• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.1426-1428
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• 2011

컴퓨터에서 사용하는 데이터의 기본 단위는 2진수 형식으로 표현되는 이진(binary) 데이터이며 이는 CPU 연산에서부터 이기종간 네트워크 통신에 이르기까지 폭넓은 영역에서 사용되고 있다. 이진데이터를 처리하는 소프트웨어를 개발하기 위하여 다양한 원시타입(Primitive Type)을 사용하는 프로그래밍 언어가 사용되는데, 일반적으로 이러한 프로그래밍 언어를 통한 개발은 소스코드에 구조체, 공용체 및 클래스로 이진 데이터를 정적으로 정의함으로써 추후 데이터 변경에 대한 유연성이 떨어지는 문제가 존재한다. XML 기반의 객체 모델은 프로그래밍 언어에서 사용되는 모든 타입 및 이진 데이터 구성 형식을 제공하고 이를 통해 이진 데이터를 동적으로 관리함으로써 이러한 유연성의 문제를 해결하고 있으며 실제 이진 데이터를 사용하는 분야에 적용할 수 있다.

• Polymer(Korea)
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• v.31 no.1
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• pp.37-46
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• 2007

Fully or nearly fully 6- [4- (4'- (nitrophenylazo)phenoxycarbonyl)]pentanoated polysaccharide derivatives were synthesized by reacting cellulose, amylose, chitosan, chitin, alginic acid, pullulan or amylopectin with 6- [4- (4'- (nitrophenylazo)phenoxy) ] pentanoyl chloride (NA6C) and their thermotropic liquid crystalline behaviors were investigated. Like in the case of NA6C, all the polysaccharide derivatives formed monotropic nematic phases, suggesting that the mesophase structure of the polysaccharide derivatives is dertermined by the mesogenic side groups and not by the polysaccharide backbone. This is the first report of polysaccharide derivatives, except cellulose derivative, that form thermotropic nematic phases. The thermal stability and degree of order of the nematic phases observed for poly saccharide derivatives were significantly different from those reported for the polymers in which the azobenzene groups are attached to flexible or rigid backbones through flexible spacers. The results were discussed in terms of the difference in the arrangement of the main and side chains and the flexibility of the main chain.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.835-836
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• 2010

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.132-133
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.563-564
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• 2011

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.258-263
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• 2009

This paper describes an analysis of the stability and performance of a large-capacity flywheel energy storage system (FESS) supported by active magnetic bearings. We designed and manufactured the system that can store up to 5kWh of usable energy at the maximum speed of 18,000 rpm. In order to analyze the stability of the systems accurately, we derived a rigid body rotor model, flexible rotor model using finite-element method, and a reduced-order model using modal truncation. The rotor model is combined with those of active magnetic bearings, amplifiers, and position sensors, resulting in a system simulation model. This simulation model is validated against experimental measurements. The stability of the system is checked from the pole locations of the closed-loop transfer functions. We also investigated the sensitivity function to quantify the robustness of the systems to the disturbances such as mass imbalance and sensor noises.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.197-204
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• 2003

This paper develops a computer model for estimating the handling of a cabover type large-sized truck. The truck is composed of front and rear suspension systems, a frame, a cab, and ten tires. The computer model is developed using ADAMS. A shock absorber, a rubber bush, and a leaf spring aunt a lot on the dynamic characteristic of the vehicle. Their stiffness and damping coefficient are measured and used as input data of the computer model. Leaf springs in the front and rear suspension systems are modeled by dividing them three links and joining them with joints. To improve the reliability of the developed computer model, the frame is considered as a flexible body. Thus, the frame is modeled by finite elements using MSC/PATRAN. A mode analysis is performed with the frame model using MSC/NASTRAN in order to link the frame model to the computer model. To verify the reliability of the developed computer model, a double lane change test is performed with an actual vehicle. In the double lane change, lateral acceleration, yaw rate, and roll angle are measured. Those test results are compared with the simulation results.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.7
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• pp.805-813
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• 2011

The dynamic stress of the diesel engine block is analyzed by using flexible-body dynamic analysis. Multiple loadings including the pressure load due to gas combustion, thermal load, and dynamic load are considered. Thermal load is assumed constant, however, pressure load and dynamic load are treated as time dependent. The present work is focused on the dynamic stress analysis, especially on finding critical points of the engine block. The analysis model includes four parts - engine block, generator, bed, and mounts. On the other hand, crank shaft, pistons, and main bearings are excluded from the model. However, their dynamic effects are applied by dynamic forces, obtained in the separate analysis. Dynamic stress is found by using flexible body dynamic analysis, and compared to the measured data.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.16-22
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• 2010

Various programs for dynamic simulation of the railway vehicle have advantages and disadvantages. These programs have limitation that cannot express a large deformable body for an wire of the railway vehicle. In this study, a program for dynamic simulation of the railway vehicle is developed. And the rigid, flexible and large deformable body can be simulated using this program. Its reliability is verified by comparison with a commercial program. Also, a wire is considered as the large deformable body and a sliding joint which connects the rigid body to the large deformable body is included. Moreover, as the wheel-rail contact module is added, the dynamic simulation of the railway vehicle can be analyzed using the developed program.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.3
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• pp.17-26
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• 2010

Pb-Sn solder is rapidly being replaced by lead-free solder for board-level interconnection in microelectronic package assemblies due to the environmental protection requirement. There is a general lack of mechanical reliability information available on the lead-free solder. In this study, thermo-mechanical behaviors of wire-bond plastic ball grid array (WB-PBGA) package assemblies are characterized by high-sensitivity moire interferometry. Experiments are conducted for two types of WB-PBGA packages that have Pb-Sn solder and lead-free solder as joint interconnections. Using real-time moire setup, fringe patterns are recorded and analyzed for several temperatures. Bending deformations of the assemblies and average strains of the solder balls are investigated and compared for the two type of WB-PBGA package assemblies. Results show that shear strain in #3 solder ball located near the chip shadow boundary is dominant for the failure of the package with Pb-Sn solder, while normal strain in #7 most outer solder ball is dominant for that with lead-free solder. It is also shown that the package with lead-free solder has much larger bending deformation and 10% larger maximum effective strain than the package with Pb-Sn solder at same temperature level.