• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.11
• /
• pp.130-136
• /
• 1998

This paper develops an efficient algorithm for the minimum distance calculation between two general polyhedra(convex and/or concave) in three-dimensional space. The polyhedra approximate objects using flat polygons which composed of more than three vertices. The algorithm developed in this paper basically computes minimum distance between two polygons(one polygon per object) and finds a set of two polygons which makes a global minimum distance. The advantage of the algorithm is that the global minimum distance can be computed in any cases. But the big disadvantage is that the minimum distance computing time is rapidly increased with the number of polygons which used to approximate an object. This paper develops a method to eliminate sets of two polygons which have no possibility of minimum distance occurrence, and an efficient algorithm to compute a minimum distance between two polygons in order to compensate the inherent disadvantage of the algorithm. The correctness of the algorithm is verified not only comparing analytically calculated exact minimum distance with one calculated using the developed algorithm but also watching a line which connects two points making a global minimum distance of a convex object and/or a concave object. The algorithm efficiently finds minimum distance between two convex objects made of 224 polygons respectively with a computation time of about 0.1 second.

• International Journal of Internet, Broadcasting and Communication
• /
• v.6 no.2
• /
• pp.13-16
• /
• 2014

This study aims to examine the effects of watching 2D and 3D images on the blink rate. Regarding the image watch, their blink rate for 2D and 3D images was separately checked for 1 minute in the 1m distance, before the watch, after 15 minutes of watch, and after 30 minutes of watch. About the change of their blink rate in the 2D image watch, it tended to become higher than that before watching the image; however, there was no statistical significance (paired t-test, p=0.106, p=0.062). And in the 2D image watch, it tended to increase in comparison between after 15 minutes and after 30 minutes, but there was no statistical significance (paired t-test, p=0.623). Meanwhile, about the change of their blink rate in the 3D image watch, it tended to decrease statistically significantly both after 15 minutes and after 30 minutes when compared with that before watching the image (paired t-test, p=0.000, p=0.000). In the 3D image watch, it tended to increase in comparison between after 15 minutes and after 30 minutes; however, there was no statistical significance (paired t-test, p=0.867).

• Journal of the Korean Society of School Health
• /
• v.4 no.2
• /
• pp.159-175
• /
• 1991

This study was carried out with 2,195 boy and girl middle school students in Inchon to examine environmental elements which may change vision and cause shortsightedness, and also to find out common knowledge of eye health. Its results are as follows. 1) As school year goes up, the normal eye sighted diminish but the visually handicapped regardless of left and right eyes increase. 2) Among weak sighted students below 0.9, boys are 42.2% and girls are 55.3%, the latter are larger by 13.1 %. Vision weakens rapidly especially for third year girl students. 3) Environmental, individual, everyday life elements which cause shortsightedness are studied, (1) environmental elements; illumination in watching TV and studying (2) individual elements; distance from TV and books, posture in studying (3) everyday life elements; hour of watching TV, hour of using game tools average, hour of studying 4) Knowledge of eye health is generally poor without regard to sex and wearing glasses. So adolescent students are in advance educated proper eye care to prevent shortsighted elements.

• Journal of Fisheries and Marine Sciences Education
• /
• v.29 no.1
• /
• pp.201-208
• /
• 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 Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.125-128
• /
• 2013

The reason why visual fatigue occurs while watching 3D TV is because the left/right images of the fixed disparity are played. This paper proposes a measuring method of pupil distance and the 3D location of a viewer using stereo camera modules, and a reflection method of the data into 3D TV.

• Journal of Intelligence and Information Systems
• /
• v.16 no.3
• /
• pp.147-161
• /
• 2010

As broadcasting and communication are converged recently, communication is jointed to TV. TV viewing has brought about many changes. The IPTV (Internet Protocol Television) provides information service, movie contents, broadcast, etc. through internet with live programs + VOD (Video on demand) jointed. Using communication network, it becomes an issue of new business. In addition, new technical issues have been created by imaging technology for the service, networking technology without video cuts, security technologies to protect copyright, etc. Through this IPTV network, users can watch their desired programs when they want. However, IPTV has difficulties in search approach, menu approach, or finding programs. Menu approach spends a lot of time in approaching programs desired. Search approach can't be found when title, genre, name of actors, etc. are not known. In addition, inserting letters through remote control have problems. However, the bigger problem is that many times users are not usually ware of the services they use. Thus, to resolve difficulties when selecting VOD service in IPTV, a personalized service is recommended, which enhance users' satisfaction and use your time, efficiently. This paper provides appropriate programs which are fit to individuals not to save time in order to solve IPTV's shortcomings through filtering and recommendation-related system. The proposed recommendation system collects TV program information, the user's preferred program genres and detailed genre, channel, watching program, and information on viewing time based on individual records of watching IPTV. To look for these kinds of similarities, similarities can be compared by using ontology for TV programs. The reason to use these is because the distance of program can be measured by the similarity comparison. TV program ontology we are using is one extracted from TV-Anytime metadata which represents semantic nature. Also, ontology expresses the contents and features in figures. Through world net, vocabulary similarity is determined. All the words described on the programs are expanded into upper and lower classes for word similarity decision. The average of described key words was measured. The criterion of distance calculated ties similar programs through K-medoids dividing method. K-medoids dividing method is a dividing way to divide classified groups into ones with similar characteristics. This K-medoids method sets K-unit representative objects. Here, distance from representative object sets temporary distance and colonize it. Through algorithm, when the initial n-unit objects are tried to be divided into K-units. The optimal object must be found through repeated trials after selecting representative object temporarily. Through this course, similar programs must be colonized. Selecting programs through group analysis, weight should be given to the recommendation. The way to provide weight with recommendation is as the follows. When each group recommends programs, similar programs near representative objects will be recommended to users. The formula to calculate the distance is same as measure similar distance. It will be a basic figure which determines the rankings of recommended programs. Weight is used to calculate the number of watching lists. As the more programs are, the higher weight will be loaded. This is defined as cluster weight. Through this, sub-TV programs which are representative of the groups must be selected. The final TV programs ranks must be determined. However, the group-representative TV programs include errors. Therefore, weights must be added to TV program viewing preference. They must determine the finalranks.Based on this, our customers prefer proposed to recommend contents. So, based on the proposed method this paper suggested, experiment was carried out in controlled environment. Through experiment, the superiority of the proposed method is shown, compared to existing ways.

