• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1732-1739
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• 2004

In this paper, we proposed a visualization system with ANN algorithm that traits the motion of particles that move colliding in the water, where we got a great deal of variable information and predicts the distribution of particles according to the flowing of water and the pattern of their precipitation. We adopted ART2 to detect sensitively the collision between particles in this visualzation. Various particles and their mutual collision influencing the force such as buoyancy force, gravitational force, and the pattern of precipitation are considered in this system. Flowing particles whose motion is changed with the environment can be visualized in the system presented here as they are in real water.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.11
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• pp.1108-1115
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• 2004

A new type of a Rotman lens is presented in this paper fur millimeter-wave applications, such as collision avoidance radar. A dielectric slab Rotman lens is proposed to reduce the conductor loss and to create an appropriate farm for favorable implementation at millimeter-wave frequency. The proposed lens consists of a dielectric slab and slot lines whereas the conventional lenses are constructed with parallel conducting plates. The dielectric slab Rotman lens excited in TE$\_$0/ mode shows a high degree of confinement for the fields, low dispersion, and has an appropriate feed structure. A prototype lens has been designed and fabricated with 9 beam ports and 9 array ports together with 9 tapered slot antennas. This lens has been tested in the range from 10 GHz to 15 GHz and the measured beam widths are about 15$^{\circ}$ at 13 GHz. The measurements also show low mutual coupling between beam ports and an efficiency of about 34.6 %. The overall performance is comparable to that of conventional Rotman lenses even though the prototype was tested at lower than desired frequencies in the microwave frequency range due to our limited resources for fabrications and measurements. It is expected that at millimeter-wave frequency the dielectric slab Rotman lens will have lower conductor loss and lower mutual coupling than conventional Rotman lenses.an lenses.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.48.3-49
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• 2017

Interplanetary space of the solar system contains a large number of dust particles, referred to as Interplanetary Dust Particles (IDPs) cloud complex. They are observable through meteors and zodiacal lights. The relative contribution of possible sources to the IDPs cloud complex was an controversial topic, however, recent research (Yang & Ishiguro, 2015 and references therein) suggested a dominance of cometary origin. In this study, we numerically investigated the orbital evolution of cometary dust particles, with special concerns on different evolutionary tracks and its consequences according to initial orbits, size and particle shape. The effect of dust particle density and initial size-frequency distribution (SFD) were not decisive in total cloud complex mass and mass supply rate, when these physical quantities are confined by observed zodiacal light brightness and dust particle SFD at 1 au. We noticed that, if we assume the existence of fluffy aggregates discovered in the Earth's stratosphere and the coma of 67P/Churyumov-Gerasimenko, the required mass supply rate decreases significantly. We also found out that close encounters with planets (mostly Jupiter) are the dominating factor of the orbital evolution of dust particles, as the result, the lifetime of cometary dust particles are shorter than Poynting-Robertson lifetime (around 250 thousand years). As another consequence of severe close encounters, only a small fraction of cometary dust particles can be transferred into the orbit < 1 au. This effect is significant for large size particles of ${\beta}$ < 0.01. The exceptional cases are dust particles ejected from 2P/Encke and active asteroids. Because they rarely encounter with Jupiter, most dust particles ejected from those objects are governed by Poynting-Robertson effect and well transferred into the orbits of small semimajor axis. In consideration of the above effects, we directly estimated probability of mutual collisions between dust particles and concluded that mutual collisions in the IDPs cloud complex is mostly ignorable, except for the case of large sized particles from active asteroids.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1958-1968
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• 2015

