• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.318-319
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• 2003

이동통신 시스템에서 데이터, 음성, 영상신호를 효율적으로 전송하기 위해 위상 배열 안테나(Phased-Array Antenna： PAA)에 관한 연구가 최근 국내외적으로 활발히 진행되고 있다. 광통신 기술을 이용한 PAA용 실시간 지연선로 (True Time-Delay： TTD)는 넓은 대역폭, 저 손실, 전자파 간섭에 무관, 소형화, 특히 ‘beam squintr´ 현상이 없는 장점이 있기 때문에 각광을 받고 있다. 특히, 신호의 간섭을 줄이기 위해 안테나 방사 패턴의 부엽 (side lobe)의 크기를 감소시킬 수 있는 안테나 설계기술이 필요하다. (중략)

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.182-187
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• 1992

This paper proposes a method by which the estimated values of the unknown parameters of system are converged to the true values in finite time using adaptive deadbeat controller. After those are converged to the true values, the deviation from these values do not virtually exist or, if any, extremely small. Also we apply this technique of deadbeat convergence to a system contaminated with white noise or colored noise. It is shown that the estimated parameters of those systems approach the true values in finite time even though the performance do not match perfectly with the system without noises.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2405-2423
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• 2012

In a traditional Single Sign-On (SSO) scheme, the user and the Service Providers (SPs) have given their trust to the Identity Provider (IdP) or Authentication Service Provider (ASP) for the authentication and correct assertion. However, we still need a better solution for the local/native true SSO to gain user confidence, whereby the trusted entity must play the role of the ASP between distinct SPs. This technical gap has been filled by Trusted Computing (TC), where the remote attestation approach introduced by the Trusted Computing Group (TCG) is to attest whether the remote platform integrity is indeed trusted or not. In this paper, we demonstrate a Trustworthy Mutual Attestation (TMutualA) protocol as a proof of concept implementation for a local true SSO using the Integrity Measurement Architecture (IMA) with the Trusted Platform Module (TPM). In our proposed protocol, firstly, the user and SP platform integrity are checked (i.e., hardware and software integrity state verification) before allowing access to a protected resource sited at the SP and releasing a user authentication token to the SP. We evaluated the performance of the proposed TMutualA protocol, in particular, the client and server attestation time and the round trip of the mutual attestation time.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.68-69
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• 2006

When an alloy such as Ni-W is liquid phase sintered, heavy solid W particles sedimentate to the bottom of the container, provided that their volume fraction is less than a critical value. The sintering process evolves typically in two stages, diffusiondriven macrosegregation sedimentation followed by true sedimentation. During macrosegregation sedimentation, the overall solid volume fraction decreases concurrently with elimination of liquid concentration gradient. However, in the second stage of true sedimentation, the average solid volume fraction in the mushy zone increases with time. It is proposed that the true sedimentation results from particle rearrangement for higher packing efficiency.

• Bulletin of the Korean Chemical Society
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• 제14권2호
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• pp.255-258
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• 1993

Molecular dynamics (MD) calculations were carried out in order to investigate the effect of MD cell size to predict the melting phenomena of A-type zeolite. We studied two model systems: a pseudocell of $(T_2O_4Na)_n$, (L= 12.264 $^{\AA}$, N= 84) and a true-cell of (SiAlO$_4Na)_n$. (L= 24.528 $^{\AA}$, N= 672), where T is Si or Al. The radial and bond angle distribution functions of T(Si, Al)-O-T(Si, Al) and diffusion coefficients of T and O were reported at various temperatures. For the true-cell model, the melting temperature is below 1500 K and probably around 1000 K, which is about 600-700 K lower than the pseudocell model. Although it took more time (about 30 times longer) to obtain the molecular trajectories of the true-cell model than those of the pseudocell model, the true-cell model gave more realistic structural transition for the A-type zeolite, which agrees with experiment.

• 한국광학회지
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• 제13권4호
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• pp.289-294
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• 2002

2${\times}$2 MEMS 스위치와 광섬유 지연선로의 조합으로 구성된 위상배열 안테나(Phased-Array Antenna: PAA)용 광학적인 실시간 지연선로(True Time-Delay : TTD)를 제안하였으며, $30^{o}$의 분해능을 갖고 최대 $120^{o}$까지 빔 주사방향을 조정 할 수 있는 선형 PAA 용 실시간 지연선로를 구현하였다. 본 구조는 제어가 간편하며, 한 개의 파장 고정 레이저 다이오드를 사용하기 때문에 기존에 제안된 파장 가변 광원을 사용하는 구조들보다 고속 동작이 가능하고, 경제적이라는 장점을 갖고 있다. 또한, 제안된 실시간 지연선로는 각각 연결된 안테나 소자 4개로 구성된 10㎓용 PAA를 설계하였다. 전산 모의 실험 결과, 설계된 PAA의 최대 빔 이득은 빔 주사각이 0˚인 경우에는 11.6dB, $\pm$$30^{o}$일 때 11.2dB, 그리고 $\pm$$60^{o}$에서 10.6dB로 나타났다.

