• Journal of Communications and Networks
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• v.9 no.3
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• pp.247-253
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• 2007

In this paper, downlink capacity of time duplex division (TDD) based cellular wireless networks utilizing fixed hopping stations is investigated. In the network, a number of fixed subscriber stations act as hopping transmission stations between base stations and far away subscribers, forming a cellular and ad hoc mobile network model. At the radio layer, TDD code division multiple access (CDMA) is selected as the radio interface due to high efficiency of frequency usage. In order to improve the system performance in terms of downlink capacity, we propose different time slot allocation schemes with the usage of fixed hopping stations, which can be selected by either random or distanced dependent schemes. Performance results obtained by computer simulation demonstrate the effectiveness of the proposed network to improve downlink system capacity.

• Annual Conference of KIPS
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• 2019.10a
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• pp.817-819
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• 2019

다양한 학습 모델이 발전하고 있는 지금, 학습을 통한 다양한 시도가 진행되고 있다. 이중 에너지 분야에서 많은 연구가 진행 중에 있으며, 대표적으로 BEMS(Building energy Management System)를 볼 수 있다. BEMS의 경우 건물을 기준으로 건물에서 생성되는 다양한 DATA를 이용하여, 에너지 예측 및 제어하는 다양한 기술이 발전해가고 있다. 하지만 FEMS(Factory Energy Management System)에 관련된 연구는 많이 발전하지 못했으며, 이는 BEMS와 FEAMS의 차이에서 비롯된다. 본 연구에서는 실제 공장에서 수집한 DATA를 기반으로 하여, 전력량 예측을 하였으며 예측을 위한 기술로 시계열 DATA 분석 방법인 LSTM 알고리즘을 이용하여 진행하였다.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.2
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• pp.93-100
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• 2022

In this paper, we propose a machine learning-based method for supporting resource management of IoT software platforms in a multi-modal sensing scenario. We assume that an IoT device installed with a oneM2M-compatible software platform is connected with various sensors such as PIR, sound, dust, ambient light, ultrasonic, accelerometer, through different embedded system interfaces such as general purpose input output (GPIO), I2C, SPI, USB. Based on a collected dataset including CPU usage and user-defined priority, a machine learning model is trained to estimate the level of nice value required to adjust according to the resource usage patterns. The proposed method is validated by comparing with a rule-based control strategy, showing its practical capability in a multi-modal sensing scenario of IoT devices.

• Asia pacific journal of information systems
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• v.28 no.3
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• pp.204-219
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• 2018

This paper touches the limitations of existing theories related to technology acceptance, which mainly focus on users' perceived ease of use and usefulness, and proposes the role for sensory capabilities and enjoyment in understanding smartphone use. Furthermore, we develop a model that explains smartphone usage and intention to use it for a task and analyzes 442 questionnaire survey responses of smartphone users. First, perceived usefulness, perceived sensory capability, and perceived enjoyment influenced smartphone usage. Second, we found that both perceived usefulness and smartphone use were significantly associated with users' intention to utilize the smartphone for their job-related tasks. Finally, both perceived sensory capability and enjoyment were found to be more powerful factors than ease of use in explaining smartphone use. From the study findings, implications and future research directions are also discussed.

• Journal of Information Technology Services
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• v.11 no.2
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• pp.19-47
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• 2012

Contemporary smartphone competition is generally described as the battle between Apple's proprietary platform and Google's open platform. However, this competition is not limited within smartphone adoption itself. User's pre-adoption of one mobile platform via smartphone can be connected to the post-adoption of the same mobile platform based on the other smart devices (e.g. smart pad). In this study, we investigate whether user's preference to a certain platform is persistent over mobile ecology, from the pre-adoption of one smart device to the post-adoption of following devices. For this investigation, we adopt the dual-model as the ground theory, where post-adoption of IT product is explained by both dedication and constraint factors. The empirical testing first evidences that dual model works well as our research model for identifying the reasons of post-adoption. Next, we group our data into two parts in order to compare the switching behavior of iPhone users and Android phone users. iPhone users show much lower switching rate to Android based smart pads, while Android phone users show higher churn rate to iPad (49.3% : 96.3%). Especially, satisfaction showed much stronger effect than switching cost on the continuing intention of existing platform, when the analysis is given to the iPhone user's group. From this result, we can conjecture the relatively stronger loyalty of iPhone users. More managerial implications on the mobile platform strategy are driven.

