Non-specific protein removal and specific protein capture simultaneously using a hydrodynamic force induced under vortex flow

류한철,안동준 한국고분자학회 2023 Macromolecular Research Vol.31 No.2

Non-specific binding (NSB) of proteins should be removed to increase the sensitivity of biosensors. In this study, cadmium selenide nanoparticles (CdSe NPs) were rotated in the solution by generating vortex flow, thereby achieved removal of two types of non-specific protein: (i) anti-mouse IgG-FITC (NSB) and (ii) bovine serum albumin (BSA)-FITC. By manipulating rotation rate from 0 to 1000 rpm, photoluminescence (PL) from each protein reduced up to 28% for anti-mouse IgG and 35% for BSA, respectively. In addition, capturing specific proteins from mixture solutions enhanced by 41% upon cyclic-mode vortexing, which is 2.7 times higher than conventional continuous vortexing. These results can open up a new feasibility for increasing sensitivity of biosensors just by utilizing properly the hydrodynamic force.

Loaded-line Ferroelectric Phase Shifter Based on Mn-doped (Ba,Sr)TiO3 Thin Films for Ka-band Systems

류한철,문승언,이수지 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.7

This paper presents on the microwave properties of a loaded-line ferroelectric phase shifter basedon (Ba, Sr)TiO3 (BST) thin films for Ka-band applications. In order to reduce the dielectric loss ofthe BST thin film and its enhance a dielectric tunability, we optimized the deposition of Mn-doped(Ba0.5, Sr0.5)TiO3 (Mn-BST) thin films on MgO substrates by using pulsed laser deposition (PLD). The crystallinity, microstructure and thickness of the thin films were investigated by using an Xraydiffractometer and a scanning electron microscope, respectively. We designed and fabricated atunable ferroelectric capacitor loaded coplanar waveguide (CPW) type phase shifter to enhance thetuning and the loss characteristics of a conventional CPW ferroelectric phase shifter. The fabricatedloaded-line phase shifter showed a low return loss of −15 dB in the frequency band from 25 GHzto 35 GHz. The differential phase shift was 293◦, and the insertion loss decreased from −11.3 dBto −1.4 dB with increasing dc bias voltage from 0 to 80 V at 35 GHz.

An Active Module Using a Ferroelectric CPW Phase Shifter for a Ku-Band APAA System

류한철,강광용,곽민환,박성욱,문승온,이수재,김용태 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.6

This paper presents the development of an active module using a ferroelectric coplanar waveguide (CPW) phase shifter for a Ku-band active phased array antenna (APAA). This active module performs roles such as amplifying an RF signal with low noise coming from an antenna and changing the phase of a received RF signal. This module is composed of a 3-stage low-noise amplifier (LNA), a high-voltage dc block with an RF choke (RFC), and a ferroelectric phase shifter, whose structure is a CPW transmission line based on a (Ba, Sr)TiO3 (BST) thin film. The ferroelectric BST thin film is deposited on an MgO substrate by using pulsed laser deposition. Both ends of the CPW are continuously tapered to obtain good impedance matching without degrading the phase tuning property of the ferroelectric CPW phase shifter. The active module using a ferroelectric CPW phase shifter attains a phase-controllable range of 360 while retaining a return loss of better than .15 dB at Ku-band. The measured gain of the active module increases from 2 dB to 16 dB corresponding to a change in the dc voltage from 0 to 150 V with a 3.6 dB maximum noise figure at 12 GHz.d

Flow-Induced Crystal Growth Using Chemical Reactor

류한철,안동준 한국고분자학회 2022 한국고분자학회 학술대회 연구논문 초록집 Vol.47 No.2

Analysis of the THz Resonance Characteristics of H-shaped Metamaterials with Varying Width

류한철 한국광학회 2021 Current Optics and Photonics Vol.5 No.1

The resonance characteristics of H-shaped metamaterials, whose widths were varied while keeping the height constant, were investigated in the terahertz (THz) frequency range. The H-shaped metamaterials were numerically analyzed in two modes in which the polarization of the incident THz electric field was either parallel or perpendicular to the width of the H-shaped structure. The resonant frequency of the metamaterial changed stably in each mode, even if only the width of the H shape was changed. The resonant frequency of the metamaterial operating in the two modes increases without significant difference regardless of the polarization of the incident electromagnetic wave as the width of the Hshaped metamaterial increases. The electric field distribution and the surface current density induced in the metamaterial in the two modes were numerically analyzed by varying the structure ratio of the metamaterial. The numerical analysis clearly revealed the cause of the change in the resonance characteristics as the width of the H-shaped metamaterial changed. The efficacy of the numerical analysis was verified experimentally using the THz-TDS (time-domain spectroscopy) system. The experimental results are consistent with the simulations, clearly demonstrating the meaningfulness of the numerical analysis of the metamaterial. The analyzed resonance properties of the H-shaped metamaterial in the THz frequency range can be applied for designing THz-tunable metamaterials and improving the sensitivity of THz sensors.

