• The Mathematical Education
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• v.47 no.2
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• pp.197-219
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• 2008

Unlike ordinary situations, deifinitions play a very important role in mathematics education in schools. Mathematical concepts have been mainly acquired by given definitions. However, according to didactical intentions, mathematics education in schools has employed mathematical concepts and definitions with less strict forms than those in pure mathematics. This research mainly discusses definitions used in geometry (promising) course in primary schools to cope with possibilities of creating misconception due to this didactical transformation. After analyzing problems with potential misconceptions, a survey was conducted $\underline{with}$ 80 primary school teachers in Jeju to investigate their recognitions in meaning of mathematical concepts in geometry and attitudes toward teaching. Most of the respondents answered they taught their students while they knew well about mathematical definitions in geometry but the respondents sometimes confused mathematical concepts of polygons and circles. Also, they were aware of problems in current mathematics textbooks which have explained figures in small topics (classes). Here, several suggestions are proposed as follows from analyzing teachers' recognitions and researches in mathematical viewpoints of definitions (promising) in geometric figures which have been adopted by current mathematics textbooks in primary schools from the seventh educational curriculum. First, when primary school students in their detailed operational stage studying figures, they tend to experience $\underline{a}$ collision between concept images acquired from activities to find out promising and concept images formed through promising. Therefore, a teaching method is required to lessen possibility of misconceptions. That is, there should be a communication method between defining conceptual definitions and Images. Second, we need to consider how geometric figures and their elements in primary school textbooks are connected with fundamental terminologies laying the foundation for geometrical definitions and more logical approaches should be adopted. Third, the consistency with studying geometric figures should be considered. Fourth, sorting activities about problems in coined words related to figures and way and time of their introductions should be emphasized. In primary schools mathematics curriculum, geometry has played a crucial role in increasing mathematical ways of thoughts. Hence, being introduced by parts from viewpoints of relational understanding should be emphasized more in textbooks and teachers should teach students after restructuring this. Mathematics teachers should help their students not only learn conceptual definitions of geometric figures in their courses well but also advance to rigid mathematical definitions. Therefore, that's why mathematics teachers should know meanings of concepts clearly and accurately.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.2
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• pp.3-9
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• 2015

Since changes in land use in urban space cause traffic volume and it is closely related to traffic accidents. Therefore, an analysis on the causes of traffic accidents is judged to be an essential factor to establish the measure to reduce traffic accidents. In this regard, the analysis was conducted on the clustering by using the nearest neighbor indexes with regard to the occurrence frequencies of commercial and residential zone based on traffic accident data of the past five years (2009-2013) with the target of local small-medium sized city, Jinju-si. The analysis results, obtained in this study, are as follows: the occurrence frequency of traffic accidents was the highest in spring and the lowest in winter respectively. The clustering of traffic accident occurrence at nighttime was stronger than at daytime. In addition, terms of the analysis on the clustering of traffic accident according to land use, changes according to the seasons was not significant in commercial areas, while clustering density in winter tended to become significantly lower in residential areas. The analysis results of traffic accident types showed that the side-right angle collision of cars was the highest in frequency occurrence, and widespread in both commercial areas and residential areas. These results can provide us with important information to identify the occurrence pattern of traffic accidents in the structure of urban space, and it is expected that they will be appropriately utilized to establish measures to reduce traffic accidents.

• Journal of Korean Theatre Studies Association
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• no.52
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• pp.359-397
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• 2014

