• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.131-138
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• 2011

We fabricated distributed feedback InGaAsP/InP laser diodes for optical fiber communication module and characterized the lasing properties in continuous wave operation. The active layer of 7-period InGaAsP(1.127 eV)/InGaAsP(0.954 eV) multi-quantum well structure was grown by the metal-organic chemical vapor deposition. The grating for waveguide was also fabricated by the implementation of the Mach-Zehender holographic method of two laser beams interference of He- Cd laser and the fabricated laser diode has the dimension of the laser length of $400{\mu}m$ and the ridge width of $1.2{\mu}m$. The laser diode shows the threshold current of 3.59 mA, the threshold voltage of 1.059 V. For the room-temperature operation with the current of 13.54 mA and the voltage of 1.12 V, the peak wavelength is about 1309.70 nm and optical power is 13.254 mW.

• KSBB Journal
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• v.17 no.1
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• pp.54-58
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• 2002

Curdlan gel containing various hydrophobic materials was prepared. The homogenized suspension of curdlan and hydrophobic materials was healed at $100^{\circ}C$. The curdlan gel can contain hydrophobic material up to 27%(v/v). When gel was compressed, only water in the gel was removed. When immersed in water, the dried gel absorbed water and became the original wet gel. The syneresis of gel decreased with the concentration of hydrophobic material added. DHA content of dried gel was about 90%. $\beta$-cyclodextrin inclusion complexes containing DHA were prepared with addition of water and ethanol. X-ray diffractograms of complexes showed a specific peak at 7-$8^{\circ}C$ and FT-IR spectrum of complex showed a specific C=O peak at $1745\textrm{cm}^{-1}$. Inclusion complex containing DHA was microcapsulated with curdlan and pullulan.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.262-268
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• 2022

This paper introduces a novel concept of the pulsed neutron facility (PNF) for maximizing the production of the thermal neutrons and its application to medical use based on prompt gamma neutron activation analysis (PGNAA) using Monte Carlo simulations. The PNF consists of a compact D-T neutron generator, a graphite pile, and a detection system using Cadmium telluride (CdTe) detector arrays. The configuration of fuel pins in the graphite monolith and the design and materials for the moderating layer were studied to optimize the thermal neutron yields. Biological samples - normal and cancerous breast tissues - including chlorine, a trace element, were used to investigate the sensitivity of the characteristic γ-rays by neutron-trace material interactions and the detector responses of multiple particles. Around 90 % of neutrons emitted from a deuterium-tritium (D-T) neutron generator thermalized as they passed through the graphite stockpile. The thermal neutrons captured the chlorines in the samples, then the characteristic γ-rays with specific energy levels of 6.12, 7.80 and 8.58 MeV were emitted. Since the concentration of chlorine in the cancerous tissue is twice that in the normal tissue, the count ratio of the characteristic g-rays of the cancerous tissue over the normal tissue is approximately 2.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.701-708
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• 2022

The mass attenuation coefficients (μ_m) of polyethylene glycol (PEG) of different molecular weights (1000-200,000) were measured using single-beam photon transmission. The X-ray fluorescent (XRF) photons from Zinc (Zn), Zirconium (Zr), Molybdenum (Mo), Silver (Ag) and Cadmium (Cd) targets were used to determine the attenuation of gamma radiation of energy range between 8.67 and 23.19 keV in PEG samples. The results were compared to theoretical values using XCOM and Monte Carlo simulation using Geant4 toolkit which was developed to validate the experiment at those certain energies. The mass attenuation coefficients were then used to compute the effective atomic numbers, electron density and half value layers for the studied samples. The outcomes showed good agreement between experimental and simulated results with those calculated theoretically by XCOM within 5% deviation. The PEG 1000 sample showed slightly higher μ_m value compared with the other samples. The dependence of the photon energy and PEG composition on the values of μ_m and HVL were investigated and discussed. In addition, the values of Z_eff and N_eff for all PEG samples behaved similarly in the given photon energy range, and they decreased as the photon energy increased.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4226-4230
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• 2022

The Korea Atomic Energy Research Institute (KAERI) has designed a Hybrid-Low Power Research Reactor (H-LPRR) which can be used for critical assembly and conventional research reactor as well. It is an open tank-in-pool type research reactor (Thermal Power: 50 kW_th) of which the most important applications are Neutron Activation Analysis (NAA), Radioisotope (RI) production, education and training. There are eight irradiation holes on the edge of the reactor core: IR (6 holes for RI production) and NA (2 holes for NAA) holes. In order to quantify the elemental concentration in target samples through the Instrumental Neutron Activation Analysis (INAA), it is necessary to measure neutron spectrum parameters such as thermal neutron flux, the deviation from the ideal 1/E epithermal neutron flux distribution (α), and the thermal-to-epithermal neutron flux ratio (f) for the irradiation holes. In this study, the MCNP6.1 code and FORTRAN 90 language are applied to determine the parameters for the two irradiation holes (NA-SW and NA-NW) in H-LPRR, and in particular its α and f parameters are compared to values of other research reactors. The results confirmed that the neutron irradiation holes in H-LPRR are designed to be sufficiently applied to neutron activation analysis, and its performance is comparable to that of foreign research reactors including the TRIGA MARK II.

