• Resources Recycling
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• v.17 no.2
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• pp.46-54
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• 2008

It is well known that PCB (Printed Circuit Board) is a complex mixture of various metals. In this study, pyro-metallurgical process was investigated to extract valuable metallic components from the PCB scrap. PCB scrap was shredded and oxidized to remove plastic materials, and then, quantitative analysis were made. 15 mass %$Al_2O_3-45$ mass %CaO-40 mass %$SiO_2$ and 32 mass %$SiO_2-20$ mass %$Al_2O_3-38$ mass %CaO-10 mass %MgO, were chosen as basic slag compositions which are determined based on the quantitative analysis of PCB scrap. During experiments a super kanthal rotating furnace was used to melt and separate metallic components. Moreover the revolution effect on was the recovery of valuable metals from PCB scrap also investigated.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.4
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• pp.97-109
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• 2012

In this study this writer carried out survey and analysis on paving materials of children's playground for 40 apartment buildings with each of such apartment containing 100 households or more and which were built within last 15 years in Jeonju. As a result of analysis of such questionnaires this author could draw following conclusion. In the second half of 1990s pavement materials which were used mainly were sand and during first half of 2000s they were mixture of sand and rubber block and around 2010 they were rubber block or rubber chip pavements. Such change seemed to be a result of consideration of convenience for management and safety rather than in deference to diversity of children's outing places. Survey on the current status of pavement materials revealed need for directives by the main entity for management and their firm resolve for its implementation. And there was need for their coping with problems such as pressure of treading or lack of it or poor condition of drainage in case of sand and phenomena of pitting or dipping down, discoloring and poor drainage in case of rubber chips and rubber blocks and loosening of gaps between rubber blocks etc. Result of analysing status of usage disclosed that 50.4% of the respondents to questionnaires stated that they had experience of accidents. With regard to cause of such accident it was found that 47.5% of accidents were attributable to play facilities and 19.5% were due to paving (floor) materials thus it was disclosed that not only play facilities but also pavement materials had impact on safety for the children. Result of analysing level of satisfaction with pavement materials showed that pavement by rubber chips and blocks had higher level of satisfaction which was reflection of fear on cleanness of sand. In terms of preference rubber chip and rubber block pavements were highest and the next one was sand. Reason for such preference was based on concern with safety.

• Journal of Radiation Protection and Research
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• v.9 no.1
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• pp.33-42
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• 1984

A great variety of nuclear gamma rays emitted from fission and activation products of spent nuclear fuel contains much information that can be elicited without affecting the integrity of the fuel elements. But the extraction of such information from the complex spectrum is difficult and requires computer codes. In the present work, a versatile code 'CAERI' was developed which locates peaks and calculates their areas for X-rays as well as gamma rays using elegant features of some widely used programs for gamma-ray peak fitting. 'CAERI' coded in FORTRAN used infinite series approximation more accurate than other workers various, simple, piecewise series approximations for evaluations of the Voigt function which represents the X-ray peak with non-negligible natural line width. 'CAERI' can handle even a complex multiplet consisting of peaks from X-rays and gamma rays in arbitrary mixture, which one often encounters in the isotopic analysis of heavy elements such as U and Pu. The results of the fitting performed on the test spectra of $^{177m}\;Lu\;{\gamma}-ray\;and\;^{235}U\;K_{\alpha}$X-ray show good agreement with those by previous workers.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.65-77
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• 2016

