• Journal of Korea Multimedia Society
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• v.25 no.11
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• pp.1634-1642
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• 2022

Numerous studies have attempted to present converting 2D drawings to 3D. However, converting 3D shapes to exactly how a person thinks is challenging because 2D drawings include numerous variables and possibilities. This study focuses on visualizing 2D to 3D in a commonly used 3D animation software required in animation education or the 3D industry. We implemented our SketchTo3D tool to add the editing and automatic texture assigning method from the imported 2D image into the 3D software that previously had to be done manually. As a result, the SketchTo3D tool saves time to immediately visualize the composition, shape, and volume to express the 3D character, providing an opportunity to break down the barrier between 2D and 3D.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.133-140
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• 2019

Two-dimensional (2D) ultrathin molybdenum dichalcogenides $MoS_2$ has gained a great deal of attention in energy conversion and storage applications because of its unique morphology and property. The 2D $MoS_2$ nanosheets provide a high specific surface area, 2D charge channel, sub-nanometer thickness, and high conductivity, which lead to high electrochemical performances for energy storage devices. In this paper, an overview of properties and synthetic methods of $MoS_2$ nanosheets for applications of supercapacitors and rechargeable batteries is introduced. Different phases triangle prismatic 2H and metallic octahedral 1T structured $MoS_2$ were characterized using various analytical techniques. Preparation methods were focused on top-down and bottom-up approaches, including mechanical exfoliation, chemical intercalation and exfoliation, liquid phase exfoliation by the direct sonication, electrochemical intercalation exfoliation, microwave-assisted exfoliation, mechanical ball-milling, and hydrothermal synthesis. In addition, recent applications of supercapacitors and rechargeable batteries using $MoS_2$ electrode materials are discussed.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.60.3-60.3
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• 2021

Squeezed vacuum injection을 이용한 중력파 검출기의 관측감도 향상 기술은 중력파 검출기 광신호의 양자 잡음을 제어하여 관측감도를 높이는 기술로 이론적으로는 10dB에 가까운 신호 대 잡음비 향상을 달성할 수 있다. 실험실 환경에서는 이미 10dB 이상의 신호 대 잡음비 향상을 달성했으며 실제 중력파 검출기에서는 GEO600의 6dB의 신호 대 잡음비 향상이 현재까지 가장 높은 수준이다. 한국천문연구원에서는 2019년부터 차세대 중력파 검출기 기술개발로 1064 nm 파장의 squeezer 개발을 추진했으며 현재 parametric down conversion을 이용해 squeezed vacuum을 생성하는 공진기를 제작하여 시험하는 단계에 있다. 이 발표에서는 한국천문연구원의 1064 nm squeezer 개발 연구와 개발 현황에 대해 소개하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.7
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• pp.293-299
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• 2003

In this paper, we have proposed a high conversion and isolation characteristic V-band quadruple sub-harmonic mixer monolithic circuit which is designed and fabricated for the millimeter wave down converter applications. While most of the sub-harmonic mixers use a half of fundamental frequency, we adopt a quarter of the fundamental frequency. The proposed circuit is based on a sub-harmonic mixer with APDP(anti-parallel diode pair) and the 0.1 ${\mu}{\textrm}{m}$ PHEMT's (pseudomorphic high electron mobility transistors). Lumped elements at IF port provide better selectivity of IF frequency and increase isolation. Maximum conversion gain of 0.8 ㏈ at a LO frequency of 14.5㎓ and at a RF frequency of 60.4 ㎓ is measured. Both LO-to-RF and LO-to-IF isolations are higher than 50 ㏈. The conversion gain and isolation characteristic are the best performances among the reported quadruple sub-harmonic mixer operating in the V-band millimeter wave frequency thus far.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.91-99
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• 2018

This paper has proposed a low-noise and high-linear RF receiver supporting TV white space from 470 MHz to 698 MHz), which is implemented in $0.13-{\mu}m$ CMOS technology. It consists of a low-noise amplifier, a RF band-pass filter, a RF amplifier, a passive down-conversion mixer, and a channel-selection low-pass filter. A low-noise amplifier and RF amplifier provide a high voltage gain to improve the sensitivity level. To suppress strong and nearby interferers, two RF filtering schemes have been performed by using a RF BPF and a down-conversion mixer. The proposed LPF has been based on the common-gate topology and adopted a bi-quad cell to achieve -24dB/oct characteristics. In addition, the RF receiver can support the overall TV band by controlling a LO frequency. The simulated results show a voltage gain of 56 dB, a noise figure of less than 2 dB, and an out-of-channel IIP3 of -2.3 dBm. It consumes 37 mA from a 1.5 V supply voltage.

