• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1374-1381
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• 2022

Under the influence of nuclear radiation, the reliability of steam generators (SGs) is an important factor in the efficiency and safety of nuclear power plant (NPP) reactors. Motion planning that remotely manipulates an SG mobile tube-inspection robot to inspect SG heat transfer tubes is the mainstream trend of NPP robot development. To achieve motion planning, conditional traversal is usually used for base position optimization, and then the A^* algorithm is used for path planning. However, the proposed approach requires considerable processing time and has a single expansion during path planning and plan paths with many turns, which decreases the working speed of the robot. Therefore, to reduce the calculation time and improve the efficiency of motion planning, modifications such as the matrix method, improved parent node, turning cost, and improved expanded node were proposed in this study. We also present a comprehensive evaluation index to evaluate the performance of the improved algorithm. We validated the efficiency of the proposed method by planning on a tube sheet with square-type tube arrays and experimenting with Model SG.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4159-4169
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• 2022

Hydrogen mitigation using Passive Autocatalytic Recombiners (PARs) has been widely accepted methodology inside reactor containment of accident struck Nuclear Power Plants. They reduce hydrogen concentration inside reactor containment by recombining it with oxygen from containment air on catalyst surfaces at ambient temperatures. Exothermic heat of reaction drives the product steam upwards, establishing natural convection around PAR, thus invoking homogenisation inside containment. CFD models resolving individual catalyst plate channels of PAR provide good insight about temperature and hydrogen recombination. But very thin catalyst plates compared to large dimensions of the enclosures involved result in intensive calculations. Hence, empirical correlations specific to PARs being modelled are often used in integral containment studies. In this work, an experimentally validated CFD model of PAR has been employed for developing an empirical correlation for Indian PAR. For this purpose, detailed parametric study involving different gas mixture variables at PAR inlet has been performed. For each case, respective values of gas mixture variables at recombiner outlet have been tabulated. The obtained data matrix has then been processed using regression analysis to obtain a set of correlations between inlet and outlet variables. The empirical correlation thus developed, can be easily plugged into commercially available CFD software.

• 대한핵의학회지
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• 제33권5호
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• pp.439-451
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• 1999

목적: 안구 내 종양의 치료계획에 있어서 악성여부의 결정은 매우 중요하다. 하지만 안구 내 종양의 생검은 시력의 손상을 가져오므로 임상적으로 권장할 수 없는 방법이다. 저자들은 안구 네 종양의 악성 여부를 진단하는 데 있어서 F-18-FDG PET의 유용성과 검사 방법이 결과에 미치는 영향에 대해 연구하였다. 대상 및 방법: 임상적으로 악성 안구 내 종양이 의심되는 13명의 환자(15병소)를 대상으로 F-18-FDG PET 스캔을 시행하였다. 세 명은 양성의 병소를 가지고 있었고(망막 박리, 맥락막 삼출, 맥락막출혈) 열 명을 열두 개의 악성 병소를 가지고 있었다(흑색종 3, 망막아종 7, 전이암 2). 양성 병소들과 악성 병소들의 크기는 각각 $164{\pm}85mm^3$과 $598{\pm}718mm^3$이었다. 영상은 GE Advance PET 스캐너(전체반값두께 4.6 mm)를 이용하여 얻었다. 각각의 영상에 대해 매트릭스 크기를 바꾸어 가면서($256{\times}256$과 $128{\times}128$) 감쇠보정을 하거나 하지 않는 두 가지방법으로 재구성하여 재구성 방법에 의한 영향을 비교하였다. 여덟 명의 환자(양성 3, 악성 병소 6)에서 추가로 전신스캔을 시행하였다. 육안 판독 후 반정량적으로 분석하여 표준섭취계수를 구하여 분석하였다. 결과: 치료하지 않은 악성 병소는 모두 진단할 수 있었고 양성 병소는 육안적으로 관찰되지 않았다. 10개의 악성 병소들의 픽셀당 최대 표준섭취 계수는 $2.64{\pm}0.57g/ml$로 한 예를 제외하고는 모두 2.0 g/ml보다 높았다. 종양의 크기와 표준섭취계수는 통계적인 상관관계가 없었다. 전신스캔에서는 두개의 $1000 mm^3$ 보다 큰 악성 병소는 높은 섭취를 보였으나 중간 크기의 병소들은 희미하게 관찰되었고 $100 mm^3$ 이하의 병소 두 개는 관찰되지 않았다. 결론: F-18-FDG PET는 안구 내 악성 종양의 진단에 있어서 높은 예민도를 보여 주었다. 악성 종양은 모두 육안적으로 진단할 수 있었다. 작은 크기의 안구 내 종양을 진단하기 위해서는 전신스캔은 예민도가 낮아 적당하지 않고 스캔시간을 충분히 길게 하여 안구 국소촬영을 할 필요가 있다. 영상은 $128{\times}128$ 매트릭스보다 $256{\times}256$ 매트릭스로 재구성하는 것이 좋다.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.518-524
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• 2016

