• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.1 s.20
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• pp.29-33
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• 2004

Design of general steel structure had applied to achieve elastic designing concept so far. Because elastic design supposes that whole structure complies with elasticity formula so that achieve via allowable stress of material. It is concept that calculate stress distribution of construction about action external load and estimate load when the maximum stress reaches equally with allowable stress that is established by maximum safety load of the structure. But, absence that compose actuality structure by deal with external load increase small success surrender and structure hardness falls and structure in limited state finally on the whole as showing complicated process by interference between collapse and buckling under compression. Applied ANSYS (elasto-plasticity large deformation finite element method) to be mediocrity finite element program for analysis method and analysis control used in Newton-Raphson method & Arc-length method.

• Nuclear Engineering and Technology
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• v.36 no.4
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• pp.357-363
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• 2004

A prototype long pulse ion source was developed, and the beam extraction experiments of the ion source were carried out at the Neutral Beam Test Stand (NBTS) of the Korea Superconducting Tokamak Advanced Research (KSTAR). The ion source consists of a magnetic bucket plasma generator, with multi-pole cusp fields, and a set of tetrode accelerators with circular apertures. Design requirements for the ion source were a 120kV/65A deuterium beam and a 300 s pulse length. Arc discharges of the plasma generator were controlled by using the emission-limited mode, in turn controlled by the applied heating voltage of the cathode filaments. Stable and efficient arc plasmas with a maximum arc power of 100 kW were produced using the constant power mode operation of an arc power supply. A maximum ion density of $8.3{\times}10^{11}\;cm^{-3}$ was obtained by using electrostatic probes, and an optimum arc efficiency of 0.46 A/kW was estimated. The accelerating and decelerating voltages were applied repeatedly, using the re-triggering mode operation of the high voltage switches during a beam pulse, when beam disruptions occurred. The decelerating voltage was always applied prior to the accelerating voltage, to suppress effectively the back-streaming electrons produced at the time of an initial beam formation, by the pre-programmed fast-switch control system. A maximum beam power of 0.9 MW (i.e. $70\;kV{\times}12.5\;A$) with hydrogen was measured for a pulse duration of 0.8 s. Optimum beam perveance, deduced from the ratio of the gradient grid current to the total beam current, was $0.7\;{\mu}perv$. Stable beams for a long pulse duration of $5{\sim}10\;s$ were tested at low accelerating voltages.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.3
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• pp.115-120
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• 2009

Point-based methods with experienced human operators are processed well in traditional photogrammetric activities but not the autonomous environment of digital photogrammetry. To develop more robust and accurate techniques, higher level objects of straight linear features accommodating element other than points are adopted instead of points in aerial triangulation. Even though recent advanced algorithms provide accurate and reliable linear feature extraction, extracting linear features is more difficult than extracting a discrete set of points which can consist of any form of curves. Control points which are the initial input data and break points which are end points of piecewise curves are easily obtained with manual digitizing, edge operators or interest operators. Employing high level features increase the feasibility of geometric information and provide the analytical and suitable solution for the advanced computer technology.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1850-1852
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• 2002

In this paper, we studies EMTP analysis and characteristics of critical voltage of pulse corona and load impedance on variable electrode length. To obtain a stable Pulse voltage, we designed a compact pulse generator switched MOSFET and tested their characteristics by adjusting electrode length and pulse repetition. As a result, critical voltage of pulse corona and load impedance on increasing electrode length were decreased. These results indicate we can control critical voltage of pulse corona and suppress arc discharging between two electrodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.184-186
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• 2002

In this paper, we studies EMTP analysis and characteristics of critical voltage of pulse corona and load impedance on variable electrode length. To obtain a stable pulse voltage, we designed a compact pulse generator switched MOSFET and tested their characteristics by adjusting electrode length and pulse repetition. As a result, critical voltage of pulse corona and load impedance on increasing electrode length were decreased. These results indicate we can control critical voltage of pulse corona and suppress arc discharging between two electrodes.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.101-106
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• 2002

Requirements to fabrication processes for arc welding of highly loaded thick-walled joint and problems of research and development in term s of the tendency for the modern aircraft structure development are outlined. A justified, choice of the development line of the new promising welding processes for solution of these problems is presented. A complex of new welding processes and technologies for making highly reliable joints with different thickness (up to 120 mm and more) and length of weld (up to 0.1 m; 0.1-0.5 m and more than 0.5 m) has bee developed. It is shown that the possibility to control the heat flow distribution over the groove surface of the welded joints provides for improved reliability. The new welding processes are equipment are effectively used in serial production of the Mykoyan md Sukhoi supersonic aircrafts as well as in AN-124 Ruslan and AN-225 Mriya wide body aircrafts.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.248-248
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• 2000

