• Corrosion Science and Technology
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• v.19 no.2
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• pp.57-65
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• 2020

As competition among global automakers intensifies, demand for materials that are better in price and performance is increasing. While steel and plastic materials compete for automotive fuel tanks, plastic materials have advantages such as light weight for automobiles. However, they have high prices. Accordingly, in this paper, four types of Zn-X plated steel sheets, electroplating (X = none, Sn) and galvannealed (X = Fe, Fe-Mg), were manufactured and their applicability as a fuel tank material was evaluated. Nano-composite coating solution with good conductivity was treated on the surface of plated steels using a roll coater and then cured through induction furnace to improve corrosion resistance. Quality characteristics such as corrosion resistance, fuel resistance to diverse gasoline and diesel fuels, and seam weldability were evaluated for the above plated steels. Their properties were compared and analyzed with conventional Zn-Ni electroplating steels. Among the above plated steels, Zn-Fe-Mg galvannealed steels coated with nano-composite coating exhibited better properties than other steels. Detailed experimental results suggest that evenly distributed Mg elements on the coating layer play a key role in the enhanced quality performance.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.4
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• pp.25-31
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• 2012

Ionic trash in furnish decreases retention and drainage performance of the microparticle retention system using recycled fibers in closed papermaking system. Two retention systems, such as the microparticle system and the PEO/cofactor system, were compared and analyzed to improve retention. The PEO/cofactor system achieved similar retention performance at low addition level as the microparticle system. Optimum ratio of PEO/cofactor dual polymer system was 1:10. Ash retention was increased when using the fixing agent. As the TMP ratio increased, the PEO/cofactor system was more efficient in retention and drainage than the other system. The high molecular weight and non-ionic polymer retention system had less effect on flocculation hindrance than the traditional electrostatic retention system.

• Earthquakes and Structures
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• v.8 no.1
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• pp.19-35
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• 2015

This study compares the seismic performances of two reinforced concrete frame specimens tested by the pseudo-dynamic procedure. The pair of 3-storey, 3-bay frames specimens are constructed with typical characteristics of older construction which is lacking seismic design. One of the specimens is a bare frame while the other is infilled with low-strength autoclave aerated concrete (AAC) block masonry. The focus of this study is to investigate the influence of low strength masonry infill walls on the seismic response of older RC frames designed for gravity loads. It is found that the presence of weak infill walls considerably reduce deformations and damage in the upper stories while their influence at the critical ground story is not all that positive. Infill walls tend to localize damage at the critical story due to a peculiar frame-infill interaction, and impose larger internal force and deformation demands on the columns and beams bounding the infills. Therefore the general belief in earthquake engineering that infills develop a second line of defence against lateral forces in seismically deficient frames is nullified in case of low-strength infill walls in the presented experimental research.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3133-3150
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• 2021

This work deals with the validation of a high-fidelity multiphysics system coupling the Serpent 2 Monte Carlo neutron transport code with SUBCHANFLOW, a subchannel thermalhydraulics code, and TRANSURANUS, a fuel-performance analysis code. The results for a full-core pin-by-pin burnup calculation for the ninth operating cycle of the Temelín II VVER-1000 plant, which starts from a fresh core, are presented and assessed using experimental data. A good agreement is found comparing the critical boron concentration and a set of pin-level neutron flux profiles against measurements. In addition, the calculated axial and radial power distributions match closely the values reported by the core monitoring system. To demonstrate the modeling capabilities of the three-code coupling, pin-level neutronic, thermalhydraulic and thermomechanic results are shown as well. These studies are encompassed in the final phase of the EU Horizon 2020 McSAFE project, during which the Serpent-SUBCHANFLOW-TRANSURANUS system was developed.

