• 한국자동차공학회논문집
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• 제16권1호
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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 $1{\sim}1.5%$.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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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.

• 한국추진공학회지
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• 제16권5호
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• pp.89-96
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• 2012

기존의 펄스에코법은 스틸 연소관 내부에서 고무면으로 초음파를 입사시키므로 검사 도중에 고무면이 오염될 수 있으며, 이로 인해 치명적인 미접착 결함을 유발시킬 수 있다. 상기 방법을 보완할 수 있는 시험 기법을 개발하기 위해 스틸/고무 접착 시험편을 제작하여 스틸면으로 초음파를 입사시켰다. 스틸/고무 접착 시험편으로부터 측정한 고무 공진 주파수는 이론적으로 예측한 공진 주파수와 일치하였다. 본 논문은 고무 공진 주파수를 이용하여 고무 두께를 측정할 수 있는 초음파 공진법에 대해 기술하였다.

• 대한기계학회논문집A
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• 제24권6호
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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.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.562-569
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• 2012

기존의 펄스에코법은 스틸 연소관 내부에서 고무면으로 초음파를 입사시키므로 검사 도중에 고무면이 오염될 수 있으며, 이로 인해 치명적인 미접착 결함을 유발시킬 수 있다. 상기 방법을 보완할 수 있는 시험기법을 개발하기 위해 스틸/고무 접착 시험편을 제작하여 스틸면으로 초음파를 입사시켰다. 스틸/고무 접착 시험편으로부터 측정한 고무 공진 주파수는 이론적으로 예측한 공진 주파수와 일치하였다. 본 논문은 고무 공진 주파수를 이용하여 고무 두께를 측정할 수 있는 초음파 공진법에 대해 기술하였다.

• 대한치과교정학회지
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• 제41권5호
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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.

• 한국콘텐츠학회논문지
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• 제10권10호
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• pp.237-245
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• 2010

신경전도검사는 당뇨병성다발신경병증 및 당뇨병의 불현성 신경병증환자를 진단하기위한 중요한 검사이며 신경의 기능을 정량적으로 측정할 수 있는 검사기법이다. 본 연구에서는 당뇨병성다발신경병증 환자에서 보이는 전기생리학적 특징을 평가하기위하여 당뇨병성다발신경병증으로 진단된 120명과 정상대조군 77명의 운동신경전도검사의 결과를 비교?분석하였다. 상지와 하지의 각 운동신경에서 정상기준치에 대해 비정상 값을 보인 비율의 특징을 신경전도속도, 말단잠복기, 복합근육활동전위의 진폭, No potential의 빈도, 전도차단의 항목으로 나누어 분석하였다. 당뇨병성다발신경병증은 상지에 비해 하지를 더욱 침범하는 전신성 탈수초성 말초다발신경병증의 전기생리학적 특징이 관찰되었고, 특히 비골신경에서 비정상의 정도가 심한 것으로 분석되었다. 하지만 전도차단의 특징은 대조군에 비하여 유의한 차이가 없는 것으로 나타났다. 운동신경전도검사의 결과를 분석하여 당뇨병성다발신경병증의 전기생리학적 특징을 분석한 본 연구의 결과 하지의 비골신경이 중요한 지표가 될 수 있음이 확인되었고, 이는 당뇨병성다발신경병증의 중요한 전기생리학적 소견으로 사료된다.

• 대한전기학회논문지
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• 제39권11호
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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.

• 한국주거학회논문집
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• 제25권4호
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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.

• 전기학회논문지
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• 제64권10호
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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.