This paper describes dramatherapy with a bulmina nervosa patient. She was in her early 20s and has been under the various psychotherapies for cure of deep depression since 2005. We had 24 sessions and 3 persons - the patient, the therapist, and the assist-therapist- participated in dramatherapy. I found there's a big collision between her important roles in the course of initial interview and diagnosis. Those roles are 'a good daughter of mom' and 'an independent adult'. Therefore I defined her bulmina nervosa as 'an symbolic behavior repeats compulsively the failure of separation from her mother.' And I set the general goals, the separation from her mother, the awareness and expression of negative emotions, and the diminuation of overeating and vomiting. To attain these object, we had many different dramatic experiences in dramatherapy. We made a self-portrait, the mask of bulmina nervosa, family sculpture, figure work, the past I and the present I, psychodramatic scene and several stories. In order to objective assessment, I used behavioral observation and 6PSM(6 Pieces Story Making) analysis. First of all the most noticeable change was a rapid decrease in over-eating and vomiting. Before the dramatherapy she had overeaten 30 times per week. At the closure it has fallen off to 1 time per week. Another behavioral changes were shift of outward appearance, not going church, working for living, and having a date with only one. She made 3 stories on 1th session, 13th session, and 23th session. And I comparatively analysed those stories with both qualitative and quantitative method. For qualitative analysis, I classified 5 structures according to the substantial similrarity. On protagonist structure, there's no difference. Three protagonists are dead things. The type of task structure is changed from an escape, a traveling, to metamorphosis. The type of obstruction structure is changed from the protagonist to an outside object. The type of closure structure is changed from an exaggerated happy ending, sad ending to probable happy ending. To quantitify the aspects of transformation, I developed an assesment tool using likert scale. It is composed of 4 sub-categories-reality testing, imagination, ego-strength, optimism problem-solving. In reality testing category, a shift of score was 9-11-15, imagination 2-5-5, ego strength 3-2-2, optimism 6-3-7, and total score 20-21-29. This change of score reflects the growth of problem solving capacity. Viewed in this light, dramatherapy with this girl was successful on the whole. The thing had significant effect on it was psycho-dynamic approach focused on separation from her mother and defence mechanism to avoid negative emotion. And assessment method used in this case will be full of suggestions to researches to come.

• Nuclear Engineering and Technology
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• v.19 no.2
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• pp.85-98
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• 1987

To analyze the aerosol dynamics in severe accidents of LMFBR, a new computer code entitled MCAD (Multicomponent Aerosol Dynamics) has been developed. The code can treat two component aerosol system using relative collision probability of each particles as sequences of accident scenarios. Coagulation and removal mechanisms incorporating Brownian diffusion and gravitational sedimentation are included in this model. In order to see the effect of particle geometry, the code makes use of the concept of density correction factor and shape factors. The code is verified using the experimental result of NSPP-300 series and compared to other code. At present, it fits the result of experiment well and agrees to the existing code. The input variables included are very uncertain. Hence, it requires uncertainty and sensitivity analysis as a supplement to code development. In this analysis, 14 variables are selected to analyze. The input variables are compounded by experimental design method and Latin hypercube sampling. Their results are applied to Response surface method to see the degree of regression. The stepwise regression method gives an insight to which variables are significant as time elapse and their reasonable ranges. Using Monte Carlo Method to the regression model of LHS, the confidence level of the results of MCAD and their variables is improved.

• The Journal of the Korea Contents Association
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• v.4 no.4
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• pp.189-196
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• 2004

Most of the recent researches for ATM switches have been based on multistage interconnection network known as regularity and self-routing property. These networks can switch packets simultaneously and in parallel. However, they are blocking networks in the sense that packet is capable of collision with each other Mainly Banyan network have been used for structure. There are several ways to reduce the blocking or to increase the throughput of banyan-type switches: increasing the internal link speeds, placing buffers in each switching node, using multiple path, distributing the load evenly in front of the banyan network and so on. Therefore, this paper proposes the use of recirculating shuffle-exchange network to reduce the blocking and to improve hardware complexity. This structures are recirculating shuffle-exchange network as simplified in hardware complexity and Rank network with tree structure which send only a packet with highest priority to the next network, and recirculate the others to the previous network. after it decides priority number on the Packets transferred to the same destination, The transferred Packets into banyan network use the function of self routing through decomposition and composition algorithm and all they arrive at final destinations. To analyze throughput, waiting time and packet loss ratio according to the size of buffer, the probabilities are modeled by a binomial distribution of packet arrival. If it is 50 percentage of load, the size of buffer is more than 15. It means the acceptable packet loss ratio. Therefore, this paper simplify the hardware complexity as use of recirculating shuffle-exchange network instead of bitonic sorter.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.858-862
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• 2018

The purpose of this study is to improve the current vessel departure control regulations to prevent traffic congestion after the lifting of vessel departure controls due to restricted visibility. AIS data was collected to analyze the traffic volume of normal traffic flow and after departure control. A statistical test was conducted to confirm the difference in traffic volume at peak hours according to whether or not departure control was used. The results of the t-test showed that there was a significant difference in traffic volume among groups of less than 10,000 tons in gross tonnage. However, the Mann-Whitney test showed no difference in traffic volume regardless of vessel control. Small and medium-sized vessels of less than 10,000 tons after departure control increased in traffic volume by 142% over normal traffic, and it was concluded that traffic congestion resulted as these small and medium-sized vessels were departing at the same time as large vessels of more than 10,000 tons. In order to prevent vessel collision accidents due to traffic congestion, it is suggested that the navigability of vessels less than 160 m or less than 10,000 tons should be improved.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1036-1043
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• 2022

