• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.422-428
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• 2001

The term High Speed Machining has been used for many years to describe end milling with small diameter tools at high rotational speeds, typically 10,000 - 100,000 rpm. The process was applied in the aerospace industry for the machining of light alloys, notably aluminium. In recent year, however, the mold and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. With increasing cutting speed used in modern machining operation, the thermal aspects of cutting become more and more important. It not only directly influences in rate of tool wear, but also will affect machining precision recognized as thermal expansion and the roughness of the surface finish. Hence, one needs to accurately evaluate the rate of cutting heat generation and temperature distributions on the machining surface. To overcome the heat generation, we used to cutting fluid. Cutting fluid play a roles in metal cutting process. Mechanically coupled effectiveness of cutting fluids affect to friction coefficient at tool-work-piece interface and cutting temperature and chip control, surface finish, tool wear and form accuracy. Through this study, we examined the behavior of heat generation in high-speed machining and the cooling performance of various cooling methods.

• 한국공간정보시스템학회 논문지
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• 제8권2호
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• pp.1-11
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• 2006

This paper addresses a GIS (Geographic Information System) based system in order to reduce the rate of public transportation accidents occurring in Iranian roads network. Over the years, the road accidents are a major issue throughout the world. Today, particular consideration is given to those technologies which can lead to diminish on the number of critical incidents. One of the main factors resulting in accidents and fatalities rates growth is the speed violation of buses in Iranian road network. The conventional speed controlling approach in Iran based on the Tachograph which records vehicle's speed, time, and stoppage in the mechanical processing has many problems. Hence, this research is intended to design and implement a GIS-based system to manage road accident of Bus transportation system using offline tracking system. This was accomplished using a GIS-based technique that encompasses three steps. The first step is developing a GIS-based accident system. The second step includes designing and applying a tracking system inside 90 buses for recording Bus information for speed controlling. Lastly, by using mentioned system in police center, the illegal drivers' punishment would be considered properly. Overall, this system has been successfully applied in this work. Therefore, the police and transportation office are able to control and make policy to diminish the number of accident. It is anticipated that online tracking system through the Web GIS would be utilized In this system in the near future.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.715-723
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• 2016

This paper proposes a design of optimal PI(D) controller for brushless DC (BLDC) motor speed control by the particle swarm optimization (PSO), one of the powerful metaheuristic optimization search techniques. The proposed control system is implemented on the TMS320F28335 DSP board interfacing to MATLAB/SIMULINK. With Back EMF detection, the proposed system is considered as a class of sensorless control. This scheme leads to the speed adjustment of the BLDC motor by PWM. In this work, the BLDC motor of 100 watt is conducted to investigate the control performance. As results, it was found that the speed response of BLDC motor can be regulated at the operating speed of 800 and 1200 rpm in both no load and full load conditions. Very satisfactory responses of the BLDC system can be successfully achieved by the proposed control structure and PSO-based design approach.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.172-175
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• 2002

High speed machining is one of the most effective technologies to improve productivity. It can give great advantage for manufacture of die and Moulds. However, when machining of micro groove in high speed machining a severely thermal damage was generated on workpiece and cutting tool. Generally, the cutting fluid is used to improve penetration. lubrication. and cooling effect. In order to rise the performance of lubrication. it contains extreme pressure agents (Cl, S, P). But the environment of work room go bad by those additive. Therefore, the compressed chilly air with oil mist system was developed to replace the conventional cutting fluid system. This paper carried out the tests to evaluate the machinability by the cutting environment in high speed micro groove machining of NAK80 (HrC40). Compressed chilly air with oil mist was ejected on the contact area between cutting edge and workpiece. The effect of this developed compressed chilly air with oil mist system was evaluated in terms of tool life. The results showed that the tool lift of carbide tool coated TiAlN with compressed chilly air mist cooling was much longer than that of the dry and flood coolant when cutting the material.

• 대한안전경영과학회지
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• 제16권2호
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• pp.1-9
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• 2014

This study tried to propose plan to prevent human error of railroad driver among human error of railroad worker which takes great share in railroad accident. For this, in order to maintain correlation between the accident actually occurred after the opening of high-speed railroad and experience of accident that did not happened, survey on respondent was analyzed by conducting survey on KTX captain who is working in driving work of high-speed railroad, and instruction management team manager who manages KTX captain and captain. This thesis classified the factors by human factor, job factor, environment factor, organization factor, and established human error management model by comparing and analyzing how each factors have spatial interrelations with a railroad accident. The purpose of this study is to contribute to make safe railroad, and reliable railroad by preventing human error accident by minimizing human error of high-speed railroad drivers, and improving driving workers to cope accurately and fast with irregularities through various institutional improvement, improvement of driving facilities, improvement of operating room environment, and improvement of education system.

• Wind and Structures
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• 제34권4호
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• pp.335-353
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• 2022

The current work numerically investigates the transient force and dynamic response of an overhead transmission tower-line structure caused by the passage of a high-speed train (HST). Taking the CRH2C HST and an overhead transmission tower-line structure as the research objects, both an HST-transmission line fluid numerical model and a transmission tower-line structure finite element model are established and validated through comparison with experimental and theoretical data. The transient force and typical dynamic response of the overhead transmission tower-line structure due to HST-induced wind are analyzed. The results show that when the train passes through the overhead transmission tower-line structure, the extreme force on the transmission line is related to the train speed with a significant quadratic function relationship. Once the relative distance from the track is more than 15 m, the train-induced force is small enough to be ignored. The extreme value of the mid-span dynamic response of the transmission line is related to the train speed and span length with a significant linear functional relationship.

