• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.257-268
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• 1998

During cleaning and shaping of narrow and curved canals, it is very difficult or nearly impossible to maintain the original canal shape. Procedural accidents such as, ledge, zipping, perforation, and instrument breakage are frequently occurred and even may lead to failure of endodontic therapy. To prevent these kinds of accidents, various instrumentation techniques and materials have been introduced. Recently some nickel titanium (NiTi) files are introduced and it is reported that These NiTi files created rounder preparations with less transportation than conventional instruments in curved canals. This study compared the change of the canal curvature and procedural accidents after instrumentation produced by stainless steel K-flexo file, and NiTi rotary files (Profile 29 and Quantec 2000). Thirty narrow and curved canals (25-45 degree) of extracted human molars were randomly divided into three groups. In group 1, canals were instrumented using a step-back and watch-winding/pull motion with K-flexo files. In group 2, canals were prepared with Profile 29. Group 3, canals were prepared with Quantec 2000 files. Before and after preparation of canals, periapical radiographs were taken and scanned. The change of canal curvature were measured using Photoshop 4.0 program and the incidence of procedural accidents were also evaluated. The results were as follows: 1. All group showed some loss of canal curvature after instrumentation. 2. Average loss of canal curvature was $6.70{\pm}5.31$ degree for group 1, $3.80{\pm}2.57$ degree for group 2, and $5.40{\pm}4.83$ degree for group 3. All group There was significant change in curvature between before and after instrumentation (p<0.05). But there was no statistical difference amoung 3 groups. 3. In group I, there were no procedural accidents, such as ledging, perforation, or instrument fracture. In group 2, two cases of ledge and one case of instrument fracture were produced Goup 3, each one case of ledge, perforation and instrument fracture were occurred. Whthin the limits of above results, It seems that NiTi rotary instrumentation is not All Mighty and if we use uncarefully, it is more dangerous to produce some procedural accidents than conventional hand files. But more studies should be taken to evaluate the exact effects of NiTi rotary instrumentations.

• Journal of Korean Society of Forest Science
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• v.45 no.1
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• pp.11-25
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• 1979

There was much mass movement at many different mountain side of Peong Chang area in Kwangwon province by the influence of heavy rainfall through August/4 5, 1979. This study have done with the fact observed through the field survey and the information of the former researchers. The results are as follows; 1. Heavy rainfall area with more than 200mm per day and more than 60mm per hour as maximum rainfall during past 6 years, are distributed in the western side of the connecting line through Hoeng Seong, Weonju, Yeongdong, Muju, Namweon and Suncheon, and of the southern sea side of KeongsangNam-do. The heavy rain fan reason in the above area seems to be influenced by the mouktam range and moving direction of depression. 2. Peak point of heavy rainfall distribution always happen during the night time and seems to cause directly mass movement and serious damage. 3. Soil mass movement in Peongchang break out from the course sandy loam soil of granite group and the clay soil of lime stone and shale. Earth have moved along the surface of both bedrock or also the hardpan in case of the lime stone area. 4. Infiltration seems to be rapid on the both bedrock soil, the former is by the soil texture and the latter is by the crumb structure, high humus content and dense root system in surface soil. 5. Topographic pattern of mass movement spot is mostly the concave slope at the valley head or at the upper part of middle slope which run-off can easily come together from the surrounding slope. Soil profile of mass movement spot has wet soil in the lime stone area and loose or deep soil in the granite area. 6. Dominant slope degree of the soil mass movement site has steep slope, mostly, more than 25 degree and slope position that start mass movement is mostly in the range of the middle slope line to ridge line. 7. Vegetation status of soil mass movement area are mostly fire field agriculture area, it's abandoned grass land, young plantation made on the fire field poor forest of the erosion control site and non forest land composed mainly grass and shrubs. Very rare earth sliding can be found in the big tree stands but mostly from the thin soil site on the un-weatherd bed rock. 8. Dangerous condition of soil mass movement and land sliding seems to be estimated by the several environmental factors, namely, vegetation cover, slope degree, slope shape and position, bed rock and soil profile characteristics etc. 9. House break down are mostly happen on the following site, namely, colluvial cone and fan, talus, foot area of concave slope and small terrace or colluvial soil between valley and at the small river side Dangerous house from mass movement could be interpreted by the aerial photo with reference of the surrounding site condition of house and village in the mountain area 10. As a counter plan for the prevention of mass movement damage the technics of it's risk diagnosis and the field survey should be done, and the mass movement control of prevention should be started with the goverment support as soon as possible. The precautionary measures of house and village protection from mass movement damage should be made and executed and considered the protecting forest making around the house and village. 11. Dangerous or safety of house and village from mass movement and flood damage will be indentified and informed to the village people of mountain area through the forest extension work. 12. Clear cutting activity on the steep granite site, fire field making on the steep slope, house or village construction on the dangerous site and fuel collection in the eroded forest or the steep forest land should be surely prohibited When making the management plan the mass movement, soil erosion and flood problem will be concidered and also included the prevention method of disaster.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.6 no.2
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• pp.63-69
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• 2012

