• ETRI Journal
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• v.45 no.6
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• pp.963-973
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• 2023

Non-orthogonal multiple access (NOMA) is considered a key candidate technology for next-generation wireless communication systems due to its high spectral efficiency and massive connectivity. Incorporating the concepts of multiple-input-multiple-output (MIMO) into NOMA can further improve the system efficiency, but the hardware complexity increases. This study develops an energy-efficient (EE) subchannel assignment framework for MIMO-NOMA systems under the quality-of-service and interference constraints. This framework handles an energy-efficient co-training-based semi-supervised learning (EE-CSL) algorithm, which utilizes a small portion of existing labeled data generated by numerical iterative algorithms for training. To improve the learning performance of the proposed EE-CSL, initial assignment is performed by a many-to-one matching (MOM) algorithm. The MOM algorithm helps achieve a low complex solution. Simulation results illustrate that a lower computational complexity of the EE-CSL algorithm helps significantly minimize the energy consumption in a network. Furthermore, the sum rate of NOMA outperforms conventional orthogonal multiple access.

• Proceedings of the Safety Management and Science Conference
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• 2010.11a
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• pp.349-355
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• 2010

EPCIS(EPC Information Services) system is a core component of EPCglobal Architecture Framework offering information of the freights, the time of awareness and the location of awareness on the EPCglobal Network. The role of EPCIS is to exchange information based on EPC. There are four kinds of event data which are object event data, aggregation event data, quantity event data, and transaction event data. These EPCIS events data are stored and managed in EPCIS repository. This paper leads to separate a in-out data overload of integrated EPCIS event and suggests the method to effectively manage EPCIS repository for exchanging data smoothly. In order to verify a effectiveness, we measure the performance of the system using a simple testing simulation by comparing existing method and suggested method.

• ETRI Journal
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• v.25 no.1
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• pp.25-33
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• 2003

This paper describes interactive dynamic simulation schemes for articulated bodies in virtual environments, where user interaction is allowed through a haptic interface. We incorporated these schemes into our dynamic simulator I-GMS, which was developed in an object-oriented framework for simulating motions of free bodies and complex linkages, such as those needed for robotic systems or human body simulation. User interaction is achieved by performing push and pull operations with the PHANToM haptic device, which runs as an integrated part of I-GMS. We use both forward and inverse dynamics of articulated bodies for the haptic interaction by the push and pull operations, respectively. We demonstrate the user-interaction capability of I-GMS through on-line editing of trajectories for 6-dof (degrees of freedom) articulated bodies.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.957-962
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• 2008

We propose a model for the line expansion problem in the AMOLED (Active Matrix Organic Light Emitting Diodes) industry, which now faces market uncertainty: for example, changing customer needs, technological development path, etc. We focus on the optimal investment time and size of the AMOLED production lines. In particular, employed here is the ROV (Real Options Valuation) model to show how to capture the value of line expansion and to determine the optimal investment time. The ROV framework provides a systematic procedure to quantify an expected outcome of a flexible decision which is not possible in the frame of the traditional NPV (Net Present Value) approach. Furthermore, we also use Monte Carlo simulation to measure the uncertainty associated with the line expansion decision; Monte Carlo simulation estimates the volatility of a decision alternative. Lastly, we present a scenario planning to be conducted for what-if analysis of the ROV model.

• Earthquakes and Structures
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• v.13 no.3
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• pp.299-307
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• 2017

High Damping Rubber bearings (HDR bearings) have been used in the seismic design of bridge structures widely in China. In earthquakes, structural natural periods will be extended, seismic energy will be dissipated by this kind of bearing. Previously, cyclic loading method was used mainly for test studies on mechanical properties of HDR bearings, which cannot simulate real seismic responses. In this paper, Real-Time Substructure (RTS) test study on mechanical properties of HDR bearings was conducted and it was found that the loading rate effect was not negligible. Then the influence of peak acceleration of ground motion was studied. At last test results were compared with a numerical simulation in the OpenSees software framework with the Kikuchi model. It is found that the Kikuchi model can simulate real mechanical properties of HDR bearings in earthquakes accurately.

