• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.2
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• pp.63-70
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• 2014

Design sensitivity analysis and topology design optimization for a piezoelectric crystal resonator are developed. The piezoelectric crystal resonator is deformed mechanically when subjected to electric charge on the electrodes, or vice versa. The Mindlin plate theory with higher-order interpolations along thickness direction is employed for analyzing the thickness-shear vibrations of the crystal resonator. Thin electrode plates are masked on the top and bottom layers of the crystal plate in order to enforce to vibrate it or detect electric signals. Although the electrode is very thin, its weight and shape could change the performance of the resonators. Thus, the design variables are the bulk material densities corresponding to the mass of masking electrode plates. An optimization problem is formulated to find the optimal topology of electrodes, maximizing the thickness-shear contribution of strain energy at the desired motion and restricting the allowable volume and area of masking plates. The necessary design gradients for the thickness-shear frequency(eigenvalue) and the corresponding mode shape(eigenvector) are computed very efficiently and accurately using the analytical design sensitivity analysis method using the eigenvector expansion concept. Through some demonstrative numerical examples, the design sensitivity analysis method is verified to be very efficient and accurate by comparing with the finite difference method. It is also observed that the optimal electrode design yields an improved mode shape and thickness-shear energy.

• Journal of Bio-Environment Control
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• v.18 no.1
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• pp.51-59
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• 2009

Bulb onion cultivation area has been restricted in southern part of Korea to avoid blotting and bulb division. The traditional culture method is transplanting bare-rooted plantlet into the field at the end of summer and harvesting at the beginning of next summer. The hot weather and weak plantlets occasionally causes unstable supply of onions in autumn. In order to enlarge cultivation area and to reduce culture period, long nursery system using plug tray and spring transplanting was tried. Forty cultivars collected from Korea and Japan were nursed using 200-plug tray and transplanted to the field in spring. Marketable yield was not related to the seedling size but lodging time. Cultivar of 'Hamasodachi' was lodged early and resulted low marketable yield. Cultivar of 'Cheonjudaego' was not lodged and yielded high but not in accordance with storability. Generally early lodged cultivars showed low storability. In order to avoid rainy harvesting season, cultivars requires excessive long time for lodging is not recommended for spring culture. Using plug nursery and spring transplanting, we successfully produced marketable onions in 3 months. But immediate using of the harvested onion is recommended. The storability of produced onions showed different result among cultivars, storage of spring onion was not recommended.

• Food Science and Preservation
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• v.12 no.4
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• pp.361-366
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• 2005

An electronic nose equipped with metal oxide sensor(MOS) was used for investigating the quality of reconstitute orange juice added different recoverable oil(cold pressed valencia oil) contents during 21 days of storage at $4^{\circ}C$. Quality changes in orange juice was described in terms of the sensitivity(${\Delta}R_{gas}/R_{air}$) of the sensors. Principal component analysis(PCA) was carried out using data obtained from twelve metal oxide sensors. The flavor of orange juice contained with the different recoverable oil contents($0.01\%{\sim}0.05\%$) was separated in PCA plot, in which the first principal component score was correlated with the content of recoverable oil. As storage periods prolonged, no significantly different sensitivity score of orange juice was observed in electronic nose. The content of recoverable oil in orange juice was reduced rapidly within 14 days, and then the decreasing ratio was slow on the next 7 days during storage at $4^{\circ}C$. The sensory score for overall and orange flavor of orange juice added $0.03\%$ recoverable oil was decreased during the 14 days and then rapidly dropped next 7 days of storage at $4^{\circ}C$.

• Journal of Animal Science and Technology
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• v.64 no.1
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• pp.166-182
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• 2022

Deer antler velvet is widely used in traditional medicine for its anti-aging, antioxidant, and immunity-enhancing effects. However, few studies have reported on the discovery of probiotic strains for deer antler fermentation to increase functional ingredient absorption. This study evaluated the ability of probiotic lactic acid bacteria to enhance the concentrations of bioactive molecules (e.g., sialic acid and gamma-aminobutyric acid [GABA]) in extracts of deer antler velvet. Seventeen strains of Lactobacillus spp. that were isolated from kimchi and infant feces, including L. sakei, L. rhamnosus, L. brevis, and L. plantarum, and those that improved the life span of Caenorhabditis elegans were selected for evaluation. Of the 17 strains, 2 (L. rhamnosus LFR20-004 and L. sakei LFR20-007) were selected based on data showing that these strains increased both the sialic acid and GABA contents of deer antler extract after fermentation for 2 d and significantly improved the life span of C. elegans. Co-fermentation with both strains further increased the concentrations of sialic acid, GABA, and metabolites such as short-chain fatty acids and amino acids. We evaluated the biological effects of the fermented antler velvet (FAV) on the antibacterial immune response in C. elegans by assessing worm survival after pathogen infection. The survival of the C. elegans conditioned with FAV for 24h was significantly higher compared with that of the control worm group fed only normal feed (non-pathogenic E. coli OP50) exposed to E. coli O157:H7, Salmonella typhi, and Listeria monocytogenes. To evaluate the protective effects of FAV on immune response, cyclophosphamide (Cy), an immune-suppressing agent was treated to in vitro and in vivo. We found that FAV significantly restored viability of mice splenocytes and immune promoting-related cytokines (interleukin [IL]-6, IL-10, inducible nitric oxide synthase [iNOS], interferon [IFN]-γ, and tumor necrosis factor [TNF]-α) were activated compared to non-fermented deer antlers. This finding indicated the protective effect of FAV against Cy-induced cell death and immunosuppressed mice. Taken together, our study suggests that immune-promoting antler velvet can be produced through fermentation using L. rhamnosus LFR20-004 and L. sakei LFR20-007.

