• 한국정밀공학회지
• /
• 제29권2호
• /
• pp.147-155
• /
• 2012

Wind power, which is one of the promising renewable energies, has shown the high growth rate of 35 % of the annual average in the recent 5 years and also windmill related equipment market has been fast-growing. Yaw & Pitch bearing are the key parts of windmill and are machined by huge vertical lathe which is monopolized by the advanced countries. The purpose of this study is to develop the multi-tasking vertical lathe for 5 MW grade windmill bearings, which might be mass produced 3 or 5 years later. In this study, the structure of the crossrail and rotary table, which are the key units of the huge multi-tasking vertical lathe, were optimized through the finite element analysis. Also the basic performance of the rotary table has been evaluated.

• 한국수학교육학회지시리즈A:수학교육
• /
• 제49권3호
• /
• pp.353-373
• /
• 2010

This research was to help slow learners to be motivated and to make their outcome productive, using GSP based on the mathematization theory for learning mathematics, as a way of encouraging the learner-centered approach. With 2 of the second graders in a high school, who had not yet understood trigonometric functions in their first grade period, 7 units of lesson plans were designed for the research. The results showed that first, understanding real life contexts and analyzing properties by observation, and experiment using GSP, to build the concept of trigonometric functions could be a foothold on which learner's organization and outcome from a horizontal mathematization led to vertical mathematization. Despite the delay during the level-up-stage for a while, the learners could attain the vertical mathematization stage and moreover the applicative mathematization through effective use of GSP and the interaction between the learners or a teacher and the learners. Second, using GSP was a vertical tool of connecting horizontal mathematization with vertical mathematization in forming the concept of trigonometric functions and its meaning could be understood by their verbalizing and presenting the outcomes through their active performance. Using GSP is helpful for slow learners to overcome learning difficulties, based on the instructional materials designed by Realistic Mathematics Education.

• 한국콘텐츠학회논문지
• /
• 제22권6호
• /
• pp.116-124
• /
• 2022

본 연구의 목적은 초등학교 5, 6학년 영어 교과서에 수록된 읽기 지문의 이독성을 분석하여 학년 간 수직적 연계성과 출판사 간 수평적 연계성을 살펴보는 것이다. 이를 위해 10종의 교과서에 수록된 읽기 지문을 코퍼스로 구축한 후, Coh-Metrix를 통해 각 교과서에 수록된 읽기 지문의 이독성을 분석하였다. 또한 일원배치 분산분석을 통해 산출된 이독성에 학년 간, 출판사 간에 통계적으로 유의한 수준의 차이가 있는지 살펴보았다. 이를 통해 얻어진 결과는 다음과 같다. 첫째, 동일 학년 내 읽기 지문의 출판사간 난이도 차이를 분석하여 수평적 연계성을 살펴본 결과 RDL2 지수에서 5학년 교과서간에 유의한 차이가 있었다. 둘째, 출판사 내에서의 학년 간 수직적 연계성을 분석한 결과 FRE와 FKGL 기준으로 교과서 A의 난이도가 5학년에 비해 6학년에서 높았으며, 이는 통계적으로 유의한 수준의 차이였다. 반면 RDL2를 기준으로 했을 경우 교과서 B의 난이도가 5학년에 비해 6학년에서 더 낮아지는 결과를 보았다. 이러한 결과는 FRE와 FKGL은 문장 길이와 단어 길이 중심으로 이독성을 산출하는 반면, RDL2는 내용어 중복, 단어 빈도 수, 문장의 통사적 유사성 등을 기초로 하고 있기 때문으로 보인다.

• 한국의류학회지
• /
• 제33권2호
• /
• pp.319-330
• /
• 2009

The contents of clothing and textiles area of elementary home economics textbooks from 1948 to 1955 were investigated. Home economics of elementary school education in those days corresponds to practice acts of elementary school education in present. Practical acts has the all-around concepts of the agriculture, industry and home economics Also the knowledge or skill for actual life are teamed. Practical acts education was started from lessons of sewing for women under title of 'jaebong'. It can be said that practical acts education was started from clothing and textiles area. The home economics elementary textbooks of the year 1948 were composed of 21 units for 5th grade and 22 units for 6th grade. The textbook for 5th grade of 1953 was composed of 19 units, and one for 6th grade of 1955 was composed of 18 units. The clothing and textiles area accounts for 38.6% in 5th grade textbook, for 32% in 6th grade textbook of 1948 and for 31% in 5th grade of 1953 and 6th grade textbooks of 1955. The textbook contents of clothing and textiles area were classified into five fields of sewing, knitting. patching, embroidering and care. In 1948, textbooks were placed a great deal of weight on sewing field education as 7 units of 15 units. The 7 units for sewing fields have suitable connection to develop. But, in the case of knitting, patching or care, just groundwork of each field was included for application to actual life without vertical connection. The contents of textbooks for clothing and textiles area in 1953 and 1955 were much alike with those in 1948.

