• Journal of Environmental Science International
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• v.7 no.4
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• pp.511-522
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• 1998

The two-stage numerical model was used to study the relation between three-dimensional local wind seal area for Korean peninsula. The first stave is three dimensional time-dependent local wind model which elves the wind field and vertical diffusion coefncient. The second stage is advection/duusion model which uses the results of the first stage as input data. First, wand fields on Korean peninsula for none synoptic scale wand showed typical land and sea breeze circulation, and the emitted particles were transported by sea breeze for daytime, emissions return to sea by land breeze for nighttime.

• Journal of the Korea Society for Simulation
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• v.11 no.3
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• pp.59-65
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• 2002

Semiconductor wafer fabrication is a business of high capital investment and fast changing nature. To be competitive, the production in a fab needs to be effectively planned and scheduled starting from the ramping up phase, so that the business goals such as on-time delivery, high output volume and effective use of capital intensive equipment can be achieved. Project executed that use conveyor in bay semiconductor A line. But conveyor capability is lacking and rundown happened in equipment. Do design without normal simulation and conveyor system failed. The comparison is peformed through simulation using .AutoMod a window 98 based discrete system simulation software, as a tool for comparing performance of proposed layouts. In this research estimate optimum conveyor capability, there is the purpose.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.125-132
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• 1995

Studies were made on differences among types and varieties of rice in stomatal density and gas diffusion resistance, and on the relationship between these traits and photosynthetic rate. Significant differences among types and varieties were found stomatal density and gas diffusion resistance. Generally, stomatal density was higher in indica varieties than in Japonica varieties, gas diffusion resistance was lower in the former than in the later, in varieties developed through indica-japonica hybridization it was intermadiate. The stomatal density was closely positively correlated with the gas conductivity and the net photosynthetic rate, was not correlated with single leaf area, and had significant negative correlation with specific leaf weight. Higher photosynthetic rate of indica varieties mainly results from its high stomatal density and low gas diffusion resistance. The result also suggested that high photosynthetic rate might be obtained if the high stomatal density and low gas diffusion resistance in indica could be combined with the larger specific leaf weight in japonica through crossing between two.

• Journal of the Semiconductor & Display Technology
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• v.9 no.2
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• pp.33-39
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• 2010

The moisture absorption properties such as diffusion coefficient and moisture content ratio of liquid type epoxy resin systems with the filler were investigated. Bisphenol A type and Bisphenol F type epoxy resin, Kayahard MCD as hardener and 2-methylimidazole as catalyst were used in these epoxy resin systems. The nano-sized spherical type fused silica as filler were used in order to study the moisture absorption properties of these liquid type epoxy encapsulant according to the change of filler size. The temperature of glass transition (Tg) of these epoxy resin systems was measured using Dynamic Scanning Calorimeter (DSC), and the moisture absorption properties of these epoxy resin systems according to the change of time were observed at $85^{\circ}C$ and 85% relative humidity condition using a thermo-hygrostat. The diffusion coefficients in these systems were calculated in terms of modified Crank equation based on Ficks' law. An increase of Tg and diffusion coefficient with filler size in these systems can be observed, which are attributed to the increase of free volume with Tg. The change of maximum moisture absorption ratio according to the filler size and filler content cannot be observed; however, the diffusion coefficients of these systems decreased with filler content. The diffusion via free volume is dominant in the epoxy resin systems with low nano-sized filler content; however, the diffusion with the interaction of absorption according the increase of the filler surface area is dominant in the liquid type epoxy encapsulant with high nano-sized filler content.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2006.10a
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• pp.156-157
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• 2006

• Journal of the Society of Naval Architects of Korea
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• v.34 no.2
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• pp.104-110
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• 1997

Increase of marine transpotation in coastal area frequently yields oil spill accidents due to collision or grounding of oil tankers, which affects great deal of damages on ocean environments. Exact prediction of oil pollution area in time domain, which is called oil map, is very important for effective and efficient oil recovery and minimization of environmental damage. The prediction is carried out by considering the two distinct processes which are initial diffusion on the still water surface and advection due to tide, wind wave induced surface currents. In the present paper, only the initial diffusion is dealt with. Somewhat new simulation model and its numerical scheme are proposed to predict it. Simple diffusion experiment is also carried out to check the validity of the present method. Furthermore, some example simulations are performed for virtual oil spill accident. Quite realistic oil map including oil thickness distributions can be obtained by the present model.

