• Journal of the Institute of Convergence Signal Processing
• /
• v.15 no.3
• /
• pp.104-111
• /
• 2014

In this paper, we deal with robotic automation for assembling car brake modules. A car brake module is comprises of a torque member, two brake pads, and two pad liners. In the assembly process, brake pads and pad liners are needed to be inserted in a torque member. If we use a typical robotic hand for the assembly, task time takes too long. So, we propose two methods. The first method is to use an end effector that has five grippers capable of gripping five assembly parts. In the first method we attached the implemented end effector to a conventional 6 degrees of freedom industrial manipulator and performed the bake module assembly task. Experimental results show that the task time is remarkably reduced. The brake module assembly task needs the robot to change its orientation frequently, so, in the second method, we added one degree of freedom to the end effector that is used in the first method. By attaching it to a conventional 6 degrees of freedom industrial manipulator, we composed a 7 degrees of freedom redundant manipulator. A redundant manipulator has the advantage of flexible manipulation so the robot can change its orientation easily and can perform assembly task very fast. Experimental results show that the second method dramatically reduce whole task time for brake module assembly.

• Journal of the Korean Vacuum Society
• /
• v.18 no.2
• /
• pp.141-146
• /
• 2009

PLZT ferroelectric thin films were deposited on Pt/Ti/$SiO_2$/Si substrate with $TiO_2$ buffer layer in between by rf magnetron sputtering method. In order to investigate the effect of Ar/$O_2$ partial pressure ratio on the ferroelectric properties of PLZT thin films, PLZT thin films were deposited at various Ar/$O_2$ partial pressure ratio ; 27/1.5 seem, 23/5.5 seem, 21/7.5 seem and 19/9.5 seem. The crystallinities of PLZT thin films were analyzed by XRD. The surface morphology was observed using FE-SEM. The P-E hysteresis loops, the remanent polarization characteristics and the leakage current characteristics were obtained using a Precision LC. The crystallinity and elaborateness of PLZT thin films were decreased as increasing the oxygen partial pressure ratio. And preferred orientation of PLZT thin films changed from (110) plane to (111) plane. The oxygen partial pressure ratio affects the thin film surface morphology and the ferroelectric properties.

• Korean Journal of Materials Research
• /
• v.5 no.2
• /
• pp.239-245
• /
• 1995

Mn-Zn ferrite thin films were deposited on $SiO_2(1000 \AA)/Si(100)$ by ion beam sputtering using a single ion source. A mosaic target consisting of a single crystal(ll0) Mn-Zn ferrite with a Fe metal strip on it was used. As-deposited films without oxygen gas flow have a wiistite structure due to oxygen deficiencies, which originated from the extra metal atoms sputtered from the metal strips during deposition. The as-deposited films with oxygen gas flow, however, have a spinel structure with (111) preferred orientation. The crystallization of thin films was maximized at the ion beam extraction voltage of 2.lkV, at which the deposited films are bombarded appropriately by the energetic secondary ions reflected from the target. As the extraction voltage increased or decreased from the optimum value, the crystallinity of thin films becomes poor owing to a weak and severe bombardment of the secondary ions, respectively. Crystallization due to the bombardment of the secondary ions was also maximized at the beam incidence angle of $55^{\circ}$. The as-deposited ferrite thin films with a spinel structure showed ferrimagnetism and had an in-plane magnetization easy axis.

• Journal of the Korean Magnetics Society
• /
• v.21 no.3
• /
• pp.88-92
• /
• 2011

We grew $Zn_{0.4}Fe_{2.6}O_4$ thin films using Pulsed Laser Deposition and studied their crystal structure and magnetical characteristics as a function of growth temperature ($T_g$). For the film with $T_g=300^{\circ}C$, X-ray reflections from ${\alpha}-Fe_2O_3$ and ZnO were observed. However, when $T_g$ was increased from 300 to $500^{\circ}C$, crystal structure of inverse spinel was stabilized with the crystal orientation of $Zn_{0.4}Fe_{2.6}O_4(111)/Al_2O_3(0001)$ without any detection of ${\alpha}-Fe_2O_3$ and ZnO phases. The surface morphology shows flattening behavior with increasing $T_g$ from 300 to $500^{\circ}C$. These observations indicate that Zn is substituted into tetrahedron A-site of the inverse-spinel $Fe_3O_4$. M-H curves exhibit clear ferromagnetism for the sample with $T_g=500^{\circ}C$ whereas no ferromagnetism is observed for the film with $T_g=300^{\circ}C$.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.20 no.6
• /
• pp.254-261
• /
• 2010

