• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.2
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• pp.3-9
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• 2006

HSM(High-speed Machining) is widely used in rapid manufacturing of precision products and molds of various materials. Improvement in cutting efficiency is one of the important subjects in the HSM process. To analyse the dynamic behavior during a very short cutting time, the computational analysis code, LS-DYNA3D, was employed for the simulation of the mechanism of HSM for aluminium 7075. This cutting mechanism includes some difficult points in simulation, for example, material and geometrical non-linearity, high-speed dynamic impact, contact with friction, etc. In this paper, a finite element model considering the strain rate effect is proposed to predict the cutting phenomena such as chip deformation, strain and stress distributions, which will help us to design the HSM process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1023-1028
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• 2009

Cleaning is required following CMP (chemical mechanical planarization) to remove particles. The minimization of particle residue is required with each successive technology generation, and the cleaning of wafers becomes more complicated. In copper damascene process for interconnection structure, it utilizes 2-step CMP consists of Cu and barrier CMP. Such a 2-steps CMP process leaves a lot of abrasive particles on the wafer surface, cleaning is required to remove abrasive particles. In this study, the chemical mechanical cleaning(CMC) is performed various conditions as a cleaning process. The CMC process combined mechanical cleaning by friction between a wafer and a pad and chemical cleaning by CMC solution consists of tetramethyl ammonium hydroxide (TMAH) / benzotriazole (BTA). This paper studies the removal of abrasive on the Cu wafer and the cleaning efficiency of CMC process.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.820-825
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• 2007

A ballscrew-linear motion(LM) guide is well-described by its name: it is a LM guide that runs by ballscrew. It consists of LM rail, LM block, end plate, screw, nut and bearing balls. The ballscrew-LM guide has many advantages compared with conventional LM guide. The high efficiency achieved with rolling contact devices permits the employment of antibacklash methods. The balls provide the only physical contact between nut rail and block and ball screw and nut replacing the sliding friction with a rolling motion. The life of the ballscrew-LM is determinated by the balls. The objective of this paper is to introduce the design of the ballscrew-LM with the safety working load.

• Journal of the Korean Society of Visualization
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• v.14 no.1
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• pp.27-32
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• 2016

The reduction of $CO_2$ emissions has been a key target in the Marine Industry since the IMO's Marine Environment Protection Committee published its findings in 2009. The representative emission index is termed as the EEDI (Energy Efficiency Design Index) for the new ships. Among various flow control techniques ever proposed, the air lubrication method is the one of most promising one in terms of practical applicability. The present study examines the basic characteristics of the flat plate test with intention of applying the air lubrication technology to the reduction of the resistance of a ship. Image analysis technique is proposed as a tool to quantify the effectiveness of the air lubrication method.

• The Journal of Korea Robotics Society
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• v.4 no.4
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• pp.265-272
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• 2009

IVarious driving mechanisms to adapt to uneven environment have been developed for many urban search and rescue (USAR) missions. A tracked mechanism has been widely used to maintain the stability of robot's pose and to produce large traction force on uneven terrain in this research area. However, it has a drawback of low energy efficiency due to friction force when rotating. Moreover, single tracked mechanism can be in trouble when the body gets caught with high projections, so the track doesn't contact on the ground. A transformable tracked mechanism is proposed to solve these problems. The mechanism is designed with several articulations surrounded by tracks, used to generate an attack angle when the robot comes near obstacles. The stair climbing ability of proposed robot was analyzed since stairs are one of the most difficult obstacles in USAR mission. Stair climbing process is divided into four separate static analysis phases. Design parameters are optimized according to geometric limitations from the static analysis. The proposed mechanism was produced from optimized design parameters, and demonstrated in artificially constructed uneven environment and the actual stairway.

• Transactions of Materials Processing
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• v.10 no.3
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• pp.235-245
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• 2001

Deep drawing process, one of sheet metal forming methods, is very useful in the industrial field because of its efficiency The deep drawing is affected by many process variables, such as blank shapes, shape radii of the punch and die, formability of materials and so on. Especially, blank shape is very important formability factor. In this study, in order to investigate the effects of blank shape, we suggested three kinds of blank shapes and examined friction test about three conditions. We measured punch load distribution according to punch stroke under the conditions of each punch and die shape radii and observed punch load of elliptical cup forming.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.35-40
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• 2014

Wire drawing is aplastic deformation process that produces a wire with a desired diameter by pulling the end of the wire through a die. During the cold wire drawing process, the temperature between the wire and the die bearing is increased. This temperature increase causesenergy consumption increase, bad wire quality, and decreased die life. To reduce friction and avoid high temperature between the wire and the die in the cold wire drawing process, a dry lubricant with soap particles is used. It is not possible to reused the lubricant onceiron oxide is attached to the soap particlesat high pressure die. In this study, recycling technologies for wasted soap particles with processes of crushing, separation, and screening are developed. From the evaluation, the recycling efficiency was found to be 86.97%.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.43.1-43.1
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• 2017

We investigate properties of black hole (BH) binaries formed in globular clusters, by using direct N-body simulations. Comparing with previous studies which usually considered single BH masses, our models consist of two-component BH masses, or continuous BH mass function with single mass ordinary cluster stars. During the early stage of dynamical evolution, initially distributed BHs are move to the cluster center by dynamical friction, then BH-BH binaries start to be formed, and eventually be ejected from the cluster due to three body interaction. Finally we find the formation efficiency of high mass BHs are alwats larger than that of lower mass BHs, implying that a BH mass spectrum expected from GW observation should be biased to high mass. In addition, mass ratios of BHs in binaries prefer similar masses (ratio~1), while the most extreme case is less than 3. Expected merger rate from our models is about 7 BH-BH mergers per $Mpc^3$ per yr.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.307-307
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• 2000

The swing motion of the spreader during and after movement causes an efficiency problem of position control in unmaned gantry crane. The objective of this research is to design implementable stabilizing controllers that minimize the swing motion of spreader in precise position control. The dynamic equations related to trolley, rope, and spreader are derived. For constitute a similar actual system, we introduced a conception of spring and damper in the connector. It is located between the trolley and link that is used in stead of rope. We derived dynamic equation by appliance that friction and external disturbance are occurred to the connector. We constituted of position servo system and velocity servo system for the control of position and velocity of the trolley and constituted of lag compensator system for the control of sway of the spreader. And we will show an effect of the proposed system in this research finally.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.03a
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• pp.152-157
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• 1995

In Turning It is good selection of cutting condition and cutting tools that influence upon the accuracy of dimension manufacturing efficiency and extension of tool life. Among them especially the identification of cutting force due to the change of cutting conditions which exerts a great influence on the turning is very important. In this study the cutting resistance due to the change of cutting conditions was caculated by using the energy method and good agreement in shown between theoritical and experimental results which were tested for the cutting resistance at the cemented carbide cutting tools with workpieces of SM20C and SM 45C.