• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.6
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• pp.563-570
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• 1985

The main purpose of this study is to evaluate a revolving plate-type biofilter system for mass culture of eels (Anguilla japonica) based on the experimental rearing for 199 days. Water quality, growth efficiency of fish and effects of fish disease control were critically evaluated. The experiment was conducted in two different units, each unit consisting of a cement tank containing $20m^3$ of water. In unit A, a biofilter which includes 400 rotating undulated P. V. C. plates being 70 cm in diameter which rotates at 6 rpm and also 400 undulated P. V. C. plates fixed in the settling chamber of an area of $66{\times}62cm$. Water was continuously passed through the filter at a rate of 260 l/min., and supplemental water was added to the fish tank at a rate of $4m^3$ a day. In unit B, the biofilter has 400 P. V. C. plates being $66{\times}62cm$ each was installed in the settling tank. The results gained from the experimental rearing for 199 days from April 21, 1984 to November 5, 1984 are as follows. In the growth experiment, the weight of fish in unit A increased from 3.0 kg to 815.6 kg, while in unit B, from 3.0kg to 416.0kg. During the period of the experiment, in the both units the fish grew at an acceptable rate at the temperature at which they were held. Observing every aspect of eel culture, including growth rate, disease control and water quality, unit A appears to have adventages over unit B, which makes it particuraly attractive in intensive recirculating fish culture system. It was further observed that certain parasites such as Trichodina sp. and Costia sp. could easily be controled by appling 4 ppm of $KMNO_4$.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.199-202
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• 1996

Artificial hearts are intended for use in patients with severe forms of heart disease for which no surgical repair is possible. The moving-actuator pump was developed to decrease the overall volume size of the electromechanical total artificial heart (TAH) by eliminating the occupied space of the fixed-actuator in the conventional pusher-plate type pump. In our pump, the actuator moves back and forth for alternative ejections of left and right ventricles. The problem of fitting the TAH to atrial remnants and arterial vessels could also be improved by circular or penduluous mot ion of the actuator instead of linear mot ion of the pusher-plate in the conventional pumps. We have evaluated two types of moving- actuator pump; one is a rolling cylinder type, and the other a pendulum type pump. In the rolling cylinder pump, frictional energy loss exists between the pump housing's guide bars and the actuator's end caps, while the bottom rack under the cylindrical actuator increases the height of the pump, the pump is therefor not implantable inside the small chest of human-sized animals with a body weight of less than 70kg. The new human type pump has a penduluous mot ion actuator to correct the above problems while maintaining the advantage of the moving- actuator's small total volume. The totally implantable TAH is composed of a blood pump, a control system and pheriperal equipments. The blood pump, which is constructed by a moving actuator, a right and left blood sac, and four artificial valves, is implanted in the thoracic. In 1988, the first implantation of the rolling cylinder TAH was performed into a female calf weighing 100kg, and the cal f recovered to the degree of voluntary standing and eat ing and survived to 100 hrs. We then survived two female sheep weighing about 63kg with the new human type TAH for three days.

• Korean Journal of Materials Research
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• v.21 no.11
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• pp.587-591
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• 2011

The effect of the precipitator (NaOH, $NH_4OH$) and the amount of the precipitator (150, 200, 250, 300 ml) on the formation of $Fe_3(PO_4)_2$, which is the precursor used for cathode material $LiFePO_4$ in Li-ion rechargeable batteries was investigated by the co-precipitation method. A pure precursor of olivine $LiFePO_4$ was successfully prepared with coprecipitation from an aqueous solution containing trivalent iron ions. The acid solution was prepared by mixing 150 ml $FeSO_4$(1M) and 100 ml $H_3PO_4$(1M). The concentration of the NaOH and $NH_4OH$ solution was 1 M. The reaction temperature (25$^{\circ}C$) and reaction time (30 min) were fixed. Nitrogen gas (500 ml/min) was flowed during the reaction to prevent oxidation of $Fe^{2+}$. Single phase $Fe_3(PO_4)_2$ was formed when 150, 200, 250 and 300 ml NaOH solutions were added and 150, 200 ml $NH_4OH$ solutions were added. However, $Fe_3(PO_4)_2$ and $NH_4FePO_4$ were formed when 250 and 300 ml $NH_4OH$ was added. The morphology of the $Fe_3(PO_4)_2$ changed according to the pH. Plate-like lenticular shaped $Fe_3(PO_4)_2$ formed in the acidic solution below pH 5 and plate-like rhombus shaped $Fe_3(PO_4)_2$ formed around pH 9. For the $NH_4OH$, the pH value after 30 min reaction was higher with the same amount of additions of NaOH and $NH_4OH$. It is believed that the formation mechanism of $Fe_3(PO_4)_2$ is quite different between NaOH and $NH_4OH$. Further investigation on this mechanism is needed. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and the pH value was measured by pH-Meter.

