• Journal of Aerospace System Engineering
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• v.9 no.3
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• pp.8-11
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• 2015

Since the late 1990's, FAA, NASA and the aerospace industry have worked together to develop the sharing system of the composite material qualification databases which were obtained through the standardized fabrication and testing procedures. The result was what is now known as the AGATE(Advanced General Aviation Transport Experiments) or NCAMP(National Center for Advanced Materials Performance) methodology, a more cost-effective concept that shifts the major responsibility for qualification and testing from the aircraft manufacturer to the material supplier. The properties of composite materials are largely dependent on the testing as well as the raw material properties and the manufacturing process including the process control parameters. Thus it is important in the composite material qualification to comply with the standardized testing procedures. In this paper, I will describe the standardized witness methodologies of certification engineers to reduce the effect of testing variability within the qualification data.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.2
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• pp.50-55
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• 2008

In this paper, multi-band internal antenna which can adjust both resonant frequency and input impedance of antenna as using lumped inductor between shoring plate and ground plane is proposed. The structure of proposed antenna consists of PIFA (Planar Inverted F Antenna) structure and half-wavelength loaded line structure and has two shorting plates and one feeding plate. One shorting plate is shared. The operating frequency bands of designed antenna are GSM, GPS in the PIFA structure and DCS, US-PCS, W-CDMA in half-wave loaded line structure as varying the inductor value in 2.2nH, 3.3nH, and 4.7nH. As varying the inductor value in the shared shorting plate, input impedance of antenna is varied. To minimize the gain variation of antenna as adding lumped element, the inductor value is restricted at maximum of 6.8nH. The maximum gain of proposed antenna is measured as -1.60dBi in the GSM band, -1.16dBi in the GPS band, and 1.41dBi in the DCS/US-PCS/W-CDMA band.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.1
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• pp.159-181
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• 2022

Today, people in cities use differentthe types of transportation that rangepeople use in cities have diversified from existing public transportation, cars, taxis to shared bicycles and shared electric kickboards. In addition, with the development of mobile platform -based search, order, and payment services, and transportation services have also begun to change into platform-based integrated services. In particular, MaaS, which has emerged as an integrated mobile service and, is currently being studied and operated worldwide., However, MaaS but remains at the level of the integrated provision of the existing public transportation. As a result of Specifically, the results of a literature review on this issue reveal that, the First/Last Mile problem raised at the current level of MaaS is likely to be solved by establishing an improved policy incorporating new means of transportation. Therefore, this study aims to establish a First/Last Mile transportation supply plan for successful MaaS provision. This establishment is realized by analyzing the traffic patterns of urban populations usingbased on the ABATA system,, an activity-based traffic analysis model withevaluated as having higher analysis power on people's traffic.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.1
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• pp.75-85
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• 2014

Existing car-sharing systems have difficulty meeting the demands of one-way trips and connecting to other sharing systems. Therefore, in this study, a multi-mobility sharing service management system that was able to meet the demands of the one-way and round-way trips and shared diverse transportation modes such as cars (electric car/gasoline car), electric motorcycles and bicycles was developed, and a field study was conducted in Kashiwa-no-ha, Kashiwa City and Nagareyama City, Chiba Prefecture, Japan. As a result of the field test, it was confirmed that this system supplied the one-way demands for 54.9% of total car trips and 43.9% of the user used multiple transportation modes by the common interface. In addition, this system contributed to reduce carbon dioxide emissions by sharing vehicles and using eco-friendly vehicles. The developed sharing system is expected to improve mobility by meeting more various types of traffic demand than existing car sharing systems.

