E급 증폭기의 바이어스 스위칭 회로를 이용한 HF-대역 자기장 통신 시스템

손용호(Yong-Ho Son),이준(June Lee),조상호(Sang-Ho Cho),장병준(Byung-Jun Jang) 한국전자파학회 2012 한국전자파학회논문지 Vol.23 No.9

본 논문에서는 ASK(Amplitude Shift Keying) 송신기, 한 쌍의 루프 안테나 및 ASK 수신기로 구성되는 HF-대역 자기장 통신 시스템을 구현하였다. 특히, E급 증폭기를 사용하는 ASK 송신기의 데이터 변조 방법으로 Drain 바이어스 전압을 입력 데이터에 따라 두 가지 레벨로 가변하여 공급하는 바이어스 스위칭 회로를 새롭게 제안하였다. E급 증폭기는 저가의 IRF510 power MOSFET를 이용하여 6.78 ㎒에서 최대 5 W 출력과 동작 바이어스 전체에서 75 % 이상의 효율이 측정되었다. ASK 수신기는 Log 증폭기, 필터 및 비교기로 구현하여 ?78 ㏈m의 수신 감도를 구현하였다. 자기장 통신 시스템의 최대 통신 거리를 예측하기 위하여 근역장과 원역장에서의 자기장 유도식을 활용하여 전송 손실을 계산하는 방법을 고안하였다. 또한, 30×30 ㎝ 크기의 사각형 루프 안테나쌍을 이용한 실내 전송 실험을 수행하여 제시한 방법의 타당성을 확인하였다. 전송 손실 추정 결과, 1 W 출력과 ?70 ㏈m 수신 감도를 가질 경우 최대 35 m의 수신거리가 계산되었다. 최종적으로 설계된 ASK 송신부와 ASK 수신부를 루프 안테나 쌍에 연결하여 5 m 거리에서 통신이 이루어짐을 확인하였다. In this paper, we implemented a HF-band magnetic-field communication system consisting of an amplitude shift keying(ASK) transmitter, a pair of loop antennas, and an ASK receiver. Especially, we suggested a new ASK transmitter architecture, where a drain bias of class E amplifier is switched alternatively between two voltage levels with respect to input data. A maximum 5 W class E amplifier was designed using a low cost IRF510 power MOSFET at the frequency of 6.78 ㎒. A measured sensitivity of the designed ASK receiver is ?78 ㏈m, which consists of a log amplifier, a filter, and a comparator. Maximum communication range of magnetic-wave communication system with loop antennas was calculated using magnetic field equations in both near-field and far-field ranges. Also, in order to verify the calculated values, an indoor propagation loss was measured using a pair of loop antennas whose dimensions are 30 ㎝×30 ㎝. Maximum operating range is estimated about 35 m in case of transmitter’s output power of 1 W and receiver sensitivity of ?70 ㏈m, respectively. Finally, the communication field test using the designed ASK transmitter and receiver was successfully done at the distance of 5 m.

CRD를 이용한 전자파 잔향실 내 전기장 균일도 향상

손용호(Yong-Ho Son),이중근(Joong-Geun Rhee),김정훈(Jung-Hoon Kim) 대한전자공학회 2007 電子工學會論文誌-TC (Telecommunications) Vol.44 No.12

