• 한국전산유체공학회:학술대회논문집
• /
• 2005.10a
• /
• pp.235-238
• /
• 2005

The unsteady supersonic flow over two- and three-Dimensional cavities has been analyzed by the integration of unsteady Reynolds-Averaged Navier-Stokes(RANS) with the k - w turbulence model. The unsteady flow is characterized by the periodicity due to the mutual relation between the shear layer and the internal flow in cavities. Numerical method is upwind TVD scheme based on the flux vector split with the Van Leer limiters, and time accuracy is used explicit 4th stage Runge-Kutta scheme. Cavity flows are Comparison of two- and three-dimensional. The cavity has a L/D ratio of 3 for two-dimensional case. and same L/D and W/D ratio is 1 for three-dimensional case. The Mach and Reynolds numbers are held constant at 1.5 and 450000 respectively. For the three-dimensional case, the flow field is observed to oscillate in the 'shear layer mode' with a feedback mechanism that follow Rossiter's formula. On the other hand, the self-sustained oscillating flow transitions to a 'wake mode' for the two-dimensional simulation, with more violent fluctuations inside the cavity.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.15 no.3
• /
• pp.7-13
• /
• 2019

To improve the flow distribution at channel locations in the welded plate heat exchanger with "L"-type inflow, the flow visualization of Model 1 was carried out. Besides, the characteristics of flow distribution was investigated experimentally according to the header shape. The inlet flow rate for each channel location was increased at the side channels but decreased at the central channels. In the case of Model 2, which has a slant structure added to the basic header of Model 1, the unevenness of inlet flow increased by 23% from 0.019 to 0.023 as compared to Model 1. On the other hand, Model 3, which has a baffle structure added to Model 2, showed 0.064 unevenness in inlet flow, which was a 36% reduction one compared to Model 1. To improve the distribution at each channel in the welded plate heat exchanger with "L"-type flow, it is necessary to improve the header external shape for the guide of flow as well as the baffle structure for reduction of vortex flow.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2016.04a
• /
• pp.799-802
• /
• 2016

It is definitely an interesting job to work with V4 to create various contents emphasizing different interfaces like 3D graphics, and multimedia such as video, audio, and camera. Moreover, beyond the other interface, as it could be used in the many aspects of the sensory sign such as visual effects, auditory effects, and touchable effects, it feels free to make a better developed model. We intended the users to feel some kind of pleasure and interactions rather than just using in aspect of Media art.

• IEIE Transactions on Smart Processing and Computing
• /
• v.2 no.5
• /
• pp.255-265
• /
• 2013

3DTV is expected to be a promising next-generation broadcasting service. On the other hand, the visual discomfort/fatigue problems caused by viewing 3D videos have become an important issue. This paper proposes a perceptual quality assessment metric for a stereoscopic video (SV-PQAM). To model the SV-PQAM, this paper presents the following features: temporal variance, disparity variation in intra-frames, disparity variation in inter-frames and disparity distribution of frame boundary areas, which affect the human perception of depth and visual discomfort for stereoscopic views. The four features were combined into the SV-PQAM, which then becomes a no-reference stereoscopic video quality perception model, as an objective quality assessment metric. The proposed SV-PQAM does not require a depth map but instead uses the disparity information by a simple estimation. The model parameters were estimated based on linear regression from the mean score opinion values obtained from the subjective perception quality assessments. The experimental results showed that the proposed SV-PQAM exhibits high consistency with subjective perception quality assessment results in terms of the Pearson correlation coefficient value of 0.808, and the prediction performance exhibited good consistency with a zero outlier ratio value.

• The Korean Journal of Pain
• /
• v.26 no.2
• /
• pp.130-134
• /
• 2013

Background: The aims of this study were to analyze the anatomic variations of supraorbital foramina/notches in Koreans and to compare the results with those of previous studies examining other races. We evaluated the three-dimensional computed tomography (3D-CT) images of human faces using multidetector computed tomography (MDCT). Methods: A total of 395 adults (232 men and 163 women) were enrolled and the 3D-CT images of their faces were reviewed in this study. In this study, the data from the images included the presence, shape, width and distance from the nasion to the supraorbital foramina/notches. ANOVA was used to assess the main effects of gender and side (right or left foramen/notch), and comparisons of the means were done by paired t-test. Results: The most common shapes in Koreans were a single notch (39.5%) on the right hand side and a single foramen (42.3%) on the left hand side. The incidence of a single foramen in Koreans was high compared to other races. The mean foramen diameter was $2.34{\pm}0.78$ mm, and the mean distance from the nasion was $27.19{\pm}4.03$ mm. The mean notch diameter was $3.37{\pm}1.71$ mm, and the mean distance from the nasion was $23.42{\pm}2.45$ mm. Conclusions: This is the first study on the variations of supraorbital foramina/notches in Koreans using 3D-CT images of faces. The anatomic characteristics of the supraorbital foramina/notch will help in performing nerve blocks and maxillofacial surgery.