The analysis was conducted for studying the degree of internet addiction and the difference between addicted group and non-addicted group based on usage time. The target group is consisted of 30 people who receive the training at home. The purpose of this training is to reduce digital divide for the disabled with reduced mobility. As a result, the typical user group, less than the 31-point appeared as 4 cases, the potentially dangerous user I group, from 31 to 54 points appeared as 25 cases, the potentially dangerous user II group, from the 54-67 points appeared as only one person. However, there was no game addiction case, more than 67 points. In addition, there was no significant difference in impulsivity and aggression between the high-risk group of 9 persons using internet more than 2.7 hours and the typical user group of 21 persons with less risk. From the result, there are two possibilities. On the one hand, an increase of the usage time for the disabled might not lead to addiction. Or, on the other hand, a measure of addiction for non-disabled might not suitable for the disabled addiction examination.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.397-403
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• 2020

This survey was willing to suggest the basic data required for strategic planning to improve the recognition rate on radiation by investigating the difference between the college students who major in radiology and who don't about using radiation. As the results of questionnaire survey on 'knowledge, degree of self-consciousness, danger, convenience and management' targeting 441 students who belonged to D college, 75% of them answered that radiation exists in their daily lives and 54% of them answered they did not know about radiation well. It showed that radiation is dangerous no matter how much the amount is (56%) and it is not dangerous if it is managed well (81%). They answered that they enjoy the convenience of radiation (82%) and the use for medical purpose took the highest percentage among them (58%). It showed that it is important to manage the radiation and should be controlled by the government in institutional way than the individual (64%). The negative answer to the question of 'do you trust the government?' was dominant (75% below average). As the results of this survey, it was recognized that both of them who major in radiology or not were aware of positive aspect of radiation (especially medical technology field) well and the improving the perception of radiation led by the government and definite restriction on its safety should be preceded for safe use.

• The Journal of the Korea Contents Association
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• v.18 no.6
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• pp.169-179
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• 2018

The Korean society has become increasingly concerned about the safety consciousness because of the Sewol Ferry disaster in April 2014. This shows the absence of social system and safety consciousness of Korean society that has been rapidly growing through fast industrialization. The purpose of this paper is to suggest guidelines for the production of a safety animation by approaching the discourse of public value. For this research process, first, literature review will be conducted by focusing on the safety culture, causes of safety accidents, safety education and educational effect using animation. Second, I will analyze 11 safety animation films by focusing on (1) construction of accident environment(narrative, character and background design) (2) exploration of dangerous elements and accident happening(accident type and dangerous elements, method of direction for accident happening, damage degree) (3) the guideline for safety behaviour. Third, guidelines for the production of safety animation will be suggested by analyzing the results of literature reviews and case studies in a comprehensive way. It is expected that this paper will be used as a basic data for academic research and animation production related to the safety accident.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.67-76
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• 2012

In this study, we established objective appraisal standard by applying newly made appraisal standard to those areas equipped with the protection system targeted to the Mobility handicapped announced in this edition (issue 5, volume 9(Oct., 2010)) beyond simple evaluation related to protector satisfaction. Additionally, we achieved efficient budget execution by conducting the preliminary estimation assessment regarding those areas on which recognition devices should be newly deployed. Through the assessment of the system coordination, the maximum safety distance is proved to be 72.2m. On the basis of this result, we applied dangerous grade to the deployment of recognition devices considering both psychological and accidental risk. With this, we proposed valuation basis to enable us to do future business. Based on this assessment standard, the degree of risk is proved to decrease by 35.2% compared to before conducting the demonstration project in terms of evaluation of comprehensive risk regarding intended areas. Additionally, we confirmed the fact that the degree of risk can decrease by 33.1% totally after having recognition devices built according to the deployment standard within budget. Furthermore, comprehensive risk can decrease up to 94% compared to the level of the demonstration project even though we spend 21.9% less of the existing budget. Hence, we can say that the deployment method of recognition devices related to the degree of risk is applied efficiently in the near future in terms of controlling comprehensive risk and cutting down budget through this study.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.4
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• pp.502-511
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• 1997

