• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.532-540
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• 2012

In this study, some considerations have been suggested in developing on-site techniques to evaluate the sensitization of stainless steels. Electrochemical potentiokinetic reactivation (EPR) technique is known to be a candidate tool for field applications since it enables quantitative assessment in reasonable test time, compared to oxalic etching (ditch) technique. The on-site application of the test method imposes additional restrictions on the selection of the test method (for example, minimum surface preparation requirement, insensitivity to testing temperature, etc.). The EPR and etching techniques have been compared in order to sensitization of stainless steel structures. It has been widely reported that the maximum sensitivity in the welded structure of stainless steel is shown at heat-affected zone (HAZ) than weldments with cast structure. In this work, sectioned weldments and external surfaces were investigated to reveal the degree of sensitization by the etching and the results were compared with those of EPR test. The EPR test showed little sensitivity to surface roughness and test temperature.

• Structural Engineering and Mechanics
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• v.64 no.1
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• pp.45-58
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• 2017

This paper presents the application of topology optimization as a design tool for a steel railway bridge. The choice of a steel railway bridge is dictated by the particular situation that it is suitable for topology optimization design. On the one hand, the current manufacturing techniques for steel structures (additive manufacturing techniques not included) are highly appropriate for material optimization and weight reduction to improve the overall structural efficiency, improve production efficiency, and reduce costs. On the other hand, the design of a railway bridge, especially at higher speeds, is dominated by minimizing the deformations, this being the basic principle of compliance optimization. However, a classical strategy of topology optimization considers typically only one or a very limited number of load cases, while the design of a steel railway bridge is characterized by relatively concentrated convoy loads, which may be present or absent at any location of the structure. The paper demonstrates the applicability of considering multiple load configurations during topology optimization and proves that a different and better optimal layout is obtained than the one from the classical strategy.

• Conservation Science in Museum
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• v.17
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• pp.43-54
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• 2016

This study examines wood materials used in the inscription sword with ring pommel discovered at Geumgwanchong Tomb in Gyeongju: one set inscribed with the name "King Isaji"(K618) and another inscribed with the phrase "the Sword of King Isaji"(M336). The scabbards of both swords are made of Juglandaceae(Juglandaceae Juglans spp). Two separate wood pieces were joined together to create the hilt and the scabbard of the sword engraved with the name "King Isaji." The hilt of the sword with the inscription "the Sword of King Isaji" was also made by joining two wood pieces.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.129-132
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• 2003

Used cutting fluid from machining processes is harmful to both environment and human health. Chemical substances that provide the lubrication function in the machining process are toxtc to the environment if the cutting fluid is released to soil and water and caused serious health problems to workers who are exposed to the cutting fluid in both liquid and mist form. Recently. cost of using cutting fluid is increasing as the number and the extensiveness of environmental protection laws and regulations increase. Therefore, the use of cutting fluid in machining processes place an enormous burden on manufacturing companies to cover the additional costs associated with their use and protection of our environment. Current trends in manufacturing are focused on minimizing or eliminating the use of metalworking fluids in machining processes. And the increased costs for the disposal of waste products (swarf, coolants and lubricants), especially in industrially developed countries, has generated interest in dry machining. A variety of new techniques are testimony that new technology has rationalized further efforts to research and implement dry machining processes. This paper presents the developed equipment, the process optimization and the applications in the field of surface grinding for the new cryogenic dry machining using a compressed cooling air. The investigated new machining process method shows many advantages compared to conventional techniques with cutting fluid.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.94-99
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• 2014

In this study, using AlN materials produced by two different sintering techniques, grinding experiments were performed under various grinding conditions, including different table speeds and cut depths. In order to measure the grinding force, a tool dynamometer was used. Surface roughness measurements and a digital microscope were also was used. The grinding forces were higher at a higher table speed and a higher cut depth. The experimental results show that the grinding characteristics of the two workpieces are similar.

• Corrosion Science and Technology
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• v.16 no.1
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• pp.38-47
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• 2017

Due to various types of Zn coatings for many decades for various applications, it is imperative to study and compare their corrosion resistance properties of some of these. Here, we introduce a systematic methodology for evaluation and validation of corrosion protection properties of metallic coatings. According to this methodology, samples are were exposed in an advanced cyclic corrosion test chamber according to ISO 14993, and removed at the end of each withdrawal for respective corrosion and electrochemical characterization to evaluate both barrier and galvanic protection properties. Corrosion protection properties of coatings were evaluated by visual examination according to ISO 10289, mass loss and subsequent corrosion rate measurements, electrochemical properties, and advanced electrochemical scanning techniques. In this study, corrosion protection properties of a commercial zinc rich coating (ZRC) on AISI 1020 mild steel substrates were evaluated and benchmarked against hot dip galvanized (HDG). Results were correlated, and corrosion protection capabilities of the two coatings were compared. The zinc rich coating performed better than hot dip galvanized coating in terms of overall corrosion protection properties, according to the exposure and experimental conditions used in this study. It proved to be a suitable candidate to replace hot dip galvanized coatings for desired applications.

