• Journal of Korean Society of Transportation
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• v.20 no.4
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• pp.135-150
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• 2002

The basic assumption of analytical Dynamic Traffic Assignment models is that traffic demand and network conditions are known as a priori and unchanging during the whole planning horizon. This assumption may not be realistic in the practical traffic situation because traffic demand and network conditions nay vary from time to time. The rolling horizon implementation recognizes a fact : The Prediction of origin-destination(OD) matrices and network conditions is usually more accurate in a short period of time, while further into the whole horizon there exists a substantial uncertainty. In the rolling horizon implementation, therefore, rather than assuming time-dependent OD matrices and network conditions are known at the beginning of the horizon, it is assumed that the deterministic information of OD and traffic conditions for a short period are possessed, whereas information beyond this short period will not be available until the time rolls forward. This paper introduces rolling horizon implementation to enable a multi-class analytical DTA model to respond operationally to dynamic variations of both traffic demand and network conditions. In the paper, implementation procedure is discussed in detail, and practical solutions for some raised issues of 1) unfinished trips and 2) rerouting strategy of these trips, are proposed. Computational examples and results are presented and analyzed.

• Safety and Health at Work
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• v.11 no.1
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• pp.26-32
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• 2020

Background: Hong Kong's construction industry currently faces a manpower crisis. Blue-collar workers are a disadvantaged group and suffer higher levels of chronic diseases, for example, cancer, than the wider population. Cancer risk factors are likely to cluster together. We documented prevalence of cancer-associated lifestyle risk behaviors and their correlates among Hong Kong construction workers. Methods: Data were collected from workers at 37 railway-related construction worksites throughout Hong Kong during May 2014. Tobacco use, alcohol consumption, unbalanced nutrition intake, and physical inactivity were included in the analysis. Latent class analysis and multivariable logistic regression were performed to identify the patterns of risk behaviors related to cancer, as well as their impact factors among construction workers in Hong Kong. Results: Overall, 1,443 workers participated. Latent class analysis identified four different behavioral classes in the sample. Fully adjusted multiple logistic regression identified age, gender, years of Hong Kong residency, ethnicity, educational level, and living status differentiated behavioral classes. Conclusion: High levels of lifestyle-related cancer-risk behaviors were found in most of the Hong Kong construction workers studied. The present study contributes to understanding how cancer-related lifestyle risk behaviors cluster among construction workers and relative impact factors of risk behaviors. It is essential to tailor health behavior interventions focused on multiple risk behaviors among different groups for further enlarging the effects on cancer prevention.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.554-561
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• 2017

IoT (Internet of Things) devices are often located in environments where indoor or underground, signals are difficult to reach. In addition, the transmission power is low, the base station should be designed to be able to receive signals even at low reception sensitivity. For this reason, a device having a poor channel condition can be transmitted at a low data rate using a low coding rate or repetition. When the coverage class is divided according to the channel condition and the data rate, the packet length may vary from one coverage class to another, and the performance of the slotted aloha random access may be degraded. We will focus on two methods of using shared-resource and seperate resources among multiple slotted aloha methods. In particular, when devices with different coverage classes use shared resources, performance of a device with a bad channel condition may deteriorate. Conversely, when using separate resources for each coverage class, there is a problem that congestion may occur which increases the number of devices that perform random access to one resource area. In this paper, we propose some methods to overcome this problem. This study is mainly focused on MTC devices, and is considered to be a high possibility of future development.

• Journal of Science Education
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• v.37 no.3
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• pp.458-475
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• 2013

According to instruction of standard-based assessment system, teachers with higher level of competence in student assessment are required. The purpose of this study is to offer the basic data to enhance pre-service physics teachers' competency in student assessment. 17 pre-service physics teachers, who are sophomore in department of physics education, participated in the study for a whole semester. To do this, we gave the assignment of multiple choice question construction in physics conceptest for formative assessment to pre-service teachers and observed review questions constructed by them. We also analyzed multiple choice questions of 17 pre-service teachers. They had 5 classes for the review process of the question and improved their questions through it. 16 of 17 pre-service teachers completed test design. Our results show that pre-service teachers had a little low competence in test design for classroom assessment. In addition to, constructing and revising questions, almost of them didn't have various perspectives and didn't consider to get information about the pre-conceptions of students. These findings indicate that they have difficulties with constructing multiple choice question and more specific plan needs to enhance the overall student-assessment competency levels of pre-service teachers for successful settlement of the standard-based assessment system.

