소형 레이다에서 송신 및 국부발진신호의 불요파 영향성 검토

서미희,박진성,김현주 한국전자파학회 2023 한국전자파학회논문지 Vol.34 No.8

The spurious signals of the transmission signal (FTX) and local oscillation signal (FLO) for a receiver are the factors that reduce the SNR(signal-to-noise ratio) performance of a radar. In particular, a spurious signal with a high-power level causes the radar to falsely indicate a target. However, the spurious emissions of a frequency synthesizer are unavoidable because of the nonlinearity of the RF active elements on the FTX and FLO paths. In this study, spurious requirements are provided to ensure the SNR performance of a compact radar. Consequently, the spurious power level should be lower than −55 dBc to −28 dBc according to the offset frequency in the FMICW mode. In addition, it should be lower than −50 dBc to −40 dBc within a linear frequency modulation bandwidth (LFMM) in the MPRF mode, and the spurious that are out of the LFMM do not impact the signal processing results.

Ka대역 100 W급 SSPA 개발

서미희,정해창,나경일,김소수 한국인터넷방송통신학회 2022 한국인터넷방송통신학회 논문지 Vol.22 No.6

In this paper, a 100 W SSPA in Ka-band was developed by combining 16 GaN MMICs which were 10 W amplifiers, respectively. The gate voltage of SSPA was controlled to minimize the effect of SSPA noise on the receiver during the receiving time. And the transmit power could be reduced about 20 dB to prevent the receiver from being saturated by a large signal from a nearby target. At 10%, 40% duty rato, the peak power and the power efficiency at center frequency were measured 52.4 dBm, 19.2%, and 51.6 dBm, 16.6% respectively. 본 논문에서는 10 W급 전력증폭 GaN MMIC(Microwave Monolithic Integrated Circuit)를 16개 전력 결합하여 100 W급 Ka대역 SSPA(Soild State Power Amplifier)를 개발하였다. 개발된 SSPA를 하나의 안테나를 이용하여송수신을 하는 Ka 대역 소형 레이다에 적용을 위해 수신 구간에 MMIC 게이트 전원을 제어하여 SSPA 잡음이 수신기에미치는 영향을 최소화 하였다. 또한 근접한 표적의 큰 수신신호에 의해 수신기가 포화되는 것을 막기 위해 SSPA의 출력전력을 약 20 dB 감소시키는 기능을 추가하였다. 개발된 SSPA는 10%, 40% 듀티비의 펄스 조건에서 각각 52.4 dBm, 51.6 dBm 이상의 첨두전력을 출력하였으며, 이때 전력효율은 각각 19.2%, 15.8% 이상이다.

특실병동 보호자 건강 상담을 통한 진료서비스 연계방안

서미희,박지윤,김혜진,김경숙,김설아,김지수 한국의료QA학회 2008 가을학술대회 Vol.2008 No.3

진단검사 전 처치로 실시하는 의식하 진정요법에 대한 환아 보호자의 인식도와 간호요구도, 간호만족도

서미희,박순주 한국융합학회 2021 한국융합학회논문지 Vol.12 No.12

This study aims to investigate the awareness, nursing needs, and nursing satisfaction of conscious sedation, and their relationships in the guardians of hospitalized children receiving conscious sedation. Data were collected from 120 guardians of children who were admitted to the pediatric ward of University Hospital C in D city from July 6 to October 6, 2016 and received conscious sedation as a pretreatment for diagnostic tests. The result showed that the guardians' awareness was relatively low (2.49±0.83) and nursing needs (4.53±0.40) was found to be significantly higher than nursing satisfaction (3.81±0.56)(p<.001). Awareness showed a significant positive correlation with nursing satisfaction (r=.18, p=.048) and there was a significant positive correlation between nursing needs and satisfaction (r=.20, p=.033). This result suggested that in order to improve the nursing satisfaction of the guardians, it is necessary to understand the awareness and nursing needs of the guardians on conscious sedation. In addition, the development of customized nursing intervention should be carried out based on the awareness and nursing needs. 본 연구는 환아 보호자를 대상으로 진단검사 전 처치로 실시하는 의식하 진정요법에 대한 인식도와 간호요구도, 간호만족도를 확인하고 변수들 간의 관계를 파악하기 위한 서술적 조사연구이다. 연구대상자는 D시에 있는 C대학병원 소아청소년과 병동에 입원하여 진단검사 전 처치로 의식하 진정요법을 받는 환아의 보호자 120명이다. 연구결과 대상자의 의식하 진정요법에 대한 인식도는 비교적 낮은 편이었고(2.49±0.83), 간호요구도(4.53±0.40)가 간호만족도(3.81±0.56)보다 유의하게 높게 나타났다(p<.001). 의식하 진정요법에 대한 인식도는 간호만족도와 유의한 양의 상관관계가 있었고(r=.18, p=.048), 간호요구도와 간호만족도도 유의한 양의 상관관계가 있었다(r=.20, p=.033). 의식하 진정요법에 대한 대상자의 간호만족도를 높이기 위해서는 의식하 진정요법에 대한 인식 정도와 간호요구 영역들을 먼저 확인하여 대상자의 요구를 기반으로 하는 맞춤형 간호중재가 제공되어야 할 것이다.

