• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.2D
• /
• pp.243-248
• /
• 2008

Moisture damage of asphalt pavements can usually occur because of the loss of adhesion and cohesion between the asphalt binder and aggregate in the asphalt mixture due to presence of water. And this is one of the causes that is effect on the main distress of asphalt pavement. The objective of this study is to find out moisture damage characteristics of asphalt pavement. Effects of this study changes of the material properties and resistance characteristics of moisture damage on the asphalt mixtures under various temperatures and repeated immersion using indirect tensile test and modify Lottman test were evaluated during this study. The asphalt mixtures were produced using straight asphalt binder, SBS modified asphalt binder and aggregates. The material properties (resilient modulus, indirect tensile strength, failure energy and $DCSE_f$) of the asphalt mixtures were generally decreased with increasing to moisture damage caused by the number of repeated immersion. The decrease ratios of material properties by repeated immersion on SBS modified asphalt mixtures were lower than those of straight asphalt mixtures at all three test temperatures. As a conclusion, current criterion for evaluation moisture damage of asphalt mixtures is difficult for using distinction standard because of the limited evaluation criterion with one time immersion and single material property. Based on this research, to evaluate long term moisture damage on asphalt mixtures, material property tests of various kinds with repeated immersion test are considered.

• Journal of Oral Medicine and Pain
• /
• v.33 no.4
• /
• pp.305-316
• /
• 2008

The mandibular advancement device(MAD) has been used to help manage snoring and obstructive sleep apnea. The aims of this study were to specify the demographic and clinical characteristics of the patients receiving long-term treatment with MAD and to quantify the compliance with and side effects of the use of the device. Of 103 patients who were treated with MAD for at least one full year after delivery date, 49 were able to be contacted with telephone and complete follow-up questionnaires were obtainable. They were telephoned to determine whether they were still using the device. If not, they were asked when and why they stopped using it. Patients were also asked how much effectiveness of the MAD in decreasing snoring and how much they and their bed-partners were satisfied with the MAD therapy. The initial respiratory disturbance indices and pre-treatment snoring frequency and intensity were obtained from the medical records of initial visit. All the data were compared between users and nonusers. The results were as follows: 1. Of 49 patients 25 are still using the device, but 24 stopped using it. Among nonusers nobody stopped wearing the device within first 1 month, but 37.5% of nonusers stopped wearing it in the following 6 months, and another 4.2% before the end of the first year. 2. The one-year compliance of the MAD therapy was 79.59%. 3. There were no significant differences in mean age, mean body mass index, and gender distribution between users group and nonusers group. 4. There was no significant difference in mean respiratory disturbance index at initial visit between users group and nonusers group. 5. There was no significant difference in pre-treatment snoring frequency and intensity between users group and nonusers group. 6. The degree of decrease in snoring with use of MAD was significantly higher in the users when compared to nonusers. 7. Patient's overall satisfaction with treatment outcome was significantly higher in the users when compared to nonusers. 8. Bed partner's satisfaction with treatment outcome tended to be higher in the users when compared to nonusers. 9. The most frequent reasons why patients discontinued wearing the MAD were: jaw pain(25%), dental pain(20.83%), broken appliance(20.83%), hassle using(16.67%), lost weight(8.3%), dental work(8.3%), no or little effect(4.17%), sleep disturbance(4.27).

• Journal of Navigation and Port Research
• /
• v.28 no.10 s.96
• /
• pp.899-908
• /
• 2004

The rise of income and introduction of 5 day a week working system give korean people opportunities to enjoy their leisure time. And many korean people have much interest in oceanic sports such as yachting and also oceanic leisure equipments. With the popularization and development of the equipments, the scope of oceanic activities has been expanding in Korea just as in the advanced oceanic countries. However, The current conditions for the sports in Korea are not advanced and even worse than underdeveloped countries. In order to develop the underdeveloped resources of Korean marina, we need to customize the marina models of advanced nations to serve the specific needs and circumstances of Korea As such we have carried out a comparative analysis of how Austrailia, Newzealand, Singapore, japan and Malaysia operate their marina, reaching the following conclusions. Firstly, in marina operations, in order to protect personal property rights and to preserve the environment, we must operate membership and non-membership, profit and non-profit schemes separately, yet without regulating the dress code entering or leaving the club house. Secondly, in order to accumulate greater value added, new sporting events should be hosted each year. There is also the need for an active use of volunteers, the generation of greater interest in yacht tourism, and the simplification of CIQ procedures for foreign yachts as well as the provision of language services. Thirdly, a permanent yacht school should be established, and classes should be taught by qualified instructors. Beginners, intermediary, and advanced learner classes should be managed separately with special emphasis on the dinghy yacht program for children. Fourthly, arrival and departure at the moorings must be regulated autonomically, and there must be systematic measures for the marina to be able, in part, to compensate for loss and damages to equipment, security and surveillance after usage fees have been paid for. Fifthly, marine safety personnel must be formed in accordance with Korea's current circumstances from civilian organizations in order to be used actively in benchmarking, rescue operations, and oceanic searches at times of disaster at sea.