The thermal aging effects on mechanical properties and microstructures in China low-activation martensitic steel have been tested by aging at $550^{\circ}C$ for 2,000 hours, 4,000 hours, and 10,000 hours. The microstructure was analyzed by scanning and transmission electron microscopy. The results showed that the grain size and martensitic lath increased by about $4{\mu}m$ and $0.3{\mu}m$, respectively, after thermal exposure at $550^{\circ}C$ for 10,000 hours. MX type particles such as TaC precipitated on the matrix and Laves-phase was found on the martensitic lath boundary and grain boundary on aged specimens. The mechanical properties were investigated with tensile and Charpy impact tests. Tensile properties were not seriously affected by aging. Neither yield strength nor ultimate tensile strength changed significantly. However, the ductile-brittle transition temperature of China low-activation martensitic steel increased by $46^{\circ}C$ after aging for 10,000 hours due to precipitation and grain coarsening.

• Nuclear Engineering and Technology
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• 제49권3호
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• pp.645-650
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• 2017

This technical note demonstrates the feasibility of using laser ablation inductively coupled plasma mass spectrometry for the characterization of U-7Mo/Ale5Si dispersion fuel. Our measurements show 5.0% Relative Standard Deviation (RSD) for the reproducibility of measured $^{98}Mo/^{238}U$ ratios in fuel particles from spot analysis, and 3.4% RSD for $^{98}Mo/^{238}U$ ratios in a NIST-SRM 612 glass standard. Line scanning allows for the distinction of U-7Mo fuel particles from the Al-5Si matrix. Each mass spectrum peak indicates the presence of U-7Mo fuel particles, and the time width of each peak corresponds to the size of that fuel particle. The size of the fuel particles is estimated from the time width of the mass spectrum peak for $^{98}Mo$ by considering the scan rate used during the line scan. This preliminary application clearly demonstrates that laser ablation inductively coupled plasma mass spectrometry can directly identify isotope ratios and sizes of the fuel particles in U-Mo/Al dispersion fuel. Once optimized further, this instrument will be a powerful tool for investigating irradiated dispersion fuels in terms of fission product distributions in fuel matrices, and the changes in fuel particle size or shape after irradiation.

• Molecules and Cells
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• 제43권4호
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• pp.340-349
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• 2020

Oleoylethanolamide (OEA), a bioactive lipid in bone, is known as an endogenous ligand for G protein-coupled receptor 119 (GPR119). Here, we explored the effects of OEA on osteoclast differentiation, function, and survival. While OEA inhibits osteoclast resorptive function by disrupting actin cytoskeleton, it does not affect receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation. OEA attenuates osteoclast spreading, blocks actin ring formation, and eventually impairs bone resorption. Mechanistically, OEA inhibits Rac activation in response to macrophage colony-stimulating factor (M-CSF), but not RANKL. Furthermore, the OEA-mediated cytoskeletal disorganization is abrogated by GPR119 knockdown using small hairpin RNA (shRNA), indicating that GPR119 is pivotal for osteoclast cytoskeletal organization. In addition, OEA induces apoptosis in both control and GPR119 shRNA-transduced osteoclasts, suggesting that GPR119 is not required for osteoclast apoptosis. Collectively, our findings reveal that OEA has inhibitory effects on osteoclast function and survival of mature osteoclasts via GPR119-dependent and GPR119-independent pathways, respectively.

