• Journal of Korea Multimedia Society
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• v.19 no.8
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• pp.1498-1504
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• 2016

The progress of mobile computing technology is bringing a large amount of multimedia contents such as image. Thus, we need an image retrieval system which searches semantically relevant image. In this paper, we propose a semantic image annotation and retrieval in mobile environments. Previous mobile-based annotation approaches cannot fully express the semantics of image due to the limitation of current form (i.e., keyword tagging). Our approach allows mobile devices to annotate the image automatically using the context-aware information such as temporal and spatial data. In addition, since we annotate the image using RDF(Resource Description Framework) model, we are able to query SPARQL for semantic image retrieval. Our system implemented in android environment shows that it can more fully represent the semantics of image and retrieve the images semantically comparing with other image annotation systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4948-4967
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• 2017

On mobile devices, image sequences are widely used for multimedia applications such as computer vision, video enhancement, and augmented reality. However, the real-time processing of mobile devices is still a challenge because of constraints and demands for higher resolution images. Recently, heterogeneous computing methods that utilize both a central processing unit (CPU) and a graphics processing unit (GPU) have been researched to accelerate the image sequence processing. This paper deals with various optimizing techniques such as parallel processing by the CPU and GPU, distributed processing on the CPU, frame buffer object, and double buffering for parallel and/or distributed tasks. Using the optimizing techniques both individually and combined, several heterogeneous computing structures were implemented and their effectiveness were analyzed. The experimental results show that the heterogeneous computing facilitates executions up to 3.5 times faster than CPU-only processing.

• Journal of Information Processing Systems
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• v.18 no.3
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• pp.402-410
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• 2022

Digital data can be manipulated easily, so information related to the timestamp is important in establishing the reliability of the data. The time values for a certain file can be extracted following the analysis of the filesystem metadata or file internals, and the information can be utilized to organize a timeline for a digital investigation. Suppose the reversal of a timestamp is found on a mobile device during this process. In this case, a more detailed analysis is required due to the possibility of anti-forensic activity, but little previous research has investigated the handling and possible manipulation of timestamps on mobile devices. Therefore, in this study, we determine how time values for multimedia files are handled according to the operating system or filesystem on mobile devices. We also discuss five types of timestamps-file created (C), last modified (M), last accessed (A), digitalized (Di), and filename (FN) of multimedia files, and experimented with their operational features across multiple devices such as smartphones and cameras.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05d
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• pp.1023-1027
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• 2002

인터넷 사용자 수가 급증하고 컴퓨터의 소형화와 고성능화로 인하여 이동성에 대한 사용자의 요구가 점점 늘어나고 있다. 이 문제를 해결하기 위해 IETF에서는 Mobile IP를 제안하여, 이동으로 인한 IP의 변경 없이도 인터넷에 연결하여 사용할 수 있다. 본 논문에서는 이러한 Mobile IP의 기본 동작 절차인 에이전트 발견, 등록, 데이터 그램 전송 중 등록과 데이터 그램 절차를 변경하여 추가적인 하드웨어 없이도 소프트웨어적으로 Mobile IP를 지원할 수 있는 방법을 제시한다.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.277-280
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• 2001

Due to the explosive popularization of the Internet, it has been researched for many mobile terminals how to receive various multimedia information. Especially, it has been considered that a mobile terminal is serviced with multimedia information through a inherent IP address. In this paper we have proposed the Handover Signaling Method and analyzed the Handover delay time of this proposed method in wireless section. This proposed method is appropriate to Broadband systems with Mobile IP. We have simulated Handover delay time with respect to the distance between a terminal and base stations

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.843-846
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• 2004

최근 차세대 이동통신서비스로 부각되고 있는 위치기반서비스 응용의 핵심기술로 Mobile GIS 서비스에 대한 관심이 증가하고 있으며, 처리능력, 저장공간, 디스플레이, 데이터통신 환경에서 제한적인 환경을 가진 이동 컴퓨팅 환경에서 지리정보를 효율적으로 처리하기 위한 Mobile GIS 서비스 모델에 관한 연구 및 개발이 이루어지고 있다. 본 논문에서는 이러한 이동 컴퓨팅 환경의 제한된 환경에서 효율적인 Mobile GIS 서비스를 제공하기 위한 방법으로 지리정보 좌표의 바이너리화와 Base-Offset 구조를 사용하는 초경량 수치지도 모델을 제안한다.

• Journal of the Korea Society of Computer and Information
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• v.14 no.7
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• pp.123-132
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• 2009

The perforrnance and portability of mobile applications can be greatly increased by adopting proxy modiles which exists between the conventional system and the device. When mobile devices collaborate with the conventional computers, there are problems to address: a battery life problem, limited input and output methods, and intermittent wireless connection. Those issues are magnified in the multimedia collaboration environment since it works in a real-time condition and the size of the message in the system is big in many cases. Additionally, because multimedia collaboration system softwares are too heavy and complex for mobile devices, it is veη hard to integrate them with conventional systems. In this paper, we describe our design and its implementation of a novel approach to map events (i.e. messages) using a proxy for mobile applications. We adopt a proxy to provide a content adaptation (i.e. transcoding) where the message contents are customized. Also, we design a mobile version publish/subscribe system to provide communication service for mobile device in loosely coupled and flexible manner. We present our empirical results which show that our design can be efficiently implemented and integrated with a conventional multimedia collaboration system.

• Proceedings of the Korea Society of Design Studies Conference
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• 2003.05a
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• pp.264-265
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• 2003

• Journal of Korea Multimedia Society
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• v.2 no.1
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• pp.59-68
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• 1999

Multimedia applications have an ability to transmit a lot of data in real time. In mobile circumstances the replay of continuous multimedia data in real time causes frequent replay breaks and poor service quality because of low transmission speed and new transmission path settings in hand-off. To avoid these unfavorable side effects, we need a new mechanism which can transmit data efficiently between base station and mobile hosts, to control the buffers of mobile hosts, and to switch to a new transmission path rapidly in hand-off. The study is to propose how to give good service to mobile hosts during hand-off and the mechanism which can increase the number of mobile hosts in the cell unit.

• Journal of Information Technology Services
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• v.12 no.2
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• pp.243-256
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• 2013

Recently, due to the proliferation of smartphones, users of mobile multimedia services which are based on wireless internet without constraint of the time and places are significantly increased. In this study, considering the characteristics of mobile multimedia and the user behavior, we analyse the factors which have an effect on the behavioral intention to use the mobile multimedia services. For this purpose, we use the model which is based on Technology Accepted Model (TAM) and add two constructs; the perceived enjoyment and the perceived risk. A survey data for 280 students at the K cyber university is used for statistical analysis As a result, the perceived ease of use affects the perceived usefulness and the perceived enjoyment, and the perceived ease of use. And the perceived usefulness and perceived enjoyment affect continuous intention to use. On the other hand, the hypothesis which the perceived risk would affect adversely the continuous intention to use is rejected. Through this study, we expect to provide the useful implications for the mobile multimedia services and contribute to the development of strategy for them.