• Title/Summary/Keyword: optimal wavelength

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Absorptance and Electrical Properties Evaluation of Nickel Layer Deposited onto Thin Film Pyroelectric PZT IR Detector (PZT박막 적외선 감지소자의 적외선 흡수층으로 증착된 니켈 박막의 광학 및 전기적 특성 분석)

  • Ko, Jong-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.11
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    • pp.1727-1732
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    • 2004
  • A nickel layer was deposited onto the PZT thin films, serving both as a selective radiation absorption layer and as a top electrode. The absorption properties of such nickel coated multi-layered infrared detectors were studied in the visible and infrared wavelength ranges. The optimal thickness of the nickel layer on our substrate was 10nm. The maximum absorption coefficient of the deposited 10nm thick nickel layer was 0.7 at a 632nm wavelength. However, a striking asymmetric polarization hysteresis loop was observed in these PZT thin films with nickel as the top electrode. This asymmetric polarization was attributed to the difference between the dynamic pyroelectric responses in these Ni/PZT/Pt films poled either positively or negatively before the measurement. A positively poled film showed a 40% higher voltage response than a negatively poled detector.

Spectrum Properties of Inductively Coupled Argon Plasma (유도결합형 플라즈마에서의 아르곤 가스의 스펙트럼 특성)

  • Lee, Young-Hwan;Pack, Kwang-Hyeon;Choi, Yong-Sung;park, Dae-Hee
    • Proceedings of the KIEE Conference
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    • 2004.11a
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    • pp.147-149
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    • 2004
  • Inductively coupled plasma is commonly used for electrodeless lamp due to its ease of plasma generation. Optical characteristics significantly depend on the RF power and gas pressure of the plasma. This paper describes the measurement of spectrum as a function of RF power and gas pressure with a goal of finding optimal operating conditions of the electrodeless lamp. The gas pressure was varied from 10 [mTorr] to 100 [mTorr] and the RF power was varied from 10 [W] to 120 [W]. It was found that the intensity of wavelength tends to be decreased when argon pressure is increased, and the intensity of wavelength is increased as RF power is increased.

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A Study on Optimal RWA Algorithms for Differentiated Service in DWDM Networks (DWDM 망에서 차등화 서비스를 위한 최적의 RWA 알고리즘 연구)

  • Lee, Ik-Seob;Song, Hyun-Su;Bae, Jung-Hyun;Kim, Sung-Un
    • Proceedings of the Korea Information Processing Society Conference
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    • 2002.04b
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    • pp.1377-1380
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    • 2002
  • 차세대 인터넷 백본망에서 DWDM(Dense Wavelength Division Multiplex) 기술은 네트워크의 증가하는 사용자 수와 요구 대역폭을 수용하기 위한 방법으로 빠르게 수용되고 있다. RWA(Routing and Wavelength Assignment) 문제는 DWDM 네트워크에서 효율적인 자원 활용 측면에서 최적의 경로 선택과 파장 할당을 위해 중요하다. 하지만 제안된 RWA 알고리즘은 네트워크의 혼잡 상황에 대한 고려가 미비하여 네트워크의 혼잡 시 성능이 제한적이다. 이를 위해 본 논문에서는 미래의 잠재적인 연결 요구에 가장 영향을 줄이는 경로를 설정하는 MIPR(Minimuim Interference Path Routing) 알고리즘을 제안한다. 또, 제안된 알고리즘을 이용하여 IP 차등화 서비스에서 QoS(Quality of Service) 제공을 위해 서비스 타입별로 차등화 된 라우팅 방법을 제공한다.

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Dynamic Characteristics of Gain-Clamped L-band EDFA with Bi-directional Pumps (양방향 펌프구조 고정이득 L-band EDFA의 과도응답 특성)

  • Kim, Ik-Sang
    • The Journal of Engineering Research
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    • v.5 no.1
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    • pp.119-133
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    • 2004
  • The gain-clamped EDFA has been developed to eliminate the output power change of WDM surviving channels to occur with added or dropped channels, which degrades the performance of EDM optical network. It maintains the constant gain of surviving channels when WDM channels are added or dropped in a network amplifying node. In this paper, the bi-directionally pumped gain-clamped EDFA is implemented to compensate the change of the input power by a lasing. The results show that the alsing of a short wavelength and backward propagation is the optimal condition to minimize the transient response of surviving channels in terms of the overshoot and gain saturation sue to the inhomogeneous broadening effect.

