• Journal of Korean Vacuum Science & Technology
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• v.3 no.1
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• pp.59-65
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• 1999

There has been an interest to develop an efficient, compact microwave device using field-emitter-arrays (FEA)-based cathode. Toe valuate the optimum device-efficiency in a compact size, the propagation properties of the premodulated electron beam for the FEA-based cathode is studied in detail by the computer simulation using a PIC code, MAGIC. For the premodulated electron beam whose phase of the energy leads the phase of the current by $\pi$/2, the amplitude of the downstream current modulation can be kept as high as the initial modulation level. Using the beam parameters with the beam voltage of 6kV and the current of 2.0A, 30% of efficiency is predicted when the quality factor of 800 is chosen. the device length is reduced about twice compared with that of the conventional device. The design of practical planar cathode is carried out to meet the minimum diameter of the electron beam as 0.5 mm.

• 전기의세계
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• v.27 no.3
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• pp.36-42
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• 1978

It has been investigates that electric characteristics of plasma electron beam in N$_{2}$, H$_{2}$ and Ar gas jars under various gas pressures during electron beams are formed. The results are as follows: 1)Electron beam is formed in the region of positive resistance on the characteristic curve. This phenomenon is identical in N$_{2}$, H$_{2}$ and Ar gases. 2)But in Ar gas, electron beam is formed at relatively lower gas pressure than in H$_{2}$ and N$_{2}$. 3)In pure gas either N$_{2}$, H$_{2}$ and N$_{2}$ the lower the gas pressure, the higher the voltage drop for the same electron beam current. 4)The region in which electron beam is formed is limited at a given pressure. 5)Beyond the limit mentioned above, it becomes glow discharge state and the current increases radically. 6)At a given gas pressure, electron beam voltage, that is, electrical power input increases with gap length.

• Journal of Welding and Joining
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• v.2 no.1
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• pp.25-29
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• 1984

In order to investigate the predominant factors which determine penetration depth and bead width in electron beam welding, bead-on-plate welding was carried out using 7075-T6 Al alloy. The results obtained from the present experiments can be summarized as follows; 1) With increasing accelerating voltage, bead width (B.W) decreases but penetration increases remarkably. 2) Increasing beam current results in increase of bead width and penetration respectively, and decrease of the ratio of penetration increment to beam current increment. 3) With increasing welding speed penetration decreases remarkably, while bead width creases.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.262-269
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• 2013

Though focused ion beam (FIB) is one of the candidates to fabricate the nanoscale patterns, precision milling of nanoscale structures is not straightforward. Thus this poses challenges for novice FIB users. Optimal determination in FIB parameters is a crucial step to fabricate a desired nanoscale pattern. There are two main FIB parameters to consider, beam current (beam size) and dose (beam duration) for optimizing the milling condition. After fixing the dose, the proper beam current can be chosen considering both total milling time and resolution of the pattern. Then, using the chosen beam current, the metal nano hole structure can be perforated to the required depth by varying the dose. In this experiment, we found the adequate condition of $0.1nC/{\mu}m^2$ dose at 1 pA Ga ion beam current for 100 nm thickness perforation. With this condition, we perforated the periodic square array of elliptical nano holes.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.263-265
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• 2005

In the alternative current plasma display panel(AC-PDP) technology, it is very important to remove the image sticking for improving an image quality. In this paper, we have investigated the driving method of alternative current plasma display panel(AC-PDP) for preventing image sticking. We have investigated the driving method of alternative current plasma display panel(AC-PDP) for preventing image sticking. The preventing method of image sticking was proposed by adopting the Sticking Remove Pulse(SRP). The variation of brightness is most affected by the MgO to be formed at the surface of the phosphor layer. As a result, the image sticking is reduced when the driving method adopted an SRP.

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.49-49
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• 1996

• Interaction and multiscale mechanics
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• v.3 no.3
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• pp.257-266
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• 2010

A novel resonance based proximity DC current sensor is proposed. The sensor consists of a piezo sensed and actuated cantilever beam with a permanent magnet mounted at its free end. When the sensor is placed in proximity to a wire carrying DC current, resonant frequency of the beam changes with change in current. This change in resonant frequency is used to determine the current through the wire. The structure is simulated in micro and meso scale using COMSOL Multi physics software and the sensor is found to be linear with good sensitivity.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.425-430
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• 2002

This thesis is a study on behavior for anchorage zone in prestressed double T beam using strut-tie model. Stress conditions of Anchorage zone in prestressed double T beam are very disturbed because large concentrated forces act on relatively small areas. Hence, anchorage zone must be considered in Design of prestressed double T beam. If irrational design or irrational construction be conducted, that may lose stability in capacity as structure. In current design practice, certain parts of structure are designed with extreme accuracy, while anchorage zone in prestressed double T beam is designed using common sense, and experience. Therefore, it is generally very conservative. For that reason, logical, reasonable concept and accuracies are desired at design of anchorage zone in prestressed double T beam. Strut-tie method satisfies those desires. In this thesis, anchorage zone in prestressed double T beam is analyzed by considering prestressing forces. Strut-tie model is constructed based on principle stress trajectory obtained from 3D-finite element analysis in anchorage zone, and amounts of reinforcement be obtained. Results of analysis are compared with the way used in current design practice, and this thesis presents that strut-tie model can be an economical design than current design methods without losing the degree of safety.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.171-176
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• 2004

A light deflector integrated laser diode(LD) was fabricated and the characteristics of LD and ourput beam deflection as a function of deflector injection current were measured. To integrate the deflector with LD, a passive waveguide was integrated with the LD and a triangular-type light deflector was fabricated on the upper clad of the passive waveguide section. Light deflection from the fabricated light deflector is controlled by the effective refractive index variation induced by carrier injection. To characterize the effect of the deflector injection current, threshold current, slope efficiency, and output beam spectrum were measured as a function of deflector injection current. From these measured data, the increment in the threshold current and the decrement of the slope efficiency were observed. However, the output beam spectrum was not affected by the deflector. The Beam Propagation Method(BPM) was used to simulate the proposed device and the light deflection was measured by the far-field pattern of the output beam as a function of the deflector injection current. In the fabricated deflector integrated LD, the deflection angle of 1.9$^{\circ}$ at the injection current of 15 ㎃ was obtained.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1609-1611
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• 2001

A large cross-section pulsed electron beam generator of cold cathode type has been developed for industrial applications, for example, waste water cleaning, flue gas cleaning, and pasteurization etc. The operational principle is based on the emission of secondary electrons from cold cathode when ions in the plasma hit the cathode, which are accelerated toward exit window by the gradient of an electric potential. The conventional electron beam generators need an electron scanning beam because the small cross section thermal electron emitter is used. The electron beam of large cross-section pulsed electron beam generator do not need to be scanned over target material because the beam cross section is large by 300$cm^2$. We have fabricated the large cross-sectional pulsed electron beam generator with the peak energy of 200keV and beam diameter of 200mm and obtained the large area electron beam in the air. The electron beam current has been investigated as a function of accelerating voltage, glow discharge current, helium pressure, distance from the exit window and radial distribution in front of the exit window.