• Journal of Powder Materials
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• v.24 no.5
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• pp.370-376
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• 2017

In this study we manufacture a Ni-Cr-B-Si +WC/12Co composite coating layer on a Cu base material using a laser cladding (LC) process, and investigate the microstructural and mechanical properties of the LC coating and Ni electroplating layers (reference material). The initial powder used for the LC coating layer is a powder feedstock with an average particle size of $125{\mu}m$. To identify the microstructural and mechanical properties, OM, SEM, XRD, room and high temperature hardness, and wear tests are implemented. Microstructural observation of the initial powder and LC coating layer confirm the layer is composed mainly of ${\gamma}-Ni$ phases and WC and $Cr_{23}C_6$ carbides. The measured hardness of the LC coating and Ni electroplating layers are 653 and 154 Hv, respectively. The hardness measurement from room up to high temperatures of $700^{\circ}C$ result in a hardness decrease as the temperature increases, but the hardness of the LC coating layer is higher for all temperature conditions. Room temperature wear results show that the wear loss of the LC coating layer is 1/12 of the wear level of the Ni electroplating layer. The measured bond strength is also greater in the LC coating than the Ni electroplating.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.1
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• pp.19-27
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• 2017

The objective of this study was to determine the growth characteristics of cool (C1) and warm season grasses (C2) in pastures mixed with C1 and C2 at an altitude of 400 m in Jeju island to establishing pasture suitable for grazing horses and to evaluate the effect of pastures mixed with tall and short type grasses on the intake characteristics of horses. C1 used in this study was Kentucky bluegrass, redtop (short type grass) and tall type grasses were orchardgrass and tall fescue, respectively. Treatments of this study were consisted of four groups and the short type grass used in pastures mixed with C1 and C2 was mainly bermudagrass. Four treatment groups were follow as; Treatment 1 (bermudagrass + Kentucky bluegrass + redtop) 2) Treatment 2 (bermudagrass + tall fescue + orchardgrass) 3) Treatment 3 (Kentucky bluegrass + redtop) 4) Treatment 4 (tall fescue + orchardgrass). Bermudagrass was a little winter killing and inhibition of plant growth at an altitude of 400 m. Plant heights in pastures mixed with C1 and C2 were grown better than that in pastures mixed with C1. Especially, plant height in Treatment 4 was higher than other treatments. Dry matter yield was in the following order: Treatment 4> Treatment 3> Treatment 2> Treatment 1. Dry matter yield in pastures mixed with C1 increased as compared with pastures mixed with C1 and C2. Dry matter yield in Treatment 3 was higher than other treatments. In the first investigation regarding vegetation distribution, bermudagrass ratios among grasses in Treatment 1 and Treatment 2 were 11.7 and 13.3%, respectively. The growth of bermudagrass in winter was low due to the cold damage. However the growth of Kentucky bluegrass, redtop, tall fescue and orchardgrass was good. In the second investigation, bermudagrass ratios among grasses in Treatment 1 and Treatment 2 were 5.0 and 11.7%, respectively. Growth of forage in the second investigation was poor as compared to the first investigation. nutritive values(crude protein content, neutral detergent fiber content, acid detergent fiber content, digestibility) were good in pastures mixed with C1 Especially, nutritive values in pastures mixed with tall was higher than those of pastures mixed short grasses. P content among minerals in Treatment 1 was higher than other groups. However, the content of Ca, Mg and Mn were lower. The contents of Ca, K, Mg, Na, Cu, Zn and Fe in Treatment 2 were higher. However, the contents of K, Mg, Na, Cu, Zn and Fe in Treatment 3 were lower. Therefore, we suggest that cool season grasses with short grasses were sowed to establishing pasture suitable for grazing horses at an altitude of 400 m in Jeju island.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.252-258
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• 1999

Tetramethyl orthosilicate (TMOS) was obtained by the direct synthesis of methanol with metallic silicon including copper compound as a catalyst and zinc compound as a promoter. The effects of the preheating temperature and the preparation method of the contact mass on TMOS synthesis were investigated. The composition effects of the contact mass which was composed of metallic silicon with copper catalyst and various metallic halide promoters including Zn, Sn or Cd compound were studied also. The best performance on TMOS synthesis was observed on a mixed bed reactor containing metallic silicon preheated with CuCl as a catalyst and $ZnCl_2$ as a promoter. When Cu/Si = 7 wt %, Zn/Cu = 7 wt % was mixed in a slurry phase and activated into contact mass at $380^{\circ}C$, the average selectivity was 87.2% in the silicon consumption of 69.2% at $220^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.81-86
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• 2019

