• Ocean Science Journal
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• v.42 no.2
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• pp.69-79
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• 2007

A vertical transect with 4 km length was established for the macrofaunal survey on the Chokchon macrotidal flat in Kyeonggi Bay, Incheon, Korea, 1994. Tidal elevation (m) and sediment mean grain size $(\phi)$ were inversely predicted by the transfer functions from the faunal assemblages. Three methods: weighted average using optimum value (WA), tolerance weighted version of the weighted average (WAT) and maximum likelihood calibration (MLC) were employed. Estimates of tidal elevation and mean grain size obtained by using the three different methods showed positively corresponding trends with the observations. The estimates of MLC were found to have the minimum value of sum of squares due to errors (SSE). When applied to the previous data $(1990\sim1992)$, each of three inference models exhibited high predictive power. This result implied there are visible relationships between species composition and faunas' critical environmental factors. Although a potential significance of the two major abiotic factors was re-affirmed, a weak tendency of biological interaction was detected from faunal distribution patterns across the flat. In comparison to the spatial and temporal patterns of the estimates, it was suggested that sediment characteristics were the primary factors regulating the distribution of macrofaunal assemblages, rather than tidal elevation, and the species composition may be sensitively determined by minute changes in substratum properties on a tidal flat.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.110-115
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• 1998

Through the ISODATA method, the micro-landform of Julpo-Bay tidal flat was classified into mudflat, mixedflat, and sandflat using Landsat TM image. Each showed an apparent differences in its topographical characteristics and grain size composition. For example, mudflats are formed with flat faces and tidal channel of dissected gully. Its characteristics of grain size analysis that the grains have less than mean grain size 4 phi. Its sorting is bad (higher than 1 S.D.), and it showed strongly positive skewness. But sandflat is topographically flat without tidal channel. It has developed with ripple marks. According to the grain size analysis of deposits, the soil is coarse size with 90% of sand and its sorting is well(lower than 1 S.D.) Also, it showed strongly negative skewness. Mixed flat is in between mudflat and sandflat in its characteristics.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.6
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• pp.694-703
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• 2012

To understand the characteristics of sedimentary and benthic environments in habitats of naturally-occurring intertidal benthic macroalgae, various geochemical parameters of sediment (grain size, ignition loss [IL], chemical oxygen demand [COD], and acid volatile sulfur [AVS]) and pore water (temperature, salinity, pH, and nutrients) were measured in the southern intertidal zone of Hampyeong Bay at two month intervals from April to October 2009. Ecological characteristics including the distribution and biomass of benthic macroalgae were also investigated. Benthic macroalgae were distributed below 4 to 5 m depth from mean sea level near the lower portion of the intertidal zone where air exposure time is relatively short. The distribution area and biomass of benthic macroalgae gradually decreased during the study period. The surface sediments in the benthic algal region were mainly composed of finer sediments, such as slightly gravelly mud and mud. The temperature, salinity, pH, and nutrient concentrations (except dissolved inorganic nitrogen) in pore water did not differ in regions with and without benthic macroalgae, whereas the mean grain size and the concentrations of IL, COD, and AVS in sediments were much higher in regions harboring benthic macroalgae. The correlation between mean grain size and IL in sediments displayed two distinct gradients and the slope was much steeper in regions harboring benthic macroalgae, indicating that the content of organic matter in benthic algal region is not solely dependent on mean grain size. Our results indicate that the benthic macroalgae in the southern intertidal zone of Hampyeong Bay play an important role in the accumulation of organic matter in sediment.

• The Journal of the Acoustical Society of Korea
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• v.18 no.8
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• pp.84-93
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• 1999

Determination of grain size of heat-treated stainless steel based fm digital ultrasonic signal processing technique is presented. This techniques consist in evidence accumulation with multiple feature parameters, difference absolute mean value(DAMV), variance(VAR), mean frequency (MEANF), auto regressive model coefficient(ARC) and linear cepstrum coefficient(LCC). Feature parameters were extracted from ultrasonic echo signal of heat-treated metals. It was found that a few parameters might not be sufficient to exactly evaluate the grain size of heat-treated metals. The determination of grain size of heat-treated metals was carried out through the evidence accumulation procedure using the distances measured with reference parameters. A fuzzy mapping function is designed to transform the distances for the application of the evidence accumulation method. In the work presented, heat-treated stainless steel samples with various grain sizes are examined. The processed experimental results supports the feasibility of the grain size determination technique presented.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.3
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• pp.386-392
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• 1996

