• Fisheries and Aquatic Sciences
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• v.26 no.1
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• pp.48-57
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• 2023

One of the ways to increase the production for aquaculture is through the cultivation of monosexuals by ensuring genital reversal from which energy for reproduction is diverted towards growth. Masculinization has been identified as one of the most prominent techniques, where sex development was directed from female to male. This approach only altered the phenotype and not the genotype. The red claw crayfish (Cherax quadricarinatus) was a relatively new commercial commodity, and the males were known to grow faster than females. Hence, it was proposed to use monocultures comprising an all-male population to increase yield using steroid hormone, synthetic 17α-methyltestosterone. However, this technique generated residues that detrimentally affect human health, the environment, and cultivated organisms. Therefore, finding new safe natural steroid sources was essential, and one of which is exploring of natural hormones extracted from the viscera of sea cucumbers (Holothuria scabra Jaeger). This study focused on the determination of male formation and testosterone levels among juvenile crayfish, after immersing in sea cucumber steroid extract (SCSE). A completely random design with factorial was used with two variables, encompassing the varied doses (0, 2, 4 mg/L, 2 mg/L 17α-methyl testosterone as control group) and immersion times of 18 and 30 h. The result showed the dose-dependent ability of SCSE increase the male genital formation and promote the testosterone level of juvenile crayfish. In addition, the testosterone was influenced by dose and immersion duration time, with the highest level of testosterone observed in treatments of 4 mg/L SCSE with 30 h immersion was 0.248 ng/mL, while the male percentage was 77%. In conclusion, the combination of dose and immersion time significantly affected growth and testosterone levels.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.3
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• pp.347-351
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• 2023

Flying fish Cypselurus agoo roe is a popular food ingredient due to its abundant nutrition, unique texture, and flavor. It contains high levels of polyunsaturated fatty acids, protein, and minerals such as calcium, phosphorus, potassium, and vitamins (A, B₁, B₂, B₆, and niacin), making it a highly utilized food ingredient. Additionally, it is widely used as a raw material for food and cooking in several countries. After harvesting, flying fish roe is dried and transported to processing plants, where it performed a re-moisturizing process. However, the conventional re-moisturizing process is time-consuming and results in some loss of quality. Thus, this study investigates the conditions required for the re-moisturization of flying fish roe including the composition of the immersion solution, immersion time, and conditions that could minimize damage to the roe. The results suggest a reasonable composition of immersion solution to minimize damage to flying fish roe and the most appropriate immersion time for re-moisturization. These results may provide valuable insights for the industry to enhance the quality of re-moisturized flying fish roe, leading to an increase in its market value and demand.

• The Korean Journal of Community Living Science
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• v.21 no.4
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• pp.633-639
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• 2010

This study was carried out to compare human thermoregulatory responses and preferred air temperature by feet immersion between summer and winter in terms of thermal comfort. Five healthy female university students participated in the study as subjects. They experienced feet immersion at $40^{\circ}C$ of water in the climatic chamber of $24^{\circ}C$, 50%RH from 19:30 to 21:00 in the summer and winter, respectively. Rectal temperature gradually decreased and maintained $0.08^{\circ}C$ lower in winter than summer, while mean skin temperature changed $0.4^{\circ}C$ greater in winter than summer(p=0.00). Air temperature selected by each subject for their thermal comfort revealed $0.8^{\circ}C$ higher in summer than winter(p=0.06). The results obtained suggest an increase in human thermoregulation and be used as preliminary data to maintain optimal indoor temperature in summer and winter.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.4
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• pp.191-198
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• 2022

Stress refers to various body reactions that occur when humans are stimulated by environmental conditions. The quality of education and flight skills can suffer if flight trainees are constantly subjected to high stress, even in the case of flight trainees, and as a result, it can harm becoming a pilot. It is therefore the aim of this study to identify stress factors (flight training, career, financial support, relationships with family and teachers) that student pilots face, to determine how these factors affect flight and academic immersion and abandonment, and to improve the quality of flight education.

• Korean Journal of Materials Research
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• v.23 no.1
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• pp.24-30
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• 2013

Today, the modification of carbon foam for high performance remains a major issue in the environment and energy industries. One promising way to solve this problem is the optimization of the pore structure for desired properties as well as for efficient performance. In this study, using a sol-gel process followed by carbonization in an inert atmosphere, hollow spherical carbon foam was prepared using resorcinol and formaldehyde precursors catalyzed by 4-aminobenzoic acid; the effect of carbonization temperature and re-immersion treatment on the pore structure and characteristics of the hollow spherical carbon foam was investigated. As the carbonization temperature increased, the porosity and average pore diameter were found to decrease but the compression strength and electrical conductivity dramatically increased in the temperature range of this study ($700^{\circ}C$ to $850^{\circ}C$). The significant differences of X-ray diffraction patterns obtained from the carbon foams carbonized under different temperatures implied that the degree of crystallinity greatly affects the characteristics of the carbon form. Also, the number of re-impregnations of carbon form in the resorcinol-formaldehyde resin was varied from 1 to 10 times, followed by re-carbonization at $800^{\circ}C$ for 2 hours under argon gas flow. As the number of re-immersion treatments increased, the porosity decreased while the compression strength improved by about four times when re-impregnation was repeated 10 times. These results imply the possibility of customizing the characteristics of carbon foam by controlling the carbonization and re-immersion conditions.