• Korean Journal of Optics and Photonics
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• v.33 no.2
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• pp.67-73
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• 2022

In a head-mounted display (HMD) for virtual-reality applications, a narrow viewing angle is preferred to the usual, wide viewing angle because the HMD is positioned close in front of the user's eyes, and the display position is fixed. In this paper, we propose a new back-light unit (BLU) for implementing a narrow viewing angle, which is suitable for a HMD. By optimizing the scattering patterns in the light-guide-plate and inverse-prism structures, the viewing angle and correlations between structural parameters in the BLU components are analyzed with ray-tracing simulations. As a result, a double-angle inverse-prism structure incorporating the scattering patterns of a light-guide plate is chosen, which results in a 14% increase in center luminance, a 16% decrease in the vertical viewing angle, and a light efficiency of up to 70%, compared to a conventional BLU. Thus, the new BLU system is expected to be applied in a high-efficiency liquid crystal display.

• Journal of Animal Science and Technology
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• v.64 no.3
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• pp.481-499
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• 2022

This study aims to determine the effects of D-methionine (D-Met) isomer and the methionine precursor 2-hydroxy-4-methylthiobutanoic acid i (HMBi) supplementation on milk protein synthesis on immortalized bovine mammary epithelial cell (MAC-T). MAC-T cells were seeded using 10-cm dishes and cultured in Dulbecco's modified Eagle's medium/F12 (DMEM/F12) basic medium. The basic medium of DMEM/F12 was replaced with the lactogenic DMEM/ F12 differentiation medium when 90% of MAC-T cells reached confluency. The best dosage at 0.6 mM of D-Met and HMBi and incubation time at 72 h were used uniformly for all treatments. Each treatment was replicated six times wherein treatments were randomly assigned in a 6-well plate. Cell, medium, and total protein were determined using a bicinchoninic acid protein assay kit. Genes, proteomics and metabolomics analyses were also done to determine the mechanism of the milk protein synthesis pathway. Data were analyzed by two-way analysis of variance (ANOVA) with supplement type and plate as fixed effects. The least significant difference test was used to evaluate the differences among treatments. The HMBi treatment group had the highest beta-casein and S6 kinase beta-1 (S6K1) mRNA gene expression levels. HMBi and D-Met treatments have higher gene expressions compared to the control group. In terms of medium protein content, HMBi had a higher medium protein quantity than the control although not significantly different from the D-Met group. HMBi supplementation stimulated the production of eukaryotic translation initiation factor 3 subunit protein essential for protein translation initiation resulting in higher medium protein synthesis in the HMBi group than in the control group. The protein pathway analysis results showed that the D-Met group stimulated fructose-galactose metabolism, glycolysis pathway, phosphoinositide 3 kinase, and pyruvate metabolism. The HMBi group stimulated the pentose phosphate and glycolysis pathways. Metabolite analysis revealed that the D-Met treatment group increased seven metabolites and decreased uridine monophosphate (UMP) production. HMBi supplementation increased the production of three metabolites and decreased UMP and N-acetyl-L-glutamate production. Taken together, D-Met and HMBi supplementation are effective in stimulating milk protein synthesis in MAC-T cells by genes, proteins, and metabolites stimulation linked to milk protein synthesis.

• Journal of the Korean Society of Earth Science Education
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• v.17 no.1
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• pp.20-33
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• 2024

The purpose of this study is to examine the scientific activities of scientists justifying Wegener's continental drift in the 20th century, which is explained as a revolutionary process in earth science, and methodologically analyze the strategy of proposing new scientific theories and how the process of theory selection is carried out. Previously, the Earth was a static model and only the vertical movement of the crust was considered. However, the theory of continental drift proposed horizontal movement of the crust as a dynamic model of the Earth, eliminating numerous problems. Therefore, this study seeks to explore the rational activities of numerous scientists until the current plate tectonics theory was formed. Additionally, the theory of continental drift is in conflict with the theory of Earth shrinkage, which is an existing static model. In other words, it deviates from the existing mechanistic world view by presenting a dynamic model in which the Earth is created and changes, as opposed to a static model in which the Earth is already completed, fixed, and unchanged. As a result, old geology was weakened and new geophysics was born. The theory of continental drift and continued exploration by subsequent generations of scholars brought about a revolution in earth science. This can be said to be a good subject of investigation as educational material for various methodologies for students in earth science education, and as educational material for changing students' worldview.

