• Korea-Australia Rheology Journal
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• 제16권3호
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• pp.135-140
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• 2004

Morphological and rheological properties of the poly(methyl methacrylate) (PMMA) and polystyrene (PS) blends were studied by scanning electron microscopy (SEM) and advanced rheometric expansion system (ARES). From the SEM results, the PMMA-PS blends showed dispersed morphology and the particle size of the dispersed phase was quite small (0.1~0.6 $\mu\textrm{m}$ compared with other immiscible polymer blends. Values of the interfacial tension of the PMMA-PS blend were obtained from the Choi-Schowalter and the Palierne emulsion models using the storage modulus of the PMMA and PS, and found to be 1.0 and 2.0 mN/m, respectively. The interfacial tension between the PMMA and PS was also calculated from the Flory-Huggins polymer-polymer interaction parameter ($\chi$) and found to be from 0.98 to 1.86 mN/m depending on the molecular weight and composition. Comparing the values of the interfacial tension from the Flory-Huggins polymer-polymer interaction parameter and the values measured by oscillatory rheometer, it is suggested that the interfacial tension of the PMMA-PS blend obtained from the polymer-polymer interaction parameter are in good agreement with the values obtained by rheological measurements.

• 한국자기공명학회논문지
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• 제21권3호
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• pp.78-84
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• 2017

Pseudin is a naturally occurring 24 amino-acid-residue antimicrobial peptide derived from the skin of paradoxical frog Pseud's paradoxa. It shows potency against the bacteria and antibiotic-resistant bacteria strain, but has high cytotoxicity against mammalian cell. In our previous study, substitution of $Pro^{11}$ for Gly (Ps-P) increased bacterial cell selectivity but decreased the antibacterial activity of pseudin. In this study, we designed pseudin analogue, Ps-4K-P with increased cationicity up to +7 in Ps-P by substituting Glu14, Gln10, Gln24, and Leu18 with Lys. Ps-4K-P showed improved potent antibacterial activity with high bacterial cell selectivity. We determined the tertiary structure of Ps-4K-P in the presence of DPC micelles by NMR spectroscopy and it has a hinge structure at $Pro^{11}$ followed by three turn helices from $Pro^{11}$ to $Val^{23}$ at the C-terminus. Amphipathicity with increased cationicity as well as helix-hinge-helix structural motif provided by introduction of a Pro at position $Gly^{11}$ are the crucial factors which confer antibacterial activity with bacterial cell selectivity to Ps-4K-P.

• Asian Pacific Journal of Cancer Prevention
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• 제13권4호
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• pp.1575-1578
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• 2012

Objectives: To obtain permeability surface (PS) values using multi-slice helical CT perfusion imaging and to evaluate the spatial distribution correlation between PS values and vascular endothelial growth factor (VEGF) expression in solitary brain metastases. Methods: Imaging was performed on 21 patients, PS values being calculated from the central, border and peripheral parts of tumours. VEGF expression was determined by immunohistochemical staining. Results: Rim enhancement was found in 16 cases, the border of the tumour featuring PS elevation with high VEGF expression in 13 cases. In the 5 cases with nodular enhancement, the border and the central part had high permeability and VEGF expression was high in all cases, the correlation being significant (P<0.01). Conclusion: VEGF expression in brain metastases positively correlates with PS values from CT perfusion imaging, so that the latter can be used in the surveillance of angiogenic activity in brain metastases.

• Korean Journal of Acupuncture
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• 제26권2호
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• pp.127-143
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• 2009

Objective : This study aimed to evaluate the effects of Plantaginis Semen herbal-acupuncture (PS-HA) at KI10 (Umgok) on nephritis induced by lipopolysaccharide (LPS) in rat. Methods : The authors performed several experimental items including measurements of urinary volume, WBC in blood, BUN, creatine, TNF-$\alpha$, CINC-1 in serum, creatinine, total protein in urine, TNF-$\alpha$, MPO in kidney and histological analysis of renal tissue. Results : PS-HA at KI10 significantly reduced WBC in blood, BUN, TNF-$\alpha$ in serum of LPS-stimulated rats. PS-HA at KI10 significantly increased urinary volume in LPS-stimulated rats. And PS-HA at KI10 significantly reduced MPO in kidney of LPS-stimulated rats. Conclusion : Taken together, PS-HA at KI10 has a therapeutic effect on nephritis in LPS-stimulated rat. Therefore, it is suggested that PS-HA at KI10 may be an useful therapeutics for nephritis in clinical field.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.555-561
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• 2024

This paper derives material properties of steel bars that simulate the distribution of stress and strain of prestressed tendons used in Prestressed concrete(PSC) girders and presents an optimal material model. ABAQUS software was used to establish the 3D solid model of the PSC girder and strand wire rope for a PS(Prestressed) tendon. Then the model of steel wire rope was imported into the Isight interface plugin directly through the ABAQUS and the Data Matching. In ABAQUS, the contact pairs were established, the models were meshed, the constraints were applied to solve the finite element model and an axial tension of 0.5m/s was loaded to analyze the stress and deformation distributions in the normal working range of the PS strand wire rope. In Data Matching, classical experimental data is fitted to the optimal material properties through finite element analysis and multi-objective optimization. The results show that the steel bar with optimal material properties presents a similar linear area and stress distribution with the PS tendon.

