• Journal of Aquaculture
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• v.11 no.1
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• pp.49-58
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• 1998

The spawning behavior and early life history of the Korean aucha perch, Coreoperca herzi were studied. The eggs were spawned in a one-layer mass, hanging from the underside of a largy stone and guarded by one male. According to the considerable size difference os eggs in the individual ovaries, it was concluded that they spawns several times within a spawning season of May~June. The ripe eggs were demersal and adhesive, and their diameter were 2.60~3.04mm with several oil globule of 0.10~0.64mm. Hatching in the tank with $19.0{\pm}1.0^{\circ}C.$ in men water temperature started from the 380 hours after fertilization. Newly-hatched larvae were measured 6.45~7.34mm in total length (TL, mean : 6.85mm), and mouth and anus were open. Melanophores were present on the head, around the yolk, and on the dorsal part of the abdominal region. 3 days old larvae were measured 7.00~7.40mm in TL (mean : 7.25mm), and they fed Daphnia sp. and Brachionus plicatilis actively. 6 days old larvae transformed to postlarval stage and they were 7.94~10.10mm in TL (mean : 9.00mm). As yolk sac were nearly absorbed, the caudal notochord flex at 45. Aggregate numbers of all fin rays were completed at over 16.90~19.80mm in TL (30 days after hatching), at which time the larvae reached the juvenile stage. In fifty days old larvae(24.60~27.10mm in TL) were similar in body form, lateral line and color to adult.

• Polymer(Korea)
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• v.31 no.3
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• pp.189-193
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• 2007

We developed the doxorubicin-loaded PLGA double-layered microspheres using relatively simple oil-in-water (O/W) solvent evaporation method for sustained release of doxorubicin and investigated the release behavior according to PLGA molecular weight and initial drug loading. The double-layered microsphere was characterized on the surface, the cross-section morphology, the behavior of doxorubicin release for 5 weeks by SEM and fluorescence spectrophotometer. Double-layered microspheres showed smooth surfaces and clear difference between core and outer-shell. As the PLGA molecular weight increased, the release rate of doxorubicin-loaded, double-layered microspheres decreased. These results showed that the release behaviors can be controlled by the variation of molecular weight of PLGA.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.3
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• pp.289-303
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• 2007

This report includes basic data on nutrition education for Chinese adolescents living in Korea. A total of 183 Chinese adolescents living in Incheon participated in the survey. Body composition was analyzed by the Inbody 4.0., and questionnaires on personal dietary behavior were administrated. When compared with the body measure indices of Korean adolescents, we found that height was similar, but weight greater ($5{\sim}12 kg$) among the participants. Regarding obesity, 30.0% of all students were obese (BMI>25), especially the high school boys (42.0%). But in the case of middle school boys, the rates of obesity and under weight (BMI<18.5) were the same (both of them at 22.9%). The average WHR (Waist Hip Ratio) of the female high school group (0.9) was over the normal range. The average percent body fat for each group was also over the normal range. The percentage of students having breakfast everyday was 52.2%, and the rate of skipping breakfast was 25.0%. In the obesity group, the rate of skipping breakfast was remarkably high (P<0.05). Because lunch service was not available at the schools, a lunch box from home was the most popular pattern (43.1 %), but eating out was also popular at 36.6%. For the male high school students, the eating out rate was 62.8%. Since many have-lived in Korea for a few generations, the students' eating practices were much closer to the Korean pattern. For their ordinary meal pattern, 96.0% of the students included Korean foods. however, for New Years Day, the rate of having Gyo-Ja was 75.2%, and having Wol-Byung at Choo-seok was 78.6%, showing that the Chinese tradition still remains. In the case of food preferences, the percentage having Kimchi everyday was 62.1 %, but those drinking green tea was 13.1 %. For cold drinks, the rate for drinking them more than twice per week was 71.6%. The most preferred cooking method was frying with oil (50.6%). Among the students who had visited China (or Taiwan), the rate for 'bad food familiarity' was 37.0%, and the rate for 'did not know Chinese traditional course menus' was 71.3%. As a result of combining eating practices from both China and Korea, and the absence of lunch service in Chinese schools, students are showing bad dietary behaviors. therefore, it is necessary to provide proper nutrition education and a system for lunch service in Chinese schools.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.114-120
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• 1998

