• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.400-408
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• 2003

Chloride ion inside concrete destroys the so-called passive film surrounding reinforcing bars inside concrete so that the so-called salt attack accelerates corrosion which is the most critical factor for durability as well as structural safety of reinforced concrete structures. Recently, as a solution of the salt attack, the ground granulated blast-furnace slag(GGBFS) have been used as binder or blended cement more extensively. In this paper, characteristics of chloride ion diffusion for the GGBFS concrete, which is known to possess better resistance to damage due to the chloride ion penetration than ordinary portland cement(OPC) concrete possesses, are analyzed and a chloride ion diffusion model for the GGBFS concrete is proposed by modifying an existing diffusion model for the OPC concrete. The proposed model is verified by comparing diffusion analysis results using the model accelerated chloride penetration test results for concrete specimens as well as field test results for an RC bridge pier. Then, an optimal resistance condition to chloride penetration for the GGBFS concrete is obtained according to degrees of fineness and replacement ratios of the GGBFS concrete. The result shows that the GGBFS concrete has better resistance to chloride ion penetration than OPC concrete has and the resistance is more affected by the replacement ratio than the degree of fineness of the GGBFS.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.393-400
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• 2011

The needs for high strength structural materials have recently increased, because construction and cost efficiencies are demanded by the costumers. But, the use of high strength reinforcing bars requires longer development and splice lengths compared to normal strength bars. This restriction may cause reduction in construction efficiency and require more complicated details. The purpose of this paper is to evaluate the bond strength on the rib shape of reinforcing bars to decrease development and splice lengths of high strength reinforcements. Total of 5 simple beam specimens were tested, and the main test variable was a rib shape of reinforcing bars. Test data was analyzed in the viewpoint of bond strength, load-deflection relationship, and crack pattern. Test results indicated that the bond strength of high relative rib area reinforcing bars increased up to 11% compared to normal strength reinforcements. And the improved rib shape reinforcements, which were formed with high and low height rib, increased the bond strength up to 23% even though the relative rib area was same as the high relative rib area reinforcements. Serviceability performances such as deflection number of cracking, and maximum crack width were similar in all specimens, so it is safe to conclude that the improved rib shape reinforcements can be applied to the structural members.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.673-683
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• 2016

In recent years, frequent terror or military attack by explosion, impact, fire accidents have occurred. Particularly, World Trade Center collapse and US Department of Defense Pentagon attack on Sept. 11 of 2001. Also, nuclear power plant incident on Mar. 11 of 2011. These attacks and incidents were raised public concerns and anxiety of potential terrorist attacks on major infrastructures and structures. Therefore, the extreme loading researches were performed of prestressed concrete (PSC) member, which widely used for nuclear containment vessel and gas tank. In this paper, to evaluate the blast resistance capacity and its protective performance of bi-directional unbonded prestressed concrete member, blast tests were carried out on $1,400{\times}1,000{\times}300mm$ for reinforced concrete (RC), prestressed concrete without rebar (PSC), prestressed concrete with rebar (PSRC) specimens. The applied blast load was generated by the detonation of 55 lbs ANFO explosive charge at 1.0 m standoff distance. The data acquisitions not only included blast waves of incident pressure, reflected pressure, and impulse, but also included displacement, acceleration, and strains at steel, concrete, PS tendon. The results can be used as basic research references for related research areas, which include protective design and blast simulation under blast loading.

• Proceedings of the Ginseng society Conference
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• 1988.08a
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• pp.141-146
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• 1988

Dwarf ginseng (Panax trifolius L.) is a member of the ginseng family (Araliaceae). which is indigenous to North America and is distributed from Southern Canada to the Northern United States. In total. nine compounds were isolated from the leaves of Dwarf gineng. Of these. four were identified as flavonoids and five were found to be ginsenosides. Two of the flavonoids were identified to be kaempferol-3. 7-dirhamnoside and kaempferol-3-gluco-7-rhamnoside. Four of the ginsenosides were identified as notoginsenoside-Fe. ginsenoside-Rd. ginsenoside-Rc and $ginsenoside-Rb_1$ The common aglycone of these ginsenosides was shown to be (20S)-protopanaxadiol. The identification of flavonoids and ginsenosides from the root. stem. leaf. flower and fruit of Dwarf ginseng was detected by Two-Dimensional Thin-Layer Chromatography (2D-TLC) and High Performance Liquid Chromatography (HPLC). The quantitation of flavonoids and ginsenosides from the root. stem. leaf. flower and fruit of Dwarf ginseng and related species such as Korean gineng (Panax ginseng C.A. Meyer) and American ginseng (Panax quinquefolium L.) was analyzed by HPLC only. Three flavonoids (Kaempferol derivatives) labelled compound 1 $(10.8\%)$, compound 3 ($2.8\%$), and compound 4 ($8.4\%)$ were found in the root of Dwarf ginseng but not found in the roots of Korean ginseng and American ginseng. This is the first time that flavonoids have been found and identified in roots of the ginseng family (Araliaceae).

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.746-753
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• 2017

Radar Cross Section (RCS) is a factor directly related to survivability, and a design to reduce the presence of this factor is needed. The upper structure, guns, radar and so on are related to warship RCS, but radar RCS reduction is difficult because of complex shapes involved. In this paper, an enclosed mast, which is one modern method for reducing radar RCS, and the characteristics of an applied Frequency Selected Surface (FSS) are analyzed. The RCS reduction ability of an enclosed mast has been confirmed by comparing RCS analysis results for a general radar with that of an enclosed mast for available frequency according to FSS shape. The characteristics of the enclosed mast have also been studied by analyzing the elevation angle and slope of the mast. General radar RCS was high because of its complex shape, but low RCS was shown for the enclosed mast model, which had a simpler shape.

