• Nuclear Engineering and Technology
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• 제35권4호
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• pp.336-346
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• 2003

This study is intended to evaluate the dependency of TRU recycling characteristics on the neutron spectrum shift in a Pb-Bi cooled core. Considering two Pb-Bi cooled cores with the soft and the hard spectrum, respectively, various characteristics of the recycled core are carefully examined and compared with each other. Assuming very simplified fuel cycle management with the homogeneous and single region fuel loading, the burnup calculations are performed until the recycled core reached to the (quasi-) equilibrium state. The mechanism of TRU recycling toward the equilibrium is analyzed in terms of burnup reactivity and the isotopic compositions of TRU fuel. In the comparative analyses, the difference in the recycling behavior between the two cores is clarified. In addition, the basic safety characteristics of the recycled core are also discussed in terms of the Doppler coefficient, the coolant loss reactivity coefficient, and the effective delayed neutron fraction.

• Applied Science and Convergence Technology
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• 제25권4호
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• pp.77-80
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• 2016

The $PbSc_{1/2}Nb_{1/2}O_3$ ceramics at a relatively low temperature of $1300^{\circ}C$ was successful synthesized. Solid state reaction of two-step process is not necessary. The dielectric constant, dielectric loss and admittance of ceramic samples were determined. The pyroelectric characteristics are in good agreement with the dielectric properties. Ferroelectric properties of well-formed the $PbSc_{1/2}Nb_{1/2}O_3$ ceramics are in agreement with broad distribution of relaxation phenomenon. Relatively strong frequency dependent of dielectric constant is observed at about $110^{\circ}C$. The distinct thermal hysteresis was observed in the measurement of the dielectric constant and dielectric loss. The critical exponents of during cooling and heating measurements in the $PbSc_{1/2}Nb_{1/2}O_3$ ceramics were 1.14 and 1.59 at 1 kHz, respectively.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.140-144
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• 2000

In treatment of contaminated ground by electrokinetic remediation, pH control is the main prolllem for enhancinfi remediation efficiency. In this study, analysed pH variation characteristics according to contaminant(Pb$^{2+}$) concentration and estimated remediation efficiency with organic acid to prevent precipitation in cathode due to hydroxide ion occurrence. Because most of transported Pb$^{2+}$ is precipitatecl according as pH is increased at specimen adjacent to cathode reservoir, little magnitude of Pb$^{2+}$ is flowed out of specimen.cimen.

• 한국환경보건학회지
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• 제27권2호
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• pp.138-144
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• 2001

This study was carried out to investigate characteristics and Pb(II) removal effect of natural clays in the batch mode test. The effect of parameters such as temperature, adsorption time and coexisting cations on the sorption ability and characteristics was investigated to find out whether the clays could be used as adsorbents. Several natural clays from domestic have been investigated to have high specific surface area and have minerals such as SiO$_2$ and $Al_2$O$_3$. As a result, removal effects of Pb(II) on clays were reached at equilibrium in aqueous solutions by stirring about 20 minutes. The removal effect of Pb(II) was best for Kang Jin clay than other clays in terms of fixed time. Adsorption efficiency was not influenced by the possibility of continuous treatment system of wastewater which contain heavy metals by using natural clays from domestic.

• 한국물환경학회지
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• 제26권6호
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• pp.926-933
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• 2010

Runoff from a parking lot can be highly contaminated nonpoint source due to the impermeability of rainwater. This study presented runoff characteristics of heavy metals especially Zn and Pb from a parking lot during total 17 rain events. Monitoring results showed the first flush phenomenon within 30 min was observed in all rain events, but the event mean concentration (EMC) did not clearly show the characteristics of runoff. The ranges of Pb and Zn was $4{\sim}201{\mu}g/L$ and $131{\sim}672{\mu}g/L$, respectively, and the runoff mass of Zn and Pb was highly to related with the flow rate, and runoff coefficient of rain. The runoff mass of Zn was greater than that of Pb in all events. The runoff mass of Pb was highly correlated with the amount of TSS, and TSS and DOC were was related with the mass of Zn. This result implies that Pb and Zn are mainly existed in the particulate form. The results can be used to as meaningful data in the management of nonpoint source, and in the management in the runoff catchment in the parking lot.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.219-220
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• 2006

In this study, m order to develop multilayer ceramics vibrator for ultrasonic nozzle, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3-Na_2CO_3$ as sintering aids and their piezoelectric and dielectric characteristics were investigated according to the aomunt of PbO. With increasing PbO contents. secondary phases were increased and phase structure were changed from tetragonal structure to rhombohedral structure and also electromechanical coupling factor were linearly decreased. At the composition ceramics with the sintering temperature of $870^{\circ}C$ and 1 mol% excess PbO, density, electromechanical coupling factor, dielectric constant, piezoelectric d constant and mechanical quality factor showed the optimum value of $7.879g/cm^2$, 0.55, 1149, 328pC/N, 1224, respectively for multilayer ceramics vibrator application for ultrasonic nozzle.