본 논문에서는 CRD(Cubical Residue Diffuser)를 이용하여 전자파 잔향실 내의 전기장 균일도를 향상시키고, 잔향실 내의 전기장 균일도가 최적화되는 CRD 면적비를 연구하였다. 1 ~ 3 ㎓ 주파수 대역에서 Schroeder 방식의 CRD를 설계하였고, 전자파 잔향실 내의 전기장 분포 해석을 위해 FDTD(Finite Difference Time Domain) 수치해석이 이루어졌다. 해석결과 2 ㎓에서 CRD의 면적이 잔향실 한쪽 내벽의 약 40 ~ 80 %일 경우 전기장 강도 표준 편차가 낮고 균일하게 분포되었으며, 40 % 이하, 또는 80 % 이상의 면적에서는 표준 편차가 높게 나타났다. 특히 가장 나쁜 경우와 비교하여 44%일 때 전기장 균일도가 1 ㏈ 향상됨을 알 수 있었다. This paper presents an improved field uniformity in a reverberation chamber, that can be alternatively used for the analysis and the measurement of electromagnetic interference and immunity, with a designed CRD(Cubical Residue Diffuser) that have various dimensions. The Schroeder type CRD is designed for 1 ~ 3 ㎓ band and the FDTD(Finite Difference Time Domain) method is used to analyze the field characteristics. At 2 ㎓, the standard deviation of test volume in the reverberation chamber is the smallest and has a good field distribution with a CRD of 40 ~ 80 % dimension of one side of the reverberation chamber. The Electric field uniformity gets worse when the dimension of a CRD is either below 40 % or above 80 % of the side wall. The result shows that the standard deviation of the test volume in the reverberation chamber with a CRD of 44 % dimension is improved by 1 ㏈ compared with that of the reverberation chamber with a CRD of 100 % dimension.

E급 증폭기의 바이어스 조정을 통한 LF-대역 무선 전력 전송시스템의 수신 전력 안정화

손용호(Yong-Ho Son),한상규(Sang-Kyoo Han),장병준(Byung-Jun Jang) 한국전자파학회 2013 한국전자파학회논문지 Vol.24 No.9

스마트폰 무선 충전 시나리오에서는 송신 패드에 비해 수신 패드의 크기가 작으므로 수신 패드의 위치에 상관없이 일정한 전력을 부하에 공급하는 것이 중요하다. 본 논문에서는 송신 패드와 수신 패드의 크기가 각각 16 ㎝×18 ㎝와 6 ㎝×8 ㎝의 직사각형 구조를 갖는 경우, 무선 전력 전송 송신부에 위치한 E급 증폭기의 Drain 바이어스 전압만을 조정하여 수신 패드의 위치에 상관없이 일정한 전력이 부하에 공급되는 방식을 제안하였다. 설계된 LF-대역 무선 전력 시스템의 구성은 PWM IC인 TL494로 제어되는 Buck converter 구조의 전원 회로, 저가의 IRF510 power MOSFET을 이용한 E급 증폭기, 송신 패드 및 수신 패드, 그리고 Schottky 다이오드를 이용한 풀 브릿지 정류기로 구성된다. 제작된 무선 전력 전송 시스템은 바이어스 조정을 하지 않는 경우 240 ㎑에서 최대 4 W 출력과 67 % 이상의 시스템 효율을 가지며, 바이어스 조정을 하는 경우에는 수신 패드의 위치에 상관없이 수신 전력을 2 W로 일정하게 유지할 수 있다. In wireless smart phone charging scenario, the transmitter pad is larger than the size of the receiver pad. Thus, it is important to supply a constant power to the receiver regardless of its location. In this paper, we propose a new method to regulate the receiver"s power by adjusting a drain bias of class E power amplifier. The proposed LF-band wireless power transfer system is as follows: a buck converter power supply which is controlled by a pulse width modulation(PWM) IC TL494, a class E amplifier using a low cost IRF510 power MOSFET, a transmitter coil whose dimension is 16 ㎝×18 ㎝, a receiver coil whose dimension is 6 ㎝×8 ㎝, and a full bridge rectifier using Schottky diodes. A measured performance show a maximum output power of 4 W and system efficiency of 67 % if we fix the bias voltage. If we adjust the bias voltage, the received power can be maintained at a constant power of 2 W regardless of receiver pad location.

