• Korean Institute of Interior Design Journal
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• v.20 no.6
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• pp.153-160
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• 2011

Some problems facing the cities in modern times begin to be highlighted due to the development into the information-oriented society via the stage of industralization. The structures built centering on the second industries have become superannuated to degenerate as horrid objects while losing their purposefulness with the emergence of the information age. In designing a hotel space where people stay temporarily unlike the housing space for a permanent stay, housing designers are making efforts to work on space design that could be more imprinted in the mind of the users. As the fruit of their sheer labor, the space design in modern hotel design comes to direct a diversity of atmospheres by virtue of various art genres which try to apply it to a space by borrowing it and changing its appearance. Thus, this study aims to look into how the gradually evolving conversion design hotel come to be recreated as an urban regeneration space while retaining the value of the space used in the past, and to analyze & systematize its subsequent design patterns applied to conversion design hotel space with focus on the recent cases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.5116-5131
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• 2017

This paper studies the radio frequency to direct current (RF-DC) conversion efficiency of rectennas applicable to wireless power transfer systems, where multiple receive antennas are arranged in serial, parallel or cascaded form. To begin with, a 2.45 GHz dual-diode rectifier is designed and its equivalent linear model is applied to analyze its output voltage and current. Then, using Advanced Design System (ADS), it is shown that the rectifying efficiency is as large as 66.2% in case the input power is 15.4 dBm. On the other hand, to boost the DC output, three composite rectennas are designed by inter-connecting two dual-diode rectifiers in serial, parallel and cascade forms; and their output voltage and current are investigated using their respective equivalent linear models. Simulation and experimental results demonstrate that all composite rectennas have almost the same RF-DC conversion efficiency as the dual-diode rectifier, yet the output of voltage or current can be significantly increased; in particular, the cascade rectenna obtains the highest rectifying efficiency.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.254-256
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• 2007

The Solar energy is either used as a solar thermal energy or converted to electrical power through power conversion system. The latter method is defined as a solar cell changing the solar energy into the direct electric energy or power conversion that convert the dc power into ac power.For the solar cell to be a practical alternative energy, the study should be focused not only on the solar cell ,but also the power conversion system for common power source. In this study, we get the suitable power to common load ,using Ag Grid DSC(Dye-sensitized solar cell). Our purpose is to achieve the common solar cell power generation system ,using converter and PWM(Pulse width modulation) inverter system controled by DSP.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.778-783
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• 2016

We synthesized $Er^{3+}-Yb^{3+}$, $Pr^{3+}-Yb^{3+}$, and $Er^{3+}-Pr^{3+}-Yb^{3+}$ -doped oxyfluoride glass ceramics containing $CaF_2$ nanocrystals by proper thermal treatments. Spectral characteristics of down- and up-converted emissions in three kinds of glass ceramics under 365-nm and 980-nm excitations were compared and explained by cross relaxations, excited-state absorptions, and energy-transfer processes between different ions. The huge reduction of up-conversion emission in the triply doped glass ceramics under 980-nm excitation compared to the $Er^{3+}-Yb^{3+}$ codoped one was explained by the split pump power and the direct energy transfer from $Er^{3+}$ to $Pr^{3+}$ ions. Increasing $Yb^{3+}$ concentration from 2% to 10% in the triply doped glass ceramics showed more than quadratic enhancement of the absorbed power, and we explained it by the enhanced energy-transfer efficiency from $Yb^{3+}$ to $Er^{3+}$ ions. We also observed enhanced up-converted emissions of $Er^{3+}$ and $Pr^{3+}$ ions in three kinds of glass ceramics under simultaneous excitation at 980 nm and 1550 nm, and suggested detailed up-conversion mechanisms.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.4
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• pp.293-299
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• 2004

An active RC 2nd order Butterworth filter suitable for a baseband channel-selection filter of a direct conversion receiver is presented. The linearity of the 2nd order Butterworth filter is analyzed. In order to improve the linearity of the filter, the operational amplifiers should have a high linear gain and low 3rd harmonic, and the filter should be designed to have large feedback factor. This second order Butterworth filter achieves-14dBV in-channel (400kHz, 500kHz) IIP3, +29dBV out-channel (10MHz, 20.2MHz) IIP3 and 15.6 $nV/\sqrt{Hz}$ input-referred noise and dissipates 10.8mW from a 2.7-V supply. The analysis and experimental results are in good agreement

• ETRI Journal
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• v.30 no.1
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• pp.33-46
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• 2008

This paper presents the experimental results of a low-power low-cost RF transceiver for the 915 MHz band IEEE 802.15.4b standard. Low power and low cost are achieved by optimizing the transceiver architecture and circuit design techniques. The proposed transceiver shares the analog baseband section for both receive and transmit modes to reduce the silicon area. The RF transceiver consumes 11.2 mA in receive mode and 22.5 mA in transmit mode under a supply voltage of 1.8 V, in which 5 mA of quadrature voltage controlled oscillator is included. The proposed transceiver is implemented in a 0.18 ${\mu}m$ CMOS process and occupies 10 $mm^2$ of silicon area.

