• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.97-103
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• 2019

Mn+1AXn (MAX) phases are a family of nano-laminated compounds that possess unique combination of typical ceramic properties and typical metallic properties. As a member of MAX-phase, $Ti_2AlN$ bulk materials are attractive for some high temperature applications. In this study, $Ti_2AlN$ bulk with high density were synthesized by spark plasma sintering method. X-ray diffraction, micro-hardness, electrical and thermal conductivity were measured to compare the effect of material properties both $Ti_2AlN$ bulk samples and a conventional Ti-6Al-4V alloy. A femto-second laser conditions were conducted at a repetition rate of 6 kHz and laser intensity of 50 %, 70% and 90 %, respectively, laser confocal microscope were used to evaluate the width and depth of ablation. Consequently, the laser ablation result of the $Ti_2AlN$ sample than that of the Ti-6Al-4V alloys show a considerably good ablation characteristics due to its higher thermal conductivity regardless of to high densification and high hardness.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.5
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• pp.103-109
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• 2019

The pressure reducing valve for water is controlled by the load of the compression spring and the force of the fluid acting on the diaphragm of the stem. Repeated upward and downward reciprocation of the pressure-reducing valve stem damages the diaphragm, resulting in leakage. In this study, we designed a stem without a diaphragm and adjusted the stiffness of the compressing spring. In order to select the spring stiffness, springs offering a stiffness of -20%, -10%, 0%, and 10% with respect to the stiffness of the compression spring attached to the existing pressure reducing valve stiffness. A prototype for the pressure reducing valve was fabricated and the pressure change was evaluated for the target static pressure (6 bar) by testing the pressure characteristics after mounting the modified stem and each compression spring. Evaluation of the pressure characteristics was carried out using ASSE 1003 and KS B 6153. In addition, the flow rates were compared by internal flow analysis of the conventional pressure reducing valve and the pressure reducing valve using the modified stems, and the flow analysis was performed using Solidworks flow simulation 2018. The spring stiffness was constantly discharged at the target static pressure of 3.793 kgf/mm, and the flow rate was increased by about 15% compared with the conventional pressure reducing valve.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.10
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• pp.105-110
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• 2020

Radioactive Oxides are formed on the surface of the primary equipment in a nuclear power plant. In order to remove the oxide film that is formed on the surfaces of the equipment, chemical and physical decontamination technologies are used. The disadvantage of traditional technologies is that they produce secondary radioactive wastes. Therefore, in this study, the short-pulsed laser eco-friendly technology was used in order to reduce production of the secondary radioactive wastes. They were also used to minimize the damages that were caused on the base material and to remove the contaminated oxide film. The study was carried out using a Stainless steel 304 specimen that was coated with nickel-ferrite particles. Further, the laser source was selected with two different wavelengths. Furthermore, the depth of the coating layer was analyzed using a 3D laser microscope by changing the laser ablation conditions. Based on the analysis, the optimal conditions of ablation were determined using a 1064nm short-pulsed laser ablation technique in order to remove the radioactively contaminated oxide film from the irradiated stainless steel surface.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.10
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• pp.98-104
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• 2020

Recently, friction stir welding of dissimilar materials has become one of the biggest issues in lightweight and eco-friendly bonding technology. In this study, a lightweight torsion beam axle, which is an automobile chassis component, was used in the welding to cast aluminum material. The friction stir welding process of A357 cast aluminum and FB590 high-strength steel as well as the effects of the process parameters were investigated and optimized using a novel definitive screening design (DSD). ANOVA was used to predict the importance of the process parameters with 13 degradation experiments using the proposed DSD. Also, FSWed experiments were conducted using an optical microscope analysis to investigate the tensile strength behavior in the weld area. In addition to determining the interaction between the tool's rotational speed and the plunge speed, results indicate that the influence of the plunge depth was the most significant.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.7
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• pp.113-120
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• 2021

An experimental device was designed to control the opening of a damper via operating the folding blade drive of the device and to control the amount of air flowing through the damper. In addition, an inverter was installed in the blower to control its fan rotation speed and hence the amount of air flowing through the damper. An experimental study was conducted on the opening of the folding blade damper and changes in the rotational speed of the blower. From the results, the theoretical air volume of the folding blade damper and experimental air volume were observed to be in good agreement within an error range of ±3%. As the mass flow rate of the air passing through the folding blade damper increases proportionally with the changes in damper opening and fan rotation speed, the performance of the damper can be controlled proportionally. The mass flow rate was also observed to increase linearly; therefore, the mass flow rate of the air passing through the folding blade damper increases proportionally with changes in the rotation speed of the blower, such that the performance of the damper is proportional to a constant air volume even with varying rotation speeds of the blower.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.24-29
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• 2021

Recently, owing to the high demand for eco-friendly cars in the automotive industry, noise and vibrations have become major challenges. The use of laminated damping steel is increasing in response to these demands. Laminated damping steel is primarily used in sound insulation plates. The vibration energy is converted into thermal energy due to the viscoelastic resin being located between two steel sheets and being able to damp the vibrations when an external force, such as, noise or vibration is applied to the steel plate. Laminated damping steel is chiefly applied to dash panels in automotive body parts, and because of its structure, junction technology for bonding with other components is necessary. However, there has not been sufficient research conducted on junctions. In this study, regardless of the electrode shape, in the range of 4.0 ~ 8.0 kA welding current, the same welding force and welding time were applied which were 2.8 kN and 200 m/s (12 cycles) and the tensile shear load and nugget size were analyzed after the resistance spot welding between different materials of laminated damping steel with a thickness of 1.035 mm. The results show that in the range of 5 ~ 8 kA welding current, 1.035 mm laminated damping steel meets the MS181-15 standard, which is the technical standard of Hyundai-Kia Motors.

