• Transactions of Materials Processing
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• v.17 no.4
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• pp.272-277
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• 2008

A constitutive equation of the electrical steel strip used for a raw material of transformer is proposed. The stress-strain behavior of electrical steel strip is quite different from that of common carbon steel and/or alloy steel. A series of tensile tests were performed with the specimens made from cold rolled strip. Several thicknesses of the strip were produced by a two-high (with upper and lower rolls) cold rolling pilot mill as reduction ratio increases from 10% to 90%. Its initial thickness of the strip was 2.5mm. Tensile specimens are cut out from the cold rolled strips. Mechanical properties of the steel are examined through rolling direction. Ramberg-Osgood model and the proposed equation are combined to describe the total behavior of stress-strain including instability region. The stress-strain curves calculated from the present constitutive equation are compared with those from experimentally obtained at each test condition of reduction ratios of specimen. Results show that the predicted stress-strain curves are in overall in a good agreement with measured ones.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.254-257
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• 2002

As the large Coolant amount used of a machine holds mass serious trouble recently, an environment pollution is increased, and a machine is conquering large specific gravity in an empty cost plane. It is the stage that must reexamine the parts washing that processing is later with this current way or a problem of a liquid waste treatment back. The environmental problems by using coolant demanded the new cooling methods. As one of them, the studies on the grinding with compressed cold air and oil mist have been done. The cooling method using compressed cold air was effective through going down the temperature of compressed air supplied below -$25^{\circ}C$ and increasing the amount of compressed cold air, but had not enough cooling effect due to the low performance of lubrication. Therefore, the cooling methods using oil mist newly were suggested. This method can satisfy both cooling effect and lubrication with only small amount of coolant, also have the benefit in the point of decreasing the environmental pollution. This paper focused on analyzing the grinding characteristics of the cooling method using oil mist. The grinding test according to compressed cold air and oil mist supply direction were done.

• Journal of the Korean Society of Food Culture
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• v.10 no.2
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• pp.89-95
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• 1995

Three potato cultivars, Sumi,Daejima and Namjak, were prepared as slices. They were dipped in distilled water for 20 seconds. The potato slices were packed in polyethylene bags and stored at $5^{\circ}C$. Browning degree, total phenol and chlorogenic acid contents and polyphenol oxidase (PPO) activity were measured. And the correlation analysis of browning parameters were conducted. The results were as follows. There were increase in browning degree, phenolic content and PPO activity during cold storage of potato slices with different cultivars. Among three cultivars, Sumi showed the highest browning degree, phenolic content and PPO activity and also showed the highest % increse of browning and PPO activity during cold storage. On the contrary, Daejima was the lowest. But Daejima showed the highest % increase in phenolic contents during cold storage. With Sumi, browning degree was significantly correlated with PPO activity and phenolic contents (p<0.05). With Daejima and Namjak, a significant correlation was found between browning degree and PPO activity (p<0.05). From the above results, enzymatic browning reactions of potato slices and factors affecting them were dependent on cultivar. Among the tested three cultivars, Daejima showed the lowest browning degree during cold storage and thus seems to be desirable for minimal processing.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.8-15
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• 2021

Cold forging is a method in which molding is performed at room temperature. It has a high material recovery rate and dimensional precision and produces excellent surface quality, and it is mainly used for the production of bolted or housing products. The lifespan of cold forging molds is generally determined by the wear of the mold, plastic deformation of the mold, and fatigue strength. Cold forging molds are frequently damaged due to fatigue destruction rather than wear and plastic deformation in a high-temperature environment as it is molded at room temperature without preheating the raw material and mold. Based on the results analyzed through FEM, an effective mold structure design method was proposed by analyzing the changes in tensile and compressive stresses on molds according to the number of molds and reinforcement rings and comparing the product geometry and mold stress using three existing mold models.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.201-207
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• 1999

The automatic pinhole detection system is described. The goal of this project is to study the feasibility test of the new concept for hole detection. The developed method is able to detect almost 50$\mu\textrm{m}$ pinhole by evaluating the shining of the light as if there is pinhole in the strip. Moreover, it is possible to inspect up to the 200$\mu\textrm{m}$ inclined pinhole. The system cosists of three main functional parts: the source part of the light which is using the linear halogen lamp, the image gathering part which is using a line CCD and the image processing part. The light spot can be controlled and optimized corresponding to the situation of the strip. To eliminate back ground noise, the binary image processing method is adopted.

