• 한국광학회지
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• 제14권3호
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• pp.306-311
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• 2003

본 논문에서는 광전송시스템에서 파장분할다중화 광소자로 사용되는 박막필터형 광소자의 특성 분석 및 평가를 위해 입력광원을 모델링 하였으며 광경로에 대해 광선추적법을 사용하여 전산모의 한 광특성을 실험과 비교, 분석하였다. 그 결과 입력광원에 대한 cell 방식의 모델링이 결합효율의 정확도 및 가우시안 강도분포에 접근성을 볼 때 마이크로 옵틱스형 광소자 분석함에 있어 적합함을 알 수 있다. 박막필터형 광소자에 대한 최적 전산모의 결과 광섬유와 GRIN 렌즈 사이 거리가 0.24mm이며 GRIN 렌즈와 박막필터 사이 거리가 0.25mm일 때 최대 결합효율은 -0.11 ㏈이었으며 동일한 조건에의 실험결과 -0.35 ㏈의 최대 결합효율을 얻었다. 이것은 단심 및 이심페룰, GRIN 렌즈 등과 같은 구성품의 불완전성과 박막필터에 의한 손실을 고려할 때, 전산모의 결과와 매우 일치하는 것으로서 본 연구에서 제안한 입력광원의 모델링을 적용한 전산모의가 박막필터형 광소자의 특성을 예측할 수 있음을 보였다.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1210-1210
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• 2001

On farm analysis of protein, moisture and oil in cereals and oil seeds is quickly being adopted by Australian farmers. The benefits of being able to measure protein and oil in grains and oil seeds are several : $\square$ Optimize crop payments $\square$ Monitor effects of fertilization $\square$ Blend on farm to meet market requirements $\square$ Off farm marketing - sell crop with load by load analysis However farmers are not NIR spectroscopists and the process of calibrating instruments has to the duty of the supplier. With the potential number of On Farm analyser being in the thousands, then the task of calibrating each instrument would be impossible, let alone the problems encountered with updating calibrations from season to season. As such, NIR technology Australia has developed a mechanism for \ulcorner\ulcorner\ulcorner their range of Cropscan 2000G NIR analysers so that a single calibration can be transferred from the master instrument to every slave instrument. Whole grain analysis has been developed over the last 10 years using Near Infrared Transmission through a sample of grain with a pathlength varying from 5-30mm. A continuous spectrum from 800-1100nm is the optimal wavelength coverage fro these applications and a grating based spectrophotometer has proven to provide the best means of producing this spectrum. The most important aspect of standardizing NIB instruments is to duplicate the spectral information. The task is to align spectrum from the slave instruments to the master instrument in terms of wavelength positioning and then to adjust the spectral response at each wavelength in order that the slave instruments mimic the master instrument. The Cropscan 2000G and 2000B Whole Grain Analyser use flat field spectrographs to produce a spectrum from 720-1100nm and a silicon photodiode array detector to collect the spectrum at approximately 10nm intervals. The concave holographic gratings used in the flat field spectrographs are produced by a process of photo lithography. As such each grating is an exact replica of the original. To align wavelengths in these instruments, NIR wheat sample scanned on the master and the slave instruments provides three check points in the spectrum to make a more exact alignment. Once the wavelengths are matched then many samples of wheat, approximately 10, exhibiting absorbances from 2 to 4.5 Abu, are scanned on the master and then on each slave. Using a simple linear regression technique, a slope and bias adjustment is made for each pixel of the detector. This process corrects the spectral response at each wavelength so that the slave instruments produce the same spectra as the master instrument. It is important to use as broad a range of absorbances in the samples so that a good slope and bias estimate can be calculated. These Slope and Bias (S'||'&'||'B) factors are then downloaded into the slave instruments. Calibrations developed on the master instrument can then be downloaded onto the slave instruments and perform similarly to the master instrument. The data shown in this paper illustrates the process of calculating these S'||'&'||'B factors and the transfer of calibrations for wheat, barley and sorghum between several instruments.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.594-597
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• 2012

전체 전송로 중간에 광 위상 공액기 (OPC; optical phase conjugator)를 둔 광전송 링크에서 파장 분할 다중 (WDM; wavelength division multiplexed) 송신기부터 OPC까지의 전반 전송 구획과 OPC부터 WDM 수신부까지의 후반 전송 구획 각각을 구성하는 단일 모드 광섬유 (SMF; single mode fiber)의 중계 구간 (span)들 중 단지 하나의 중계 구간에서만 RDPS(residual dispersion per span)만 갖고 나머지 중계 구간에서는 RDPS가 0 ps/nm로 설계된 전송 링크에서 WDM 신호를 최상의 성능으로 전송하기 위한 최적의 링크 구조를 도출하였다.

