• 품질경영학회지
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• 제9권1호
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• pp.3-11
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• 1981

동일한 부품 K개를 갖고 있으며, 그 중에서 S개 이상의 스트렝스(strength)가 스트레스(stress) 보다 크게 될 경우 신뢰성이 유지되는 시스템에서 스트레스와 스트렝스가 모두 와이블(weibull) 분포를 하고 있을 때의 시스템 신뢰성을 고찰하였다. 2 절에서는 시스템 신뢰성의 최소분산불편추정량(MVU estimator)을 구하였고, 3 절에서는 최소분산불편추정량의 점근분포(asymototic distribution)를 구하고 표본크기가 클때 시스템 신뢰성의 최소분산불편추정량과 최우추정량(MLE)과의 관계를 구하였으며, 4 절에서는 시스템 신뢰성의 일양최적불편신뢰구간(uniformly most accurate unbiased confidence interval) 을 구하였고, 5 절에서는 몬데 카를로 씨뮤레이션(Monte Carlo Simulation)을 사용하여 작은 표본에서의 최우추정량과 최소분산불편추정량의 편기(bias)와 평균자승오차(MSE)를 비교하였고 6 절에서는 결과를 간단히 요약하고 본 논문을 더 확장할 경우에 문제점을 제시하였다.

• 자원환경지질
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• 제25권3호
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• pp.225-232
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• 1992

The hydrothermal alteration is evaluated using multicomponent equilibrium calculations with the program CHILLER for the reactions between hydrothermal water and rhyolite at the temperature of $300^{\circ}C$ and pressure of 500 bars. The chemical-reaction model on the depositional processes of the sericitite confirms that the hydrothermal water-rock interaction(hydrothermal alteration) is the main mechanism of the sericitite formation. The principal change in the aqueous phase during the reaction is the pH increase. Overall trends for the major species are the increase in total molalities of K, Ca, $SiO_2$, Al, Mg, Fe, Na, and sulfide in solid phase with hydrothermal water-rhyolite reaction and the decrease of them in aqeous solution by precipitation of hydrothermal products. Quartz and sericite are the first minerals to form. The sequence of minerals to precipitate following them is chlorite, epidote, pyrite and microcline as water/rock ratio decreases. Although calculated results cannot duplicate the complexities of natural hydrothermal alteration, the calculation provides thermodynamic constraints on the natural process. The calculation results resemble those of experimental studies. Sericitite forms where pH decreases and water/rock ratio increases.

• 대한화학회지
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• 제51권6호
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• pp.520-525
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• 2007

Thiourea/urea, 다양한 aromatic aldehydes, ammonium acetate의 세가지 요소를 가지고 마이크로파의 조 사하에서 무수조건의 활성화된 비산화재를 촉매로 사용하여 높은 수율의 6-aryl-1,2,4,5-tetrazinan-3-thiones/ones를 얻었 다. 6-aryl-1,2,4,5-tetrazinan-3-thiones/ones의 구조는 녹는점, MS, IR, 1H NMR, D2O 교환, 13C NMR, 이차원의 NMR 스펙트럼(HOMOCOR, HSQC)을 바탕으로 증명되었다.

• 대한화학회지
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• 제34권6호
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• pp.616-621
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• 1990

UV-VIS 흡광광도법으로 Nd, Pr, Sm, Eu, Ho 및 Er을 정량할 때 스펙트럼 방해를 다원소 보정법으로 방법에 대하여 연구하였다. 개별희토류의 흡광도를 측정하고 또, Nd와 Pr의 혼합용액 및 Sm, Eu, Ho, Er의 혼합용액의 흡광도를 측정하여 몰흡광 계수를 구하고 이들로부터 상호 방해가 가장 적은 파장 즉, Nd(444.2nm), Pr(575.1nm), Sm(401.7nm), Eu(394.2nm), Ho(416.6nm), Er(379.7 nm)임을 알았다.

• 음성과학
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• 제12권4호
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• pp.53-70
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• 2005

A Vowel of speech signals are multicomponent signals composed of AM-FM components whose instantaneous frequency and instantaneous amplitude are time-varying. The changes of emotion states cause the variation of the instantaneous frequencies and the instantaneous amplitudes of AM-FM components. Therefore, it is important to estimate exactly the instantaneous frequencies and the instantaneous amplitudes of AM-FM components for the extraction of key information representing emotion states and changes in speech signals. In tills paper, firstly a method decomposing speech signals into AM - FM components is addressed. Secondly, the fundamental frequency of vowel sound is estimated by the simple method based on the spectrogram. The estimate of the fundamental frequency is used for decomposing speech signals into AM-FM components. Thirdly, an estimation method is suggested for separation of the instantaneous frequencies and the instantaneous amplitudes of the decomposed AM - FM components, based on Hilbert transform and the demodulation property of the extended Fourier transform. The estimates of the instantaneous frequencies and the instantaneous amplitudes can be used for modification of the spectral distribution and smooth connection of two words in the speech synthesis systems based on a corpus.

