• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2437-2444
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• 2012

Tumor metastasis remains the principal cause of treatment failure and poor prognosis in patients with colorectal cancer. It is a multistage process which includes proteolysis, motility and migration of cells, proliferation in a new site, and neoangiogenesis. A crucial step in the process of intra- and extra-vasation is the activation of proteolytic enzymes capable of degrading the extracellular matrix (ECM). In this stage, urokinase plasminogen activator receptor (uPAR) and matrix metalloproteinases (MMPs) are necessary. Micrometastases need the presence of growth factor and vascular growth factor so that they can form macrometastasis. In addition, cell adhesion molecules (CAMs) and guanine nucleotide exchange factors (GEFs) play important roles in the progression of colorectal cancer and metastatic migration. Further elucidation of the mechanisms of how these molecules contribute will aid in the identification of diagnostic and prognostic markers as well as therapeutic targets for patients with colorectal metastasis.

• East Asian mathematical journal
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• v.28 no.2
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• pp.173-195
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• 2012

The purpose of this study is to help for an in-depth understanding of their thinking process by observing and analyzing the response found by two elementary school students, Through this study, the following findings could be obtained. First, two students have a tendency trying to solve the complex situation at first. Second, we could know that it is an important factor in discovering the pattern to predict it. Third, we could know that the activity of reconstructing the data meaningfully is an important factor in discovering the pattern. Fourth, it is an important factor in finding the pattern to work organically the activity of predicting it with the activity of reconstructing the data meaningfully. We hope that this study offers the help for an in-depth understanding of students's thinking process.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.4
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• pp.17-23
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• 1984

A model analysis of pattern shift in the epitaxial growth of silicon on (111) substrates was performed. The growth rate anisotropy was considered as the most important affecting factor of pattern shift, and for the model establishment the off angle of the substrate and the process temperature were taken as the variables. We derived a theoretical equation of pattern shift by assuming the growth rate anisotropy as the trigonometric sine function of the off angle of the substrate and defining the growth rate anisotropy factor related to the process temperature. The pattern shift ratio calculated by this model had the same tendency with the experimental ones, which, however, were about twice greater than those. It was supposed that this discrepailcy was due to the second order affecting factor such as facetting and step broadening which had been exluded in model establishment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.3-7
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• 1996

Metal Matrix Composite(MMC) material of 30% SiC particulate based on A1 matrix was machined by drilling and Electrical Discharge Machining (EDM) processes. When drilling process was executed, surface fracture due to brittle property near the bottom was found. It was also found the possiblity of difficult shape of EDM process for MMC material, but few the research about basic EDM characteristics. Material Removal Rate(MRR) was examined for different conditions and the surface morphology was evaluated by roughness values and Scanning Electron Microscopy(SEM) research. The higher the current is, the more MRR was obtained but the higher MRR was showed around 0.45 duty factor. The average roughness of EDMed surface was slightly changed with increased pulse current and increases with duty factor. The SEM photographs of EDMed surface showed recast region after melting.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.4
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• pp.24-29
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• 2020

Measuring the torque of the wheel loader of a driving device is a preemptive task to ensure its performance. In this study, wireless torque measurements were successfully conducted. Moreover, based on the experimental results and the adopted design method, the key factor of torque generation, which is the main load in driving devices, was analyzed. Other data not analyzed in this paper will be the basis for the logical design of wheel loader-based driving devices.

• Korean Journal of Computational Design and Engineering
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• v.21 no.2
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• pp.151-158
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• 2016

It is important to analyze dimensional errors occurring during shipbuilding process. A ship is constructed by assembling blocks and installing outfits in assembled ship structure. Blocks and outfits have a main direction that has greater importance than other directions from the view point of dimensional error. Therefore, a main direction should have a greater weighting factor than other directions in order to achieve meaningful inspection results. In this paper, a modified point registration method based on iterative closest point (ICP) is proposed. In this method, a user determines one or two main directions among x, y, and z directions, and then each main direction is made to have a greater weighting factor than other directions. For points registration, mapping between measured points and design points are performed by the modified ICP in which weighting factor assigned to each main direction is considered.

• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2294-2302
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• 2004

The objective of this study is to obtain detailed information for the micro fabrication of lead frames by applying spray technology to wet etching process. Wet etching experiments were performed with different etching parameters such as injection pressure, distance from nozzle tip to etched substrate, nozzle pitch and etchant temperature. The characteristics of single and twin spray were measured to investigate the correlation between the spray characteristics and the etching characteristics. Drop size and velocity were measured by Phase-Doppler Anemometer (PDA). Four liquids of different viscosity were used to reveal the effects of viscosity on the spray characteristics. The results indicated that the shorter the distance from nozzle tip and the nozzle pitch, the larger etching factor became. The average etching factor had good positive correlation with average axial velocity and impact force. It was found that the etching characteristics depended strongly on the spray characteristics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.115-118
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• 2002

The purpose of this paper is to design a pick-up for the small form factor optical disk drive and to fabricate a micro-compensatory lens for the pick-up using the micro-compression molding process. At design stage, the optical elements including the objective lens and the compensatory lens are miniaturized. The height of pick-up and free working distance are designed as 2mm and 0.2% respectively. To analyze the fabricated micro-compensatory lens, the system was analyzed using the surface profile of the fabricated micro-compensatory lens and CODE V which is commercial software. The RMS wave front aberration of the system using fabricated micro-compensatory lens is 0.01677λ which is lower than Marechal's criterion, 0.07λ.

• Journal of Power Electronics
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• v.15 no.1
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• pp.227-234
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• 2015

This paper presents the application of bee colony optimization (BCO) to obtain the optimal switching angles for single phase PWM AC choppers. The optimal switching angles are found in the region of 0-${\pi}$ based on the asymmetrical PWM technique. This PWM process results in improvements of the total harmonic distortion of the output voltage and in the input power factor. Simulation and experimental results are compared with the conventional PWM to verify the performance of the proposed PWM process.

• Fire Science and Engineering
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• v.7 no.1
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• pp.17-29
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• 1993

The method has been proposed for the risk assessment of petro-chemical plant, specially which can evaluate relative risk levels on the materials and process-es. The each potential risk of materials and processes are derived numerically and combined these values, finally Fire and Explosion Index was found. Material factor was evaluated with the flammability and the reactivity and process factor with emprical factor called penalty. This F&EI can be performed for relative risk assesment at the whole plant and directely applicable at the line.