• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1603-1607
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• 2012

The effects of plating process on the surface coverage of the accelerator were investigated in terms of Cu superfilling for device metallization. When a substrate having 500 nm-wide trench patterns on it was immersed in an electrolyte containing poly (ethylene glycol) (PEG)-chloride ion ($Cl^-$)-bis(3-sulfopropyl) disulfide (SPS) additives without applying deposition potential for such a time of about 100s, voids were generated inside of the electrodeposit. In time-evolved electrochemical analyses, it was observed that the process (immersion without applying potential) in the electrolyte led to the build-up of high initial coverage of SPS-Cl on the surface, resulting in the fast saturation of the coverage. Repeated experiments suggested that the fast saturation of SPS-Cl failed in superfilling while a gradual increase in the SPS-Cl coverage through competition with initially adsorbed PEG-Cl enabled it. Consequently, superfilling was achievable only in the case of applying the plating potential as soon as the substrate is dipped in an electrolyte to prevent rapid accumulation of SPS-Cl on the surface.

• 한국항공운항학회지
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• 제32권3호
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• pp.35-43
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• 2024

In domestic airport planning, capacity assessment traditionally focuses on comparing demand forecasts with runway capacity to identify saturation periods, which overlooks operational characteristics. Even when demand does not exceed capacity, prolonged near-capacity utilization can cause significant operational issues. Therefore, it is crucial to consider operational characteristics in capacity assessments to ensure stable airport operations and efficient development planning. This study uses the Capacity Coverage Chart to analyze the operational characteristics of Incheon Airport and major international airports. Based on the analysis, it suggests improving airspace and air traffic control procedures and utilizing off-peak hours to enhance operational efficiency at Incheon Airport. However, due to geopolitical constraints, increasing operational capacity at Incheon Airport is challenging. Thus, continuous efforts to expand infrastructure are necessary to meet future demand and prevent facility saturation.

• 한국산업융합학회 논문집
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• 제6권3호
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• pp.201-205
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• 2003

The effects of adsorption and desorption of alkali-metals on Si(111) surface were investigated by using AES and RHEED-system. The adsorption system is a fundamental interest because of its unique electronic properties such as measurement of work function change, adatom-core level shift. It was found that the growth node of K on Si(111) surface was layer by layer growth and the saturation coverage was 2.0ML at room temperature. Superstructure changes on Si(111) surface according to the alkali-metal thickness and substrate temperatures were accurately defined. By applying the isothermal desorption method, the desorption energies of Li/Si(111) and K/Si(111) surfaces was measured. On Li/Si(111) and K/Si(111) surfaces, the desorption energies were 3.07 eV, 2.19 eV respectively.

• Bulletin of the Korean Chemical Society
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• 제22권3호
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• pp.267-270
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• 2001

The adsorption of chlorine on a Pt(111) surface at 90 K has been studied using scanning tunneling microscopy (STM) in ultra-high vacuum environments. The adsorbed chlorine atoms give rise to two different ordered structures, (3${\times}$3)-Cl and c(4${\times}$2)- Cl, depending on the coverage. It has been determined from the STM image that the absolute coverage of (3${\times}$3)-Cl structure is 0.44, which is not in agreement with coverage calibrated by a low energy electron diffraction technique together with an Auger electron spectrometer and a thermal desorption spectrometer. The Cl atoms bound to on-top sites at the Pt(111)(3${\times}$3)-Cl surface appeared to effectively perturb the density of states of Pt atoms, as compared with that bound to bridging sites. The other ordered structure, c(4${\times}$2)-Cl, with small domain sizes, consists of both on-top and bridge-bonded species with a saturation coverage of 0.5.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.61-61
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• 2010

By using high resolution x-ray photoelectron spectroscopy, we show that inelastic scattering of photoelectron at low temperature (30K~50K) generates two kinds of oxygen species on Pt (111) surface. Intense synchrotron radiation source dissociates oxygen molecules into chemisorbed atomic oxygen and induces the formation of PtO on surface. Estimated coverage of dissociated atomic oxygen is 0.5 ML, suggesting possible formation of p($2{\times}1$) surface structure, while PtO coverage shows saturation coverage of 0.5 ML. Molecular oxygen dosed at 30 K undergoes thermally activated transition from physisorbed to chemisorbed state at around 40K.