• 한국정밀공학회지
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• 제24권12호
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• pp.50-56
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• 2007

Femtosecond laser ablation of the Invar alloy and hole drilling for a shadow mask are studied. We used a regenerative amplified Ti-sapphire laser with a 1kHz repetition rate, 184fs pulse duration and 785nm wavelength. Femtosecond laser pulse was irradiated on the Invar alloy with air blowing at the condition of various laser peak power. An ablation characteristic of the Invar alloy was appeared non-linear at $125J/cm^2$ of energy fluence. For the application to a shadow mask, the hole drilling of the Invar alloy with the cross section of a trapezoidal shape was investigated. The ablated micro-holes were characterized using an atomic force microscopy(AFM). The optimal condition of hole pattern f3r a shadow mask was $4\;{\mu}m$ z-axis feed rate, 0.2mm/s circular velocity, $26.4{\mu}J$ laser peak power. With the optimal processing condition, the fine circular hole shape without burr and thermal damage was achieved. Using the femtoseocond laser system, it demonstrates excellent tool for the Invar alloy micro-hole drilling without heat effects and poor edge.

• 한국정밀공학회지
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• 제27권11호
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• pp.17-23
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• 2010

Titanium alloy is one of the hard processing materials made by the traditional manufacturing method because of the excellent mechanical strength. Ablation of titanium alloy is investigated by using a femtosecond laser which is a regenerative amplified Ti:sapphire laser with 1kHz repetition rate, 184fs pulse duration time and 785nm wavelength. Experiments are carried out under various ablation conditions with different pulse overlap ratios for the rectangular shape and micro hole. Test results show that the ablation characteristic according to pulse overlap ratio of titanium alloy seems to be as non-linear type at the different zone of energy fluence. The optimal condition of rectangular shape processing is obtained at the laser peak power 1.3mW, pulse overlap ratio of 90%, beam gap of $1\;{\mu}m$. The micro hole has a good quality from the pulse overlap ratio of 99% at the same laser peak power. With the optimal processing condition, the fine rectangular shape and micro hole without burr and thermal damage are achieved.

• 전기학회논문지P
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• 제58권4호
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• pp.455-460
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• 2009

A number of factors combine to make ultraviolet radiation a superior means of water purification for ground water, rainwater harvesting systems and so on. Ultraviolet radiation is capable of destroying all types of bacteria. Additionally, ultraviolet radiation disinfects rapidly without the use of heat or chemical additives which may undesirably alter the composition of water. In a typical operation, water enters the inlet of a UV lamp and flows through the annular space between the quartz sleeve and the outside chamber wall. The irradiated water leaves through the outlet nozzle. Several design features are combined to determine the dosage delivered. The first is Wavelength output of the lamp, the Second is Length of the lamp - when the lamp is mounted parallel to the direction of water flow, the exposure time is proportional to the length of the lamp, the third is Design water flow rate - exposure time is inversely related to the linear flow rate, the forth is Diameter of the purification chamber - since the water itself absorbs UV energy, the delivered dosage diminishes logarithmically with the distance from the lamp. In this paper, It describe the how to design optimal UV disinfection device for ground water and rainwater. To search the optimal design method, it was performed computer simulation with 3D-CFD discrete ordinates model and manufactured prototype. Using proposed design method manufactured prototype applied to disinfection test and proved satisfied performance.

