• Nuclear Engineering and Technology
• /
• 제52권4호
• /
• pp.689-699
• /
• 2020

In this work, new multi-recycling options of TRU nuclides using PWR fuel assemblies comprised of MOX and FCM (Fully Ceramic Micro Encapsulated) fuels are suggested and neutronically analyzed. These options do not use a fully recycling of TRU but a partial recycling where TRUs from MOX fuels are recycled while the ones from FCM fuels are not recycled due to their high consumption rate resulted from high burnup. In particular, additional external TRU feed in MOX fuels for each cycle was considered to significantly increase the TRU consumption rate and the finally selected option is to use external TRU and enriched uranium feed as a makeup for the heavy metal consumption in MOX fuels. This hybrid external feeding of TRU and enriched uranium in MOX fuel was shown to be very effective in significantly increasing TRU consumption rate, maintaining long cycle length, and achieving negative void reactivity worth during recycling.

• Nuclear Engineering and Technology
• /
• 제11권1호
• /
• pp.29-45
• /
• 1979

이 논문에서는 6개의 다른 연료봉 모형을 기준으로 하여 TRIGA Mark-III 연구용 원자로의 핵특성이 자세히 분석되고 있다. 현재 핵연료로 사용하고 있는 FLIP fuel은 연료의 수명을 증진시키기 위해 개발되었던 모형이나, 70%의 고농축이기 때문에 비확산금지조약에 위배되어 수입이 곤란한 실정이다. 따라서 본 논문에서는 FLIP 연료 모형에 대치할 수 있는 다른 연료봉온 찾고 그들의 핵특성을 비교함으로써 앞으로 연료수입계륵을 설립하고자 한다.

• 인지과학
• /
• 제20권2호
• /
• pp.197-223
• /
• 2009

반응 조화설 (Shafir, 1993)은 결정에서 두 대안 중 한 대안의 특징들이 선택이나 거부의 반응과 조화될수록 사람들이 그 대안을 더 택한다고 주장한다. 장단점을 많이 가진 풍부한 대안이 그렇지 않은 보통의 대안보다 더 많이 선택되고 더 많이 거부되어야 한다. 유승민과 이영애(2001)는 이 가설의 예측과 일치하지 않은 결과를 얻었다. 본 연구는 두 대안의 특징들의 제시 방식 그리고 질문 순서를 변화시켜 반응 조화설을 검토하였다. 특징들을 나열하지 않고 문장으로 제시하고 선택 또는 거부 질문을 먼저 제시하였을 때 반응 조화설과의 예측과 상당히 일치하는 결과를 얻었다. 본 연구는 반응 조화설을 검토할 때 선호의 구성 방식이 중요함을 밝혔다. 본 연구의 결과를 최근 연구들과 비교하였다.

• Restorative Dentistry and Endodontics
• /
• 제43권2호
• /
• pp.17.1-17.7
• /
• 2018

Iatrogenic perforations negatively impact the outcome of endodontic treatments. Studies on prognostic factors showed that perforations in the coronal third of the root with periodontal pocket formation have an unfavorable prognosis. A 36-year-old female was referred for endodontic evaluation of tooth #13 with a history of an iatrogenic perforation, happened 3 years ago. There was a sinus tract associated with perforation, 10 mm probing on the mesial and mesio-palatal, bleeding on probing, radiolucent lesion adjacent to the perforation and complete resorption of the interdental bone between teeth #13 and #12. After the treatment options were discussed, she chose to save the tooth. The tooth was accessed under rubber dam isolation, the perforation site was cleaned and disinfected using 0.5% sodium hypochlorite and sealed with calcium-enriched mixture cement. Eighteen months after treatment the tooth was functional and asymptomatic. The probing depths were normal without bleeding on probing. Radiographically, the interdental crestal bone formed between teeth #13 and #12. Despite all negative prognostic factors in this case (i.e., perforations in the coronal third, pocket formation, and radiolucent lesion), healing was unexpectedly achieved via non-surgical repair of the perforation. Further research on biological aspects of healing in the periodontium following iatrogenic perforations are recommended.

