• Asia-Pacific Journal of Business
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• v.8 no.1
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• pp.67-77
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• 2017

The purpose of this study was to analysis Korean market competitiveness of Chinese metal items. Methods of analysis were Market Share Index, Market Comparative Advantage. The data was collected through Korean Materials & Components Technology Network and period of analysis were 2009-2016. Chinese main 6 metal items which recorded high-ranked export sum and exported to Korea in 2009-2016. From this study, following results were found. i) In searching trade balance aspects through MSI, highly ranked Chinese metal items in Korea market were steel rolling, pressing&elongation products, steel tubes, steel casting industry. ii) In searching market advantage aspects through MCA, Chinese metal items have strong competitiveness in Korea market. especially, steel rolling, pressing & elongation products, steel tubes, steel casting industry had strong competitiveness in Korea Market. In conclusion, we found that most of Chines metal items have competitiveness in Korea market. Especially, steel rolling, pressing & elongation products had very strong competitiveness in Korea market.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.132-141
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• 1999

No. 1 PL(Pickling Line) and No. 1 TCM(Tandem Cold Rolling Mill) at Pohang works started up in 1977 and have been operating successfully keeping high productivity for productivity thin gauge sheat such as BP, CR and silicon steel. On the other hand, customer's requirements of quality level are rasing higher continuously, so that Pohang works has combined and revamped No. 1 PL and No. 1 TCM in order to improve labor productivity, thickness accuracy and shape control capability, and so on in the period of 1977∼1999. This paper introduce the applied facilities, technologies and recent operations after revamping.

• Transactions of the Society of Information Storage Systems
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• v.9 no.2
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• pp.36-41
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• 2013

Frictional behavior of a single carbon nanotube(CNT) was investigated using molecular dynamics simulation. A single CNT aligned horizontally on silver or graphene substrate was modeled to evaluate its frictional behavior such as frictional force and rolling/sliding motion with respect to potential parameter and lattice structure of the substrate. As a result, it was found that friction and rolling was affected by adhesion between two surfaces and period of the rolling depended on lattice distance of the substrate.

• Journal of the Korean Society for Heat Treatment
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• v.11 no.3
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• pp.192-199
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• 1998

This study was carried out to investigate the influence of variations in the temperature and time of isothermal heat treatment, applied stresses and prestrain on the isothermal transformation behavior of ${\gamma}$ and ${\sigma}$ phases and mechanical properties of 25Cr-7Ni-3Mo duplex stainless steel. The precipitation of ${\gamma}$ and ${\sigma}$ phases through isothermal heat treatment showed the type curves with a certain incubation period, the curve migrated to in a short period of time and the amount of precipitation increased with decreasing isothermal heat treatment temperature. Under the state of isothermal transformation, the precipitation of ${\gamma}$ and ${\sigma}$ phases was stimulated by applied stress, with increasing applied stress, the curves migrated to in a short period of time and also observed that the application of stress has a greater influence on the amount of ${\sigma}$ precipitation than that of ${\gamma}$ precipitation. The precipitation of ${\gamma}$ and ${\sigma}$ phases was stimulated by cold and warm rolling before isothermal heat treatment and precipitation of ${\gamma}$ and ${\sigma}$ phases has a greater influence on the warm rolling than cold rolling. The tensile strength and hardness increased with increasing cold and warm rooling reduction ratio.

• Journal of Fisheries and Marine Sciences Education
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• v.21 no.1
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• pp.68-77
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• 2009

In this study it will be discussed how to solve the problem of discomfort from rolling motion on the small fishing boats. Up to now, the equipments of reducing rolling system can be examined by various case, but difficult to apply small vessel by function, space and costly establishment. A way of improving the feeling of getting on a boat through the equipped sail at stern edge of bulwark top was researched and developed. The author has tested the sailing performance of the experimental skiff boat, from the signals obtained by the inclinometer in irregular waves and compared with the results got in sail on and off mode operation for 10 minutes duration at the conditions of stop and underway. These data has been analyzed in the application statistical methods. Eventually we summarize the analyzed results obtained from the vessel while stationary and underway for two cases, the vessel with a sail and the vessel without a sail. The field test was done in Jeju outer harbor. The ratio of the motion responses at resonance for the sail with and without cases indicate that under given conditions the motion was reduced by the efficiency of diminution is 4.726%, 2.792% in the stopping and 11.663%, 3.282% in the underway and mean rolling periods are 2.158, 2.142, 2.421, 2.412sec. and 1.968, 1.963, 2.089, 2.051sec. respectively. Consequently the efficiency of diminution was higher when the ship is underway and rolling periods got longer in the equipped sail.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.14 no.2
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• pp.69-78
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• 1978

