• Journal of Industrial Technology
• /
• v.16
• /
• pp.45-50
• /
• 1996

An experimental study os performed to examine the feasibility of using wastes steel furnace slag construction materials and its utility as a replacement for the natural resources to prevent the economic loss was investigated. A half factorial exprements was performed with the variables of W/C ratio, S/A, Coarse aggrigate/Slag ratio and slump as a preliminary study for optimum mix design of concrete. The results show that the W/C ratio and Slump ratio are the most important factor to the concrete strength. The substitute of waste Slag up to 100% has little influence, saying that it can substitute the coarse aggregate without damaging the concrete properties.

• Journal of the Korean Society of Safety
• /
• v.24 no.3
• /
• pp.1-6
• /
• 2009

Recently power plants and oil refineries are focusing on capacity enlargement for better efficiency through higher temperature and higher pressure. Thickness of boiler tubes becomes lessened due to oxidation and erasion caused by high temperature bums gas flowing over tubes outside. Accordingly, mechanical stress of tubes is increasing and that is a critical factor to make a crack and fracture. To prevent those sorts of accidents, aging assessment for proper periodic repair and replacement should be conducted reliably and reasonably. We performed IIT test on Cr-Mo steel, one of the most heat-resistant materials for facilities in power plants, and we report the test result and the considerable effectiveness of IIT test.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.6 no.3
• /
• pp.58-64
• /
• 1997

A micromechanics model to describe the elastic behavior of fiber or whisker reinforced metal matrix composites was developed and the stress concentrations between reinforcements were investigated using the modified shear lag model with the comparison of finite element analysis (FEA). The rationale is based on the replacement of the matrix between fiber ends with the fictitious fiber to maintain the compatibility of displacement and traction. It was found that the new model gives a good agreement with FEA results in the small fiber aspect ratio regime as well as that in the large fiber aspect ratio regime. By the calculation of the present model, stress concentration factor in the matrix and the composite elastic modulus were predicted accurately. Some important factors affecting stress concentrations, such as fiber volume fraction, fiber aspect ratio, end gap size, and modulus ratio, were also discussed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.8
• /
• pp.1309-1316
• /
• 2003

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. But products with inferior quality are produced under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not apply this dicing method to GaN wafer, because the GaN wafer is harder than the other wafer such as SiO2, GaAs, GaAsP, and AlGaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes a new wafer dicing method using fixed diamond scriber and precision servo mechanism and determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using scriber.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.2
• /
• pp.218-225
• /
• 2003

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. However, inferior goods may be made under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not apply this dicing method to a GaN wafer, because the GaN wafer is harder than other wafers such as SiO$_2$, GaAs, GaAsP, and AlGaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using a scriber.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.164-167
• /
• 2002

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. But inferior goods are made under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not applicable this dicing method to GaN wafer, because the GaN wafer is harder than the other wafer such as SiO$_2$, GaAs, CaAsP, and AlCaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using scriber.

• Journal of the Society of Naval Architects of Korea
• /
• v.30 no.1
• /
• pp.115-124
• /
• 1993

A structural system reliability analysis is studied for the safety assessment of midship section. Probabilistically dominant collapse modes are generated by Element Replacement Method and Incrimental Load Method. In order to avoid generating the same modes repeatedly, it is branched at final plastic hinge. Using first and second order bound methods, system failure probability of midship section is computed and compared with deterministic load factor method to show the usefulness of the proposed method.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1678-1688
• /
• 2008

In this study, dredging reclamation ground were performed to evaluate the ground improvement and liquefaction reduction effect with the result that standard penetration test(SPT) and piezo penetration test(CPT) before and after of improvement. Especially, the estimate center of the pile and factor of liquefaction safety to the position of ground around with the pile presented improvement of compaction for improved compaction of dredging reclamation ground.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.4
• /
• pp.460-464
• /
• 2004

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above all, the advantage of ring-shaped electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours and is intended as a high efficacy replacement for the incandescent reflector lamp in many applications. In this paper, maxwell 3D finite element analysis program (Ansoft) was used to obtain electromagnetic properties associated with the coil and nearby structures. The electromagnetic emitting properties were presented by D simulation software operated at 250KHz and some specific conditions. Photometric characteristic of the ring-shaped electrodeless fluorescent lamp were investigated using LS-100 lightmeter and TA-0510 thermometer respectively.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.18 no.36
• /
• pp.287-295
• /
• 1995

This paper is concerned with cost analysis model in periodic maintenance policy. Generally periodic maintenance policy in which item is repaired periodic interval times. And in the article minimal repair is considered. Mimimal repair means that if a unit fails, unit is instantaneously restored to same hazard rate curve as before failure. In the paper periodic maintenance policy with minimal repair is as follows; Operating unit is periodically replaced in periodic maintenance time, if a failure occurs between minimal repair and periodic maintenance time, unit is replaced by a new item until tile periodic maintenance time comes. Also unit undergoes minimal repair at failures in minimal-repair-for-failure interval. Then total expected cost per unit time is calculated according to scale parameter of failure distribution. Maintenance cost factors are included operating, fixed, minimal repair, periodic maintenance and new item replacement cost. Numerical example is shown in which failure time of system has weibull distribution.