• Design & Manufacturing
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• v.13 no.2
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• pp.6-11
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• 2019

In this study, we constructed the mathematical model to evaluate the roundness for plastic injection mold parts with complicated 3D curvatures. Mathematically we started off from the equation of circle and successfully derived an analytical solution so as to minimize the area of the residuals. On the other hand, we employed the numerical method the similar optimization process for the comparison. To verify the mathematical models, we manufactured and used a ball valve type plastic parts to apply the derived model. The plastic parts was fabricated under the process conditions of 220-ton injection mold machine with a raw material of polyester. we experimentally measured (x, y) position using 3D contact automated system and applied two mathematical methods to evaluated the accuracy of the mathematical models. We found that the analytical solution gives better accuracy of 0.4036 compared to 0.4872 of the numerical solution. The numerical method however may give adaptiveness and versatility for optional simulations such as a fixed center.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.12
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• pp.1985-1990
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• 2020

Objective: The objective of this experiment was to investigate the effects of fat-soluble vitamin injection on plasma and tissue vitamin status in nursery pigs. Methods: A total of 16 pigs (initial body weight: 7.15±1.1 kg) were allotted to 2 treatments at d 7 post-weaning. Pigs were fed a corn-soybean meal-based basal diet with no supplemental vitamin A and i.m. injected with 300,000 IU of retinyl palmitate, 900 IU of d-α-tocopherol and 30,000 IU of vitamin D₃ with control pigs having no vitamin injection. Blood (d 0, 3, 7, and 14 post-injection) and tissue samples (liver, brain, heart, lung, and muscle; d 7 and 14 post-injection) were collected from pigs. Retinyl palmitate, retinol, and α-tocopherol concentrations were analyzed in plasma and tissues, while plasma was assayed for 25-hydroxycholecalciferol (25-OHD₃). Results: Plasma retinol and 25-OHD₃ concentrations increased by the vitamin injection from d 3 to 14 post-injection (p<0.05) whereas plasma retinyl palmitate was detected only in the vitamin treatment at d 3 and 7 post-injection (115.51 and 4.97 ㎍/mL, respectively). Liver retinol, retinyl palmitate, and retinol+retinyl palmitate concentrations increased by retinyl palmitate injection at d 7 and 14 post-injection (p<0.05) whereas those were not detected in the other tissues. The d-α-tocopherol injection increased α-tocopherol concentrations in plasma at d 3 and 7 post-injection (p<0.05) and in liver, heart (p<0.10), and muscle (p<0.05) at d 7 post-injection. Conclusion: Fat-soluble vitamin injection increased plasma status of α-tocopherol, retinol, retinyl palmitate and 25-OHD₃. As plasma levels decreased post-injection, vitamin A level in liver and vitamin E level in muscle, heart and liver increased. The α-tocopherol found in plasma after injection was distributed to various tissues but retinyl palmitate only to the liver.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.88-93
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• 2004

The objective of this study was to investigate applicability of epoxy injection method to cracked RC beams and structural behavior of repaired RC beams considering pre-loading conditions. For this purpose, five test beams were fabricated under two experimental variables. The main variables of this experimental study were pre-loading conditions and repair methods. The two pre-loading conditions were selected as $70\%$ and $90\%$ of nominal strength and the repair methods were to repair the cracked RC beams under free loading after crack and sustained loading. The comparative study was executed to evaluate effects of pre-loading conditions on the structural behavior of the cracked RC beams after crack-repair. The strains of reinforcement and concrete and deflections of beams at each loading step were measured and evaluated. As the results of this study, repair methods have much influence on structural behavior of epoxy injected RC beams and epoxy injection method for cracks of RC structures is appeared to be efficient.

