• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.19-20
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• 2006

As the Mobile and Display technology are being developed quickly, new wireless devices are released in great numbers. They reduce existing devices' life time and demand a reduction of developing period of portable devices. With these demands, existing film cutting mold used many films of portable devices, especially LCD Display, needs to be more precise, and cheaper. In this research, we have analyzed machining characteristics of cutter shapes, materials, and cutting conditions for application to other films. Cutter edge was machined by slot cutting method and CAD program to select the cutter shape and cutter angle. Also, we have determined the optimal cutting conditions using high speed machining experiments to improve the productivity.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.343-348
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• 2000

The term‘High Speed Machining’has been used for many years to describe end milling with small diameter tools at high rotational speeds. typically 10,000 - 100,000 rpm. The process was applied in the aerospace industry for the machining of light alloys, notably aluminium. In recent years, however, the mold and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. And the end-mill is an important tool in the milling process. A typical examples for the end mill is the milling of pocket and slot in which a lot of material is removed from the workpiece. Therefore the proper selection of cutting parameters for end milling is one of the important factors affecting the cutting cost. The one of the advantages of HSM is cutting thin-wall part of light alloy like Al (thinkness about 0.3mm). In this paper, firstly, we study characteristics of HSM, and then, we choose the optimal parameters(cutting forces) and investigate various machining strategies to cut thin-wall part by experiment.

• 열처리공학회지
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• 제9권3호
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• pp.177-186
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• 1996

Surface alloying of Ti alloy by $CO_2$ laser is able to produce few hundred micrometers thick TiN or TiC surface-alloyed layer with high hardness on the substrate by injecting reaction gas($N_2$ or $CH_4$). Laser surface alloying by means of process control is in many applications essential in order to obtain predictable hardening layer. This research has been investigated the effect of such parameters on TiN and TiC gas alloying of Ti-6Al-4V alloy by $CO_2$ laser. The maximum surface hardness of TiN layer was obtained 1750Hv on the conditions of 0.8kW laser power, 0.8m/min scanning speed and 100% $N_2$ atmosphere. However, the maximum hardness of TiC formation layer after laser treatment was about 630Hv. As scanning speed was increased, the hardness and depth of these layers were decreased at constant laser power.

• 한국분말재료학회지
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• 제27권5호
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• pp.373-380
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• 2020

The purpose of this study is to investigate the densification behavior and the corresponding microstructural evolution of tantalum and tantalum-tungsten alloy powders for explosively formed liners. The inherent inhomogeneous microstructures of tantalum manufactured by an ingot metallurgy might degrade the capability of the warhead. Therefore, to overcome such drawbacks, powder metallurgy was incorporated into the near-net shape process in this study. Spark plasma-sintered tantalum and its alloys with finer particle sizes exhibited higher densities and lower grain sizes. However, they were contaminated from the graphite mold during sintering. Higher compaction pressures in die and isostatic compaction techniques also enhanced the sinterability of the tantalum powders; however, a full densification could not be achieved. On the other hand, the powders exhibited full densification after being subjected to hot isostatic pressing over two times. Consequently, it was found that the hot isostatic-pressed tantalum might exhibit a lower grain size and a higher density as compared to those obtained in previous studies.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.203-208
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• 2008

Recently, the modern society in development and industrial growth is investing a lot of time and much effort to improvement and environment of life quality. Thus, the casting tape which uses environmentally friendly and human body friendly water hardening process Polymer is rapidly substituted for the gypsum cast product which has been plentifully used in medical treatment. Until currently, prior researches have a tendency to focusing the analysis about chemical creation expense and reaction quality rather than the issue about optimization of the process for this polymerization. In the polymerization process which has been accomplished with actual same chemical creation expense, there has been a problem which is the possibility of getting a different result. This is because the optimization of respectively control factors is not accomplished which affect at polymerization process. Therefore, this research sees the chemical qualities of casting tape Polymer, consequently selects the polymerization process which is suitable. And, by using a experimental design, this research will evaluate the affects which the respective factors have on remaining NCO and viscosity. futhermore, this research will carry out the process optimization which can get the above results.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.35-38
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• 2008

