• Title/Summary/Keyword: multi-material design

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Surface Resistance of Antistatic Agent Using Lithium-Fluoro Compound and Quaternary Ammonium Salt and Characteristics Evaluation of Antistatic Film (리튬 불소계 화합물과 4차 암모늄염을 사용한 대전방지제의 표면저항 및 대전방지필름의 특성 평가)

  • Soh, Soon-Young;Chun, Yong-Jin;Lee, Jae-Kyeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.4
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    • pp.575-581
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    • 2020
  • A colorless antistatic agent was prepared for use in antistatic films for liquid crystal displays (LCDs) requiring low surface resistance and high transmittance. Among various lithium-fluoro compounds and quaternary ammonium salts, antistatic materials were selected based on their electrical conductivity, and antistatic agents were prepared to measure the surface resistance. As a result, the material with high conductivity showed a relatively low surface resistance, i.e., relatively good antistatic performance. Based on the antistatic materials selected, the formulation ratio for producing the best antistatic agent was established through the experimental design method and the effects of each factor were analyzed. The higher the use of lithium- fluoro compounds as antistatic materials, the higher the ratio of oligomer use with multi-functional groups, and the smaller the surface resistance. The quaternary ammonium salts increased the antistatic performance of the lithium-fluoro compounds, but the effects of the amount used were not relatively large. After manufacturing the antistatic PET film, the properties of the antistatic film showed low surface resistance values (<109 Ω/sq.), high permeability (>92%), low haze (<0.5%), and high whiteness (L>95). In addition, the antistatic film reliability was found to be excellent by showing a stable surface-resistance change rate of less than 10%, even under high temperature and high humidity conditions.

Study of Organic-inorganic Hybrid Dielectric for the use of Redistribution Layers in Fan-out Wafer Level Packaging (팬 아웃 웨이퍼 레벨 패키징 재배선 적용을 위한 유무기 하이브리드 유전체 연구)

  • Song, Changmin;Kim, Sarah Eunkyung
    • Journal of the Microelectronics and Packaging Society
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    • v.25 no.4
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    • pp.53-58
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    • 2018
  • Since the scaling-down of IC devices has been reached to their physical limitations, several innovative packaging technologies such as 3D packaging, embedded packaging, and fan-out wafer level packaging (FOWLP) are actively studied. In this study the fabrication of organic-inorganic dielectric material was evaluated for the use of multi-structured redistribution layers (RDL) in FOWLP. Compared to current organic dielectrics such as PI or PBO an organic-inorganic hybrid dielectric called polysilsesquioxane (PSSQ) can improve mechanical, thermal, and electrical stabilities. polysilsesquioxane has also an excellent advantage of simultaneous curing and patterning through UV exposure. The polysilsesquioxane samples were fabricated by spin-coating on 6-inch Si wafer followed by pre-baking and UV exposure. With the 10 minutes of UV exposure polysilsesquioxane was fully cured and showed $2{\mu}m$ line-pattern formation. And the dielectric constant of cured polysilsesquioxane dielectrics was ranged from 2.0 to 2.4. It has been demonstrated that polysilsesquioxane dielectric can be patterned and cured by UV exposure alone without a high temperature curing process.

A Study on the Implementation of Coexistent Reality Technology for Ship Outfitting Inspection (선박 의장 검사를 위한 공존현실 기술 적용에 관한 연구)

  • Ha, Yeon-Chul;Kim, Jin-Woo;Kim, Goo;Shin, Hyun-Shil
    • Journal of the Institute of Convergence Signal Processing
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    • v.21 no.1
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    • pp.13-20
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    • 2020
  • In shipyards, internal materials are assembled after designing and manufacturing each ship's block. Internal material assembly means the installation of parts and equipment except ship's body. In this process, if the assembly of pipes and equipment existing in the block is not done correctly during the assembly between blocks, this causes a lot of costs. In addition, even if the assembly of the internal materials already completed, the production efficiency of the ship is reduced due to rework when problems such as space arrangement of the internal materials occurs. Therefore, this study introduces space arrangement and inspection system before and after hull outfitting work based on coexistence reality technology using 3D design drawing to solve these problems. The various coexistence reality algorithms and inspection systems developed and introduced in this study are based on AR service, which has never been introduced in Korea. So it will be widely applicable to various manufacturing industries using design drawings such as automobiles and architectures as well as ship building process.