• Archives of Plastic Surgery
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• v.45 no.6
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• pp.504-511
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• 2018

Background Acellular dermal matrix (ADM) helps wound healing by stimulating angiogenesis, acting as a chemoattractant for endothelial cells, providing growth factors, and permitting a substrate for fibroblasts to attach. The current standard for using paste-type ADM (CG Paste) in wound healing is direct application over the wounds. The major concerns regarding this method are unpredictable separation from the wounds and absorption into negative-pressure wound therapy devices. This study aimed to investigate the effects of subcutaneous injection of paste-type ADM on wound healing in rats. Methods Full-thickness skin defects were created on the dorsal skin of rats. Eighteen rats were randomly divided into three groups and treated using different wound coverage methods: group A, with a saline dressing; group B, standard application of CG Paste; and group C, injection of CG Paste. On postoperative days 3, 5, 7, 10, and 14, the wound areas were analyzed morphologically. Histological and immunohistochemical tissue analyses were performed on postoperative days 3 and 7. Results Groups B and C had significantly less raw surface than group A on postoperative days 10 and 14. Collagen fiber deposition and microvessel density were significantly higher in group C than in groups A and B on postoperative days 3 and 7. Conclusions This study showed comparable effectiveness between subcutaneous injection and the conventional dressing method of paste-type ADM. Moreover, the injection of CG Paste led to improved wound healing quality through the accumulation of collagen fibers and an increase in microvessel density.

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.3
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• pp.273-278
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• 2020

The milk fever and mastitis that occur during the colostrum period in dairy cattle cause great damage in the dairy industry by causing a rapid decline in the cattle's health and decreasing milk production. In order to prevent this, gradual milking (GM), calcium injection with gradual milking (CG), and calcium injection with complete milking (CC) methods are used. However, differences in effectiveness between these methods have not been established. Therefore, this study was conducted to determine the effects of each preventive method on milk fever and mastitis. The results of this study showed that while there was a significant negative correlation of GM with milk fever and mastitis (r = -0.657, p < 0.05), there was no correlation of CG and CC with milk fever and mastitis. The incidence of milk fever was significantly lower in CG and CC than in GM (p < 0.05) but no differences in the incidence of mastitis were observed between the three groups. No significant differences in the rate of recovery from milk fever and mastitis were observed between the three groups. The recurrence rate of milk fever was significantly higher in CG and CC than in GM (p < 0.05), though no differences in the recurrence rate of mastitis were observed. This study showed an inverse relationship between the incidence rates of milk fever and mastitis when calcium injection was not used during the colostrum period. When calcium injections were used, the incidence of milk fever was reduced without affecting the incidence of mastitis regardless of the milking method, but the recurrence rate of milk fever was increased. The results of this study would be useful for controlling blood calcium concentrations and establishing efficient milking strategy in order to effectively prevent milk fever and mastitis in dairy cattle during the colostrum period.

• Journal of ILASS-Korea
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• v.19 no.3
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• pp.115-122
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• 2014

As a demand for an automobile increases, air pollution and a problem of the energy resources come to the fore in the world. Consequently, governments of every country established ordinances for green-house gas reduction and improvement of air pollution problem. Especially, as international oil price increases, engine using clean energy are being developed competitively with alternative transportation energy sources development policy as the center. Bio ethanol, one of the renewable energy produced from biomass, gained spotlight for transportation energy sources. Studies are in progress to improve fuel supply methods and combustion methods which are key features, one of the engine technologies. DI(Direct Injection), which can reduce fuel consumption rate by injecting fuel directly into the cylinder, is being studied for Green-house gas reduction and fuel economy enhancement at SI(Spark Ignition). GDI(Galoine Direct Injection) has an advantage to meet the regulations for fuel efficiency and $CO_2$ emissions. However it produces increased number of ultrafine particles, that yet received attention in the existing port-injection system, and NOX. As fuel is injected into the cylinder with high-pressure, a proper injection strategy is required by characteristics of a fuel. Especially, when alcohol type fuel is considered. In this study, we tried to get a base data bio-ethanol mixture in GDI, and combustion for optimization. We set fuel mixture rate and fuel injection pressure as parameters and took a picture with a high speed camera after gasoline-ethanol mixture fuel was injected into a constant volume combustion chamber. We figured out spraying characteristic according to parameters. Also, we determine combustion characteristics by measuring emissions and analyzing combustion.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.3
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• pp.399-405
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• 1999