• Journal of Welding and Joining
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• v.31 no.3
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• pp.76-83
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• 2013

This study investigated the effect of bonding temperature and holding time on microstructures and mechanical properties of diffusion bonded joint of Haynes230. The diffusion bonds were performed at the temperature of 950, 1050, and $1150^{\circ}C$ for holding times of 30, 60, 120 and 240 minutes at a pressure of 4MPa under high vacuum condition. The amount of non-bonded area and void observed in the bonded interface decreased with increasing bonding temperature and holding time. Cr-rich precipitates at the linear interface region restrained grain migration at $950^{\circ}C$ and $1050^{\circ}C$. However, the grain migration was observed in spite of short holding time due to the dissolution of precipitates to base metal in the interface region at $1150^{\circ}C$. Three types of the fracture surface were observed after tensile test. The region where the coalesce and migration of grain occurred much showed high fracture load because of base metal fracture whereas the region where those did less due to the precipitates demonstrated low fracture load because of interface fracture. The expected fracture load could be derived with the value of fracture area of base metal ($A_{BF}$) and interface ($A_{IF}$), $Load=201A_{BF}+153A_{IF}$. Based on this equation, strength of base metal and interface fracture were calculated as 201MPa and 153MPa, respectively.

• Applied Microscopy
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• v.34 no.2
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• pp.95-102
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• 2004

The TEM samples prepared by ion milling have the advantage that thin area can be obtained from almost any materials. However, it has the disadvantage that the amount of thin area can often be quite limited. For the cross-sectioned samples and grossly heterogeneous materials, the thickness of less than $0.1{\mu}m$ can be achieved by mechanical grinding and polishing (tripod polisher) and then the TEM samples may be ion-milled for final thinning or cleaning. These approaches were described in this paper. Examples of TEM observations were taken from cross-section samples of thin films on silicon and sapphire, from diffusion layers between $Mo_5Si_3\;and\;Mo_2B$, and from rapidly solidified 304 stainless steel powders embedded in electroplated copper.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.231-234
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• 2000

This paper has been studied a method that effectively displaying color image to monochromatic display such as PDA and movable-phone. Generally, the Floyd-Steinberg dithering algorithm has been used in this area and its' effectiveness were well known. But it shows some ugly patterns in white area and also shows some directionality in vertical and horizontal directions. To reduce those directionality, I suggest the error diffusion direction to be rotated randomly according to the bit value of the current position. This can also mitigate some ugly pattern in white area

• Korean Journal of Radiology
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• v.20 no.5
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• pp.791-800
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• 2019

Objective: To compare various models of diffusion-weighted imaging including monoexponential apparent diffusion coefficient (ADC), biexponential (fast diffusion coefficient [D_f], slow diffusion coefficient [D_s], and fraction of fast diffusion), stretched-exponential (distributed diffusion coefficient and anomalous exponent term [α]), and kurtosis (mean diffusivity and mean kurtosis [MK]) models in the differentiation of renal solid masses. Materials and Methods: A total of 81 patients (56 men and 25 women; mean age, 57 years; age range, 30-69 years) with 18 benign and 63 malignant lesions were imaged using 3T diffusion-weighted MRI. Diffusion model selection was investigated in each lesion using the Akaike information criteria. Mann-Whitney U test and receiver operating characteristic (ROC) analysis were used for statistical evaluations. Results: Goodness-of-fit analysis showed that the stretched-exponential model had the highest voxel percentages in benign and malignant lesions (90.7% and 51.4%, respectively). ADC, D_s, and MK showed significant differences between benign and malignant lesions (p < 0.05) and between low- and high-grade clear cell renal cell carcinoma (ccRCC) (p < 0.05). α was significantly lower in the benign group than in the malignant group (p < 0.05). All diffusion measures showed significant differences between ccRCC and non-ccRCC (p < 0.05) except D_f and α (p = 0.143 and 0.112, respectively). α showed the highest diagnostic accuracy in differentiating benign and malignant lesions with an area under the ROC curve of 0.923, but none of the parameters from these advanced models revealed significantly better performance over ADC in discriminating subtypes or grades of renal cell carcinoma (RCC) (p > 0.05). Conclusion: Compared with conventional diffusion parameters, α may provide additional information for differentiating benign and malignant renal masses, while ADC remains the most valuable parameter for differentiation of RCC subtypes and for ccRCC grading.