• Journal of the Korean Geographical Society
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• v.48 no.1
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• pp.72-86
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• 2013

Industrial agglomeration is an old theme in economic geography and many studies have been devoted to this topic. But only few have empirically looked at the time trend of industrial agglomeration. This study measured agglomeration of U.S. industries over last 29 years and measurement results indicated that industrial clustering has occurred during the study period in all study industries without a common time trend shared amongst the study industries. The agglomeration levels then were plugged in to investigate causalities, i.e. causal relations, around industrial agglomeration. Three variables were selected to see causal relations with agglomeration levels based on literatures, and our focus was given to the causality between transport network and agglomeration. Causal relation from transport to agglomeration was found in various industries and this supports the argument that the development of transportation influences industrial agglomeration. At the same time inverse and bi-directional causalities were also revealed implying more complex relationship between these two.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.4
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• pp.95-104
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• 2013

As global warming and depletion of fossil fuel are considered as urgent problems, the development of electric vehicle (EV) is getting more attention by automobile industry. However, the wide adoption of EVs is not coming yet, because of many issues such as long recharging time and high cost of batteries etc. As an alternative solution to the conventional battery charging EV, the idea of battery exchanging EV is introduced. To realize the battery exchanging business model, one should solve the issues of ownership and reliability of battery. To address such issues, the concept of battery sharing should be considered together with good traceability system. In this study, we studied RFID code structure to provide better visibility and traceability for shared EV batteries. The proposed RFID code and code generation system is based on GRAI-96 of EPCglobal and included factors such as chemical, physical, and manufacturing features. The designed code can be also used as the ID of each battery.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.2
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• pp.70-80
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• 2008

CSMA(Carrier Sense Multiple Access) is a media access control protocol when nodes use a shared channel. To reduce the probability of collision and increase the performance, the station lust checks the state of the channel. In this paper, we study the performance improvement method based on p-persistent strategy. The p-persistent method reduces the chance of collision and improves the efficiency. However, a probability p and the number of station affect the performance. This paper proposes a dynamic CSMA multiple access based on the network status. If the possibility of collision is low, the station increases the probability p to improve the performance. In the opposite case, the station decreases the probability p. Our simulation results show that the proposed scheme outperforms any methods of CSMA multiple access according to the current persistent strategy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.837-840
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• 2003

Recently the multimedia streaming traffic such as digital audio and video in the Internet has increased tremendously. Unlike TCP, the UDP protocol, which has been used to transmit streaming traffic through the Internet, does not apply any congestion control mechanism to regulate the data flow through the shared network. If this trend is let go unchecked, these traffic will effect the performance of TCP, which is used to transport data traffic, and may lead to congestion collapse of the Internet. To avoid any adverse effort on the current Internet functionality, A study on a new protocol of modification or addition of some functionality to existing transport protocol for transmitting streaming traffic in the Internet is needed. TCP-frienly congestion control mechanism is classified with window-based congestion control scheme and rate-based congestion control scheme. In this paper, we propose an algorithm for improving the transmitting rate on a hybrid TCP-friendly congestion control scheme combined with widow-based and rate-based congestion control for multimedia streaming in the internet.

• The KIPS Transactions:PartA
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• v.9A no.1
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• pp.29-36
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• 2002

For the efficient collaboration awareness, the CSCW (Computer-Supported Cooperative Work) systems provide functions such as telepointing, snap-shot, and document/project tracking. Among these, telepointing allows an event occurrence on the shared window of a local computing system to be presented in remote computing systems. Although telepointing has been mentioned in the literature, few research papers deal with the functional requirements and protocols for telepointing. This parer describes the functional requirements and payload format for RTP (Real-Time Transport Protocol)-based telepointing. In order to evaluate the performance of the proposed RTP-barred telepointing, we have implemented a whiteboard and compared it with that of the Microsoft Netmeeting. The evaluation results show that the proposed telepointing performs better in terms of CPU usage and the amount of network traffic.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.311-318
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• 2001

In recent years, users\` demands for multimedia service are increasing because of a diffusion of internet. Server systems, however, offer inefficient multimedia data service to users. Multimedia applications often transfer the same data between shared devices at very high rates, and therefore require an efficient I/O subsystem. Data copying and context switching have long been identified as sources of I/O inefficiency. Therefore we propose the new Multimedia Stream System Call (MSSC) mechanism, which is inserted into a Linux kernel: The MSSC mechanism operates in kernel domain with RTP (Real-time Transport Protocol). We present measurements indicating that use of our techniques resulted in a 12.5%∼14% gain in throughput as compared with a conventional Linux system.