• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.1
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• pp.13-20
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• 1991

This paper describes the fish-density dependence of the mean backscattering strength with aggregations of encaged, free-swimming fish of known density in relation to the experimental verification of echo-integration technique for estimating the density of fish shoals. In this experiment, various numbers of gold crussian, Carassius burgeri burgeri, with a mean length of 18.5cm and a mean weight of 205.9g, were introduced into a net cage of approximately 0.76m super(3). During the backscattering measurements. the cage was suspended on the sound axis of the 50kHz transducer having a beam width of 33 degrees at -3dB downpoints. The volume backscattering strengths from fish aggregations were measured as a function of fish density. Data acquisition, processing and analysis were performed by means of the microcomputer-based sonar-echo processor including a FFT analyzer. The calibration of echo-sounder system was carried out at field with a steel ball bearing of 38mm in diameter having the target strength of -40.8dB. The dorsal-aspect target strengths on anesthetized specimens of gold crussian used in the cage experiment were measured and compared with the target strength predicted by the fish density-echo energy relationship for aggregations of free-swimming gold crussian in the cage. The results obtained can be summarized as follows: 1. The target strengths in the dorsal aspect on anesthetized specimens of gold crussian, with the mean length of 19.1cm and the mean weight of 210.5g, varied from -40.9dB to -44.8dB with a mean of -42.6dB. This mean target strength did not differ significantly from that predicted by the regression of echo energy on fish density of free-swimming gold crussian in the cage. It suggests that the target-strength measurements on anesthetized fish was valid and can be representative for live, free-swimming fish. 2. The relationship between mean backscattering strength(, dB) and distribution density of gold $crussian(\rho, $ fish/m super(3)) was expressed by the following equation; =-41.9+11 $Log(\rho)$ with a correlation coefficient of 0.97. This result support the existence of a linear relationship between fish density and echo energy, but suggest that this line has steeper slope than the regression by the theory of estimating the density of fish schools.

• Korean Journal of Community Nutrition
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• v.9 no.2
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• pp.173-182
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• 2004

We carried out a validation-calibration study of the food frequency questionnaire (FFQ) that we had previously developed for a community-based cohort of the Korean Genome and Health Study of the Korea National Genome Research Institute. We have collected a total of 254 3-day diet records (DRs) from 400 subjects, 200 each randomly selected from the two study cohorts of Ansung and Ansan. FFQ was administered at the time of cohort recruitment in 2001, and DRs were collected during a two month period from January through February of 2002. The mean age was 52.2 years. Farming for men and housewife for women were the most common occupations. The majority of the subjects had undergone 6∼12 years of education. The general characteristics including demographic and other data were not different from the total cohort subjects. Absolute levels of consumed nutrients including total energy (energy), protein, fat, carbohydrate, calcium, phosphorus, sodium, potassium, iron, retinol, carotene, vitamin A, thiamin, riboflavin, niacin and vitamin C were compared. The average of energy intake was not significantly different between the data collected by the 2 methods. However, consumptions of protein and fat were higher in data of DRs, whereas that of carbohydrate was higher in FFQ data. Significant correlation of each nutrient consumption between the data sets was observed (p ＜ 0.05) except in the case of iron, while the average correlation coefficient between them was 0.22 ranging from 0.33 for energy to 0.11 for iron. The results of cross classification by quantile for exact classification ranged from 25.2% (carotene) to 35.0% (phosphorus), and from 64.6% (vitamin A) to 76.4% (retinol) for adjacent classification. The proportion of completely opposite classification was 8.1% in average. Calibration slope was estimated by regression and calibration parameters ranged from 0.025 for carotene to 0.423 for niacin. We conclude that the FFQ we have developed is an appropriate tool for assessing the nutrient intakes as ranking exposures in epidemiology studies in view that amounts of consumed nutrients obtained by FFQ were similar to those collected by DRs, that correlations between consumed nutrients collected by these methods were significant, and that classification results were relatively fair. The correlation coefficients, however, were lower than expected, which may be mainly due to the survey season. In fact, any short-term dietary survey cannot accurately reflect the overall dietary intakes that change heavily depending on seasons. Further studies including the analysis of chemical indices would be helpful for the studies of causal relationship between the diet and disease.

