• Advances in concrete construction
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• v.9 no.2
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• pp.217-225
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• 2020

The recovery of waste proves a solution with two impacts: the environmental impact by the reduction of pollution and the gain of the occupied space by this waste, and the economic impact by the use of these lasts in the building and in the area of public works. The present research consists in recovering a waste marble (thrown powder exposed to the different meteorological phenomena) generated by the quarry marble of Fil-fila, located at the east side of Skikda in the north-east of Algeria, and add it, as sand in the composition of sand concrete. To carry out this research, we analyzed the evolution brought by the substitution of ordinary sand by marble waste sand, with 25%, 50%, 75% and 100% on the properties in the fresh state (density, workability and air content) and in the cured state (compressive strength, tensile strength, surface hardness and sound velocity). For durability we tested water absorption by immersion and chloride penetration. The results obtained are compared with control samples of 0% of substitution rate. In order to have a good filling of the voids in the granular skeleton; we added a quantity of limestone recycled fines from the quarries and for a good workability a super-plasticizing additive. The results showed that the partial substitution modified both the fresh and the hardened characteristics of the tested concretes, the durability parameters also improved.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.4
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• pp.157-162
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• 1987

The basic experiments on the plastic sea eel pots used in fishing were carried out in order to investigate the elasticity of the funnel ribs, hydrodynamic resistance, sinking time and diffusion of the bait from June to October, 1987. The elasticity of the bamboo funnel ribs was higher than that of the polypropylene ribs up to the load 150g. The hydrodynamic resistance R (kg) of the pots towing to the head direction horizontally in relation to towing velocity V (m/sec) was expressed as following formula; R=0.36V super(2.01) and coefficient of drag C sub(D) was 0.52. The sinking times of the covered pots by tape fully or partially were late 1-2 second than the typical pots within the water depth 7.5m. The diffusion tendency through the covered pots using dye and sardine extracts solution was concentrated to the entrance more than the typical pots. However, fishing efficiency as number and weight of fish per pots for nine times fishing operation was revealed no difference between the covered pots and the typical pots.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.141.1-141.1
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• 2011

New CCD BVR light curves of BD And are presented. Our light curves with nearly equal depths for both primary and secondary eclipses show well-defined photometric waves outside eclipse for all of BVR bandpasses. The orbital period is greatly revised as $0.^d92580519$ which is twice longer than that known previously. Sixteen timings from our observations and thirteen ones from the SuperWASP measurements were calculated. All available timings over 76 years, including ours, were analyzed to figure out the dynamical behavior of the system. It was found that the recent CCD O-C residuals varied in a cyclical way with a period of $9.^y18$ and a semi-amplitude of $0.^d0046$. The secondary period of $9.^y18$ is the most shortest one among those which have been ever found in the short period RS CVn binary stars. The periodic variation most likely arises from the light-travel time effect due to a low-mass ($m_3{\sim}0.88\;M_{\odot}$) tertiary companion moving in an orbit with an large eccentricity ($e_3$=0.70) and a low inclination ($i_3{\sim}28^{\circ}$). The Applegate mechanism could not operate properly in both components because the model parameters require too much large luminosity changes of ${\Delta}L/L_{p,s}$ > 10. The new light curves were synthesized using the 2003 version of Wilson-Divinney code. It was found useful to model two huge spots on the surface of the hotter star and a third-light in order to minimize the residuals from the observations. Astronomical basic parameters were deduced from our photometric solution.

• Korean Journal of Materials Research
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• v.23 no.11
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• pp.643-648
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• 2013

Activated carbon (AC) was synthesized from rice husks using the chemical activation method with KOH, NaOH, a combination of (NaOH + $Na_2CO_3$), and a combination of (KOH + $K_2CO_3$) as the chemical activating reagents. The activated carbon with the highest surface area (around $2000m^2/g$) and high porosity, which allows the absorption of a large number of ions, was applied as electrode material in electric double layer capacitors (EDLCs). The AC for EDLC electrodes is required to have a high surface area and an optimal pore size distribution; these are important to attain high specific capacitance of the EDLC electrodes. The electrodes were fabricated by compounding the rice husk activated carbons with super-P and mixed with polyvinylidene difluoride (PVDF) at a weight ratio of 83:10:7. AC electrodes and nickel foams were assembled with potassium hydroxide (KOH) solution as the electrolyte. Electrochemical measurements were carried out with a three electrode cell using 6 M KOH as electrolyte and Hg/HgO as the reference electrode. The specific capacitance strongly depends on the pore structure; the highest specific capacitance was 179 F/g, obtained for the AC with the highest specific surface area. Additionally, different activation times, levels of heating, and chemical reagents were used to compare and determine the optimal parameters for obtaining high surface area of the activated carbon.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.19-24
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• 2008

The Construction Management for the Asan Baebang Complex Development PF Project is aiming the solution for the needs of specialized organization and management for the construction of the project, as a independent representative managing the whole process of the super high rise and huge volume of complex project. This case shall be counted as a remarkable one in the point of view that the CM was decided to be encountered even in this consortium project made between the private firm and government, and shows that the project can be executed successfully without having its own organization of a huge number of staffs. This study is for the Construction Management applied for the consortium project between the private firm and government and it is my pleasure if this study could be a help to encourage CM for wide applying in the field by reviewing of its necessity and analyzing of its effect and advantage.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.5
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• pp.516-520
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• 1999

