• 한국산학기술학회논문지
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• 제13권12호
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• pp.6098-6104
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• 2012

현재 철도 역사의 승객 위험영역과 보안영역 등의 감시를 위해 수십대의 CCTV를 널리 이용하고 있다. 그중에서 가장 빈번한 사고가 발생되는 곳은 승객의 열차 승하차가 이루어지는 승강장 영역이다. 하지만 사고 예방과 신속한 대응을 위해 역무원이 여러 대의 CCTV를 항시 모니터링 하기는 불가능하다. 따라서 위험상황을 자동으로 인지할 수 있는 영상처리 기술을 이용한 승강장 모니터링 시스템이 요구되며, 이를 위해서는 우선적으로 승강장에서의 정확한 열차상태 판단이 필요하다. 본 논문은 비전기반 승강장 모니터링 시스템을 위한 승강장에서의 열차상태에 대한 검지방법을 제안한다. 제안된 검지 방법은 승강장에서의 열차 점유영역을 분석하여 열차의 진입(IN), 진출(OUT), 정지(ON), 없음(OFF)의 4가지 생태를 판별한다. 제안된 검지방법의 성능 평가을 위해 서울메트로 4호선 동작역과 남태령역을 대상으로 열차상태 검지결과를 제시하였다.

• Structural Engineering and Mechanics
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• 제61권6호
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• pp.785-794
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• 2017

This paper is concerned with the comparative numerical and experimental study on the natural behavior and the motion responses of a 1/75 moored scale model of a 2.5 MW spar-type floating offshore wind turbine subject to 1-D regular wave. Heave, pitch and surge motions and the mooring tensions are investigated and compared by numerical and experimental methods. The upper part of wind turbine which is composed of three rotor blades, hub and nacelle is modeled as a lumped mass and three mooring lines are pre-tensioned by means of linear springs. The numerical simulations are carried out by a coupled FEM-cable dynamics code, while the experiments are performed in a wave tank equipped with the specially-designed vision and data acquisition system. Using the both methods, the natural behavior and the motion responses in RAOs are compared and parametrically investigated to the fairlead position, the spring constant and the location of mass center of platform. It is confirmed, from the comparison, that both methods show a good agreement for all the test cases. And, it is observed that the mooring tension is influenced by all three parameters but the platform motion is dominated by the location of mass center. In addition, from the sensitivity analysis of RAOs, the coupling characteristic of platform motions and the sensitivities to the mooring parameters are investigated.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권1호
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• pp.13-21
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• 2016

Parametric pitch instability of a Deep Draft Semi-submersible platform (DDS) is investigated in irregular waves. Parametric pitch is a form of parametric instability, which occurs when parameters of a system vary with time and the variation satisfies a certain condition. In previous studies, analyzing of parametric instability is mainly limited to regular waves, whereas the realistic sea conditions are irregular waves. Besides, parametric instability also occurs in irregular waves in some experiments. This study predicts parametric pitch of a Deep Draft Semi-submersible platform in irregular waves. Heave motion of DDS is simulated by wave spectrum and response amplitude operator (RAO). Then Hill equation for DDS pitch motion in irregular waves is derived based on linear-wave theory. By using Bubnov-Galerkin approach to solve Hill equation, the corresponding stability chart is obtained. The differences between regular-waves stability chart and irregular-waves stability chart are compared. Then the sensitivity of wave parameters on DDS parametric pitch in irregular waves is discussed. Based on the discussion, some suggestions for the DDS design are proposed to avoid parametric pitch by choosing appropriate parameters. The results indicate that it's important and necessary to predict DDS parametric pitch in irregular waves during design process.

• Structural Engineering and Mechanics
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• 제54권5호
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• pp.909-922
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• 2015

The dynamic response and the mooring line tension of a 1/75 scale model of spar-type platform for 2.5 MW floating offshore wind turbine subject to one-dimensional regular harmonic wave are investigated numerically and verified by experiment. The upper part of wind turbine which is composed of three rotor blades, hub and nacelle is modeled as a lumped mass the scale model and three mooring lines are pre-tensioned by means of linear springs. The coupled fluid-rigid body interaction is numerically simulated by a coupled FEM-cable dynamics code, while the experiment is performed in a wave tank with the specially-designed vision and data acquisition system. The time responses of surge, heave and pitch motions of the scale platform and the mooring line tensions are obtained numerically and the frequency domain-converted RAOs are compared with the experiment.

• 한국CDE학회논문집
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• 제20권4호
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• pp.420-430
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• 2015

Operator Training Simulators (OTSs) provide macroscopic training environment for plant operation. They are equipped with simulation systems for the emulation of remote monitoring and controlling operations. OTSs typically provide 2D block diagram-based graphic user interface (GUI) and connect to process simulation tools. However, process modeling for OTSs is a difficult task. Furthermore, conventional OTSs do not provide real plant field information since they are based on 2D human machine interface (HMI). In order to overcome the limitation of OTSs, we propose a new type of plant training system. This system has the capability required for collaborative training between operators and field workers. In addition, the system provides 3D virtual training environment such that field workers feel like they are in real plant site. For this, we designed system architecture and developed essential functions for the system. For the verification of the proposed system design, we implemented a prototype training system and performed experiments of collaborative training between one operator and two field workers with the prototype system.

