• 대한수학회논문집
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• 제19권2호
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• pp.293-305
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• 2004

Trotter-Kato type approximations of the convoluted solution operator families for the Volterra integral equations (V $E_n$): v(t)=$A_{n} \int_0^t v(t-s) d\mu_n(s) + f_n(t), t \geq 0$ and the convergence of the solutions to the equations (V $E_n$) are studied.

• Journal of applied mathematics & informatics
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• 제17권1_2_3호
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• pp.559-565
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• 2005

In this paper, we establish the convergence of semigroups that are strongly continuous on (0, $\infty$). By using Laplace transform theory, we show some properties of semigroups and the convergence result.

• 대한수학회논문집
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• 제13권1호
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• pp.171-179
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• 1998

In this paper, we establish Trotted-Kato type convergence theoren for nonlinear semigroups generated by coaccretive operators in a hyperbolic space.

• Korean Journal of Mathematics
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• 제23권1호
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• pp.65-72
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• 2015

In this paper we show that the spectrum is continuous on the class of ${\star}$-paranormal operators but the approximate point spectrum generally is not continuous at ${\star}$-paranormal operators.

• 대한기계학회논문집B
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• 제21권7호
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• pp.862-872
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• 1997

Ice formation in a horizontal circular cylinder has been studied numerically. From the numerical analysis results, it was found that there were three types of freezing pattern and that freezing phenomenon was affected largely by density inversion and cooling rate. The type of freezing pattern largely depends on the secondary flow which is generated by density inversion. When supercooling energy is released before the development of the secondary flow, the annular ice layer grows. If the energy is released when the secondary flow is considerably developed and the supercooled region is removed to the upper half part of the cylinder, an asymmetric ice layer grows. And if the energy is released after perfect development of the secondary flow, instantaneous dendritic ice formation over the full region occurs. Furthermore, this secondary flow was found to have an effect on heat transfer characteristics. The heat transfer rate becomes small at the instant when the secondary flow is generated, but becomes large with the development of the flow. It's concluded that for the facilitation of heat transfer it is desirable to keep water in liquid phase until the secondary flow is perfectly developed. This study gave an instruction of performance improvement of capsule type ice storage tank.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권2호
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• pp.67-75
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• 2002

The human complement receptor type 1 (CR 1, C3 b/C4b receptor) is a polymorphic membrane glycoprotein expressed on human erythrocytes, peripheral leukocytes, plasma and renal glomerular podocytes, which consists of transmembrane and cytoplasmic domains with 30 repeating homologous protein domains known as short consensus repeats (SCR). CR1 has been used as an inhibitor for inflammatory and immune system for the past several years. Recently; it is reported that CRl was found to suppress the hyper-acute rejection in xeno-transplantation and can be used to cure autoimmune diseases. A soluble form of CRl, called sCRl, is a recombinant CRl by cleaving the transmembrane domain at C-terminus and has been expressed in Chinese Hamster Ovary (CHO) cells. Several purification methods for sCR1 from CHO cells have been reported, but most of them require complicated steps at high cost. Moreover, such methods are mostly performed under the pH condition apt to denaturing sCR1 and causes sCRl losing its activity. We here report a rapid and efficient method to purify sCR1 from CHO cell. The new method consists of a two-stage of cell culture by cultivating cells in serum medium followed by serum-free medium, and a two-stage of column purification by means of heparin and gel filtration column chromatography. By using this novel method, sCR1 can be purified in a simple and effective way with high yield and purity, furthermore, the purified sCR1 was confirmed to retain its activity to suppress the complement activation in vivo and ex vivo.

