• Journal of Internet Computing and Services
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• v.17 no.4
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• pp.35-42
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• 2016

Recently many researches have been focused on the use of the markerless augmented reality system using face, foot, and hand of user's body to alleviate many disadvantages of the marker based augmented reality system. In addition, most existing augmented reality systems have been utilized rigid objects since they just desire to insert and to basic interaction with virtual object in the augmented reality system. In this paper, unlike restricted marker based augmented reality system with rigid objects that is based in display, we designed and implemented the markerless augmented reality system using deformable objects to apply various fields for interactive situations with a user. Generally, deformable objects can be implemented with mass-spring modeling and the finite element modeling. Mass-spring model can provide a real time simulation and finite element model can achieve more accurate simulation result in physical and mathematical view. In this paper, the proposed markerless augmented reality system utilize the mass-spring model using tetraheadron structure to provide real-time simulation result. To provide plausible simulated interaction result with deformable objects, the proposed method detects and tracks users hand with Kinect SDK and calculates the external force which is applied to the object on hand based on the position change of hand. Based on these force, 4th order Runge-Kutta Integration is applied to compute the next position of the deformable object. In addition, to prevent the generation of excessive external force by hand movement that can provide the natural behavior of deformable object, we set up the threshold value and applied this value when the hand movement is over this threshold. Each experimental test has been repeated 5 times and we analyzed the experimental result based on the computational cost of simulation. We believe that the proposed markerless augmented reality system with deformable objects can overcome the weakness of traditional marker based augmented reality system with rigid object that are not suitable to apply to other various fields including healthcare and education area.

• Wind and Structures
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• v.16 no.1
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• pp.93-115
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• 2013

This paper describes a study of the influence of a dynamically flexible building structure on pressures inside and net pressures on the roof of low-rise buildings with a dominant opening. It is shown that dynamic interaction between the flexible roof and the internal pressure results in a coupled system that is similar to a two-degree-of-freedom mechanical system consisting of two mass-spring-damper systems with excitation forces acting on both the masses. Two resonant modes are present, the natural frequencies of which can readily be obtained from the model. As observed with quasi-static building flexibility, the effect of increased dynamic flexibility is to reduce the first natural frequency as well as the corresponding peak value of the admittance, the latter being the result of increased damping effects. Consequently, it is found that the internal and net roof pressure fluctuations (RMS coefficients) are also reduced with dynamic flexibility. This model has been validated from experiments conducted using a cylindrical model with a leeward end flexible diaphragm, whereby good match between predicted and measured natural frequencies, and trends in peak admittances and RMS responses with flexibility, were obtained. Furthermore, since significant differences exist between internal and net roof pressure responses obtained from the dynamic flexibility model and those obtained from the quasi-static flexibility model, it is concluded that the quasi-static flexibility assumption may not be applicable to dynamically flexible buildings. Additionally, since sensitivity analyses reveal that the responses are sensitive to both the opening loss coefficient and the roof damping ratio, careful estimates should therefore be made to these parameters first, if predictions from such models are to have significance to real buildings.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.8
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• pp.1187-1193
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• 2013

In this paper, we present realistic 3D head modeling and facial expression systems. For 3D head modeling, we perform generic model fitting to make individual head shape and texture mapping. To calculate the deformation function in the generic model fitting, we determine correspondence between individual heads and the generic model. Then, we reconstruct the feature points to 3D with simultaneously captured images from calibrated stereo camera. For texture mapping, we project the fitted generic model to image and map the texture in the predefined triangle mesh to generic model. To prevent extracting the wrong texture, we propose a simple method using a modified interpolation function. For generating 3D facial expression, we use the vector muscle based algorithm. For more realistic facial expression, we add the deformation of the skin according to the jaw rotation to basic vector muscle model and apply mass spring model. Finally, several 3D facial expression results are shown at the end of the paper.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.4
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• pp.5-11
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• 2007

The future combat system is likely to be studied and developed in terms of enhancing both firepower and mobility simultaneously. Increased firepower often necessitates a heavier firing system. In return, the body of the vehicle needs to be light-weight in order to improve the mobility of the whole system. For this reason, in the areas of weapons systems such as the tank and self-propelled artillery, a number of studies attempting to develop designs that reduce recoil force against the body of the vehicle are being conducted. The current study proposes a tank construction that has a mass-spring-damper system with two degrees of freedom. A tank structure mounted with a specific soft recoil system that was implemented using a soft recoil technique and another tank structure based on a general recoil technique were compared to each other in order to analyze the recoil forces, the displacements of recoil, and the firing intervals when they were firing. MATLAB-Simulink was used as a simulating tool. In addition, the relationship between the movement of the recoil parts and the positions of the recoil latches in each of the two structures were analyzed. The recoil impact power, recoil displacement, firing interval, and so on were derived as functional formulas based on the position of the recoil latch.

