• Resources Recycling
• /
• v.24 no.3
• /
• pp.27-33
• /
• 2015

EAFD (Electric Arc Furnace Dust) is considered as pernicious pollutant, assigned hazardous waste. Since this dust is a by-product of industry, it contains valuable metals such as Fe, Zn, Ni, Cu which can be turned into resources by recycling process. In this study, hydrometallurgical process was applied to recover Zn from Electric Arc Furnace Dusts. The result showed 95% Zn recovery at 3M $H_2SO_4$, Solids/Liquid ratio 1:2 and aeration of 1.8L/min for 2hr. However there was 80% Zn recovery at lower $H_2SO_4$ concentration apply for pilot scale plant.

• YAKHAK HOEJI
• /
• v.53 no.5
• /
• pp.274-280
• /
• 2009

To survey the status of quality control of major ingredients of 'Ssanghwatang (Oriental medicine used for fatigue)', we analyzed 1,024 samples (9 kinds) of medical herbs to determine amounts of ashes, acid-insoluble ashes, loss on drying that are major elements to ensure basic quality of herbal drugstuffs. After ash analysis, Paeoniae Radix (from China) failed to meet the herbal standard criterion. After yielding Z-score(indicating the probability of exceeding its criterion) Zizyphi Fructus, Zingiberis Rhizoma, Paeoniae Radix, Rehmanniae Radix Preparata became objects of intense quality control (=IQC). Analysis on loss on drying shows Cinnamomi Cortex was unsuitable and was put under the IQC. In case of respective heavy metals, Angelicae Gigantis Radix, Cnidii Rhizoma, Cinnamomi Cortex exceeded the maximum permissible range for Cd. The 3 kinds of sub-standards were put to the IQC. Statistic figures showed a significant correlation (t-test, p<0.01) between country-of-origin and sub-quality rates. Compared to domestic one, imported medicinal herbs were less suitable in regard of acid-insoluble ash, loss on drying and Pb/Hg content. Meanwhile, amounts of Acid-insoluble ash showed positive relation with amounts of Pb (r=0.202) and As (r=0.243) among heavy metals leading to an inference that herbs of which root/rhizome is used for medical purposes attribute its high heavy metal content to the fine earth/sand being stuck to its root stalk.

• Journal of the Microelectronics and Packaging Society
• /
• v.12 no.3 s.36
• /
• pp.267-274
• /
• 2005

This paper presents the fabrication of surface acoustic wave (SAW)-based pressure sensor for long-term stable mechanical compression force measurement. SAW pressure sensor has many attractive features for practical pressure measurement: no battery requirement, wireless pressure detection especially at hazardous environments, and easy other functionality integrations such as temperature, humidity, and RFID. A $41^{\circ}$ YX $LiNbO_3$ piezoelectric substrate was used because of its high SAW propagation velocity and large values of electromechanical coupling factors $K^2$. A silicon substrate with $\~200{\mu}m$ deep cavity was bonded to the diaphragm with epoxy, in which gold was covered all over the inner cavity in order to confine electromagnetic energy inside the sensor, and provide good isolation of the device from its environment. The reflection coefficient $S_{11}$ was measured using network analyzer. High S/N ratio, sharp reflected peaks, and clear separation between the peaks were observed. As a mechanical compression force was applied to the diaphragm from top with extremely sharp object, the diaphragm was bended, resulting in the phase shifts of the reflected peaks. The phase shifts were modulated depending on the amount of applied mechanical compression force. The measured $S_{11}$ results showed a good agreement with simulated results obtained from equivalent admittance circuit modeling.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.235-235
• /
• 2017