This study was to Investigate the consumer's understanding and purchasing foods, which were produced by organic agricultured method. The results of this study were as follows: 1. When shopping foods, the items which were deeply considered were taste of family and food safety. 2 Contaminants which were considered to be dangerous were, in decreasing order, agricultural chemical residue, food additives, environmental contaminant, and microbial hazard. Consumer's perception to agricultural chemical residue In foods was 'be much serious' and over 4.0 by Likert 5 scale. 3. Among of characteristics which was associated with organic farmming foods, taste and nutrition were considered the least important characteristic, whereas safety and good health were considered the most important characteristic. 4. The foods which were thought to be polluted by agricultural chemical residue were, in decreasing order fruit, vegetable, cereal, egg, meat, milk, and fish & shellfish. 5. The respondants' purchasing degree for organic farmming foods was 'often purchase' and 3.44 by Likert 5 scale. These result showed significant difference for age(p＜0.05), for education level (p＜0.05), for income(p＜0.05) and for food expenditure(p＜0.05), respectively 6. The type of organic farmming food which frequently purchased were, in decreasing order, vegetable. fruit, egg, cereal, milk, and meat. The reasons why consumer purchased organic farmming food were, in decreasing order, no pesticide/therbicides, no artifical fertilizer, no growth regulators, residue free, and good quality. 7. 78% of respondants Indicated that they bought organic farmming food in this year increasely or same as last year and 91.9% of respondants Indicated that they plan to buy organic farmming foods in next year.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.103-105
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• 2016

Shin(2015) etc. published use of smart phones on the effect the use of smart phones released in the ship duty performed by survey of using smart phones Status and Usage in previous studies, soon as the survey provided this environment(36% on sailing) where you can use your smart phone from the ship, at the risk of officers using survey questionnaires were analyzed smart phones that use about twice the risk than before. In this study, maritime those who have experienced a period of sailors aboard a diagnostic test subjects Ship Handling Simulation analysis evaluation item of Maritime Traffic Admit, Proximity evaluation of a ship evaluation, by measuring the degree of danger that the subjective evaluation and control of the ship evaluation to evaluate the risk on navigation safety. Also indicated the risk of a smart phone quantitatively by measuring the time that the awareness of dangerous situation depending on using smart phone or not.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.1
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• pp.1-9
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• 2016

In this paper, we propose a new learning control scheme for various walk motion control of biped robot with same learning-base by neural network. We show that learning control algorithm based on the neural network is significantly more attractive intelligent controller design than previous traditional forms of control systems. A multi layer back propagation neural network identification is simulated to obtain a dynamic model of biped robot. Once the neural network has learned, the other neural network control is designed for various trajectory tracking control with same learning-base. The biped robots have been received increased attention due to several properties such as its human like mobility and the high-order dynamic equation. These properties enable the biped robots to perform the dangerous works instead of human beings. Thus, the stable walking control of the biped robots is a fundamentally hot issue and has been studied by many researchers. However, legged locomotion, it is difficult to control the biped robots. Besides, unlike the robot manipulator, the biped robot has an uncontrollable degree of freedom playing a dominant role for the stability of their locomotion in the biped robot dynamics. From the simulation and experiments the reliability of iterative learning control was illustrated.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.461-471
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• 2010

Recently, Augmented Reality(AR) technologies have been emerged, which shows the types of digital contents integrating real and virtual worlds. To maximize the effect of AR technology, tangible user interface, which enables users to interact with the contents in the same way in which they manipulate objects in real world, is applied. In particular, we expect that the technologies are able to enhance learners' interests and degree of immersion, and produce new learning contents in order to maximize the effect of learning. In this paper, we propose a learning system for scientific experiments with multi-touch screen and tangible user interface. The system consists of an experiment table equipped with a large multi-touch screen and a realistic learning device that can detect the user's simple gestures. In real world, some scientific experiments involve high cost, long time or dangerous objects, but this system will overcome such hindrance and provide learners with a variety of experiment experience in realistic ways.