• Transactions of Materials Processing
• /
• v.24 no.3
• /
• pp.194-198
• /
• 2015

Microstructure based FE simulations were conducted to investigate the micro-mechanical properties of ferrite-martensite dual-phase steels. The FE model was built based on real microstructure images which were characterized by optical microscopy through the thickness direction. Serial sectioned 2D images were converted into semi-2D representative volume elements (RVEs) model. Each RVE model was subjected to a non-proportional loading condition and the mechanical response was analyzed on both the macroscopic and microscopic levels. Macroscopically, stress-strain curves were described under tension-compression and tension-orthogonal tension conditions and the Bauschinger effect was well captured for both loading paths. In addition, micromechanical properties were investigated in the view of stress-strain partitioning and strain localization during monotonic tension.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2015.04a
• /
• pp.139-142
• /
• 2015

데이터 센터에서는 물리적인 규모 증가와는 달리 별도의 처리 없이는 분산처리 프레임워크가 동일한 클러스터 내에서 복수로 동작할 수 없어 전체 환경을 정적으로 분할하여 이들을 배치하는 것이 일반적이다. 그러나 최근 연구에서는 복수의 프레임워크를 한 클러스터 내에서 동작시킴으로써 클러스터의 활용률을 높이는 방향으로 이루어지고 있다. Mesos는 복수의 분산처리 프레임워크를 한 클러스터에서 동작시키기 위한 시스템 중 하나로 각 프레임워크 스케줄러의 스케줄링을 지원하는 단일 Allocation Module을 가진다. Allocation Module은 모든 Slave와 프레임워크 스케줄러들의 요청을 처리하는데, 시스템 규모가 커질수록 Allocation Module으로 집중되는 부하가 증가하여 이에 따른 할당 속도 저하로 정상적인 동작이 불가능해진다. 이 문제를 해결하기 위해 본 논문에서는 Mesos 시스템의 Allocation Module 병렬화를 제안한다. 제안 방식을 통해 Allocation Module의 부하를 분산함과 동시에 Head-of-line Blocking으로 인한 스케줄링 지연 문제를 해결할 수 있을 것이다.

• Nuclear Engineering and Technology
• /
• v.53 no.2
• /
• pp.562-571
• /
• 2021

In this work, we propose a new mechanistic model for the treatment of helium behaviour which includes the description of helium solubility in oxide fuel. The proposed model has been implemented in SCIANTIX and validated against annealing helium release experiments performed on small doped fuel samples. The overall agreement of the new model with the experimental data is satisfactory, and given the mechanistic formulation of the proposed model, it can be continuously and easily improved by directly including additional phenomena as related experimental data become available.

• Ocean and Polar Research
• /
• v.38 no.4
• /
• pp.271-286
• /
• 2016

We evaluate the temperature and salinity fields in the East Sea reproduced by the global ocean reanalysis data using HYbrid Coordinate Ocean Model (HYCOM for short). Temporal correlation of Sea Surface Temperature (SST) change between HYCOM and the Group for High Resolution Sea Surface Temperature (GHRSST) are higher in summer than winter. Though distributions of temperature and salinity in the HYCOM are similar to those from historical data (World Ocean Atlas 2013 V2), salinity in the HYCOM is lower (highter) in the region where the salinity is high (low). Temperature fields in the Ulleung basin of HYCOM are quite similar to those derived from Pressure-recording Inverted Echo Sounder (PIES), such as the correlation coefficient is higher than 0.7. This indicates that the HYCOM represents well the circulation and meso-scale phenomena in the Ulleung basin.

• Structural Engineering and Mechanics
• /
• v.38 no.6
• /
• pp.803-823
• /
• 2011

In this paper, the three dimensional Parallel Realistic Failure Process Analysis ($RFPA^{3D}$-Parallel) code based on micromechanical model is employed to investigate the bonding behavior in FRP sheet bonded to concrete in single shear test. In the model, the heterogeneity of brittle disordered material at a meso-scale was taken into consideration in order to realistically demonstrate the mechanical characteristics of FRP-to-concrete. Modified Mohr-coulomb strength criterion with tension cut-off, where a stressed element can damage in shear or in tension, was adopted and a stiffness degradation approach was used to simulate the initiation, propagation and growth of microcracks in the model. In addition, a Master-Slave parallel operation control technique was adopted to implement the parallel computation of a large numerical model. Parallel computational results of debonding of FRP-concrete visually reproduce the spatial and temporal debonding failure progression of microcracks in FRP sheet bonded to concrete, which agrees well with the existing testing results in laboratory. The numerical approach in this study provides a useful tool for enhancing our understanding of cracking and debonding failure process and mechanism of FRP-concrete and our ability to predict mechanical performance and reliability of these FRP sheet bonded to concrete structures.