• 한국기계가공학회지
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• 제4권2호
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• pp.3-9
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• 2005

In this study, the chip breaking characteristics of S, PbS and BiS free machining steels have been assessed. PbS free machining steel shows the lowest value of chip thickness ($t_c$) under the same cutting conditions. SM10C steel has the largest value of the chip cross-section area ratio ($R_{CA}$). As the feed rate becomes larger the chip breaking cycle time ($T_B$) decreases and the chip breaking index ($C_B$) increases. The properly controlled-C type chip has been obtained with the value of $C_B$ between 0.05 and 0.2. Free machining steel, PbS produces the properly controlled-C type chip in a wider feed rate range than other steels.

• 한국임상수의학회지
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• 제40권5호
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• pp.323-329
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• 2023

Peripheral blood-derived mesenchymal stem cells (PB-MSCs) have shown promise in cell-based therapy, as they can be harvested with ease through minimally invasive procedures. This study aimed to isolate PB-MSCs from foals and mares and to compare the proliferation and cellular characteristics of the PB-MSCs between the two groups. Six pairs of mares and their foals were used in this study. MSCs were isolated from PB by direct plating in a tissue culture medium, and cell proliferation (population doubling time [PDT], and colony-forming unit-fibroblast assay [CFU-F]), and characterization (morphology, plastic adhesiveness, colony formation, trilineage differentiation) were examined. There was no significant difference in the PB-MSC yield, CFU-F, and PDT between the mares and foals. PB-MSCs from both mares and foals showed typical MSC characteristics in terms of spindle-shaped morphology, plastic adhesive properties, formation of colonies, trilineage differentiation. These results suggest that PB-MSCs isolated from horses, both adult horses, and foals, can be used for equine cell-based therapy.

• 분석과학
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• 제13권3호
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• pp.368-377
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• 2000

실리카고정괭생이모자반을 합성하여 중금속 흡착제로 이용하였다. 이 흡착제에 대한 중금속 Cd(II), Pb(II)이온의 최대흡착조건을 알아보고 흡착특성을 연구하였다. 그 결과 산성보다는 알카리성에서 흡착량이 더 크고 Si-고정괭생이모자반에 대한 중금속 Cd(II), Pb(II)이온의 흡착량이 더 큼을 알 수 있었다. 또한 Cd(II) 이온보다 Pb(II) 이온의 흡착량이 더 높음을 알 수 있었다. Cd(II) 및 Pb(II) 이온의 회수율은 괭생이모자반에서 58.0-62.6%, 61.2-64.4%로 나타났고, Si-고정괭생이모자반에서 56.8-92.7%, 37.8-47.9%로 나타났다. Cd(II)이온은 Si-고정괭생이모자반에서의 회수율이 더 높게 나타났으나, Pb(II) 이온은 Si-고정괭생이모자반에서의 회수율이 더 낮게 나타났음을 알 수 있었다.

• 대한환경공학회지
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• 제30권4호
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• pp.446-452
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• 2008

중금속 제거를 위한 조류 Spirulina platensis의 생물흡착 특성에 관해 연구하기 위하여, 조류 균체와 Ca-alginate를 이용하여 조류를 고정화한 고정체에 대하여 각각 회분식반응기에서 Pb와 Cu의 제거 실험을 하였다. Spirulina platensis 균체에 의한 Pb와 Cu의 생물흡착은 20분 이내에 흡착평형에 도달하였다. Pb와 Cu의 흡착량은 초기 농도가 증가하거나 용액의 pH가 높아짐에 따라 증가하여, pH 4.5$\sim$5.0에서 최적 조건을 나타내었다. Pb 혹은 Cu의 농도가 200 mg/L일 때, Spirulina platensis의 단위 무게당 흡착된 Pb와 Cu의 최대 흡착량은 각각 86.43과 57.02 mg/g이었으며, 이는 같은 조건에서 활성탄보다 1.94와 1.48배 높은 값이다. Spirulina platensis 균체에 의한 Pb와 Cu의 흡착특성은 Freundlich와 Langmuir 흡착등온식에 의해 잘 해석되었으며, Langmuir 흡착등온식에 의해 구한 흡착제 단위 무게당 흡착되는 Pb 혹은 Cu의 최대 흡착량($q_{max}$)은 각각 95.24와 62.50 mg/g이었다. Sp. platensis 균체에 대한 FT-IR 분석결과 여러 가지의 기능기들을 확인하였고, 이러한 기능기들이 수용액상에서 금속 이온과 반응할 수 있다. 조류 Spirulina platensis를 Ca-alginate를 이용하여 고정화한 고정체에 의한 Pb와 Cu의 생물흡착의 경우, 40분 정도에 흡착평형에 도달하여 균체에 의한 경우에 비하여 약간의 확산제한이 관찰되었다.