Metal oxide/graphene composites have been known as promising functional materials for advanced applications such as high sensitivity gas sensor, and high capacitive secondary battery. In this study, tin dioxide ($SnO_2$) nanostructures were grown on chemically synthesized graphene nanosheets using a two-zone horizontal furnace system. The large area graphene nanosheets were synthesized on Cu foil by thermal chemical vapor deposition system with the methane and hydrogen gas. Chemically synthesized graphene nanosheets were transferred on cleaned $SiO_2$(300 nm)/Si substrate using the PMMA. The $SnO_2$ nanostuctures were grown on graphene nanosheets at $424^{\circ}C$ under 3.1 Torr for 3 hours. Raman spectroscopy was used to estimate the quality of as-synthesized graphene nanosheets and to confirm the phase of as-grown $SnO_2$ nanostructures. The surface morphology of as-grown $SnO_2$ nanostructures on graphene nanosheets was characterized by field-emission scanning electron microscopy (FE-SEM). As the results, the synthesized graphene nanosheets are bi-layers graphene nanosheets, and as-grown tin oxide nanostructures exhibit tin dioxide phase. The morphology of $SnO_2$ nanostructures on graphene nanosheets exhibits complex nanostructures, whereas the surface morphology of $SnO_2$ nanostructures on $SiO_2$(300 nm)/Si substrate exhibits simply nano-dots. The complex nanostructures of $SnO_2$ on graphene nanosheets are attributed to functional groups on graphene surface.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.84-84
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• 2012

소자가 고집적화 됨에 따라, 비저항이 낮고 electro migration (EM), Stress Migration (SM) 특성이 우수한 구리(Cu)를 배선재료로서 사용하고 있다. 그러나, 구리는 Si과 $SiO_2$의 내부로 확산이 빠르게 일어나, Si 소자 내부에 deep donor level을 형성하고, 누설 전류를 증가시키는 등 소자의 성능을 저하시킬 수 있는 문제점을 가지고 있다. 그러나, electroplating 을 이용하여 증착한 Cu 박막은 일반적으로 확산 방지막으로 쓰이는 TiN, TaN, 등의 물질과의 접착 (adhesion) 특성이 나쁘다. 따라서, Cu CMP 에서 증착된 Cu 박막의 벗겨지거나(peeling), EM or SM 저항성 저하 등의 배선에서의 reliability 문제를 야기하게된다. 따라서 Cu 와 접착 특성이 좋은 새로운 확산방지막 또는 adhesion layer의 필요성이 대두되고 있다. 본 연구에서는 이러한 Cu 배선에서의 접착성 문제를 해결하고자 Metal organic chemical vapor deposition (MOCVD)을 이용하여 제조한 코발트(Co) 박막을 $Cu/TaN_x$ 사이의 접착력 개선을 위한 adhesion layer로 적용하려는 시도를 하였다. Co는 비저항이 낮고, Cu 와 adhesion이 좋으며, Cu direct electroplating 이 가능하다는 장점을 가지고 있다. 하지만, 수소 분위기에서 $C_{12}H_{10}O_6(Co)_2$ (dicobalt hexacarbonyl tert-butylacetylene, CCTBA) 전구체에 의한 MOCVD Co 박막의 경우 탄소, 산소와 같은 불순물이 다량 함유되어 있어, 비저항, surface roughness 가 높아지게 된다. 따라서 구리 전착 초기에 구리의 핵 생성(nucleation)을 저해하고 핵 생성 후에도 응집(agglomeration)이 발생하여 연속적이고 얇은 구리막 형성을 방해한다. 이를 해결하기 위해, MOCVD Co 박막 증착 시 수소 반응 가스에 암모니아를 추가로 주입하여, 수소/암모니아의 분압을 1:1, 1:6, 1:10으로 변화시켜 $Co/TaN_x$ 박막의 특성을 비교 분석하였다. 각각의 수소/암모니아 분압에 따른 $Co/TaN_x$ 박막을 TEM (Transmission electron microscopy), XRD (X-ray diffraction), AES (Auger electron spectroscopy)를 통해 물성 및 조성을 분석하였고, AFM (Atomic force microscopy)를 이용하여, surface roughness를 측정하였다. 실험 결과, $Co/TaN_x$ 박막은 수소/암모니아 분압 1:6에서 90 ${\mu}{\Omega}-cm$의 낮은 비저항과 0.97 nm 의 낮은 surface roughness 를 가졌다. 뿐만 아니라, MOCVD 에 의해 증착된 Co 박막이4-6 % concentration 의 탄소 및 산소 함량을 가지는 것으로 나타났고, 24nm 크기의 trench 기판 위에 약 6nm의 $Co/TaN_x$ 박막이 매우 균일하게 형성된 것을 확인 할 수 있었다. 이러한 결과들은, 향후 $Co/TaN_x$ 박막이 Cu direct electroplating 공정이 가능한 diffusion barrier로서 성공적으로 사용될 수 있음을 보여준다.

• Journal of Powder Materials
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• v.13 no.5 s.58
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• pp.351-359
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• 2006

Ni based($Ni_{57}Zr_{20}Ti_{18}Si_2Sn_3$) bulk metallic glass(BMG) powders were produced by a gas atomization process, and ductile Cu powders were mixed using a spray drying process. The Ni-based amorphous powder and Cu mixed Ni composite powders were compacted by a spark plasma sintering (SPS) processes into cylindrical shape. The relative density varied with the used SPS mold materials such as graphite, hardened steel and WC-Co hard metal. The relative density increased from 87% to 98% when the sintering temperature increased up to $460^{\circ}C$ in the WC-Co hard metal mold.

