• Title/Summary/Keyword: 재료가격

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Magnetocaloric Effect of LaPbMnO3 Alloy (LaPbMnO3 합금의 자기열량효과)

  • Min, Seong-Gi;Kim, Kyeong-Sup;Yu, Seong-Cho;Moon, Young-Mo
    • Journal of the Korean Magnetics Society
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    • v.15 no.4
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    • pp.236-240
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    • 2005
  • The magnetocaloric effect and magnetization behaviors have been studied for $La_{1-x}Pb_{x}MnO_3$ (x=0.1, 0.2, 0.3) alloys. The Curie temperature increased from 195 K to 352 K with increasing Pb concentration. A large magnetic entropy change (${\Delta}S_M$), which is calculated from H vs M curves associated with the ferromagnetic-paramagnetic transitions, has been observed. The maximum ${\Delta}S_M$ of $La_{0.8}Pb_{0.2}MnO_3$ was 1.22 J/kg K at 294 K for an applied field of 1.5 T. Adiabatic temperature change (${\Delta}T_ad$) was measured directly by a special cryostat. The maximum ${\Delta}T_ad$ of $La_{0.7}Pb_{0.3}MnO_3$ was 1.00 K at 352 K for an applied field of 2 T.

The effect of crystallinity of hollow $TiO_2$ spheres on conversion efficiency of DSSC (Hollow $TiO_2$의 결정성이 염료감응형 태양전지의 광전 변환 효율에 미치는 영향)

  • Song, Minkyeong;Kim, Jeonghyun;Yu, Yeontae
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.50.2-50.2
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    • 2011
  • 염료감응형 태양전지는 기존의 실리콘 태양전지에 비해 저렴한 가격과 다양한 날씨 조건에서도 태양광과의 반응성이 안정하다는 여러 가지 장점을 갖고 있다. 하지만 광전 변환 효율이 기존의 실리콘 태양전지에 비해 현저히 떨어진다는 문제점과 장기적으로 안정하지 못하다는 단점을 가지고 있다. 이러한, 염료감응형 태양전지에서 크게 광전 변환 효율을 향상시킬 수 있는 재료는 염료, $TiO_2$와 같은 반도체 산화물전극 재료, 전해질이다. 이 중 $TiO_2$의 특성 및 크기는 염료감응형 태양전지의 효율에 영향을 미친다. 염료감응형 태양전지의 광전 변환 효율을 증가시키기 위해서 $TiO_2$는 넓은 비표면적, 높은 전자의 이동성 및 태양광과의 우수한 반응성을 가져야 한다. Microwave hydrothermal 방법에 의해 제조된 hollow $TiO_2$를 염료감응형 태양전지에 적용시킬 경우 기존의 $TiO_2$의 광흡수 반응이 200~400 nm 사이에서 발생하는 반면, hollow $TiO_2$의 광흡수 반응은 기존의 UV 영역인 200~400 nm 뿐만 아니라 가시광 영역인 400~460 nm 에서도 광흡수 반응이 가능하기 때문에 염료감응형 태양전지에서 광전 변환효율을 증가 시킬 수 있을 것으로 기대된다. 또한, microwave hydrothermal법에 의해 제조된 hollow $TiO_2$는 150-200 nm의 크기를 갖으며 20-30 nm 크기의 $TiO_2$ particle들로 이루어져 있다. hollow $TiO_2$ (150-200 nm)를 기존의 $TiO_2$ (10-20 nm) 층 위에 올려 염료감응형 태양전지의 electrode에 적용할 경우 기존의 $TiO_2$ 단층을 이용한 것보다 우수한 light-scattering 효과를 갖게 되어 광전 변환 효율 증가에 긍정적인 영향을 미칠 것이다. 본 연구에서는 hollow $TiO_2$의 광학적 특성 및 결정성이 염료감응형 태양전지에 미치는 영향을 조사하였다. hollow $TiO_2$의 광학적 특성 및 결정성의 변화를 위하여 microwave hydrothermal 법의 합성 온도 및 합성시간에 변화를 주었다. hollow $TiO_2$의 광학적 특성은 UV-visible spectrometer를 이용하여 조사하였으며, hollow $TiO_2$의 형상과 결정학적 특성은 TEM과 SEM 그리고 X선 회절 분석을 이용하여 관찰되었고, hollow $TiO_2$의 비표면적 측정은 BET 측정법을 이용하였다. 또한 염료감응형 태양전지 cell을 제작하여 $100mW/cm^2$(AM 1.5G) 기준에서 광전 변환 효율을 측정하였다.

