• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.317-318
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• 2008

Cu-Pc유기물 반도체를 얼 진공증착기술로 유리기판위에 40 nm 두께로 적층하였다. 상온에서 적층한 박막과 상온에서 적층한 후 $250^{\circ}C$ 이상의 온도로 후열 처리한 박막과 박막 적층 시 기판의 온도를 $250^{\circ}C$로 고정하여 적층한 박막들을 상호 비교 분석하였다. 적층된 Cu-Pc의 박막의 온도조건에 따라 X-ray diffraction(XRD)의 결정 특성이 $\alpha$-phase와 $\beta$-phase로 뚜렷이 구분되었으며， 자외선-가시광선 영역의 광 흡수도(UV-visible absorption spectra)와 field emission scanning electron microscopy(FE SEM)를 이용하여 결정성장 방향 및 표면 특성 변화를 비교조사하였다.

• 열처리공학회지
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• 제5권4호
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• pp.215-223
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• 1992

This study has been performed to investigate into some effects of temperature, gas mixing ratio and time on the optical microstructure, hardness and wear characteristics of medium carbon alloy steel treated by plasma nitriding. The results obtained from the experiment are summarized as follows: (1) Optical micrographs of AISI 4140 steel plasma-nitrided by the double stage technique have revealed that the nitrided layer is composed of the compound layer and the diffusion layer. The variation in temperature at the first stage gives effects, on the formation of compound layer and the growth rate is shown to be relatively fast at $460^{\circ}C$. (2) The thickness of compound layer has been found to increase with increasing nitrogen percentage in the gas mixture and the holding time. It is therefore recommended that a shorter holding time and a lower nitrogen percentage are more effective to produce a tougher compound layer and a diffusion layer only. (3) X-ray diffraction analysis for AISI 4140 steel has shown that the compound layer consist of ${\gamma}^{\prime}-Fe_4N$ and ${\alpha}-Fe$ and that tough compound layer diffustion layer only can be obtained by the double stage plasmanitriding process. (4) There is also a tendency that the total hardened layer depth increases with increasing temperature, time and nitrogen percentage in the first stage during the double stage plasma nitriding. (5) The wear resistance of plasma nitrided specimens has been found thobe considerably increased compared to the untreated specimens and the amount of increment has appeared to increase further with increasing nitriding temperature, holding time and notrogen percentage of gas mixture in the first stage treatment.

• 공업화학
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• 제31권4호
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• pp.347-351
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• 2020

재료는 방사선과 상호작용을 통해 그 물리적, 화학적 특성이 변화하며 여러 방사선 중에서 전하를 띄고 있지 않아 침투깊이가 깊은 중성자 조사에 의한 금속소재의 조사손상은 원자력발전소의 안전과 관련해서 오랜 기간 동안 집중적인 연구대상이었다. 중성자 조사에 의한 조사손상은 초반 피코 초 스케일에서 벌어지는 원자단위의 점결함의 생성으로 시작되며 그 이후의 전개 양상은 전위 고리나 공극과 같은 미세구조상 결함으로 확인될 수 있다. 이러한 미세구조 상 결함의 형상과 분포에 따라 소재의 특성에 미치는 효과는 상이하게 된다. 그러므로 중성자 조건에 따른 미세구조를 예측하는 것은 매우 중요한 일로, 본 논문에서는 중성자 조사에 의한 재료 내의 미세구조 발달에 대해 리뷰한 뒤 조사된 소재의 미세구조 변화 예측에 널리 사용될 수 있는 상장 모델에 대해 간략히 소개하였다.

• 센서학회지
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• 제29권1호
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• pp.27-32
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• 2020

This study proposes a pixel-patterning method for organic light-emitting diodes (OLEDs) based on thermal transfer. An infrared lamp was introduced as a heat source, and glass type donor element, which absorbs infrared and generates heat and then transfers the organic layer to the substrate, was designed to selectively sublimate the organic material. A 200 nm-thick layer of molybdenum (Mo) was used as the lightto-heat conversion (LTHC) layer, and a 300 nm-thick layer of patterned silicon dioxide (SiO₂), featuring a low heat-transfer coefficient, was formed on top of the LTHC layer to selectively block heat transfer. To prevent the thermal oxidation and diffusion of the LTHC material, a 100 nm-thick layer of silicon nitride (SiN_x) was coated on the material. The fabricated donor glass exhibited appropriate temperature-increment property until 249 ℃, which is enough to evaporate the organic materials. The alpha-step thickness profiler and X-ray reflection (XRR) analysis revealed that the thickness of the transferred film decreased with increase in film density. In the patterning test, we achieved a 100 ㎛-long line and dot pattern with a high transfer accuracy and a mean deviation of ± 4.49 ㎛. By using the thermal-transfer process, we also fabricated a red phosphorescent device to confirm that the emissive layer was transferred well without the separation of the host and the dopant owing to a difference in their evaporation temperatures. Consequently, its efficiency suffered a minor decline owing to the oxidation of the material caused by the poor vacuum pressure of the process chamber; however, it exhibited an identical color property.

