• Journal of People, Plants, and Environment
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• v.24 no.6
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• pp.585-593
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• 2021

Background and objective: Illegal open-air incineration, which is criticized as a leading source of air pollutants among agricultural activities, currently requires constant effort and attention. Countries around the world have been undertaking studies on the emission of heavy metal substances in fine dust discharged during the incineration process. A precise analytical method is required to examine the harmful effects of particulate pollutants on the human body. Methods: In order to simulate open-air incineration, the infrastructure needed for incineration tests complying with the United States Environmental Protection Agency (EPA) Method 5G was built, and a large-area analysis was conducted on particulate pollutants through automated scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS). For the test specimen, high-density polyethylene (HDPE) waste collected by the DangJin Office located in Choongcheongnam-do was used. To increase the identifiability of the analyzed particles, the incineration experiment was conducted in an incinerator three times after dividing the film waste into 200 g specimens. Results: Among the metal particulate matters detected in the HDPE waste incineration test, transition metals included C (20.8-37.1 wt%) and O (33.7-37.9 wt%). As for other chemical matters, the analysis showed that metal particulate matters such as metalloids, alkali metals, alkaline earth metals, and transition metals reacted to C and C-O. Si, a representative metalloid, was detected at 14.8-20.8 wt%, showing the highest weight ratio except for C and O. Conclusion: In this study, the detection of metal chemicals in incinerated particulate matters was effectively confirmed through SEM-EDS. The results of this study verified that HDPE waste adsorbs metal chemicals originating from soil due to its own properties and deterioration, and that when incinerated, it emits particulate matters containing transition metals and other metals that contribute to the excessive production and reduction of reactive oxygen species.

• Korean Journal of Environmental Agriculture
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• v.41 no.1
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• pp.9-15
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• 2022

BACKGROUND: Heavy metals discharged from various sources contaminate the soil and water and the residuals can persistently be accumulated. In this study, the concentration of soil heavy metals was assessed over the whole regions of Korea based on the contamination factor and the geoaccumulation index. METHODS AND RESULTS: The data of averaged concentrations of heavy metals and fluorine were collected from the Korean Statistical Information Service (KOSIS) and the research papers published. In order to classify the levels of heavy metal concentration, the contamination index, including the contamination factor and the geoaccumulation index, based on the relative ratio of the actual concentration of heavy metals in the soil to the background concentration was calculated. In addition, the distribution of heavy metals in soils was visualized by using the geographic information system (GIS). As a result, the Cd contamination in the soils was the most concerned. CONCLUSION(S): This study very roughly indicated the outline of heavy metal concentration over the whole regions of Korea. The change in heavy metals' concentration over the time should further be monitored and the larger data of heavy metal contamination are needed for better understanding in the future.

• Korean Journal of Metals and Materials
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• v.50 no.4
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• pp.271-279
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• 2012

9-12% Cr steels have been used in thermal power plants which repeat start and stop operations. Major factors of fatigue life are temperature, frequency, stress ratio, holding time, microstructure, and environment. Normally, fatigue life decreases at high temperature, low frequency, high stress ratio, and long holding time conditions. A Mod.9Cr-1Mo steel, called G91, was developed at ORNL (Oak Ridge National Laboratory, USA) and was adopted as a high-temperature structural material in the ASME Code in 2004. However, its low-cycle fatigue and fatigue crack growth characteristics have been rarely studied. In this work, we have investigated the low-cycle fatigue crack growth behaviors of G91 steel under various test conditions in terms of temperature and stress ratio. As temperature and stress ratio increase, the crack growth rate becomes faster and striation distance also increases. On the other hand, the number of branch cracks decreases.