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Optimization of the Emission Spectrum of Red Color in Quantum Dot-Organic Light Emitting Diodes

  • Jeong, Byoung-Seong
    • Applied Chemistry for Engineering
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    • v.32 no.2
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    • pp.214-218
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    • 2021
  • We investigated the optimal stacked structure from the perspective of process architecture (PA) through emission spectrum analysis according to the wavelength of quantum dot (QD)-organic light-emitting diodes (OLED). We confirmed that the blue-light leakage through the QD can be minimized by increasing the QD filling density above a critical value in the red QD (R-QD) layer. In addition, when the thickness of red-color filter (R-CF) at the upper part of the R-QD increased to more than 3 ㎛, the leakage of blue light through the R-CF was effectively blocked, and a very sharp emission spectrum in the red wavelength band could be obtained. According to these outstanding results, we expect that the development of QD-OLED displays with very excellent color gamut can be possibly realized.

Performance of WDM Signals in Optical Links with Random Distribution of Residual Dispersion Per Span only in Half Transmission Section of Total Length (전송 반 구획에서만 중계 구간 당 분산이 랜덤하게 분포하는 광 링크에서의 WDM 신호의 성능)

  • Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • v.16 no.3
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    • pp.440-448
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    • 2012
  • Optimal net residual dispersion (NRD) and effective launching power range of optical transmission links with optical phase conjugator (OPC) and dispersion management (DM) for compensating the distorted wavelength division multiplexing (WDM) signals due to interaction of group velocity dispersion (GVD) and optical nonlinear effects. WDM systems considered in this research have optical links with the random distribution of residual dispersion per span (RDPS) in each single mode fiber (SMF) spans of only one half transmission section for designing the adaptive optical transmission system configurations. It is confirmed that optimal NRD is 10 ps/nm and effective launching power range is obtained to be -8~1 dBm under NRD = 10 ps/nm in optical links with total dispersion controlled by precompensation. And, it is also confirmed that optimal NRD is -10 ps/nm and effective launching power range is obtained to be -7.5~1 dBm under NRD = -10 ps/nm in optical links with total dispersion controlled by postcompensation.

Compensation for Distorted WDM Signals Through Dispersion Managed Optical Transmission Links with Ununiform Distribution of SMF Length and RDPS of Optical Fiber Spans (중계 구간의 SMF 길이와 RDPS 분포가 일정하지 않은 분산 제어 광전송 링크를 통한 왜곡된 WDM 신호의 보상)

  • Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • v.16 no.5
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    • pp.801-809
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    • 2012
  • Dispersion management (DM) is the typical technique compensating for the distorted signals due to interaction of group velocity dispersion (GVD) and optical nonlinear effects for transmitting wavelength division multiplexed (WDM) channel with the excellent performance. Optimal net residual dispersion (NRD) and effective launching power range of optical transmission links with random distribution and artificial distribution of single mode fiber (SMF) length and residual dispersion per span (RDPS) required to flexibly design of optical links in DM. It is confirmed that optimal net residual dispersion (NRD) are +10 ps/nm and -10 ps/nm controlled by precompensation and postcompensation, respectively, in both of the considered distribution patterns of SMF length and RDPS. And, in optimal NRD, system performance in optical links with the descending distribution of SMF length and the ascending distribution of RDPS among the artificial distribution patterns are more improved, consequently, effective launching power range is expanded by almost 2 dB than those in optical links with the uniform distribution.