• Computational Structural Engineering : An International Journal
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• 제1권2호
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• pp.107-116
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• 2001

The present paper investigates the nonlinear behavior of reinforced concrete shear walls with a crank based on a finite element analysis. The loading type is a horizontal cyclic one such as earthquake loads. Experiments of the shear walls with and without cranks, performed previously to see flow the behavior changes depending on the crank, are compared with the results obtained from the finite element analysis. The finite element analysis is based on an isoparametric degenerated shell formulation. The nonlinear constitutive equations fur concrete are modeled adopting the formulation based on a concept of Ring Typed-Lattice Model. The experiments indicate that the shear walls with a crank have low stiffness and relatively low carrying capacity compared with an ordinary plane shear wall without cranks and that they are more ductile, and the tendency is a1so confirmed based on the finite element analysis. Moreover, a good agreement between the experiments and analyses is obtained, accordingly, it is confined that the present numerical analysis scheme based on the Lattice Model is a powerful one to evaluate the behavior of reinforced concrete shear walls with cranks and without cranks.

• 한국수산과학회지
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• 제9권4호
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• pp.287-292
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• 1976

1) A선형은 배수량이 2,400톤인 경우 KG의 값이 3.40m, 3.70m때 안정상태를 나타내었으며 배수량이 1,600톤 1,900톤 2,200톤일 경우는 KG의 값이 3.40m때 어느정도 안정범위에 있음이 판정되었다. 2) B선형은 배수량이 2,400톤일 경우 KG의 값이 3.40m때 만이 어느정도 안정범위에 있으나 배수량이 1,30 $0\~2,200$톤일 경우 KG값이 $3.40\~4.60m$때는 모두 위험범위에 있음이 판정되었다. 3. A선형은 GM의 값이 2.14m이고 $GZ_max$ 1.395m때 안정범위에 있고 B선형은 GM의 값이 2.14m이고 $GZ_max$ 1,890m때 어느 정도 안정범위에 있음이 판정되었다. 끝으로 본연구를 하는데 지도하여 주신 부산공대 김진안 교수님과 자료를 제공해 주신 대양조선주식회사 정부장씨께 감사드리며, 계산과정에서 협조해준 양주호군에게 사의를 표한다.

• 생명과학회지
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• 제17권12호
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• pp.1723-1728
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• 2007

본 연구에서는 다양한 기능성을 가지는 복분자를 80% methanol로 추출한 후 분획물들을 제조하여 항산화 효과 및 인간 유래 위암세포인 AGS와 KatoIII을 이용하여 성장 저해 효과와 DNA손상을 측정하였다. 항산화 효과를 측정해 보기 위하여 총 폴리페놀 함량과 플라보노이드 함량, DPPH free radical의 소거활성을 측정하였는데, 먼저 폴리페놀의 경우 butanol fr., ethylacetate fr., water fr.순으로 나타났고 특히 butanol fr.의 경우 $546.25{\mu}g/mg$의 매우 높은 폴리페놀 함량을 확인 할 수 있었다. 플라보노이드의 함량 결과 ethylacetate fr., butanol fr., water fr.,순으로 나타났으며 ethylacetate fr.의 경우 $141.78{\mu}g/mg$의 높은 플라보노이드 함량을 확인할 수 있었다. DPPH free radical의 소거활성에서는 폴리페놀 함량의 순서와 같은 효과를 보였으며, 합성 항산화제인 BHA의 $RC_{50}$값 $3{\mu}g/ml$보다 water fr.을 제외하고 더 좋은 소거능을 확인 할 수 있었다. 인간 유래 위암세포주의 성장 저해 효과를 살펴본 결과 AGS와 KatoIII 세포주 모두 butanol fr.에서 가장 좋은 저해능을 나타내었고, butanol fr., ethylacetate fr., water fr. 순서로 저해효과를 나타내었다. DNA손상을 측정한 결과 역시 이와 같은 순으로 나타났으며, butanol fr.에서 1시간 이내에 약 50%정도의 손상유도 효과를 보였다. 이상의 결과에서 복분자 methanol추출물과 각각의 분획물은 항산화 효과 및 위암 세포주에 대한 성장 저해 활성 및 높은 DNA손상 유도 효과를 갖고 있음을 알 수 있었다.