• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.48-55
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• 2006

Performance characteristics of the position-domain Hatch filter is analyzed for differential global navigation satellite systems. It is shown that the position-domain Hatch filter generates white measurement residual sequences, which is beneficial property for fault detection. It is also shown that the position-domain Hatch filter yields more accurate a priori state estimate than the position-domain Kalman-type filter. Thus, it can be concluded that the position-domain Hatch filter is beneficial in wide application areas where fault-tolerance and accuracy are required at the same time.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1563-1576
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• 2017

This paper presents a novel switching pattern current control (SP-CC) scheme, which is applied in three-phase voltage-source converters (VSCs). This scheme can select the optimal output switching pattern (SP) by referring the basic principle of space vector modulation (SVM). Moreover, SP-CC is a method without a carrier wave. Thus, the implementation process is concise and easy. When compared with the conventional hysteresis current control (C-HCC) and the space vector-based hysteresis current control (SV-HCC), the SP-CC has the performances of faster dynamic response of C-HCC and less switching number (SN) of SV-HCC. In addition, it has less harmonic contents in the three-phase current, along with a lower switching loss and a higher efficiency. Moreover, the hysteresis bandwidth and Clarke conversion are not required in the SP-CC. The effectiveness of the presented SP-CC is verified by simulation and experimental test results. In addition, the advantages of the SP-CC, when compared with the C-HCC and SV-HCC, are verified as well.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.272-276
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• 2015

The PbS quantum dot is an emerging photovoltaic material, which may provide high efficiency breakthroughs. The most crucial element for the high efficiency solar cells's development is to understand charge transport characteristics of PbS quantum dot solids, which are also important in planning strategic research. We have investigated charge transport characteristics of PbS quantum dot solids thin films using space charge limited conduction analysis and assessed thickness dependent photovoltaic performances. The extracted carrier drift mobility was $low-10^{-2}cm^2/Vs$ with the estimated diffusion length about 50 nm. These and recently reported values were compared with those from a commercial photovoltaic material, and we present an essential element in further development of PbS quantum dot solids materials.

• Journal of Korea Multimedia Society
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• v.25 no.10
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• pp.1499-1511
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• 2022

In the context of globalization, circulation between cities has become more frequent. The airport is no longer just a place for boarding, disembarking, and transportation, but a public place that serves as the communication function of the "aviation city". The intervention of public art in the airport space not only gives users a sense of space experience, but also becomes a unique carrier for city and country image shaping. The purpose of this paper is to study the emotional value brought by airport public art to users, and to investigate the correlation analysis of public art design elements and user preferences based on this premise. The research methods are machine learning method and SPSS 21.0. The user's emotional value is introduced in the big data evaluation, and the preference and inclination of airport users to various elements of public art are analyzed by questionnaire. Through the research conclusion, the preference and main contradiction of users in the airport for the four dimensions of public art design elements are obtained. Opinions and optimization methods to provide reference data and theoretical support for public art design.

• MALSORI
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• no.62
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• pp.1-17
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• 2007

The purpose of this study was to investigate and quantitatively describe the acoustic characteristics of current Korean monophthongs. Recordings were made of 33 men and 27 women producing the vowels /i, e, ${\epsilon}$, a, ${\partial}$, o, u, i/ in a carrier phrase "This character is ___." A listening test was conducted in which 19 participants judged each vowel. F1, F2, and F3 were measured from the vowels judged as intended vowels by more than 17 people from the listening test. Analysis of formant data shows some interesting results including the undeniable confirmation of the 7-vowel system in modern Korean. It turns out that quite different sounding Korean vowels and English vowels happen to have very similar formant measurements. Also the difference between "citation-form reading" vs. "natural utterance reading" is discussed.

• ETRI Journal
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• v.27 no.3
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• pp.257-266
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• 2005

Many multi-modulus blind equalization algorithms (MMA) have been presented in the past to overcome the undesirable high misadjustment exhibited by the well-known constant modulus algorithm. Some of these MMA schemes, specifically tailored for quadrature amplitude modulation (QAM) constellations, have also been proved to fix the phase offset error without needing any rotator at the end of the equalizer stage. In this paper, a new multi-modulus algorithm is presented for QAM signals. The contribution lies in the technique to incorporate the sliced symbols (outcomes of decision device) in the multi-modulus-based weight adaptation process. The convergence characteristics of the proposed sliced multi-modulus algorithm (S-MMA) is demonstrated by way of simulations, and it is shown that it gives better steady-state performance in terms of residual inter-symbol interference and symbol-error rate. It has also been shown that the proposed algorithm exhibits lesser steady-state misadjustment compared to the best reported MMA.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.3-6
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• 2004

This paper. we investigate the OFDM-based wireless LAN systems operating in the 60 GHz frequency band as part of the fourth-generation (4G) systems. The 60 GHz band is of much interest since this is the band in which a massive amount of spectral space (5 GHz) has been allocated worldwide for dense wireless local communications. This paper gives an overview of 60 GHz indoor wireless channel characteristics and an effect on phase noise. The performance of OFDM system is severely degraded by the local oscillator phase noise, which causes both common phase error and inter-carrier interference. We provide the exact analysis of the phase noise effect on the OFDM system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.3
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• pp.60-65
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• 1984

In this paper, we have used symmetrical GaAs/(Ga, Al) As DH-LED as a model for the optimization of frequency response which is the most important design parameter of the optical communication-LED. And optimum design parameters have been chosen to improve performance factors of the DH-LED by computer simulation. This is for the purpose of systematic consideration of the interrelation of the physical parameters such as impurity concentration of the active layer, thickness of the active layer, minority carrier lifetime, space charge capacitance and injected current density.

• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1612-1621
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• 2007

In this paper, we introduced our designed TDMA (Time Division Multiple Access) based MAC (Medium Access Control) protocol for Home Networks called HomeTDMA. We have implemented and tested it in a test bed using crossbow motes and TinyOS. We also have compared HomeTDMA and CSMA (Carrier Sense Multiple Access) in terms of space and time complexity, channel access time, delivery success ratio, and throughput. Based on our results, HomeTDMA has an advantage over CSMA on channel access time, throughput and delivery success ratioIn the case of complexity, HomeTDMA is more complex compared to CSMA. Thus, CSMA is more appropriate in wireless sensor networks (WSNs) where memory, energy, and throughput are important parameters to be considered. However, HomeTDMA has a natural advantage of collision free medium access and is very promising for home networks where a reliable transmission or data transfer and congestion control is highly preferred.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.11a
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• pp.165-169
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• 2006

Here this Study is purposed Importance of an arcade in Mixed - Use Building. Because Mixed - Use Building ha)'e problem In korea. So Solution the Community of Mixed - Use Building a Housing development. An Acade of Mixed-use Building have a good point that is carrier Space. The Process of this Study 1) A study on the Mixed-Use Building Form and a user form in theory. 2) Condolence about Mixed-used Building of three type in kyungki and seoul ( Lotte Castle In Jamsil Seoul, park view In SungNam kyungki, Dong- Yang Paragon in SungNam kyungki) 3) analysis by theory of Mixed-Use Building Form and a user form about Mixed-Use Building 4) As a result of as being Comparison three building develop.