• 천문학회보
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• 제42권1호
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• pp.34.2-34.2
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• 2017

A small wide-field imaging telescope is a powerful instrument to survey the Universe: wide-field image can monitor the variability of many sources at a time, e.g. young stellar objects and active galactic nuclei, and it can be an effective way to locate transient sources without precise positional information such as gravitational wave sources or some gamma-ray bursts. In February 2017, we installed a 0.25 m f/3.6 telescope on the McDonald 0.8 m telescope as a piggyback system. With a $4k{\times}4k$ CCD camera, the telescope has a $2.35{\times}2.35deg$ field-of-view. Currently, it is equipped with Johnson UBVRI filters and 3 narrow-band filters: $H{\alpha}$, OIII and SII. We will present the installation process, and the telescope performance such as detection limit and image quality based on the data from commissioning observations. We will also discuss possible scientific projects with this system.

• 한국재료학회지
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• 제17권11호
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• pp.587-592
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• 2007

Al-42wt%Nb powder was prepared by high-energy mechanical milling(HEMM). The particle size, phase transformation and microstructure of the as-milled powder were investigated by particle size distribution (PSD) analyzer, scanning electron microscopy (SEM), X-ray diffractometery (XRD), transmission electron microscopy (TEM)and differential thermal analysis (DTA). The milled powders were heated to a sintering temperature at 1000C with under vaccum with vaccum tube furnace. Microstructural examination of sintered Ti-42wt%Nb alloy using 4h-milled powder showed Ti-rich phases (${\alpha}$-Ti) which are fine and homogeneously distributed in the matrix (Nb-rich phase: ${\beta}$-Ti). The sintered Ti-42wt%Nb alloy with milled powder showed higher hardness. The microstructure of the as quenched specimens fabricated by sintering using mixed and milled powder almost are same, but the hardness of as quenched specimen fabricated by using mixed powder increased due to solution hardening of Nb in Ti matrix. The aging effect of these specimens on microstructural change and hardening is not prominent.

• Composites Research
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• 제33권1호
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• pp.19-24
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• 2020

본 연구에서는 Poly(vinylidene fluoride) (PVDF) 필름 제작 과정 중 마이크로웨이브 처리 과정을 도입하여 β 결정성 향상에 어떠한 영향을 미치는지 분석하였다. 또한, 나노 입자 보강제로써 금속산화물인 TiO₂를 혼합하여 PVDF 복합재료 필름을 만들어, 전기적 음성도 차이로 인한 반데르발스 힘을 통해 β 결정 형성을 추가적으로 향상시키려고하였다. FTIR과 XRD 분석을통하여해당필름시편들에대해결정화도(Crystallinity) 및결정성(Crystalline)을 분석하였다. 이러한 분석 결과를 바탕으로, 용매 증발 과정 중 마이크로웨이브 처리 과정이 PVDF 필름의 결정화도를 높여주는 것을 확인하였고, 추가적인 연신(Stretching) 공정을 통해 α 결정에서 β 결정 변화(Crystalline phase change)가 발생함으로써 결과적으로 더 많은 β 결정성을 나타내었다. 그리고 금속산화물을 넣은 PVDF 복합재료 필름이 Neat PVDF 필름보다 상대적으로 더 높은 β 결정성을 나타내는 것을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.43-47
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• 2008

The nickel and cobalt resistance of Cupriavidus metallidurans CH34 is mediated by the CnrCBA efflux pump encoded by the cnrYHXCBAT metal resistance determinant. The products of the three genes cnrYXH transcriptionally regulate expression of cnr. CnrY and CnrX are membrane-bound proteins, probably functioning as anti-sigma factors, whereas CnrH is a cnr-specific extracytoplasmic functions (ECF) sigma factor. The periplasmic domain of CnrX (residues 29-148) was cloned as a N-terminal His-tagged protein, expressed in Escherichia coli, and purified using affinity chromatography and gel filtration. The molecular mass was estimated to be about 13.6kDa by size exclusion chromatography, corresponding to a monomer. The tetragonal bipyramid crystals were obtained by mixing an equal volume of protein in 50mM Tris-HCl, pH 7.5, 1% glycerol, 100mM NaCl, 1mM DTT, and the reservoir solution of 15% w/v PEG 2000, 100mM lithium chloride at 277K in 2-4 days using hanging drop vapor diffusion. The protein concentration was 24mg/ml. The crystal that diffracted to $2.42{\AA}$ resolution belongs to space group $P4_1\;or\;P4_3$ with unit cell parameters of $a=b=32.14{\AA},\;c=195.31{\AA},\;{\alpha}={\beta}={\gamma}=90^{\circ}$, with one molecule of CnrX in the asymmetric unit.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1998년도 제14회 학술발표회 논문개요집
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• pp.94-94
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• 1998