• Journal of the Korean institute of surface engineering
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• v.54 no.5
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• pp.238-247
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• 2021

PEO (plasma electrolytic oxidation) was applied to modify the surface of AZ31 magnesium alloy in this study. The mixed solution of sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) was used as the electrolyte, and 0 - 0.05 g/L of Ca-GP (Glycerol Phosphate Calcium salt) was added in the electrolyte as an additive. PEO treatment was conducted at a current density of 30mA/cm² for 5 minutes using a DC power supply. The surface properties were identified by SEM, XRD and surface roughness analyses, and the corrosion resistance was evaluated by potentiodynamic polarization and immersion tests. In addition, the biocompatibility was evaluated by immersion test in SBF solution. As the concentration of Ca-GP was increased, the surface morphology was denser and more uniform, and the amount of Ca and the thickness of oxide layer increased. Only Mg peak was observed in XRD analysis due to very thin oxide layer. The corrosion resistance of PEO-treated samples increased with the concentration of Ca-GP in comparision with the untreated sample. In particular, the highest corrosion resistance was identified at the group of 0.04g Ca-GP through potentiodynamic polarization and immersion tests in saline solution (0.9 wt.%NaCl). During the immersion in saline solution, pH rapidly increased at the beginning of immersion period due to rapid corrosion, and then increase rate of pH decreased. However, the pH value in the SBF temporarily increased from 7.4 to 8.5 during the day, then decreased due to the inhibition of corrosion with HA(hydroxyapatite) formation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.406-416
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• 2019

This study aims to examine whether a parental neglect affects an adolescent's peer attachment and adult media immersion has a mediating effect. To achieve this goal, the first year of middle school panel of 'the 6th(2015) Korean Children and Youth Panel Survey(KCYPS)' was utilized. Using SPSS PROCESS Macro developed by Hayes, 'Bootstrapping' was employed to examine the significancy of the mediating effect on 563 objectives. According to the study, first of all, more parental neglect gave rise to less peer attachment. Second, the adult media immersion partly mediates the parental neglect and the adolescent's peer attachment. The practical implications of this results are below : First, parents' care and affection inside a home is necessary to formulate the healthy peer attachment of adolescent. Second, a parent education is important to prevent an adolescent's adult media immersion. Third, an adult media education for an adolescent is desired.

• Journal of the Korea Society of Computer and Information
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• v.27 no.1
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• pp.107-113
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• 2022

In this paper, we propose the relationship between the expectation of home training, exercise commitment, and exercise continuation intention. The subject of this study is the police officers belonging to the Busan and Gyeongnam Provincial Police Agency as of March 2021. Among them, a survey was conducted targeting 337 people who had experience participating in home training. As a result of the study, first, it was found that the expectations of home training were significantly correlated with exercise immersion and exercise continuation intention factors. Second, it was found that the expectation of home training participants had a significant effect on exercise immersion and exercise continuation intention. Third, exercise immersion of home training participants was found to have a significant effect on exercise continuation intention. Home training will be usefully used to prepare physical conditions for various public safety situations. If you training with a long-term plan rather than short-term training, you will be able to achieve the effect that home training seeks.

• Composites Research
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• v.21 no.3
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• pp.1-8
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• 2008

The main objective of this study is to investigate the effect of salt water on the mechanical properties of a carbon-epoxy composite material. Specimens were made of a carbon-epoxy composite USN125 and tested under inplane tension and shear after 0, 0.5, 1, 2, 3, 6, 9, and 12 months immersion in 3.5% salt water. Waterproof painting and acceleration technique were not applied. The tensile strengths and moduli in fiber and matrix directions did not show any remarkable degradation until 12 months immersion. In contrast to the tensile properties, shear strength and modulus started to degrade from the early stage of the immersion time and gradually decreased to 36% and 46% of dry values, respectively, after 12 months immersion.

• Smart Media Journal
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• v.12 no.11
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• pp.86-94
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• 2023

In recent years, advertisements and brand promotions using virtual influencer have been actively conducted, and this study focused on the characteristics of virtual influencer, including Attractiveness, to examine the Attractiveness of virtual influencer through previous studies and to test the hypothesis that Attractiveness has an effect on Brand attitude and Advertising attitude when mediated by Immersion. For this purpose, data were collected from university students who experienced marketing contents using virtual influencer, and Process macro was conducted to analyse the mediating effect. The results showed that virtual influencer Attractiveness partially mediated the relationship between Brand attitude and Advertising attitude. These results suggest that virtual influencer Attractiveness not only affects Brand attitude and Advertising attitude, but also positively increases consumer attitude when mediated by Immersion. This study has both academic and practical implications by examining the mediating effect of Immersion on the effect of virtual influencer Attractiveness on consumer attitudes.