• The Korean Journal of Air & Space Law and Policy
• /
• v.25 no.1
• /
• pp.27-54
• /
• 2010

Soon after September 11 attacks in 2001, there were strong demands in Korea on making relevant laws and regulations on aviation security, and Korean parliament legislated "Aviation Safety and Security Act"to fulfill the demands on safety and security of aircrafts during aviation. However, the current Aviation Safety and Security Act seems to have many problems which do not meet the practical needs in Korea, because there were not enough considerations on the practical needs and extinguishable national circumstances on civil aviation system in Korea, but only regarded the relevant international conventions and foreign practices on it. In this context, it is necessary to amend several provisions in Aviation Safety and Security Act to enhance more practical efficiencies in its implementation through systematization of the provisions on crimes which may happen during aviation. In this context, this article argues two main issues. First, Article 39 of Aviation Safety and Security Act does not express whether it is possible to punish the attempt of crime of causing damage to aircraft. Therefore, regarding a principle of legality, it is impossible to punish the perpetrator even when coincidently failed to destruct or damage aircraft. In this context, this article argues that the necessity to introduce the possibility to punish the attempt of crime of causing damage to aircraft. Second, regarding Article 160 of Civil Aviation Act of Korea, current Aviation Safety and Security Act should be amended by guaranteeing the culpability of negligence of crime of causing damage to aircraft.

• Journal of Internet Computing and Services
• /
• v.21 no.6
• /
• pp.23-31
• /
• 2020

This study was carried out to generate various images of railroad surfaces with random defects as training data to be better at the detection of defects. Defects on the surface of railroads are caused by various factors such as friction between track binding devices and adjacent tracks and can cause accidents such as broken rails, so railroad maintenance for defects is necessary. Therefore, various researches on defect detection and inspection using image processing or machine learning on railway surface images have been conducted to automate railroad inspection and to reduce railroad maintenance costs. In general, the performance of the image processing analysis method and machine learning technology is affected by the quantity and quality of data. For this reason, some researches require specific devices or vehicles to acquire images of the track surface at regular intervals to obtain a database of various railway surface images. On the contrary, in this study, in order to reduce and improve the operating cost of image acquisition, we constructed the 'Defective Railroad Surface Regeneration Model' by applying the methods presented in the related studies of the Generative Adversarial Network (GAN). Thus, we aimed to detect defects on railroad surface even without a dedicated database. This constructed model is designed to learn to generate the railroad surface combining the different railroad surface textures and the original surface, considering the ground truth of the railroad defects. The generated images of the railroad surface were used as training data in defect detection network, which is based on Fully Convolutional Network (FCN). To validate its performance, we clustered and divided the railroad data into three subsets, one subset as original railroad texture images and the remaining two subsets as another railroad surface texture images. In the first experiment, we used only original texture images for training sets in the defect detection model. And in the second experiment, we trained the generated images that were generated by combining the original images with a few railroad textures of the other images. Each defect detection model was evaluated in terms of 'intersection of union(IoU)' and F1-score measures with ground truths. As a result, the scores increased by about 10~15% when the generated images were used, compared to the case that only the original images were used. This proves that it is possible to detect defects by using the existing data and a few different texture images, even for the railroad surface images in which dedicated training database is not constructed.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.51 no.2
• /
• pp.1-11
• /
• 2023

This study intended to develop a technique for quantitatively and 3-dimensionally predicting the potential failure zone and impulse that may occur when trees are fall down. The main outcomes of this study are as follows. First, this study established the potential failure zone and impulse calculation formula in order to quantitatively calculate the risks generated when trees are fallen down. When estimating the potential failure zone, the calculation was performed by magnifying the height of trees by 1.5 times, reflecting the likelihood of trees falling down and slipping. With regard to the slope of a tree, the range of 360° centered on the root collar was set in the case of trees that grow upright and the range of 180° from the inclined direction was set in the case of trees that grow inclined. The angular momentum was calculated by reflecting the rotational motion from the root collar when the trees fell down, and the impulse was calculated by converting it into the linear momentum. Second, the program to calculate a potential failure zone and impulse was developed using Rhino3D and Grasshopper. This study created the 3-dimensional models of the shapes for topography, buildings, and trees using the Rhino3D, thereby connecting them to Grasshopper to construct the spatial information. The algorithm was programmed using the calculation formula in the stage of risk calculation. This calculation considered the information on the trees' growth such as the height, inclination, and weight of trees and the surrounding environment including adjacent trees, damage targets, and analysis ranges. In the stage of risk inquiry, the calculation results were visualized into a three-dimensional model by summarizing them. For instance, the risk degrees were classified into various colors to efficiently determine the dangerous trees and dangerous areas.