• Journal of the Korea Safety Management & Science
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• v.12 no.4
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• pp.169-174
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• 2010

EPCIS(EPC Information Services) system is a core component of EPCglobal Architecture Framework offering information of the freights, the time of awareness and the location of awareness on the EPCglobal Network. The role of EPCIS is to exchange information based on EPC. There are four kinds of event data which are object event data, aggregation event data, quantity event data, and transaction event data. These EPCIS events data are stored and managed in EPCIS repository. This paper deals with the method which diversifies the data flow load of intensive EPCIS events and effectively manages EPCIS repository for exchanging data smoothly. In order to verify a effectiveness, we measure the performance of the system using a simulation by comparing the existing method with the suggested method.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.118-124
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• 2000

본 논문은 계층 구조적이고 모듈화 된 모델링 및 시뮬레이션 프레임워크를 이용한 네트워크 보안 모델링과 사이버 공격에 대한 시뮬레이션 기법의 연구를 주목적으로 한다. 단순한 네트워크 모델에서의 원인-결과 모델을 대상으로 시뮬레이션 하는 기존의 접근방법과는 달리, 복잡한 네트워크 보안 모델과 모델 기반의 사이버 공격에 대한 시뮬레이션 기법은 아직까지 시도된 바가 없는 실정이다. 따라서, 본 논문에서는 첫째, System Entity Structure/Model Base(SES/MB)을 통하여 계층 구조적, 모듈화, 객체지향적 설계를 하였고 둘째, 해킹 행위의 상세분석을 위해 취약성을 고려한 명령어 수준의 네트워크 보안 모델링 및 시뮬레이션 방법론을 제안하였다. 마지막으로, 사이버 공격 시나리오를 이용한 사례연구를 통하여 타당성을 검증하였다.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.174-179
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• 2000

Proposed in the paper is a V-FMS (Virtual Flexible Manufacturing System) model to be used as a prototyping tool for FMS design. The proposed V-FMS framework follows an object-oriented modeling (OOM) paradigm and is based on a set of user requirements for FMS prototyping. The V-FMS model consists of four types of object: virtual device, transfer handler, state manager and flow controller. A virtual device model, which corresponds to a static model in OOM, consists of two parts, shell and core, for reusability. A transfer handler corresponds to a functional model of OOM and it stores low level device commands required to perform job flow operations between giving and taking devices. The state manager and the flow controller constitute a dynamic model of OOM. The proposed V-FMS model has been implemented for a couple of linear type FMS-lines

• Nuclear Engineering and Technology
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• v.49 no.6
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• pp.1339-1345
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• 2017

In the framework of the EU funded project NURESAFE, the subchannel code CTF and the neutronics code DYN3D were integrated and coupled on the NURESIM platform. The developments achieved during this 3-year project include assembly-level and pin-by-pin multiphysics thermal hydraulics/neutron kinetics coupling. In order to test this coupling, a PWR rod ejection transient was simulated on a MOX/UOX minicore. The transient is simulated using two different models of the minicore. In the first simulation, both codes model the core with an assembly-wise resolution. In the second simulation, a pin-by-pin fuel-centered model is used in CTF for the central assembly, and a pin power reconstruction method is applied in DYN3D. The analysis shows the influence of the different models on global parameters, such as the power and the average fuel temperature, but also on local parameters such as the maximum fuel temperature.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.157-164
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• 2003

A simulation-based approach that can be used to systematically model the uncertainties of seismic loading and geotechnical property is presented in the context of reliability analysis of slope stability. The uncertainty of seismic loading is studied by generating a large series of hazard-compatible artificial motions, and by using them in subsequent response analyses. The stochastic nature of spatially varying material properties and also the uncertainty arising from insufficient information are treated in the framework of random fields. The simulation-based analyses indicate that in a seismically less active region, a moderate variability in soil properties has a relatively large effect as much as characterization of earthquake hazard on the computed risk of slope failure and excessive slope deformations.