Rancidity Prediction of Soybean Oil by Using Near-Infrared Spectroscopy Techniques

  • Hong, Suk-Ju;Lee, Ah-Yeong;Han, Yun-hyeok;Park, Jongmin;So, Jung Duck;Kim, Ghiseok
    • Journal of Biosystems Engineering
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    • v.43 no.3
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    • pp.219-228
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    • 2018
  • Purpose: This study evaluated the feasibility of a near-infrared spectroscopy technique for the rancidity prediction of soybean oil. Methods: A near-infrared spectroscopy technique was used to evaluate the rancidity of soybean oils which were artificially deteriorated. A soybean oil sample was collected, and the acid values were measured using titrimetric analysis. In addition, the transmission spectra of the samples were obtained for whole test periods. The prediction model for the acid value was constructed by using a partial least-squares regression (PLSR) technique and the appropriate spectrum preprocessing methods. Furthermore, optimal wavelength selection methods such as variable importance in projection (VIP) and bootstrap of beta coefficients were applied to select the most appropriate variables from the preprocessed spectra. Results: There were significantly different increases in the acid values from the sixth days onwards during the 14-day test period. In addition, it was observed that the NIR spectra that exhibited intense absorption at 1,195 nm and 1,410 nm could indicate the degradation of soybean oil. The PLSR model developed using the Savitzky-Golay $2^{nd}$ order derivative method for preprocessing exhibited the highest performance in predicting the acid value of soybean oil samples. onclusions: The study helped establish the feasibility of predicting the rancidity of the soybean oil (using its acid value) by means of a NIR spectroscopy together with optimal variable selection methods successfully. The experimental results suggested that the wavelengths of 1,150 nm and 1,450 nm, which were highly correlated with the largest absorption by the second and first overtone of the C-H, O-H stretch vibrational transition, were caused by the deterioration of soybean oil.

Optimization of Net Residual Dispersion and Launching Power Depend on Total Transmission Length and Span Length in Optical Transmission Links with Dispersion Management and Optical Phase Conjugation (분산 제어와 광 위상 공액이 적용된 광전송 링크에서 총 전송 거리와 중계 간격에 따른 전체 잉여 분산과 입사 전력의 최적화)

  • Lee, Seong-Real
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.12B
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    • pp.1433-1441
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    • 2011
  • Design rules of optical transmission links with dispersion management (DM) and optical phase conjugation (OPC) for compensating optical signal distortion due to chromatic dispersion and self phase modulation (SPM) of single mode fiber (SMF) are investigated in this paper. Design rules consist of optimal net residual dispersion (NRD) and optimal range of launching power of wavelength division multiplexed (WDM) channels as a function of total transmission length and span length. In all considered total transmission length and span length, optimal NRD are obtained to +10 ps/nm and -10 ps/mn for transmission links, which is controlled by precompensation and postcompensation, respectively. It is confirmed that system performances are more improved and effective NRD for wide launching power have wider range as total transmission length and span length are more decreased.

Classification of Convective/Stratiform Radar Echoes over a Summer Monsoon Front, and Their Optimal Use with TRMM PR Data

  • Oh, Hyun-Mi;Heo, Ki-Young;Ha, Kyung-Ja
    • Korean Journal of Remote Sensing
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    • v.25 no.6
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    • pp.465-474
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    • 2009
  • Convective/stratiform radar echo classification schemes by Steiner et al. (1995) and Biggerstaff and Listemaa (2000) are examined on a monsoonal front during the summer monsoon-Changma period, which is organized as a cloud cluster with mesoscale convective complex. Target radar is S-band with wavelength of 10cm, spatial resolution of 1km, elevation angle interval of 0.5-1.0 degree, and minimum elevation angle of 0.19 degree at Jindo over the Korean Peninsula. For verification of rainfall amount retrieved from the echo classification, ground-based rain gauge observations (Automatic Weather Stations) are examined, converting the radar echo grid data to the station values using the inverse distance weighted method. Improvement from the echo classification is evaluated based on the correlation coefficient and the scattered diagram. Additionally, an optimal use method was designed to produce combined rainfalls from the radar echo and Tropical Rainfall Measuring Mission Precipitation Radar (TRMM/PR) data. Optimal values for the radar rain and TRMM/PR rain are inversely weighted according to the error variance statistics for each single station. It is noted how the rainfall distribution during the summer monsoon frontal system is improved from the classification of convective/stratiform echo and the use of the optimal use technique.