• Wind and Structures
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• 제8권4호
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• pp.295-307
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• 2005

The paper describes the work of the IAWE Working Group WBG - Reliability and Code Level, one of the International Codification Working Groups set up at ICWE10 in Copenhagen. The following topics are covered: sources of uncertainties in the design wind load, appropriate design target values for the exceedance probability of the design wind load for different structural classes with different consequences of a failure, yearly exceedance probability of the design wind speed and specification of the design aerodynamic coefficient for different design purposes. The recommendations from the working group are summarized at the end of the paper.

• 대한안전경영과학회지
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• 제12권2호
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• pp.55-64
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• 2010

This study tried to focus on nontraditional job that has not been studied in terms of the subjects associated with MSDs(Musculoskeletal Disorders). Specifically, dental procedure was the job to be analyzed in this study. An alternative method as well as a traditional method for viewing teeth while performing simulated dental procedures. Four graduated students did both methods(direct view and indirect view) as the subjects in this study. The method based on indirect view used a video camera and monitor to view the teeth. The experiment was conducted five times for each subject. The major findings in this study were as follows; 1) Job speed was increased with the repetitions for both methods, 2) Difference of Neck flexion between direct and indirect methods was statistically siginificant(Neck flexion for indirect method was dramatically decreased), 3) Difference of job speed between direct and indirect methods was statistically significant(Job speed for direct method was faster than that of indirect method), 4) Difference of error rate between direct and indirect methods was statistically significant(error rate for direct method was lower than that of indirect method), 5) Even though indirect method did not provide better performance in terms of job speed and error rate yet, it seemed to need a trade-off between two methods in the future since indirect method provided better working postures than that of direct method.

• 한국정밀공학회지
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• 제31권1호
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• pp.67-73
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• 2014

A reliability evaluation or prediction can be defined as MTBF which stands for mean time between failures (Exclusively for repairable failures). Spindle system has huge effect on performance of machine tools and working quality as well as is required of high reliability. Especially, it takes great importance in producing automobiles which includes a large number of working processes. However, it is unusually difficult to predict reliability because there are lack of data and research about reliability of spindle system. Standards and methods of examinations for reliability evaluation of machine tools are scarce at local and abroad as well. Therefore, this research is meant to improve the reliability of spindle system before mass produced with developing standards of reliability and methods of examinations through FMEA to assess reliability of spindle system in prototype stages of developing high speed spindle system of machining center.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.478-487
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• 1996

A " plucking rolls device" was developed in this study to improve the quality of harvested tea leaves. In this report, the outline of the system and the results of performance experiments in our laboratory are discussed. Tow kinds of performance experiments were carried out. The first experiment checked harvesting accuracy by using a plucking unit that was developed for harvesting machine installation. The second experiment was a harvesting experiment which utilized a fron bar in order to prevent cutting of the tea buds which had been a problem in precious experiments . As a results of the first experiments , it was confirmed that selective harvesting obtained high quality tea leaves. but a cutting problem that, when the harvesting seed was faster than the working speed, which was non-selective harvesting , was also seen. In the second experiment, the cutting rate decreased to a maximum of 50% level, when tea buds most bent ahead by the front bar. The effect was seen that cutt ng problem was alleviated from this.

• 인지과학
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• 제23권4호
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• pp.487-515
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• 2012

본 연구의 목적은 다양한 방식으로 개개인의 인지능력을 측정하고 문단 이해 능력을 살펴보는 것을 통해 문단이해에 영향을 미치는 인지정보처리 기제를 살펴보는 것이다. 이를 위하여 본 연구에서는 어휘판단 과제와 형태비교 과제를 사용하여 하위 인지능력을 측정하였고 숫자폭 과제, 작업폭 과제와 읽기폭 과제를 통하여 작업기억의 개인차를 측정하였다. 또한 논리적으로 유효한 추론과 유효하지 않은 추론의 처리 속도와 정확도를 살펴보는 것을 통해 고차 인지능력을 측정하였다. 문단이해 능력을 측정하기 위해서는 목표 문장 앞에 원인 문장이 있는 경우와 그렇지 않은 경우에 실험참여자들의 문장의 읽기 속도와 정확도를 측정하였다. 구조 모형을 통해 문단이해에 영향을 미치는 요인들을 살펴본 결과 하위 인지처리의 속도는 고차 인지처리의 속도와 상관이 있고 하위 인지처리의 정확도는 고차인지 처리의 정확도와 상관이 있었으나 고차 인지처리와 하위 인지처리에서 모두 속도와 정확도간의 상관은 나타나지 않았다. 또한 작업기억은 고차 인지처리 및 하위 인지처리의 정확도와는 상관이 있었으나 인지처리의 속도와는 상관이 없었다. 보다 중요하게 문단이해의 속도에는 하위 인지처리의 속도만이 영향을 미쳤지만 문단이해의 정확도에는 작업기억과 고차인지처리 기제가 영향을 미치는 것으로 나타났다. 문단이해의 속도는 문단이해의 정확도에 영향을 미치지 않았다.