해동검도와 택견 수련이 초등학생의 신체구성과 체력에 미치는 영향

손용호(Son, Yong-Ho),천성용(Chun, Sung-Yong) 한국체육과학회 2014 한국체육과학회지 Vol.23 No.4

The purpose of this study is the effect of Headong Keumdo and Teakkyon practice on body composition and physical fitness in a elementary school students. The elementrary school students practiced 5time a week for 60minutes over a twelve weeks. There were divided into Control Group(n=15), Headong Keumdo(n=15), and Teakkyon(n=12) for a total of 42male elementary students. All data were analyzed by one-way ANOVA & paired t-test. The results are as follows: Body composition was not significant different between Headong Keumdo and Teakkyon. Sit and reach and Closed eyes one leg stance was not significant different, but Right grip strength was increased(p<.05) on Teakkyon. Sit up and Standing long jump was increased(p<.05) on Teakkyon and 10m shuttle run was increased on Headong Keumdo(p<.05), Teakkyon(p<.01). With the finding as above, this study suggests that; The practice of Headong Keumdo, Teakkyon, was important on basic physical fitness to elementary school student. And following study need to practice program assessment fitted to physical activity of elementary school students.

HVPE 방법으로 성장된 alpha-Ga₂O₃의 특성에 대한 VI/III ratio 변화 효과

손호기,최예지,이영진,이미재,김진호,김선욱,라용호,임태영,황종희,전대우,Son, Hoki,Choi, Ye-Ji,Lee, Young-Jin,Lee, Mi-Jai,Kim, Jin-Ho,Kim, Sun Woog,Ra, Yong-Ho,Lim, Tae-Young,Hwang, Jonghee,Jeon, Dae-Woo 한국결정성장학회 2018 한국결정성장학회지 Vol.28 No.3

본 연구에서는 HVPE 성장법을 이용하여 사파이어 기판 위에 알파 갈륨옥사이드를 성장시키며 VI/III 비의 변화에 따른 효과를 확인하였다. 성장된 알파 갈륨옥사이드의 표면은 평평하고 crack 없이 성장되었다. 성장된 갈륨옥사이드의 광학적 특성을 분석하기 위해 투과율을 측정하고 광학 밴드갭을 얻었다. 광학 밴드갭은 약 5.0 eV로 나타났고 VI/III 비가 증가함에 따라 비례하여 증가하는 결과를 보여주었다. 이론적 광학 밴드갭에 가장 근접한 VI/III 비가 23인 조건에서 성장된 알파 갈륨옥사이드의 결정성을 확인하기 위해 HR-XRD를 이용하여 FWHM을 측정하였고 이를 바탕으로 전위밀도를 계산하였을 때 나선형 전위밀도는 $1.5{\times}10^7cm^{-2}$, 칼날 전위 밀도는 $5.4{\times}10^9cm^{-2}$로 계산되었다. In this study, we report the effect of VI/III ratio on ${\alpha}-Ga_2O_3$ epilayer on sapphire substrate by halide vapor phase epitaxy. The surface of ${\alpha}-Ga_2O_3$ epilayer grown with various VI/III ratios was flat and crack-free. To analyze the optical properties of the ${\alpha}-Ga_2O_3$ epilayers, the transmittance and an optical band gap were measured. The optical band gap was shown to be around 5 eV and showed a proportional increase in VI/III ratios. To determine the crystal quality of alpha gallium oxide grown with a ratio of 23, closed to the theoretical optical band gap, the FWHM was measured by HR-XRD. The calculated dislocation density of screw and edge were $1.5{\times}10^7cm^{-2}$ and $5.4{\times}10^9cm^{-2}$, respectively.

