• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.1
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• pp.34-40
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• 2012

We have developed a highly sensitive inspection technique based on an electron beam inspection for detecting the contact failure of a poly-Si plugged layer. It was difficult to distinguish the contact failure from normal landing plugs with high impedance. Normally, the thermal annealing method has been used to decrease the impedance of poly-Si plugs and this method increases the difference of charged characteristics and voltage contrast. However, the additional process made the loss of time and broke down the device characteristics. Here, the interval scanning method without thermal annealing was effectively applied to enhance the difference of surface voltage between well-contacted poly-Si plugs and incomplete contact plugs. It is extremely useful to detect the contact failures of non-annealed plug contacts with high impedance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.629-636
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• 2001

In order to investigate the possibility of impact punching in brittle materials, an experimental setup was developed. In the setup, a long bar as a punch was used to apply the impact load to the specimen plate and measure the applied impact force during the impact punching process. Impact punching tests with various shape of punches were performed in soda-lime glass and silicon wafer under a different level of contact pressure. The damage appearance after the impact punching was examined according to the applied contact pressure. The minimum contact pressure required for a complete punching in glass specimens without development of radial cracks around the punched hole was sought at each condition. The minimum contact pressure increased with increasing the thickness of specimens and decreasing the end radius of punches. The profile of impact forces was measured during the impact punching experiment, and it could explain well the behavior of the punching process in brittle material plates. The measured impact force increased with increasing the contact pressure applied to the plates.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.96-109
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• 1996

The airbag system is known to be extremely efficient for the protection in an automobile crash. The performance of the airbag system is evaluated by real tests. However, the test is very difficult and expensive. Therefore, the computational simulations are carried out with low cost. The airbag analysis is included in the anlysis of the full-car crashworthiness. The behavior of the airbag can be predicted by a thermodynamic analysis. The contact force between the occupant and the airbag is calculated from the contact volume and the pressure in the airbag. The injury rate is evaluated from the contact force and the acceleration of dummies. So far, the contact is defined after the airgag is fully inflated. In many cases, the occupant is seated in the out-of-position and the contact can happen during the inflation process. A new algorithm has been developed for the out-of-position. To describe the inflation process precisely, the airbag is defined by a sphere and a torus. The injury is evaluated for the contact happened at any time. The developed algorithm is coded and interfaced with an existing software in the public domain. The full-car modeling is adopted from the previous study which is tuned for the regular position and real tests. Numerical experimentation have been carried out with a couple of dummies in the out-of-position and the injury processes are analyzed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1129-1137
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• 1990

Based on the formulation which incorporates large deformation and anisotropy, an elastic-plastic finite element code is developed with membrane element to include the contact treatment. For the analysis of the general sheet metal forming process with contact condition, the treatment of contact is considered by employing the successive skew coordinate system. Three kinds of sheet metal forming processes with contact conditions are analyzed; stretching of a square diaphragm with a hemispherical punch, deep drawing of a circular cup and deep drawing of a square cup. Then the computational results are compared with the experiment. The computed loads and the distribution of the thickness strain are in good agreement with the experiment for all cases. However, the computational results of the thickness strain show the effect of bending can not be ignored in the deep drawing process whereas the effect of bending is negligible in stretching.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.350-355
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• 2009

The crysralline silicon solar cell where the solar cell market grows rapidly is occupying of about 85% or more high efficiency and low cost endeavors many crystalline solar cells. The fabricaion process of high efficiency crystalline silicon solar cells necessitate complicated fabrication processes and Ti/Pd/AG contact, This metal contacts have only been used in limited areas in spite of their good srability and low contact resistance because of expensive materials and process. Commercial solar cells with screen-printed solar cells formed by using Ag paste suffer from loe fill factor and high contact resistance and low aspect ratio. Ni and Cu metal contacts have been formed by using electroless plating and light-induced electro plating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Copper and Silver can be plated by electro & light-induced plating method. Light-induced plating makes use the photovoltaic effect of solar cell to deposit the metal on the front contact. The cell is immersed into the electrolytic plating bath and irradiated at the front side by light source, which leads to a current density in the front side grid. Electroless plated Ni/ Electro&light-induced plated Cu/ Light-induced plated Ag contact solar cells result in an energy conversion efficiency of 16.446 % on 0.2~0.6${\Omega}$ cm, $20{\times}20mm^2$, CZ(Czochralski) wafer.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.35-40
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• 2019

