• 전기의세계
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• v.26 no.3
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• pp.76-83
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• 1977

The choice of control method and circuit must be decided after a broad inspection with the characteristics of load and control elements as well as that of electric and mechanical nature. In the present study, Pulse width modulated(PWM) SCR chopper was chosen and for the electric commutation, Jones' forced method was taken bacause of its having enough reverse bias energy. Objectives of experimentation by this system are; 1) the condition of SCR as a gate trigger pulse. 2) the observation of phenomena at the time of forced commutation 3) the experimentation on characteristics of speed control by PWM chopper. Above experimentation shows good characteristics, however, in the limit of narrow gap between the ON and OFF pulses, a complete control was not possible. So, that must be the point to be studied further alone with the harmonics influence.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.154-160
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• 1998

This study describes a theoretical and experimental investigation of gas wave propagation in the pipe system. Most calculations of compressible flows in the pipe have been based on the method of characteristics. This technique has propensity to truncate waves and is difficult to apply to non-perfect gas. A method that describes the application of a two-step Lax-Wendroff acheme to solution of the unsteady one-dimentional flow in the pipe was developed. Theoretical calculations using both the method of characteristics and the two-step Lax-Wendroff method are presented including a realistic model for heat transfer and friction processes. In the present work, account is taken of the nonlinear behavior. For sections of parallel pipe, an one dimensional unsteady homentropic analysis is employed, and a numerical solution is obtained with the aid of a digital computer, using the method of characteristics and two-step Lax-Wendroff method. This analysis is then combined with boundary models, based on a quasi-steady flow approach, to give a complete treatment of the flow behavior in the pipe system.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.94-98
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• 2002

The Partial breakdown (PBD) and complete breakdown (BD) voltage characteristics in a composite insulation system of glass fiber reinforced plastics (GFRP) and liquid nitrogen are investigated to find the PBB and BD characteristics in solenoid type high temperature superconducting (HTS) coils at quench. The electrode system used is made from a coaxial spiral coil-to-cylindrical electrode with an insulation barrier and spacers, and is immersed in liquid nitrogen. A heater is mounted inside the coil electrode to generate boiling which occurs on quenched superconducting coils. The experimental results show that: (1) breakdown voltages are affected severely by the risetime of the applied voltage and the PBD inception voltage, (2) two kinds of BD mechanisms are found depending on the shape of the spacer, length of cooling channel and heater power.

• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.79-85
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• 2000

Press-fit pin connection is the solderless interference-fit between pins and plated through holes(PTH) in the printed curcuit board(PCB). Because of not only its simple assembly and absence of problems associated with soldering, but also its good mechanical and electrical characteristics, the press-fit pin connection technology has quickly gained wide acceptance in the telecommunications and computer industries. In this paper, the contact stress characteristics of the domestic CPF pin when inserted into the friction coefficients were compared and the stress variations of the compliant part of the pin, which have an influence on the performance, were displayed with the time and arc length after complete connected. It is supposed that the results will provide useful data to improve the performance of the pin-PCB interconnection mechanism.

• Journal of Drive and Control
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• v.12 no.1
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• pp.21-27
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• 2015

Pneumatic cylinders are classified into rod-type pneumatic cylinders and rodless pneumatic cylinders depending on the presence of the rod. Rodless cylinders have a constant area and have no deflection. Rodless cylinders are widely used in automatic systems requiring high-speed performance and high-precision transportation. However, the research of the pneumatic cylinder has been focused on the structure and life characteristics. In this research, aging characteristics and shape parameter analysis which are related to the lifetime were investigated. By conducting the lifetime tests with two different materials for the transfer plate, the failure mode and lifetime characteristics were analyzed. By the Anderson-Darling (A-D) verification based on the complete data set, the analysis results of lifetime distribution, shape parameter, and scale parameter were provided.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2895-2898
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• 2009

The complete structural characterization of dehydrodivanillin, an important natural product of interest to the food, cosmetics and aroma industries, has been carried out using multi-dimensional NMR spectroscopic techniques, and its previously $reported^{13}$C-NMR values have been reassigned. Dense and granular thin films of dehydrodivanillin have been grown by sublimation under high vacuum and studied using Scanning Electron Microscopy (SEM), electrical and optical techniques. The transmittance spectra of the films indicate a wide optical band gap of more than 3 eV. Typical J-V characteristics of Glass/ITO/dehydrodivanillin/Al structure exhibited moderate current densities ${\sim}10^{-4}\;A/cm^2$ at voltages > 25 V with an appreciable SCLC mobility of the order of $10^{-6}\;cm^2$/V-s.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.70-75
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• 1997

Power driving shaft systems with reduction gear are frequently equipped with elastic couplings to protect reduction gears and to relieve the torsional vibration problems. In this study, torsional vibration characteristics for the engine shafting system with elastic couplings are investigated and the calculating program is developed. It is confirmed that torsional vibration can be controled by careful selection of a elastic coupling with suitable characteristics and the suitability of a elastic coupling can only be determined as a result of a complete torsional vibration analysis including engine conditions such as misfring for shafting system.

• Journal of Information Processing Systems
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• v.18 no.1
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• pp.89-96
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• 2022

A novel multistage pulse jamming suppression algorithm was proposed to solve the anti-pulse jamming problem encountered in navigation receivers. Based on the characteristics of the short duration of pulse jamming and distribution characteristics of satellite signals, the pulse jamming detection threshold was derived. From the experiments, it was found that the randomness of pulse jamming affects jamming suppression. On this basis, the principle of the multistage anti-pulse jamming algorithm was established. The effectiveness of the anti-jamming algorithm was verified through experiments. The characteristics of the algorithm include simple determination of jamming detection threshold, easy programming, and complete suppression of pulse jamming.

• Korean Institute of Interior Design Journal
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• no.38
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• pp.38-47
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• 2003

This study is one of studies which refer aesthetic characteristics and relationship about Korean traditional architecture. In this rapidly changing society, it is worthy to recognize our traditional aesthetics from which we may get a solution for improving our surrounding. The major purpose of this study was to present a holistic framework to understand aesthetics of Korean traditional architecture in a viewpoint of relationship. As a secondary purpose with this framework, Gyeongbokgung which is one of Korean traditional palaces in Chosen dynasty was analyzed and appropriate case example images were gained. Through this process, the framework could get better capability to persuade relativity of this study by showing relevant example. Through the purpose, the uniqueness of this study were like following; First, it referred a word 'relationship' clearly and exposed it to a systematic framework. Second, it referred space characteristics and aesthetics characteristics of Korean traditional architecture synthetically comparing with that other literatures referred the characteristics partially focused on their interests. Third, many literatures showed the characteristics partially by some case examples and photos but, it showed a complete case example and appropriate photos to endow persuasive power for understanding the framework.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.6
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• pp.10-15
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• 1977

This paper proposes a simple and systematic method for the generation of the fault detection test sets for the combinational logic networks. Based on tile path sensitizing concept, the test patterns for the primary input gates of the network are defined, and then it is shown that, arranging these predefined test patterns according to the path sensitizing characteristics of the given network sturctures, the minimal complete test sets for the fan-out free combinational networks can be found easily. It is also shown that, taking into account the fan-out paths sensitizing compatibility, the proposed method can be extended to the irredundant reconvergent fan-out networks.