It is well known that the aluminizing steel is excellent in corrosion resistance and heat resistance. Therefore it has been used as boiler parts, heat exchanger parts and guide rails which are used under comparatively simple conditions. Recently, it has been noticed that aluminizing steel has high resistance to various atmosphere, high temperature oxidation and seawater resistance. So its usage has been extended widely to the production of parts such as intake and exhaust valve of internal combustion engine, turbine blade and pipelines On ships which required such properties. It is considered that aluminium coated steel is excellent in wear resistance because of high hardness on main ingredient FezAIs of Fe-AI alloy layer existed in diffusion coating layer. And it will beused as a new material taking wear resitance with seawater resistance in marine field. However it is difficult to findout any report concering the wear behaviors or properties of alum in izing steel. In this study the experiment was carried out under the condition of rolling-sliding contact using an Amsler-type wear testing machine at 0.80, 0.91, 1. 10, 1. 25% of slip ratio and 55.43, 78.38, 110.85 kg/mm^2 of Hertz's contact stress in run-in period for the purpose of service-ability test of aluminizing steel as a wear resisting material and obtaining the available design data. The followings are the obtained results from the experimen tal study; 1) The 2nd diffusion material has most excellent wear resistance. This material has brought out about 18% decrease of wear weight in a lower friction load level and 40~G decrease in a higher level comparing to the raw material. 2) Satisfactory effect of wear resistivity cannot be much expected in 2nd diffusion specimens. This is considered due to the formation of fine void in the alloy layer near the boundary to the aluminium layer. 3) Fracture on friction surface of aluminizing steel by the rolling-sliding contact is spalling, and spalling crack occurres initially beneath the specimen surface near the boundary in diffusion coating layer.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1916-1932
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• 2008

The railway accident is characterized by widespread and great(immerse) damage to our society when an accident occurred even if the probability of a railway accident is low. It is no doubt that the role of a rolling stock driver who are active in the first line of the rail safety driving is the most important to prevent an unexpected railway accident. Before new railway safety law being taken into effect, each railway operating organization had the responsibility of training a rolling stock driver by qualification criteria (the requirements or standards of competency), training period, probation period decided on their own standards. To train drivers driving same locomotive model, each railway operating organization had a variety of standards to draft and train trainees. Consequently, It was considered inefficient way to train and manage rolling stock drivers. However, after implementing the new railway safety law, a new system including training and evaluation process to issue driver's license on the condition that entire requirements are satisfied has been established. To prove the competency of the rolling stock driver objectively, training center and third-party evaluation center are divided individually and assigned by government office. Training center should design the training program to allot theatrical education time for different trainee group and to secure maximum practical training time utilizing simulator system to enhance the rolling stock driver's competency. This study analyzes certain conditions necessary to maximize the effectiveness and practical use of training for aquisition of a driver's license and the problems of the existing rail safety law and the ways to improve them.

• IE interfaces
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• v.16 no.1
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• pp.27-33
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• 2003

The maintenance cost in K Steelworks has been continuously increased in proportion to the production cost. However, there seems to be a possibility of reducing cost through the optimization of maintenance actions. The failure types of the equipment in steelworks ate various with different failure cost. Thus the failure rate and cost of each type of failures should be considered simultaneously when the optimum maintenance period is to be determined. It is considered that the equipment undergoes periodic replacement and a specified number of incomplete preventive maintenance actions are performed during a replacement period. Assuming that the time to failure follows a Weibull distribution, the parameters of the failure rate are estimated using the maximum likelihood estimation. The optimal replacement period is determined to minimize the average cost per unit time. As the result of analysis it is suggested that the existing maintenance period for a hot-rolling equipment can be extended significantly.

• Communications for Statistical Applications and Methods
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• v.25 no.4
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• pp.397-409
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• 2018

The world financial markets are inter-linked in ways that varies according to market and time. We examine the causality of change focusing on the Korean market as related to the U.S. (S&P 500), Japan (Nikkei 225), Hong-Kong (HSI), and European (DAX) markets. In order to capture time-varying causality running from and to the Korea stock market, we apply the Granger causality test under a VAR model with a wild bootstrap rolling-window approach. We also propose a new concept of a significant causality ratio to measure the intensity of the Granger causality in each time unit. There are many asymmetric strengths in mutual Granger causal relationships. Moreover, there are cases with significant Granger causal relations only in one direction. The period with the most severe Granger causality both running from and to the KOSPI market is the GFC. The market that formed the two-way Granger causal relationship with the KOSPI market for the longest period is the S&P 500. The HSI and DAX markets have the strongest two-way Granger causal relationship with the KOSPI shortly after 2000, and the Nikkei market had the strongest two-way Granger causal relationship with the KOSPI market before the Asian financial crisis.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.183-187
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• 2004

To predict rolling performance for a barge-type FPSO, the evaluation of correct nonlinear roll damping is critical. The squall section of FPSO causes a fair amount of viscous damping effect. Free roll decoy tests were conducted to estimate nonlinear roll damping for a barge-typ FPSO of three different loading conditions. The roll motion RAO was deduced by model tests in the wave condition of wideband spectrum. In numerical calculation, the quadratic damping was considered as equivalent linear damping using the results of free roll decay test. Tested roll performance in JONSWAP wave spectrum was compared with numerical results. These two results show good agreement, in spite of proximity in peak wave period and roll natural period.