• 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.

• Journal of Korea Game Society
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• v.4 no.4
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• pp.11-18
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• 2004

The on-line games in the past were played by only two persons exchanging data based on one-to-one connections, whereas recent ones (e.g. MMORPG: Massively Multi-player Online Role-playings Game) enable tens of thousands of people to be connected simultaneously. Specifically, Korea has established an excellent network infrastructure that can't be found anywhere in the world. Almost every household has a high-speed Internet access. What made this possible was, in part, high density of population that has accelerated the formation of good Internet infrastructure. However, this rapid increase in the use of on-line games may lead to surging traffics exceeding the limited Internet communication capacity so that the connection to the games is unstable or the server fails. expanding the servers though this measure is very costly could solve this problem. To deal with this problem, the present study proposes the load distribution technology that connects in the form of local clustering the game servers divided by their contents used in each on-line game reduces the loads of specific servers using the load balancer, and enhances performance of sewer for their efficient operation. In this paper, a cluster system is proposed where each Game server in the system has different contents service and loads are distributed efficiently using the game server resource information such as CPU utilization. Game sewers having different contents are mutually connected and managed with a network file system to maintain information consistency required to support resource information updates, deletions, and additions. Simulation studies show that our method performs better than other traditional methods. In terms of response time, our method shows shorter latency than RR (Round Robin) and LC (Least Connection) by about 12%, 10% respectively.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.5_6
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• pp.202-213
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• 2007

A network is an important model widely used in natural and social science as well as engineering. To analyze these networks easily it is necessary that we should layout the features of networks visually. These Graph-Layout researches have been performed recently according to the development of the computer technology. Among them, the Scale-free Network that stands out in these days is widely used in analyzing and understanding the complicated situations in various fields. The Scale-free Network is featured in two points. The first, the number of link(Degree) shows the Power-function distribution. The second, the network has the hub that has multiple links. Consequently, it is important for us to represent the hub visually in Scale-free Network but the existing Graph-layout algorithms only represent clusters for the present. Therefor in this thesis we suggest Graph-layout algorithm that effectively presents the Scale-free network. The Hubity(hub+ity) repulsive force between hubs in suggested algorithm in this thesis is in inverse proportion to the distance, and if the degree of hubs increases in a times the Hubity repulsive force between hubs is ${\alpha}^{\gamma}$ times (${\gamma}$??is a connection line index). Also, if the algorithm has the counter that controls the force in proportion to the total node number and the total link number, The Hubity repulsive force is independent of the scale of a network. The proposed algorithm is compared with Graph-layout algorithm through an experiment. The experimental process is as follows: First of all, make out the hub that exists in the network or not. Check out the connection line index to recognize the existence of hub, and then if the value of connection line index is between 2 and 3, then conclude the Scale-free network that has a hub. And then use the suggested algorithm. In result, We validated that the proposed Graph-layout algorithm showed the Scale-free network more effectively than the existing cluster-centered algorithms[Noack, etc.].

• Progress in Medical Physics
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• v.19 no.4
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• pp.231-240
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• 2008

We developed a user-friendly program to independently verify monitor units (MUs) calculated by radiation treatment planning systems (RTPS), as well as to manage beam database in clinic. The off-axis factor, beam hardening effect, inhomogeneity correction, and the different depth correction were incorporated into the program algorithm to improve the accuracy in calculated MUs. A beam database in the program was supposed to use measured data from routine quality assurance (QA) processes for timely update. To enhance user's convenience, a graphic user interface (GUI) was developed by using Visual Basic for Application. In order to evaluate the accuracy of the program for various treatment conditions, the MU comparisons were made for 213 cases of phantom and for 108 cases of 17 patients treated by 3D conformal radiation therapy. The MUs calculated by the program and calculated by the RTPS showed a fair agreement within ${\pm}3%$ for the phantom and ${\pm}5%$ for the patient, except for the cases of extreme inhomogeneity. By using Visual Basic for Application and Microsoft Excel worksheet interface, the program can automatically generate beam data book for clinical reference and the comparison template for the beam data management. The program developed in this study can be used to verify the accuracy of RTPS for various treatment conditions and thus can be used as a tool of routine RTPS QA, as well as independent MU checks. In addition, its beam database management interface can update beam data periodically and thus can be used to monitor multiple beam databases efficiently.