Modeling for complex reacting flow in Fischer-Tropsch reactor is one of the challenges in the field of Computational Fluid Dynamics (CFD). It is hard to derive each and every reaction rate for all chemical species because Fisher-Tropsch reaction produces many kinds of hydrocarbons which include lots of isomers. To overcome this problem, after analyzing the existing methodologies for reaction rate modeling, non-Anderson-Schulz-Flory methodology is selected to model the detailed reaction rates. In addition, the inside flow has feature of multi-phase flow, and the methodologies for modeling multi-phase flow depend on the interference between the phases, distribution of the dispersed phase, flow pattern, etc. However, existing studies have used a variety of inside flow modeling methodologies with no basis or rationale for the feasibility. Modeling inside flow based on the experimental observation of the flow would be the best way, however, with limited resources we infer the probable regime of inside flow based on conventional fluid dynamics theory; select the appropriate methodology of Mixture model; and perform systematic CFD modeling. The model presented in this study is validated through comparisons between experimental data and simulation results for 10 experimental conditions.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.704-709
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• 1994

The $(LaS)_xCrS_2(x \approx 1.20$) of the incommensurate misfit layer was systhesized from reactant mixture of$La_S_3$,Cr and S at 1273K. Powder X-ray diffration of $(LaS)_xCrS_2(x \approx 1.20$) was indexed as a complex structure consisted with a monoclinic LaS-sublattice, a triclinic $CrS_{2}$-sublattice and their superlattice. The temperature dependence of sublattice dimension was investigated by the X-ray diffraction analysis at low temperature. The magnetic susceptibility of $(LaS)_xCrS_2(x \approx 1.20$) was measured between 77K and room temperature using a Faraday balance method. $(LaS)_xCrS_2(x \approx 1.20$) was paramagnetic on a $\sigma$-H plot at room temperature. The observed effective magnetic moment( p dr) was in fair agreement with the value calculated by spin-only contribution for $Cr^{3+}$ and spin and orbital contribution for $La^{3+}$.

• Journal of Ocean Engineering and Technology
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• v.25 no.3
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• pp.28-33
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• 2011

The thermal shock properties of SiC materials were investigated for high temperature applications. In particular, the effect of thermal shock temperature on the flexural strength of SiC materials was evaluated, in conjunction with a detailed analysis of their microstructures. The efficiency of a nondestructive technique using ultrasonic waves was also examined for the characterization of SiC materials suffering from a cyclic thermal shock history. SiC materials were fabricated by a liquid phase sintering process (LPS) associated with hot pressing, using a commercial submicron SiC powder. In the materials, a complex mixture of $Al_2O_3$ and $Y_2O_3$ powders was used as a sintering additive for the densification of the microstructure. Both the microstructure and mechanical properties of the sintered SiC materials were investigated using SEM, XRD, and a three point bending test. The SiC materials had a high density of about 3.12 Mg/m3 and an excellent flexural strength of about 700 MPa, accompanying the creation of a secondary phase in the microstructure. The SiC materials exhibited a rapid propagation of cracks with an increase in the thermal shock temperature. The flexural strength of the SiC materials was greatly decreased at thermal shock temperatures higher than $700^{\circ}C$, due to the creation of microcracks and their propagation. In addition, the SiC materials had a clear tendency for a variation in the attenuation coefficient in ultrasonic waves with an increase in thermal shock cycles.

• Environmental Analysis Health and Toxicology
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• v.20 no.4 s.51
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• pp.365-374
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• 2005

Ambient air particulate matters are classified into two distinct modes in sire distribution, namely the coarse and fine particles. Correlation between high particulate concentration and adverse effect on human populations has long been recognized. However, the toxicology of these adverse efforts has not been clarified. We investigated the genotoxic effect of PM 2.5 collected from urban area in Seoul by comet assay (A549 cells), CBMN assay (CHO-K1 cells) and EROD-microbioassay (H4IIE cells). Results from in vitro micronucleus assay and comet assay showed that PM 2.5 samples collected from traffic area, residential area and indoor air induced chromosomal damage and DNA breakage in a non-cytotoxic dose. The complex mixture effect of these PM 2.5 extracts was quantified by EROD-microbioassay in terms of its bio-TEQ (biologiral -TCDD equivalent concentration) which was 70.87$\pm$28.07, 93.55$\pm$21.80 and 14.31 $\pm$ 1.10 ng/g-PM 2.5 in traffic area, residental area and indoor air samples, respectively. Conclusively, we suggested that PM 2.5 collected from traffic area and residential area contains CYPIA inducer and genotoxic materials.

