• Journal of Broadcast Engineering
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• v.25 no.2
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• pp.185-191
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• 2020

MPEG-I is actively working on standardization on the immersive video coding which provides up to 6 degree of freedom (6DoF) in terms of viewpoint. In a virtual space of 3DoF+, which is defined as an extension of 360 with motion parallax, looking at the scene from another viewpoint (another position in space) requires rendering an additional viewpoint using multiple videos included in the 3DoF+ video. In the MPEG-I Visual workgroup, efficient coding methods for 3DoF+ video are being studied, and they released Test Model for Immersive Video (TMIV) recently. This paper presents a patch packing method which packs the patches into atlases efficiently for improving coding efficiency of 3DoF+ video in TMIV. The proposed method improves the reconstructed view quality with reduced coding artifacts by introducing guardbands between patches in the atlas.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.305-316
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• 2014

As avionics and mechanical devices have been developed, the size of unmanned aerial vehicle (UAV) is getting smaller. However, the complicated and accurate missions are provided to the UAV. Among various types of UAVs, quadrotors are widely used for their availability by virtue of simple structure and hovering function. However, the control of quadrotor is highly constrained, because the quadrotor is an under-actuated system which has only 4 actuator inputs. To deal with this under-actuated problem, a new quadrotor model with two more actuators in addition to the 4 propeller inputs is provided to make the system fully-actuated. For the proposed model, a controller is designed using feedback linearization methods. To validate the model and to verify the performance of the proposed controller, numerical simulation is performed.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.315-328
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• 2016

Techniques for determinating hydrodynamic derivatives of underwater tow-fish using CFD(Computational Fluid Dynamics) are described in this paper. Main components of hydrodynamic derivatives are added mass, linear damping and non-linear damping coefficients. In this study, linear and non-linear damping coefficients for translational velocities are settled by CFD analysis. In order to analyze the underwater tow-fish, UlsanFOAM based on open-source CFD code, namely OpenFOAM, is employed. By simulating pitch and yaw angle variation of underwater tow-fish, 6DOF(Degree-of-Freedom) forces and moments are estimated at each attitudes. In order to determinate the hydrodynamic derivatives, curves(forces and moments vs attitude) for CFD results are fitted by least square methods. To demonstrate the applicability of the current approach, two different problems(impulsive side towing and straight towing) are simulated and all results are validated.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.2
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• pp.172-181
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• 2012

One of the most critical issues in naval architecture these days is the operational safety. Among many factors to be considered for higher safety level requirements, the hull stability in intact and damaged conditions is the first to ensure for both commercial and military vessels. Unlike the intact stability cases, the assessment of the damaged ship stability is very complicated physical phenomena. Therefore it is widely acknowledged that computational fluid dynamics (CFD) methods are one of most feasible approaches. In order to develop better CFD methods for damaged ship stability assessment, it is essential to perform well-designed model tests and to build a database for CFD validation. In the present study, free roll decay tests in calm water with both intact and damaged ships were performed and six degree-of-freedom (6DOF) motion responses of intact ship in regular waves were measured. Through the free roll decay tests, the effects of the flooding water on the roll decay motion of a ship were investigated. Through the model tests in regular waves, the database that provides 6DOF motion responses of intact ship was established.

• Journal of the Korean Chemical Society
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• v.20 no.5
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• pp.351-357
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• 1976

Adsorption isotherms of benzene and p-xylene on both of Spheron 6 (a graphitized carbon black) and Alucer (Alumina) are obtained at various temperatures using a sensitive quartz beam microbalance. From these isotherms BET plots are made to obtain the molecular areas of these adsorbates. On the Spheron 6, the molecular area of p-xylene remains constant until the temperature is increased up to $19^{circ}C$, increases abruptly at $19^{circ}C$ through $19.2^{circ}C$, and then again remains constant thereafter. On the other hand, adsorbed benzene molecules give a quite temperature-independent molecular area. The results are interpreted as the adsorbed p-xylene molecules and benzene molecules are localized on the adsorbents with compact packing, while it gains a hindered-rotational degree of freedom at the expense of vibrational one at the higher temperatures. This peculiar behavior of adsorption is considered as due to the interactions between benzene rings of adsorbents and graphite surface. Molecular areas of these adsorbates on Alucer M. A. increase gradually with temperature, indicating that the adsorbed molecules are unlocalized.