• (The) Research of the performance art and culture
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• no.36
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• pp.603-647
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• 2018

During the Japanese colonial era, Chosun Central Young Men's Christian Association Hall, Gyeongseong Public Hall, or Bumingwan was used as multipurpose space where various performances or events were held. Although traditional music performed in each of the places did influence the remaining of traditional music in existence as well as the vitalization of traditional musicians' activity, since these places were mostly for Western music or other genres, no research has been carried out to study the performance of traditional music there in detail. The purpose of this study is to understand the aspects of performing traditional music in multipurpose places mentioned above. Reviewing newspaper materials of the time, this author has examined the aspects of performing traditional music in each of those places in terms of the forms of performances performance programs performers as well as performing groups the aspects of development. First, this researcher considered in what forms traditional music was performed in each of the places mostly. About performance programs, this author divided them into instrumental music, vocal music court music, and folk music. Regarding performers, this study divided them into instrumental music and vocal music professional performers and unprofessional performers male and female master singers and gisaeng and figured out the importance of each of them in different places. Also, concerning the appearance of performers and performing groups, this researcher studied how it was associated with the space, and about the aspects of performance, how it was developed in different periods was examined. In that process, this author has learned that the aspects of performing traditional music in the space were significantly influenced by the characteristics of each space and has clearly and concretely understood performing programs as well as the aspects of performers and groups' activity. With this research as an opportunity, this author expects that research will be actively conducted on the performance of traditional music in each of the places that have not been studied yet and it can contribute to figuring out the development or trends of performing traditional music during the Japanese colonial era.

• Korean Journal of Construction Engineering and Management
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• v.15 no.5
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• pp.3-12
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• 2014

With the scale of program management getting larger and complexity, More accurate and precise method for management cost estimate is demanded. However, most of project management cost estimates are based on similar cases and hence can not reflect distinct features of each project. Cost estimate precision is also not up to the standards, and also troublesome to policy-making and budget allocation. Therefore, project typical model for cost estimate of Comprehensive Project Management is developed, and makes it easier to manage level of effort and allocate cost by applying characteristic factor of each project. This study categorized the project package by phase; planning, detailed design, and bid procurement, to develop typical model. And by designating specific level of effort required for each field and rank, the study aims to improve the method for calculating the detailed and objective program cost. Outcome of this study will prevent conflicts between client and contractor, accurately calculate program management contract cost for the client, and become a reference for the contractor to receive rational and practical payments for their work.

• Korean Journal of Construction Engineering and Management
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• v.16 no.1
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• pp.119-128
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• 2015

Domestic dominant method in subcontract cost estimate for comprehensive program management is estimation by referencing similar cases or relying on the experience and expertise of the engaged. However, this method is not reliable due to lack of accuracy, making it harder for clients to plan and budget the program. Since budget itself is roughly estimated, it becomes a source of cost rise in the course of management due to design modifications. Therefore, the client and service providers shall calculate more accurate service cost by applying objective and scientific method in order to minimize cost rise and cost related dispute. Traditional cases, in estimating program management cost, took Top-Down approach based on precedents and experience. On the contrary, this study will categorize management structure into phases and activities, issue WBS for each phase to estimated schedule and cost for each code, and take Bottom-UP approach. By taking this approach named ICEP (Integrated Cost Estimate based on Project), Set project typical model will be developed for service cost estimating, calculate cost by applying project-specific factors. Also, by analyzing progress data and allocated management cost to complement them, more efficient construction management will take shape based on program management cost standards which reflect project-specific features.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.2
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• pp.397-402
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• 2008

The purpose of this study is to prepare black Panax ginseng leaf (PGL) and evaluate its antioxidative effect. In order to make black PGL, the raw PGL was successiely steamed at $95^{\circ}C$ for 3 hr nine times. The antioxidant activities of total saponins (Sa) from PGL and black PGL against peroxyl radicals and peroxynitrites were determined by the total oxy-radical scavenging capacity (TOSC) assay. Specific TOSC values for black PGL-Sa against peroxyl radicals and peroxynitrites were 2.3-fold and 2.1-fold of PGL-Sa, respectively, and 2.2-fold and 5.2-fold of glutathione, a positive control antioxidant, respectively. The black PGL-Sa exhibited stronger antioxidative effect than PGL-Sa. The main ginsenosides of black PGL were $Rg_3,\;Rk_1\;and\;Rg_5$. Among the saponins in black PGL, the amount of ginsenoside $Rg_3$ was examined by HPLC. 22.12 mg of ginsenoside $Rg_3$ was obtained from 1g of dried black PGL.