• Steel and Composite Structures
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• v.22 no.2
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• pp.399-409
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• 2016

The fracture propagation mechanism and fractured rock mass failure mechanism were important research in geotechnical engineering field. Many failures and instability in geotechnical engineering were related on fractures propagation, coalescence and interaction in rock mass under the external force. Most of the current research were limited to two-dimensional for the brittleness and transparency of three-dimensional fracture materials couldn't meet the requirements of the experiment. New materials with good transparent and brittleness were developed by authors. The making method of multi fracture specimens were established and made molds that could be reused. The tension-compression ratio of the material reached above 1/6 in normal temperature. Uniaxial and biaxial loading tests of single and double fracture specimens were carried out. Four new fractures were not found in the experiment of two-dimensional fractures such as the fin shaped crack, wrapping wing crack and petal crack and anti-wing crack. The relationship between stress and strain of the specimens were studied. The specimens with the load had experienced four stages of deformation and the process of the fracture propagation was clearly seen in each stage. The expansion characteristics of the fractured specimens were more obvious than the previous research.

• Corrosion Science and Technology
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• v.9 no.5
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• pp.216-222
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• 2010

Most of the thirteen substations in operation in the metropolitan area were installed around the year 2000, and since water cooling methods are used to directly withdraw heat from transformer oils, a stable supply of electric power is required through optimal maintenance of facilities. The water cooling tower installed outdoors, which uses the water supply as sprinkler water, experiences the most problems. Since more than 90% of the cooling water is reused, the dissolved composition in the water becomes concentrated due to long operating hours, and impurities dissolve in the water due to air flowing in from the outside, forming hard scales on the outer surface of the cooling tube, and in extreme cases, reacting with the tube material composition, leading to corrosion. As a result, not only is cooling efficiency lowered, but in extreme cases the cooling tube must be replaced. In this study, the characteristics and composition of the scales formed on the cooling tube were analyzed and corrosion characteristics of material types were identified in order to find an efficient maintenance method for cooling tubes. In addition, the degree of dissolution of various chemicals were investigated during the removal of scales that have been formed.

• International Journal of Computer Science & Network Security
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• v.21 no.1
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• pp.125-136
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• 2021

The development of systems that can generate automatically instructional material is a challenging goal for the e-learning community. These systems pave the way towards large scale e-learning deployment as they produce instruction on-demand for users requesting to learn about any topic, anywhere and anytime. However, realizing such systems is possible with the availability of vast repositories of web information in different formats that can be searched, reused and integrated into information-rich environments for interactive learning. This paradigm of learning relieves instructors from the tedious authoring task, making them focusing more on the design and quality of instruction. This paper presents a mobile learning system (Mole) that supports the generation of instructional material in M-Learning (Mobile Learning) contexts, by reusing and integrating heterogeneous hypermedia web resources. Mole uses open hypermedia repositories to build a Learning Web and to generate learning objects including various hypermedia resources that are adapted to the user context. Learning is delivered through a nice graphical user interface allowing the user to navigate conveniently while building their own learning path. A test case scenario illustrating Mole is presented along with a system evaluation which shows that in 90% of the cases Mole was able to generate learning objects that are related to the user query.

• Journal of Integrative Natural Science
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• v.8 no.4
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• pp.235-243
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• 2015

Rhodium(I)-complex of $[Rh(CO)_2I_2{^-}]$ catalyzed carbonylation of anhydrous-trimethylamine in the presence of methyl iodide to give DMAC (N,N-dimethylacetamide) in no solvent. The catalyst had been reused 20 times, the analyses and distillation of collected products showed that the yields of DMAC, MAA (N-methylacetamide), and DMF (N,N-dimethylformamide) were 82.3%, 12.6%, and 4.4%. The conversion rate of trimethylamine was 99 % and the selectivity of DMAC was 82.3% with TON (Turnover Number) of 700. Stepwise procedure of inner-sphere reductive elimination for the formation of DMAC was suggested instead of acyl iodide intermediate.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2001.11a
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• pp.136-141
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• 2001

If we build new building after demolition of commercial building that is located in the downtown, it will be caused a social and environmental problem as wasting of resources and generating of waste. In this study, I investigated about remodel ins, this conclusion is given below. 1. Reconstruction cost is 2.1 times, and construction period is 1.4 times as much remodeling. So remodeling has an advantage. 2. For repairing and reinforcing timeworn building, we reinforced it as using carbon fiber sheet (girder, slab) and injecting method steel plate bonding Also, we tried to maintain efficiency of new building as using epoxy to protect concrete crack. 3. In the side of waste products and cost, remodeling has much more advantage than reconstruct. But demolition used construction period much. Because it had to be reused as repairing and reinforcing. And there was no difference between remodeling cost and reconstruct cost. If we develop research with enterprise.university.laboratory to exploit material and equipment and to train specialized engineer who will has a capacity to know construct repair and reinforce, it can be attribute to prevail remodeling in new construct market.

