• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.29-30
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• 2007

내지문 강판은 가전재 내외판으로 사용되며 주로 전기아연도금강판을 이용한다. 그러나 최근 일부 가전사에서는 전기아연도금강판 대신 용융아연도금강판으로 일부 대체가 되고 있으며 특히 분체도장을 하는 외판에서 용융아연도금강판의 수요가 늘어나게 되었다. 이에 본고에서는 내지문 용융도금강판 개발을 위해 분체도장물성이 우수한 내지문 수지를 사용하여 기존 전기도금강판과 비교 테스트를 하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.2
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• pp.192-199
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• 2002

In continuous galvanizing process, the mass of zinc deposited and its distribution are controlled by the air pressure, effective distance from the air knife nozzle to the steel strip surface and line speed. Coating defects are resulted from the unbalance of these control factors and the inaccuracy of coating equipments. This paper investigates the main cause of coating deviation and a new air knife system for control of coating thickness was developed. We investigate dynamic pressure variation by air knife types. It is found that the coating deviation is caused by the unbalance of dynamic pressure, the irregularity of strip position, and the strip vibration. Formulating a useful coating model by using present working condition, an optimal working condition is suggested. The productivity and coating quality are improved by applying the result of this research at the shop floor.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.358-363
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• 2003

Spot welded structure is operated in diverse situation because of temperature, humidity and precipitation. In addition factors of environmental pollution such as acid rain, that courses corrosion, have the tendency to increase, But spot welded structure strength is affected by dampness and environment temperatures. Therefore, it is important to evaluate effect of temperature of spot welded part, In this study, the strength distribution of spot welded plates is evaluated about the environmental temperature of zine coated steel plates and test is conducted with welded part immersed in distilled and synthetic sea water. Specimens are immersed into water for 10, 100, 500 and 1000hours to evaluate the effects of water immersion time on tensile-shear strength under the conditions of -40, 0, 20 and $50^{\circ}C$. Strength is evaluated by tensile-shear test. The conditions of spot welding are 240kgf electrode force, 10KA welding current with 0 and 5mm clearance. From this study, spot welded specimens with clearance have lower tensile-shear strength in the distilled water or synthetic sea water comparing with spot welded specimens without clearance. And they have lower tensile-shear strength under $-40^{\circ}C$ and over $50^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.747-754
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• 1988

High strength steels (HS) of dual phase and monogalvanized steel sheets (GA ; plated plane, GAB ; bare plane0 were used to investigate the fatigue strengths of four kinds of single-spot-welded joint specimen under tensile-shear repeated load. The specimen is classified as the same mating metal specimen (HS*HS, GA*GAB) and different mating metal specimen (HS*GA, HS*GAB). Some of the results are ; (1) Static tensile load of single-spot-welded joint specimens is proportional to tensile strength of metal and rigidity of mating metal sheet. (2) Fatigue life of HS*HS specimens increased about 20% longer than that of GA*GAB specimens in low cycle range. (3) In different mating metal specimens, the fatigue life of HS*GA specimens increased about 84% more that of HS*HS specimens in high cycle range.

• Journal of Adhesion and Interface
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• v.4 no.3
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• pp.1-8
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• 2003

Adhesion between rubber compound and copper-film-coated steel plate (abbreviated hereafter as copper film plate) with different thicknesses of copper film was investigated. Two different methods were employed for the preparation of the copper film plates: a substitution plating of preelectroplated zinc with copper ion and a vacuum sputtering of copper on steel plate. Adhesion strength of the copper film plates with rubber compounds was largely dependent upon the thickness of copper film, regardless of their preparation methods. The copper film plates with thinner thickness than 75 nm showed high adhesion comparable to brass, while those with thicker copper film showed poor adhesion due to excessive growth of copper sulfide at adhesion interface.

