• Korean Journal of Materials Research
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• v.25 no.6
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• pp.269-273
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• 2015

The effect of adding Ca on the microstructural and mechanical properties of as-cast Mg-11Li-3Zn-1Sn(wt%) alloys were investigated. Mg-11Li-3Zn-1Sn-0.4Mn with different Ca additions (0.4, 0.8, 1.2 wt%) were cast under an $SF_6$ and $Co_2$ atmosphere at $720^{\circ}C$. The cast billets were homogenized at $400^{\circ}C$ for 12h and extruded at $200^{\circ}C$. The microstructural and mechanical properties were analyzed by OM, XRD, SEM, and tensile tests. The addition of Ca to the Mg-11Li-3Zn-1Sn-0.4Mn alloy resulted in the formation of $Ca_2Mg_6Zn_3$, MgSnCa intermetallic compound. By increasing Ca addition, the volume fraction and size of $Ca_2Mg_6Zn_3$ with needle shape were increased. This $Ca_2Mg_6Zn_3$ intermetallic compound was elongated to the extrusion direction and refined to fine particles due to severe deformation during hot extrusion. The elongation of the 0.8 wt% Ca containing alloy improved remarkably without reduction strength due to the formation of fine grain and $Ca_2Mg_6Zn_3$ intermetallic compounds by Ca addition. It is probable that fine and homogeneous $Ca_2Mg_6Zn_3$ intermetallic compounds played a significant role in the increase of mechanical properties.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.341-353
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• 2000

The purpose of this study is to investigate the characteristics of pollutants overflow on storm events and the first flush analysis in industrial complex. Eight sub-basins in the Chongju industrial complex were selected for sampling and study with different characteristics during the period from June 1997 to August 1998. Water quality parameters of stormwater runoff such as $BOD_5$, COD, SS, TKN, $NO_3-N$, $PO_4-P$, TP, n-Hexane extracts, Cr, Cu, Pb and Fe were analyzed. During the storm events, measured concentration ranges of $BOD_5$, COD, SS, $NO_3-N$, TKN, $PO_4-P$, TP, r-Hexane extracts, Cr, Cu, Pb and Fe were 2~324 mg/L, 5~810 mg/L, 1~1,110 mg/L, 0.01~10.89 mg/L, 0.1~59.8 mg/L, 0.08~7.02 mg/L, 0.1~7.8 mg/L, 0.1~1,723.6 mg/L, 0.001~0.363 mg/L, 0.001~0.488 mg/L, 0.001~1.28 mg/L, and 0.26~18.91 mg/L, respectively in the industrial complex watersheds. And a quantitative of first flush has been presented. First flush occurs more frequently as the ratio of impervious area increases.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.138-142
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• 1999

Imide-containing diamine and dicarboxylic acid monomers, N-(4-aminophenyl)-4-aminophthalimide(APAP), N-(4-carboxyphenyl)-4-carboxyphthalimide(CPCP), N,N'-oxydiphenylenebis(4-aminophthalimide)(ODPAP) and N,N'-oxydiphenylenebis(4-carboxyphthalimide)(ODPCP) were prepared. Poly(amide-imide)s were prepared by condensation reaction of the diamine and the dicarboxylic acid monomers. Poly(amide-imide)s were also prepared from the diamine monomers and aromatic acid chlorodes such as terephthaloyl chloride and isophthaloyl chloride. The polymers possess inherent viscosity of 0.18~0.67 dL/g and brittle films were cast from NMP/LiCl solution. The poly(amide-imide)s are easily soluble in NMP/LiCl and also partially soluble in polar aprotic solvents such as DMF, DMSO, NMP and DMAc even at $80^{\circ}C$. DSC traces of polymers showed no glass transition temperature and melting temperature, and TGA traces showed a 10% weight loss at $500^{\circ}C$.

• Korean Journal of Materials Research
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• v.32 no.10
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• pp.403-407
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• 2022

This research investigated the effect of Si addition on the microstructure, mechanical properties, electric and thermal conductivity of as-extruded Al 6013 alloys. As the content of Si increased, the area fraction of the second phase increased. As the Si content increased, the average grain size decreased remarkably, from 182 (no Si addition) to 142 (1.5Si), 78 (3.0Si) and 77 ㎛ (4.5Si) due to dynamic recrystallization by the dispersed second particles in the aluminum matrix during the hot extrusion. As the Si content increased, the yield strength and ultimate tensile strength increased. The maximum values of yield strength and ultimate tensile strength were 224 MPa and 103 MPa for the 6013-4.5Si alloy. As the amount of Si added increased, the electrical and thermal conductivity decreased. The electrical and thermal conductivity of the Al6013-4.5Si alloy were 44.0 % IACS and 165.0 W/mK, respectively. The addition of Si to Al 6013 alloy had a significant effect on its thermal conductivity and mechanical properties.

