• Korean Journal of Ichthyology
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• v.34 no.3
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• pp.179-185
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• 2022

The feeding habits of Largehead hairtail Trichiurus japonicus was studied using 377 specimens collected in the Yellow Sea of Korea. The specimens ranged from 4.5 to 33.7 cm in Anal length (AL). T. japonicus consumed mainly a piscivore, such as Engraulis japonicus [percent index of relative importance (%IRI) =74.1%]. We calculated the trophic level as 3.84 for T. japonicus. Fishes were the main prey items for all seasons. The main fish prey during autumn and winter was E. japonicus, whereas those during spring and summer was Larimichthys polyactis. Fishes were the main prey items for all size groups (<15 cm, 15~20 cm, 20~25 cm, ≥25 cm). T. japonicus also showed size-related dietary shift from Spratelloides gracilis and E. japonicus to L. polyactis and T. japonicus. As the anal length of T. japonicus increased, the mean number of preys per stomach (mN/ST) and the mean weight of preys per stomach (mW/ST) tended to increased (One-way ANOVA, P<0.05). Seasonal and size-related shifts in dietary composition were investigated by PERMANOVA analysis, which showed significant variations among size classes and seasons.

• Korean Journal of Food Science and Technology
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• v.2 no.1
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• pp.96-103
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• 1970

No foods are available commercially for weanling infants except a limited amount of expensive milk products in Korea. Although the majority of infants are breast-fed, when it is not possible, rice products must usually be substituted which is not sufficient in protein. Therefore, it is urgent to develop low-cost quality protein food mixtures. In order to accomplish this purpose three food mixtures (F-S-2, F-F-3 and F-P-4), consisting of rice (37∼46%), soybean (24∼40%), FPC (3∼7%), vitamins, minerals and other food additives, are developed. The food mixtures are white to light yellow in color; dispersed readily in water with water absorption index 320; viable bacterial population, less than $10^4$ per gram; sedimentation value, 63; Bostwick consistency value, 15cm/30%; and ring test value, 23cm/30%. The products contain 22∼25% protein and ensure reasonably balanced essential amino acids for the requirement of infants compared with FAO provisional pattern, Rao's maximum growth requirements and Holt's amino acid requirements in early life. Although threonine is limiting, protein score of F-P-4 formula is 93 based on the modified FAO provisional pattern (1965). Furthermore, a 100g of the products supplies required amounts of vitamins and minerals by the recommended daily dietary allowances for infants.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.1
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• pp.1-6
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• 1991

A field experiment was conducted to find out the effects of nitrogen and potassium rates on the chemical constituents and physical properties of burley tobacco (1988； Burley 21. 1989； Burley 21 and KB 101) during successive two years. KB 101 was low in total nitrogen and total alkaloid contents and potassium/total nitrogen ratio of cured leaf. but high in the lightness, red and yellow color and filling power, comparing to Burley 21. The increasing rates of total nitrogen and total alkaloid contents were larger when nitrogen applied to 22.75kg/10a, but they were smaller when nitrogen applied above 22.75 kg/l0a. The potassium content, potassium/total nitrogen ratio, filling power and shatter resistance index of cured leaf were decreased by nitrogen fertilizer addition. The potassium content and shatter resistance index were increased by potassium fertilizer addition. The effect of nitrogen rate on the potassium/total nitrogen ratio of cured leaf was larger than the effect of potassium rate. When the nitrogen fertilizer being applied above 22.75 kg/l0a, there were no advantageous effects on the chemical and physical properties. It is considered to be sufficient that the potassium application is about 35.0 kg/l0a.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.2025-2036
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• 2000