Polycrystalline silicon (pc-Si) films are fabricated and characterized for application to pc-Si thin film solar cells as a seed layer. The amorphous silicon films are crystallized by the aluminum-induced layer exchange (ALILE) process with a structure of glass/Al/$Al_2O_3$/a-Si using various thicknesses of $Al_2O_3$ layers. In order to investigate the effects of the oxide layer on the crystallization of the amorphous silicon films, such as the crystalline film detects and the crystal grain size, the $Al_2O_3$ layer thickness arc varied from native oxide to 50 nm. As the results, the defects of the poly crystalline films are increased with the increase of $Al_2O_3$ layer thickness, whereas the grain size and crystallinity are decreased. In this experiments, obtained the average pc-Si sub-grain size was about $10\;{\mu}m$ at relatively thin $Al_2O_3$ layer thickness (${\leq}$ 16 nm). The preferential orientation of pc-Si sub-grain was <111>.

• Journal of the Korean Ceramic Society
• /
• v.34 no.2
• /
• pp.131-138
• /
• 1997

Silicon carbide films were chemically vapor deposited onto graphite substrates using MTS(Ch3SiCl3) as a source and Ar or H2 as a diluent gas. The experiments were performed at a fixed condition such as a de-position temperature of 130$0^{\circ}C$, a total pressure of 10 torr, and a flow rate of 100 sccm for each MTS and carrier gas. The purpose of this study is to consider the variation of the growth behavior with the addition of each diluent gas. It is shown that the deposition rate leads to maximum value at 200 sccm addition ir-respective of diluent gases and the deposition rate of Ar addition is faster than that of H2 one. It seems that these characteristics of deposition rate are due to varying interrelationship between boundary layer thick-ness and the concentration of a source with each diluent gas addition, when overall deposition rate is con-trolled by mass transport kinetics. The preferred orientation of (220) plane was maintained for the whole range of Ar addition. However, above 200 sccm addition, especially that of (111) plane was more increased in proportion to H2 addition. Surface morphologies of SiC films were the facet structures under Ar addition, but those were gradually changed from facet to smooth structures with H2 addition. Surface roughness be-came higher in Ar, but it became lower in H2 with increasing the amount of diluent gas.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.327.1-327.1
• /
• 2014

Nitrides-on-silicon structures are considered to be an excellent candidate for unique design architectures and creating devices for high-power applications. Therefore, a lot of effort has been concentrating on growing high-quality III-nitrides on Si substrates, mostly Si(111) and Si(001) substrates. However, there are several fundamental problems in the growth of nitride compound semiconductors on silicon. First, the large difference in lattice constants and thermal expansion coefficients will lead to misfit dislocation and stress in the epitaxial films. Second, the growth of polar compounds on a non-polar substrate can lead to antiphase domains or other defective structures. Even though the lattice mismatches are reached to 16.9 % to GaN and 19 % to AlN and a number of dislocations are originated, Si(111) has been selected as the substrate for the epitaxial growth of nitrides because it is always favored due to its three-fold symmetry at the surface, which gives a good rotational matching for the six-fold symmetry of the wurtzite structure of nitrides. Also, Si(001) has been used for the growth of nitrides due to a possible integration of nitride devices with silicon technology despite a four-fold symmetry and a surface reconstruction. Moreover, Si(110), one of surface orientations used in the silicon technology, begins to attract attention as a substrate for the epitaxial growth of nitrides due to an interesting interface structure. In this system, the close lattice match along the [-1100]AlN/[001]Si direction promotes the faster growth along a particular crystal orientation. However, there are insufficient until now on the studies for the growth of nitride compound semiconductors on Si(110) substrate from a microstructural point of view. In this work, the microstructural properties of nitride thin layers grown on Si(110) have been characterized using various TEM techniques. The main purpose of this study was to understand the atomic structure and the strain behavior of III-nitrides grown on Si(110) substrate by molecular beam epitaxy (MBE). Insight gained at the microscopic level regarding how thin layer grows at the interface is essential for the growth of high quality thin films for various applications.