산의 나무를 죽이는 새벽 등산객들

서미희 사회발전연구소 1997 한국인 Vol.16 No.5

W대역 소형 레이다의 주파수 해상도 향상을 위한 위상잡음 분석

서미희,김현주,김소수 한국전자파학회 2022 한국전자파학회논문지 Vol.33 No.5

FMICW radars detect and track targets using frequency information based on the distance and velocity of the target. Therefore, the phase noise of the received signal and the frequency resolution must be minimized to ensure detection and tracking accuracy of the radars. However, as the signal frequency increases, the phase noise degrades. Therefore, the design requirement of the phase noise is important for radar using high-frequency signals. In this study, the phase noise of the transmission signal (FTX), local oscillation signal (FLO1, FLO2), and reference signal (Fref) are analyzed for application to a W-band compact radar. Additionally, phase-noise require- ments are derived to increase the frequency resolution of the radar within a range that can be implemented in a W-band transceiver.

저전력 홀추력기 플라즈마 진단 및 방전특성 연구

서미희,이종섭,강성민,김연호,선종호,최원호 한국진공학회 2009 한국진공학회 학술발표회초록집 Vol.37 No.-

MMIC 기반 Ka대역 주파수합성기 및 수신기 개발

서미희,정해창,나경일,김소수 한국인터넷방송통신학회 2023 한국인터넷방송통신학회 논문지 Vol.23 No.1

In this paper, the frequency synthesis(FS) MMIC and the receive MMICs were developed for a Ka-band compact radar. Also a compact Ka-band frequency synthesizer and a receiver were developed based on those MMICs. The FS MMIC and the wireless-receiver(WR) MMIC to receive the baseband frequency were manufactured by a 65 nm CMOS process and the front-end(FE) MMIC to receive the Ka-band frequency was manufactured by a 150 nm GaN process. Linear frequency modulation waveform and pulse waveform for the transmit signal were measured by output signal of frequency synthesizer. The measured performance of developed receiver including the FE MMICs and the WR MMIC were ≧ 80 dB gain, ≦ 6 dB noise figure and ≧ 10 dBm at OP1dB. The measurement results of the developed frequency synthesizer and the receiver including the manufactured MMICs showed that they could be applied to Ka-band compact radar.

알루미늄 합금의 복사방열향상을 위한 코팅연구

서미희(Mihui Seo),김동현(Donghyun Kim),이정훈(Junghoon Lee),정원섭(Wonsub Chung) 한국표면공학회 2013 한국표면공학회지 Vol.46 No.5

The aim of the present study was to improve the radiative heat dissipation of aluminum alloy, Al 1050. Resin/CuO coating and Cu/CuO composite plating were applied on aluminum alloy to improve the radiative heat dissipation. Resin/CuO coating was made using thermosetting silicon resin and Cu/CuO composite plating was made in pyrophosphate copper plating bath. Radiant heat flux(W/㎡) was measured by self-produced radiant heat measurement device to compare each specimen. The cross section of specimen and chemical bonding of surface were analyzed by FE-SEM, XPS and FT-IR. As a result, radiant heat of Resin/CuO coating was higher than Cu/CuO composite plating due to the adhesion with aluminum plate and the difference in chemical bonding. But, Both of them were higher than aluminum alloy. In order to confirm the result of experiment, aluminum plate, Resin/CuO coating and Cu/CuO composite plating sample were applied LED and measured the LED temperature. As a result, LED temperature of samples were matched previous results and confirmed coated samples were lower about 10 degrees than the aluminum alloy.

Fold 건축 특성 분석에 따른 Issey Miyake 패션의 Fold 특성

서미희 ( Meehee Seo ),윤정아 ( Jung A Yoon ),이연희 ( Younhee Lee ) 복식문화학회 2015 服飾文化硏究 Vol.23 No.5

This study examines the formative characteristics of Fold architecture and how its properties are shown in the fashion of the modern work of Issey Miyake through analysis. In this research, the Fold classification criteria for analysis features that appeared in Issey Miyake fashion features were established through research literature on Fold architecture and leading research. Empirical data collection was conducted for Issey Miyake``s work and collection by collecting photo materials, and design concepts and the results are analyzed in terms of features. Study ranges of Issey Miyake’s creative design development are Pleats Please, A-POC, 132.5 project, and collections from 2000 to 2014. The conclusion is as follows. First, design concepts presented in the Issey Miyake fashion features of Fold are Hybrid, topology, and uncertainty. Hybrid look for the meaning of fashion, which is the interaction between the wearer and garments. The concept of topology designs clothing, focusing on interrelationship of the body and clothing, and pays no attention to absolute size or the form of the clothing. The concept of uncertainty is an uncertain form that is infinitely expandable because all the elements have openness and uncertainty due to the determined incomplete state by the creator. Second, in the results presented in the Issey Miyake fashion features is the destruction of the boundary and diagram form. The destruction of the boundary is free from traditional clothing. The diagram form is a geometric form which does not create a Dart or Princess line.