• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.2
• /
• pp.1-8
• /
• 2011

5-axis NC machining has a good advantage of the accessibility of tool motion by adding two rotary axes. It offers numerous advantages such as expanding machining fields in parts of turbo machineries like impeller, propeller, turbine blade and rotor, reasonable tool employment and great reduction of the set-up process. However, as adding two rotary axes, it is difficult to choose suitable machining conditions in terms of cutter path and cutter posture at a cutter contact point. Therefore in this paper, it is proposed to decide suitable machining condition through an experimental method such as adopting various cutter paths, cutter postures types. Also, in order to increase the efficiency of 5-axis machining, it is necessary to minimize the cutter posture changes and create a continuous cutter path while avoiding interference. This study, by using an MC-space algorithm for interference avoidance and an MB-spline algorithm for continuous control, is intended to create a 5-axis machining cutter path with excellent surface quality and economic feasibility. finally, this study will verify the effectiveness of the suggested method through verification processing.

• Proceedings of the Korea Multimedia Society Conference
• /
• 1998.10a
• /
• pp.155-160
• /
• 1998

VRML 파서는 VRML(.wrl) 파일을 읽기 위하여 반드시 필요한 부분으로서, 이미 공개되어 있는 것으로는 C/C++ 코드의 QvLib1.0과 Yacc & Lex로 개발한 VRML2.0 파서가 있다. 그러나 QvLib1.0의 경우 VRML2.0 파일에 적용할 수 없으며, Yacc & Lex로 개발한 파서는 생성된 소스 코드를 수정하기 어려울 뿐만 아니라 이를 수정하기 위해서는 자동 생성기인 Yacc & Lex의 사용 방법을 잘 알고 있어야 한다. 이에 본 논문에서는 C/C++ 코드의 VRML2.0 파서를 설계 및 구현하고 파싱의 결과로 생성된 parse tree를 이용하여 VRML 파일을 scene graph로 bygus할 수 있도록 하는 Scene Graph 생성기의 구현과정을 소개하였다. 또한 본 연구의 파서와 Scene Graph 생성기를 기 개발된 VRML 저작도구에 적용 및 테스트하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.4
• /
• pp.335-342
• /
• 2021

By using HLS when developing a communication system FPGA, HDL code can be automatically generated from a little modified C/C++ source code used for performance verification, which has the advantage of shortening the development period. In this paper, a method of designing a telemetry standard 106-17 LDPC decoder in C language is proposed using Xilinx's Vivado HLS, and by synthesizing Spartan-7 and Kintex-7 as target devices, throughput and FPGA utilization rate was compared.

• Journal of the Korean GEO-environmental Society
• /
• v.4 no.2
• /
• pp.57-64
• /
• 2003

Marston (1913) and Spangler's (1982) theory was widely used in the analysis of the earth pressure of the narrow and long excavated ditch type backfield ground. Their theory was more clearly explained by expressing the minor principle stress arch connecting the minor principle stress link induced by interaction between the excavated wall surface and the backfilled earth. which was done by R.L. Handy(1985). Later C.G. Kellogg(1993) extended the study from vertical symmetric to incline symmetric in the backfill space type research. In the C.G. Kellogg's study, it is assumed that the resistance of wall friction on the sloping wall could be replaced by the internal friction angle in the sloping section bottom. In the study, the resistance of wall friction in the sloping section bottom, which was applied by C.G. Kellogg, would be different in magnitude with the resistance of wall friction in sloping section. The magnitude is expected to affect in the earth pressure calculation and verified by the soil test box, the C.G. Kellogg's theory, the numerical analysis and the modified C.G. Kellogg's theory considering the friction resistance to influence the incline wall.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.9
• /
• pp.663-670
• /
• 2020