• 한국도로학회논문집
• /
• 제10권4호
• /
• pp.171-180
• /
• 2008

본 연구는 지반위에 놓여진 콘크리트 슬래브가 온도하중을 받아서 컬링할 때의 거동을 실내 실험을 통해 분석하고 슬래브를 지지하고 있는 하부층의 구성이 슬래브의 컬링 거동에 어떠한 영향을 미치는지를 분석하기 위하여 수행되었다. 실험을 위해 콘크리트슬래브를 제작하고 온도측정센서를 장착하였으며 인위로 온도하중을 가하며 슬래브의 여러 위치에서 변위의 변화를 측정하였다. 하부층은 두 가지의 관점을 고려하여 구성하였으며, 첫째는 단일 하부층을 이용하여 재료와 두께를 달리하여 지지력을 다르게 하는 경우이며, 둘째는 하부층을 복층으로 구성하되 복합지지력은 일정하나 슬래브와 직접 접촉하는 상위하부층의 재료성질을 다르게 하는 경우이다. 실험결과 시간에 따른 슬래브의 수직 변위 변화는 온도구배의 변화와 거의 일치하는 양상을 보였으며 컬링 거동의 특성을 컬업 구간과 컬다운 구간으로 구분하여 분석하였다. 하부층의 지지력은 커질수록 슬래브의 중앙과 코너의 수직 변위 차이는 감소하게 되며 최상위 하부충의 재료 성질이 컬링 거동에 영향을 미치는 것을 알 수 있었다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2009년도 춘계학술대회 논문집
• /
• pp.84-90
• /
• 2009

The gravel ballast in the ballasted track has the function to not only transfer/scatter the train loads to subgrade through rail and sleeper but also elastically support the train loads. Because track irregularities results inevitably from the repetitive train loads, the track maintenance should be undertaken for correcting them. By analyzing the track maintenance history in the Gyeongbu high speed railway, this study tries to choose the local two spots in the railway in which the repair frequencies are maximum and relative small; to analyze their dynamic characteristics as well as grade; and to compare them with maintenance history. As the dynamic characteristics of track, the vertical displacement and vibrating acceleration of sleeper as well as acceleration of ballast are measured/analyzed. Furthermore, by collecting soil and gravel on the reinforced roadbed and undertaking ballast screening test, the size distributions are compared with grade distribution standards of high speed railway.

• 한국의류학회지
• /
• 제24권6호
• /
• pp.850-860
• /
• 2000

The purposes of this study was to provide the fundamental data for children's wear standardizing sizes of ready-made clothes by analyzing the elementary school girls’somatotype. The subjects for anthropometic measurements were 434 elementary school girls’by age groups < ‘(1st age(1ㆍ2 grade)’,‘2nd age(3ㆍ4 grade)’, and 3rd(5ㆍ6 grade)’ > living in Pusan. According to the analysis of upper bodies by the age groups 1. According to the analysis to draw somatometric factors by the age groups, sevenㆍseven and six actors in 1st . End and 3rd age groups are obtained from measurements of upper body. 2. The 1st & 2nd age groups: As the result of factor analysis for the factor, the first and second factors which explain more than 70% of the whole variance represent“horizontal size”and“vertical size”, which characterize more aspects of the body shape of girls at elementary school ages. 3. The 3rd age groups: As the result of factor analysis for the factor, 6 factor which explain 74.39% of variance were extracted form anthropometic data. The first factor represented the items of circumference, breadth and depth related to“sectional size the front length of the upper body”, The second factor described the items of "heights & the back length of the upper body”.