The spawning behavior, development of eggs and larvae of the Korea freshwater goby, Rhinogobius brunneus (Temminck et Schlegel) were studied. The eggs were spawned as a one-layer mass, hanging from the underside of a small pebble, and guarded by one male. The eggs were elliptic, about 1.48 mm in length and 0.65 mm in breadth, with a round top and a somewhat flat base with glutinous fibers. Hatching in the indoor tank with $17.0^{\circ}C$ in mean water temperature started from the 146 hours after fertilization. In the late developing stages, the embryo moved and freely changed its head to face the free tip of the chorion (normal egg) or to the basal end with a boundle of adhesive filaments (agrippa egg). Newly-hatched larvae were $3.10\~3.30$ mm in total length (mean: 3.22 mm), and mouth and anus were not yet open. Melanophores were present on the air- bladder, around the anus, and on the ventral part of the caudal region. The larva $3\~4$ days old transformed to postlarval stage, and they were $3.30\~3.85$ mm in total length (mean: 3.60 mm). As yolk sac and oil globules werw nearly absorbed, mouth and anus were open, and they fed rotifers actively. In $20\~22$ days after hatching the larvae grew to 5.85 mm in 71, and the caudal notochord flex at $45^{\circ}$.

• Elastomers and Composites
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• v.55 no.4
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• pp.306-313
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• 2020

To investigate the reinforcing effects of functional fillers in nitrile rubber (NBR) materials, high-structure carbon black (HS45), coated calcium carbonate (C-CaCO3), silica (200MP), and multi-walled carbon nanotubes (MWCNTs) were used as functional filler, and carbon black (SRF) as a common filler were used for oil-resistant rubber. The curing and mechanical properties of HS45-, 200MP-, and MWCNT-filled NBR compounds were improved compared to those of the SRF-filled NBR compound. The reinforcing effect also increased with a decrease in the particle size of the fillers. The C-CaCO3-filled NBR compound exhibited no reinforcing effect with increasing filler concentration because of their large primary particle size (2 ㎛). The reinforcing behavior based on 100% modulus of the functional filler based NBR compounds was compared by using several predictive equation models. The reinforcing behavior of the C-CaCO3-filled NBR compound was in accordance with the Smallwood-Einstein equation whereas the 200MP- and MWCNT-filled NBR compounds fitted well with the modified Guth-Gold (m-Guth-Gold) equation. The SRF- and HS45-filled NBR compounds exhibited reinforcing behavior in accordance with the Guth-Gold and m-Guth-Gold equations, respectively, at a low filler content. However, the values of reinforcement parameter (100Mf/100Mu) of the SRF- and HS45-filled NBR compounds were higher than those determined by the predictive equation model at a high filler content. Because the chains of SRF composed of spherical filler particles are similarly changed to rod-like filler particles embedded in a rubber matrix and the reinforcement parameter rapidly increased with a high content of HS45, the higher-structured filler. The reinforcing effectiveness of the functional fillers was numerically evaluated on the basis of the effectiveness index (��SRF/��f) determined by the ratio of the volume fraction of the functional filler (��f) to that of the SRF filler (��SRF) at three unit of reinforcing parameter (100Mf/100Mu). On the basis of their effectiveness index, MWCNT-, 200MP-, and HS45-filled compounds showed higher reinforcing effectiveness of 420%, 70%, and 20% than that of SRF-filled compound, respectively whereas C-CaCO3-filled compound exhibited lower reinforcing effectiveness of -50% than that of SRF-filled compound.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.4
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• pp.423-430
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• 2022

Pressure-dependent elastic behavior and chemical reaction of natural sepiolite (Mg₈Si₁₂O₃₀(OH)₄·12H₂O) was studied under two different pressure-transmitting medium (PTM) conditions using synchrotron X-ray powder diffraction. Under non pore-penetrating silicone oil PTM, we observed that the b-axis length increases up to ca. 3.6 GPa, marking an anisotropic compression region with negative linear compressibility of β^b= -0.0012 GPa^-1, which then decreases at 7.7 GPa. Under pore-penetrating water PTM, the anisotropic compression behavior is enhanced with doubled negative linear compressibility of β^b= -0.0025 GPa^-1 up to 3.2 GPa, where transformation into stevensite is observed upon ex-situ temperature treatment at 280 ℃ as confirmed via XRD and SEM. Derived bulk moduli (K₀) and linear compressibilities (β) were compared to other structurally and chemically related minerals.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.122-127
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• 2024

