• 한국멀티미디어학회논문지
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• 제21권2호
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• pp.188-198
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• 2018

With recent development of high-speed wide-area wireless networks and wide spread of highperformance wireless devices, the demand on seamless video streaming services in Long Term Evolution (LTE) network environments is ever increasing. To meet the demand and provide enhanced Quality of Experience (QoE) with mobile users, the Dynamic Adaptive Streaming over HTTP (DASH) has been actively studied to achieve QoE enhanced video streaming service in dynamic network environments. However, the existing DASH algorithm to select the quality of requesting video segments is based on a procedural algorithm so that it reveals a limitation to adapt its performance to dynamic network situations. To overcome this limitation this paper proposes a novel quality selection mechanism based on a Deep Q-Network (DQN) model, the DQN-based DASH ABR($DQN_{ABR}$) mechanism. The $DQN_{ABR}$ mechanism replaces the existing DASH ABR algorithm with an intelligent deep learning model which optimizes service quality to mobile users through reinforcement learning. Compared to the existing approaches, the experimental analysis shows that the proposed solution outperforms in terms of adapting to dynamic wireless network situations and improving QoE experience of end users.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.242-248
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• 1987

Recently, a quite large number of investigation is published on the subject of Flexible Manufacturing System which can cope with the volatile market demand and the variety of product. Minimum requirement of designing FMS is depicted and by investigating the communication system between the machine tool and the cell control computer, ana between the central computer and the cell control computer, when it is formed as a sub-system of an FEM, the software can be evolved to the control software of the total Flexible Manufacturing System. It is developed the communication system between the central computer and the cell control computer which is the basic structure of the control architecture of FMS under the concept of DNC (Direct Numerical Control). It is used CYBER 180-830 as the central computer, and GMC-1100 computer as the cell control computer, and the main basic program is developed and tested, thus forming a DNC system which can be used in educational environment.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.223-230
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• 1999

The seismic damage assessment to the postulated earthquake is attempted for the buildings in the model district of Seoul City. The capacity spectrum method is employed in which the vulnerability functions are expressed as functions of the spectral displacement. the database of the building stock is constructed and managed using Geographic Information System software. The model district is selected to represent the typical structural and residential characteristics of Seoul City The structural properties were collected from the design documents. The field inspections were carried out to find out the current status of the building. They are classified into 11 structural types. The fragility curves in HazUS are employed, The ground motions from the postulated earthquakes are simulated using the Boor's methods, The surface soil in the district is classified into 3 profiles using the depth as the parameter. The one-dimensional wave propagation method is used to calculate he filtered ground motion through surface soil layer. The average spectrum of this sample time histories is used as the demand curves. The calculated results are expressed in maps using GIS software ArcView 3.0a

• 기술사
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• 제30권2호
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• pp.79-86
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• 1997

As network has high speed and wide communication capability, users demand diverse and new software to satisfy their needs. To meet users needs, the softwares for multimedia or groupware or distributed virtual environments can communicate the widely distributed information fast and accurately. Even though the technology for this is under development, it is deficient to support the reliable computer communication. Distributed Object System aims, as the new paradigm of distributed system software development to overcome this problem, to obtain in distributed environment the easiness of development and management, expandability, reusability which object oriented technologies support by solving the complexity of communication processing through the object oriented methods. This paper aims to introduce distributed object system, its technological properties and the current status and trend of technology development related to its standardization. Additionally, with explaining the Replicated Shared Object System(RSOS) which is developed in our country as one of the distributed object systems, its future prospects and technical issues are discussed.

• 드라이브 ㆍ 컨트롤
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• 제16권3호
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• pp.16-22
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• 2019

Due to the rise in energy consumption and natural resource prices, the demand to improve energy efficiency in the construction machine has been highlighted. Even though many researchers have contributed to the development of the technology, CO2 gas emissions of heavy machinery remains high. One of the most significant problems of the novel excavator with internal combustion engines is the emission of harmful gas. To reduce emissions in the construction machine, it is necessary to replace the internal combustion engines with the alternative one. To overcome those problems, this paper focuses on the adoption of PEMFC hybrid engine for the excavator system. An internal combustion engine is replaced by new structures with fuel cell, battery and ultra capacitor. The proposed system has been designed and modeled using Simcenter Amesim software and compared with the conventional one through simulation results.

• 국제초고층학회논문집
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• 제12권2호
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• pp.169-177
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• 2023

The massive increase in elevator usage and a severe demand for energy efficiency have prompted manufacturers to develop various innovative technologies, including AC and gearless motors, machine-room-less (MRL) technologies, regenerative drives, elevator ropes, and LED lighting. In addition, manufacturers are providing software solution systems such as destination dispatching systems, people flow solutions, standby mode, and predictive maintenance applications. Future technologies include electromagnetic levitation, circulating multi-car elevator systems, robotization, and drones. This article outlines elevators' technological advancements. It discusses how to harness new technologies and apply them to aging, modern, and future buildings.

