• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.1
• /
• pp.34-43
• /
• 1994

In order to improve thickness profile of cold rolled steel strip, a computer simulation and actual cold rolling experiments on a 4-high tandem cold mill were carried out. In this study, tapered barrel end at top work roll and incurved barrel body at bottom work roll were examined for reducing edge drop and threading of stripe. Also, the most effective stand of tandem cold mill and magnitude of optimal taper crown at several stand were investigated under a typical rolling condition. From actual rolling experiments, it was verified that thickness deviation over strip width could be improved up to 1.06% by applying tapered and incurved work roll only at the second and up to 0.89% by applying them at both the second and the third stand.

• Nuclear Engineering and Technology
• /
• v.8 no.3
• /
• pp.151-157
• /
• 1976

The strain ageing behavior of cold-worked Zircaloy-4 in vacuum was studied as a function of deformation temperature and oxygen content from 1143 ppm to 3500 ppm 0. Strain ageing occured in the temperature range between 200 and 45$0^{\circ}C$ for the 0 to 10% cold-worked Zircaloy-4, decreasing with increasing amount of cold work. This suppression of strain ageing by cold work is considered to be due to the trapping of oxygen atoms by cold work-produced defects. It has been found that the maximum strain ageing stress in cold-worked Zircaloy-4 is proportional to the square root of oxygen content.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.5
• /
• pp.1149-1157
• /
• 1995

The research for variation of coolant film thickness and separating force has been investigated following the examination for friction profile of work roll and roughness change of strip surface in rolling mill producting actual commercial products. The obtained results are as follows ; (1) Coolant film thickness in cold rolling has been increased relative to the circumferential velocity of work roll, and formation of coolant films has decreased with the smaller diameter of work roll. (2) Separating force is related to the formation of coolant film, and large separating force is needed to the formation of coolant film but it is constant after formation of appropriate film. (3) Wear and roughness alleviation of work roll is larger in bottom-roll than in top-roll on cold surface is larger in the direction of width than in roll direction, and changes of roughness and strip surface hardness rarely occurred after 3 passes.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.23 no.6
• /
• pp.616-621
• /
• 2003

There are various Non-Destructive Evaluation (NDE) techniques used for measurement of residual stresses in material, such as magnetic methods, X-ray diffraction, Ultrasonic velocity measurement etc. The capabilities, applications and limitations of these techniques for evaluation of cold work/plastic deformation were studied and compared. Mild steel plates were subjected to different degree of cold deformation and were analyzed by Magneto-mechanical Acoustic Emission (MAE), Barkhausen Noise (BN) and magnetic properties (hysteresis loop parameters analysis). Further, these specimens were analyzed by X-ray diffraction and ultrasonic velocity measurements. The microhardness measurement and microstructure studies of these cold worked plates were also carried out. The results of all these studies and comparison of different techniques are discussed in this paper.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.2
• /
• pp.281-285
• /
• 2008

Die hobbing is one of the dieblock manufacturing methods of cold forging die, which makes the upper side of dieblock indented using master punch, hobb to produce impression not using cutting work. SKD11, alloy tool steel was used as the material of dieblock and stainless sheet metal was used as product material in cold forging work. The life span of the die was 6,000 strokes. In this research, the material of dieblock was changed into SKH51, the high speed tool steel and the product material was S45C, the carbon steel in the cold forging work. The life span of the die was 21,000 strokes, which is 350% of the life span of the die using the former method.

• Computers and Concrete
• /
• v.22 no.3
• /
• pp.319-326
• /
• 2018

RC (Reinforced Concrete) members are always subjected to loading conditions and have construction joints when constructed on a big scale. Service life for RC structure exposed to chloride attack is usually estimated through chloride diffusion test in sound concrete, however the test is performed without consideration of effect of loading and joint. In the present work, chloride diffusion coefficient is measured in concrete cured for 1 year. In order to evaluate the effect of applied load, cold joint, and mineral admixtures, OPC (Ordinary Portland Cement) and 40%-replaced GGBFS (Ground Granulated Blast Furnace Slag) concrete are prepared. The diffusion test is performed under loading conditions for concrete containing cold joint. Investigating the previous test results for 91 days-cured condition and the present work, changing diffusion coefficients with applied stress are normalized considering material type and cold joint. For evaluation of service life in RC continuous beam with 2 spans, non-linear analytical model is adopted, and service life in each location is evaluated considering the effects of applied stress, cold joint, and GGBFS. From the work, varying service life is simulated under various loading conditions, and the reduced results due to cold joint and tensile zone are quantitatively evaluated. The effect of various conditions on diffusion can provide more quantitative evaluation of chloride behavior and the related service life.