Laser processing has been used in various fields. In this study, the feasibility of a hydrophobic surface was investigated through the laser cladding technique. A diode laser was used, and the output was set to 600-800 W. Seven different specimens were prepared with different cladding widths and spacings, and the contact angles for water droplets were evaluated. As a result, the contact angle of water droplets measured in the direction parallel to the cladding line was higher than that in the vertical direction. The wider the cladding width and the cladding space, the higher the contact angle in the parallel direction. It is thought that when a higher contact angle is formed in the parallel direction, more air can be placed in the valley between the cladding lines. In addition, for the hydrophobic coating effect, the contact angle of the coated cladding surface was increased by about $5-15^{\circ}$ as a whole compared to the coated smooth surface. It was confirmed that the wetting characteristics were improved through the cladding.

• The korean journal of orthodontics
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• v.49 no.2
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• pp.106-115
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• 2019

Objective: This study aimed to evaluate the effects of force loading on root damage caused by contact with temporary anchorage devices (TADs) during orthodontic treatment and to examine the repair process 4, 8, and 12 weeks after TAD contact by micro-computed tomography (CT). Methods: We enrolled 42 volunteers who required bilateral upper first premolar extractions. The experimental study design was as follows. For both first premolars, cantilever springs were placed, and then TADs were immediately inserted between the premolars of all volunteers. According to the removal order of the appliances, the participants were divided into the TAD group (Group T: n = 21, only TAD removal) and the spring group (Group S: n = 21, only spring removal). A splitmouth design was adopted in both groups as follows. For each volunteer, the left premolars were extracted 4, 8, or 12 weeks after TAD-root contact. The right premolars were extracted immediately after contact in both groups (Groups T-C and S-C) and used as positive controls. Resorption volumes and numbers of craters were determined by micro-CT. Results: The numbers of resorption craters were higher in Group T than in Group S at 8 and 12 weeks (p < 0.01). Crater volumes were higher in Group T than in Group S at 4 and 12 weeks (p < 0.01, both). Conclusions: Root injury was not completely repaired 12 weeks after root-TAD contact, even when the TADs were removed in cases of continuous force application.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.3
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• pp.39-46
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• 2011

The automotive air conditioning hose is used for connecting the components of air conditioner in a vehicle. The hose is usually manufactured by the swaging process to connect the rubber hose with the metal fitting at the end of the hose. In case that the clamping force is small, the refrigerant gas in the hose can leak locally under the severe operating circumstances. The practical test of clamping force is performed by means of the measurement of separation force. In this study, the swaging process of a hose is simulated with the finite element method, to investigate the effect of friction coefficient on the clamping force. The contact condition is used in consideration of real manufacturing process, and the material properties for the Mooney-Rivlin model is obtained by the experimental results. The result interpretations are focused on the contact forces, which is displayed graphically with respect to friction coefficient, on the surfaces between the hose and the metal fittings.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.6
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• pp.74-80
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• 2022

The surface status of a workpiece determines its functionality, product quality, and manufacturing costs. Thus, several finishing technologies have been widely investigated and applied to improve surface characteristics. In this study, rotational electro-magnetic abrasive finishing (REMAF) was suggested as a non-contact finishing process to achieve high geometric precision. To verify the effects of the REMAF process on burr removal on the surface of Al6061, experiments were conducted using the Taguchi method. Based on the experimental results analyzed by the S/N ratio and ANOVA, the optimal conditions were defined as A₃B₂C₃D₃ that corresponded to 1,800 rpm of rotational speed, 1.5 kg of abrasive particle weight, 0.7 mm of abrasive diameter, and 15 min of working time. In addition, the particle weight was a key attribute for deburring, whereas the working time was less effective.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.32-39
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• 2009

This paper describes mathematical models of the torsional geared driving system for the indexing path and the mill driving path in a mill turret. The eigenvalue analysis for the models is conducted both with and without the gear contact stiffnesses. The natural frequency leads to the effect of gear contact stiffnesses on the vibration of torsional geared systems in a mill turret. It is necessary to analyze eigenvalues of the complex geared torsional system in order to prevent the unexpected vibrations.