• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.22-28
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• 2008

Generally block imbedded type oil pump is adopted to make a small engine. In this paper 1D/3D numerical simulations were conducted to reduce energy consumption of the block imbedded type oil pump. At each stage of engine development we have estimated the oil flow rate and pressure to optimize oil pump sizes by using the 1D system analysis and then accomplished 3D CFD(Computational Fluid Dynamics) simulations to optimize oil pump shapes including inlet/outlet port. As a result, the energy consumption of oil pump has been reduced to nearly 27% and the engine fuel consumption to $1{\sim}1.5%$.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3032-3036
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• 2011

Cooling type of traction motor for EMU in domestic is mostly an open type. Its system is a cooling air entered through air inlet cool down a traction motor and an hot air by traction motor get out air outlet. It is easy to cool it down but hard to maintain it. To improve an ability of maintenance, a total enclosed type traction motor is already developed and used in abroad, not an opne type. So we developed a total enclosed type traction motor which will be used in domestic and abroad EMU. We tried to reduce a weight and a size compared with the abroad one. In contrast with open type traction motors which cool off inside of motors, total enclosed motors cool down by cooling exterior frame of motors. In this case, cooling fins or air fan blowing to the exterior of motors are applied. The total enclosed type traction motor developed by us have two housing to block the foreign substance into inner of a motor and have two cooling fan to easy to reduce a heat happened at a coil. In this paper, design of a cooling structure of the total enclosed traction motor developed twice and performance verification through test will be discussed.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.5
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• pp.89-96
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• 2012

The rubber side could be contaminated using the existing pulse echo method because the ultrasonic wave was incident on the rubber side from the interior of the steel motor case, which could lead to the critical disbond defect. To develop the test method which can be replaced the existing method, the ultrasonic wave was incident on steel face of the steel/rubber adhesive test block. Rubber resonance frequencies measured from the steel/rubber adhesive test block were in good agreement with theoretically predicted rubber resonance frequencies. This paper was described about the ultrasonic resonance method to convert the rubber resonance frequency into the rubber thickness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1479-1490
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• 2000

The design process of the motor driven tilt/telescopic steering column is established by axiomatic design approach in conceptual design stage. By selecting independent design variables for improvin g performance of the steering system, each detailed design can be carried out independently. In the detailed design, the safety in crash environment and vibration reduction are considered. An occupant analysis code SAFE(Safety Analysis For occupant crash Environment) is utilized to simulate the body block test. Segments, contact ellipsoids and spring-damper elements are used to model the steering column in SAFE. The model is verified by the result of the body block test. After the model is validated, the energy absorbing components are designed using an orthogonal array. Occupant analyses are performed for the cases of the orthogonal array. Final design is determined for the minimum occupant injury. For vibrational analysis, a finite element model of the steering column is defined for the modal analysis. The model is validated by the vibration experiment. Size and shape variables are selected for the optimization process. An optimization is conducted to minimize the weight subjected to various constraints.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.562-569
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• 2012

The rubber side could be contaminated using the existing pulse echo method because the ultrasonic wave was incident on the rubber side from the interior of the steel motor case, which could lead to the critical disbond defect. To develop the test method which can be replaced the existing method, the ultrasonic wave was incident on steel face of the steel/rubber adhesive test block. Rubber resonance frequencies measured from the steel/rubber adhesive test block were in good agreement with theoretically predicted rubber resonance frequencies. This paper was described about the ultrasonic resonance method to convert the rubber resonance frequency into the rubber thickness.

• The korean journal of orthodontics
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• v.41 no.5
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• pp.354-360
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• 2011

Objective: To investigate the effects of different pilot-drilling methods on the biomechanical stability of self-tapping mini-implant systems at the time of placement in and removal from artificial bone blocks. Methods: Two types of artificial bone blocks (2-mm and 4-mm, 102-pounds per cubic foot [102-PCF] polyurethane foam layered over 100-mm, 40-PCF polyurethane foam) were custom-fabricated. Eight mini-implants were placed using the conventional motor-driven pilot-drilling method and another 8 mini-implants were placed using a novel manual pilot-drilling method (using a manual drill) within each of the 2-mm and 4-mm layered blocks. The maximum torque values at insertion and removal of the mini-implants were measured, and the total energy was calculated. The data were statistically analyzed using linear regression analysis. Results: The maximum insertion torque was similar regardless of block thickness or pilot-drilling method. Regardless of the pilot-drilling method, the maximum removal torque for the 4-mm block was statistically higher than that for the 2-mm block. For a given block, the total energy at both insertion and removal of the mini-implant for the manual pilot-drilling method were statistically higher than those for the motor-driven pilot-drilling method. Further, the total energies at removal for the 2-mm block was higher than that for the 4-mm block, but the energies at insertion were not influenced by the type of bone blocks. Conclusions: During the insertion and removal of mini-implants in artificial bone blocks, the effect of the manual pilot-drilling method on energy usage was similar to that of the conventional, motor-driven pilot-drilling method.