A physicochemical process called ultra rapid coagulation(URC) was applied as a pilot scale to recover eutrophicated lake water at Inkyung Lake located on-campus in Inha university. The URC was uniquely designed to completely remove the presence of phosphorus up to 95%, which in turn leading to lessen the level of eutrophication of lake. For a pilot test of period, the lake was restored showing Carlson's Trophic State Index(TSI) of mesotrophic state which accounts for the reduction of total phosphorus and chlorophyll-a down to approximately 55 from 70 and 73, respectively. A residual presence of aluminum and additional coagulants in the effluent was tested for their potential effects on Photobacterium phosphoreum. The effect concentration ($EC_{50}$-15 min) observed in the effluent revealed that the bioactivity of Photobacterium phosphoreum was not influenced by the residual presence of coagulants. After the pilot test of period, the lake was consequently restored as a mesotrophic state in obtaining the second grade of lake water quality. The URC may be further applied for restoration of greater scale of lake in eutrophication.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.882-888
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• 1998

This study was designed as a part of efforts to investigate the biochemical pollutant markers for diagnosis of marine pollutions by changes in lipid components of the flounder (Paralichthys olivaceus) in the South Sea of Korea, Hemoglobin levels in serum of cultured flounders in the South Sea were lower ($4\~17\%$) than those of wild flounder in Pohang as a control group. Triglyceride (TG), Total and low density lipoprotein (LDL)-cholesterol contents in serum of cultured flounders in the South Sea were $12\~25\%,\;9\~19\%$ and $17\~25\%$ respectively which are higher than those of wild flounder in Pohang. Atherogenic index (AI) and T-Chol/PL ratios in serum of cultured flounders in the South Sea were significantly higher($26\~43\%$ and $17\~26\%$ respectively) than those of wild flounder in Pohang. These results suggest that near-coastal water as well as neritic water of the South Sea might be affected by pollutant input as well as the Yellow Sea of Korea.

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.175-185
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• 2012

To clarify reproductive ecology of the melania snail Semisulcospira coreana (v. Martens, 1886) in Bukhan River, gonad development, fatness, gonad index, sex ratio, first sexual maturity of population, monthly change of larvae number and developmental stages in brood pouches were investigated by six identification methods. As maturation progrsses, the sex of the snali can be distinguishable easily by color:: the ovary being blue-green and testis light yellow. The sex ratio of female to male individuals over 13.95 mm shell height was significantly different from 1:1 (${\chi}^2$ = 38.45, p < 0.05). The sex ratio of female to male individuals changed drastically according to the season, Based on the monthly variations of fatness, gonad index and histological analysis, spawning occurred twice a year (spring and autumn) and the mean size of matured eggs was $450{\mu}m$ in diameter. The monthly change of larval number in brood pouch showed also two distinct peaks in March and September during the year. The average number of larvae in brood pouches was 286 - 862 individuals. In this study, the number of larvae in the brood pouches were a minimum in December and a maximum in March (975 larvae). The biological minimum size (the size at 50% of group sexual maturity) of the melania snail was 13.95 mm in shell height in females and males. All females over 15 mm in shell height possesed brood pouches.

• Korean Journal of Agricultural Science
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• v.29 no.1
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• pp.44-54
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• 2002

The fresh eggs of African ostrich in Korea were used in this study to investigate their interior and exterior quality characteristics. In ostrich egg shape characteristics, long and short length were measured as 15.1~16.1 cm and 12.1~13.6 cm, respectively. The egg shape index was calculated as 81.0 and the egg shell showed a more g loss white in color than that of hen egg. Calculated breaking strength of egg shell and egg shell surface based on the equation were $41.155kg/cm^3$ and $804.7cm^2$, respectively. Average egg shell thickness including egg shell membrane was 1.89 mm and there are no differences among parts of the shell. The egg shell membrane thickness was 0.10 mm showing relatively thick in equator compared with that of blunt end. The ave rage number of egg shell pores was counted as $19.7/cm^2$ showing relatively high number of egg shell pores at point end and the total number of egg shell pores in an egg was estimated as 15,241. The relative port ion of each parts based on egg weight was estimated as 25.1% for egg yolk, 58.2% for egg white, 16.7% for egg shell and the ratio of egg yolk to egg white (Y/W) was 0.43. The average diameter and the ave rage height of ostrich egg white were 19.7 cm and 13.2 mm, respectively. Calculated the H.U (Haugh Unit) was -69.7 and the pH was 8.3. In ostrich egg yolk, the diameter, the height, the egg yolk index, and it's pH were calculated as 14.4 cm, 29.4 mm, 0.20, and 6.6, respectively. And the egg yolk color showed a more thin in yellow chroma compared with that of hen egg as due to it's thicker membrane.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.243-274
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• 2013

