• Journal of Conservation Science
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• v.28 no.4
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• pp.403-410
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• 2012

The brine treatment applied during the fabrication of forged high tin bronze objects is considered effective at the removal of surface oxide layers developed at elevated temperatures. There is not much information, however, available for the understanding of its exact effect and purpose. This work performed laboratory experiments to characterize the effect brine treatments produce on the surface of bronze objects during fabrication. Specimens were first made in the bronze shop of the Yongin folk village under varying conditions of brine treatments, and the results obtained were then used in the following laboratory experiments where the effect of brine treatments were investigated in terms of brine concentrations, alloy compositions and thermo-mechanical treatments. The results show that oxide layers generated at high temperature are easily removed by the brine treatment. It was found that the element, chlorine, played a key role in the removal of such oxide layers as opposed to the other constituent of the brine, sodium, makes no notable contribution. In bronze alloys containing 22% tin, this brine effect is obtained regardless of the application of forging as long as the brine concentration is over 0.5% based on weight. In alloys containing lead, however, no brine effect is observed due to the molten lead that emerges from inside the hot bronze specimen and forms a thin layer on its surface.

• Korean Journal of Materials Research
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• v.26 no.10
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• pp.528-534
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• 2016

The aim of this paper is to consider the effect of the manufacturing processes on corrosion and centerline cracking of ancient bronze spoons. The ancient bronze spoons in question were made by several steps of forging, in reheated condition with cast ingots. The manufacturing method is similar to that of the modern spoons. The investigations include observations from light and scanning electron microscopes of the microstructure in terms of the crack propagation. Cracks in the centerline are caused by solute segregation in the center-line region; this solute is solidified in the final stage of bronze spoon manufacture. Centerline cracking is also caused by ${\alpha}$ phase segregation, accompanied by forged overlapping along the longitudinal direction of the spoons. A vertical stripe with cracks along the centerline of the spoon's width is formed by folding in the wrought process. The overlapping area causes crack propagation with severe corrosion on the spoon surfaces over a period of a thousand years. The failure mechanisms of ancient bronze spoons may be similar to that of modern spoons, and the estimation of the failure mechanisms of ancient spoons can be appropriate to determine failure causes for such modern spoons.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.6
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• pp.293-299
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• 2008

In order to provide with fundamental data of the wrought Mg alloy for press forging, the effect of annealing temperature on the microstructure, texture development and tensile properties is studied in a commercial AZ31B Mg alloy sheet. Basal texture i.e. $(0001){\pm}5^{\circ}$[21$\bar{3}$0] is developed in a commercial AZ31B Mg sheet, and the texture is not changed considerably by annealing over $400^{\circ}C{\times}30min$, while (10$\bar{3}$0) component with high intensity can be observed due to abnormal grain growth. When the sheet is tensile-deformed with RD, $45^{\circ}$ and TD directions at room temperature, fracture strains are given by 25.8, 21.4 and 11.9% in the order of RD, $45^{\circ}$ and TD directions, respectively. With increasing annealing temperature up to $450^{\circ}C{\times}30min$, little change in mean grain size can be revealed by annealing below $300^{\circ}C{\times}30min$ but an abnormal grain growth, where some grains become significantly coarser than the rest, occurs by annealing above $400^{\circ}C{\times}30min$. The maximum tensile strain of around 25% is obtained by annealing below $300^{\circ}C{\times}30min$, but it is abruptly decreased to 16% by annealing above $400^{\circ}C{\times}30min$ owing to intergranular fracture of abnormal grown grains.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.361-370
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• 2015

Wind energy began to receive attention as a new alternative fuel since 20 years ago and is growing as a booming global business model. Global wind power generation in the world has been continuously increasing for the past 10 years, accounting for over 30% of cumulative rate compared to total power generation. Global demand for wind power generation is gradually expanding due to restriction on carbon emission and environmental problems caused by increased greenhouse effect. Accordingly in this study, current transportation routes are classified into three types including access-priority route, economics-priority route, and convenience- priority route depending on distribution characteristics of wind power equipment in order to suggest transportation methods other than ships. The three types of transportation route that this study declared can make the Wind power equipment manufacturing companies can judge not only the duration of transportation but also effectiveness and economic feasibility. It means that the manufacturers can analyze and compare the effectiveness and economic feasibility, which are proceed by the shipping company and freight forwarder until now days.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.287-290
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• 2005

Once hot forgings for automotive parts such as wheel bearing flange to which cyclic asymmetric bending stress is continuously applied are produced, it is necessary to control their microstructure to obtain superior mechanical properties. It is however hard to control the microstructure uniformly because the strength is reduced as coarsening of ferrite grains. To investigate the microstructural alteration according to process variables during hot working, the variation of the ferrite grain size was studied by utilizing of the computer aided servo-hydraulic Gleeble tester which is hot deformation behavior reproduction equipment. In addition, the effect of the ferrite grain size of raw material on the austenite grain behavior of hot forgings was also examined. The rolling contact fatigue resistance of the induction hardened SAE 1055 steel was compared with the occasion of the same condition of SAE52100 bearing steel. As a result, it was confirmed that the ferrite grain sizes of the forgings depend on the heating temperature and cooling start temperature during hot forging and cooling processes. The induction hardened SAE1055 steel showed a superior rolling contact fatigue resistance to the induction hardened SAE52100 steel. The reason is that SAE1055 steel is freer from the material defect such as segregation than the comparative steel.

