• Journal of Convergence for Information Technology
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• v.10 no.9
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• pp.22-27
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• 2020

In the fifth generation (5G) networks, the mobile services require much faster connections than in the fourth generation (4G) mobile networks. Recently, as one of the promising 5G technologies, non-orthogonal multiple access (NOMA) has been drawing attention. In NOMA, the users share the frequency and time, so that the more users can be served simultaneously. NOMA has several superiorites over orthogonal multiple access (OMA) of long term evolution (LTE), such as higher system capacity and low transmission latency. In this paper, we investigate impact of channel estimation errors on successive interference cancellation (SIC) performance of NOMA. First, the closed-form expression of the bit-error rate (BER) with channel estimation errors is derived, And then the BER with channel estimation errors is compared to that with the perfect channel estimation. In addition, the signal-to-noise (SNR) loss due to channel estimation errors is analyzed.

• Journal of The Korean Association of Information Education
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• v.24 no.2
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• pp.139-146
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• 2020

There is a hot debate about what the core competencies of future generations, who have to live an uncertain future, should cultivate. The future society is expected to become a Software-oriented Society driven by software. Under these circumstances, interest in software education is exploding around the world, and interest in cultivating computational thinking through software education is also increasing. Also, discussions about what computational thinking is and what competence factors are made up are in progress. However, the research on the relationship between the competence factors of computational thinking is relatively insufficient. In order to solve this problem, this study proceeded as follows. First, five competence factors of computational thinking were selected. Second, we defined a path model to analyze the relationships among the competence factors of computational thinking. Third, we chose a test tool to test computational thinking. Fourth, the computational thinking tests were conducted for 801 students in grades 3 through 6 of elementary school. Fifth, implications were derived by analyzing various viewpoints based on the results of the computational thinking test.

• Earthquakes and Structures
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• v.19 no.1
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• pp.45-57
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• 2020

This paper presents the experimental application of a new method for seismic vulnerability assessment of buildings recently introduced in literature, the SMAV (Seismic Model Ambient Vibration) methodology with reference to their operational limit state. The importance of this kind of evaluation arises from the civil protection necessity that some buildings, considered strategic for seismic emergency management, should retain their functionality also after a destructive earthquake. They do not suffer such damage as to compromise the operation within a framework of assessment of the overall capacity of the urban system. To this end, for the characterization of their operational vulnerability, a Structural Operational Index (IOPS) has been considered. In particular, the dynamic environmental vibrations of the two considered strategic buildings, the fire station and the town hall building of a small town in the South of Italy, have been monitored by positioning accelerometers in well-defined points. These measurements were processed through modern Operational Modal Analysis techniques (OMA) in order to identify natural frequencies and modal shapes. Once these parameters have been determined, the structural operational efficiency index of the buildings has been determined evaluating the seismic vulnerability of the strategic structures analyzed. his study aimed to develop a model to accurately predict the acceleration of structural systems during an earthquake.

• Journal of Broadcast Engineering
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• v.22 no.5
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• pp.600-607
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• 2017

Virtual Reality (VR) has lately gained significant attention primarily driven by the recent market availability of consumer devices, such as mobile phone-based Head Mounted Displays (HMDs). Apart from classic gaming use cases, the delivery of $360^{\circ}$ video is considered as another major application and is expected to be ubiquitous in the near future. However, the delivery and decoding of high-resolution $360^{\circ}$ videos in desirable quality is a challenging task due to network limitations and constraints on available end device decoding and processing. In this paper, we focus on aspects of $360^{\circ}$ video streaming and provide an overview and discussion of possible solutions as well as considerations for future VR video streaming applications. This paper mainly focuses on the status of the standardization activities, Omnidirectional MediA Format (OMAF), to support interoperable $360^{\circ}$ video streaming services. More concretely, MPEG's ongoing work for OMA aims at harmonization of VR video platforms and applications. The paper also discusses the integration in MPEG Dynamic Adaptive Streaming over HTTP (MPEG-DASH), which is considered as $360^{\circ}$ video streaming services with OMAF content. In context of the general OMAF service architecture.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.1
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• pp.30-35
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• 2017

In this study, we measured the natural frequencies of aluminum honeycomb sandwich beams using digital image correlation technique. The vibration images were captured using two high speed digital cameras and the images were converted to displacements by the digital image correlation technique. Displacement data in time domain were tranformed to frequency domain data by fast Fourier transform software. To reduce noise invoked by random exitation, a spectrum averaging technique and Savitsky-Golay digital filter were adopted. A conventional vibration measurement using an accelerometer and a finite element analysis were performed to compare the results by high speed digital camera measurement method. In conclusion, new method using high speed digital cameras and digital image correlation technique can measure the vibration of beam structures and can be applied to bio-structures where sensors cannot be attached.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.527-534
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• 2009

Almost every mobile phone supports MMS to send and receive multimedia messages among users. MMS is suitable for different types of mobile phones and effectively operates in wireless environments. So the mobile content delivery method using MMS can be efficient. However, there would be some problems if a mobile service provider tries to deliver mobile content to subscribers by using the existing MMS. In this paper, we propose an improved data transmission and control scheme for MMS. Our scheme assists mobile service providers to deliver mobile contents easily by modifying the MMS system software. By using our scheme, mobile service providers are able to manage mobile contents stored in mobile devices. Therefore, they can provide various services such as mobile daily news service, automatic software upgrade service, mobile advertising service, etc. We verify the possibility of the proposed scheme through simulation.

