• Advances in aircraft and spacecraft science
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• 제6권6호
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• pp.479-495
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• 2019

Periodic cellular core structures included in sandwich panels possess good stiffness while saving weight and only lately their potential to act as passive vibration filters is increasingly being studied. Classical homogeneous honeycombs show poor vibracoustic performance and only by varying certain geometrical features, a shift and/or variation in bandgap frequency range occurs. This work aims to investigate the vibration filtering properties of the AUXHEX "hybrid" core, which is a cellular structure containing cells of different shapes. Numerical simulations are carried out using two different approaches. The first technique used is the harmonic analysis with commercially available software, and the second one, which has been proved to be computationally more efficient, consists in the Wave Finite Element Method (WFEM), which still makes use of finite elements (FEM) packages, but instead of working with large models, it exploits the periodicity of the structure by analysing only the unit cell, thanks to the Floquet-Bloch theorem. Both techniques allow to produce graphs such as frequency response plots (FRF's) and dispersion curves, which are powerful tools used to identify the spectral bandgap signature of the considered structure. The hybrid cellular core pattern AUXHEX is analysed and results are discussed, focusing the investigation on the possible spectral bandgap signature heritage that a hybrid core experiences from their "parents" homogeneous cell cores.

• Journal of Magnetics
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• 제7권3호
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• pp.101-105
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• 2002

MRAM (Magnetoresistive Random Access Memory) is a promising candidate for a universal memory that meets all application needs with non-volatile, fast operational speed, and low power consumption. The simplest architecture of MRAM cell is a series of MTJ (Magnetic Tunnel Junction) as a data storage part and MOS transistor as a data selection part. This paper is for testing the actual electrical parameters to adopt MRAM technology in the semiconductor based memory device. The discussed topics are an actual integration of MRAM core cell and its properties such as electrical tuning of MOS/MTJ for data sensing and control of magnetic switching for data writing. It will be also tested that limits of the MRAM technology for a high density memory.

• Nuclear Engineering and Technology
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• 제34권3호
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• pp.250-258
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• 2002

This Paper is to apply the well-established coarse mesh finite difference(CMFD) method to the method of characteristics(MOC) transport calculation as an acceleration scheme. The CMFD problem is first formulated at the pin-cell level with the multi-group structure To solve the cell- based multi-group CMFD problem efficiently, a two-group CMFD formulation is also derived from the multi-group CMFD formulation. The performance of the CMFD acceleration is examined for three test problems with different sizes including a realistic quarter core PWR problem. The CMFD formulation provides a significant reduction in the number of ray tracings and thus only about 9 ray tracing iterations are enough for the realistic problem. In computing time, the CMFD accelerated case is about two or three times faster than the coarse-mesh rebalancing(CMR) accelerated case.

• 생명과학회지
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• 제16권5호
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• pp.828-833
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• 2006

옥수수 (Zea mays L.) 꽃은 암술 세포사멸과 수술 세포 성장정지 등을 통하여 양성상태에서 단성 상태로 성결정 과정을 완성한다. 본 논문에서는 옥수수 성 결정 동안 세포주기 유전자들의 시간적, 공간적 발현조절을 조사하였다. 세포주기의 양성조절 인자 즉 cyclin A, cyclin B, cyclin dependent kinase A (CDK A), Mad2 유전자들은 성장하는 암술과 수술에서 높게 발현되는 반면 죽어가는 암술과 성장이 정지되는 수술에서는 이들의 발현이 사라졌다. 이와 반대로, Wee1과 CDK inhibitor (CKI) 같은 세포주기 음성 조절유전자들은 야생형 암꽃과 tasselseed2 돌연변이 수꽃의 성장이 정지하고 있는 수술에서 발현이 증가되었지만, 흥미롭게도, 이들 유전자들은 죽어가는 암술세포에서는 발현되지 않았다. 이들 결과들을 통하여 옥수수 성 결정 과정 중에서 암술 세포사멸과 수술세포 성장정지는 세포주기조절과 밀접한 관계가 있으며, 특히 성장이 정지하는 수술과 죽어가는 암술에서의 음성 세포주기 조절 유전자들의 다른 발현양상은 이 둘의 성 결정 메커니즘이 구별 될 것이라고 사료된다.

• 한국동물생명공학회지
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• 제37권4호
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• pp.239-245
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• 2022

Protein and peptide candidates are screened to apply therapeutic application as a drug. Ensuring that these candidates are delivered and maximized effectiveness is still challenging and a variety of studies are ongoing. As drug delivery system vehicles, cell-penetrating peptide (CPP) can deliver various kinds of cargo into the cell cytosol. In a previous study, we developed Ara27 CPP, which are a zinc knuckle family protein of Arabidopsis, and confirmed internalization in human dermal fibroblasts and human dental pulp stem cells at low concentration with short time treatment condition without any toxicity. Ara27, an amphipathic CPP, could be modified and utilized in the biomedical field excluding the risk of toxicity. Therefore, we would like to confirm the non-toxic induced penetrating ability of Ara27 in various cell lines. The purpose of this study was to screen the cell internalization ability of Ara27 in various cell lines and to confirm Ara27 as a promising core CPP structure. First, Ara27 was screened to confirm non-toxicity concentration. Then, fluorescence-labeled Ara27 was treated on human normal cell lines, cancer cell lines and animal cell lines to identify the cellular internalization of Ara27. Ara27 was well intracellular localized in all cell lines and the intensity of fluorescence was remarkably increased in time pass manner. These results indicate that Ara27 has the potential as a core structure for applications in various drug delivery systems.

