• Journal of the Korean Society for Precision Engineering
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• v.13 no.7
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• pp.78-89
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• 1996

This paper discusses automation of a small-scale hydraulic shovel and its trajectory control. To move an end-effect (grinder) along a desired trajectory, the controller uses PID(proportional-integral- defferential) control and internal pressure of hydraulic cylinder. To apply PID control in the present hydraulic system, the system model is derived physically and its system parameters are obtained by actual measurement. To show the effectiveness of the PID controller and propriety of system model, the computer simulations and experiments are performed. These results of the simulations and experiments indicate that the PID trajectory control of robotic deburring by hydraulic shovel is very effective.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.751-756
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• 2023

In this study, We investigated a fire case and performed an experiment to prevent fire from sparks that is generated during grinding operation. Before conduct the test, confirmed that the generating mechanism of fire-flakes in working grinder and the fire experiment was conducted using commonly tools, flammable materials in industrial field. in result, It could be measured scattering distance, temperature, ignition possibility by type of combustible materials. Based on the results of this study, We are expected to be used as basic data for fire prevention in grinding Industry.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.5
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• pp.969-977
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• 2001

The purpose of this study was to investigate disinfection state and effective factors of utensils and equipments used to foodservice of elementary schools in Busan area, The questionnaire which was administered to 160 dietitians was used in this study as a survey method. The results were as follows. The disinfection method of tray was mainly used by electric gas. Table and other products of stainless steel sanitized by sodium hypochlorite and hot water, but above 51% of slicer. grinder and peeler were not sanitized after used. The products of wood and plastic also used mainly sodium hypochlorite and hot water as sanitizers. In disinfection time, knife, wood spoon and plastic products should be sanitized on demand, but 30.9~53.5% of this utensils except rice scoop were sanitized on demand that showed deficiency of cognition for sanitation. The disinfection of most of utensils and equipments was conducted every day, but food case, slicer, peeler, grinder and wood spoon showed lower disinfection frequency than other products, The method of disinfection was related to dietitians age and career number of total serving, duration of foodservice and serving place, The disinfection time was also affected by dietitians age and educational level, and serving place. The disinfection frequency was affected by number of employee, number of total serving and duration of foodservice. Therefore based on the results of this study, it should be given to the microbiological study on disinfection method of utensils such as slicer, grinder, peeler, large spoon, plastic prouducts and the dietitians sanitation training also should be conducted continuously.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.4
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• pp.398-412
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• 2006

The purpose of this study is to investigate the relationship between the acceleration of vibration by the powered hand tools used in the shipbuilding industry, and to develop the prospective prevalence model for the hand-arm vibration syndrome among the shipbuilding workers.The acceleration levels and frequencies of six types of grinder were measured using the ISO5349 method along with the time of exposure to the vibration from the powered hand tools. Medical examination for 114 workers were performed using the cold provocation test. Comparisons were made between the estimated prevalence of hand-arm vibration syndrome from ISO5349 and the observed values from the medical examinations. By multiple regression, we developed the prospective prevalence model of hand-arm vibration syndrome produced by the hand tools used in the shipbuilding industry. 4 hour-energy-equivalent frequency-weighted accelerations were $6.23m/s^2$ in the grinding job done after welding, and $13.39m/s^2$ in the grinding job done before painting. The mean exposure time while holding powered hand tools was 4.64 hours. Prevalence rates of Raynaud's Phenomenon were 12.04% in the grinding after soldering, and 42.9% in the grinding before painting measured using the ISO5349 method. After exposure to vibration for 10.79 years, about a half of the workers in the grinding after welding could developed Raynaud's Phenomenon. For the workers in the grinding before painting, the latency was 5.02 years. The ISO equation for dose response relationship was not significantly correlated with observed recovery rates of finger skin temperatures, blood flows and amplitudes of nerve conduction velocities. A multiple regression model for dose-response relationship was proposed from the results. Recovery rate of the skin temperatures = -0.668+ 0.337 ${\times}$ 4 hour energy equivalent frequency-weighted accelerations + 0.767 ${\times}$ duration of vibration exposure(years) The validity was proved by multiple regression analysis after correlation transformation and regression results based on model-building data and validation data.

• Korean Journal of Materials Research
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• v.18 no.12
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• pp.635-639
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• 2008

In this paper, experimental studies of the regrinding of tungsten carbide (WC-Co) tools for high-speed machining were conducted. Regrinding and a subsequent evaluation test were carried out for a flat endmill tool with diameters of 10 mm and 3 mm using a CNC five-axis tool grinder and a CNC three-axis machining center. Tool wear on the two types of endmill tools increased as the cutting length increased, and the tool wear was not influenced by the regrinding state. In case of the micro endmill with a tool diameter of 3 mm, the effective regrinding time was determined for a flank wear threshold of 0.3 mm considering the tool life according to cutting length. The tool lives of the 10 mm and 3 mm endmill tools were increased by 80% and 72%, respectively. This conclusion proves the Feasibility of the recycling of tungsten carbide materials in the high-speed machining of high-hardened materials for industrial applications.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.121-129
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• 2017