Chromium (Cr) toxicity is hazardous to the seed germination, growth, and development of plants. ${\gamma}$-Aminobutyric acid (GABA) is a non-protein amino acid and is involved in stress tolerance in plants. To investigate the effects of GABA in alleviating Cr toxicity, we treated eight-d-old mustard (Brassica juncea L.) seedlings with Cr (0.15 mM and 0.3 mM $K_2CrO_4$, 5 days) alone and in combination with GABA ($125{\mu}M$) in a semi-hydroponic medium. The roots and shoots of the seedlings accumulated Cr in a dose-dependent manner, which led to an increase in oxidative damage [lipid peroxidation; hydrogen peroxide ($H_2O_2$) content; superoxide ($O{_2}^{{\cdot}-}$) generation; lipoxygenase (LOX) activity], MG content, and disrupted antioxidant defense and glyoxalase systems. Chromium stress also reduced growth, leaf relative water content (RWC), and chlorophyll (chl) content but increased phytochelatin (PC) and proline (Pro) content. Furthermore, supplementing the Cr-treated seedlings with GABA reduced Cr uptake and upregulated the non-enzymatic antioxidants (ascorbate, AsA; glutathione, GSH) and the activities of the enzymatic antioxidants including ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II), and finally reduced oxidative damage. Adding GABA also increased leaf RWC and chl content, decreased Pro and PC content, and restored plant growth. These findings shed light on the effect of GABA in improving the physiological mechanisms of mustard seedlings in response to Cr stress.

• Journal of Fashion Business
• /
• v.15 no.2
• /
• pp.145-159
• /
• 2011

The study aimed to analyze the status quo of manufacturing work environment and the work clothes' clothing comfort and wearer mobility of welding and grinding work processes in the machine and shipbuilding industries in South Korea. A questionnaire survey was conducted for the study, which consisted of questions about work clothes' clothing comfort and wearer mobility according to body parts. The findings derived from the research were: the high impact levels of work environment factors on welding and grinding work processes were noise, metal fragment, superheat, toxic gas, UV ray factors. Subject workers' assessment of work clothes' clothing pressures were in the levels between 3 (i.e. moderate) and 4 (i.e. comfortable) in a range of 5-point scale. The impact levels of wearer mobility factor were high on the work processes of welding and grinding in machine and grinding in shipbuilding. While welding process in shipbuilding showed a 'moderate' wearer mobility level and this was because its work postures were uncomfortable yet the rate of the motion change was low. The consideration to develop the work clothes specialized for certain work processes should include the materials' protecting performance from the hazardous work environment factors; and work clothes' designs that provides workers with maximized clothing comfort and wearer mobility for bending or tilting postures of upper, lower and lateral body parts defined in the study.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2015.11a
• /
• pp.249-249
• /
• 2015

Silver films have been of considerable interest for years due to their better performance relative to other metal films for engineering applications. A series of multi-layer silver coatings with different thickness (i.e. 0.3 um to 1.5 um) were prepared on Aluminium substrate containing copper undercoat by direct current (DC) magnetron sputtering method. For the comparative purpose, similar thickness silver coatings were prepared by electrolytic deposition method. Microstructural, morphological, and mechanical characteristics of the silver coatings were evaluated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), Surface roughness test, microhardness test and nano-scratch test. From the results, it has been elucidated that the silver films prepared by DC magnetron sputtering method has superior properties in comparison to the wet coating method. On the other hand, DC magnetron sputtering method is relatively easier, faster, eco-friendly and more productive than the electrolytic deposition method that uses several kinds of hazardous chemicals for bath formulation. Therefore, a New Work Item Proposal (NWIP) for the test methods standardization of DC magnetron sputtered silver coatings has recently been proposed via KATS, Korea and a NP ballot is being progressed within a technical committee "ISO/TC107-metallic and other inorganic coating".

• Journal of the East Asian Society of Dietary Life
• /
• v.23 no.2
• /
• pp.153-170
• /
• 2013

