• Journal of Internet Computing and Services
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• v.25 no.4
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• pp.109-119
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• 2024

This study aims to contribute to the initial research on on-device AI in an environment where generative AI-based services on mobile and other on-device platforms are increasing. To derive success strategies for generative AI-based chatbot services in a mobile environment, over 200,000 actual user experience review data collected from the Google Play Store were analyzed using the LDA topic modeling technique. Interpreting the derived topics based on the Information System Success Model (ISSM), the topics such as tutoring, limitation of response, and hallucination and outdated informaiton were linked to information quality; multimodal service, quality of response, and issues of device interoperability were linked to system quality; inter-device compatibility, utility of the service, quality of premium services, and challenges in account were linked to service quality; and finally, creative collaboration was linked to net benefits. Humanization of generative AI emerged as a new experience factor not explained by the existing model. By explaining specific positive and negative experience dimensions from the user's perspective based on theory, this study suggests directions for future related research and provides strategic insights for companies to improve and supplement their services for successful business operations.

• Journal of Korean Society of Transportation
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• v.28 no.3
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• pp.61-74
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• 2010

ITS (Intelligent transportation systems) collects real-time traffic data, and accumulates vest historical data. But tremendous historical data has not been managed and employed efficiently. With the introduction of data management systems like ADMS (Archived Data Management System), the potentiality of huge historical data dramatically surfs up. However, traffic data in any data management system includes missing values in nature, and one of major obstacles in applying these data has been the missing data because it makes an entire dataset useless every so often. For these reasons, imputation techniques take a key role in data management systems. To address these limitations, this paper presents a promising imputation technique which could be mounted in data management systems and robustly generates the estimations for missing values included in historical data. The developed model, based on NPR (Non-Parametric Regression) approach, employs various traffic data patterns in historical data and is designated for practical requirements such as the minimization of parameters, computational speed, the imputation of various types of missing data, and multiple imputation. The model was tested under the conditions of various missing data types. The results showed that the model outperforms reported existing approaches in the side of prediction accuracy, and meets the computational speed required to be mounted in traffic data management systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.5
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• pp.473-482
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• 2015

Recent development in science and technology has enabled vehicles to be equipped with advanced autonomous functions. ADAS (Advanced Driver Assistance Systems) are examples of such advanced autonomous systems added. Advanced systems have several operational modes and it has been observed that drivers could be unaware of the mode they are in during vehicle operation, which can be a contributing factor of traffic accidents. In this study, possible mode confusions in a simulated environment when vehicles are equipped with an adaptive cruise control system were investigated. The mental model of the system was designed and verified using the formal analysis method. Then, the user interface was designed on the basis of those of the current cruise control systems. A set of human-in-loop experiments was conducted to observe possible mode confusions and redesign the user interface to reduce them. In conclusion, the clarity and transparency of the user interface was proved to be as important as the correctness and compactness of the mental model when reducing mode confusions.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.340-340
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• 2020

본 연구는 산지-도심-해안으로 연결된 해안도시의 지역적인 특성으로 인해 해일과 같은 조위 상승 원인이 침수 및 홍수 위험을 증가시키는 복합재난에 대응하기 위하여 실시간 침수 위험정보 확인 및 대응, 대시민 상황전파 등이 가능하도록 IoT 융합 침수 대응시스템을 개발하는 것이다. 또한, 침수 및 홍수방어벽 등의 구조적대책을 검토하여 실시간 IoT 융합 침수 대응시스템과 연계운영함으로써 해안도시의 시설 및 재산을 보호하고 시민의 안전을 확보하는데 기여할 수 있는 실증연구를 수행하는 것을 목표로 한다. 침수 대응을 위한 구조적 대책은 양산형 IoT 침수 및 하천수위 감지 장비, 센서 연동 침수 및 홍수방어벽, 복합재난알림 디스플레이 등의 개발이며, 비구조적 대책은 강우-하천수위-조위 실측자료기반의 머신러닝 침수위험 분석 모듈 개발, 수치모의에 의한 예상 침수심 및 침수위험지도 작성, 재난상황 전파 알림서비스 등이 있으며 개발된 시제품과 기술을 테스트베드에 적용하고 부산광역시에서 운영하는 재난상황관리시스템인 스마트빅보드(SBB, Smart Big Board)에 연계 및 탑재함으로써 향상된 침수대응 및 대시민 서비스가 가능한 시스템을 구축 및 실증하고자 한다. 센서, 통신, 자료연계 및 분석에 대한 IoT 융합 기술을 침수 대응 기술개발에 적극 활용하여 실측자료와 수치모의 분석 결과가 연계된 침수위험정보를 생산하고 실시간 대응이 가능한 효율적이고 실질적으로 피해를 저감 할 수 있는 기술을 개발하고 적용성을 입증한다면 국내외 해안도시에 확대 보급이 가능해져 침수 피해로부터 효과적으로 국민의 재산과 생명 보호할 수 있다. 또한, IoT 기술을 연계한 재난 모니터링 시스템의 확산으로 복합재난 대응 연구에 기여할 수 있고 상대적으로 실측자료 수집, 연구에 소외되어 온 소하천 등에도 적용이 가능하여 재난으로 인한 사회적 비용을 경감시킬 수 있을 것으로 기대된다.