• Journal of ILASS-Korea
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• v.6 no.1
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• pp.44-51
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• 2001

The distributions of the SMD and behavior of 2% $NH_4H_2PO_4$ spray discharged from a fan-spray twin fluid type nozzle are measured and observed. The spray characteristics, according to the variation in the applied voltages, are demonstrated using the PMAS (particle Motion Analysis System) and the CCD camera, respectively. The preliminary experiments are executed to select an optimum condition for solidifying a galvanized coating layer in the uncharged condition before carrying out the main experiments. The liquid and air pressure of $0.07kgf/cm^2\;and\;0.15kgf/cm^2$ can be considered the optimum conditions to use in the main experiment. As the applied voltage increases, the frequent range of relatively large droplets diminishes. Thus, the distributions of drop diameter in the charged spray are more uniform than these in the uncharged condition. This is explained by recognizing that repulsive forces among droplets with the charges of the same sign cause them to be uniform.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.44-48
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• 1993

산업현장에서부터 실생활용품에 이르기까지 각종판재를 소재로하여 제작하는 가공품은 종류나 수가 매우 많다고 할수 있다. 이러한 제품들을 제작 하기 위해 여러단계의 성형 공정을 거치게 되며 원만한 성형공정 을 수행하기 위한 적절한 판재성형 제어방법으로써 다이곡률 반경의 변화나 블랭크홀딩가압정도의 부분적 변화로 드로잉률을 향상시키는 방법도 있으나 이보다 판재의 성형공정 제어방법에서 공구사이 상하에 비드 를 설치하여 판재를 성형할 경우 성형공정후 제품의 두께 분포가 비교적 균일해지고 드로잉의 마찰저항을 부분적으로 증가시키며 판재성형중 미끄럼 저항의 균형을 이루어 성형시킬 판소재가 절감도며 또한 성형중 주름을 억재하여 드로잉률을 향상시킨다. 다른 방법에 비해 비드는 설차가 간단해서 적절한 형상의 bead set을 선정하여 산업현장에서 실제 사용하고 있으며 또한 소재가 비드를 통과한후 탄성역에서 소성역으로 전환되기에 성형공정 이후 스프링백 현상으로인한 제품형상의 치수가 변하는 현상을 방지하는 효과도 기대할수 있다. 따라서 본 연구에서는 자동차용판재인 아연도금피막 강판으로 실험한 결과와 비드 이론식을 고찰해 보고자 한다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2001.11a
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• pp.124-129
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• 2001

점 용접부는 응력상태가 복잡하고, 피로균열은 판 두께, 너겟 직경, 용접 타점수, 부하 방식 등의 역학적인 인자와 재질, 화학성분, 표면 상태 등의 재료적인 인자, 그리고 용접전류, 가압력, 통전 시간등의 용접적인 인자의 영향을 동시에 받으며 3차원적으로 성장하므로 균열 성장 모드는 항상 혼합보드이고 균열이 박판 내면에서 발생. 성장하므로 검출이 곤란하여 균열 성장의 해석 및 예측이 어렵다/sup 1)/. 따라서 비접촉, 실시간, Whole-field, 레이저 파장 단위까지 측정이 가능하여 기존의 방법들의 문제점을 극복할 수 있고, 반도체와 같은 소형의 제품뿐만 아니라 기존에 측정하지 못했던 초고온, 대형 구조물의 변형도 정확하게 측정을 할 수 있는 ESPI법을 이용하여 일반가전 제품, 자동차 건축용에 많이 사용되고 있는 아연도금강판(SGCC)을 선택하여 단일 용접조건으로 점용접의 피치를 변화시켜 시험편을 제작하고 면외변위를 다각도로 측정하여 그 가능성을 검증하고자 한다.(중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3260-3268
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• 2009

A test apparatus has been fabricated to simulate chemical effect on head loss through a strainer in a pressurized water reactor (PWR) containment water pool after a loss of coolant accident (LOCA). Tests were conducted under condition of same ratio of strainer surface area to water volume between the test appratus and the containment sump. A series of tests have been performed to investigate the effects of spray, existence of calcium-silicate with tri-sodium phosphate (TSP), and composition of materials. The results showed that head loss across the chemical bed with even a small amount of calcium-silicate insulation instantaneously increased as soon as TSP was added to the test solution. Also, the head loss across the test screen is strongly affected by spray duration and is increased rapidly at the early stage, because of high dissolution and precipitation of aluminum and zinc. After passivation of aluminum and zinc by corrosion, the head loss increase is much slowed down and is mainly induced by materials such as calcium, silicon, and magnesium leached from NUKONTM and concrete. Furthermore, it is newly found that the spay buffer agent, tri-sodium phosphate, to form protective coating on the aluminum surface and reduce aluminum leaching is not effective for a large amount of aluminum and a long spray.