• Korean Journal of Environmental Agriculture
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• v.19 no.5
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• pp.401-418
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• 2000

1. Production of the artificial zeolite from coal ash Coal fly ash is mainly composed of several oxides including $SiO_2$ and $Al_2O_3$ derived from inorganic compounds remained after burning. As minor components, $Fe_2O_3$ and oxides of Mg, Ca, P, Ti (trace) are also contained in the ash. These components are presented as glass form resulting from fusion in the process of the combustion of coal. In other word, coal ash may refer to a kind of aluminosilicate glass that is known to easily change to zeolite-like materials by hydrothermal reaction. Lots of hot seawater is disposing near thermal power plants after cooling turbine generator periodically. Using seawater in the hydrothermal reaction caused to produce low price artificial zeolite by reduction of sodium hydroxide consumption, heating energy and water cost. As coal ash were reacted hydrothermally, peaks of quartz and mullite in the ash were weakened and disappeared, and new Na-Pl peaks were appeared strengthily. Si-O-Si bonding of the bituminous coal ash was changed to Si-O-Al (and $Fe^{3+}$) bonding by the reaction. Therefore the produced Na-Pl type zeolite had high CEC of 276.7 $cmol^+{\cdot}kg^{-1}$ and well developed molecular sieve structure with low concentration of heavy metals. 2. Utilization of the artificial zeolite in agro-environment The artificial zeolite(1g) could remove 123.5 mg of zinc, 164.7 mg copper, 184.4 mg cadmium and 350.6 mg lead in the synthetic wastewater. The removability is higher 2.8 times in zinc, 3.3 times in copper, 4.7 times in cadmium and 4.8 times in lead than natural zeolite and charcoal powder. When the heavy metals were treated at the ratio of 150 $kg{\cdot}ha^{-1}$ to the rice plant, various growth inhibition were observed; brownish discoloration and death of leaf sheath, growth inhibition in culm length, number of panicles and grains, grain ripening and rice yield. But these growth inhibition was greatly alleviated by the application of artificial zeolite, therefore, rice yield increased $1.1{\sim}3.2$ times according to the metal kind. In addition, the concentration of heavy metals in the brown rice also lowered by $27{\sim}75%$. Artificial Granular Zeolites (AGZ) was developed for the purification of wastewater. Canon exchange capacity was 126.8 $cmol^+{\cdot}kg^{-1}$. AGZ had Na-Pl peaks mainly with some minor $C_3S$ peaks in X-ray diffractogram. In addition, AGZs had various pore structure that may be adhere the suspended solid and offer microbiological niche to decompose organic pollutants. AGZ could remove ammonium, orthophosphate and heavy metals simultaneously. Mixing ratio of artificial zeolite in AGZs was related positively with removal efficiency of $NH_4\;^+$ and negatively with that of $PO_4\;^{3-}$. Root growth of rice seedling was inhibited severely in the mine wastewater because of strong acidity and high concentration of heavy metals. As AGZ(1 kg) stayed in the wastewater(100L) for 4days, water quality turned into safely for agricultural usage and rice seedlings grew normally.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.6
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• pp.586-590
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• 2009

Poisson's ratio, one of elastic constants of elastic solids, has not attracted attention due to its narrow range and difficult measurement. Transverse wave velocity as well as longitudinal wave velocity should be measured for nondestructive measurement of Poisson's ratio. Rigid couplants for transverse wave is one of obstacle for scanning over specimen. In the present work, a novel measurement of Poisson's ratio distribution was applied. Immersion method was employed for the scanning over the specimen. Echo signals of normal beam longitudinal wave were collected, and transverse wave modes generated by mode conversion were identified. From transit time of longitudinal and transverse waves, Poisson's ratio was determined without the information of specimen thickness. Poisson's ratio distribution of the carbon steel weldment was mapped. Heat affected zone of the weldment was clearly distinguished from base and filler metals.

