• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.86-87
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• 2003

Unstructured grid system is suitable for flows of complex geometries. For problems with moving boundary walls, the grid system must be changed and deformed with time if we use a body fitted grid system. In this paper, a new moving-grid finite-volume method on unstructured grid system is proposed and developed for unsteady compressible flows with shock waves. To assure geometric conservation laws on moving grid system, a control volume on the space-time unified domain is adopted for estimating numerical flux. The method is described and applied for two-dimensional flows.

• Conservation and Restoration of Cultural Heritage
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• v.1 no.1
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• pp.39-48
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• 2012

The first twenty-five years of scientific study within Korea on Korean traditional ceramics has been characterized as a bridging effort to understand the rich field of artistic ceramic masterpieces on one hand with analytic results gained from mounds of broken shards and kiln wastes on the other. First shard pieces were collected directly from the waste mounds, but most of the analyzed shards were provided by art historians and museum staffs directly involved in systematic excavations. The scientific study is viewed as one of many complimentary ways in learning about the multi-faceted ceramics culture, ultimately connecting human spirits and endeavors from the past to the present to the future. About 1350 pieces of analyzed shards have been so far collected and organized according to the production location and time period. From the experimental results of the analysis, the compositional and microstructural characteristics of bodies and glazes have been deduced for many kiln sites of Goryeo and Joseon dynasties. Except for a few local kilns, porcelain stone was used as body material in both dynasties. The principle of mixing a clay component with a flux material was used in Korean glazes as was in China. The clay component different from body clay was often used early on. In Gangjin a porcelain material appropriate for whiteware body was mixed for celadon glaze, and in Joseon Gwangju kilns glaze stone was chief clay material. The use of wood ash persisted in Korea even in making buncheong glazes, but in Joseon whitewares burnt lime and eventually crushed lime were used as flux material.

• Journal of Conservation Science
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• v.20
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• pp.105-117
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• 2007

This study is examined the beads excavated in the Sacheon Neukdo ruins to investigate the features of archaeological chemistry and to compare those of the same type of beads excavated within the Gyeongsang-do area by means of scientific analysis. The samples have been observed the micro-structures by an optical microscope and SEM and confirmed the physical property by density measurement. Chemical property have been analyzed main components such as flux, stabilizers, and colorants by SEM-EDS. Besides, XRD was used to identified the characteristic materials of beads. The white opaque beads, which was initially estimated as sea-shell beads, confirm as amorphous silica material. The glass beads, which are blue type as a result of compositional analysis, it is revealed potash glass group and LCA(Low-CaO, $Al_2O_3$) system. gB ones are revealed only in LCA-A(LCA-CaO<$Al_2O_3$), while purple blue ones in LCA-B(LCA-CaO>$Al_2O_3$).

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.321-326
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• 1993

Membrane separation technology with polymeric membranes for the effective separation and energy conservation has emerged to be a new technology for separation in recent years. In this research, the reverse osmosis process was applied to the concentration process of clarified apple juices. The changes of concentration and permeate flux of apple juice in this process were measured at different membrane characteristics, operating pressures, temperature and flow rate. And the changes of quality were also measured at different pressures. The prediction model for the permeate flux based on these data was established. Generally, the osmotic pressure increased as the concentration of the feed increased in the RO process, which caused a reduction of permeate flux. The changes of permeate flux were not much dependent on temperature and flow rate, but very much dependent on pressure. The most effective factor in increased permeate flux was found to be the operating pressure, followed by temperature and flow rate. The final prediction model for the permeate flux was developed by the $SPSS^x$ computer program. The result showed that recovery of sugar was not affected by processing pressures, but the percentage recovery of total flavor was increased with increasing pressure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.9
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• pp.1093-1100
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• 2004

Numerical analysis of the heat transfer associated with droplet impact on a hot solid surface is performed by solving the equations governing conservation of mass, momentum and energy in the liquid and gas phases. The deformed droplet shape is tracked by a level set method which is modified to achieve volume conservation and to include the effect of contact angle at the wall. The numerical method is validated through the calculations for the cases reported in the literature. Based on the numerical results, the heat transfer rate is found to depend strongly on the droplet spread radius. Decreased advancing/receding contact angles enlarge the splat radius and in turn enhance the wall heat flux. The effect of impact velocity on the droplet spread is reduced as the droplet size decreases. Also, droplet atomization is observed to significantly enhance the heat transfer rate and the effect is pronounced for a smaller size of droplet. An existing model equation to predict the maximum spread radius is improved for application to a micro droplet.

• Journal of Conservation Science
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• v.34 no.5
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• pp.345-358
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• 2018

The purpose of this study is to analyze the characteristics of low-grade 12th-century celadons, which were excavated from a kiln site in Noksan-dong, Busan. The physical and chemical properties of the body and the glaze are evaluated through scientific analyses. All the selected celadon shards have a similar body color, regardless of the kiln from which they originated. The celadon shards from 2 3 kilns are brighter than those from 4 5 kilns, and there are two saturations, namely gray and brown. The brightness of the glaze shows a high contribution of red and yellow. The porosity of the selected shards is 8.8% in the gray saturation and 16.1% in the brown saturation. The major chemical compositions of the body and glaze are in the typical chemical composition of the celadon, but the $TiO_2$ flux contents are different. The visible characteristic difference between the 2 3 kilns and the 4 5 kilns can be attributed to the mixing and the firing process rather than the raw materials used. The difference in the $Fe_2O_3$ and $K_2O$ flux between the 2 3 and 4 5 kilns can be attributed to changes in the ingredient combination during the process. In conclusion, Noksan-dong celadon could not be easier vitrification due to the manufacturing process that primary burning process, It is highly likely that there were process differences in kilns to produce high quality celadon.