• Smart Media Journal
• /
• v.1 no.4
• /
• pp.18-26
• /
• 2012

The increase of the number of smartphone applications has enforced the importance of new user interface emergence and has raised the interest of research in the convergence of multiple sensors. In this paper, we propose a method for the convergence of acceleration, magnetic and gyro sensors to recognize the gesture from motion of user smartphone. The proposed method first obtain the 3D orientation of smartphone and recognize the gesture of hand motion by using HMM(Hidden Markov Model). The proposed method for the representation for 3D orientation of smartphone in spherical coordinate was used for quantization of smartphone orientation to be more sensitive in rotation axis. The experimental result shows that the success rate of our method is 93%.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.3
• /
• pp.308-314
• /
• 2017

Jet pump in automotive fuel tank module is used to deliver fuel to fuel pump so that the pump is operated without aeration in suction side. In this study, three dimensional simulation model of jet pump is developed to understand performance variation over design parameters. Performance of jet pump is also investigated experimentally in terms of operating pressures. The experimental data is used to verify the three dimensional simulation model of jet pump. Verification results show that the three dimensional simulation model of jet pump is about 1% error with experiment. The simulations are conducted in terms of throat ratio and primary flow induction angle. As the throat ratio is increased, the flux ratio is trade-off at 3 times of throat diameter. On the other hand, as primary flow induction angle is increased, vapor pressure inside the nozzle is decreased. In summary, the results show that liquid jet pump has to be optimized over design parameters. Additionally, high velocity of induced flow is able to evolve cavitation phenomena inside the jet pump.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.17 no.3
• /
• pp.283-289
• /
• 2011

As leisure boats become large-scaled and high value-added, their design requirements gradually get more complicated and accordingly their manufacturing processes get more complicated than those of existing ones. Leisure boat builders overseas make efforts to overcome this circumstance by establishing a 3-D model-based design system which is based on the concept of PLM. On the other hand, Korean shipbuilders still remain in the development process of traditional leisure boats which are mainly based on 2-D drawings. There have been some efforts made to have the 3-D model-based design system; however, they belong to a very early stage. This study carried out initial research to apply DMU technology to the development process of leisure boats. It established the design process based on a DMU model and proved its usefulness through a case study on the design of 40-ft class aluminum leisure boats.

• Journal of the Korea Convergence Society
• /
• v.9 no.1
• /
• pp.9-20
• /
• 2018

The purpose of this paper is to analyze the effect of corporation internal reservation on R&D investment. It is to find how much effect the reflux tax has achieved through empirical analysis. In addition, education training expense was taken as a moderating variable to find the effectiveness of government policy. Furthermore, the study looked through the effect once again by using GMB model. According to the result counted by regression analysis, it could be concluded that the effect of both moderation and intervention had a significant effect and the variable of interest cost and welfare & benefit cost in model 1, 2 and 3 had a meaningful impact at the level of 99%. On the other hand, the previous corporate internal reservation failed to show any significant result in all types of models. Even in GBM model of convergence level applied to additional analysis, similar results came out.

• Journal of Korea Technology Innovation Society
• /
• v.20 no.2
• /
• pp.458-486
• /
• 2017

This article suggests Living Lab approach as a technology commercialization model of public research and development (R&D) projects. Living Lab is a model for end-users, private companies, research institutes, and public organizations to develop technology in a living space which works as a laboratory. Unlike the dominant technology commercialization model which focuses on private enterprises, a new living lab model discusses end-user centered commercialization. Based on general living lab model, three types of technology commercialization model are suggested. The 'Demand exploring type living lab' and the 'Problem solving type living lab' are project-based living lab. The other type of living lab is 'Living lab platform'. The projectbased living lab can be utilized as modules when promoting R&D projects. On the other hand, the living lab platform is infrastructure to provide living labs services to companies, public institutes and municipalities.