• 반도체디스플레이기술학회지
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• 제9권3호
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• pp.41-45
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• 2010

The ZnO thin films doped with Ga(GZO) and both Ga and Ge(GZO:Ge) were deposited on glass substrate by using RF sputtering system respectively. Structural, morphological and optical properties of the films deposited in the same condition were investigated. Structural properties of the films were investigated by Field Emission Scanning Electron Microscopy, FE-SEM images and X-ray diffraction, XRD analysis. These studies showed shape of films' surface and direction of film growth respectively. It's showed that all films were deposited by vertical orientation strongly. It can be confirmed that all dopants of targets were included in deposited films by results of EDX analysis. UV-Vis spectrometer results showed that all samples had highly transparent characteristics in visible region and have similar 3.28~3.31 eV band gap. It was found that existence of all dopants by EDX analysis. Morphology and roughness of surface of each film were clearly shown by Atomic Force Microscopy, AFM images. It was found in this research that film doped with Ge more dense and stable with hardly any difference in gap energy compared to ZnO films.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2889-2896
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• 2023

The waste acceptance criteria for heavy metals in mixed waste should be developed by reflecting the leaching behaviors that could highly depend on the repository design and environment surrounding the waste. The current standards widely used to evaluate the leaching characteristics of heavy metals would not be appropriate for the silo-type repository since they are developed for landfills, which are more common than a silo-type repository. This research aimed to explore the leaching behaviors of cementitious waste with Pb, Cd, and Sb metallic and oxide powders in an environment simulating a silo-type radioactive waste repository. The Toxicity Characteristic Leaching Procedure (TCLP) and the ANS 16.1 standard were employed with standard and two modified solutions: concrete-saturated deionized and underground water. The compositions and elemental distribution of leachates and specimens were analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES) and energy-dispersive X-ray spectroscopy combined with scanning electron microscopy (SEM-EDS). Lead and antimony demonstrated high leaching levels in the modified leaching solutions, while cadmium exhibited minimal leaching behavior and remained mainly within the cement matrix. The results emphasize the significance of understanding heavy metals' leaching behavior in the repository's geochemical environment, which could accelerate or mitigate the reaction.

• 반도체디스플레이기술학회지
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• 제22권4호
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• pp.53-58
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• 2023

The storage capacity of 3D-NAND flash memory has been enhanced by the multi-layer dielectrics. The deposition process has become more challenging due to the tight process margin and the demand for accurate process control. To reduce product costs and ensure successful processes, process diagnosis techniques incorporating artificial intelligence (AI) have been adopted in semiconductor manufacturing. Recently there is a growing interest in process diagnosis, and numerous studies have been conducted in this field. For higher model accuracy, various process and sensor data are required, such as optical emission spectroscopy (OES), quadrupole mass spectrometer (QMS), and equipment control state. Among them, OES is usually used for plasma diagnostic. However, OES data can be distorted by viewport contamination, leading to misunderstandings in plasma diagnosis. This issue is particularly emphasized in multi-dielectric deposition processes, such as oxide and nitride (ON) stack. Thus, it is crucial to understand the potential misunderstandings related to OES data distortion due to viewport contamination. This paper explores the potential for misunderstanding OES data due to data distortion in the ON stack process. It suggests the possibility of excessively evaluating process drift through comparisons with a QMS. This understanding can be utilized to develop diagnostic models and identify the effects of viewport contamination in ON stack processes.

• 반도체디스플레이기술학회지
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• 제15권4호
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• pp.27-32
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• 2016

In recent years, various researches have been conducted to improve process yields in accordance with miniaturization of semiconductor. APC(Advanced Process Control) is considered one of the methods to increase in process yields. APC is a process control technology that maintains optimal process conditions and improves the reliability of results by controlling and formulating the relationship among the various process parameters and results. We built up an optical diagnostic system with a three-channel spectrometer. The system detects signals those represent the changes of specific emission peaks intensity versus each reference and converts it into MFC control signals to get back the changes to the reference state. Controlling the MFC continues until the specific peak intensity changes into the normal state. Through this device, we tested a APC automatically responding to process changes during the plasma process. We could control gas flow while sputtering process on going and improve uniformity of plasma intensity with this system. Finally, we have got results those enhance the plasma intensity non-uniformity to 7.7% from 15.5%. Also, found unexpected oxygen flow what is estimated to be come out from IGZO target.

