• 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.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.2
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• pp.85-91
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• 1988

A field experiment was conduted to determine the effects of shading degrees (O: full sunlight, 25, 50 and 75%) on the proximate components, cell wall constituents (CWC), digestibility, water soluble carbohydrates (WSC) and nitrate nitrogen ($NO_3$-N) concentration of grasses grown in forest. For the test different artificial shading houses were established and pasutre species used were orchardgrass, timothy, perennial ryegrass and ladino clover. the experiment was performed at LES in Suwon, 1985 1. Considering proximate components, CWC and digestibility of grasses, ladino clover showed the best quality, and then perennial ryegrass. 2. The contents of crude protein, crude ash, and digestibility of grasses were increased with shadking, regardless of pasture species. As the shading degrees are increased, the contents of crude fibe in orchardgrass, perennial ryegrass and timothy were decreased, while that in ladino clover was increased with shading. 3. Grasses grwon in spring showed higher digestibility than those grwon in summer season. 4. The content of WSC was the highest in perennial ryegrass, and then ladino clover, orchardgrass, and timothy, in that order. Also WSC was decreased as the shading degrees are in creased. 5. The content of $NO_3$-N was the highest in perennial ryegrass, and then orchardgrass, ladino clover and timothy, in that order. Also the $NO_3$-N was significantly increased with higher shading level. In the regression equation between shading degrees and $NO_3$-N ($r^2=0.90^{**},\;r^2=0.95^{**}$), shading degree of 43 to 44% was critical level, causing nitrate poisoning to animal. 6. Considering grass quality, dry matter yield and $NO_3$-N, less than 40% of shading degree (over 60% of full sunlight) was desirable for better grassland improvement, management and utilization in the forest.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.4
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• pp.263-271
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• 2009

This study evaluated the flocs forming characteristics in the mixing zone to increase the coagulation effect in the drinking water plant. As a measuring tool of formed flocs, on-line particle dispersion analyzer (iPDA) was used in Y drinking water plant. To evaluate the forming flocs, many parameters such as poly amine, coagulant dosing amount, raw water turbidity, and pH was applied in this study. During the periods of field test, poly aluminium chloride (PACl) as a coagulant was used. With the increase of the raw water turbidities, poly amine was also added as one of aids for increasing in coagulation efficiency. The turbidity and pH of raw water was ranged from 7 to 9 and from 25 to 140 NTU, respectively. The increasing of raw water turbidity brought the bigger floc sizes accordingly. From a regression analysis, $R^2$ value was 0.8040 as a function of T, raw water turbidity. Floc size index (FSI) was obtained from a correlation equation as follows; FSI = 0.9388logT - 0.3214 Also, polyamine gave the bigger flocs the moment it is added to the coagulated water in the rapid mixing zone. One of parameters influencing the floc sizes was the addition of powdered active carbon(PAC) in the mixing zone. In case of higher turbidity of raw water, $R^2$ value was 0.9050 in the parameters of [PACl] and [PAC]; FSI = $0.0407[T]^{0.324}[PACI]^{0.769}[PAC]^{0.178}$ On-line floc monitor was beneficial to evaluate the flocs sizes depending on the many parameters consisting raw water properties, bring the profitable basic data to control the mixing zone more effectively.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.893-905
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• 2020

This study is a study on solubilization and emulsifying power of tocopheryl acetate using vegetable surfactants. High purity polyglyceryl-10 isostearate and polyglyceryl-10 oleate were mixed to synthesize a vegetable surfactant with excellent solubilizing power and emulsifying power. The mixed raw material was named Solubil EWG-1100. The appearance of this raw material was a pale yellowish paste with a specific smell, specific gravity of 1.12, and acid value of 0.085. The HLB value of this surfactant was calculated by the Griffin's equation with an average value of 15.17. The behavior of this surfactant to solubilize tocopheryl acetate was mechanically verified. The performance of solubilization was evaluated by a method of visual evaluation and was measured by a transmittance rate at 650 nm using a UV spectrophotometer. As a result, in the formulation using 3% ethanol as a co-solvent, the concentration of surfactant was required to solubilize tocopheryl acetate was required about 5 times of natural surfactant. In the formulation without ethanol as a co-solvent, the concentration of surfactant was required to solubilize tocopheryl acetate required about 7 times of natural surfactant. In addition, the concentration of surfactant required to make an emulsifivation 10 % of tocopheryl acetate was 1 wt% of Solubil EWG-1100, and the emulsified particle size was 3.5 mm in cream formula. In order to obtain stable and fine emulsified particles, it was found that as the concentration of tocopheryl acetate increased, the concentration of Solubil EWG-1100 also was to increase. As a result of testing the solubilizing power of the surfactant according to the pH various change, it showed stable solubilizing power in the acidic region of pH=3.2, the neutral region of pH=7.0, and the alkaline region of pH=11.8. As application, based on these results, it is expected that it can be widely applied to the cosmetics field that develops skin care prescriptions, sensitive skin products, and heavy dry skin products.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.1
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• pp.34-43
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• 1996