본 연구는 조선 소조립, 판넬조립 등의 공정에서 발생되는 필렛 용접 부위의 용접 자동화를 위한 로봇 시스템 개발에 관한 연구이다. 조선등의 중공업 분야에서는 작업이 중량이고 대형임에 따라 로봇이 부재의 특정위치로 이동하여 작업해야 한다. 또한 작업대상의 형상이나 치수가 매번 변경됨에 따라 이에 능동적으로 대처할 수 있어야 한다. 본 연구에서는 두 대의 로봇(2대x6축=12축)이 다축 문형 캔트리(4축)에 장착된 조선용 필렛용접 로봇 시스템(16축)을 개발하였다. 필렛용접부재를 중심으로 두 대의 로봇이 양쪽을 동시에 용접하는 방식으로 고속회전토치를 적용하여 위빙동작없이 원하는 용접각장(Leg Length)을 생성할 수 있다. 캔트리 시스템은 PC 기반의 별도 제어기로 구성하여 두 대의 로봇 제어기와 신호 입출력에 의해 동시동작이 가능하도록 하였으며, 작업장에 놓인 부재의 위치오차를 보장하기 위하여 시각센서를 적용하였다. 용접시작점의 위치보정을 위한 시작점 검출을 위해접촉센서(Touch Sensor)를 적용하였으며, 용접선 추적을 위해서 아크센서(Arc Sensor)를 적용하였다. 본 시스템 2000년 1월 제작 설치가 완료되어 현재 성능 테스트가 완료된 상태로 향후 생산현장에 적용될 계획이다.

• Journal of Biosystems Engineering
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• v.13 no.2
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• pp.38-45
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• 1988

This study was intended to develop the system automatically controlling travel direction of combine by means of sensing paddy rows. The control system was composed of three detecting levers having different length, micro-switch, microcomputer and electro-hydraulic control system. Sensor and control system developed was tested to estimate optimum design values and its actual performance as installed in combine. The computer simulation and performance test at simulated and actual field were conducted to test for possibility of practical use. The results of the study arc summarized. as follows: 1. The travel traces of combine hiving the conventional sensor with 2 levers and the new sensor detecting the slope of paddy rows were compared through computer simulation. Turning frequency of combine having new sensor was fewer than that of conventional sensor, but the rate of turning for the combine with new sensor was much greater than that of conventional sensor. 2. As sensor was established behind the tip of divider, the sensor itself well followed paddy rows but the tip of divider did not, resulting in divider being deviated from paddy rows. It was analyzed that the sensor should be attached closer to the tip of divider to have a better performance of the control system. 3. The greater the length of sensor lever for given location of sensor attachment and combine forward speed, the higher sensitivity of turning in control system. Moreover, increasing combine speed resulted in a worse performance of control system following paddy rows. Consequently, it was necessary that an optimum length of sensor attachment and for the range of combine operational speed. 4. Field test of combine installed with the sensor and electro-hydraulic system developed in this study showed that it may be operated smoothly and well behaved to paddy rows to 4th gear of combine speed which was 59cm/s. Consequently. it was concluded that the combine with the guidance control system developed in this study may be successfully used for paddy combining.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.1
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• pp.174-184
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• 1997

A shock wave, being an irreversible process, gives rise to entropy increase. A great deal of effort has been made to control shock wave and boundary layer interaction related to energy losses as well as problems of vibration and noise. In the present study, tests are performed on a roof mounted half circular arc in an indraft type supersonic wind tunnel to evaluate the effects of porosity, length and depth of cavity in passive control of shock wave on the attenuation of shock strength by reviewing the measured static pressures at the porous wall and cavity. Also the flow field is visualized by a Schlieren system. The results show that in the present study the porosity of 8% produced the largest reduction of pressure fluctuations and that for the same porosity, the strength of shock wave decreases with the increasings of the depth and length of cavity.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.4
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• pp.321-327
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• 2012

This paper presents a comparative analysis on three different types of performance indices of obstacle detection for an overlapped ultrasonic sensor ring. Due to beam overlap, the entire sensing zone of each ultrasonic sensor can be divided into three smaller sensing subzones, which leads to significant reduction of positional uncertainty in obstacle detection. First, the positional uncertainty in obstacle detection is expressed in terms of the area of a sensing subzone, and type 1 performance index is then defined as the area ratio of side and center sensing subzones. Second, based on the area of a sensing subzone, type 2 performance index is defined taking into account the size of the entire range of obstacle detection as well as the degree of the positional uncertainty in obstacle detection. Third, the positional uncertainty in obstacle detection is now expressed in terms of the length of the uncertainty arc spanning a sensing subzone, and type 3 performance index is then defined as the average value of the uncertainty arc lengths over the entire range of obstacle detection. Fourth, using a commercial low directivity ultrasonic sensor, the changes of three different performance indices depending on the parameter of an overlapped ultrasonic sensor ring are examined and compared.