• 한국세라믹학회지
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• 제51권6호
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• pp.533-538
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• 2014

Today, silicon and epoxy resin are used as materials of conversion lenses for white LEDs on the basis of their good bonding and transparency in LED packages. But these materials give rise to long-term performance problems such as reaction with water, yellowing transition, and shrinkage by heat. These problems are major factors underlying performance deterioration of LEDs. In this study, in order to address these problems, we fabricated a conversion lenses using glass, which has good chemical durability and is stable to heat. The fabricated conversion lenses were applied to a remote phosphor type. In this experiment, the conversion lens for white LED was coated on a glass substrate by a screen printing method using paste. The thickness of the coated conversion lens was controlled during 2 or 3 iterations of coating. The conversion lens fabricated under high heat treatment temperature and with a thin coating showed higher luminance efficiency and CCT closer to white light than fabricated lenses under low heat treatment temperature or a thick coating. The conversion lens with $32{\mu}m$ coating thickness showed the best optical properties: the measured values of the CCT, CRI, and luminance efficiency were 4468 K, 68, and 142.22 lm/w in 20 wt% glass frit, 80 wt% phosphor with sintering at $800^{\circ}C$.

• 소성∙가공
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• 제15권5호
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• pp.366-372
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• 2006

The effect of coating time in arc ion plating on surface properties of the TiN-coated high speed steel(SKH51) is presented in this paper. Surface roughness, micro-hardness, coated thickness, atomic distribution of TiN and adhesion strength are measured for various coating times. It has been shown that the coating time has a deep influence on the micro-hardness, the coated thickness, the atomic distribution of Ti and the adhesion strength of the SKH51 steels but that it has little influence on the surface roughness.

• 한국해양공학회지
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• 제17권6호
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• pp.77-82
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• 2003

The absorption of water into an anti-corrosive organic coating, such as alkyd and urethane resin coating, was investigated, using a quartz crystal microbalance (QCM). Anticorrosive properties of the coatings were also measured, by means of electrochemical impedance spectroscopy (EIS). The overall absorption of water in the coating is determined by the chemical nature of resin, and decreases with increasing thickness. The enhancement of anti-corrosive performance, through increase of coating thickness, was more remarkable in the case of the coating that hadlower equilibrium water absorption. The absorption kinetics curves were Fickian in nature. The EIS analysis confirmed that the resin, having lower equilibrium water absorption, shows higher anti-corrosive performan.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.1928-1937
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• 2003

Effect of elastic modulus mismatch on the contact crack initiation is investigated to find major parameters in designing desirable surface-coated system. Silicon nitride coated soft materials with various elastic modulus mismatch, E$\_$c//E$\_$s/＝1.06∼356 are prepared for the analysis. Hertzian contact test is conducted for producing contact cracks and the acoustic emission detecting technique for measuring the critical load of crack initiation. The implication is that coating thickness and material strength are controllable parameters to prevent the initiation of contact cracks resulted from the elastic modulus mismatch in the hard ceramic coating layer on the soft materials.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.59-64
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• 2001

The fluid flow, mass transfer and film thickness variation during a wafer spin coating process are numerically studied. Governing equations for the cylindrical coordinates are simplified using the similarity transformation and solved efficiently using the finite difference method. Concentration dependent viscosity and the binary diffusivity of the coating liquid are used in the analysis. The time variational velocity components of the coating liquid and the film thickness are analyzed according to the various spin speed. When the evaporation is considered, the flow decease in the early times due to the increase of the viscosity and the resultant flow resistance. Effects of the two film thinning mechanism, the flow-out and evaporation are also considered in the analysis.

• 대한조선학회논문집
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• 제45권6호
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• pp.637-645
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• 2008

It is very hard to control the quality of coating work in shipbuilding process, because it is highly affected by several parameters such as space between object and nozzle tip, spray velocity, pressure, tip size, etc.. Even so a coating work in shipbuilding is done by workers' experience and skill as yet. It causes not only an excessive use of paints but also a decrease of productivity. In order to solve this problem, we developed a formula that predicts the film thickness and determined the proper coating pattern. Also we had done a series of experiments to verify the results of this study.

• 한국주조공학회지
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• 제7권2호
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• pp.122-132
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• 1987

Full mold casting process is a new technique offering numerous advantages and promising possibilities. The present study is aimed to bring out the results of experiments carried out to study the effect of pattern coatings on the solidification of 99.5% pure aluminum plate-shaped castings in the various sand molds and the thermal behavior of the molds. The results of the investigation indicate that (i) with increase in pattern coating thickness, the relative chilling power decreases gradually for silica and increases for zircon coating, and (ii) the application of a pattern coating significantly reduces the maximum interface temperature by the mold which is more pronounced in the case of thinner mold wall. The investigation also indicates that Chvorinov's rule is not found to be valid for the casting in the full mold, with or without pattern coating. Therefore in full mold process, the pattern coating thickness will be a very important parameter in the study of thermal behavior.

• 한국표면공학회지
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• 제27권5호
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• pp.303-311
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• 1994

In this study, the factors, such as coating temperature T(K), reaction time t(sec) and mobile carbon content $C^*$ (wt%) of steels affecting, the growth rate of carbide layer were investigated in the reactive deposition and diffusion coating using the fluidized bed. From the results, the coating thickness d(cm) can be expressed by an equation. d=$C^*$$(KT)^{1/2}$, where K=K$\circ$exp(~Q/RT), KTEX>$\circ$ = 1.4$\times$$10^{-2}cm^{-2}$/sec, and Q=46Kcal/ mol. It was in a good aggrement with the experimental results, reguardless of the diffusion coating method and the carbide layer. Therefore, if the mobile carbon content of carbon steels and alloyed steels is known, the thickness under coating conditions can be predicted from the previous equation.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.585-591
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• 2013

페키지형 발전시스템용 라디에이터를 균일한 두께로 코팅할 수 있는 로봇자동화 시스템을 개발하였다. 이 시스템은 스프레이 건을 부착한 6축 로봇, 로봇을 주행방향으로 이송하는 주행대차, 공압과 함께 도료와 신너를 공급하는 장치, 제어장치 및 로봇경로 오프라인프로그램으로 구성되어 있다. 최적운전 조건으로 코팅로봇 자동화 시스템을 사용하여 라디에이터를 코팅한 결과, 평균 코팅두께가 $43{\mu}m$로서 규정치인 $25-100{\mu}m$을 만족하였다. OLP를 활용한 코팅로봇 자동화 시스템의 생산성은 기존 수작업의 12.6 배로 향상되었다.

• 한국분말재료학회지
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• 제20권4호
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• pp.245-252
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• 2013

This study attempted to manufacture a Cu-Ga coating layer via the cold spray process and to investigate the applicability of the layer as a sputtering target material. In addition, changes made to the microstructure and properties of the layer due to annealing heat treatment were evaluated, compared, and analyzed. The results showed that coating layers with a thickness of 520 mm could be manufactured via the cold spray process under optimal conditions. With the Cu-Ga coating layer, the ${\alpha}$-Cu and $Cu_3Ga$ were found to exist inside the layer regardless of annealing heat treatment. The microstructure that was minute and inhomogeneous prior to thermal treatment changed to homogeneous and dense with a more clear division of phases. A sputtering test was actually conducted using the sputtering target Cu-Ga coating layer (~2 mm thickness) that was additionally manufactured via the cold-spray coating process. Consequently, this test result confirmed that the cold sprayed Cu-Ga coating layer may be applied as a sputtering target material.