• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.377-377
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• 2012

Microprocessor technology now relies on copper for most of its electrical interconnections. Because of the high diffusivity of copper, Atomic layer deposition (ALD) $TaN_x$ is used as a diffusion barrier to prevent copper diffusion into the Si or $SiO_2$. Another problem with copper is that it has weak adhesion to most materials. Strong adhesion to copper is an essential characteristic for the new barrier layer because copper films prepared by electroplating peel off easily in the damascene process. Thus adhesion-enhancing layer of cobalt is placed between the $TaN_x$ and the copper. Because, cobalt has strong adhesion to the copper layer and possible seedless electro-plating of copper. Until now, metal film has generally been deposited by physical vapor deposition. However, one draw-back of this method is poor step coverage in applications of ultralarge-scale integration metallization technology. Metal organic chemical vapor deposition (MOCVD) is a good approach to address this problem. In addition, the MOCVD method has several advantages, such as conformal coverage, uniform deposition over large substrate areas and less substrate damage. For this reasons, cobalt films have been studied using MOCVD and various metal-organic precursors. In this study, we used $C_{12}H_{10}O_6(Co)_2$ (dicobalt hexacarbonyl tert-butylacetylene, CCTBA) as a cobalt precursor because of its high vapor pressure and volatility, a liquid state and its excellent thermal stability under normal conditions. Furthermore, the cobalt film was also deposited at various $H_2/NH_3$ gas ratio(1, 1:1,2,6,8) producing pure cobalt thin films with excellent conformality. Compared to MOCVD cobalt using $H_2$ gas as a reactant, the cobalt thin film deposited by MOCVD using $H_2$ with $NH_3$ showed a low roughness, a low resistivity, and a low carbon impurity. It was found that Co/$TaN_x$ film can achieve a low resistivity of $90{\mu}{\Omega}-cm$, a low root-mean-square roughness of 0.97 nm at a growth temperature of $150^{\circ}C$ and a low carbon impurity of 4~6% carbon concentration.

• 정보관리연구
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• 제43권3호
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• pp.23-41
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• 2012

전 세계적으로 이용되는 인용색인 서비스인 Web of Science(WoS)는 데이터 수록 범위에 한계가 있음이 인용색인 연구에서 지적되어 왔다. 또한 국내 학술논문이 인용하는 해외 문헌의 비율이 전체의 약 75%를 차지한다는 것이 인용패턴 분석연구에서 밝혀진 바 있다. 본 연구에서는 WoS DB의 데이터 수록 범위를 검증하기 위한 첫 번째 단계로써 WoS DB에 포함되어 있지 않은 국내 연구자의 인용문헌 즉, 한국과학기술인용 DB(Korea Science Citation Database: KSCD)에 수록된 참고문헌 데이터 일부를 JCR 학술지 영향력지수 산출과정에 포함시켜 학술지 영향력 지수(Impact Factor: IF)의 변화 및 그에 따른 학술지 순위변동 여부를 조사하였다. 구체적으로 국내 문헌정보학 분야 학술지에 수록된 참고문헌을 JCR 2009 문헌정보학 분야 학술지 IF 산출과정에 포함하였다. 하지만 학술지 IF의 변화와 그에 따른 순위 차이가 통계적으로 유의하지 않았고, 이에 데이터 범위를 넓혀 컴퓨터 공학 및 전자공학 분야 학술지 45종에 수록된 참고문헌을 추가로 분석하여 JCR 2010 전자공학 분야 학술지 IF 산출과정에 포함하였다. 그 결과, 부분적으로 통계적으로 유의한 학술지 순위 변화가 일어났다. 본 연구는 한정된 데이터를 사용하였음에도 불구하고 미미하지만 통계적으로 유의한 JCR 학술지 순위 변동을 보여줌으로써 WoS DB에 포함되지 않은 인용 데이터의 잠재적 가치를 제시하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1559-1562
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• 1999

We formed $SiO_2:F$ films by low-temperature process called Liquid Phase Deposition(LPD) and investigated its electrical and physical properties. Because of the use of room-temperature and no special vacuum apparatus for forming $SiO_2:F$ films, this technique can have some advantages related with the application to dielectric interlayer for multilevel structure in ULSI devices. The growth rate 100nm/hr was obtained at the growth solution of 2.5mol/l. The P-etch rate showed a similar or better tendency compared with $SiO_2$ films formed by CVD, Sputter, E-beam evaporator etc.. The fourier transform infrared (FTIR) spectra revealed that the contained fluorine atoms exist uniform throughout the formed $SiO_2$ films. The Scanning Electron Microscope images showed that LPD-$SiO_2$ films could be stably grown on silicon substrates and the good step-coverage could also be obtained, which indicates that the LPD-$SiO_2$ films have some possibility of the application to planarization and interlayer dielectric films which are vitally necessary to achieve the multilevel interconnection in ULSI. The I-V characteristics has some distinct differences according to the concentration of growth solution.

