• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.123-129
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• 2018

Recently, as required wireless communication traffic increase, millimeter wave mobile technologies that can secure broadband spectrum are gaining attention. However, the path loss is high in the millimeter wave channel. Massive MIMO system is being researched in which can complement the path loss by beamforming by equiped large-scale antenna at the base station. While legacy beamforming techniques have analog and digital methods, practical difficulties exist for application to massive MIMO systems in terms of system complexity and cost. Therefore, this paper studies a hybrid beamforming scheme for massive MIMO system in the millimeter wave band. Also this paper considers spatial multiplexing scheme to serve multi-users with multiple received antennas. Gains of the beamforming and the spatial multiplexing schemes are evaluated by analyzing the spectral efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.896-905
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• 2005

In this paper, we propose a SPD(Selective Packet Delay) scheme to improve the performance of High-Speed Downlink Shared Channel(HS-DSCH) employing N-Channel Stop and Wait retransmission scheme in High Speed Downlink Packet Access(HSDPA) system. The proposed SPD coordinates packet transmissions according to the channel condition. When the channel condition is bad, packet transmission is forcedly delayed, and the designated time slot is set over to other users in good channel condition. Hence, the SPD is able to reduce the average transmission delay for packet transmission under the burst error environments. In addition, we propose two packet scheduling schemes called SPD-LDPF(Long Delayed Packet First) and SPD-DCRR(Deficit Compensated Round Robin) that are effectively combined with the SPD scheme. Simulation results show that the proposed scheme has better performance in terms of delay, throughput and fairness.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.2
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• pp.150-160
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• 2016

The quality of service in ERP services is a key issue in innovating the ERP performance as an IT service for corporations. Currently, most of the research works for this area are based on the existing quality models such as SERVQUAL, which are said not to measure service quality properly. Also, it does not consider the factor of the system acceptance, which is thought to be closely related to the quality of service in this type of IT services. Therefore, a research model is required, which can address the issues related to the ERP service quality measurements. In this paper, new research models have been proposed, and empirical data obtained from SME's ERP users have been applied to the proposed model to analyze the causal relationship between quality factors and to identify the most suitable quality measures. Also, the relationship between the service quality and the system acceptance was analyzed using a combined model. The results show that factors such as productivity and convenience affects the quality mostly and that the most appropriate measure for the service quality of ERP service is satisfaction. Also, for the system acceptance, the ease-of-use is the main factor. And, the service quality and system acceptance shows a strong correlation. This means that, in order to enhance the quality of ERP services, the service provider needs to provide customers with productivity-enhanced user-friendly IT services and active product support. The work of this research can help to improve the service quality and the user acceptance of ERP services and to lead further research works in this area.

• Journal of the Korea Computer Graphics Society
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• v.24 no.4
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• pp.39-54
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• 2018

Recently, augmented reality(AR) based building information applications using a smart phone provide information in the static form irrespective of the distance between a user and a target building. If many target buildings are located close to each other, discrimination of information is reduced due to overlapping information objects. Furthermore, it is difficult to intuitively grasp the current position of the user in the previous AR-based applications. In this paper, to solve these limitations, we have designed and implemented a novel building information system in which the location and size of information objects are adaptively displayed according to locations of a user and target buildings, and which allows users to intuitively understand their location by providing a 3D map that displays the user's location and all target buildings within a given distance in real-time. The AR-based building information application proposed in this paper focuses on the building guide in Deoksu Palace in Jung-gu, Seoul.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.10
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• pp.939-947
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• 2010

With the rising numbers of elderly and disabled people, the demand for welfare services using a robotic system and not involving human effort is likewise increasing. This study deals with a mobile-robot system combined with a BWS (Body Weight Support) system for gait rehabilitation. The BWS system is designed via the kinematic analysis of the robot's body-lifting characteristics and of the walking guide system that controls the total rehabilitation system integrated in the mobile robot. This mobile platform is operated by utilizing the AGV (Autonomous Guided Vehicle) driving algorithm. Especially, the method that integrates geometric path tracking and obstacle avoidance for a nonholonomic mobile robot is applied so that the system can be operated in an area where the elderly users are expected to be situated, such as in a public hospital or a rehabilitation center. The mobile robot follows the path by moving through the turning radius supplied by the pure-pursuit method which is one of the existing geometric path-tracking methods. The effectiveness of the proposed method is verified through the real experiments those are conducted for path tracking with static- and dynamic-obstacle avoidance. Finally, through the EMG (Electromyography) signal measurement of the subject, the performance of the proposed system in a real operation condition is evaluated.

