• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.599-605
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• 2005

The characteristics of PCDD/Fs were studied when accumulating on 1 to 4 year old pine needles that were used as passive samplers of atmospheric POPs. The rate of concentration increase was linear in lower(tetra- through hexa-) chlorinated PCDD/Fs, but higher (hepta- and octa-) chlorinated homologue concentrations did not increase with needle age. The lower were in gas phase and the higher in particles. Photodegradation rates of PCDDs on pine needles were similar to PCDFs, higher chlorinated PCDD/Fs tend to photolyze quickly. Therefore it is recommended that the younger needles should be collected to avoid errors from the depositional accumulation rates and photodegradation, and that, when comparing local concentrations of PCDD/Fs, needles of same age should be collected to reduce the errors.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.29-37
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• 2003

The purpose of this study was to identify the distribution of non-ortho and mono-ortho PCB congeners and homologues in adipose tissues and sera of women with breast cancer. The collected samples were 25 adipose tissues and 33 sera from women with breast cancer. The samples from the control group were 49 adipose tissues and 52 sera. The levels of three non-ortho and eight mono-ortho PCBs identified in adipose tissue and serum samples were determined by GC/MSD and GC/ECD analyses. Non-ortho and mono-ortho PCB congeners were more dominant in the control group than in the case group for serum samples. The Tetra-PCB and the Hexa-, Hepta-PCB were more dominant in tale and control groups, respectively. The level of PCB homologues in normal women was similar to that of the normal human milk samples. However, the levels of PCB homologues from breast cancer patients were almost same the level of sample from environment. As a result of this study, it is suggested that breast cancer could be related to environmental factors such as PCB level in stack gas and soil sample. More extended research should be to verify this result.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1476-1481
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• 2003

Kinematic calibration enhances absolute accuracy by compensating for the fabrication tolerances and installation errors. Effectiveness of calibration procedures depends greatly on the measurements performed. This paper investigates identifiable parameters and optimum postures for four different calibration procedures - measuring postures completely with inverse kinematic residuals, measuring postures completely with forward kinematics residuals, measuring only the three position components, and restraining the mobility of the end-effector using a constraint link. The study is performed for a six degree-of-freedom fully parallel HexaSlide type parallel manipulator, HSM. Results verify that all parameters are identifiable with complete posture measurements. For the case of position measurements, one and for the case of constraint link, three parameters were found non-identifiable. Selecting postures for measurement is also an important issue for efficient calibration procedure. Typically, the condition number of the identification Jacobian is minimized to find optimum postures. Optimal postures showed the same trend of orienting themselves on the boundaries of the search space.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.87-93
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• 2014

Optical brightening agents (OBA) is generally used to improve the optical property of printing paper in the paper industry. However, effects of OBA addition on paper preservability has been not fully understood yet. Therefore, this study was aimed to investigate effects of a OBA on the aging characteristics of paper. The OBA treatment of three different types was performed by dipping a filter paper into each a OBA solutions of different concentrations. The filter papers applied with a OBA were artificially aged at 80oC and 65% RH, and their optical and mechanical properties were evaluated. It was found that application of OBAs influenced the aging characteristics of paper. Especially, after aging, the optical and mechanical properties of the filter paper treated with the tetra-type OBA were more significantly decreased than those of the non-treated filter paper. The more the concentration of the tetra-type OBA increased, the more decreasing rate of optical and mechanical properties of the filter paper. While, in case of di-type OBA and hexa-type OBA, paper optical and mechanical properties were slightly decreased or not changed with a OBA treatment.

• Journal of the Korean institute of surface engineering
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• v.32 no.2
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• pp.165-171
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• 1999

The etching reaction of $UO_2$ in $CF_4/O_2$ gas plasma is examined as functions of $CF_4/O_2$ ratio, plasma power, and substrate temperature at up to $370^{\circ}C$ under the total pressure of 0.30 Torr. It is found that the highest etching rate is obtained at 20% $O_2$ mole fraction, regardless of r. f. power and substrate temperature. The existence of the optimum $CF_4/O_2$ ratio is confirmed by SEM, XPS and XRD analysis. The highest etching reaction rate at $370^{\circ}C$ under 150W exceeds 1000 monolayers/min., which is equivalent to 0.4$\mu\textrm{m}$/min. The mass spectrometry analysis results reveal that the major reaction product is uranium hexa-fluoride $UF_6$. Based on the experimental findings, dominant overall reaction of uranium dioxide in $CF_4/O_2$ plasma is determined : $8UO_2+12CF_4+3O_2=8UF_6+12CO_{2-x}$ where $CO_{2-x}$ represents the undetermined mix of $CO_2$ and CO.

