• 한국콘텐츠학회논문지
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• 제19권1호
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• pp.132-140
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• 2019

최근 전 세계 많은 도시는 교통량 및 대기오염을 감축하기 위해 공유자전거 시스템을 도입하여 운영하고 있고, 서울시에서도 2015년부터 따릉이 공유자전거 서비스를 제공하고 있다. 공유자전거의 사용이 확산됨에 따라 대여소별로 자전거의 수요는 증가하고 있으나, 제한된 예산 하에서 대여소별로 수요를 관리하기 때문에 운영 및 관리상의 어려움이 존재한다. 현재 자전거 재배치를 통해 대여소별로 수요의 변동을 해결하려고 노력하고 있으나, 불확실한 미래의 사용자 수요를 정확히 예측하는 것이 보다 근본적인 방안이다. 본 연구에서는 통계적 시계열 분석을 통해 서울시 따릉이의 수요를 예측하는 모델을 개발하고, 이를 실제 데이터를 통해 분석하고자 한다. 특히, 전기 사용량의 수요에 사용했던 Holt-Winters방법을 따릉이 수요 예측을 위해 변형하여 적용하였고, 또한 파라미터들의 변동이 실제 수요예측에 어떠한 영향을 미치는지 민감도 분석도 수행하였다.

• 한국정보통신학회논문지
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• 제17권6호
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• pp.1375-1382
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• 2013

공유 화이트보드는 여러 사람들과 실시간으로 공유할 수 있는 그림 작업장을 제공한다. 공유 화이트보드는 협업이나 커뮤니케이션을 위한 다양한 그리기 도구를 제공하기 때문에 가상 회의와 같은 공동 작업에서 효과적인 수단으로 사용된다. 본 논문에서는 공유 화이트보드 기능을 제공하는 XMPP 클라이언트 어플리케이션인 SyncNote에 대하여 기술한다. 또한 공유 화이트보드 기능을 제공하기 위하여 오픈 표준 커뮤니케이션 프로토콜인 XMPP의 확장을 제안한다. 안드로이드 플랫폼에서 동작하는 SyncNote 어플리케이션은 그룹 사용자들에 의하여 생성된 그림과 이미지의 공유를 통하여 효과적인 커뮤니케이션을 제공한다.

• 한국컴퓨터정보학회논문지
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• 제3권2호
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• pp.169-175
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• 1998

ATM스위치에서 셀을 전송하기 위한 버퍼방식으로 HOL 블록킹을 방지하는 공유다중버퍼 방식이 있다. 그러나, 이러한 방식에서도 셀 손실이 발생하여 스위치의 성능을 저하시킨다. 따라서, 본 논문에서는 기존의 비충돌 공유 다중 버퍼 구조에서 발생하는 셀 손실을 방지하는 방안을 제안하였다. 셀 손실을 방지하는 방안으로 한 슬롯 타임동안에 손실되는 셀을 다음 슬롯 타임에 전송할 수 있도록 특정한 임시메모리에 저장할 수 있는 구조를 사용하였다. 이러한 구조를 시뮬레이션을 통해 성능평가를 한 결과 셀 손실율과 처리율면에서 기존의 시스템보다 우수함을 검증하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2568-2588
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• 2021

Shared mesh protection (SMP) protects traffic against failures occurring in a working path, as with linear protection, and allows resource sharing of protection paths with different endpoints. The SMP mechanism coordinates multiple protection paths that require shared resources when failures occur on multiple working paths. When multiple failures occur in SMP networks sharing limited resources, activation can fail because some of the resources in the protection path are already in use. In this case, a node confirming that a resource is not available has the option to wait until the resource is available or to withdraw activation of the protection path. In this study, we recognize that the protection switching time and the number of protected services can be different, depending on which option is used for SMP networks. Moreover, we propose a detailed design for the implementation of SMP by considering options and algorithms that are commonly needed for network nodes. A simulation shows the performance of an SMP system implemented with the proposed design and utilizing two options. The results demonstrate that resource utilization can be increased or protection switching time can be shortened depending on the option selected by the network administrator.

• 한국멀티미디어학회논문지
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• 제24권8호
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• pp.1138-1148
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• 2021

In this study, we developed a 'shared-use mobility'-mounted local particulate matter monitoring terminal technology to measure the actual particulate matter concentration around me. As a mobile terminal device in the form of an IoT sensor platform, it is designed to be separated into a control module and a sensor module to minimize interference between sensors and to consider the optimal observation position of each sensor. As a result of the field test, it was confirmed that particulate matter was locally different depending on time and space even within the same area. In addition, it was confirmed that the concentration of particulate matter in the relevant section differed by up to 100 times compared to the surrounding area due to specific sources of particulate matter such as unpaved roads. In addition, we positively reviewed the applicability of the service in the real-time metaverse environment using this result. Through technological advancement and application of multiple shared-use mobilities, we expect to be able to provide new services for practical smart city air environment monitoring, such as localized particulate matter information, air pollution event information, and identification of causes of particulate matter.