Things intelligence communication (M2M or IoT) service activation and global company of OneM2M-related business on aggressive investing and has led to the acceleration of change in the ICT market. But a variety of hacking security technology because of the possibility of secure communication (data exposure, theft, modification, deletion, etc.) has been issued as an important requirement. In this paper, we propose a mutual authentication protocol for secure communications chameleon hash based on the M2M environment. The results of performance analysis efficiency is encryption and decryption an average of 0.7%, calculated rate showed good results as compared to the target algorithm, equivalent to a 3%(Average 0.003 seconds) difference, mutual authentication and encryption region by using the key update advantage of ECC(Elliptic Curve Cryptography)based Chameleon hash function is signed of the operational efficiency, using a collision message verifiable properties demonstrated strong security of the communication section.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.34
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• pp.77-108
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• 2007

The traditional name given to the insurance of third party liabilities and certain contractual liabilities which arise in connection with the operation of ships is protection and indemnity(P & I) insurance. P & I insurance is very different from traditional hull and machinery insurance in that shipowners' hull and machinery insurance is designed primarily to protect the assured against losses to his vessel, whereas P & I insurance seeks to indemnify an shipowner in respect of the discharge of legal liabilities he has incurred in operating his own vessels. This study is to examine the background of establishment of British P & I clubs md, therefore, the identity of P & I insurance. The present British P & I clubs are the remote descendants of the many small and local hull mutual insurance clubs that were formed by British shipowners in the end of 18th century. At that time, British shipowners were dissatified with the state of marine insurance market and, therefore, established clubs together in mutual hull insurance clubs. After the removal of the company monopoly in 1824, greater competition had a good effect on the rates, terms of cover and service offered by the commercial marine insurance market and by Lloyd's underwriters, and the hull clubs became less necessary and went into decline. The burden of British shipowners on liabilities to third parties was steadily increased after the middle of the 19th century, but the amount insured under hull policy was limited in the insured value of the ship. Eventually, the first protection club, that is, the Shipowners' Mutual Protection Society was formed in 1855. It was designed to like past mutual hull clubs, but to cover liabilities for loss of life and personal injury and also the collision risks excluded from the current marine policies, particularly the excess above the limits in hull policies. In 1870, the risks of liability for loss of or damage to cargo carried on board the insured ship was first awarded by the British shipowners. After 1874, many protection clubs formed indemnity club to cover the risk of liability for loss or damage to cargo. As mentioned above, British P & I clubs have been steadily changed according to the response of shipowners under the rapidly changing law of British shipowners' liability, and so on in the future.

• Journal of The Korean Astronomical Society
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• v.32 no.2
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• pp.137-147
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• 1999

Recent studies show the importance of understanding three-dimensional magnetic reconnect ion on the solar surface. For this purpose, I consider non-coplanar magnetic reconnection, a simple case of three-dimensional reconnect ion driven by a collision of two straight flux tubes which are not on the same plane initially. The relative angle e between the two tubes characterizes such reconnection, and can be regarded as a measure of magnetic shear. The observable characteristics of non-coplanar reconnection are compared between the two cases of small and large angles. An important feature of the non-coplanar reconnect ion is that magnetic twist can be produced via the re-ordering of field lines. This is a consequence of the conversion of mutual helicity into self helicities by reconnection. It is shown that the principle of energy conservation when combined with the production of magnetic twist puts a low limit on the relative angle between two flux tubes for reconnect ion to occur. I provide several observations supporting the magnetic twist generation by reconnection, and discuss its physical implications for the origin of magnetic twist on the solar surface and the problem of coronal heating.

• Educational Technology International
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• v.12 no.1
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• pp.21-46
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• 2011

International virtual teamwork offers new opportunities for the professional development of teachers. In this paper, we examine the initial experiences in an ongoing international virtual benchmarking project coordinated by the Finnish Online University of Applied Sciences. What challenges does an international context present for project construction and collaboration? Data from five countries, in the form of participant reflections and researchers' observations, were analysed according to four types of barriers: language, time, technical and mental barriers. Initial data indicates that trust is an essential starting point, as there is neither time nor possibilities to build mutual trust by traditional means. Organisational confidentiality issues, however, can complicate the situation. The project introduces 'collision' as a method of professional development, in which physical and organisational borders are crossed and the skills and competencies needed in global learning environments are acquired.

