• Journal of Ocean Engineering and Technology
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• v.22 no.6
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• pp.41-45
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• 2008

Effectsof carbon content on the weldability of B-containing 620 grade high Cr ferritic cast steels were investigated. Cast steel with lower carbon content of 0.07% showed lower HAZ hardness because of the formation of lower carbon martensite in HAZ. It also showed less solidification cracking susceptibility in weld metal because of the formation of delta ferrite. However, hot ductility showed no difference between cast steels with lower and higher carbon contents. Cast steel with lower carbon content showed greater HAZ softening after PWHT in the region heated between AC1 and AC3 because of its higher base metal hardness.

• Journal of Environmental Health Sciences
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• v.22 no.1
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• pp.91-98
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• 1996

산업장이나 생활환경에서 접하기 쉬운 수용성 염화물을 중심으로 19개 원소 24종의 금속화합물이 Chinese Hamster Don 세포에 있어서의 sister chromatid exchange(SCE) 출현빈도에 미치는 영향을 조사하였다. Chinese Hamster Don 세포에 대한 자매염색분체 교환출현빈도의 증가가 $CrO_3, K_2CrO_4, K_2Cr_2O_7, MnCl_2, K_2SeO_3, CH_3HgCl$ (p<0.01), $CoCl_2, Na_2HAsO_4, HgCl_2$ (p<0.05) 9종의 금속화합물에서 나타났으며, dose-response relationships이 현저한 금속화합물은 6가 크로화합물과 $K_2SeO_3$이었다.

• Particle and aerosol research
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• v.9 no.4
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• pp.221-230
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• 2013

We demonstrated the efficacy of magnetic nanoparticles (MNPs) produced from a low grade iron ore as an adsorbent for the removal of Cr(VI), a toxic heavy metal anion present in wastewater. The adsorption of Cr(VI) by these MNPs strongly depended on the dosage of MNPs, the initial concentration of the Cr(VI) solutions, and pH. The highest Cr(VI) adsorption efficiency of 22.0 mg/g was observed at pH 2.5. The adsorption data were best fit with the Langmuir isotherm and corresponded to a pseudo-second-order kinetic model. The used adsorbent was regenerated by eluting in highly alkaline solutions. Sodium bicarbonate showed the highest desorption efficiency of 83.1% among various eluents including NaOH, $Na_2HPO_4$, and $Na_2CO_3$. Due to the high adsorption capacity, the simple magnetic separation, and the high desorption efficiency, this nano-adsorbent produced from inexpensive and abundant resources may attract the attention of the industries to apply for removing various metal anionic contaminants from wastewater.

• Korean Journal of Materials Research
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• v.22 no.12
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• pp.675-681
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• 2012

We aimed to examine the co-doping effects of 1/6 mol% $Mn_3O_4$ and 1/4 mol% $Cr_2O_3$ (Mn:Cr = 1:1) on the reaction, microstructure, and electrical properties, such as the bulk defects and grain boundary properties, of ZnO-$Bi_2O_3-Sb_2O_3$ (ZBS; Sb/Bi = 0.5, 1.0, and 2.0) varistors. The sintering and electrical properties of Mn,Cr-doped ZBS, ZBS(MnCr) varistors were controlled using the Sb/Bi ratio. Pyrochlore ($Zn_2Bi_3Sb_3O_{14}$), ${\alpha}$-spinel ($Zn_7Sb_2O_{12}$), and ${\delta}-Bi_2O_3$ (also ${\beta}-Bi_2O_3$ at Sb/Bi ${\leq}$ 1.0) were detected for all of the systems. Mn and Cr are involved in the development of each phase. Pyrochlore was decomposed and promoted densification at lower temperature on heating in Sb/Bi = 1.0 system by Mn rather than Cr doping. A more homogeneous microstructure was obtained in all systems affected by ${\alpha}$-spinel. In ZBS(MnCr), the varistor characteristics were improved dramatically (non-linear coefficient, ${\alpha}$ = 40~78), and seemed to form ${V_o}^{\cdot}$(0.33 eV) as a dominant defect. From impedance and modulus spectroscopy, the grain boundaries can be seen to have divided into two types, i.e. one is tentatively assigned to ZnO/$Bi_2O_3$ (Mn,Cr)/ZnO (0.64~1.1 eV) and the other is assigned to the ZnO/ZnO (1.0~1.3 eV) homojunction.

