• The KIPS Transactions:PartC
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• v.10C no.7
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• pp.943-954
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• 2003

The mobile telecommunication system has been growing exponentially after 1990s due to the high population in a city and the growth of mobile user. In this time, the current mobile system mainly concentrates on the voice communication. However, in the next generation, mobile users want to get very diverse services via mobile terminal such as the Internet access, web access, multimedia communication, and etc. For this reason, the next generation system, such as the UMTS (Universal Mobile Telecommunication Services) system, has to support the packet data service and it will play the major role in the system. By the way, since the Web service is based on TCP, most of the Internet traffic TCP traffic. Therefore, efficient transmission of TCP traffic will take very important role in the performance of packet data service. There are many researches about improving TCP performance over wireless network. In those schemes, the UMTS system adapts the link layer retransmission scheme. However, there are rarely studies about the exact performance of the link layer retransmission scheme in the face of dynamic changes of wireless environment over the UMTS system. The dynamic changes of wireless environment, such as wireless bandwidth, can degrade TCP performance directly. So, in this paper, we simulate and analyze the TCP performance in the UMTS system with dynamic wireless environments. Then, we propose a simple scheme for minimizing TCP performance degradation. As a result of simulation, we can find that when wireless environment is changed dynamically, the probability of TCP timeout is increased, and the TCP performance is degraded very much. In this situation, the proposed simple scheme shows good performance. It saves wireless resources and reduces the degradation of TCP performance without large overhead of the base station.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.5
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• pp.1-11
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• 2008

Wireless Sensor Networks is applied to improvement of life convenience or service like U-City as well as environment pollution, tunnel and structural health monitoring, storm, and earthquake diagnostic system. To increase the usability of sensor data and applicability, mobile devices and their facilities allow the applications of sensor networks to give mobile users and actuators the results of event detection at anytime and anywhere. In this paper, we present MUSNEMO(Multi-sensor centric Ubiquitous Smart sensor NEtwork using Mobile devices) developed system for providing more efficient and valuable information services with a variety of mobile devices and network camera integrated to WSN. Our system is performed based on IEEE 802.15.4 protocol stack. To validate system usability, we built sensor network environments where were equipped with five application sensors such magnetic, photodiode, microphone, motion and vibration. We also built and tested proposed MUSNEMO to provide a novel model for event detection systems with mobile framework.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.4
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• pp.1892-1903
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• 2016

Mobile social network is becoming more and more popular with respect to the development and popularity of mobile devices and interpersonal sociality. As the amount of social data increases in a great deal and cloud computing techniques become developed, the architecture of mobile social network is evolved into cloud-based that mobile clients send data to the cloud and make data accessible from clients. The data in the cloud should be stored in a secure fashion to protect user privacy and restrict data sharing defined by users. Ciphertext-policy attribute-based encryption (CP-ABE) is currently considered to be a promising security solution for cloud-based mobile social network to encrypt the sensitive data. However, its ciphertext size and decryption time grow linearly with the attribute numbers in the access structure. In order to reduce the computing overhead held by the mobile devices, in this paper we propose a new Outsourcing decryption and Match-then-decrypt CP-ABE algorithm (OM-CP-ABE) which firstly outsources the computation-intensive bilinear pairing operations to a proxy, and secondly performs the decryption test on the attributes set matching access policy in ciphertexts. The experimental performance assessments show the security strength and efficiency of the proposed solution in terms of computation, communication, and storage. Also, our construction is proven to be replayable choosen-ciphertext attacks (RCCA) secure based on the decisional bilinear Diffie-Hellman (DBDH) assumption in the standard model.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.691-693
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• 2003

The development of an open LBS platform makes it easy to use of the location information between telecommunication companies which have different platforms and to develop various LBS solutions using position information. This paper proposes a mobile webservice solution providing public transportation services to the mobile subscribers.

