• Design & Manufacturing
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• v.17 no.4
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• pp.42-51
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• 2023

In this study, we investigated the injection molding technology of thick-walled light guides, which are parts that control the light source of automotive lamps. Through injection molding analysis, the gate position that can minimize product shrinkage and deformation was selected, and a mold reflecting the analysis results was manufactured to evaluate the effect of injection speed and holding pressure on transferability during micro-pattern molding through experiments. When designing an injection mold for products with varying thicknesses, it was found that installing the gate on the side of the thicker part was advantageous for reducing volume shrinkage and deformation. It was found that the effect of shrinkage due to thickness may be greater than the position of the gate on pattern transferability. The pattern transfer error decreased as the injection speed and holding pressure increased, and it was found that increasing the injection speed was relatively effective.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.115-120
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• 2010

The reduction rate of fuel consumption by showing the fuel injection data for driver was measured in this study. The fuel injection data are composed of injection period, real time fuel economy and average fuel economy. The fuel consumption was measured by processing the voltage signal of injector and driven distance by GPS sensor. The fuel consumption was reduced by driving more carefully, i.e driving more steady without sudden acceleration and deceleration watching these fuel injection data. The reduction rate was up to 37% and the rate increased as the driver is customed to this driving pattern.

• Journal of the Korean institute of surface engineering
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• v.53 no.4
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• pp.138-143
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• 2020

In this study, we produced a coil of micro-pattern that can be used for electromagnetic wave absorber, heating material, wireless charging, sensor, antenna, etc. by using electrochemical additive manufacturing method. Currently, it contains research contents for manufacturing a micro pattern coil having practicality through control of process control variables such as applied voltage, distance between electrode, and nozzle injection. Circulation of the electrolyte through the nozzle injection control can significantly contribute to improving the surface characteristics of the coil because of minimizing voltage fluctuations that may occur during the additive manufacturing process. In addition, by applying the pulse method in the application of voltage, the lamination characteristics of the plated body were improved, which showed that the formation of a fine line width plays an important role in the production of a micro pattern coil. By applying the pulse signal to the voltage application, the additive manufacturing characteristics of the produced product were improved, and it was shown that the formation of a fine line width plays an important role in the production of a micro pattern coil.

• Journal of Nutrition and Health
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• v.32 no.7
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• pp.767-774
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• 1999

This study was carrid out to examine a part of the mechanism for the etiology of diabetic complications. Thirty normal and forty streptozotocin(STZ)-induced diabetic rats were used as the animal models. Animals were sacrificed at the time points of 3 days, 1, 2, 4 and 6 weeks after STZ-injection and time course in body weight and organ weight, the levels of blood glucose, plasma lipid patterns, and atherogenic index were measured during 6 weeks. The STZ-diabetic animals showed 63% survival rate and fsting blood glucose levels of the diabetic animals measured in the range of 230-410mg/dL during the experimental period. The body weigh of diabetic animals decreased significantly throughout the experimental period and the relative weights of organs to body weight were significantly higher than the normal control ones. The enlargement of the kidney in the diabetic animals was especially remarkable. Plasma triglyceride concentration in diabetic rats substancially increased from the first week of onset of diabetes mellitus and maintained higher levels than the control ones throughout the whole experimental period. The plasma total cholesterol level and atherogenic index in the diabetic rats were significantly higher than the normal ones from the third day after STZ injection and showed a gradual increase with the duration of the disease. Throughout the experiment, the diabetic rats consistently showed a slightly lower HDL-cholesterol level compared to the normal animals. From the results of this study, it appears that the significant changes in blood lipid pattern in STZ-diabetic animals start from the first week after STZ injection.

• Transactions of Materials Processing
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• v.16 no.1 s.91
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• pp.9-14
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• 2007

In this paper, a mold temperature control method for injection molding is proposed. The inner surface of mold is locally heated by jet impingement to improve pattern transcription. Heating by hot jet is completed while the mold is open. An experimental system that realizes the proposed idea has been built, which includes mold, nozzle assembly and heater. Actual injection molding process including the proposed heating procedure has been conducted to verify the validity of the method. The process has been done for several conditions with different jet temperatures and duration of heating. The results from different conditions are compared.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.85-90
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• 2011

In this paper a design procedure via computer-aided molding simulation is presented to optimize the air-trap locations in a speaker encloser of mobile phone. The molding flow simulation reveals that the race-tracking phenomenon is the dominant feature in the current mold design. In obtaining an optimal filling pattern, the local modifications of the wall thickness such as in a flow leader attachment are considered as the primary control factor, and both the gate position and the filling time become the secondary control factor. In the one-at-a-time approach, the last location to be filled in the mold cavity could be successfully moved to the extremities of the part, allowing a natural ventilation of entrapped air through the mold parting plane.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.192-196
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• 2005

