• Nuclear Engineering and Technology
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• 제39권2호
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• pp.95-102
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• 2007

The conceptual design of the MIT modular pebble bed reactor is described. This reactor plant is a 250 Mwth, 120 Mwe indirect cycle plant that is designed to be deployed in the near term using demonstrated helium system components. The primary system is a conventional pebble bed reactor with a dynamic central column with an outlet temperature of 900 C providing helium to an intermediate helium to helium heat exchanger (IHX). The outlet of the IHX is input to a three shaft horizontal Brayton Cycle power conversion system. The design constraint used in sizing the plant is based on a factory modularity principle which allows the plant to be assembled 'Lego' style instead of constructed piece by piece. This principle employs space frames which contain the power conversion system that permits the Lego-like modules to be shipped by truck or train to sites. This paper also describes the research that has been conducted at MIT since 1998 on fuel modeling, silver leakage from coated fuel particles, dynamic simulation, MCNP reactor physics modeling and air ingress analysis.

• 대한방사선협회지
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• 제25권1호
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• pp.234-252
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• 1999

Purpose : Physical properties of radiophamaceuticals of technetium($^{99m}Tc$) and thallium($^{201}Tl$) have early been used for clinical diagnostics. The studies of those radiophamaceuticals have been contributed to the efficient to

• Nuclear Medicine and Molecular Imaging
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• 제41권3호
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• pp.258-259
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• 2007

Benign metastasizing leiomyoma(BML) is a rare condition affecting women with a history of having undergone hysterectomy or myomectomy for a benign uterine fibroid, that is found to have metastasized to extrauterine sites, usually many years after hysterectomy. 1,2) Patient with BML almost always asymptomatic, although if the lesions are large enough, they can cause compressive symptoms. Among several hypothesis of pathogenesis, most plausible theory is that these tumors represent a true metastatic lesion but are very low-grade sarcoma. 3) Because the tumor is responsive to estrogen, menopause and pregnancy have slowed the growth of these lesion 4) and it seems reasonable to perform hysterectomy in patients with a uterine mass and, at the same time, perform oophorectomy for hormonal control. BML is an unusual cause of diffuse pulmonary nodules which should be considered in females with unexplained nodules and a history of surgery for uterine leiomyoma.

• 천문학회보
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• 제41권1호
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• pp.39.2-39.2
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• 2016

The central regions of barred-spiral galaxies contain interesting gaseous structures such as dust lanes located at the leading side of the bar and nuclear rings that are sites of intense star formation. Our previous studies showed how gas structures form under the influence of a non-axisymmetric bar potential and temporal/spatial behavior of the star formation in nuclear rings. However, previous works were limited to 2-dimensional infinitesimally-thin, unmagnetized and isothermal disks. To study effects of cooling/heating, vertical motions of gas structures and magnetic field, we use Mesh-Free magneto-hydrodynamic simulation code GIZMO. We find that temporal variations of the star formation rates in the nuclear ring in the three-dimensional model are overall similar those in the previous two-dimensional results, although the former shows more violent small-scale fluctuations near the early primary peak. We will present our recent results about evolution of gaseous structures and star formation rate compare with results of previous studies.

• 대한핵의학회지
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• 제21권2호
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• pp.213-219
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• 1987

Although the exact mechanism is not clearly understood yet, there were examples of the uptake of radiopharmaceuticals to the soft tissue lesions with $^{99m}Technetium$ methylene diphosphonate bone scan. Recently, we experienced two cases of neuroblastoma of which primary sites were imaged with $^{99m}Tc-MDP$ bone scan preoperatively and could make the diagnosis. So, we report here that $^{99m}Tc-MDP$ bone scan is the reasonable method not only to find out the bone metastasis, but also to diagnose the neuroblastoma preoperatively.

• Journal of Plant Biology
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• 제23권1호
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• pp.3-10
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• 1980

Effects of thermal effluents on the marine algal communities were investigated with the quadrat method during June, 1977-December, 1978, at the intertidal zone of Kori Nuclear Power Plant, Southeast Coast of Korea. As a result, both the number of algal species occurred in quadrat (50$\times$50cm) and the total coverage were observed to be decreased in June, 1978, at three sites near the discharge point compared with those of previous year but being recovered afterwards. The representative dominant species at the coast of Kori Nuclear Power Plant were, on the whole, Corallina pilulifera, Pachymeniopsis elliptica, and Chondrus ocellatus. Among the species, the coverage of Corallina pilulifera appeared to be rather increased, while the vegetation of Chondria crassicaulis was found to be decreased particularly in 1978. Total 102 species (3 blue-green, 16 green, 30 brown, and 53 red algae) of marine algae were identified in this study. Among them 71 species were common to 133 species reported by previous investigators during 1969-1970.