• Ocean and Polar Research
• /
• v.33 no.1
• /
• pp.21-34
• /
• 2011

We determined potential meso-scale benthic-pelagic ecosystem coupling in the north equatorial Pacific by comparing surface chl-a concentration with sediment bacterial abundance and adenosine triphosphate (ATP) concentration (indication of active biomass). Water and sediment samples were latitudinally collected between 5 and $11^{\circ}N$ along $131.5^{\circ}W$. Physical water properties of this area are characterized with three major currents: North Equatorial Current (NEC), North Equatorial Count Current (NECC), and South Equatorial Current (SEC). The divergence and convergence of the surface water occur at the boundaries where these currents anti-flow. This low latitude area ($5{\sim}7^{\circ}N$) appears to show high pelagic productivity (mean phytoplankton biomass=$1266.0\;mgC\;m^{-2}$) due to the supplement of high nutrients from nutrient-enriched deep-water via vertical mixing. But the high latitude area ($9{\sim}11^{\circ}N$) with the strong stratification exhibits low surface productivity (mean phytoplankton biomass=$603.1\;mgC\;m^{-2}$). Bacterial cell number (BCN) and ATP appeared to be the highest at the superficial layer and reduced with depth of sediment. Latitudinally, sediment BCN from low latitude ($5{\sim}7^{\circ}N$) was $9.8{\times}10^8\;cells\;cm^{-2}$, which appeared to be 3-times higher than that from high latitude ($9{\sim}11^{\circ}N$; $2.9{\times}10^8\;cells\;cm^{-2}$). Furthermore, sedimentary ATP at the low latitude ($56.2\;ng\;cm^{-2}$) appeared to be much higher than that of the high latitude ($3.3\;ng\;cm^{-2}$). According to regression analysis of these data, more than 85% of the spatial variation of benthic microbial biomass was significantly explained by the phytoplankton biomass in surface water. Therefore, the results of this study suggest that benthic productivity in this area is strongly coupled with pelagic productivity.

• Korean Journal of Food Science and Technology
• /
• v.31 no.1
• /
• pp.224-230
• /
• 1999

The ddh gene encoding meso-DAP-dehydrogenase (DDH) involved in the dehydrogenase pathway is essential for high-level lysine production in Brevibacterium lactofermentum. To investigate its influence on lysine production by overexpression of the ddh gene in a lysine-producing B. lactofermentum, recombinant plasmid pRK1 and pRK31 containing the ddh gene of B. lactofermentum were constructed and they were introduced into B. lactofermentum by electroporation. Multiple copies of pRK1 and pRK31 caused 7-fold and 14-fold increase of DDH activity in B. lactofermentum cell extracts, respectively. As determined in shake flask fermentation, lysine production of B. lactofermentum harboring pRK1 or pRK31 was 22% or 19% higher than that of the control, respectively.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.20 no.1
• /
• pp.13-24
• /
• 2017

This study is to provide basic data on ecology and morpho-pedo milieu by analyzing diatom and grain size of Mt. Jeombong forest wetland. Sample was collected from 6 points and named sample 943, 932, 885, 881A, 881b, 849. Sample 934 could not identify diatom, and the soil layer was colluvium deposited by mass-movement process. Layer of sample 932 was developed in the lower velocity environment, and presence frequence of complete diatom was very low. Hydrological situation of sample 855 was analysed in oligosaprobien environments. Sample 881A was meso-saprobic environments, velocity was slow area that inhabit musci bryopsida and sphaerocarpus. Sample 881B was acidic wetland in oligosaprobien environments. Sample 849 was analysed in oligosaprobien environments. The results of soil and diatom analysis are well reflect on wet environments of mountain wetlands and also it will expected to be in the help of environmental changes study of mountain wetlands.

• Transactions of the Korean hydrogen and new energy society
• /
• v.24 no.4
• /
• pp.320-325
• /
• 2013

TUnitized reversible fuel cells (URFC) combine the functionality of a fuel cell and electrolyzer in one unitized device. For a URFC with proton exchange membrane, a titanium (Ti)-felt is applied to the gas diffusion layer (GDL) substrate at the oxygen electrode, and additionally titanium (Ti)-powders and TiN-powders are loaded in the GDL substrate as a micro porous layer (MPL). Double porous layer with TiN MPL was not acceptable for the URFC because both of fuel cell performance and electrolysis performance are degraded. The double porous layer with Ti-powder loading in the Ti-felt substrate influence rearly for the electrolysis performance. In contrast, the change of pore-size distribution brings a significant improvement of fuel cell performance under fully humidification conditions. This fact indicates that the hydrophobic meso-pores in the GDL play an important role for mass transport.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.21 no.3
• /
• pp.403-412
• /
• 2018

In this study, a three-dimensional variational(3DVAR) data assimilation system was developed for the operational numerical weather prediction(NWP) system at the Republic of Korea Air Force Weather Group. The Air Force NWP system utilizes the Weather Research and Forecasting(WRF) meso-scale regional model to provide weather information for the military service. Thus, the data assimilation system was developed based on the WRF model. Experiments were conducted to identify the nested model domain to assimilate observations and the period appropriate in estimating the background error covariance(BEC) in 3DVAR. The assimilation of observations in domain 2 is beneficial to improve 24-h forecasts in domain 3. The 24-h forecast performance does not change much depending on the estimation period of the BEC in 3DVAR. The results of this study provide a basis to establish the operational data assimilation system for the Republic of Korea Air Force Weather Group.