• Journal of Information Processing Systems
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• 제19권4호
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• pp.450-464
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• 2023

To address the problems of large system overhead and low timeliness when dealing with task scheduling in mobile edge cloud computing, a task scheduling and resource management strategy for edge cloud computing based on an improved genetic algorithm was proposed. First, a user task scheduling system model based on edge cloud computing was constructed using the Shannon theorem, including calculation, communication, and network models. In addition, a multi-objective optimization model, including delay and energy consumption, was constructed to minimize the sum of two weights. Finally, the selection, crossover, and mutation operations of the genetic algorithm were improved using the best reservation selection algorithm and normal distribution crossover operator. Furthermore, an improved legacy algorithm was selected to deal with the multi-objective problem and acquire the optimal solution, that is, the best computing task scheduling scheme. The experimental analysis of the proposed strategy based on the MATLAB simulation platform shows that its energy loss does not exceed 50 J, and the time delay is 23.2 ms, which are better than those of other comparison strategies.

• 디지털융복합연구
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• 제19권10호
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• pp.303-317
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• 2021

본 연구는 OTT 산업에 특화된 분석틀을 개발하여 OTT 사업자들의 경쟁력 분석을 하는 데에 목적이 있다. 비즈니스 모델, 플랫폼 비즈니스 모델, OTT 특성에 관한 기존연구를 바탕으로 OTT 플랫폼 비즈니스 모델 프레임워크를 개발하였고 관련 자료, 문헌, 내부자료의 데이터를 토대로 사례 분석을 하여 국내 OTT 사업자들이 나아가야 할 방향을 제시하였다. 연구 결과, 국내 OTT 사업자들은 발전된 AI와 빅데이터 기술을 활용해 오리지널 콘텐츠를 제작하고 플랫폼의 인프라 및 서비스의 질을 향상해야 한다. 또한, 보유한 콘텐츠를 맞춤화된 추천 시스템을 통해 충분히 활용할 수 있어야 하고 이용자들이 선호할 해당 플랫폼만의 오리지널 콘텐츠에 아낌없는 투자가 지속되어야 한다. 본 연구는 급변하는 미디어 산업 속에서 OTT 사업자들이 자신만의 경쟁전략을 수립할 수 있는 분석틀을 제공하고 사례 적용을 통해 국내 OTT 사업자들이 나아가야 할 방향성을 제시했다는 점에서 의의가 있다.

• 한국IT서비스학회지
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• 제20권2호
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• pp.127-146
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• 2021

Donation-based crowdfunding(DBC) is conducted from voluntary participation by project operators. It requires a different operational strategy than general crowdfunding. However, there is a limited amount of research on the operational strategy of DBC. This study explores the value co-creation(VCC) strategy of DBC and analyzes the operation of DonorsChoose.org. The research questions encompass the following: First, we identify the VCC activities of DBC. Second, we uncover activities of the platform operators that facilitate the participation of project operators in VCC activities. Third, we explore how VCC activities affect project operational performance and platform performance in DBC. By adopting a single case study method on DonorsChoose.org, this study provides meaningful insight and detailed understanding into the VCC in DBC. First, VCC processes of DBC are identified(Co-ideation, Co-design, Co-funding, Co-operation, and Co-evaluation). Also, interactions between platform operators and project operators were defined at each stage. Second, this study confirmed that standardization and simplification of platform operators, support for pre- and post-activity, and high-quality information delivery activities were critical. Third, we confirm that these VCC activities improve VCC operational performance and platform performance. The theoretical significance of this study is that the concept of VCC, previously concentrated on participants with economic drivers(consumers and investors), has been applied to the context of DBC, a form of participation by participants with non-economic drivers(supporters and donors). In addition, this study practically contributes to the practice of VCC strategy among various platform operating strategies in DBC.

• 한국정보통신학회논문지
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• 제26권1호
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• pp.153-161
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• 2022

본 연구는 콘텐츠 제공자를 포함한 플랫폼 사업자가 광대역 인터넷 접속을 통해 고품질의 콘텐츠를 제공하는 경우 보편적 서비스 기여금을 분담할 때 이것의 경제적 효과를 분석한다. 주요 결과는 다음과 같다. 첫째, 플랫폼 사업자가 독점적 위치에 있다면 트래픽 이용량은 사회적 최적 수준보다 적으며, ISP가 결정하는 가격들은 콘텐츠 수요의 가격민감도에 영향을 받는다. 둘째, 플랫폼 사업자가 경쟁적인 경우 ISP가 책정하는 요금은 사회적 최적 수준과 동일하다. 셋째, 플랫폼 사업자가 콘텐츠 요금을 부과하지 않는 경우는 ISP는 요금을 사회적 최적 수준으로 결정하고 광고 수입이 많을수록 소비자에게 부과하는 망 이용대가는 줄어든다. 이는 플랫폼 사업자에게 고품질 콘텐츠 서비스를 제공할 수 있는 네트워크 서비스를 이용하는 대신, 보편적 서비스 기여분 분담을 의무화한다면 사회후생은 증가될 수 있기 때문에 플랫폼 사업자에게 보편적 서비스 기여분을 분담하는 것이 사회적으로 바람직하다는 것을 시사해 준다.

• 한국CDE학회논문집
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• 제20권3호
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• pp.281-290
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• 2015

The specific goal of the SMS (Ship Management System) is to increate ship safety and decrease maintenance fee. Equipment of ship is managed by PMS (Planned Management System), subsystem of SMS. But hull has not managed by ship manager. So, the Classes have developed the system for hull maintenance. Recently, the ship maintenance system has been developed for satisfying operator's requirements such as managing maintenance data as integrated platform, intuitive manipulation and design for ease of use. To reflect such requirement, 3D Model based maintenance system was introduced for ship in operation stage. Hull items that have to be inspected, repaired, replaced, are stored in integrated data platform with drawing, reports, and etc. and completely linked to 3D product Model. This system is specially developed for measurement and maintenance of hull thickness.