• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.39-43
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• 2009

In this paper, the flow characteristics of underfill material driven by capillary action between flip-chip and substrate were investigated. Also, the effects of viscosity level and dispensing point of underfill on flow characteristics were investigated. Flip chip package size was $5mm{\times}5mm{\times}0.65^tmm$, the diameter of solder bump was 100 ${\mu}m$, and the pitch was 150 ${\mu}m$. It was full grid area-array type with 1024 I/Os. The glass substrate was used and the gap between the chip and substrate was 50 ${\mu}m$. For the experimental study, three different underfills with different viscous properties($2000{\sim}3700$ cps), and two different types of dispensing methods(center dot and edge dot) were used. The flow characteristics and filling time of underfill were investigated by using CCD camera. The results show that the edge flow was faster than center flow due to the edge effect, which was caused by the resistance of solder bumps. In case of edge dot dispensing type, the filling time was faster due to the large edge effect, compared to center dot dispensing type. Also, it was found that the underfill flow was faster and the filling time decreased as the viscosity level of underfill was decreased.

• Journal of Korea Water Resources Association
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• v.53 no.10
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• pp.889-902
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• 2020

This study was performed in Seolmacheon basin to evaluate the adequacy of GLDAS (Global Land Data Assimilation System) and GLEAM (Global Land Evaporation Amsterdam Model) evapotranspiration data. The verification data necessary for the evaluation of adequacy were calculated after processing the latent heat flux data produced in the Seolmacheon basin with the Koflux program. In order to gap-fill the empty period, alternative evapotranspiration was calculated in three ways: FAO-PM (Food and Agriculture Organization-Penman Monteith), MDV (Mean Diurnal Variation) and Kalman Filter. This study selected Kalman Filter method as the data gap-filling method because it showed the best Bias and RMSE among the three methods. The amount of GLDAS spatial evapotranspiration was calculated as Noah (version 2.1) with a time interval of 3 hours and a spatial resolution of 0.25°. The amount of GLEAM spatial evapotranspiration was calculated using GLEAM (version 3.1a). This study evaluated the spatial evapotranspiration of GLDAS and GLEAM as the evapotranspiration based on eddy covariance. As a result of evaluation, GLDAS spatial evapotranspiration showed better results than GLEAM. Accordingly, in this study, the GLDAS method was proposed as a method for calculating the amount of spatial evapotranspiration in the Seolmacheon basin.

• Korean Journal of Materials Research
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• v.3 no.2
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• pp.121-130
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• 1993

The GaP crystals were grown by synthesis solute diffusion method and its properties were investigated. High quality single crystals were obtained by pull-down the crystal growing ampoule with velocity of 1.75mm/day. Etch pits density along vertical direction of ingot was increased from 3.8 ${\times}{10^4}$c$m^{-2}$ of the first freeze to 2.3 ${\times}{10^5}$c$m^2$ of the last freeze part. The carrier concentration and mobilities at room temperature were measured to 197.49cc$m^2$/V.sec and 6.75 ${\times}{10^{15}}$c$m^{-3]$, respectively. The temperature dependence of optical energy gap was empirically fitted to $E_g$(T)=[2.3383-(6.082${\times}{10^{-4}}$)$T^2$/(373. 096+TJeV. Photoluminescence spectra measured at low temperature were consist with sharp line-spectra near band-gap energy due to bound-exciton and phonon participation in band edge recombination process. Zn-diffusion depth in GaP was increased with square root of diffusion time and temperature dependence of diffusion coefficient was D(Tl = 3.2 ${\times}{10^3}$exp( - 3.486/$k_{\theta}$T)c$m^2$/sec. Electroluminescence spectra of p-n GaP homojunction diode are consisted with emission at 630nm due to recombination of donor in Zn-O complex center with shallow acceptors and near band edge emission at 550nm. Photon emission at current injection level of lower than 100m A was due to the band-filling mechanism.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.229-234
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• 2006

On May 31, 2003. Landsat 7 experienced an anomaly causing the Scan Line Corrector(SLC) to stop functioning normally. The SLC-off causes individual scan lines to alternately overlap and then leave large gaps at the edge of the Image. A many scientists with ongoing experience using ETM+ data evaluated the scientific usability and validity of Landsat 7 products containing the SLC anomaly The best reference scene for gap-filling is the other SLC-on Landsat scene that provide same resolution, few changes, and similar data acquisition. But receiving of Landsat imagery is not stable in Korea. So SPOT image can be another alternative solution because it is a steady-state multispectral satellite image as Landsat image. In this study, we filled the SLC-off gap s of 2, 3, 4 bands using SPOT image by a local regression technique, and assigned the optimum spectral value to gaps of 1, 5, 7 bands based on a spectral adjacency. Through this process, we could restore Landsat SLC-off image and evaluated the accuracy of the results.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.2
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• pp.5-9
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• 2015

Thermal management becomes serious in 3D stacked IC because of higher heat flux, increased power generation, extreme hot spot, etc. In this paper, we reviewed the recent developments of thermal management for 3D stacked IC which is a promising candidate to keep Moore's law continue. According to experimental and numerical simulation results, Cu TSV affected heat dissipation in a thin chip due to its high thermal conductivity and could be used as an efficient heat dissipation path. Other parameters like bumps, gap filling material also had effects on heat transfer between stacked ICs. Thermal aware circuit design was briefly discussed as well.