• Journal of the Korean Institute of Navigation
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• v.9 no.1
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• pp.1-40
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• 1985

The transport of cargoes carried by coastal and ocean-going vessels has increased with the rapid growth of the Korean economy these days. This increase of the sea-borne cargoes has made the Korean coastal traffic so congested that this can be a cause of large pollution as well as great marine casualties such as loss of human lives and properties. Marine casualties generally result from the complicated interaction of natural and human factors; the former being the topographic, marine traffic volume and meteorological conditions, and the latter being the quality of seafares. In this paper, the authors analyse the trend of marine casualties in the Korean coastal and clear up the cause of accidents and examine closely the mutual relations among sea accidents, weather conditions, and marine traffic volume. These accidents are classified into several patterns on hte point of view of ship's size, ship's type and ship's age and its characteristics of each pattern are described in detail. Also, the authors estimate the amount of economical losses resulting from marine casualties which are classified into the accident patterns, and clarify the effects of those losses on B/B(Balance Sheet) and P/L(Profit & Loss) of Korean shipping companies and Korean national economy. The analyzed results of marine casualties are summarized as follows: 1) The average number of sea accidents is 248 cases per year with the loss of 107 persons during last 13 years. 2) Collision is the top of causes of sea accidents (approx. 36.4%), shipwreck the second (approx. 20.3%), agroung the third rank (approx. 18.2%). 3) The ship's number under 1, 000G/T is approx. 74% of total ship's number of accidents. 4) 80% of total number of marine accidents is taken plact at the coastal waters. (involved ports & narrow channels) 5) Marine casualties are occur likely to in the night, the winter and the summer. 6) The average amount of economical losses is approx. 18.5 billion won. (approx. 0.14% of GNP) 7) Shipwreck is the top of the amount of economical losses (approx. 60.4%), collision the second (aprox. 24.5%), aground the third (approx. 9.9%). 8) The amount of economical losses is approx. 5.24% of gross capital of shipping co., 1.24% of shipping revenue, 1.38% of shipping total income in 1983.

• The Journal of the Korea Contents Association
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• v.18 no.9
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• pp.614-622
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• 2018

As multiple weapons are fired simultaneously in multi-target and multi-weapon environments, a possibility always exists in the collision occurred by the intersection between weapon trajectories. The collision between weapons not only hinders the rapid reaction but also causes the loss of the asset of weapons of friendly force to weaken the responsive power against the threat by an enemy. In this paper, we propose an intersection validation and interference elimination algorithm between weapon trajectories in multi-target and multi-weapon environments. The core points of our algorithm are to confirm the possible interference through the analysis on the intersections between weapon trajectories and to eliminate the mutual interference. To show the superiority of our algorithm, we implement the evaluation and verification of performances through the simulation and visualization of our algorithm. Our experimental results show that the proposed algorithm performs effectively the interference elimination regardless of the number of targets and weapon groups by showing that no cross point exists.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.11
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• pp.1317-1322
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• 2014

To complete an image, it is needed to go through the process to capture the actual actor's motion and compose it with virtual environment. Due to the excessive cost for production or lack of post-processing technology, however, it is mostly conducted by manual labor. The actor plays his role depending on his own imagination at the virtual chromakey studio, and at that time, he has to move considering the possible collision with or reaction to an object that does not exist. And in the process of composition applying CG, when the actor's motion does not go with the virtual environment, the original image may have to be discarded and it is necessary to remake the film. The current study suggested and realized depth-based real-time 3D virtual image composition system to reduce the ratio of remaking the film, shorten the production time, and lower the production cost. As it is possible to figure out the mutual collision or reaction by composing the virtual background, 3D model, and the actual actor in real time at the site of filming, the actor's wrong position or acting can be corrected right there instantly.