• 산업공학
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• 제11권2호
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• pp.13-24
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• 1998

A distribution system is composed of multiple levels from a producer to customers, and it's objective is to supply customers with goods timely with a prescribed level of quality at a minimum cost. For the installation and operation of multi-echelon distribution system, DRP(Distribution Resource Planning) is widely used. However, because of the characteristic difference of material flow dynamic of each distribution center, it is almost impossible to get the optimal distribution scheduling. In this paper, an improved DRP method to schedule multi-echelon distribution network is proposed so that the lot-size and order point is dynamically obtained to meet the change of demand rate and timing. The experiment is done with various demand pattern, forecast errors of demand and lead times of central distribution center. The proposed method is compared with traditional statistical approach.

• 산업공학
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• 제19권4호
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• pp.291-299
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• 2006

In order to enhance sustainable war fighting capabilities, it is important to maintain a good ammunition support system. In this paper, we evaluate the performance of ammunition companies using Imprecise Data Envelopment Analysis (IDEA)-BCC and IDEA-Additive model, which can deal with imprecise data in DEA. The input variables of IDEA models were selected by stepwise multiple regression analysis. With the regression model, we could choose the number of soldiers, officers, and ammunition warehouses as input variables that have significant effects on the output performance. Then, we applied the IDEA-BCC model with the concept of potential efficiency. The results of the model indicate that 8 out of 16 ammunition companies are efficient, 7 are inefficient, and 1 is potentially efficient. We could also identify the possible input excesses and output shortfalls to reach the efficient frontier using the IDEA-Additive model.

• 대한음성학회지:말소리
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• 제58호
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• pp.101-117
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• 2006

The development of efficient multimodal interfaces and fusion algorithms requires knowledge of usage patterns that show how people use multiple modalities. We analyzed multimodal usage patterns for TV-guide application scenarios (or tasks). In order to collect usage patterns, we implemented a multimodal usage pattern collection system having two input modalities: speech and touch-gesture. Fifty-four subjects participated in our study. Analysis of the collected usage patterns shows a positive correlation between the task type and multimodal usage patterns. In addition, we analyzed the timing between speech-utterances and their corresponding touch-gestures that shows the touch-gesture occurring time interval relative to the duration of speech utterance. We believe that, for developing efficient multimodal fusion algorithms on an application, the multimodal usage pattern analysis for the given application, similar to our work for TV guide application, have to be done in advance.

• 지식정보인프라
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• 통권7호
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• pp.141-148
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• 2001

This paper describes a mechanisms for IPv6 multihomming with loadsharing broker, focusing on the interdomain scalability and load sharing with redundancy on IPv6 networks. Unlike currently-practiced IPv4 multihoming, this model does not impact the worldwide routing table size, also it provides inbound load sharing at site level based on router renumbering, and multiple-prefix assigning techniques of IPv6. The proposed model has four modules such as building interfaces MIB module, priority list maintaining module, load detection module, and RRP configuration module.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권4호
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• pp.1249-1265
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• 2022

Video streaming has become one of the most popular applications for mobile devices. The network bandwidth required for video streaming continues to exponentially increase as video quality increases and the user base grows. Multi-Path TCP (MPTCP), which allows devices to communicate simultaneously through multiple network interfaces, is one of the solutions for providing robust and reliable streaming of such high-definition video. However, mobile video streaming over MPTCP raises new concerns, e.g., power consumption and cellular data usage, since mobile device resources are constrained, and users prefer to minimize such costs. In this work, we propose a mobile video streaming framework over MPTCP (mDASH) to reduce the costs of energy and cellular data usage while preserving feasible streaming quality. Our evaluation results show that by utilizing knowledge about video behavior, mDASH can reduce energy consumption by up to around 20%, and cellular usage by 15% points, with minimal quality degradation.

• ETRI Journal
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• 제46권3호
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• pp.501-512
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• 2024

With an explosive increase of data produced annually, researchers have been attempting to develop solutions for systems that can effectively handle large amounts of data. Single-operating-system (OS) non-uniform memory access (NUMA) abstraction technology is an important technology that ensures the compatibility of single-node programming interfaces across multiple nodes owing to its higher cost efficiency compared with scale-up systems. However, existing technologies have not been successful in optimizing user performance. In this paper, we introduce a single-OS NUMA abstraction technology that ensures full compatibility with the existing OS while improving the performance at both hypervisor and guest levels. Benchmark results show that the proposed technique can improve performance by up to 4.74× on average in terms of execution time compared with the existing state-of-the-art opensource technology.

