• Korean Journal of Organic Agriculture
• /
• v.7 no.1
• /
• pp.147-159
• /
• 1998

In order to study the effects of chemical fertilizer and organic fertilizer on the toxic mineral content in the absence or presence of the wood extraction, the lettuce an experiment of fatal 20 treatments was conducted far a peried of 10 weeks. The results obtained from the experiment are summarized as follows; 1. The mineral contents of the lettuce in the wood extraction-treated group and the wood extraction non-treated group showed no conspicious differenves. 2. These are no prominent differences in the mineal contents(Chromium, Nickel, Lead, and Aluminium) in the lettuce between the organic fertifized group and the lettuce raised in the chemical fertilized group. 3. Mercury was not detected in all samples of lettuces raised in all treatments.4. Cadmium contents in the lettuce samples were increased as the amount of organic fertilizer was increased from 25% to 100%.

• Food Science of Animal Resources
• /
• v.30 no.2
• /
• pp.190-197
• /
• 2010

The present study was conducted to determine the effect of tannery waste protein concentrate (TWPC) on fattening of cattle and the carcass and meat quality, with the aim of replacing the costly commercial protein concentrate (Jasoprot) with a more economical and effective alternative. Twelve young cattle (six male and six female) were fed during the study period on a control diet (T1) with 10% Jasoprot and on two test diets: 5% TWPC + 5% Jasoprot (T2) and 10% TWPC (T3). The test diets significantly affected (p<0.05) live weight gain and profitability compared to the control diet, perhaps due to the increased protein and essential amino acid content, relative to Jasoprot. TWPC was free of aflatoxin. Sensory-evaluated organoleptic scores did not differ among the groups. Chemical composition was normal as other beef and was non toxic especially within recommended chromium level ($1.90{\pm}0.6{\mu}g$) Total lipid contents were higher (p<0.05) in T3, and moisture, ash and crude protein contents were almost similar (p>0.05) among the three groups. It is concluded that TWPC or an equal mixture of TWPC and Jasoprot may be an economic and efficient alternative protein source to Jasoprot in the cattle industry, which minimizes adverse effects on carcass and sensory meat quality.

• Journal of the Korean GEO-environmental Society
• /
• v.20 no.5
• /
• pp.39-46
• /
• 2019

Most of the soil used for reclamation is marine clay generated from dredging construction.The soft ground made of dredged clay has high water content and high compressibility, so the bearing capacity of the ground is very weak and it is difficult to enter the ground improvement equipment. Therefore, surface hardening treatment method is used to enter equipment prior to full-scale civil engineering work, and stabilizer is mainly used for cement series. Cement-based stabilizers have the advantage of improving the ground in a short period of time and have excellent economic efficiency, but they are disadvantageous in that they cause environmental problems due to leaching of heavy metals such as hexavalent chromium. In this study, environmental effects evaluation of dredged clay mixed with normal portland cement and environmentally friendly stabilizer was evaluated, and uniaxial compressive strength test and indoor model test were conducted to confirm the bearing capacity characteristics of the solidified layer.

• Corrosion Science and Technology
• /
• v.21 no.3
• /
• pp.230-241
• /
• 2022

Austenitic stainless steel has been widely used because of its good corrosion resistance and mechanical properties. However, intergranular corrosion can occur if the alloy is welded or aged. The objective of this study was to determine intergranular corrosion behaviors of austenitic medium carbon (0.05 wt%) and low carbon (0.02 wt%) stainless steel aged at several conditions. Alloys were evaluated according to ASTM A262 Practice A, ISO 12732 DL-EPR (double loop-electrochemical potentiokinetic reactivation) test, and ASTM A262 Practice C. The degree of sensitization and intergranular corrosion rate were obtained. The relationship between the degree of sensitization and the intergranular corrosion rate showed a very large fluctuation. Such behavior might be related to whether two-dimension tests or three-dimension tests were performed. On the other hand, regardless of carbon content of alloys, when the intergranular corrosion rate increased, the degree of sensitization also increased. However, the DL-EPR test showed a higher sensitivity than the Huey test for differentiating the intergranular corrosion property at a low intergranular corrosion rate, while the Huey test had a higher sensitivity than the DL-EPR test for distinguishing the intergranular corrosion property at a high intergranular corrosion rate.