• 한국전자파학회논문지
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• 제28권11호
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• pp.924-927
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• 2017

본 논문에서는 6~18 GHz 대역 8-비트 true time delay(TTD) 회로의 설계 및 측정결과에 대하여 기술하였다. 단위 지연 회로는 상대적으로 시간 지연 변화율이 일정한 m-유도 필터(m-derived filter)를 이용하였다. 설계한 8-비트 TTD는 2개의 single-pole double-throw(SPDT)와 7개의 double-pole double-throw(DPDT) 스위치로 구현하였으며, 인덕터를 이용하여 반사 특성을 개선하였다. 설계된 8-비트 TTD는 $0.18{\mu}m$ CMOS 공정을 이용하여 제작하였다. 측정된 TTD 회로의 시간 가변 범위는 250 ps이고, 시간 지연 해상도는 약 1 ps이다. 6~18 GHz의 동작 주파수에서 RMS 시간 지연 오차는 11 ps 미만이며, 입출력 반사 손실은 10 dB 이상이다. 공급 전압은 1.8 V이며, 소비 전력은 0.0 mW이다. 칩 면적은 $2.36{\times}1.04mm^2$이다.

• 대한치과보철학회지
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• 제14권1호
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• pp.11-16
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• 1976

Casts are often transferred to the articulator by arbitrary means, because the method of locating the true hinge axis point thought to be a complicated and time consuming procedure, and because the importance and significance of the true hinge axis in the construction of dental prosthesis is not sufficiently understood. In this report, the author constructed the hinge axis locator and determined the variations in location of the true hinge axis points from the location of the hinge axis point determined by arbitrary means. For this report, the procedure was followed on 50 persons with normal occlusion and sound T.M.J. function, so 100 true hinge axis points were recorded and compared with the arbitrary hinge axis point. The results obtained were as follows. 1. The mean distance from the arbitrary hinge axis point to the true hinge axis point was as follows. Right; (O)5.17mm., (V)3.44mm., (H)3.55mm.. Left; (O)5.63mm., (V)3.95mm., (H)3.51mm.. 2. The percentage of true hinge axis points classified at intervals of 2mm was as follows. 0-2mm; 4%, 2-4mm; 21%, 4-6mm; 37%, 6-8mm; 26%, 8-10mm; 10%, Over 10mm; 2%. And only 50% of the 100 true hinge axis points were located within a 5mm. radius of the arbitrary hinge axis point. 3. Instead of transferring the casts to the articulator by arbitrary means, the careful location of the true hinge axis points is recommended to avoid potential sources of error in mounting casts.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.21-24
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• 2001

In this paper, we present a fast face detection algorithm by estimating the eye region using neural network. To implement a real time face detection system, it is necessary to reduce search space. We limit the search space just to a few pairs of eye candidates. For the selection of them, we first isolate possible eye regions in the fast and robust way by modified histogram equalization. The eye candidates are paired to form an eye pair and each of the eye pair is estimated how close it is to a true eye pair in two aspects : One is how similar the two eye candidates are in shape and the other is how close each of them is to a true eye image A multi-layer perceptron neural network is used to find the eye candidate region's closeness to the true eye image. Just a few best candidates are then verified by eigenfaces. The experimental results show that this approach is fast and reliable. We achieved 94% detection rate with average 0.1 sec Processing time in Pentium III PC in the experiment on 424 gray scale images from MIT, Yale, and Yonsei databases.

• 한국광학회지
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• 제30권3호
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• pp.94-100
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• 2019

본 연구에서는 광 지연선로를 이용한 스퀸팅(squinting)이 없는 위상배열 안테나의 근접장 미세파장 포커싱(subwavelength focusing)을 디자인하고 전산모사를 통해 검증하였다. 마이크로파 파장에서 위상배열 안테나의 수치적 계산을 위해 호이겐스-프레넬(Huygens-Fresnel) 원리를 적용하였다. 제안하는 시스템은 첩 광섬유 격자(chirped fiber grating)에 기반한 광 지연선로를 이용하여 빔 스퀸팅이 생기지 않는다는 것을 전산모사를 통해 확인하였다. 그리고 개별 안테나의 배열은 광학렌즈시스템에서 회절 소자로 간주할 수 있음에 착안해 높은 개구율(numerical aperture)을 구현하고 미세파장 포커싱을 얻었다. 또한, 위상배열 안테나의 안테나 사이 거리를 반파장 이하로 줄여 사이드 로브를 억제할 수 있음을 보였다.