• Korean Institute of Interior Design Journal
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• v.24 no.6
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• pp.79-86
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• 2015

This study started from the concern for Bjrake Ingels, an emerging architect in the architecture circle, who is creative and popular. Recently, the architecture field provides architects with a foundation to express a process on a new form creation through various new expressive languages, design concepts, and methods. The global Danish group BIG(Bjarke Ingels Group) develops a story by their distinctive architectural language. The storytelling is being used in various fields and now the tool called 'story' is settling down as an important element in the life that human lives. Bjarke Ingels leading the group BIG aims for the form expression by the scientific analysis and adaptation after being affected by Danish regional background and OMA. It creates a form to share stories with local members by visually simplifying the region, culture, environment, social phenomenon, economy, and politics that are invisible and do not have the form in the modern society. The elements and expressive features of the space storytelling include locality, cultural, natural environment, and connectivity which are the content structure(story) that enables you to intervene in the story according to the main agent to imagine a new space. The expressive element includes the watching moving line story of the successive, hierarchical, and organic structures which are constructive elements creating various spaces through the mixture, transmutability, and relocation of the program and inducing users to the space. The space storytelling is composed of the symbolism, community, and eco-friendliness to appear diversely through BIG's case analysis. This study will have significance that it drew a method and feature looked at by many contemporary architects from the storytelling viewpoint in the form-creating process, classified the form-creating process through a new storytelling type, and showed a possibility on the development of various methodologies.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.137-139
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• 2012

최근 다양한 모바일 플랫폼과 애플리케이션 스토어에 대한 문제가 점점 커져가고 있다. 그에 발맞추어 최근 애플리케이션 시장규모는 대대적으로 웹으로 넘어가고 있으며, 스토어 또한 같이 성장해 가고 있다. 그러나 현재 출시된 웹 애플리케이션 스토어는 한 스토어에 종속적인 단점을 가지고 있어, 사용자로부터 스토어에 종속된 애플리케이션에 대하여 타 플랫폼에서는 애플리케이션을 사용할 수 없어 사용자에게 폭넓은 선택을 제한하며 불편을 가져다준다. 본 논문에서는 이러한 단점에 대한 해결책으로 웹 애플리케이션 스토어의 연동 모듈을 설계하고, 이를 토대로 웹 애플리케이션 연동 시나리오를 구현한다. 웹 애플리케이션 스토어의 기본 구조는 OMA(Open Mobile Alliance)에서 제안한 TAS(Telco's Application Store)를 따랐으며 기존 TAS의 모듈에 연동을 위한 모듈을 추가 확장하여 설계하고 이를 OWS(Open Web Store)라 명한다. OWS는 차세대 웹 언어를 사용하는 웹 애플리케이션을 다루기 때문에 애플리케이션 플랫폼에 독립적인 성향을 가지므로 소비자는 운영체제, 브라우저, 단말기 등의 종류에 구애 받지 않고 다양한 애플리케이션을 접할 수 있다. 본 논문에서 OWS간 연동을 위한 시나리오를 구상하고 프로토타입을 구현하여 기존의 애플리케이션의 단점을 보완할 수 있는 방법을 제시한다.

• The korean journal of orthodontics
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• v.14 no.1
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• pp.151-160
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• 1984

This study was designed to get the informations of the mesiodistal axial inclinations of the posterior teeth and of the relationships between these and other angular measurements of facial bony structures in normal occlusion and malocclusion groups using lateral roentgenocephalograms. The subjects consisted of 73 normal occlusions (31 males 42 females), 38 Class II Division 1 malocclusions (17 males 21 females) and 47 Class III malocclusions (19 males 28 females). The findings of this study are as follows : 1. In mandible, the posterior teeth axes of Class II Division 1 malocclusion group were inclined more mesially and those of Class III malocclusion group were inclined more distally than normal occlusion group. In maxilla, Class II Division 1 malocclusion group showed more distal inclination and Class III malocclusion group showed more mesial inclinaton of 1st, 2nd premolars and more distal inclination of 1st, 2nd molars than those of the normal occlusion group. 2. There was a tendency for teeth axes to maintain nearly the same inclination in relation to occlusal plane irrespective of various OMA and OPA in each group. 3. F M A, P M A and O P A were the largest in Class II Division 1 malocclusion group and O M A, GoA were the largest in Class 111 malocclusion group. 4. There were high correlationships between mandibular teeth inclinations related to mandibular plane and 4 angular measurements except OPA, and between maxillary teeth inclinations related to palatal plane and OPA.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.122-129
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• 2009

In this paper, we have proposed the QoS (quality of services) control scheme which can adjust data transfer rates of the session participants in response to their radio channel conditions under the time-varying propagation radio environment. The outage probability is selected as the performance index in order to compare the performance of the proposed scheme with the conventional QoS control scheme. The outage probability of the single and multiple paths is mathematically derived here and its numerical results are investigated. The results show that the significant performance improvement can be obtained compared with the conventional scheme and also the diversity gain can improve the radio link outage as the degrees of the multipath diversity increases. Therefore the overall performance improvement in terms of the QoS of the outage probability can be significantly be achieved by applying the proposed scheme.