• 전기화학회지
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• 제11권2호
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• pp.100-104
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• 2008

Titanium sheet metal substrates used in thin film batteries were wet etched and their surface area was increased in order to increase the discharge capacity and power density of the batteries. To obtain a homogeneous etching pattern, we used a conventional photolithographic process. Homogeneous hemisphere-shaped wells with a diameter of approximately $40\;{\mu}m$ were formed on the surface of the Ti substrate using a photo-etching process with a $20\;{\mu}m{\times}20\;{\mu}m$ square patterned photo mask. All-solid-state thin film cells composed of a Li/Lithium phosphorous oxynitride (Lipon)/$LiCoO_2$ system were fabricated onto the wet etched substrate using a physical vapor deposition method and their performances were compared with those of the cells on a bare substrate. It was found that the discharge capacity of the cells fabricated on wet etched Ti substrate increased by ca. 25% compared to that of the cell fabricated on bare one. High discharge rate was also able to be obtained through the reduction in the internal resistance. However, the cells fabricated on the wet etched substrate exhibited a higher degradation rate with charge-discharge cycling due to the nonuniform step coverage of the thin films, while the cells on the bare substrate demonstrated a good cycling performance.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.557-565
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• 2014

We report the effect of basal-plane stacking faults (BSFs) on X-ray diffraction (XRD) of non-polar (11$\underline{2}$0) a-plane GaN films with different $SiN_x$ interlayers. Complete $SiN_x$ coverage and increased three-dimensional (3D) to two-dimensional (2D) transition stages substantially reduce BSF density. It was revealed that the Si-doping profile in the Si-doped GaN layer was unaffected by the introduction of a $SiN_x$ interlayer. The smallest in-plane anisotropy of the (11$\underline{2}$0) XRD ${\omega}$-scan widths was found in the sample with multiple $SiN_x$ layers, and this finding can be attributed to the relatively isotropic GaN mosaic resulting from the increase in the 3D-2D growth step. Williamson-Hall (WH) analysis of the (h0$\underline{h}$0) series of diffractions was employed to determine the c-axis lateral coherence length (LCL) and to estimate the mosaic tilt. The c-axis LCLs obtained from WH analyses of the present study's representative a-plane GaN samples were well correlated with the BSF-related results from both the off-axis XRD ${\omega}$-scan and transmission electron microscopy (TEM). Based on WH and TEM analyses, the trends in BSF densities were very similar, even though the BSF densities extracted from LCLs indicated that the values were reduced by a factor of about twenty.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.302-305
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• 2003

It is difficult to obtain sufficient healthy skin for coverage of a wide area of skin wound. In the skin, an additional population of living epithelial cells is located in the outer root sheath (ORS) of hair $follicles.^{1),2)}$ ORS cells should be a good source of epithelium because they are easily obtainable and patients do not have to suffer from scar formation at donor sites. We modified ordinary primary culture technique for the purpose of solving such problem that epithelial cells have a low propagation and easy aging during culture periods. First of all, we improved primary cultivation methods. In the ordinary primary culture, average yield of human ORS cells was $2\;{\times}\;10^3$ cells/follicle by direct incubation with trypsin (0.1%)/EDTA (0.02%) solution for 15 min at $37^{\circ}C$ but we could obtain about $6.5\;{\times}\;10^3$ cells/follicle by two step enzyme digestion method with dispase (1.2 U/ml) and trypsin (0.1%)/EDTA (0.02%) solution. So we could achieve three times higher primary cultured ORS cell yield. Secondly, we could obtain total $2\;{\times}\;10^7$ cells in serum free medium and even more total $6\;{\times}\;10^7$ cells in modified E-medium with mitomycin C-treated feeder cells during 17 days. Using the cultured ORS cells, and we could make bioartificial skin equivalent in vitro and concluded that ORS cells were progenitor cells for skin epithelial cell.

• 복식
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• 제66권5호
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• pp.66-81
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• 2016

This study is designed to understand the problems of existing Korean male soldiers' winter uniform tops by researching its current state, and contribute to developing uniforms with improved size and motion appropriateness. Military bases were visited to research satisfaction of size and motion appropriateness of the current winter uniform tops. 193 soldiers were surveyed and interviewed, and the shape and fit of the standard sizes of the inner and outer layers of the current winter uniform were analyzed. Findings of this study are as follows. 1) Compared to the new combat uniforms that soldiers were wearing in their appropriate size (of the 44 sizes), there were many cases where the soldiers were not wearing winter uniform inner (of the 8 sizes) or outer (of the 18 sizes) layers in the correct size for their body. 2) A total of 37 combat uniform sizes appropriate for the body shapes were expected to be newly applied, and inside and outside layers of winter tops would be presented as sets of 14 different sizes in step with the new combat uniform sizes, instead of the existing 8 inside layer sizes and 18 outside layer sizes. 3) The inner and outer layer of the existing winter uniform tops had several problems with the shape and fit. First, the inner layer was shorter than the combat uniform. Its shoulder width was wide, but the sleeve length was short creating lack of coverage, and the angle connecting the sleeve and bodice was very small creating a high sleeve cap curve and narrow sleeve width that make motions difficult and cause discomfort. As for the outer layer, the hem moved up when soldiers bent over or adjusted the waist string so the top could not sufficiently cover, the shoulder width was wide and the sleeve length was short, requiring improvements.

