• Structural Engineering and Mechanics
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• 제69권1호
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• pp.51-67
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• 2019

In this paper, the anisotropy of tensile behaviours of layered rocks consisting internal notch has been investigated using particle flow code. For this purpose, firstly calibration of PFC2D was performed using Brazilian tensile strength. Secondly Brazilian test models consisting bedding layer was simulated numerically. Thickness of layers was 10 mm and layered angularity was $90^{\circ}$, $75^{\circ}$, $60^{\circ}$, $45^{\circ}$, $30^{\circ}$, $15^{\circ}$ and $0^{\circ}$. The strength of bedding interface was too high. Each model was consisted of one internal notch. Notch length is 1 cm, 2 cm and 4 cm and notch angularities are $60^{\circ}$, $45^{\circ}$, $30^{\circ}$, $15^{\circ}$ and $0^{\circ}$. Totally, 90 model were tested. The results show that failure pattern was affected by notch orientation and notch length. It's to be noted that layer angle has not any effect on the failure pattern. Also, Brazilian tensile strength is affected by notch orientation and notch length.

• 한국의학물리학회지:의학물리
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• 제24권4호
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• pp.253-258
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• 2013

본 연구의 목적은 electronic portal imaging device (EPID)를 통하여 방사선 치료를 받는 환자로부터 투과해 나오는 선량으로 외부적인 선량 재구성과 몬테카를로 전산모사로부터 도출되는 내부 선량 계측과의 관계를 도출하고 이를 분석하기 위한 연구로 진행되었다. 본 연구는 전산모사 연구로써 두 가지의 경우를 비교 분석하고 이와 비슷한 연구에 대한 기본적인 지표를 제공하고자 시행되었다. 실험에 관한 기하학적 정보와 방사선 소스에 대한 정보를 몬테카를로 전산모사 툴인 Monte Carlo n-particle (MCNPX)에 입력하였고 EPID 이미지 도출을 위하여 MCNPX 내에 tally카드를 이용하여 선량정보를 도출하고 이를 영상화 할 수 있도록 하였다. 또한 내부적인 계측을 위하여 물 팬텀을 소스와 표면의 거리(source to surface distance, SSD)가 100 cm이 되도록 설정하였으며, 그보다 10 cm 아래에 EPID를 위치시켰다. 내부 계측은 물팬텀 자체에서 흡수되는 흡수 선량을 mesh tally로 수집하였고, 4문 조사를 통하여 중첩된 선량에 대한 데이터를 획득하였다. 그와 동시에 EPID에서 물을 투과해 나오는 선량을 획득 한 뒤 역 투사 방법을 사용하여 선량 재구성을 하였다. 이둘의 경우를 비교하기 위해 자체적인 교정(calibration)을 통하여 투과해 나온 선량과 흡수된 선량과의 관계를 비교하고 4문 조사를 통하여 물 팬텀 내의 특정 부분에 대한 중첩된 선량 데이터와 EPID를 통해 재구성한 선량 데이터를 분석하였다. 물 팬텀과 EPID에서 획득한 누적 선량의 합은 각각 평균 3.4580 MeV/g과 3.4354 MeV/g이었다. 이는 앞서 계측된 물 팬텀 내부의 누적 선량과 0.6536% 선량 오차를 보였다.

• Food Science and Biotechnology
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• 제14권4호
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• pp.456-460
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• 2005

To enforce the maximum residue limit for residual hexane (0.005 g/kg) in commercially available Korean vegetable oil, convenient and accurate quantification methods were investigated. Using dual surrogate standards, pentane and heptane were dissolved in ethanol, and then added to hexane-tree sunflower oil for setting up the calibration curve. Gas Chromatograph-Flame Ionization Detector with a porous layer open tubular column, indicated good chromatographic separation of hexane from other inhibiting matrix components. The lowest calibration level was $0.5\;{\mu}g/g$, not exceeding a relative standard deviation of 10% (RSD%), and 1.0\;{\mu}g/g$ not exceeding a deviation of 22% RSD% using heptane as an internal standard for the Static headspace analysis by using a headspace auto-sampler and manual injection, respectively. The residual hexane was detected in nine of the samples among 87 vegetable oil samples purchased on the local market.

• 제어로봇시스템학회논문지
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• 제7권10호
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• pp.837-842
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• 2001

In this paper, we design and implement the DC characteristic measurement system for semiconductor devices. The proposed system is composed of 4 SMU(Source and Measure Unit) channels. Various efforts in hardware and software have been made to reduce the measurement errors. Internal and external sources of errors in measurement system especially in pA range measurement have been identified and removed. Also, various digital signal processing techniques are developed. Calibration is executed under the control of microprocessor periodically. Experimental results show that the implemented system can measure the DC characteristic of semiconductor devices with less than 0.2% error in various voltage and current source/measurement range.

• 한국작물학회지
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• 제51권spc1호
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• pp.304-309
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• 2006

Near infrared reflectance spectroscopy (NIRS) was used to develop a rapid and nondestructive method for the determination of fatty acid composition in sesame (Sesamum indicum L.) seed oil. A total of ninety-three samples of intact seeds were scanned in the reflectance mode of a scanning monochromator, and reference values for fatty acid composition were measured by gas-liquid chromatography. Calibration equations were developed using modified partial least square regression with internal cross validation (n=63). The equations obtained had low standard errors of cross-validation and moderate $R^2$ (coefficient of determination in calibration). Prediction of an external validation set (n=30) showed significant correlation between reference values and NIRS estimated values based on the SEP (standard error of prediction), $r^2$ (coefficient of determination in prediction) and the ratio of standard deviation (SD) of reference data to SEP. The models developed in this study had relatively higher values (more than 2.0) of SD/SEP(C) for oleic and linoleic acid, having good correlation between reference and NIRS estimate. The results indicated that NIRS, a nondestructive screening method could be used to rapidly determine fatty acid composition in sesame seeds in the breeding programs for high quality sesame oil.