• BMB Reports
• /
• 제56권4호
• /
• pp.258-264
• /
• 2023

As a high-grade soft-tissue sarcoma (STS), undifferentiated pleomorphic sarcoma (UPS) is highly recurrent and malignant. UPS is categorized as a tumor of uncertain differentiation and has few options for treatment due to its lack of targetable genetic alterations. There are also few cell lines that provide a representative model for UPS, leading to a dearth of experimental research. Here, we established and characterized new cell lines derived from two recurrent UPS tissues. Cells were obtained from UPS tissues by mincing, followed by extraction or dissociation using enzymes and culture in a standard culture environment. Cells were maintained for several months without artificial treatment, and some cell clones were found to be tumorigenic in an immunodeficient mouse model. Interestingly, some cells formed tumors in vivo when injected after aggregation in a non-adherent culture system for 24 h. The tissues from in vivo study and tissues from patients shared common histological characteristics. Pathways related to the cell cycle, such as DNA replication, were enriched in both cell clones. Pathways related to cell-cell adhesion and cell-cell signaling were also enriched, suggesting a role of the mesenchymal-to-epithelial transition for tumorigenicity in vivo. These new UPS cell lines may facilitate research to identify therapeutic strategies for UPS.

• Nuclear Engineering and Technology
• /
• 제48권2호
• /
• pp.351-359
• /
• 2016

The Korean Prototype Gen-IV sodium-cooled fast reactor (PGSFR) is supposed to be loaded with a relatively-costly low-enriched U fuel, while its envisaged transuranic fuels are not available for transmutation. In this work, the U-enrichment reduction by improving the neutron economy is pursued to save the fuel cost. To improve the neutron economy of the core, a new reflector material, PbO, has been introduced to replace the conventional HT9 reflector in the current PGSFR core. Two types of PbO reflectors are considered: one is the conventional pin-type and the other one is an inverted configuration. The inverted PbO reflector design is intended to maximize the PbO volume fraction in the reflector assembly. In addition, the core radial configuration is also modified to maximize the performance of the PbO reflector. For the baseline PGSFR core with several reflector options, the U enrichment requirement has been analyzed and the fuel depletion analysis is performed to derive the equilibrium cycle parameters. The linear reactivity model is used to determine the equilibrium cycle performances of the core. Impacts of the new PbO reflectors are characterized in terms of the cycle length, neutron leakage, radial power distribution, and operational fuel cost.

• Nuclear Engineering and Technology
• /
• 제55권6호
• /
• pp.2288-2297
• /
• 2023

Current designs of both large reactor units and small modular reactors utilize a nuclear fuel with increasing enrichment. This increasing demand for better nuclear fuel utilization is a challenge for nuclear fuel handling facilities. The operation with higher enriched fuels leads to reduced reserves to legislative and safety criticality limits of spent fuel transport, storage and final disposal facilities. Design changes in these facilities are restricted due to a boron content in steel and aluminum alloys that are limited by rolling, extrusion, welding and other manufacturing processes. One possible solution for spent fuel pools and casks is the burnup credit method that allows decreasing very high safety margins associated with the fresh fuel assumption in spent fuel facilities. This solution can be supplemented or replaced by an alternative solution based on placing the neutron absorber material directly into the fuel assembly, where its efficiency is higher than between fuel assemblies. A neutron absorber permanently fixed in guide tubes decreases system reactivity more efficiently than absorber sheets between the fuel assemblies. The paper summarizes possibilities of fixed neutron absorbers for various nuclear fuel and fuel handling facilities. Moreover, an absorber material was optimized to propose alternative options to boron. Multiple effective absorbers that do not require steel or aluminum alloy compatibility are discussed because fixed absorbers are placed inside zirconium or steel cladding.