• 디지털융복합연구
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• 제9권6호
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• pp.137-151
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• 2011

이 연구의 주요 목적은 지역 간 소프트웨어산업연관분석을 통해 지역 소프트웨어산업육성이 지역 경제에 미치는 효과를 경험적으로 분석해 보는데 있다. 소프트웨어산업이 지역경제에 미치는 영향 분석의 시간적 범위는 2008년 한국은행에서 발행된 2005년 지역산업연관표를 근간으로 분석하기 때문에 2005년으로 하고, 공간적 범위는 행정구역별 기준인 16개 광역시도별로 한정하였다. 지역 간 소프트웨어산업연관분석 결과를 요약하면 다음과 같다. 첫째, 지역별 소프트웨어산업의 평균 생산 유발효과는 1.6248로 전 산업 평균 생산유발효과 1.7979 대비 낮은 것으로 산정 되었다. 둘째, 이중에서 지역별 소프트웨어산업이 지역 내 타 산업에 미치는 생산유발효과는 0.1794로 전 산업 0.1382 대비 높게 나타났으나 지역별 소프트웨어산업의 지역 내 자기산업과 타지역 전 산업에 미치는 평균 생산 유발효과는 각각 1.0119와 0.4335로 전 산업 1.0982와 0.5616 대비 낮게 나타났다. 셋째, 지역별 소프트웨어산업의 최종수요 항목별 생산유발액은 서울이 17조 3,309억원인 전체의 81.0%로 가장 많으며, 다음은 경기가 2조 3,370억원인 10.9%로 많은 비중을 차지하였다. 넷째, 지역별 소프트웨어산업의 최종수요 발생에 따른 총생산유발의존도는 소비, 투자, 수출의 비중이 각각 19.1%, 72.1%, 8.8%로 나타나 전 산업의 생산유발의존도 각각 47.3%, 19.8%, 32.9% 대비 투자에 의한 생산유발의존도가 매우 높게 나타났다.

• 디지털융복합연구
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• 제14권11호
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• pp.297-304
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• 2016

본 연구의 목적은 애자일 개발 초기 단계에서 재사용의 지원을 통하여 애자일 방법과 소프트웨어 재사용의 통합이다. 애자일 방법과 소프트웨어 재사용은 각기 다른 원칙과 프랙티스를 가지고 있지만, 2가지 방법은 모두 개발 시간 및 비용 단축과 생산성 향상과 같은 공통된 목표를 가지고 있다. 이 방법들은 급변하는 환경에서 요구사항 변경의 수용이나 빠른 개발 요구에 대한 해결책으로 기대되고 있다. 본 연구에서는 절약형 애자일 재사용과 유형을 식별하고, 혼합 애자일 방법 초기 단계에서 칸반 보드의 입력 대기열을 위한 재사용 기술을 연구하였다. 본 연구의 결과를 통하여, 스크럼과 칸반 혼합 방법에서 입력 대기열 항목에 백로그 팩토링 기술을 사용하여 애자일 방법과 소프트웨어 재사용을 결합할 수 있었다. 아울러, 제안된 방법을 이클래스 응용에 적용하여 입력 대기열 항목의 재사용과 2가지 접근 방법의 통합을 보였다. 본 연구는 애자일 개발 초기에서의 재사용에 기여를 의도하였다. 앞으로, 절약형 애자일 재사용 도구를 개발할 계획이다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2022년도 추계학술발표대회
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• pp.377-379
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• 2022

POI refers to the point of Interest in Location-Based Social Networks (LBSNs). With the rapid development of mobile devices, GPS, and the Web (web2.0 and 3.0), LBSNs have attracted many users to share their information, physical location (real-time location), and interesting places. The tremendous demand of the user in LBSNs leads the recommendation systems (RSs) to become more widespread attention. Recommendation systems assist users in discovering interesting local attractions or facilities and help social network service (SNS) providers based on user locations. Therefore, it plays a vital role in LBSNs, namely POI recommendation system. In the machine learning model, most of the training data are stored in the centralized data storage, so information that belongs to the user will store in the centralized storage, and users may face privacy issues. Moreover, sharing the information may have safety concerns because of uploading or sharing their real-time location with others through social network media. According to the privacy concern issue, the paper proposes a recommendation model to prevent user privacy and eliminate traditional RS problems such as cold-start and data sparsity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5223-5242
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• 2017

In the last decade, the 2.4 GHz band of IEEE 802.11 WLANs has become heavily congested due to the explosive increase in demand of Wi-Fi connectivity. With the current deployment of enterprise WLANs, channel switching mechanism continues to exhibit inefficiencies because it cannot adapt to real-time channel condition and the inability to support seamless channel switching. Software Defined Networking (SDN) as an emerging architecture is promising to introduce flexibility and programmability for wireless network management. Leveraging SDN to existing enterprise WLANs, channel switching method can be improved significantly. This paper presents a software-defined enterprise WLAN framework with a load aware automatic channel switching solution, which utilizes AP load and channel interference factor (CIF) to provide seamless channel switching. Two automatic channel switching algorithms named Single Switch (SS) and Double Switch (DS) are proposed to improve the overall user experience and the experience of users with highest traffic load respectively. Experiment results demonstrate that our solution can efficiently improve user experience in terms of jitter, transmission delay and network throughout when compared to the conventional channel switching mechanism.