• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.17 no.2
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• pp.85-91
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• 1981

An equation was derived which describes the slip force that occurs at the casting of initial state due to unequilibrium with support bar weight, liquid metal, casting velocity, thickness, control roller, hydraulic motor and etc. The slip force equations are solved on the basis of velocity, gravity and thickness in casting ingot. In this paper the auther assumed that the other mechanisms are normal. The behaviour of slip force in many characteristics is calculated as a function of velocity, gravity and thickness with variation. The conclusion with this phenomena is reached that the present theory realistically predicts the growth of slip force in a flat plate ingot continuous casting machine.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.16-24
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• 2021

A laser-engineered net shaping (LENS) process is a representative directed energy deposition process. Deposition characteristics of the LENS process are greatly dependent on the process parameters. The present paper preliminarily investigates deposition characteristics of Inconel 718 superalloy on S45C structural steel using a LENS process. The influence of process parameters, including the laser power and powder feed rate, on the characteristics of the bead formation and the dilution in the vicinity of the deposited region is examined through repeated experiments. A processing map and feasible deposition conditions are estimated from viewpoints of the aspect ratio, defect formation, and the dilution rate of the deposited bead. Finally, an appropriate deposition condition considering side angle, deposition ratio, and buy-to-fly (BTF) is predicted.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.693-700
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• 2012

In this study, the Charpy impact test along with metallurgical observation was conducted to evaluate low temperature impact toughness of structural steel welds with different welding processes to find out the optimal welding process to guarantee the required impact toughness at low temperatures. The welding processes employed are shield metal arc welding (SMAW) and flux cored arc welding(FCAW), which are commonly used welding methods in construction. The Charpy impact test is a commercial quality control test for steels and other alloys used in the construction of metallic structures. The test allows the material properties for service conditions to be determined experimentally in a simple manner with a very low cost. To investigate the impact toughness at low temperatures of the steel welds, specimens were extracted from the weld metal and the heat affected zone. Standard V-notch Charpy specimens were prepared and tested under dynamic loading condition. The low temperature impact performance was evaluated based on the correlation between the absorbed energy and the microstructure. Analysis of the results showed that the optimal welding process to ensure the higher low temperature impact toughness of the HAZ and the weld metal is SMAW process using the welding consumable for steels targeted to low temperature use.

• Journal of Welding and Joining
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• v.4 no.2
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• pp.1-11
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• 1986

최근 개발된 구조용강을 대표하는 TMCP강재는 가속냉각법의 도입으로 그 적용범위가 과거 2-3 년 동안에 거의 모든 구조용 강재에 확산되었다. 이와 같은 확대 적용에는 생산비를 절감하려는 Steel Marker의 노력과 가속 냉각처리된 강재에 대한 fabricator 측의 긍정적인 반응이 크게 작 용했는데, 이는 이 강재가 같은 우수한 기계적 성질 및 용접성에 기인하고 있다. 그러나 fabricator 측은 가속냉각된 강재에 대해 익숙치 않으므로 가속냉각된 강재와 기존의 강재에 대 한 차이점을 충분히 인식하고, 사용할 때 예상되는 문제점에 대해서는 강재 주문시 Steel Maker 측과 충분한 토의를 거친후 구매하는게 바람직하다고 하겠다. 이로 인하여서만이 fabricator측은 가속냉각된 강재의 우수성을 백분 활용할 수 있을 뿐만 아니라 제작시 야기될 문제를 미연에 방 지할 수 있을 것이다.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.2
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• pp.56-67
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• 1987

박판연속주조법은 용강으로부터 직접 제품을 제조하는 방법으로써 최근 에너지 절약, 신소재개발의 측면에서 주목되어지고 있다. 쌍로울식 연속주조법은 두개의 로울러 사이 에 있어서 응고완료점의 제어가 극히 중요하다. 본 논문에서는 경제고정법에 의하여 액 상역과 고상역을 동시에 해석하는 방법을 제안하여 이론해석의 결과를 실험결과와 비교 한다. 또한 주조조건에 영향을 미치는 로울러 각속도, 로울러간의 간격이 응고형상에 미치는 영향을 밝히며 응고완료점이 로울러출구에 존재하는 주조조건을 구하여 주조가능 조건을 검토한다.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.03a
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• pp.70-73
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• 1998

