• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1279-1287
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• 2014

The purpose of this study is to develop the U-turn accident model at signalized intersections in urban areas. The characteristics of the accidents which are associated with U-turn operation at 3 and 4-legged signalized intersections was analyzed and the U-turn accident model was developed by regression analysis in Changwon city. First, in order to analyze the effectiveness on traffic accidents by U-turn installation, the difference of mean of traffic accident number are measured between two groups which are composed by whether or not U-turn installation the groups by Mann-Whitney U test. The result of significance test showed that intergroup comparison on mean by accident types made difference except rear-end accident type and by accident locations exit section only showed difference in significance level at 4-legged intersections, so the accident number have more where the U-turn is permitted than not. Response measures about the number of accidents were classified by whether accidents occurred and accident model were constructed using binomial logistic regression analysis method. The developed models show that the variables of conflict traffic, number of opposing lane are adopted as independent variable for both intersections. The variables of longitudinal grade for 3-legged signalized intersection and number of crosswalk for 4-legged signalized intersection at which the U-turn is permitted is adopted as independent variable only. These study results suggest that U-turn would be permitted at the intersection where the number of opposing lane is more than 3.5 each, the longitudinal grade of opposing road is upward flow and there is need to establish the U-turn traffic sign at signalized intersections.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.743-748
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• 2019

This study suggested a process of redesigning and implementing problem based learning to enhance students' active and collaborative learning activities and learning outcomes. The results of this study are as follows. First, the ef ect of class participation, academic self-regulated learning, and academic self-efficacy were examined. As a result, first, the average of learning activity, class extension, and participation in class was high in the difference between before and after class. Second, the post average scores of all the factors except the 'evaluation' were higher than before. Third, academic self-efficacy showed a significant difference only in 'task preference'. Finally, students' satisfaction with the class was also high. The professor was also able to grasp the characteristics of individual students by designing and operating the classes using PBL, and it was confirmed that the interaction with students increased. Based on the results of this study, we discussed the limitations and educational implications of the problem based learning class and propose successful problem based learning design and operation of the classroom.

• Membrane Journal
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• v.20 no.2
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• pp.127-134
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• 2010

This study is conducted about the system that reduces organism after fermenting food waste from a food waste disposal equipment, divides gas made when food waste is fermented into gas and water, and then sends gas to a reactor again, condenses water, and apply it to the MBR system with submerged MF hollow fiber membranes. A submerged MF hollow fiber membrane module was installed to a food waste disposal equipment and a water treatment system made by Bio Hitech Co,. Ltd. to process food waste generated from a staff cafeteria in a H institute for 90 days. For initial seeding of a food waste disposal equipment, 305 kg of rice bran, chaff, and sawdust as well as 1,648 kg of food were input during the operation, and 1,600 L of condensed wastewater occurred. Fermented by-product after finishing running a food waste disposal equipment was 386 kg and its reduction was shown to be 80%. The organism was processed by applying submerged MF hollow fiber membrane module to the MBR system of condensed wastewater, and the result shows reduction rates were BOD 99.9%, COD 97.5%, SS 98.6%, T-N 54.6% and T-P 34.7% and the total colon bacillus was perfectly eliminated.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.1
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• pp.48-58
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• 2001

After performing mandibular setback surgery, we found some changes in patterns and organs of speech. This investigation was undertaken to investigate the aspect and degree of speech patterns according to the amount of surgical setback in mandibular prognathic patients. Thirteen patients with skeletal Class III malocclusion were studied preoperative and postoperative over 6 months. They had undergone the mandible setback operation via bilateral sagittal split ramus osteotomy(BSSRO). We split the patients into two groups. Group 1 included patients whose degree of mandibular setback was 6mm or less, and Group 2 above 6mm. Control group was two adults wish normal speech patterns. A phonetician performed narrow phonetic transcriptions of tape-recorded words and sentences produced by each of the patients and the acoustic characteristics of the plosives, fricatives, and flaps were analyzed with a phonetic computer program (Computerized Speech Lab(CSL) Model 4300B(USA)). The results are as follows: 1. Generally, Patients showed longer closure duration of plosives, shorter VOT(voice onset time) and higher ratio of closure duration against VOT. 2. Patients showed more frequent diffuse distribution than the control group in frication noise energy of fricatives. 3. In fricatives, frequency of compact from were higher in group 1 than in group 2. 4. Generally, a short duration of closure for /ㄹ/ was not realized in the patient's flaps. Instead, it was realized as fricatives, sonorant with a vowel-like formant structure, or trill type consonant. 5. Abnormality of the patient's articulation was reduced, but adaptation of their articulation after surgery was not perfect and the degree of adaptation was different according to the degree of surgical setback.