Determining the actual evapotranspiration(ETa) of a crop, and appropriate water management of the crop based on the ETa are very important For increasing the yield. The present study aimed at determining ETa and crop coefficient of sesame growing under different climatic conditions with the transparent thin polyethylene film mulch(0.03 mm thick) and without this mulch. Bottomless cylindrical lysimeters(105cm in diameter, 120cm in height, protruded 20 cm above the soil surface) were installed on the field of sandy loam "Bonyang series" soil with a moderate drainage. The determination of ETa was performed by measuring each component of a model equation, $ETa=(R+I)-\{Ro+(D1+D2)\}+C{\pm}{\Delta}S$. Sesame, cv. "Ansan" was sown in two rows with the spacing of $50{\times}15cm$ on May 10 in 1991 and 1992. The mulching covers 80% of the soil surface. Sesame consumed the water of 139.0 mm(1.53 mm/day) and 171.2 mm(1.59 mm/day) in ETa without the film mulch, but that of 132.6 mm(1.46 mm/day) and 199.8 mm(1.85 mm/day) with its mulching through both years of 1991 and 1992, respectively. The ETa's accounted for 52 and 69% of the potential evapotranspiration(ETp) in the mulched crop, and 54 and 59% of ETp in the non-mulched crop 1991 through 1992, respectively. Its ETa's were much more and their gap between the mulching and non-mulching treatment was larger in 1992 than in 1991 as a result of the better climatic condition of 1992.

• Journal of The Korean Association For Science Education
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• v.38 no.4
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• pp.495-504
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• 2018

This study was conducted to develop items to measure scientific core competency based on statements of scientific core competencies presented in the 2015 revised national science curriculum and to identify the validity and reliability of the newly developed items. Based on the explanations of scientific reasoning, scientific inquiry ability, scientific problem-solving ability, scientific communication ability, participation/lifelong learning in science presented in the 2015 revised national science curriculum, 25 items were developed by five science education experts. To explore the validity and reliability of the developed items, data were collected from 11,348 students in elementary, middle, and high schools nationwide. The content validity, substantive validity, the internal structure validity, and generalization validity proposed by Messick (1995) were examined by various statistical tests. The results of the MNSQ analysis showed that there were no nonconformity in the 25 items. The confirmatory factor analysis using the structural equation modeling revealed that the five-factor model was a suitable model. The differential item functioning analyses by gender and school level revealed that the nonconformity DIF value was found in only two out of 175 cases. The results of the multivariate analysis of variance by gender and school level showed significant differences of test scores between schools and genders, and the interaction effect was also significant. The assessment items of science core competency based on the 2015 revised national science curriculum are valid from a psychometric point of view and can be used in the science education field.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.3
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• pp.205-209
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• 2018

'Saemimyeon,' a Tongil-type rice variety (Indica x Japonica), containing high amylose content, is suitable for rice noodle production. Currently, the major parts of the rice processing industry that include products such as rice flour and noodles are expected to partially replace the wheat flour market. The volume of the rice noodle market is growing and can contribute to the rice surplus problems and farmer's income. This study was carried out to promote productivity of 'Saemimyeon' by finding the most suitable transplanting times in Youngnam Province. The transplanting times were May $10^{th}$, May $17^{th}$, May $24^{th}$, May $31^{th}$, June $7^{th}$, and June $14^{th}$ and the planting distance was $30{\times}12cm$. The field experiment was conducted in the Miryang region (southern plain region of Korea) from 2015 to 2017. Our results suggested that the optimum transplanting dates were from May $17^{th}$ to May $31^{th}$, which resulted in an average yield of 750 kg/10 a. The average grain filling rate before May $31^{th}$ was more than 83% and it declined to 75% after June $7^{th}$. The average temperature range from heading to harvesting time was $21{\sim}25^{\circ}C$ and the estimated optimal temperature was $24^{\circ}C$, which is similar to that of May $24^{th}$ by regression equation. It is suggested that low temperature at seed maturation time caused the lower grain filling rate, and therefore 'Saemimyeon' needed to be transplanted before May $31^{th}$ for higher productivity. Estimated optimal transplanting time based on temperature was 1 ~ 2 weeks earlier than the optimum transplanting time for common japonica rice cultivars in Youngnam Province.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.199-206
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• 2004

