• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.7
• /
• pp.2904-2918
• /
• 2020

With a huge demand for replicated content on the Internet, a new networking paradigm called information-centric networking (ICN) has been introduced for efficient content dissemination. In ICN, named content is distributed over the network cache and it is accessed by name instead of a location identifier. These aspects allow users to retrieve content from any of the nodes having replicas, and consequently 1) network resources are more efficiently utilized by avoiding redundant transmission and 2) more scalable services are provided by distributing server loads. However, in-network caching in ICN brings about a new type of security issues, called content poisoning attacks, where fabricated content is located in the network cache and interferes with the normal behavior of the system. In this paper, we look into the problems of content poisoning in ICN and discuss security architectures against them. In particular, we reconsider the state-of-the-art schemes from the perspective of feasibility, and propose a practical security architecture.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.7
• /
• pp.1590-1598
• /
• 1997

The paper first introduces the new concept of potential diversity and signal decomposability, which establish a foundaton to generalize the existing concepts of path and frequency diversities. Then it presents a new DS/CDMA system called chip-spreading OCDM system, which is an embodiment of the petential diversity concept that combines the path diversity of the DS/CDMA system and the frequency diversity of the OFDM/CDMA system. In the chip-spreading OCDM system the chip sequences in each symbol interval are first converted into aralled streams, which then simultaneously modulate different orthogonal Walsh basis functions. In the receiver, the received signal is matched to each extended basis-function which is the union of the transmitter basis-functions and their delayed replicas, and the matched-filtered chip samples are combined together after individual channel compensation. The conventional DS/CDMA system using the maximal ratio combining. In addition, it effectively resolves the high PAR and high sensitivity to frequency offset problems which are critical in multi-carrier systems.

• Journal of Technologic Dentistry
• /
• v.38 no.3
• /
• pp.185-191
• /
• 2016

Purpose: The purpose of this study were to evaluate the quality of dental prostheses printed by 3-dimensional printing system. Methods: Mater model was prepared and ten study models were fabricated. Ten single crowns were printed by 3D-printing system(Resin group) and another ten single crowns using casting method were manufactured(Metal group). The marginal adaptation of single crowns were measured using by silicone replica technique. Silicone replicas were sectioned four times. The marginal adaptations were evaluated using by digital microscope. Statistical analyses were performed with Mann-Whitney test(${\alpha}=0.05$). Results: $Mean{\pm}standard$ deviations of all marginal adaptations were $92.1(20.0){\mu}m$ for Metal group and $69.7(12.3){\mu}m$ for Resin group. Two groups were no statistically significant differences(p>0.05). Conclusion: Marginal adaptation of single crowns printed by 3D-printing system were ranged within the clinical recommendation.

• Wind and Structures
• /
• v.16 no.2
• /
• pp.193-211
• /
• 2013

This paper presents results from a wind tunnel study that examined the drag coefficient and wind flow over an asymmetric wave train immersed in turbulent boundary layer flow. The modeled wavy surface consisted of eight replicas of a statistically-valid hurricane-generated wave, located near the coast in the shoaling wave region. For an aerodynamically rough model surface, the air flow remained attached and a pronounced speed-up region was evident over the wave crest. A wavelength-averaged drag coefficient was determined using the wind profile method, common to both field and laboratory settings. It was found that the drag coefficient was approximately 50% higher than values obtained in deep water hurricane conditions. This study suggests that nearshore wave drag is markedly higher than over deep water waves of similar size, and provides the groundwork for assessing the impact of nearshore wave conditions on storm surge modeling and coastal wind engineering.

• Applied Microscopy
• /
• v.25 no.2
• /
• pp.53-64
• /
• 1995

This study was designed to investigate the morphological alterations of zonula occludens, macula adherences and gap junctions between the hepatocytes in the fasting conditions. Animals (Sprague Dawley, $250{\sim}280g$) were divided into two groups: normal and fasting. The latter were fasted for eight days prior to sampling. Liver tissues were sectioned and replicated after freeze fracturing for the transmission electron microscopy. In the normal rat liver, the interhepatocellular space at the area of some zonula occludens appeared to be widened in thin sections. On the freeze fracture replicas., the zonula occludens appeared as an anastomosing network of $2{\sim}4$ strands or grooves on P or E faces. Free ends and fragments of the strands were observed. In the rat fasted for eight days, the hepatocytes were diminished in size and the organelles were decreased in number and size. The intercellular space was wide at many areas of zonula occludens in thin section. On the freeze fracture replicas, the zonula occludens showed diminution or disappearence of anastomosing network of strands or grooves. Free ends and small fragments of the strands or grooves were frequently encountered. The macula adherens was markedly increased in number in thin sections, although they could not be found on the freeze fracture replicas. The gap junctions were increased in number in thin sections. Small aggregations of the intramembranous particles appeared with larger ones on the freeze fracture replica. The evidences may suggest the followings: (1) The disassembly of zonula occludens in the fasting states is led from the diminished mechanical stress on the luminal surface of bile canaliculus with the impaired secretion of bile components from the hepatocytes. (2) The increase of macula adherens is necessary to maintain the liver parenchyma integrity in the fasting state which leads the hepatocyte to be diminished and finally the intercellular space to be separated. (3) The rise in both number and size of gap junctions is owing to the need of increasing intercellular communication between the hepatocytes during the fasting. (4) The alteration of zonula occludens is easily led by the physiological condition of hepatocytes even in the normal ones.