• Korean Journal of Environment and Ecology
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• v.27 no.1
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• pp.99-112
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• 2013

This study aims to show the changes of characteristics of vegetation structure for 20 years(1991~2010) in Naejangsan National Park. As a result of analysis of actual vegetation, the mixed community of Quercus variabilis and Quercus serrata was distributed with 56.1%, and Q. variabilis community showed in southern steep slope with 17.6%. Pinus densiflora community(5.8%) was observed on the ridge and Carpinu tschonoskii community distributed in the slope of the valley with 6.6%. Zelkova serrata and Prunus sargentii community were distributed in valley. The classification by TWINSPAN, ordination by DCA considering importance percentage and property of vegetation class were divided into 4 communities, which are community I(P. densiflora-Q. variabilis community), community II(Q. variabilis community), community III(C. tschonoskii community) and community IV(Mixed deciduous broad-leaved trees community). The age of Pinus densiflora was 32years old and Q. serrata was 36 years old in the community I, that of Q. variabilis was 64 years old in the community II, Q. serrata was 46 years old and C. tschonoskii was 45 years old in the community III, and Acer palmatum was 54 years old and Cornus controversa was 47 years old in the community IV. As the result of Shannon's index of species diversity, the community Iwas ranged from 0.9751 to 1.4199, community II was ranged from 1.0765 to 1.3278, community III was ranged from 1.0353 to 1.2881, and community IV was ranged from 1.1412 to 1.3807. The change of vegetation structure analyzed through the comparison with results of studies carried out 20 years ago were natural selection of P. densiflora, expansion of Quercus spp. and increase of C. tschonoskii. Especially, A. palmatum is dominated by Q. variabilis in canopy layer like the result of study 20 years ago. A. palmatum was analysed by 14.6% in the canopy layer of only mixed deciduous broad-leaved trees community. As a result of analysis of habitat property of Q. variabilis and A. palmatum, Q. variabilis was distributed in dry area with the low value of pH, O.M., exchangeable cations and Avail. P, and A. palmatum was located in the wet valley with huge value of nourishment. The tendency of reduction of bio-diversity by Sasa borealis is same as previous study but, the distributed areas were reduced in Naejangsan area.

• Journal of the Korean Electrochemical Society
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• v.23 no.4
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• pp.105-112
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• 2020

Transition metal oxide, which undergoes a conversion reaction in the negative electrode material for a lithium-ion batteries, has a high specific capacity, but still has several critical problems. In this study, manganese pyrophosphate (Mn₂P₂O₇), nickel pyrophosphate (Ni₂P₂O₇), and carbon composite materials with pyrophosphates as novel negative electrode materials instead of transition metal oxide, are synthesized through simple solid-state reaction. The initial reversible capacity of Mn₂P₂O₇ and Ni₂P₂O₇ are 333 and 340 mAh g^-1, and when the composite materials are composed with carbon, the reversible capacity increases to 433 and 387 mAh g^-1, respectively. The initial Coulombic efficiency is also improved by about 10%. The Mn₂P₂O₇ and carbon composite material has the highest initial capacity and efficiency, and has the best cycle performance. Mn₂P₂O₇ containing polyanion, has a lower specific capacity due to the large mass of polyanion compared to MnO (manganese oxide). However, since Mn₂P₂O₇ shows a voltage curve with a slope, the charging (lithiation) voltage increases from 0.51 to 0.57 V (vs. Li/Li⁺), and the discharge (delithiation) voltage decreases from 1.15 to 1.01 V (vs. Li/Li⁺). Therefore, the voltage efficiency of the cell is improved because the voltage difference between charging and discharging is greatly reduced from 0.64 to 0.44 V, and the operating voltage of the full cell increases because the negative electrode potential is lowered during the discharging process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5578-5586
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• 2012

