• Journal of Surface Science and Engineering
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• v.52 no.1
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• pp.43-51
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• 2019

The environmental pollution which is global warming and abnormal climate is caused by increasing population and activated economics. To reduce environmental pollution, we have being efforts into reducing $CO_2$ emission and use of energy, resources. Especially, for the sake of light weight and fuel efficiency of automotive industry, many countries have defined the restrict environmental regulation which stipulate high magnitude of reducing $CO_2$ emission. In this study, we have predicted the problem of Mu-cell injection molding through the finite element analysis as a function of temperature controlled by Joule heating or in terms of mold temperature. From the result of finite element analysis, we have determined the optimized process and made the injection mold included electric current heating system with Mu-cell manufacturing. Lastly, we analyzed the surface characteristics of the injection products with mold temperature.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.10
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• pp.595-603
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• 2005

This Paper proposes the tire mold number identification method which reads the letters on a tire surface with 3D. It is very difficult to separate the letters from the background of an image since the letters on a tire surface is an embossed data. There was many studies to read the letters on a tire surface for the factory automation, however, it was very difficult to separate the letters from the background of an image since the letters on a tire surface is embossed black characters on the black ground. In this study, we first developed the method to find the location of tire mold number, which is used to classify the tire size, from the embossed letters on a tire surface using 3-dimensional laser profile camera which is not affected by the lighting condition, then developed the method to separate the mold number from that location. As a result, we were able to contribute to automate the tire size classification which has been manually performed by operators previously.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.143-146
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• 1995

Due to the recent growth of die/mold machining industry, demands for the high-precision and the high0quality of die product are increasing rapidly. Free surfaces of die/mold are often manufactured using the ball-end milling process. It is difficult to find the cutting condition of the ball-end milling process due to the free form machining for the various tool paths on inclined surface.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.1
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• pp.104-112
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• 1998

The mold filling process has been a central issue in the development of numerical methods to solve the casting processes. A mold filling which is inherently transient free surface fluid flow, is important because the quality of casting highly depends on such phenomenon, Most of the existing numerical schemes to solve mold filling process have severe limitations in time step restrictions or Courant criteria since explicit time integration is used. Therefore, a large computation time is required to analyze casting processes. In this study, the well known SOLA-VOF method has been modified implicitly to simulate the mold filling process. Solutions to example filling problems show that the proposed method is more efficient in computation time than the original SOLA -VOF method.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1910-1914
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• 1991

In the continuous casting process, mold level fluctuation Is the major cause of the surface and sub-surface defects. In the No.3 bloom continuous caster at Kobe Works, we ensured that the major cause of mold level fluctuation was mechanical hysteresis which existed in the driving system of mold level control. Moreover, we found out that it was possible to greatly Improve the stability of mold level by estimating this mechanical hysteresis and compensating It on-line. As a result of applying a new level control system based on this method, we got accurate control over good stability.

• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.348-352
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• 1995

Severe gray mold neck rot of onion occurred in most farmers' fields in the southern part of Korea, and 20∼50% of onions were infected by the disease at Goheung, Chonnam, in 1994. Symptoms of the disease appeared on the lower leaves near the soil surface in late February. The symptoms initially appeared as yellowish blotch with compact gray mold on the surface of the infected leaves and developed to blast of the aboveground parts of onions. As brown to dark brown symptoms progressed around the necks of onion later, the bulbs were rotting gradually. Botrytis sp. repeatedly isolated from the lesions produced the typical symptom on the neck of healthy onion 7 days after wound inoculation of conidial suspension of the fungus. The fungus reisolated from the bulbs was identified as Botrytis allii Munn based on the morphological and cultural characteristics and pathogenicity. This is first report of a gray mold neck rot of onion in Korea.

• Journal of Korea Foundry Society
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• v.21 no.4
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• pp.253-259
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• 2001

There are many methods to produce metal foams, which can be classified into three groups according to the state of the starting metal i.e. liquid or powder or solid. Three types of defects such as cell closing, cell deformation or breakdown and cell misrun are thought to be occurred when we make the open cell aluminum foams by precision casting. Filling ability of the mold slurry between preform is related with cell closing, mold collapsibility is related with cell deformation or breakdown, mold temperature and pouring pressure are related with cell misrun. These factors can be evaluated by measuring slurry fluidity, burnout strength and permeability of the mold. Properties of the plaster mold were evaluated to find optimum mold conditions for high quality open cell aluminum foam in this study. Permeability was almost zero independent of burnout conditions, however, crack initiation was found on the surface of all specimens one or two minutes after taking out from the furnace. Crack has grown and disappeared with time. This crack may facilitate the mold filling when molten metal is poured, because of the improved mold permeability. It was considered that crack initiation and disappearance was closely related with temperature difference between the surface and inner part. Knocking-out the mold is a difficult problem due to the small cell size, because continuous mesh structure of the metal foam is not strong. It is not easy to remove molding material after pouring. We can expect that water quenching can facilitate the knocking-out the mold after solidification without damaging cell structures. Collapsed particles after water quenching became bigger with the increase in time.

• Transactions of Materials Processing
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• v.19 no.3
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• pp.152-159
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• 2010

Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. High-frequency induction is an efficient way to heat mold surface by electromagnetic induction in a non-contact manner, and has been recently applied to the injection molding due to its capability of rapid heating and cooling of mold surface. The present study covers a three-dimensional finite element analysis to investigate heating efficiency and structural safety of the induction heating process of an injection mold. To simulate the induction heating process, an integrated simulation method is proposed by effectively connecting an electromagnetic field analysis, a transient heat transfer analysis and a thermal stress analysis. The estimated temperature changes are compared with experimental measurements for various types of induction coil, from which heating efficiency according to the coil shape is discussed. The resulting thermal stress distributions of the mold plate for various types of induction coils are also evaluated and discussed in terms of the structural safety.

• Journal of Korea Foundry Society
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• v.27 no.3
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• pp.135-139
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• 2007

To produce higher quality of titanium casting at a lower cost, the new titanium casting technology by using a permanent metal mold was developed and applied to fabricate hip joint for biomedical application. The present study was carried out to investigate the reactivity and fluidity of the Ti-6.0 wt%Al-4.0 wt%V alloy with metal mold by applying various ceramic powders coating on the mold surface. The molten titanium for manufacturing hip joint was poured into steel mold. No reaction layer was formed on the surface of specimens fabricated steel mold coated with $Y_2O_3$ powder.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.3
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• pp.259-264
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• 2012

Automatic magnetic abrasive polishing (MAP), which can be applied after machining of a mold on a machine tool without unloading, is very effective for finishing a free-form surface such as a complicated injection mold. This study aimed to improve the efficiency of MAP of a non-ferrous mold surface. The magnetic array table and control of the electromagnet polarity were applied in the MAP of a free-form surface. In this study, first, the magnetic flux density on the mold surface was simulated to determine the optimal conditions for the polarity array. Then, the MAP efficiency for polishing a non-ferrous mold surface was estimated in terms of the change in the radius of curvature and the magnetic flux density. The most improved surface roughness was observed not only in the upward tool path but also in the working area of larger magnetic flux density.