• 보존과학연구
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• s.27
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• pp.83-102
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• 2006

The Suchon-ri tomb No. 1 is the earliest one among the Suchon-ri tombs excavated in 2003. The Suchon-ri tomb No. 1 yielded a number of valuable artifacts furnished with burial goods such as gilt bronze items of a crown, a pair of earrings and shoes and a loop-handled sword with inlaid silver decoration. In particular, a loop-handled sword drew scholarly attention in that it showed characteristics of Baekje such as wave patterns on a silver plate decorated in the handle and sheath and inlaid dragon design on the loop-handle. In the process of the reproducing the loop-handled sword, classification methods of the loop-handled swords, iconography decorated on the swords, unearthed loop-handled swords of the Three Kingdoms Period have been investigated along with studying the reproduction cases in Japan. In addition to the study focused on the shape of the swords, manufacturing techniques have been thoroughly analyzed through scientific methods. Finally, based on the synthesis of a series of studies and analyses, traditional manufacturing techniques employed by Baekje artisans had been inferred and a replica of the loop-handled sword was manufactured with the traditional methods.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.388-393
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• 2009

It is important to know character about efficiency of converters before manufacturing it. Recently, various techniques are developed for solar array system. Converters can be used for control of solar array's condition. So, solar array with converter structures are very useful. If we want to measure converter's efficiency after manufacturing it. It's not difficult if we have measuring equipment. But we need to measure efficiency before realization converters for development of optimized efficiency and simulations. This research offers an efficiency calculation of single phase hard switching boost converter. And it is the most basic type of converters. In fact, it can be used techniques for getting higher efficiency like soft-switching and more. But the cost is an important issue in compact solar array system. One way to escape from the cost problem is finding optimized efficiency of basic types of convener.

• Journal of Conservation Science
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• v.26 no.3
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• pp.269-276
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• 2010

This study aims to extract manufacturing techniques by analysing metallurgical characteristics of the cast-iron pot from Bubjusa, examining corrosion status and microstructure with a optical microscope, SEM-EDS, micro vickers hardness tester and XRD. The microstructure analysis has presented that ferrite and partial portion of pearlite exist within the corroded outer layer. The analysis of the inner layer revealed that there is pearlite and graphite of feather shape. The one of the middle layer, which is placed between outer and inner layer, showed that corrosion has been heavily developed. Micro vickers hardness values range from 217Hv to 698Hv in constituent layers and such values lie within the ranges of the ancient iron relics. The result of EDS analysis for each microstructure presented that the outer layer has been more decarbonized than the inner layer. XRD analysis of iron corrosion compound revealed that Goethite and Hematite had been produced from the corrosive process of iron. The study concludes that the large iron pot was made by casting technique, and microstructure of inner layer had a gray cast iron. Outer layer has been decarbonized through repetitive process of heating and cooling. This results can be used as fundamental data for comparative study to reveal manufacturing techniques of large cast-iron pot.

• The Korean Journal of Quaternary Research
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• v.18 no.1 s.22
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• pp.1-20
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• 2004

A geoscientific research was performed on 12 samples of comb-pattern potteries which were excavated at Daecheonri neolithic site, Korea. The texture and compositions of 12 potteries and surrounding metrix of soil and rocks were compared with the help of petrographic microscope, XRD and REE data. As to the manufacturing techniques thick potteries are caused by the amount and number of coarse grains which are assumed to be added shards when their distributional pattern are considered. DC1, DC3, DC 7 and DC11 samples have clearly oriented textures, and the orientation of vesicles in DC3 and DC11 samples arranged in the same direction with those on the pottery surface. This indicates the use potter's wheel technique in manufacturing potteries. Burning temperature is assumed over $800^{/circ}C$, particularly under reduction environment. As to the source, raw materials of pottery matrix are derived from the bottom of excavation site, or in an extracted outcrop of the northwestern foothill from site, while the shard materials are very similar with those extracted from sandy loams near sites. Finally any use pattern of pottery may control the pottery thickness, shard addition, and matrix selection.