The accurate estimation of discharge is very essential as the important factor of river design for the utilization and flood control, hydraulic construction design. The present discharge production is using the stage-discharge relationship curve in the river. The rating curve uses the method by predicting the discharge based on regression analysis using the measured stage and discharge data in a flood season. The method is comparatively convenient and has especially advantages in that it can predict the discharge having the difficulty of observation in a flood season. However, this method has basically room for improvement because the method only uses the relationship between stage and discharge, and doesn't reflect the hydraulic parameters such as hydraulic radius, energy slope, roughness, topography, etc.. Therefore, in this study, discharge was predicted using the convenient calculation method with empirical parameters of the Manning and Chezy equations, which were proposed by Choo et at (2011) in KSCE as a new methodology for estimating discharge in open channel. The proposed method can conveniently estimate empirical parameters in both of Manning and Chezy equations and the discharge is estimated in the open channels. There are proved by using data measured in meandering lab. channel and India canal and the accuracies show about determination coefficient 0.8. Accordingly, this method will be used in actual field if this study is continuously conducted.

• Journal of the Korean earth science society
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• v.36 no.3
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• pp.222-235
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• 2015

Samples were collected from both places including the coastal area within the height of 5 m above the mean sea level (msl) (DH) and the top of the coastal terrace of 10-15 m msl (KS) high in Gwangseungri, Gochanggun, Korea. To find the origin of the deposit in the coastal area, granulometric analysis and geochemical analysis were performed. The result showed that the DH samples were originated from the reddish soils overlaying weathered bedrock which presented gradual change of chemical composition from the bottom toward the top. Clay minerals were found from the DH samples. These results concluded that the DH samples were found as in-situ weathered materials. The KS samples were originated from the soil layer covering gravel layer at the foot slope of the hill along the coast. The KS samples contained different chemical compositions from the DH. It is inferred that some of this layer was disturbed or experienced the influx of foreign material. The particle size of the KS samples was different from those found on the beach. The particle size of lower parts of KS site was finer than that on the beach, but the particle size of middle part of the site was coarser than that on the beach. The sorting of the KS site was poorer than that on the beach. Thus, it is inferred that some parts of the layer were formed by short-lived high energy event rather than sustained and continuous action of tidal currents and/or waves. Analysis using an optically stimulated luminescence (OSL) method showed that the burial age of samples from KS site were found 0.65-0.71 ka. Though the characteristics of the sediment layer and forming event in this area should be further studied, it can be inferred that this sedimentary layer formed by coastal flooding with storm.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.232-235
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• 1992

Effect of temperature and initial pH were studied on the pH change of MSG solution during heating. The heating temperature and initial pH of 2% MSG solution were in the range of $100{\sim}120^{\circ}C$ and $pH\;2{\sim}9$, respectively. The results showed that the pH of MSG solution was more rapidly decreased as the temperature increased and the initial pH decreased due to pyroglutamic acid formation from MSG thermal degradation. A linear relationship was obtained between pH decreased and logarithmic value of heating time and the decreasing rate constant of pH were calculated from the slope. The pH decreased$({\Delta}pH)$ after 3 hrs of heating was 1.2 at the initial pH 4 and $120^{\circ}C$ and 0.33 at pH 5 and $120^{\circ}C$ while little pH change measured at the range of $pH\;6{\sim}9$. Activation energy calculated for pH decrease during heating was 11.77 and 22.26 kcal/mole at pH 4 and pH 5, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.663-666
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• 2005

