• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.435-438
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• 2001

Reverse engineering technology refers to the process that creates a CAD model of an existing part using measuring devices. Recently, non-contact scanning devices have become more accurate and the speed of data acquisition has increased drastically. However, they generate thousands of points per second and various types of point data. Therefore, it becomes a major issue to handle the huge amount and various types of point data. To generate a CAD model from scanned point data efficiently, these point data should be well arranged through point data handling processes such as data reduction and segmentation. This paper proposes a new point data handling method using 3D grids. The geometric information of a part is extracted from point cloud data by estimating normal values of the points. The non-uniform 3D grids for data reduction and segmentation are generated based on the geometric information. Through these data reduction and segmentation processes, it is possible to create CAD models autmatically and efficiently. The proposed method is applied to two quardric medels and the results are discussed.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.27 no.1
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• pp.263-290
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• 2016

The purpose of this study is to compare seven data science programs in Korea and ten data science programs in the US. Results show that 14 data science programs are housed in graduate schools. 10% of data science courses in Korea and 26% in the US fall under the Math and Statistics Knowledge area, one of the three areas defined by Conway. The syllabus analysis does not show much differences in terms of class contents and grading. The results of this study can be used to design data science programs that are more effective and well-grounded.

• The Journal of Korean Association of Computer Education
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• v.5 no.4
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• pp.19-29
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• 2002

This study focuses on applying the peer tutoring as an alternative instructional method in computer education. The purpose of this study is two folds: first, to examine the effect of peer tutoring on academic achievement; and second, to investigate the effect of peer tutoring on self-efficacy on learning about computer. To achieve the purpose, an experimental research was performed with 130 10th graders. The results showed no significant differences between the two groups on academic achievement, and among four groups of peer tutoring. However, there are significant differences on learners' self-efficacy.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.117-131
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• 2018

PBL is expected to be very useful in the engineering project course that leads students to active learning in problem solving process. But it is not actively utilized because of various problems. In this study, modified PBL lectures were laid out for a course that practice UX design process. Modified PBL lectures provide theoretical class and two PBL practices. The variant is that the problem design is made by the students themselves on a weekly basis, rather than by the instructor, and that the two PBL processes consist of one project. The results of this study are meaningful as a basic data in PBL-based engineering college project class. Additional discussion of how to evaluate grades needs to be specified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.5
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• pp.828-834
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• 1997

The knowledge of material stress-strain behavior is an essential requirement for design and analysis of deformation processes. Empirical stress-strain relationship and constitutive equations describing material behavior during deformation are being widely used, despite suffering some drawbacks in terms of ease of development, accuracy and speed. In the present study, back-propagation neural networks are used to model and predict the flow stresses of a HSLA steel under conditions of constant strain, strain rate and temperature. The performance of the network model is comparedto those of statistical models on rate equations. Well-trained network model provides fast and accurate results, making it superior to statistical models.

• Nuclear Engineering and Technology
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• v.19 no.1
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• pp.1-9
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• 1987

The fracture toughness of SA 533 Grade B Class 1 steel has been studied with the Charpy impact test specimens in a range of temperature between -4$0^{\circ}C$ and 288$^{\circ}C$. The dynamic fracture toughness is measured by the instrumented precracked Charpy impact test while the static fracture toughness is by the 3-point bend test based on the unloading compliance method. The results are compared with the data obtained from the large specimens. It is known through the studies that temperature dependence of the appropriate (a low bound) value of the fracture toughness can be estimated by taking the static fracture toughness above the transition temperature and the dynamic fracture toughness below the temperature and it is also shown that the tests are satisfied with the requirements of ASTM E 813 when the side-groove is more than 14%.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.29-29
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• 2010