• Transactions of the Korean hydrogen and new energy society
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• v.4 no.2
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• pp.17-22
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• 1993

$ErCo_2$화합물에서 Co를 천이원소로 10%만큼 치환한 $Er(Co_{0.9}M_{0.1})_2$화합물(M=Cr, Mn, Fe, Ni, Cu)의 비정질화 온도를 측정해서 수소유기 비정질화에 영향을 미치는 인자에 대해 살펴보았다. 비정질화 온도는 치환원소의 원자반경과 비례함을 알 수 있었다 그러므로 $ErCo_2$ Laves 화합물에서 수소유기 비정질화에 영향을 미치는 인자는 확산과 밀접한 연관이 있는 원자의 크기임을 알 수 있다.

• The korean journal of orthodontics
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• v.25 no.6 s.53
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• pp.675-688
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• 1995

The purposes of this study were:1) to determine the normal range of CR-CO discrepancy in normal occlusion group ; 2) to evaluate the changes of condylar position and craniofacial morphology between centric relation and centric occlusion before and after stabilization splint therapy in malocclusion group outside the normal range of CR-CO discrepancy. The normal occlusion group consisted of 80 subjects who had well-balanced faces and good occlusions with acceptable Class I molar relationship. They had not been treated orthodontically and had no signs or symptoms of temporomandibular joint dysfunction. 71 malocclusion patients enrolled for orthodontic treatment at the Department of Orthodontics, College of Dentistry, Chosun University comprised the malocclusion group, little variation of growth factor by the second molar eruption. They had CR-CO discrepancy beyond normal range and were subdivided into anterior-posteriorly -[25 Class I (0$\geq$4), and 24 Class III (ANB$\leq$0)] : vertically - [20 Normodivergentscy (30$\geq$34), and 18 Hypodivergency (SNGoMe$\leq$30)] ; and sexually - [26 Male and 45 Female]. For malocclusion group, stabilization splint with mutually protected type of occlusal scheme was applied for three months. Panadent articulators, Panadent condylar position indicator (CPI), and lateral headfilm were used to investigate the influence of stabilization splint on condylar position and craniofacial morphology. The results of this study were as follows. 1. The amounts of CR-CO discrepancy in normal occlusion were that the antero-Posterior component (${\bigtriangledown}X$) was $0.56\pm0.46mm$ (Male:$0.63\pm0.42mm$, Female:$0.49\pm0.50mm$) ; the supero-inferior component (${\bigtriangledown}Y$) was $-0.75\pm0.48mm$ (Male:$-0.76\pm0.52mm$, Female:-$0.73\pm0.43mm$) : and the transverse component (${\bigtriangledown}Z$) was $-0.33\pm0.28mm$ (Male : $-0.38\pm0.29mm$, Female:$-0.31\pm0.27mm$). 2. The condylar position was in normal range after stabilization splint therapy. 3. The mandible was always rotated infero-posteriorly after stabilization splint therapy. 4. Antero-posteriorly, Class III malocclusion responded very well to the stabilization splint therapy. 5. Vertically, Hyperdivergency responded very well to the stabilization splint therapy 6. Sexually, Male responded very well to the stabilization splint therapy.

• Korean Journal of Materials Research
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• v.22 no.12
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• pp.689-695
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• 2012

We have examined the co-doping effects of 1/2 mol% NiO and 1/4 mol% $Cr_2O_3$ (Ni:Cr = 1:1) on the reaction, microstructure, and electrical properties, such as the bulk defects and the grain boundary properties, of ZnO-$Bi_2O_3-Sb_2O_3$ (ZBS; Sb/Bi = 0.5, 1.0, and 2.0) varistors. The sintering and electrical properties of Ni,Cr-doped ZBS, ZBS(NiCr) varistors were controlled using the Sb/Bi ratio. Pyrochlore ($Zn_2Bi_3Sb_3O_{14}$), ${\alpha}$-spinel ($Zn_7Sb_2O_{12}$), and ${\delta}-Bi_2O_3$ were detected for all of compositions. For the sample with Sb/Bi = 1.0, the Pyrochlore was decomposed and promoted densification at lower temperature by Ni rather than by Cr. A homogeneous microstructure was obtained for all of the samples affected by ${\alpha}$-spinel. The varistor characteristics were not dramatically improved (non-linear coefficient, ${\alpha}$ = 5~24), and seemed to form ${Zn_i}^{{\cdot}{\cdot}}$(0.17 eV) and ${V_o}^{\cdot}$(0.33 eV) as dominant defects. From impedance and modulus spectroscopy, the grain boundaries were found to have been divided into two types, i.e., one is tentatively assigned to ZnO/$Bi_2O_3$ (Ni,Cr)/ZnO (0.98 eV) and the other is assigned to a ZnO/ZnO (~1.5 eV) homojunction.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.468-475
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• 2018

