• Macromolecular Research
• /
• 제10권4호
• /
• pp.236-239
• /
• 2002

Centrifugation is a method to create functionally graded materials (FGM) with a thermosetting matrix. In this study the movement of short carbon fibers in an epoxy resin during the centrifugation process was modeled to determine the fiber distribution in the final product. For this purpose a form factor K was introduced to modify a set of equations that was previously shown to be valid for the motion of spheres. It was shown that the results of the simulation were in good agreement with the experimental data, when an empirical K factor of four was chosen.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2000년도 추계학술발표대회 논문집
• /
• pp.42-45
• /
• 2000

The properties of thermosetting resins are dependent on the degree of cure and consolidation quality. Since the consolidation process of thermosetting resin matrix fiber composites is much dependent on the viscosity of resin in the composites, in this study, the dissipation factor which is a function of viscosity was measured by the newly developed Lacomtech dielectrometry apparatus and sensors. Using the measured dissipation factors, the relationship between the dissipation factor and degree of cure with respect to environmental temperature was investigated.

• 농업생명과학연구
• /
• 제50권2호
• /
• pp.151-160
• /
• 2016

염증성 사이토카인은 파골세포형성과정에서 중요한 요인이며, 뼈의 흡수는 자주 골다공증과 연결된다. 설포라판은 보로콜리의 화뢰로 부터 분리된 물질로 염증성 사이토카인을 억제한다고 알려져 있다. 본 실험에서는 Receptor activator of nuclear factor kappaB ligand(RANKL)로 자극된 세포에서 설포라판이 파골세포 형성 억제에 대한 효과를 측정하였다. 설포라판은 대식세포인 RAW 264.7 세포에서 파골세포 특이 마커 유전자인 tartrate-resistant acid phosphatase(TRAP), Cathepsin K, matrix metalloproteinase 9(MMP-9), calcitonin receptor을 저해하였으며, TRAP, MMP-9, tumor necrosis factor receptor-associated factor 6(TRAF6)와 전사인자인 nuclease factor of activated T cells(NFATc1)의 단백질 발현과 RANKL로 자극하였을 때 전자인사인 nuclear factor kappaB(NF-kappaB)의 전사활성도 억제 하였다. 이와 같은 결과로 설포라판이 NF-kappaB의 전사활성 억제뿐만 아니라, 파골세포형성인자(TRAP, cathepsin K, MMP-9, calcitonin, NFATc1)와 NFATc1의 발현을 억제시키는 효과가 있음을 확인하였다.

• Tuberculosis and Respiratory Diseases
• /
• 제51권6호
• /
• pp.530-539
• /
• 2001

연구배경 : 기관지 천식은 기도의 재구성과 관련된 기도의 염증성 질환이다. Vascular endothelial growth factor(VEGF) 는 혈관생성과 염증반응에 관여하는 강력하고 다양한 기능의 사이토카인이며 Matrix metalloproteinase-9(MMP-9)은 기관지 천식에서 기도의 재구성을 일으키는 주요 단백분해 효소이다. 그러나, 아직 급성 기관지 천식에서 VEGF의 역할 및 VEGF와 MMP-9의 관련성등에 관한 보고는 거의 없다. 저자들은 급성 기관지 천식에서 VEGF가 기관지 염증반응에 관여하는지를 조사하였고 또한 객담내 VEGF 발현 정도와 MMP-9의 관련성도 같이 알아보고자 하였다. 방 법 : 저자들은 안정상태 및 급성천식상태 환자에서 객담내 VEGF와 MMP-9의 양을 효소 면역측정과 zymography 분석으로 측정하였고 또한 기관지 천식의 자발 발작시에도 측정하였다. 결 과 : 기관지 천식 환자군에서 안정상태의 천식환자군이나 건강 대조군보다 객담내 VEGF 양이 유의있게 높음을 알 수 있었고 또한 천식 발작시에는 안정시보다 더 유의있게 높았으며 천식치료후 점차 감소하였다. 급성 천식 환자들에서 객담내 VEGF농도는 호중구및 호산구들 수와 의의있게 관련이 있었고 또한 객담내 VEGF와 MMP-9의 농도사이에 유의있는 상관관계가 있음을 알 수 있었다. 결 론 : 급성 기관지 천식 환자에서 VEGF의 과도발현은 기도 염증반응과 관련이 있으며 또한 MMP-9과도 밀접한 연관성이 관련성이 있는 것으로 사료된다.

• 한국공작기계학회논문집
• /
• 제16권3호
• /
• pp.125-132
• /
• 2007

The purpose of present paper is to investigate a fracture characteristics of the finite-width single-edge-notch(SEN) carbon fiber/epoxy reinforced plastics(CFRP) plates by using an acoustic emission(AE). Uni-directionally oriented 10 plies CFRPs specimen which had different notch length were prepared for monotonic tensile test. Matrix cracking appeared over whole testing process and fiber breaking appeared later on mainly Load distribution factor of the matrix confirmed that increased according as increases of plate width ratio. The amplitude distribution of AE signal from a specimens is an aid to the determination of the different fracture mechanism such as matrix cracking, disbonding, interfacial delamination, fiber pull-out, fiber breaking, and etc. In the result of AE amplitude distribution analysis, matrix cracking, fiber disbonding or interfacial delamination, and fiber pull-out or fiber breaking signal correspond to <65dB, <75dB, and <90dB respectively, Also, changes of the slope of cumulative AE energy represented crazing phenomena or degradation of materials.

