• Applied Microscopy
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• v.32 no.4
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• pp.311-317
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• 2002

There is great requirement on the TEM specimen preparation method with particle size selectivity as a prerequisite for the quantitative structure analysis on the materials such as gibbsite powder, which generally forms a large agglomerate and shows a variation of transition process depending on their sizes. In this experiment, we made an attempt to give a methodology for the TEM specimen preparation of powder with the size selectivity. After mixing 1 wt% gibbsite powder with ethanol solvent, gibbsite suspension was prepared by application of ball-milling and ultrasonification with addition of 0.25 vol% dispersion agent, Darvan C, which was diluted into distilled water by the ratio 1:19. Appling the static sedimentation method to gibbsite suspension after estimation of the sedimentation time by the measurement of accumulative concentration variation, we acquired TEM specimens with well-dispersed and size selected gibbsite particles in nm scale. Overall picture of each sample was taken by SEM and morphology of each dispersed particle was imaged by TEM. Raw and processed gibbsite powders were also examined by XRD to investigate whether they were suffered from phase change during the process or not.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.2
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• pp.92-102
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• 2004

In this paper, an analytical solution of calculating the excess temperature field due to a point heat source is presented in the presence of spring-neap modulation of convective alongshore flow. The basic form of the solution is identical to that given by Jung et al. (2003) but the convective term in the exponential kernel function is extended and a spring-neap variation in the horizontal eddy diffusivity is newly introduced. A set of calculations have been performed to examine the sensitivity of the heat build-up to the change in current fields and turbulent dispersion. Results indicate that the excess temperature field is confined within the tidal excursion distance, while the excess temperature field beyond the distance is mainly controlled by the horizontal diffusion. The heat build-up within the distance is considerably affected by the spring-neap variation in the horizontal eddy diffusivity; the relatively high excess temperature more than 1$^{\circ}C$ is extended further when the eddy diffusivity has spring-neap modulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.77-80
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• 2001

Crystallographic and magnetic characteristics of CoCr-based magnetic thin film for perpendicular magnetic recording media were influenced on preparing conditions. In these, there is that substrate temperature was parameter that increases perpendicular coercivity of CoCrTa magnetic layer using recording layer. While preparation of CoCr-based doublelayer, by optimizing substrate temperature, we expect to increase perpendicular anisotropy of CoCr magnetic layer and prepare ferromagnetic recording layer with a good quality by epitaxial growth. CoCrTa/Si doublelayer showed a good dispersion angle of c-axis orientation $\Delta\theta_{50}$ caused by inserting amorphous Si underlayer which prepared at underlayer substrate temperature 250C. Perpendicular coercivity was constant, in-plane coercivity was controlled a low value about 200Oe. This result implied that Si underlayer could restrain growth of initial layer of CoCrTa thin film, which showed bad magnetic properties effectively without participating magnetization patterns of magnetic layer. In case of CoCrTa/Si that prepared with ultra thin underlayer, crystalline orientation of CoCrTa was improved rather underlayer thickness 1nm, it was expected that amorphous Si layer played a important role in not only underlayer but also seed layer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.197-203
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• 2013

Optical power optimization of 10 Gbps 40 wavelength division multiplexing channels was analyzed at the 3000 km long-haul transmission distance when the link span distance was changed between 40 km and 140 km. The signal performance of the transmission was obtained as a Q value and it was compared when input power into SSMF and input power into DCF on the transmission link were changed. The optimized input power into SSMF increased linearly to link span distance with 1 dB/km. The optimized power into DCF increased linearly with 0.5 dB/km up to 100 km link span, but it had no variation at longer link span than 100 km.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1288-1291
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• 2004

In this study, physical characteristics of alumina slurry on variation of pH value and the effect of non-ionic surfactants on alumina slurry for copper chemical mechanical planarization (CMP) slurry have been investigated. After pH value of the slurry with alumina abrasive was changed by adding various amount of $HNO^3$ or KOH, the differences of settling rate, particle size, and zeta-potential were estimated. Better settling rates were shown in slurries with alumina abrasive at near pH 1. Higher zeta-potential was shown at around pH 2 in alumina slurry and the point of zero charge (PZC) was measured at about pH $9\sim10$. Non-ionic surfactant was added in the slurry with 5wt% alumina abrasive to get its effect on slurry practically. Abrasive size was smaller increased when amount of surfactant increased in slurry with P-4 as abrasive; on the other side, it was smaller when amount of surfactant decreased with AES-12. Variation of zeta-potential has no tendency with adding surfactant; however, values of zeta-potential were between $35\sim50mV$. The proper amount of surfactant was $0.1\sim1.0wt%$ in slurry with P-4 and $0.5\sim1.0wt%$ in slurry with AES-12 respectively. Excellent dispersion stabilization was obtained by addition of non-ionic surfactant