• Journal of Korean Society for Geospatial Information Science
• /
• v.17 no.4
• /
• pp.75-80
• /
• 2009

The Beacon Mounds play a important role in defence and communication extending from the period of the Three States to the period of Chosun. About the research of beacon mounds have focused on investigation in old literature. This research analyzed geographic factors such as altitude, cross section, distance and visible distance affect in selecting location of beacon mounds. And it was presumed how each beacon mound geographic characteristics was considered in selecting location of beacon mounds. As a result, it is presumed that communicating among beacon mounds and watching the coast were affected by geographic characteristics and selecting location of beacon mounds was considered by several geographic factors.

• Journal of Korean Ophthalmic Optics Society
• /
• v.16 no.3
• /
• pp.299-305
• /
• 2011

Purpose: In watching 3D stereoscopic display using the binocular disparity, effect of difference of the pupillary distance between the adults and children on the perception of depth were investigated. Methods: The average PD of children was determined from the PD measurements of children of the elementary school of 2nd and 3rd grade in Seoul. The location of crossing visual axes were derived from the relation of the binocular disparity and the PD for the adults and children. Results: The average PD of the children was measured to be 57.3 mm which was smaller than the average PD of the adults that was known to be about 65 mm. As the binocular disparity increases to the positive direction, the crossing location steeply moves farther behind the screen. On the other hand, when the binocular disparity increases to the negative direction, the crossing location gradually moves toward the viewer. For the same amount of the binocular disparity, the crossing locations were derived to be larger for the children than the adults due to the difference of the PD. Therefore, children will perceive larger depth than the adults. Conclusions: Small PD of the viewer causes the larger amount of the depth perception. In producing the stereoscopic images, the average PD of children as well as adults need to be considered.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.11 no.2
• /
• pp.214-221
• /
• 2005

Purpose: This study was to investigate the perception of the myopia in early school-aged children's mother and develope myopia preventive education program. Method: Data was collected from June 1th to 24th, 2003. The sample group(two elementary schools in A city)consisted of 105students mother with normal vision(naked vision 1.0 or more), 105 students mother with subnormal vision(0.7 or less). The data was analyzed using S.A.S. For the test of homogeneity and significance of variable, Fisher's Exact test and Student's t-test were used. Results: 1. There was significant difference in perception of being changed the children's eyesight between normal and myopia group(t=7.86, p=.0492). 2. High scores of cause of myopia were distance from TV or computer to viewer and time of watching TV or using computer in both groups. 3. There was significant difference in perception score of cause of myopia in the myopia group was 13.26, and 18.04 in the normal group(t=3.01, p=0.003). Especially in the unbalanced and regulated diet, regulated exercise, distance of eyes reading books and illumination, normal group had more perception score than myopia group. Conclusion: A myopia education program for children and parents should be planed and the effect be verified.

• Journal of the Korean Institute of Educational Facilities
• /
• v.5 no.2
• /
• pp.16-29
• /
• 1998

Bell Laboratory introduced the sound and visual system for the first time in 1927. Since then, the development of telecommunication technology made it possible for people located far away to communicate each other watching through the TV screen. Over the period different types of telelecturing systems have prospered in line with the development of telecommunication technology. Therefore, it is quite natural that telelecturing/conferending system attracts the attention of many people as a new way of educating people located in a long distance. In the industrial sector, telelecturing systems already come into wide use to save time and training and travelling expense. In this study, I examine the concept and characteristics of telelecturing/conferencing system and introduce different types telelecturing system developed in parallel with the development of communication technology. Then, I analyze how those merits of the telelecturing system can be applied to educational purpose. Finally, I propose and design ideal telelectuirng/conference facilities consisting of telelecturing rooms, bilateral movie system, seats, ceilings, color, TV screen, lighting, acoustics, humidities and temperature control, security system, projection system to maximize the educational purpose and effectiveness.