• 정보과학회 논문지
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• 제42권6호
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• pp.807-816
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• 2015

최근 주목 받고 있는 사물인터넷(Internet of Things)환경에서는 와이파이와 블루투스 같은 다양한 무선 표준들이 공존한다. 이러한 사물인터넷(IoT) 환경에서는 이종 무선 통신망 간의 핸드오버를 통하여 보다 안정적이고 효율적인 패킷 전송이 가능하다. 이에 본 논문에서는 사물인터넷 환경에서 다양한 무선표준과 통신프로토콜을 지원하는 IoT 브로커를 이용하여 와이파이와 블루투스 사이의 이종망 간 수직 핸드오버(Vertical handover) 시스템을 구현하였다. 핸드오버 시점 결정을 위하여 블루투스 프로토콜 스택(BlueZ)에서 제공하는 함수를 이용한 LQ(Link Quality)및 RSSI(Received Signal Strength Indication)측정 실험과 리눅스에서 제공하는 네트워크 정보를 활용한 사용자의 실시간 트래픽 측정 실험을 통해 최적의 Threshold값을 선정하였다. 실제 하드웨어를 사용한 실험을 통해 제안 방법이 에너지 효율을 향상시키고 QoS(Quality of Service)를 보장할 수 있음을 확인하였다.

• 한국항공우주학회지
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• 제35권6호
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• pp.556-563
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• 2007

저 비용으로 개발되는 초소형 위성의 경우 개발비용을 줄이기 위해서 상용제품(COTS; Commercial-Off-The Shelf)을 많이 사용하는 추세이며, 따라서 실제 위성을 운용하고 데이터를 수집 처리하는 명령 및 데이터 처리계(C&DH; Command and Data Handling)도 상용 컨트롤러를 중심으로 설계 및 개발되고 있다. 하지만 상용 컨트롤러는 그 기능이 제작사의 규격에 따라 한정되어 있기 때문에 다양한 인터페이스를 갖는 위성 개발에 적용할 경우 별도의 인터페이스 회로 구성이 필수적이다. 따라서 상용 컨트롤러가 지원하지 못하는 다수의 디지털 인터페이스를 쉽게 확장하고 SEU 보상을 위해서 FPGA(Field Programmable Gate Array)를 이용한 다중 디지털 데이터 처리 시스템(MDDCS; Multi Digital Data Control System)을 개발하였다. 개발 언어로 VHDL(Very High Speed Integrated Circuits Hardware Description Language)을 사용하였으며 Actel의 A3P1000에 구현하였다.

• 한국실내디자인학회논문집
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• 제22권5호
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• pp.302-310
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• 2013

Many museums have recently employed digital technologies in exhibition installations to provide visitors with interactive experiences with the installations, not just audiences. However, most of them have focused on the adoption of new prototypes or technologies, not considering user experiences of those systems carefully. This study developed an evaluation tool for usability of the tangible user interfaces and conducted a usability study on museum installations emphasizing user interaction and experience. The evaluation tool is composed of 5 features of tangible user interfaces such as tangible, interaction, convenience, representation, spatial interaction and social interaction, and 24 items. The museum we investigated is the Gwacheon National Science Museum, where 8 installations, classified 4 categories, were selected for the usability study. We recruited 6 undergraduate students, who were divided into 2 teams, each team having 3 students. Three students in a team manipulated and experience each installation together and reported their evaluation score through the questionnaire and interviews. The results showed that the score of the usability for the category 3, which requires students to move their bodies for the interaction, is the highest one because it features with spatial interaction. Students expressed much interest in the category 4, which utilizes users' other senses, however, the score of the usability is the lowest because the interaction is temporary and repetitive. Most installations are well designed in terms of control constraints, legibility, lower thresholds, participation encouragement, and open to the public, but pooly designed in terms of multiple access points, configurability, accurate movement, ambient media, and full-body interaction.

• 한국인터넷방송통신학회논문지
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• 제10권3호
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• pp.111-119
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• 2010

오늘날 무선 기술의 급속한 발전으로 인해 복수개의 액세스 인터페이스를 갖는 이동단말들이 나타나고 있다. 최근 WLAN이 근거리 통신을 위해 많은 가정과 기업에서 사용되고 있으며, WiMAX 또한 장거리 데이터 전달을 위한 무선 표준으로 부각되고 있다. 따라서 이기종 무선망간에 멀티미디어 데이터를 전달하기 위한 효율적인 접속 방안 연구가 필요하다. 본 논문에서는 WiMAX와 WLAN 인터페이스를 갖고 모바일 IP를 이용해 두 망사이를 이동할 수 있는 멀티홈드 노드의 시뮬레이션 모델과 환경을 개발하였다. 개발된 모델을 검증하기 위해 단방향/양방향 UDP 패킷, FTP 트래픽, SIP 프로토콜을 이용한 음성 전송 등과 같은 다양한 트래픽 환경하에서 여러가지 시뮬레이션 시나리오 즉, WiMAX와 WLAN 망간 이동, 그룹 이동성, MANET, 중첩 모바일 IP 등을 설계하고 구성하였으며, 시뮬레이션 결과를 분석함으로써 개발된 모델이 다양한 무선망 접속 시나리오에서의 이동성 연구에 효율적임을 보였다.