• Transactions of Materials Processing
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• v.11 no.5
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• pp.388-393
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• 2002

Heat-treatment-free steels have been replacing for conventional quenched-and-tempered structural steels since the microalloyed forging steel was developed in early 1970s in Germany. Substantial cost reduction provides the driving force for this change. As a result of intensive R & D efforts and application trials, various kinds of grades, for example heat-treatment-free steels for hot forging, machining and cold heading, have been developed and moreover these steels are in tonnage production throughout the world. The developments in alloy steels, processing conditions and structure-property characteristics of the heat-treatment-free steels, are described and also recent trend and future prospect are summarized in this report.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.15-18
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• 2019

점점 더 많은 어플리케이션이 Serverless 컴퓨팅 기반으로 구현되고 있다. Serverless 서비스 제공자는 가용자원을 확보하기 위하여 요청이 장시간동안 발생하지 않은 서비스 인스턴스를 종료한다. 종료된 인스턴스에 대한 요청은 Cold Start 로 인한 지연시간이 발생하게 된다. 서비스 사용자는 Cold Start 를 방지하기 위해 인스턴스가 종료되지 않도록 주기적으로 의미 없는 요청을 하게 되고, 이는 Serverless 서비스 시스템에 불필요한 오버헤드를 발생시키게 된다. 따라서 이 논문은 이러한 불필요한 오버헤드를 줄이기 위한 전략을 제시하고 그 구현에 관해 설명한다.

• Korean Journal of Plant Resources
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• v.26 no.3
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• pp.383-388
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• 2013

The research concerned of the regeneration of plants from embryos obtained from anther cultures of ginseng (Panax ginseng C. A. Meyer). The aim was to determine the influence of the regeneration medium on the efficiency of the regeneration process. We conducted to determine the optimum conditions such as cold pretreatment, plant growth regulators and carbon sources on anther culture of P. ginseng. Highest callus formation rate was obtained when flower buds pretreated at $4^{\circ}C$ for 1 day. Among the treated growth regulators with various degrees of concentration in Murashige and Skoog's (MS) medium, 4.53 ${\mu}M$ of 2.4-dichlorophenoxyacetic acid and 4.44 ${\mu}M$ of 6-benzylaminopurine gives the most responsive callus with the frequency of 73.89% and 129.53 g of fresh weight. When we used 3-9% of sucrose and maltose among the different kinds and various concentrations of carbohydrates, callus was formed highest 67.29% in the medium with 3% of sucrose. Shoots induced from callus supplemented with 28.9 ${\mu}M$ of gibberellic acid and rooted in Gamborg's B5 medium supplemented with 14.7 ${\mu}M$ of indole-3-butyric acid.

• Safety and Health at Work
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• v.6 no.1
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• pp.56-61
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• 2015

Frozen food processing workers work under a cold environment which can cause several adverse health effects.This study explored factors affecting workers' health in the frozen food industry in Thailand. Participants comprised 497 workers exposed to a cold working environment and 255 office workers who served as the controls. Data were collected by a survey on the work environment, and the interview of workers for abnormal symptoms. The exposed group had the following characteristics: 52.7% male, overall average age of 27 (SD 6.6) years old, attained elementary education (Grade 4 and Grade 6) (54.1%), married (48.9%), smokers (21.3%), alcohol consumption (31.0%), duration of work was between 1 and 5 years (65.2%), working 6 days a week (82.7%), 1-5 hours of overtime per week (33.8%), office workers (33.9%); work category: sizing (6.9%), peeling (28.3%) dissecting (22.2%), and in the warehouse (8.6%). The temperature in the work environment ranged from $17.2^{\circ}C$ to $19.2^{\circ}C$ in most sections, $-18.0^{\circ}C$ in the warehouse, and $25^{\circ}C$ in the office areas. Warehouse workers had more abnormal symptoms than controls including repeated pain in the musculoskeletal system (OR 11.9; 95% CI 6.12-23.45), disturbance throughout the body (OR 4.60; 95% CI 2.00-10.56), respiratory symptoms (OR 9.73; 95% CI 3.53-26.80), episodic finger symptoms (OR 13.51; 95% CI 5.17-35.33). The study results suggest that workers' health should be monitored especially with regard to back and muscle pain, respiratory symptoms, episodic finger symptoms, and cardiovascular symptoms. Health promotion campaigns such as antismoking and reduction of alcohol consumption should be established because smoking and alcohol consumption are contributing factors to the pathogenesis of Raynaud's phenomenon and peripheral vascular disorders such as hypertension and heart disease.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.175-178
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• 2008

While read operation on flash memory is fast and doesn't have any constraints, flash memory can not be overwritten on updating data, new data are updated in new area. If data are frequently updated, garbage collection, which is achieved by erasing blocks, should be performed to reclaim new area. Hence, because the number of erase operations is limited due to characteristics of flash memory, every block should be evenly written and erased. However, if data with access locality are processed by cost benefit algorithm with separation of hot block and cold block, though the performance of processing is high, wear-leveling is not even. In this paper, we propose CB-MG (Cost Benefit between Multi Group) algorithm in which hot data are allocated in one group and cold data in another group, and in which role of hot group and cold group is exchanged every period. Experimental results show that performance and wear-leveling of CB-MG provide better results than those of CB-S.