• Title/Summary/Keyword: power-space functions

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Study Tendency of Cyber Security in Power IT Area (전력 IT Cyber Security 연구 동향)

  • Kim, Hak-Man;Park, Jae-Sae;Kim, Sang-Nam
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.205-206
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    • 2008
  • Electrical Power System is very important infrastructure in the country. The functions of control, monitoring and so on in the electrical power system are implemented by information technologies(IT) through cyber space. Recently, many activities for enhancing cyber security in the world. In this paper, we introduce the study tendency of cyber security in power IT areas.

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Numerical Feasibility Study for a Spaceborne Cooler Dual-function Energy Harvesting System

  • Kwon, Seong-Cheol;Oh, Hyun-Ung
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.3
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    • pp.579-587
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    • 2017
  • Spaceborne cryocoolers produce undesirable micro-vibration disturbances during their on-orbit operation, which are a primary source of image-quality degradation for high-resolution observation satellites. Therefore, to comply with the strict mission requirement of high-quality image acquisition, micro-vibration disturbances induced by cooler operation have always been subjected to an isolation objective. However, in this study, we focused on the applicability of energy harvesting technology to generate electrical energy from micro-vibration energy of the cooler and investigated the feasibility of utilizing harvested energy as a power source to operate low-power-consumption devices such as micro-electromechanical system (MEMS) devices. A tuned mass damper (TMD)-type electromagnetic energy harvester combined with a conventional passive vibration isolator was proposed to achieve this objective. The system performs the dual functions of electrical energy generation and micro-vibration isolation. The effectiveness of the strategy was evaluated through numerical simulations.

Simple Space Vector PWM Scheme for 3-level NPC Inverters Including the Overmodulation Region

  • Lee, Dong-Myung;Jung, Jin-Woo;Kwa, Sang-Shin
    • Journal of Power Electronics
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    • v.11 no.5
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    • pp.688-696
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    • 2011
  • This paper proposes a simple space vector PWM (SVPWM) scheme including overmodulation operation for 3-level NPC (Neutral Point Clamped) Inverters. The proposed scheme features a simple decision and calculation procedure for determining switching times in the overmodulation range by utilizing the duty calculation method used in 2-level inverters and the minimum phase error projection method widely employed in motor drive systems. The proposed scheme does not need to detect the angle of the reference vector or calculate trigonometric functions to determine the magnitude of the voltage vector. The magnitude of the angle of the new reference voltage vector is decided in advance with the help of the Fourier Series Expansion to extend the linearity of the output voltage of 3-level inverters in the overmodulation region. Experimental results demonstrate the validity of the proposed SVPWM scheme including overmodulation operation for 3-level NPC inverters.

An In-depth Study on Applying Metric Weighting to Space Syntax (공간구문론에의 거리가중개념 적용에 관한 심층 연구)

  • Kim, Minseok;Piao, Gensong
    • Journal of the Architectural Institute of Korea Planning & Design
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    • v.34 no.12
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    • pp.49-54
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    • 2018
  • Applying metric(distance) factor as weighting to spatial syntax is known to not contribute to the explanatory power for the human movement behavior as compared to the geometric(angle) factor according to the negative results of several related studies. However, Kim & Piao (2017) assumed that there is not a problem of the metric factor itself but a problem of the way of applying the metric factor as weighting, and presented a new possibility of the metric factor as weighting by proposing and verifying the methods of applying the metric weighting, which are different from the existing ones. The purpose of this study is to propose advanced methods of applying the metric weighting to space syntax, and to verify whether they contribute to the improvement of explanatory power of space syntax analysis. In this paper, we propose functions for combined depth of distance-step that combine the distance-weighted depth function with the step depth function and apply them to axial segment analysis to check the improvement of explanatory power of them.

Information and Communication Technology and the Organization of Corporate Space (정보통신기술과 기업공간의 재조직)

  • 황주성
    • Journal of the Korean Regional Science Association
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    • v.12 no.2
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    • pp.99-116
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    • 1996
  • This study investigates the nature and patterns of interrelation between the emerging information and communication technology(ICT) and the organization of corporate space, both theoretically and empirically. In this work, ICT is conceptualized not so much a space-adjusting technology as an organizational technology. ICT is considered as a governance technology which is related to coordination function within a firm. Therefore, it is supposed to have a great relevance to the spatial reorganization of functions within a firm. Both questionnaire and case study method are used to gather necessary data from Korean electronics manufactures. The results of this study can be summarized as follow. First, the spatial structure of a firm, which is operationalised as the number and type of spatially separated establishments, is turned out to have a great explanatory power to its adoption of computer networks. Computer networks in muli-locational companies are introduced to overcome the limits of its spatial structure, such as duplication of functions, such as duplication of functions, loss of time spent in proceeding a job between different functional units, and unresponsiveness to the change of market demand. Second, new spatial division of labor and function could be possible through a series of business process reengineering, not through the mere adoption of ICT. Case studies reveal that computer network could help a firm to realize new forms of spatial division of labor, especially in those functions which is mainly based on the flow of information. Such function as ICT management, sales logistics and after-sales service are major parts where a new operational unit has appeared with the help of ICT. From above results, it can be concluded that the interrelations between ICT and organizational space should be approached intimately integrated with the change of industrial structure and it's organizational implications.