A review on the design requirement of temperature in high-level nuclear waste disposal system: based on bentonite buffer (고준위폐기물처분시스템 설계 제한온도 설정에 관한 기술현황 분석: 벤토나이트 완충재를 중심으로)

  • Kim, Jin-Seop;Cho, Won-Jin;Park, Seunghun;Kim, Geon-Young;Baik, Min-Hoon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.5
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    • pp.587-609
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    • 2019
  • Short-and long-term stabilities of bentonite, favored material as buffer in geological repositories for high-level waste were reviewed in this paper in addition to alternative design concepts of buffer to mitigate the thermal load from decay heat of SF (Spent Fuel) and further increase the disposal efficiency. It is generally reported that the irreversible changes in structure, hydraulic behavior, and swelling capacity are produced due to temperature increase and vapor flow between $150{\sim}250^{\circ}C$. Provided that the maximum temperature of bentonite is less than $150^{\circ}C$, however, the effects of temperature on the material, structural, and mineralogical stability seems to be minor. The maximum temperature in disposal system will constrain and determine the amount of waste to be disposed per unit area and be regarded as an important design parameter influencing the availability of disposal site. Thus, it is necessary to identify the effects of high temperature on the performance of buffer and allow for the thermal constraint greater than $100^{\circ}C$. In addition, the development of high-performance EBS (Engineered Barrier System) such as composite bentonite buffer mixed with graphite or silica and multi-layered buffer (i.e., highly thermal-conductive layer or insulating layer) should be taken into account to enhance the disposal efficiency in parallel with the development of multilayer repository. This will contribute to increase of reliability and securing the acceptance of the people with regard to a high-level waste disposal.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

Development of Manual Multi-Leaf Collimator for Proton Therapy in National Cancer Center (국립암센터의 양성자 치료를 위한 수동형 다엽 콜리메이터 개발)

  • Lee, Nuri;Kim, Tae Yoon;Kang, Dong Yun;Choi, Jae Hyock;Jeong, Jong Hwi;Shin, Dongho;Lim, Young Kyung;Park, Jeonghoon;Kim, Tae Hyun;Lee, Se Byeong
    • Progress in Medical Physics
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    • v.26 no.4
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    • pp.250-257
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    • 2015
  • Multi-leaf collimator (MLC) systems are frequently used to deliver photon-based radiation, and allow conformal shaping of treatment beams. Many proton beam centers currently make use of aperture and snout systems, which involve use of a snout to shape and focus the proton beam, a brass aperture to modify field shape, and an acrylic compensator to modulate depth. However, it needs a lot of time and cost of preparing treatment, therefore, we developed the manual MLC for solving this problem. This study was carried out with the intent of designing an MLC system as an alternative to an aperture block system. Radio-activation and dose due to primary proton beam leakage and the presence of secondary neutrons were taken into account during these iterations. Analytical calculations were used to study the effects of leaf material on activation. We have fabricated tray model for adoption with a wobbling snout ($30{\times}40cm^2$) system which used uniform scanning beam. We designed the manual MLC and tray and can reduce the cost and time for treatment. After leakage test of new tray, we upgrade the tray with brass and made the safety tool. First, we have tested the radio-activation with usually brass and new brass for new manual MLC. It shows similar behavior and decay trend. In addition, we have measured the leakage test of a gantry with new tray and MLC tray, while we exposed the high energy with full modulation process on film dosimetry. The radiation leakage is less than 1%. From these results, we have developed the design of the tray and upgrade for safety. Through the radio-activation behavior, we figure out the proton beam leakage level of safety, where there detects the secondary particle, including neutron. After developing new design of the tray, it will be able to reduce the time and cost of proton treatment. Finally, we have applied in clinic test with original brass aperture and manual MLC and calculated the gamma index, 99.74% between them.

The Arch Type PV System Performance Evaluation of Multi Controlled Inverter for Improve the Efficiency (효율개선을 위한 다중제어 인버터방식의 아치형 PV System 성능 분석)

  • Lee, Mi-Yong;Park, Jeong-Min
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.11
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    • pp.5452-5457
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    • 2012
  • It is saving material cost and construction cost by replacing conventional building materials, and It has advantages for aesthetic value. In the Europe, the United States, Japan and other country research about BIPV is actively being carried out and marketability is also being infinity expanding. Arch type PV systems efficiency characteristics is different depending on PV array's directly connection, parallel connection and arches angle, but is a lack of analysis on this nowadays. When the arch type PV system design up, they consider about aesthetic value and they didn't consider about generation efficiency. In this paper, we try to improve the efficiency through optimization of arch type PV system and estimation of the efficiency parameters of the arch type PV system, such as latitude, longitude, temperature, insolation, arch angle and each kind loss from system organization. For improving Arched PV system efficiency, proposed multiple control inverter system, and using simulation tool of Arched PV system "Solar pro", flat-plate type and many arch type PV system configuration the driving characteristics were compared and analyzed.