포토닉스 기반 테라헤르츠 가변형 연속파 신호원/검출기 및 응용 기술

류한철,김남제,문기원,박정우,고현성,한상필,김대용,박경현,Ryu, H.C.,Kim, N.J.,Moon, K.W.,Park, J.W.,Ko, H.S.,Han, S.P.,Kim, D.Y.,Park, K.H. 한국전자통신연구원 2012 전자통신동향분석 Vol.27 No.5

테라헤르츠파는 0.1~10THz 대역의 미개발 주파수 자원으로 전자기파 스펙트럼에서 적외선과 밀리미터파의 중간 영역에 위치한다. 전파의 투과성과 광파의 직진성을 동시에 가지고 있어 독특한 물리적 특성을 보유한 테라헤르츠파는 THz 소자, 분광, 영상 기술 등의 기초 과학과 의공학, 보안, 환경/우주, 정보통신 등의 응용 과학 분야에서 이미 그 중요성이 검증되어 향후 폭넓은 산업 응용으로 다양한 분야에서 새로운 형태의 시장이 형성될 것으로 기대된다. 이러한 테라헤르츠파 기술의 사회, 경제적 파급력을 극대화하기 위해서는 테라헤르츠 대역 소자의 특성을 향상시키고, 크기와 가격을 낮추는 것이 매우 중요하다. 본고에서는 크기와 가격을 낮출 수 있는 포토닉스 기반의 테라헤르츠 가변형 연속파 신호원 및 검출기 기술과 이를 기반으로 구현 가능한 응용 기술 동향에 대하여 기술하였다.

Folded Dipole Antenna for Power Enhancement of a Terahertz Photomixer

류한철 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.10

A folded dipole antenna is proposed to increase the input impedance of an antenna for powerenhancement of a terahertz integrated photomixer/antenna because the impedance of a teraherzphotomixer is very high compared to the impedance of an antenna. The antenna was optimizedusing an electromagnetic simulator, and its resistance was increased to 2750, which is about40 times as high as the impedance of a self-complementary broadband antenna. The optimizedantenna was fabricated on low-temperature-grown GaAs (LTG-GaAs) and measured using a liquidhelium-cooled silicon bolometer. Two distributed-feedback tunable diode lasers were scanned forphotomixing at frequencies from 100 to 1300 GHz in steps of 1 GHz. For stable frequency scans, thetwo lasers were controlled by using a feedback loop system. The measured THz output power of theproposed folded dipole antenna integrated with a THz photomixer showed resonant characteristicsand was larger at the resonant frequency bands.

식각된 VO 2 박막을 이용한 밴드-전환형 테라헤르츠파 메타물질

류한철 한국광학회 2020 한국광학회지 Vol.31 No.1

본 논문에서는 온도 변화에 따라 절연체-금속 상전이 특성을 보이는 이산화바나듐(VO 2 )를 식각한 도선과 금속 도선을 조합한 밴드-전환형 테라헤르츠 메타물질을 제시하였다. 갭을 가지는 금속 사각 구조 가운데 식각된 VO 2 도선을 위치시킨 구조와 VO 2상전이 특성을 이용하여 제안된 메타물질의 가변성을 확보하였다. 설계한 VO 2 기반 메타물질은 VO 2 의 절연체-금속 상전이 특성에 따라 공진 주파수가 1.4 THz에서 0.7 THz으로 전환되었다. 이때, 제안한 메타물질의 절대 투과율은 0.7 THz와 1.4 THz에서 각각 78.5%와 65.8%로 높은 변화율을 가지고, 전환이 가능한 두 공진 주파수 중간 대역에서 40%와 60% 사이의 안정적인 투과 율을 보이면서 균일하게 90도의 높은 차등 위상 변위 특성을 보였다.

메타물질 및 VO2 박막 기반의 전기적 제어 가능한 테라헤르츠파 변조기

류한철 한국광학회 2014 한국광학회지 Vol.25 No.5

본 논문에서는 온도 변화에 따라 절연체-금속 상전이 특성을 보이는 이산화바나듐(VO2)과 메타물질을 이용하여 전기적으로제어 가능한 테라헤르츠 변조기를 제시하였다. 변조기 기능을 하는 메타물질 구조가 VO2의 도전율 변화에 영향을 주는 열을전기적으로 조절할 수 있는 히터의 역할도 동시에 할 수 있는 정사각고리 구조의 메타물질을 설계하였다. 설계한 VO2기반 메타물질 변조기의 전파 투과량은 정사각고리 메타물질에 직접 연결된 전압 인가용 도선을 통한 인가 전압 변화로 조절이 가능하다. VO2의 도전율 변화에 따라 전파 투과계수는 470 GHz 에서 0.27에서 0.80으로 안정적으로 조절되었고, 13% 주파수 대역폭에서투과계수 변화폭이 일정하게 유지되었다.

柳麟錫의 연해주 망명과 국권회복운동의 전개

柳漢喆 한국근현대사학회 1996 한국 근현대사 연구 Vol.4 No.-