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FACTORIZATION IN KREIN SPACES

  • Yang, Mee-Hyea
    • Communications of the Korean Mathematical Society
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    • v.13 no.4
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    • pp.801-810
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    • 1998
  • Let A(z), W(z) and C(z) be power series with operator coefficients such that W(z) = A(z)C(z). Let D(A) and D(C) be the state spaces of unitary linear systems whose transfer functions are A(z) and C(z) respectively. Then there exists a Krein space D which is the state space of unitary linear system with transfer function W(z). And the element of D is of the form (f(z) + A(z)h(z), k(z) + C*(z)g(z)) where (f(z),g(z)) is in D(A) and (h(z),k(z)) is in D(C).

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Engineered Surface Characterization by Space Series Function (공간 계열 함수를 이용한 가공 표면의 특성 연구)

  • Hong, Minsung
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.12
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    • pp.120-128
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    • 1996
  • An attempt is made to characterize and synthesize engineered surfaces. The proposed method is not only an analytical tool to characterize but also to generate/synthesize three-dimensional surfaces. The developed method expresses important engineered surface characteristics such as the autocorrelation or power spectrum density functions in terms of the two-dimensional autoregressive coefficients.

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Model Independent Statistics in Cosmology

  • Keeley, Ryan E.;Shafieloo, Arman
    • The Bulletin of The Korean Astronomical Society
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    • v.45 no.1
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    • pp.49.1-49.1
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    • 2020
  • In this talk, I will discuss a few different techniques to reconstruct different cosmological functions, such as the primordial power spectrum and the expansion history. These model independent techniques are useful because they can discover surprising results in a way that nested modeling cannot. For instance, we can use the modified Richardson Lucy algorithm to reconstruct a novel primordial power spectra from the Planck data that can resolve the "Hubble tension". This novel primordial power spectrum has regular oscillatory features that would be difficult to find using parametric methods. Further, we can use Gaussian process regression to reconstruct the expansion history of the Universe from low-redshift distance datasets. We can also this technique to test if these datasets are consistent with one another, which essentially allows for this technique to serve as a systematics finder.

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Analyzing the Functional Spaces of Military Dining Facilities Using Analytic Hierarchy Process (AHP를 이용한 군 취사식당 기능공간 분석)

  • Lee, Seung-Hoo;Lee, Hyun-Soo;Park, Moonseo;Ji, Sae-Hyun
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.36 no.5
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    • pp.155-164
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    • 2020
  • This research used Analytic Hierarchy Process(AHP) to analyze the importance and priority of functional space and evaluation factors of each functional space of the military dining facility. Dining in the military is an important factor in restoring combat power and promoting morale. The military dining facility serves as a not only for meals, but also for watching TV, education and club activities. Workers working in dining facility spend most of their work hours in dining facility, perform tasks such as cooking, dishwashing, and leftover disposal, and take breaks. As such, the military dining facility is a space where various functions are performed, and space planning should take into account these various functions when planning the building of the dining facility. However, the criteria for defense and military facilities, which are the basis for planning the space of military dining facility, are calculated only by simply analyzing the standard floor plan to match the size of the person-to. Therefore, when there is space to be reduced in the total area, there are side effects such as leaving visible table space without consideration for priority or functional space, unseen office space, and adjusting the entire area through reduction of the lounge. Accordingly, based on the priority of the space that the staff of the military dining facility considers important, this research aims to analyze the characteristics of each functional space through classification according to its unique function. This can be an indicator that can be used as a basis for future revision of the building floor area standards of the defense and military facilities standards, and it can improve usability with an efficient space plan that takes into account the characteristics of the Korean military and the satisfaction of its workers. Furthermore, efficient use of the defense budget through rational building plans can contribute to budget reduction.

Mid-IR Luminosity Functions of Local Galaxies in the North Ecliptic Pole Field

  • Kim, Seong Jin;Lee, Hyung Mok;Jeong, Woong-Seob
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.1
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    • pp.72.3-72.3
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    • 2015
  • We present the mid-infrared (MIR) luminosity function (LF) of local (z < 0.3) star forming (SF) galaxies based on the AKARI's NEP-Wide Survey data. We utilized a combination of the NEP-Wide point source catalogue containing a large number (114,000) of infrared (IR) sources distributed over the wide (5.4 sq. deg) field and spectroscopic redshift (z) data for 1790 selected targets obtained by optical follow-up surveys with MMT/Hectospec and WIYN/Hydra. The AKARI's continuous $2{\sim}24{\mu}m$ wavelength coverage and the spectroscopic redshifts for sample galaxies enable us to derive accurate spectral energy distributions (SEDs) in the mid-infrared. We carried out SED-fit analysis and employed 1/Vmax method to derive the mid-IR (e.g., $8{\mu}m$, $12{\mu}m$, and $15{\mu}m$ rest-frame) luminosity functions. Our results for local galaxies from the NEP region generally consistent with various previous works for other fields over wide luminosity ranges. The comparison with the results of the NEP-Deep data implies the luminosity evolution from higher redshifts towards the present epoch. We attempted to fit our derived LFs to the double power-laws and present the resulting power indices. We also examined the correlation between mid-IR luminosity and total IR luminosity.

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