• Design & Manufacturing
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• v.2 no.1
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• pp.33-38
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• 2008

As consumer in optics, electronics, aerospace and electronics industry grow, the demand for ultra precision aspherical surface lens increases higher. Precision turning with single-diamond tools has a long history of development for fabrication of optical quality surfaces since the advent of aerostatic rotary spindles and precise linear motion guide ways. To enhance the precision and productivity of ultra precision aspherical surface micro lens, the following specification of ultra precision grinding system is required: the highest rotational speed of the grinder is 100,000rpm and its turning accuracy is $0.1{\mu}m$, positioning accuracy is $0.1{\mu}m$. The development process of the grinding system for the ultra precision aspherical surface micro lens for optoelectronics industry is introduced. In the work reported in this paper, an intelligent grinding system for ultra precision aspherical surface machining was designed by considering the factors affecting the surface roughness and profiles accuracy. An aerostatic form was adopted to build the spindle of the workpiece and the spindle of grinder and ultra precision LM guide way was adopted in this system. And this paper deals with mirror grinding of an aspheric surface micro lens by resin bonded diamond wheel and spherical lens of BK7. It results was that a form accuracy of $0.6{\mu}m$ P-V and a surface roughness of $0.006{\mu}m$ Rmax.

• Explosives and Blasting
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• v.15 no.3
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• pp.14-19
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• 1997

Koreans have emphasized education as the primary means to reconstruct our country means to reconstruct our country after two catastrophic events-the Japanese occupation and the Korean War(1950-1953). A Strong belief- in education coupled with sheer deter-mination spurred the period of industrial and eeonomic development that started in the early 1970-'s. The "can-do" attitude of the general public was matched and aided by small S & T communities. Scientists and engineers provided the neeessary expertise to manufacture goods and process the many raw materials imported from overseas. After nearly three decades of reconst-ructing our completely devastated country, Korea has become a modern, cosmo-politan, fast-paced and dynamic country. In order to further increaser our manufac- turing capabilities and double the per-capita income by the beginning of the 21st century, we must improve productivitiy and encourage creatitivity in all sectors of our country. The S & T community's efforts in research and development. education, and interna-tional cooperation will be invaluable in determining our direction and reaching these goals. The general public is eager to peacefully unite our foreign powers since 1945. Toward that end. members of the S & T community are willing to coope-rate with our north Korean counterparts in all areas of S & T with the exception of defense related endeavors. Establi-shing scientific ties with north Korea will result in mutual economic benefit and greater regional stability in East Asia. In particular. scientists and manu-facturers in each province are eager to initiate cordial and professional relation-ships with north Korea in the hopes of securing these benefits. The Korean Federation of Science and Technology Societies(KOFST) has played an important role both in developing S & T policies, and in gostering the frowty of S & T societies. A non-governmental umbrella organization composed of over 251 professional societies, KOFST facili-tates the transfer of research outcomes and technology from research institutions to the various industries. KOFST also seeks to increase cooperation between the countries of the Pacific Rim. As evidence of that, we have pursued joint research and industrial ventures with China. Established projects include those on environmental conditions in the Yellow Sea, and improvement of aircraft manufacturing, telecommunica-tion equipment, and agricultural produ-cts. Increased cooperation between the Pacific Rim countries, particularly in S & T, would foster social and economic development for the region as a whole.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.179-187
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• 2010

The purpose of this study is to suggest the advancement of the competitive power of Korean electronics and automobile industries from a product-architectural point of view. There are two types for the characteristics of parts. They are the modular type and the integral type. The former is very independent between one subsystem and another, whereas the other is very dependent. The distinction of product architecture makes them different for the ability to organize developing products suited for the product manufacturing. The organizing ability is generally divided into the abilities of 'modulation integration' and 'selection assembly'. For the integral products such as cars, the integration ability is important between an enterprise and another, as well as between a part and another. However, the modular products such as a PC need the ability to select and effectively organize optimal parts or enterprises. The strategy raising product competitiveness is pursued by synthesizing 'design manufactu-turing strategy' for the product architecture and 'customer value strategy' for the customer values.

• Journal of Korea Society of Industrial Information Systems
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• v.21 no.4
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• pp.43-53
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• 2016

In this paper, monitoring method of tool fracture using motor current was proposed for turning process. In order to take more reliable current signal, cutting force signal was compared as reference signal because cutting force signal is reliable, and analysis of signal correlation between cutting force and motor current was performed. The static components of the cutting force and motor current signals were correlated very well for different cutting conditions, and it was proven to use the motor current as an proper sensor for monitoring of tool fracture. To understand the characteristics of motor current, various kinds of cutting experiment were performed including tool fracture experiments. As a result, a new method to detect tool fracture using motor current in turing was proposed, and a large number of fracture experiments were carried out to evaluate the reliability of the proposed method. Finally, it can be possible to detect the tool fracture reliably.

