• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1509-1517
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• 1993

The purpose of this study is to develop a program for the automatic derivation of the symbolic equations necessary for the kinematic and dynamic analyses of the spatial mechanism. For this purpose, a symbolic manipulation package called MCSYMA is used. Every symbolic equation is formulated using relative joint coordinate to obtain the numerically efficient system equations. These equations are produced in FORTRAN statements and linked to a FORTRAN program for numerical analysis. Several examples are taken for comparison with the commercial package called DADS which is using Cartesian coordinate approach. Also, this symbolic formulation approach is compared with a conventional numerical approach for an example. The results show that this symbolic approach with relative joint coordinate system is most efficient in computational time among three and is recommended for the derivation of macro elements frequently used.

• Journal of Periodontal and Implant Science
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• v.28 no.4
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• pp.823-828
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• 1998

A primary goal of periodontal therapy is the creation of root surfaces that are free of plaque and calculus. It is not yet to be determined whether it is desirable to have a smooth root surface after treatment. It is also not clear what degree of roughness result from different instruments. In the present study various instruments for root surface debridement were evaluated. 20 extracted teeth were utilized, and the teeth were treated with one of the following instrument: Gracey curette, Perio Clean, and piezo ultrasonic device(Setlec, P Max) with general scaler tip, curette-like tip, and diamond tip. 3 dimensional planimetric device(Accura) was used to evaluate the average surface roughness. It was demonstrated hand and power-driven instruments did not have a significant difference in roughness of the root surface following instrumentation. And ultrasonic scaler tip tended to make a most smooth surface than other instruments. The possible reasons of the result were discussed.

• Journal of the Ergonomics Society of Korea
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• v.16 no.3
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• pp.11-21
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• 1997

The purpose of this study is to obtain 3-dimensional isocomfort workspace using the robot kinematics, which is based on perceived discomfort in varying postures for manipulating four types of controls. Fifteen healthy male subjects participated in the experiment where their perceived discomfort in the given postures was measured, in which L32 orthogonal array was adopted. The shoulder flexion and adduction-abduction, elbow flexion, types of controls, and right/left hands were selected as experimental variables. The results showed that the shoulder flexion and adduction-abduction, elbow flexion, and types of controls significantly affected the perceived discomfort at .alpha. =0.01. Depending upon the types of control used, regression equations predicting perceived dis- comfort and three dimensional isocomfort workspace were suggested based on the experiemntal cata. Using the equations, driver's isocomfort workspace in his/her cabin for pushing operation was illustrated, in which the robot kinematics was employed to describe the translational relationships between the upper arm and the lower arm/hand. It was ecpected that isocomfort workspace could be used as a valuable guideline to design workplaces ergonomically.

• Journal of Biomedical Engineering Research
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• v.15 no.3
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• pp.289-294
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• 1994

A new type of electrogoniometer to measure the three dimensional motion of the human knee joint was developed. This instrument is composed of six potentiometers: four arranged for two universal joints, one for pin joint, and one for axial rotation measurement. The voltage change in six potentiometers were collected through A/D converter for acquisition, storage and analysis. With a developed instrument, gait analysis was performed. Compared to earlier developed triaxial type goniometer, new instrument shows its convenience in application and accuracy in measurement.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.433-442
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• 1989

Owing to the development of CNC machine tools and automatic programing software, the milling process with ball-end mill has become the most widely used process where three-dimensional precision machining is important. In this study, the ball-end milling process has been analyzed and a cutting force model has been developed to predict the cutting force acting on the ball-end mill on given machining conditions. The development of the model is based on the analysis of geometry of a ball-end mill an the oblique cutting process. The cutting edges of ball-end mills are considered as a series of infinitesimal elements and the geometry of the cutting edge element each cutting edge element is straight. The oblique cutting process in the small cutting edge element has been analyzed as orthogonal cutting process in the plane containing the cutting velocity vector and chip-flow vector. Hence, with the orthogonal cutting data obtained from orthogonal turning test, the cutting forces can be predicted through the model. The predicted cutting forces has shown a fairly good agreement with the test results in various plane cutting conditions.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.44-52
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• 2004