• Nutrition Research and Practice
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• v.16 no.6
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• pp.765-774
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• 2022

BACKGROUND/OBJECTİVES: It is important to determine Dysfunctional eating behaviors such as dietary restraint and overeating tendencies in order to provide weight management and acquire the right habits in children. The purpose of this study was to test the reliability and validity of Dutch Eating Behaviour Questionnaire Children (DEBQ-C) with Turkish preadolescent children. MATERIALS/METHODS: This research included 440 preadolescents (9.3 ± 6.9 years and 235 girls, 205 boys). The instrument is divided into three subscales, each with 20 items. Emotional eating, restrained eating, and external eating are the three subscales. Confirmatory factor analysis (CFA) was used to assess the construct validity of the Turkish version of the DEBQ-C, and Cronbach α values were computed to evaluate the subscale reliabilities. There were 20 observable variables and three latent variables in the hypothesized model. RESULTS: Fit indices for the hypothesized model were good (×2/degree of freedom = 1.96; root mean square error of approximation = 0.05; comparative fit index = 0.95; goodness of fit index = 0.93). These findings revealed that the Turkish version of the DEBQ-C has a factor structure that was identical to the three-factor structure of the original scale. The Turkish version of the DEBQ-C subscales has internal consistency coefficients ranging from 0.72 (external eating) to 0.86. (emotional eating). CONCLUSIONS: The DEBQ-C Turkish version is a viable and reliable tool for measuring overeating tendencies in Turkish preadolescents, according to the findings.

• Journal of computational fluids engineering
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• v.19 no.2
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• pp.86-92
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• 2014

In this paper, prediction of separation trajectory for Two-stage-To-Orbit space launch vehicle has been numerically simulated by using an aerodynamic database based on steady state analysis. Aerodynamic database were obtained for matrix of longitudinal and vertical positions. The steady flow simulations around the launch vehicle have been made by using a 3-D RANS flow solver based on unstructured meshes. For this purpose, a vertex-centered finite-volume method was adopted to discretize inviscid and viscous fluxes. Roe's finite difference splitting was utilized to discretize the inviscid fluxes, and the viscous fluxes were computed based on central differencing. To validate this flow solver, calculations were made for the wind-tunnel experiment model of the LGBB TSTO vehicle configuration on steady state conditions. Aerodynamic database was constructed by using flow simulations based on test matrix from the wind-tunnel experiment. ANN(Artificial Neural Network) was applied to construct interpolation function among aerodynamic variables. Separation trajectory for TSTO launch vehicle was predicted from 6-DOF equation of motion based on the interpolated function. The result of present separation trajectory calculation was compared with the trajectory using experimental database. The predicted results for the separation trajectory shows fair agreement with reference[4] solution.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.2
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• pp.83-90
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• 2010

The hydrodynamic interaction of two floating bodies in waves freely floating or connected by a rigid link is studied by using a boundary element method in the frequency-domain. The exact two-body hydrodynamic coefficients of added mass, wave damping and exciting force are calculated from the radiation-diffraction potential solution of the improved Green integral equation associated with the free surface Green function. The irregular frequencies in the conventional Green integral equation make it difficult to predict the physical resonance of the fluid in the gap between two bodies floating side by side. However, the improved Green integral equation employed in this study is free of irregular frequencies and always yields the exact solution of the multi-body radiation-diffraction potential boundary value problem. The 6 degree-of-freedom motions of two bodies freely floating side by side or connected parallel by a rigid link have been calculated for the incident wave frequencies ranging from 0.1 to 5 radians per second in head, left and right bow quartering seas. The 6-component load of the rigid link have also been presented.

• Ocean Systems Engineering
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• v.6 no.3
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• pp.265-287
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• 2016

The change of the global performance of a turret-moored FPSO (Floating Production Storage Offloading) with DP (Dynamic Positioning) control is simulated, analyzed, and compared for two different internal turret location cases; bow and midship. Both collinear and non-collinear 100-yr GOM (Gulf of Mexico) storm environments and three cases (mooring-only, with DP position control, with DP position+heading control) are considered. The horizontal trajectory, 6DOF (degree of freedom) motions, fairlead mooring and riser tension, and fuel consumptions are compared. The PID (Proportional-Integral-Derivative) controller based on LQR (linear quadratic regulator) theory and the thrust-allocation algorithm which is based on the penalty optimization theory are implemented in the fully-coupled time-domain hull-mooring-riser-DP simulation program. Both in collinear and non-collinear 100-yr WWC (wind-wave-current) environments, the advantage of mid-ship turret is demonstrated by the significant reduction in heave at the turret location due to the minimal coupling with pitch mode, which is beneficial to mooring and riser design. However, in the non-collinear WWC environment, the mid-turret case exhibits unfavorable weathervaning characteristics, which can be reduced by employing DP position and heading controls as demonstrated in the present case studies. The present study also reveals the plausible cause of the failure of mid-turret Gryphon Alpha FPSO in milder environment than its survival condition.

• Journal of Broadcast Engineering
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• v.25 no.5
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• pp.672-684
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• 2020

Restoring a low resolution and motion blurred light field has become essential due to the growing works on parallax-based image processing. These tasks are known as light-field enhancement process. Unfortunately, only a few state-of-the-art methods are introduced to solve the multiple problems jointly. In this work, we design a framework that jointly solves light field spatial super-resolution and motion deblurring tasks. Particularly, we generate a straight-forward neural network that is trained under low-resolution and 6-degree-of-freedom (6-DOF) motion-blurred light field dataset. Furthermore, we propose the strategy of local region optimization on the adversarial network to boost the performance. We evaluate our method through both quantitative and qualitative measurements and exhibit superior performance compared to the state-of-the-art methods.