• Industrial Engineering and Management Systems
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• v.13 no.4
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• pp.421-431
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• 2014

The market basket data in the form of a binary user-item matrix or a binary item-user matrix can be modelled as a binary classification problem. The binary logistic regression approach tackles the binary classification problem, where principal components are predictor variables. If users or items are sparse in the training data, the binary classification problem can be considered as a cold-start problem. The binary logistic regression approach may not function appropriately if the principal components are inefficient for the cold-start problem. Assuming that the market basket data can also be considered as a special regression problem whose response is either 0 or 1, we propose three supervised learning approaches: random forest regression, random forest classification, and elastic net to tackle the cold-start problem, comparing the performance in a variety of experimental settings. The experimental results show that the proposed supervised learning approaches outperform the conventional approaches.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.9
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• pp.32-39
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• 2006

In this paper, an iterative subspace-based calibration algorithm for a CDMA-based antenna array in the presence of unknown gain and phase error is presented. The algorithm does not depend on the array geometry and does not require a prior knowledge of the Directions Of Arrival (DOA) of the signals. The method requires the code sequence of a reference user only. The proposed algorithm is based on the subspace method and root finding approach, and it provides estimates of the calibration vector, the DOA and the channel impulse response, by using the code sequence of a reference user. The performance of the proposed algorithm was investigated by means of computer simulations and was verified using field data measured through a custom-built W-CDMA test-bed. The data show that experimental results match well with the theoretical calibration algorithm. Also, teh study propose an efficient algorithm using the simulated annealing technique. This algorithm overcomes the requirement of initial guessing in the subspace-based approach.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.494-500
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• 2004

The purpose of this thesis is to know and understand the user requirements to provide with intelligent railway information service in response to the Ubiquitous environment. The railroad specially has a disadvantage of door-to-door service, however by using the information and communication techniques, we can provide the passengers who are using the intermodal transportation means with the realtime information, therefore we can overcome the above disadvantage. To deduce the passenger's needs for providing the future-type railway information service, we introduce the results of the questionnaire. In chapter 2, we studies on the concepts of intelligent railway information service, and in chapter 3, we investigate the cases of Japan and China, and in chapter 4, we study the passager's satisfaction by the questionnaire concerning the railway information service and suggest the needs for information offering.

• Journal of the Ergonomics Society of Korea
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• v.18 no.3
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• pp.105-125
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• 1999

As speech is the human being's most natural communication medium, using it gives many advantages. Currently, most user interfaces of a computer are using a mouse/keyboard type but the interface using speech recognition is expected to replace them or at least be used as a tool for supporting it. Despite the advantages, the speech recognition interface is not that popular because of technical difficulties such as recognition accuracy and slow response time to name a few. Nevertheless, it is important to optimize the human-computer system performance by improving the usability. This paper presents a set of guidelines for designing speech recognition interfaces and provides a method for evaluating the usability. A total of 113 guidelines are suggested to improve the usability of speech-recognition interfaces. The evaluation method consists of four major procedures: user interface evaluation; function evaluation; vocabulary estimation; and recognition speed/accuracy evaluation. Each procedure is described along with proper techniques for efficient evaluation.

• Journal of the Korea Society of Computer and Information
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• v.23 no.7
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• pp.39-47
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• 2018

This paper confirms the risk of using smartphone through the analysis of collected usage pattern and proposes the smartphone intervention system in risk situations. In order to check the risk of smartphone usage, we made information collecting application and collected smartphone usage pattern from 11 experiment participants for two months. By analyzing smartphone usage pattern, we confirmed that about 12% of smartphone usage is being used in driving, walking, and on the street. In addition, we analyzed the response rate of smartphone notification in risk situations and confirmed that user responds the smartphone notifications in real-time even in risk situations. Therefore, it is required to present a system that intervenes the use of smartphone in order to protect smartphone users in risk situations. In this paper, we classify risk situations of using smartphone. Also, the proposed smartphone intervention system is designed to periodically detect risk situations. In risk situations, smartphone function can be restricted according to user setting of smartphone. And smartphone can be used normally when safe situation is restored.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.162-166
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• 2017