• Journal of the Society of Disaster Information
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• v.15 no.2
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• pp.292-300
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• 2019

Purpose: To reduce the noise and vibration of reinforced concrete slab structures, the damping performance is to be performed experimentally after installing hollow core or filling it with liquid. Method: Using the hollow rate as an experimental variable, the damping ratio and stiffness of each test specimen at impact load are obtained to determine the difference between the damping ratio and stiffness of the numerical analysis. In addition, the damping effects are reviewed by comparing the difference in the damping ratio and stiffness of a test specimen filled with liquid 50% of the study. Results: Since the difference in resistance between a specimen with or without hollow core is 5%, it is judged that there is no structural problem, and the injection of liquid into the hollow core can increase the damping ratio, which can reduce noise or vibration. Conclusion: At less than 20% of hollow rate, there was little damping effect, and at 30%, damping effect was found. However, if liquid is injected into the hollow core of the specimen, damping rate is shown to increase, and the injection of liquid into the hollow part is believed to reduce noise or vibration.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.1
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• pp.45-50
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• 2019

With the gradual advancement of IT, passive work processes are automated and the overall quality of life has greatly improved. This is made possible by the formation of an organic topology between a wide variety of real-life smart devices. To serve these diverse smart devices, businesses or users are using the cloud. The services in the cloud are divided into Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS). SaaS runs on PaaS, and PaaS runs on IaaS. Since IaaS is the basis of all services, an algorithm is required to operate virtualization resources efficiently. Among them, desktop resource virtualization is used for resource high availability of unused state time of existing desktop PC. Clustering of hierarchical structures is important for high availability of these resources. In addition, it is very important to select a suitable algorithm because many clustering algorithms are mainly used depending on the distribution ratio and environment of the desktop PC. If various attempts are made to find an algorithm suitable for desktop resource virtualization in an operating environment, a great deal of power, time, and manpower will be incurred. Therefore, this paper proposes a resource clustering simulator for cluster selection of desktop virtualization. This provides a clustering simulation to properly select clustering algorithms and apply elements in different environments of desktop PCs.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.3
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• pp.23-32
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• 2001

Since the LILI-128 cipher is a clock-controlled keystream generator, the speed of the keystream data is degraded in a clock-synchronized hardware logic design. Basically, the clock-controlled $LFSR_d$ in the LILI-128 cipher requires a system clock that is 1 ~4 times higher. Therefore, if the same clock is selected, the system throughput of the data rate will be lowered. Accordingly, this paper proposes a 4-bit parallel $LFSR_d$, where each register bit includes four variable data routines for feed feedback of shifting within the $LFSR_d$ . Furthermore, the timing of the propose design is simulated using a $Max^+$plus II from the ALTERA Co., the logic circuit is implemented for an FPGA device (EPF10K20RC240-3), and the throughput stability is analyzed up to a late of 50 Mbps with a 50MHz system clock. (That is higher than the 73 late at 45 Mbps, plus the maximum delay routine in the proposed design was below 20ns.) Finally, we translate/simulate our FPGA/VHDL design to the Lucent ASIC device( LV160C, 0.13 $\mu\textrm{m}$ CMOS & 1.5v technology), and it could achieve a throughput of about 500 Mbps with a 0.13$\mu\textrm{m}$ semiconductor for the maximum path delay below 1.8ns.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5A
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• pp.433-442
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• 2010

A control of chloride diffusion coefficient is very essential for service life of reinforced concrete (RC) structures exposed to chloride attack so that much studies have been focused on this work. The purpose of this study is to derive the intended diffusion coefficient which satisfies intended service life and propose a technique for optimum concrete mixture through genetic algorithm(GA). For this study, 30 data with mixture proportions and related diffusion coefficients are analyzed. Utilizing 27 data, fitness function for diffusion coefficient is obtained with variables of water to binder ratio(W/B), weight of cement, mineral admixture(slag, flay ash, and silica fume), sand, and coarse aggregate. 3 data are used for verification of the results from GA. Average error from fitness function is observed to 18.7% for 27 data for diffusion coefficient with 16.0% of coefficient of variance. For the verification using 3 data, a range of error for mixture proportions through GA is evaluated to 0.3~9.3% in 3 given diffusion coefficients. Assuming the durability design parameters like intended service life, cover depth, surface chloride content, and replacement ratio of mineral admixture, target diffusion coefficient, where exterior conditions like relative humidity(R.H.) and temperature, is derived and optimum design mixtures for concrete are proposed. In this paper, applicability of GA is attempted for durability mixture design and the proposed technique would be improved with enhancement of comprehensive data set including wider range of diffusion coefficients.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.319-326
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• 2009

Two parallel wide flange built-up beams are widely used as struts in resisting lateral earth pressure because of the effectiveness in structure and construction. In a certain structural system, the reinforced concrete columns are to be placed at the intersection where two perpendicular beams cross each other, the square part of the joint being filled with concrete. In the punching shear mechanism of the beam-column joint, the radial deformation caused due to shear cracking will be constrained by the spring action of the squarely encompassed beam flanges. As a result, the punching shear strength of the joint concrete can be expected to be increased. To verify this phenomenon experiments have been performed for various constraining elements and distances between columns and constraints. Test results are compared with the approximation analysis formula which has been proposed in this study, based on the code formula. The results calculated by the proposed equation show comparatively close agreement with the punching shear strength detected from the test.