• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.715-719
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• 2003

The Aerosol Deposition (AD) process will be proposed as a new fabrication technology for the integrated RF modules. $\alpha$-A1$_2$O$_3$ thick films were successfully grown on glass and Al substrates at room temperature by the AD process. Relative dielectric permittivity and loss tangent of the $Al_2$O$_3$ thick films on Al showed 9.5 and 0.005, respectively. To form microstrip lines on aerosol-deposited A1903 thick films, copper electroplating and lithography processes were employed, and the square-type cross section with sharp edges could be obtained. Low-pass LC filters with 10 GHz cutoff frequency were simulated by an electromagnetic analysis, exhibiting the validity of the AD process as a fabrication technology f3r integrated RF modules.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.693-701
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• 2002

In this paper, we analyze the coverage of asynchronous IMT(International Mobile Telecommunication)-2000 reverse link with a MUD(Multi-User Detector) system. The MUD system is utilized to increase the coverage of reverse link. Also we have considered a propagation loss model and an interference effect. Because it is very difficult that we have calculated the interference accurately, so a fractional cell loading factor(F) is used in this paper. We make use of a MUD efficiency($\beta$) to analyze the performance; this efficiency is presented the MAI of reduction. A simulation utilizes Hata's model, we calculated the coverage according to voice and data services. In this paper, we have assumed that the frequency of carrier has 800 MHz or 1.9 GHz, and a bandwidth is decided 3.84 MHz. We have predicted the performance of actual system by the analysis of capacity and coverage.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.55-59
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• 2008

In this paper, the linearity of Doherty amplifier has been improved by applying a compact slow-wave microstrip branch-line coupler on the output of Doherty amplifier. The proposed branch coupler has four microstrip high-low impedance resonant cells periodically placed inside the branch-line coupler to result in high slow-wave effect. The new coupler not only effectively reduces the occupied area to 30% of the conventional branch-line coupler at 1.8GHz, but also has high second harmonic suppression performance. We obtained the 3rd-order intermodulation distortion ($IMD_3$) of -31.16 dBc for CDMA applications with that of maintaining the constant power added efficiency (PAE). The IMD3 performance is improved as much as -7 dBc compared with a Doherty amplifier.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.114-115
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• 2007

In this study, low temperature sintering property of the $0.6TiTe_3O_8-0.4MgTiO_3$ ceramics with sintering adds were investigated for LTCC application which enable to cofiring with Ag electrode. $TiTe_3O_8$ mixed with $MgTiO_3$ to improve the temperature property. In the X-ray diffraction patterns, the columbite structure of $TiTe_3O_3$ phase and ilmenite structure of $MgTiO_3$ phase were coexisted in all specimens. In the case of $H_3BO_3$ addition, the bulk density and dielectric constant were decreased but quality factor was increased with amount of $H_3BO_3$ additions. The TCRF of the $0.6TiTe_3O_8-0.4MgTiO_3+xwt%H_3BO_3$ ceramics were moved to positive direction. In another case, SnO addition, the bulk density and dielectric constant were increased but Quality factor was decreased with amount of SnO additions. The TCRF of the $0.6TiTe_3O_8-0.4MgTiO_3$+ywt%SnO ceramics were shifted to negative direction. The dielectric constant, quality factor and TCRF of the $0.6TiTe_3O_8-0.4MgTiO_3$ ceramics with $2wt%H_3BO_3$ and 2.5wt%SnO sintered at $830^{\circ}C$ for 1h, were 28.5, 39,570GHz, $+9.34ppm/^{\circ}C$ and 29.86, 35,80000z, $-0.58ppm/^{\circ}C$, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.80-80
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• 2000

Surface acoustic wave (SAW) devices have become more important as mobile telecommunication systems need h호-frrequency, low-loss, and down-sized components. Higher-frequency SAW divices can be more sasily realized by developing new h호-SAW-velocity materials. The ZnO/diamond/Si multilasyer structure is one of the most promising material components for GHz-band SAW filters because of its SAW velocity above 10,000 m/sec. Silicon carbide is also a potential candidate material for high frequency, high power and radiation resistive electronic devices due to its superior mechanical, thermal and electronic properties. However, high price of commercialized 6- or 4H-SiC single crystalline wafer is an obstacle to apply SiC to high frequency SAW devices. In this study, single crystalline 3C-SiC thin films were grown on Si (100) by MOCVD using bis-trimethylsilymethane (BTMSM, C7H20Si7) organosilicon precursor. The 3C-SiC film properties were investigated using SEM, TEM, and high resolution XRD. The FWHM of 3C-SiC (200) peak was obtained 0.37 degree. To investigate the SAW propagation characteristics of the 3C-SiC films, SAW filters were fabricated using interdigital transducer electrodes on the top of ZnO/3C-SiC/Si(100), which were used to excite surface acoustic waves. SAW velocities were calculated from the frequency-response measurements of SAW filters. A generalized SAW mode. The hard 3C-SiC thin films stiffened Si substrate so that the velocities of fundamental and the 1st mode increased up to 5,100 m/s and 9,140 m/s, respectively.