• Journal of Korea Society of Industrial Information Systems
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• v.22 no.1
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• pp.11-21
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• 2017

Internet Banking Offers Major Advantages for Both Banks and Customers. However, Not All People have equal Access or Skills to use such Services. The Main Objective of this Study is to Understand the Fctors Influencing Internet Banking Usage we Developed a Research Model Drawing from the UTAUT and Digital Divide Research. The Model was Tested and find more than 90% of Variance of Internet Banking Usage was Explained by the Model. Results Demonstrate that the Strongest Factor Influencing the Intention to adopt Internet Banking Services is the Degree to which an Individual Believes that it is Safe to use such Services. In the Paper, all the Hypotheses Except for the Hypothesis on the Effort Expectation are Accepted with Statistical Significance.

• Journal of Korea Game Society
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• v.16 no.6
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• pp.39-48
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• 2016

This study intended to find out the influence of media usage motivations including Wishful Identification toward BJ, Entertainment, Passing Time, Information Seeking on watching personal game webcasting, based on Use & Gratification Theory. We conducted a survey of 395 audiences who had experienced in watching personal game webcasting and analyzed collected data using hierarchical regression analysis. First, we put and analyzed demographic factors of audiences in model 1. After that, we added media usage motivations in model 2. As a result of the study, gender and age in model 1 and age, Wishful Identification and Entertainment in model 2 are found to have a significant influence on watching personal game webcasting respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.10 s.89
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• pp.969-976
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• 2004

The wide and growing use of cellular phones has raised the question about the possible health risks associated with radio-frequency electromagnetic fields. It would be helpful for phone users to blow the exposure levels during cellular phone use. But it is very difficult to recognize the amount of exposure, because measuring accurate level of RF is a difficult matter. In this study, we developed a model to estimate the exposure level and the individual risk of exposure by utilizing the available informations that we can get. We used such parameters as usage time a day, total using period, distance between cellular phone and head, slope of cellular phone, hands-free usage, antenna pulled out or not SAR(Specific Absorption Rate) of cellular phone, and flip or folder type. We proposed a model presenting individual risk of RF exposure from level 0 to 10 by using a neural network.

• Journal of the Korean Society for Library and Information Science
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• v.35 no.2
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• pp.151-170
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• 2001

Pricing for e-journals has become more complex than before-certainly much more complex than print pricing has ever been. E-journals charge either a fiat fee based on print, user, library size, usage, and combination. A survey of publisher's pricing structure found that print based model is popular followed by user based model. The current pricing situation is far from equitable and can be improved if publishers can be coerced to change their pricing practices. This study focus on a number of possible pricing models that may supplement and/or possibly replace the current print based model. With the possibility that its pricing will eventually be based strictly according to usage, may lead to the most equitable pricing model as well as the most efficient use of society's resources. Libraries can alleviate the pricing problem by encouraging library organizations and university consortia to exploit their potential monopoly power into a bilateral monopoly situation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.67-71
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• 2023

Recently, there are increasing cases of managing software labs by assigning virtual PCs in the cloud instead of physical PCs to each student. In this paper, we design and implement a Linux-based software practice platform that allows students to efficiently build their environments in the cloud. In our platform, instructors can create and control virtual machine templates for all students at once, and students practice on their own machines as administrators. Instructors can also troubleshoot each machine and restore its state. Meanwhile, the biggest obstacle to implementing this approach is the difficulty of predicting the costs of cloud services instantly. To cope with this situation, we propose a model that can estimate the cost of cloud resources used. By using daemons in each user's virtual machine, we instantly estimate resource usage and costs. Although our model has very low overhead, the predicted results are very close to the actual resource usage measured by cloud service providers. To further validate our model, we used the proposed platform in a Linux practice lecture for a semester and confirmed that the proposed model is very accurate.