In this paper, we investigated the possibility of replicating patterned media by nano-injection molding process with a metallic nano-stamper. The original nano-master was fabricated by E-beam lithography and ICP etching process. The metallic nano-stamper was fabricated using a nanoimprint lithography and nano-electroforming process. The nano-patterned substrate was replicated using a nano-injection molding process without additional etching process. In nano-injection molding process, since the solidified layer, generated during the polymer filling, deteriorates transcribability of nano patterns by preventing the polymer melt from filling the nano cavities, an injection-mold system was constructed to actively control the stamper surface temperature using MEMS heater and sensors. The replicated polymeric patterns using nano-injection molding process were as small as 50 nm in diameter, 150 nm in pitch, and 50 nm in depth. The replicated polymeric patterns can be applied to high density patterned media.

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.38-45
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• 2021

In this study, changes in cavitation pattern and noise by air injection were investigated experimentally in a cavitation tunnel. Air injection system that can control the location and the amount of air was manufactured and installed in an elliptic wing that exhibits similar characteristics to those of a propeller blade. Various types of cavitation were simulated on the hydrofoil by adjusting the test conditions in the cavitation tunnel, and the changes in cavitation pattern and noise according to air injection were experimentally analyzed. It was shown that the noise characteristics varied depending on the position and the amount of air injection. This means that in order to apply the air injection technology to the propeller, it is necessary to optimize the air injection location and the amount of injection according to the cavitation characteristics.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1064-1069
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• 2014

The use of emulsified fuel and EGR (Exhaust gas recirculation) system are effective methods to reduce NOx emission from diesel engines. In general, it is considered that EGR method influences diesel engine combustion in three different ways: thermal, chemical and dilution effect. Among others, the thermal effect is related to the increase of specific heat capacity due to the presence of $CO_2$ and $H_2O$ in inlet air. Meanwhile, emulsified fuel method of utilizing latent heat of vaporization and miro-explosion has been recognized as an effective technique for reducing diesel engine emissions. In this paper, an author studied on combustion and emission characteristics by using emulsified fuel (EF, Light oil : 80% + Water : 20%) and EGR (30% EGR ratio) system. And the effect of fuel injection pattern control was investigated.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.203-220
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• 1991

The purpose of this study was to investigate the changes of morphology and structure of bone tissue, caused by administration of high-dose hydrocortisone, elcatonin and cyclophosphamide. In order to carry out experiment, 60 four-week old Sprague-Dawley strain rats weighing about 107 gms were selected and divided into experimental group and control group. The experimental group was subdivided into three groups, assigned fifteen rats for each group, by the different drugs administered. Each experimental group was then categorized as follows: hydrocortisone 30㎎/㎏ b.w. with daily subcutaneous injection, elcatonin 20U/㎏ b.w. with daily subcutaneous injection, and cyclophosphamide 100㎎/㎏ b.w. with a single intraperitoneal injection. Fifteen rats were injected daily with 5㎖/㎏ b.w. of normal saline solution subcutaneously in control group. Rats in control group and experimental group were serially sacrificed on the 6th, the 15th and the 22nd day after injection of normal saline, hydrocortisone, elcatonin and cyclophosphamide, respectively. Being sacrificed, both sides of mandibular condyles were removed and fixed with 10% neutral formaline. The one side of mandibular condyles was radiographed with soft X-ray apparatus. Thereafter, the obtained radiographs were observed, and the bone density of condylar head and condylar neck regions was measured by use of transferring video-based digital radiograph. The other side was further decalcified and embedded in paraffin as usual manner, then sectioned and stained with hematoxylin and eosin, observed by light microscope. The obtained results were as follows: 1. Sclerotic changes with regularly increased trabecular pattern were seen throughout experimental periods in hydrocortisone group. Increased the number of trabecular pattern with irregularity and periodic striation on the periphery of condylar head region were appeared with lapse of time in elcatonin group. In cyclophosphamide group, irregular trabecular pattern and stippled radiopacities on mandibular condyle were observed with lapse of time. 2. The bone density of condylar head region was increased in hydrocortisone group, decreased in elcatonin group, and tended to be decreased in cyclophosphamide group, compared with that of control group according to the experimental periods. 3. The bone density of condylar neck region tended to be rather increased in hydrocortisone group, elcatonin group and cyclophosphamide group, depending on the experimental periods. 4. In microscopic studies, there were irregular trabecular bonds and osteoblastic activity in hydrocortisone group and elcatonin group throughout experimental periods, degenerative cartilage and trabecular bones in the 6th day and densely calcified trabecular bones in the 22nd day in cyclophosphamide group.