• Korean Journal of Materials Research
• /
• v.17 no.5
• /
• pp.256-262
• /
• 2007

Effects of interlayer and the combination of different coating methods on the mechanical and corrosion behaviors of TiN and CrN coated on 420 stainless steel have been studied. STS 420 specimen were tempered at $300^{\circ}C$ for 1 hr in vacuum furnace. The TiN and CrN thin film with 2 ${\mu}m$ thickness were coated by arc ion plating and DC magnetron sputtering following the formation of interlayer for pure titanium and chromium with 0.2 ${\mu}m$ thickness. The microstructure and surface analysis of the specimen were conducted by using SEM, XRD and roughness tester. Mechanical properties such as hardness and adhesion also were examined. XRD patterns of TiN thin films showed that preferred TiN (111) orientation was observed. The peaks of CrN (111) and $Cr_2N$ (300) were only observed in CrN thin films deposited by arc ion plating. Both TiN and CrN deposited by arc ion plating had the higher adhesion and hardness compared to those formed by magnetron sputtering. The specimen of TiN and CrN on which interlayer deposited by magnetron sputtering and thin film deposited by arc ion plating had the highest adhesion with 22.2 N and 19.2 N. respectively. TiN and CrN samples shown the most noble corrosion potentials when the interlayers were deposited by using magnetron sputtering and the metal nitrides were deposited by using arc ion plating. The most noble corrosion potentials of TiN and CrN were found to be approximately -170 and -70 mV， respectively.

• Journal of the Korean Vacuum Society
• /
• v.9 no.3
• /
• pp.197-206
• /
• 2000

The deposition characteristics of MOCVD Cu using the (hfac)Cu(1,1-COD)(1,1,1,5,5,5-hexafluoro-2,4-pentadionato Cu(I) 1,5-cyclooctadine) have been investigated in terms of the effects of carrier gas such as hydrogen and argon as well as the effects of H(hfac) ligand addition. MOCVD Cu using a hydrogen carrier gas led to a higher deposition rate and lower resistivity than an argon carrier gas system. The improvement in the surface roughness of the MOCVD Cu films and the (111) preferred orientation texture was obtained by using a hydrogen carrier gas. However, the adhesion characteristics of the films showed relatively weaker compared to the Ar carrier gas system, probably due to the larger amount of F content in the films, which was confirmed by the AES analyses. When an additional H(hfac) ligand was added, the deposition rate was significantly enhanced in the case of an argon + H(hfac) carrier gas system while significant change in the deposition rate of MOCVD Cu was not observed in the case of the hydrogen carrier gas system. However, the addition of H(hfac) in both carrier gases led to lowering the resistivity of the MOCVD Cu films. In conclusion, this paper suggests the deposition mechanism of MOCVD Cu and is expected to contribute to the enhancement of smooth Cu films with a low resistivity by manipulating the deposition conditions such as the carrier gas and addition of H(hfac) ligand.

• Journal of the Korean Vacuum Society
• /
• v.19 no.6
• /
• pp.475-482
• /
• 2010

Polycrystalline NiO thin films were deposited on glass substrate by RF magnetron sputtering using only Ar as a plasma sputter gas. based on the analysis of x-ray diffraction (XRD), NiO films had a polycrystalline cubic (NaCl type) structure. NiO thin films grown below and above $200^{\circ}C$ showed preferred orientation of (111) and (220) respectively. It showed colossal change in electrical resistivity as much a ${\sim}10^7$ order form an insulating state of $105\;{\Omega}cm$ below $200^{\circ}C$ to a conducting state of $10^{-2}{\sim}10^{-1}\;{\Omega}cm$ above $300^{\circ}C$ such a Mott metal-insulator transition (MIT) in polycrystalline.