• 대한전자공학회논문지
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• 제25권3호
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• pp.315-321
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• 1988

The input-output relation for nonlinear systems can e explicitly represented by the volterra functional series and it is characterized by the Volterra kernels. A block diagram reduction method is proposed to determine the Volterra kernels for nonlinear differential equations and is compared with the direct substitution techniques. The former method can significantly reduce the computational complexity. A degree of nonlinearity is defined and analyzed for the analysis of nonlinear systems.

• Tribology and Lubricants
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• 제5권1호
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• pp.21-27
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• 1989

A paper facirig, used for clutch disc or brake lining of the vehicles, is consisted of a combination of cellulose fiber of pulp with assorted filler and friction imparting particles, impregnated with a thermo-setting resin. In this study, as a substitution for the paper-production method, the molding-production method was attempted to produce the paper facings, and their frictional characteristics were investigated. According to the experimental results, it was estimated that the paper facings added with silica (SiO$_2$) have superior frictional characteristics, which is mused by the porosity and Mobs' hardness of the silica (SiO$_2$).

• 대한수학회보
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• 제61권3호
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• pp.699-715
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• 2024

We study the Riemann problem for the pressureless Euler system with the source term depending on the time. By means of the variable substitution, two kinds of Riemann solutions including deltashock and vacuum are constructed. The generalized Rankine-Hugoniot relation and entropy condition of the delta-shock are clarified. Because of the source term, the Riemann solutions are non-self-similar. Moreover, we propose a time-dependent viscous system to show all of the existence, uniqueness and stability of solutions involving the delta-shock by the vanishing viscosity method.

• 콘크리트학회논문집
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• 제27권3호
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• pp.237-244
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• 2015

시멘트는 건설 산업의 발전과 비례하여 눈부신 발전을 이루었다. 그러나 이산화탄소의 발생량 또한 매우 치명적이다. 이러한 문제를 해결하기 위해 이산화탄소의 배출이 적은 시멘트의 개발이 시급한 상황이다. 따라서 본 연구에서는 시멘트의 대체제로 소성과정이 없어 에너지 손실률이 낮으며 이산화탄소의 배출량이 적은 비소성 시멘트(Non-Sintered Cement, 이하 NSC) 모르타르를 개발하고자 하였다. 산업 부산물인 고로슬래그 미분말(Granulated ground Blast Furnace Slag, 이하 GBFS)에 이를 활성화시키기 위한 자극제를 배합하였다. 그리고 GBFS와 자극제의 배합비율이 어떠한 양생조건에서 우수한 지를 알아보기 위해 각각의 양생조건에 따른 휨 및 압축강도, 그에 따른 수화 반응 생성물과 메커니즘을 알아보기 위해 SEM, XRD 실험을 진행하였고, 또한 화학저항성, pH측정, 염화물 이온 침투 저항성 및 탄산화 촉진실험을 실시하여 내구성을 알아보았다. 실험 결과 보통 포틀랜드 시멘트와 비교하여 전체적으로 우수한 특성과 내구성을 보여주었고, 콘크리트 2차 제품으로 개발하여 경제성 향상, 친환경적인 제품 생산, 환경문제 및 에너지 절약에 큰 이바지를 할 것으로 기대된다.

• 산업경영시스템학회지
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• 제3권3호
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• pp.59-66
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• 1980

The purpose of this paper to study on measuring method in technical progress. Technology is combination method of raw material and capital, land, labour. The first step to technical Progress is COBB-DOUGLAS production function, so technical progresses are important role in economic growth and development. General production function from Y=f(K, L, T) and COBB-DOUGLAS production function Y=${AK^I}{L^b}$ is first condition. Technical progress is saving of production factor In capital saving, labour saving, neutral saving. Marred Hicks Robinson has Insist on technical progress by each view of production factor, but, what is most excellent measuring method of technical progress\ulcorner I : productivity index method. II : Gross Production function method. Productivity method used in every products level in weight values, gross method function method used in production factor attributed to products. Above two measuring method has delicate problem in each input factor, substitution relation and production factor simultaneously linked each others This basic problem based on technical progress is not solubable in this time.

• Applied Microscopy
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• 제37권3호
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• pp.175-183
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• 2007

정확한 세포의 구조 분석을 위해서는 조직을 가능한 한 자연 상태 그대로 보존하는 것이 무엇보다 중요하다. 그러나 지금까지 이용되고 있는 화학적인 고정방법은 조직의 변형을 유도하는 것으로 알려져 그 해결방법에 관한 연구가 활발히 진행되고 있다. 그 연구의 결과로 현재 급속 동결법이 제시되었고, 그 중 초고압동결법(high-pressure freezing method)는 가용 두께가 $200{\mu}m$로서 $10{\sim}15{\mu}m$정도인 침윤동결법(plunging method) 혹은 접촉동결법 (slamming method)보다 우수한 방법으로 보고되고 있다. 본 연구팀에는 노랑초파리(Drosophila melanogaster)의 레티나를 화학고정법과 고압동결법으로 고정하여 미세구조를 비교하였다. 먼저 120kV 전자현미경을 이용하여 각 세포 소기관을 비교하였고, 그 중 미토콘드리아의 형태변화를 좀 더 자세히 비교하기 위하여 초고압전자현미경을 이용하였다. 그 결과 급속동결 세포의 세포막과 미토콘드리아의 고정에서 특히 차이가 있음을 알 수 있었고, 이는 주로 탈수에 의한 구조변형 때문인 것으로 추측된다.

