• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.363-366
• /
• 2003

The hard turning is a turning operation performed in high strength alloy steels (HRC>30) in order to reach surface roughness close to those obtained in grinding. This is possible because of availability of improved tool materials (polycrystalline cubic boron nitride. PCBN), ad more rigid machine tools. According to many previous work of hard turning mechanism, the maximum temperature of cutting can be raised up to 100$0^{\circ}C$. As the heat generation rate is very high, the thermal displacement of tool holder cannot be negligible. Therefore, the aim of this paper is to analyze effects of high heat generation at CBN tool tip to the thermal displacement of a tool holder in hard turning and finally geometric accuracy. The thermal behavior of a CBN tool holder is investigated by numerical simulation and experiment, and the result shows thermal elongation of microns order is possible during hard turning process.

• Journal of the Korean Society for Precision Engineering
• /
• v.6 no.4
• /
• pp.61-70
• /
• 1989

A new analytical method is proposed to monitor the chip form of cutting forces applying the techinque of signal process. Cutting experiments are carried out under various cutting conditons and cutting forces are measured in-processing through Tool Dynamometer. In this report, auto-correlation functions, frequency characteristics of dynamic force, high frequency distribution and Peak/RMS values are calculated from the measured cutting forces, and the concept of method is also discussed. The experimental results show that six types of the form of chips are possible to classify from the signal of cutting forces not related to cutting conditions.

• Proceedings of the KSME Conference
• /
• 2000.04a
• /
• pp.809-813
• /
• 2000

In this study, screw machining system by use of a rotational tool such as an end-mill or a face cutter with Y axis off-set on a CNC turing center was developed for quick machining. In this system, It was possible to use different tools for different processes, and by off-setting the tool in Y direction by calculated amount it was possible to avoid tool interference problem which could occur within the central area at the end of a tool. In addition, machining a screw with a helix of up to 3 different leads combined and with tapered minor diameter was possible.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.04a
• /
• pp.685-690
• /
• 2000

In this study relationship between relief angles and chatter vibration in turning was examined by using the direct cutting test, in which the cutting depth of a tapered workpiece is varied continuously and the limiting depth of cut is measured at the time when chatter occurs. Test results reveal that 1) limiting depth of cut increases is proportion to side relief angles between 0$^{\circ}$ and 3$^{\circ}$, 2) limiting depth of cut does not show any evident change in spite of side relief angle increased from 3$^{\circ}$ to 12$^{\circ}$, 3) also limiting depth of cut does not change despite front angle change from 0$^{\circ}$ to 12$^{\circ}$.

• Proceedings of the Korean Information Science Society Conference
• /
• 2007.10a
• /
• pp.185-186
• /
• 2007

ITSP(Internet Telephony Service Provider)를 이용한 VoIP 서비스의 사용자가 증가함에 따라 VoIP 스팸은 큰 문제로 대두되고 있다. 기존의 일반 전화 때부터 사용되던 스팸은 실시간적 음성 통신이라는 특성상 콘텐츠 필터링을 하기 어렵기 때문에 롤 행위 패턴 조사를 통해 스패머(Spammer)를 구분하고 있다. 그러나 잘못된 오판으로 인한 문제와 스팸으로 인식하는 임계값을 넘지 않는 한도의 스팸 전송, 그리고 여러 사용자가 하나의 번호를 공유하여 사용하는 경우에는 여전히 스팸의 위협이 남아 있다. 이에 본 논문에서는 튜링 테스트를 이용한 VoIP 스팸 방지를 제안한다. 제안된 방법은 송신자에게 튜링 테스트를 거치게 하고, 튜링 테스트를 통과한 사용자만 수신자와 연결이 되는 방식으로 동작한다. 또한 튜링 테스트를 통과한 정상적인 사용자에게는 티켓을 줌으로써 재발신시 거쳐야하는 튜링 테스트의 번거로움을 줄일 수 있다. 제안된 방법은 ASUS WL-500G 무선 공유기 및 Asterisk IP-PBX에서 구현되었고 실험을 통해 제안된 방법의 유효성을 검증하였다.

• Journal of Advanced Marine Engineering and Technology
• /
• v.23 no.5
• /
• pp.622-629
• /
• 1999

This paper presents the development of an interactive knowledge-based CAM system for design-ing and manufacturing the mold. The system is composed of two functional parts. One is the geo-metric modeller that uses the feature-based models. The models include base plate step, hole, pocket, boss and slot, These are designed by interactive user interface. The other is the expert sys-tem module with inference engine and knowledge database of workpiece material tools manufac-turing machines process an working conditions. With two parts the final mold shape is generated with manufacturing information for effective production.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2002.03a
• /
• pp.145-153
• /
• 2002

A coastwise chemical tanker sailing at full speed has capsized in calm water and whole turing. In the precious paper, we investigated reasons of the accident by demonstrating the proper correction for the free surface effect of the liquid cargo and the bow-sinkage effect. In this paper, we also carry out model experiments of a transverse pressure under the seawater and an outward heel moment according to the heel angle and rudder angle, on the basis of radius of turning circle, ship's speed and drift angle of model ship occurring in turning. It is also shown that the flooding of seawater onto the deck occurring in turning generated a significant outward heel moment and the vertical distance between the center of gravity of the ship and the renter of lateral water drag.

• Journal of the Korean Institute of Navigation
• /
• v.3 no.1
• /
• pp.1-17
• /
• 1979

It is very important for both naval architects and ship's officers to know the maneuvering characteristics of their ships. As the abilities of a rudder which controlls a ship can be determined clearly by analyzing the results of Kempf's zig-zag maneuver and directional stability of a ship also known by Dieudonn spiral maneuver, the importance of turning test which takes much time is recently apt to be neglected. But because the test can be executed comparatively more simply than any other maneuvering tests, it gives some informations on the directional stability, and turning characteristics may be expressed simply by the results of the test, it is still often performed. In this paper several assumptions are made to simplify the turning motion of a ship. The equations of initial transient phase, the radius ofsteady turning circle, and the center of the steady turning point are derived by using the hydrodynamic derivatives. And then the approximate method of drawing the turning circle geometrically is suggested.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.6
• /
• pp.20-26
• /
• 1995

With the recent development of light and high efficient automobiles and aircraft, demand of the A1-Si alloy is rapidly increasing. However, there is an inclination that as the content of silicon increases it becomes more difficult to machine. Accordingly, the present study intends to analyse and study the cutting resistance and surface roughness of A1-Si alloy with Si contents of 8%, 12%, 17%, and 20%. The A1-Si alloy specimens were turned by a poly- crystalline diamond tool under selected cutting conditions, and results are here described and discussed.

• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.1
• /
• pp.108-118
• /
• 1997

The heterarchical structure provides a more attractive solution to the conventional hierarchical structure as the density and level of distrubution of computing resources in manufacturing system expands. Tracing the evolution of control structures for automated manufacturing systems, this paper discusses the design principles for heterarchical system to reduce complexity, increase extendability, flexible configurability and suggests a good example of real-time adaptation using the concept of intelligent agent of manufac- turing entities and fault diagmosis system.