• Korean Security Journal
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• no.41
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• pp.97-121
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• 2014

A survey on effects of the participation style of martial art classes in students majoring in guard on both their major satisfaction and adapt to school lie was performed for 285 male and female students. The survey was carried out using a questionnaire on the participation style of martial art classes, degree of major satisfaction, and adapt to school life. Based on the survey, a correlation analysis was implemented to investigate effects of the martial art class participation styles on both major satisfaction and adapt to school life. Then, a multiple regression analysis was also performed. As a result, the sub-elements of the martial art class participation styles, such as the cooperative and participation styles, significantly affect the general satisfaction, class satisfaction, relationship satisfaction, and cognitive satisfaction in the major satisfaction. In the martial art class participation styles, the sub-elements, such as the cooperative, competitive, and participation styles, significantly affect the class, sociality, and adapt to school environments in adapt to school life. The sub-element of the major satisfaction, such as the general satisfaction, significantly affects the adaptations in class, sociality, and school environments in adapt to school life.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.165-172
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• 2015

The class of Dynamic Positioning System is divided in 3 classes depending on its redundancy and reliability according to IMO and classification society. There are 3 DP classes such as DP Class 1, 2 and 3 according to IMO MSC/Circ. 645. Higher DP class vessel has higher reliability, since redundancy concept is applied to the DP vessel depending on its DP class and can operate more safely. There are not enough information about DP class notation, which are needed when a company builds a new or buys second hand DP vessel or modifies DP classes, even the Korean shipyard is building a lot of DP vessels now. Also, the practical case of DP vessel modification, which had been done in Korea, to meet DP notation of IMO and classification society, will be helpful for DP vessel modification and sales industry development in Korea as a new business. As such this research identified what kind of requirements need to be taken into account to be from DP class 1 to DP class 2. The real DP class modification case is used to identify the requirements of DP class upgrade. Through the FMEA the redundancy concept on power system, thruster system and DP control system need to apply for DP class upgrade. The power system have to keep its DP function even if just a single fault happens on the generator or switchboard. Also, the PMS is required to monitor and control power system. Ship's Surge, Sway and Yaw movements can be controlled by the remaining thruster system after a single thruster fails. Lastly, multiple installation of PRS, sensors and DP control system are required to keep DP ability after a single fault on the DP control systems.

• Korean Journal of Human Ecology
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• v.7 no.3
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• pp.35-48
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• 2004

In this study, by determining lower limb movements which cause significant changes in body surface lines, body parts with the greatest maximum expansion and contraction rate respectively were illustrated in descending order. Using unmarried female university students aged 18 - 24 as subjects, a total of 32 body surface categories (15 body surface lines and 17 body surface segment lines) were measured in one static and 9 movement poses. In particular, expansion and contraction levels and rates were measured and used in the analysis. The analysis first involved the calculation of the average measurement per body part in body surface line in static pose as well as of the average expansion and contraction levels and rates in 9 lower limb movements. Two-way MANOVA and multiple comparison analysis (Tukey) were conducted on movements and individual somatotypes regarding measurement per body part and expansion and contraction rates. Movements which cause measurements of body surface lines differed significantly in body surface line in static pose versus in movement were then identified. Among average expansion and contraction rates in such movements, maximum average expansion and contraction levels, maximum average expansion and contraction rate, and classes of expansion and contraction rate were determined per body part. The results of this study are as follows. First, 5 lower limb movements; F2, F5, F6, F7, F8, which caused significant changes in body surface lines were determined and illustrated in table 4. Second, the levels, rates, and classes of expansion and contraction rate per body part are illustrated in Tables 5 and 6. Body parts with the greatest maximum expansion rate were, in descending order: upper segment of center back leg line, upper segment of inner leg line, middle segment of center front leg line, posterior crotch length, anterior knee girth, anterior thigh girth, center back leg line, girth at crotch height, anterior midway thigh girth, hip girth, anterior crotch length, knee girth, waist girth, inner leg line, thigh girth, and crotch length. Those with the greatest maximum contraction rate were, in descending order: anterior crotch length, upper segment of center front leg line, lower segment of center back leg line, center front leg line, and posterior thigh girth. The maximum expansion rates and maximum contraction rates, which ranged from 2.05 to $35.95\%$ and from -0.20 to $-30.16\%$ respectively, were classified per body part into 4 ABCD classes. The body part with maximum expansion was the upper segment of the center back leg line at vertical body surface line, expanding by $35.95\%$ or 16.03cm in F5 flexion movement. In contrast, the body part with maximum contraction was the anterior crotch length at vertical body surface line, contracting by $-30.16\%$ or -10.54cm in F5 flexion movement. Both, however, were the body parts to expand or contract the most among all horizontal and vertical body surface lines.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.348-356
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• 2019