• Radiation Oncology Journal
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• 제36권1호
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• pp.63-70
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• 2018

Purpose: The objective of this study was to compare dosimetric characteristics of three-dimensional conformal radiotherapy (3D-CRT) and two types of intensity-modulated radiotherapy (IMRT) which are step-and-shoot intensity modulated radiotherapy (s-IMRT) and modulated arc therapy (mARC) for thoracic esophageal cancer and analyze whether IMRT could reduce organ-at-risk (OAR) dose. Materials and Methods: We performed 3D-CRT, s-IMRT, and mARC planning for ten patients with thoracic esophageal cancer. The dose-volume histogram for each plan was extracted and the mean dose and clinically significant parameters were analyzed. Results: Analysis of target coverage showed that the conformity index (CI) and conformation number (CN) in mARC were superior to the other two plans (CI, p = 0.050; CN, p = 0.042). For the comparison of OAR, lung V5 was lowest in s-IMRT, followed by 3D-CRT, and mARC (p = 0.033). s-IMRT and mARC had lower values than 3D-CRT for heart $V_{30}$ (p = 0.039), $V_{40}$ (p = 0.040), and $V_{50}$ (p = 0.032). Conclusion: Effective conservation of the lung and heart in thoracic esophageal cancer could be expected when using s-IMRT. The mARC was lower in lung $V_{10}$, $V_{20}$, and $V_{30}$ than in 3D-CRT, but could not be proven superior in lung $V_5$. In conclusion, low-dose exposure to the lung and heart were expected to be lower in s-IMRT, reducing complications such as radiation pneumonitis or heart-related toxicities.

• 한국재료학회지
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• 제26권8호
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• pp.430-437
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• 2016

Aluminum oxide ($Al_2O_3$) thin films were grown by atomic layer deposition (ALD) using a new Al metalorganic precursor, dimethyl aluminum sec-butoxide ($C_{12}H_{30}Al_2O_2$), and water vapor ($H_2O$) as the reactant at deposition temperatures ranging from 150 to $300^{\circ}C$. The ALD process showed typical self-limited film growth with precursor and reactant pulsing time at $250^{\circ}C$; the growth rate was 0.095 nm/cycle, with no incubation cycle. This is relatively lower and more controllable than the growth rate in the typical $ALD-Al_2O_3$ process, which uses trimethyl aluminum (TMA) and shows a growth rate of 0.11 nm/cycle. The as-deposited $ALD-Al_2O_3$ film was amorphous; X-ray diffraction and transmission electron microscopy confirmed that its amorphous state was maintained even after annealing at $1000^{\circ}C$. The refractive index of the $ALD-Al_2O_3$ films ranged from 1.45 to 1.67; these values were dependent on the deposition temperature. X-ray photoelectron spectroscopy showed that the $ALD-Al_2O_3$ films deposited at $250^{\circ}C$ were stoichiometric, with no carbon impurity. The step coverage of the $ALD-Al_2O_3$ film was perfect, at approximately 100%, at the dual trench structure, with an aspect ratio of approximately 6.3 (top opening size of 40 nm). With capacitance-voltage measurements of the $Al/ALD-Al_2O_3/p-Si$ structure, the dielectric constant of the $ALD-Al_2O_3$ films deposited at $250^{\circ}C$ was determined to be ~8.1, with a leakage current density on the order of $10^{-8}A/cm^2$ at 1 V.

• Korean Chemical Engineering Research
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• 제43권1호
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• pp.98-102
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• 2005

본 연구에서는 유기금속 전구체인(HFAC)Cu(DMB)을 이용하여 구리를 제조하고, 기판온도 및 요오드 화합물이 증착 구리막의 표면 형상 및 충진 특성에 미치는 영향을 살펴보았다. 증착 온도가 높을수록 표면 형상이 거칠어지고 충진 특성이 악화되었으며, 요오드를 사용하여 증착할 경우 표면 거칠기와 충진 특성이 개선됨을 알 수 있었다. 이때 요오드 화합물과 전구체를 동시에 반응기에 유입할 경우보다 구리의 씨앗층을 증착하고 요오드 화화물을 반응기에 유입한 후 다시 구리 증착을 진행하는 경우가 좀 더 효과가 컸다.