• Korean Journal of Optics and Photonics
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• v.13 no.1
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• pp.15-20
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• 2002

We demonstrate a widely-tunable wavelength converter based on four-wave mixing in a semiconductor-fiber ring laser with no external pump light. Applying 10 GHz short pulses at -8 dBm as a probe signal, we achieve continuous wavelength tuning over the semiconductor optical amplifier gain-bandwidth reaching 30 nm down- and 17 m up-wavelength conversion. In addition to the wide tuning capability, the converter shows high-speed conversion and low saturation power capabilities.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.165-172
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• 1998

The electromechanical energy conversion conditioning and processing implementation in USM direct motion control system is generally divided into two power stages: the two-phase high-frequency ac power inversion stage for driving piezoelectric ceramic PZT transducer array off the USM stator and the mechanical thrust power conversion stage based on the frictional force between the piezo electric stator array and the rotary slider of the USM. However, the dynamic and steady-state mathematical modeling of the USM is extremely default from a theoretical point of view because it contains many complicated an nonlinear characteristics dependant on operation temperature. In +2$0^{\circ}C$~3$0^{\circ}C$, the operating characteristics of the USM has represented normal condition. But the other temperature, it has abnormal condition so that driving frequency, current and motor speed will be down. The recent USM has controller without temperature compensation. This study represents the fuzzy controller for speed compensation according to operating temperature by driving frequency.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.45-49
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• 2009

In this paper, a direct down conversion LNA/Mixer has been designed and tested for 900Mhz UHF RFID application. The designed circuit has been implemented in 0.18um CMOS technology with 3.3V operation. In this work, a common gate input architecture has been used to cope with the higher input self jamming level. This LNA/Mixer is designed to support two operating modes of high gain mode and low gain mode according to the input jamming levels. The measured results show that the input referred P1dBs are 4dBm of high gain mode and 11dBm of low gain mode, and the conversion gains are 12dB and 3dB in high and low gain mode respectively The power consumptions are 60mW for high gain mode and 79mW for low gain mode. The noise figures are 16dB and 20dB in high gain mode and low gain mode respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.7
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• pp.7-15
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• 2002

The digital DBS tuner is designed and implemented in a CMOS process using a direct-conversion architecture that offers a high degree of integration. To generate mathched LO I/Q quadrature signals covering the total input frequency range, a fully integrated ring oscillator is employed. And, to decrease a high level of phase noise of the ring oscillator, a frequency synthesizer is designed using a double loop strucure. This paper proposes and verifies a band selective loop for fast frequency switching time of the double loop frequency synthesizer. The down-conversion mixer with source follower input stages is used for low voltage operation. An experiment implementation of the frequency synthesizer and mixer with integrated a 0.25um CMOS process achieves a switching time of 600us when frequency changes from 950 to 2150MHz. And, the experiment results show a quadrature amplitude mismatch of max. 0.06dB and a quadrature phase mismathc of max. >$3.4^{\circ}$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.3
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• pp.51-57
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• 2010

A dual-mode direct conversion receiver is developed in $0.13\;{\mu}m$ RF CMOS process for IEEE 802.11n based wireless LAN and IEEE 802.16e based mobile WiMAX application. The RF receiver covers the frequency band between 2.3 and 2.7 GHz. Three-step gain control is realized in LNA by using current steering technique. Current bleeding technique is applied to the down-conversion mixer in order to lower the flicker noise. A frequency divide-by-2 circuit is included in the receiver for LO I/Q differential signal generation. The receiver consumes 56 mA at 1.4 V supply voltage including all LO buffers. Measured results show a power gain of 32 dB, a noise figure of 4.8 dB, a output $P_{1dB}$ of +6 dBm over the entire band.