• Journal of Preventive Medicine and Public Health
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• v.23 no.4 s.32
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• pp.391-403
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• 1990

In order to assess the degree of atmospheric pollution and noise and to contribute the health improvement of residents in Pusan, the author measured the levels of CO, $SO_2,\;NO_2$, TSP, HCHO and noise in 8 areas (industrial, residential and park areas) from January to March in 1990. The results were as follows : 1. Sasang industrial area was significantly higher($2.85{\pm}0.84ppm$) in the average concentration of CO than other areas. However, there no areas to affect the human body in terms of CO concentration. 2. In general, industrial area was significantly higher ($0.134{\pm}0.084ppm$) in the average concentration of $SO_2$ than other areas, and it was the lowest ($0.009{\pm}0.005ppm$) in the Namchon-dong area. 3. Industrial ($0.033{\pm}0.009ppm$) and residential area ($0.029{\pm}0.004ppm$) were significantly higher in the average concentration of $NO_2$ than Park area ($0.009{\pm}0.001ppm$). However, there were no areas to affect the human body in terms of $NO_2$ concentration. 4. Sasang industrial area was the highest ($580.4{\pm}415.26{\mu}g/m^3$) at the average concentration of TSP and Hae-Un Dae area was the lowest ($97.22{\pm}37.86{\mu}g/m^3$). But TSP concentration showed the level to affect the human body in most areas. 5. Industrial area was significantly higher ($2.25{\pm}1.15ppb$) in the average concentration of HCHO than residential ($1.13{\pm}0.25ppb$) and park area ($1.33{\pm}0.20ppb$). 6. Industrial area was significantly higher ($77.28{\pm}6.92dB(A)$) in the level of noise than residential ($65.77{\pm}3.76dB(A)$) and park area ($64.65{\pm}5.25dB(A)$). In comparison with regional Standard Noise Level, howeverm the average noise level of residential and park area was higher than that of the Standard. In general, the level of pollution of industrial complex areas was relatively higher than those of residential and park areas. Among the industrial areas, sasang area was worst in most items. Both $SO_2$ and TSP showed the level to affect the human body in most of studied areas. It is necessary to install a new Air Quality Standard for HCHO to screen our environmental pollution.

• Journal of Korean Society for Quality Management
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• v.43 no.2
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• pp.141-150
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• 2015

Purpose: The purpose of this paper is to motivate small/medium business challenged masterpiece development and to develop masterpiece strategic system. Methods: Each checklists are developed based on WC300 (World Class 300) and MQI (Masterpiece Quality Index). Correlation between the evaluation items about MQI and WC300 is analyzed. MQI is derived associated with main improvement areas of WC300 through IPA (Importance Performance Analysis). Compliance and ranking are analyzed through HOQ (House Of Quality) using masterpiece quality main factor and limiting factor. Strategy establishment base is secured through improvement derivation and correlation analysis between MQI and GQM 4.0(Global Quality Management 4.0). Results: Detail strategy is derived considering work condition about small/medium business's three kinds of industries (machine, electric and electronic). Conclusion: It is necessary to determine the potential capacity of the current domestic small/medium businesses. Small/medium businesses should be given the opportunity to self identify and manage their strengths and improvement.

• Membrane and Water Treatment
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• v.11 no.4
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• pp.303-312
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• 2020

This study aims to investigate at a laboratory scale fluorides removal from an industrial wastewater having excessive F^- concentration through a hybrid process combining neutralization and membrane separation. For the membrane separation operation, both Reverse Osmosis (RO) and Nanofiltration (NF) were investigated and confronted. The optimized neutralization step with hydrated lime allowed reaching fluoride removal rates of 99.1± 0.4 %. To simulate continuous process, consecutive batch treatments with full recirculation of membrane process brines were conducted. Despite the relatively high super saturations with respect to CaF₂, no membrane cloaking was observed. The RO polishing treatment allowed decreasing the permeate fluoride concentration to 0.9± 0.3 mg/L with a fluoride rejection rate of 93± 2% at the optimal transmembrane pressure of around 100 psi. When NF membrane was used to treat neutralization filtrate, the permeate fluoride concentration dropped to 1.1± 0.4 mg/L with a fluoride rejection rate of 88± 5% at the optimal pressure of around 80 psi. Thus, with respect to RO, NF allowed roughly 20% decrease of the driving pressure at the expense of only 5% drop of rejection rate. Both NF and RO permeates at optimal operating transmembrane pressures respect environmental regulations for reject streams discharge into the environment.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1544-1551
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• 2024

