• 천문학회보
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• 제38권1호
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• pp.67.2-67.2
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• 2013

The GMT project is in its final stage of Design Development Phase in 2013, moving toward the Construction Phase planned to begin on Jan. 1st, 2014. In this contribution, we present the current status and progress of the GMT project including selection of the first generation instruments, development of primary mirror segments, site preparation, and science case revision along with plans for 2013 when the preparation of construction phase will be made.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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• pp.303-311
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• 2012

An innovative interpretation of the per-unit interior permanent magnet (IPM) machine model known as Design Space is presented in this paper. Based on the proposed Design Space formulation, an effective computation method to predict IPM machine performance factors, such as the current and power factor in a full range of speeds, is proposed. A systematic methodology is summarized, which translates the full speed range machine design procedure into the region determination on the so-called Design Space. The effect of dc-link voltage is also analyzed in a similar manner with the current and power factor. A series of IPM motors have been designed, and a preferred motor is selected with the help of the proposed Design Space Methodology (DSM), which has the best tradeoff between the nominal voltage and the dropped voltage condition. Experiment results show that the selected motor satisfies the machine requirements and all the design constrains, such as the current and back-EMF limitations.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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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 Astronomy and Space Sciences
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• 제29권4호
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• pp.329-336
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• 2012

Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Bohyunsan Observatory to measure the Earth's magnetic field variations in South Korea. In 2007, we installed a fluxgate magnetometer (RFP-523C) to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we use the H, D, Z components of fluxgate magnetometer data to investigate the characteristics of mid-latitude geomagnetic field variation. To remove the temporary changes in Earth's geomagnetic filed by space weather, we use the international quiet days' data only. In other words, we performed a superposed epoch analysis using five days per each month during 2008-2011. We find that daily variations of H, D, and Z shows similar tendency compared to previous results using all days. That is, H, D, Z all three components' quiet intervals terminate near the sunrise and shows maximum 2-3 hours after the culmination and the quiet interval start from near the sunset. Seasonal variations show similar dependences to the Sun. As it becomes hot season, the geomagnetic field variation's amplitude becomes large and the quiet interval becomes shortened. It is well-known that these variations are effects of Sq current system in the Earth's atmosphere. We confirm that the typical mid-latitude geomagnetic field variations due to the Sq current system by excluding all possible association with the space weather.

• 천문학회보
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• 제37권2호
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• pp.117.1-117.1
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• 2012

Energetic neutral atoms (ENAs) are emitted by charge exchange collisions between energetic ions and cold neutral atoms. ENAs can be used as an alternative measure of the energetic ions in the source region because they maintain the energy and pitch angle of the source energetic ions. In the present study we present simulation results of the ENA emissions during a magnetic storm to be measured by the STEIN instrument onboard the CINEMA/TRIO satellites. The CINEMA/TRIO mission consists of three identical cubesats with low-altitude orbits. The STEIN instrument onboard each cubesat can measure ENAs with energies from ~4 keV to ~20 keV as well as suprathermal electrons and ions. The measurement of ENA emissions from ring current by STEIN is simulated using the models for energetic ring current ions and geocoronal neutral atoms. Especially we will discuss about the energy spectrum of the ENAs and the effect of transient variations of the ring current.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2006년도 추계학술발표대회 논문집
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• pp.109-114
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• 2006

The world has become one united world so that it is worthless to divide it into two; the East and West. In the 20th century, eastern perspectives proliferated in western science involving theology, philosophy and psychotherapy. In this time of various trends of ideas emerged minimalism, artistic and cultural current seeking simplicity and conciseness. This current of idea appeared about the time of World War II in visual art, and then expanded to other fields like music, architecture, fashion and philosophy in diverse forms. Minimalism is also presented in interior space with extreme form of simplicity and detail, revealing parts of the space as delicate and pure style with emphasis on purity of the space itself. In this research, demonstrate clear features of eastern view of space appeared in minimalism of interior design mainly in America. The reason the scope of study is limited to America is that America is the origin of minimal art and has been hub of modern design since the 1930s. The research, first, finds out the origin and conceptual idea of minimalism and features of eastern view of space. Based on this understanding, further study has been carried to discover relation of minimalistic interior space to eastern view of space and to analyze eastern characteristic expressed in minimalistic space by examination of cases pertaining to commercial space.