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A Study on the Fabrication of the Solar Cells using the Recycled Silicon Wafers (Recycled Si Wafer를 이용한 태양전지의 제작과 특성 연구)

  • Choi, Song-Ho;Jeong, Kwang-Jin;Koo, Kyoung-Wan;Cho, Tong-Yul;Chun, Hui-Gon
    • Journal of Sensor Science and Technology
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    • v.9 no.1
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    • pp.70-75
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    • 2000
  • The recycled single crystal silicon wafers have been fabricated into solar cells. It can be a solution for the high cost in materials for solar cells and recycling of materials. So, p-type (100) single crystal silicon wafers with high resistivity of $10-14\;{\Omega}cm$ and the thickness of $650\;{\mu}m$ were used for the fabrication of solar cells. Optimistic conditions of formation of back surface field, surface texturing and anti-reflection coating were studied for getting high efficiency. In addition, thickness variation of solar cell was also studied for increase of efficiency. As a result, the solar cell with efficiency of 10% with a curve fill factor of 0.53 was fabricated with the wafers which have the area of $4\;cm^2$ and thickness of $300\;{\mu}m$. According to above results, recycling possibility of wasted wafers to single crystal silicon solar cells was confirmed.

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Research on the Architectural Applications of High-Performance Vacuum Insulation Panel (고성능 진공단열재의 건축적인 적용에 관한 연구)

  • Kwon, Young Cheol;Kim, Suk
    • Land and Housing Review
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    • v.10 no.3
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    • pp.23-32
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    • 2019
  • Vacuum Insulation Panel(VIP) has the lowest thermal conductivity among present insulations. It is composed of envelope, core material and getter. Aluminum film is usually used as the envelope of VIP, and it is important component to decide the useful life of VIP. In this research, the thermophysical properties of incombustible fiber glass core VIP were investigated with the possibility of its architectural applications. The results of this research can be summarized as follows: 1) The thermal conductivity of 20mm-thick fiber glass core VIP is resulted as 0.00177W/m·K, which means that 20mm-thick VIP can meet all the reinforced insulation guideline and it can be used in any envelope of any region in Korea. 2) As a result of the test of incombustion and gas toxicity, fiber glass core VIP was suitable for incombustible material. 3) As the test result for the long term thermal conductivity, fiber glass core VIP was found out that it would keep above 10 times insulating performance than polystyrene foam and glass fiber. 4) To meet the thermal transmittance of 0.12W/㎡K, limited-combustible insulation of expanded polystyrene foam and phenolic foam should be used respectively as thick as above 280mm and 170mm, incombustible VIP can meet the same insulation level with 20mm thickness. 5) The price competitiveness of incombustible VIP to meet the thermal transmittance of 0.12W/㎡·K was about 1,500won/㎡ higher than that of phenolic foam.

Numerical Analysis for Thermal-deformation Improvement in TSOP(Thin Small Outline Package) by Anti-deflection Adhesives (TSOP(Thin Small Outline Package) 열변형 개선을 위한 전산모사 분석)

  • Kim, Sang-Woo;Lee, Hai-Joong;Lee, Hyo-Soo
    • Journal of the Microelectronics and Packaging Society
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    • v.20 no.3
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    • pp.31-35
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    • 2013
  • TSOP(Thin Small Outline Package) is the IC package using lead frame, which is the type of low cost package for white electronics, auto mobile, desktop PC, and so on. Its performance is not excellent compared to BGA or flip-chip CSP, but it has been used mostly because of low price of TSOP package. However, it has been issued in TSOP package that thermal deflection of lead frame occurs frequently during molding process and Au wire between semiconductor die and pad is debonded. It has been required to solve this problem through substituting materials with low CTE and improving structure of lead frame. We focused on developing the lead frame structure having thermal stability, which was carried out by numerical analysis in this study. Thermal deflection of lead frame in TSOP package was simulated with positions of anti-deflection adhesives, which was ranging 198 um~366 um from semiconductor die. It was definitely understood that thermal deflection of TSOP package with anti-deflection adhesives was improved as 30.738 um in the case of inside(198 um), which was compared to that of the conventional TSOP package. This result is caused by that the anti-deflection adhesives is contributed to restrict thermal expansion of lead frame. Therefore, it is expected that the anti-deflection adhesives can be applied to lead frame packages and enhance their thermal deflection without any change of substitutive materials with low CTE.