• Analytical Science and Technology
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• v.15 no.1
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• pp.54-66
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• 2002

In order to study systematic survey of Kumho river pollution, water analysis for 24 items was conducted at 16 sites surrounding the Kumho river system for 3 times from May 2000 to February 2001. Analytical items for the study of water quality are as follows; water temperature, pH, BOD, COD, DO, SS, electrical conductivity, oil & grease, ABS, phenol, T-P, ${PO_4}^{3-}-P$, T-N, $NH_3-N$, ${NO_2}^--N$, ${NO_3}^--N$, Cu, Zn, Cr, Cd, Mn, Fe, Pb and As. The mean values obtained for water temperature, pH, BOD, COD, DO, SS, electrical conductivity, oil & grease, ABS, phenol T-P, T-N, Cu, Zn, Fe and Mn showed $17.84^{\circ}C$, 8.04, $2.54{\mu}g/mL$, $5.64{\mu}g/mL$, $7.07{\mu}g/mL$, $8.75{\mu}g/mL$, $600.4{\mu}S/cm$, $0.19{\mu}g/mL$, $0.015{\mu}g/mL$, $0.29{\mu}g/mL$, $0.21{\mu}g/mL$, $5.22{\mu}g/mL$, $0.005{\mu}g/mL$, $0.007{\mu}g/mL$, $0.044{\mu}g/mL$ and $0.001{\mu}g/mL$ respectively. As, Cd, Cr and Pb are not detected. The mean concentration of phenol, $NH_3-N$ and $NO_2-N$ were found to be increased compared to the prior study for 3 years from January 1997 to December 1999, that of BOD, COD, SS, oil & grease and ABS were found to be decreased and the others are nearly constant. The effect of Kumho river to the Nakdong river pollution are as follows. The mean concentration of BOD changed from $1.07{\mu}g/mL$ to $1.42{\mu}g/mL$ before and after of introducing of Kumho river water respectively. The mean concentration of COD, electrical conductivity, oil & grease, ABS, phenol, T-N and T-P changed from $1.99{\mu}g/mL$, $221{\mu}S/cm$, $0.15{\mu}g/mL$, $0.006{\mu}g/mL$, $0.06{\mu}g/mL$, $2.21{\mu}g/mL$ and $0.08{\mu}g/mL$ to $2.44{\mu}g/mL$, $392{\mu}S/cm$, $0.16{\mu}g/mL$, $0.015{\mu}g/mL$, $0.07{\mu}g/mL$, $2.81{\mu}g/mL$ and $0.19{\mu}g/mL$ respectively.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.281-295
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• 2010

This paper deals with magnetic susceptibility, mineralogy, soil properties (pH, EC, CEC, loss on ignition), iron and manganese oxides, the content and partitioning of heavy metals (As, Cd, Cr, Cu, Ni, Pb, Zn), and their mutual relationship in the soil samples of an unpolluted, abandoned mine area, and industrial complex area. The various minerals derived from weathered bedrock were identified by X-ray diffraction in the unpolluted soil samples, except for the magnetic minerals. XRD analysis also revealed the existence of hematite and magnetite related to mine tailings and waste rocks in the abandoned mine area samples. The industrial complex area samples had carbonate minerals, such as calcite and dolomite, that might be due to anthropogenic deposition. The sum of the reducible, oxidizable, and residual fractions was over 80% for the abandoned mine area samples and over 50% for the industrial complex area samples using the sequential extraction method. The industrial complex area samples had a relatively high carbonate fraction that was associated with carbonate minerals. The content of aqua regia-extractable Fe, Mn, As, and Zn had a high positive correlation with the content of the dithionite-citrate-bicarbonate (DCB)-extractable method related to Fe/Mn oxide phases. The 54% and 58% of aqua regia-extractable Fe and As content, respectively, acted together with the concentrations of the DCB-extractable phases. Magnetic susceptibility values of total samples ranged from 0.005 to $2.131{\times}10^{-6}m^3kg^{-1}$. The samples including iron oxide minerals, such as hematite and magnetite, had a high magnetic susceptibility. The magnetic susceptibility showed a significant correlation with the heavy metals, Cd (r=0.544, p<0.05), Cr (r=0.714, p<0.01), Ni (r=0.645, p<0.05), Pb (r=0.703, p<0.01), and Zn (r=0.496, p<0.01), as well as Fe (r=0.608, p<0.01) and Mn (r=0.615, p<0.01). The aqua regia-extractable Fe and Mn content had a significant positive correlation with Cd, Cr, Cu, Ni, and Zn. However, the DCB-extractable Fe and Mn content had a significant positive correlation with As and Ni, indicating that the heavy metals were associated with Fe and Mn oxide minerals.

