• 한국정보과학회논문지:정보통신
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• 제30권6호
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• pp.685-694
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• 2003

최근 이동성을 제공하는 시스템이 매우 빠른 속도로 보급되고 있는 추세이며 그 서비스 분야도 다양해져 무선 멀티미디어 서비스에 대한 요구가 커지고 있다. 멀티미디어 서비스는 큰 데이타 용량을 요구하며, 같은 정보를 여러 사용자들에게 보내야 하는 특징을 갖는다. 이동하는 사용자에게 이와 같은 특징을 갖는 멀티미디어 서비스를 효율적으로 제공하기 위해서는 이동성을 지원하는 멀티캐스트 기법이 필요하다. 본 논문에서는 Mobile IP 기반의 이동 네트워크 환경에서 멀티캐스트 서비스를 지원하는 기존 연구가 갖는 데이타 전송 경로의 비최적화, 빈번한 멀티캐스트 전송 트리의 재구성으로 인한 오버헤드, 서비스 단절의 문제를 해결하기 위해 이동 형태 기반의 가변 서비스 범위 멀티캐스트 기법을 제안한다. 이동 형태 기반의 가변 서비스 범위 멀티캐스트 기법은 서비스 범위를 호스트의 이동성에 따라 가변적으로 설정하고 자원 예약 기법을 사용하여 멀티캐스트 서비스를 지원한다. 다양한 실험을 통해 본 논문에서 제안된 멀티캐스트 기법을 성능 평가하였다.

• 한국멀티미디어학회논문지
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• 제15권12호
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• pp.1475-1484
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• 2012

Today many companies introduce new mobile office environments evolved from the recent rapid development in mobile device technologies. Most of the recent mobile office systems use a simple authentication scheme such as ID/Password. This method is easy to use, but it does not consider the user's context. Thus it cannot provide appropriate security service required by the user's proper contexts. Therefore, this paper proposes a context based authentication system which applies security level verification and uses fuzzy algorithm based on the importance of access authority control.

• 한국멀티미디어학회논문지
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• 제7권12호
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• pp.1754-1764
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• 2004

Lately mobile handheld devices such as Personal Digital Assistant (PDA) and cellular phones are getting more popular for personal web surfing. However, today most mobile handheld devices have relatively poor web browsing capability due to their low performance so their users have to suffer longer communication latency than those of desktop Personal Computers (PCs). In this paper, we propose an effective pre-refresh mechanism for embedded web browser of mobile handheld devices to reduce this problem. The proposed mechanism uses the idle time to pre-refresh the expired web objects in an embedded web browser's cache memory. It increases the utilization of Central Processing Unit (CPU) power and network bandwidth during the idle time and consequently reduces the client's latency and web browsing cost. An experiment was done using a simulator designed by us to evaluate the efficacy of the proposed mechanism. The experiment result demonstrates that it has a good performance to make web surfing faster.

• 한국멀티미디어학회논문지
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• 제19권4호
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• pp.780-788
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• 2016

Development of information and communication technologies has given a lot of changes in the business processing methods including the school and class managements. However, many business processing systems are still based on desktop computer. In particular, most of the class management system only supports desktop computers; hence school teachers have difficulty in using their class managements systems on mobile environment. In this paper, we proposed and developed a mobile classroom management system for teachers, which will easily handle information such as personal records of students, student counseling records, student life record and so on. The implementation of the application of mobile-based class management can be managed by many school elements including student register information, student evaluation records and transcripts, counseling report, and so on.

• Journal of Multimedia Information System
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• 제3권2호
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• pp.13-20
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• 2016

Biometric authentication for account-based mobile payment continues to gain attention because of improvements on sensors that can collect biometric information. We propose an enhanced method for mobile payment security based on biometric authentication. In this mobile payment system, the communication between the user and the relying party is based on public key infrastructure. This method secures both the key and the biometric template in the user side using fuzzy vault biometric cryptosystems, which is based on non-random chaff point generator. In this paper, we consider an important process for the common fuzzy vault system, that is, the feature extraction method. We evaluate various feature extraction methods to enhance the accurate performance of the system.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.953-960
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• 2018

In recently, eye blink recognition, and face recognition are very popular and promising techniques. In some cases, people can use the photos and face masks to hack mobile security systems, so we propose an eye blinking detection, which finds eyes through the proportion of human face. The proposed method detects the movements of eyeball and the number of eye blinking to improve face recognition for screen unlock on the mobile devices. Experimental results show that our method is efficient and robust for the screen unlock on the mobile devices.

• 한국멀티미디어학회논문지
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• 제12권12호
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• pp.1701-1709
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• 2009

The mobile terminal system plays a key role in medical industries which require in fast and accurate diagnosis from heterogeneous acquisition equipment. The demand for PACS (picture archiving and communication systems) has continued to increase in major hospitals and private clinics. Patient care depends on how fast the medical imaging system provides images and how accurately the images are interpreted by physicians. In this paper, we propose an efficient method to decipher the hundreds of images required by physicians to accurately diagnose patients. By exploring Motion- JPEG (M-JPEG), this paper has demonstrates the possibilities for efficient management of medical images with a newly designed image file format and improvement in imaging diagnoses through the replaying of moving pictures of a patient in a mobile environment.

• 한국멀티미디어학회논문지
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• 제22권10호
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• pp.1133-1141
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• 2019

Most of the previous studies for bark recognition have focused on the extraction of LBP-like statistical features. Deep learning approach was not well studied because of the difficulty of acquiring large volume of bark image dataset. To overcome the bark dataset problem, this study utilizes the MobileNet which was trained with the ImageNet dataset. This study proposes two approaches. One is to extract features by the pixel-wise convolution and classify the features with SVM. The other is to tune the weights of the MobileNet by flexibly freezing layers. The experimental results with two public bark datasets, BarkTex and Trunk12, show that the proposed methods are effective in bark recognition. Especially the results of the flexible tunning method outperform state-of-the-art methods. In addition, it can be applied to mobile devices because the MobileNet is compact compared to other deep learning models.

• 한국멀티미디어학회논문지
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• 제21권12호
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• pp.1526-1533
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• 2018

This study aims to provide implications for mobile foreign language vocabulary learning app by analyzing the effects of mobile vocabulary learning app based on character animation. For this purpose, we applied the learning application designed with character animation and text, and the application designed with text only to two groups of learners, and analyzed the effect. As a result, we found that application designed with character animation and text was useful in recognition frequency and duration concerning learning. Regarding learning outcomes, we found that it is useful not only in memory but also in learning interest and motivation. This study provides implications for learning method and design development of mobile-based foreign language vocabulary learning application which actively using recently.

• 한국멀티미디어학회논문지
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• 제13권5호
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• pp.792-801
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• 2010

본 논문에서는 모바일 플랫폼을 위한 범용적인 그래픽스 미들웨어로써, 모바일 장면그래프 라이브러리인 '모바일 OpenSceneGraph (모바일 OSG)'를 제안하고 그 개발 사례를 소개한다. 제안하는 모바일 그래픽스 미들웨어는 데스크탑 환경에서 그래픽스 미들웨어로 널리 쓰이고 있는 OpenSceneGraph를 모바일 환경에 적합하도록 재설계하였으며, 이를 통해 범용성, 확장성, 모바일 플랫폼 UI 지원, 호환성 등의 특성을 확보하였다. 복잡한 가상환경의 실시간 렌더링, 터치 UI 기반의 카메라 조작, 노드 전환을 통한 애니메이션 등과 같은 예시 응용프로그램을 통해 제안하는 모바일 장면 그래프 라이브러리의 효용성을 보이도록 한다.