• Korean Journal of Materials Research
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• v.24 no.11
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• pp.591-598
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• 2014

In this research, magnesium powder was prepared by gas atomizing. Refinement behaviors of magnesium powder produced under different conditions were investigated using a mechanical milling (attrition milling) process. Analyses were performed to assess the characterization and comparison of milled powder with different steel ball sizes and milling times. The powders were analyzed by field emission scanning electron microscope, apparent density and powder fluidity. The particle morphology of the Mg powders changed from spherical particles of feed metals to irregular oval particles, then plate type particles, with an increasing milling time. Because of the HCP structure, deformation occurs due to the existence of the easily breakable C-axis perpendicular to the base, which results in producing plate-type powders. An increase in ball size and the impact energy of the magnesium powder maximizes the effect of refinement. Furthermore, it is possible to improve the apparent density and fluidity according to the smoothness of the surface of the initial powder.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.6
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• pp.33-38
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• 2012

EMB is considered as the next generation braking mechanism because it has simple structure and is environment friendly. However, as other brake mechanisms, EMB should be operated reliably for any operating conditions. EMB should be designed with fail-safe and fault-tolerant control concepts which require robust fault detection algorithms for various possible faults. In the design of fault detection algorithms, it is very difficult to construct faulty conditions in real EMB and thus, simulations are often used to emulate the faulty conditions. In this paper, a simulation tool is developed using the commercial software to emulate gear faults in the EMB mechanism. A backlash compensation algorithm is introduced based on contact point detection because screw backlash causes a delay in clamping force response time.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.54-63
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• 2011

An educational network system based on CAN protocol internal to a passenger ground vehicle has been developed. The developed network system has been applied to a commercial plug-in electrical vehicle and verified the educational applicability. To apply this in-vehicle network technology based on CAN, a suitable electric vehicle has been chosen and a CAN network structure has been designed, developed and manufactured. Since the commercial electric vehicle chosen as a test bed has its own proprietary electric network, we explain how the original electric network has been utilized and how the new network system has been designed. The developed network system on a real vehicle has been tested to show the applicability and the performance. Finally, the system has been applied at few classrooms to demonstrate how the in-vehicle network system works and to teach how to analyse the CAN signals. The developed system proven to be effective for educational purpose.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.6
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• pp.267-271
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• 2003

In this work, chemical solution derived Ca-doped zirconia fiber has been prepared by using calcium- and zirconium-naphthenate. Fibrous $ZrO_2$-CaO was drawn from a sticky mixture. Dried gel fibers were finally annealed at $1000^{\circ}C$ for 1 h in argon. 91 mol%$ZrO_2$-9 mol%CaO fiber consisted of tetragonal, monoclinic and $CaZrO_3$ phases after annealing at $1000^{\circ}C$. On the other hand, samples annealed at $500^{\circ}C$ consisted of almost tetragonal single phase. Homogeneous fibers surface at $500^{\circ}C$ became rougher after $1000^{\circ}C$-annealing. The sample annealed at $1000^{\circ}C$ with relatively rough surface structure showed a high Calcium phocphate forming ability.

• Journal of Korean Society for Quality Management
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• v.45 no.3
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• pp.521-532
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• 2017

Purpose: The purpose of this study is to structure affective factors related to the tactile sense in order to improve tactile sensibility satisfaction of interior material. In this paper, we propose the design direction of interior material by analyzing the association between material properties and affective factors for automotive interior material. Methods: The relationship between sensibility adjectives and feelings related to tactile sensation were derived through factor analysis after touching prepared samples that were made by changing the material properties of automotive interior material. The association between affective factors and interior material properties were analyzed through ANOVA. Results: Seven kinds of visual and tactile affective factors were derived from the correlation between feeling of material and sensibility adjectives measured by 215 subjects. It is found that there is a quadratic relationship rather than a linear relationship through association analysis between affective factors and the material properties such as roughness, friction coefficient, and hardness. Conclusion: This study suggests the direction of the interior material design which can improve the sensibility satisfaction of the automobile customers by identifying the tactile factors related to the material properties of automotive interior material.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.3
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• pp.352-359
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• 2015

This study investigates the analysis result of structure and fatigue due to the models of the hub space with bolt joint at wheel and the existence or nonexistence of hub ring as the part of suspension system of vehicle. As the static analysis result, the structural vulnerability can be found at hub bolt and the center of wheel at three models. Model 2 and 3 have nearly same deformation and model 1 can be endured at the least load among three models. As the fatigue analysis result, fatigue lives of three models are same at the severest load of SAE bracket history. As many screw threads of weak bolts are jointed in case of model 1, model 1 is shown to be the weakest at fatigue damage among three models. By the result of this study, model 1 with bolt joint becomes most weakest among three models. As model 2 with no hub ring and model 3 with hub ring have the nearly same states of analysis results, hub ring is shown to have no influence on the safety of automotive driving.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.6
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• pp.375-382
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• 2022