원뿔 형태의 patterned sapphire substrate 위에 성장한 α-Ga₂O₃의 특성분석

손호기,최예지,이영진,김진호,김선욱,라용호,임태영,황종희,전대우,Son, Hoki,Choi, Ye-Ji,Lee, Young-Jin,Kim, Jin-Ho,Kim, Sun Woog,Ra, Yong-Ho,Lim, Tae-Young,Hwang, Jonghee,Jeon, Dae-Woo 한국결정성장학회 2019 韓國結晶成長學會誌 Vol.29 No.4

본 연구에서는 halide vapor phase epitaxy 성장법을 이용하여 원뿔 형태의 패턴이 주기적으로 형성된 patterned sapphire substrate(PSS) 위에 ${\alpha}-Ga_2O_3$를 성장하고 그 특성에 변화에 대해 분석하였다. PSS의 패턴의 유무에 따른 영향을 알아보기 위해 c-plane 사파이어 기판과 원뿔의 크기가 다른 두 개의 PSS 위에 ${\alpha}-Ga_2O_3$를 성장하여 비교 분석하였다. 또한 PSS 위에 성장된 ${\alpha}-Ga_2O_3$의 성장과정을 알아보기 위해 점차 성장 시간을 증가해가며 관찰하였고 성장 온도를 $470-550^{\circ}C$까지 변화해가며 성장하였다. 이를 통해 원뿔 형태의 패턴이 형성된 PSS 위에서의 최적 성장 조건과 그 성장 mechanism에 대해 분석이 가능하였고 그 결과로 성장과정에서 발생하는 수평 성장에 의해 ${\alpha}-Ga_2O_3$의 비대칭면인 (10-14) 반치폭 값을 크게 감소시킬 수 있었다. In this study, we demonstrated a characterization of ${\alpha}-Ga_2O_3$ grown on a cone-shape patterned sapphire substrate by using the halide vapor phase epitaxy. An ${\alpha}-Ga_2O_3$ was grown on different size of PSS and c-plane sapphire substrate for comparison to confirm the effect of PSS. In addition, growth time of ${\alpha}-Ga_2O_3$ was gradually increased to confirm growth mechanism of ${\alpha}-Ga_2O_3$ grown on the PSS. A growth temperature was changed to $470-550^{\circ}C$. It can be analyzed growth conditions and mechanisms on the cone-shape PSS, resulting in a significant decrease in the FWHM value of an asymmetric plane (10-14) of ${\alpha}-Ga_2O_3$, due to lateral growth that occurs during the growth process.

HVPE 방법으로 성장한 Alpha-Ga₂O₃의 특성 분석

손호기,라용호,이영진,이미재,김진호,황종희,김선욱,임태영,전대우,Son, Hoki,Ra, Yong-Ho,Lee, Young-Jin,Lee, Mi-Jai,Kim, Jin-Ho,Hwang, Jonghee,Kim, Sun Woog,Lim, Tae-Young,Jeon, Dae-Woo 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.6

We demonstrated a crack-free ${\alpha}-Ga_2O_3$ on sapphire substrate by horizontal halide vapor phase epitaxy (HVPE). Oxygen-and gallium chloride-synthesized Ga metal and HCl were used as the precursors, and $N_2$ was used as the carrier gas. The HCl flow and growth temperature were controlled in the ranges of 10~30 sccm and $450{\sim}490^{\circ}C$, respectively. The surface of ${\alpha}-Ga_2O_3$ template grown at $470^{\circ}C$ was flat and the root-mean-square (RMS) roughness was ~2 nm. The full width at half maximum (FWHM) values for the symmetric-plane diffractions, were as small as 50 arcsec and those for the asymmetric-plane diffractions were as high as 1,800 arcsec. The crystal quality of ${\alpha}-Ga_2O_3$ on sapphire can be controlled by varying the HCl flow rate and growth temperature.