• 제어로봇시스템학회논문지
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• 제21권3호
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• pp.243-249
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• 2015

In direct vehicle teleoperation, a human operator drives a vehicle at a distance through a pair of master and slave device. However, if there is time delay, it is difficult to remotely drive the vehicle due to slow response. In order to address this problem, we introduced a novel methodology of shared vehicle teleoperation using a virtual driving interface. The methodology was developed with four components: 1) virtual driving environment, 2) interface for virtual driving environment, 3) path generator based on virtual driving trajectory, 4) path following controller. Experimental results showed the effectiveness of the proposed approach in simple and cluttered driving environment as well. In the experiments, we compared two sampling methods, fixed sampling time and user defined instant, and finally merged method showed best remote driving performance in term of completion time and number of collision.

• Journal of Communications and Networks
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• 제17권3호
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• pp.286-295
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• 2015

Avionic databuses fulfill a critical function in the connection and communication of aircraft components and functions such as flight-control, navigation, and monitoring. Ethernet-based avionic databuses have become the mainstream for large aircraft owning to their advantages of full-duplex communication with high bandwidth, low latency, low packet-loss, and low cost. As a new generation aviation network communication standard, avionics full-duplex switched ethernet (AFDX) adopted concepts from the telecom standard, asynchronous transfer mode (ATM). In this technology, the switches are the key devices influencing the overall performance. This paper reviews the avionic databus with emphasis on the switch architecture classifications. Based on a comparison, analysis, and discussion of the different switch architectures, we propose a new avionic switch design based on a time-division switch fabric for high flexibility and scalability. This also merges the design concept of space-partition switch fabric to achieve reliability and predictability. The new switch architecture, called space partitioned shared memory switch (SPSMS), isolates the memory space for each output port. This can reduce the competition for resources and avoid conflicts, decrease the packet forwarding latency through the switch, and reduce the packet loss rate. A simulation of the architecture with optimized network engineering tools (OPNET) confirms the efficiency and significant performance improvement over a classic shared memory switch, in terms of overall packet latency, queuing delay, and queue size.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.636-647
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• 2004

The objective of this paper is to provide an improved reorder decision policy for general multi-echelon distribution systems utilizing the shared stock information. It has been known that traditional reorder policies sometimes show poor performance in distribution systems. Thus, in our previous research we introduced the order risk policy which utilizes the shared stock information more accurately for the 2-echelon distribution system and proved the optimality. However, since the real world supply chain is generally composed with more than 2 echelons, we extend the order risk policy for the general multi-echelon systems. Since the calculation of the exact order risk value for general multi-echelon systems is very complex, we provide two approximation methods for the real-time calculation. Through the computational experiment comparing the order risk policy with the existing policies under various conditions, we show the performance of the order risk policy and analyze the value of the shared stock information varying with the characteristics of the supply chain.

• 산업공학
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• 제17권3호
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• pp.359-374
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• 2004

The objective of this paper is to provide an improved reorder decision policy for general multi-echelon distribution systems utilizing the shared stock information. It has been known that traditional reorder policies sometimes show poor performance in distribution systems. Thus, in our previous research we introduced the order risk policy which utilizes the shared stock information more accurately for the 2- echelon distribution system and proved the optimality. However, since the real world supply chain is generally composed with more than 2 echelons, we extend the order risk policy for the general multi-echelon systems. Since the calculation of the exact order risk value for general multi-echelon systems is very complex, we provide two approximation methods for the real-time calculation. Through the computational experiment comparing the order risk policy with the existing policies under various conditions, we show the performance of the order risk policy and analyze the value of the shared stock information varying with the characteristics of the supply chain.

• Journal of Computing Science and Engineering
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• 제6권4호
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• pp.267-278
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• 2012

The state-of-the-art techniques in multicore timing analysis are limited to analyze multicores with shared instruction caches only. This paper proposes a uniform framework to analyze the worst-case performance for both shared instruction caches and data caches in a multicore platform. Our approach is based on a new concept called address flow graph, which can be used to model both instruction and data accesses for timing analysis. Our experiments, as a proof-of-concept study, indicate that the proposed approach can accurately compute the worst-case performance for real-time threads running on a dual-core processor with a shared L2 cache (either to store instructions or data).