• Journal of the Korea Society of Computer and Information
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• v.19 no.3
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• pp.155-161
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• 2014

The objective of this study is to weight analysis portable backpack system of infantry weapon systems for ergonomic design in manual materials handling tasks. For the product design, we analyzed the ergonomic guidelines and status of similar weapon systems by comparing the efficient operation performance provide for the basic data. Result of this study, the relationship between portability and mobility presented for schematic. In the short distance of the short biomechanical criterion, 1-2 hours in the middle of moving psychophysical criterion, 4 hour or more long-distance criterion applied for the physiological criterion for easy of trade-offs that need to be considered. This study suggests for 4 research items for infantry backpack system in manual materials handling tasks. Throughout the result of anthropometric populations, the 5%tile body weight for -0.91kg but 95%tile in 34.17kg considered to be margin for free, easy and efficient operation for the weight margin between portability and mobility in manual materials handling tasks.

• Journal of Welding and Joining
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• v.32 no.5
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• pp.32-43
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• 2014

Welding and joining technology has become a core field. Therefore it is more widely applied to nonferrous metals, inorganic and polymeric materials. That is because the high performance, high function and diversification trend of materials used as industrial technology develops. In the laser welding process, STS 304 and SCP1-S were used as the base materials, the output density was fixed $7MW/cm^2$, the protective gas was argon(Ar) and the transfer rate was fixed 5 mm/sec. and it was progressed while the magnetic field is gradually increasing by 100 mT ranging 0 to 400 mT. The tensile test showed in average about 6 % tensile strength improvement in the case of the laser welding process using the magnetic fields. In the shielded metal arc welding process using SPHC only or the combination of SPHC+STS304 as base materials. The electric current was set at 80 Amperes and the protective gas used argon(Ar) the same as the laser welding process and the strength of magnetic fields. In the shielded metal arc welding process using the magnetic fields, the tensile tests showed about 5 % tensile strength improvement in the case of using SPHC only, 3 % tensile strength improvement in the case of using the combination of SPHC+ STS304. In comparing the results of numerical analysis to the results of experimental tests, it was revealed that the temperature, thermal stress distribution and the behavior of molten pool were similar to those of real tests. Consequently, it may be considered that the numerical assumption and the analytical model used in this study were reasonable.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.735-741
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• 2002

This paper investigates circularity of fly ashes using the digital image processing. Fly ashes directly collect from electrostatic precipitator when the load of conditions of boiler are changed at a coal-fired power plant. Circularity measurement can be accomplished in five steps: ① image acquisition, ② grey image processing, ③ detection the component to measure ④ binary image processing ⑤ feature measurement. The mean circularity of fly ashes is in the range of 0.78 to 0.83. fly ashes collected from the same hopper has similar circularity regardless of the load of boiler and circularity increases as going from the 1st hopper to 3rd one, namely as particle size become finer.

• Advances in concrete construction
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• v.9 no.6
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• pp.547-556
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• 2020

This study aimed to develop reference materials (RMs) that are chemically stable and can simulate the flow characteristics of cement paste. To this end, the candidate components of RMs were selected considering the currently required properties of RMs. Limestone, slag, silica, and kaolin were selected as substitutes for cement, while glycerol and corn syrup were selected as matrix fluids. Moreover, distilled water was used for mixing. To select the combinations of materials that meet all the required properties of RMs, flow characteristics were first analyzed. The results revealed that silica and kaolin exhibited bilateral nonlinearity. When an analysis was conducted over time, slag exhibited chemical reactions, including strength development. Moreover, fungi were observed in all mixtures with corn syrup. On the other hand, the combination of limestone, glycerol, and water exhibited a performance that met all the required properties of RMs. Thus, limestone, glycerol, and water were selected as the components of the RMs. When the influence of each component of the RMs on flow characteristics was analyzed, it was found that limestone affects the yield value, while the ratio of water and glycerol affects the plastic viscosity. Based on this, it was possible to select the mixing ratios for the RMs that can simulate the flow characteristics of cement paste under each mixing ratio. This relationship was established as an equation, which was verified under various mixing ratios. Finally, when the flow characteristics were analyzed under various temperature conditions, cement paste and the RMs exhibited similar tendencies in terms of flow characteristics. This indicated that the combinations of the selected materials could be used as RMs that can simulate the flow characteristics of cement paste with constant quality under various mixing ratio conditions and construction environment conditions.

