• 한국전기전자재료학회논문지
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• 제22권10호
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• pp.890-896
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• 2009

Li(Ni, Co, Mn)$O_2$ has been known as one of the most promising cathode materials for lithium secondary batteries. However, it has some problems to overcome for commercialization such as inferior rate capability and unstable thermal stability. In order to address these problems, surface modification of cathode materials by coating has been investigated. In the coating techniques, selection of coating material is a key factor of obtaining enhanced properties of cathode materials. In this work, we introduced solid electrolyte (Li-La-Ti-O) as a coating material on the surface of $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ cathode. Specially, we focused on a rate performance of Li-La-Ti-O coated $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ cathode. Both bare and Li-La-Ti-O 2 wt.% coated sample showed similar discharge capacity at 0.5C rate. However, as the increase of charge-discharge rate to 3C, the coated samples displayed better discharge capacity and cyclic performance than those of bare sample.

• 한국산업융합학회 논문집
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• 제22권6호
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• pp.785-795
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• 2019

This paper is a study on the modeling of the quantity estimation model for offshore plant Material handling equipment in FEED(Front End Engineering Design) verification stage using system engineering approach which is an engineering design methods. The relevant engineering execution procedure is not systemized although the operation method and Material handling equipment selection with weight and space constraints is a key part of the FEED. Using the system engineering process, the stakeholder requirements analysis process, the system requirements analysis, and the final system architecture design were sequentially performed, and the process developed through the functional development diagram and Requirement traceability matrix (RTM) was verified. In addition, based on the established process, we propose a Material handling quantity estimation model and Quantity calculation verification Table that can be applied at the FEED verification stage and we verify the applicability through case studies.

• 한국세라믹학회지
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• 제56권1호
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• pp.98-103
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• 2019

Optical filters to control light wavelength of displays or cameras are fabricated by multi-layer stacking process of low and high index thin films. The process of multi-layer stacking of thin films has received much attention as an optimal process for effective manufacturing in the optical filter industry. However, multi-layer processing has disadvantages of complicated thin film process, and difficulty of precise control of film morphology and material selection, all of which are critical for transmittance and coloring effect on filters. In this study, the composite $TiO_2$, which can be used to control of UV absorption, coated on nano hollow silica sol, was synthesized as a coating material for optical filters. Furthermore, systematic analysis of the process parameters during the chemical reaction, and of the structural properties of the coating solutions was performed using SEM, TEM, XRD and photo spectrometry. From the structural analysis, we found that the 85 nm nano hollow silica with 2.5 nm $TiO_2$ shell formation was successfully synthesized at proper pH control and titanium butoxide content. Photo luminescence characteristics, excited by UV irradiation, show that stable absorption of 350 nm-light, correlated with a 3.54 eV band gap, existed for the $TiO_2$ shell-nano hollow silica reacted with 8.8 mole titanium butoxide solution. Transmittance observed on substrate of the $TiO_2$ shell-nano hollow silica showed effective absorption of 200-300 nm UV light without deterioration of visible light transparency.

• 한국지반공학회논문집
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• 제23권8호
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• pp.149-158
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• 2007

최근 들어 포항지역에서 매립이나 도로성토를 위한 양질의 재료 취득이 점점 더 어려워지고 있다. 따라서 이암을 도로나 항만 등의 공사에서 성토재료나 매립재로 활용하려는 시도가 진행되고 있다. 그러나 이암을 매립재로 활용한 예가 없으며 또한, 이암을 이용한 매립지반의 거동 특성에 대해 명확하게 밝혀지지는 않았다. 이암을 매립재료로 활용하기 위해서는 이암의 흡수, 연화, 슬레이킹등의 거동특성을 파악하여 향후 발생할 수 있는 침하나 강도저하등에 대한 명확한 정보를 파악해야 한다. 그러나 이에 대한 이암의 공학적 특성이 명료하지가 않다. 본 연구에서는 이암을 도로 기초나 항만 등의 성토나 매립재료로 사용시 그 적합성을 실내시험과 시험시공을 통해 파악코자 하였다.