Fabrication and characterization of Sn-3.0Ag-0.5Cu, Sn-0.7Cu and Sn-0.3Ag-0.5Cu alloys (Sn-3.0Ag-0.5Cu, Sn-0.7Cu 및 Sn-0.3Ag-0.5Cu 합금의 제조 및 특성평가)

  • Lee, Jung-Il;Paeng, Jong Min;Cho, Hyun Su;Yang, Su Min;Ryu, Jeong Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.28 no.3
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    • pp.130-134
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    • 2018
  • In the past few years, various solder compositions have been a representative material to electronic packages and surface mount technology industries as a replacement of Pb-base solder alloy. Therefore, extensive studies on process and/or reliability related with the low Ag composition have been reported because of recent rapid rise in Ag price. In this study, Sn-3.0Ag-0.5Cu, Sn-0.7Cu and Sn-0.3Ag-0.5Cu solder bar samples were fabricated by melting of Sn, Ag and Cu metal powders. Crystal structure and element concentration were analyzed by XRD, XRF, optical microscope, FE-SEM and EDS. The fabricated solder samples were composed of ${\beta}-Sn$, ${\varepsilon}-Ag_3Sn$ and ${\eta}-Cu_6Sn_5$ phases.

An Experimental Study for Substitutability of Sand Mat with Fiber Mat (Fiber Mat의 Sand Mat 대체가능성평가를 위한 실험적 연구)

  • Lee Song;Jeong Yong-Eun
    • Journal of the Korean Geotechnical Society
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    • v.21 no.5
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    • pp.225-230
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    • 2005
  • At present, there are several problems related with sand mat which is used as a way to accelerate consolidation settlement, to act like an underground drainage layer and to increase trafficability simultaneously. First of all, the unbalance of the demand and supply of sand is one of the biggest problems, which causes not only price rise but also delay of the term of the total construction work. Secondly, the damage of ecosystem and scenery is triggered by thoughtless sand dredging or mining. So, the need that sand mat should be replaced with a new environmentally friendly material has been increased. Fiber mat may be one of the proper materials that suits the need. Therefore, we intended to compare the drainage properties of sand mat with those of fiber mat by experimental model tests. On the basis of the test results, fiber mat took shorter period of consolidation than sand mat and the amount of settlement in the farmer showed a little bit bigger than in the latter. As a conclusion, the substitutability of sand mat with fiber mat could be placed highly in view of drainage efficiency. Furthermore, when fiber mat is used, it has an advantage that spoiled soil of the construction site or nearby site can be used for the purpose of increasing trafficability in addition to a role of drainage layer.

An Analysis of the Composite Discharge Capacity Effect with GCP Method (GCP공법의 복합통수능 효과 분석)

  • Park, Minchul;Kwon, Hyukchan;Shin, Hyohee;Jang, Gisoo;Lee, Song
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.12
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    • pp.37-46
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    • 2011
  • An application frequency of vertical drainage method is increasing as an effective consolidation acceleration method. PBD method is most frequently used as a consolidation acceleration method in vertical drainage methods. PBD is economical and easy to operate but has some problems those are an environmental pollution and a decrease of a discharge capacity caused by bending of drainage materials when it is used in great depth. SCP method was frequently used because it's discharge capacity was good but now it is rarely used because of an increase of the material price because of an order imbalance. As the way to solve these problems, GCP method has been to the fore. For analyzing the effect of GCP method on the discharge capacity, three types of composite discharge capacity tests are done by using GCP, SCP and PBD respectively with the circle case, ${\phi}38{\times}h70cm$. On the contrary to this, GCP shows the worst discharge capacity for a decrease of the void ratio and the clogging phenomenon caused by increasing load. Also to figure out the clogging range of GCP, the clogging of GCP is checked in each load stage with a large case($1.0m{\times}0.5m{\times}1.1m$) which has clear acrylic front face. The diameter of GCP was 35cm and a clogging phenomenon occurred in 10% approximately. The result shows that the discharge capacity of GCP was given the lowest value for a decrease of the void ratio and the clogging phenomenon causing by increasing load. And the clogging phenomenon mostly occurred within 10% of GCP's diameter range.