• Genomics & Informatics
• /
• 제21권2호
• /
• pp.22.1-22.15
• /
• 2023

Kidney renal clear cell carcinoma (KIRC) is one of the most aggressive cancer type of the urinary system. Metastatic KIRC patients have poor prognosis and limited therapeutic options. Ankyrin 3 (ANK3) is a scaffold protein that plays important roles in maintaining physiological function of the kidney and its alteration is implicated in many cancers. In this study, we investigated differential expression of ANK3 in KIRC using GEPIA2, UALCAN, and HPA databases. Survival analysis was performed by GEPIA2, Kaplan-Meier plotter, and OS-kirc databases. Genetic alterations of ANK3 in KIRC were assessed using cBioPortal database. Interaction network and functional enrichment analyses of ANK3-correlated genes in KIRC were performed using GeneMANIA and Shiny GO, respectively. Finally, the TIMER2.0 database was used to assess correlation between ANK3 expression and immune infiltration in KIRC. We found that ANK3 expression was significantly decreased in KIRC compared to normal tissues. The KIRC patients with low ANK3 expression had poorer survival outcomes than those with high ANK3 expression. ANK3 mutations were found in 2.4% of KIRC patients and were frequently co-mutated with several genes with a prognostic significance. ANK3-correlated genes were significantly enriched in various biological processes, mainly involved in peroxisome proliferator-activated receptor (PPAR) signaling pathway, in which positive correlations of ANK3 with PPARA and PPARG expressions were confirmed. Expression of ANK3 in KIRC was significantly correlated with infiltration level of B cell, CD8+ T cell, macrophage, and neutrophil. These findings suggested that ANK3 could serve as a prognostic biomarker and promising therapeutic target for KIRC.

• Nuclear Engineering and Technology
• /
• 제45권6호
• /
• pp.731-744
• /
• 2013

Energy security is a topic of high importance to many countries throughout the world. Countries with access to vast energy supplies enjoy all of the economic and political benefits that come with controlling a highly sought after commodity. Given the desire to diversify away from fossil fuels due to rising environmental and economic concerns, there are limited technology options available for baseload electricity generation. Further complicating this issue is the desire for energy sources to be sustainable and globally scalable in addition to being economic and environmentally benign. Nuclear energy in its current form meets many but not all of these attributes. In order to address these limitations, TerraPower, LLC has developed the Traveling Wave Reactor (TWR) which is a near-term deployable and truly sustainable energy solution that is globally scalable for the indefinite future. The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared to conventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowest cost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferation concerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generation infrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need to be built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costs and 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel. With advanced technological development and added cost, TWRs are also capable of reusing both their own used fuel and used fuel from LWRs, thereby eliminating the need for enrichment in the longer term and reducing the overall societal waste burden. This paper describes the origins and current status of the TWR development program at TerraPower, LLC. Some of the areas covered include the key TWR design challenges and brief descriptions of TWR-Prototype (TWR-P) reactor. Selected information on the TWR-P core designs are also provided in the areas of neutronic, thermal hydraulic and fuel performance. The TWR-P plant design is also described in such areas as; system design descriptions, mechanical design, and safety performance.

• 지능정보연구
• /
• 제29권4호
• /
• pp.347-373
• /
• 2023

최근 기업의 지속가능한 성장을 이끄는 ESG(Environmental, Social, and Governance) 관리의 중요성이 강조되고 있다. 이에, 본 연구는 기업과 일반 대중 간의 ESG에 대한 인식 차이를 실증적으로 밝히고, ESG 정책의 시행을 방해하는 부정적인 여론과 그 배경을 규명하는 것을 목표로 한다. 이를 위해, LDA(Latent Dirichlet Allocation) 토픽모델링, JST(Joint Sentiment Topic Modeling) 및 의미연결망분석 기법을 사용하여 지속가능경영보고서와 소셜미디어에서의 주요 키워드와 토픽, 그리고 그 연결관계를 분석하였다. 또한, ChatGPT를 활용하여, 텍스트마이닝 분석의 결과를 보완하였다. 분석 결과, 기업과 일반 대중 간 ESG에 대한 인식과 중요도에 상당한 차이가 있음을 확인하였다. 구체적으로, 기업들은 위기 관리, 투명한 지배구조, 윤리적 경영 등에 집중하여 신뢰를 구축하려 했으나, '그린워싱', '중대재해', '불매운동' 등과 같은 부정적 키워드가 자주 소셜네트워크에서 등장하여, 많은 대중들이 기업의 ESG 이슈 처리에 대해 의심하고 있음을 확인하였다. 본 연구는 기업, 정부 기관, 고객 및 투자자를 위한 ESG 전략수립에 도움이 될 수 있는 가이드라인을 제공한다는 점에서 의의가 있다.