• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.1
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• pp.53-63
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• 1994

The conventional cold-heading process for the production of a bolt-shaped product is composed of some process and two or three blows heading. The strength of a bolt-shaped product produced by multi-blow heading depends on the working conditions of the heading process such as preforming die angle, corner-radius of the necked portion of product, and the reduction in height during pre-forming. Arigid-plastic finite-element program(RDHPSC) has been coded and the program testified by comparison with the results of experimentation. A method of testing the optimum die-conditions in the double-blow heading process by use of RDHPSC analysis is discussed a fundamental structures of CAD/CAPP system for two-blow heading process is discussed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.216-225
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• 2023

This paper describes the finite element analysis and die design change of cold heading punching process to increase the cold forging tool life and reduce the tool wear and stress concentration. Through this study, the optimization of punch tool design has been studied by an analysis of tool stress and wear distribution to improve the tool life. Plastic deformation analysis was carried out in order to understand the cold heading process between tool and workpiece stress distribution. Cold heading punch die design was set up to each process with different four types analysis progressing, the cold heading punch dies shapes with combination of point angle and punch edge corner radius shapes of cold forging dies, punch die material properties and frictional coefficient. The design parameters of point angle and corner radius of punch die geometry, die material properties and frictional coefficient were selected to apply optimization with the DoE (design of experiment) and Taguchi method. DoE and Taguchi method was performed to optimize the cold heading punch die design parameters optimization for bolt head cold forging process, it was possible to expect an reduce the cold heading punch die wear to the 37 % compared with current using cold heading punch in the shop floor.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.4
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• pp.29-35
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• 2008

In this paper, a new guidance law to reduce sensitivity to the initial heading errors is proposed. In order for shaping the input weights over the flight, we introduce the distribution functions expressed in terms of time-to-go and its inverse term. By applying the optimal control theory with the synthesized weights, the homing guidance law is derived. Also the characteristics of the proposed law are examined. Various computer simulations show the good performance of the proposed guidance.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.95-102
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• 2016

Geomagnetic sensors are widely utilized for sensing heading direction of quadrotors. However, measurement from a geomagnetic sensor is easily corrupted by environmental magnetic field interference and roll/pitch directional motion. In this paper, a measurement method of a quadrotor heading direction is proposed for application to yaw attitude control. In order to eliminate roll/pitch directional motion effect, the geomagnetic sensor data is compensated using the roll/pitch angles measured for stabilization control. In addition, yaw-directional angular velocity data from a gyroscope sensor is fused with the geomagnetic sensor data using a complementary filter which is a simple and intuitive sensor fusion method. The proposed method is applied to experiments, and the results are presented to prove validity and effectiveness of the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.1
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• pp.25-32
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• 2010

With the latest automobile technology, though the third generation common rail system requires high injection pressures up to 1,800bar, the next generation diesel engine is expected to require more higher pressures than the third generation. The common rail pipe requires higher strength because it is one of the parts in the common rail system, which is influenced directly by fuel under high pressure. Preform design is very important for preventing head of the common rail pipe from folding in the heading process. In this study, die angle, curvature, outer diameter of die and length of trapped part are selected as main parameters to obtain best preform shape minimizing radius of folding. Therefore optimal design is carried out by finite element analysis and Taguchi method through main parameters. Results of the finite element analysis have good agreements with those of the experiments in the actual field.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1373-1378
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• 2007

Metal forming ins the process changing shapes and mechanical properties of the workpiece without initial material reduction through plastic deformation. Above all, because of hot working carried out above recrystallization temperature can be generated large deformation with one blow, it can produce with forging complicated parts or heat resisting super alloy such as Inconel 718 has the worst forgeability. In this paper, we established optimal variation of hot heading precess of the Inconel 718 used in heat resisting component and evaluated mechanical properties hot worked produce. Die material is SKD61 and initial temperature is $300^{\circ}C$. Initial billet temperature and punch velocity changed, relatively. Friction coefficient is 0.3 as lubricated condition of hot working. CAE is carried out suing DEFORM software before making the tryout part, and it is manufactured 150 ton screw press with optimal condition. It is known that forming load was decreased according to decreasing punch velocity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.991-998
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• 2013

The fuel injection pipe of a common rail system used in a clean diesel vehicle plays a role in supplying fuel from a rail to the injector of each cylinder connecting the engine under a repeated internal pressure. The fuel injection pressure is increased to over 200 MPa for satisfying EU emission standards and improving fuel efficiency, and a heading process and an autofrettage process are required for preventing folding defects and improving fatigue life. In this study, the flow stress and SN data of the material of the pipe are obtained through a tensile test and a fatigue test. The heading process for checking the folding defects of pipe ends is performed by using FEA. Furthermore, the optimal design of the autofrettage process for improving fatigue life considering not only the compressive residual stresses of the inner surface but also the tensile residual stresses of the outer surfaces of the pipe under the repeated internal pressure is performed by using FEA. To verify the process design, fatigue analysis for the autofrettaged pipe is performed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.526-528
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• 2012

우리나라 VTS 운영 시스템 중 Norcontrol 장비와 Vissim 장비의 기능 비교를 통해 장 단점을 분석하고 개선 방안을 도출함으로써 관제사가 보다 편리하고 쉽게 기능을 사용하여 해상교통관제업무에 활용할 수 있도록 하기 위함.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.794-798
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• 1995

We performed analysis for crank shaft and connecting rod in driving device of Cold Heading Machine. The results of this study is following ; 1. The nominal pressure is happened at 8mm under bottom dead center. And then the theoretical angel of crank (.theta.) and connecting rod (.phi.) are .theta. = 25 .deg. 1' and .phi.= 6 .deg. 1' but the analysis angel are .theta. = 25 .deg. and .phi.= 7 .deg. 2. The load is loaded at theta. = 51 .deg. in crank angle. 3. The maximum stress of connecting rod is about290MPa. It is exited inner stress range in consideration of safety factor.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.1-2
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• 2011

최근 많은 분야에 무인시스템이 도입되고 있다. 초기에는 산업분야에서 인간이 하기 힘들거나 위험한 작업을 대신하는 단순 반복적인 자동화기술이 대부분이었으나, 최근에는 전자통신 기술발달에 힘입어 무인자동차, 무인항공기, 무인잠수정, 무인선박 등이 연구 개발되고 있다. 본연구에서는 자율형 소형무인선을 개발하고자 하였으며, 이와 관련하여 인터넷기반의 무선통신제어, 동력 추진 조타 냉각시스템, GPS 영상 헤딩센서 등 센싱시스템, 자율운항을 위한 제어기설계, GUI 등을 연구하였다. 아울러, 해상실험을 통해 유효성을 검증하였다.