Impact Resistance Reliability of Sn-1.2Ag-0.5Cu-0.4In Solder Joints (Sn-1.2Ag-0.5Cu-0.4In 조성 솔더 접합부의 내 충격 신뢰성 평가)

  • Yu, A-Mi;Lee, Chang-Woo;Kim, Jeong-Han;Kim, Mok-Soon;Lee, Jong-Hyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.226-226
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    • 2008
  • 지난 10여년 동안 Sn-3.0Ag-0.5(wt%)Cu 합금은 대표 무연솔더 조성으로 다양한 전자제품의 실장 및 접합에 적용되어 왔으며, 그 신뢰성 역시 충분히 검증된 바 있다. 그러나 최근 Ag 가격의 급격한 상승과 솔더 접합부의 내 충격 신뢰성을 보다 향상시키고자 하는 업계의 동향은 Ag의 함량이 낮은 무연솔더 조성의 적용 확대를 유도하고 있다. 이에 따라 본 연구자들은 저 Ag 함유 무연슬더로 Sn-1.2Ag-0.5Cu-0.4In 조성을 제안한 바 있는데, 이는 Sn-3.0Ag-0.5Cu 조성 이상의 solderability를 가지면서도 그 금속원료 가격이 약 20% 가량 저렴한 특징을 가진다. 또한 열 싸이클링 (cycling) 테스트를 통한 슬더 조인트의 신뢰성을 평가한 결과, Sn-3.0Ag-0.5Cu에 크게 뒤떨어지지 않는 양호한 특성이 관찰되었다. 따라서 본 연구에서는 열 싸이클링 테스트와 더불어 최근 그 중요성이 지속적으로 커지고 있는 내 충격 신뢰성 평가 시험을 실시하여 개발된 4원계 무연솔더 조성의 기계적 특성을 기존 무연솔더 조성과 비교, 분석해 보았다. 각 솔더 조성은 솔더 볼 형태로 제조되어 CSP(Chip Scale Package) 상에 범핑 (bumping)되었으며, CSP를 PCB(Printed Circuit Board) 상에 실장하는 공정에서도 Sn-3.0Ag-0.5Cu 및 Sn-1.2Ag-0.5Cu-0.4In의 두 종류의 솔더 페이스트가 사용되었다. 본 연구에서의 내 충격 신뢰성 시험에는 자체 제작한 rod drop 시험기를 사용하였는데, 고정된 CSP 실장 board의 후면 부위를 일정한 높이에서 추를 반복적으로 자유 낙하시켜 급격한 충격을 주는 방식으로 실험을 실시하였다. 이 때 추의 무게는 30g, 낙하 높이는 10cm 였으며, 추의 낙하 시 측정된 board 의 휨 변위량은 약 0.7mm로 측정되었다. 사용된 CSP와 PCB 는 모두 daisy chain 방식으로 연결되어 있기 때문에 저항측정기를 사용한 간단한 실시간 저항 측정 방법으로 시험 이력에 따른 파단부의 발생 시점과 대략의 위치를 손쉽게 확인할 수 있었다. 솔더 조인트의 파단 기준 저항값으로 $1000\Omega$을 설정하였으며. 각 조건 당 5 개 이상의 샘플에 대해 평가를 실시한 후 그 평균값을 조사하였다. 시험 결과 제안된 Sn-1.2Ag-0.5Cu-0.4In 조성은 대표적인 저 Ag 함유 조성인 Sn-1.0Ag-0.5Cu에 비해서는 떨어지는 내 충격 신뢰성을 나타내었지만, 우수한 연성에 기인하여 Sn-3.0Ag-0.5Cu 조성에 비해서는 약 2 배 이상 우수한 신뢰성이 관찰되었다. 또한 CSP의 실장 시 Sn-3.0Ag-0.5Cu보다 Sn-1.2Ag-0.5Cu-0.4In 조성 솔더 페이스트를 적용한 경우에서 보다 우수한 내 충격 신뢰성을 나타내어 기본적으로 개발된 Sn-1.2Ag-0.5Cu-0.4In 솔더 페이스트가 Sn-3.0Ag-0.5Cu 조성의 기존 솔더 페이스트 보다 내 충격 신뢰성이 우수함을 검증할 수 있었다. 각 조성의 솔더 조인트를 $150^{\circ}C$ 에서 500시간 aging한 후 실시한 내 충격 신뢰성 평가에서는 모든 조성에서 그 신뢰성이 급감하는 경항을 나타내었으나, Sn-1.2Ag-0.5Cu-0.4In가 Sn-l.0Ag-0.5Cu보다도 그 상대적인 신뢰성이 우수한 것으로 관찰되었다. 이와 같이 aging 후 실시하는 충격시험은 가장 실제적인 상황과 유사한 조건이므로 상기의 실험 결과는 매우 고무적이었으며, 이에 대한 보다 면밀한 분석이 요청되었다. 마지막으로 파면 및 미세조직 관찰을 통하여 각 조성에서의 충격 파단 특성을 비교, 분석해 보았다.

