• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.131-139
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• 1998

An aluminium sandwich sheet is the material fabricated by adhering two aluminum panels to one plastic core. If it has the same bending stiffness as an steel panel, it is 65% lighter than steel panel and 30% lighter than aluminum panel. Therefore it is marked exclusively as god substitutive materials of steel body for improving fuel efficiency. But an aluminium sandwich sheet has problem of the lower formability than steel for automotive application. In this paper we intend to develop application technologies of an aluminum sandwich sheet for auto body panels from the selecting composed materials of aluminium sandwich sheets to fabricating prototype. We selected aluminium sandwich panels fabricated by Hoogovens company. Through formability tests we have finished the design and fabricated a mould and a prototype.

• Journal of Welding and Joining
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• v.23 no.5
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• pp.25-29
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• 2005

Steel has been mainly used in the automotive industry, because of good mechanical properties, weldability and so on. However, there has been increase in using aluminum to reduce the weight of vehicle. This leads to improve fuel efficiency and to reduce air pollution. A steel-aluminum hybrid body structure is recently used not only to reduce the weight of vehicle but also to increase safety. In this paper, the laser beam joining method is suggested to join steel and aluminum. To avoid making brittle intermetallic compounds(IMC) that reduce mechanical properties of the joint area, only aluminum is melted by laser irradiation and wetted on the steel surface. The brittle IMC layer is formed with small thickness at the interface between steel and aluminum. By controlling the process parameters, brittle IMC layer thickness is suppressed under 10 micrometers which is a criterion to maintain good mechanical properties.

• Journal of Hydrogen and New Energy
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• v.23 no.5
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• pp.484-492
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• 2012

The TMS(Thermal Management System) heater in a fuel cell vehicle has been developed to prevent a decline of fuel cell durability and cold start durability. Main functions of the COD(Cathode Oxygen Depletion) heater are depletion of oxygen in a cathode as heat energy and consumption of electric power for rapid warming up of a fuel cell stack. This paper covers subjects including the design specification of a heater, heater controller for detection of overheat and reliability assessment including coolant pressure cycle test of a heater. To verify the design concept, burst pressure and deformation analysis of plastic housing were carried out. Also, temperature distribution analysis of heater surface and coolant inside of housing were carried out to verify the design concept. By designing the plastic housing instead of a steel housing, the 30% weight lightening and 50% cost reduction were attained. A module-based design of a TMS system including a heater or reducing the watt density of a heater is a problem to be solved in the near future work.

• Journal of Wellbeing Management and Applied Psychology
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• v.3 no.4
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• pp.5-10
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• 2020

Purpose: This study aims to explore the experience of cross-cultural communication adaptation between local and expatriate employees at PT. XX Organizational culture in the company is the most important factor to helpemployees in the company to work efficiently and effectively in order to achieve company goals. Research design, data and methodology: The analysis methods used in this research are data reduction, data presentation, and drawing a conclusion. From this collaboration, the cultural adaptations arouse due to the challenges for workers who have to work together with different cultural backgrounds. The method used is qualitative with a case study approach. Data collection methods used is employee interviews at PT. XX with triangulation conducted on 2 expatriates and 2 local employees. Results: Studies show that successful management is highly dependent on employees adapting to local culture and work situations. This process rarely runs smoothly because the persons in intercultural interaction do not use the same language and the lack of adaptation.. Conclusions: . In order to maintain its existence, the company strives to expand its wings in the global market and establish partnerships to expand cooperation. PT. XX from South Korea cooperated with Krakatau Steel, a state-owned Indonesian company

• Management & Information Systems Review
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• v.33 no.2
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• pp.1-12
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• 2014

The purpose of this study is to examine the the effect of organizational reputation on company commitment, turnover intention and the moderating effect of employer trust. Despite the progress of organizational reputation studies, There is a shortage of employee-perspective studies. This study considered the limitation of previous study and the help to the company. This study built a exploratory model that there is causal relationship of organizational reputatio to company commitment, turnover intention and the moderating effect of employer trust on the effect of company commitment, and turnover intention. To test hypotheses empirically, the data was collected from 239 iron and steel company's workers in Po-hang. The study showed following results. First organizational reputation had the effect on the company commitment and turnover intention significantly. a positve reputation in an organization is associate with commitment and negative reputation in an organization is associate with turnover. Second perceived employer trust played the role as the moderating variable in relation with the effect of reputation on the company commitment. The implication of these results to the union and the company, the limitation and the direction of future study were suggested.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.2
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• pp.130-137
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• 2014

As one of the largest shipbuilding company in the world, STX Offshore & Shipbuilding currently developed an inventory managing system for steel-plates, which is applied to their steel stock yard. In a traditional way to manage steel yard, almost every work has been done by manually. The manual steel-plate piling process caused some problems such as process delay due to piling errors and the uncertainty of work plan due to lack of information. To solve these problems, we developed an integrated inventory managing system based on real-time crane tracking system which automatically updates steel-plates' piling status. We built the integrated steel-plate database, developed several programs including steel-plate input program, real-time steel-plate monitoring program and steel-yard management program, and constructed hardware system for tracking magnetic cranes. As a result, a supervisor of steel-yard can manage the inventory of steel-plates efficiently and furthermore plan an efficient piling schedule and crane working schedule.

