• Informatization Policy
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• v.21 no.1
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• pp.35-56
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• 2014

Information and communication technologies(ICT) allow and force people to work anywhere, anytime using remote databases and application systems available in real-time twenty four hours a day and seven days a week. With the real time nature of ICT, individual work is becoming more and more fragmented. Instead of working on a similar task repeatedly, individuals are required to respond to e-mails and inquiries through social networks, work on planning documents, work on presentation documents, work on spreadsheets, input necessary data on company databases, generate necessary reports from the database, run teleconference, etc., all maybe in a day's work. Work fragmentation may impact negatively on productivity as the flow is interrupted, but it may increase the productivity by allowing people to handle multiple tasks in a shorter time period. This study explores the types of work fragmentation and their characteristics. An online survey was administered to collect data about work fragmentation and work characteristics including autonomy, complexity, flexibility, usage of ICT, etc. 300 cases were used in the analysis. Analysis of k-mean cluster indicated four different types of work fragmentation: concentrated, temporally distributed, spatially distributed, and fully fragmented.

• Geomechanics and Engineering
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• v.16 no.2
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• pp.195-204
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• 2018

Based on theories of rock mechanics, rock fragmentation, mechanics of elasto-plasticity, and energy dissipation etc., a method is presented for evaluating the rock fragmentation efficiency by using plastic energy dissipation ratio as an index. Using the presented method, the fragmentation efficiency of rocks with different strengths (corresponding to soft, intermediately hard and hard ones) under indentation is analyzed and compared. The theoretical and numerical simulation analyses are then combined with experimental results to systematically reveal the fragmentation mechanism of rocks under indentation of indenter. The results indicate that the fragmentation efficiency of rocks is higher when the plastic energy dissipation ratio is lower, and hence the drilling efficiency is higher. For the rocks with higher hardness and brittleness, the plastic energy dissipation ratio of the rocks at crush is lower. For rocks with lower hardness and brittleness (such as sandstone), most of the work done by the indenter to the rocks is transferred to the elastic and plastic energy of the rocks. However, most of such work is transferred to the elastic energy when the hardness and the brittleness of the rocks are higher. The plastic deformation is small and little energy is dissipated for brittle crush, and the elastic energy is mainly transferred to the kinetic energy of the rock fragment. The plastic energy ratio is proved to produce more accurate assessment on the fragmentation efficiency of rocks, and the presented method can provide a theoretical basis for the optimization of drill bit and selection of well drilling as well as for the selection of the rock fragmentation ways.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.3
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• pp.29-44
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• 2016

The purpose of this study is to quantitatively and visually analyze the degree of green biotope fragmentation caused by road construction and other development work using FRAGSTATS and GUIDOS tool. Moreover, linking of the endangered species research, we mapped "Biotope Fragmentation Map" of Daejeon-city. The findings of the study are summarized as follows: First, as the result of FRAGSTATS, landscape indices : number of patch(NP), mean patch size (MPS), edge length(TE), mean nearest neighbor distance(MNN), edge shape(LSI) showed meaningful change from fragmentation. Moreover, the result of GUIDOS analysis, middle core-small core-bridge-branch-edge-islet-perforation showed increase of area percentage without large core. Lastly, analysis result of 'Biotope Fragmentation Map' revealed that changing site of large core's size appeared eighteen-site and designated as the special protection area appeared forty-one site. As the result of the two data, overlapping areas that showed both change of core size and revealed special protection areas revealed four site. For example, five species of endangered species appeared on the NO. 4 site in 'Biotope Fragmentation Map'. The findings of this study as summarized above are considered to play an important role in basic data preventing green biotope fragmentation at the planned level from various development work.

• Mass Spectrometry Letters
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• v.7 no.4
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• pp.96-101
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• 2016

To determine the influence of the cationization agent on the collision activated dissociation (CAD) fragmentation behavior of oligosaccharides, the CAD spectra of the singly protonated, sodiated oligosaccharides and singly sodiated and dibenzo-18-crown-6 ether conjugated oligosaccharides were carefully compared. Each of these three different species showed quite different fragmentation spectra. The comparison of singly protonated and sodiated oligosaccharide CAD spectra revealed that different cationization agents affected the cationization agent adduction sites as well as the fragmentation sites within the oligosaccharides. When the mobility of $Na^+$ was limited by the dibenzo-18-crown-6 ether encapsulation agent, the examined linear oligosaccharides showed fragmentation patterns quite different from the unmodified ones. For the dibenzo-18-crown-6 ether conjugated oligosaccharides, the charge-remote fragmentation pathways were more likely to be activated than the chargedirected pathways. This work demonstrates that dibenzo-18-crown-6 ether conjugation can potentially provide a route to selectively activate the charge-remote fragmentation pathways, albeit to a limited extent, in tandem mass spectrometry studies.