This study examined awareness and information acquisition behavior regarding food hygiene and safety of university students to improve safe dietary practices and to get basic information to develop educational materials for food safety. It was conducted among 276 university students of Qingdao University and Liaocheng University in Shandong province, China through a self-administered questionnaire. Data were analyzed by SPSS Windows V.19.0. To describe characteristics of the respondents, frequency distributions were used. In addition, t test, one-way analysis of variance and Duncan's multiple range tests were conducted. The results were as follows: The respondents were generally interested in food hygiene and safety. However, the level of awareness regarding the food hygiene and safety system in China was not high. Almost forty-five percent of the respondents did not think that foods produced and distributed in China were safe. For the reasons for their distrust, most of the students replied that they did not trust the safety 'because of distrust for hygiene of the food process', followed by 'because of distrust for food distribution' and 'because of excess or illegal use of food additives on food process'. The respondents answered for the concern level toward food hygiene and safety foodborne disease threatened food safety the most, followed by heavy metal contamination and endocrine disruptors. The respondents acquired most information from electronic media including TV and radio. Most of the students wanted to participate in food hygiene and safety education. Finally, when they found hazardous or foreign materials in food the most frequent reaction was 'paying attention in the next purchase', followed by 'notifying others', and 'letting it go this time but never buying that product in the future'.

• Korean Journal of Soil Science and Fertilizer
• /
• v.47 no.3
• /
• pp.213-216
• /
• 2014

Arsenic is a known hazardous metalloid not only to the animals but also to plants. With high concentrations, it can impede normal plant growth and cause even death of plants at extremely high levels. A known plant response to stress conditions such as toxic levels of metal (loids) is the production of stress ethylene, causing inhibitory effect on root growth in plants. When the effect of various arsenic concentrations was tested to maize plant, the stress ethylene emission proportionately increased with increasing concentration of As(V). The inoculation of two arsenic tolerant bacteria; Pseudomonas grimonti JS126 and Pseudomonas taiwanensis JS238 having respective high and low 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity reduced stress ethylene emission by 59% and 30% in maize grown in arsenic polluted soils. The result suggested the possible use of Pseudomonas grimonti JS126 for phytoremediation of arsenic polluted soils.

• Applied Chemistry for Engineering
• /
• v.25 no.3
• /
• pp.237-241
• /
• 2014

Benzene is a hazardous air pollutant, classified as carcinogenic to humans, that requires special management. Benzene exists both indoors and outdoors and the control measure of indoor benzene is different from that of outdoor benzene. The removal of indoor benzene needs to be accomplished at low temperatures (normally below $100^{\circ}C$), while outdoor benzene is usually removed at much higher temperature ($300-400^{\circ}C$) by using catalytic oxidation. This review paper summarizes the recent trend in catalytic treatment of airborne benzene, focusing on catalytic oxidation and catalytic ozone oxidation. Particular attention is paid to Mn-based catalysts for low-temperature oxidation of benzene, which are more economical than the other noble-metal catalysts. Various methods are used to generate more efficient Mn-based catalysts for benzene removal. Ozone oxidation is attracting particularly significant attention because it can remove benzene effectively below $100^{\circ}C$, even at room temperature.

• Advances in environmental research
• /
• v.6 no.1
• /
• pp.67-81
• /
• 2017

Mining activities play a significant role in environmental pollution by producing large amounts of tailings which comprise heavy metals. The impressive increase in mining activities in recent decades, due to their high influence on the industry of developing countries, duplicates the need for a substantial effort to develop and apply efficient measures of pollution control, mitigation, and abatement. In this study, our objective was to investigate the effect of simulation of the leachate, pH and inflow intensity of transport of $Pb^{2+}$, $Zn^{2+}$, and $Cd^{2+}$ through Lakan lead and zinc plant tailings, in Iran, and to evaluate the modeling efficiency by comparing the modeling results and the results obtained from previous column studies. We used the HP1 model and the PHREEQC database to simulate metals transport through a saturated soil column during a 15 day time period. The simulations assumed local equilibrium. As expected, a lower pH and inflow intensity increased metal transport. The retardation of heavy metals followed the order $Zn^{2+}$ > $Pb^{2+}$ > $Cd^{2+}$ and the removal concentrations of Cd, Pb, and Zn at the inflow intensity critical scenario, and Cd and Pb at inflow acidity critical scenario exceeded the allowable EPA and Iranian's 1053 standard thresholds. However, although the simulation results generally agreed well with the results of the column study, improvements are expected by using multi-dimensional models and a kinetic modeling approach for the reactions involved. The results of such investigations will be highly useful for designing preventative strategies to control reactive transport of hazardous metals and minimize their environmental effects.