Earliest virtual deadline zero laxity (EVDZL) algorithm is proposed for mobile GPU schedulers for its improved responsiveness. Responsiveness of user interface (UI) is one of the key factors in evaluating smart devices because of its significant impacts on user experiences. However, conventional GPU schedulers based on completely fair scheduling (CFS) shows a poor responsiveness due to its algorithmic complexity. In this letter, we present the EVDZL scheduler based on the conventional earliest deadline zero laxity (EDZL) algorithm by accommodating the virtual laxity concept into the scheduling. Experimental results show that the EVDZL scheduler improves the response time of the Android UI by 9.6% compared with the traditional CFS scheduler.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.120.1-120
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• 2002

In this paper, we propose an interactive genetic algorithm (IGA) to implement an automated 2D avatar synthesis. The IGA technique is capable of expressing user's personality in the avatar synthesis by using the user's response as a candidate for the fitness value. Our suggested IGA method isapplied to creating avatars automatically. Unlike the previous works, we introduce the concepts of 'hidden population', as well as 'primitive avatar' and 'simplified genotype', which are used to overcome the shortcomings of IGA such as human fatigue or reliability, and reasonable rates of convergence with a less number of iterations. The procedure of designing avatar models consists of two steps. The firl...

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.7
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• pp.848-854
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• 1999

In this paper, we designed and implemented a precise pulse motor controller chip that generates the pulse needed to control step motor, DC servo and AC servo motors. This chip generates maximum pulse output rate of 5Mpps and has the quasi-S driving capability and speed and moving distance override capability during driving. We designed this chip with VHDL and executed a logic simulation and synthesis using Synopsys tool. The pre-layout simulation and post-layout simulation was executed by Compass tool. This chip was produced with 100 pins, PQFP package by 0.8${\mu}{\textrm}{m}$ gate array process and implemented by completely digital logic. We developed the test hardware board of performance and the CAMC(Computer Aided Motor Controller) Agent softwate to test the performance of the pulse motor controller chip produced. CAMC Agent enables user to set parameters needed to control motor with easy GUI(Graphic User Interface) environment and to display the output response of motor graphically.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.351-354
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• 2018

데스크탑과 모바일 기기가 고성능화됨에 따라 다양한 분야에서 고사양 응용들이 출시되고 있다. 이러한 응용들의 응답성은 사용자 경험을 결정하는 중요한 요소들 중 하나이다. 측정에 따르면 고사양 응용들 중 하나인 웹 브라우저의 응답시간에서 페이지 zeroing에 소요되는 시간이 적지 않은 비중을 차지한다. 또한 페이지 zeroing이 발생시키는 캐시 오염에 의해 추가적인 성능저하가 발생한다. 본 논문은 페이지 zeroing에 소요되는 시간을 단축하고, zeroing에 의한 캐시 오염으로 인해 발생하는 시스템의 성능저하를 방지하기 위한 기법을 제안한다. 제안된 기법은 사용자 응답시간이 아닌 구간에서 페이지들을 DMA를 사용하여 캐시를 거치지 않고 zeroing하여 보관해 두었다가 페이지 할당 요청시 선 zeroing 된 페이지들을 응용에게 제공한다. 이를 Linux 커널 4.17이 탑재된 데스크탑 환경에서 구현하였고 실험을 통해 확인한 결과 응답시간이 평균 20% 단축됨을 확인하였다.

• Journal of Korea Technology Innovation Society
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• v.8 no.3
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• pp.911-931
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• 2005

This paper analyzes the demand characteristics of DMB services using survey data. According to a Logit analysis, the willingness to adopt the services is higher if the would-be user is male, is better informed with the service, is watching TV longer, and is spending more for the telecommunications services. And the survey results tell us that for the stimulation of the service, efforts should be made to increase the level of public awareness of the services. The survey response from the would-be DMB users shows that the respondents who value the nationwide coverage and the numbers of channel are more inclined to use the satellite DMB service. On the other hand, the service charge and the availability of the terrestrial broadcasting channel for the time being does not seem to influence the intention of using the terrestrial DMB service. It could be interpreted that the potential user are deciding whether to use the service more by the quality and contents of the service rather than by the cost of the service.