• IMMUNE NETWORK
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• v.2 no.2
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• pp.79-85
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• 2002

Background: In contrast to evidences of Ig H chain receptor editing in transformed cell lines and transgenic mouse models, there has been no direct evidence that this phenomenon occurs in human developing B cells. Methods: $V_HDJ_H$ rearrangements were obtained from genomic DNA of individual $IgM^-$ B cells from liver and $IgM^+B$ cells from bone marrow of 18 wk of gestation human fetus by PCR amplification and direct sequencing. Results: We found three examples of H chain receptor editing from $IgM^+$ and $IgM^-human$ fetal B cells. Two types of $V_H$ replacements were identified. The first involved $V_H$ hybrid formation, in which part of a $V_H$ gene from the initial VDJ rearrangement is replaced by part of an upstream $V_H$ gene at the site of cryptic RSS. The second involved a gene conversion like replacement of CDR2, in which another $V_H$ gene donated a portion of its CDR2 sequence to the initial VDJ rearrangement. Conclusion: These data provide evidence of receptor editing at the H chain loci in developing human B cells, and also the first evidence of a gene conversion event in human Ig genes.

• Journal of Power Electronics
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• v.11 no.2
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• pp.148-155
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• 2011

Direct torque control(DTC) of induction machines is known to offer fast instantaneous torque and flux control with a simple control structure. However, this scheme has two major disadvantageous, namely, a variable inverter switching frequency and a high torque ripple. These problems occur due to the use of hysteresis comparators in conventional DTC schemes, particularly in controlling the output torque. This paper reviews the utilization of constant frequency torque controllers (CFTC) in DTC to solve these problems while retaining the simple control structure of DTC. Some extensions of the work in utilizing a CFTC will be carried out in this paper which can further reduce the torque ripple. This is particularly useful for a system which has a limited/low sampling frequency. The feasibility of a CFTC with an extended carrier frequency in minimizing the torque ripple is verified through experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.819-830
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• 1999

NAVTEX system is an international automated direct-printing service, broadcast on 5181kHz and 490kHz, for the promulgation of navigational and meteorological warnings and urgent information to ships. With our government's adoption of the international convention for SAR(Search and Rescue) in 1993, various trials for the installation of NAVTEX system have been executed by the government committee, relating laboratory and experts. An important consideration of the installation for NAVTEX system is the availability that could broadcast messages written in korean letter. Also, the receiver which can process the signal demodulated from the two frequencies, 518kHz and 490kHz, should be developed and supplied in domestic. In this paper, the code table and algorithm for conversions between NAVTEX characters and Korean Letters are studied, and signal processing techniques of code conversion are developed. Circuit design and implementation of the NAVTEX simulator using the Direct Digital Synthesizer are discussed, code conversion algorithm and signal processing technique of the NAVTEX transmission are programmed in its circuits. For evaluating the its functional characteristics, receiving module which has I-Q channel structure is designed. From the measurements of simulator, the characteristics show the frequency stability of the $(\pm)2Hz$ and Spurious free dynamic range is -63dBc. And the simulator can generate simultaneously wanted signal and several interfere signals. So, its capability is valuable for designers of the transmitting system and NAVTEX receiver, for provider as testing facilities of the type approval.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.630-631
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• 2009

Recent developments such as concern over global warming, depletion of fossil fuels and increase in energy demands by the increasing world population has eventually lead to mass production of electricity using renewable sources. Apart from wind and solar, ocean holds tremendous amount of untapped energy in forms such as geothermal vents, tides and waves. The current study looks at generating power using waves and the focus is on the primary energy conversion (first stage conversion) of incoming waves for two different models. Observation of flow characteristics, pressure and the velocity in the augmentation channel as well as the front guide nozzle are presented in the paper. A numerical wave tank was utilized to generate waves of desired properties and later the turbine section was integrated. The augmentation channel consisted of a front nozzle, rear nozzle and an internal fluid region representing the turbine housing. The analysis was performed using the commercial CFD code.