• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.266-273
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• 2012

In conventional direct torque control (DTC) using space-vector modulation (SVM) of induction machine (IM) drives, at least three current sensors are needed. In this paper, a low-cost SVM-DTC strategy is proposed, in which only a single current sensor is used. The position of the voltage space vector is divided into two areas: effective and non-effective area. If it is located in the non-effective area, the voltage space vector will be shifted into the effective area with minimum distortion. Further, the switching frequency remains constant. The simulation is carried out on a MATLAB/Simulink platform and the simulated results verify the effectiveness of the proposed strategy.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.4
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• pp.131-141
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• 2014

Over the last decade, the Global Navigation Satellite System (GNSS) has been increasingly utilized as a meteorological research tool. The Korea Astronomy and Space Science Institute (KASI) has also been developing a near real-time GNSS precipitable water vapor (PWV) information management system that can produce a precise PWV for the Korean Peninsula region using GNSS data processing and meteorological measurements. The goal of this paper is to evaluate whether the precise point positioning (PPP) strategy will be used as the new data processing strategy of the GNSS-PWV information management system. For this purpose, quality assessment has been performed by means of a comparative analysis of the troposphere zenith total delay (ZTD) estimates from KASI PPP solutions (KPS), KASI network solutions (KNS), and International GNSS Service (IGS) final troposphere products (IFTP) for ten permanent GNSS stations in the Korean Peninsula. The assessment consists largely of two steps: First, the troposphere ZTD of the KNS are compared to those of the IFTP for only DAEJ and SUWN, in which the IFTP are used as the reference. Second, the KPS are compared to the KNS for all ten GNSS stations. In this step, the KNS are used as a new reference rather than the IFTP, because it was proved in the previous step that the KNS can be a suitable reference. As a result, it was found that the ZTD values from both the KPS and the KNS followed the same overall pattern, with an RMS of 5.36 mm. When the average RMS was converted into an error of GNSS-PWV by considering the typical ratio of zenith wet delay and PWV, the GNSS-PWV error met the requirement for PWV accuracy in this application. Therefore, the PPP strategy can be used as a new data processing strategy in the near real-time GNSS-PWV information management system.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.29 no.3
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• pp.339-359
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• 2018

The purpose of this study is to suggest a strategy of introduction of Larchiveum, which is a concept of multi cultural space in libraries. Problem of library space programs are discussed in terms of Larchiveum and Maker space, and recently it has been studied in various aspects such as Europeana, GLAM and DPLA from the view point of digital Larchiveum. As a multi cultural space, it is a strategy for constructing Larchiveum that reflects the recent maker's movement. Maker space that explores new ideas and encourages active participation of users, nature and health, curiosity and the construction of an attractive space using ecological concepts as key words. The processes and methods for constructing Larchiveum are classified into 3 types of space configuration, service, program, and operating regulation, and twelve details are laid out to derive the process and method of building Larchiveum as a future type library.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.72-86
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• 2019

SpaceX is currently leading the global launch market with the successful launch and recovery of Falcon 9 v1.2 Block 5. SpaceX developed Merlin engine, a kerosene gas generator engine, and continuously upgraded the engine from Falcon 1 to Falcon Heavy to increase payload weight. SpaceX suffered a lot of failures early on, but with the help of NASA, it was possible to overcome many crises and develop vehicles. In addition, it successfully developed reusable vehicles, which drastically reduced operating costs. Subsequent launch vehicles in Korea also need to be developed with reference to SpaceX's development strategy.

• Journal of Aerospace System Engineering
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• v.9 no.2
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• pp.47-50
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• 2015

MSIP(Ministry of Science, ICT and Future Plaaning) established the 'space technology commercialization plan' at 2012. According to this plan, MSIP and KARI(Korea Aerospace Research Institute) are nuturing space-related venture companies so that those companies are increasing from 2013. In addition, MSIP and KARI held space-related idea festivals last two years, and will run start-up program (STAR-Exploration) this year.

