• Title/Summary/Keyword: Sealing surface

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Effect of Coating Methods on the Properties of Poly(lactide)-coated Paperboard: Solution Coating vs. Thermo-compression Coating

  • Rhim, Jong-Whan
    • Food Science and Biotechnology
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    • v.18 no.5
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    • pp.1155-1160
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    • 2009
  • Poly(lactide) (PLA)-coated paperboards were prepared by solution coating and thermo-compression coating methods and their effect of coating on the packaging properties such as tensile, water resistance, water vapor barrier, and heat sealing properties was tested. Compared with uncoated control paperboard, tensile strength (TS) of PLA-coated paperboard increased profoundly (2.2-2.6 folds) with slight increase in elongation at break (E). Water absorptiveness (WA) of the paperboard decreased 74-170 folds and water vapor permeability (WVP) decreased 6.3-22.1 folds by coating with PLA, which indicates an increase in the hydrophobicity of the surface of paperboard. Compared with polyethylene (PE)-coated paperboard, both PLA-coated paperboard exhibited 2.3 time higher heat sealing strength. In addition, the PLA-coated paperboards showed equal or higher wet TS than PE-coated paperboard. All the test results showed that the paperboard coated by the thermo-compression coating method was similar to or better than those of coated by the solution coating method.

Evaluation of ultrasonic reflection characteristics on an interface surface using Simulated Annealing (Simulated Annealing기법을 이용한 초음파의 계면 반사 특성평가)

  • 은길수;김노유;나환선
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.395-400
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    • 2002
  • Epoxy coating and sealing used in nuclear plants for the protection of radiation degrades with aging and hazardous atmosphere. In order to evaluate the degradation of the epoxy, dependence of the acoustic impedance on the change of mechanical properties has been used. Unlike metals, the surface of the epoxy coating on a concrete liner is so wavy that the acoustic impedance is difficult to measure by using the reflectivity of the ultrasound on the interface surface because of the irregular reflection and propagation from the epoxy surface. SA(simulated annealing) algorithm is applied to calculate the acoustic impedance using a reflection wave from the rough epoxy surface. The surface waviness and acoustic impedance are taken into account and determined by SA method to evaluate the state of degradation quantitatively.

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The study on the quality characteristics factor of medium-sized orbit scroll (중형 선회 스크롤의 품질 특성 인자에 대한 연구)

  • Kim, Jae-Gi;Lim, Jeng-Taek;Kang, Soon-Kook;Park, Jong-Soon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.9
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    • pp.718-723
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    • 2016
  • The use of the scroll compressor in the air conditioning of medium-sized vehicles has increased because of its low torque fluctuation, high energy efficiency and low noise. In addition, the main components of the compressor have been changed from steel to aluminum to reduce its weight, following studies on the constituent materials. The processing precision of the fixed scroll and orbiting involute scroll wrap of the scroll compressor must be below $10{\mu}m$. To ensure this, the surface roughness and contour tolerance are measured. To improve the hardness of the orbiting scrolls using aluminum subjected to anodizing treatment and as the base material, we used a sealing treatment and measured the resulting characteristics. The aluminum materials were made of an Al-Mg-Cu based alloy including small amounts of Ni, Fe, and Zn. The surface roughness was less than $3{\mu}m$ and the processing accuracy was within $10{\mu}m$. Also, the hardness of the nanodiamonds with CNTs used in the sealing treatment was more than 450. This was found to improve the hardness of the material by 50% or more compared to the water sealing treatment and there was little difference between the use of carbon nanotubes and nanodiamonds as sealing materials.

Study of Characteristics of Hot Dip Galvanized Steel Strip by Oxygen-free Finishing (비산화성 분위기에 의한 용융아연도금의 특성 연구)

  • 진영구;김흥윤
    • Journal of the Korean institute of surface engineering
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    • v.28 no.5
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    • pp.300-308
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    • 1995
  • The effect of nitrogen finishing for the control of coating weight in a nitrogen sealing box on the coating surface property in hot dip galvanizing process has been studied. The coated surface is free of oxide marks and edge overcoated. The coating uniformity is excellent ; the standard deviation of the coating thickness along width of the specimen was $1~1.2\mu\textrm{m}$ in the box whereas $2.5~3\mu\textrm{m}$ in the air. Considering surface quality of the coating such as oxide mark, edge overcoated and zinc dust, the oxygen content between 40 and 200 ppm was suggested in the box in addition the oxygen content of at least 40 ppm or the minimum dew point of $-27^{\circ}C$ is required to prevent a zinc vaporization.

