• 한국안전학회지
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• 제27권5호
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• pp.16-21
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• 2012

The purpose of this study is to try to find the risk of roller(mixing mill) in working site. In order to achieve the purpose, accident analysis and survey was carried out. This analysis revealed that average of loss days is 334.3 by roller jamming accident and 229.2 by other causes. It means jamming accident entails serious bodily harm. According to our research, we realize that most of rollers have some risk of the jamming accidents. It is simply because the roll gap in the roller is not more than 10cm. It also does not meet minimum distance so as to avoid the risk for jamming accident by KS. Furthermore, 28% of rollers have only one switch and 40% of rollers have two switches operating emergence stop equipment so as to reduce the risk of jamming accidents. Therefore, we presume that it is very difficult to turn on the switch of emergence stop equipment when they confront the accident because most of engineers are working alone.

• 제어로봇시스템학회논문지
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• 제15권6호
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• pp.634-640
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• 2009

The plate manufacturing processes are composed of the reheating furnace, finishing mill, cooling process and hot leveling. The finishing rolling mill (FM) as a reversing mill has produced the plate steel through multiple pass rolling. The automatic gauge control (AGC) is employed to maintain the thickness tolerance. The high grade products are forming greater parts of the manufacturing and customers are requiring strict thickness margin. For this reason, the advanced AGC method is required instead of the conventional AGC based on the PI control. To overcome the slow response performance of the conventional AGC and the thickness measurement delay, a fuzzy AGC based on the thickness deviation and its trend is proposed in this paper. An embedded controller with the fuzzy AGC has been developed and implemented at the plate mill in POSCO. The fuzzy AGC has dynamically controlled the roll gap in real time with the programmable logic controller (PLC). On line tests have been performed for the general and TMCP products. As the results, the thickness deviation range (maximum - minimum of the inner plate) is averagely from 0.3 to 0.1 mm over the full length. The fuzzy AGC has improved thickness deviation and completely satisfied customer needs.

• Journal of Advanced Marine Engineering and Technology
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• 제34권2호
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• pp.303-309
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• 2010

유한요소법을 통하여 유성압연기(planetary rolling mill)에 의한 동관 압연공정을 연구하였다. 이 압연은 3개의 롤에 의해 만네스만 공법으로 동관을 성형하는 공정이고, 냉간가공으로 시작하여 열간가공으로 종료되며, 기존의 압출방식에 비해 공정의 단축과 원가 절감의 장점을 갖고 있다. 압연공정은 다양하고 복합적인 공정변수 들을 포함하고 있고, 각각의 변수들은 성형결과에 영향을 미친다. 그러므로 동관압연의 모든 공정변수가 고려되어져야 한다. 동관 압연공정은 성공적으로 시뮬레이션 되었고 최적의 압연조건을 결정하는데 유용할 것이다.

• 한국재료학회지
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• 제32권3호
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• pp.161-167
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• 2022

A cold roll-bonding process is applied to fabricate an AA6061/AA5052/AA6061/AA5052 layered sheet. Two AA6061 and one AA5052 sheets of 2mm thickness, 40mm width and 300mm length are alternately stacked, then reduced to a thickness of 2.0 mm by multi-pass cold rolling after surface treatment such as degreasing and wire brushing. The rolling is performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 400 mm at a rolling speed of 6.0 m/sec. The roll-bonded AA6061/AA5052/AA6061/AA5052 layered sheet is then hardened by natural aging (T4) and artificial aging (T6) treatments. The microstructure of the as-roll bonded and the age-hardened Al sheets was revealed by SEM observation; the mechanical properties were investigated by tensile testing and hardness testing. After T4 and T6 aging treatment, the specimens had a recrystallization structure consisting of coarse equiaxed grains in both AA5052 and AA6061 regions. The as-roll-bonded specimen showed a clad structure in which the hardness of AA5052 regions was higher than that of AA6061 regions. However, after T4 and T6 aging treatment, specimens exhibited different structures, with hardness of AA6061 regions higher than that of AA5052 regions. Strengths of T6 and T4 age-treated specimens were found to increase by 1.55 and 1.36 times, respectively, compared to the value of the starting material.

• 한국재료학회지
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• 제29권6호
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• pp.392-397
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• 2019

A cold roll-bonding process is applied to fabricate an AA6061/AA5052/AA6061 three-layer clad sheet. Two AA6061 and one AA5052 sheets of 2 mm thickness, 40 mm width, and 300 mm length are stacked, with the AA5052 sheet located in the center. After surface treatment such as degreasing and wire brushing, sample is reduced to a thickness of 1.5 mm by multi-pass cold rolling. The rolling is performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 400 mm at rolling speed of 6.0 m/sec. The roll bonded AA6061/AA5052/AA6061 complex sheet is then hardened by natural aging(T4) and artificial aging(T6) treatments. The microstructures of the as-roll bonded and age-hardened Al complex sheets are revealed by optical microscopy; the mechanical properties are investigated by tensile testing and hardness testing. After rolling, the roll-bonded AA6061/AA5052/AA6061 sheets show a typical deformation structure in which grains are elongated in the rolling direction. However, after T4 and T6 aging treatment, there is a recrystallization structure consisting of coarse equiaxed grains in both AA5052 and AA6061 sheets. The as roll-bonded specimen shows a sandwich structure in which an AA5052 sheet is inserted into two AA6061 sheets with higher hardness. However, after T4 and T6 aging treatment, there is a different sandwich structure in which the hardness of the upper and lower layers of the AA6061 sheets is higher than that of the center of the AA5052 sheet. The strength values of the T4 and T6 age-treated specimens are found to increase by 1.3 and 1.4 times, respectively, compared to that value of the starting material.