• Journal of Microbiology and Biotechnology
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• v.13 no.2
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• pp.301-304
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• 2003

In this study, hydrogen sulfide ($H_2S$), ammonia ($NH_3$), and benzene, which represent the major odor from a natural leather process plant, were removed using a fluidized bed bioreactor and biofilter including Thiobacillus sp. IW and a MY microbial consortium. The critical removal rate was $12g m^{-3}h^{-1}\;for\;H_2S,\;11g m^{-3}h^{-1}\;for\;NH_3\;and\;28 g m^{-3}h^{-1}$ for benzene by the fluidized bed bioreactor, and $8.5g m^{-3}h^{-1}\;for\;H_2S\;7g m^{-3}h^{-1}\;for\;NH_3,\;and\;25 g m^{-3}h^{-1}$ for benzene in the biofilter. The average removal efficiency of $H_2S$, $NH_3$, and benzene by continuous operation for over 30 days with the fluidized bed bioreactor was $95{\pm}3\%,\;99{\pm}1\%,\;and\;98{\pm}5\%$, respectively, whereas that with the biofilter was $96{\pm}4\%,\;95{\pm}4\%,\;and\;97{\pm}3\%$, respectively. Therefore, the critical removal rate of $H_2S$, $NH_3$, and benzene was higher in the fluidized bed bioreactor, whereas the removal efficiency on the continuous operation was similar in both bioreactors.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.168.1-168.1
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• 2014

We developed poly (3,4-ethylene dioxylene thiophene):poly (styrene sulfonic acid) (PEDOT:PSS)-free organic solar cells (OSCs) using buffer and anode combined Ta doped $In_2O_3$ (ITaO) electrodes. To optimize the ITaO electrodes, we investigated the effect of $Ta_2O_5$ doping power on the electrical, optical, and structural properties of the co-sputtered ITaO films. The optimized ITaO film doped with 20 W $Ta_2O_5$ radio frequency power showed sheet resistance of 17.11 Ohm/square, a transmittance of 93.45%, and a work function of 4.9 eV, all of which are comparable to the value of conventional ITO electrodes. The conventional bulk heterojunction OSC with ITaO anode showed a power conversion efficiency (PCE) of 3.348% similar to the OSCs (3.541%) with an ITO anode. In addition, OSCs fabricated on an ITaO electrode successfully operated without an acidic PEDOT:PSS buffer layer and showed a PCE of 2.634%, which was much higher than the comparable no buffer OSC with an ITO anode. Therefore, co-sputtered ITaO electrodes simultaneously acting as a buffer and an anode layer can be considered promising transparent electrodes for cost-efficient and reliable OSCs because they can eliminate the use of an acidic PEDOT:PSS buffer layer.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.628-634
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• 2016

The cold rolling workability and mechanical properties of two new alloys, designed and cast Al-5.5Mg-2.9Si and Al-7Mg-0.9Zn alloys, were investigated in detail. The two alloy sheets of 4 mm thickness, 30 mm width and 100 mm length were reduced to a thickness of 1 mm by multi-pass rolling at ambient temperature. The rolling workability was better for the Al-7Mg-0.9Zn alloy than for the Al-5.5Mg-2.9Si alloy; in case of the former alloy, edge cracks began to occur at 50% rolling reduction, and their number and length increased with rolling reduction; however, in the latter alloy, the sheets did not have any cracks even at higher rolling reduction. The mechanical properties of tensile strength and elongation were also better in the Al-7Mg-0.9Zn alloy than in Al-5.5Mg-2.9Si alloy. Work hardening ability after cold rolling was also higher in the Al-7Mg-0.9Zn alloy than in the Al-5.5Mg-2.9Si alloy. At the same time, the texture development was very similar for both alloys; typical rolling texture developed in both alloys. These differences in the two alloys can primarily be explained by the existence of precipitates of $Mg_2Si$. It is concluded that the Al-7Mg-0.9Zn alloy is better than the Al-5.5Mg-2.9Si alloy in terms of mechanical properties.