• Journal of Korea Foundry Society
• /
• v.41 no.6
• /
• pp.543-549
• /
• 2021

Aluminum cast iron has excellent oxidation resistance and good resistance to sulfide and corrosion. Compared to Ti and Ni alloys, it is expected to be a substitute material for structural materials and stainless steels because it is relatively inexpensive to use Fe, which is a non-strategic element. This results in a weight reduction effect of about 30% as compared to the use of stainless steel. With regard to aluminum as an alloying material, it is an element that has been widely used for the alloying of cast iron in recent years. Practical use has been delayed owing to the resulting lack of ductility at room temperature and the sharp decrease in the strength above 600℃ of this alloy, however. The cause of the weak room temperature ductility is known to be environmental embrittlement by hydrogen, and the addition of various alloying elements has been attempted in order to mitigate these shortcomings. Although alloying elements such as vanadium, chromium, and manganese are mainly used to increase the hardness and wear resistance of gray cast iron, the price of finished products containing these elements and the problems associated with alloys with this material impose many limitations.

• Advances in materials Research
• /
• v.13 no.3
• /
• pp.183-194
• /
• 2024

D3 tools steel and 440C stainless steel (SS) are normally being employed for application such as knife blade and cutting tools. These steels are iron alloys which have high carbon and high chromium content. In this study, lab work focused on the microstructural and corrosion behavior of D3 tools steel and 440C SS after went through heat treatment processes. Heat treatments for both steels were started with normalizing at 1020 ℃, continue with hardening at 1000 ℃followed by oil quenching. Cryogenic treatment was carried out in liquid nitrogen for 24 hours. The addition of cryogenic heat treatment is believed to increase the hardness and corrosion resistance for steels. Both samples were then tempered at two different tempering temperatures, 160 ℃ and 426 ℃. For corrosion test, the samples were immersed in NaCl solution for 30 days to study the corrosion behavior of D3 tool steel and 440C SS after heat treatment. The mechanical properties of these steels have been investigated using Rockwell hardness machine before heat treatment, after heat treatment (before corrosion) and after corrosion test. Microstructure observation of samples was carried out by scanning electron microscopy. The corrosion rate of these steels was calculated after the corrosion test completed. From the results, the highest hardness is observed for D3 tool steel which tempered at 160 ℃(54.1 HRC). In terms of microstructural analysis, primary carbide and pearlite in the as-received samples transform to tempered martensite and cementite after heat treatment process. From this research, for corrosion test, heat treated 440C SS sample tempered with 426 ℃possessed the excellent corrosion resistance with corrosion rate 0.2808 mm/year.

• Journal of the Korean Dietetic Association
• /
• v.18 no.2
• /
• pp.97-114
• /
• 2012

This study was performed to assess the nutritional status and hair mineral content of children with behavioral problems and compare the values with a gender, age-matched control group. The subjects were recruited from S elementary school children in Seoul, Korea. Students scored higher than 60 points were diagnosed with behavioral problems according to the Korean-Child Behavior Checklist. Nutritional assessment of the two groups (behavior problem group: male n=15, female n=24; $9.6{\pm}1.6$ years, control group: male n=16, female n=18; $9.5{\pm}1.9$ years) was performed using a nutritional survey and by measuring hair mineral contents. In the results, food frequency questionnaire analysis showed that the intakes of anchovy (P<0.05), soybean curb (P<0.01), radish (P<0.05), bean sprouts (P<0.05), spinach (P<0.05), carrot (P<0.05), pumpkin (P<0.05), lettuce (P<0.05), cabbage (P<0.01), apple (P<0.05), and milk (P<0.01) were higher in the control group than the behavior problem group, whereas intakes of ramyeon (P<0.05), cookies (P<0.05), and coke (P<0.01) were higher in the behavior problem group than the control group. Intakes of most nutrients such as plant-derived protein (P<0.05), fiber (P<0.05), plant-derived calcium (P<0.05), phosphorus (P<0.05), plant-derived iron (P<0.05), vitamin B2 (P<0.05), vitamin B6 (P<0.05), vitamin C (P<0.01), vitamin E (P<0.05), and folate (P<0.05) were significantly higher in the control group than the behavior problem group. Hair analysis showed that the levels of arsenic (P<0.05), mercury (P<0.001), uranium (P<0.05), iron (P<0.001), boron (P<0.01), and germanium (P<0.001) were lower, but the levels of phosphate (P<0.05), chromium (P<0.001), sodium (P<0.05), and sulfur (P<0.001) were higher in the behavior problem group than the control group. Conclusively, behavioral problems constitute a complicated condition in which nutritional factors may play major roles. However, it is still under investigation as to whether or not modification of dietary habits or nutritional supplementation can improve children's behavior, since symptoms require a broad understanding of the environmental and genetic interactions.