A study on mechanical property characterization and modeling technique was carried out to approximate the behaviour of structures with 2.5D C/SiC material. Several tensile tests were performed to analyze the behaviour characteristics of the 2.5D C/SiC material and elastic property was characterized by applying a mathematical homogenization and a modified rule of mixture. SiC matrix representing the elasto-plastic behavior approximates as a bilinear function. Then the equivalent yield strength and equivalent plastic stiffness were calculated by minimizing errors in experiment and approximation. RVE(Representative Volume Element)was defined from the fiber and matrix configuration of 2.5D C/SiC and a process of calculating the effective stiffness matrix by applying the modified rule of mixture to RVE was implemented in the ABAQUS User-defined subroutine. Finite element analysis was performed by applying the mechanical properties of fiber and matrix calculated based on the proposed process, and the results were in good agreement with the experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.1C
• /
• pp.50-58
• /
• 2004

An image enhancement method using modified anisotropic diffusion filter is proposed in this paper. It employs sensor noise estimation and scale space methods based on the minimum reliable scale. Then the anisotropic diffusion filter is modified by the calculated critical value function and local gradient. Through simulation, it is verified that the proposed algorithm has the capability of little or no noise amplification in homogenous region as well as superior edge enhancement.

• Korean Journal of Animal Reproduction
• /
• v.16 no.3
• /
• pp.239-246
• /
• 1992

Capacitated and acrosome~reacted spermatozoa were microinjected into the perivitelline space of bovine oocytes matured in vitro. Oocytes obtained from the ovaries of slaughtered heifers and cows were cultured in vitro in the TCM-199 supplemented with 20% FCS for 24 hr at 39$^{\circ}C$ under an atmosphere of 5% CO$_2$ 8% O$_2$. Fresh or frozen spermatozoa were incubated for 2 hr at 39°C under an atmos-phere of 5% CO$_2$, 8% O$_2$ in Ham's F-lO medium containing 0.75% BSA for capacitation, and kept for 30 min in culture medium containing 12 mM of dbcGMP and lOmM of immidazol for acrosome resction. One motile spermatozoon was injected into the perivitelline space of each oocyte. The 2nd polar body and the pronuclei were observed in 9.5% and 5.4% of oocytes, respectively. The rate of cleavage of oocyte over 2-cell stage was 4.1%(10 of 242), These results indicate that the microinjection may be a useful technique to study sperm-oocyte interaction.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.2 no.2
• /
• pp.81-89
• /
• 2001

Space systems are operating in a changing and uncertain space environment and are desired to have autonomous capability for long periods of time without frequent telecommunications from the ground station At the same time. requirements for new set of projects/systems calling for ""autonomous"" operations for long unattended periods of time are emerging. Since, by the nature of space systems, it is desired that they perform their mission flawlessly and also it is of extreme importance to have fault-tolerant sensor/actuator sub-systems for the purpose of validating science measurement data for the mission success. Technology innovations attendant on autonomous data validation and health monitoring are articulated for a growing class of autonomous operations of space systems. The greatest need is on focus research effort to the development of a new class of fault-tolerant space systems such as attitude actuators and sensors as well as validation of measurement data from scientific instruments. The characterization for the next step in evolving the existing control processes to an autonomous posture is to embed intelligence into actively control. modify parameters and select sensor/actuator subsystems based on statistical parameters of the measurement errors in real-time. This research focuses on the identification/demonstration of critical technology innovations that will be applied to Autonomous Spacecraft Health Monitoring/Data Validation Control Systems (ASHMDVCS). Systems (ASHMDVCS).

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.10
• /
• pp.831-835
• /
• 2020

By automatically generating HDL codes from C/C++ source codes, HLS makes it possible to shorten FPGA system developing period through easy timing control and structure change. We designed LDPC encoder for telemetry standard 106-17 with Xilinx Vivado HLS and showed hardware structure can be easily adapted for different purposes through minor C code modification. Synthesis results targeting Spartan-7 xc7s100 device are presented for throughput and hardware complexity comparison.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.1C
• /
• pp.45-49
• /
• 2004

An image enhancement method using modified anisotropic diffusion filter is proposed in this paper. It employs sensor noise estimation and scale space methods based on the minimum reliable scale. Then the anisotropic diffusion filter is modified by the calculated critical value function and local gradient. Through simulation, it is verified that the proposed algorithm has the capability of little or no noise amplification in homogenous region as well as superior edge enhancement.