• Journal of the Optical Society of Korea
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• 제18권3호
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• pp.244-250
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• 2014

Due to the difficulty in measuring very low out-of-band cutoff depths of solar blind UV filters, we propose a cutoff depth adjustable measurement system (CDAM) to test deep cutoff filters with a large dynamic range. The CDAM utilizing the substitution method is elaborately composed of several parts, including narrow-band LED light sources, standard reflective neutral attenuators with known attenuation coefficients, and a photomultiplier (PMT). This paper also presents an attenuator combination method ensuring that the PMT works within its linear response range. In addition, numerical simulation testifies to the method, and experiment shows that the CDAM system can achieve an extension of dynamic range from 0-6 OD to 0-10 OD, which is sufficient for the measurement of out-of-band cutoff depths of solar blind UV filters. Above all, the CDAM system, being easily implemented, of wide dynamic range, and highly precise, could be widely used in the measurement of filter cutoff depth.

• Journal of Magnetics
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• 제11권1호
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• pp.51-54
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• 2006

Variation of magnetic properties through Cr substitution for Co in inverse-spinel $CoFe_2O_4$ has been investigated by vibrating-sample magnetometry (VSM) and conversion electron $M\ddot{o}ssbauer$ spectroscopy (CEMS). $Cr_{x}Co_{1-x}Fe_2O_4$ samples were prepared as thin films by a sol-gel method. The lattice constant of the $Cr_{x}Co_{1-x}Fe_2O_4$ samples was found to remain unchanged, explainable in terms of a reduction of tetrahedral $Fe^{3+}$ ion to $Fe^{2+}$ due to substitution of $Cr^{3+}$ ion into octahedral $Co^{2+}$ site. The existence of the tetrahedral $Fe^{2+}$ ions in $Cr_{x}Co_{1-x}Fe_2O_4$ was confirmed by CEMS analysis. Room-temperature magnetic hysteresis curves for the $Cr_{x}Co_{1-x}Fe_2O_4$ films measured by VSM revealed that the saturation magnetization $M_s$ increases by Cr doping. The $M_s$ is maximized when x = 0.1 and decreases for higher x but is still bigger than that of $CoFe_2O_4$. The increase of $M_s$ can be explained partly by the reduction of the tetrahedral $Fe^{3+}$ ion to $Fe^{2+}$.

• 한방안이비인후피부과학회지
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• 제20권3호
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• pp.127-137
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• 2007

Objects : This study was designed to determine origin-plants of 3 kinds of Scrophulariaceae herbs reported worldwide 220 families 3000 species, domestic 21 families 55 species by researching efficacy of each herb. Furthermore the objects of study were confirmation of genuine species and substitution species standing on the results. Methods : In this studies, the origin-plants and efficacy were determined by bibliographic method. Results : The results indicate that 1. There were total 15 species of original plants of Scrophulariaceae herbs, 9 species for Radix Scrophulariae, 4 species for Radix Rehmanniae Recens, 2 species for Rhizoma Picrorrhizae. 2. In the view of authenticity of Radix Scrophulariae, there were 2 genuine species, 1 species for substitution, and study of 6 species later on. 3. In the view of authenticity of Radix Rehmanniae Recens, there were 2 genuine species, 1 species for substitution, and study of 1 species later on. 4. In the view of authenticity of Rhizoma Picrorrhizae, all the original species was genuine species. 5. The each efficacy of origin-plants were reported in the main subject. Conclusions : The 15 original plants were present among the 3 medicinal herbs in the common family scrophul ariaceae. There were 2 genuine species in Radix Scrophulariae and Rhizoma Picrorrhizae. All the original species was genuine species in Rhizoma Picrorrhizae.

• 대한교통학회지
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• 제26권6호
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• pp.133-142
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• 2008

통행시간 신뢰성은 통행자가 예측하기 힘든 통행시간의 변동을 설명하는 개념이다. 그 동안 이 주제는 교통학의 주요 연구 분야 중 하나였다. 본 연구는 특히 신뢰성의 가치에 관하여 살펴본다. 가치 산정을 위한 방법론으로는 한계대 체율법이 제안되며, 기초자료는 선택실험법을 이용하여 통행자의 잠재선호 자료를 구축한다. 조사된 자료를 이용하여 수단선택모형을 추정하며, 앞서 언급한 한계대체율법을 적용하여 신뢰성의 가치를 산정한다. 신뢰성의 가치는 통행권 역에 따라 지역 간과 도시부 통행으로 나누고, 통행목적에 따라 업무와 비업무 통행으로 구분하여 제시된다. 본 연구의 결과가 도로 및 철도 투자사업의 신중한 의사결정에 일조할 수 있기를 기대한다.