Numerical Study of Warpage and Stress for the Ultra Thin Package (수치해석에 의한 초박형 패키지의 휨 현상 및 응력 특성에 관한 연구)

  • Song, Cha-Gyu;Choa, Sung-Hoon
    • Journal of the Microelectronics and Packaging Society
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    • v.17 no.4
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    • pp.49-60
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    • 2010
  • Semiconductor packages are increasingly moving toward miniaturization, lighter and high performance. Futhermore, packages become thinner. Thin packages will generate serious reliability problems such as warpage, crack and other failures. Reliability problems are mainly caused by the CTE mismatch of various package materials. Therefore, proper selection of the package materials and geometrical optimization is very important for controlling the warpage and the stress of the package. In this study, we investigated the characteristics of the warpage and the stress of several packages currently used in mobile devices such as CABGA, fcSCP, SCSP, and MCP. Warpage and stress distribution are analyzed by the finite element simulation. Key material properties which affect the warpage of package are investigated such as the elastic moduli, CTEs of EMC molding and the substrate. Geometrical effects are also investigated including the thickness or size of EMC molding, silicon die and substrate. The simulation results indicate that the most influential factors on warpage are EMC molding thickness, CTE of EMC, elastic modulus of the substrate. Simulation results show that warpage is the largest for SCSP. In order to reduce the warpage, DOE optimization is performed, and the optimization results show that warpage of SCSP becomes $10{\mu}m$.

Correlation between Mix Proportion and Mechanical Characteristics of Steel Fiber Reinforced Concrete (강섬유 보강 콘크리트의 배합비와 역학적 특성 사이의 관계 추정)

  • Choi, Hyun-Ki;Bae, Baek-Il;Koo, Hae-Shik
    • Journal of the Korea Concrete Institute
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    • v.27 no.4
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    • pp.331-341
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    • 2015
  • The main purpose of this study is reducing the cost and effort for characterization of tensile strength of fiber reinforced concrete, in order to use in structural design. For this purpose, in this study, test for fiber reinforced concrete was carried out. Because fiber reinforced concrete is consisted of diverse material, it is hard to define the correlation between mix proportions and strength. Therefore, compressive strength test and tensile strength test were carried out for the range of smaller than 100 MPa of compressive strength and 0.25~1% of steel fiber volume fraction. as a results of test, two types of tensile strength were highly affected by compressive strength of concrete. However, increase rate of tensile strength was decreased with increase of compressive strength. Increase rate of tensile strength was decreased with increase of fiber volume fraction. Database was constructed using previous research data. Because estimation equations for tensile strength of fiber reinforced concrete should be multiple variable function, linear regression is hard to apply. Therefore, in this study, we decided to use the ANN(Artificial Neural Network). ANN was constructed using multiple layer perceptron architecture. Sigmoid function was used as transfer function and back propagation training method was used. As a results of prediction using artificial neural network, predicted values of test data and previous research which was randomly selected were well agreed with each other. And the main effective parameters are water-cement ratio and fiber volume fraction.

Joining High-Strength Steel and Al6061 Sheet Using Hole Clinching Process (Hole 클린칭을 이용한 고장력강판과 Al6061 이종소재의 접합)

  • Ahn, Nam-Sik;Lee, Chan-Joo;Lee, Jung-Min;Ko, Dae-Cheol;Lee, Seon-Bong;Kim, Byung-Min
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.6
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    • pp.691-698
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    • 2012
  • The joining of aluminum and HSS (high-strength steel) by the conventional clinching process is limited by the low formability of HSS. Defects in the clinching joint, such as necking of the upper sheet, cracks, and lack of interlocking, are produced by the different ductility properties of HSS and aluminum. In this study, we propose the hole clinching process for joining Al6061 and SPFC440, in which deformation of SPFC440 is avoided by drilling a hole in the SPFC440. The dimensions of the interlocking in the hole-clinched joint necessary to provide the required joint strength were determined. Based on the volume constant of the hole clinching process, the shapes of the tools were designed by finite element (FE)-analysis. A hole clinching experiment was performed to verify the proposed process. A cross-section of the joint showed good agreement with the results of the FE-analysis. The lap shear strength was found to be 2.56 kN, which is higher than required joint strength.