• 토지주택연구
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• 제11권2호
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• pp.47-57
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• 2020

In this study, we aimed to identify the latest trends of landscape in apartment complexes by identifying how landscaping spaces are being created and what their characteristics are. Furthermore, we aimed to find out what type of garden is being constructed in the landscaping space and what the difference between the landscaping space and the garden space is, and to define the future direction of landscape for apartment complexes. The following results were our findings. First, we identified that landscaping space is divided into general landscaping space and garden space. The garden space has designated area within the whole apartment complex as a garden and there is a variety of garden themes and plants, facilities, packaging patterns, and sculptures are used accordingly. On the other hands general landscaping space features uniform patterns of packaging and simple planting patterns. Our finding is that the current trend is to set up separate garden space within the landscaping space of apartment complexes. Although gardens are often regarded as personal property and spaces that need to be cultivated or managed, and spaces that are limited to fences are defined as gardens, the current landscaping space of apartments is creating gardens-like spaces within public spaces.

• 시스템엔지니어링워크숍
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• 통권4호
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• pp.90-94
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• 2004

System engineering(SE) management techniques applied for space launch system development are introduced to assess the current status and address the effwctiveness of these techniques. Management plans and guides are prepared for the work breakdown structure , data, comfiguration, interface control, Quality assurance, procurement, reliability, risk and verification/validation . Further improvement is required for the system engineering management plan(SEMP) to merge the international cooperation into current engineering managment system.

• 천문학회보
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• 제36권2호
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• pp.100.2-100.2
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• 2011

The dynamical evolution of the Earth's magnetosphere loaded with a transiently enhanced ring current is studied by numerical magnetohydrodynamic (MHD) simulation. Two cases with different values of the primitive ring current are considered. In one case, the initial ring current is strong enough to create a magnetic island in the magnetosphere. The magnetic island readily reconnects with the earth-connected ambient field and is destroyed as the system approaches a steady equilibrium. In the other case, the initial ring current is not so strong, and the initial magnetic field configuration bears no magnetic island, but a wake of bent field lines, which is smoothed out through the relaxing evolution of the magnetosphere. The relaxation time of the magnetosphere is found to be about five to six minutes, over which the ring current is reduced to about a quarter of its initial value. Before reaching a steady state, the magnetosphere is found to undergo an overshooting expansion and a subsequent contraction. Fast and slow magnetosonic waves are identified to play an important role in the relaxation toward equilibrium.

• Journal of Power Electronics
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• 제16권6호
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• pp.2258-2271
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• 2016

In this paper, some crucial performance characteristics related to the operational reliability of the post-fault Pulse Width Modulated (PWM) rectifiers, such as line current harmonic distortion, Common Mode Voltage (CMV), and current stress on the capacitors, are fully investigated. The aforementioned performance characteristics of post-fault rectifiers are highly dependent on the utilized space vector modulation (SVM) schemes, which are also examined. Detailed analyses of the three most commonly used SVM schemes for post-fault PWM rectifiers are provided, revealing the major differences in terms of the zero vector synthesis approaches. To compare the performances of the three SVM schemes, the operating principles of a post-fault rectifier are presented with various SVM schemes. Using analytical and numerical methods in the time domain, the performances of the line current distortion, common mode voltage and capacitor current are evaluated and compared for each SVM scheme. The proposed analysis demonstrates that the zero vector synthesis approaches of the considered methods have significant impacts on the performance characteristics of rectifiers. In addition, the advantages and disadvantages of the proposed SVM schemes are discussed. The experimental results verify the effectiveness and validity of the proposed analysis.