• Journal of Yeungnam Medical Science
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• 제23권1호
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• pp.82-89
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• 2006

최근 여러 종양에서 단백분해효소의 분비와 암의 악성도에 대한 연구가 이루어져 왔으며, 이를 신세포암종 환자의 예후 측정인자로 사용하려는 시도가 진행되고 있다. 이에 저자들은 제 4형 collagenase 중 대표적인 MMP-9의 발현정도를 정상 신조직과 신세포암종 조직에서 비교하였고, 또 암의 침윤 및 전이정도와의 관계와 다른 임상적 인자들과의 상관성을 분석하여 암의 단계적 진행과정에서의 MMP-9의 발현변화에 대하여 조사하였다. 그 결과 정상 신 조직에 비해 신세포암종 조직에서 MMP-9의 발현이 증가되며 암의 크기가 크고 혈관침범이 있으며 병기가 높을수록 MMP-9의 발현이 증가됨을 관찰할 수 있었다. 이는 MMP-9 발현의 증가가 신세포암종의 발생과정 및 암의 후기 진행에 관여함을 시사하므로 향후 신세포암종의 예후척도로 사용되어 치료방침을 결정하는데 도움을 줄 수 있을 것으로 생각한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.32-35
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• 2004

In boundary estimation in Electrical Impedance Tomography (EIT), conventional method is the modified Newton Raphson (mNR) method .The mNR is famous for good method since has good convergence and robustness against noisy data. But the mNR is low efficiency to get and update Jacobian matrix. So, the mNR become very slow algorithm. We propose the Quasi Newton (QN) method to improve efficiency which will lead to speed up in boundary estimation. The QN can improve a low efficiency by using estimated Jacobian matrix contrary to using exactly calculated Jacobian matrix, this used by the mNR. And finally, we propose the modified Quasi Newton (mQN) method because the QN has some problems such as bad early convergence rate and instability of 'divided by zero'. For the verification of the propose method, numerical experiments are conducted and the results show a good performance.

• Asian Pacific Journal of Cancer Prevention
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• 제17권7호
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• pp.3061-3063
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• 2016

Exploiting the immune system to abolish cancer growth via vaccination is a promising strategy but that is limited by many clinical issues. For DNA vaccines, viral vectors as a delivery system mediate a strong immune response due to their protein structure, which could afflect the cellular uptake of the genetic vector or even induce cytotoxic immune responses against transfected cells. Recently, synthetic DNA delivery systems have been developed and recommended as much easier and simple approaches for DNA delivery compared with viral vectors. These are based on the attraction of the positively charged cationic transfection reagents to negatively charged DNA molecules, which augments the cellular DNA uptake. In fact, there are three major cellular barriers which hinder successful DNA delivery systems: low uptake across the plasma membrane; inadequate release of DNA molecules with limited stability; and lack of nuclear targeting. Recently, a polysaccharide polymer produced by microalgae has been synthesized in a form of polymeric fiber material poly-N-acetyl glucosamine (p-GlcNAc). Due its unique properties, the F2 gel matrix was suggested as an effective delivery system for immune and gene vaccinations.

• BMB Reports
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• 제43권1호
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• pp.62-68
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• 2010

Matrix Metalloproteinases (MMPs) are a family of zinc-endopeptidases which can degrade extracellular matrix (ECM) components and play important roles in a variety of biological and pathological processes. 6,6'-bieckol isolated and characterized from an edible marine brown alga Ecklonia cava (EC), according to the comprehensive spectral analysis of MS and NMR data. Here the influence of 6,6'-bieckol on expressions of MMPs was examined by zymography and western blot analysis via human fibrosarcoma cell line (HT1080). It is shown that 6,6'-bieckol significantly down regulated the expressions of MMP-2 and -9 in dose-dependent manner. The influence of 6,6'-bieckol on the cell viability and cell behavior of HT1080 cells were also investigated, our dates shown that it suppressed the migration and 3D culture in HT1080 cells. Meanwhile, we explored several signal pathways which may contribute to this process, and found the suppressing of MMPs expressions in HT1080 cells might be due to the suppression of NF-${\kappa}B$ signal pathway.