• The Journal of Korean Association of Computer Education
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• v.16 no.1
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• pp.97-110
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• 2013

The purpose of this study is to analyze the needs of teachers as main users to make suggestions for active use of educational information sharing system. The study sets three research tasks about the problems of the current system, improvements, and desired content from the perspective of teachers. To collect specific opinions, we conducted an open questionnaire survey and made a qualitative analysis using the NVivo 10 program. The present system has such problems as functional issues, lack of data reliability, systemic problems for sharing and use. We suggest that in order to enhance Web site services, authoring tools for editing contents and new search engines with customized search function need to be provided. In addition, the open market service system has to be established, so that teachers can actively create, share, and distribute to meet the various needs of teachers. Finally, to promote free access to the system, copyright issues need to be resolved to prevent the potential digital piracy.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.11-19
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• 2004

A software-controlled unregulated bus system in which the main bus is directly connected to a battery and the duty-ratio for PWM switch is controlled by the on-board satellite software, is usually used for LEO satellites. This paper proposes a new power-stage circuit that can be available for modularization of a power regulator which is used at the software-controlled unregulated bus system satellite. And we analyze the proposed power-stage operation according to its operating modes and verify it by performing software simulation and hardware experiment using prototype. We construct a parallel-module converter which is composed of the proposed power-stage and perform experiment to verify modular characteristics of the proposed power-stage. Finally, we verify the usefulness of the proposed power-stage by comparing above results with those of a parallel-module converter made of conventional power-stage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.99-106
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• 2011

The emerging of ubiquitous computing and healthcare technologies provides us a strong platform to build sustainable healthcare applications especially those that require real-time information related to personal healthcare regardless of place. We realize that system stability, reliability and data protection are also important requirements for u-healthcare services. Therefore, in this paper, we designed a u-healthcare system which can be attached to the patient's body to measure vital signals, enhanced with USN secure sensor module. Our proposed u-healthcare system is using wireless sensor modules embedded with NLM-128 algorithm. In addition, PS-LFSR technique is applied to the NLM-128 algorithm to enable faster and more efficient computation. We included some performance statistical results in term of CPU cycles spent on NLM-128 algorithm with and without the PS-LFSR optimization for performance evaluation.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.2
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• pp.84-91
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• 2003

KOMPSAT series use software-controlled unregulated bus system in which the main bus is directly connected to a battery and the duty-ratio for PWM switch is controlled by the on-board satellite software. This paper proposes a new power-stage circuit that can be available for modularization of the power regulator which is used at the software-controlled unregulated bus system satellite. And we analyze the proposed power-stage operation according to its operating modes and verify it by performing software simulation and hardware experiment using prototype. We construct a parallel-module converter which is composed of proposed power-stages and perform experiment to verify modular characteristics of the proposed power-stage. Finally, we verify the usefulness of the proposed power-stage by comparing above results with those of a parallel-module converter made of conventional power-stages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.415-422
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• 2004

DSRC provides high speed radio link between Road Side Equipment and On-Board Equipment within the narrow communication area. In this paper, a 5.8 GHz down-conversion mixer for DSRC communication system was designed and fabricated using 0.8 ${\mu}{\textrm}{m}$ SiGe HBT process technology and RF/LO matching circuits, RF/LO input balun circuits, and If output balun circuit were all integrated on chip. The chip size of fabricated mixer was 1.9 mm${\times}$1.3 mm and the measured performance was 7.5 ㏈ conversion gain, －2.5 ㏈m input IP3, 46 ㏈ LO to RF isolation, 56 ㏈ LO to IF isolation, current consumption of 21 mA for 3.0 V supply voltage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.350-357
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• 2005

DSRC provides high speed radio link between Road Side Equipment and On-Board Equipment within the narrow communication area. In this paper, a 5.8 GHz up-conversion mixer for DSRC communication system was designed and fabricated using 0.8 m SiGe HBT process technology and IF/LO/RF matching circuits, IF/LO input balun circuits, and RP output balun circuit were all integrated on chip. The chip size of fabricated mixer was $2.7mm\times1.6mm$ and the measured performance was 3.5 dB conversion gain, -12.5 dBm output IP3, 42 dB LO to If isolation, 38 dB LO to RF isolation, current consumption of 29 mA for 3.0 V supply voltage.