후막 스피커 응용을 위한 Pb(Zr₁Ti)O₃-PVDF 복합체의 압전 특성 평가

손용호,김성진,김영민,정준석,류성림,권순용,Son Yong-Ho,Kim Sung-Jin,Kim Young-Min,Jeong Joon-Seok,Ryu Sung-Lim,Kweon Soon-Yong 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.10

We reported on characteristics of the piezoelectric ceramic-polymer composite for the application of the thick-film speaker. The PVDF-PZT composites were fabricated to incorporate the advantages of both ceramic and polymer with various mixing ratios by 3-roll mill mixer. The composite solutions were coated by the conventional screen-printing method on ITO electrode coated PET (Polyethylene terephthalate) polymer film. After depositing the top-electrode of silver-paste, 4 kV/mm of DC field was applied at $120^{\circ}C$ for 30 min to poling the composite films. The value of $d_{33}$ (piezoelectric charge constant) was increased when the PZT weight percent was increased. The maximum value of the $d_{33}$ was 24 pC/N at 70 wt% PZT. But the $g{33}$ (piezoelectric voltage constant) showed the maximum value of $32mV{\cdot}m/N$ at 65 wt% of PZT powder. The SPL (sound pressure level) of the speaker fabricated with the 65:35 composite film was about 68 dB at 1 kHz.

HVPE 방법으로 성장된 알파-갈륨 옥사이드의 전처리 공정에 따른 특성 변화

최예지,손호기,라용호,이영진,김진호,황종희,김선욱,임태영,전대우,Choi, Ye-ji,Son, Hoki,Ra, Yong-Ho,Lee, Young-Jin,Kim, Jin-Ho,Hwang, Jonghee,Kim, Sun Woog,Lim, Tae-Young,Jeon, Dae-Woo 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.5

In this study, we report the effect of pre-treatment of alpha-$Ga_2O_3$ grown on a sapphire substrate by halide vapor phase epitaxy (HVPE). During the pre-treatment process, 10 sccm of GaCl gas was injected to the sapphire substrate at $470^{\circ}C$. The surface morphologies of the alpha-$Ga_2O_3$ layers grown with various pre-treatment time (3, 5, and 10 min) were flat and crack-free. The transmittance of the alpha-$Ga_2O_3$ epi-layers was measured to analyze their optical properties. The transmittance was over 80% within the range of visible light. The strain in the alpha-$Ga_2O_3$ grown with a pre-treat 5 min was measured, and was found to be close to the theoretical XRD peak position. This can be explained by the reduction of strain having caused a lattice mismatch between the alpha-$Ga_2O_3$ layer and sapphire substrate. The calculated dislocation density of the screw and edge were $2.5{\times}10^5cm^{-2}$ and $8.8{\times}10^9cm^{-2}$, respectively.

Glass Frit의 첨가에 따른 BaTiO₃ 소결체의 유전 특성 및 미세구조 변화

우덕현,윤만순,손용호,류성림,어순철,권순용,Woo, Duck-Hyun,Yoon, Man-Soon,Son, Yong-Ho,Ryu, Sung-Lim,Ur, Soon-Chul,Kweon, Soon-Yong 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.3

$BaTiO_3$ dielectric ceramics are widely used to multi-layer ceramic capacitor. The $BaTiO_3$ powder was synthesized at $950^{\circ}C$ by using a solid state reaction and grinded by using a high-energy mill. And then, 2.53 wt% glass frit was added to the synthesized $BaTiO_3$ powders for lowering the sintering temperature. The mixed powders were sintered at various temperatures of $1170^{\circ}C$, $1200^{\circ}C$, $1230^{\circ}C$. Microstructures of the sintered $BaTiO_3$ ceramics were inspected by SEM and crystal structures were analyzed by XRD method. The relative dielectric constant was measured by using a impedance/gain phase analyzer. The synthesized $BaTiO_3$ powder had the tetragonal perovskite structure without secondary phase and the particle size was below 200 nm. The relative densities measured at the samples sintered at the temperature above $1200^{\circ}C$ were about 95%. The relative dielectric constant showed maximum value of 2310, which was measured in the specimen sintered at $1200^{\circ}C$. From these results, we could know that the added glass frit had effects on both lowering the sintering temperature and improving the dielectric property.