• 한국해양학회지
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• v.18 no.2
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• pp.142-148
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• 1983

In order to understand the circulation dynamics of the Keum River estuary, an extensive study was conducted; (i) variability of salinity boundary layer (ii) fluid dynamic characteristics (iii) tides and tidal currents (iv) circulation, diffusion, and dispersion (v) numerical modelling. As first part of this series of work, the salinity data obtained at six sites by using instantaneous profil]ing technique were analyzed in detail. it is found that the amplitude of salinity variation increases toward the upstream direction and its magnitude is greater at neap tide than spring tide. And also duration of salinity boundary layer is much longer during the neap tide than the spring tide, As a result of this study, the Keum River estuary is classified as a typical standing wave type estuary. Finally, we present a schematic diagram for the duration of the salinity boundary layer, which will be useful for further study on flocculation phenomena and sedimentation dynamics.

• Economic and Environmental Geology
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• v.9 no.3
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• pp.143-156
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• 1976

The Cretaceous metal ore deposits in the Gyeongsang basin of Gyeongsangbuk-do are characterized by the formation of metallogenic provinces which show zonal distribution pattern around Yeonil province where pneumatolytic type is dominated and hydrothermal type are distributed in the order of decreasing temperature type outward. Some Cretaceous granitic rocks include zoned alkali feldspars which reflect rapid variation of $H_2O$ during emplacement and crystallization of the water-saturated granitic magma. The ore deposits are considered to be originated from upward transportation of ore solution from the excess of water exhausted from uprising magma, which seems to be intimately related to the fact that the majority of the ore deposits in Daegu area are cummulated around the granites including zoned alkali feldspars. In order to collect geochemical data necessary for geochemical exploration in the study area, certain trace elements were chosen as pathfinders from monzonite and soil in the vicinity of Dalsung Tungsten Mine by studying the dispersion patterns of trace elements: Ba and Sr show trends to decrease toward ore deposit while Cu, Pb, and Mo increase. Around mining area there are distributed apparently Equisetum arvense Linne and Mentha sachinensis Kudo which may be used as index plants. In the viewpoint of geologic structure, the trends of the ore veins in contact aureole around the Palgongsan granite body correspond with the pre- and syn- plutonism joint pattern in hornfels in the area.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.593-604
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• 2020

This study analyzes human development convergence and the impact of funds transfer to the regions using σ and β-convergence analysis method. Observations were made in all Indonesia's provinces in the period 2010-2019. The coefficient of variation calculation shows a dispersion in the inequality of human development, which means that convergence occurred. This is also documented by the clustering analysis results developed in the study. The results are in line with the hypothesis of neoclassical theory, which shows the tendency for provinces with lower human development levels to grow relatively faster. The dynamic panel data approach with the GMM model shows that a model built with explanatory variables for transfer of funds to regions may lead to the process of convergence of human development - 2.21% per year or 31 years to cover the half-life of convergence. This is a consequence of the Special Allocation Fund and the Village Fund, which positively impact the convergence process, and the General Allocation Fund and the Revenue Sharing Fund with negative signs slowing the convergence process. This evidence opens opportunities to review the justification of the weighting component in determining the amount of funds transferred to the region to accelerate the convergence process of human development.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.16
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• pp.6889-6894
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• 2015

Gastric cancer (GC) is the fifth most common cancer in the world, with a wide variation in incidence rates across different geographical areas. In Iran GC is the most common cancer in males and it is reported to be the third most prevalent after breast and colorectal in females. A geographical information system (GIS) allows investigation of the geographical distribution of diseases. The purpose of the present study was to explore the relationship between gastric cancer and effective climatic factors using GIS. The dispersion distribution and the relationship between environmental factors effective on cancer were measured using Arc GIS. Of all cases, 672 (73.8%) were in males with a sex ratio of 3 to1. The highest incidence by cities was seen in Namin with 137.5 per 100,000. The results of this study showed that the distribution of GC around the Sabalan volcanic mountain was significantly higher than other places in the same province. These results can be considered as a window to future comprehensive research on gastric cancer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.23-28
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• 1999

Au fine particles dispersed $TiO_{2}$ film was prepared on silica glass substrate by sol-gel dipping and firing process. The $TiO_{2}$ films were fabricated from the system of titanium tetraisopropoxide-EtOH-HCl-$H_{2}O$-hydrogen tetrachloroaurat (III) tetrahydrate. The conditions for the formation of clear solution and dissolving high concentration of Au compound were examined. Photoreduction process was adopted to control the size of gold metal particles. Phase evolution of matrix $TiO_{2}$ and variation of Au particle with UV irradiation were investigated by XRD, SEM, TEM and UV-visible spectrophotometer. The effect of CPCl (Cetylpyridinium chloride monohydrate) as a dispersion agent was evaluated.