• 대한기계학회논문집A
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• 제27권2호
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• pp.327-333
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• 2003

Most of shape defects in steel strip are originated from the structure of rolling mill itself. For instance, strip crown occurs when the work roll is deformed by the bending moment induced on roll chocks. To get rids of the shape defects, it is necessary to increase the stiffness of rolling mill. The structure change of back-up roll is one of alternative ways to increase the mill stiffness without facility revamping from 4 high mill to 6 high mill. In this research work, the new back-up roll was developed and can be used in any type of 4 high mill to reduce the strip shape defects. The developed back-up roll consists of sleeve, arbor and phase angle adjusting system for arbor. The circumference of arbor is specially machined to adapt the strip width change during rolling. The experimental cold rolling test was done to prove the effectiveness of newly developed back-up roll. The experimental rolling results show that the new back-up roll has more powerful performance in reducing the shape defects than conventional back-up roll. It was also found that the new back-up roll has higher stability for shape control. In addition to, the only sleeve surface needs to be reground and changed in most cases, so that the maintenance cost can be greatly reduced.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.138-140
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• 2002

We fabricated textured Ni substrate for YBCO coated film and evaluated the degree of texture in terms of rolling condition and annealing time. The substrate was compacted from pure Ni powder and reduced the thickness to 100 $\mu$m by rolling followed by heat treatment. As decreasing the thickness of substrate, it was observed that the non-uniform deformation such as ‘wave edge’ or ‘wave buckle’ developed locally on it, causing reduced texture. On the other hand, uniformly deformed substrate showed better cube texture indicating the FWHM of in-plane and out-of-plane of about $11^{\circ}$ ~ $14^{\circ}$. In addition, annealing at $1000^{\circ}C$ for 1~ 8 hr did not make a remarkable difference on the texture.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1453-1458
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• 2006

KTX Railway rolling stock wheel run its course to corrode, deteriorate and wear away through out the time. So it is natural that the performance and ability of wheel gets declined. The frequency characteristic analysis were accomplished to above trend and shock wave flow to wheels were examined. The result will be used to find Railway rolling stock wheel crack and maintenance method hereafter.

• 한국정밀공학회지
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• 제13권5호
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• pp.67-73
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• 1996

The necessity for more accurate automatic flatness control(AFC) system has increased of customers' requirement for cold rolled steel sheet. Therefore, many cold rolling mills replaced its AFC system with a measuring roll of the contact type form the non-contact type. In this paper. The performance of AFC system of contact type has been investigated under industrial conditions. It has two kinds of actuator: roll bender, spot cooling system. The test results are as follows: The more strip thickness is thick, the smaller the I value, and the more it is thin, the bigger the I value. And a complex distribution of strip tension was controlled, for example, not only a pocket wave but also a simple center wave and edge wave. Because the tension deviation is larger at acceler- ation speed and decelerationspeed than steady speed, AFC system of contact type is better to adopt over 50m/mim. AFC system reduces rapidly large flatness deviation. The maximum I value of strip has been decreased to 13 I, and sticker, defects caused by poor flatness, have been decreased about 60%.

• 대한기계학회논문집A
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• 제34권9호
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• pp.1299-1304
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• 2010

압연실험을 통해서 폭 방향 변형 편차가 존재하는 실리콘 강판의 가공파손을 고찰하였다. 폭 방향 변형 편차는 강판에 웨이브를 발생시키고 압연방향으로 소재의 에지 부위(혹은 센터 부위)에 인장(혹은 압축)을 준다. 실제 압연기에서 발생하는 웨이브를 실험실적으로 구현하기 위해서 공형롤을 설계 및 제작하였다. 실험에 사용한 소재는 고-실리콘(약 3%) 강판이다. 본 실험을 통해서 센터 웨이브에 의해 발생되는 에지 부위 인장응력이 가공파손에 가장 지배적인 요인이라는 것이 제시되었다. 센터 웨이브를 일으키는 폭 방향 변형 편차의 정도에 따라 에지 파손과 지그재그 형태의 시편 중심 절손을 유발한다는 결과도 도출하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.175.2-175
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• 2001

The strip profile and shape control is one of the most important technologies in Hot Rolling Mill System. Because the unbalance of strip´s shape and wave appearance between stands has a bad effect on Hot Rolling Mill System by making the inferior thickness, strip´s damage and so forth in factories. Many competition Plate Mill introduced shape control system, for example, pair cross-mill, work roll bender, which includes shape measuring instruments and shape control mathematical models. Shape meter, which is equipped for flatness, only does feedback control at the top of coil. And, for crown, we depend on initial setup value and there is no feedback control. Therefore we predict the shape of strip using rolling pressure, bender force and tension of inter-stand in ...

• 한국레이저가공학회지
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• 제9권1호
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• pp.25-29
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• 2006

This study aimed to investigate the change of mechanical properties with the rolling direction and shielding condition during laser welding of AZ31 magnesium alloy. AZ31 magnesium alloy sheets of 1mm thickness were welded using a continuous wave Nd:YAG laser with and without Ar shielding gas. The effect of Ar shielding gas and rolling direction on the mechanical properties were investigated using Vickers hardness, transverse-weld tensile. Porosity in the weld metals was investigated using an optical microscope. The experimental results showed that mechanical properties of AZ31 magnesium alloy laser welds were upgraded compared to those of base metal. Mechanical properties of AZ31 magnesium alloy laser welds were not substantially changed when Ar shielding gas was supplied.

• 대한조선학회논문집
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• 제29권1호
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• pp.61-70
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• 1992

본 연구에서는 파에 의한 선체의 횡요 운동에 대한 예측의 문제를 다루었다. 설계시 필요한 횡요 운동의 확률 밀도 함수를 구하기 위하여 FRK방정식을 이용하겠다. FRK방정식의 해는 평균화 과정을 통하여 근사적으로 구하였다. 이 근사해를 Dalzell[4]의 Simulation과 Roberts[14]의 계산 결과와 비교하여 그 정확도를 검토하여 보았다.

• 수산해양기술연구
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• 제47권3호
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• pp.248-256
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• 2011

The inherent efficiency of a ship would be prior to any other quality factors in ship's safety, because lack of it may give rise to a serious sea casuality even if it were a light mistake in operation. And the representative casualty comes from a deficiency of stability and an operating error combined would be capsizing. The Korean offshore large purseiner looks to have a structural weak point with small range of stability in spite of her big initial metacentric height, and have various type of roll reduction devices in order to cover up the defect. The aim of this study is to grasp for the roll reduction characteristics of the purseiner with bilge keel only and a stern keel additionally attached. The results are summarized as follows; The rolling angle of the model ship was increased in accordance with increase of the wave period and height, especially at close to the natural wave period of her, and the trends were more distinguished in the situation of bilge keel only installation than in the stern keel additionally installed. And stern keel has not noticeable effect on the reduction of the roll in the light ship condition, but has a little effect in full load condition.

• 한국항해항만학회지
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• 제28권5호
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• pp.353-358
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• 2004

ISSC 스팩트럼을 기초로 종래의 불규칙파가 아닌 새로울 과도 불규칙파를 설계하였다. 이 설계불규칙파를 장수조에서 조파기를 사용하여 발생시키고, 파고계와 6자유도계를 설치하여서 모형선의 횡동요 운동을 계측하였다. 모형선의 최대 횡동요각의 실험값과 이론값을 비교하여 단기 해상에서 발생 가능한 횡동요 피크치를 추정하는 방법에 관하여 검토하였다.