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Study on 3D Printer Suitable for Character Merchandise Production Training (캐릭터 상품 제작 교육에 적합한 3D프린터 연구)

  • Kwon, Dong-Hyun
    • Cartoon and Animation Studies
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    • s.41
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    • pp.455-486
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    • 2015
  • The 3D printing technology, which started from the patent registration in 1986, was a technology that did not attract attention other than from some companies, due to the lack of awareness at the time. However, today, as expiring patents are appearing after the passage of 20 years, the price of 3D printers have decreased to the level of allowing purchase by individuals and the technology is attracting attention from industries, in addition to the general public, such as by naturally accepting 3D and to share 3D data, based on the generalization of online information exchange and improvement of computer performance. The production capability of 3D printers, which is based on digital data enabling digital transmission and revision and supplementation or production manufacturing not requiring molding, may provide a groundbreaking change to the process of manufacturing, and may attain the same effect in the character merchandise sector. Using a 3D printer is becoming a necessity in various figure merchandise productions which are in the forefront of the kidult culture that is recently gaining attention, and when predicting the demand by the industrial sites related to such character merchandise and when considering the more inexpensive price due to the expiration of patents and sharing of technology, expanding opportunities and sectors of employment and cultivating manpower that are able to engage in further creative work seems as a must, by introducing education courses cultivating manpower that can utilize 3D printers at the education field. However, there are limits in the information that can be obtained when seeking to introduce 3D printers in school education. Because the press or information media only mentions general information, such as the growth of the industrial size or prosperous future value of 3D printers, the research level of the academic world also remains at the level of organizing contents in an introductory level, such as by analyzing data on industrial size, analyzing the applicable scope in the industry, or introducing the printing technology. Such lack of information gives rise to problems at the education site. There would be no choice but to incur temporal and opportunity expenses, since the technology would only be able to be used after going through trials and errors, by first introducing the technology without examining the actual information, such as through comparing the strengths and weaknesses. In particular, if an expensive equipment introduced does not suit the features of school education, the loss costs would be significant. This research targeted general users without a technology-related basis, instead of specialists. By comparing the strengths and weaknesses and analyzing the problems and matters requiring notice upon use, pursuant to the representative technologies, instead of merely introducing the 3D printer technology as had been done previously, this research sought to explain the types of features that a 3D printer should have, in particular, when required in education relating to the development of figure merchandise as an optional cultural contents at cartoon-related departments, and sought to provide information that can be of practical help when seeking to provide education using 3D printers in the future. In the main body, the technologies were explained by making a classification based on a new perspective, such as the buttress method, types of materials, two-dimensional printing method, and three-dimensional printing method. The reason for selecting such different classification method was to easily allow mutual comparison of the practical problems upon use. In conclusion, the most suitable 3D printer was selected as the printer in the FDM method, which is comparatively cheap and requires low repair and maintenance cost and low materials expenses, although rather insufficient in the quality of outputs, and a recommendation was made, in addition, to select an entity that is supportive in providing technical support.