• 한국환경생태학회지
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• 제33권4호
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• pp.472-480
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• 2019

도심지 내 미세먼지 저감 식재를 위한 식물 소재 선정 시에는 식물의 흡착 기능에 영향을 미치는 식물의 잎 모양, 질감, 수피의 형태 등 형태적 특성을 종합적으로 고려하여 선정하여야 한다. 그러나 지금까지 식물을 통한 미세먼지 저감에 대한 연구는 식물의 흡착 기능보다 흡수 기능에 대한 연구가, 실외식물보다 실내식물인 관엽식물을 대상으로 한 연구가 주로 진행되어 왔다. 특히, 미세먼지 저감 수종 선정 기준이 구체적이지 않아 미세먼지 저감 식재를 위한 식물 소재 선정 기준에 대한 연구가 필요한 실정이다. 본 연구는 퍼지다기준 의사결정법(Fuzzy MCDM)을 활용하여 미세먼지 저감에 영향을 미치는 8가지 지표 항목에 대한 우선순위를 도출하고 도심 내 미세먼지 저감 식재를 위한 수종 선정 기준을 마련하였다. 이를 위하여 미세먼지 관련 분야 전공자와 미세먼지 관련 연구 경험자들을 대상으로 설문 조사를 실시하였다. 설문 조사 분석 결과, 미세먼지 저감에 영향을 미치는 지표 항목 중 잎 면적과 수종의 종류가 가장 높은 순위를 나타냈다. 그리고 잎 표면의 거칠기, 수고, 성장 속도, 잎의 복잡성, 잎 가장자리 형태, 수피 특징 순서로 우선순위가 높게 나타났다. 잎 표면이 거친 수종을 선정할 경우에는 잎에 털이 있고, 광택이 나며, 왁스층이 있는 수종을 우선적으로 선정하는 것이 좋다. 잎의 형태를 고려할 경우, 단일 잎보다 3종 혹은 2종 잎과 손바닥 형태의 잎을 선정하고, 잎의 가장자리는 밋밋한 모양보다는 톱니 모양의 잎을 선별하여 공기 중의 미세먼지가 잎의 표면에 흡착되는 표면적 비율을 높아지게 할 필요가 있다. 수피의 특성을 고려할 경우에는 피목이나 무늬종보다는 코르크층이 있고 껍질이탈이나 갈라짐이 관찰되거나, 앞으로 관찰될 가능성이 높은 수종을 선정하는 것이 바람직하다. 본 연구는 도심 내 미세먼지 저감을 위한 식재계획 시 식물의 미세먼지 흡착 기능에 영향을 미치는 식물의 형태적 특성을 중심으로 식물 소재 선정 기준에 대한 우선순위를 제시하였다는 것에 의의가 있다. 본 연구에서 도출한 결과는 도심지 내 수목 식재 계획을 위한 수종 선정 시 기초 자료로서 활용될 수 있을 것이다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2006년도 ISMP 2006
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• pp.67-73
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• 2006

A system in package (SiP) generally contains a variety of systems such as analog, digital, optical and micro-electro-mechanical systems, integrated in a system-level package connected through a substrate. However, there are many electrical and mechanical reliability issues including the reliability issue for embedded structures. A mismatch of thermal coefficients of expansion among packaging materials and devices can lead to warping or delamination in the package. In this study, the effect of material properties of underfill, such as Young's modulus and CTE, are investigated through FEM simulation. Experimental investigation on the warpage of the package is also carried out to verify the simulation results. The results show that the reliability of the system in package is closely related to the material properties of underfill. The results of this study provide a good guidance for the material selection when designing the system in package.