• Advanced Composite Materials
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• v.17 no.1
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• pp.75-87
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• 2008

Aerospace structural applications, along with high performance marine and automotive applications, require high-strength efficiency, which can be achieved using metal matrix composites (MMCs). Rotating components, such as jet-engine blades and gas turbine parts, require materials that maximize strength efficiency and metallurgical stability at elevated temperatures. Titanium matrix composites (TMCs) are well suited in such applications, since they offer an enhanced resistance to temperature effects as well as corrosion resistance, in addition to optimum strength efficiency. The overall behavior of the composite system largly depends on the properties of the interface between fiber and matrix. Characterization of the fiber.matrix interface at operating temperatures is therefore essential for the developemt of these materials. The fiber fragmentation test shows good reproducibility of results in determining interface properties. This paper deals with the evaluation of fiber fragmentation characteristics in TMCs at elevated temperature and the results are compared with tests at ambient temperature. It was observed that tensile testing at $650^{\circ}C$ of single-fiber TMCs led to limited fiber fragmentation behavior. This indicates that the load transfer from the matrix to the fiber occurs due to interfacial friction, arising predominantly from mechanical clamping of the fiber by radial compressive residual and Poisson stresses. The present work also demonstrates that composite processing conditions can significantly affect the nature of the fiber.matrix interface and the resulting fragmentation of the fiber.

• Bulletin of the Korean Mathematical Society
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• v.42 no.4
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• pp.855-867
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• 2005

Shattering or disintegration of mass is a well known phenomenon in fragmentation processes first introduced by Kol­mogorov and Filippop and extensively studied by many physicists. Though the mass is conserved in each break-up, the total mass decreases in finite time. We investigate this phenomenon in the n particle system. In this system, shattering can be interpreted such that, in uniformly bounded time on n, order n of mass is located in order o(n) of clusters. It turns out that the tagged particle processes associated with the systems are useful tools to analyze the phenomenon. For the newly defined stochastic shattering based on the above ideas, we derive far sharper conditions of fragmentation kernels which guarantee the occurrence of such a phenomenon than our previous work [9].

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.111-114
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• 2012

The ignition behavior of single coal particles of five kindes of coal with different ranks (low volatile bituminous, low volatile sub-bituminous, high volatile bituminous, lignite) with particle size of $150-200{\mu}m$ was investigated at high heating rate condition. Particles were injected into a laminar flow reactor and the ignition behavior was observed with high speed cinematography. Sub-bituminous were observed to ignite homogeneously; however, low volatile bituminous coal and lignite undergo fragmentation prior to igntion. The observation was analyzed with previous work.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.2
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• pp.81-95
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• 2013

When collapse occurs due to explosion near a tunnel, fragmentation zone should be comprehended quickly to recover the function of the tunnel itself. In this study, a method to interpret explosion behavior and predict the fragmentation zone fast. For this purpose, the various 3D-meshes were generated using SolidWorks and explosion analyses were carried out using AUTODYN. The influence of explosion variables such as source location on fragmentation volume were examined by performing sensitivity analyses. Also, a training database for an artificial neural network analysis had been established and the optimal training model was selected, and the predicted results for fragmentation volume and radius were verified. The suggested method had demonstrated that it could be effective for the fast prediction of fragmentation zone.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.50.1-50.1
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• 2021

Gravitational instability (GI) can produce massive gas giants on wide orbits by fragmentation of protoplanetary disks (PPDs). While most previous works focus on PPDs around solar mass stars, gas giants have been observed in systems with a wide range of stellar masses including M dwarfs. We use the GIZMO code to perform global three-dimensional simulations of self-gravitating disks around low-mass stars. Our models consider heating by turbulent viscosity and stellar irradiation and the β cooling occurring over the dynamical time. We run various models with differing disk-to-star mass ratio q and disk temperature. We find that strongly gravitating disks either produce spirals or undergo fragmentation. The minimum q value for fragmentation is 0.2-0.7, with a smaller value corresponding to a more massive star and/or a smaller disk. The critical q value depends somewhat sensitively on the disk temperature, suggesting that the stellar irradiation is an important factor in determining GI. We discuss our results in comparison with previous work as well as recent ALMA observations.

• Mass Spectrometry Letters
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• v.6 no.4
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• pp.105-111
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• 2015

Sixteen compounds of Neobalanocarpus heimii were successfully identified directly from their plant extract using a triple quadrupole LC-MS/MS system. In order to fulfil the objectives of this work, a series of stilbene oligomers of various degrees of condensation were isolated and their structure are characterized. Out of these, four are resveratrol dimers, three trimers, and nine tetramers. The isolation process was done on a fully automated semi-preparative HPLC system. Their structures were elucidated on the basis of 1D- and 2D-NMR as well as MS data. The mass fragmentation patterns of the compounds were recorded and a retrievable in-house library was built to keep the data. In order to demonstrate the potential of this approach, the polyphenolic crude extract was analysed with the LC-MS/MS system and the MS/MS spectra extracted for each chromatographic peak of interest. The fragmentation patterns were compared with those of anticipated pure compounds that were previously recorded. All compounds were successfully identified. It is therefore believed that the LC-MS/MS potential for dereplication of structurally similar compounds in a crude mixture was thus firmly established.