• E2M - 전기 전자와 첨단 소재
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• 제9권10호
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• pp.1047-1052
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• 1996

In this study, the thermal and optical proper-ties of multicomponent oxide glass fiber for IR sensor by adding heavy metal oxide Ga$_{2}$O$_{3}$ were investigated. The fiber samples were made by rod-in tube method. The optical loss of fiber was measured in 0.3-1.8/M wavelength region. As Ga$_{2}$O$_{3}$ increased up to 12wt%, the transition and softening temperature of bulk glass were increased from 495.deg. C to 564.deg. C and from 548.deg. C to 612.deg. C respectively. Whereas the thermal expansion coefficient was decreased from 102 to 88.2*10$^{-7}$ /.deg. C. The refractive index was increased from 1.621 to 1.662, and IR cut-off wavelength was enlarged from 4.64.mu.m to 5.22.mu.m. The optical loss of fiber was decreased and more remarkably decreased in 1.146.mu.m-1.8.mu.m wavelength region.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.994-1000
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• 2014

Synthesis of tetrahydroimidazo[1,2-a]pyridines and tetrahydropyrido[1,2-a] pyrimidines by a one-pot and three component reaction of ${\alpha}$-oxoketenedithioacetals, diamines and DMAD in water has been described. Different routes for accessing the desired compounds were examined and a few specially designed-substrates have been utilized further to afford the new imidazo and pyrido fused [1,8] naphthyridine tetracyclic compound by $S_NAr$ intramolecular cyclization.

• Nuclear Engineering and Technology
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• 제48권1호
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• pp.72-86
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• 2016

A steam explosion may occur during a severe accident, when the molten core comes into contact with water. The pressurized water reactor and boiling water reactor ex-vessel steam explosion study, which was carried out with the multicomponent three-dimensional Eulerian fuel-coolant interaction code under the conditions of the Organisation for Economic Co-operation and Development (OECD) Steam Explosion Resolution for Nuclear Applications project reactor exercise, is presented and discussed. In reactor calculations, the largest uncertainties in the prediction of the steam explosion strength are expected to be caused by the large uncertainties related to the jet breakup. To obtain some insight into these uncertainties, premixing simulations were performed with both available jet breakup models, i.e., the global and the local models. The simulations revealed that weaker explosions are predicted by the local model, compared to the global model, due to the predicted smaller melt droplet size, resulting in increased melt solidification and increased void buildup, both reducing the explosion strength. Despite the lower active melt mass predicted for the pressurized water reactor case, pressure loads at the cavity walls are typically higher than that for the boiling water reactor case. This is because of the significantly larger boiling water reactor cavity, where the explosion pressure wave originating from the premixture in the center of the cavity has already been significantly weakened on reaching the distant cavity wall.

• Applied Microscopy
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• 제28권4호
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• pp.539-549
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• 1998

The silk glands of the spiders are of several types. Among the several types of spider's silk glands, the principal fibers used in constructing the eggcase are products of the tubuliform glands (TBG), which are present only in females. Development of these glands parallels maturations of the ovaries and fat bodies. In order to understand the mechanism of eggcase-silk production, this paper has examined the fine structural changes of the TBG during the period of egg maturation in the garden spider, Argiope aurentia. Between the two kinds of secretory granules observed in the glandular epithelium of the mature TBG, the electron-dense granules which have paracrystalline structure are revealed to be the precursors of the eggcase silk fibers. During the production of eggcase, rapid release of the secretory product occurs at apical surface by the mechanism of apocrine secretion. Moreover, secondary lysosomes appear due to the rapid disorganization of cellular components during the eggcase formation. Examinations of formed fibers indicate a multicomponent internal structure, and electron micrographs reveal each fiber contains numerous electron lucent fibrils embedded in an amorphous electron dense matrix. The secretory precursors are produced as separated vesicles via well-oriented rER, and no Golgi complex has been found in the glandular epithelial cells.

• 한국염색가공학회지
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• 제8권5호
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• pp.68-75
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• 1996

Even if fibers are practically identical with respect to chemical composition and denier, the dyeabilities are freqently a little different in an industrial processing. It is difficult to interpret the numerical values of dye diffusion coefficients from a dye solution into fibers. The main reasons are the multicomponent nature of the diffusion process and the inhomogeneities of the substrate, so-called, various kinds of ordered and disordered regions of polymers, void and pores. The equilibrium dye adsorptions and dyeing rates of a disperse dye into the several PET fibers having the same denier were determined at various temperatures. The dyeability of examined samples was divided into two groups, that is, lower dye adsorption fiber and higher ones at the lower temperatures. This result was discussed with the degree of crystallinity, DSC diagram, X-ray diffractometry and Porosimetry of the PET fiber, and an appropriate model for fine structure of PET fiber was proposed.