• Journal of the Korean Geotechnical Society
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• v.37 no.4
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• pp.19-26
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• 2021

The high-level radioactive waste (HLW) produced from nuclear power plants is disposed in a rock-mass at a depth of hundreds meters below the ground level. Since HLW is very dangerous to human being, it must be disposed of safely by the engineered barrier system (EBS). The EBS consists of a disposal canister, backfill material, buffer material, and so on. When the components of EBS are installed, gaps inevitably exist not only between the rock-mass and buffer material but also between the canister and buffer material. The gap can reduce water-retarding capacity and heat release efficiency of the buffer material, so it is necessary to investigate properties of gap-filling materials and to analyze gap spacing effect. Furthermore, there has been few researches considering domestic disposal system compared to overseas researches. In this reason, this research derived the peak temperature of the bentonite buffer material considering domestic disposal system based on the numerical analysis. The gap between the canister and buffer material had a minor effect on the peak temperature of the bentonite buffer material, but there was 40% difference of the peak temperature of the bentonite buffer material because of the gap existence between the buffer material and rock mass.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1341-1352
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• 2023

The normalized difference vegetation index (NDVI) derived from satellite images is a crucial tool to monitor forests and agriculture for broad areas because the periodic acquisition of the data is ensured. However, optical sensor-based vegetation indices(VI) are not accessible in some areas covered by clouds. This paper presented a synthetic aperture radar (SAR) based approach to retrieval of the optical sensor-based NDVI using machine learning. SAR system can observe the land surface day and night in all weather conditions. Radar vegetation indices (RVI) from the Sentinel-1 vertical-vertical (VV) and vertical-horizontal (VH) polarizations, surface elevation, and air temperature are used as the input features for an automated machine learning (AutoML) model to conduct the gap-filling of the Sentinel-2 NDVI. The mean bias error (MAE) was 7.214E-05, and the correlation coefficient (CC) was 0.878, demonstrating the feasibility of the proposed method. This approach can be applied to gap-free nationwide NDVI construction using Sentinel-1 and Sentinel-2 images for environmental monitoring and resource management.

• English Language & Literature Teaching
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• v.16 no.1
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• pp.61-80
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• 2009

This study investigates the effects of different types of genre and tasks on college students' English listening comprehension. 104 college students were assigned to Argumentative (AG), Causal and Evaluation (CE), and Narrative (NA) group. They report their listening comprehension through gap-filling (GF), summary (ST), and multiple-choice comprehension task (MC). Results showed that different genre groups were significantly different on overall tasks. Moreover, results from each group also presented that different mean scores on each task indicated a statistical significance. Proficiency levels, higher and lower level group, showed a significant effect for the task on listening comprehension. The results of the statistical analysis, using One-way ANOVA indicated that genre significantly affects Korean college students' listening comprehension, and implied that listening comprehension sores for each genre were also substantially different. Different genre groups resented significant different in overall listening comprehension tasks.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.1
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• pp.20-30
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• 2001

A 1.8V $650{\;}\textrm{mm}^2$ 4Gb DRAM having $0.10{\;}\mu\textrm{m}^2$ cell size has been successfully developed using 0.11 $\mu\textrm{m}$DRAM technology. Considering manufactur-ability, we have focused on developing patterning technology using KrF lithography that makes $0.11{\;}\mu\textrm{m}$ DRAM technology possible. Furthermore, we developed novel DRAM technologies, which will have strong influence on the future DRAM integration. These are novel oxide gap-filling, W-bit line with stud contact for borderless metal contact, line-type storage node self-aligned contact (SAC), mechanically stable metal-insulator-silicon (MIS) capacitor and CVD Al process for metal inter-connections. In addition, 80 nm array transistor and sub-80 nm memory cell contact are also developed for high functional yield as well as chip performance. Many issues which large sized chip often faces are solved by novel design approaches such as skew minimizing technique, gain control pre-sensing scheme and bit line calibration scheme.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.388-391
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• 2004

This research investigates how the fineness modulus of fine aggregates and the grain shape of coarse aggregates affects flow characteristics, packing characteristics and compressive strength characteristic. The experimental results, show that increase of the fine aggregate's fineness modulus improved concrete flow, but filling ability was high at over KS regulation extent due to segregation phenomena. It is considered that the improvement of 0.1 spherical rate was effective to concrete fluidity elevation by reducing about $6\%$ of fine aggregate ratio displays which the smallest gap rate of aggregate. Compressive strength was increased to about 0.6MPa everytime F.M. 0.1 of fine aggregate fineness is increased. However, it was decreased to about 9MPa at F.M. 3.5 compared to F.M. 3.0.