• Korean Journal of Materials Research
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• v.8 no.9
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• pp.819-824
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• 1998

The influence of casting cooling rate during the preparation of ingots on the grain size distribution and the magnetizing ability of $\textrm{Nd}_{16}\textrm{Fe}_{72}\textrm{V}_{4}\textrm{B}_{8}$ sintered magnets were investigated. Sintered magnets prepared from copper mold which allow a higher cooling rate, show a smaller grain size distribution and god magnetizing ability. The effects of adding bride forming elements, such as Cr, Mn, Nb, and W on the magnetic properties of Nd-Fe-B sintered magnets were also investigated. Both Cr and W addition increase coercivity and the resultant $\textrm{Nd}_{16}\textrm{Fe}_{72}\textrm{Cr}_{4}\textrm{B}_{9}$ alloy exhibits a similar magnetizing ability in comparison with $\textrm{Nd}_{16}\textrm{Fe}_{72}\textrm{V}_{4}\textrm{B}_{8}$ alloy.

• Journal of Powder Materials
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• v.18 no.3
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• pp.226-237
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• 2011

W-ZrC and W-HfC composite powders were fabricated by the Plasma Alloying & Spheroidization (PAS) method and the powders were sprayed into hybrid coating layers by using Low Vacuum Plasma Spray (LVPS) process, respectively. Microstructure, mechanical properties, and ablation characteristics of the fabricated coating layers were investigated. The LVPS process led to successful production of W-Carbide hybrid coatings, approximately 400 ${\mu}M$ or above in thickness. As the substrate preheating temperature increased from $870^{\circ}C$ to $917^{\circ}C$, the hardness of the W-ZrC coating layer increased due to decreased porosity. Vickers hardness showed higher value (about 108.4 HV) in W-ZrC hybrid coating material compared to that of W-HfC while adhesive strength was found to be similar in both coating layers. The plasma torch test revealed good ablation resistance of the W-Carbide hybrid coating layers. The relatively high performance W-ZrC coating layer at the elevated temperature is thought to be attributed to both the strengthening effect of ZrC particle remained in the layer and the formation of ZrO2 phase with high temperature stability.

• Journal of Periodontal and Implant Science
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• v.30 no.2
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• pp.277-287
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• 2000

For the regeneration of osseous defect on the furcation area, autogeneous bone graft has been primarily used. But it has the limitation of donor site, additive surgical operation etc. Recently anorganic xenogenic bone graft materials of removing all organic components are commonly used for the regeneration of periodontal defects. This study was the comparison of the effect on the regeneration with two types xenografts($Bio-oss^{(R)}$ and Ca-P thin coated Bovine bone powder) on the furcation involvement in Beagle dogs. After surgically induced chronic periodontitis in bifurcation area of premolar, $Bio-oss^{(R)}$ and Ca-P BBP were grafted on the osseous defects. Tissue blocks including defects with soft tissues were harvested following a four-& eight-week healing interval and prepared for histologic analysis. The results of this study were as follows: 1. $Bio-oss^{(R)}$ group: there were significant differences among the $Bio-oss^{?}$ group at 4weeks and 8weeks, but the control group had various appearances : new bone formation, resorption of graft materials by multinuclear giant cells, connective tissue cells intervention in the bone graft sites etc. 2. Ca-P BBP group: lots of new bone formation were observed but the arrangement of periodontal ligament was not completed at 4weeks. New bone were replaced mature bone and the periodontal ligaments showed the functional arrangement at 8weeks. 3. By reason of undergrowing the epithelium within the osseous defects, new bone formation was not happened in the upper area of bifurcation in $Bio-oss^{(R)}$ group. 4. In Ca-P BBP group, epithelial undergrowth was not seen and generally showed much more new bone formation. 5. Ca-P BBP group showed the osteocyte-like cells at the inner portion of the graft materials 6. Both groups were similar to resorptive appearances of graft materials, but Ca-P BBP group had the better effects of osteoconduction.