• Therapeutic Science for Rehabilitation
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• v.12 no.2
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• pp.25-42
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• 2023

Objective : The purpose of this study was to identify the characteristics of a single-subject research study and qualitative levels in which occupational therapy interventions were performed on children with cerebral palsy. Methods : This study targeted papers, published in Research Information Sharing Service (RISS), National Digital Science Library (NDSL), Koreanstudies Information Service System (KISS), and E-article from May 20 to 29, 2022. The search terms were 'cerebral palsy' AND 'single subject research design' OR 'individual subject study'. Eleven papers, were finally selected and analyzed. Results : Most of the studies were medium in methodological quality, and the subjects were pre-school age and spastic hemiplegia. Among the single-subject designs, intervention-removal designs were the most common, and among them, ABA designs were the most common. Interventions included assistive devices, constraint-induced therapy, neurodevelopmental therapy, and sensory integration therapy were 2, and upper extremity exercise, interactive metronome, and CO-OP were 1. Dependent variables were measured with 2 to 4 measurement tools, Significant improvements were found in postural control ability, gait and balance, hand function, and upper extremity function. Conclusion : This study confirmed that it is helpful to apply cerebral palsy occupational therapy by presenting the characteristics of cerebral palsy, intervention sessions and effects, measurement tools and methodological quality levels.

• Journal of Aquaculture
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• v.21 no.4
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• pp.244-251
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• 2008

We evaluated the optimum dietary lipid level and feeding rates of extruded pellets (EP) in juvenile flounder Paralichthys olivaceus during the summer season. The first experiment was conducted to determine the optimum dietary lipid level in juvenile flounder. Five isonitrogenous EP (52% crude protein) with increasing dietary lipids (6, 8, 10, 12 and 14%) were fed to satiety to triplicate groups of the juveniles ($18.4{\pm}0.11g$) twice a day for 6 weeks. Weight gain (WG) of fish fed EP with 10% lipid was significantly higher than those of fish fed EP with 6 and 14% lipid (P<0.05). Broken line model analysis suggested that the optimum dietary lipid level could be $9.08{\pm}0.37%$ for the maximum WG in juvenile flounder. The second experiment was conducted to determine the optimum feeding rate using experimental diet contained 10% lipid level that had the highest WG in first experiment. The feed intake of triplicate groups of the juveniles ($13.4{\pm}0.15g$) was restricted to four different feeding rates of 2.0, 2.5, 3.0 and 3.5% of their body weight $day^{-1}$ and to satiation using experimental diets. WG and feed efficiency (FE) of fish was affected by feeding rates. WG and specific growth rate of fish fed the diets increased with increasing feeding rate, however no significant differences (P>0.05) in WG and specific growth rate were observed between the fish fed 3.5% of their body weight $day^{-1}$ and to satiation. FE of fish fed 3.5% of their body weight $day^{-1}$ was significantly higher than those offish fed 2.0% of their body weight $day^{-1}$ and to satiation (P<0.05). Broken line model analysis suggested that the optimum dietary feeding rate could be $3.56{\pm}0.06%$ for the maximum WG in juvenile flounder. These results indicated that the optimum lipid level and feeding rate could be $9{\sim}10%$ (Energy: 4,774kcal and PIE ratio: 108mg protein/kcal in diet) and 3.5% of their body weight $day^{-1}$in juvenile flounder, respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.188-196
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• 2023

Among marine accidents caused by bad weather, visibility restrictions caused by sea fog occurrence cause accidents such as ship strand and ship bottom damage, and at the same time involve casualties caused by accidents, which continue to occur every year. In addition, low visibility at sea is emerging as a social problem such as causing considerable inconvenience to islanders in using transportation as passenger ships are collectively delayed and controlled even if there are local differences between regions. Moreover, such measures are becoming more problematic as they cannot objectively quantify them due to regional deviations or different criteria for judging observations from person to person. Currently, the VTS of each port controls the operation of the ship if the visibility distance is less than 1km, and in this case, there is a limit to the evaluation of objective data collection to the extent that the visibility of sea fog depends on the visibility meter or visual observation. The government is building a marine weather signal sign and sea fog observation networks for sea fog detection and prediction as part of solving these obstacles to marine traffic safety, but the system for observing locally occurring sea fog is in a very insufficient practical situation. Accordingly, this paper examines domestic and foreign policy trends to solve social problems caused by low visibility at sea and provides basic data on the need for government support to ensure maritime traffic safety due to sea fog by factually investigating and analyzing social problems. Also, this aims to establish a more stable maritime traffic operation system by blocking marine safety risks that may ultimately arise from sea fog in advance.