• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.490-493
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• 2002

In this paper, the old Fourier-Motzkin method (abbreviated as the old FH method from now on) is first modified to the form which can derive all minimal vectors as well as all minimal support vectors of nonnegative integer homogeneous solutions (i.e., T-invariants) for a matrix equation $Ax=b=0^{m{\times}1}$, $A\epsilonZ^{m{\times}n}$ and $b\epsilonZ^{m{\times}1}$, of a given Petri net, where the old FM method is a well-known and direct method that can obtain at least all minimal support solutions for $Ax=0^{m{\times}1}$ from the incidence matrix . $A\epsilonZ^{m{\times}n}$, Secondly, for $Ax=b\ne0^{m{\times}n}$ a new extended FM method is given; i.e., all nonnegative integer minimal vectors which contain all minimal support vectors of not only homogeneous but also inhomogeneous solutions are systematically obtained by applying the above modified FH method to the augmented incidence matrix $\tilde{A}$ =〔A,-b〕$\epsilon$ $Z^{m{\times}(n＋1)}$ s.t. $\tilde{A}\tilde{x}$ = 0^{m{\times}1}$ However, note that for this extended FM method we need some criteria to obtain a minimal vector as well as a minimal support vector from both of nonnegative integer homogeneous and inhomogeneous solutions for Ax=b. Then those criteria are also discussed and given in this paper.

• 한국축산식품학회지
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• 제32권5호
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• pp.627-634
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• 2012

This study was carried out to investigate the physical and thermal properties of ${\kappa}$-carrageenan (${\kappa}$-car) gel added whey protein isolate (WPI) as a cryoprotectant. The concentration of ${\kappa}$-carrageenan was fixed at 0.2 wt%. The mean ice crystal size of the WPI/${\kappa}$-car was decreased according to increasing whey protein isolate concentration. The temperature of gel-sol (Tg-s) and sol-gel (Ts-g) transition of WPI/${\kappa}$-car maxtrix was represented in the order of 3.0, 0.2, 5.0 and 1.0 wt%. In addition, the transition temperature of gel-sol of WPI in sucrose solution were showed in order of 1.0, 5.0, 0.2 and 3.0 wt% depending on whey protein isolate concentration. The shape of ice crystal was divided largely into two types, round and rectangular form. 1.0 wt% WPI/${\kappa}$-car matrix at pH 7 and 9 showed minute and rectangular formation of ice crystals and whey protein isolate in sucrose solution at a concentration of 1.0 wt% WPI/${\kappa}$-car matrix at pH 3 and 5 showed relatively large size and round ice crystals. The ice recrystallization characteristics and cryprotective effect of ${\kappa}$-carrageenan changed through the addition of different concentrations of whey protein isolate. It seems that the conformational changes induced interactions between whey protein isolate and ${\kappa}$-carrageenan affected ice recrystallization.

• Archives of Metallurgy and Materials
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• 제67권4호
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• pp.1543-1546
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• 2022

The aluminum composite with dispersed high entropy alloy were developed by stir casting involving the powder-in-tube method. First, Al_0.5CoCrCuFeNi high entropy alloy (HEA) powder was made by mechanical alloying, and the powder was extruded in a tube-type aluminum container to form HEA precursor. The extruded HEA precursor was then dispersed in the aluminum matrix via stir casting. As a result, Fe-Cr-Ni based high-entropy phases was uniformly formed in the aluminum matrix, revealing ~158, 166, 235% enhancement of tensile strength by incorporating 1, 3, and 5 wt% HEA particles, respectively.

• 한국재료학회지
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• 제28권9호
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• pp.495-498
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• 2018

Intermetallic compound matrix composites have been expected to be established as high temperature structural components. $Ni_3Al$ is a representative intermetallic alloy, which has excellent ductility even at room temperature by adding certain alloying elements. $Ni_3Al$ matrix composites with aluminum oxide particles, which are formed by the in-situ reaction between the alloy and aluminum borate whiskers, are fabricated by a powder metallurgical method. The addition of aluminum borate whiskers disperses the synthetic aluminum oxide particles during sintering and dramatically increases the strength of the composite. The uniform dispersion of reaction synthesized aluminum oxide particles and the uniform solution of boron in the matrix seem to play an important role in the improvement in strength. There is a dramatic increase in strength with the addition of the whisker, and the maximum value is obtained at a 10 vol% addition of whisker. The $Ni_3Al$ composite with 10 vol% aluminum oxide particles $0.3{\mu}m$ in size and with 0.1 wt% boron powder fabricated by the conventional powder metallurgical process does not have such high strength because of inhomogeneous distribution of aluminum oxide particles and of boron. The tensile strength of the $Ni_3Al$ with a 10 vol% aluminum borate whisker reaches more than twice the value, 930 MPa, of the parent alloy. No third phase is observed between the aluminum oxide and the matrix.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제14권2호
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• pp.113-124
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• 2010

We consider matrix polynomial which has the form $P_1(X)=A_oX^m+A_1X^{m-1}+...+A_m=0$ where X and $A_i$ are $n{\times}n$ matrices with real elements. In this paper, we propose an iterative method for the symmetric and generalized centro-symmetric solution to the Newton step for solving the equation $P_1(X)$. Then we show that a symmetric and generalized centro-symmetric solvent of the matrix polynomial can be obtained by our Newton's method. Finally, we give some numerical experiments that confirm the theoretical results.