• Ocean and Polar Research
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• v.32 no.3
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• pp.237-245
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• 2010

Bioaccumulation of polychlorinated biphenyls (PCBs) and organochlorine pesticides was studied in sediment dwelling bivalves, Manila clams (Ruditapes philippinarum), collected from the midwestern coast of Korea. As witnessed by the dominance of tetra- to penta-chlorinated congeners in sediments and the penta- to hexa-chlorinated congener dominance in clams, the profile of PCBs in the sediments and Manila clams differed. Lipid and organic carbon-normalized biota-sediment accumulation factors (BSAFs) were determined for organochlorine pesticides. BSAFs of $\beta$-hexachlorocyclohexane ($\beta$-HCH) and $\Sigma$DDTs were in the range of 0.06~1.36 and 0.31~1.06. No clear relationships were found between BSAFs of $\Sigma$DDTs in Manila clams and the concentrations of DDTs in the associated sediment. The accumulated PCBs and organochlorine pesticides were compared in Manila clams and oysters (Crassostrea gigas) collected from 3 sites. Highly chlorinated PCBs were more commonly found in oyster tissues than in clam tissues. The reasons for the different accumulation pattern of organic pollutants in the two organisms are discussed.

• International Journal of Fluid Machinery and Systems
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• v.4 no.1
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• pp.199-208
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• 2011

This work presents numerical results, using OpenFOAM, of the flow in the swirl flow generator test rig developed at Politehnica University of Timisoara, Romania. The work shows results computed by solving the unsteady Reynolds Averaged Navier Stokes equations. The unsteady method couples the rotating and stationary parts using a sliding grid interface based on a GGI formulation. Turbulence is modeled using the standard k-${\varepsilon}$ model, and block structured wall function ICEM-Hexa meshes are used. The numerical results are validated against experimental LDV results, and against design velocity profiles. The investigation shows that OpenFOAM gives results that are comparable to the experimental and design profiles. The unsteady pressure fluctuations at four different positions in the draft tube is recorded. A Fourier analysis of the numerical results is compared whit that of the experimental values. The amplitude and frequency predicted by the numerical simulation are comparable to those given by the experimental results, though slightly over estimated.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.76-81
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• 2008

UV curable pressure sensitive adhesive (PSA) was made by blending the di-functional or hexa-functional urethane-acrylate oligomer with synthesized acrylic PSA. The change of adhesive property and removability were investigated at various oligomer contents under each oligomer. As the content of oligomer increased, the peel strength was increased before UV irradiation, but it was decreased after UV irradiation. Also, it was observed that the peel strength increased with decrease of storage modulus (G'), and that loss factor (tan ${\delta}$) of the adhesive material affected the adhesive properties and removability.

• Journal of the Korean Chemical Society
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• v.57 no.3
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• pp.311-315
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• 2013

The geometry structures of hexa-coordinated [NiLX]X complexes ($X=Cl^-,\;Br^-,\;I^-$) {L = 8,9,18,19-tetrahydro-7H,17H-dibenzo[f,o] [1,5,9,13]dioxadiaza cyclohexadecine-8,18-diol} are optimized by density functional theory (DFT) using B3LYP/LANL2DZ. The calculated geometric parameters are in good agreement with the corresponding experimental values. Calculation results about these complexes show that dipole moment decreases, and the energy levels of HOMOs descend from iodo-complex to chloro-complex. The energy levels of HOMOs descend gently from iodo-complex to chloro-complex, while the energy levels of LUMOs in the present complexes are almost similar; therefore the energy gapes between HOMOs and LUMOs increased from iodo-complex to chloro-complex.

• Journal of the Korean Chemical Society
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• v.18 no.4
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• pp.267-271
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• 1974

The tetradentate schiff base, N,N'-bis(salicylaldehyde)-ethylene diimine has been reacted with a series of Mo(IV), Mo(V), Mo(IV), and Mo(III) oxidation states to form new Complexes; $[MoO_2(C_{16}H_{14}O_2N_2)], (MoO(C_{16}H_{14}O_2N_2)]_2O, (Mo(SCN)(C_{16}H_{14}O_2N_2)]_2O, and (Mo(H_2O)(C_{16}H_{14}O_2N_2)]_2O.$ These complexes have hexa coordinated configurations and the mole ratio of these ions to the ligand was 1:1. These complexes have been identified by visible spectra, infrared specra, T.G.A., D.T.A., and elemental analysis.