• Journal of Yeungnam Medical Science
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• v.7 no.1
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• pp.81-93
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• 1990

The author fractographically analyized the cause of metal failure(the first time this procedure has been used for this metal failure)and also analyized it clinically. In this study, I selected eight cases which have been analyized fractographically. In all these cases, the analysis was done after treatment of metal failure of implants internally fixed to femur shaft fractures at the Department of Orthopedic Surgery, Yeung-Nam University Hospital during the six year period from May 1983 to September 1989. 1. Metal failure occured in five dynamic-compression plates, one Jewett nail, one screw in Rowe plate, and one interlocking nail. 2. The clinical cause of metal failure was deficiency of medial butress in five cases, incorrect position of implant in one case, and incorrect selection of implant in two cases. 3. The time interval between internal fixation and metal failure was four months in one case, between five months to twelve months in six cases, three years in one case. 4. The fractographically analytical cause of metal failure was ; first, impact failure, one case, second, fatigue failure, six cases, machining mark(stress liser), four cases type : low consistent cyclic fatigue failure irregular cyclic fatigue failure third, stress corrosion crack, one case. 5. 316L Stainless Steel has good resistance to corrosion. However, when its peculiar surface film is destroyed by fretting, it shows pitting corrosion. This is, perhaps, the main cause of metal failure. 6. It is possible that mechanical injury occured in implants during the manufacturing of implants or that making a screw hole is the main cause of metal failure.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.268-268
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• 2012

Atmospheric pressure microwave induced plasmas are used to excite and ionize chemical species for elemental analysis, for plasma reforming, and for plasma surface treatment. Microwave plasma differs significantly from other plasmas and has several interesting properties. For example, the electron density is higher in microwave plasma than in radio-frequency (RF) or direct current (DC) plasma. Several types of radical species with high density are generated under high electron density, so the reactivity of microwave plasma is expected to be very high [1]. Therefore, useful applications of atmospheric pressure microwave plasmas are expected. The surface characteristics of SUS304 stainless steel are investigated before and after surface modification by microwave plasma under atmospheric pressure conditions. The plasma device was operated by power sources with microwave frequency. We used a device based on a coaxial transmission line resonator (CTLR). The atmospheric pressure plasma jet (APPJ) in the case of microwave frequency (880 MHz) used Ar as plasma gas [2]. Typical microwave Pw was 3-10 W. To determine the optimal processing conditions, the surface treatment experiments were performed using various values of Pw (3-10 W), treatment time (5-120 s), and ratios of mixture gas (hydrogen peroxide). Torch-to-sample distance was fixed at the plasma edge point. Plasma treatment of a stainless steel plate significantly affected the wettability, contact angle (CA), and free energy (mJ/$m^2$) of the SUS304 surface. CA and ${\gamma}$ were analyzed. The optimal surface modification parameters to modify were a power of 10 W, a treatment time of 45 s, and a hydrogen peroxide content of 0.6 wt% [3]. Under these processing conditions, a CA of just $9.8^{\circ}$ was obtained. As CA decreased, wettability increased; i.e. the surface changed from hydrophobic to hydrophilic. From these results, 10 W power and 45 s treatment time are the best values to minimize CA and maximize ${\gamma}$.

• The korean journal of orthodontics
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• v.47 no.5
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• pp.298-305
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• 2017

Objective: This paper describes changes in the characteristics of patients seeking orthodontic treatment over the past decade and the treatment they received, to identify any seasonal variations or trends. Methods: This single-center retrospective cohort study included all patients who presented to Seoul National University Dental Hospital for orthodontic diagnosis and treatment between January 1, 2005 and December 31, 2015. The study analyzed a set of heterogeneous variables grouped into the following categories: demographic (age, gender, and address), clinical (Angle Classification, anomaly, mode of orthodontic treatment, removable appliances for Phase 1 treatment, fixed appliances for Phase 2 treatment, orthognathic surgery, extraction, mini-plate, mini-implant, and patient transfer) and time-related variables (date of first visit and orthodontic treatment time). Time series analysis was applied to each variable. Results: The sample included 14,510 patients with a median age of 19.5 years. The number of patients and their ages demonstrated a clear seasonal variation, which peaked in the summer and winter. Increasing trends were observed for the proportion of male patients, use of non-extraction treatment modality, use of ceramic brackets, patients from provinces outside the Seoul region at large, patients transferred from private practitioners, and patients who underwent orthognathic surgery performed by university surgeons. Decreasing trends included the use of metal brackets and orthodontic treatment time. Conclusions: Time series analysis revealed a seasonal variation in some characteristics, and several variables showed changing trends over the past decade.

• Composites Research
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• v.24 no.2
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• pp.30-37
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• 2011

Analysis of wettability between epoxy resin and glass fabric was studied. The mixing ratios of epoxy resin and anhydride hardener were varied as 1:0.5, l:l and l:1.2. Catalyst content was fixed as 0.1wt% of the mixed resin. A curing analysis by differential scanning calorimeter(DSC) showed a possible impregnation of the mixed resin at the room temperature. An effective contact angle of the mixed epoxy resin drop onto the glass fabric being preset on a flat glass plate was measured as a function of time. The wet area of the epoxy resin drop was also measured. Behaviors of the contact angle, the droplet height, the neat wet area and the coefficient of wettability were used to evaluate the wettability of the epoxy resin onto the glass fabric. It was concluded that the equivalent ratio of 1: 1.2 was the most suitable for the wettability.