This paper proposes a multi-core cooperative computing structure considering the heterogeneous features of automotive embedded on-chip software. The automotive embedded software has the heterogeneous execution flow properties for various hardware drives. Software developed with a homogeneous execution flow without considering these properties will incur inefficient overhead due to core latency and load. The proposed method was evaluated on an target board on which a automotive MCU (micro-controller unit) with built-in multi-cores was mounted. We demonstrate an overhead reduction when software including common embedded system tasks, such as ADC sampling, DSP operations, and communication interfaces, are implemented in a heterogeneous execution flow. When we used the proposed method, embedded software was able to take advantage of idle states that occur between heterogeneous tasks to make efficient use of the resources on the board. As a result of the experiments, the power consumption of the board decreased by 42.11% compared to the baseline. Furthermore, the time required to process the same amount of sampling data was reduced by 27.09%. Experimental results validate the efficiency of the proposed multi-core cooperative heterogeneous embedded software execution technique.

• IEMEK Journal of Embedded Systems and Applications
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• v.16 no.6
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• pp.267-276
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• 2021

The automotive industry and academic research have been continuously conducting research on standardization such as AUTOSAR (AUTomotive Open System ARchitecture) and ISO26262 to solve problems such as safety and efficiency caused by the complexity of electric/electronic architecture of automotive. AUTOSAR is an automotive standard software platform that has a layered structure independent of MCU (Micro Controller Unit) hardware, and improves product reliability through software modularity and reusability. And, ISO26262, an international standard for automotive functional safety and suggests a method to minimize errors in automotive ECU (Electronic Control Unit)s by defining the development process and results for the entire life cycle of automotive electrical/electronic systems. These design methods are variously applied in representative automotive safety-critical systems. However, since the functional and safety requirements are different according to the characteristics of the safety-critical system, it is essential to research the AUTOSAR functional safety design method specialized for each application domain. In this paper, a software functional safety mechanism design method using AUTOSAR is proposed, and a new failure management framework is proposed to ensure the high reliability of the product. The AUTOSAR functional safety mechanism consists of memory partitioning protection, timing monitoring protection, and end-to-end protection. The fault management framework is composed of several safety SWCs to maintain the minimum function and performance even if a fault occurs during the operation of a safety-critical system. Finally, the proposed method is applied to the Shift-by-Wire system design to prove the validity of the proposed method.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.85-96
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• 1996

Most protection systems such as seat belts and airbags are not effective means for side structure. There has been significant effort in the automobile industries in seeking other protective methods, such as stiffer structure and padding on the door inner panel. Therefore, a car-to-car side impact model has been developed using ATB occupant simulation program and validated for test data of the vehicle. Compared to the existing side impact models, the developed model has a more detailed vehicle side structure representation for the more realistic impact response of the door. This model include impact bar which effectively increases the side structure stiffness without reduction of space between the occupant and the door and padding for absorbing impact energy. The established model is applied to a 4-door vehicle. The parameter study indicated that a stiffer impact bar would reduce both the acceleration-based criteria, such as thoracic trauma index: TTI(d), and deformation-based criteria, such as viscous criterion(VC). Padding on the door inner panel would reduce TTI(d) while VC gives the opposite indication in a specified thickness range. For a 4-door vehicle, the stiffness enhancement of B-pillar is more beneficial than that of A-pillar for occupant injury severity indices.

• International Journal of Automotive Technology
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• v.5 no.4
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• pp.247-255
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• 2004

The majority of real world frontal collisions involves partial overlap (offset) collision, in which only one of the two longitudinal members is used for energy absorption. This leads to dangerous intrusions of the passenger compartment. Excessive intrusion is usually generated on the impacted side causing higher contact injury risk on the occupants compared with full frontal collision. The ideal structure needs to have extendable length when the front-end structure is not capable to absorb crash energy without violating deceleration pulse requirements. A smart structure has been proposed to meet this ideal requirement. The proposed front-end structure consists of two hydraulic cylinders integrated with the front-end longitudinal members of standard vehicles. The work carried out in this paper includes developing and analyzing mathematical models of two different cases representing vehicle-to-vehicle and vehicle-to-barrier in full and offset collisions. By numerical crash simulations, this idea has been evaluated and optimized. It is proven form numerical simulations that the smart structures bring significantly lower intrusions and decelerations. In addition, it is shown that the mathematical models are valid, flexible, and can be used in an effective way to give a quick insight of real life crashes.