Gas hydrates are ice-like compounds that form at the low temperature and high pressure conditions common in shallow marine sediments at water depths greater than 300-500 m when concentrations of methane and other hydrocarbon gases exceed saturation. Estimates of the total mass of methane carbon that resides in this reservoir vary widely. While there is general agreement that gas hydrate is a significant component of the global near-surface carbon budget, there is considerable controversy about whether it has the potential to be a major source of fossil fuel in the future and whether periods of global climate change in the past can be attributed to destabilization of this reservoir. Also essentially unknown is the interaction between gas hydrate and the subsurface biosphere. ODP Leg 204 was designed to address these questions by determining the distribution, amount and rate of formation of gas hydrate within an accretionary ridge and adjacent basin and the sources of gas for forming hydrate. Additional objectives included identification of geologic proxies for past gas hydrate occurrence and calibration of remote sensing techniques to quantify the in situ amount of gas hydrate that can be used to improve estimates where no boreholes exist. Leg 204 also provided an opportunity to test several new techniques for sampling, preserving and measuring gas hydrates. During ODP Leg 204, nine sites were drilled and cored on southern Hydrate Ridge, a topographic high in the accretionary complex of the Cascadia subduction zone, located approximately 80km west of Newport, Oregon. Previous studies of southern Hydrate Ridge had documented the presence of seafloor gas vents, outcrops of massive gas hydrate, and a pinnacle' of authigenic carbonate near the summit. Deep-towed sidescan data show an approximately $300\times500m$ area of relatively high acoustic backscatter that indicates the extent of seafloor venting. Elsewhere on southern Hydrate Ridge, the seafloor is covered with low reflectivity sediment, but the presence of a regional bottom-simulating seismic reflection (BSR) suggests that gas hydrate is widespread. The sites that were drilled and cored during ODP Leg 204 can be grouped into three end-member environments basedon the seismic data. Sites 1244 through 1247 characterize the flanks of southern Hydrate Ridge. Sites 1248-1250 characterize the summit in the region of active seafloor venting. Sites 1251 and 1252 characterize the slope basin east of Hydrate Ridge, which is a region of rapid sedimentation, in contrast to the erosional environment of Hydrate Ridge. Site 1252 was located on the flank of a secondary anticline and is the only site where no BSR is observed.

• Geophysics and Geophysical Exploration
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• v.14 no.1
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• pp.42-49
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• 2011

To locate anomalous features including seepage pathways through the Daeryong earth-fill dam, P and Rayleigh waves were recorded along a 250-m profile on the crest of the dam. Seismic energy was generated using a 5-kg sledgehammer and detected by 24 4.5-Hz vertical-axis geophones installed at 3-m intervals. P-wave and apparent S-wave velocities of the reservoir dam and underlying bedrock were then inverted from first-arrival traveltimes and dispersion curves of Rayleigh waves, respectively. Apparent dynamic Poisson's ratios as high as 0.46 were obtained at the base of the dam near its north-east end, where an outlet conduit occurs, and in the clay core body near the south-west end of the profile where the dam was repeatedly grouted to abate seepage before our survey. These anomalies of higher Poisson's ratios in the upper part of clay core were also associated with effusion of grout on the downstream slope of the dam during post-survey grouting to abate leakage. Combining P-wave traveltime tomography and inversion of Rayleigh wave velocities was very effective in detecting potential pathways for seepage and previous grouted zones in this earthen dam.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.2
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• pp.95-102
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• 2002

Spatial interpolation has become a common procedure in converting temperature forecasts and observations at irregular points for use in regional scale ecosystem modeling and the model based decision support systems for resource management. Neglection of terrain effects in most spatial interpolations for short term temperatures may cause erroneous results in mountainous regions, where the observation network hardly covers full features of the complicated terrain. A spatial interpolation model for daytime hourly temperature was formulated based on error analysis of unsampled site with respect to the site topography. The model has a solar irradiance correction scheme in addition to the common backbone of the lapse rate - corrected inverse distance weighting. The solar irradiance scheme calculates the direct, diffuse and reflected components of shortwave radiation over any surfaces based on the sun-slope geometry and compares the sum with that over a reference surface. The deviation from the reference radiation is used to calculate the temperature correction term by an empirical conversion formula between the solar energy and the air temperature on any sloped surfaces at an hourly time scale, which can be prepared seasonally for each land cover type. When this model was applied to a 14 km by 22 km mountainous region at a 10 m horizontal resolution, the estimated hourly temperature surfaces showed a better agreement with the observed distribution than those by a conventional method.