• Journal of the Korean institute of surface engineering
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• v.44 no.1
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• pp.32-37
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• 2011

Numerical analysis is done to investigate the effect of surface treatment of a toilet on the cleanness. The surface treatment using plasma for the super-hydrophobic surface expects the self-cleaning effect of the toilet seat cover for preventing the droplets with a great quantity of bacteria during the toilet flushing after evacuation. In this study, the fluid analysis in the toilet during the flushing was performed by an ultrahigh-speed CCD camera with 1,000 frame/sec and the numerical modeling. And the spattering phenomenon from the toilet surface during urine was analyzed quantitatively by CFD-ACE+ with a free surface model and a mixed model of two fluids. If the surface tension of the toilet surface is weak, many urine droplets after collision bounded in spite of considering the gravity. The turbulence generated by the change of angle and velocity of urine and the variation of the collision phenomenon from toilet surface were modeled numerically.

• 한국HCI학회:학술대회논문집
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• 2008.02c
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• pp.224-224
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• 2008

Recent advances in model acquisition, computer-aided design, and simulation technologies have resulted in massive databases of complex geometric data occupying multiple gigabytes and even terabytes. In various graphics/geometric applications, the major performance bottleneck is typically in accessing these massive geometric data due to the high complexity of such massive geometric data sets. However, there has been a consistent lower growth rate of data access speed compared to that of computational processing speed. Moreover, recent multi-core architectures aggravate this phenomenon. Therefore, it is expected that the current architecture improvement does not offer the solution to the problem of dealing with ever growing massive geometric data, especially in the case of using commodity hardware. In this tutorial, I will focus on two orthogonal approaches--multi-resolution and cache-coherent layout techniques--to design scalable graphics/geometric algorithms. First, I will discuss multi-resolution techniques that reduce the amount of data necessary for performing geometric methods within an error bound. Second, I will explain cache-coherent layouts that improve the cache utilization of runtime geometric applications. I have applied these two techniques into rendering, collision detection, and iso-surface extractions and, thereby, have been able to achieve significant performance improvement. I will show live demonstrations of view-dependent rendering and collision detection between massive models consisting of tens of millions of triangles on a laptop during the talk.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.6 s.324
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• pp.33-39
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• 2004

Design of efficient Medium Access Control (MAC) protocols with both high throughput performances is a major focus in distributed contention based MAC protocol research. In this paper, we propose an efficient contention based MAC protocol for wireless Local Area Networks, namely, the Developed Collision Resolution (DCR) algorithm. This algorithm is developed based on the following innovative ideas: to speed up the collision resolution, we actively redistribute the backoff timers for all active nodes; to reduce the average number of idle slots, we use smaller contention window sizes for nodes with successful packet transmissions and reduce the backoff timers exponentially fast when a fixed number of consecutive idle slots are detected. We show that the proposed DCR algorithm provides high throughput performance and low latency in wireless LANs.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.1
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• pp.201-208
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• 2017

The major cause of the marine accidents is the collision with a moving object such as ship as well as the fixed object such as breakwater. Therefore, the most effective way to reduce the maritime ship accidents is the prevention of collision. In order to decrease the collision, it is principle that the navigation officer promptly judges the dangerous condition and makes the quick response. The ship does not allow any object or other ships approaching its surrounded area called ship area so that it prevents the collision. Generally, the ship which has high speed or poor maneuvering capability shall be managed from the distance so that the other ship does not invade its ship domains(watching distance, blocking distance). Accordingly, this study sets the navigational risk assessment model by applying ship dynamic domain and collision judgement method considered ship length, speed and navigational capability. It also reviewed the validity of the model and evaluated the perilous water way (Maenggol Channel) and a curved route near Maenggol Channel. As a result, in case of a ship with 100m in length passing Maenggol Channel, it represented "warning" level before 1.5nm to the entry, "dangerous"level 0.75nm before to it and "very dangerous" level 0.5nm before to it and then "dangerous"level again up to the entry. Applying to the curved route also showed the same results as the Narrow Channel or Maenggol Channel. This analysis highly matched with the actual navigation results. In the future, this model will be useful for coastal navigation safety chart development and safety evaluation for route or port development. It also allows to evaluate the dangerous route or the best route by applying the result into ECDIS so that it will finally help to reduce the marine accidents. Eventually the model will be effective for the marine traffic simulation evaluation forced by Maritime Traffic Safety Act.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1907-1908
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• 2006