In medical ultrasound imaging, frequency-dependent attenuation downshifts and reduces a center frequency and a frequency bandwidth of received echo signals, respectively. This causes considerable errors in quadrature demodulation (QDM), result in lowering signal-to-noise ratio (SNR) and contrast resolution (CR). To address this problem, adaptive dynamic QDM (ADQDM) that estimates center frequencies along depth was introduced. However, the ADQDM often fails when imaging regions contain hypoechoic regions. In this paper, we introduce a valid region-based ADQDM (VR-ADQDM) method to reject the misestimated center frequencies to further improve SNR and CR. The valid regions are regions where the center frequency decreases monotonically along depth. In addition, as a low-pass filter of QDM, Gaussian wavelet based dynamic filtering was adopted. From the phantom experiments, average SNR improvements of the ADQDM and the VR-ADQDM over the traditional QDM were 1.22 and 5.27 dB, respectively, and the corresponding maximum SNR improvements were 2.56 and 10.58 dB. The contrast resolution of the VR-ADQDM was also improved by 0.68 compared to that of the ADQDM. Similar results were obtained from in vivo experiments. These results indicate that the proposed method would offer promises for imaging technically-difficult patients due to its capability in improving SNR and CR.

• Economic and Environmental Geology
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• v.35 no.2
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• pp.137-147
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• 2002

Natural geological and environmental processes reflect to element abundances in geological materials on the surface. This study aims to elucidate a possibility of geostatistical application to differentiate geochemical anomalies affected by anthropogenic and geogenic factors. A regional geochemical map was produced using 'inverse distance weight interpolation' method for analytical results of stream sediments «150 11m) which were collected from 2,290 first- to second-order streams over the whole Gyeonggi Province. The Jurassic granitic batholith in the southeastern province was selected as a target for the geostatistical examination. Factor analysis was conducted using 22 elements for stream sediments from 445 drainage basins over the granitic body. Co, Cr, Sc, MgO, Fe$_{2}$O$_{3}$, V, and Ni were grouped with high correlation coefficients and the depletion of the components may reflect the whole-rock chemistry of the granite. Regression analysis was done using Co, Cr, and Sc as dependent variables and other six components as independent variables, and the results were drawn as maps. The maps acquired generally show quite similar distribution patterns with those of concentrations of each variable. The similarity in the spatial patterns between the two maps indicates that the application of regression statistics can be valid for the interpretation of regional geochemical data. However, some components show local discrepancies which may be influenced by secondary factors regardless of the basement lithology. The regression analysis may be effective in extracting local geochemical anomalies which may reflect rather anthropogenic pollutions than geogenic influences.

• Korean Journal of Pharmacognosy
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• v.22 no.4
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• pp.233-239
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• 1991

Phellinus linteus was examined for its anticancer activity using an animal model. Water extract of Phellinus linteus was prepared from artificially cultivated mycelia. Neither toxicity nor abnormal changes of hematological parameters were observed in the rat given orally with high doses of drug extract for 15 days. ICR mice were transplanted with Sarcoma-180 tumor cells intraperitoneally and drug extract was daily given to the mice from 1 day after tumer transplantation for 3 weeks. Administration of drug extract significantly prolonged the survival duration of Sarcoma 180-transplanted mice. For the better understanding of the anticancer activity, we have examined the effect of the drug extract administration on various killer cell functions, such as natural killer(NK) cells, cytotoxic T-lymphocytes (CTL) and macrophages which have been known to be main effector cells in immune responses against tumors. The results from the 4 hr $^{51}Cr-release$ assay have shown that the drug extract augments mouse NK cell activity but neither CTL nor macrophages. It is possible, then, that the anticancer activity of the Phellinus linteus may be associated with augmentation of NK cell function in the cancerated hosts.