(MFB), a twin-tower structure was studied for its wind-induced responses. The MFB system allowed the twin towers, which were linked structurally, to be treated as a single structural system with its corresponding modes of vibration involving coupled motions of the two towers. The towers were also studied using a more conventional force balance approach in which each tower was treated as an isolated structure, i.e., as though no structural link existed. Comparison of the results reveals how the wind loads between the towers are redistributed through the structural links and the modal couplings. The results suggest that although the structural links usually have beneficial impacts on wind-induced response, they may also play a negative role if the frequency ratios of pair modes are near 1.0.