• Journal of Aerospace System Engineering
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• v.10 no.3
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• pp.32-38
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• 2016

This paper explains space-technology startup-business support programs. MSIP (Ministry of Science, ICT and Future Planning) and KARI (Korea Aerospace Research Institute) began running startup-business support programs from 2013 according to a "space-technology industrialization plan." In addition, MSIP and KARI have been running startup academies and STAR-Exploration for future entrepreneurs and startup companies since 2015. From these programs, five startup companies were established and they are generating sales. This paper shows the results of the programs, and the program cases of the startup and venture companies are analyzed for both domestic and international audiences. The future direction of startup-business support programs that are based on space technology is also discussed.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.2
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• pp.39-44
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• 2004

The city environment construction of China is facing many difficulties and challenges. Through the concerted exploration in the recent years to find the way of improving city environment that is suitable to Chinese situation, the result is to plan and construct a complete green space system, supplement the defective conditions by the system's superiority and produce the integrated effectiveness. The article dissertates on the composition of green space system, some important issues in the planning and construction and corresponding measures. The fact illustrates the effectiveness of city green space system in solving the city environment problems. However it needs some research and continues improving.

• Journal of Astronomy and Space Sciences
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• v.36 no.4
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• pp.235-248
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• 2019

This paper suggests a relative orbit control strategy for the CubeSat Astronomy by NASA and Yonsei using Virtual Telescope Alignment eXperiment (CANYVAL-X) mission whose main goal is to demonstrate an essential technique, which is an arrangement among two satellites and a specific celestial object, referred to as inertial alignment, for a next-generation virtual space telescope. The inertial alignment system is a relative orbit control system and has requirements for the relative state. Through the proposed orbit control strategy, consisting of separation, proximity keeping, and reconfiguration, the requirements will be satisfied. The separation direction of the two CubeSats with respect to the orbital plane is decided to provide advantageous initial condition to the orbit controller. Proximity keeping is accomplished by differential atmospheric drag control (DADC), which generates acceleration by changing the spacecraft's effective cross section via attitude control rather than consuming propellant. Reconfiguration is performed to meet the requirements after proximity keeping. Numerical simulations show that the requirements can be satisfied by the relative orbit control strategy. Furthermore, through numerical simulations, it is demonstrated that the inertial alignment can be achieved. A beacon signal had been received for several months after the launch; however, we have lost the signal at present.

• Journal of Korea Port Economic Association
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• v.21 no.3
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• pp.115-148
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• 2005

In the liner market, a strategy is hard to sustain as competitors can easily imitate the strategy. For examples, when a number of shipping companies pursue this space exchange strategy in a liner market, their competitors are likely to build a cooperative alliance, following similar strategic pattern without any difficulty. Such strategic imitations are universal in international liner market. Therefore, the success of global alliance requires following critical considerations. First, the strategy of global alliance should be designed the way it gives the liner operators an economy of scale, which could be a key advantage in the competitive market. Second, thorough global alliance the lines should be able to improve their transport service through the reduction of operating costs and the business rationalization. The international alliance today is characterized by a strategic cooperation among a limited number of 'mega-carriers'. Such cooperation between the large-sized operators has come in many different forms. However, the trend has been towards the space exchange agreement, where a carrier on a route offers to another carrier a fixed number of spaces for a fixed period of time. the major carriers have been entered into groupings by integrating their services structures to increase market power. With reference to the above, this study has the following primary objectives: (1) to explore the present status of global alliance in liner shipping industry, (2) to prospect the future trend of the global alliance.

• Korean Institute of Interior Design Journal
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• v.13 no.3
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• pp.145-152
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• 2004

The European architects including MVRDV, Rem Koolhaas, Van Berkel, and Zaha Hadid tend to use the their own design strategy based on the objective data. This Architectural design method leads to make new paradigm of contemporary architecture. For the purpose of the understanding a part of new architecture paradigm I will analyze the case of Villa VPRO designed by MVRDV. At the result, I can draw the following conclusions. First, through collecting and analyzing data, drawing design concept and planning the space program, they decided on the design strategies of Villa VPRO. They designed the space volume having 42.4m$\times$42.4m floors and infiltrated environmental elements to solve the problems about deep space. Second, Villa VPRO was constructed by 'creative space-making system: a series of floors much like a geological formation, the continuous floors interconnected by spatial means, the precision bombardments of snake-like holes, open elevations, the stacking spaces. Third, Villa VPRO produced the spectacle space effect the various formation of continuous floors make a lot of difference space types in this building. Also they lead to move naturally and give event space. A numbers of holes and openness make it possible to provide friendly environment with combining light and air with views of the surrounding and transparency. And using the method of stacking many types of space make the differences in height.