• Nuclear Engineering and Technology
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• 제33권6호
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• pp.626-637
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• 2001

A series of study on energy dependence in chemiluminescence dosimetry with sugar and sorbite produced in two different countries was carried out administering a dose of 5 Gy to the samples at six different mean photon energies of 30, 50, 80, 130, 662 and 1250 keV. The results revealed distinct energy dependence of chemiluminescence(CL) output of sugar and sorbite. Although the energy dependence, in general, could be fitted by a polynomial of (os E, with I being radiation energy, up to cubic term, we reached a conclusion that the adoption of a fitting function, $y_{R}$$^{=a}$.(1-e $^{-b.logE}$)$^{c}$ +d, deduced from theoretical energy response curve calculated as the ratio of the mass energy absorption of the samples of interest to the soft tissue is more reasonable and rational. Herecoefficients $y_{R}$ is CL intensity, and a, b, c and d are constants to be determined in the fitting process. Energy dependence of relative sensitivities of one sample to the other, discrepancy in sensitivities of the samples from the two countries, and prominent grain size effect in Sorbitol were also shown.shown.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.852-856
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• 2011

The lithium ion diffusion coefficients of bare, carbon-coated and Cr-doped $LiFePO_4$ were obtained by fitting the discharge curves of each half cell with Li metal anode. Diffusion losses at discharge curves were acquired with experiment data and fitted to equations. Theoretically fitted equations showed good agreement with experimental results. Moreover, theoretical equations are able to predict lithium diffusion coefficient and discharge curves at various discharge rates. The obtained diffusion coefficients were similar to the true diffusion coefficient of phase transformation electrodes. Lithium ion diffusion is one of main factors that determine voltage drop in a half cell with $LiFePO_4$ cathode and Li metal anode. The high diffusion coefficient of carbon-coated and Cr-doped $LiFePO_4$ resulted in better performance at the discharge process. The performance at high discharge rate was improved much as diffusion coefficient increased.

• 한국광학회지
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• 제2권4호
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• pp.203-208
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• 1991

모드동기된 아르곤 이온 레이저를 여기광원으로 사용한 시간상관 단일광자 계수장치를 이용하여 에틸렌글리콜 용매 내에서 Rhodamine 6G에서 Malachite Green으로의 비복사 에너지전달과정을 연구하였다. 측정된 donor의 형광소멸곡선을 full-fitting 방법으로 분석 처리하여 acceptor 농도의 변화에 따른 환산농도와 임계전이거리를 구했다. donor의 농도가 acceptor의 농도 보다 클때는 donor-donor의 원거리 쌍극자 모멘트에 의한 에너지 이주 효과를 고려해야하며 Forster 모델 보다 Huber 모델이 더 적절하였다.

• Wind and Structures
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• 제33권6호
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• pp.423-435
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• 2021

Although existing algorithms can predict wind speed using historical observation data, for engineering feasibility, most use moment methods and probability density functions to estimate fitted parameters. However, extreme wind speed prediction accuracy for long-term return periods is not always dependent on how the optimized frequency distribution curves are obtained; long-term return periods emphasize general distribution effects rather than marginal distributions, which are closely related to potential extreme values. Moreover, there are different wind speed parent sample types; how to theoretically select the proper extreme value distribution is uncertain. The influence of different sampling time intervals has not been evaluated in the fitting process. To overcome these shortcomings, updated steps are introduced, involving parameter sensitivity analysis for different sampling time intervals. The extreme value prediction accuracy of unknown parent samples is also discussed. Probability analysis of mean wind is combined with estimation of the probability plot correlation coefficient and the maximum likelihood method; an iterative estimation algorithm is proposed. With the updated steps and comparison using a Monte Carlo simulation, a fitting policy suitable for different parent distributions is proposed; its feasibility is demonstrated in extreme wind speed evaluations at Longhua and Chuansha meteorological stations in Shanghai, China.

• 대한임베디드공학회논문지
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• 제18권3호
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• pp.117-124
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• 2023

In the machine vision inspection equipment, diameter measurement is important process in inspection of cylindrical object. However, machine vision inspection equipment requires complex algorithm processing such as camera distortion correction and perspective distortion correction, and the increase in processing time and cost required for precise diameter measurement. In this paper, we proposed the algorithm for diameter measurement of cylindrical object using the laser displacement sensor. In order to fit circle for given four input outer points, grid search algorithms using root-mean-square error and mean-absolute error are applied and compared. To solve the limitations of the grid search algorithm, we finally apply the singular-value-decomposition based circle fitting algorithm. In order to compare the performance of the algorithms, we generated the pseudo data of the outer points of the cylindrical object and applied each algorithm. As a result of the experiment, the grid search using root-mean-square error confirmed stable measurement results, but it was confirmed that real-time processing was difficult as the execution time was 10.8059 second. The execution time of mean-absolute error algorithm was greatly improved as 0.3639 second, but there was no weight according to the distance, so the result of algorithm is abnormal. On the other hand, the singular-value-decomposition method was not affected by the grid and could not only obtain precise detection results, but also confirmed a very good execution time of 0.6 millisecond.