• Journal of Internet Computing and Services
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• v.21 no.2
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• pp.57-64
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• 2020

The widespread use of smartphones with a variety of features has enabled mobile Internet-based services. One of these is online-to-offline (O2O) based services that connects online users with offline stores to add value. Applying this O2O strategy to local information retrieval induces online users to be linked to offline regions, thereby enabling the exchange of local-based information and helps create new value. This paper proposes and illustrates the implementation of O2O-based a local information providing service that utilizes photos of the local attraction. Also, we propose a fake-free ranking method to provide reliable local information to users and suggest its application of the service.

• Journal of the Korean Geographical Society
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• v.46 no.6
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• pp.738-750
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• 2011

Partly due to the climate changes, flooding occurs more often than before. Particularly high urbanization causes more damages by flooding with unexpected downpours. Recent mobile telecommunication technology can help to reduce the damage by a natural disaster with quick alarming process. This research aimed to implement a flood warning GIS service system based on open source software and mobile hybrid application program with LBS. The developed system utilized location information of mobile clients for smart phone users to get alerted to flooding immediately. This service system would be very useful in urban areas to reduce the flood damages.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1551-1554
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• 2002

홈 오토메이션은 댁내의 가전제품을 네트워크로 연결시켜 단말기를 이용하여 어디서든지 편리하게 가전제품을 제어하는 기술이다. 본 논문은 고정된 공간에서 유선 인터넷 망에 접속하던 PC환경에서 벗어나 휴대성과 이동성의 특징을 가지는 이동 단말기를 이용하여 이동 중에도 무선 인터넷에 접속하여 실시간으로 댁내의 가전제품을 제어할 수 있으며, 또한 비용적인 측면과 효율적인 측면을 고려하여 PC의 프린트 포트를 통하여 가정내의 가전제품을 제어하는 홈 오토메이션 서비스 기능의 설계 및 구현에 초점을 맞추고 있다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.333-336
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• 1996

This paper is an exploratory study aimed at finding factors that influence the penetration of cellular mobile telecommunications which have seen rapid development since 1980s. The paper tries to find economy and policy variables to influence the penetration by means of the multiple regression analysis. This paper shows a model that explain the penetration ratio of cellular service. The model is based on data from 39 upper middle income and 39 high income countries. The result shows that GDP per capita and the service period of the cellular mobile telecommunication have influenced on the penetration ratio positively, and the tariff of the service negatively. But, it is the open area to study the impact of the telecommunications policy changes on penetration, and to set a model which could explain the nation-specific characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.133-144
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• 2004

This research aimed to do an empirical study, by comparing the relationships of service quality, customer satisfaction and customer loyalty in mobile telecommunications between Korea and China which possess different growth phases. For this purpose, six factors in service quality, customer satisfaction and customer loyalty have been under a regression analysis to verify the causal relationship. The key findings of this study are as follows. Both Korea and China showed the causal relationship between customer satisfaction and customer loyalty; the service support which applies as the core services, have been found to be the most important factors in customer satisfaction and customer loyalty. And this study has been able to establish strategic views on reinforcing customer bases in mobile telecommunication service markets in both countries.

• Journal of Internet Computing and Services
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• v.18 no.2
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• pp.113-121
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• 2017

As the industrial structure of the mobile telecommunications market is transforming into the ICT ecosystem centered on smartphones, the regulatory system conforming to the new ICT environment has become the main subject of discussion in key developed countries. The EU segmented the mobile phone service into wholesale and retail. Simultaneously, the EU appraised mobile telecommunication carriers' market domination in segmented markets to continuously improve the scheme to promote competition in the telecommunications market. In Korea, also, there is discussion about adopting the EU scheme to segment the mobile phone market definition more finely and taking measures to appraise the market domination in accordance with object appraisal criteria. As such, this study analyzes whether the current criteria for appraising the wholesale termination rate market domination under the ICT's domestic mobile telecommunication ecosystem is adequate and presents the rational improvement measures reflecting the theoretically suggested evaluation factors.