• Korean Journal of Metals and Materials
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• v.50 no.2
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• pp.152-158
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• 2012

The effect of current waveform on Cu filling into TSV (through-silicon via) and the bottom-up ratio of Cu were investigated for three dimensional (3D) Si chip stacking. The TSV was prepared on an Si wafer by DRIE (deep reactive ion etching); and its diameter and depth were 30 and $60{\mu}m$, respectively. $SiO_2$, Ti and Au layers were coated as functional layers on the via wall. The current waveform was varied like a pulse, PPR (periodic pulse reverse) and 3-step PPR. As experimental results, the bottom-up ratio by the pulsed current decreased with increasing current density, and showed a value of 0.38 on average. The bottom-up ratio by the PPR current showed a value of 1.4 at a current density of $-5.85mA/cm^2$, and a value of 0.91 on average. The bottom-up ratio by the 3-step PPR current increased from 1.73 to 5.88 with time. The Cu filling by the 3-step PPR demonstrated a typical bottom-up filling, and gave a sound filling in a short time.

• Korean Journal of Metals and Materials
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• v.46 no.5
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• pp.289-295
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• 2008

The effect of the alloy elements(Si/Mn) ratio on the coating quality including wettabilty with molten zinc, galvannealing kinetics and crater has been investigated in interstitial-free high strength steel(IFHSS) containing Si and Mn. When the Si/Mn ratio was below 0.75, IF-HSS exhibited a good wettability leading to a good galvannealed coating quality after annealing at $800^{\circ}C$ for 40s in $15%H_2-N_2$ mixed gas with dew point $-60^{\circ}C$. In contrast, the wettability and galvannealed coating quality were deteriorated in the Si/ Mn ratio above 0.75. It is shown that they have relevance to oxides forms by selective oxidation on the steel surface. The oxide particles dispersed on the steel surface with a surface coverage of below 40% resulted in good wettability and galvannealed coating quality. The oxide particle is mainly consisted of $Mn_2SiO_4$ with low contact angle in molten zinc. On the other hand, the continuous oxide layer on the steel surface, such as network- and film-type,caused to poor wettability and galvannealed coating quality. The coverage of oxide layer was above 80%, and its chemical species was $SiO_2$ with high contact angle in molten zinc. Consequently, the Si/Mn alloy ratio played an importance role in galvannealed coating quality of IF-HSS.

• Journal of environmental and Sanitary engineering
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• v.19 no.2
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• pp.15-22
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• 2004

Yellow loess, Tidal plat sediment, and mud are blown to be high in adsorption though they have great distinction according to the ratio of clay minerals content and their kinds. Thus one of the samples for this study can be obtained by drying of Yellow loess, Tidal plat sediment, and the mud which is semifinished products that are from the progress of heat treatment and making homogeneity which can be found everywhere in our county. Another sample can be prepared by reducing pollutants with the adsorbent and by homing heavy metals of their on. With the samples, noxious heavy metals such as Pb, Cd, and essential trace elements such as Cu, Fe, Mn by each concentration is tested for adsorption according to pH, the kinds of adsorbents and the amount of injection. With the help of these steps, this study shows that the adsorbents, which are green, reducing the additional pollution and low in price, can be found. It also shows that the optimal condition for removing pollutants can be found and the basic materials for treating water can be offered. The results were as follows ; Yellow loess shows the rates of adsorption by more than 50% and Tidal plat sediment and Mud show it by more than 90%. Thus Tidal plat sediment and Mud are higher than Yellow loess the rates of adsorption. The pH should be treated in natural condition because the rates of adsorption of Pb, Cd, Cu, Mn excepting Fe in mud is higher in pH 7 than in pH 3 of Yellow loess, Tidal plat sediment, and Mud. The drying adsorbents are good to use because the rates of adsorption of heavy metals has tendency to be higher in the drying method than in the burning method. It is considered that the more the mont of the injection of the adsorbent is , the higher the rates of adsorption is, and one gram is reasonable for the amount of the injection of Tidal plat sediment and mud. Yellow loess is suitable for the treatment of the water that includes low concentration of heavy metals because it has the lower rate of adsorption as the concentration of noxious heavy metals is higher. It is thought that Tidal plat sediment and Mud is proper for the treatment of the water that includes high concentration of heavy metals because the rates of adsorption has not been changed as the concentration of heavy metals increases.