• Computers and Concrete
• /
• v.2 no.3
• /
• pp.239-248
• /
• 2005

The article presents the results of examination of the fractal dimension D of concrete specimen fracture surfaces obtained in fracture toughness tests. The concretes were made from three different types of coarse aggregate: gravel, dolomite and basalt aggregate. Ordinary concretes (C40) and high-performance concretes (HPC) were subjected to testing after 7, 14, 28 and 90 days of curing, respectively. In fracture toughness and compressive tests, different behaviours of concretes were found, depending on the type of aggregate and class of concrete (C40, HPC). A significant increase in the strength parameters tested occurred also after a period of 28 days (up to the $90^{th}$ day of curing) and was particularly large for concretes C40. Fractal examinations performed on fracture replicas showed that the fractal dimension D was diverse, depending on the coarse aggregate type and concrete class being, however, statistically constant after 7 and 14 days for respective concretes during curing. The fractal dimension D was the greater, the worse strength properties were possessed by the concrete. A cross-grain crack propagation occurred in that case, due to weak cohesion forces at the coarse aggregate/mortar interface. A similar effect was observed for C40 and HPC made from the same aggregate. A greater dimension D was exhibited by concretes C40, in which case the fracture was easier to form compared with high-performance concretes, where, as a result of high aggregate/mortar cohesion forces, the crack propagation was of inter-granular type, and the resulted fracture was flatter.

• Journal of the Korea Society of Computer and Information
• /
• v.10 no.6 s.38
• /
• pp.37-46
• /
• 2005

In Processing many operations based on distributed environment, it is very important to support the reliability of resources. Providers of resources generally adapt the structure of server-replication to support the reliability of services. Tn server side, it maintains replicas. duplicated server objects. In the structure of this replication, service of stable replica is very important. Therefore the structure to diagnosis the fault of such replica is required. In this Paper, we suggested an effective PUSH fault management algorithm based on PUSH monitoring style of CORBAto overcome weak points of the PULL monitoring style of the replication management system in the distributed object system. Outcomes of the suggested PUSH fault monitoring style were better than other system. We confirmed valuable result in the workloads and timeout-rates.

• Journal of the Korean Geographical Society
• /
• v.32 no.4
• /
• pp.543-548
• /
• 1997

New technologie of information and interaction create ambiguous, multifaceted relationships between concepts and realities that once seemed clear and simple. The acvent of cyberspace implies the existence of cyberplaces and relationships among cyberspace and places that could be as or more complex then those that exist among the spaces and places of the non-digital world. Virtual reality-the current uses of infomation technologies to create replicas of places and processes in the world-offers a point of exploring such relationships. But more penetrating insights become evident in the examination of real virtuality-the uses of information technologies to enhance the experience of places in the world. Real virtuality offers geographers a variety of innovative and powerful tools for augmenting the effectiveness and domain of their craft. Widespread use of real virtuality by geograpgers will alter their use of data, methods, and theory in research, teaching, and practice.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.4 no.3
• /
• pp.273-288
• /
• 2010

In this paper, we propose a cooperative multi-relay scheme for a secondary system to achieve spectrum access along with a primary system. In the primary network, a primary transmitter (PT) transmits the primary signal to a primary receiver (PR). In the secondary network, N secondary transmitter-receiver pairs (ST-SR) selected by a centralized control unit (CCU) are ready to assist the primary network. In particular, in the first time slot, PT broadcasts the primary signal to PR, which is also received by STs and SRs. At STs, the primary signal is regenerated and linearly combined with the secondary signal by assigning fractions of the available power to the primary and secondary signals respectively. The combined signal is then broadcasted by STs in a predetermined order. In order to achieve diversity gain, STs, SRs and PT will combine received replicas of the primary signal, using selection combining technique (SC). We derive the exact outage probability for the primary network as well as the secondary network. The simulation results are presented to verify the theoretical analyses.

• Korean Journal of Medicinal Crop Science
• /
• v.19 no.6
• /
• pp.508-513
• /
• 2011

The bark of the root and stem of Ulmus davidiana var. japonica has been used as a traditional Korean medicine to treat inflammatory disorders. This plant reportedly shows antioxidant, anticancer, and anti-inflammatory effects. In this study, we investigated the protective effects of Ulmus davidiana var. japonica ethanolic extract (UDE) on UVB irradiation-induced wrinkle in hairless mice. We evaluated for their free radical-scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the anti-elastase activities, and for their anti-matrix metalloproteinase-1 (MMP-1) activity in human skin fibroblast cells. In the wrinkle measurement and image analysis of skin replicas, the results showed that UDE significantly inhibited wrinkle formation caused by chronic UVB irradiation. These results suggest that UDE has anti-wrinkle activity.