최근 a-CH:N (hydrogenated amorphous carbon nitride)가 a-CH 보다 팡학적, 기계객성 질이 우수하므로 이에 대한 연구가 활발하게 진행되고 있다. 본 실험에선 원료 가스의 유량 은 5 sccm으로 고정시킨 채 원료가스내의 질소 대 메탄 혼합비 (N2ICHa)훌 O 에서 4 까지 변 화시 키 띤서 DC saddle-field PECVD (plasma enhanced chemical vapour d야Xlsition)훌 이 용하여 a-CH:N 박막융 제작하여, 가스 혼합비가 박막의 미세구조와 광학척 성질에 미치는 영향올 연구하였다. 박막 성장시 진공조 내의 압력온 throttle valve롤 사용하여 90 mTorr로 일정하게 유지하였으며 양극 전압과 기판전업은 각각 500 V, 200 V로 고청하고 상온에서 중 착하였다. a a -step으로 측정 한 a-C:H:N 박막의 두께는 혼합가스내의 질소의 양이 증가할수륙 4800 A에서 2000 A로 두께가 감소하였지만 표면 rot핑비less는 혼합가스내의 질소의 양이 중가할 수록 중가함을 AFM (atomic force mi$\alpha$'0 scopy) 으로 관찰하였다. 박막내의 C와 N의 정량 분석은 RES (Rutherford back scattering s야ctroscopy) 핵공명법을 이용하여 분석하였다. X XPS (X -ray photoelectron spec$\sigma$oscopy) 와 FT-IR (Fo삐er transform-infrared s spectrometry)로 미세구조률 측정한 결과 혼합가스내의 질소의 양이 충가할수록 C-H기는 감 소하였지 만 C르N, N-H기 는 늘어 났다. 또한 PL (photoluminescence) 측정 결과 웬료가스 내 메탄과 질소의 비율이 1:1일 때 최대의 발광올 보였고 UVS (비없 vi이et spec$\sigma$orne$\sigma$y)으 로 측정한 광학쩍 에너지 캡은 혼합비내의 질소의 양이 증가할수록 2.53 eV에서 2.3 eV로 감 소하였다. 이를 결과로부터 원료가스내의 N2ICHa의 중가에 따른 박막의 미세구조 변화와 광학척 생 질의 상관 관계가 고찰될 것이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.183-183
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• 2011

Multiferroic materials have been widely studied in recent years, because of their abundant physics and potential applications in the sensors, data storage, and spintronics. $BiFeO_3$ is one of the well-known single-phase multiferroic materials with $ABO_3$ structure and G-type antiferromagnetic behavior below the Neel temperature $T_N$ ~ 643 K, but the ferroelectric behavior below the Curie temperature $T_c$~1,103 K. In this study, the $BiFe_{1-x}Ni_xO_3$ (x=0 and 0.05) bulk ceramics were prepared by solid-state reaction and rapid sintering with high-purity $Bi_2O_32$, $Fe_3O_4$ and NiO powders. The powders of stoichiometric proportions were mixed, as in the previous investigations, and calcined at 450$^{\circ}C$ for $BiFe_{1-x}Ni_xO_3$ for 24 h. The obtained powders were grinded, and pressed into 5-mm-thick disks of 1/2-inch diameter. The disks were directly put into the oven, which has been heated up to 800$^{\circ}C$ and sintered in air for 20 min. The sintered disks were taken out from the oven and cooled to room temperature within several min. The phase of samples was checked at room temperature by powder x-ray diffraction using a Rigaku Miniflex diffractometer with Cu K${\alpha}$ radiation. The Raman measurements were carried out by employing a hand-made Raman spectrometer with 514.5-nm-excitation $Ar^+$ laser source under air ambient condition on a focused area of 1-${\mu}m$ diameter. The field-dependent magnetization measurements were performed with a superconducting quantum-interference-device magnetometer.