• Solar Energy
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• v.20 no.2
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• pp.43-54
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• 2000

We prepared and characterized $Cu(In_{1-x}Ga_x)Se_2$(CIGS) films using a elemental co-evaporation method for absorbing layer of high efficiency thin film solar cells. The CIGS films deposited on a soda-lime glass exhibited low resistivity because of higher carrier concentration. Na was accumulated at the CIGS surface and the 0 and Se were also accumulated at the surface, suggesting that oxidation is a driving force of Na accumulation. The structure of CIGS film was modified or a secondary phase was formed in the Cu-poor CIGS bulk films probably due to the incorporation of Na into Cu vacancy sites. As the Ga/(In+Ga) ratio increased, the diffraction peaks of $Cu(In_{1-x}Ga_x)Se_2$ films were shifted to larger angle and splitted, and the grain size of $Cu_{0.91}(In_{1-x}Ga_x)Se_2$ films became smaller. All $Cu_{0.91}(In_{1-x}Ga_x)Se_2$ films showed the p-type conductivity regardless of the Ga/(In+Ga) ratio. Ag/n-ZnO/i-ZnO/CdS/$Cu_{0.91}(In_{0.7}Ga_{0.3})Se_2$/Mo solar cells were fabricated. The currently best efficiency in this study was 14.48% for $0.18cm^2$ area ($V_{oc}=581.5mV,\;J_{sc}=34.88mA$, F.F=0.714).

• Investigative Magnetic Resonance Imaging
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• v.16 no.1
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• pp.47-54
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• 2012

Purpose : This study was performed to evaluate the characteristics of rat mesenchymal stem cells (RMSCs) transduced with human ferritin gene and investigate $in$ $vitro$ MRI detectability of ferritin-transduced RMSCs. Materials and Methods: The RMSCs expressing both myc-tagged human ferritin heavy chain subunit (myc-FTH) and green fluorescence protein (GFP) were transduced with lentiviurs. Transduced cells were sorted by GFP expression using a fluorescence-activated cell sorter. Myc-FTH and GFP expression in transduced cells were detected by immunofluorescence staining. The cell proliferative ability and viability were assessed by MTT assay. The RMSC surface markers (CD29+/CD45-) were analyzed by flow cytometry. The intracellular iron amount was measured spectrophotometically and the presence of ferritin-iron accumulation was detected by Prussian blue staining. $In$ $vitro$ magnetic resonance imaging (MRI) study of cell phantoms was done on 9.4 T MR scanner to evaluate the feasibility of imaging the ferritin-transduced RMSCs. Results: The myc-FTH and GFP genes were stably transduced into RMSCs. No significant differences were observed in terms of biologic properties in transduced RMSCs compared with non-transduced RMSCs. Ferritin-transduced RMSCs exhibited increased iron accumulation ability and showed significantly lower $T_2$ relaxation time than non-transduced RMSCs. Conclusion: Ferritin gene as MR reporter gene could be used for non-invasive tracking and visualization of therapeutic mesenchymal stem cells by MRI.

• The Journal of Internal Korean Medicine
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• v.27 no.1
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• pp.40-54
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• 2006

Objective: This study aimed to identify the different effects of GMCSBHT water-extract and ethanol-extract on Th1/Th2 differentiation by monitoring Th1/Th2 specific cytokine secretion patterns and the transcriptional activities of T-bet, GATA-3, c-maf, $INF{\gamma}$ and IL-4. Materials and Methods: Spleen cells from eight week-old BALB/c mice were cultured in GMCSBHT extracts containing medium without activation for 24 hours and with activation for 48 hours. CD4+ T cells were isolated and mRNA expression levels of $INF{\gamma}$, IL-4, T-bet, GATA-3, c-maf by RT-PCR and secretion cytokines levels of $IFN{\gamma}$, IL-4 by ELISA were analyzed. Results: GMCSBHT extracts didn't have mitogenic effects on the unstimulated CD4+ T cells. In Th1 skewed condition, GMCSBAHT water extract had no significant effects on mRNA expression levels of $IFN{\gamma}$, T-bet and c-maf, but inhibited mRNA expression levels of IL-4, GATA-3. It showed significantly increased secretion cytokine levels of $IFN{\gamma}$, but had no significant effect on secretion cytokine levels of IL-4. In Th2 skewed condition, GMCSBHT ethanol extract inhibited mRNA expression levels of $INF{\gamma}$, IL-4, GATA-3 and c-maf significantly, but had no significant effects on mRNA expression levels of T-bet. It had no significant effects on secretion cytokine levels of $INF{\gamma}$, but showed remarkable inhibitory effects on secretion cytokine levels of IL-4. Conclusion: Results suggest that on Th1/Th2 deviation, GMCSBHT water extract has both amplifying effects on Th1 differentiation and inhibitory effects on Th2, but GMCSBHT ethanol extract has stronger inhibitory effects on Th2 differentiation than on Th1.