• 공업화학
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• 제3권1호
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• pp.81-87
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• 1992

폴리에틸렌에 아라미드단섬유를 보강시킨 복합재료를 roll mill을 사용하여 제조하였다. 섬유배향과 물리적 성질의 이방성을 주사전자현미경과 인장시험기로, 유변특성을 RDS 를 사용하여 측정하였다. 섬유의 배향은 roll 작업으로 어느 정도 이루어 졌으며, 섬유 loading 이 증가할수록 기계적강도의 이방성도 증가하였다. 섬유 loading 에 따른 복합점도의 상승은 저주파수 영역에서 뚜렷이 관찰되었으며, 특히 섬유 loading 이 작은 범위에서 현저하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.163-172
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• 2004

A fast, accurate model for calculating roll gap variables are critical to the implementation of computer based automation systems for cold rolling mills. Based on the work of Fleck and Johnson, rollgap simulator with non-circular arc model was developed using the influence function. This developed model is capable of predicting values of force, torque and slip which can be applied over the wide range of rolling conditions including cold rolling/DR/temper mill with high execution speed. Friction coefficient was obtained as a function of operation conditions through analyzing measured data. After combination of rollgap simulator with production strategy, draft schedule for No.3 RCM (Reversible Cold Rolling Mill) in Incheon works of Dongbu Steel was developed. This draft schedule will be installed in the setup computer of No.3 RCM replacing old Hitachi model.

• 한국수산과학회지
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• 제46권2호
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• pp.139-146
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• 2013

Surimi products are among the most prominent seafoods in Korea. Together with fish meat, wheat flour is a major ingredient in the preparation of surimi products. Rice flour, however, can be an effective ingredient in enhancing the rheological characteristics of surimi products. In this study, we evaluated the potential of rice flour as an agent to replace wheat flour in surimi products. The effects of rice flour milling types and addition methods on the rheological and sensory properties of surimi products were investigated. Among different addition methods, the surimi product containing non-treated rice flour showed better gel strength and sensory properties than products containing paste (1:1.3 rice flour/water, w/v) and steamed paste (steamed at $100^{\circ}C$ for 30 min). According to the gel strength results for surimi products with added roll-mill (40 mesh) and jet-mill (180 mesh) rice flours, the roll-mill rice flour shows good potential as a replacement for wheat flour. When considering gel strength and sensory properties, an effective amount of rice flour to add was 10-15% (w/w). In conclusion, the rheological and sensory properties of surimi products containing rice flour were comparable with those of a premium commercial surimi product. Therefore, rice flour might be an effective alternative to wheat flour for premium surimi products.

• 한국재료학회지
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• 제26권7호
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• pp.388-392
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• 2016

A cold roll-bonding process was applied to fabricate an AA1050/AA6061/AA1050 laminate complex sheet. Two AA1050 and one AA6061 sheets of 2 mm thickness, 40 mm width and 300 mm length were stacked up after surface treatment that included degreasing and wire brushing; material was then reduced to a thickness of 3 mm by one-pass cold rolling. The laminate sheet bonded by the rolling was further reduced to 1.2 mm in thickness by conventional rolling. The rolling was performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 210 mm. The rolling speed was 5.0 m/sec. The AA1050/AA6061/AA1050 laminate complex sheet fabricated by roll bonding was then hardened by natural aging T4) and artificial aging (T6) treatments. The microstructures of the as-roll bonded and the age hardened Al complex sheets were revealed by optical microscope observation; the mechanical properties were investigated by tensile testing and hardness testing. The strength of the as-roll bonded complex sheet was found to increase by 2.9 times compared to that value of the starting material. In addition, the hardness of the complex sheets increased with cold rolling for AA1050 and age-hardening treatment for AA6061, respectively. After heat treatment, both AA1050 and AA6061 showed typical recrystallization structures in which the grains were equiaxed; however, the grain size was smaller in AA6061 than in AA1050.

• 한국재료학회지
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• 제26권3호
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• pp.154-159
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• 2016

A roll-bonding process was applied to fabricate an AA1050/AZ91/AA1050 laminate complex sheet. Two AA1050 and one AZ91 magnesium sheets of 2 mm thickness, 30 mm width and 200 mm length were stacked up after surface treatment that included degreasing and wire brushing; material was then reduced to a thickness of 3 mm by one-pass cold rolling. The laminate sheet bonded by the rolling was further reduced to 2 mm in thickness by conventional rolling. The rolling was performed at 623K without lubricant using a 2-high mill with a roll diameter of 210 mm. The rolling speed was 15.9 m/min. The AA1050/AZ91/AA1050 laminate complex sheet fabricated by roll bonding was then annealed at 373~573K for 0.5h. The microstructure of the complex sheets was revealed by electron back scatter diffraction (EBSD) measurement; the mechanical properties were investigated by tensile testing and hardness testing. The strength of the complex sheet was found to increase by 11 % and the tensile elongation decreased by 7%, compared to those values of the starting material. In addition, the hardness of the AZ91 Mg region was slightly higher than those of the AA1050 regions. Both AA1050 and AZ91 showed a typical deformation structure in which the grains were elongated in the rolling direction; however, the mis-orientation distribution of grain boundaries varied greatly between the two materials.