This paper proposed a error compensation methodology for three-DOF translational parallel manipulator. The proposed method uses CMM (coordinate measuring machine) as metrology equipment to measure the position of end-effector. To identify the transform relationships between the coordinate system of the parallel manipulator and the CMM coordinate system, a new coordinate referencing (or coordinate system identification) technique is presented. By using this technique, accurate coordinate transformation relationships are efficiently established. According to these coordinate transformation relationships, an equation to calculate the compensating error components at any arbitrary position of the end-effector is derived. In this paper, Monte Carlo simulation method is applied to simulate the compensation process. Through the simulation results, the proposed error compensation method proves its effectiveness and feasibility.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.631-634
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• 2001

In this study, the graphic simulation system of multi joint manipulator is developed to analyze and optimize the remote handling processes for the spent fuel assembly. This system consists of a 3-D graphical modeling system, a device assembling system, and a motion simulation system. To analyze and optimize the processes involved in multi-joint manipulator operation such as NFBC transportation process and bottom nozzle removal process, the virtual work place is implemented using a computer graphic technology. This virtual workcell is exactly same as that of the real environment. This graphic simulation system of the multi-joint manipulator can be effectively used for designing the main processes and maintenance processes of the spent fuel management.

• Electronics and Telecommunications Trends
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• v.14 no.3 s.57
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• pp.86-94
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• 1999

유럽의 전기통신 표준화기구(ETSI)는 유럽연합(EU) 차원의 지역 표준화를 추진함에 있어서 갈등요인이 될 수 있는 지적재산권 문제를 원활하게 해결하기 위한 노력의 일환으로 1993년 3월 ETSI IPR 정책을 채택하였다. 그러나 동 정책을 재검토하게 되었으며, 그 결과로 IPR 정책 운영상의 주요 문제가 되었던 IPR 협약서 내용을 폐지하고 1994년 11월의 ETSI 21차 총회에서 본 IPR 정책을 새로이 수립하여 그 후 3년이 지난 1997년 11월에 이를 정식 ETSI IPR 정책으로 채택하였다. 이에 본 고에서는 ETSI에서 추구하고 있는 정보통신 표준화와 관련한 IPR 정책의 주요 변화사항을 분석하였으며, 아울러 최근에 개정된 주요 IPR 정책의 내용을 고찰함으로써 국내의 관련 정책 수립시 도움이 되도록 하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.929-932
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• 2002

As 3-D solid modeling systems have been widely used in product design recently, dedicated design systems for molds of the products have been developed and introduced to mold manufacturers. These mold design systems provide solid modeling capabilites for mechanism to free undercuts. This paper describes an algorithm for slide design capability that has been developed based on a commercial CAD system, Unigraphics. Since the relationship between slide parts were investigated and predefined using parameters in the system, the dimensions and locations of the parts are modifed automatically when a part is modified.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.10a
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• pp.202-209
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• 1999

한국전력공사 전력연구원 로봇 원격제어기술과 가상현실기술을 접목하는 과정의 일환으로 로봇작업을 3-D 그래픽으로 시뮬레이션하는 연구를 수행하였다. 본 논문에서는 로봇언어를 이용하여 이동경로를 생성하고 이동된 로봇의 위치와 자세정보를 그래픽변수와 연결하여 가시화하는 일련의 과정을 다룬다. 개발된 시뮬레이션 패키지는 실시간으로 로봇의 움직임을 관찰하는 목적 이외에 로봇작업경로의 생성과 로봇설계 등의 엔지니어링 목적으로도 활용할 수 있는 기능을 갖추고 있다. 이 시스템은 사용자의 편이성과 로봇의 신뢰성 및 가격적인 면 등을 고려하여 팬티엄-II급 산업용 PC와 Windows NT로 구성되어 있고, 그래픽 툴로는 Microsoft가 멀티미디어용으로 개발한 DirectX를 활용하였다. DirectX는 다양한 예제 프로그램을 포함하고 있는 Software Design Tool을 제공하므로 소프트웨어 개발시간을 단축시키는 장점을 가지고 있다.