• Electronics and Telecommunications Trends
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• v.37 no.3
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• pp.1-10
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• 2022

Traditional centralized radio access network architecture used for 4G is based on Option 8, a functional split between PHY and RF. This option is commonly used with a fronthaul interface based on common public radio interface (CPRI) specifications; however, the increased data rates in 5G make this option impractical because of the fronthaul interface's high bandwidth requirement. Since CPRI specifications have many vendor-specific options, achieving multi-vendor interoperability becomes challenging. Open RAN (O-RAN) Alliance is developing novel open fronthaul interface specifications based on the functional split Option 7-2x, one of the intra-PHY split options, to relax the bandwidth requirement of the fronthaul interface and achieve multi-vendor interoperability. This article provides a brief overview of the various functional split options for 5G fronthaul that have been reported so far and existing fronthaul technologies. Further, the technological trends in the 5G open fronthaul interface is discussed, focusing on the O-RAN Alliance specifications under standardization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4451-4466
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• 2014

We present joint radio selection and relay scheme that delivers data from a source to a sink in heterogeneous stationary sensor networks consisting of various radio interfaces. The proposed scheme finds the optimal relay nodes and their corresponding radio interfaces that minimize energy consumption throughout the network while satisfying the end-to-end packet deadline requirement. We formulate the problem of routing through radio interface selection into binary integer programs, and obtain the optimal solution by solving with an optimization solver. We examine a trade-off relationship between energy consumption and packet delay based on network level simulations. We show that given the end-to-end deadline requirement, our routing algorithm finds the most energy-efficient routing path and radio interface across mesh hops. We demonstrate that the proposed routing scheme exploits the given packet delivery time to turn into network benefit of reducing energy consumption compared to routing based on single radio interface.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.5
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• pp.314-321
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• 2021

In the existing whole ship analysis, topside was modeled as mass element. However recently, the topside is modeled as beam element due to the owner's requirement to improve the maturity of the whole ship FE model. To follow the owner'srequirement, detailed information for topside drawing and modeling, which may delay analysis schedule, is needed. However, it is hard to respond effectively to this matter due to the lack of study on the topside from the hull perspective. Therefore in this study, the effect of the topside on the hull is investigated when the topside is modeled as a mass element or beam element respectively. In addition, the interface modeling method is analyzed to verify modeling method used in the existing whole ship analysis. The results indicate that the interface and topside modeling method used in existing whole ship analysis are appropriate. This conclusion will be the technical basis for responding to owner's requirement about the topside modeling method.

• Journal of Aerospace System Engineering
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• v.15 no.4
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• pp.57-63
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• 2021

The launch vehicle (LV) separation detection interface of the satellite, which is designed to initiate the launch and early operation phase (LEOP) for S-band data transmission and the solar array deployment after the LV separation, is one of the hazard items at the launch site. Therefore, this interface should satisfy the single-fault tolerance requirement for the range safety. In this paper, we discuss the LV separation detection interfaces for two different satellite launch configurations and propose a method to guarantee for the satellite to start the LEOP even under the emergency case such as a partial separation from the LV. Furthermore, the proposed method meets the range safety requirement of the launch site. As this method only changes the external harness configuration of the satellite, it increases the reliability of the satellite early operation without any modification of the existing internal logics to detect the separation event.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.3
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• pp.401-408
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• 2016

During daylight, the solar array of low earth orbit satellites harvests electrical power to operate satellites. The power conversion of the solar array is carried out by control of the operation point using the solar array regulator when the solar array faces the sunlight. Thus, the design of the solar array should comply with not only the power requirement of satellite system but also the input voltage requirement of the solar array regulator. In this paper, the design requirements of the solar array for low earth orbit satellites are defined, and the means of satisfying these requirements are described. In addition, the architecture of a multi-distributed interface is suggested to maximize the power harvested from a solar array having high temperature deviation between each panel. The power analysis in this paper shows the optimal number of multi-distributed interfaces with a converter.

• The Bulletin of The Korean Astronomical Society
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• v.34 no.1
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• pp.162.2-162.2
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• 2009

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.310-316
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• 2008

This theory focuses on the Enterprise Portal and researches and analyzes the user requirement on as-is system. The UI Checklist Matrix is made based on the result of user analysis and evaluation of checklist. The horizontal axis of the Matrix is composed of 6 results(Layout, Navigation, Information, Function, Visibility and Interaction) of user requirement analysis. The vertical axis of the Matrix is composed of 10 subjects, Learnability, Efficiency, Accuracy, Accessibility, Consistency, Agility, Convergence, Personalization, Technology, and Standardization. At the point of vertical and horizontal items meet, indicates the graded of importance and defines a details item. The Guideline in which Matrix is reflected is set and according to the guideline, designing the business screen and assessing the Matrix.

• Korean Journal of Computational Design and Engineering
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• v.8 no.4
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• pp.231-242
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• 2003

Multidisciplinary Design Optimization (MDO) is an optimization technique considering simultaneously multiple disciplines such as dynamics, mechanics, structural analysis, thermal and fluid analysis and electromagnetic analysis. A software system enabling multidisciplinary design optimization is called MDO framework. An MDO framework provides an integrated and automated design environment that increases product quality and reliability, and decreases design cycle time and cost. The MDO framework also works as a common collaborative workspace for design experts on multiple disciplines. In this paper, we present the architecture for an MDO framework along with the requirement analysis for the framework. The requirement analysis has been performed through interviews of design experts in industry and thus we claim that it reflects the real needs in industry. The requirements include integrated design environment, friendly user interface, highly extensible open architecture, distributed design environment, application program interface, and efficient data management to handle massive design data. The resultant MDO framework is datasever-oriented and designed around a centralized data server for extensible and effective data exchange in a distributed design environment among multiple design tools and software.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.7
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• pp.309-316
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• 2005

In this paper we analyzed a dangerous failure and a safety requirement based on HIA (Hazard Identification and Analysis) of an interface model between CTC (Centralized Traffic Control) system and El (Interlocking) system, and assigned SU (Safety Integrity Level) by way of an risk estimation of the interface, which employed PHA (Preliminary Hazard Analysis) for the interface of the track control system, being managed as separated system between the centralized traffic control system and the interlocking system, An estimation which satisfies a safety reference of the international standard has been achieved through a quantification of the system failure rate and the dangerous failure rate of the interface model.

• Journal of the Korean Society for Railway
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• v.8 no.2
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• pp.161-169
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• 2005

In this paper, we provide safety requirements and advices to guarantee the safety of an interface in a level crossing system which is an interface between the conventional facilities and the new ATP (Automatic Train Protection) system, as well as we accomplish a safety management for the facilities of a country that has a different standard with already standardized ATP system. The system model has been made based on a safety activity of the international standard, and then a tolerance of a risk by the safety activity through PHA (Preliminary Hazard Analysis) has been analyzed. finally we achieved HIA (Hazard Identification and Analysis) for the assumptions that have been produced from a operating scenario and a functional interface. Thus, the safety requirements for the interface has been provided from the safety plan of HIA, and we showed the safety activity to guarantee the system safety through HIA which was depend on the design.