This paper discusses about the development of a visual sensor that can be installed in an automatic mooring device to detect the berthing condition of a vessel. Despite controlling the ship's speed and confirming its location to prevent accidents while berthing a vessel, ship collision occurs at the pier every year, causing great economic and environmental damage. Therefore, it is important to develop a visual system that can quickly obtain the information on the speed and location of the vessel to ensure safety of the berthing vessel. In this study, a visual sensor was developed to observe a ship through an image while berthing, and to properly check the ship's status according to the surrounding environment. To obtain the adequacy of the visual sensor to be developed, the sensor characteristics were analyzed in terms of information provided from the existing sensors, that is, detection range, real-timeness, accuracy, and precision. Based on these analysis data, we developed a 3D visual module that can acquire information on objects in real time by conducting conceptual designs of LiDAR (Light Detection And Ranging) type 3D visual system, driving mechanism, and position and force controller for motion tilting system. Finally, performance evaluation of the control system and scan speed test were executed, and the effectiveness of the developed system was confirmed through experiments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.1-11
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• 2020

Medium to large post structures installed along the roadside without proper protection can lead to serious vehicle damage and occupant injury at the impact. In North America and Europe, splitting systems such as slip base or breakaway device are used to reduce impacts. But the system has the risk of secondary accident when the splitted post falls down to the traffic or pedestrian. Sliding Post have been proposed as a way to solve this problem. By studying the crash test results of the 1.3ton and 0.9ton vehicle with 60 km/h and 80 km/h to a Rigidly Fixed Post (RFP) and Sliding Post (SP), danger of the conventional RFP and crashworthiness of the SP have been proven. While collision analysis only from the acceleration measured at the center of the vehicle assumes the motion of the post is the same as that of the vehicle, in this paper, by adding high speed film data to the analysis with vehicle acceleration could have separate the post motion from the vehicle motion. It gives better explanations on the movement of post and vehicle in each distinctive time step and provides basics to the crashworthy post design.

• Journal of Korean Society of Transportation
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• v.22 no.5
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• pp.75-87
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• 2004

Along the seashore regions in Korea, though strong winds with very large strength are frequently witnessed, no system which can provide appropriate speed information for driving vehicle has been introduced. The driving against strong winds could be very dangerous because of the high possibility of accidents such as rollover and collision. These accidents usually resulted from driver's forced driving try even in difficult situation for steering vehicle, and sometimes overspeed without consideration of wind impact to the vehicles. To reduce accident caused by strong winds, it is important to inform drivers of appropriate driving speeds by perceiving strong winds. By setting up WIS at the main points where strong winds frequently appear and using the variable message sign(VMS) connected to the on-line whether information system, it tis possible to provide desired speed information, which can maintain vehicles' tractive force and maximum running resistance. The case study is conducted on the case of Mokpo-Big-Bridge, which is under construction at Mokpo city. The result show that in case the annual average direction of wind is South and the wind speed is over 8m/hr, the desired speed, which is required in order for vehicles running to South direction to maintain the marginal driving power, is 60km/hr. In addition, for the case of a typhoon such as Memi generated in 2003 year, if wind speed had been 18m/sec in Mokpo city at that time, the running resistance at the speed of 40km/hr is calculated as 1131N. This resistance can not be overcome at the 4th gear(1054N) level, therefore, the gear of vehicles should be reduced down to the 3rd level. In this case, the appropriate speed is 40km/h, and at this point the biggest difference between running resistance and tractive force is generated.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.39-51
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• 2017

Recently, looking at construction sites with either large or small scale, accidents like collision, fall, etc. occur often. These accidents lead to not only damage of human lives but also serious economic loss. In case of large scale constructions sites, safety management systems are used to reduce industrial accidents. However in construction sites with small scale, those systems cannot be applied due to problems such as lack of compatability and high installation expense. In this case, just by putting on safety gears can also reduce industrial accidents. Therefore, in this paper, a safety management systems that can be used at both large and small scale construction sites is proposed. This safety management system consists of a smart module, a repeater and a gateway, and a monitoring system. The smart module, which is detachable, is attached to a safety helmet. This module transfers the current status of the user to the monitoring system through the repeater and the gateway. The repeater transfers the data received from the smart module to the gateway, and the gateway sends the data from the repeater to the monitoring system. The monitoring system shows the user status to the safety supervisor by displaying the data - temperature, height, intensity of illumination, images - received from the smart module. The safety supervisor can monitor the user status in real-time and take immediate action in case of emergency through this monitoring system.