• Journal of Sasang Constitutional Medicine
• /
• v.33 no.1
• /
• pp.1-21
• /
• 2021

Objective The purpose of this study was to examine the correlation between the Cold-damage Six-meridian disease of Qibo (岐伯六經病證) and Sasang Constitutional Symptomatology (四象體質病證), presented in Discourse on the Origin of Eastern Medicine (醫源論) of Longevity and Life Preservation in Eastern Medicine (Donguisusebowon, 東醫壽世保元). Method The process of development from Cold-damage Six-meridian disease of Qibo (岐伯六經病證) to Six Meridians Physical Symptoms and Medicines (六經形證用藥) in the chapter Cold(寒門) of the Treasure Mirror of Eastern Medicine (Donguibogam, 東醫寶鑑) was investigated. And the correlation between Six Meridians Physical Symptoms and Medicines (六經形證用藥) and Sasang Constitutional Symptomatology (四象體質病證) was considered. Results and Conclusions 1. The Cold-damage Six-meridian disease of Qibo (岐伯六經病證) in the chapter Heat Treatise (熱論篇) of Basic Questions (素問) had evolved into Six Meridians Physical Symptoms and Medicines (六經形證用藥) in the chapter Cold(寒門) of the Treasure Mirror of Eastern Medicine (Donguibogam, 東醫寶鑑) through Book for Life Saving (Huorenshu, 活人書), a work of Zhu Gong (朱肱), Six Books on Cold Damage disease (Shanghanliushu, 傷寒六書), a work of Tao Hua (陶華) and Introduction to Medicine (YixueRumen, 醫學入門), a work of Li Chan (李梴). 2. The correlation between the Cold-damage Six-meridian disease of Qibo (岐伯六經病證) and Sasang Constitutional Symptomatology (四象體質病證) can be analyzed and understood through Six Meridians Physical Symptoms and Medicines (六經形證用藥) in the chapter Cold(寒門) of the Treasure Mirror of Eastern Medicine (Donguibogam, 東醫寶鑑). 3. Greater Yang meridian disease of Qibo (岐伯) is related to Soyangin early stage of Lesser-Yang Wind-Injury symptomatology and Soyangin early stage of Chest-Heat symptomatology, Yang Brightness meridian disease and Greater Yin meridian disease to Taeeumin Liver-Heat symptomatology, Lesser Yin meridian disease to Soyangin Chest-Heat symptomatology, Lesser Yang meridian disease to Soyangin early stage of Lesser-Yang Wind-Injury symptomatology and Reverting Yin meridian disease to Soeumin Reverting Yin symptomatology of Greater Yang disease.

• Transactions of the Korean hydrogen and new energy society
• /
• v.14 no.3
• /
• pp.207-216
• /
• 2003

By using the electrochemical method, the relation between the deformation and the geometrical shape, and the effect of cold work on hydrogen absorption-desorption cycling in palladium were investigated, In order to study this problem, four kinds of the Pd specimens used were plates and bars as cold worked and annealed states. As results, it is found that the deformation of thickness direction in the palladium plates increased whereas other lateral directions decreased. But the palladium bars showed the same deformation ratio in all directions because of uniform distribution of the $\beta$ phase. Grains in the plate specimens were greatly deformed after hydrogenation cycling whereas grains in the bar specimens were pulverized. Also, deterioration of the hydrogen absorption rate of the bar specimen was larger than the plate specimen. And the effect of cold work on hydrogen absorption capacity was relatively small.

• Nuclear Engineering and Technology
• /
• v.53 no.6
• /
• pp.1909-1923
• /
• 2021

We experimentally investigated the effects of thermal aging and cold work on the microstructure, mechanical properties, and primary water stress corrosion cracking (PWSCC) initiation time for Alloy 182 welds. The effects of thermal aging and cold work on the PWSCC initiation time of Alloy 182 were modeled based on the plastic energy concept and the PWSCC initiation data of this study and previous reports by considering censored data. Based on the results, it is estimated that the PWSCC resistance of the Alloy 182 weld firstly increases and then decreases with thermal aging time when the applied stress is kept constant.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2002.05a
• /
• pp.39-39
• /
• 2002

In order to improve wear and fatigue resistance of the structural materials, especially cold work roller for 304 stainless steel, an eco-super-finishing and surface hardening treatment using ultrasonic vibration energy was developed and applied to the SKD-ll roller. The eco-super-finishing machine was designed and fabricated by DesignMecha Co, by its own technology. It was observed that the surface roughness, hardness and residual stress were changed from $Ra{\;}={\;}O.25\mu\textrm{m}$, Hv=710 and ${\sigma}$={\;}+400{\;}MPa{\;}to{\;}Ra{\;}={\;}0.165\mu\textrm{m}$, Hv = 1200 and ${\sigma}=-610$ MPa after 20 KHz micro-cold forging, which means almost equal to the 300 % improvement of life-time.