• Journal of Science Education
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• v.44 no.1
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• pp.92-111
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• 2020

The 2015 revised science curriculum and NGSS (Next Generation Science Standard) suggest computational thinking as an inquiry skill or competency. Particularly, concern in computational thinking has increased since the Ministry of Education has required software education since 2014. However, there is still insufficient discussion on how to integrate computational thinking in science education. Therefore, this study aims to prepare a way to integrate computational thinking elements into scientific inquiry by analyzing the related literature. In order to achieve this goal, we summarized various definitions of the elements of computational thinking and analyzed general problem solving process and scientific inquiry process to develop and suggest the model. We also considered integrated problem solving cases from the computer science field and summarized the elements of the Computational Thinking-Scientific Inquiry (CT-SI) model. We asked scientists to explain their research process based on the elements. Based on these explanations from the scientists, we developed 'Problem-finding' CT-SI model and 'Problem solving' CT-SI model. These two models were reviewed by scientists. 'Problem-finding' model is relevant for selecting information and analyzing problems in the theoretical research. 'Problem solving' is suitable for engineering problem solving process using a general research process and engineering design. In addition, two teachers evaluated whether these models could be used in the secondary school curriculum. The models we developed in this study linked with the scientific inquiry and this will help enhance the practices of 'collecting, analyzing and interpreting data,' 'use of mathematical thinking and computer' suggested in the 2015 revised curriculum.

• Journal of the Korea Society of Computer and Information
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• v.25 no.7
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• pp.103-111
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• 2020

Performance indicators have often investigated and developed in order to identify foundational elements and factors for an enhancement of performance in sports. In order to identify the valid performance indicators it is important that the indicators used within a performance analysis system discriminate between the winning and losing performances within a match (Hughes and Bartlett, 2002). However, the performance indicators proposed in research studies on basketball performance have not been used for real-time analysis and feedback within a coaching context. Such real-time support for the coach and players has been described within research on other sports (Choi et al., 2004; O'Donoghue, 2001; Palmer et al., 1997). Within the process of real-time feedback, the identification of relevant performance indicators that distinguish winning and losing performances should be the first stage of the development of a real-time analysis system. Therefore, this study investigated the differences between winning and losing teams in terms of a set of performance indicators gathered during the analysis of 10 English National Basketball League matches. Winning and losing teams were compared using whole match data (N=10) as well as individual quarters (N=40). A series of Wilcoxon Signed Ranks tests was used to identify the relevant performance indicators that discriminate between winning and losing performers within whole matches and individual quarters. The tests found that 3 point shots made (p<0.05) and Assists (p<0.05) were significantly different between winning and losing teams within matches. However, 2 point shots made (p<0.05), 2 point shots attempted (P<0.05), percentages of 2 point shots scored (p<0.05), 3 point shots made (p<0.05), Defensive Rebounds (p<0.05) and Assists (p<0.05) were significantly different between winning and losing performance within quarters. The analysis task should be based on relevant performance indicators which explain the current performances to performance analysts and coaches. Within a real-time analysis and feedback scenario, this will have the additional benefit of supporting a decision based on immediate performance within the most recent quarter. Consequently, the real-time analysis system would use performance indicators which have the property of construct validity to support the decisions of the coach.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.249-256
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• 2011

Finding a new set of features representing textured images is one of the most important studies in textured image analysis. This is because it is impossible to construct a perfect set of features representing every textured image, and it is inevitable to choose some relevant features which are efficient to on-going image processing jobs. This paper intends to find relevant features which are efficient to textured image segmentation. In this regards, this paper presents a different method for the segmentation of textured images based on the Gabor filter. Gabor filter is known to be a very efficient and effective tool which represents human visual system for texture analysis. Filtering a real-valued input image by the Gabor filter results in complex-valued output data defined in the spatial frequency domain. This complex value, as usual, gives the module and the phase. This paper focused its attention on the phase information, rather than the module information. In fact, the module information is considered very useful at region analysis in texture, while the phase information was considered almost of no use. But this paper shows that the phase information can also be fully useful and effective at region analysis in texture, once a good method introduced. We now propose "phase derivated method", which is an efficient and effective way to compute the useful phase information directly from the filtered value. This new method reduces effectively computing burden and widen applicable textured images.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.5
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• pp.644-652
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• 2007