• Journal of the Korea Computer Industry Society
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• v.7 no.1
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• pp.17-22
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• 2006

Variable contents are extracted and used to improve the correctness of the retrieval in the content-based in age retrieval. This way use the physical feature for the retrieval. In this way of retrieval, the user has to know the basic physical features and spatial relationship of target images that he wants to retrieve. There are some restriction to reflect the user's intend. We need the retrieval system that reflect the user's intend. In this paper, we propose an emotion-based retrieval system. It is different from past emotion based image retrieval in point of view that it uses relevance feedback to estimate the users intend and it is easily combined with past content-based image retrieval system. The features and similarity measures are adopted from MPEG-7 color descriptors which are proper retrieval of large multimedia databases. We use wallpaper images for the experiment. The result shows that the system get successful result.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.477-481
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• 2008

Place recognition is necessary for a mobile user to be provided with place-dependent information. This paper proposes real-time video based place recognition system that identifies users' current place while moving in the building. As for the feature extraction of a scene, there have been existing methods based on global feature analysis that has drawback of sensitive-ness for the case of partial occlusion and noises. There have also been local feature based methods that usually attempted object recognition which seemed hard to be applied in real-time system because of high computational cost. On the other hand, researches using statistical methods such as HMM(hidden Markov models) or bayesian networks have been used to derive place recognition result from the feature data. The former is, however, not practical because it requires huge amounts of efforts to gather the training data while the latter usually depends on object recognition only. This paper proposes a combined approach of global and local feature analysis for feature extraction to complement both approaches' drawbacks. The proposed method is applied to a mobile information system and shows real-time performance with competitive recognition result.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.14
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• pp.5517-5522
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• 2014

Oral contraceptive use is the most common type of contraception. More than 300 million women worldwide take oral contraceptives every day. However, there is a concern about the relationship with the incidence of cancer. This analytical retrospective study aimed to investigate the relationship between the incidence of cervical and breast cancers and oral contraceptive use in 128 Iranian patients with cervical cancer, 235 with breast cancer and equal numbers of controls. Data were collected through interviews with an organized set of questions. Details were also extracted from patient files. Data were analyzed using Student's t-test, chi-square and Fisher's exact tests, and Pearson's correlation analysis. The result revealed correlations between both cervical and breast cancers and history of contraceptive pills use. While cervical cancer significantly correlated with duration of use of pills, breast cancer had significant correlations with the type of oral contraceptive and age at first use. No significant relationships were found between the two types of cancer and age at discontinuation of oral contraceptives, patterns of use, and intervals from the last use. The use of oral contraceptives may triple the incidence of cervical cancer and doubles the incidence of breast cancer. Therefore, performing Pap smears every six months and breast cancer screening are warranted for long-term oral contraceptive users.

• The KIPS Transactions:PartB
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• v.10B no.2
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• pp.179-188
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• 2003

In content-based image retrieval, the query is an image itself and the retrieval process is the process that seeking the similar images to the given query image. In this way of retrieval, the user has to know the basic physical features of target images that he wants to retrieve. But it has some restriction because to retrieve the target image he has to know the basic physical feature space such as color, texture, shape and spatial relationship. In this paper, we propose an emotion-based retrieval system. It uses the emotion that color images have. It is different from past emotion-based image retrieval in point of view that it uses relevance feedback to estimate the users intend and it is easily combined with past content-based image retrieval system. To test the performance of our proposed system, we use MPEG-7 color descriptor and emotion language such as "warm", "clean", "bright" and "delight" We test about 1500 wallpaper images and get successful result.lpaper images and get successful result.

• Korean Institute of Interior Design Journal
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• v.19 no.3
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• pp.224-233
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• 2010

As urban function has become diversified and complicated, multifunctional complex facilities to satisfy new functional desires are necessary. Since local autonomy started, many facilities previously run and managed by central administrative agencies are now under management of localities, and functionally, the necessity for governments complexes town to satisfy diverse taste of populace such as creating local community becomes imminent. Analyzing characteristics by space composition factor of the public health center, newly built as part of such governments complexes town and understanding required area of each part, this project is to be used as basic material for construction plan of public health center that is equipped with local characters while devising construction of the public health center in the governments complexes town. Research method is to analyze four public health center facilities located in governments complexes town sites built after 2007, among twenty five public health centers in Seoul, by spatial functions. Also, based on statistical documents of usage of public health center facilities, research over spatial compositional factors and area composition has been conducted. As a result, connectivity between local government building located inside the governments complexes town and public health center and that of spatial composition factor by part, area ratio by part and floor type of public health center are comprehended. Connectivity type of public health centers are divided into horizontal and vertical connectivity and it is found that spatial composition of public health center is compartmentalized into low level, mid level and high level, to make access by users easier. Level type is decided as radial, rotational and combined by hallway connecting facilities.