Objective: In the preparation of ICSI, cumulus and corona cells should be removed from the oocytes by using a combination of enzymatic (hyaluronidase) and mechanical (pipetting) methods. But little is known about the effects of different degrees of oocyte denudation and incubation time between denudation and sperm injection on the outcomes of ICSI. The aim of this study was to evaluate the effects of varying the degrees of oocyte denudation and the lengths of incubation time from denudation to sperm injection on the outcomes of ICSI. Methods: In experiment 1, patients (oocytes) were grouped into group A and B according to the degree of denudation, complete and partial, respectively. In experiment 2, patients (oocytes) were grouped into group I, II and III according to the length of incubation time of denuded oocytes until sperm injection as < 1, $1{\sim}2$ and >2 hours, respectively. Results: There was no significant difference between the degree of oocyte denudation on the survival, fertilization and development rates after ICSI procedure. In case of the incubation time of denuded oocytes until ICSI, survival rates was higher in group III (83.1 %) than in group I (61.5%, p<0.05) or group II (64.3%). However no statistically significant differences were found between incubation time and fertilization or development rates. Conclusions: This study reveals that the outcomes of ICSI are not affected by the degree (complete or partial) of oocyte denudation. However, the denuded oocytes with incubation period of more than 2 hours show better outcomes of ICSI than those with the incubation period of less than 2 hours.

• Journal of Veterinary Science
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• v.21 no.6
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• pp.90.1-90.11
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• 2020

Background: Mandibular fractures are common in camels, leading to considerable economic losses. This study explored methods of improving mandibular fractures repair, adjuvant with interdental wire, or bone plate fixation. Autologous bone marrow (BM) injection enhances osteogenesis and rapid healing. Objectives: To investigate the effect of autologous BM aspirate as an adjuvant treatment for repairing mandibular fractures in camels with interdental wire, or bone plate fixation. Methods: Thirty dromedary camels aged 5-8 years and of both sexes were randomly divided into 4 treatment groups: group 1 (n = 10) treated with stainless steel wire fixation and BM injection at the fracture line, group 2 (n = 10) treated with plate fixation and BM injection at the fracture line, group 3 (n = 5) treated with stainless steel bone wire fixation and placebo saline injection at the fracture line, and group 4 (n = 5) treated with plate fixation and placebo injection at the fracture line. The mandibular fractures were followed weekly for 12 weeks postoperatively to assess improvement and healing based on clinical evaluation, radiographic union scale, and bone turnover markers (i.e., bone alkaline phosphatase, osteocalcin, pyridinoline, and deoxypyridinoline). Results: Compared to other groups, elevated bone turnover markers in group 1 were demonstrated (p < 0.05) on the seventh postoperative day. Likewise, compared to other groups, both clinical findings and radiographic union scale significantly improved (p < 0.05) in group 1 on the 56th postoperative day. Conclusions: BM aspirate has a promising beneficial osteogenic effect on mandibular fracture repair in camels, most notably when combined with interdental wire fixation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.14-20
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• 2015

Molding technologies for plastic microstructures have been extensively investigated during the last two decades, and theoretical and numerical studies on the micro molding process have provided efficient tools for the development of such molding technologies. In this paper, we present a review of numerical simulation methods for the micro molding process. Basic models for a description of the material property, governing equations of the flow and heat transfer during the molding process, and numerical methods will be described. Particularly, numerical simulations for micro injection molding and hot embossing processes will be presented, and their main features noted and compared to those for conventional molding processes.

• Journal of Powder Materials
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• v.25 no.4
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• pp.346-354
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• 2018

Over the last decade, the study of the synthesis of semiconductor colloidal quantum dots has progressed at a tremendous rate. Colloidal quantum dots, which possess unique spectral-luminescent characteristics, are of great interest in the development of novel materials and devices, which are promising for use in various fields. Several studies have been carried out on hot injection synthesis methods. However, these methods have been found to be unsuitable for large-capacity synthesis. Therefore, this review paper introduces synthesis methods other than the hot injection synthesis method, to synthesize quantum dots with excellent optical properties, through continuous synthesis and large capacity synthesis. In addition, examples of the application of synthesized colloid quantum dots in displays, solar cells, and bio industries are provided.