• Journal of The Korean Astronomical Society
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• v.49 no.1
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• pp.37-44
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• 2016

The Korea Microlensing Telescope Network (KMTNet) is a wide-field photometric system installed by the Korea Astronomy and Space Science Institute (KASI). Here, we present the overall technical specifications of the KMTNet observation system, test observation results, data transfer and image processing procedure, and finally, the KMTNet science programs. The system consists of three 1.6 m wide-field optical telescopes equipped with mosaic CCD cameras of 18k by 18k pixels. Each telescope provides a 2.0 by 2.0 square degree field of view. We have finished installing all three telescopes and cameras sequentially at the Cerro-Tololo Inter-American Observatory (CTIO) in Chile, the South African Astronomical Observatory (SAAO) in South Africa, and the Siding Spring Observatory (SSO) in Australia. This network of telescopes, which is spread over three different continents at a similar latitude of about -30 degrees, enables 24-hour continuous monitoring of targets observable in the Southern Hemisphere. The test observations showed good image quality that meets the seeing requirement of less than 1.0 arcsec in I-band. All of the observation data are transferred to the KMTNet data center at KASI via the international network communication and are processed with the KMTNet data pipeline. The primary scientific goal of the KMTNet is to discover numerous extrasolar planets toward the Galactic bulge by using the gravitational microlensing technique, especially earth-mass planets in the habitable zone. During the non-bulge season, the system is used for wide-field photometric survey science on supernovae, asteroids, and external galaxies.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.2
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• pp.83-93
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• 2020

In fisheries, the importance of designing efficient fish cages is being emphasized as aquaculture has become more production than capture fishing. Particularly, the gravity cage system is one of the popular fish cage system in Korea. Currently, gravity cages of various shapes and sizes are being widely designed and installed in offshore and inland seas. The cage is subject to external forces, such as currents and waves, and the shape of the structure and tension on the ropes changes according to these external forces. Thus, it is important to accurately calculate these dynamic behavior, including the external forces and tension on the structure during the design stage. In this study, three types of cage systems with an equal internal volume of 8000 ㎥ were analyzed using mass-spring models and their behavior was interpreted through simulations. These simulations were used to analyze the behavior and tension of the ropes in response to currents and waves to aid in the selection of individual cage sizes for a given total volume. The numerical calculation results indicate that depending on the flow rate, the most resistant system is System 1, which has eight strays, and System 2 and System 3 have 69.4% and 54.8% of the resistance of System 1. Further, total resistance increased as the number of cages increased for all flow rates.

• Journal of Information Processing Systems
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• v.8 no.1
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• pp.55-66
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• 2012

This paper presents a dual modeling method that simulates the graphic and haptic behavior of a volumetric deformable object and conveys the behavior to a human operator. Although conventional modeling methods (a mass-spring model and a finite element method) are suitable for the real-time computation of an object's deformation, it is not easy to compute the haptic behavior of a volumetric deformable object with the conventional modeling method in real-time (within a 1kHz) due to a computational burden. Previously, we proposed a fast volume haptic rendering method based on the S-chain model that can compute the deformation of a volumetric non-rigid object and its haptic feedback in real-time. When the S-chain model represents the object, the haptic feeling is realistic, whereas the graphical results of the deformed shape look linear. In order to improve the graphic and haptic behavior at the same time, we propose a dual modeling framework in which a volumetric haptic model and a surface graphical model coexist. In order to inspect the graphic and haptic behavior of objects represented by the proposed dual model, experiments are conducted with volumetric objects consisting of about 20,000 nodes at a haptic update rate of 1000Hz and a graphic update rate of 30Hz. We also conduct human factor studies to show that the haptic and graphic behavior from our model is realistic. Our experiments verify that our model provides a realistic haptic and graphic feeling to users in real-time.

• Smart Structures and Systems
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• v.15 no.3
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• pp.627-643
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• 2015

Negative stiffness, previously emulated by active or semi-active control for cable vibration mitigation, is realized passively using a self-contained highly compressed spring, the negative stiffness device (NSD).The NSD installed in parallel with a viscous damper (VD) in the vicinity of cable anchorage, enables increment of damper deformation during cable vibrations and hence increases the attainable cable damping. Considering the small cable displacement at the damper location, even with the weakening device, the force provided by the NSD-VD assembly is approximately linear. Complex frequency analysis has thus been conducted to evaluate the damping effect of the assembly on the cable; the displacement-dependent negative stiffness is further accounted by numerical analysis, validating the accuracy of the linear approximation for practical ranges of cable and NSD configurations. The NSD is confirmed to be a practical and cost-effective solution to improve the modal damping of a cable provided by an external damper, especially for super-long cables where the damper location is particularly limited. Moreover, mathematically, a linear negative stiffness and viscous damping assembly has proven capability to represent active or semi-active control for simplified cable vibration analysis as reported in the literature, while in these studies only the assembly located near cable anchorage has been addressed. It is of considerable interest to understand the general characteristics of a cable with the assembly relieving the location restriction, since it is quite practical to have an active controller installed at arbitrary location along the cable span such as by hanging an active tuned mass damper. In this paper the cable frequency variations and damping evolutions with respect to the arbitrary assembly location are then evaluated and compared to those of a taut cable with a viscous damper at arbitrary location, and novel frequency shifts are observed. The characterized complex frequencies presented in this paper can be used for preliminary damping effect evaluation of an adaptive passive or semi-active or active device for cable vibration control.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1510-1510
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• 2001

