• Journal of the korean Society of Automotive Engineers
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• v.16 no.2
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• pp.45-54
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• 1994

미국 등 선진국에서는 복합재료 자동차 차체 및 부품에 관한 연구를 활발히 수행하고 있다. 그러나, 국내 자동차 업계의 역사가 짧고, 보수성으로 인하여 복합재료 차체와 부품에 대한 연구와 응용이 부족한 형편이다. 따라서 본 고에서는 복합재료의 성질을 고찰한후에, 드라이브 샤프트와 Door Side Impact Beam을 복합재료로 설계하는 예를 설명하고자 한다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.5
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• pp.609-615
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• 2016

Measuring similarity between two signals is a key element of the location template matching (LTM) method which is one of impact source localization technique. As a measure of similarity, the correlation coefficient is most widely used, and the group delay based method is recently proposed to improve the accuracy of finding the impact source. In practice, the LTM method assumes that the similarity between two signals decreases as the distance between two corresponding impact points increases, where the distance between two neighboring impact points defines the grid spacing. In this paper, it is shown that this assumption is not always true but the correlation coefficients fluctuate forming a main robe and many side robes as the distance between two neighboring impact points increases. On the other hand, the standard deviation of group delay sharply increases with a small increase of the grid spacing. These are demonstrated by using a simple cantilever beam. Based on these findings, an optimal way of implementing the LTM method may be suggested by combining the correlation coefficient and the group delay based approaches.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.3
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• pp.8-15
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• 2011

The computer-based simulation tools are currently used overwhelmingly to simulate the performance of automotive designs. Then, the search for an optimal solution that satisfies a number of performance requirements usually involves numerous iterations among several simulation tools. Therefore, meta-modeling techniques are becoming widely used to build approximations of computationally expensive computer analysis tools. The set-based approach proposed in the first report of a four-part paper has been a test bed for the innovation of vehicle structure design process in the Structural Design and Fabrication Committee of JSAE(Society of Automotive Engineers of Japan). In the second report, the proposed design approach is illustrated with a side-door impact beam design example using meta-modeling techniques.

• Journal of Ocean Engineering and Technology
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• v.14 no.2
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• pp.89-98
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• 2000

Using conventional textile techniques such as weaving braiding knitting and stitching it is possible to produce a wide range two and three dimensional fiber preforms, however so far only a limited attention has been given to knitted fabrics in composite industry. This is mainly due to the opinion that knitted fabric reinforced composites posses low mechanical properties owing to their looped fiber architecture. But it is possible to obtain desired mechanical properties by selecting proper knitted fabric structure, In this paper mechanical characteristics of kevlar plain weft knitted fabrics reinforced plastics(KFRP) are evaluated for th development of intrusion beam of car side door. Tensile bending impact properties of KFRP are measured experimentally and crush demands of Americal Federal Motor Vehicle Safety Standard No.214(FMVSS 214) compared with the bending load and displacement of KFRP by quasi-static test method. The applicability and limitation of bending load and displacement of KFRP according to specimen size has been discussed.

• Imaging Science in Dentistry
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• v.43 no.1
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• pp.25-30
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• 2013

Purpose: This study was performed to determine the prevalence of bifid mandibular condyles (BMCs) in asymptomatic and symptomatic temporomandibular joint (TMJ) subjects with no traumatic history, and to assess their impact on clinical and radiographic manifestations of TMJ. Materials and Methods: A total of 3,046 asymptomatic and 4,378 symptomatic patients were included in the study. Cone-beam computed tomography (CBCT) images were reviewed for bifid condyles. T-tests were used to compare the frequency of BMCs when stratified by symptom, gender, and side. In BMC patients, the clinical features of pain and noise, osseous changes, and parasagittal positioning of the condyles were compared between the normally shaped condyle side and the BMC side using chi-squared tests. Results: Fifteen (0.49%) asymptomatic and 22 (0.50%) symptomatic patients were found to have BMCs. Among the bilateral cases, the number of condyles were 19 (0.31%) and 25 (0.29%), respectively. No statistically significant differences were found between asymptomatic and symptomatic patients, between female and male patients, or between the right and left sides (p>0.05). Compared with the normally shaped condyle side, the BMC side showed no statistically significant differences in the distribution of pain and noise, parasagittal condylar position, or condylar osseous changes, with the exception of osteophytes. In the symptomatic group, osteophytes were found more frequently on the normally shaped condyle side than the BMC side (p<0.05). Conclusion: BMCs tended to be identified as an incidental finding. The presence of BMC would not lead to any TMJ symptoms or cause osseous changes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.4
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• pp.138-144
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• 2011

