• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.182-189
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• 2003

Communication Ocean Meteorological Satellite(COMS) for the hybrid mission of meteorological observation, ocean monitoring, and telecommunication service is planned to be launched onto Geostationary Earth orbit (GEO) in 2008 according to the korea national space program, For the development of the meteorological payload of COMS, imager, the characteristics of Modulation Transfer Function (MTF) for GEO meteorological imager is investigated and the theoretical MTF limit is analyzed for each spectral channel of the imager in the both cases of a currently operating GEO instrument technology and an advanced GEO instrument technology under development. This study shows that MTF value can be considerably low in the infrared channels with longer wavelength than 10㎛ due to diffraction effect so that the MTF performance of long wavelength infrared channels should be paid attention to for the development of the imager.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.756-759
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• 2012

This paper presents the multibeam service coverage of GEO(Geostationary Orbit) satellite and the practical antenna scheme scenarios to provide the universal communication services on the Korean peninsula. The proposed antenna systems consist of the simplest scheme and feed network so that they can be mounted on satellites. The feed networks are effectively organized according to the frequency and polarization plan. Despite simple structure, all scenarios meet the electrical performance by the optimization of feed allocation and feed excitation.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.189-192
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• 2017

본 논문에서는 하이브리드라디오 서비스를 성공적으로 도입하기 위해 필요한 정책적 조건들을 제안한다. 하이브리드라디오는 그 UI(User Interface) 특성과 오디오 방송 콘텐츠 외 서비스 구현으로 인해 기존 지상파플랫폼 외 추가적인 플랫폼이 필요하며, 이들 플랫폼을 구축하고 운영하는 새로운 플랫폼사업자의 등장을 수반하게 된다. 콘텐츠공급자와 플랫폼사업자가 일치하던 지상파 방송 산업과 달리 콘텐츠사업자와 플랫폼사업자가 분리되는 산업에서는 소수 플랫폼사업자가 다수 콘텐츠사업자에 비해 협상력 우위에 서는 역학관계가 생기게 되고, 이런 게임의 룰에 익숙하지 않고 사업적 규모도 영세한 지상파라디오 사업자들은 힘겹고 불공정한 사업 환경 속에 던져지는 상황을 맞게 될 수도 있다. 따라서 플랫폼사업자와 콘텐츠사업자가 상생하면서도 경쟁의 효율을 높이기 위해선 정교한 정책적, 제도적 장치가 필요하다. 또 하이브리드라디오가 기존 라디오 산업 내 제로섬 경쟁을 넘어 전체 이용자 규모를 확대하고 이를 효과적으로 수익과 연결하기 위해서는, 하이브리드라디오의 기술적 특성이 수용자에게 의미 있는 편익이 될 수 있도록 하이브리드라디오의 사업적 가능성을 충분히 활성화할 수 있는 제도 개선이 필요하다. 마지막으로 급변하는 미디어 빅뱅 상황에서 유의미한 유효 기간 내에 하이브리드라디오라는 신규 콘텐츠 유통 플랫폼을 성공적으로 도입하기 위해서는 산업 플레이어 간 불필요한 오해를 줄여 무의미한 논란을 최소화해야 한다.

• Journal of IKEEE
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• v.19 no.3
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• pp.327-334
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• 2015

Various types of middle-ware were created for integration between legacy systems and newly built systems. RPC(Remote Procedure Call), MOM(Message Oriented Middle-ware) and TM(Transaction processing Monitor) are the typical types of middle-ware. One of the most known MOM type middle-ware is PS(Publish/Subscribe). PS enables to create a system which has low coupling and high scalability. But PS based systems also have low cohesiveness. On the contrary, RPC has high cohesiveness but also has high coupling. This paper proposed design and implementation of hybrid model which offset disadvantages of RPC and PS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1249-1272
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• 2016

In this paper, we propose a symmetric key establishment scheme for wireless sensor networks which tries to minimize the resource usage while satisfying the security requirements. This is accomplished by taking advantage of the communication pattern of wireless sensor networks and adopting heterogeneous wireless sensor networks. By considering the unique communication pattern of wireless sensor networks due to the nature of information gathering from the physical world, the number of keys to be established is minimized and, consequently, the overhead spent for establishing keys decreases. With heterogeneous wireless sensor networks, we can build a hybrid scheme where a small number of powerful nodes do more works than a large number of resource-constrained nodes to provide enhanced security service such as broadcast authentication and reduce the burden of resource-limited nodes. In addition, an on-demand key establishment scheme is introduced to support extra communications and optimize the resource usage. Our performance analysis shows that the proposed scheme is very efficient and highly scalable in terms of storage, communication and computation overhead. Furthermore, our proposed scheme not only satisfies the security requirements but also provides resilience to several attacks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1363-1376
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• 2020

