• Journal of the Korean Ceramic Society
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• v.37 no.7
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• pp.686-692
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• 2000

Tin-doped In2O3 (ITO) films were fabricated using a d.c. magnetron reactive sputteirng of a In-10 wt% Sn alloy target in an Ar and O2 gas mixture. To understand the behavior of the carrier mobility in ITO films with O2 partial pressure, the resistivity, carrier concentration and mobility, film density, and intrinsic stress in the films were measured with O2 partial pressure. It was found experimentally that the carrier mobility increased rapidly as the film density increased. In the ITO film with the density close to theoretical one, the mean free path was the same as the columnar diameter. This indicated that the mobility in ITO films was strongly influenced by the crystall size. However, in the case where the film density was smaller than a theoretical density, the mean free paths were also smaller the columnar diameter. It was analyzed that the electron scattering at pores and holes within the crystalline was the major obstacle for electron conduction in ITO films. The measurement of intrinsic stress in ITO films also made it clear that the density of ITO films was controlled by the bombardment of oxygen neutrals on the growing film.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.96-97
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• 2012

In nitride and oxide film deposition, sputtered metals react with nitrogen or oxygen gas in a vacuum chamber to form metal nitride or oxide films on a substrate. The physical properties of sputtered films (metals, oxides, and nitrides) are strongly influenced by magnetron plasma density during the deposition process. Typical target power densities on the magnetron during the deposition process are ~ (5-30) W/cm2, which gives a relatively low plasma density. The main challenge in reactive sputtering is the ability to generate a stable, arc free discharge at high plasma densities. Arcs occur due to formation of an insulating layer on the target surface caused by the re-deposition effect. One current method of generating an arc free discharge is to use the commercially available Pinnacle Plus+ Pulsed DC plasma generator manufactured by Advanced Energy Inc. This plasma generator uses a positive voltage pulse between negative pulses to attract electrons and discharge the target surface, thus preventing arc formation. However, this method can only generate low density plasma and therefore cannot allow full control of film properties. Also, after long runs ~ (1-3) hours, depends on duty cycle the stability of the reactive process is reduced due to increased probability of arc formation. Between 1995 and 1999, a new way of magnetron sputtering called HIPIMS (highly ionized pulse impulse magnetron sputtering) was developed. The main idea of this approach is to apply short ${\sim}(50-100){\mu}s$ high power pulses with a target power densities during the pulse between ~ (1-3) kW/cm2. These high power pulses generate high-density magnetron plasma that can significantly improve and control film properties. From the beginning, HIPIMS method has been applied to reactive sputtering processes for deposition of conductive and nonconductive films. However, commercially available HIPIMS plasma generators have not been able to create a stable, arc-free discharge in most reactive magnetron sputtering processes. HIPIMS plasma generators have been successfully used in reactive sputtering of nitrides for hard coating applications and for Al2O3 films. But until now there has been no HIPIMS data presented on reactive sputtering in cluster tools for semiconductors and MEMs applications. In this presentation, a new method of generating an arc free discharge for reactive HIPIMS using the new Cyprium plasma generator from Zpulser LLC will be introduced. Data (or evidence) will be presented showing that arc formation in reactive HIPIMS can be controlled without applying a positive voltage pulse between high power pulses. Arc-free reactive HIPIMS processes for sputtering AlN, TiO2, TiN and Si3N4 on the Applied Materials ENDURA 200 mm cluster tool will be presented. A direct comparison of the properties of films sputtered with the Advanced Energy Pinnacle Plus + plasma generator and the Zpulser Cyprium plasma generator will be presented.

• Journal of the Korean Statistical Society
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• v.24 no.1
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• pp.233-242
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• 1995

In this paper we will prove the existence and uniqueness of the smoothest density with prescribed moments. The space of functions considered is the Sobolev space $W^2_m[0,1]$ and the target functional to be minimized is the seminorm $$\mid$$\mid$f^{(m)}$\mid$$\mid$_{L^2}$, which measures the roughness of the function f.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.474-477
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• 1989

The PDA (Probabilistic Data Association) Filter proposes a new approach to the problem of tracking when the source of the measurement data is uncertain. The PDA filter shows good simulation results in a known clutter density. In this paper the PDA filter has been modified so that it can be applied when the clutter density is not known.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.167-168
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• 2018

Recently high magnetic flux is used for water treatment and medical treatment. The magnetic flux density reaches up to several Tesla. In this paper, high magnetic flux generator and detector are investigated. The target flux density is 7 Tesla. Proto-types are made and tested.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.50-50
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• 2011

The aluminum nitride films were prepared by RF magnetron sputtering using an AlN ceramic target. The crystallinity, grain size, Al-N bonding and thermal conductivity were investigated in dependence on the plasma power densities (4.93, 7.40, 9.87 W/$cm^2$) during sputtering. High thermal conductivity is important properties of A1N passivation layer for functioning properly in thermal inkjet printhead. The crytallinity, grain size, Al-N bonding formation and chemical composition were observed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The AlN thin film was changed from amorphous to crystalline as the power density was increased, and the largest grain size appeared at medium power density. The near stoichiometry Al-N bonding ratio was acquired at medium power density. So, we know that the AlN thin film had better thermal conductivity with crystalline phase and near stoichometry Al-N bonding ratio at 7.40 W/$cm^2$ power density.

