• Transactions of the Korean hydrogen and new energy society
• /
• v.32 no.1
• /
• pp.53-62
• /
• 2021

Batch type reduction-oxidation tests were performed to check effects of temperature, pressure, gas velocity, and capacity on reduction characteristics of mass produced particle in a 0.5 MWth chemical looping combustion system. The fuel conversion and the CO2 selectivity increased as the temperature increased and as the gas velocity decreased. However the CO2 selectivity showed the maximum and decreased as the capacity increased because the CO emission increased. The results show that high temperature, low gas velocity and low inert gas concentration are preferable to ensure high reactivity of oxygen carrier in the fuel reactor.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.2 no.4
• /
• pp.61-66
• /
• 2003

An excellent mesh construction is of Importance in yielding good results of finite element analysis. The new mesh generation algorithm, which offsets boundaries inward, was developed on the basis of a looping method. An user interface technique and automatic splitting lines which both divide a given domain into subdomains manually or automatically, were used. In addition, the separation method has advantages to prevent the large scale of element size and to control numbers of nodes and elements. This new mesh generation algorithm was proved in practice.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.11
• /
• pp.2932-2943
• /
• 1994

An efficient approach to the automatic construction of effective quadrilateral finite element meshes for two-dimensional analysis is presented. The procedure is composed of, firstly, an initial mesh generation and, secondly, an h-version of adaptive refinement based on error analysis. As for an initial mesh generation scheme, a modified looping algorithm has been employed. For the adaptive refinement process, an error indicator obtained by computing the residual error of the equilibrium equations in the energy norm with a relaxation factor has been employed. Examples of mesh generation and self-adaptive mesh improvements are given. These example solutions demonstrate that an effective mesh for a given error tolerance can be obtained in a few steps of the analysis processes.

• Journal of Communications and Networks
• /
• v.13 no.4
• /
• pp.385-392
• /
• 2011

A loop can take place in the process of managing tree topology for mobility management of mobile nodes in infrastructure-based mobile ad hoc networks. The formation of a loop degrades an effective bandwidth of the wireless network by passing an identical message repeatedly within the same loop. Therefore, the loop should be resolved to revert the system back to the normal state. In this paper, we propose a simple and novel mechanism that detects and resolves a loop quickly by tracking the depth of trees. The mobility management approach that employs the loop resolution method is evaluated comparatively with the original tree-based one and the hybrid one. It is shown that the proposed approach far outperforms the other approaches, and it is robust against the rapid changes in network topology.

• Molecules and Cells
• /
• v.44 no.12
• /
• pp.883-892
• /
• 2021

Genome-wide chromosome conformation capture (3C)-based high-throughput sequencing (Hi-C) has enabled identification of genome-wide chromatin loops. Because the Hi-C map with restriction fragment resolution is intrinsically associated with sparsity and stochastic noise, Hi-C data are usually binned at particular intervals; however, the binning method has limited reliability, especially at high resolution. Here, we describe a new method called HiCORE, which provides simple pipelines and algorithms to overcome the limitations of single-layered binning and predict core chromatin regions with three-dimensional physical interactions. In this approach, multiple layers of binning with slightly shifted genome coverage are generated, and interacting bins at each layer are integrated to infer narrower regions of chromatin interactions. HiCORE predicts chromatin looping regions with higher resolution, both in human and Arabidopsis genomes, and contributes to the identification of the precise positions of potential genomic elements in an unbiased manner.

• Biomedical Science Letters
• /
• v.29 no.3
• /
• pp.103-108
• /
• 2023

Enhancers are cis-elements to regulate transcription of cell/tissue-specific genes in multicellular organisms. These elements locate in upstream or downstream regions of target genes and are found in a long distance up to 100 Kb in some cases. Transcription factors and coactivators bind to enhancers in a chromatin environment. Enhancers appear to facilitate the transcription of target genes by communicating with promoters and activating them. As transcription activation mechanism of enhancers, chromatin looping between enhancers and promoters, tracking of enhancer activity to promoters along the intervening regions, and movement of enhancers and promoters into transcription condensates have been suggested based on various molecular and cellular biology studies. These mechanisms are likely to act together rather than exclusive each other for gene transcription. Understanding of enhancer action mechanism may provide a way to regulate the transcription of cell/tissue-specific genes relating with aging or various diseases.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 2001.11a
• /
• pp.93-98
• /
• 2001

• Journal of Internet Computing and Services
• /
• v.2 no.1
• /
• pp.1-11
• /
• 2001

Though it is proposed to use Petri net or dynamic FSM methods for the generation of test sequences on some specific protocols, those methods ere unavailable on the cases where the protocol allows faults processing or includes paths in looping which cause errors or endless looping by the explosion of states. The determination of test coverage on the protocol software that has been designed and implemented is difficult by the reason of development periods, technical solutions to support and also economical limitations. It is suggested to generate timely protocol software test sequences on the basis of regular expressions covering the functions of protocol. With this regular expression method, the 38 test sequences of Q.2971 protocol has been generated and also minimized the endless looping problem when dynamic test suites are used by simplifying the test path expressions that denotes loops, According to the works, the suggested method is confirmed as simple and easy compare to the other dynamic test sequence generation techniques. Moreover. the method to search an optional test path whether it Is included or not in the regular path expression is reviewed.

• Korean Chemical Engineering Research
• /
• v.47 no.1
• /
• pp.65-71
• /
• 2009

In this study, performance and economic analysis of natural gas/syngas fueled 100 MWth chemical-looping combustion (CLC) combined cycle plant were performed. Net efficiency of both cases was 53~54%, corresponding to previous research. We used Chemical Engineering Plant Cost Index and Guthrie method to evaluate plant cost. For syngas fueled CLC combined cycle plant, the plant cost was higher since lower heating value(LHV) of syngas was lower than that of natural gas and cost of electricity(COE) was also higher since the cost of syngas was higher than that of natural gas. By sensitivity analysis, it was shown that the cost of syngas should be less than 5.3 $/GJ in order to make COE lower than 5.8 ¢/kWh which was COE of natural gas fueled CLC combined cycle plant.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.5
• /
• pp.554-560
• /
• 2017

Reduction reactivity of new oxygen carriers for chemical looping combustion system were investigated using $CH_4$ as a reduction gas in a bubbling fluidized bed reactor and compared with that of former SDN70 oxygen carrier. New oxygen carriers showed good reduction reactivity at different $CH_4$ concentration. N018-R2 particle represented better reactivity than SDN70 at high $CH_4$ concentration. N018-R2 particle showed higher fuel conversion and $CO_2$ selectivity than those of SDN70 particle within the temperature range of $750-900^{\circ}C$. Moreover, attrition loss of N018-R2 particle was almost same with that of SDN70 particle. Consequently, we could select N018-R2 particle as the best oxygen carrier.