The design flexibility and robustness have become key factors to handle various sources of uncertainties at the early phase of design. Even though designers are uncertain about which single values to specify, they usually have a preference for certain values over others. In the first and second reports of a four-part paper, a set-based design approach has been proposed for achieving design flexibility and robustness while capturing designer's preference, and its effectiveness has been illustrated with a simple vehicle side-door impact beam design problem. This report presents the applicability of the proposed design approach to the large-scale multi-objective design optimization with a successful implementation of real vehicle side-door structure design.

• Journal of the Korean Geotechnical Society
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• v.35 no.11
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• pp.25-36
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• 2019

The safety barrier is installed on road embankment to prevent vehicles from falling into road side slope. Among the safety barrier, flexible guardrails are usually installed. The flexible guardrail generally consists of a protection cross-beam and supporting in-line piles. These guardrail piles are installed nearby slope edge of road embankment because the side area of the road is much narrow. The protection cross-beam absorbs impact energy caused by vehicle collision. The pile-soil interaction also absorbs the rest of the impact energy and then, finally, the flexible guardrail system resists the impact load. This paper aims to investigate the pile-soil interaction subjected to impact load using centrifuge model tests. In this study, a single pile was installed in compacted residual soil and loaded under lateral impact load. An impact loading system was designed and developed available on centrifuge tests. Using this loading system, a parametric study was performed and the parameters include types of loading and ground. Finally, the ultimate bearing capacity of supporting pile under impact load was analyzed using load-displacement curve and soil reaction pressure distributions at ultimate were evaluated and compared with previous studies.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.50-57
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• 2013

Characterization of microstructures and cryogenic mechanical properties of electro beam (EB) welds between cast and forged Inconel 718 superalloys has been investigated. Optimal EBW condition was found in the beam current range of 36~39 mA with the constant travel speed of 12 mm/s and arc voltage of 120 kV for 10 mm-thick specimens. Electron beam current lower than 25 mA caused to occur the liquation microfissuring in cast-side heat affected zone (HAZ) of EB welds. The HAZ liquation microfissure was found on the liquated grain boundaries with resolidified ${\gamma}/Laves$ and ${\gamma}/NbC$ eutectic constituents. EBW produced welds showing a fine dendritic structure with relatively discrete Laves phase due to fast cooling rate. After post weld aging treatment, blocky Laves phase and formation of ${\gamma}^{\prime}+{\gamma}^{{\prime}{\prime}}$ strengtheners were observed. Presence of primary strengthener and coarse Laves particles in PWHT weld may cause to reduce micro-plastic zone ahead of a crack, leading to a significant decrease in Charpy impact toughness at $-196^{\circ}C$. Fracture initiation and propagation induced by Charpy impact testing were discussed in terms of the dislocation structures ahead of crack arisen from the fractured Laves phase.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.108-113
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• 2005

The damageability and repairability of similar platform type vehicles could be very concerned with design optimization. In all the vehicles crash tested, small size passenger vehicles were weakness in aspect of damageability and repairability. The most critical area appears to be repair cost considering that parts cost is the largest portion of total repair cost segments. Besides repair cost, attaching method of front sidemember and subframe are placed special importance for impact energy absorption and damageability and repairability. So in order to improve damageability and repairability of vehicle structure and body component of the monocoque type passenger vehicles, the end of front side member and front back beam should be designed with optimum level and to supply the end of front side member as a partial condition approx 300mm. The effectiveness of design concept on the 40% offset frontal impact characteristics of the passenger vehicle structure is investigated and summarized.

• Ocean Systems Engineering
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• v.10 no.2
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• pp.131-161
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• 2020

The objective of this study was to evaluate the downtime cost of side-by-side offloading operations in Malaysian waters. With the help of a numerical time domain tool, the structure and cable response of moored FPSO vessel was simulated for heading and beam sea-states under irregular waves. The weather downtime was assessed by comparing the response under operational wave condition with the pre defined industrial safe offloading criteria. Additionally, two cases of cable failure were simulated for each sea-state. The novel study on downtime cost was presented for three different location of Malaysia subcontinent for which the location specific wave scatter diagram facilitated to estimate the probability of occurrence of operational wave condition. It was concluded that an unpredictable increment in wave height by 0.5 m can significantly impact the production cost.