• Phonetics and Speech Sciences
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• v.4 no.2
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• pp.3-20
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• 2012

The purpose of this study was to investigate whether a segmentation unit for a Korean noun is a 'syllable' and whether the process of segmenting spoken words occurs at the lexical level. A syllable monitoring task was administered which required participants to detect an auditorily presented target from visually presented words. In Experiment 1, syllable neighborhood density of high frequency words which can be segmented into both CV-CVC and CVC-VC were controlled. The syllable effect and the neighborhood density effect were significant, and the syllable effect emerged differently depending on the syllable neighborhood density. Similar results were obtained in Experiment 2 where low frequency words were used. The significance of word frequency effect on syllable effect was also examined. The results of Experiments 1 and 2 indicated that the segmentation unit for a Korean noun is indeed a 'syllable', and this process can occur at the lexical level.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1577-1583
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• 2012

Penetrator with enhanced lateral effect (PELE) is a novel projectile that does not require dynamite and a fuse. It comprises a high-density jacket that is closed at its rear end and filled with a low-density filling material. To study the explosion characteristics of PELE using AUTODYN-3D code, the calculation models of the projectile body and the bullet target were developed and the process of penetrating an aluminum-2024 alloy target using PELE was simulated. The scattering characteristics after PELE penetrated the aluminum-2024 alloy target were studied for different filling materials. The explicit finite element analysis of PELE fragmentation was implemented with the stochastic failure criterion in AUTODYN-3D code. As the filling expanded, the fragments gained velocity and dispersed laterally, increasing the damage area considerably. The number and shape of PELE fragments differed depending on the impact pressure of the filling that fragmented during the penetration and lateral dispersion processes.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.223-230
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• 2014

This study examined emission characteristics of far-infrared ray, formaldehyde, volatile organic compounds and deodorization rate of particleboard prepared at different target board densities and resin content levels, using the xylem part of Broussonetia Kazinoki Sieb. The deodorization rate increased, as the target density of board and resin content increased. Emission rates of the far-infrared ray and total volatile organic compounds (TVOCs) were 0.892~0.899, and $0.074mg/m^2{\cdot}h$ for particleboard prepared with the resin content of 13% and target density of $0.6g/cm^3$ while the deodorization rate was 80~90% for the same particleboard. The formaldehyde emission factor ranged from $0.004mg/m^2{\cdot}h$ to $0.006mg/m^2{\cdot}h$ for all particleboard fabricated at different resin content and target densities. These results indicate that particleboard prepared from the xylem part of Broussonetia Kazinoki Sieb have a potential as a building construction material.

• Journal of the Korean Wood Science and Technology
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• v.30 no.3
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• pp.48-58
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• 2002

This study was carried out through scanning electron microscopy to elucidate the mechanism of thickness swelling in wood particle-polypropylene composite which is a typical way of using wood and plastic materials. For this purpose, control particleboards and nonwoven web composites from wood particle and polypropylene fiber formulations of 100:0, 70:30, 60:40, and 50:50 were manufactured at target density levels of 0.5, 0.6, 0.7, and 0.8 g/cm³. Their water absorption and thickness swelling were tested according to ASTMD 1037-93 (1995). To elucidate thickness swelling mechanism of composite through the observation of morphological change of internal structures, the specimens before and after thickness swelling test by 24-hour immersion in water were used in scanning electron microscopy. From the scanning electron microscopy, thickness swelling of composite was thought to be caused by the complicated factors of degree of built-up internal stresses by mat compression and/or amount of wood particles encapsulated with molten polypropylene fibers during hot pressing. In the composites with wood particle contents of 50 to 60% at target densities of 0.5 to 0.8 g/cm³ and with wood particle content of 70% at target densities of 0.5 to 0.7 g/cm³, thickness swellings seemed to be largely dependent upon the restricted water uptake by encapsulated wood particles with molten polypropylene fibers. Thickness swelling in the composite with wood particle content of 70% at target density of 0.8 g/cm³, however, was thought to be principally dependent upon the increased springback phenomenon by built-up internal stresses of compressed mat.