• Journal of the Korean earth science society
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• v.43 no.2
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• pp.239-252
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• 2022

Quality control methods for the first G-band vapor radiometer (GVR) mounted on a weather aircraft in Korea were developed using the GVR Precipitable Water Vapor (PWV). The aircraft attitude information (degree of pitch and roll) was applied to quality control to select the shortest vertical path of the GVR beam. In addition, quality control was applied to remove a GVR PWV ≥20 mm. It was found that the difference between the warm load average power and sky load average power converged to near 0 when the GVR PWV increased to 20 mm or higher. This could be due to the high brightness temperature of the substratus and mesoclouds, which was confirmed by the Communication, Ocean and Meteorological Satellite (COMS) data (cloud type, cloud top height, and cloud amount), cloud combination probe (CCP), and precipitation imaging probe (PIP). The GVR PWV before and after the application of quality control on a cloudy day was quantitatively compared with that of a local data assimilation and prediction system (LDAPS). The Root Mean Square Difference (RMSD) decreased from 2.9 to 1.8 mm and the RMSD with Korea Local Analysis and Precipitation System (KLAPS) decreased from 5.4 to 4.3 mm, showing improved accuracy. In addition, the quality control effectiveness of GVR PWV suggested in this study was verified through comparison with the COMS PWV by using the GVR PWV applied with quality control and the dropsonde PWV.

• Preventive Nutrition and Food Science
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• v.9 no.1
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• pp.53-57
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• 2004

The purpose of this study was to investigate the effects of green tea catechin on mixed function oxidase system (MFO), lipofuscin contents, carbonyl value, oxidative damage and the antioxidative defense system in lung of microwave exposed rats. Experimental groups were divided to normal group and microwave exposed group. The microwave exposed groups were subdivided into three groups: catechin free diet (MW-0C) group, 0.25% catechin (MW-0.25C) group and 0.5 ％ catechin (MW-0.5C) group according to the levels of dietary catechin supplementation. The rats were irradiated with microwave at frequency of 2.45 GHz for 15 min. Experimental animals were sacrificed at 6th day after microwave irradiation. The contents of cytochrome P$_{450}$ contents in MW-0C group was increased to 95% , compared with normal group. MW-0.25C and MW-0.5C groups were reduced to 16% and 31%, respectively, compared with MW-0C group. The activity of NADPH-cytochrome P$_{450}$ reductase in MW-0C group was increased to 44%, compared with normal group. MW-0.25C and MW-0.5C groups were reduced to 12% and 17％, respectively, compared with MW-0C group. The activity of superoxide dismutase (SOD) in MW-0C group was decreased to 21 ％, compared with normal group. MW-0.25C and MW-0.5C group were significantly (p < 0.05) increased, compared with MW-0C group. The activity of glutathione peroxidase (GSHpx) in MW-0C group was significantly decreased, compared with normal group. MW-0.25C and MW-0.5C groups were recovered to the level of normal group. The thiobarbituric acid reactive substances (TBARS) content in MW-0C group was increased to 34 ％, compared with normal group. Catechin supplementation groups were maintained the level of normal group. The levels of caybonyl value in MW-0C group was increased to 21 ％, compared with normal group. MW-0.25C and MW-0.5C groups were reduced to 14% and 12%, respectively, compared with MW-0C group. The lipofuscin contents in MW-0C group were increased to 23.4 ％, compared with normal group. That of MW-0.5C group was significantly reduced, compared with MW-0C group. In conclusion, MFO system was activated and the formation of oxidized protein, lipofuscin was increased and antioxidative defense system was weakened of lung tissue in microwave exposed rats, thus oxidative damage was increased. But it was rapidly recovered to normal level by green tea catechin supplementation.n.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.563-566
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• 2000