• The Journal of the Korea Contents Association
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• v.10 no.10
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• pp.237-245
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• 2010

Nerve conduction studies (NCS) are the most objective measure of nerve function and essential for the diagnosis of sub-clinical neuropathy in diabetes mellitus and diabetic polyneuropathy (DPN). This study evaluates the characteristic of electrophysiological abnormalities in DPN. Electrodiagnostic data from 120 patients with diabetic polyneuropathies and 77 control subjects were reviewed. Motor nerve conduction velocities (MNCV), distal motor latencies (DML), compound muscle action potential (CMAP) amplitudes, No potential frequency and conduction block were analyzed. Data were normalized based on normative reference values, and the proportion of nerves with abnormal values in the lower and upper limbs were evaluated. DPN was systemic demyelinating peripheral polyneuropathy and more severe abnormal nerve conduction was found in lower limbs than in upper limbs. The abnormal degree was more severe in peroneal nerve. It was no statistically significant difference of conduction block in control and DPN group. Our findings suggest that DPN had more common and severe peroneal nerve involvement in the motor nerve conduction studies (MNCS). These findings have important implications for the electrophysiological evaluation of DPN.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.11
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• pp.1174-1182
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• 1990

A hgih efficiency and good dynamic performance drive system of an induction motor is presented in this paper using vector control technique. If the induction motor is driven under light loads with rated flux, the iron loss is excessively large compared with the copper loss, resulting in poor motor efficiency. High efficiency drive of an induction motor can be achieved by adjusting the flux level which leads the total motor loss to be a minimum value. Generally reducing the flux degrades the dynamic performance, but the dynamic performance of the proposed system is also maintained high. If the d-axis is coincident with rotor flux phasor in synchronous rotating reference frame, the stator current can be decoupled as flux component and torque component. At steady state, the developed motor torque is proportional to the product of the flux and torque component. The combination of the two components minimizing the motor loss could be found with numerical method. As the procedure to obtain the optimal combination is too hard, it is found experimentally. The system block diagram is suggested for maximum efficiency control. The proposed system is studied through digital simulation and verified with experiment. The experimental results show the possiblity of a high efficiency drive with good dynamic performance of maximum efficiency control.

• Journal of the Korean housing association
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• v.25 no.4
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• pp.83-91
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• 2014

The purpose of this study is to clarify the characteristics between the type of daily routine and spatial configuration of activity areas in classroom and provide alternatives for space planning of activity areas in classroom of child-care centers. This study used the content analysis on daily activity plan and floor plans through field survey. Analysis on floor plans was conducted for 35 classrooms in 9 child-care centers which allowed field survey. The results of this study were as follows; There was no significant difference for classroom size according to the type of daily routine in 3 to 5-year-old classrooms. The average size of classrooms was $61.6m^2$ for care oriented type, $41.4m^2$ for indoor activity oriented type and $48.8m^2$ for group activity oriented type. There was no significant difference in composition of activity areas in classrooms according to the type of daily routine. In case of 0 to 2-year-old classrooms, they were composed of 6 activity areas including gross-motor, role play, block building, language, creative expression, exploration/manipulation. Activity area of the most low frequency was gross-motor area. In case of 3 to 5-year-old classrooms, most classrooms were composed of all the 7 activity areas including art, tone and rhythmic, block building, role play, language, math and science. Most accessible and central areas in 0 to 2-year-old classrooms were gross-motor and role play. Also, most separate areas were exploration/manipulation and block building. Most accessible and central areas in 3 to 5-year-old classroom were art and math. Also, most separate areas were tone and rhythmic and science.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.10
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• pp.1523-1527
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• 2015

Traction power is supplied by three-phase alternating current of 154 kV power grid and electric trains are operated on single phase feeding system. It becomes important to use all the three phases equally and convert them into two-phase electric power (90 degree phase rotation) for traction supply. This is achieved by special transformer from the adjacent traction substation which is separated by a neutral section. Neutral section locations are in front of the substation and between the two substations. The first stage of the Seoul-Busan high-speed railway, design curve radius is larger than 7,000 m and the greatest slope is 25‰. The railway track conditions are evaluated as good enough to install a neutral section at the first stage, but a few factors of coasting operation of the train should be considered at the second stage of Seoul-Busan high-speed railway. The neutral section was located at Kim-cheon substation, which made some neutral section problems produced by the operating train, and the neutral section was moved about 1.5 km to the south toward Dong Dae-gu station due to the track operation condition. Some of the trains which stopped at the existing Kim-cheon Gu-mi station produced another motor block failure after moving the neutral section. In this paper, power quality, system performance and track condition, etc. are suggested to solve the problems.