In this study, we examined family history of chronic diseases, food group intake and physical activity in $5^{th}\;and\; 6^{th}$ grade elementary school children. Food group intake was compared with the KDRI food guides for children. The measurements of daily physical activity, television viewing, computer use, and daily servings of five food groups, including grains, meats, dairy products, fruits, and vegetables, were based on child and parent self-reports. As indices of obesity, the obesity index(%) and BMI(Body Mass Index) were used. The results were as follows. In boys, 83.2% were normal weight with 7.4% slightly obese, 7.4% moderately obese, and 2.0 were highly obese while the percentages of normal and slightly obese in girls were 89.9% and 6.2% respectively (p<0.05). The boys had more hours of daily physical activity(p<0.05) and more hours of computer usage(Internet searching or games)(p<0.05) than the girls. Slightly over 50% of the subjects met the daily recommended servings of grains, dairy products, fruits, and vegetables according to the KDRI food guides. However, only 26% of boys and 27% of girls met the recommended daily servings of protein foods such as meats, beans, and eggs. Thirty two percent(32%) of girls consumed high fat snacks everyday while 32% consumed high sugar snacks every day. The girls consumed more vegetables(p<0.05) and more high sugar snacks(p<0.05) than the boys. The children with family histories of obesity showed greater obesity rates(p<0.05) and sedentary lifestyles(p< 0.05) than those children without a family history of obesity. Children with family histories of high blood pressure consumed more sewings of vegetables and high fat snacks than the controls(p<0.05). The children with family histories of obesity consumed more high sugar or high fat snacks than the controls(p<0.05).

• Journal of the Korean Arthroscopy Society
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• v.16 no.2
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• pp.160-166
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• 2012

Purpose: The aim of this study was to determine the patterns of the stress distribution within the reconstructed anterior cruciate ligament (ACL) double bundles in response to an anterior tibial load and rotatory load at $45^{\circ}$ flexed knee model by use of a 3-dimensional finite element analysis (FEM). Materials and Methods: The $0^{\circ}$ and $45^{\circ}$ flexed 3-D knee model were reconstructed based on the high resolution computed tomography (CT) images from the right knee of a healthy male subject. To simulate double bundle ACL reconstruction, in $0^{\circ}$ analytic model, four 7 mm diameter tunnels were created at the center of each anteromedial (AM) and posterolateral (PL) footprints on the femur and tibia. The grafts were inserted into the corresponding bone tunnels and then reconstructed knee model was flexed to $45^{\circ}$. As a next step, the 5 mm anterior tibial load and internal rotational load of $10^{\circ}$ were applied on the final Computer aided design (CAD) model. And then stress patterns of each bundle were assessed using a finite element analysis. Results: In response to the 5 mm of anterior tibial load, the AM bundle showed increased stresses around the tibial and femoral attachment sites; especially in the anterior aspect of the bundle. In the PL bundle, the highest stress concentration was also noticed on the anterior aspect of the bundle. Under $10^{\circ}$ internal rotational load, the stress concentration was predominant around the anterior aspect of the tibial attachment site within the AM bundle. The PL bundle also showed highest stress concentration on the anterior aspect of the bundle. Conclusion: Although the stress patterns were not identical among the AM and PL bundle, there were common trends in the stress distribution. The stress concentration was predominant on the anterior aspect of both bundles in response to the anterior tibial load and rotatory load.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.199-205
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• 2020

Cryopreservation of semen is useful for animal breeding via artificial insemination (AI). However, the use of frozen-thawed boar semen is limited due to cryodamage. The aim of this study was to investigate the effects of different concentrations of MitoTEMPO (a mitochondria-targeted antioxidant) in lactose-egg yolk (LEY) extenders on kinetic characteristics of frozen-thawed boar sperms. Semen samples were collected from mature Duroc boars (2~3 years old) and cryopreserved in LEY extenders containing 0, 0.5, 5, 50, and 500 μM MitoTEMPO. The kinetic characteristics of frozen-thawed sperms were determined 0 and 30 min after thawing using computer-assisted sperm analysis (CASA). Results indicated that sperm motility immediately after thawing was significantly higher with 5 and 50 μM (50.46±2.71% and 46.96±2.66%, respectively) than with 500 μM MitoTEMPO (35.40±2.95%) (P<0.05). However, there were no significant differences in other kinetic characteristics except motility. In conclusion, the addition of MitoTEMPO to the sperm freezing extender may have a beneficial effect on motility of post-thawed boar semen.