• 한국기계가공학회지
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• 제10권3호
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• pp.39-46
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• 2011

The automotive air conditioning hose is used for connecting the components of air conditioner in a vehicle. The hose is usually manufactured by the swaging process to connect the rubber hose with the metal fitting at the end of the hose. In case that the clamping force is small, the refrigerant gas in the hose can leak locally under the severe operating circumstances. The practical test of clamping force is performed by means of the measurement of separation force. In this study, the swaging process of a hose is simulated with the finite element method, to investigate the effect of friction coefficient on the clamping force. The contact condition is used in consideration of real manufacturing process, and the material properties for the Mooney-Rivlin model is obtained by the experimental results. The result interpretations are focused on the contact forces, which is displayed graphically with respect to friction coefficient, on the surfaces between the hose and the metal fittings.

• 한국기계가공학회지
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• 제4권2호
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• pp.37-42
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• 2005

Recently $6{\sigma}$ quality control is an most important strategy to many enterprises in order to be a top company in the world, because it is an excellent scientific method to achieve the best quality control for their management and products. SY company is a small and medium one that has the quality problem for a long time such as occurring cracks on the surface of commutator at his assembly line while being assembled a rotor shaft and commutator of DC motor. This research was started to improve this problem by $6{\sigma}$ process, and as the results of this study, first, to find three vital fews, second, to get an achievement of about 21% improvement for the fracture strength of commutator, and third, to be recognized to change into $6{\sigma}$ quality control in SY company.

• 대한기계학회논문집B
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• 제29권9호
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• pp.1022-1031
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• 2005

Temporal behavior of the laser induced incandescence (LII) signal is often used for soot particle sizing, which is possible because the cooling behavior of a laser heated particle is dependent on the particle size. In present study, LII signals of soot particles are modeled using two non-linear coupled differential equations deduced from the energy- and mass-balance of the process. The objective of this study is to obtain an appropriate calibration curve for determining primary particle size by comparing the gated signal ratio and double-exponential curve fitting methods. Not only the effects of laser fluence and gas temperature on the cooling behavior but also heat transfer mechanisms of heated soot particle have been investigated. The second-order exponential curve fitting showed better agreements with the LII signals than the gated signal ratio method which was based on the lust-order exponential curve fit. And the temporal decay rate of the LII signal and primary particle size showed nearly linear relationship, which was little dependent on the laser fluence. And it also could be reconfirmed that vaporization was dominant process of heat loss during first loons after laser pulse, then heat conduction played most important role while thermal radiation had little influence all the time.

• 대한수학교육학회지:수학교육학연구
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• 제20권1호
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• pp.73-84
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• 2010

학교수학에서 다루는 수학적 모델링의 일반적인 특성은 하나의 실제적인 문제를 해결하기 위하여 수학적 모델을 도입하고 이를 풀어서 실제적인 문제에 답을 제시하는 일회적인 경우가 많다. 그러나 실제적인 문제는 일회적인 모델링으로는 해결되지 않거나 그 해가 충분히 정밀하지 못한 경우가 있다. 본 연구는 여러 가지 변인을 가진 실제적인 문제를 해결하기 위해 수학적 모델을 구성할 경우, 구성한 수학적 모델의 해의 의미성을 분석해 보고 필요하면 더욱 정교한 해를 구할 수 있는 모델로 나아가는 수학적 모델링의 정교화 과정 모형을 구안하였다. 또한 그것을 수학교실에서 활용할 수 있는 수학적 모델링의 예를 제시함으로써 학교수학에서 수학적 모델링의 정교화를 다룰 수 있게 하였다.

• 대한기계학회논문집A
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• 제38권6호
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• pp.637-647
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• 2014

국내 가압경수로형 원자로의 압력용기 상부헤드에는 많은 제어봉구동장치(CRDM) 노즐이 분포한다. 이들 노즐은 억지끼워맞춤(Shrink fitting) 방식으로 결합되어 용접 처리 된다. 용접에 의해 발생되는 인장잔류응력은 일차수응력부식균열을 발생시키는 주요 요인이다. 이러한 이유로 최근 15 여 년 동안 관통노즐 용접부 부위에서 균열 발생 사례가 증가하고 있으며, 이를 극복하기 위해 다양한 방안이 모색되고 있다. 또한 용접과정에서 발생되는 불필요한 결함은 일차수응력부식균열(PWSCC)을 가속화 시키는 원인이 되기도 한다. 원자로 제작과정에서 용접에 의한 결함은 보수용접에 의해 즉시 수리가 이루어 진다. 기존의 연구에서는 정상적인 용접과정에서 발생되는 잔류응력을 예측하였으나, 본 연구에서는 용접과정에서 발생되는 결함을 보수하기 위해 실시되는 보수용접이 용접잔류응력에 미치는 영향을 분석하였다.