An improved clustering scheme based on user group is proposed. Every two users are grouped among N-users in the allowed system according to their link gain from large to small. Each user group is numbered sequentially. Two user clusters are obtained according to the principle of maximizing link gain difference for the users in the first and last user groups. The remaining user groups are added to the two existing user clusters according to the parity of the group number. The clustering should be clustered again among the users in either user cluster if the throughput summation of a user cluster in NOMA is less than that of these users in orthogonal multiple access. The simulation results show that the proposed clustering scheme can increase the system throughput by about 8% compared with the hybrid clustering scheme when the number of users requiring service is 12.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1032-1037
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• 2016

In this paper, the method of isolation enhancement for the mobile phone MIMO antenna of LTE class 40(2300~2400MHz) was studied. Design of MIMO antenna was based on the hybrid antenna that operates both a monopole and an IFA(Inverted F Antenna). A structure for the isolation enhancement which controls induced electric field on the ground plane is located between MIMO antenna, and was not connected with the ground but apart 0.3mm. A MIMO antenna that operates on class 3~40(1710~2400MHz) of LTE service bands and a structure for the isolation enhancement at the class 10 band were designed. VSWR measurement of implemented antenna on the FR4 board showed within 3:1 at entire design bands, and isolation between antennas at the class 40 band was less than -30dB. Isolation was enhanced more than 20dB by the studied structure. ECC(Envelope Correlation Coefficient) for MIMO performance was under 0.1, and antenna average gain and efficiency measured in the anechoic chamber were -4.28~-1.40dBi and 37.32~72.36% respectively.

• Korean Journal of Adult Nursing
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• v.20 no.5
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• pp.707-718
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• 2008

Purpose: The present study was designed to understand the conceptual definition and attributes of the clinical critical thinking ability(CCTA) in nursing and to grasp the characteristics of clinical critical thinking abilities. Methods: The data were analyzed using the Hybrid model of Schwartz-Barcott and Kim(2000). Results: Having the skills and dispositions to think critically, CCTA refers to something that implies the cognizant ability to interpret contextual meanings, analyze the relationships between materials or circumstances, draw out the best conclusions, predict things using relevant information and evaluate the reliability of information and the strength of inference on the one hand and the emphatic disposition to be curious, open-minded, intellectually integral, systematic and creative and to reflect on things in contextual terms on the other. Conclusion: CCTA is characterized by clinical circumstances, such as guessing the reasons for facts, predicting things, connecting theory to practice and approaching individual situation in total terms as well as by the Korean circumstances, such as taking another person's perspective. Hence, this study proposes developing the tools to measure the clinical critical thinking ability and the strategies to improve the clinical critical thinking ability and seeking to verify their validity, on the basis of the findings.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.723-743
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• 2016

Indoor positioning is considered an enabler for a variety of applications, the demand for an indoor positioning service has also been accelerated. That is because that people spend most of their time indoor environment. Meanwhile, the smartphone integrated powerful camera is an efficient platform for navigation and positioning. However, for high accuracy indoor positioning by using a smartphone, there are two constraints that includes: (1) limited computational and memory resources of smartphone; (2) users' moving in large buildings. To address those issues, this paper uses the TC-OFDM for calculating the coarse positioning information includes horizontal and altitude information for assisting smartphone camera-based positioning. Moreover, a unified representation model of image features under variety of scenarios whose name is FAST-SURF is established for computing the fine location. Finally, an optimization marginalized particle filter is proposed for fusing the positioning information from TC-OFDM and images. The experimental result shows that the wide location detection accuracy is 0.823 m (1σ) at horizontal and 0.5 m at vertical. Comparing to the WiFi-based and ibeacon-based positioning methods, our method is powerful while being easy to be deployed and optimized.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.25 no.4
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• pp.109-128
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• 2014

A digital library could be understood as not a part of information cycling, but whole process of information production, circulation and reproduction. This study suggests that a digital library should be a creator as which it is publishing, circulating, and re-producing the information resources. Therefore, the role of intrinsic DRM (Digital Resources Management) can be interpreted as a digital library. Open access model have been already adopted to many university libraries, many university libraries are publishing free access online research resources by themselves. Also, research collection based on cloud computing can be extended to networked research collection and share with other university libraries. These evidences show future library can be the digital library with online and open accessible publishing function.