• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.723-734
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• 2018

A structural weight estimation methodology for the multicopter design process is presented. In general, a multicopter is composed of an airframe, motors, propellers, battery and so on. Among these, the weight of motors, propellers and battery can be obtained from the weight trends with respect to design parameters. However, the structural weight is hard to be estimated due to the various configurations and design concepts of multicopters. Moreover, the airframe weights of most commercial multicopter products are not provided. Thus, an accurate airframe weight model is required for the reliable mutlcopter design process. Firstly, the standard configuration of multicopters is defined. Then, we proposed the structural weight estimation method using the number and diameter of propellers determined from the initial step of sizing process. Finally, we validated our suggested method using the commerical products.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.304-307
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• 2008

In order to evaluate the effect of permanent softening behavior on springback prediction, 2D-draw bending simulations were compared with experiments for friction stir welded DP590 steel sheets. To account fur the nonlinear hardening behavior, the combined isotropic-kinematic hardening law was utilized with and without considering the permanent softening behavior during reverse loading. Also, the non-quadratic orthotropic yield function, Yld2000-2d, was used to describe the anisotropic initial-yielding behavior of the base sheet while anisotropic properties of the weld zone were ignored for simplicity.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.301-303
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• 2008

In order to investigate the influence of anisotropy on formability and also to obtain guidelines for the stamping process design in friction stir welded TWB (tailor welded blank), the aluminum ally 6111-T4 sheet was welded with three different types of combination: RD||RD, TD||RD and TD||TD (Here, RD and TD mean the rolling direction and transverse direction, respectively) and then hemisphere dome stretching and cylindrical cup drawing tests were carried out. In addition, the numerical analysis was performed to confirm the validity of experimental results. For the numerical analysis, the non-quadratic orthotropic yield function, Yld2004-18p was utilized to represent precise anisotropic properties.

• JOURNAL OF ELECTRICAL WORLD
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• no.8 s.16
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• pp.17-22
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• 1969

본고는 지난 2월 14일과 15일 양일간에 걸쳐 Okinawa에서 유구(Ryukyu)전력공사 주최로 개최된 제8회 ${\ulcorner}$과학청소년의 날${\lrcorner}$기념행사에 참석하였던 토마스$\cdot$앨바$\cdot$에디슨재단의 전무이사인 제임스$\cdot$G$\cdot$쿡(James G. Cook)씨가 동 행사에 참석한 우수학생들에게 정찬회 석상에서 행한 강연의 원고를 번역한 것이다. 제임스$\cdot$쿡씨는 현재 토마스$\cdot$앨바$\cdot$에디슨재단의 전무이사의 요직에 재직하고 있으며 1965년에 동 재단의 상무이사로 취임하기 이전에는 5년간 Detroit 시에 있는 General Motors 회사의 모터연구소원 및 섭외담당관으로 활약하였다. 미시간주 Detroit 시 출신인 씨는 Eastern Michigan 대학에서 심리학박사학위를 받았으며 또한 정치학도 수업하였다. 씨는 동행사 참가 직후 내한하여 약 1주간 체류하면서 당 대한전기협회와 내년 4월에 한국에서 개최하기로 된 제14회 ${\ulcorner}$국제에디슨탄생일기념축전${\lrcorner}$에 관한 행사계획의 세부내용을 협의한 바 있다.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.942-949
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• 2002

The use of a combined starter/generator integrated into the drive train of an automobile offers several possibilities for improvement of fuel economy The use of such a starter/generator system is made feasible by a switch from a 14 volts electrical system to a 42 volts system, however, the sizing of the components is not a trivial problem. This study combines a dynamic electromechanical model of the starter, battery and power electronics with the nonlinear mechanics of the piston/crankshaft system and a thermofluid model of the compression and expansion processes to investigate the cold start problem. The example involves the start of an eight cylinder engine at -25 degrees Celsius. This paper shows how the mechatronic V8 engine of an automotive starter/generator system for the startability works well.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1926-1930
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• 2007

In this study, we performed the CFD analysis to predict the cooling performance of the motor for golf-car application. The motor for the golf-car is different from the general motors in the cooling method and the operating condition. So, it is important to predict the motor's temperature generated by the electric losses. We investigated the inner temperature rise using the unsteady state analysis and compared with the experiment for the reliability evaluation of the CFD results through the present study.

• Proceedings of the Korean Society for Quality Management Conference
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• 1998.11a
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• pp.429-434
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• 1998

QS-9000 was established by Chrysler, Ford, General Motors and some Truck Manufactures to solve problems of efforts to prepare original standards for each company. When we compare the requirements in QS-9000 with those in ISO 9000, we may observe that those of QS-9000 are more specific, since the user of the standard is limited to the automobile industry. In particular, the requirements on statistical techniques are described in more detail. In this paper, we present the requirements on statistical techniques in QS-9000. Specifically, we review the contents of QS-9000 and explore the philosophy and the minimum requirement on statistical techniques behind the description.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.227-230
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• 2009

In order to predict failure behavior of advanced high-strength steel sheets (AHSS) in hole expansion tests, damage model was developed considering surface condition sensitivity (with specimens prepared by milling and punching: 340R, TRIP590, TWIP940). To account for the micro-damage initiation and evolution as well as macro-crack formation, the stress triaxiality dependent fracture criterion and rate-dependent hardening and ultimate softening behavior were characterized by performing numerical simulations and experiments for the simple tension and V-notch tests. The developed damage model and the characterized mechanical property were incorporated into the FE program ABAQUS/Explicit to perform hole expansion simulations, which showed good agreement with experiments.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.231-234
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• 2009

Based on combined continuum-fracture mechanics, fracture criterion was utilized to predict impact performance of advanced high-strength steel sheets: 340R and TWIP940. The macro-crack propagation behavior at high stress triaxiality was characterized by V-notch tests while deformation behavior at high strain rate was characterized by simple tension tests with various cross head speeds. The characterized mechanical properties were incorporated into the FE program ABAQUS/Explicit to simulate the charpy impact tests, which showed good agreement with experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.753-757
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• 2004

This paper describes a PC-based distributed multi-rate realtime control system using USB protocol, which is developed as a general motion controller. The control system consists of two control programs: one running at 1 kHz sampling rate on a PC with Linux and another running at 10 kHz sampling rate on a remotely located motion control card called RASID (remote axis serial interface device). Two programs communicates through USB at every 1 msec. A USB communication driver is developed to ensured the 1 msec desired communication time. The main program running on the PC generates reference trajectory at 1 kHz and send it to the RASID through USB and RASIDs located near the motors gather the sensor information and execute the low-level control at 10 kHz. The USB-based connectivity reduces the wiring harness and eventually the manufacturing cost of the machine. The multi-rate nature of the developed system improves the control capability. The effect of sampling rate is analyzed and simulated.