The purpose of this study was to identify latent classes in changes of mothers' daily life stress over six years from multicultural families and to test its relationship with early adolescents' perceived neglecting parental attitudes and their academic achievements. For achieving this purpose, as the study sample 1,039 students were gathered from the 4th grade of elementary school to 3rd grade of middle school, using Growth Mixture Modeling, Multiple Group Analysis, and One-way ANOVA. The results were as follows. First, latent classes of mothers' daily life stress were categorized into three types: high-stable trajectory, moderate-changing trajectory, and low-changing trajectory. Second, these three types showed different characteristics in early adolescents' perceived neglecting parental attitudes and academic achievements. Third, early adolescents' perceived neglecting parental attitude were not significant determinants of the latent classes while academic achievements were. The findings of this study may provide a framework for understanding the relationships among mothers' daily life stress and early adolescents' perceived neglecting parental attitudes and their academic achievements in multicultural families and practical implications for providing social support to overcome daily life stress of mothers in multicultural families.

• Journal of Science Education
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• v.37 no.2
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• pp.405-415
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• 2013

The purpose of this study was to investigate high school students in natural science track and engineering major university students' perceptions about the writing and composition education. A total of 318 high school students in natural science track from two high schools in a metropolitan area and 447 university students majoring in engineering from three universities participated in the survey and asked to response their perceived status and needs of writing education for science-engineering track. The survey instrument, developed by Lee et al.(2009), was used for this study. The data was analyzed through the SPSS 18.0 program for Windows for Multiple Response Frequency Analysis, Descriptive Statistics, Independent Samples t-test, and One-way Analysis of Variance. The results indicated that high school students relatively perceived that writing education was less necessary compared to university students. In addition, high school students found writing less difficult than university students do. In related to studying their experience with writing and composition education, almost no high school students have taken writing classes and university students have taken an average of one class. Most university students who took writing classes took basic writing classes that were not programmed for students in Science and Engineering. In the basic survey to revitalize writing and composition education for Science and Engineering students in different majors, the level of writing and composition education required by students in each major was different. Writing was considered most necessary for students majoring in Chemical Engineering, followed by students majoring in Mechanical Engineering and Electronic Engineering. The study of writing and composition education for high school and college should extend to studies on teachers or professors who teach writing, studies on contents and methods of writing education, and studies on the development of writing programs for different majors in university.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.38-47
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• 2019

The purpose of this study was to identify latent classes in executive function difficulty of first graders depends on evaluations from their mother and teacher and to investigate how its related with their school adaption and academic performance in second grade. Based on the model of the latent profile analysis, the 8th and 9th wave data from Korean Children and Youth Panel Survey were analyzed. The results of this study were as following. First, results showed that there were three types of latent classes in the executive function difficulty depend on evaluations from their mother and teacher: 'low executive function,' 'students who were highly evaluated by mother,' and 'students who were highly evaluated by teacher.' Second, students' executive function difficulty had a direct effect on the students' school adaption and academic performance in their second year of school. Especially students who were evaluated as having the lowest executive function difficulty showed significant higher means than students who were evaluated higher by mother and teacher. This study emphasized the importance of multiple evaluation in students' executive function difficulty to provide an educational intervention.