• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.276-278
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• 1997

The reliable etching process is one of the essential steps in fabricating GaN based-device. High etch rate is needed to obtain a deeply etched structure and perfect anisotropic etched facet is needed to obtain lasing profile. In the research, therefore, we had proposed a planar inductively coupled plasma etcher (Planar ICP Etcher) as a high density plasma source, and studied the etching mechanism using the $CH_4/H_2$/Ar gas mixture. Dry etching characteristics such as etch rate, anisotropic etching profile and so on, for the III-V nitride layers were investigated using Planar ICP Etcher, based on the plasma characteristic as a variation of plasma process parameters.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.1
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• pp.8-14
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• 2004

An O-mode Ultrashort Pulse Reflectometry (USPR) system has been designed and developed for the measurement of electron density profiles on the Sustained Spheromak Physics Experiment (SSPX) spheromak. In the original design of SSPX, peak densities were envisioned to be in the range of 0.5-3${\times}$10$^{14}$ cm$^{-3}$ . The total duration of formation and sustained discharges is typically ∼2 msec. Moreover, diagnostic access on SSPX is severely restricted. Such high density and short duration plasmas coupled with stringent diagnostic access are quite challenging for conventional reflectometer systems. In USPR, the SSPX diagnostic requirements have been successfully satisfied by employing up-converting mixers and monostatic horn/waveguide configuration. As a result, the USPR system has proven its applicability for the density measurement of a future fusion device. In the density profile measurements, the USPR system is capable of routinely generating density profiles with a temporal resolution of 57 $\mu$s. This paper presents details regarding the USPR fundamental principles, associated subsystems and laboratory tests as well as the experimental results obtained on SSPX

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2399-2411
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• 1995

Crane operation for transporting heavy loads inherently causes swinging motion at the loads due to crane's acceleration or deceleration. This motion not only lowers the handling safety but also slows down the handling process. To complement such a problem, Korea Atomic Energy Research Institute(KAERI) has designed several anti-swing controllers using open loop and closed loop approaches. They are namely a pre-programmed feedback controller and a fuzzy controller. These controllers are implemented on a 1-ton crane system at KAERI and their control performances are compared. Test operations show that the new controllers are superior to that of conventional cranes in terms of robustness to the disturbances and adaptation capability to the change of rope length.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.9
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• pp.739-745
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• 1998

The objective of this paper is to provide experimental data of Er(rare- earth)doped $SiO_2$thin film made by sputtering methods. The deposition rate of silica glass by sputtering method was 55$\AA$/min. In EDD measurements, the average Er concentration in the deposited film was 0.77(wt%). After annealing at $900^{\circ}C$, the Cl concentration decreased from 3.79(wt%) to 1.52(wt%). The refractive indices of the core $n_1$, cladding $n_2$ were 1.458, 1.558 respectively at 632.8 nm. The refractive index difference between core and cladding, $\Delta$n was 0.1. The refractive index profile of core and cladding interface shows step profile. In the study, $SiO_2$ glass films of Si wafer were successfully doped with active erbium. Therefore, this experimental data will be applicable for fabrications of Er doped planar integrated optical device.

• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.146-151
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• 2009

A Gaussian beam of single mode fiber laser was changed into a ring-shaped pattern after it was transmitted through the hollow optical fiber. The ring-shaped beam was focused on a plane by an f-. lens and it was scanned by a Galvano-mirror. The spatial profile of laser energy incident on a plane had two peaks at both sides of the scanned linear track. The profile was compared with the result obtained when the Gaussian beam was dithered transversely by an acousto-optic modulator. It is found that hollow optical fiber beam shaper can replace acousto-optic beam dithering device which is employed in a laser induced thermal printing system.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.115-120
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• 2006

A Korean Road Roughness Classification(KRC) method is proposed. Using a dynamic road profiling device equipped with the Accelerometer Established Inertial Profiling Reference(AEIPR) method, road profile measurement is performed on various types of public paved roads in Korea. The road profiling data are processed to classify the characteristics of Korean road roughness. The resultant Korean road roughness classification(KRC) is shown different characteristics compared to the road classification proposed by ISO, MIRA, and Wong. The proposed KRC is composed of 8 classes(A-H, very good-poor) based on the power spectral density and is in good agreements with the characteristics of Korean paved road roughness and can be used well in vehicle ride comfort simulation using domestic road profile.

• Journal of Welding and Joining
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• v.20 no.1
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• pp.69-75
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• 2002

This study investigated the effect of the system parameters on penetration depth measurement using infrared temperature sensing system. The distance from focusing lens to detector was varied to diminish the error in measuring weld bead width. The effect of bead surface shape on measured surface temperature profile was evaluated using specimen heated by electric resistance. The measuring distance from laser beam was changed to optimize the measuring point. The results indicated that the monitoring device of surface temperature using infrared detector array was applicable to real time penetration depth control.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.138-142
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• 2019

As the NAND flash memory goes to 3D vertical Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) structure, the lateral charge migration can be critical in the reliability performance. Even more, with miniaturization of flash memory cell device, just a little movement of trapped charge can cause reliability problems. In this paper, we propose a method of predicting the trapped charge profile in the retention mode. Charge diffusivity in the charge trapping layer (Si₃N₄) was extracted experimentally, and the effect on the trapped charge profile was demonstrated by the simulation and experiment.

• Korean Journal of Metals and Materials
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• v.47 no.5
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• pp.311-315
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• 2009

2-dimensional (2D) dopant profiling in semiconductor device was carried out by electron holography and scanning capacitance microscopy methods with the same multi-layered p-n junction sample. The dopant profiles obtained from two methods are in good agreement with each other. It demonstrates that reliability of dopant profile measurement can be increased through precise comparison of 2D profiles obtained from various techniques.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.1
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• pp.99-111
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• 2010

Recently, a very large vessel's maneuvering performance, rudder performance and rudder design's importance is considered to be an important subject. There have been few studies on the design process of rudder device before. The aim of this paper is to investigate a design process of rudder device and to propose a generalized design process of rudder device. Firstly, we investigated the rudder device design process of Korean major shipyards. And the differences of a torque calculation method, rudder section design, maneuvering performance examination method, etc were analyzed theoretically. Secondly, the design process of rudder device was divided into concept design, initial design and detail design. In concept design, a rudder area was estimated and its validity was examined. In initial design, rudder profile and design method has been selected through rudder form determination process. And principal dimension and steering gear capacity were determined. Maneuvering performance was also examined by simulation tool. In detail design, design criteria considered in rudder initial design has been investigated thoroughly. Also a rudder torque, rudder cavitation performance and rudder structure analysis were estimated. And maneuvering performance was also examined by model test. Finally, based on the results of investigation, the design process of rudder device was generalized and proposed.