• 한국정밀공학회지
• /
• 제29권10호
• /
• pp.1050-1055
• /
• 2012

The bearing coupling section of machine tools is the most important factor to determine their static/dynamic stiffness. To ensure the proper performance of machine tools, the static/dynamic stiffness of the rotating system has to be predicted on the design stage. Various parameters of the bearing coupling section, such as the spring element, node number and preload influence the characteristics of rotating systems. This study focuses on the prediction of the static and dynamic stiffness of the rotating system with the bearing coupling section using the finite element (FE) model. MATRIX 27 in ANSYS has been adopted to describe the bearing coupling section of machine tools because the MATRIX 27 can describe the bearing coupling section close to the real object and is applicable to various machine tools. The FE model of the bearing couple section which has the sixteen node using MATRIX 27 was constructed. Comparisons between finite element method (FEM) predictions and experimental results were performed in terms of the static and dynamic stiffness.

• Asian Pacific Journal of Cancer Prevention
• /
• 제16권17호
• /
• pp.7393-7400
• /
• 2015

Matrix metalloproteinase (MMP) 9, a key member of multifunctional family of zinc dependent endopeptidases has been found to be upregulated during inflammation and in some cancers. MMPs cleave extracellular matrix (ECM) proteins and play critical roles in cellular apoptosis, angiogenesis, tumor growth and metastasis. Several genetic polymorphisms have been identified that show allele specific effects on MMP9 regulation and are associated with gastric cancer, the fourth most common malignancy in the world. Besides Helicobacter pylori infection, genetic predisposition is another documented risk factor for gastric carcinoma. The single nucleotide polymorphism (SNP) at position -1562C/T of MMP9 results in the modulation for binding of transcription factors to the MMP9 gene promoter and thereby causes differences in protein expression and enzymatic activity. MMP9 transcriptional regulation during gastric cancer development remains poorly known although several studies have demonstrated associations between MMP9 -1562 C/T polymorphism with different diseases. Knowledge on mechanisms of MMP9 upregulation during gastric cancer may provide new paradigm in diagnostics and therapeutics.

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

• 대한후두음성언어의학회지
• /
• 제32권1호
• /
• pp.15-23
• /
• 2021

Background and Objectives During speech, the vocal folds oscillate at frequencies ranging from 100-200 Hz with amplitudes of a few millimeters. Mechanical stimulation is an essential factor which affects metabolism of human vocal folds. The effect of mechanical vibration on the cellular response in the human vocal fold fibroblasts cells (hVFFs) was evaluated. Materials and Method We created a culture systemic device capable of generating vibratory stimulations at human phonation frequencies. To establish optimal cell culture condition, cellular proliferation and viability assay was examined. Quantitative real time polymerase chain reaction was used to assess extracellular matrix (ECM) related and growth factors expression on response to changes in vibratory frequency and amplitude. Western blot was used to investigate ECM and inflammation-related transcription factor activation and its related cellular signaling transduction pathway. Results The cell viability was stable with vibratory stimulation within 24 h. A statistically significant increase of ECM genes (collagen type I alpha 1 and collagen type I alpha 2) and growth factor [transforming growth factor β1 (TGF-β1) and fibroblast growth factor 1 (FGF-1)] observe under the experimental conditions. Vibratory stimulation induced transcriptional activation of NF-κB by phosphorylation of p65 subunit through cellular Mitogen-activated protein kinases activation by extracellular signal regulated kinase and p38 mitogen-activated protein kinases (MAPKs) phosphorylation on hVFFs. Conclusion This study confirmed enhancing synthesis of collagen, TGF-β1 and FGF was testified by vibratory stimulation on hVFFs. This mechanism is thought to be due to the activation of NF-κB and MAPKs. Taken together, these results demonstrate that vibratory bioreactor may be a suitable alternative to hVFFs for studying vocal folds cellular response to vibratory vocalization.

• Journal of Pharmaceutical Investigation
• /
• 제26권3호
• /
• pp.187-192
• /
• 1996

The matrix tablet containing sodium alginate and $CaHPO_4$ can release drugs in a controlled fashion from hydrogel with gelling and swelling due to their interaction as water penetrates the matrices of the tablet. The purpose of this study was to evaluate release characteristics of the matrix tablet varying the amount of sodium alginate, $CaHPO_4$ and other excipients such as chitosan, hydroxypropyl methylcellulose (HPMC) and $Eudragit^{\circledR}$ RS100 in the simulated gastric and intestinal fluid. The practically soluble ibuprofen was used as a model drug. The release profiles of matrix tablet in the gastric fluid as a function of sodium alginate/$CaHPO_4$ ratio was not pronounced because of low solubility of drug and stability of alginate matrices. However, release rate of drug from the matrix tablet in the intestinal fluid was largely changed when sodium alginate/$CaHPO_4$ ratio was increased, suggesting that the ratio of sodium alginate/$CaHPO_4$ was an important factor to control the gelling and swelling of the matrix tablet. The incorporation of other excipients into the matrix tablet also influenced the release rate of drug. The chitosan and HPMC decreased the release rate of drug. No release of drug was occurred when $Eudragit^{\circledR}$ RS100 was added into the tablet. The retarded release of matrix tablet when excipients were added resulted from the hindrance of swelling and gelling of the matrix tablet containing sodium alginate and $CaHPO_4$. The hardness and bulk density of the matrix tablet was not correlated with release rate of drug in the study. From these findings, the ratio of sodium alginate and $CaHPO_4$ in the matrix tablet in addition to incorporation of excipients could be very important to control the release rate of drug in dosage form design.