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Development of Wear-Resistant Sliding Parts Material

  • Shioiri, Hironori;Uemoto, Keiichi;Motooka, Naoki
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.116-117
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    • 2006
  • Conventional high-speed steels, which are carbide decentralized materials, are used for sliding parts, but they lack sufficient hardness for some applications. Improvement of surface hardness is possible for high-Cr steels through nitriding. However, nitriding P/M parts is not advisable without sealing the porosity before treatment, as they will become brittle. However, it is difficult to seal the pores with steam treatment, because high-Cr steel has a passive film on the surface. Controlling nitriding by decreasing the amount of oxygen on the surface to be nitrided, and grinding to decrease the porosity of the surface, makes it possible to produce a material that has reasonable and sufficient hardness in the required areas.

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Infiltration Experiments According to the Variation of Soil Condition of Infiltration Collector Well (침투정 토양 조건에 따른 침투 실험)

  • Rim, Chang-Soo
    • Journal of Korea Water Resources Association
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    • v.40 no.3
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    • pp.215-221
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    • 2007
  • The main purpose of this study is to find the appropriate method to prevent the reduction of infiltration capacity due to sealing of soil surface. The study results indicate that installation of gravel or larger soil facilitates the drainage of infiltrated rainwater. However, considering that the infiltration capacity has been reduced since the installation, it seems that the sealing of soil surface is caused by the inflow of suspended soil into the lower sand layer. To promote the infiltration capacity by reducing the pounding of lower natural soil layer, the sand soil should be placed above the natural soil layer with shallow depth just below the larger gravel. Furthermore, the crust generated above the soil surface should be removed regularly and the sand layer above the natural soil layer should be replaced with new one so that the original infiltration capacity can be maintained properly.

Vacuum Packaging of MEMS (Microelectromechanical System) Devices using LTCC (Low Temperature Co-fired Ceramic) Technology (LTCC 기술을 이용한 MEMS 소자 진공 패키징)

  • 전종인;최혜정;김광성;이영범;김무영;임채임;황건탁;문제도;최원재
    • Journal of the Microelectronics and Packaging Society
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    • v.10 no.1
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    • pp.31-38
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    • 2003
  • In the current electronic technology atmosphere, MEMS (Microelectromechanical System) technology is regarded as one of promising device manufacturing technologies to realize market-demanding device properties. In the packaging of MEMS devices, the packaged structure must maintain hermeticity to protect the devices from a hostile atmosphere during their operations. For such MEMS device vacuum packaging, we introduce the LTCC (Low temperature Cofired Ceramic) packaging technology, in which embedded passive components such as resistors, capacitors and inductors can be realized inside the package. The technology has also the advantages of the shortened length of inner and surface traces, reduced signal delay time due to the multilayer structure and cost reduction by more simplified packaging processes owing to the realization of embedded passives which in turn enhances the electrical performance and increases the reliability of the packages. In this paper, the leakage rate of the LTCC package having several interfaces was measured and the possibility of LTCC technology application to MEMS devices vacuum packaging was investigated and it was verified that improved hermetic sealing can be achieved for various model structures having different types of interfaces (leak rate: stacked via; $4.1{\pm}1.11{\times}10^{-12}$/ Torrl/sec, LTCC/AgPd/solder/Cu-tube; $3.4{\pm}0.33{\times}10^{-12}$/ Torrl/sec). In real application of the LTCC technology, the technology can be successfully applied to the vacuum packaging of the Infrared Sensor Array and the images of light-up lamp through the sensor way in LTCC package structure was presented.

