• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.161-164
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• 2006

This paper introduces a preliminary work for the design of a mini-dish cluster system for power general ion. Each mini-dish (typically has a 20 to 30cm in diameter) is designed with a simple parabolic profile, concentrating sun light (after the glass glazing cover to avoid dust deposition on the reflector and facilitate cleaning) onto a centrally located small plane(or concave) mirror which is placed on the bottom side of the transparent glass cover. The mirror with a mini-dish concentrator is designed to focus beam radiation onto a focal point before it enters a bundle of optical fibers connected to a remote receiver for power generation different options are considered In designing a mini-dish concentrator to maximize its effectiveness for the collection and use of solar energy.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.6-6
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• 1992

Ionized cluster beam deposition (ICBD) technique has been employed to fabricate high-purity crystalline polyimide (PI) film. The pyromellitic dianhydride (PMDA) and oxydianiline (ODA) were deposited using dual ICB sources, Fourier trans forminfraredspectroscopy (FT-IR), X-ray photoemission spectroscopy (XPS), and Transmission electron microscopy (TEM)study show that the bulk and surface chemical properties and the crystalline structure are very sensitive to the ICBD conditions such as cluster ion acceleration voltage and ionization voltage, At optimum ICBD conditions, the PI films have a maximum imidization, negligible impurities(∼1% isoimide), and a good crystalline structure probably due to the high surface migration energy and surface cleaning effect. These characteristics are superior to those of films deposited by other techniques such as colvent cast, vapowr deposition, or sputtering techniques.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.34-42
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• 2021

Recent cleaning technologies of mask in extremely ultraviolet semiconductor processes were reviewed, focused on newly developed issues such as particle size determination or hydrocarbon and tin contaminations. In detail, critical particle size was defined and proposed for mask cleaning where nanosized particles and its various shapes would result in surface atomic ratio increase vigorously. A new cleaning model also was proposed with amphoteric behavior of electrolytically ionized water which had already shown excellent particle removing efficiency. Having its non-equilibrium and amphoteric properties, electrolyzed ion water seemed to oxidize contaminant surface selectively in nano-scale and then to lift up oxidized ones from mask surface very effectively. This assumption should be further investigated in future in junction with hydrogen bonding and cluster of water molecules.

• Environmental Engineering Research
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• v.24 no.2
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• pp.279-288
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• 2019

To obtain insightful knowledge of geochemical process controlling fluoride enrichment in groundwater of the villages near Shilabati river bank, West Bengal, India, multivariate statistical techniques were applied to a subgroup of the dataset generated from major ion analysis of groundwater samples. Water quality analysis of major ion chemistry revealed elevated levels of fluoride concentration in groundwater. Factor analysis (FA) of fifteen hydrochemical parameters demonstrated that fluoride occurrence was due to the weathering and dissolution of fluoride-bearing minerals in the aquifer. A strong positive loading (> 0.75) of fluoride with pH and bicarbonate for FA indicates an alkaline dominated environment responsible for leaching of fluoride from the source material. Mineralogical analysis of soli sediment exhibits the presence of fluoride-bearing minerals in underground geology. Hierarchical cluster analysis (HCA) was carried out to isolate the sampling sites according to groundwater quality. With HCA the sampling sites were isolated into three clusters. The occurrence of abundant fluoride in the higher elevated area of the observed three different clusters revealed that there was more contact opportunity of recharging water with the minerals present in the aquifer during infiltration through the vadose zone.

• Journal of the Korean Vacuum Society
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• v.13 no.1
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• pp.22-28
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• 2004

Ta films were deposited on Si (100) substrates at zero substrate bias voltage and a substrate bias voltage of -125 V ($V_{s}$ = -125 V) using a non-mass separated ion beam deposition system. To investigate the effect of the negative substrate bias voltage on the impurity concentration in the Ta films, secondary ion mass spectrometry (SIMS) was used to determine impurities in the Ta films. By the SIMS depth profiles with $Cs^{+}$ cluster ion beam, high intensities of O, C and Si were clearly found in the Ta film at $V_{s}$ = 0 V, whereas these impurities remarkably decreased in the Ta film at $V_{s}$ = -125 V. Furthermore, from the SIMS result with $Cs^{+}$ and $O_2^{+}$ ion beams, it was found that applying the negative substrate bias voltage could affect individual impurity contents in the Ta films during the deposition. Discussions concerning the effect of the negative substrate bias voltage on the impurity concentration of Ta films will be described in details.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.237-242
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• 2003