• 한국분말재료학회지
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• 제4권2호
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• pp.100-105
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• 1997

In this study the changes of the hardness and microstructures during aging at 120$^{\cire}C$ of an RS-P/M Al-5.6wt%Zn-2.0wt%Mg-1.3wt%Zr-1.0wt%Mn-0.25wt%Cu alloy were studied using a transmission electron microscopy. The hardness increased rapidly at early stage of aging and reached the maximun when the specimen was aged for 24 hr. The many irregular-shaped $Al_4Mn$ and rod-shaped $Al_6Mn$ dispersoids with 0.1-0.4 $\mu$m in length were observed in the as-extruded alloy. The dark particles with 2-3 nm in size were observed in aged specimen for 5hr and those are thought to be G.P.zones or precursor of $\eta'$ precipitates. In aged specimen for 24 hr, the $\eta'$ phases were distributed homogeneously within the matrix and the PFZ with 30-40 nm in width was observed along the grain boundary. With further aging, the width of PFZ increased and $\eta$ phases were also detected within the matrix.

• 한국환경보건학회지
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• 제26권4호
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• pp.75-81
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• 2000

A matrix modification was studied for the determination of trace manganese in several seaweeds by electrothermal atomic absorption spectrophotometry(ETAAS). The type and quantity of modifiers were investigated to realize the efficient modification. Palladium was chosen as a single modifier. By the addition of palladium(5$\mu\textrm{g}$/$m\ell$) to 2ng/$m\ell$ manganese solution, the temperatures were raised from 1,00$0^{\circ}C$ to 1,20$0^{\circ}C$ for the charring and from 2,10$0^{\circ}C$ to 2,20$0^{\circ}C$ for the atomization as well as the sensitivity and reproducibility were improved. With such optimum conditions, the trace amount of manganese in several seaweeds(laver, tangle and brown seaweed) could be determined by a calibration curve method, and good recoveries of more than 965 were also obtained in the samples in which a given amount of manganese was spiked. The detection limit of this method was about 0.048ng/$m\ell$.

• Journal of the Korean Data and Information Science Society
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• 제21권6호
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• pp.1263-1270
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• 2010

60명의 환자들을 20명씩3개 그룹으로 나누어 각 그룹마다 다른 종류의 식이요법을 실시한 후 1주 간격으로 5주간에 걸쳐서 콜레스테롤 수치에 대한 반복측정 자료를 얻었다. 해당자료를 바탕으로 적합성여부와 유의성 검정을 실시한 결과 등분산 Toeplitz가 다양한 공분산행렬 형태들 중에서 가장 적합한 공분산구조 모형으로 판명되었다. 이 모형에서는 시점들 간의 상관계수는 0.64-0.78로 대체적으로 높은 상관관계들을 보여주고 있으며, 모수인자들의 유의성검정 결과, 시간효과는 대단히 유의하게 나타났으나, 처리 및 처리와 시간과의 교호작용효과는 유의하지 않은 것으로 판명되었다.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제23권3호
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• pp.507-522
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• 2009

일반적으로 종이접기를 하고 그 종이를 다시 펼치면 흔적이 남는다. 직사각형의 종이를 이용하여 얻을 수 있는 수학적 사실과 프로그램을 접목해 보았다. 사각형의 종이를 접는 방향에 따라 골과 등성이의 형태가 다양하게 나타나며 이런 종이 모양의 흔적을 (0,1)코드와 (0,1)행렬을 이용하여 4종류로 분류하고 연구하였다. 따라서 이런 사각형 종이접기의 흔적을 보고 거꾸로 어떻게 접는지를 귀납적 추론력을 통해 코드와 종이접기의 흔적의 관계를 탐구하였다. 마지막으로 이 내용을 수학프로그램을 계발하였고 현장에서 실습을 할 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.376-376
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• 2016

Poly(ethylene oxide) (PEO)/functionalized bacterial cellulose nanowhiskers (f-BCNW) (0.1 wt%) composite nanofibers were fabricated by electrospinning process and the thermomechanical properties were significantly enhanced more than the PEO and PEO/bacterial cellulose nanowhiskers (BCNW) (0.1 wt%) composite nanofibers. The functionalization of BCNW (f-BCNW) was performed by microwave plasma treatment for effects of nitrogen functionalization of chemically-driven BCNW. The N-containing functional groups of f-BCNW enhanced chemical bonding between the hydroxyl groups of the polymer chains in the PEO matrix and diameter size of PEO/f-BCNW (0.1 wt%) composite nanofibers were decreased more than PEO and PEO/BCNW (0.1 wt%) composite nanofibers on the same concentration. The strong interfacial interactions between the f-BCNW nanofillers and polymer matrix were improved the thermomechanical properties such as crystallization temperature, weight loss and glass transition temperature (Tg) compared to PEO and PEO/BCNW composites nanofibers. The results demonstrated that N2 plasma treatment of BCNW is very useful in improving thermal stability for bio-applications.