• Journal of Environmental Impact Assessment
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• v.6 no.1
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• pp.105-110
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• 1997

Sanitary landfill is a general method as a final disposal of municipal solid waste(MSW), therefore leachate characteristics are very various as lime goes by because of highly concentrated organic acids are contained non biodegradable COD. So it is hard to abide by the mandatory standards of discharge eventhough applying the physicochemical and biological processes to treat the leachate. The process of treating leachate are determined by the degree of removal and components, but they are highly contained organic materials. It is a removal method to use jointly with the physicochemical process if the hard and fast rule is needed. The critical components of material are COD, ammonia, salts and heavy metals in the case of treating biologically. Biological process is to use metabolism of microorganism, therefore it is a desirable condition which heavy metals are not contained, because they acting as an inhibitor of enzyme. Of these are contained, organic decomposition and synthetic function of microorganisms decrease significantly. Consequently, this research paper lays emphasis on the concentration of heavy metals in leachate and for the purpose of forecasting the factors which are affecting the leaching of metalic waste in some degree, experimented the various reacting conditions. 1. When the concentration of heavy metals in leachate is in comparison with the level eluted after reaction, at pH 7.9 the result of reaction for PCB to CCL scrap showed that Zn, Mn, Cu was more eluted 11.6 times, 340.3 times, and 2,705.5 times respectively than the leachate undiluted solution. 2. At the condition of strong acid pH 4.7, the concentration of heavy metals in EM undiluted solution showed that Zn, Mn, Cu was more eluted 26.5 times, 147.3 times, and 3,656.3 times respectively than leachate undiluted solution. 3. When the ratio leachate to EM was 50 vs 50(V/V%), Mn was more eluted 198.7 times than leachate undiluted solution, but Zn and Cu do not show the meaningful results. 4. The color of landfill leachate was black-brown. And fulvic acid that is main ingredient of NBD COD contained, oxygen of 44~50%. For that reason, I estimated that the level of Zn, Mn, Cu was higher than the case of leachate. 5. COD of leachate from general landfill is difficult to remove. Because the solution of heavy metals is improved by the character of leachate(pH & ingredient of oxygen etc.) hence the Mn, Cu, Zn act as disturbing factor, the biochemical treatment is hard. Therefore the type of PCB & CCL scrap, iron, aluminum contained metals need to previously separate from general wastes as much as possible.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.297-302
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• 2001

To compare the relationship between the vertical distribution of heavy metals in paddy soil and soil pH near four abandoned metal mines, 40 paddy surface soils $(0{\sim}15\;cm)$ and 12 soils with soil depths ($0{\sim}20$, $20{\sim}40$, $40{\sim}60$, $60{\sim}80$ and $80{\sim}100$ cm) were collected. Both total and extractable heavy metal contents in soils were analyzed after acid digestion $(HNO_3:HClO_4:H_2SO_4)$ and 0.1 N-HCl extraction, respectively. The 0.1 N-HCl fraction ratio over total contents of Cd, Cu, Pb, and Zn were 57, 30, 23, and 19% respectively. Vertical distribution of heavy metals varied considerably among the different mines. In Choil mine, there was no difference in concentrations of all the metals with soil layers. However, Cu and Pb contents in Gahak mime were high at $0{\sim}20\;cm$ depth, and Zn was high at $0{\sim}40\;cm$ depth. In Sinyemi mine, Cd and Cu contents were high at $0{\sim}40\;cm$ depth. Cd, Cu, and Pb contents in Okcheon mine were high through all soil profiles up to 100 cm soil depth. The 0.1 N-HCl fraction ratio over total contents of heavy metals with soil layers were very high at $0{\sim}20\;cm$ depth. As soil depth increased, fraction ratio of heavy metals decreased at the high soil pH (Gahak, Sinyemi, and Choil mines). However, the ratios of Cd, Cu, and Pb in Okcheon mine, having a relatively lower soil pH than other sites, were relatively similar through all the soil profiles up to 100 cm soil depth. Therefore, it was estimated that the mobility and availability of heavy metals in soils were affected by soil pH.