• The Korean Journal of Food And Nutrition
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• v.14 no.2
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• pp.132-137
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• 2001

To know a degree of pollution in agricultural products cultivated around 4 unworked mines located in Chollanam-Do, we investigated a concentration of trace metal to provide the basic data for its residual limits. 28 samples of seven kinds of agricultural products (lettuce, onion. potato, radish, pepper. pumpkin, bean) collected from 4 unworked mines located in Chollanam-Do in 1999 were analyzed by Mercury Analyzer for mercury and Atomic Absorption spectrophotometer for Pb, As, Cd. Cu, Mn, and Zn. Hg contents were detected N.D. ∼trace level (0.01 ppm and less) and As contents were detected N.D. ∼ 0.038 ppm but most of samples were not detected. Cd contents were detected N.D∼0.101 ppm. The results of Hg, As, Pb and Cd content showed that for all the 7 species of agricultural products studied, none have accumulated levels dangerous enough to pose health problems. The average contents of Cu were 4.356∼10.624 rpm in bean. the Mn were 4.332∼24.385 ppm in lettuce and the Zn were 4.072 ∼ 20.715 ppm in bean, respectively.

• Design & Manufacturing
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• v.7 no.1
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• pp.23-27
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• 2013

Orchard sprayers, wide area dusters and multipurpose control cars are flagship products of Hansung T&I Ltd. Spray pumps are one of the essential parts for these products. But conventional belt pulleys for spray pumps are heavy and expensive, and they bring down the quality as well as productivity of the end-products. Therefore, this study focuses on mold design for aluminum die casting belt pulley and mold manufacture.

• Transactions of Materials Processing
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• v.9 no.4
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• pp.413-420
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• 2000

In the die casting process, the flow of liquid metal has significant influence on the quality of casting products and die life. For the optimal process design of front housing part of aircon compressor, various analyses were performed in this study by using computer simulation code, MAGMAsoft. The simulation has been focused on the molten metal behaviors during the filling and solidification stages for the sound casting products. Two cases of casting design that have different types of gating system are considered in the analysis. The potential sites where the casting defects may occur is examined by computer simulation and an improved design process is proposed. Also the effect of partial squeeze on the quality of casting products is considered and the optimal time lag after filling process is determined. For the die-stability, the effect of operational parameters such as die temperature, heat cycle and spot cooling on the die life has also been analyzed.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.93-94
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• 2006

A novel production method for porous metal components has been developed by applying powder space holder (PSH) method to metal powder injection molding (MIM) process. The PSH-MIM method has an industrial competitive advantage that is capable of net-shape manufacturing the micro-sized porous metal products with complicated shapes and controlled porosity and pore size. In this study, the small impeller with homogeneous micro-porous structure was manufactured by the PSH-MIM method. The effects of combinations in size and fraction of PMMA particle on dimensional tolerance and variation of sintered porous specimens were investigated. It was concluded that the PSH-MIM method could manufacture commercially microporous metal components with high dimensional accuracy.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.643-648
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• 2008

Ultra-thin sheet metal forming techniques are required in precision forming of miniaturized and integrated products. In order to manufacture a good quality and low cost ultra-thin sheet metal products, a highly precise high-speed press is needed. The precision of a press is related with its vibration characteristics during pressing operation. This study evaluated the vibration characteristics of a proposed press design using computer simulation. The analysis compares the static deformation characteristics of the slide and the slide motion for the metal forming of an ultra-thin sheet of thickness less than 0.1mm. Further, in order to minimize the vibrations during high speed pressing operation, revolution balances of the eccentric shaft and the balance weight device is also considered. Finally, modal analysis is used to characterize the natural frequency of vibration of the press.

• Journal of Powder Materials
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• v.31 no.3
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• pp.213-219
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• 2024

Additive Manufacturing (AM) is a process that fabricates products by manufacturing materials according to a three-dimensional model. It has recently gained attention due to its environmental advantages, including reduced energy consumption and high material utilization rates. However, controlling defects such as melting issues and residual stress, which can occur during metal additive manufacturing, poses a challenge. The trial-and-error verification of these defects is both time-consuming and costly. Consequently, efforts have been made to develop phenomenological models that understand the influence of process variables on defects, and mechanical/ electrical/thermal properties of geometrically complex products. This paper introduces modeling techniques that can simulate the powder additive manufacturing process. The focus is on representative metal additive manufacturing processes such as Powder Bed Fusion (PBF), Direct Energy Deposition (DED), and Binder Jetting (BJ) method. To calculate thermal-stress history and the resulting deformations, modeling techniques based on Finite Element Method (FEM) are generally utilized. For simulating the movements and packing behavior of powders during powder classification, modeling techniques based on Discrete Element Method (DEM) are employed. Additionally, to simulate sintering and microstructural changes, techniques such as Monte Carlo (MC), Molecular Dynamics (MD), and Phase Field Modeling (PFM) are predominantly used.