• 환경생물
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• 제27권1호
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• pp.114-123
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• 2009

1997$\sim$2006년의 10년간 계절별로 동해안에 위치한 3개 원자력발전소(울진, 월성 및 고리)의 배수구 부근 방파제와 대조구에서 산호말류의 종조성과 생물량을 조사하였다. 조사를 통하여 13종의 산호말류가 관찰되었으며, 작은구슬산호말, 고리마디게발, 참산호말 및 잘피껍데기의 4종은 거의 모든 조사정점에서 지난 10년간 50% 이상의 출현빈도를 보이는 보편 종으로 밝혀졌다. 조사정점별로는 발전소 방파제에서 10$\sim$12종이 출현하고 대조구에서 8$\sim$12종이 관찰되어 출현종수는 정점간에서 뚜렷한 차이를 보이지 않았다. 산호말류의 단위면적당 평균 생물량은 0$\sim$2,530 g dry wt m$^{-2}$의 넓은 범위로 나타났으며, 생물량으로 본 우점종은 공통적으로 작은구슬산호말이었다. 배수구 부근 방파제 구역에서 측정된 산호말류의 단위면적당 생물량은 대조구의 생 물량보다 전반적으로 많았다. 단위면적당 해조류 생물량 가운데 산호말류가 차지하는 구성비율의 평균은 0$\sim$95.0%의 넓은 범위로 나타났으며, 발전소 방파제 구역에서 대조구보다 전반적으로 높게 나타났다. 특히 울진원자력발전소의 경우 수온이 높은 여름에 생물량이 가장 많고 구성비율 역시 가장 높게 나타나면서 다른 계절과 유의한 차이를 보였다. 이와 같은 발전소 주변 산호말류의 독특한 시 공간적 분포 양식은 조사정점간의 국지적 수온 차이와 무관하지 않은 것으로 추정된다.

• 환경생물
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• 제29권4호
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• pp.373-378
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• 2011

Our aim was to investigate the genotoxicity of ambient air in the Krak$\acute{o}$w area after Fukushima Nuclear Power Plant (NPP) accident and compare with results from Chernobyl fallout. For the detection of ambient air genotoxicity the technique for screening gene mutation frequency in somatic cells of the $Tradescantia$ stamen hairs ($Trad$-SH assay) was used. Since 11th of March 2011 (Fukushima NPP accident), several pots containing at least 15 shoots of bioindicating plants were exposed to ambient air at 2 sites in the Krak$\acute{o}$w surrounding area, one in the city center, and about 100 pots in a control site (in the glasshouse of the Institute of Nuclear Physics) Continuous screening of mutations was performed. Progenies of 371,090 cells exposed were analyzed. Mutation frequency obtained in the first 10 days has shown a mean control level (GMF*100=$0.06{\pm}0.01$). At scoring period related to influence of a potential Fukushima fallout, a significant increase of gene mutation frequencies above the control level was observed at each site in the range, 0.10~0.33 depending on the location, (mean value for all sites GMF*100=$0.19{\pm}0.05$) that was associated with a strong expression of toxic effects. In the reported studies following the Chernobyl NPP accident monitoring $in$ $situ$ of the ambient air genotoxicity was performed in the period since April $29^{th}$ till June $3^{rd}$ 1986 also with Trad-SH bioindicator. In general, mutation frequency increases due to Chernobyl fallout(GMF*100=$0.43{\pm}0.02$) were corresponding to fluctuation of radioactivity in the air reported from physical measures, and to published reports about increase in chromosome aberration levels. Although, recent data obtained from monitoring of the ambient air quality in the Krak$\acute{o}$w and surroundings are lower when compared to results reported after Chernobyl NPP accident, though results express a significant increase above the control level and also are corresponding with increased air radioactivity reported from physical measurements. Statistically significant in comparison to control increase in gene mutation rates and more prolonged than that after Chernobyl fallout increase of GMF was observed during the period following the Fukushima NPP failure.

• Nuclear Medicine and Molecular Imaging
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• 제42권1호
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• pp.79-80
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• 2008

Including malignancy, various disease can show abnormal uptake in bone marrow. We report a case of non-specific inflammatory FDG uptake in bone marrow mimicking malignancy. A 35-year old woman with fever of unknown origin (FUO) underwent $^{18}F$-FDG PET/CT to find out fever $^{18}F$-FDG and unknown malignancy. $^{18}F$-FDG was injected and imaged 1hr after injection with Discovery ST (GE, USA), $^{18}F$-FDG PET/CT whole body image showed abnormal uptake in lower extremities (Fig. 1). MRI and biopsy was also done in the sites of abnormal uptake. PET and MRI suspect malignancy (Fig. 2, 3), but biopsy result was non-specific inflammatory process (Fig. 4). The patient was improved her clinical condition after antibiotics therapy.

• Nuclear Engineering and Technology
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• 제38권2호
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• pp.139-146
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• 2006

An experimental study was performed to evaluate the effects of surface coating and an enhanced insulation structure on the downward facing boiling process and the critical heat flux on the outer surface of a hemispherical vessel. Steady-state boiling tests were conducted in the Subscale Boundary Layer Boiling (SBLB) facility using an enhanced vessel/insulation design for the cases with and without vessel coatings. Based on the boiling data, CHF correlations were obtained for both plain and coated vessels. It was found that the nucleate boiling rates and the local CHF limits for the case with micro-porous layer coating were consistently higher than those values for a plain vessel at the same angular location. The enhancement in the local CHF limits and nucleate boiling rates was mainly due to the micro-porous layer coating that increased the local liquid supply rate toward the vaporization sites on the vessel surface. For the case with thermal insulation, the local CHF limit tended to increase from the bottom center at first, then decrease toward the minimum gap location, and finally increase toward the equator. This non-monotonic behavior, which differed significantly from the case without thermal insulation, was evidently due to the local variation of the two-phase motions in the annular channel between the test vessel and the insulation structure.