• KSTLE International Journal
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• v.3 no.2
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• pp.101-109
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• 2002

This paper presents the fabrication and performance inspection of a peristaltic micropump by flow simulation. The valve-less micropump using the diffuser/nozzle is consists of base plate, mid plate, top plate and connection tubes fur inlet and outlet. In detail, the base plate is composed of two diffuser nozzles and three chambers, the mid plate consists of a glass diaphragm for the volumetric change of the pumping chamber. The inlet and outlet tubes are connected at the top plate and the actuator fur pressing the diaphragm is located beneath the top plate. The micropump is fabricated on the silicon wafer by DRIE (Deep Reactive ion Etching) process. The pumping performances are tested by the pneumatic test rig and compared with the simulated results fur various dimensions of diffuser nozzles. The pumping characteristics of the micropump by the volumetric change at the pumping chamber is modeled and simulated by the commercial software of FLOW-3D. The simulated results shows that reverse flow is the inherent phenomena in the diffuser nozzle type micropump, but it can be reduced at the dual pumping chamber model.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.34-39
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• 2010

The purpose of this study is to suggest objective evaluation model as a plan to utilize as opportunity in establishing judgment standard of mutual inspection criteria and to upgrade inspection ability by reviewing and analyzing level of danger and importance in advance based on inspection results of inspection institutions regarding tower cranes used in construction fields. Tower crane is a mechanical device transporting construction supplies and heavy materials to places over 20~150M high from the ground for the period ranging from a short time of 2~3 months to two years after being installed in construction sites in vicinity of buildings or structures and is an important facility indispensable for construction sites. However, since use period after installation is short and professional technical ability of technicians working on-site about of tower crane is poor, systematic and quantitative safety management is not carried out As a part of researches on procedure of RBI(Risk Based Inspection) possible to apply to Knowledge Based System based on knowledge and experiences of experts as well as to tower cranes for solving these problems, quantitative RPN(Risk Priority Number) was applied to RPN utilizing technique of FMEA(Failure Mode and Effect Analyses). When general RBI 80/20 Rule was applied parts with high level of risks were found out as wire rope, hoist up/down safety device, reduction gear, and etc. However, since there are still many insufficient parts as risk analyses of tower crane were not established, it is necessary for experts with sufficient experiences and knowledge to supplement active RBI techniques and continuous researches on tower cranes by sharing and setting up data base of important information with this study as a starting point.

• Korean Journal of Construction Engineering and Management
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• v.18 no.5
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• pp.59-67
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• 2017

At the completion of the construction, various finishing processes are concentrated. This imposes a burden on the on-site manager and imposes on experience based quality control, thereby causing deviations in the quality of construction depending on supervisor or worker's individual competence. In addition, the information related to quality control is frequently scattered in various types of documents such as specifications and drawings, and checkpoints are frequently omitted. It is necessary to provide a tool that can effectively provide the practitioner before or during the inspection work by systematically storing the information related to the defect prevention and linking them in a mutually referential state. This paper proposes an quality inspection support model that can systematically store necessary information on activity or room basis for the quality check of the apartment house finishing work. Establish a defect prevention information base and a information nexus by linking specifications, design standards, checklists, regulations, defect cases, and drawings to the finishing process and the rooms. Based on this, information registration and search interface are presented. It can contribute to securing a certain level of construction quality or more by suggesting a frame that can be utilized by linking various defects prevention information with the focus on closing activity and room.

• The Journal of Advanced Prosthodontics
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• v.12 no.5
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• pp.307-315
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• 2020

PURPOSE. The purpose of this study was to evaluate the occurrence of displacement while tightening the screw of scan bodies, which were compared according to the material type. MATERIALS AND METHODS. Three types of scan bodies whose base regions were made up of polyether ether ketone (PEEK) material [Straumann Group, Dentium Group, and Myfit (PEEK) Group] and another scan body whose base region was made up of titanium material [Myfit (Metal) Group] were used (15 per group). The reference model was fabricated by aligning the scan body library on the central axis of the implant, and moving this position by the resin model. The screws of the scan bodies were tightened to the implant fixture with torques of 5 Ncm, 10 Ncm, and a hand tightening torque. After the application of the torque, the scan bodies were scanned using a laboratory scanner. To evaluate the vertical, horizontal, and 3-dimensional (3D) displacements, a 3D inspection software program was used. To examine the difference among groups, one-way analysis of variance and Tukey's HSD post hoc test were used (α=.05). RESULTS. There were significant differences in 3D, vertical, and horizontal displacements among the different types of scan bodies (P<.001). There was a significantly lower displacement in the Straumann group than in the Myfit (PEEK) and Dentium groups (P<.05). CONCLUSION. The horizontal displacement in all groups was less than 10 ㎛. With the hand tightening torque, a high vertical displacement of over 100 ㎛ occurred in PEEK scan bodies (Myfit and Dentium). Therefore, it is recommended to apply a tightening torque of 5 Ncm instead of a hand tightening torque.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2172-2180
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• 2016