• 동의신경정신과학회지
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• 제13권1호
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• pp.53-77
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• 2002

Alzheimer's disease(AD) is a progressive neurodegenerative disease, which is pathologically characterized by neuritic plaques and neurofibrillary tangles associated with the acetylcholinesterase, apolipoprotein E and butylcholinesterase, and by mutations in the presenilin genes PS1 and PS2, and amyloid precursor proteins (APPs) overexpression. The present research is to examine the inhibitory effect of KGBH on PS1, PS2 and APPs overexpression detected by Western blotting. To verify the Effects of KGBH on cognitive deficits further, we tested it on the scopolamine(1mg/kg)-induced amnesia model of the mice using the Morris water maze tests, and there were ameliorative effects on memory impairment as a protection against scopolamine. KGBH only partially blocked the increase in blood serum level of acetylcholinesterase and Uric acid induced by scopolamine, where as blood glucose level was shown to attenuate the amnesia induced by scopolamine and inreased extracellular serum level. In conclusion, studies of KGBH that has been known as anti-choline and inhibitory ablilities of APPs overexpression, could also be used further as a important research data for a preventive and promising symptomatic treatment for Alzheimer's disease.

• 동의신경정신과학회지
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• 제14권1호
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• pp.45-58
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• 2003

Alzheimer's disease(AD) is progressive neurodegenerative disease, which is pathologically characterized by neuritic plaques and neurofibrillary tangles associated with the acetylcholinesterase, apolipoprotein E and butylcholinesterase, and by mutations in the presenilin genes PS1 and PS2, and amyloid precursor proteins (APP) overexpression. The present research is to examine the inhibition effect of MDOF on PS-1, PS-2 and APP overexpression by detected to Western blotting. To verify the effects of MDOF on cognitive deficits further, we tested it on the scopolamine-induced amnesia model of the mice using the Morris water maze tests, and there was ameliorative effects of memory impairment as a protection to scopolamine. MDOF only partially blocked the increase in blood serum level of acetylcholinesterase and Uric acid induced by scopolamine, whereas blood glucose level was shown to attenuate the amnesia induced by scopolamine and inreased extracelluar serum level compared with only scopolamine injection. In conclusion, studies of MDOF that has been know as anti-choline and inhibition ablilities of APP overexpression, this could also be used further as a important research data for a preventive and promising symptomatic treatment for Alzheimer's disease.

• 동의신경정신과학회지
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• 제14권1호
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• pp.59-74
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• 2003

Alzheimer's disease(AD) is a progressive neurodegenerative disease, which is pathologically characterized by neuritic plaques and neurofibrillary tangles associated with the acetylcholinesterase, apolipoprotein E and butylcholinesterase, and by mutations in the presenilin genes PS1 and PS2, and amyloid precursor proteins (APP) overexpression. The present research is to examine the inhibition effect of CPRT on PS-1, PS-2 and APP overexpression by detected to Western blotting. To verify the Effects of CPRT on cognitive deficits further, we tested it on the scopolamine-induced amnesia model of the mice using the Morris water maze tests, and there was ameliorative effects of memory impairment as a protection to scopolamine. CPRT only partially blocked the increase in blood serum level of acetylcholinesterase and Uric acid induced by scopolamine, whereas blood glucose level was shown to attenuate the amnesia induced by scopolamine and inreased extracellular serum level compared with only scopolamine injection. In conclusion, studies of CPRT that has been known as anti-choline and inhibition ablilities of APP overexpression, this could also be used further as a important research data for a preventive and promising symptomatic treatment for Alzheimer's disease.

• 한국가스학회지
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• 제4권1호
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• pp.16-25
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• 2000

스틸렌 공중합체의 열적특성과 독성인자를 평가하기 위하여 활성화 에너지, 물리적 특성 및 마취성 기체와 같은 독성물질의 발생가능성에 대하여 조사하였다 고온 분해시에 Kissinger법과 DSC법에 의해 계산된 활성화 에너지는 25${\~}$50 Kcal/mol이었다. 이것은 화재발생가능성에 대하여 좋은 정보가 될 것이다 FED계산으로부터 PS, SAN 및 ABS에 대한 $LC_{50}$의 값은 8,580, 265 및 308 $mg/m^3$이 되었다. FT-IR에 의해 분석한 열분해 반응의 메카니즘은 측쇄반응이 아니고 주쇄반응이었다.

• 한국통신학회논문지
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• 제26권11B호
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• pp.1607-1611
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• 2001

매우 짧은 펄스를 이용한 40-Gb/s 광전송의 성능과 전송용 광섬유의 색 분산과의 관계를 컴퓨터 시뮬레이션을 사용하여 연구하였다. 매우 짧은 펄스를 사용할 경우 펄스매우 짧은 펄스를 이용한 40-Gb/s 광전송의 성능과 전송용 광섬유의 색 분산과의 관계를 컴퓨터 시뮬레이션을 사용하여 연구하였다. 매우 짧은 펄스를 사용할 경우 펄스의 넓은 스펙트럼이 광섬유의 색분산과 어우러져서 광섬유의 비선형성에 의한 신호의 왜곡이 억제된다. 이러한 억제의 정도는 광섬유의 색분산, 광신호의 세기 그리고 전송거리 등에 의해 복합적으로 결정된다. 3ps의 길이를 갖는 펄스가 사용되었을 경우 장신호의 세기가 너무 높지 않을 때, 눈 잠김 페널티는 광섬유의 색분산이 D=4ps/nm/km일 경우 가장 컸으며 그 양쪽으로 패널티는 줄어들었다.