• Advances in concrete construction
• /
• 제10권6호
• /
• pp.547-557
• /
• 2020

This paper presents one of the demonstration projects undertaken during the FP7 EU-funded Anagennisi project (Innovative reuse of all tyre components in concrete-2014-2017) on a full-scale (30 m×40 m, thickness: 0.2 m) Steel Fibre Reinforced Concrete (SFRC) slab-on-grade using a blend of manufactured steel fibres (MSF) and Recycled Tyre Steel Fibres (RTSF). The aim of the project was to assess the use of RTSF in everyday construction practice. The Anagennisi partners, Dulex Ltd in collaboration with Gradmont-Gradacac Ltd and University of Zagreb, designed, cast and monitored the long-term shrinkage deformations of the indoor slab-on-grade slab at Gradmont's precast concrete factory in Gradacac, Bosnia and Herzegovina. A hybrid RTSF mix (20 kg/㎥ of MSF+10 kg/㎥ of RTSF) was used to comply with the design criteria which included a maximum load capacity of 20 kN/㎡. The slab was monitored for one year using surveying equipment and visual inspection of cracks. During the monitoring period, the slab exhibited reasonable deformations (a maximum displacement of 3.3 mm for both, horizontal and vertical displacements) whilst after five years in use, the owners did not report any issues and were satisfied with the construction methodology and materials used. This work confirms that RSTF is a viable and sustainable solution for slab-on-grade applications.

• Nuclear Engineering and Technology
• /
• 제55권11호
• /
• pp.3973-3982
• /
• 2023

As for two-phase flow in rectangular channels, the flow regimes especially like churn-turbulent and annular flow are significant for the physical problem like Countercurrent Flow Limitation (CCFL). In this study, the rectangular channels with cross-sections of 4 × 66 mm, 6 × 66 mm, 8 × 66 mm are adopted to investigate the flow regimes of air-water vertical upward two phase flow under adiabatic condition. The gas and liquid superficial velocities are 0 ≤ j_g ≤ 20m/s and 0.25 ≤ j_f ≤ 3m/s respectively which covering bubbly to annular flow. The flow regimes are identified by random forest algorithm and the flow regime maps are obtained. As the results, the transitional void fraction from slug to churn turbulent flow fluctuate from 0.47 to 0.58 which is significantly affected by the dimensional size of channel and flow rate. Besides, the void fraction at transitional points from churn-turbulent (slug) to annular flow are 0.66-0.67, which are independent with the gap size. Furthermore, a new criteria of slug to churn-turbulent flow is established in this study. In addition, by introducing the interfacial force model, the criteria of churn-turbulent (slug) flow to annular flow is verified.

• 대한토목학회논문집
• /
• 제35권1호
• /
• pp.187-192
• /
• 2015

도시부 교차로의 설계는 지방부 교차로와 근본적으로 달라야하나, 현행 도시부 교차로 설계는 지방부 교차로 설계기준을 준용하고 있다. 이에 국내외 교차로 종단경사 관련기준 문헌고찰, 현장조사 및 비교분석 등의 연구를 통해 향후 도시부에 적용할 적정 교차로 종단경사를 제시하였다. 본 연구는 도시부 및 지방부 교차로의 차이점을 비교 분석하고, 국내외 교차로 종단경사 설계기준을 검토한 후 적정 설계기준(안)을 도출하였다. 도출된 설계기준(안)의 검증을 위해 현장조사를 시행하고 통계분석을 시행하여 설계기준을 정립하였다. 여러 지침들을 비교하여 분석한 결과 도시부 교차로 종단경사 기준은 2.5~3% 정도가 적절할 것으로 판단되고, 부득이한 경우 5%정도가 적정경사인 것으로 판단되었다. 이러한 결과를 검증하기 위해 현장조사를 시행한 결과 0.0부터 8.6까지 다양한 종단경사 데이터를 확보하였다. 통계검증을 위한 사고데이터를 추가로 수집하여 SPSS를 활용한 상관관계 분석을 시행하였다. 95% 유의수준으로 분석한 결과 정면충돌사고율과 차대차추돌사고율이 종단경사와 상관관계가 있는 것으로 나타났다. 따라서 교차로 사고건수를 줄이기 위해 해당 변수들의 영향을 최소화 하기위한 노력을 하여야 하고, 그러한 노력의 일환으로 적정 교차로 종단경사를 적용한 설계가 이루어져야 함을 확인 할 수 있었다. 따라서 도시부 교차로의 종단경사는 1~3%의 적정수준을 유지할 필요가 있고, 부득이한 경우에도 3~5%를 넘지 않도록 설계시 주의를 기울여야 한다.