• Journal of Advanced Navigation Technology
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• v.17 no.5
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• pp.506-515
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• 2013

In cognitive radio networks, several research works typically address the framework which consists of a spectrum sensing period and a data transmission period. When the frame period is short, there is the problem that the throughput of secondary users decrease. In this paper, aggregated data slot structure is considered to increase the throughput of secondary users. Chapman-Kolmogorov equation is used for the modeling of the transmission probability of primary users and formulation of an optimization problem to maximize the throughput of secondary users. Solution of the optimization problem results in the optimal spectrum sensing time, the length of data slot and the number of data slots governed by a spectrum sensing.

• Korean Journal of Remote Sensing
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• v.18 no.1
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• pp.61-69
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• 2002

The purpose of Electro-Optical Camera (EOC), the primary payload of KOMPSAT-1, is to collect high resolution visible imagery of the Earth including Korean Peninsula. EOC images will be distributed to the public or many user groups including government, public corporations, academic or research institutes. KARI will offer the online service to the users through internet. Some application, e.g., generation of Digital Elevation Model (DEM), needs a secondary data such as satellite ephemeris data, attitude data to process the EOC imagery. EOC imagery with these ancillary information will be distributed in a file of Hierarchical Data Format (HDF) file formal. HDF is a physical file format that allows storage of many different types of scientific data including images, multidimensional data arrays, record oriented data, and point data. By the lack of public domain softwares supporting HDF file format, many public users may not access EOC data without difficulty. The purpose of this research is to develop a browsing system of EOC data for the general users not only for scientists who are the main users of HDF. The system is PC-based and huts user-friendly interface.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.11
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• pp.3064-3082
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• 2023

During the last decade, several Electronic Orientation Aids devices have been proposed to solve the autonomy problems of visually impaired people. When hearing is considered the primary sense for Visually Impaired people (VI) and it is generally loaded with the environment, the use of tactile sense can be considered a solution to transmit directional information. This paper presents a new wearable haptic system based on four motors implemented in shoes, while six directions can be played. This study aims to introduce an interface design and investigate an appropriate means of spatial information delivery through haptic sense. The first experiment of the proposed system was performed with 15 users in an indoor environment. The results showed that the users were able to recognize, with high accuracy, the directions displayed on their feet. The second experiment was conducted in an outdoor environment with five blindfolded users who were guided along 120 meters. The users, guided only by the haptic system, successfully reached their destinations. The potential of tactile-foot stimulation to help VI understand Electronic Orientation Aids (EOA) instructions was discussed, and future challenges were defined.

• Journal of Information Technology Services
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• v.23 no.2
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• pp.117-133
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• 2024

This research analyzes users' cognitive responses to Out-Of-Home advertising content based in virtual environments. Specifically, it distinguishes the depth of advertisements as 2D or 3D and categorizes animation effects of light as a representation of virtuality into 'none', 'blinking', and 'flowing'. For this purpose, virtual reality content was developed, and after experiencing the content while wearing HMD, users' cognitive responses were investigated. Involving 60 participants, the study found that the interaction effects between depth perception and animation effects were not statistically significant, nor was the primary effect of depth perception. However, the main effect of animation showed statistically significant differences in users' attention, vividness, perceived intrusiveness, avoidance tendency, and flow. This study presents design elements that can be utilized in the production of virtual environment-based Out-Of-Home advertising and experimentally demonstrates that animation effects can serve as an effective means of emphasis in virtual environment advertising. These findings provide important insights for the creation and strategic planning of advertisements in virtual environments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.72-81
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• 2009

In this paper, we investigate a spectrum sharing scheme based on the interference temperature (IT), that is a recently introduced receiver-centric metric by FCC. We extend the existing frequency sharing procedure for single CR to the one for multiple CRs (or secondary users, SUs). In the proposed interference model, we consider the practical operating characteristics of primary users (PUs), stochastically activated (ON)/deactivated (OFF) at the time axis, and analyze quantitatively the CR user capacity based on the model. We define the instantaneous capacity for idle time-slot channel allocation and the mean capacity averaging this instantaneous capacity and use them for a proper frequency sharing. Apart from existing schemes, the proposed frequency sharing scheme changes the frequency parameters adaptively depending on the channel characteristics and does not need any sensing information from PUs. Through computer simulation, we verify the proposed model.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.29 no.2 s.43
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• pp.79-104
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• 2003

