• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.197-200
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• 2002

The current Inn technique is many problems that is permission of radio station using RF Wireless Modem, that is influence of geographic obstacle using radio wave, that is frequency interference, that is finiteness of frequency resources. In this paper, we are solved many elements, IM replaces RF Wireless Modem, we suggest transmission technique of correction message using mobile phone, we researched Interface Module development which is linkage of DGPS receiver and mobile phone. IM can transmit correction message passing RS-232 port and modem communication control. IM of base station is initialized RS-232 port and modem to move station for correction message transmission, IM waited response mode. IM of move station is initialized RS-232 port and modem, IM requests hand shaking to base station, completed connection establishment. Users are worked Differential surveying using receiving correction message between mobile phones.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.147-154
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• 2012

I made an analysis on the case of Kakao Talk, which is Korean top mobile instant messaging service, to find the growth potential of Korean Social Network Service in the global market. First, I found that unlike the PC messenger services, Kakao Talk is not only unlimited in mobile IM service provider but also has evolving into a social network service firm. Second, attempts with a variety of social services such as photo-based Kakao Story and Marketing Platform for Mobile Game, Kakao Talk successfully landed as a SNS company. Third, with 'Plus Friends' Service, soon-to-be launched Avatar and App Market Service, Kakao Talk is evolving into social media and social platforms. The big success of Kakao Talk in Korean market is expanding and reproducing into Japanese and Southeast Asian markets through the 'Line' serviced by NHN. Line is applying the proven success stories of Kakao Talk to the Japanese and Southeast Asian markets. It means that Kakao and Line, both are mobile IM services, have raised the possibility of success in the global SNS market although online web-based SNS Cyworld has failed in the global market.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.238-240
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• 2002

MoIM(Mobile Message Internet Middleware)-Message 시스템은 이러한 메시지 시스템의 요구사항을 만족하는 메시지 시스템으로서 Point-to-Point 및 Publish-Subscribe 방식을 제공하는 시스템이다. 이 시스템의 통신 방법은 RMI(Remote Method Invocation)을 사용한다. 최근의 인터넷 사용자 수가 급증함에 따라서 메시징 서버를 사용하는 동시 클라이언트의 수도 수천에서 수만으로 이를 것으로 예상되어 대규모의 동시 사용자를 지원하는 연결 기술이 필요하다. 이 논문에서는 이러만 대용량의 데이터를 RMI 통신방법을 사용하여 설계 및 구현한 방법을 기술한다.

• Information Systems Review
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• v.15 no.2
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• pp.91-110
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• 2013

Due to the intense competition and low switching cost, to find out which factors will significantly impact on user's continuance intention is very important for mobile instant messaging (IM) practitioners. In this study, we adopted network externalities and perceived service quality as independent variables based on the definition of mobile IM service. Network externalities also include direct externalities (referent network size) and indirect externalities (perceived complementarity). The result of this study shows that referent network size has a critical influence on perceived usefulness and perceived complementarity has a critical influence on perceived enjoyment; perceived service quality, as we expected, has significantly impact on not only customer's satisfaction but also perceived usefulness and perceived enjoyment. Meanwhile, both perceived usefulness and perceived enjoyment have directly critical influences on customer's continuance intention.

• 한국ITS학회:학술대회논문집
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• 2003.11a
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• pp.100-104
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• 2003

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.5
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• pp.182-189
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• 2002

This paper presents a framework of hybrid dynamic control systems for the motion control of wheeled mobile robot systems with nonholonomic constraints. The hybrid control system has the 3-layered hierarchical structure: digital automata for the higher process, mobile robot system for the lower process, and the interface as the interaction process between the continuous dynamics and the discrete dynamics. In the hybrid control architecture of mobile robot, the continuous dynamics of mobile robots are modeled by the switched systems. The abstract model and digital automata for the motion control are developed. In high level, the discrete states are defined by using the sensor-based search windows and the reference motions of a mobile robot in low level are specified in the abstracted motions. The mobile robots can perform both the motion planning and autonomous maneuvering with obstacle avoidance in indoor navigation problem. Simulation and experimental results show that hybrid system approach is an effective method for the autonomous maneuvering in indoor environments

• Healthcare Informatics Research
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• v.24 no.4
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• pp.381-386
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• 2018

Objectives: This study aimed to describe the process of utilizing a mobile application for ecological momentary assessment (EMA) to collect data on stress and mood in daily life setting. Methods: A mobile application for the Android operating system was developed and installed with a set of questions regarding momentary mood and stress into a smartphone of a participant. The application sets alarms at semi-random intervals in 60-minute blocks, four times a day for 7 days. After obtaining all momentary affect and stress, the questions to assess the usability of the mobile EMA application were also administered. Results: The data were collected from 97 police officers working in Gyeonggi Province of South Korea. The mean completion rate was 60.0% ranging from 3.5% to 100%. The means of positive and negative affect were 18.34 of 28 and 19.09 of 63. The mean stress was 17.92 of 40. Participants responded that the mobile application correctly measured their affect ($4.34{\pm}0.83$) and stress ($4.48{\pm}0.62$) of 5-point Likert scale. Conclusions: Our study investigated the process of utilizing a mobile application to assess momentary affect and stress at repeated times. We found challenges regarding adherence to the research protocol, such as completion and delay of answering after alarm notification. Despite this inherent issue of adherence to the research protocol, the EMA still has advantages of reducing recall bias and assessing the actual moment of interest at multiple time points that improves ecological validity.

• Magazine of the Korean Society of Hazard Mitigation
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• v.7 no.4
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• pp.128-136
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• 2007

• 한국ITS학회:학술대회논문집
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• 2004.11a
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• pp.115-119
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• 2004

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.921-927
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• 2006

The current DGPS technique is many problems that is permission of radio station using RF Wireless Modem, that is influence of geographic obstacle using radio wave, that is frequency interference, that is finiteness of frequency resources. In this paper, we are solved many elements, IM(Interface Module) replaces RF Wireless Modem, we suggest transmission technique of correction message using mobile phone, we researched Interface Module development which is linkage of DGPS receiver and mobile phone. IM can transmit correction message passing RS-232 port and modem communication control. IM of base station is initialized RS-232 port and modem to move station for correction message transmission, IM waited response mode. IM of move station is initialized RS-232 port and modem, IM requests hand shaking to base station, completed connection establishment. Users are worked Differential surveying using receiving correction message between mobile phones.