• 한국자동차공학회논문집
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• 제21권2호
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• pp.9-16
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• 2013

The comparisons of performance characteristics between the super-mirror face grinding machine using variable air pressure developed in this laboratory to grind precisely the sliding face of a surface hardened workpiece with thermal spray and the conventional one are investigated by measuring the surface roughness and hardness for a SCM440. To process variously workpiece according to shape, size and materials, the rotating and contacting forces of the developed grinding machine can be changed by air pressure. The surface roughness of processed workpiece can be also attained to state of mirror face by grinding precisely the sliding face with changing the rotating speed of diamond wheel. It is possible to be attached to the various machine tools because the super-mirror face grinding machine using variable air pressure is a small size. The grinding efficiency is elevated because it can be worked by two or more grinding machines attached to concurrently a machine tool for the large workpiece. In this study, results show that the cusp height of the super-mirror face grinding machine for the particle size of 100 and $1500No./mm^2$ is lower than that of the conventional one because the vibration is reduced by rotating very fast the diamond wheel with a pressed air and it can be processed by rotating the diamond wheel with a constantly varied air pressure perpendicular to workpiece surface, and that the workpiece in the super-mirror face grinding machine for the particle size of $3000No./mm^2$ can be processed to state of mirror face that is rarely seen by the cusp height. It is also found that the surface hardness of both the conventional and the super-mirror face grinding machines are increased as the particle size of diamond wheel is reduced, and the surface hardness of the super-mirror face grinding machine is HRC 1.1 ~ 1.8 higher than that of the conventional one.

• 한국재료학회지
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• 제16권11호
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• pp.681-686
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• 2006

Plasma nitrocarburising and plasma post oxidation were performed to improve the wear and corrosion resistance of S45C and SCM440 steel by a plasma ion nitriding system. Plasma nitrocarburizing was conducted for 3h at $570^{\circ}C$ in the nitrogen, hydrogen and methane atmosphere to produce the ${\varepsilon}-Fe_{2-3}$(N, C) phase. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature of $500^{\circ}C$ for 1 hour. The very thin magnetite ($Fe_3O_4$) layer $1-2{\mu}m$ in thickness on top of the $15{\sim}25{\mu}m$ ${\varepsilon}-Fe_{2-3}$(N, C) compound layer was obtained by plasma post oxidation. A salt spray test and electrochemical testing revealed that in the tested 5% NaCl solution, the corrosion characteristics of the nitrocarburized compound layer could be further improved by the application of the superficial magnetite layer. Throttle valve shafts were treated under optimum plasma processing conditions. Accelerated life time test results, using throttle body assembled with shaft treated by plasma nitrocarburising and post oxidation, showed that plasma nitrocarburizing and plasma post oxidation processes could be a viable technology in the very near future which can replace $Cr^{6+}$ plating.

• 한국항만경제학회지
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• 제27권1호
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• pp.13-30
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• 2011

글로벌 물류기업의 경쟁이 심화되어가고 있어 핵심역량분야에 관한 비교우위의 확보가 필요하다. 글로벌기업은 공급연쇄관리 측면에서 핵심거점을 위한 전략을 수행하기위하여 항만물류배후단지를 거점화한다. 항만배후물류단지는 지속 가능항 물동량을 확보 할수 있어 부가가치가 창출과 지역 경제에 큰 영향을 미친다. 오늘날 항만 물류배후단지의 물류시설과 서비스를 보다 체계적이며 효과적으로 활용하여 경영의 효율성을 높여야한다. 정부는 항만물류배후단지에 관련하여 축소화 정책을 시행하고 있으나 세계 경제자유구역중 우리나라는 마산자유무역지대(FTZ)만이 24위이다. 본 연구는 어느정도 물동량을 확보하여야하며 우리나라의 효율적인 항만물류배후단지를 제시하고자 한다. CCR과 BCC모형의 효율성이 100%로 나타난 가장 효율적인 항만물류배후 단지는 광양항의 경우, 로지스올인터내셔널(주) 아이씨모터스(주), 부산항의 경우, 부산신항 CFS(주), 신대륙물류(주), SI로지스틱스, 한진케리,로지스틱스(주)이 있다. 부산항은 IRS 5개 CRS2개 DRS16개이다. 광양항은 IRS 5개 CRS2개 DRS16개이다. CCR 모형 분석에서 물동량을 확보하여 매출액을 증가시켜야 하는 기업으로 부산항에 비하여 광양하은 더 많은 항만물류배후단지가 지속 가능한 물동량 확보에관 세부적 전략을 추구하여야 한다. 전체 단순평균으로는 부산과 광양 440%이상의 물동량확보가 요구된다. 우리나라 항만 배후단지는 국제적환경에 맞는 시장 맞춤형 항만 배후단지를 조성하여 기업의 적극적 수용이 요구되고 있다. 항만 물류배후단지의 경쟁력 확보를 위하여 항만별 배후단지의 차별화가 이루어져야 한다.