• 한국항만학회지
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• 제11권2호
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• pp.273-280
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• 1997

Recently the importance of the cargo handling equipments in a port has been increasing to get strong competition from other ports. Many ports are making efforts to modernize their cargo handling equipments. The kernel technology of such equipments is the speed control of DC motor which is used as an essential part of them. In this paper, we discuss the speed control of a DC motor as a basic work for building cargo handling equipments in a port. DC Motors are still widely used in industrial fields, as driving power motor for electrical fields. DC drives, being easy to control, are widely used in many variable-speed and position control drive system. Traditional analog control circuits used in such applications have many disadvantages. Complex control schemes are difficult to implement with analog components. All these factor and invention of the microprocessor has made it possible to use digital control circuits, using microprocessing system. These digital circuits have been found to be reliable, flexible, and also immune to noise. In this paper it presents the speed control of a SCR DC motor driver which using dual converter by 80c196kc microprocessor. We developed a thyristor power amplifier which does not cause damage thyristor because it is designed to prevent triggering the two SCRs in the same arm simultaneously. And it was analyzed voltage and currents wave at reactive load.

• 문화경제연구
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• 제20권2호
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• pp.3-18
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• 2017

본 연구에서는 콘텐츠산업 인력의 업무 자율성 변화를 분석했다. 한국근로환경조사(2011, 2014) 자료에서 콘텐츠산업 인력과 업무 자율성 변수를 추출하고 이중차감추정법을 활용하여 분석한 결과 전체 표본에서는 콘텐츠산업 인력의 업무 자율성(업무 순서, 업무 방법, 업무속도)에 유의미한 변화가 나타나지 않았다. 반면 최근 콘텐츠업계의 자율성 감소는 논의는 대규모 인력과 자본이 투입되는 경우라는 것을 고려하여 30인 이상 사업체 표본을 대상으로 분석하면 콘텐츠산업 인력의 자율성이 유의미하게 감소한 것으로 나타난다. 업무의 자율성은 직위와 역량과는 정(+)의 관계가, 사업체 규모와는 부(-)의 관계가 나타난다. 본 연구는 그동안 사례 중심으로 논의되어 왔던 콘텐츠산업 인력의 업무 자율성 변화를 실증분석했다는 의의를 가진다. 또한, 인력들의 부여되는 자율성이 콘텐츠 제작 유통 과정에서 긍정적인 효과를 창출하기 위해서는 인력에 대한 보상 및 관리 체계 개선이 수반되어야 함을 제시하였다.

• 비교문화연구
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• 제29권
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• pp.85-111
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• 2012

Zhong-lie-xiao-wu-yi(忠烈小五義), whose author was Shiyukun(石玉昆), is a Xia-Yi-Gong-An(俠義公案) novel in the late Qing Dynasty. This work published in 1890 when Emperor Guangxu(光緖) governed China. This work's author is Shiyukun, distribution books has an amender. The amender will be a shuoshuyiren (說書藝人). Zhong-lie-xiao-wu-yi is Zhong-lie-xia-yi-zhuan(忠烈俠義傳)'s a sequel, the story leads from Zhong-lie-xia-yi-zhuan. It is just the beginning of Zhong-lie-xiao-wu-yi is redundant. Zhong-lie-xiao-wu-yi was introduced to the late Chosun(朝鮮) Dynasty. This work was translated in Hangeul, Chosun's readers read Zhong-lie-xiao-wu-yi. This work's circulation is not clear, But this work's exciting story is interested in the readers. This work is characterized as follows: First of all, Zhong-lie-xia-yi-zhuan's charaters appear equally, the readers feels familiar. The readers like the familiar characters, because the readers read the book. The familiar characters can have a sense of speed in reading. Second, the story is continuous. Zhong-lie-xiao-wu-yi is narrated by connecting Zhong-lie-xia-yi-zhuan's story. Third, Zhong-lie-xiao-wu-yi was seeking an open ending. Classical novels prefer happy ending, this work is open ending, the expectations for the sequel became more doubled. The fourth, this work took advantage of the colloquial expressions. Zhong-lie-xiao-wu-yi is Huabenti(話本體) novel, took advantage of the spoken language. Suyu(俗語) and xiehouyu(歇後語) was represented in this work. Fifth, this work is formed a universal consensus. Ordinary people must empathize about xia-yi(俠義) and retribution, this work was well represented. Because the readers would have liked to this story.

• 한국통신학회논문지
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• 제21권1호
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• pp.241-250
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• 1996

In this work, an improved architecture of two-dimensional digital filter(2D DF) is suggested, and then the filter is simulated by C, VHDL language and related layouts are designed by Berkeley CAD tools. The 2D DF consists of one-dimensional digital filters and delay lines. For one-dimensional digital filter(1D DF) case, once filter coefficients are represented by canonical signed digit formats, multiplications are exected by hardwired-shifting methods. The related bit numbers are handled to prevent picture quality degradation and pipelined adder architectures are adopted in each tap and output stage to speed up the filter. For delay line case, line-sharing DRAM is adopted to improve power dissipation and speed. The filter layout is designed by semi/full custom methods considering regularity and speed improvement, and normal operation is confirmed by simulation.