Recently, an automatic crane control system is required with high speed and rapid transportation. Therefore, when container is transferred from the initial coordinate to the finial coordinate, the container paths should be built in terms of the least time and without sway. Therefore, we calculated the anti-collision path for avoiding collision in its movement to the finial coordinate in this paper. And we constructed the neural network predictive two degree of freedom PID controller to control the precise navigation. The proposed predictive control system is composed of the neural network predictor, two degree of freedom PID controller, neural network self-tuner which yields parameters of two degree of freedom PID. We analyzed crane system through simulation, and proved excellency of control performance over the conventional controllers.

• Journal of Mechanical Science and Technology
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• v.19 no.4
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• pp.976-984
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• 2005

This paper presents the analysis results of dynamics in the billiards game within the frame­work of rigid-body mechanics and a numerical simulation program. The friction exists between the ball and the table bed as well as between the ball and the rail. There are three parts in the dynamic behavior of the ball on the table bed; motion of the ball on the table bed, collision between balls, and collision between the ball and the cushion. During the development of the simulation program, the dynamics problems such as rolling motion and three-dimensional frictional impact motion have been analyzed in detail. The theoretical issues are implemented into a viable graphic simulation program and its efficacy is demonstrated through the experi­mental validation of the billiards game. The resulting analysis results are verified quantitatively and qualitatively using high-speed video camera. Through the experimental tests, it was found that the physical parameters such as coefficients of restitution and friction vary according to the motion variables and corresponding empirical formulations were developed. The simulation and experimental results agree well.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.95-102
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• 1999

Because a driver is located in the front end of KHST, he is most likely to be insured at collision accidents. So, it is very important to design some survival space for the driver. To evaluate the driver's safety of KHST (Korean High Speed Train), the front structure of power car is analysed using PAMCRASH under the SNCF accident scenario(collision against a movable rigid mass 15 ton at 110㎞/h). Because the driver's cab of KHST is a modified version of TGV-K, which is not so strong as to protect him, it turns out to be inadequate to guarantee his survival space. Therefore it is recommended to redesign the driver's cab in a crashworthy point of view like the case of TGV-Duplex or NEC.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.545-552
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• 1998

A study on collision analysis of TGV-K using a 2-dimensional model is described to evaluate its crashworthiness. Two-dimensional analysis gives good information on overriding behaviour and impact forces applied to interconnecting devices such as side buffers, ball & socket joints, hooks, pins, and fingers. Since the headstock of TGV-K is not designed in a crashworthy point of view, its conceptual design fur KHST(Korean High Speed Train), under development, is suggested to improve crashworthiness. The suggested design, which adopts an energy absorber and a crashworthy headstock, is compared with the conventional headstock on dynamic behaviour to the vertical direction under the accident scenario of SNCF (collision at 110km/h against a movable rigid mass of 15 ton). It is concluded that the design modification make little difference in vertical motion. To evaluate validation of the 2-dimensional model, the results fur longitudinal motion is compared with those of 1-dimemsional one. It is found that the two results are in good agreements.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.866-869
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• 2013

In this Paper, I propose a new anti-collision algorithm called Arbitrator-collision free reflected frame which restricts the size of frames and controlled the frame size when there are small tags. Since the proposal algorithm keeps the frame size and controlled the number of responding tags in such a way ones. can increase slot utilization, the algorithm shows superior performance to the existing algorithms. The simulation results showed that the proposed algorithm improves the efficiency by 0.8times compared to the existing algorithm.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.1
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• pp.6-12
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• 2004

Identification rate and time are very important in the identification of RFID tag, and the tag requires simple structure to use economically large quantity of tags. These factors make the MAC protocols of wired or wireless network environment result in different requirements. In the paper, we propose a method to apply spread spectrum scheme using orthogonal channel via Walsh function as the anti-collision communication system for the purpose of non-collision identification of multiple tags, and consider its property. The proposed system use two step identification. in the first step, collision is resolved via constructing to respond after specific delay time based on unique n, and conventional polling scheme follows in the second step.