• 한국음향학회지
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• 제20권3호
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• pp.83-90
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• 2001

기존의 탄성표면파 듀플렉서 필터는 1/4 파장 정합선로를 이용한 격리회로를 이용하기 때문에 패키지 상에 스트립 라인을 구성하는 제작상의 어려움이 있다. 송수신 필터와 격리회로를 따로 제작하여 조립하기 때문에 제작공정 또한 복잡하다. 본 연구에서는 격리회로가 송신용, 수신용 필터와 함께 하나의 단일 칩 위에 위치할 수 있는 새로운 형태의 탄성표면파 듀플렉서 필터를 설계하였다. 이러한 형태의 듀플렉서를 구성하기 위하여, 개별 탄성표면파 사다리형 필터와 집중소자인 인덕터와 캐패시터로 구성되는 격리회로망을 설계하였고, 듀플렉서의 전체 성능을 최적화할 수 있는 적절한 목표함수를 세워, 이를 비선형 다차원 최소화 방법을 통하여 최적화하였다. 그 결과 상용제품보다 더 우수한 성능이 구현됨을 확인하였다.

• KSBB Journal
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• 제8권2호
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• pp.143-149
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• 1993

Activated carbons were used to examine their performance for the separation of undesirable colored materials from culture broth containing hyaluronic acid. Six local samples and a NORIT ROX 08 were tested, whereas the latter was mainly studied under batch and continuous modes. The optimal wavelength for the detection of colored materials was 330nm. The optimal choice of NORIT ROX 08 provided 30% colored residuals with 96% hyaluronic acid recovery of original broth in batch experiments. The nonlinear adsorption behavior of protein and colored materials with activated carbon (C) was correlated by a Langmuir equation to give 18C/24+C and 500C/892+C for protein and colored materials, respectively. It appears that colored materials were composed of 78% protein and 22% glucose residuals on the basis of clearance results. A microscopic study using a scanning electron microscope suggests that regeneration of used activated carbon with 0.1N NaOH and hot water was not satisfactory. The present study proposes that the continuous monitoring of colored materials during purification can be accomplished by Installation of a UV monitor commonly used for continuous detection of protein during the process, as resulted from the significant correlation of color (A330)=0.353protein(mg/ml)+0.1(R=99.7%).

• Journal of Biosystems Engineering
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• 제23권6호
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• pp.561-570
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• 1998

The MLR(Multiple Linear Regression) models to estimate soluble solids content non-destructively were presented to make a selection of optimal photosensor utilized to measure the soluble solids content of apples. Visible and NIR absorbance in the 400 to 2498 nanometer(nm) wavelength region, soluble solids content(sugar content), hardness, and weight were measured for 400 apples(gala). Spectrophotometer with fiber optic probe was utilized for spectrum measurement and digital refractometer was used for soluble solids content. Correlation between absorbance spectrum and soluble solids content was analyzed to pick out the optimal wavelengths and to develop corresponding prediction model by means of MLR. For the coefficient of determination($R^2$) to be over 0.92, the MLR models out of the original absorbance were built based on 7 wavelengths of 992, 904, 1096, 1032, 880, 824, 1048nm, and the ones of the second derivative absorbance based on 5 wavelengths of 784, 1056, 992, 808, 872nm. The best model of the second derivative absorbance spectrum had $R^2$=0.91, bias= -0.02bx, SEP=0.28bx for unknown samples.

• Journal of Biosystems Engineering
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• 제38권3호
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• pp.199-207
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• 2013

Purpose: Tomatoes, an important agricultural product in fresh-cut markets, are sometimes a source of foodborne illness, mainly Salmonella spp. Growth cracks on tomatoes can be a pathway for bacteria, so its detection prior to consumption is important for public health. In this study, multispectral Visible/Near-Infrared (NIR) reflectance imaging techniques were used to determine optimal wavebands for the classification of defect tomatoes. Methods: Hyperspectral reflectance images were collected from samples of naturally cracked tomatoes. To classify the resulting images, the selected wavelength bands were subjected to two-band permutations, and a supervised classification method was used. Results: The results showed that two optimal wavelengths, 713.8 nm and 718.6 nm, could be used to identify cracked spots on tomato surfaces with a correct classification rate of 91.1%. The result indicates that multispectral reflectance imaging with optimized wavebands from hyperspectral images is an effective technique for the classification of defective tomatoes. Conclusions: Although it can be susceptible to specular interference, the multispectral reflectance imaging is an appropriate method for commercial applications because it is faster and much less expensive than Near-Infrared or fluorescence imaging techniques.