A numerical method based on genetic algorithms was introduced to characterize the grain-size distribution more effectively. This technique was proved significant particularly for multimodal size distributions, as was verified for samples from Korea Strait continental shelf. Sediment samples collected from the Korea Strait continental shelf revealed that $96\%$ of the grain-size distributions were multimodal. Therefore, the use of grain-size parameters was not the ideal method. As an alternative method, the decomposition of sue curves into elementary normal component curves was used. Means and standard deviations of 593 decomposed normal components were calculated by a numerical method from 268 size curves of Korea Strait sediments. The mean values of decomposed normal components showed peaks at $1\~3\phi\;and\;7\~9\phi$ size classes. The plot of mean and standard deviation values of the coarse fraction normal components on the map showed a characteristic areal distribution. The characteristic distribution was found to derive from underlying Pleistocene sediment on the basis of sea bottom geologic distribution of the area. The method of decomposition into normal components was found to be more effective than the analysis using traditional grain-size parameters in investigation of multimodal size distribution of Korea Strait shelf sediment.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.441-444
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• 2006

Nakdong river estuary is located at south-eastern coast if the Korea. Especially, Complicating topography change is generated by interaction of much sediment, wave and tide. This study is investigated into observation data of grading size distribution in the post and surface sediment characteristics is investigated into grading size analysis using sieve analysis in Nakong river estuary. As a result, mean diameter of surface sediment is distributed to front of shoal as a size with 0.1~0.2 mm and mean diameter of the last generated shoal is about 0.2~0.3 mm.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.225-228
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• 2007

This paper presents a geostatistical methodology to model local uncertainty in spatial estimation of sediment grain size with high-resolution remote sensing imagery. Within a multi-Gaussian framework, the IKONOS imagery is used as local means both to estimate the grain size values and to model local uncertainty at unsample locations. A conditional cumulative distribution function (ccdf) at any locations is defined by mean and variance values which can be estimated by multi-Gaussian kriging with local means. Two ccdf statistics including condition variance and interquartile range are used here as measures of local uncertainty and are compared through a cross validation analysis. In addition to local uncertainty measures, the probabilities of not exceeding or exceeding any grain size value at any locations are retrieved and mapped from the local ccdf models. A case study of Baramarae beach, Korea is carried out to illustrate the potential of geostatistical uncertainty modeling.

• Journal of The Geomorphological Association of Korea
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• v.27 no.4
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• pp.1-11
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• 2020

Coastal dunes play an important role in coastal defense. The Moraeul dune in Daecheongdo Island is representative in this regard. However, there is little knowledge, concerning the morphology, grain size, and formation timing of the dune. This study investigated the geomorphological characteristics of the Moraeul dune using topographic surveys, grain size analyses, and OSL dating. The dune was classified as 'single accreted foredune', which was developed under dense vegetation cover and efficient sand trapping. The dune consisted of fine to medium sand with 1.6Φ of mean grain size, and was covered with pine trees (> 100 years old). The samples from the upper part of the dune yielded quartz OSL ages ranging 0.5 ~ 0.7 ka. Therefore, it is likely that the dune developed at least before the Little Ice Age and became what it is today about one century ago.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.4
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• pp.304-312
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• 2011

Grain size analysis was conducted for a total of 402 surface sediments collected from 67 sites along three (upper, middle, and lower) transects corresponding to the high-, mid-, and low-intertidal zone of beach on the Sinjado, Nakdong River estuary in Nov. 2005 and May 2006. Sinja-do beach sediments showed uni-modal grain size distributions, in which the mode of $3.0{\phi}$ was dominant in 2005 whereas the mode of $2.5{\phi}$ in 2006. This coarsening trend was more remarkable in the western side of beach as well as in the mid- and low-intertidal zone. In this study, we focused on investigating characteristics of sediment size changes on the basis of transect data that differ in tidal elevation. For this purpose, a statistical test was applied for transect by transect comparison of grain size parameters such as mean, sorting, and skewness. Mean values between middle and lower transect, sorting values between upper and lower transect, and skewness values over the beach reflected statistically significant temporal changes. Also, mean and skewness parameters showed an inverse relationship which was more stronger in 2006 than in 2005. Temporal changes in Sinja-do beach sediments resulted in decrease of mean and sorting values but increase of skewness values, intensifying the inverse relationship between mean and skewness parameters.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.4
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• pp.265-271
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• 2000

The microstructural change and transformation characteristics with cooling rate i.e. wheel speed were investigated in 82.8wt%Cu-12.8wt%Al-4.3wt%Ni SMA ribbons fabricated by melt-spinning. The thickness and width of ribbon were decreased with increasing wheel speed, while the uniformity of it was improved. At same wheel speed, the grain size of the contact surface of ribbon was smaller than that of free surface. The mean grain size was decreased with increasing wheel speed, resulted in obtaining grains with $3{\mu}m$ in mean diameter in the wheel speed of 30 m/s. However, micro-voids and cracks at grain boundary could be observed at higher wheel speed. $M_s$ and $A_s$ temperatures were decreased, and $M_s{\sim}M_f$ and $A_s{\sim}A_f$ temperature ranges were broadened with increasing wheel speed. All the ribbons were retained the ordered $D0_3$ due to rapid cooling, the volume fraction of it was increased with increasing wheel speed.