Introducing to the market place, safe and effective product is an important responsibility of clinical investigators as well as regulatory agencies in all developed countries. Products claiming to improve skin wrinkles are no exceptions. To date, Renova(R) (all-trans retinoic acid), Avage(R) (tazarotene), and Botox(R) (botulinum toxin) are the only agents FDA approved to ameliorate wrinkles associated with photoaged skin in the USA. For all three, clinical evaluation of wrinkle severity was the primary endpoint required for the approval process. No sophisticated instrument measurements of wrinkles were required, nor used in the pivotal studies. The Division of Dermatologic & Dental Products of the US FDA (Director, Jonathan Wilkin, MD) is not against the use of mechanical instruments in assessing wrinkle severity. Its position on this issue however, remains that any such device must be grounded in patients' or product users' perspective, which means that the evaluation instrument must be clinically relevant and clinically perceptible. Sophisticated devices that can detect minimal improvement, but imperceptible to the users are considered useless in the eyes of the US FDA. Two instruments that have been tried in some antiwrinkle studies in the USA are silicone replicas and Primos. Despite their sophistications, they have clear limitations; thus have never replaced clinical evaluations in these studies. At most, they have served as secondary measures to provide corroborative data on the clinical efficacy of antiwrinkle products. For the foreseeable future, at least in the USA, careful clinical assessment of wrinkles will continue to serve as the critical benchmark to determine whether an antiwrinkle product has enough efficacy to benefit its users. We must not lose sight of the fact that sophisticated devices are only to serve in generating supportive evidence, and not the primary evidence, in any clinical studies.

• Korean Journal of Clinical Pharmacy
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• v.25 no.4
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• pp.273-279
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• 2015

Objective: Codeine may result in death or respiratory depression in children, particularly who are rapid metabolizer of CYP2D6, therefore it should be used cautiously among children under 12 years of age. This study was to investigate the prescribing pattern of codeine among children according to the age group, prescribed diagnosis, type of medical service and medical specialties. Method: We used Korea Health Insurance Review and Assessment Service-National Patient Sample (HIRA-NPS) database. Study subjects included inpatients or outpatients, who were prescribed codeine between January, 1, 2011 and December, 31, 2011. Contraindicated use of codeine was defined as the use of codeine at least one times under aged 12. Age groups were subclassified according to the <2 years, 2-4 years, 5-8 years, and 9-11 years. Frequently prescribed diagnosis (ICD-10), type of medical service, and medical specialties were also described among codeine users under aged 12. Results: Codeine users were 6,411 inpatients (9,958 prescriptions), and 3,397 outpatients (6,258 prescriptions), respectively. Codeine prescription under 12 years of age were 2.1% (210 prescriptions) among inpatients, and 12.3% (776 prescriptions) among outpatients (p-value<0.05). Outpatient prescriptions of codeine under 12 aged were issued mostly from primary care clinics and frequent diagnosis were unspecified bronchopneumonia (51.6%), and vasomotor rhinitis (23.7%). Conclusion: This study found prescribing of codeine under 12 aged is common in outpatient and primary clinics. Nationwide and community-based efforts should be needed to reduce inappropriate prescribing among children.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1623-1635
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• 2011

Fourth-generation (4G) cellular communication systems must provide different quality-of-service (QoS) to users according to the service type, membership class, and usage case of each user. For the purpose of user's QoS differentiation, we propose an enhanced uplink random access scheme for bandwidth request. More specifically, we divide a bandwidth request channel into two parts: One is a primary region and the other is a secondary region. Then, each region has a unique minimum access class that allows only specific users to perform random access through that region. By doing so, we can reduce collision probability and increase the success probability of bandwidth request. From the perspective of standardization, we presented this scheme in the IEEE 802.16m Session #66 held on March 2010. As a result, the concept of the proposed scheme and required messages were defined in the 802.16m standard.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.9-15
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• 2010

Cognitive radio is a technology, which automatically recognizes and searches for temporally and spatially unused frequency spectrum, then actively determines the communication method, bandwidth, etc. according to the environment, thus utilizing the limited spectrum resources efficiently. In this paper, with the imperfect sensing of misdetection and false alarm, we quantitatively investigate the effects of primary and secondary user's queue on the primary and secondary users' spectrum usage through the analysis of continuous time Markov Chain. With the queue primary user's spectrum usage improved up to 18%, and the secondary user's spectrum usage improved up to 50%.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.6
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• pp.357-366
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• 2013

Spectrum sensing, as a fundamental functionality of Cognitive Radio (CR), enables Secondary Users (SUs) to monitor the spectrum and detect spectrum holes that could be used. Recently, the security issues of Cognitive Radio Networks (CRNs) have attracted increasing research attention. As one of the attacks against CRNs, a Primary User Emulation (PUE) attack compromises the spectrum sensing of CR, where an attacker monopolizes the spectrum holes by impersonating the Primary User (PU) to prevent SUs from accessing the idle frequency bands. Energy detection is often used to sense the spectrum in CRNs, but the presence of PUE attack has not been considered. This study examined the effect of PUE attack on the performance of energy detection-based spectrum sensing technique. In the proposed protocol, the stationary helper nodes (HNs) are deployed in multiple stages and distributed over the coverage area of the PUs to deliver spectrum status information to the next stage of HNs and to SUs. On the other hand, the first stage of HNs is also responsible for inferring the existence of the PU based on the energy detection technique. In addition, this system provides the detection threshold under the constraints imposed on the probabilities of a miss detection and false alarm.