• Journal of Welding and Joining
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• v.34 no.2
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• pp.1-10
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• 2016

The use of materials for modern lightweight auto-bodies is becoming more complex than hitherto assemblies. The high strength materials nowadays frequently used for more specific fields such as the front and rear sub frames, seat belts and seats are mounted to the assembled body structure using bolt joints. It is desirable to use nuts attached to the assembled sheets by projection welding to decrease the number of loose parts which improves the quality. In this study, nut projection welding was carried out between a nut of both boron steel and carbon steel and ultra-high strength hot-stamped steel sheets. Then, the joints were characterized by optical and scanning electron microscope. The mechanical properties of the joints were evaluated by microhardness measurements and pullout tests. An indigenously designed sample fixture set-up was used for the pull-out tests to induce a tensile load in the weld. The fractography analysis revealed the dominant interfacial fracture between boron steel nut weld which is related to the shrinkage cavity and small size fusion zone. A non-interfacial fracture was observed in carbon steel nut weld, the lower hardness of HAZ caused the initiation of failure and allowed the pull-out failure which have higher in tensile strengths and superior weldability. Hence, the fracture load and failure mode characteristics can be considered as an indication of the weldability of materials in nut projection welding.

• Corrosion Science and Technology
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• v.14 no.2
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• pp.47-53
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• 2015

Recently, the bending process is greatly applied to fabricate the pipe line. Bending process can reduce welding joints and then decrease the number of inspection. Thus, the maintenance cost will be reduced. Induction heat bending process is composed of bending deformation by repeated local heat and cooling. By this thermal process, corrosion properties and microstructure can be affected. This work focused on the effect of induction heating bending process on the properties of ASME SA106 Gr. C low carbon steel pipes. Microstructure analysis, hardness measurements, and immersion corrosion test were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. Hardness was measured using a Rockwell B scale. Induction heat bending process has influenced upon the size and distribution of ferrite and pearlite phases which were transformed into finer structure than those of base metal. Even though the fine microstructure, every bent area showed a little lower hardness than that of base metal. It is considered that softening by the bending process may be arisen. Except of I2, intrados area, the others showed a similar corrosion rate to that of base metal. But even relatively high rate of intrados area was very low and acceptable. Therefore, it is judged that induction heat bending process didn't affect boric acid corrosion behaviour of carbon steel.

• Korean Journal of Metals and Materials
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• v.50 no.7
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• pp.487-493
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• 2012

To analyze the factors on stretch-flangeability for 980 MPa-grade hot-rolled steels, two types of steels (Fe-Cr and Fe-Mo) were manufactured by hot-rolling. Manufactured steels at the low coiling temperature, such as 400 and $500^{\circ}C$, had poor stretch-flangeability due to un-uniformly distributed carbides and a large deviation of interphase hardness. However, when the coiling temperature was set at $650^{\circ}C$ with Fe-Cr steel, 998 MPa of ultimate tensile strength, 19% of total elongation and 65% of the hole expanding ratio were achieved by microstructural constituents of polygonal ferrite (PF) and granular ferrite (GF) dispersed with fine carbides (<50 nm). Therefore, the material to attain 980 MPa with superior formability was the Fe-Cr steel that was precipitation-hardened in polygonal ferrite and granular ferrite at the coiling temperature $650^{\circ}C$.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.33.1-33.13
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• 2022

Background: Circadian rhythm disturbance caused by shift work has adverse effects on the metabolic homeostasis of the liver. Disruption of the metabolic homeostasis of the liver causes fat accumulation in the liver. The aim of this study was to investigate the correlation between shift work and non-alcoholic fatty liver disease (NAFLD) among male workers in the steel manufacturing industry of Korea. Methods: Based on medical examination data collected in June 2020, 2,511 male subjects from one steel manufacturing company in Korea were selected in total. NAFLD was evaluated using abdominal ultrasound, which was performed by two experienced radiologists. The multinomial logistic regression analysis was performed by adjusting for age, physical activity, smoking history, alcohol consumption, body mass index, waist circumference, blood pressure, blood glucose, lipidemia, liver function test, employment duration, and hepatotoxic materials exposure status. Results: Compared to daytime workers, the odds ratio (OR) of moderate-severe NAFLD in shift workers was 1.449 (95% confidence interval [CI], 1.028-2.043). Compared to daytime workers, the ORs of moderate-severe NAFLD were significantly higher for the group that engaged in total shift work for more than 20 years (OR, 2.285; 95% CI, 1.051-4.970), the group that was not allowed to sleep during night shift work (OR, 1.463; 95% CI, 1.030-2.078), and the group that consumed food during night shift work (OR, 1.580; 95% CI, 1.093-2.284). Conclusions: There was a correlation between shift work and moderate-severe NAFLD in male steel manufacturing workers. There will be a need for more research related to the correlation of shift work with steatohepatitis and cirrhosis in the future.