The effect of CuO and CuO-B $i_2$ $O_3$ additives on microwave dielectric properties of (P $b_{0.45}$C $a_{0.55}$)[F $e_{0.5}$N $b_{0.5}$)$_{0.9}$S $n_{0.1}$] $O_3$were investigated to decrease the sintering temperature for usage of Low Temperature Co-firing Ceramics (LTCC). The (P $b_{0.45}$C $a_{0.55}$)[F $e_{0.5}$N $b_{0.5}$)$_{0.9}$S $n_{0.1}$] $O_3$ceramics was sintered at 11$65^{\circ}C$. In order to decrease the sintering temperature, CuO and Cuo-B $i_2$ $O_3$ were added in the (Pb,Ca)[(Fe,Nb)Sn] $O_3$ with CuO-B $i_2$ $O_3$. For the addition of 0.4 wt.% CuO, the sintered density and the dielectric constant of the ceramics were revealed the maximum values of the 6.06g/c $m^2$ and 83 respectively and temperature coefficient of resonance frequency ($\tau$$_{f}$) shifted to the positive value. As increasing B $i_2$ $O_3$to the (Pb,Ca)[(Fe,Nb)Sn] $O_3$ with CuO-B $i_2$ $O_3$with 0.2 wt.% CuO, the sintered density, the $\varepsilon$$_{r}$ and the Q was decreased, and $\tau$$_{f}$ was minimized at 0.2 wt.% CuO, and 0.2 wt.% B $i_2$ $O_3$. For this composition, dielectric properties were $\varepsilon$$_{r}$ of 81, Q. $f_{0}$ of 4400 GHz, and $\tau$$_{f}$ of 5 ppm/$^{\circ}C$ at sintering temperature of 100$0^{\circ}C$. the relationship between the microstructure and properties of ceramics was studied by X-ray diffraction(XRD), scanning electron microscopy(SEM).copy(SEM).oscopy(SEM).copy(SEM).EM).

• 전기의세계
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• v.27 no.5
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• pp.33-54
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• 1978

(차례) 1.산학협동심포지업 (1)우리나라에서의 연구개발과 산학협동 (2)산학협동과 산업계의 역할 (3)산학협동의 현황과 진로 2.학술회의A (1)전력게통의 계층구조와 협조원리에 관한 연구 (2)2중층괴상회전자 유도전동기의 이론해석 (3)초고주파가열장치에 사용하는 철공진변압기의 해석적 설계 (4)한국전기기시험연구소 대전력단락 시험설비설계 (5)직류전동기제어를 위한 Thyristor Chopper정류회로에 관한 연구 (6)선로의 개폐정보를 포함하는 전력계통의 상태추정 (7)단일신경세포에 대한 ITEM 신호 특성 3.학술회의B (1)MMM-1 Computer System의 설계 및 제작 (2)Adaptive Delta Modulation System의 성능비교 연구 (3)6GHZ FMD마이크로파 무선전송장치의 개발 (4)적선도에 의한 회로망함수의 결정 (5)동맥혈압의 해석과 그의 전기적 유사모델 (6)피부감각의 정보전달 특성에 관하여 (7)선형직접회로의 공정설계 및 그 특성 조성 (8)DH L.D의 전기적포화현상에 관한 이론적 해석 (9)Potocoupler를 이용한 Isolator 4.학술회의C (1)Al-Al$_{2}$O$_{3}$ -Al박막구조의 전기적 특성 (2)이종금속에 샌드위치된 고분자물질의 단락전조 (3)유전체가 일부체워진 직 6면체의 캐비티의 다중모오드 해석 (4)반도체 가스 검지소자의 제조 및 그의 전기적 특성 (5)실리콘 산화공정에 대한 실험적 고찰 (6)진공증착법에 의한 InSb 박막제도에서 열처리효과 (7)(Ba$_{1}$-xBix) Tio$_{3}$ PTC thermistor의 첨가량의 최적건안 (8)금속박막증착시 두께조절 5.특별강연회 (1)일본에 있어서의 절력계통공학연구 (2)Linear Motor의 최근개발동향량도 높았다. valine과 leucine 및 aspartic acid, glycine과 glutamic acid, leucine과 aspartic acid 간에는 고도의 정상관, glycine과 serine, valine과 phenylalanine, threonine과 proline, phenylalanine과 arginine, methionine과 glutamic acid, histidine과 lysine 간에는 유의 정상관, 그리고 isoleucine과 lysine 간에는 유의한 부상관이 있었다. 4. lysine 함량은 단백질 함량과 정산곤, isoleucine 함량은 단빅질 함량과 부상관을 보였으며, alanine, valine, leucine 함량은 지방함량과 각각 유의한 정산관을 보였다. 5. 대두 단백질은 7.5% acrylamide gel 전기영동에 의해 품종에 따라 12～16개의 구성분으로 분리되었으며, 이들중 주구성분들은 상대이동도가 0.06(a), 0.14(b). 0.24(d) 이었고, 구성분 b의 함량이 품종간에 가장 변이가 컸으며, 구성분 b는 그밖의 주요 구성분들의 함량과 부의 상관이 있었고, 구성분 a는 단백질 함량과 정상관이 있었다. 6. 종실단백질 구성분들의 조합 특성 면에서 공시 86품종은 11개 유형군으로 분류되었으며, 우리나라와 일본품종은 미국품종에 비해 단백질구성분 조성이 훨씬 다양하였다. 7. 이동도가 매우 빠른 단백질 구성분 o(Rm 0.77) p(Rm 0.81)를 모두 갖고 있는 품종은 3품종, 모두 갖고 있지 않은 품종은 1품종이었고, 나머지 82품종은 o나 p중 한 구성분을 갖고 있었으며 그 분포율은 30 : 65 이었는데 미국계 품종은 우리나라 품종에 비해 구성분 o를 간고 있는 비율이 현저히 적었다. 8. 대두 종실은 개화후 22일까지 완만히, 그 이후 20～30일간 급속히