• Journal of Ecology and Environment
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• v.47 no.4
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• pp.272-281
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• 2023

Ecosystem observatories are burgeoning globally in an endeavour to detect national and global scale trends in the state of biodiversity and ecosystems in an era of rapid environmental change. In this paper we highlight the additional importance of regional scale outcomes of such infrastructure, through an introduction to the Great Western Woodlands TERN (Terrestrial Ecosystem Research Network) SuperSite, and key findings from three gradient plot networks that are part of this infrastructure. The SuperSite was established in 2012 in the 160,000 km² Great Western Woodlands region, in a collaboration involving 12 organisations. This region is globally significant for its largely intact, diverse landscapes, including the world's largest Mediterranean-climate woodlands and highly diverse sandplain shrublands. The dominant woodland eucalypts are fire-sensitive, requiring hundreds of years to regrow after fire. Old-growth woodlands are highly valued by Indigenous and non-Indigenous communities, and managing impacts of climate change and the increasing extent of intense fires are key regional management challenges. Like other TERN SuperSites, the Great Western Woodlands TERN SuperSite includes a core eddy-covariance flux tower measuring exchanges of carbon, water and energy between the vegetation and atmosphere, along with additional environmental and biodiversity monitoring around the tower. The broader SuperSite incorporates three gradient plot networks. Two of these represent aridity gradients, in sandplains and woodlands, informing regional climate adaptation and biodiversity management by characterising biodiversity turnover along spatial climate gradients and acting as sentinels for ecosystem change over time. For example, the sandplains transect has demonstrated extremely high spatial turnover rates in plant species, that challenge traditional approaches to biodiversity conservation. The third gradient plot network represents a 400-year fire-age gradient in Eucalyptus salubris woodlands. It has enabled characterisation of post-fire recovery of vegetation, birds and invertebrates over multi-century timeframes, and provided tools that are directly informing management to reduce stand-replacing fires in eucalypt woodlands. By building regional partnerships and applying globally or nationally consistent methodologies to regional scale questions, ecological observatories have the power not only to detect national and global scale trends in biodiversity and ecosystems, but to directly inform environmental decisions that are critical at regional scales.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.1
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• pp.5-17
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• 2018

The standardized eddy covariance flux data processing in KoFlux has been updated, and its database has been amended accordingly. KoFlux data users have not been informed properly regarding these changes and the likely impacts on their analyses. In this paper, we have documented how the current structure of data processing in KoFlux has been established through the changes and improvements to ensure transparency, reliability and usability of the KoFlux database. Due to increasing diversity and complexity of flux site instrumentation and organization, we have re-implemented the previously ignored or simplified procedures in data processing (e.g., frequency response correction, stationarity test), and added new methods for $CH_4$ flux gap-filling and $CO_2$ flux correction and partitioning. To evaluate the effects of the changes, we processed the data measured at a flat and homogeneous paddy field (i.e., HPK) and a deciduous forest in complex and heterogeneous topography (i.e., GDK), and quantified the differences. Based on the results from our overall assessment, it is confirmed that (1) the frequency response correction (HPK: 11~18% of biases for annually integrated values, GDK: 6~10%) and the stationarity test (HPK: 4~19% of biases for annually integrated values, GDK: 9~23%) are important for quality control and (2) the minimization of the missing data and the choice of the appropriate driver (rather than the choice of the gap-filling method) are important to reduce the uncertainty in gap-filled fluxes. These results suggest the future directions for the data processing technology development to ensure the continuity of the long-term KoFlux database.

• Journal of Environmental Science International
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• v.22 no.2
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• pp.173-185
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• 2013

In order to clarify the impact of wildfire and its thermal forcing on atmospheric wind and temperature patterns, several numerical experiments were carried out using three dimensional atmospheric dynamic model WRF with wildfire parametrization module SFIRE. Since wind can accelerate fire spread speed, the moving speed of fireline is faster than its initial values, and the fireline tends to move the northeast, because of the wind direction and absolute vorticity conservation law associated with driving force induced by terrain. In comparison with non-fire case, the hydraulic jump that often occurs over downwind side of mountain became weak due to huge heat flux originated by surface wildfire and wind pattern over downwind side of mountain tends to vary asymmetrically with time passing. Therefore temporal variation of wind pattern should be catched to prevent the risk of widfire.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.362-367
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• 1997

To assess the coolability of particle bed, which is formed in reactor cavity, it is important to assess the prediction capabilities of Dryout Heat flux correlations. The existing DHF correlations (Sowa et al., Dhir-Catton (a), Dhir-Catton (b), Hardee-Nilson, Ostesen, Shires-Stevens, Lipinski, Jones et al., Dhir-Barleon, Theofanous-Saito, Henry-Fauske) for particle beds are assessed using developed DHF database. Eleven DHF correlations are chosen for assessment based on literature survey. Among them, five are based on flooding correlation, which are used for chemical engineering and others are based on conservation equations. The parameters in DHF correlations are directly substituted into correlations. Totally 202 data are classified into 6 groups based on bed thickness and particle diameter. In each group, prediction capabilities of correlations are assessed and shown by standard deviation and root mean square (RMS) error. Prediction capability of each correlation depends on the data group and none of correlations shows best prediction capability on entire groups. According to present study, even if those correlations show poor prediction capability, Lipinski correlation is best correlation considering entire groups.