• Molecules and Cells
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• 제45권12호
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• pp.923-934
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• 2022

Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have great potential in applications such as regenerative medicine, cardiac disease modeling, and in vitro drug evaluation. However, hPSC-CMs are immature, which limits their applications. During development, the maturation of CMs is accompanied by a decline in their proliferative capacity. This phenomenon suggests that regulating the cell cycle may facilitate the maturation of hPSC-CMs. Aurora kinases are essential kinases that regulate the cell cycle, the role of which is not well studied in hPSC-CM maturation. Here, we demonstrate that CYC116, an inhibitor of Aurora kinases, significantly promotes the maturation of CMs derived from both human embryonic stem cells (H1 and H9) and iPSCs (induced PSCs) (UC013), resulting in increased expression of genes related to cardiomyocyte function, better organization of the sarcomere, increased sarcomere length, increased number of mitochondria, and enhanced physiological function of the cells. In addition, a number of other Aurora kinase inhibitors have also been found to promote the maturation of hPSC-CMs. Our data suggest that blocking aurora kinase activity and regulating cell cycle progression may promote the maturation of hPSC-CMs.

• Nuclear Engineering and Technology
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• 제14권2호
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• pp.86-91
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• 1982

1977년 집합체 cell 중심간의 간격을 53.34cm(162 연료 집합체 저장)에서 36cm(562 연료 집합체저장)로 줄임으로 고리 1호기 부속 기사용 연료 저장 용량을 화장하였다. 확장된 저장 시설에 대하여 Monte Carlo방법을 이용한 KENO-IV코드로 Core Performance Branch에서 제시한 비정상적인 냉각수 밀도 조건에 따라 유효증배계수를 구하였다. KENO-IV결과 밀도 0.1143g/cm에서 최대유효 증배계수 0.9958$\pm$0.0048을 얻었고, 이 값은 US NRC 기준과 CPB기준인 0.98을 초과하므로 새로운 집합체 cell중심간의 간격을 구하였다. 이 과정은 KENO-IV보다 보수적인 결과를 나타내는 확산 코드 KIDD를 이용하여 cell중심간의 간격에 따른 상관 연구로부터 새로운 cell중심간의 간격을 얻었다. 이로부터 현재의 집합체 cell중심 간의 간격 36cm를 43cm 이상으로 늘려야 비정상적인 냉각수 밀도의 감소로 인한 사고의 경우에도 안전함을 알았다.

• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.544-550
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• 2005

To develop a highly efficient mammalian expression vector, a series of vectors were constructed based on the murine cytomegalovirus (MCMV) immediate-early (IE) promoter and human ${\beta}$-globin second intron. The resulting MCMV promoter was several-fold stronger than the HCMV promoter in various mammalian cell lines, such as the NIH3T3, Neuro-2a, 293T, and HT1080 cell lines, and was only slightly weaker than the HCMV promoter in HeLa and CHO cells. The inclusion of the human ${\beta}$-globin second intron behind the MCMV promoter or HCMV promoter markedly enhanced the promoter activity in various mammalian cell lines, and the resultant MCMV/Glo-I expression system was stronger than the HCMV promoter from 4.7- to 11.2-fold in every cell line tested. Also, the MCMV/Glo-I promoter induced a higher level of the VSV-G protein in a transiently transfected 293T cell line, which is useful for the production of recombinant retrovirus and lentivirus vectors.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(1)
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• pp.77-82
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• 1997

The CANDU-6 transition core refuelled from 37-element fuel to CANFLEX-NU fuel has been evaluated by an 100full power day time-dependent fuel-management simulation to find the core compatibility with the CANFLEX fuel loading. The simulation calculations for the transition core were carried out with the RFSP code, provided by the cell averaged fuel properties obtained from the POWDERPUFS-V code. The simulation results were compared with those of the current 37-element fuel loading only. The results show that the CANFLEX-NU fuel bundles will be compatible with the CANDU-6 reactor because the core physics characteristics of CANFLEX-NU fuel are very similar to those of the 37-element fuel bundle.

• 대한기계학회논문집B
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• 제34권4호
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• pp.349-354
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• 2010

연료전지는 환경문제와 천연자원 고갈을 해결할 수 있기 때문에 가장 주목받고 있는 새로운 동력원이다. 본 논문에서는 마이크로 연료전지의 효율을 높이기 위해 다양한 형상에 대해 마이크로 채널에서 수소가스 유동을 수치해석 하였다. 이미 개발된 채널과 새롭게 고안된 채널, 모두 여섯 개의 다른 형상을 가진 채널이 같은 유동 특성과 경계조건으로 수치해석을 수행하였다. 수치해석 결과를 통해 유속, 유동분포, 유동균일성 등이 채널형상에 따라 영향을 많이 받는 것을 알았다. 이에 수소 가스 유동을 고려한 채널형상 최적화를 통해 연료전지의 성능을 향상시키고자 하였다. 수치해석을 통한 최적화된 채널형상을 사용한 PEMFC 실험결과 평균보다 높은 전류밀도를 나타내었다. 그러나 내구성이 낮았다.