• Journal of Korea Port Economic Association
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• v.34 no.1
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• pp.81-98
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• 2018

Port logistics is essential for Korea's economy which heavily rely on international trade. Vast amounts of capital and time are consumed for the operation and development of ports to improve their competitiveness. Therefore, it is important to forecast cargo volume in order to establish the optimum level of construction and development plan. Itemized forecasting is necessary for appropriate port planning, since disaggregate approach is able to provides more realistic solution than aggregate forecasting. We introduce a new time series model which is Two-way Seasonality Multiplied Regressive Model (TSMR) to forecast oil cargo volume, which accounts for a large portion of total cargo volume in Korea. The TSMR model is designed to take into account the characteristics of oil cargo volume which exhibits trends with short and long-term seasonality. To verify the TSMR model, existing forecasting models are also used for a comparison reason. The results shows that the TSMR excels the existing models in terms of forecasting accuracy whereas the TSMR displays weakness in short-term forecasting. In addition, it was shown that the TSMR can be applied to other cargoes that have trends with short- and long-term seasonality through testing applicability of the TSMR.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.5
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• pp.1-10
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• 2014

This research focuses on the warrants for the Two-Way Left-Turn Lanes (TWLTL). Using a microscopic traffic simulation tool, two key parameters were investigated herewith. One is a wide range of the Design Hourly Volume (DHV), reflective of recent Korean roadway volume characteristics, that is conventionally reduced from the Average Daily Traffic (ADT). The other is driveway spacing, the length of the middle-lane section where two conflicting left-turn demands often compete for space. In addition, unlike previous researches, the way and the procedure the TWLTL operation is realized in the VISSIM S/W with its add-on application such as VISVAP is clearly stated and described in detail. According to the result of simulations for 10 volume scenarios, as expected, the higher the volume level is, the more delay the left-tuner experience. The Level Of Service (LOS) for most cases was in the range of C and D based on the non-signalized intersection LOS criteria. Furthermore, the TWLTL was found operable up to the volume level of 1,116 and 1,860 vph in heavy direction (equivalent of volume level 7) for 3-lane and 5-lane facility respectively, which covers significant portion of existing two to four-lane highway volumes in Korea.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.124-137
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• 2018

The main purpose of this study is to find the hotspots of crimes that occur frequently in the space and to derive the appropriate CCTV installation location. One of the characteristics of crime is clustered around past occurrence area, and these crimes are strongly correlated. It is also possible to find the cause of the clusters and the variables that affect the crime through the history of the crime. In addition to the traditional OLS model, spatial differential model including spatial autocorrelation and spatial error model were used to select the variables influencing the five major crime rate, the theft rate and the foreign resident rate. The variables affecting the Five major crimes were positive (+) sign for the welfare and the rate of the bar cluster rate, and negative (-) for the street density. The CCTV area occupies 46% of the hotspots based on the overlapping of the areas where the elderly people are crowded, the bar cluster, many multicultural families, and the areas with low density of street lamps. It turned out. Taking into account the current CCTV operation, the total number of new cases to cover the risk point was 89.

• Journal of Digital Contents Society
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• v.19 no.3
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• pp.505-512
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• 2018

Internet demand has increased rapidly, and Internet Protocol Version 4, the main Internet protocol, can not cope with various types of network demand in the future. Therefore, it is urgent to spread IPv6-based stable network to solve the shortage of Internet address resources. Due to the proliferation of IoT and the increase in mobile devices, efficient and optimal IPv6 routing design is indispensable. In this paper, we have studied about characteristics of IPv6, address system of IPv6, structure analysis and efficient routing technology among IPv6 terminals. Furthermore, experimental results on routing packet analysis and convergence time are presented in network - based IPv6 routing implementation environment. In addition, we show the results of the experiment analysis by dividing the implementation of IPv6 routing, operation test, and fail over performance into three kinds of routing protocol methods. As a result, this study can be applied to the introduction of IPv6 system, test bed environment construction, and network design.

• Journal of The Korean Association For Science Education
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• v.37 no.2
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• pp.263-271
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• 2017

Teacher reeducation is required to be comfortable with the 'Integrated science' subject as introduced in the 2015 revised curriculum. In this research, we designed in-service teacher training programs according to the types of secondary school science teacher's certificates, and developed ways to improve in-service science teachers' competencies. Through Delphi surveys with 22 science education experts, we investigated the features of the 2015 revised 'Integrated science' curriculum in light of its characteristics, purposes, contents system, contents, and so on, and explored teachers' competencies to teach the subject. Based on the analysis of the features of each type of secondary school science teachers' certification and required teacher competencies for teaching 'Integrated science', we developed three types of teacher training programs: in-service training courses for understanding the 2015 revised 'Integrated science' (Type A), in-service training courses for 'Integrated science' (Type B), and in-service teacher training certificate program for 'Integrated science' (Type C). For each teacher training program, we suggested the target of the training program in light of teacher certificates, operation systems, and ways to organize the program. In addition, we also suggested ways to improve 'Integrated science' teacher education programs for pre-service as well as in-service teachers, and examined ways to improve educational requirements for qualification in 'Integrated science' teaching based on the opinions of experts. Discussed in the conclusion are ways to design in-service teacher training programs for 'Integrated science' teaching and ways to improve 'Integrated science' teacher training.

• Korean Journal of Construction Engineering and Management
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• v.16 no.5
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• pp.54-64
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• 2015

The modular construction has several advantages such as high quality of product, safe work condition and short construction duration. The manufacturing planning of modular construction should consider time frame of manufacturing, transport and erection process with limited resources (e.g., modular units, transporter and workers). The manufacturing planning of multi modular construction project manages the modular construction's characteristics and diversity of projects, as a type of modular unit, modular unit quantities, and date for delivery. However, current modular manufacturing planning techniques are weak in dealing with resource interactions and each project requirement in multi modular construction project environments. Inefficient allocation of resources during multi modular construction project may cause delays and cost overruns to construction operation. In this circumstance, this research suggest a manufacturing planning model for schedule optimization of multi project of modular construction, using genetic algorithm as one of the powerful method for schedule optimization with multiple constrained resources. Comparing to the result of the existed schedule of case study, setting optimized scheduling for multi project decrease the total factory producing schedule. By using proposed optimization tool, efficient allocation of resource and saving project time is expected.