To investigate the research state and characteristics of dinoflagellate cyst along the Korean coastal waters, this work analyzed 45 studies conducted in the Korean coasts and basin, the south of Jeju, East China Sea including some part of the Yellow Sea. It was found that the research on dinoflagellate cyst began in the later half of the 1980s in Korea, and that the research areas focused on eutrophied regions where a red tide occurred or on the seas where coastal development occurred. In other words, no research on the East Sea was found. In terms of research contents, there were various studies on analysis of cyst assemblage, tracking of the changes in marine environment like process of eutrophication, roles as a seed population in occurrence of a red tide, creation of cyst by use of sediment trip and tracking of its changes, morphological changes by the change of pH concentration in the hypoxia zone of eutrophied region, germination of a specific species, and other international-level studies. Species composition and cell density also varied in the Korean coastal waters. However, much research on dinoflagellate cyst in Korea is not systematic, and is fragmentary and individual and hencesuffers from great limitations. The research results so far have focused only on specific regions, and sporadic research had been conducted by specific research groups. Dinoflagellate cyst of surface sediments represents the accumulation index of pelagic environment in the sea and is a useful index to understand the marine environment efficiently. In conclusion, Korea requires organized human resources and collaborative research on dinoflagellate cyst which in turn should be considered as a component of marine ecosystem and as an essential aspect of marine biology.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.1 s.119
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• pp.38-47
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• 2007

This study was carried out to develop a new application field and obtain the basic data of citrus peel as waste in Jeju island and traditional Hanji for producing functional Hanji. The results measuring physical and optical properties, water vapor permeance and antibacterial activity are as follows. It was revealed that apparent density go as down but bulk raise up in the structural view of Hanji with increasing of the addition various Korean citrus peel (citrus unshiu, cheonggyun and hanrabong peel, and citrus unshiu peel powder) percentages, and that the density of Hanji added citrus unshiu peel was higher, but bulk was lower in compared with Hanji added other kinds of peel. Those Hanji added citrus unshiu peel, cheonggyun peel, hanrabong peel and citrus unshiu powder were very great not only in the strength (breaking length, burst index, tear index and folding endurance) but also in water vapor permeant rate in comparison with Hanji. The pHs of Hanji were neutrality (7 to 8). The brightness of the Hanji added various citrus peel percentages was low in compared to Hanji, and the 40% addition of hanrabong peel was the lowest. When 40% hanrabong peel was added to Hanji, it was very yellow in the color degree. When cheonggyun peel was added to Hanji manufacture, water vapor permeant rate was highly effective. It is known that vacant space of intrafiber was reduced by image analysis of Hanji and the additions of peel of citrus unshiu, cheonggyun and hanrabong were distributed equally in the interior of Hanji. The antibacterial activity of Hanji added citrus unshiu peel is more than 98%. After all, it would be able to increase utilization of Hanji, extensively. Namely, production of high quality Hanji added functional materials is expected for new valuable industry of citrus peel and Hanji.

• Korean Journal of Optics and Photonics
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• v.32 no.4
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• pp.163-171
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• 2021

Conventional white light-emitting diodes (LEDs) for lighting applications consist of blue LEDs and yellow phosphors, the spectrum of which lacks deep red. To improve the color-rendering characteristics of white LEDs, a red quantum-dot film was applied to the diffuser plate of LED lighting. The mean free paths of the quantum dots and the concentration of the TiO₂ particles in the diffuser plate were adjusted to optimize the optical structure of the lighting. The color-rendering index (CRI) was greater than 90 for most conditions, which demonstrates that adoption of the red quantum-dot film is an effective way for improving the color-rendering properties of conventional white LEDs. The angular dispersion of color coordinates could be removed by utilizing the optical cavity formed between the diffuser plate and the reflector on the bottom of the lighting, where multiple passages of the light through the quantum-dot film reduced the differences in optical path length depending on the viewing angle.