• Transactions of Materials Processing
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• v.18 no.2
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• pp.122-127
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• 2009

The injection mold with multi-cavity is essential for mass production of plastic products. Multi-cavity molds are designed to geometrically balanced runner system to uniformly fill to each cavity. However, despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed in injection molding. To solve these problems, many studies such as Melt Flipper, RC Pin, and others have been presented. The results of these studies have been an effect on filling balances in multi-cavity molds. But, those have had a limitation that additional insert parts must have existed in the mold. In this study, a new runner system is suggested for filling balance between cavity to cavity using "Melt-Buffer" with simple change of runner shape. A series of simulation to confirm feasibility of Melt-Buffer's effects was conducted using injection molding CAE program. Also, a series of injection molding experiment was conducted using plastic materials such as ABS and PP. As results of this study, feasibilities of filling balances by Melt-Buffer were confirmed.

• Design & Manufacturing
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• v.7 no.1
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• pp.19-22
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• 2013

Almost all injection molds have multi-cavity runner system for mass production, which are designed with geometrically balanced runner system in order to accomplish filling balance between cavity to cavity during processing. However, even though geometrically balanced runner is used, filling imbalances have been observed. So, many studies for improving filling balance in the multi-cavities molds are worked up. In this study, the Melt-Buffer which is a new runner system for filling balance has been suggested, and a series of experiment about degree of filling balance in cavity-to-cavity was conducted in the mold with the Melt-Buffer. From the experiment, the filling balance was increased up to 5~6% by using the Melt-Buffer.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.95-98
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• 2008

Almost all injection molds have multi-cavity runner system for mass production, which are designed with geometrically balanced runner system in order to accomplish filling balance between cavity to cavity during processing. However, even though geometrically balanced runner is used, filling imbalances have been observed. So, many studies for improving filling balance in the multi-cavities molds are worked up. In this study, the Melt-Buffer which is a new runner system for filling balance has been suggested, and a series of experiment about degree of filling balance in cavity-to-cavity was conducted in the mold with the Melt-Buffer. From the experiment, the filling balance was increased up to $5^{\sim}6%$ by using the Melt-Buffer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.661-662
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• 2009

• Journal of Environmental Science International
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• v.23 no.7
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• pp.1339-1347
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• 2014

This study were performed on roadside buffer green in Songpa-dong, Songpa-gu, Seoul in order to analyze the anion concentration according to the type of composition of roadside buffer green. Buffer green separating the physical structure of the measurement points and measurement locations were separated by roadside, green interior, the other side of the road. planting density and deposit of trees per each buffer green was measured in the order of mounding type> slope type> the plain type. If the measured temperature of the location-specific weather elements roadside> inside> the other side of the road in order of measurement and the temperature is lowered farther away from the road. If the relative humidity of the road on the other side> inside> the roadside in order to measure and this is the opposite of the temperature tendency. According to physical structure reduction of the temperature on the other side of the road and roadside in order of mounding type> the plain type> slope type was measured. As a result of measuring a anion therefore concentration of the anion inside of melt is in order of mounding type> the plain type> slope type, tended to match the melt characteristics. According to measured positions anion concentration is in the order of the other side of the road> inside> the roadside was measured. As a result of correlation analysis, in the case of measurement location-specific weather and anions the temperature is positive correlation, relative humidity is negative correlation and that's results of previous studies were supported.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.4
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• pp.161-166
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• 2013

AlN buffer layers have been used for the growth of GaN layers on Si substrates. However, the doping of high concentration of carriers into AlN layers is still not easy, therefore it may cause the increase of series resistance when it is used for the electrical or optical devices. In this work, to improve such a problem, the growth of GaN layers on Si substrates were performed using metal buffer layers instead of AlN buffer layer. We tried combinations of Ti, Al, Cr and Au as metal buffer layers for the growth of GaN on Si substrates. Surface morphology was measured by optical microscope and scanning electron microscope (SEM), and optical properties and crystalline quality were measured by photoluminescence (PL) and X-ray diffractometer (XRD), respectively. Electrical resistances for both cases of AlN and metal buffer layer were compared by current-voltage (I-V) measurement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.1
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• pp.1-6
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• 2017

Tungsten carbide (WC) has been suggested as a new buffer layer for the GaN-on-Si technology. We have investigated and optimized the sputtering condition of WC layer on the Si-substrate. We confirmed the suppression of the Si melt-back phenomenon. In addition, surface energy of WC/Si layer was measured to confirm the possibility as a buffer layer for GaN growth. We found that the surface energy(${\gamma}=82.46mJ/cm^2$) of WC layer is very similar to that of sapphire substrate(${\gamma}=82.71mJ/cm^2$). We grow GaN layer on the WC buffer by using gas-source MBE, and confirm that it is available to grow a single crystalline GaN layer.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.680-685
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• 1998

Two kinds of new aliphatic diols were synthesized by the ring-opening reaction of lactide and glycolide with 1,4-butanediol, a difunctional initiator, in the presence of stannous octoate. The resulting aliphatic diols were melt-polymerized with D-tartaric acid at 150 ℃ to produce new crosslinkable polyesters. They were reacted with hexamethylene diisocyanate in THF at 65 ℃ in a teflon mold for 24 h to prepare sequentially ordered crosslinked polyesters (BD/LT/GL/D-tartarate). Degradation of the prepared yellow crosslinked films was carried out in a buffer solution in order to examine the effect of time, pH, temperature and crosslinking degree on their degradation rate and mechanism. The rate of degradation increased with an increase in pH and temperature, but it decreased with increasing degree of crosslinkage incorporated into the crosslinked polyesters. We also found that the crosslinked polymers were converted into the acidic compounds such as lactic, glycolic, and D-tartaric acids during the degradation.

• Polymer(Korea)
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• v.33 no.6
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• pp.581-587
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• 2009

PLA/PEG blend fibers composed of poly (lactic acid) (PLA) and poly (ethylene glycol) (PEG) were prepared via melt blending and spinning for bioabsorbable filament sutures. The blend fibers hydrolyzed with the immersion in a phosphate buffer solution at pH 7.4 and $37\;^{\circ}C$ for 1~8 weeks. The effects of blending time, blend composition, and hydrolysis time on the weight loss and tensile strength of the hydrolyzed blend fibers were investigated. After hydrolysis, the weight loss of the blend fibers increased with increasing PEG content, blending time, and hydrolysis time. The tensile strength and tensile modulus of the blend fibers decreased with increasing PEG content, blending time, and hydrolysis time. Therefore, it can be concluded that the weight loss of the PLA/PEG blend fibers was less than 0.9% even at hydrolysis time of 2 weeks and their strength retentions were over 90%.

• Progress in Superconductivity and Cryogenics
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• v.22 no.1
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• pp.1-6
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• 2020

This is a parameter study for the direct fabrication of a large grain YBCO bulk superconductors using Y₂O₃, BaCO₃ and CuO powders without any grinding step. The cracks, which have been formed due to volume contraction during calcination step, have been prevented by controlling the heating rate at 930~950 ℃. It has been observed that multi-grain growth has occurred due to the dissolution of Sm123 seed due to the retention of carbon in Ba-Cu-O melt. In order to accelerate the carbon release in prior calcination heat treatment, the reduction of pellet thickness and the drilling of artificial holes have been applied. Single-grain YBCO bulk superconductor has been successfully fabricated by stacking multiple thin slab. However, the crack formation has been rather prominent for the compact with artificial holes. The use of buffer pellet, which is supposed to act as diffusion barrier, has prevented the dissolution of Sm123 seed crystal and has led to the growth of single grain of high content of carbon containing specimen.