• Journal of Advanced Marine Engineering and Technology
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• 제18권2호
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• pp.64-74
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• 1994

The gundrill is capable of machining for having large length to diameter ratio in single pass. The techniques of gundrill and gun boring began developing in the late 18th century with the need for more accurate bores in rifle, cannon, machinery part and marine part etc. The main feature of the gun drilling provides a stabilizing cutting force resultant necessary for self guidance of the drill head. A study of the accuracy and surface finish of holes produced would reveal quite useful information regarding the process. The thesis deals with the experimental results obtained during gun drilling on marine part materials for different machining conditions.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.613-617
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• 2000

This paper descries the effect of the stylus tip size on the measuring error in surface topography measurement. To analyze the distortional effect of an actual surface geometry originating from the finite stylus size, the surface is modeled as a sinusoid and the stylus tip as a circle. the measuring error is defined as the ratio of the standard deviation of a tracing profile and an original profile. It is shown that this measuring error depends on the amplitude and wavelength of an original profile. In this paper, the spectrum analysis is applied to investigate the distortional effect due to the mechanical filtering of the stylus in the frequency domain. and, the cumulative power spectrum is applied to determinate the minimum wavelength limits to be measured with the various stylus tip radius from these results, a new method to select proper stylus tip radius is proposed.

• Journal of Biosystems Engineering
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• 제23권6호
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• pp.607-614
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• 1998

An automatic grading algorithm was developed to replace the manual trading of white ginseng. The algorithm consists of three consecutive stages, (a) image acquisition and preprocessing, (b) mathematical feature extraction, and (c) grade decision using artificial neural network. Mathematical features such as area ratio, mean and standard deviation of graylevel, skewness of graylevel histogram, and the number of run segment are extracted from five equally divided parts of ginseng. An artificial neural network model was used to classify white ginsengs into three categories. The performance of the algorithm was evaluated using 120 ginseng samples and the rate of successful classification was 74%.

• Communications for Statistical Applications and Methods
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• 제21권6호
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• pp.529-538
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• 2014

In this paper, we consider maximum likelihood estimators of normal distribution based on type II censoring. Gupta (1952) and Cohen (1959, 1961) required a table for an auxiliary function to compute since they did not have an explicit form; however, we derive an explicit form for the estimators using a method to approximate the likelihood function. The derived estimators are a special case of Balakrishnan et al. (2003). We compare the estimators with the Gupta's linear estimators through simulation. Gupta's linear estimators are unbiased and easily calculated; subsequently, the proposed estimators have better performance for mean squared errors and variances, although they show bigger biases especially when the ratio of the complete data is small.

• 한국정밀공학회지
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• 제15권8호
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• pp.116-125
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• 1998

In this paper, main target is to select parameters for prediction of tool wear and detection of tool fracture. The research about choosing parameter for prediction of tool wear is done by using force ratios. Also current sensor, tool-dynamometer, and accelerometer are used for researching detection method of tool fracture. Experiment is done using Taguchi's method in medium machining conditions. Parameter which is best for prediction of tool wear and detection of tool fracture by deviation analysis is selected. In this paper, tool wear means flank wear.

• 분석과학
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• 제8권4호
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• pp.461-464
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• 1995

Three wavelength spectrophotometry was used to determine the content of eugenol in Eugenia Caryophyllata Thunb. Using this method could effectively eliminate the deviation of background absorption caused by the change of concentration and the error of quantitative analysis caused by asymmetric peaks, and at the same time the leaning degree of base line was corrected. This method was simple the recovery ratio was 90.05%-116.94% and the coefficient of variation was 3.5%.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.849-851
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• 2015

본 연구에서는 비대칭 이중게이트 MOSFET의 상하단 게이트 산화막 두께 비에 대한 문턱전압이하 스윙 및 전도중심의 변화에 대하여 분석하고자한다. 문턱전압이하 스윙은 전도중심에 따라 변화하며 전도중심은 상하단의 산화막 두께에 따라 변화한다. 비대칭 이중게이트 MOSFET는 상단과 하단의 게이트 산화막 두께를 다르게 제작할 수 있어 문턱전압이하 스윙의 저하 등 단채널효과를 감소시키기에 유용한 소자로 알려져 있다. 본 연구에서는 포아송방정식의 해석학적 해를 이용하여 문턱전압이하 스윙을 유도하였으며 상하단의 산화막두께 비가 전도중심 및 문턱전압이하 스윙에 미치는 영향을 분석하였다. 결과적으로 문턱전압이하 스윙 및 전도중심은 상하단 게이트 산화막 두께 비에 따라 큰 변화를 나타냈다. 또한 채널길이 및 채널두께, 상하단게이트 전압 그리고 도핑분포함수의 변화에 따라 문턱전압이하 스윙 및 전도중심은 상호 유기적으로 변화하고 있다는 것을 알 수 있었다.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.449-452
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• 2014

We present a multi-tap microwave photonic filter with high selectivity through applying time-to-frequency mapping and optical frequency comb shaping techniques. When arranged in the time-to-frequency mapping stage, by a Fourier transform, the deviation of the optical taps to the target profile is significantly reduced while maintaining the apodization profile, resulting in high sidelobe suppression in the filters. By applying a simple time-to-frequency mapping stage to the conventional optical frequency combs, we demonstrate a substantially enhanced (>10dB) sidelobe suppression, resulting in filter lineshapes exhibiting a significantly high (>40dB) main lobe to sidelobe suppression ratio. These results highlight the potential of the technique for implementation in various passband filters with high sidelobe suppression.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
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• pp.26.1-26.1
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• 2009

Many solar, interplanetary and geomagnetic activity parameters have 11-year cycle on the average in sync with solar sunspot number. The galactic cosmic ray (GCR) intensity measured by ground Neutron Monitor (NM) is one of those parameters showing the unprecedented activity levels in the current solar minimum (2008-2009) of solar cycles 23/24. We defined abnormality as the ratio of deviation from long term mean over mean amplitude of solar cycle change. The abnormality distribution map was drawn using all the data of NM stations available online. The implications of those unprecedented levels of GCR intensities of different cutoff rigidities will be discussed.

• 산업경영시스템학회지
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• 제37권4호
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• pp.259-268
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• 2014

Uniform brightness is very crucial for LCD panels, which should be made in during manufacturing. Usually some compensating algorithms are applied to recover the brightness deviation that occurs in actual panels. Although such remedying tools are used, it is very hard to prevent horizontal or vertical crosstalks that represent the brightness level difference in horizontal or vertical direction. This research applied transformability Taguchi dynamic characteristics and "nominal is best" static characteristic simultaneously to design the compensating circuit optimally that may reduce the crosstalks and make uniform brightness level.