A pattern master and a Ni stamper for 50nm class of patterns are fabricated through e-beam lithography and Ni electroforming process. A model pattern set is designed, which is based on unit patterns of 50nm, 100nm, 150nm and 200nm in length and 50nm in width. The e-beam process is optimized to fabricate designed patterns with some parameters including dose, accelerating voltage, focal distance and developing time. For Ni electroforming to fabricate Ni stamper, a seed layer, a conducting layer, is deposited first on the pattern master fabricated by an e-beam lithography process. Ni, Ti/Ni and Cr are first tested to find optimal seed layer process. Currently the best result is obtained when adopting Cr deposited to be 100nm thick with continuous tilting motion of the master substrate during the deposition process.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.45-50
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• 2008

In previous study, it showed that the MAP was greatly effective polishing process for magnesium plate. But it had lower efficiency than magnetic materials such as SM45C. It was very difficult to cut non-magnetic materials using the MAP process because the process was fundamentally possible by help of a magnetic force. This study aimed to verify analytically formation of the magnetic field in a case of the non-magnetic materials especially focused on magnesium plate. So, In this study, the magnetic density flux was predicted using simulation program. As a result, the magnetic density flux was lower at the center of pole on inductor than outside. It had same result on the experimental verification. And magnetic force was lower according to increase of working gap. So, to improve the magnetic force, permanent magnet was installed under the workpiece. In that case, the magnetic density flux not only at center but also at outside of pole was increased. Therefore, the efficiency of magnetic abrasive polishing was also increased. A design of experimental method was adopted for assessment of parameters' effect on the MAP results of magnesium plate for improving the magnetic force.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.51-54
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• 2008

Drill process is usually used to manufacture a industry about processing, Therefore, the burr problem is very significant, The burrs took place when drill process. And then, sometimes, the burrs are often caused of some problems during automatic such as no good quality products and having good surface roughness products. And also, this paper had some experiments using magnesium. Specially, the magnesium is one of the non-ferromagnetic materials. Magnesium has attracted a lot of interest for using the industry. They offer a possible alternative to steel and aluminum in automotive and aero industries to satisfy the lightweight requirement. also, magnesium has good specific strength and absorbs vibration in occurring working process. So, it has good quality of product processing. And then, it is one of the lightest materials being used to electronic product's cases and automotive because of lightweight and miniaturization. But this material has not widely used all of the industry due to its natural property. If the magnesium is contacted water, it will cause the exploration. But, nowadays many of people study magnesium to safe their experiment and to widely use this industry.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.61-66
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• 2008

The hydraulic system have been used much in a heavy machine which high power source is desired. In the case of the heavy press machine and the injection molding machine, the use of the hydraulic power is essential especially for increasing productivity and getting the good products. Because the hydraulic circuit is very complex and the system parameters are uncertain, the development of the simulation model for hydraulic system is not easy in the heavy machine. In this case, Many researchers have used a commercial program for analysis and development in a major field of study. In this paper, the aim is to develop the simulation model of the hydraulic system with various commercial program for trajectory tracking. And adaptive control method is applied to the simulation model for the trajectory tracking of a cylinder motion. Load on the cylinder is modeled in ADAMS program, the hydraulic circuit including pump, spool valve and cylinder is modeled in AMESim program and a controller is designed in MatLab/simulink program. The suggested model is applied for the tracking of a cylinder motion, and through computer simulation, its trajectory tracking performance is illustrated.

• Steel and Composite Structures
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• 제10권3호
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• pp.245-260
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• 2010

In this paper, experimental and theoretical investigations on the response and collapse of 310 stainless steel tubes with different diameter-to-thickness ratios subjected to cyclic bending are discussed. The tube-bending device and curvature-ovalization measurement apparatus were used to conduct the experiment. The endochronic theory combined with the principle of virtual work and finite element software, ANSYS, were used to simulate the moment-curvature and ovalization-curvature relationships. It is shown that although the two methods lead to good simulation of the moment-curvature relationship, the endochronic theory combined with the principle of virtual work has the better simulation of the ovalization-curvature response when compared with experimental data and the simulation by ANSYS. In addition, the theoretical formulations proposed by Kyriakides and Shaw (1987) and Lee et al. (2001) were used to simulate the controlled curvature-number of cycles to produce buckling relationship. It is shown that the theoretical formulations effectively simulate the experimental data.