• Fibers and Polymers
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• v.7 no.2
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• pp.112-116
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• 2006

Caprolactam is the most important raw material for making Nylon 6 fibers and its quality directly determines the quality of Nylon. So it is necessary to study the techniques and methods to remove the colorful impurities from caprolactam. In this paper, the decolorization of caprolactam aqueous solution by anion exchange resins was studied and the decoloring abilities of five commercial resins were investigated. The regeneration of the resins was also studied, too. This study shows that the resin AMTX202 have excellent decoloring ability in the column experiment and that the decoloring efficiency is correlated with the volume of resins packed and is slightly affected by the flow rate and regenerating times. The fact that the resins can be regenerated and reused without affecting the efficiency of decolorization will decrease the cost of the treatment and operation in the industry. The adsorption of colored compounds with anion exchange resins in the packed columns seems to be technically feasible.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.145-148
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• 2003

Recently, the recycle of CMP (chemical mechanical polishing) slurries have been positively considered in order to reduce the high COO (cost of ownership) and COC (cost of consumables) in CMP process. Among the composition of slurries (buffer solution, bulk solution, abrasive particle, oxidizer, inhibitor, suspension, antifoaming agent, dispersion agent), the abrasive particles are one of the most important components. Especially, the abrasive particles of slurry are needed in order to achieve a good removal rate. However, the cost of abrasives, is still very high. In this paper, we have collected the silica abrasive powders by filtering after subsequent CMP process for the purpose of abrasive particle recycling. And then, we have studied the possibility of recycle of reused silica abrasive through the analysis of particle size and hardness. Also, we annealed the collected abrasive powders to promote the mechanical strength of reduced abrasion force. Finally, we compared the CMP characteristics between self-developed KOH-based silica abrasive slurry and original slury, As our experimental results, we obtained the comparable removal rate and good planarity with commercial products. Consequently, we can expect the saving of high cost slurry.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.325-334
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• 2018

Lactose is a reducing disaccharide consisting of two different monosaccharides such as galactose and glucose. The hydrogenation of lactose to lactitol is a formidable challenge because it is a complex process and several side products are formed. In this work, we synthesized Ru-Ni bimetallic nanohybrids as efficient catalysts for selective lactose hydrogenation to give selective lactitol. Ru-Ni bimetallic nanohybrids with $Ru-NiO_x$ (x = 1, 5, and 10 wt%) are prepared by impregnating Ru and Ni salts precursors with $TiO_2$ used as support material. Ru-Ni bimetallic nanohybrids (represented as $5Ru-5NiO/TiO_2$) catalyst is found to exhibit the remarkably high selectivity of lactitol (99.4%) and turnover frequency i.e. ($374h^{-1}$). In contrast, monometallic $Ru/TiO_2$ catalyst shows poor performance with ($TOF=251h^{-1}$). The detailed characterizations confirmed a strong interaction between Ru and NiO species, demonstrating a synergistic effect on the improvement on lactitol selectivity. The impregnation-reduction method for the preparation of bimetallic $Ru-NiO/TiO_2$ catalyst promoted Ru nanoparticles dispersed on NiO and intensified the interaction between Ru and NiO species. $Ru-NiO/TiO_2$ efficiently catalyzed the hydrogenation of lactose to lactitol with high yield/selectivity at almost complete conversion of lactose at $120^{\circ}C$ and 55 bar of hydrogen ($H_2$) pressure. Moreover, $Ru-NiO/TiO_2$ catalyst could also be easily recovered and reused up to four runs without notable change in original activity.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.497-503
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• 2022

This study was conducted to investigate the horticultural media + decomposed granite + reused rock wool in the following mixing ratio: Control = 100:0, M1 = 80:0:20, M2 = 60:30:10, M3 = 40:30:30, M4 = 30:40:30, M5 = 0:50:50 (reused rockwool : decomposed granite : horticultural media) and develop the physicochemical properties and the growth of 'Sulhyang' strawberry runner plant. In the physical aspect of the horticultural media, statistical differences were recognized that the bulk density and particle density were lower in the control and M1. But the bulk density and particle density were high in the M3, M4, and M5, because it had high mixing ratio between recycled rock wool and decomposed granite. EAW and WBC showed a similar tendency. The air porosity and total porosity were higher in control and M1 than M3, M4, M5. Exchangeable cation (K⁺, Ca²⁺, Na⁺, Mg²⁺) and base replacement capacity (CEC) were higher in control and M1, than M2, M3, M4, and M5. As a result of the cultivation of 'Sulhyang' runner plant, the plant length was long in M2, 32.1 cm and smaller than M5 to 28.4 cm. However, if the crown diameter, which is the growth indicator of the runner plant, all 6 treatments were formed 11.23 mm-12.03 mm, which is considered to be suitable for the growth of the runner plant. There wasn't a statistical difference between the weight and dry weight of the root. As a result, the growth difference of the seedlings by the horticulture media was similar. Therefore, considering the physical properties of the horticultural media, it was judged that the air porosity and total porosity would be improved when the recycled rock wool and the decomposed granite were properly mixed rather than the use of the horticultural media as a single medium, which would be advantageous for irrigation management.

• Resources Recycling
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• v.10 no.3
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• pp.3-13
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• 2001

The Korean Auto industry has developed remarkably over the past 30 years. In 2000 alone, Korea produced 3.11 million vehicles, and the number of vehicles registered surpassed the ten million mark. As the number of vehicles registered in Korea has increased, yew after you, a rising number of cars have been scrapped. In 2000, a total of 455,592 automobiles were scrapped, up dramatically from only 101,158 in 1989. The system for handling of ELV(End-of-Life Vehicles) in Korea is governed by the "Motor Vehicle Control Act". The Act places the responsibility for vehicle scrapping directly on the vehicle owners. h vehicle owner can only can eel a vehicle registration after he gets a certificate from an authorized vehicle dismantler showing that his vehicle was properly scrapped according to the law. The take-back rate of ELV reaches nearly 100% in Korea. The vehicle scrapping process in Korea is very similar to those in other countries. fluids such as fuels and oils are first removed, and recyclable parts are collected and separated. Engines and transmissions are dismantled and recycled for use as raw material. Plastics, which are not easily reused, are generally treated as industrial wastes. The "Motor Vehicle Control Act" prohibits reuse of certain parts in order to guarantee the safety of the used auto parts. However, some restrictions on the reuse of auto parts have recently been eased to promote recycling. In this paper, additionally, car recycling policy of the foreign countries such as Japan, Germany and EU were reviewed.