Cosmetic preservatives are an important class of ingredients in terms of ensuring sustainable use and providing customer satisfaction. Recently, a great deal of interest has been drawn to the production and use of toxic-free, naturally derived preservatives. In this work, a new naturally derived preservative (laurimino bispropanediol, LB) was developed to replace the most widely used diol preservatives, such as 1,2-hexanediol or 1,2-octanediol. The basic properties of the obtained preservative were measured, and the solution behavior of the preservative in an aqueous medium was examined. The feasibility of micelle formation in the preservative solution was investigated using the fluorescence (FL) based pyrene method. Micelle formation was feasible owing to the relatively long hydrophobic chains and increased hydroxyl groups in the preservative molecules. The emulsification capability of the preservative was assessed using the Rosano and Kimura method, showing that the preservative possessed emulsifying capability in an organic solvent (benzene) and soy bean oil. In addition, the dispersion stability of cosmetic formulations, including the new LB preservatives such as essence and lotion, was demonstrated by comparing the light transmittance of the formulations. This article provides important information for future research regarding the synthesis and practical applications of new toxic-free naturally derived preservatives.

• Fire Science and Engineering
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• v.34 no.2
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• pp.86-93
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• 2020

This study aims to maintain the safety of an outdoor storage tank through the fundamental case analysis of explosion and fire accidents in the storage tank. We consider an accident caused by the explosion of fire inside the tank, as a result of the gradual spreading of the residual fire generated by wind lamps flying off a workplace in the storage tank yard. To determine the cause of the accident, atmospheric diffusion conditions were derived through CCTV image analysis, and the wind direction was analyzed using computational fluid dynamics. Additionally, the amount of oil vapor inside the tank when the floating roof was at the lowest position, and the behavior of the vapor inside the tank when the floating roof was at the highest position were investigated. If the cause of the explosion in the storage tank is identified and the level of the storage tank is maintained below the internal floating roof, dangerous liquid fills the storage tank, and the vapor in the space may stagnate on the internal floating roof. We intend to improve the operation procedure such that the level of the storage tank is not under the Pontoon support, as well as provide measures to prevent flames from entering the storage tank by installing a flame arrester in the open vent of the tank.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.4
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• pp.294-303
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• 2008

Squid jigging fishery is very important in that there are about 1,000 jigging vessels more than 10 tonnage and about 5,000 ones less than 10 tonnage in Korea. But the cost of oil which is used to light fishing lamps, goes significantly up to almost one hundred million won for 50 tonnage vessels and forty million won in case of vessels less than 10 tonnage. This cost has almost taken 40% of total fishing costs. That is, the fishing business condition of squid jigging fishery is recently in the very difficult situation. As oil price increases, the business condition of the fishery gets worse and worse. Therefore it is very urgent to develop an economical fishing lamp, to solve this problem of fishery's business difficulty. This research aims at developing a fishing lamp for squid jigging fishery using the light emitting diode which has very excellent efficiency and durability. We made a water tank with 20 meters width which is a shape of raceway to research behavioral characteristics of Japanese flying squid to LED light, and made an experiment to investigate optimum wave of LED light to lure squid. The method is to establish LED lamps on both ends of water tank and to observe squid's behavior. Colors and wave lengths of LED lamps, used in experiment, are red(634nm), yellow(596nm), green(523nm), blue(454nm) and white(454nm+560nm). In experiment for attractive capability of LED lamp to squids, Japanese flying squid are highly attracted to blue lamp and white lamp. However, they are dispersed to red and yellow lamps. In addition, Japanese flying squid have moved and stayed in both dark ends of water tank. When compared intermittent lamp with continuous lamp, Japanese flying squid are highly attracted to intermittent lamp when intermittent interval is 0.25 second.

• Environmental and Resource Economics Review
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• v.16 no.4
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• pp.833-854
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• 2007

Output prices tend to respond faster to input price increases than to decreases. The 'rockets and feathers' hypothesis of asymmetric price behavior in petroleum market is tested by a full adjustment error correction model. Using monthly data for the period January 1977 to June 2006, evidence is found that there is a significant degree of asymmetry in the adjustment of wholesale prices to increases and to decreases in crude oil price. A similar hypothesis in regard to the exchange rate is also rejected by the data. Using weekly data over the period examined, evidence of asymmetry for gasoline, diesel and heating oil is also found in the transmission of price changes from wholesale to retail: retail prices increase more quickly in response to the wholesale price increases than to wholesale price decreases.