A unique brick series based on Vietnamese clay was manufactured at 114.22 MPa pressure rate for γ-ray attenuation purposes, consisting of (x) metallic waste & (90%-x) red clay mineral & 10% (hardener mixed with epoxy resin), where (x) is equal to the values 0%, 20%, 40%, 50%, and 70%. The impacts of industrial metal waste ratio in the structure and radiation protective characteristics were evaluated experimentally. The increase in metallic waste doping concentrations from 0% to 70% was associated with an increase in the manufactured brick's density (ρ) from 2.103 to 2.256 g/cm³ while the fabricated samples' porosity (Φ) decreased from 11.7 to 1.0%, respectively. Together with a rise in fabricated brick's density and a decrease in their porosities, the manufactured bricks' γ-ray attenuation capacities improved. The measured linear attenuation coefficient (μ, cm^-1) was improved by 30.8%, 22.1%, 21.6%, and 19.7%, at E_γ equal to the values respectively 0.662, 1.173, 1.252, and 1.332 MeV, when the metallic waste concentration increased from 0% to 70%, respectively. The study demonstrates that manufactured bricks exhibit superior radiation shielding properties, with radiation protection efficiencies of 88.4%, 90.0%, 91.7%, 92.1%, and 92.4% for bricks with industrial metal waste contents of 0%, 20%, 40%, 50%, and 70%, respectively, at γ-ray energy (E_γ) of 1.332 MeV.

• Nutrition Research and Practice
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• v.8 no.4
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• pp.432-438
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• 2014

BACKGROUND/OBJECTIVES: This research was conducted to develop a construct model regarding the dietary style, late night snacking choice attributes and health promotion behaviors of industrial workers. SUBJECTS/METHODS: The surveys were collected during the period between January and February 2013. A statistical analysis of 888 industrial workers was conducted using SPSS 12.0 for Windows and SEM (Structural Equation Model) using AMOS (Analysis of Moment Structure) 5.0 statistics package. RESULTS: The results of the correlations between all variables showed significant positive correlations (P < 0.05). Results of factors analysis on dietary styles were categorized into five factors and health promotion behaviors were categorized into four. The reliability of these findings was supported by a Cronbach's alpha coefficient of 0.6 and higher for all other factors. After obtaining the factors from processing an exploratory factor analysis and the end results supported the validity. In an attempt to study the late night snacking choice attributes in accordance to dietary styles and the health promotion behaviors of industrial workers, a structural equation model was constructed and analyzed. CONCLUSIONS: All tests proved the model satisfied the recommended levels of the goodness on fit index, and thus, the overall research model was proved to be appropriate.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.2
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• pp.181-195
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• 1997

The purpose of this study was to investigate factors affecting the composition and concentrations of fumes generated from various types of welding processes. The results are as follows. 1. Iron(Fe), zinc(Zn) and manganese(Mn) were predominant in Welding fumes. The Fe content in total fumes was 25.5% in coated electrode and 28.2% in $CO_2$ are welding, and the Zn content was 4.5% and 9.1%, respectively, and the Mn was 3.6% and 7.8%, respectively. 2. It was found that the important factors determining composition and concentration of fumes were type of industries, type of welding processes, type and composition of electrodes, composition of base metals, confinement of workplaces or condition of ventilation, work intensity, coated metals such as lead and Zn in paint. 3. The Mn content in airborne fumes was highly correlated with that of electrode(r=0.77, p<0.01) and was about 4 times higher than that in electrodes or base metals. The results lindicate that Mn is well evaporated into air during welding. The higher vapor pressure of Mn may explain this phenomenon. 4. the airborne total fume concentrations were significantly different among types of industries(p<0.001). The airborne total fume concentration was higher in order of sleel-structure manufacturing($GM=15.1mg/m^3$), shipbuilding($GM=13.2mg/m^3$), automobile-component manufacturing ($GM=7.8mg/m^3$) and automobile assembling industry($GM=3.0mg/m^3$) 5. The airbone total fume concentration was 6 times higher in $CO_2$ welding than in coated electrode welding, and approximately 3 times higher in confined area than in open area, in steel-structure manufacturing industry. 6. The concentration of welding fume outside welding helmet was about 2 times higher than that inside it. It is recommened that air sampling be done inside helmet to evaulate worker's exposure accurately, for it has an outstanding effect on reducing worker exposure to fumes and other contaminants.