As increasing the emphasis of competence-based learning, Project-base instruction is adopted more with frequency at the educational field. This study focuses on developing the methodology of project-based instructional system. The first one is to manage the project independently not to link with any module. The second one is to link a project to a module. And the third one is to link a project to the more than two major modules. Also It suggests the tool for project based instruction. Before & after class conducting the inspection for increasing satisfaction of instruction by the systematic management and improvement, the project base instruction shows the positive effect to promote the creative personality and problem solving ability. The contentment of the class increases 7% more at the 2nd year than the 1st. As a result, it can derive the evaluation of the pupils' higher achievement rate.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.615-618
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• 2002

This paper proposes a real-time face detection and tracking a method in complex backgrounds. The proposed method is based on the principal component analysis (PCA) technique. For the detection of a face, first, we use a skin color model and motion information. And then using the PCA technique the detected regions are verified to determine which region is indeed the face. The tracking of a face is based on the Euclidian distance in eigenspace between the previously tracked face and the newly detected faces. Camera control for the face tracking is done in such a way that the detected face region is kept on the center of the screen by controlling the pan/tilt platform. The proposed method is extensible to other systems such as teleconferencing system, intruder inspection system, and so on.

• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.77-86
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• 2014

Objective: The purpose of this study is to grasp the fundamental structure of incident occurrence in nuclear organizations based on system thinking, and analyze how various causes are interrelated in terms of the causal loop diagram. Background: The recent domestic and overseas nuclear power plant-related incidents and accidents are directly or indirectly associated with safety culture, and thus effective plans for the improvement of safety culture are being called for. While the safety of a nuclear power plant is highly dependent upon technology and equipment, the utilization, maintenance and inspection of the technology and equipment are conducted by workers of the nuclear power plant. Method: Methodology of system thinking perspective using causal loop analysis. Results: As a result of the analysis, first, it turned out that the fundamental cause of incident occurrence in nuclear organizations is time constraint. Second, if a workload of workers increases, their adherence to regulations and procedures comes to be reduced due to time constraint. Third, it is needed, through organizational learning education, to increase actions made from thoughts considering safety as the utmost priority in advance. Fourth, it is necessary to improve professionalism by enhancing educational programs for new workers, and to develop various scenarios with which they can cope with certain situations. Application: This paper provides a base for system dynamics simulation model for future study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.277-280
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• 2000

Reverse Engineering is a procedure where the results of engineering decisions in manufacturing is feedback to the design phase and the knowledge-base is generated from the process know-how to reduce the errors. Since it used to take lots of time and efforts to finalize the machining of dies out of the original CAD design especially for die spotting and try-outs, reverse engineering is important to improve the productivity and quality of the die manufacturing process. In this regard, we developed system to support reverse engineering in machining of stamping dies for auto-body production. They automatically generate the relevant MC programs for a CMM simply with the input of measuring points in CAD environments, and show the CAD model and the results of inspection simultaneously for the ease of comparison. They also help reduce the overall clearance between the lower and upper dies. Applying these systems to the machining process of stamping dies, we could improve the reliability of measuring and get the optimal compensation distance between the two dies. We also analyzed the expected benefits of the system in terms of savings in time and costs.

• Geomechanics and Engineering
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• v.33 no.2
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• pp.203-209
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• 2023

One major advantage of ground penetrating radar (GPR) over other field test methods is its ability to obtain subsurface images of roads in an efficient and non-intrusive manner. Not only can the strata of pavement structure be retrieved from the GPR scan images, but also various irregularities, such as cracks and internal cavities. This article introduces a deep learning-based approach, focusing on detecting subsurface cracks by recognizing their distinctive hyperbolic signatures in the GPR scan images. Given the limited road sections that contain target features, two data augmentation methods, i.e., feature insertion and generation, are implemented, resulting in 9,174 GPR scan images. One of the most popular real-time object detection models, You Only Learn One Representation (YOLOR), is trained for detecting the target features for two types of subsurface cracks: bottom cracks and full cracks from the GPR scan images. The former represents partial cracks initiated from the bottom of the asphalt layer or base layers, while the latter includes extended cracks that penetrate these layers. Our experiments show the test average precisions of 0.769, 0.803 and 0.735 for all cracks, bottom cracks, and full cracks, respectively. This demonstrates the practicality of deep learning-based methods in detecting subsurface cracks from GPR scan images.

• Journal of Korean Society for Quality Management
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• v.48 no.2
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• pp.297-307
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• 2020

Purpose: The purpose of this study is to analyze the factors that affect ammunition performance by applying data mining techniques to the Ammunition Stockpile Reliability Program (ASRP) data of the 155mm propelling charge. Methods: The ASRP data from 1999 to 2017 have been utilized. Logistic regression and decision tree analysis were used to investigate the factors that affect performance of ammunition. The performance evaluation of each model was conducted through comparison with an artificial neural networks(ANN) model. Results: The results of this study are as follows; logistic regression and the decision tree analysis showed that major defect rate of visual inspection is the most significant factor. Also, muzzle velocity by base charge and muzzle velocity by increment charge are also among the significant factors affecting the performance of 155mm propelling charge. To validate the logistic regression and decision tree models, their classification accuracies have been compared with the results of an ANN model. The results indicate that the logistic regression and decision tree models show sufficient performance which conforms the validity of the models. Conclusion: The main contribution of this paper is that, to our best knowledge, it is the first attempt at identifying the significant factors of ASPR data by using data mining techniques. The approaches suggested in the paper could also be extended to other types ammunition data.