Mechanical alloying (MA) by planetary type ball mill of pure iron powders was carried out under the ammonia gas atmosphere. The powders of metastable iron nitrides was synthesized up to the nitrogen content of 23 at% N. The observed phases are identified as the super-saturated bcc solid solution for the nitrogen concentration below 14.5 at% N and the non-equilibrium hcp phase stable at high temperature for 20.8 at.% N. Magnetization of Fe-N powders gradually decreases with increasing the N concentration on contrast to the enhancement reported for the bct iron nitrides. Neutron diffraction experiments also provide detailed information concerning the local atomic structure surrounding the nitrogen atoms. The coordination number of Fe atom around a nitrogen atom for the iron nitride containing 9.5 at% N turns out to be 3.9 atoms. This suggests that a nitrogen atom is situated at a center of the tetrahedron formed by iron atoms.

• Smart Structures and Systems
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• v.15 no.3
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• pp.627-643
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• 2015

Negative stiffness, previously emulated by active or semi-active control for cable vibration mitigation, is realized passively using a self-contained highly compressed spring, the negative stiffness device (NSD).The NSD installed in parallel with a viscous damper (VD) in the vicinity of cable anchorage, enables increment of damper deformation during cable vibrations and hence increases the attainable cable damping. Considering the small cable displacement at the damper location, even with the weakening device, the force provided by the NSD-VD assembly is approximately linear. Complex frequency analysis has thus been conducted to evaluate the damping effect of the assembly on the cable; the displacement-dependent negative stiffness is further accounted by numerical analysis, validating the accuracy of the linear approximation for practical ranges of cable and NSD configurations. The NSD is confirmed to be a practical and cost-effective solution to improve the modal damping of a cable provided by an external damper, especially for super-long cables where the damper location is particularly limited. Moreover, mathematically, a linear negative stiffness and viscous damping assembly has proven capability to represent active or semi-active control for simplified cable vibration analysis as reported in the literature, while in these studies only the assembly located near cable anchorage has been addressed. It is of considerable interest to understand the general characteristics of a cable with the assembly relieving the location restriction, since it is quite practical to have an active controller installed at arbitrary location along the cable span such as by hanging an active tuned mass damper. In this paper the cable frequency variations and damping evolutions with respect to the arbitrary assembly location are then evaluated and compared to those of a taut cable with a viscous damper at arbitrary location, and novel frequency shifts are observed. The characterized complex frequencies presented in this paper can be used for preliminary damping effect evaluation of an adaptive passive or semi-active or active device for cable vibration control.

• Journal of Adhesion and Interface
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• v.16 no.4
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• pp.152-155
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• 2015

Platinum (Pt) is an easily moldable, anti-corrosive and also good catalyst in a variety of chemical reactions. Platinum can be used in many fields, however, however, the low wettability of platinum substrate in many platinum-based devices has been made a problem when they contact with liquid state environment. In this study, we report a simple and effective self-assembled monolayer coating method which provides tremendously increased wettability on platinum substrate device by using Sodium 3-mercapto-1-propanesulfonic acid solution. After surface modifications, water contact angle of the surfaces displayed less than $10^{\circ}$, representing that surfaces are successfully coated to be super-hydrophilic surface by simple dip coating method.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.1-15
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• 2017

Recently terrorism targets unspecified masses and causes massive destruction, which is so-called Super Terrorism. Many countries have tried hard to protect their citizens with various preparation and safety net. With inexpensive and advanced technologies of sensors, the surveillance systems have been paid attention, but few studies associated with the classification of the pedestrians' trajectories and the difference among themselves have attempted. Therefore, we collected individual trajectories at Samseoung Station using an analytical solution (system) of pedestrian trajectory by LiDAR sensor. Based on the collected trajectory data, a comprehensive framework of classifying the types of pedestrians' trajectories has been developed with data normalization and "trajectory association rule-based algorithm." As a result, trajectories with low similarity within the very same cluster is possibly detected.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.15-20
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• 2015

To examine the magnetic shielding effect for carbon-based materials at extremely low frequencies (60 Hz), two types of carbon black (Super-P and Denka Black) and a natural graphite (HC-198) were mixed into organic binder at 10 wt.% to produce a coating solution, and a powder coating with varying thickness was applied on an aluminum disk measuring 88 mm in radius. A device was developed to measure the sheielding effect at extremely low frequencies. A closed circuit was achieved by connecting a transformer and a resistor. The applied voltage was fixed at 65 V, and the magnetic field was measured to being the range of 4.95~5.10 mG. Depending on the thickness of the coating layer, the magnetic field showed a decreasing trend. The maximum decrease in the magnetic field of 38.3% was measured when natural graphite was coated with specimens averaging $455{\mu}m$. This study confirmed that carbon-based materials enable magnetic shielding at extremely low frequencies, and that the magnetic shielding effect can be enhanced by varying the coating thickness.