In this study, the quality of recycled aggregate for concrete was investigated as the number of recycled aggregate crushing cycles, grinder and crusher, peeling and crushing. First, the quality of density, absorption ratio and solid content was improved as the separation distance decreased and the number of crushing increased, depending on the number of crushing of recycled aggregate and the distance between mantle and cone cave. The quality of density, absorption ratio and solid content was improved as the wire mesh used in striking plate and the number of hammers increased, depending on the type of striking plate and the number of hammers.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3
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• pp.402-407
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• 2013

In this paper, the image processing for flexible disk grinding and the effect of the grinding conditions on the flat zone length of a workpiece are investigated, with the purpose of automating the grinding process. To accomplish this, three issues should be carefully studied. The first is finding the relationship between the flat zone length and the grinding conditions such as the cutting speed and feeding speed. The second is developing a neural network algorithm to predict the flat zone. The third is developing an image processing algorithm to measure the flat zone length of a workpiece. Slope analysis is used to determine straight and curved sections during the image processing. For verification, the estimated length and the length from the image processing are compared with the length measured by a projector. There is a minimum difference of 1.7% between the predicted and measured values. The results of this paper will be useful in compiling a database for process automation.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.3
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• pp.83-91
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• 1996

The pulverized wastes originated from kitchen garbage grinder cause an additional load in sewage treatment plant and water environment. Therefore, several problems occur in sewer, such as microbial corrosion, odor, psychoda and fly interrupting flow of sewage etc. by their precipitation with earth and sand. This study was conducted on two experiments: hydrogen sulfide gas generation from sediments in sewer and anaerobic batch test. In anaerobic batch test, gas generation was increased when organic compounds were increased in concentration. Sulfide was decreased upon decreasing in sulfate concentration. In $H_2S$ gas generation test along the depth of sediments there were two different sampling sites which are apart from about 50 cm each other in a menhole. The one has the thickness of 55 cm from the surface, the other, of 60 cm. The hydrogen sulfide gas production rates were measured based on ranges from 0 to 10 cm, 10 to 20 cm, 20 to 30 cm for two samples. The results obtained were 1.08, between 0 to 10 cm in depth for the sample thickness of 55 cm and 3.07, 5.36, $5.42{\mu}g/g-VS{\cdot}hr$ in order of depth for the sample thickness of 60 cm, respectively.

• Journal of Sericultural and Entomological Science
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• v.43 no.1
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• pp.41-48
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• 2001

The purification, dissolution and powdering of stained waste silk obtained from weaving and dyeing process were studied for the surface modification of textile fabric and plastic materials. The whiteness of stained waste silk could be improved through degumming and bleaching with sodium hydrosulfite. The water-soluble fibroin solution can be obtained by dissoving the degummed waste silk in a boiling solution of 50% calcium chloride for 60 minutes. The salts and heavy metals contained in fibroin solution were removed by electric dialysis, wool fiber filtration and gel filtration chromatography. The fibroin powder was prepared by using a fine grinder after the alkali treatment for weakening the silk fiber. The fine fibroin powder of particle size around 30 ㎛ was obtained with a ultra fine-mill, while it was finer below 10 ㎛ with a ball-mill. The dissolved or powdered silk was applied to the surface of fabric with addition of the binder (a urethane resin). The moisture content of polyester and nylon fabrics treated with the silk solution was improved due to hygroscopic property of silk. The fine fibroin powder mixed with the binder ws coated on the surface of synthetic film by use of the air pressed sprayer. It was revealed that the hygroscopicity as well as the softness of fibroin powder coated film was much improved. Therefore, it is thought that the fine silk fibroin powder is applicable as an coating agent for the surface modification of plastic and synthetic leather.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.326-329
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• 2005

A worker who grinded the inner parts of camshafts for automobile engines using water-soluble metalworking fluid (MWF) for 14 years was diagnosed with sinusitis. We postulated that the outbreak of sinusitis could be associated with exposure to microbes contaminated in water-soluble MWF during the grinding operation. To suggest responsible agents for this outbreak, quantitative exposure assessment for chemical and biological agents and prevalence of work-related respiratory symptoms by questionnaire were studied. The exposure ranges of MWF mist (0.59 $mg/m^3$to 2.12 $mg/m^3$) measured during grinding exceeded 0.5 $mg/m^3$ of the recommended exposure limit (REL). Grinder's exposures to bacteria, fungi and endotoxins were also generally higher than not only the proposed standards, but also those reported by several studies to identify the cause of respiratory effects. Statistical test indicated that the prevalence rate of reported symptoms related to nasal cavities showed no significant differences among the operations. Evaluation on grinding operation characteristics and quantitative exposure assessment indicated that repeated exposure to MWF mist including microbes contaminated from the use of water-soluble MWF may cause respiratory diseases like sinusitis or at least increase susceptibility to the development of sinusitis