• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.5
• /
• pp.530-537
• /
• 2019

In this paper we propose a novel approach to representation of the 3D reconstruction problem by employing a concept of system function that is defined as the ratio of the output to the input signal. Akin to determination of system function (or system response), this paper determines system function by choosing (or defining) appropriate input and output signals. In other words, the 3D reconstruction using structured circular light patterns is reformulated as determination of system function from input and output signals. This paper introduces two algorithms for the reconstruction. The one defines the input and output signals as projected circular light patterns and the images overlaid with the patterns and captured by camera, respectively. The other one defines input and output signals as 3D coordinates of the object surface and the image captured by camera. The first one leads to the problem as identifying the system function and the second one leads to the problem as estimation of an input signal employing concept of modulation-demodulation theory. This paper substantiate the proposed approach by providing experimental results.

• Journal of Practical Engineering Education
• /
• v.11 no.1
• /
• pp.1-8
• /
• 2019

Virtual Training is an educational exercise in which the environment or the situation is virtually implemented for specific training and proceed like a real situation. In recent years, the virtual reality technology has developed rapidly, and the demand for experiencing situation that are not directly experienced in the real world is increasing more and more in virtual reality. Particularly, there is an increasing demand of contents for hands-on training and virtual training for equipment training that replaces high-risk and high-cost industry training. The virtual training contents have been developed and utilized for the purpose of technical training. However, it is known that virtual training is more effective when it is used as a supplementary training material or combined with e-learning contents rather than replacing one training course with virtual training contents because purpose and effect are different from general technical training course. In this study, we explored the development method for effective utilization of electrohydraulic servo control process, which is the virtual reality contents developed in 2017 in combination with e-learning contents. In addition, in order to establish a teaching and learning strategy, we actually develop and operate a case studies using virtual training contents. Surveys and case studies are conducted to investigate the effects of teaching and learning strategies applied in the classroom on students and their educational usefulness.

• Knowledge Management Research
• /
• v.22 no.2
• /
• pp.227-246
• /
• 2021

In the context of the global pandemic caused by COVID-19, emergency alert text messages can violate the privacy of confirmed corona positive cases. This study used conjoint analysis to identify the essential information factors and the privacy invasion information factors of local government initiated safety notices. As a result of this study, we found eight essential information factors, including all routes of the confirmed case and ten privacy invasion factors of safety notices. In addition, we found that there is a similarity between the combinations of information perceived to be the most essential and perceived as the most significant privacy invasion; both combinations include the confirmed case's personal and route information. This study ultimately tried to suggest a way to lower the concern about privacy invasion of the confirmed cases without damaging the emergency alert text messages' essential information. We expect that this study will provide researchers and policymakers interested in disaster communication with valuable theoretical and practical implications.

• Journal of the Institute of Convergence Signal Processing
• /
• v.21 no.2
• /
• pp.61-66
• /
• 2020

Recently, a variety of electric anesthetics devices have been developed and used in clinical practice to reduce the fatigue of the operator during local anesthesia for dental procedures and to compensate for the disadvantages of manual anesthesia device. In this electric anesthesia injection device, the accurate and constant delivery of pressure for drug infusion is a very important performance factor. In order to evaluate the accuracy of the transfer pressure, a small pressure gauge using a load cell is often used, but since the elastic body inside the load cell may not be able to accommodate a sufficient displacement, an error may occur when evaluating pressure performance. For these reasons, in this study, we proposed and evaluated a silicon-chrome steel (Si-Cr steel) spring jig that can accommodate relatively large displacements that can be used when evaluating the performance of a pressure-controlled pressure application device using a load cell type pressure gauge. As a result of the pressure transmissibility test and repeated measurement results using a commercial dental anesthesia injection device, a more stable result was obtained when using a spring jig, and it was confirmed that the frequency of abnormally high measurement was reduced.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.2
• /
• pp.774-780
• /
• 2021

The auxiliary power unit (APU) of a rotorcraft starts the engine during operation/flying. The APU is composed of a gas turbine engine type. The starting principle of the component is that the electric start motor generates the power required for starting by rotating the shaft. In this study, quality improvement was performed by applying an over-running clutch (ORC) between the APU and the starter motor to secure the operability of the starter motor of the APU mounted on the rotorcraft. The starter motor has the main role of starting the APU, but during operation, it is rotated without load by the rotational force of the APU gear shaft, resulting in friction at the brush. This phenomenon causes abrasion of the brush of the starter motor. Consequently, when the APU operation time increases, the brush life decreases, and the operability of the APU is affected. In this study, an ORC that separates the interlocking between the start motor brush abrasion and the APU operation time was applied to improve the operability/durability of the APU starter motor. The effect was verified through a test, and the technical feasibility of the design change was analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.1
• /
• pp.461-467
• /
• 2021

