• 전기의세계
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• v.25 no.2
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• pp.55-57
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• 1976

자동차에서 발전기는 engine의 기계적 energy를 전기 energy로 변환시켜 engine의 발동, light, radio및 여러가지 계기등에 전류를 공급하며 잉여전력을 축전지에 저장한다. 이러한 자동차용 발전기는 1900년 중반기까지 직류발전기를 사용하였으나 1960년 초기부터 반도체개발과 더불어 저속출력특성이 우수한 교류발전기와 정류기를 병용하였다. 그러나 1960년 하반기부터는 자동차의 고속화, 차내의 라디오, TV시설, 각종 전자제어장치등의 급속한 발달로 보다 안정도가 높은 전원의 공급이 필요하게 되었다. 또한 자동차사용이 일반화됨에 따라 최소의 유지보수를 요하는 발전기를 추구하게 되었다. 이에 따라 미국, 영국, 불란서 등 선진공업국에서는 브러시가 필요없는 발전기의 개발을 서두르게 되었으며 여러가지 형태의 Brushless generator를 개발하여 현재 사용하고 있다. 종래의 발전기에서 Brush와 slip-ring, 즉 금속의 회전마찰접촉을 통하여 계자권선에 전류가 공급됨으로 이에 따른 성능저하, 접촉부분에서 발생하는 arc로 인한 폭발위험 및 전자장치에 주는 방해, Brush 마모로 인한 유지보수등의 단점을 주고 있다.

• Journal of the Korean Geotechnical Society
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• v.29 no.5
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• pp.39-52
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• 2013

The shear stress characteristics of landslide materials can be affected by various factors. We examined the shear stress characteristics of two different soils using ring-shear apparatus, in which saturation-consolidation-shearing speed can be easily controlled. This paper presents (i) shear stress-time characteristics, (ii) shear stress depending on normal stress and shear speed and (iii) shear stress as a function of shearing speed. Materials used in this paper were the Nakdong River sand and muds taken from Jinhae coastal area in Korea. Samples were prepared in three types: Sand (upper)-Sand (lower), Clay (upper)-Clay (lower) and Sand (upper)-Clay (lower). The upper and lower indicate the samples placed in upper and lower ring shear boxes, respectively. For given normal stresses (50 and 100 kPa) and shearing speed (0.1 mm/sec), we performed ring shear tests. Then the failure lines were determined in the second test. Last, we determined the shear stress characteristics depending on different shearing speeds, such as 0.01, 0.1, 1, 10, 100 mm/sec. As a result, we found that shear stress characteristics are strongly dependent on above three factors. The shear stress of Sand (upper)-Clay (lower) is smaller than that of Sand (upper)-Sand (lower), but slightly larger than that of Clay (upper)-Clay (lower). The shear stress is also characterized by grain crushing and wetting process at slip surface.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.3
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• pp.237-242
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• 2016

The major advantage of slip-ring technology in Spiral CT is that it facilitates continuous rotation of the x-ray tube, so that volume data can be acquired from a patient quickly. Not only for such a fast scan, but also for the dose reduction purpose, high signal-to-noise ratio and fast data acquisition system is required. In this study, we have built a multi-channel photodetector and multi-channel data acquisition system for CT application. The detector module consisted of CdWO4 crystal and Si photodiode in 16 channels. For the performance test of the preamplifier stage, both the transimpedance and switched integrator types are optimized for the photodetector modules. Switched integrator showed better noise performance in the limited bandwidth which is suitable for the current CT application. The control sequence for data acquisition and 20 bit ADC is designed with VHDL(Very High Speed Integrated Circuit Hardware Description Language) and implemented on FPGA(Field Programmable Gate Array) chip. Our Si photodiode detector module coupled to CdWO4 crystal showed comparable signal with other commercially available photodiode for CT. Switched integrator type showed higher SNR but narrower bandwidth compared to transimpedance preamplifier. Digital hardware is designed by FPGA, so that the control signal could be redesigned without hardware alteration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.472-482
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• 2019

This paper describes the stabilization of underwater TAS winch system Deploy/Recover operation performance. TAS winch installed on the stern of submarine performs to deploy/recover sensor, towing cable and rope tail which is deployed from the stern and separated from submarine itself. Also TAS winch provides transmission path of power to the sensor and data transmitting/receiving path which data are acquired from underwater environment like sound, depth and temperature. At the step of TAS winch evaluation test, sporadic standstill and rotating speed oscillation phenomenon were occurred. Winch motor provides the available torque to deploy/recover TAS and root cause analysis to the winch motor was done to find exact reason to sporadic malfunction. When winch motor was disassembled, eccentricity of rotor, slip-ring and the other composition part for winch motor were found. These might cause magnetic field distortion. To make TAS winch system more stable and block magnetic field distortion, this paper suggests methods to enhance fixing status installed in winch motor. For reliable data acquisition for TAS winch operation, the deploy/recover function of the improved type of TAS winch was verified in LBTS making similar condition with sea status. At the end of stage, improved type of TAS winch was tested on some functions not only deploy/recover function, but sustainability of TAS operation on specific velocity, steering angle of submarine in the sea trial. Improved type of TAS winch was verified in accordance with design requirement. Also, validity of suggested methods were verified by the sea trial.