• Journal of the Korean Chemical Society
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• v.9 no.1
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• pp.61-65
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• 1965

Metal distribution in the reaction products and system of reactions between organo chloro acid or ester and zinc, silicon, magnesium, and tin under acetonitrile, dioxane, and toluene solvent were determined by means of radioactive tracer prepared by means of a (n, ${\gamma}$) reaction. It was found that the solubility of the organo halogen metal complex was markedly increased in a hydrophilic solvent and was decreased in a nonpolar solvent which resulted in an increased metal distribution in the recovered metal or water washing of the recovered metal mixture. This was also true in the case of the reaction conducted in the presence of a carbonyl compound. The relative increase of the solubility of the metal complex in a hydrophilic solvent was in order of zinc, silicon, tin and magnesium, and in a nonpolar solvent, it was in order of silicon, tin, magnesium, and zinc. There was no formation of organo metallics throughout the reaction sequence. The result was discussed and the observed solvent influence on the present reaction path was criticized.

• Journal of Environmental Science International
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• v.14 no.2
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• pp.185-192
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• 2005

The concentration of heavy metal were studied for the estimation of quality in herbal medicines which is Bupleuri Radix, Paeoniae Radix, Dioscoreae Rhizoma and Astragali Radix in products of north Gyeongbuk area Also, we collected soils from several area in Gyeongbuk, and determined heavy metal concentration of soils by ICP. We compared with herbal medicines in products of Gyeongbuk and their soils. The average levels of heavy metal of herbal medicines in Gyeongbuk area are as follows: Mercury is 0.037mg/kg, Chromium is 0.093 mg/kg, Nickel is 0.108mg/kg, Copper is 0.475mg/kg, Zinc is 3.14mg/kg, Manganese is 1.52mg/kg, Iron is 7,83mg/kg, and Cadmium, Lead and Arsenic is not detected. It was very lower in concentrations than those of average Korea area. For the heavy metals contents of Gyeongbuk area, in Gong Jung Ri, represented the higher level, it may be due to a near the road. The Cd contents in soil was not a wide difference. For the As and Pb contents in soil, Song Sa Ri (Bupleuri Radix) represented the higher level(0.68mg/kg, 1523mg/kg). Correlation coefficients of heavy metal contents in cultured herbal medicines and their soils did not give reproducible results. But the degree of correlation between a few heavy metal contents of Dioscoreae Rhizoma and their soil showed the good transfer from the soil.

• Korean Journal of Environmental Agriculture
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• v.20 no.3
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• pp.169-174
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• 2001

This study was conducted to compare and evaluate the heavy metal contents of agricultural products in Korea and to compare with relevant international criteria such as the Average Daily Intake(ADI) and the Provisional Tolerable Weekly Intake(PTWI) proposed by the joint FAO/WHO Codex Committee on additives and contaminant. Contents of heavy metal in cereals, pulses, potatoes, vegetables and fruits were in the range of $0.010{\sim}0.073$ for Cd, $0.40{\sim}6.45$ for Cu, $0.083{\sim}0.698$ for Pb, $2.45{\sim}16.30$ for Zn, $0.171{\sim}1.378$ for Ni, $0.023{\sim}0.233$ for Cr and $0.026{\sim}0.070$ mg/kg(F.W.) for As. Heavy metal contents of cereals, pulses, potatoes, vegetables and fruits were with natural content levels proposed by FAO/WHO and were similar to value monitored in other countries. Also, average intake of heavy metal from agricultural products was lower than the ADI and PTWI by the joint FAO/WHO Codex Committee on Additives and Contaminants. Therefore, none of the cereals, pulses, potatoes, vegetables and fruits evaluated showed accumulation of such heavy metal high enough to cause health problems to human.

• Journal of Food Hygiene and Safety
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• v.37 no.6
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• pp.394-399
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• 2022

This study was conducted to estimate hazardous heavy metal content, including lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in 120 collagen products currently marketed in Korea. Hg concentration was analyzed by a gold amalgamation method using a mercury analyzer, while concentrations of Pb, Cd, and As were analyzed by ICP-OES. The average Pb concentration was 0.097 mg/kg. For comparison, respective average concentrations were 0.108 mg/kg, 0.084 mg/kg, 0.131 mg/kg, and 0.149 mg/kg in functional health foods, other processed products, beverages, and fruit/vegetable processed products. The average concentration of Cd was 0.026 mg/kg. All products in which Cd was detected were functional health foods. The average concentration of As was 0.097 mg/kg, with respective average concentrations of 0.091 mg/kg, 0.133 mg/kg, and 0.086 mg/kg in functional health foods, other processed products, and fruit/vegetable processed products. The average Hg concentration was 0.0025 mg/kg, with respective average concentrations of 0.0012 mg/kg, 0.0028 mg/kg, 0.0013 mg/kg, and 0.0031 mg/kg in functional health foods, other processed products, fruit/vegetable processed products, and candies respectively. Heavy metal levels in beverages and candy products with set heavy metal standards were below the set standards. Even products without regulatory standards were found to be relatively safe compared with heavy metal standards set for domestic and foreign foods.