• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.42 no.4
• /
• pp.537-548
• /
• 2022

It is important to design the pavement thickness considering heavy-duty traffic loads, which can cause excessive stress and strain in the pavement. Port-rear roads and industrial roads have many problems due to early stress in pavement because these have a higher ratio of heavy loads than general roads such as national roads and expressways. Internationally, composite pavement has been widely applied in pavement designs in heavy-duty areas. Composite pavement is established as an economic pavement type that can increase the design life by nearly double compared to that of existing pavement while also decreasing maintenance and user costs. This study suggests a thickness design method for composite pavement using roller-compacted concrete as a base material to ensure long-term serviceability in heavy-duty areas such as port-rear roads and industrial roads. A three-dimensional finite element analysis was conducted to investigate the mechanical behavior and the long-term pavement performance ultimately to suggest a thickness design method that considers changes in the material properties of the roller-compacted concrete (RCC) base layer. In addition, this study presents a user-friendly catalog design method for RCC-base composite pavement considering the concept of linear damage accumulation for each container trailer depending on the season.

• Journal of the Society of Disaster Information
• /
• v.8 no.2
• /
• pp.119-137
• /
• 2012

In this study, the damages and condition of road pavement were analyzed using pavement management system (PMS) for the structural improvement. Problems of road pavement management were issued by in-depth interview with workers in charge of plant, construction and supervision. By surveying advanced road pavement management, the way how to improve road pavement management in Seoul was discussed. In conclusion, it is necessary to take measures against road heavy traffic and heavy rain in summer. It was found that the problem of early damages of road pavement due to uniform layout with analyzing life cycle cost (LCC). According to the results of survey, it was suggested to strength practical training and to control precisely the temperature of pavement in the process of production and construction.

• Journal of the KSME
• /
• v.36 no.9
• /
• pp.855-866
• /
• 1996

승요차 앞자축에 장착되어 회전하면서 동력을 전달하는 드라이브축은 운행중에 주로 비틀림하중을 받는다. 따라서 동 부품의 피로해석 및 설계를 위해서는 실제 운행중에 받는 서비스토크의 크기, 주파수 등에 관한 데이터가 필요하다. 차량에 탑재된 엔진의 토크와 회전수 등의 규격으로부터 드라이브축에 부가되는 최대 토크 값을 예측할 수 있으나, 자동차 운행주에는 승차인원, 도로조건, 운전자의 운전습관 등 여러가지 외적인 영향으로 인하여 서비스토크가 불규칙하게 변할 것으로 예상되므로 서비스토크를 정확히 예측하기는 어려운 실정이다. 또한, 최근의 자동차 구조부품에 대한 설계개념이 무한수명 설계에서 경량화 설계로 변화되고 있으며, 따라서 자동차 드라이브축도 실제 운용하중을 바탕으로 한 정확한 수명예측 및 강도설계가 요구되고 있다. 본 연구에서는 4륜구동형 승용차용 드라이브축에 대해 실제 운용하중에서의 피로수명을 예측하기 위해 1)텔리메트리를 이용하여 토크를 측정하고, 2) 일정진촉하중하에서의 드라이브축의 비틀림 피로시험을 수행하고, 3) 일정진폭하중하에서의 드라이브축의 비틀림 피로시험을 수행하고, 4) 축류 소재의 피로특성 데이터를 구성하여 5) 자체 개발한 프로그램으로 피로수명을 예측하고자 한다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.1
• /
• pp.57-63
• /
• 2007

The systematic method to construct equivalent static load from a given dynamic load is proposed in the present study. Previously reported works to construct equivalent static load were based on ad hoc methods. Due to improper selection of loading position, they may results in unreliable structural design. The present study proposes the employment of primary degrees of freedom for imposing the equivalent static loads. The degrees of freedom are selected by two-level condensation scheme with reliability and efficiency. In several numerical examples, the efficiency and reliability of the proposed scheme is verified by comparison displacement for equivalent static loading and dynamic loading at the critical time.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.20 no.5
• /
• pp.455-460
• /
• 1991