• 한국결정성장학회지
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• 제27권1호
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• pp.42-46
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• 2017

스컬용융법으로 $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ 형광체 합성을 하였으며, 합성한 형광체의 산화물 몰비는 $SrCO_3$ : $Al(OH)_3$ : $Eu_2O_3$ : $Dy_2O_3$= 1 : 2 : 0.015 : 0.02였다. 결정구조 및 표면 형상은 X-선 회절분석과 주사전자현미경으로 규명하였다. 합성한 $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$의 광학적 특성인 여기, 발광 및 장잔광 특성의 심도 있는 연구를 위해 PL(photoluminescence) 분광계로 측정하였다. PL 측정을 통해 360 nm 영역에서 여기(excitation)되고, 300~420 nm의 파장까지 여기가 일어남을 확인하였다. 발광(emission)스펙트럼은 450~600 nm의 파장에서 폭넓은 스펙트럼을 보였으며, 530 nm에서 최대 발광파장을 나타내었다. $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ 형광체는 오랜 시간 동안 발광하는 장잔광 특성을 나타내었다.

• Korean Chemical Engineering Research
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• 제50권4호
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• pp.684-689
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• 2012

Poly(acrylic acid) (PAA) 구형 입자는 바이오 분야의 소재에서부터 전자 재료에 이르기까지 다양한 분야에 사용되는 고분자 물질이다. 이를 생산하기 위해서는, 분산제(surfactant)를 이용한 중합 방법으로 합성을 한 후, 사용한 분산제를 제거하기 위한 별도의 Purification 과정을 거치게 된다. 일반 유기 용매를 사용하면 막대한 폐수 발생, 별도의 분리 공정 추가, 잔류 용매의 가능성 등의 문제점이 발생한다. 이에 이러한 문제를 해결하고자, 액체 이산화탄소를 용매로 하여, high-pressure Soxhlet extraction 방법을 개발하였다. 본 연구에서는 compressed liquid dimethyl ether (DME) 상에서 PAA 분산 중합에 사용된 pyrrolidene carboxylic acid-g-poly (siloxane) 계열의 분산제, Monasil PCA 제거하는 연구를 진행하였다. 추출된 PAA 입자의 모양은 field emission scanning electron microscopy (FE-SEM)으로 확인을 하였고, Monasil PCA의 농도는 Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES)로 분석하였다. 용매의 효과를 비교하기 위해서, 액체 이산화탄소와 n-hexane과 liquid DME를 대상으로 추출 실험을 하였다. 그 결과 n-hexane의 경우 일부 정제된 PAA 구형 입자를 얻을 수 있었지만, 일부는 n-hexane 증기의 높은 열에 의해서 변형된 형태의 입자를 얻었다. Liquid DME의 경우엔, 추출이 잘 되지 않았다. 액체 $CO_2$를 이용하는 경우에 구형의 형태는 유지하면서 분산제가 제거된 입자를 얻을 수 있었다. 그리고 최적 운전 조건을 알기 위해서 8시간 동안 재비기와 응축기의 온도를 달리하면서 실험을 실시하였다. 그 결과 추출기의 온도가 $19.6{\pm}0.2^{\circ}C$, 압력이 $51.5{\pm}0.5$ bar일 때, 가장 좋은 제거 효율을 보였다.

• 공업화학
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• 제28권1호
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• pp.101-111
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• 2017

광물탄산화 기술은 천연광물 및 산업부산물에 포함된 칼슘이나 마그네슘을 이산화탄소와 반응시켜 탄산염을 생성하는 기술로 이산화탄소를 열역학적으로 안정한 형태로 저장할 수 있는 기술이다. 본 연구는 철강슬래그를 이용한 이산화탄소 저감 및 추출 후 슬래그 재활용을 통해 환경적 부담 및 공정 비용 절감을 절감할 수 있는 광물탄산화 상용화 기술 개발을 목표로 설정하였다. 추출 용매(염화암모늄)를 사용하여 괴재 및 전로슬래그로부터 칼슘을 추출하고 추출된 칼슘을 이산화탄소와 반응시켜 순도 98% 이상의 탄산칼슘을 합성하였다. 또한 칼슘 추출 후 슬래그를 건축자재(패널)로 활용하는 기술을 개발하였다. 슬래그의 칼슘 추출효율에 따라 상이한 결과를 보였지만 광물탄산화 전체 공정에 있어 중량 비(약 80-90%)를 차지하는 칼슘 추출 후 슬래그(잔여슬래그)의 활용을 통해 광물탄산화 공정으로부터 배출되는 산업부산물의 양을 최소화하고자 하였다. 잔여슬래그는 시멘트 패널 제작에 활용되는 규사미분 대체 물질로서 이용하였고 기존 시멘트 패널과 물성평가(압축강도 및 휨강도)를 상호 비교하였다. 용액 내 칼슘 농도는 유도결합 플라즈마 분광분석기(Inductively coupled plasma optical emission spectrometer, ICP-OES)를 사용하여 분석하였다. 합성한 탄산칼슘은 X선 회절 분석법(X-ray diffraction, XRD)을 이용하여 결정학적 특성 및 정량 분석하였고 주사 전자 현미경(Field emission scanning electron microscope, FE-SEM)을 사용하여 표면 형상을 확인하였다. 시멘트 패널평가는 KS L ISO 679에 준하여 패널 제작 및 패널의 압축강도와 휨강도를 측정하였다.