• Asia pacific journal of information systems
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• v.22 no.3
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• pp.1-27
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• 2012

Many companies have recently become interested in using social networking sites such as Twitter and Facebook as a new channel to communicate with their customers. For example, companies often offer "special deals" (e.g., coupons, discounts, free samples, etc.) to their customers who participate in promotions or events on social networking sites. Companies often make important announcements on their products or services on social networking sites. By doing so, customers are encouraged to continue to have relationships with companies on social networking sites and to recommend the companies' presence on social networking sites to other potential customers. Moreover, customers who keep close relationships with companies on social networking sites often provide the companies with valuable suggestions and feedback. For instance, Starbucks has more than 2 million followers on Twitter, and often receive suggestions and feedback for their product offerings and services from the followers on Twitter. Although companies realize potential benefits of using social networking sites as a channel to communicate with their customers, it appears that many companies have difficulty forging long-lasting relationships with customers on social networking sites. It is often reported that many customers who had followed companies on Twitter later stopped following them for various reasons. Therefore, it is an important issue to understand what motivates customers to continue to keep relationships with companies on social networking sites. Nonetheless, due attention has yet paid to this issue until recently. This study intends to contribute to our understanding on customers' intention to continue to follow companies on Twitter and to spread positive word-of-mouth about companies on Twitter. Specifically, we identify seven potential factors that customers perceive as important in evaluating their experience with companies on Twitter. The seven factors include similarity, receptivity, interactivity, ubiquitous connectivity, enjoyment, usefulness and transparency. We posit that the seven perception factors can affect the two types of satisfaction, emotional and cognitive, which can in turn influence on customers' intention to follow companies on Twitter and to spread positive word-of-mouth about companies on Twitter. Research hypotheses formulated in this study were tested with data collected from a questionnaire survey administered to customers who had been following companies on Twitter. The data was analyzed with the partial least square (PLS) approach to structural equation modeling. The results of data analysis based on 177 usable responses were generally supportive of our predictions for the effects of the seven factors identified and the two types of satisfaction. In particular, out results suggest that emotional satisfaction was strongly influenced by perceived similarity, perceived receptivity, perceived enjoyment, and perceived transparency. Cognitive satisfaction was significantly influenced by perceived similarity, perceived interactivity, perceived enjoyment, and perceived transparency. While cognitive satisfaction was found to have significant and positive effects on both continued following and word-of-mouth intentions, emotional satisfaction had a significant and positive effect only on word-of-mouth intention.

• Korean Journal of Materials Research
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• v.2 no.1
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• pp.65-75
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• 1992

0.4wt%C steel added with V and/or Nb were forged and followed by air cooling. The structure-property relationships were examined and multiple regression analysis was conducted to quantify the magnitudes of effects of microalloying elements on the properties of the steels. All material's tensile strength are greater than $70kg/\textrm{mm}^2$, so they are equal to or superior to Q/T material's(S45C). Their impact energies are less than 40J, so they are 50% of Q/T material's. Increasing the content of V from 0.10 to 0.15 wt% had brought improvement in UTS about 20% but with some sacrifice of impact energy. These were the results from the precipitation strengthening by fine dispersion of VC in ferrite, increment of pearlite volume fraction and decrement of pearlite interlamellar spacings. However, increasing the content of Nb from 0.05 to 0.l0wt % slightly improved UTS and impact energy. NbC precipitates were more effective in suppression of austenite grain coarsening than VC precipitates. Combined additions of V+Nb were more effective to bring impact toughness than sole addition. Optimum combination of strength and toughness was accomplished wish 0.4C-1. 19Mn-0.05S-0.12V-0.07Nb steel.

• Korean Security Journal
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• no.9
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• pp.27-68
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• 2005

Recently, because credit card crime using a personal credit information is increasing, professionalizing, and spreading the area, the loss occurring from credit card crime is enormous and is difficult to arrest and punish the criminals. At past, crime from forging and counterfeiting the credit card was originated by minority criminals, but at present, the types and appearance of credit card crime is very different to contrasting past crime. The numbers of people using credit card in the middle of 1990's was increasing and barometer of living conditions was evaluated by the number having credit card, therefore this bad phenomenon occurring from credit card crime was affected by abnormal consumption patterns. There is no need emphasizing the importance of personal credit card in this credit society. so, because credit card crime using personal credit card information has a bad effect, and brings the economic loss and harms to individuals, credit card company, and members joining credit card. Credit card crime using personal credit card information means the conduct using another people's credit card information(card number, expiring duration, secret number) that detected by unlawful means. And crime using dishonest means from another people's credit information is called a crime profiting money-making and a crime lending an illegal advance by making false documents. A findings on countermeasures of this study are as follows: Firstly, Diverting user's mind, improving the art of printing, and legitimating password from payment gateway was suggested. Secondly, Complementing input of password, disseminating the system of key-board protection, and promoting legitimations of immediate notification duty was suggested. Thirdly, Certificating the electronic certificates as a personal certificates, assuring the recognition by sense organ of organism, and lessening the ratio of crime occurrence, and restricting the ratio of the credit card crime was suggested.