본 연구에서는 광양제철소에서 철광석과 코크스를 이용하여 용선을 생산하는 고로공장과 이러한 용선을 용강으로 변화시키는 제강공장지역을 운행하는 기관차 및 TLC (Torpedo Ladle Car)의 용선 수성작업을 분석하여 기관차 및 TLC의 적정댓수를 산정하고, 운행 패턴의 변화에 따른 대안들을 검토하였다. 시뮬레이션은 AUTOMOD II를 이용하여 수행하였으며, 시뮬레이션에 이용되는 관련 기준 및 운행 패턴을 수집하여 확정하고, 실적치의 분포를 추정하였다. 시뮬레이션의 결과는 현장 전문가들의 이해를 높이기 위아여 Animation을 통하여 가시화하였다.

• Journal of the KSME
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• v.28 no.4
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• pp.401-407
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• 1988

해수 중에 있는 구조용강에 음극방식을 실시했을 때의 피로균열진전 특성을 공기 중에서와 비교 하면서 정리하였으며 또한 몇 가지 영향인자들의 역할에 대해서도 기술하였다. 그러나, 이러한 특성들은 아직까지 그 정확한 메커니즘이 규명되지 못하고 있으며, 특히 균열선단에서의 소성 거동이 부식분위기나 수소분위기에서 어떻게 변화하는가 하는 문제에 대해서는 앞으로도 많은 연구가 이루어져야 할 것이다. 응력조건과 부식조건이 동시에 적용될 때, 재료의 거동을 직접 적으로 해석하기 어려운 경우가 많으며, 따라서 관련되는 많은 영향인자들의 역할에 대한 상세한 정보들이 요구되고 있으며, 또한 관련 정보들을 유기적으로 결합시키는 이론적인 근거를 마련 해야 할 필요가 있다.

• Resources Recycling
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• v.22 no.1
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• pp.36-41
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• 2013

LF slag is formed by EAF carryover slag and slag former(such as lime, dolomite) put into the ladle during the tapping molten metal. After LF process, continuous casting is started when molten steel is sent from ladle to tundish through bottom nozzle of ladle. Conventionally, remained molten slag and steel in ladle are poured into a slag port and they are transferred to a slag yard and then recycled. In this study, we investigated about recycling of molten LF slag residue(including Fe residue to reuse) which is made in steelmaking process. As a result, lime usage was decreased about 2.2~3.2 kg/steel-ton and also molten steel yield rate was increased about 0.3 ~ 0.5 percent point.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.8
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• pp.56-63
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• 2020

The heat transfer phenomenon in the vicinity of the irradiated region of a focused laser beam of a DMT process greatly affects both the deposition characteristics of powders on a substrate and the properties of the deposited region. The goal of this paper is to investigate the heat transfer characteristics of a single bead deposition of Inconel 718 powders on S45C structural steel using a laser-aided direct metal tooling (DMT) process. The finite element analysis (FEA) model with a Gaussian volumetric heat flux is developed to simulate a three-dimensional transient heat transfer phenomenon. The cross-section of the bead for the FEA is estimated with an equivalent area method using experimental results. Through the comparison of the results of the experiments and those of the analysis, the effective beam radius of the bottom region of the volumetric heat flux and the efficiency of the heat flux model for different powers and travel speeds of the laser are predicted. From the results of the FEA, the influence of the power and the travel speed of the laser on the creation of a steady-state heat transfer region and the formation of the heat-affected zone (HAZ) in the substrate are investigated.

• Resources Recycling
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• v.26 no.6
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• pp.45-49
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• 2017

Most Waste slurry is produced in the process of silicon manufacturing for semiconductor industry, containing silicon (Si) and silicon carbide (SiC). Waste slurry is simply stored with solidifying by cement or buried. On the other hand, it was suggested in this study that the waste slurry should be used for heating source as supplementary material in steel making process. The waste slurry was refined and pulverized, which was recycled into SiC-based sludge briquette. Chemical composition for SiC-based sludge briquette was analyzed and the feature of heating source was observed in accordance with the injection time and input amount. As a result, SiC-based sludge briquette in terms of low cost and high efficiency had an effect on increasing liquid steel temperature in steel making plants.