• Korean Journal of Materials Research
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• v.7 no.9
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• pp.811-823
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• 1997

차세대 반도체 배선분야에서, Cu박막은 현재의 AI을 대체할 물질로서 대두되고 있으며 CVD에 의한 선택적 증착은 Cu의 patterning과 관련하여 상당한 관심을 일으키고 있다. 본 연구에서는 (hfac)Cu(VTMS)의 유기원료를 사용하여, CVD공정변수, 운반기체, 표면 처리 공정에 따른 SiO$_{2}$, TiN, AI기판에 대한 선택성을조사하였다. 선택성은 저온(15$0^{\circ}C$), 저합(0.3Torr)에서 향상될 수 있었으며, 특히, HMDS in-situ-predosing공정에 의해 더욱 향상될 수 있었다. 모든 경우에 대해, H$_{2}$운반기체가 Ar 보다 짧은 incubation time과 높은 증착 속도가 얻어졌으며, Cu입자들의 크기가 작고 연결상태가 보다 양호하였다. 이는 H$_{2}$경우에 기판표면에 원료가 흡착되어 핵을 형성시키는 위치 (-OH)가 보다 많이 제공되기 때문으로 여겨진다. 이러한 미세구조의 차이는 H$_{2}$경우에 보다 낮은 비저항을 얻게 했다. HMDS in-situ predosing공정에 의한 Cu박막내 불순물 차이는 없었으며 뚜렷한 비저항의 차이도 나타나지 않았다.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.133-133
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• 1998

In the thin film alloy formation of the transition metals ion-beam-mixing technique forms a metastable structure which cannot be found in the arc-melted metal alloys. Sppecifically it is well known that the studies about the electronic structure of ion-beam-mixed alloys pprovide the useful information in understanding the metastable structures in the metal alloy. We studied the electronic change in the ion-beam-mixed ppt-Ct alloys by XppS and XANES. These analysis tools pprovide us information about the charge transfer in the valence band of intermetallic bonding. The multi-layered films were depposited on the SiO2 substrate by the sequential electron beam evapporation at a ppressure of less than 5$\times$10-7 Torr. These compprise of 4 ppairs of ppt and Cu layers where thicknesses of each layer were varied in order to change the alloy compposition. Ion-beam-mixing pprocess was carried out with 80 keV Ae+ ions with a dose of $1.5\times$ 1016 Ar+/cm2 at room tempperature. The core and valence level energy shift in these system were investigated by x-ray pphotoelectron sppectroscoppy(XppS) pphotoelectrons were excited by monochromatized Al K ａ(1486.6 eV) The ppass energy of the hemisppherical analyzer was 23.5 eV. Core-level binding energies were calibrated with the Fermi level edge. ppt L3-edge and Cu K-edge XANES sppectra were measured with the flourescence mode detector at the 3C1 beam line of the ppLS (ppohang light source). By using the change of White line(WL) area of the each metal sites and the core level shift we can obtain the information about the electrons pparticippating in the intermetallic bonding of the ion-beam-mixed alloys.

• 보존과학연구
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• s.22
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• pp.93-114
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• 2001

The composition analysis of Danchung pigments at Geunjeongjeon Hall in Gyeongbokgung Palace were carried out by FXRF and MXRD. The analytical result of the inside pigments at Geunjeongjeon showed that these painted in use the mineral pigments. Gold pigment was pure gold(Au).The main composition identified in green pigments were chalcanthite($CuSO_4$.$5H_2O$) and celadonite($K(Mg, Fe, Al)_2$.$(Si, Al)_4O_10(OH)_2$ ). Red pigments werecinnnabar(HgS).The analytical result of the outside pigments at Geunjeongjeon revealed that these applied to the artificial synthetic pigment. Yellow pigment was chromeyellow($PbCrO_4$). The main composition identified in red pigments were red lead($Pb_3O_4$)and hematite($Fe_2O_3$). Green pigments were emeral green($C_2H_3A_s3Cu_2O_8$) and chromegreen($Cr_2O_3$). Blue pigment was lazurite($Na_6Ca2Al_6Si_6O_24(SO_4)_2$), titanium dioxide($TiO_2$) of white pigment.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.740-742
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• 1998

In this paper, we described the effect of rapid thermal annealing on the electrical properties of interfacial layer between various top electrodes and $(Ba_{0.5}Sr_{0.5})TiO_3$ thin films. BST thin films were fabricated on Pt/TiN/$SiO_2$/Si substrate by RF magnetron sputtering technique. AI, Ag, and Cu films for the formation of top electrode were deposited on BST thin films by thermal evaporator. Top electrodes/BST/Pt capacitor annealed with rapid thermal annealing at various temperature. In $(Ba_{0.5}Sr_{0.5})TiO_3$ thin films with Cu top electrode annealed at $500^{\circ}C$, the dielectric constant was measured to the value of 366 at 1.2 [kHz] and the leakage current was obtained to the value of $5.85{\times}10^{-7}\;[A/cm^2}$ at the forward bias of 2 [V].