Among the defect factors that can occur when a wafer-level lens is molded using a thermosetting material, the mold sticking problem of a molded lens during the release process can damage the molded substrate and deform the substrate at the wafer level. An experiment was conducted to examine the factors affecting the demolding force in the lens forming process. The demolding force was examined according to the coating material of the molds. The mold was surface-treated with ITO and Ti, followed by plasma treatment in an O2 atmosphere. A DLC coating was then performed, and the curing and releasability were examined. A coating method for the pull-off experiment was selected based on the results. To measure the demolding force according to the curing process conditions, a method of curing at a constant pressure and a method of curing at a constant position were applied. As a result, the TiO2 surface treatment reduced the release force. When cured by controlling the location, curing shrinkage can reduce the adhesion energy of the interface during curing, resulting in better demolding.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.6
• /
• pp.175-182
• /
• 2020

The non-contact eye tracking is a nonintrusive human-computer interface providing hands-free communications for people with severe disabilities. Recently. it is expected to do an important role in non-contact systems due to the recent coronavirus COVID-19, etc. This paper proposes a novel approach for an eye mouse using an eye tracking method based on a context-aware based AdaBoost multi-region classifier and ASSL algorithm. The conventional AdaBoost algorithm, however, cannot provide sufficiently reliable performance in face tracking for eye cursor pointing estimation, because it cannot take advantage of the spatial context relations among facial features. Therefore, we propose the eye-region context based AdaBoost multiple classifier for the efficient non-contact gaze tracking and mouse implementation. The proposed method detects, tracks, and aggregates various eye features to evaluate the gaze and adjusts active and semi-supervised learning based on the on-screen cursor. The proposed system has been successfully employed in eye location, and it can also be used to detect and track eye features. This system controls the computer cursor along the user's gaze and it was postprocessing by applying Gaussian modeling to prevent shaking during the real-time tracking using Kalman filter. In this system, target objects were randomly generated and the eye tracking performance was analyzed according to the Fits law in real time. It is expected that the utilization of non-contact interfaces.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.1
• /
• pp.499-505
• /
• 2022

Recently, the metaverse has been receiving a lot of attention. Metaverse means a virtual space, and various events can be held in this space. In particular, 360-degree video, a format optimized for the metaverse space, is attracting attention. A 360-degree video image is created by stitching images taken with multiple cameras or lenses in all 360-degree directions. When shooting a 360-degree video, a variety of shooting equipment, including a shooting staff to take a picture of a subject in front of the camera, is displayed on the video. Therefore, when shooting a 360-degree video, you have to hide everything except the subject around the camera. There are several problems with this shooting method. Among them, lighting is the biggest problem. This is because it is very difficult to install a fixture that focuses on the subject from behind the camera as in conventional image shooting. This study is an experimental study to find the optimal angle for 360-degree images by adjusting the angle of indoor lighting. We propose a method to record 360-degree video without installing additional lighting. Based on the results of this study, it is expected that experiments will be conducted through more various shooting angles in the future, and furthermore, it is expected that it will be helpful when using 360-degree images in the metaverse space.

• KIPS Transactions on Computer and Communication Systems
• /
• v.11 no.10
• /
• pp.373-380
• /
• 2022

This paper presents a deep learning based group synchronization that supports networked immersive interactions between remote users. The goal of group synchronization is to enable all participants to synchronously interact with others for increasing user presence Most previous methods focus on NTP-based clock synchronization to enhance time accuracy. Moving average filters are used to control media playout time on the synchronization server. As an example, the exponentially weighted moving average(EWMA) would be able to track and estimate accurate playout time if the changes in input data are not significant. However it needs more time to be stable for any given change over time due to codec and system loads or fluctuations in network status. To tackle this problem, this work proposes the Deep Group Synchronization(DeepGroupSync), a group synchronization based on deep learning that models important features from the data. This model consists of two Gated Recurrent Unit(GRU) layers and one fully-connected layer, which predicts an optimal playout time by utilizing the sequential playout delays. The experiments are conducted with an existing method that uses the EWMA and the proposed method that uses the DeepGroupSync. The results show that the proposed method are more robust against unpredictable or rapid network condition changes than the existing method.

• KIPS Transactions on Computer and Communication Systems
• /
• v.11 no.10
• /
• pp.345-352
• /
• 2022

Recent LiDAR(Light Detection And Ranging) sensor is used for scanning object around in real-time. This sensor can detect movement of the object and how it has changed. As the production cost of the sensors has been decreased, LiDAR begins to be used for various industries such as facility guard, smart city and self-driving car. However, LiDAR has a large input data size due to its real-time scanning process. So another way for processing a large amount of data are needed in LiDAR system because it can cause a bottleneck. This paper proposes edge computing to compress massive point cloud for processing quickly. Since laser's reflection range of LiDAR sensor is limited, multiple LiDAR should be used to scan a large area. In this reason multiple LiDAR sensor's data should be processed at once to detect or recognize object in real-time. Edge computer compress point cloud efficiently to accelerate data processing and decompress every data in the main cloud in real-time. In this way user can control LiDAR sensor in the main system without any bottleneck. The system we suggest solves the bottleneck which was problem on the cloud based method by applying edge computing service.