• 한국압력기기공학회 논문집
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• 제10권1호
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• pp.75-81
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• 2014

A simulation of eddy current testing has been utilized for predicting the signal characteristics to the various defects and developing the probes. Especially, CIVA which is a simulation tool dedicated to nondestructive testing has a good accuracy and speed, and provides a three-dimensional graphical user interface for improved visualization and familiar data displays consistent with NDE technique. Although internal validations have been performed by the CIVA software development specialists, an independent validation study is necessary for the accuracy assessment of the software prior to practical use. For this purpose, in this study, eddy current testing signals of ASME FBH calibration standard tube for bobbin probe were simulated using CIVA and the results were compared to the experimental inspected signals based on the relationship between each flaw signal in terms of amplitude and phase, and the shape of the Lissajous curve. And then we verified the accuracy of the simulated signals and the possible range for simulation. Overall, there is a good qualitative agreement between the CIVA simulated and experimental results in the absolute and differential modes at the two inspection frequencies.

• 한국압력기기공학회 논문집
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• 제9권1호
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• pp.25-30
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• 2013

The periodic inspection of piping and pressure vessels welds in nuclear power plant has to provide reliable result related to weld flaws, such as location, maximum amplitude response, ultrasonic length, height and finally the nature or flaw pattern. The founded flaw in ultrasonic inspection is accepted or rejected based on these data. Specially, the amplitude of flaw response is used as basic parameter for flaw sizing and it may cause some deviation in length sizing result. Currently the ultrasonic inspections in nuclear power plant components are performed by specific inspection procedure which describing inspection technique include inspection system, calibration methodology and flaw characterizing. To perform ultrasonic inspection during in-service inspection, reference gain should be established before starting ultrasonic inspection by the requirement of ASME code. This reference gain used as basic criteria to evaluate flaw sizing. Sometimes, a little difference in establishing reference gain between calibration and field condition can lead to deviation in flaw sizing. Due to this difference, the inspection result may cause flaw sizing error. Therefore, the objective of this study is to compare and evaluate the ultrasonic amplitude difference between air filled and water filled pipe in nuclear power plant. Additionally, the accuracy of flaw sizing is estimated by comparing both conditions.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2354-2358
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• 2007

MALDI-TOF-MS technique was applied to obtain structural and compositional information of synthetic polyamides, Nylon6 and Nylon66. Mass spectra of both the original and the hydrolyzed polyamide samples were analyzed using the self calibration method as well as the internal calibration method with the standard materials of known masses. The MALDI-TOF mass spectra of Nylon6 samples showed the presence of protonated, sodiated, and potassiated ions that were assigned to cyclic and NH2/COOH terminated linear oligomers. From the MALDI-TOF mass spectra of Nylon66 samples, the potassiated linear oligomers with three different end groups are identified as well as the cyclic oligomers, i.e., NH2/COOH terminated oligomers, NH2/NH2 terminated oligomers, and COOH/COOH terminated oligomers. Full characterization of the molecular species and end groups present in the polyamide samples has been achieved, and also the changes in mass spectral patterns after the hydrolysis of the samples are presented.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2359-2362
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• 2007

MALDI-TOF-MS technique was applied to obtain structural and compositional information of synthetic polyamides, Nylon6 and Nylon66. Mass spectra of both the original and the hydrolyzed polyamide samples were analyzed using the self calibration method as well as the internal calibration method with the standard materials of known masses. The MALDI-TOF mass spectra of Nylon6 samples showed the presence of protonated, sodiated, and potassiated ions that were assigned to cyclic and NH2/COOH terminated linear oligomers. From the MALDI-TOF mass spectra of Nylon66 samples, the potassiated linear oligomers with three different end groups are identified as well as the cyclic oligomers, i.e., NH2/COOH terminated oligomers, NH2/NH2 terminated oligomers, and COOH/COOH terminated oligomers. Full characterization of the molecular species and end groups present in the polyamide samples has been achieved, and also the changes in mass spectral patterns after the hydrolysis of the samples are presented.

• 한국전기전자재료학회논문지
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• 제30권10호
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• pp.677-682
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• 2017

Lamination is used extensively in various industries. The type of lamination applied to the material depends on the precision level required, which varies for materials needed for everyday use, materials used in high-tech industries, and processes employed to fabricate finished products. Especially in hot lamination, the distribution of the surface temperature of the heating roller is very important to avoid the generation of internal bubbles and ensure flatness of the attached materials, and thus maintain a good standard of quality and productivity. In this study, we have developed a system to monitor the surface temperature of the heating rollerby applying a heterogeneous controller and a non - contact temperature sensor. This monitoring system accurately measures the surface temperature of the heating roller and applies the RS485 MODBUS communication method for easy expansion. Using this system, a laminated prototype was fabricated, and its efficacy for non-contact temperature sensor calibration, Ethernet IP communication, stoppage of the heating roller, and determination of temperature distribution with rotation was examined for its potential usage in industries.