• Journal of Biosystems Engineering
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• 제43권3호
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• pp.161-172
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• 2018

Purpose: During tillage operations, the selection of a working machine (tool) depends on the soil conditions as well as the type of tillage operation to be performed. The goal of this research was to ascertain the effects of varying working machine parameters of a compact disc harrow on tillage operations under various soil moisture content (SMC) conditions. Methods: The working machine parameters were the disc spacing and machine speed. The tillage parameters under investigation were the soil inversion ratio (SIR), tillage cutting depth (TCD), and soil clod breakage ratio (SCB). To determine the SIR, the areas of the white regions before and after tillage were obtained. The ratio of the difference of the areas of the white regions before and after tillage to the area of the white regions before tillage was considered as the SIR. The SCB was obtained as the ratio of the weight of soil clods after sieving with a mesh size of <0.02 m to the total weight of the soil clods before sieving. The soil TCD was measured using a tape measure at random points after the tillage operation. The resulting data were statistically analyzed in a one-way analysis of variance. Results: The highest soil inversion was achieved when the machine speed was 0.2 m/s with the disc spaced at 0.2 m in the 16.5% SMC. At a 0.4-m/s machine speed and 0.3-m disc spacing the highest soil breakage was achieved in the 26.5% SMC. The highest TCD was achieved at a 0.2-m/s machine speed and 0.2-m disc spacing in the 16.5% SMC. Conclusions: It was concluded that varying the working machine parameters, such as the disc spacing and machine speed, could significantly affect the soil inversion and soil clod breakage; however, it had no significant impact on the TCD.

• 한국생활과학회지
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• 제18권2호
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• pp.407-418
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• 2009

In our modern society along with high speed economic growth and improvement of living conditions and through concentration of people in cities cars became essential necessities for people living in modern society. Due to social and economic conditions and for the need of recycling of materials and as a countermeasure for waste of materials importance of car service is stressed. In this connection need for improvement of working clothes which are suitable for safety and working efficiency in a difficult working environment is essential. However most of working clothes now being sold in the market are produced without consideration of ergonomic aspects of wearers of working clothes. For this reason there is need for basic research on development of working clothes which improve safety and comfort for working of car service workers. Accordingly in this study this author carried out research on fitness, level of satisfaction and dissatisfaction, suitability for movement and level of demand for improvement in working clothes with focus on workers at car service firms and direction for its improvement was explored. This study is intended to provide basic data for development of functional pattern of working clothes for car service workers in future.

• Design & Manufacturing
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• 제6권2호
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• pp.84-89
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• 2012

In recent years, technology of press plastic working having made remarkable progress. We can say this because it facilitates mass production and have superior performances in machining speed and equivalency of quality than other processing methods. In characteristics of press plastic working, mold manufacturing according to characteristics of each product should be preceded before processing and it has a great influence on machining speed and quality of products and etc according to manufacturing method. Therefore, mold design technology is a critical technology in press plastic working. There are lots of variables in press plastic working according to worked material, mold materials, conditions of heat treatment, clearance and so on. Abrasion of mold depends on these kind of conditions and sheared surface which is crucial for quality of product also depends on them. In this study, we conduct research on abrasion loss of mold according to 8, 10 and 12% of clearance for thickness of 1.0mm of worked material out of mold design variables of the products whose worked materials are high carbon steel and carbon tool steel by a practical experiment.

• Tribology and Lubricants
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• 제20권1호
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• pp.21-26
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• 2004

The average frictional coefficient was used generally to analyze the working process of the lubricated machine parts. But it is difficult of taking the correct frictional coefficient because the average frictional coefficient of it is progressed always unstably with a large amplitude on working condition. If the correct analysis of frictional coefficient on working condition for the lubricated machine parts can be possible, it can be effect on condition diagnosis of lubricated machine system. This study was carried out to get the optimum working condition of the hydraulic actuator parts using statistical techniques. From this result, it has the lowest friction coefficient in case of applied load of 3 kg and sliding speed of 120 mm/sec.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제18권1호
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• pp.31-40
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• 2014

Working with dynamic visual representations can help students-with-computer discover new mathematical ideas. Students translate among multiple representations as a strategy to investigate non-routine problems to explore possible solutions in mathematics classrooms. In this paper, we use the area models as new representations for our secondary students to investigate three problems related to the average speed of a particle. Students show their ideas in the process of investigating arithmetic mean, harmonic mean, and average speed through their created dynamic figures. These figures really utilize dynamic geometry software.