• Economic and Environmental Geology
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• v.26 no.3
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• pp.403-420
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• 1993

The Cretaceous Kyongsang Basin is known to be composed of several tectonic blocks (or subbasins) with each distinct stratigraphic succession. The study area represents a major part of one of these blocks, i. e. the $\check{U}is\check{o}ng$ block. The area is charaterized by a suite of WNW-trending sinistral strike-slip faults as well as a number of ring faults. A total of 292 independently oriented core samples were drilled from 23 sites, covering virtually all the formations of the Cretaceous $Ky\check{o}ngsang$ Supergroup. Alternating field and thermal demagnetization experiments were conducted to reveal the primary magnetization. Due to the homoclinal nature of the strata in the area, it was not possible to make use of the conventional fold test It is, however, believed that the primary remanent components have been obtained from the majority of the formations, considering the similarity of the palaeomagnetic pole positions with those of contemporary strata of other blocks and the existence of antiparallel reversed remanence. It was found neither any significant difference in magnetic declination on each side of the strike-slip faults nor systematic change of magnetic declination with distance from the fault-line. This does not support such a block rotation hypothesis associated with the strike-slip faulting in the area as alleged by some authors. The samples from the outcrops on or near the fault-lines were severely overprinted by the recent magnetic fields regardless of age and lithology. Epithermal Au-Ag-Cu-Pb-Zn mineralizations are known along some fault lines in the area. It is interpreted that these two facts are closely related with fluid circulations along the fracture zones caused by fault activities. In regard to the age of the strata as deduced from the magnetostratigraphic consideration, the $Ch\check{o}mgok$ formation and the lower strata should be older than Barremian or 124 Ma. The age of volcanics of the $Yuch^{\prime}\check{o}n$ Group sampled in this study should be younger than Campanian or 83 Ma.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.381-382
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• 2002

The Fluid film between the valve plate and the cylinder block was measured by use of a gap sensor and the mercury-cell slip ring unit under real working conditions. During the operating periods, experiments with discharge pressure, revolution speed, and valve geometry was carried out for the fluid film on the valve plate. To investigate the effect of the valve shape, we designed two valve plates each having a different shape; the first valve plate was a plane valve plate. while the second valve plate was a spherical valve plate. It was noted that these two valve plates observed different aspects of the fluid film characteristics between the cylinder block and the valve plate. The leakage flow rate and the shan torque were also investigated in order to clarify the difference between these two types of valve plates. From the results of this study. we found that the spherical valve plate estimated good fluid film patterns and performance more than the other valve plate in oil hydraulic axial piston pumps.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1993.04a
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• pp.39-53
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• 1993

The minimum oil film thickness(MOFT) in the connecting-rod bering of a 1.5 liter, L-4, gasoline engine is measured up to 5500 rpm and calculated to study the dynamically loaded engine bearing. Short bearing approximation and Mobility method are used for theoretical analysis of oil film charactrtistics. And cylinder pressure, crank-pin surface temperature and bearing tenp ture are measured as the input data of theoretical analysis. The MOFT are measured by the total capacitance method(TCM). To improve the reliability of the test results, a reasonable detmuuination method of bearing clearance is introduced and used, and the effects of cavitation and aeration on the test results are neglected. The crankshaft is grounded by means of a slip ring. A scissor type linkage system was developed to measure the MOFT and bearing temperature. The effects of engine speed, load and oil viscosity on the measured and calculated minimum oil film thicknesses are investigated at 1500 to 5500 rpm. From the comparison between the measured and calculated MOFT, it is found that a qualitative similarity exists between them, but in all cases, the measured MOFT are smaller than those calculated.

• The Journal of Korea Robotics Society
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• v.8 no.4
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• pp.247-255
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• 2013

This paper shows the development of a snake robot (KAEROT-snake V) which consists of 16 1-DOF actuator modules and head module. The modules are connected serially and the joint axis of each module is rotated by $90^{\circ}$ with respect to the previous joint so that the snake robot can move in the 3D space. A tail actuator module includes slip-ring and metal connector. KAEROT-snake IV developed in prior research could move in the 3D space and climb up in a narrow pipe. But its design was not appropriate to the unstructured tough environment and its speed was somewhat slow. A new actuator module is designed to enclose all parts of the module so that any wire is not exposed. The size and weight of the new module was slightly reduced. And the rotation speed and torque of the joint was increased by about twice when compared with pre-module. An embedded controller was developed so small that it can be mounted inside the module. The performance of the developed robot was demonstrated through various locomotion experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.3
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• pp.45-52
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• 2009

Power line communication or power line carrier (PLC) is a system for carrying data on a conductor and can also used for electric power transmission. Now the powers used in the motor drive system are mostly DC sources. Even AC powers in some systems are generated from DC sources by the inverter. It is can be forecasted that the DC-link PLC technology will be widely used in various industrial fields. In this paper a novel BLDC motor control system using ASK DC-link PLC technology is proposed. The characteristic of this system is that the communication only needs 2 DC lines and there are no additional lines to translate the reference signals. The number of signal cables can be minimized when the DC-link PLC method is applied in the multi motor control system and the slip ring design also can be simplified when this method is applied in rotation machines. The proposed motor control system is clarified by the PSIM and MATLAB simulations and tested through the hardware prototype.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.592-594
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• 2008

The powers used in the robot drive motor system are mostly DC sources such as batteries. Even AC powers in some systems are generated from DC sources by the inverter. It is can be forecasted that the DC-link communications will be widely used invarious industrial application. In this paper a novel BLDC motor drive system by using DC-link communications is proposed. The characteristic of this system is the communication only needs 2 DC lines. There are not additional lines to translate the reference signals and the reliability of the system is enhanced especially in some badly circumstance. The number of lines can be least when applied in the multi motor control system and the slip ring design can be simplified when applied as rotation machine. The reasonableness of proposed motor system is clarified by the PSIM simulation and the hardware prototype.