In order to identify hard distinct 12 fish species(shiba shrimp Metapenaeus joyneri, fleshy shrimp Penaeus orientalis, ridgetail prawn Palaemon carinicauda, yellow croaker Pseudosciaena manchurica, croaker Niber albiflora, Colichthyes fragilis, brown sole Limanda herzensteini, frog flounder Pleuronichthys cornutrs, Areliscus rhomaleus, stone flounder Kareius bicoloratus, harvest fish Pampus argenteus, flag fish Goniistius zonatus) by seeing with naked eye in Kunsan coastal area, sarcoplasmic protein in the supernatant was used for isoelectric focusing. For getting supernatant, fish muscle tissue was blended with two times deionized water and centrifuged (at $4^{\circ}C$, 12,000rpm for 15min). Isoelectric focusing of sarcoploasmic protein carried out on a LKB Multiphor II using polyacrylamide gel plate (2mm thickness, pH $3.5~10^{\circ}C$, pH 5~8 gradient, at $10^{\circ}C$ for 1.5, 3 hours). In case of uncertain protein pattern, pH gradient was modified to narrow pH gradiet, and excuted 2-D electrophoresis using conventional polyacrylamide gel electrophoresis. Most of fishes except yellow croaker and Collichthyes fragilis were distingushed by isoelectric focusing. The protein maps of 2-D electrophoresis for analyzing two protein bands at aimilar positions(pH 5, 6) between the two fish species showed the diffeences of the estimated molecular weights, 11,700(pH5.0) and 87,000(pH6.0)

• Journal of Gifted/Talented Education
• /
• v.20 no.3
• /
• pp.789-807
• /
• 2010

This study was carried out in order to explore possibility of artistic activity for strengthening creativity of the gifted children at home by analyzing influence of the gifted children's musical experience and interest level upon creativity. As a result of research, the gifted children's musical experience and interest level were distributed in the mid-lower rank as a whole. The mean in score of creativity was high. Among sub-spheres, originality, abstractness of titles, and resistance to premature closure were surveyed to be especially excellent. And the result of this study was indicated to be high in influence of musical experience and interest level upon creativity. Some conclusions and implications that were obtained through this study are as follows. First, to explore influence of musical experience as artistic activity upon creativity, first of all, the qualitative inspection needs to be given priority to musical activity itself, which is being experienced by the gifted children as the research subjects. Second, there is necessity of paying attention to the musical experience and interest level of the low gifted children. Third, for the gifted children prior to activation of art education, a clear reason why the art education is needed and the usefulness need to be presented.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.438-438
• /
• 2012

우리나라의 용수사용의 48%를 차지하고 있는 농업용수는 저수지와 양수장 보 등을 이용하여 농경지에 용수를 공급하고 있다. 이 중 농업용저수지는 18,000 여개에 이르고 있으며, 전국에 산재되어 하천의 중 상류부에서 농경지에 용수를 공급하는 역할을 수행하고 있다. 유역의 중상류부에 위치한 농업용저수지의 용량을 증대시키는 사업인 "농업용저수지 둑높이기사업"은 이 치수측면에서 농업지역 관개용수의 공급과 함께 하천유지용수의 공급이고, 더불어 재해측면에서 취약한 농업용저수지 보강을 목적으로 하고 있다. 둑높이기사업 이전의 저수지운영은 못자리용수가 들어가는 시기인 4월 중순부터 5월 중순경의 모내기 기간 동안에 가장 공급량이 많게 하면서 관개용수의 원활한 공급을 위한 운영을 해 왔으나, 둑높임저수지의 경우는 영농기간이 종료되는 시기인 9월 중하순을 기준으로 하천유지용수 공급을 위한 저수지 운영이 필요하게 되었다. 농업용저수지는 관개기 시점의 저수량이 이수안전을 위한 중요한 요인이며 하천유지용수의 공급을 감안할 경우 관개기 종료 시점의 저수량 도 중요한 의사결정 요인이 된다. 이 에 본 연구에서는 용수목적별 공급을 위한 둑높임저수지 운영곡선을 계획하는데 있다. 운영곡선의 기본적인 의사결정기준은 영농시점인 4월의 저수지 수위와 영농 종료시점인 10월의 수위이다. 둑높임저수지의 운영은 영농이 종료되는 시점인 10월을 기준으로 저수용량을 최대한 확보해야 하며, 다음연도 관개시작일인 4월을 기준으로 농업용수 수위가 확보 될 수 있도록 저수위조절이 필요하다. 따라서 본 연구에서는 저수지 관리자가 상기와 같은 조건을 만족하면서 해당 저수지를 운영하도록 하기 위해 비관개기동안에 하천유지용수를 최대한 공급하면서도 다음 4월에 농업용수 필요수량을 충족할 수 있는 수위를 가질 수 있도록 운영곡선 가이드라인을 수립하였다. 본 연구를 통해 작성된 운영곡선을 프로그램화하여 모의조작 할수 있는 기반을 만든다면 농업용수의 원활한 공급을 바탕으로 하류하천의 하천유지용수 공급을 갈수기에 최대한 공급할 수 있으며 향후 예상되는 기상조건에 따른 주단위, 월단위의 용수공급계획수립이 가능할 것으로 기대된다.