• 산업경영시스템학회지
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• 제36권2호
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• pp.81-90
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• 2013

Material flow control (MFC) is a kind of operational policy to control of the movement of raw materials, components, and products through the manufacturing lines. It is very important because it varies throughput, line cycle time, and work-in-process (WIP) under the same manufacturing environments. MFC can be largely categorized into three types such as Push, Pull, and Hybrid. In this paper, we set various manufacturing environments to compare five existing MFC mechanisms: Push, Pull, and Hybrid (CONWIP, Gated MaxWIP, Critical WIP Loops, etc). Three manufacturing environments, manufacturing policies (make to stock and make to order), demand (low, medium, high), and line balancing (balanced, unbalanced, and highly unbalanced) are considered. The MFCs are compared in the point of the five functional efficiencies and the proposed compounded efficiency. The simulation results shows that the Push is superior in the functional efficiency and GMWIP is superior in the compounded efficiency.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권4호
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• pp.237-248
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• 2015

"Dynamic stabilization" systems have been developed in recent years to treat degenerative disorders of the spinal column. In contrast to arthrodesis (fusion), the aim here is to conserve intervertebral mobility to maximize comfort. When developing innovative concepts, many mechanical tests need to be carried out in order to validate the different technological solutions. The present study focuses on the B Dyn$^{(R)}$ "dynamic stabilization" device (S14$^{(R)}$ Implants, Pessac, France), the aim being to optimize the choice of polymer material used for one of the implant's components. The device allows mobility but also limit the range of movement. The stiffness of the ring remains a key design factor, which has to be optimized. Phase one consisted of static tests on the implant, as a result of which a polyurethane (PU) was selected, material no.2 of the five elastomers tested. In phase two, dynamic tests were carried out. The fatigue resistance of the B Dyn$^{(R)}$ system was tested over five million cycles with the properties of the polymer elements being measured using dynamic mechanical analysis (DMA) after every million cycles. This analysis demonstrated changes in stiffness and in the damping factor which guided the choice of elastomer for the B Dyn$^{(R)}$ implant.

• 한국정밀공학회지
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• 제27권1호
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• pp.91-98
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• 2010

The increasing of power and processing speed and miniaturization of central processor unit (CPU) used in electronics equipment requires better performing thermal management systems. A typical thermal management package consists of thermal interfaces, heat dissipaters, and external cooling systems. There have been a number of experimental techniques and procedures for estimating thermal conductivity of thin, compressible thermal interface material (TIM). The TIM performance is affected by many factors and thus TIM should be evaluated under specified application conditions. In compact packaging of electronic equipment the chip is interfaced with a thin heat spreader. As the package is made thinner, the coupling between heat flow through TIM and that in the heat spreader becomes stronger. Thus, a TIM characterization system for considering the heat spreader effect is proposed and demonstrated in detail in this paper. The TIM test apparatus developed based on ASTM D-5470 standard for thermal interface resistance measurement of high performance TIM, including the precise measurement of changes in in-situ materials thickness. Thermal impedances are measured and compared for different directions of heat dissipation. The measurement of the TIM under the practical conditions can thus be used as the thermal criteria for the TIM selection.

• 대한치과기공학회지
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• 제31권2호
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• pp.31-38
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• 2009

In recent year, the population for sports has been increased and lots of wounded patients at the oral & facial portion were troubled with the accidents. So, it was needed to protect them from the sports accident, by the use of the mouthguard appliance. This study was done as ae guide for selection of the mouthguard materials. Such mouthguards classified as E.V.A., PE, silicone as material, Scheu(Germany), Tru-Tain(U.S.A.), Dreve(Germany) as companies, 1.5mm, 3.0mm, and 4.0mm as thickness and single sheet, soft double sheet, hard double sheet methods were selected for experiment to compare the fracture protect test. The obtained results are as follows. 1. All types of mouthguards, whatever differences there are in material, production company, procedure and the thickness, were effective for fracture protect effect. 2. The most effective one for fracture protection was recommended as E.V.A. in material, and Tru-Tain in company. 3. More thick, and soft & hard multi sheets productions were more effective for fracture protection.