• 한국전기전자재료학회논문지
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• 제29권9호
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• pp.546-551
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• 2016

$SrSnO_3:Tb^{3+}$ phosphor thin films were prepared on sapphire and quartz substrates in the growth temperature range of $100{\sim}400^{\circ}C$ by using the radio frequency magnetron sputtering deposition. The resulting $SrSnO_3:Tb^{3+}$ thin films were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible-infrared spectrophotometer, and photoluminescence spectrometer. The results indicated that the morphology, optical transmittance, band gap energy, and luminescence intensity of the phosphor thin films significantly depended on the growth temperature. All the thin films, regardless of the type of substrate, showed an amorphous behavior. As for the thin films deposited on sapphire substrate, the maximum crystallite size was obtained at a growth temperature of $400^{\circ}C$ and the strongest emission was green at 544 nm arising from the $^5D_4{\rightarrow}^7F_5$ transition of Tb3+. The average optical transmittance for all the thin films grown on sapphire and quartz substrates was decreased as the growth temperature increased from 100 to $400^{\circ}C$. The results suggest that the optimum growth temperatures for depositing highly-luminescent $SrSnO_3:Tb^{3+}$ phosphor thin films on sapphire and quartz substrates are 400 and $300^{\circ}C$, respectively.

• 한국산업보건학회지
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• 제29권1호
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• pp.34-41
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• 2019

Objective: This study is conducted to evaluate airborne lead concentration in and around lead production plant. Methods: Airborne lead concentration was monitored simultaneously inside of the processes of lead recycling factory and outside of factory which include stack, boundary of factory and residential area 1 km and 7.5 km from factory, respectively. All samples were measured three times at 1.5 m from the ground and analyzed using inductively coupled plasma mass spectrometer, inductively coupled plasma optical emission spectrometer or flame atomic absorption spectrometer. Results: All airborne lead concentrations measured inside of factory($13.9{\mu}g/m^3-252.9{\mu}g/m^3$) and outside of factory($0.001{\mu}g/m^3-54.97{\mu}g/m^3$) showed log-normal distribution. Geometric mean lead concentration, $54.81{\mu}g/m^3$, measured inside of factory was significantly higher than outside of factory, $0.20{\mu}g/m^3$(p<0.01). Among the samples measured inside the factory, lead concentration was the highest in the refining process($59.02{\mu}g/m^3-252.9{\mu}g/m^3$). In the case of the samples outside the factory, the nearest chimney was the highest($3.84{\mu}g/m^3-54.97{\mu}g/m^3$), and the lead concentration at the farthest place, 7.5 km from the factory was the lowest($0.001{\mu}g/m^3-1.7{\mu}g/m^3$). The arithmetic lead concentration, $0.45{\mu}g/m^3$ in the residential area near the factory was below the atmospheric environment standard of $0.5{\mu}g/m^3$, but the maximum concentration of $3.4{\mu}g/m^3$ was exceeded. Conclusions: Airborne lead concentration in residential area, 1 km away from lead recycling plant, may exceed ambient air standard of $0.5{\mu}g/m^3$.

• 한국진공학회지
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• 제17권2호
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• pp.102-108
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• 2008

대향 타겟식 스퍼터링법 (Facing Targets Sputtering)을 이용하여 유리기판위에 증착한 Ag/ZnO 다층 박막의 특성을 연구하였다. Ag 박막의 높은 전도도와 투과율을 나타내는 공정조건을 찾기 위하여, 증착시간, 기판온도 변화에 따른 Ag박막의 특성을 살펴보았으며, ZnO 박막의 두께 변화에 따른 Ag/ZnO 다층박막의 특성을 살펴보았다, 10초간 증착한 Ag 박막은 연속된 막구조를 가지지 못하여, 30초간 증착된 막에 비해 전기적, 광학적 특성이 저하되는 것을 확인할 수 있었다. ZnO 박막의 AFM 측정 결과 박막의 거칠기(Rrms) 값의 변화에 따라 Ag/ZnO박막의 특성에 영향을 미쳤으며, 거칠지 않은 표면을 지닌 박막에서 Ag 박막 증착 시 좋은 특성을 나타냈다. 제작된 박막은 four point probe, UV/VIS spectrometer, AFM을 사용하여 전기적, 광학적, 구조적 특성을 조사하였다. 제작결과 Ag/ZnO 다층박막의 면저항은 9.25 $[\Omega/sq.]$을 나타내었으며, 가시광영역에서 광투과율은 80%이상을 나타내었다.