• Korean Journal of Soil Science and Fertilizer
• /
• v.27 no.2
• /
• pp.72-77
• /
• 1994

This study was conducted to investigate the influence of treatment of fly ash on heavy metal contents of the arable soil. Rice was cultivated on the two types of paddy field clay loam and sandy loam with 0, 12ton/10a of anthracite fly ash and bituminous coal fly ash application. And soybean was cultivated at the same type of upland fields with those ashes of 0, 9ton/10a, yearly for three years. At the harvest time, the heavy metal contents in the different layer were investigated. The results were summarized as follows : 1. The contents of some heavy metal were increased in the surface soils but didn't show the tendency in the deeper layer or soil texture. 2. In the paddy fields, the contents of Cd, Cu, Zn, Cr were increased. Meanwhile and the upland fields, the contents of Cd and Cr were increased with the successive application of Anthracite fly ash, but the others didn't show those tendency. 3. The contents of Cd, Cu and Zn in the paddy field, were increased but the upland field, the contents of Cd, Cr and Ni were increased by the successive application of bituminous coal fly ash.

• Journal of Soil and Groundwater Environment
• /
• v.17 no.3
• /
• pp.1-9
• /
• 2012

According to the agreement on WTO/TBT, we are under the situation to adopt international standard (ISO standard) as a national standard if it exists. However, in case of environmental area, it is a domestic legal obligation to use Korean environmental standard method(KESM) for analyzing various contaminants. Therefore it is necessary to assess the comparability between KEM and ISO standard prior to apply ISO standard to soil conservation law in Korea. The main purpose of this study is to assess the comparability of both methods for analyzing heavy metals in soil. We looked over various aspects like pre-treatment, calibration curve range, detection wavelength, soil organic matter content and so on. Apparently, the procedure of both methods is almost same. However in details, both methods are different in stationary time before aqua-regia extraction using reflux system, calibration curve range for Cu, Pb, Ni and measuring wavelength for Pb. According to the results of comparison test, the results were significantly different when the different calibration range was used. In case that all the extracts independent of methods were reanalyzed with the same calibration range of each method, both methods showed statistically same results. Other conditions like different stationary time, measuring wavelength of AAS and soil organic matter content did not have any influence on the analytical result. Therefore, we suggest to extend the calibration curve range to 0~8 mg/L which is used in KS I ISO standard(Korean standard related with environment which is translation version of ISO standard without any technical change). In case of $Cr^{6+}$, the results showed no significant differences between two methods even though the pretreatment, instrumentation and other analysis conditions were different. In addition to UV/Visble spectrometry of KESM for soil contamination, we suggest to adopt ion chromatography of ISO 15192(US EPA method 7199) for analyzing $Cr^{6+}$ with the consideration of laboratory work efficiency.

• Journal of Environmental Health Sciences
• /
• v.43 no.2
• /
• pp.103-110
• /
• 2017

Objectives: This study was performed to provide basic data for the re-establishment of standards (criteria) and analytical methods for hazardous metals in nail enamel. Methods: Ten metals (lead; Pb, arsenic; As, cadminum; Cd, antimony: Sb, cobalt; Co, nikel; Ni, copper; Cu, chromium; Cr, aluminum; Al, and mercury; Hg) were measured in 67 commercial nail enamels containing glitter and/or pearls. The content of hazardous metals (excepting Hg) was determined by using an inductively coupled plasma-optical emission spectrophotometer (ICP-OES) after microwave digestion. Mercury content was measured by a mercury analyzer without any preparation. Results: The detected ranges of the intact samples were as follows: $ND-1.756{\mu}g/g$ for Pb, $ND-1.24{\mu}g/g$ for As, ND for Cd, $ND-20.41{\mu}g/g$ for Sb, $ND-12.36{\mu}g/g$ for Co, $ND-7.908{\mu}g/g$ for Ni, $0.088-79.27{\mu}g/g$ for Cu, $0.281-18.54{\mu}g/g$ for Cr, $13.78-3563{\mu}g/g$ for Al, and $ND-0.044{\mu}g/g$ for Hg. After centrifugation, the detected ranges of supernatant were as follows: $ND-0.435{\mu}g/g$ for Pb, $ND-0.504{\mu}g/g$ for As, ND for Cd, $ND-0.035{\mu}g/g$ for Sb, $ND-13.17{\mu}g/g$ for Co, $ND-0.232{\mu}g/g$ for Ni, $0.117-90.07{\mu}g/g$ for Cu, $0.174-2.787{\mu}g/g$ for Cr, and $9.459-1565{\mu}g/g$ for Al. The results of this analysis showed that the levels of heavy metals such as Pb, As, and Sb were much higher in the intact samples than those of supernatant. Conclusion: In the present study, we found that the levels of hazardous metals were significantly different depending on the status of the presence of glitter. Based on the results, we recommend that the product consumer refrain from prolonged application of nail enamel, avoid biting or chewing the nails, and wear gloves during cooking and washing dishes.