NIRS uses reflectance signals resulting from bending and stretching vibrations in chemical bonds between carbon, nitrogen, hydrogen, sulfur and oxygen. These reflectance signals are used to measure the concentration of major chemical composition and other descriptors of homogenized and freeze-dried whole broiler carcasses. Six strains of chicken were analyzed and the NIRS model predictions compared to reference data. The results of this comparison indicate that NIRS is a rapid tool for predicting dry matter (DM), fat, crude protein (CP) and ash content in the broiler carcass. Males and females of six commercial strain crosses of broiler chicken (Gallus domesticus) were used in this study (6$\times$2 factorial design). Each strain was grown to 16 weeks of age, and duplicate serial samples were taken for body composition analysis. Each whole carcass was pressure-cooked, homogenized, and a representative sample was freeze-dried. Body composition determined as follows: DM by oven dried method at 105$^{\circ}C$ for 3 hours, fat by Mojonnier diethyl ether extraction, CP by measuring nitrogen content using an auto-analyzer with Kjeldhal digest and ash by combustion in a muffle furnace for 24 hour at 55$0^{\circ}C$. These homogenized and freeze-dried carcass samples were then scanned with a Foss NIR Systems 6500 visible-NIR spectrophotometer (400-2500nm) (Foss NIR Systems, Silver Spring, MD., US) using Infra-Soft-International, ISI, WinISl software (ISI, Port Matilda, US). The NIRS spectra were analyzed using principal component (PC) analysis. This data was corrected for scatter using standard normal “Variate” and “Detrend” technique. The accuracy of the NIRS calibration equations developed using Partial Least Squares (PLS) for predicting major chemical composition and carcass descriptors- such as body mass (BM), bird dry matter and moisture content was tested using cross validation. Discrimination analysis was also used for sex and strain identification. According to Dr John Shenk, the creator of the ISI software, the calibration equations with the correlation coefficient, $R^2$, between reference data and NIRS predicted results of above 0.90 is excellent and between 0.70 to 0.89 is a good quantifying guideline. The excellent calibration equations for DM ($R^2$= 0.99), fat (0.98) and CP (0.92) and a good quantifying guideline equation for ash (0.80) were developed in this study. The results of cross validation statistics for carcass descriptors, body composition using reference methods, inter-correlation between carcass descriptors and NIRS calibration, and the results of discrimination analysis for sex and strain identification will also be presented in the poster. The NIRS predicted daily gain and calculated daily gain from this experiment, and true daily gain (using data from another experiment with closely related broiler chicken from each of the six strains) will also be discussed in the paper.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.161-171
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• 2003

The present study evaluated water quality variation, limiting nutrient, and sediment of a shallow eutrophic lake (Lake Ilgam) in the metropolitan area from 2000 to 2002. According to annual mean chl.a ($77.2{\pm}36.6\;{\mu}g/l) and TP ($66.6{\pm}20.5\;{\mu}g/l) concentration and trophic state index (>60), Lake llgam was in very eutrophic status. Both inorganic nitrogen ($NH_3-N$ and $NH_3-N$) and phosphorus (SRP) concentrations in the water column increased during winter and spring, but decreased during summer followed by the phytoplankton development. Evidence for phosphorus and nitrogen as being the potential limiting nutrients for phytoplankton growth was supported by the ratio of DIN/DIP (by mass) (${\sim}$835.8), TSI derivations analysis, and algal growth potential bioassay. Based on the results of TSI derivations, strong nutrient limitation by both N and P occurred from September to November when P content in sediment (114.6 mg P/kg) was relatively low compared with the summer. Sediment contained a large amount of nitrogen (TKN: 4,452${\pm}$283.0mg N/kg dry sediment). Phosphorus content in sediment (TP: 313${\pm}$155 mg P/kg) was relatively low with temporal change. P release rate (0.29${\pm}$0.02 mg $m^{-2}$ $day^{-1}$) was high under the aerobic condition at pH 9. These results indicate that the sediment could play an important role as a source of a limiting nutrient, and temporal change of P content in the sediment is closely related with water quality, especially algal biomass change in Lake llgam.