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Sliding Wear Properties of Graphite as Sealing Materials for Cut off Hot Gas (고온차단 기밀용 그라파이트의 고온 미끄럼마모 특성 평가)

  • Kim, YeonWook;Kim, JaeHoon;Yang, HoYeong;Park, SungHan;Lee, HwanKyu;Kim, BumKeun;Lee, SeungBum;Kwak, JaeSu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.11
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    • pp.1349-1354
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    • 2013
  • Sealing structure to prevent flowing hot gas into the driving device, located between the driving shaft and the liner of On-Off valve for controlling the hot gas flow path was studied. Wear occurs due to the constant movement of the driving shaft controlled by actuator on graphite as the sealing material. In this paper, the dynamic wear behavior in high temperature of graphite(HK-6) to be used as sealing material was evaluated. Reciprocating wear test was carried out for the graphite(HK-6) to the relative motion between shaft materials(W-25Re). The results of friction coefficient and specific wear rate according to contact load, sliding speed at room temperature and $485^{\circ}C$ considering the actual operating environment were evaluated. Through the SEM analysis of the worn surface, third body as lubricant films were observed and lubricant effect of third body was considered.

A Study on the Elastic Restoration Characteristics According to Environmental Resistance Condition of Structural Sealing Finishing Materials (구조용 실링마감재의 내환경 조건에 따른 탄성복원 특성 연구)

  • Jang, Pil-Sung;Kang, Dong-Won;Hong, Soon-Gu;Kim, Young-Geun;Kim, Sung-Rae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.1
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    • pp.6-12
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    • 2018
  • Recently, The use of the curtain wall method is increasing in construction. The curtain wall construction is widely applied to the exterior wall of the building for shortening construction period and economical efficiency. However, the replacement of deterioration of the weather resistance and structural behavior of the sealing material connecting the curtain wall method and the glass frame is necessary for introduction of the stable curtain wall method and quality improvement in accordance with KS F 4910 standard. In this study, the elastic restoring force test was performed in the external environment. In this study, the deterioration of the sealant was evaluated for structural sealants. In Korea, studies on the variable displacement behavior of structural sealants are lacked. In this study, the reproduced results in laboratory conditions are compared with the deteriorating conditions exposed to the external environment, and they are reflected in the design of sealing materials in the future. According to the results of the study, it was confirmed that the existing structure sealant meets the quality standard of KS F 4910, but in the conditions performed in this study, adhesion failure of the specimen and cracking of the surface occurred. Especially, in the weather resistance test, it is necessary to evaluate the long-term durability performance of the structural sealant used in the curtain wall method by checking the insoluble state of all the test pieces. Therefore, in order to apply a conventional structural sealant to the site, it is necessary to introduce another durability performance evaluation.

Microgrooves on titanium surface affect peri-implant cell adhesion and soft tissue sealing; an in vitro and in vivo study

  • Lee, Hyo-Jung;Lee, Jaden;Lee, Jung-Tae;Hong, Ji-Soo;Lim, Bum-Soon;Park, Hee-Jung;Kim, Young-Kwang;Kim, Tae-Il
    • Journal of Periodontal and Implant Science
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    • v.45 no.3
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    • pp.120-126
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    • 2015
  • Purpose: With the significance of stable adhesion of alveolar bone and peri-implant soft tissue on the surface of titanium for successful dental implantation procedure, the purpose of this study was to apply microgrooves on the titanium surface and investigate their effects on peri-implant cells and tissues. Methods: Three types of commercially pure titanium discs were prepared; machined-surface discs (A), sandblasted, large-grit, acid-etched (SLA)-treated discs (B), SLA and microgroove-formed discs (C). After surface topography of the discs was examined by confocal laser scanning electron microscopy, water contact angle and surface energy were measured. Human gingival fibroblasts (hGFs) and murine osteoblastic cells (MC3T3-E1) were seeded onto the titanium discs for immunofluorescence assay of adhesion proteins. Commercially pure titanium implants with microgrooves on the coronal microthreads design were inserted into the edentulous mandible of beagle dogs. After 2 weeks and 6 weeks of implant insertion, the animal subjects were euthanized to confirm peri-implant tissue healing pattern in histologic specimens. Results: Group C presented the lowest water contact angle ($62.89{\pm}5.66{\theta}$), highest surface energy ($45{\pm}1.2mN/m$), and highest surface roughness ($Ra=22.351{\pm}2.766{\mu}m$). The expression of adhesion molecules of hGFs and MC3T30E1 cells was prominent in group C. Titanium implants with microgrooves on the coronal portion showed firm adhesion to peri-implant soft tissue. Conclusions: Microgrooves on the titanium surface promoted the adhesion of gingival fibroblasts and osteoblastic cells, as well as favorable peri-implant soft tissue sealing.