레이저 용접은 고밀도 에너지빔을 이용하는 용접방법으로 아크용접에 비해 빠른 용접과 깊은 용입이 가능하며, 낮은 열이력을 가지는 장점이 있다. 때문에 열에 의해 연화되는 고강도강의 용접에 큰 이점을 가지고 있다. 차체경량화 추세와 더불어 차량에 고강도강의 적용이 늘어나고 있는데 충돌시 차량 구조를 유지시켜주는 범퍼나 B-필러와 같은 부품에 적용되는 무도금 보론 합금강과 알루미늄 코팅 보론 합금강은 핫스템핑(Hot Stamping) 기술에 의해 제조된 소재로 약 1.5GPa의 인장강도를 가진다. 알루미늄 코팅 보론 합금강의 경우 제조공정과 이송 중 소재 표면산화에 의한 산화철발생 또는 표면 탈탄 현상을 방지하기 위해 알루미늄 코팅 처리를 하는데 이러한 코팅층이 용접시 용접부의 물성을 저하시키는 역할을 한다고 보고되어 있다. 본 연구에서는 1.5GPa급 무도금 보론 합금강과 알루미늄 코팅 보론 합금강을 대상으로 레이저 용접을 적용하여 용접부 특성을 파악하고자 하였다. 실험은 겹치기 형상으로 Fiber Laser, Disk Laser를 적용하여 진행하였으며 빔Size, 용접속도, Gap등을 변경하며 해당조건에서의 용입특성, 파단모드, 기계적특성 등을 알아보았다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1191-1198
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• 2015

In this study, vehicle/track interaction analysis by the Saemaul powered vehicle was carried out. The prediction equation for the bending stress of rail was estimated using the rail bending stress by the rail surface irregularities at welds. Also, the fatigue analysis using a S-N curve of welds in the conventional railway was carried out. We estimated the fatigue life of CWR by the fracture probability. By the rail grinding, the fatigue life of CWR was evaluated in consideration to reduce the rail bending stress through removing the rail surface irregularities. Therefore, it presented the fatigue life of CWR according to the rail grinding execution plan in the conventional railway.

• Composites Research
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• v.23 no.5
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• pp.1-7
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• 2010

To increase the adhesive strength of acrylonitrile butadiene rubber(NBR) and steel plate, the atmospheric pressure flame plasma(APFP) treatment device is applied. The effect of various conditions(processing velocity and distance) is experimentally investigated to ascertain the optimum conditions to yield the best adhesive properties. It is found that the optimum distance between burner port and steel plate is 40mm and the optimum processing velocity is 50m/min at given condition. When the surface is coated twice with the bonding agent, the adhesion strength of APFP treated steel plate is increased to about 20.5%. It suggests that the surface modification of steel by flame plasma treatment at atmospheric pressure is a proper and applicable method to improve the adhesion strength between steel and rubber.

• Annual Conference of KIPS
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• 2000.10a
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• pp.11-14
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• 2000

대부분 기존의 Multimedia 시스템은 응용프로그램이나 사용자에 의해 발생되는 Operation 을 수동적인 형태로 처리를 한다. 개발자는 시스템의 목적이나 전략에 따라 시스템을 구성하는 각각의 Module에 대해 작업을 해야 하지만 목적이나 전략이 변경되면 해당되는 각각의 Module을 찾아서 수정을 해야만 한다. 이러한 일은 상당히 번거롭고 Error를 발생시킬 수 있는 가능성을 내포하고 있다. 또한 Multimedia 시스템은 적절한 정보를 관리하고 다양한 응용프로그램을 지원하기 위해서 많은 기능을 가져야 한다. 이 논문은 Event-Condition-Action(ECA) rule의 Active특성을 Multimedia 시스템에 적용하는 것을 제안하고 있다. 이러한 접근 방법을 통해 코드를 효과적으로 관리할 수 있다. 또한, Operation으로부터 rule을 정의하고 관리하는 것을 분리함으로써 Multimedia 시스템에 대해 상위 계층의 새로운 개념을 제시한다. 이렇게 Multimedia 시스템 상에 Active Rule시스템을 계층화시킴으로써 진보된 Multimedia 서비스를 제공할 수 있다. 시스템의 모든 기능은 Event에 의해 발생되고 Rule의 Condition이 만족할 때 해당하는 Rule의 Action이 실행된다. 여기서 제안한 Interactive Group Teaching System (IGTS) 시스템은 Active Rule 시스템인 Active Rule Management System(ARMS) 상에서 구현되었고, Active 속성을 가진 IGTS 을 설계하는 것을 목적으로 하고 있다. 본 시스템은 ECA Rule 개념이 적용 가능함을 보여준다.