• 대한교통학회지
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• 제34권1호
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• pp.81-94
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• 2016

교통신호를 가변 운영하는 실시간신호제어시스템은 방향별 움직임 포화도 추정을 위해 이론 기반 모형을 활용하나, 현장구축 실무에선 지침 부재로 모형에 고려되지 않은 운영상황에도 시스템을 설치하여 왔다. 본 연구는 서울시 실시간신호제어시스템 서버 운영 이력자료를 활용하여 교통조건, 기하구조 조건, 검지기 설치위치 등 현장여건에 따른 실시간신호제어시스템 포화도 모형의 포화도 추정 패턴을 진단한다. 총 476,505 신호주기 이력자료를 분석하여 직진 움직임 포화도를 진단한 결과 (1) 검지기가 모든 직진차로에 설치될 때 일부차로에 표본 설치되는 상황보다 포화도 추정이 안정적으로 판단되고, (2) 가로변버스전용차로가 존재하는 경우는 오히려 검지기를 일부 차로 표본 설치하는 것이 안정적으로 분석되며, (3) 공유차로 포함 차로군 검지기가 활용되는 경우 차량간섭으로 인해 포화도 추정이 정상적이지 않은 것으로 분석되고, (4) 검지기가 전용차로에 설치되더라도 공유차로에 인접한 경우도 차량간섭에 지속 영향 받아 포화도 추정이 어렵고, (5) 하루 24시간 중 특정시간은 교통흐름 속성에 따라 포화도 추정이 안정적이지 않을 수 있다는 내용이 진단되었다. 이러한 진단결과를 종합하여 향후 포화도 추정모형 개발단계 및 시스템 현장구축 단계에서 참조 가능한 기술발전 방향을 제언한다.

• Bulletin of the Korean Chemical Society
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• 제16권2호
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• pp.143-148
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• 1995

Ketene (CH2CO) adsorption on Ag(111) has been studied in ultrahigh vacuum using electron energy loss spectroscopy and temperature programmed desorption. Ketene adsorbs molecularly on Ag(111) at temperatures below 126 K. The coverage increases linearly with exposure until saturation. No multilayer formation and no shift in desorption temperature with coverage were observed, indicating a lack of attractive interaction between adsorbate molecules. The desorption activation energy is estimated to be 7.8 kcal/mol by assuming first order kinetics and a pre-exponential factor of 1013 sec-1. The adsorption geometry of ketene on the surface is determined from the relative intensities of the vibrational energy loss peaks. The CCO axis of CH2CO is found to be almost parallel to (∼4°away from) the surface and the molecular plane is almost perpendicular to the surface (∼3°tilt).

• Bulletin of the Korean Chemical Society
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• 제23권3호
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• pp.395-399
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• 2002

The voltammetric behavior of spontaneously adsorbing Mo layers on Pt(111) and Pt(100) electrodes has been studied to estimate the number of electrons involved in the electrochemical processes of spontaneously adsorbed Mo and the number of the bloc ked Pt sites for hydrogen adsorption. On Pt(111) and Pt(100) surfaces, the spontaneously adsorbed Mo layers showed redox peaks at 0.10 V and 0.15 V, respectively, and continuous current-potential waves in the conventional hydrogen region. Since the potential range of the Mo redox processes on both surfaces overlapped partially with the potential range of hydrogen adsorption, the variation in the ratio of the total charge of Mo and H ($Q_H$ +$Q_{MO}$) to the hydrogen charge of clean Pt electrode ($Q_H^0$) was analyzed. From the analysis, six electrons were estimated to be involved in the electrochemical processes of the spontaneously adsorbed Mo, and four Pt sites for hydrogen adsorption were calculated to be blocked by one adsorbed Mo atom. Based on these figures and the pH dependence of the Mo redox processes, we have proposed an electrochemical equation for the spontaneously adsorbed Mo. This electrochemical equation led us to conclude that the saturation coverage of the spontaneously adsorbed Mo is 0.25. The coverage of Mo less than 0.25, however, could not be determined voltammetrically due to the convolution of the charges of Mo and H.

• Journal of Positioning, Navigation, and Timing
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• 제8권4호
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• pp.215-223
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• 2019

This paper analyzes navigation performances of the Korean Positioning System (KPS) constellation with respect to the orbit parameters which fulfills the specification requirements. Specifically, the satellite configuration and navigation requirements of KPS are explained, and the daily mean horizontal dilution of precision (HDOP) and satellite visibility on KPS coverage are analyzed to confirm the adequate orbit parameters. However, due to orbital slot saturation, geostationary-orbit (GEO) satellites may not be allocated in the original orbit as specified in the KPS requirements. Therefore, in a spanned window of 4 degrees from the reference longitude the navigation performance of each GEO satellite orbit is investigated.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.191-196
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• 2005

The effects of shot peening on the fatigue strength of SK-5M steel is investigated by experiment. The shot peening process is investigated optimum peening condition by changing impeller speed and exposure time. Bending fatigue test is accomplished to investigate the effect of optimum peening condition on the fatigue characteristics. As exposure time is increased, fatigue life in high stress is increased in early stage, become the maximum from 60 to 100 seconds, and then is decreased. Observing fracture surface through SEM after fatigue test, we can see clear configuration of cracks and peening layer.