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.165-165
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• 2017

모돈은 사육 특성상 제한된 파일롯 공간 안에 장시간 머물기 때문에 과중한 몸무게에 의한 지제 이상, 섭식 등의 불량, 수면상태의 불량 등을 지속적으로 관찰해야 하는 대상이다. 측면에 다수의 초음파 센서를 설치하여 기립의 상태 및 운동 시 몸체 궤적의 특성을 분석하여 종합적으로 모돈의 행동 특성을 정량화 하고자 하였다. 이 과정에서 계측 신호의 값을 대수적으로 비교하는 방식에 한계가 있음을 발견하였고, 이를 해결하고자 10 Hz/Ch 내외의 시계열 상대거리 궤적 신호를 주파수 도메인으로 변경하여 분석을 수행하였다. 일정 주파수에 집중되어 있는 주파수 값의 크기 변화(파워 스펙트럼 밀도)를 기준으로 모돈의 움직임의 정상 상태 유무 판별이 가능하였다. 단, 이러한 분석은 계측 데이터를 일괄 처리 방식으로 분석하는 방법으로 도출이 되었으므로, 계측과 정량 분석을 동시에 수행하기 위한 개선이 필요하였다. 계측 시스템에서 사용한 마이크로 프로세서는 Nucleo-446(STMelectronics, CA, USA)로 180 Mhz의 클럭 속도로 작동하나, 총 100 Hz 내외의 16비트 계측 신호에 대해 추가적으로 FFT 등의 주파수 변환 신호 처리를 수행하기에는 연산 능력이 부족하였다. 한편, 주파수 분석의 주기를 1분 단위로 할 경우 처리해야할 정보의 크기는 $100{\times}60{\times}5{\times}2Byte$ 이므로 1분 내에 해당 연산을 종료할 수 있는 추가의 연산 장치가 필요하였다. 계측과 주파수 도메인 변환 연산을 동시에 수행하기 위하여 1 Ghz의 연산능력을 가진 ARM A9 계열의 초소형 멀티코어 AP인 NanoPi Neo Air(Friendlyarm, Guangzhou, China)을 선정하였다. 4개의 코어를 각각 계측, Median 필터링, Smoothing 연산, FFT 분석에 사용하여 1분 단위, 2분 단위, 5분 단위의 주파수 분석을 동시에 수행하였다. 병렬 연산 라이브러리는 오픈 소스인 MPICH(www.mpich.org)를 이용하였다. 상대적으로 여유있는 자원을 보유하고 코어를 실시간으로 결정하여 다수의 모돈 개체 동시 모니터링을 위한 네트워크 연결 역할을 동시에 수행하도록 하였다. 1주일 내외의 요인 실험 수행 결과, 약 70 Mbyte의 데이터가 축적이 되었으며, 1분 단위, 2분 단위, 5분 단위의 주파수 도메인 변환 후 결과를 동시에 취득할 수 있었다. 일부 주파수 도메인 상의 파워 밀도 값이 모돈의 행동 특성에 분석에 유효한 정보를 제공함을 발견하였다. 모돈사 내 현장 보급이 가능한 초소형 AP와 멀티 코어 기반 병렬 처리 기법을 이용한 현장 진단 시스템 개발 연구를 지속적으로 수행할 것이다.