• Proceedings of the KIEE Conference
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• 2006.10b
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• pp.216-220
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• 2006

This paper is presented for the measurement of the bearing stiffness for the spindle motors. BLDC Spindle Motors for the Hard Disk Drive are used by several kinds of the bearings, such as ball bearing, fluid dynamic bearing, and aero dynamic bearing. The spindle motors are attached the platters to read and write the data. Because the platter rotates at high end speed with the load and can be shocked from a suddenly moving, the bearing needs the rated stiffness with the pressure. By the way, it has not been realized to measure the real stiffness for each bearing types. In this paper, we proposed the method of measuring the stiffness for the bearings by using the magnet force. Experimental results show the performance to measure the bearing stiffness of the BLDC spindle motors for an HDD.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.175-178
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• 2007

This paper is presented for the design of the thrust yoke for the spindle motors. HDD spindle motors are rotated by fluid dynamic bearing which consists of the shaft and the sleeve with the groove to generate the pressure. Because the thrust and journal clearances between shaft and sleeve is too small, around 8um and 2.5um, respectively, it is very difficult to design the bearing to come up to the disks to read and write the data. By the way, it is also so hard to overcome the load of the disks with only the thrust bearing. So, the paper is proposed for the trust yoke to come up to the disks considering of the force of the thrust bearing. In this paper, we proposed the thrust yoke with an unique fluid dynamic bearing in comparison with the motors without thrust yoke. Experimental results show the performance of the thrust yoke of the spindle motors for an HDD.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.51-53
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• 2008

The vehicle aerodynamic crosswind characteristics are mainly governed by the coefficient of side force and yawing moment. These performances affect not only the driving comfort which can be felt by driver but also the safety due to the instability of vehicle. The aims of this investigation are to improve the aerodynamic crosswind performance of sedan vehicle under the crosswind conditions. In order to improve the crosswind stability, numerical analysis has been performed by modifying the rear body shape of vehicle. As the results, we observed about 20% reduction of yawing moment coefficient relative to the base vehicle.

• The Journal of the Acoustical Society of Korea
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• v.15 no.2
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• pp.12-20
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• 1996

A real-time Dolby AC-3 decoder has been implemented using a 20-bit fixed point general purpose DSP chip. It is shown that AC-3 decoder of this paper has same performance as decoder of C-simulator on PC. And also, it is applied to DVD player. Especially, in this paper, we proved that it has shorter latency time than that of previous AC-3 decoder.

• Proceedings of the KIEE Conference
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• 2005.10a
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• pp.150-154
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• 2005

This paper is presented for the development of the brushless DC(BLDC) spindle motors for hard disk drives. A new BLDC Motor has the use of insulated, compacted, iron powder for the armature core material of BLDC motors. Insulated iron powder in this paper is generally called soft magnet composite(SMC). The SMC is used for the stator of the motor instead of the laminated steel core. The motor used by SMC can have the good advantages in condition of the high frequency input power and small sized motor. It gets much more high efficiency than laminated steel core at same input power. The proposed motor has a technique of speed sensorless control. Experimental results show the performance of the proposed BLDC spindle motors for an HDD.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.3
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• pp.27-40
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• 2013

Rotorcraft operating in the domestic aviation safety techniques are applied CRM training is conducted but, aircraft accidents caused by human factors has not shown a declining trend. Thus, knowledge of aviation safety and human factors for the spread of awareness of improved rotorcraft flight operations department managers to understand the complexity of nature and culture, and to perform high-risk mission helicopter pilot study of local activation and enhance safety awareness research was conducted in order to. In this study, the development direction of CRM training studies in order to identify the leading NOTECHS (Non-Technical Skills; non-technical pilot skills) of the four categories as the independent variable and the dependent variable corresponding to the resulting effect on the key variables awareness of the differences were studied. In addition, the direction and strength of the relationship were analyzed to determine the relationship of each independent variable to assess the impact on the dependent variable regression analysis was performed. Pilot training and evaluation of non-technical skills related to the teaching reflected in the CRM training and assessment must be carried out with 5 star rating scale was preferred. Therefore, to meet our country rotorcraft operating environment 'NOTECHS' aviation safety by developing training programs reflected in the educational process, implementation, and periodic training and assessment is done in future research on this analysis and feedback is done to reflect the specific performance expect.