• International Journal of Contents
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• v.5 no.3
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• pp.50-56
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• 2009

Internet is being used for several activities by a great range of users. These activities include communication, e-commerce, education, and entertainment. Users are required to register regarding website in order to enroll web activities. However, registration can be done by automated hacking software. That software make false enrollments which occupy the resources of the website by reducing the performance and efficiency of servers, even stop the entire web service. It is crucial for the websites to have a system which has the capability of differing human users and computer programs in reading images of text. Completely Automated Public Turing Test to Tell Computers and Human Apart (CAPTCHA) is such a defense system against Optical Character Recognition (OCR) software. OCR can be defined as software which work for defeating CAPTCHA images and make countless number of registrations on the websites. This study proposes a new CAPTCHA context that is Korean CAPTCHA by means of the method which is splitting CAPTCHA images into several parts with random rotation values, and drawing random lines on a grid background by using Korean characters only. Lines are in the same color with the CAPTCHA text and they provide a distortion of image with grid background. Experimental results show that Korean CAPTCHA is a more secure and effective CAPTCHA type for Korean users rather than current CAPTCHA types due to the structure of Korean letters and the algorithm we are using: rotation and splitting. In this paper, the algorithm of our method is introduced in detail.

• Journal of Navigation and Port Research
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• v.37 no.4
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• pp.337-343
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• 2013

To ensure the safety for vessels anchored in stormy weather, duty officer and VTS operator have to frequently check whether their anchors are dragging. To judge dragging of the anchored vessel, it is important for VTS operator to recognize the turning circle and its center of the anchored vessel. The judgement for the anchored vessel dragging can be made by using Radar and AIS. If it is available, CCTV or eye-sighting can be used to know the center of turing circle. However, the VTS system collects individual ship's dynamic information from AIS and ARPA radar and monitors of the anchored vessels, it is difficult for VTS operator not only to get the detailed status information of the vessels, but also to know the center of turning circle. In this study, we propose an efficient algorithm to estimate the center of turning circle of anchored vessel by using the ship's heading and position data, which were from AIS. To verify the effectiveness of the proposed algorithm, the experimental study was made for the anchored vessel under real environments.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.471-478
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• 2003

In the Signalized Intersection, the capacity analysis is conducted with a large amount of input data such as road way, traffic and signal condition. but the level of service(LOS) is determined by delay estimated as a measure of effectiveness (MOE) based on this procedure. However, It is under the circumstances which are not considered for the errors caused by the uncertainty of input data in the field(the turing volumes, lane geometry, signal timing, grade of approach lane, percentage heavy vehicles, peak hour factor and arrival type etc.) as become the bases in the determination of the capacity and LOS. It includes the problem of reliability which is not verified for the capacity and LOS estimated. So, this study is to suggest the minimization of their influences by examining whether the uncertainty of input data such as the traffic volume, percentage of heavy vehicles and roadway geometry on the approach lane in the intersection under the study affects the capacity analysis and LOS determination.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.4
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• pp.153-166
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• 2008

According to the growth of the internet and the usage of software agents, the CAPTCHA that is a method for taking apart humans and computers has been widely deployed and used. As the results of many research activities, the CAPTCHA, which is spoken for a distorted image material including random text, has known to be easily breakable via artificial intelligence techniques. As one of alternatives for those text-based CAPTCHAs, methods using photos are concerned and various image-based CAPTCHAs are suggested. However, image-based CAPTCHAs still have some problems. In this paper, we discuss what are the problems in each image-based CAPTCHA and propose a new image-based CAPTCHA using image composition as the solution of those problems. Furthermore, for the secure operation of the CAPTCHA, we suggest a communication protocol that works without the virtual session and consider possible security and usability problems in the protocol.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.4
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• pp.761-770
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• 2012

CAPTCHAs(Completely Automated Public Turing tests to tell Computer and Human Apart) have been widely used for preventing the automated attacks such as spam mails, DDoS attacks, etc.. In the early stages, the text-based CAPTCHAs that were made by distorting random characters were mainly used for frustrating automated-bots. Many researches, however, showed that the text-based CAPTCHAs were breakable via AI or image processing techniques. Due to the reason, the image-based CAPTCHAs, which employ images instead of texts, have been considered and suggested. In many image-based CAPTCHAs, however, the huge number of source images are required to guarantee a fair level of security. In 2008, Kang et al. suggested a new image-based CAPTCHA that uses test images made by composing multiple source images, to reduce the number of source images while it guarantees the security level. In their paper, the authors showed the convenience of their CAPTCHA in use through the use study, but they did not verify its security level. In this paper, we verify the security of the image-based CAPTCHA suggested by Kang et al. by performing several attacks in various scenarios and consider other possible attacks that can happen in the real world.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.6
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• pp.105-112
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• 2009

Nowadays, completely automated public turing tests to tell computers and humans apart(CAPTCHAs) are widely used to prevent various attacks by automated software agents such as creating accounts, advertising, sending spam mails, and so on. In early CAPTCHAs, the characters were simply distorted, so that users could easily recognize the characters. From that reason, using various techniques such as image processing, artificial intelligence, etc., one could easily break many CAPTCHAs, either. As an alternative, By adding noise to CAPTCHAs and distorting the characters in CAPTCHAs, it made the attacks to CAPTCHA more difficult. Naturally, it also made users more difficult to read the characters in CAPTCHAs. To improve the readability of CAPTCHAs, some CAPTCHAs used different colors for the characters. However, the usage of the different colors gives advantages to the adversary who wants to break CAPTCHAs. In this paper, we suggest a method of increasing the recognition ratio of CAPTCHAs based on colors.