• Ocean and Polar Research
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• v.26 no.4
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• pp.595-606
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• 2004

Hydrographic survey in the Korea Strait has long history that has begun in August 1917 at the Busan - Tsushima cross section, still continues to date. However, chemical properties of bottom cold water found exclusively in the western channel of the Korea Strait during summer did not receive much scientific attention. The aim of the study is to decipher the enigmatic origin of the Korea Strait Bottom Cold Water (KSBCW) in terms of chemical properties. The physicochemical properties of the KSBCW are extracted from the CREAHS II hydrographic data. OMP method was applied to analyze origin of the KSBCW quantitatively. The KSBCW is well defined by low temperature below $10^{\circ}C$. The cold waters exhibited the local presence near the coast at about 120m depth with a thickness of 20m to 30m. The cold water was characterized by relatively cold, saline and higher chemical concentrations than adjacent waters. The KSBCW seems to have different origin kom that of the coastal upwelled waters at the Ulgi-Gampo because it is saline, denser and contains considerably less dissolved oxygen than upwelled waters. The physicochemical properties are reported to have noticeable annual variations which suggest the complex origin of the KSBCW. OMP analysis show that the KSBCW is a mixture of three water types; TMW (24%), ESIW (36%) and ESPW (40%). Relationship between the KSBCW and the east Sea circulation is traced by mapping the water masses that have similar T, S and DO of KSBCW. The result showed that the KSBCW is most possibly an extension of southward flowing coastal intermediate waters. Front these results, we expect that the monitoring KSBCW will provide us valuable information about the East Sea circulation.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.796-801
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• 1992

An empirical Lewis basicity, DN, for eight mixed methanol solvents has been measured by the solvatochromic behavior of the [Cu(tmen)(acac)]$CIO_4$. The change of DN in mixed methanol solvents is not correlated with composition of the mixtures and divided into three groups: (1) dipolar aprotic solvents contribute mainly to the solvation of solute (MeOH-DMSO, MeOH-PY, MeOH-DMF), (2) two components of mixture contribute equally to the solvation of solute (MeOH-MeCN, MeOH-dioxane, MeOH-AC) and (3) methanol contributes entirely to the solvation of solute (MeOH-DCE, MeOH-TCE). The relationship between DN and Kamlet-Taft's $B_{KT}$ for mixed methanol solvents was found to agree well. These DN values also were a useful factor to analysis of reactivity for mixed methanol solvents.

• Journal of the Korean Society of Tobacco Science
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• v.29 no.1
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• pp.30-40
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• 2007

The objective of this study was to investigate the contribution of various smoke constituents to the toxicological activity of total particulate matter(TPM) or the gas/vapor phase(GVP). These components included phenol compounds, aromatic amines, polycyclic aromatic hydrocarbons, heterocyclic amines, and carbonyl compounds. The mutagenic and cytotoxic potencies were assessed using the Salmonella mutagenicity assay with S. typimurium TA98 strain and the neutral red uptake cytotoxicity assay(NRU) with BALB/c 3T3 fibroblast cells, respectively. The Salmonella mutagenicity test showed that heterocyclic amines exhibited significantly higher levels of toxicity compared to other smoke constituents. Among them, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline(MeIQ) was shown the most mutagenic compound with a specific mutagenicity of $7.9{\times}10^5\;revertants/{\mu}g$. An analysis of the possible contribution revealed that MeIQ account for only 0.85% of the 2R4F-TPM mutagenicity in TA98. NRU data demonstrated that high cytotoxic activity was obtained for hydroquinone, formaldehyde, and acrolein. Based on the results of the present study, the contribution of acrolein to the cytotoxicity of the GVP fraction was calculated as 61%. Thus, a large proportion of the cytotoxic activity of this complex mixture, cigarette smoke gas phase, can be attributed to the acrolein.