• Journal of The Korean Association For Science Education
• /
• v.31 no.6
• /
• pp.836-847
• /
• 2011

This study investigated the effects of taking elective science courses in high school on studying science at the university level. The research methods undertaken for this study included surveys of college students in science areas. For physics and biology major students, no significant differences in achievement in the basic courses at the university level were found between the groups that took only Science I courses and the group took Science I and II courses. For chemistry major students, achievement for the group that took Chemistry I and II courses was significantly higher in the basic courses, while no significant differences between the two groups was found in the advanced courses. The perceptions of college students regarding the effects of their science learning experience in high school on learning science at the university level were investigated. All the college students perceived that whether or not they took Science II courses in high school, it did not affect their learning in basic science courses in college. They also perceived that students were able to overcome difficulties by making extra effort even if they did not take Science II courses in high school.

• Journal of Nutrition and Health
• /
• v.52 no.2
• /
• pp.194-205
• /
• 2019

Purpose: The aim of this study was to evaluate the dietary behaviors of preschoolers in Daejeon using the Nutrition Quotient for Preschoolers (NQ-P). Methods: The study subjects were recruited from child-care centers and kindergartens located in Daedeok-gu, Daejeon between August and September 2018. A total of 411 preschoolers aged 3 ~ 6 years were included in the data analyses. A questionnaire of NQ-P, which consisted of 14 checklist items on dietary behaviors, was completed by the parents or guardians of the study subjects. The NQ-P scores and its three factors, including "balance", "moderation", and "environment" factors, were calculated according to sex, age, and weight status. Differences in the NQ-P scores and their factors according to sex, age, and weight status were tested using a student's t-test. Results: The mean NQ-P score of the total subjects was $58.5{\pm}9.2$, which was within the medium-low grade. The NQ-P score was $58.5{\pm}9.4$ in boys and $58.6{\pm}9.0$ in girls (p = 0.955). The NQ-P score was similar regardless of the age groups ($57.8{\pm}9.4$ in 3 ~ 4 years vs. $59.2{\pm}9.0$ in 5 ~ 6 years, p = 0.124), whereas subjects aged 5 ~ 6 years showed a significantly higher scores of environment factors than those aged 3 ~ 4 years ($67.9{\pm}16.8$ vs. $61.7{\pm}17.3$). The mean score of the moderation factor was lower in the overweight/obese children compared to the non-overweight/obese children ($46.6{\pm}13.3$ vs. $51.0{\pm}16.2$, p = 0.012). Compared to children aged 3 ~ 4 years, children aged 5 ~ 6 years had higher intakes of vegetable dishes and processed meat. The overweight/obese group showed a higher consumption of processed beverages than the non-overweight/obese group. Conclusion: The current study indicates that the dietary behaviors of preschoolers residing in Daejeon need to be improved. These findings suggest that nutrition education or health interventions targeting young children is necessary for improving their nutritional health status.

• Computational Structural Engineering
• /
• v.7 no.3
• /
• pp.95-103
• /
• 1994

The safety related components in the nuclear power plant should be designed to withstand the seismic load. Among these components the integrity of reactor internals under earthquake load is important in stand points of safety and economics, because these are classified to Seismic Class I components. So far the modelling methods of reactor internals have been investigated by many authors. In this paper, the dynamic behaviour of reactor internals of Yong Gwang 1&2 nuclear power plants under SSE(Safe Shutdown Earthquake) load is analyzed by using of the simpled Global Beam Model. For this, as a first step, the characteristic analysis of reactor internal components are performed by using of the finite element code ANSYS. And the Global Beam Model for reactor internals which includes beam elements, nonlinear impact springs which have gaps in upper and lower positions, and hydrodynamical couplings which simulate the fluid-filled cylinders of reactor vessel and core barrel structures is established. And for the exciting external force the response spectrum which is applied to reactor support is converted to the time history input. With this excitation and the model the dynamic behaviour of reactor internals is obtained. As the results, the structural integrity of reactor internal components under seismic excitation is verified and the input for the detailed duel assembly series model could be obtained. And the simplicity and effectiveness of Global Beam Model and the economics of the explicit Runge-Kutta-Gills algorithm in impact problem of high frequency interface components are confirmed.