Factors of universal soil loss equation, USLE, and its revised version, RUSLE for Korean soils were reevaluated to estimate the national scale of soil loss based on digital soil maps. Rainfall erosivity factor, R, of 158 locations of cities and counties were spacially interpolated by the inverse distance weight method. Soil erodibility factor, K, of 1321 soil phases of 390 soil series were calculated using the data of soil survey and agri-environmental quality monitoring. Topographic factor, LS, was estimated using soil map of 1:25,000 scale with soil phase and land use type. Cover management factor, C, of major crops and support practice factor, P, were summarized by analyzing the data of lysimeter and field experiments for 27 years (1975-2001) in the National Institute of Agricultural Science and Technology. R factor varied between 2322 and 6408 MJ mm $ha^{-1}$ $yr^{-1}$ $hr^{-1}$ and the average value was 4276 MJ mm $ha^{-1}$ $yr^{-1}$ $hr^{-1}$. The average K value was evaluated as 0.027 MT hr $MJ^{-1}$ $mm^{-1}$. The highest K factor was found in paddy rice fields, 0.034 MT hr $MJ^{-1}$ $mm^{-1}$, and K factors in upland fields, grassland, and forest were 0.026, 0.019, and 0.020 MT hr $MJ^{-1}$ $mm^{-1}$, respectively. C factors of upland crops ranged from 0.06 to 0.45 and that of grassland was 0.003. P factor varied between 0.01 and 0.85.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.1
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• pp.15-23
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• 1979

In the first paper of the series the five soil fertility factors were evaluated by means of principal component analysis and varimax method. They are interpreted as representing, 1) skeletal available phosporus status, 2) organnic matter status, 3) salt status 4) base status, and 5) free oxide status. In order to resynthesize such fragmented information for the overall soil fertility evaluation, the method of multiple regression analysis was adopted, using the five factor scores and yield data for Korean paddy soils as independent and dependent variables respectively. As test of linear models with different combinations of independent variables the results of t-test of regression coefficient were revealed that the organic matter status (FII) has no relevance to the yield of paddy and that the free oxides and salt supply has by it self only an insignificant contribution to the yield. The multiple correlation coefficient (R) revealed its multiple regression analysis was as low as 0.43. Introduction of quadratic terms to the linear model bettered the result. Thus multiple correlation coefficient (R) was increased as 0.59. Therefore, a coefficient of determination 0.35 was obtained by a quadratic model with interaction terms among the five fertility constituents. Generally we think that the fertility factor has more contribution to raise the rice yield in paddy and that the failure of yield prediction by fertility factor scores was caused by one of follows; 1) the roughness of the yield inspection, and 2) missextraction of fertility constituents. The second step in this study, assuming that the residuals by multiple regression analysis were due to factors other than soil fertility, we can now proceed to predicting the yield from the field characters with the classified fertility groups by means of Hayashi's theory of quantification No. 1. Such variables as fertility groups (FTYG), water availability (WATER), soil drainage (DRNG), climatic zone (CLIZ), surface soil's stickiness (STCKT), surface soil's dry consistence (DCNST), and surface soil's texture (FTEXT) are taken up as the explanatory variables. The quantification appears reasonable; the well to extremely well in soil drainage, very sticky of surface soil, inefficiency in water availability, coarse texture, and very hard to extremely hard dry consistence in soil are detrimental to the rice yield. The R was as high as 0.90 for the set of variables. But the given explanatory variables in this study were not quite effective in explaining rice yield. The method developed seems to be promising only if properly collected data are available. Conditions that should be satisfied in the yield inspection obtained from common cultivator for the purpose of deriving a prediction equation were put forward.

• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.411-420
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• 2015

This study examined methods for stand density control by using shape ratio (tree height/DBH) and its application for effective management of Pinus thunbergii coastal disaster prevention forests. We analyzed the present conditions (height, DBH, and density) of P. thunbergii coastal disaster prevention forests at 123 study sites on Jeju Island and west, south, and east coasts of South Korea and compared them with results from previous studies. The average shape ratio for P. thunbergii showed positive correlations with stand density and was significantly higher on the west coast (66.32) than on the south (49.57) and east (48.19) coasts and Jeju Island (48.29). Stands with shape ratio higher than 70 accounted for 50% of the total study sites on the west coast, indicating a decrease in their disaster prevention function compared to that of other previous studies. The stand density in most coastal areas, except the east coast, was significantly higher than the standards recommended by the Korea Forest Service and the Forestry and Forest Products Research Institute of Japan, indicating the need for stand density control. According to the growth estimation equation for P. thunbergii in the coastal area of South Korea, density control is required for young stands less than 14 years old, which show drastic increase in the shape ratio, to conserve their disaster prevention function. Particularly, the first thinning of P. thunbergii forests should be implemented before the stand age of 8 years that a shape ratio exceeds 70. For disaster-prone young stands (${\leq}20cm$ DBH) of P. thunbergii, the stand density was higher in the standard of Japan considering shape ratio than in that of Korea aiming timber production. Hence, the standard guidelines employed in Japan, which assign higher importance to disaster prevention function based on field surveys, can be applied effectively for controlling the stand density of P. thunbergii coastal forests in South Korea, to improve their disaster prevention function.