투어멀린(Tourmaline)은 비대칭 쌍극자를 가진 유극성 결정체로 광물 중에서 영구적으로 전기분극 특성을 띄고 있는 유일한 물질로써, 일명 "전기석"이라고 알려져 있다. 자체의 미약 전류(약 0,06mA)와 함께 음이온 및 원적외선의 발생으로 최근 우리 주변에서 건강과 환경정화를 위한 관심 대상의 투어멀린은 육방정계의 압전성 및 초전성을 띄는 붕규산염으로, 물분자를 만나면 수소($H^+$)와 수산기($OH^-$)로 분해하여 친수기와 소수기를 구분하여 발생하며, $H^+$와 $OH^-$는 각각 $H_2O$와 결합하여 활성이 강한 hydronium ion($H_3O^+$)과 계면활성 작용이 있는 hydroxyl ion($H_3O_2^-$)을 생성한다. 물속에서 불안정한 상태로 존재하는 수산기는 hydroxyl (-)ion을 형성하여 약 알카리성($pH{\sim}7.4$)을 띄고, 물의 클러스터(cluster)를 세분화하는 수질개선 기능과 함께 살균, 항균 및 세균번식억제 효과를 갖는 것으로 확인되었다. 따라서 투어멀린 소결체를 활용하여 그 처리수의 특성조사 및 기능개발과 함께 대장균의 번식억제 작용 및 살균작용과 수질개선 기능 등 유용한 결과의 분석으로부터 다양한 응용성을 확보하였다.

• Journal of the Korean Ceramic Society
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• v.34 no.11
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• pp.1121-1128
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• 1997

In this study, the Ar plasma treatment was used to improve the surface roughness of Poly-Si1-xGex thin film deposited by RTCVD. The surface roughness and the resistivity of Si1-xGex thin film were investigated with variation of Ar plasma treatment parameters (electrode distance, working pressure, time, substrate temperature and R.F power). When the Ar plasma treatment was used, the cluster size decreased by the surface etching effect due to the increasing surface collision energy of particles (ion, neutral atom) in plasma under the conditions of decreasing electrode distance and increasing pressure, time, temperature, and R. F power. Although the surface roughness value decreased by the reduction of the cluster size due to surface etching effect, however, the resistivity increased. This may be due to the surface damage caused by the increasing surface collision energy. It was concluded that the surface roughness could be improved by the Ar plasma treatment, while the resistivity was increased by the surface damage on the substrate.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.109.1-109.1
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• 2011

Shock waves are ubiquitous in astrophysical environments. In particular, shocks formed by merger of subclumps, infall of matter and internal flow motion in intracluster media (ICMs) and cluster outskirts are relatively weak with Mach number M ${\lesssim}$ a few. At such weak shocks, it has been believed that the diffusive shock acceleration (DSA) of cosmic rays is rather inefficient. Yet, the presence of nonthermal phenomena, such as radio halos and relics, suggests that contrary to the expectation, DSA as well as magnetic field amplification should operate at weak shocks in cluster environments. We recently initiated a study of weak, collisionless, astrophysical shocks using a PIC(Particle-in-Cell) code. The PIC code describes the motion of electron and ion particles under the electromagnetic field which is represented in grid zones. Here, we present a preliminary work of one-dimensional simulations. We show how shocks are set up as the turbulent electromagnetic field is developed in the shock transition layer, and discuss the implication on DSA and magnetic field amplification.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.207-207
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• 2013

증착온도 $700^{\circ}C$, 산소분압30mTorr에서 c-plane 사파이어 기판위에 PLD를 이용하여 ZnO nano-rod를 합성하였다. 거리가 멀어질수록 rod의 직경과 증착율이 감소하는 것을 확인 하였다. 이는 ablated particle이 가진 kinetic energy가 감소되고, cluster ion의 형성으로 인해 고온에서 rod가 형성될 수 있는 것으로 이해된다. 고진공에서는 kinetic energy가 감소되기 어렵기 때문에 nano-rod shape 형성은 불가능 할 것이며, ZnO와 같은 wurtzite 구조를 가진 물질의 타겟을 사용하여 cluster 형성 분위기에서 증착한다면 비슷한 경향을 나타낼 것으로 예상된다.

• Applied Microscopy
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• v.50
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• pp.27.1-27.6
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• 2020

Transition metal dichalcogenides (TMD), which is composed of a transition metal atom and chalcogen ion atoms, usually form vacancies based on the knock-on threshold of each atom. In particular, when electron beam is irradiated on a monolayer TMD such as MoS₂ and WS₂, S vacancies are formed preferentially, and they are aligned linearly to constitute line defects. And then, a hole is formed at the point where the successively formed line defects collide, and metal clusters are also formed at the edge of the hole. This study reports a process in which the line defects formed in a monolayer WS₂ sheet expends into holes. Here, the process in which the W cluster, which always occurs at the edge of the formed hole, goes through a uniform intermediate phase is explained based on the line defects and the formation behavior of the hole. Further investigation confirms the atomic structure of the intermediate phase using annular dark field scanning transition electron microscopy (ADF-STEM) and image simulation.