• Title/Summary/Keyword: Vacuum Characteristics

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Evaluation of Sliding Friction Properties of Laser Surface Texturing Dimple Pattern with DLC Coating under GaInSn Liquid Metal Lubricant (액체금속(GaInSn)윤활하에서 DLC(ta-C) 코팅된 레이저 표면 텍스쳐링 딤플패턴의 미끄럼 마찰특성평가)

  • Kwon, Gyubin;Jang, Youngjun;Chae, Younghun
    • Tribology and Lubricants
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    • v.37 no.3
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    • pp.106-111
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    • 2021
  • There are several studies on reducing the friction that occurs on the relative sliding contact surface of moving parts under extreme environments. In particular, a solid lubricated bearing is studied to solve the tribological problem with friction reduction and durability parts using solid lubricants (lead or silver) in a vacuum atmosphere. Galinstan is mainly used as a liquid metal lubricant, but it is inevitable to have limited tribological applications owing to its high coefficient of friction. Many researchers work on surface texturing for surface modification and precision processing methods. To increase durability and low friction, DLC coating with hydrophobicity is applied on the contact surface texture. Therefore, using an untextured specimen, a dimple specimen, and a DLC-coated dimple specimen under liquid metal lubrication, this paper presents the following experimental sliding friction characteristics in the sliding friction test. 1) The average coefficient of friction of the DLC-coated dimple specimen and dimple specimen are lower compared to that of a non-patterned specimen. 2) In the DLC-coated dimple specimens, the average coefficient of friction changes according to the change in the dimple density. 3) DLC-coated dimple specimens with a density of 12.5 have the lowest average coefficient of friction under 41.6 N of normal load and 143.3 RPM.

Microstructural Characteristics of Oxidation Resistant Cr-Si-Al alloys in Cast State and after High Temperature Heating (내산화성 Cr-Si-Al합금의 주조상태 및 고온가열 후의 미세조직 특성)

  • Kim, Jeong-Min;Kim, Chae-Young;Yang, Won-Chul;Park, Joon-Sik
    • Korean Journal of Materials Research
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    • v.31 no.3
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    • pp.156-161
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    • 2021
  • Cr-Si based alloys are not only excellent in corrosion resistance at high temperatures, but also have good wear resistance due to the formation of Cr3Si phase, therefore they are promising as metallic coating materials. Aluminum is often added to Cr-Si alloys to improve the oxidation resistance through which stable alumina surface film is formed. On the other hand, due to the addition of aluminum, various Al-containing phases may be formed and may negatively affect the heat resistance of the Cr-Si-Al alloys, so detailed investigation is required. In this study, two Cr-Si-Al alloys (high-Si & high-Al) were prepared in the form of cast ingots through a vacuum arc melting process and the microstructural changes after high temperature heating process were investigated. In the case of the cast high-Si alloy, a considerable amount of Cr3Si phase was formed, and its hardness was significantly higher than that of the cast high-Al alloy. Also, Al-rich phases (with the high Al/Cr ratio) were not found much compared to the high-Al alloy. Meanwhile, it was observed that the amount of the Al-rich phases reduced by the annealing heat treatment for both alloys. In the case of the high temperature heating at 1,400 ℃, no significant microstructural change was observed in the high Si alloy, but a little more coarse and segregated AlCr phases were found in the high Al alloy compared to the cast state.

Physical, chemical composition and umami compound of dried immature and mature roes of skipjack tuna (Katsuwonus pelamis)

  • Phetchthumrongchai, Thithi;Chuchird, Niti;Roytrakul, Sittiruk;Chintong, Sutasinee;Klaypradit, Wanwimol
    • Fisheries and Aquatic Sciences
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    • v.25 no.7
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    • pp.390-402
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    • 2022
  • In this study we investigate physical and chemical characteristics of immature and mature skipjack tuna (Katsuwonus pelamis) roes in fresh and dried forms. Fresh roes were studied for histological structure and also dried by three methods: hot air drying (HD), vacuum drying (VD) and freeze drying (FD). The obtained roe powders were analysed for proximate composition, color value, fatty acid composition, amino acid profile, equivalent umami concentration (EUC) and protein pattern. Unyolked oocytes were more common in immature roes, while fully yolked oocytes were more common in mature roes. All dried tuna roes contained high content of protein and lipid (69.31%-70.55% and 11.14%-16.02%, respectively). The powders obtained by FD provided the highest lightness value (L*). The main fatty acid found in all roe powders was docosahexaenoic acid (DHA) (23.49%-27.02%). Glutamic acid, leucine, and aspartic acid were the three most abundant amino acids found in the powders (13.58-14.61, 8.06-8.42, and 7.81-8.39 g/100 g of protein, respectively). The mature roe powder obtained from HD provided the highest EUC value (73.09 g monosodium glutamate/100 g of samples). The protein band at molecular weight of 97 kDa (vitelline) represented the major protein. Therefore, dried tuna roe could be a functional ingredient source of protein and lipid rich in DHA and it also has potential to be used as taste enhancer with umami compound.

Characteristics of Magnetic Sengon Wood Impregnated with Nano Fe3O4 and Furfuryl Alcohol

  • Gilang Dwi LAKSONO;Istie Sekartining RAHAYU;Lina KARLINASARI;Wayan DARMAWAN;Esti PRIHATINI
    • Journal of the Korean Wood Science and Technology
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    • v.51 no.1
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    • pp.1-13
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    • 2023
  • Sengon (Falcataria moluccana Miq.) tree offers a wood of low quality and durability owing to its low density and thin cell walls. This study aimed to improve the properties of sengon wood by making the wood magnetic, producing new functions, and characterizing magnetic sengon wood. Each wood sample was treated using one of the following impregnation solutions: Untreated, 7.5% nano magnetite-furfuryl alcohol (Fe3O4-FA), 10% nano Fe3O4-FA, and 12.5% nano Fe3O4-FA. The impregnation process began with vacuum treatment at 0.5 bar for 2 h, followed by applying a pressure of 1 bar for 2 h. The samples were then tested for dimensional stability and density and characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) analysis, and vibrating sample magnetometry (VSM) analysis. The results showed that the Fe3O4-FA impregnation treatment considerable affected the dimensional stability, measured in terms of weight percent gain, anti-swelling efficiency, water uptake, and bulking effect, as well as the density of sengon wood. Changes in wood morphology were detected by the presence of Fe deposits in the cell walls and cell cavities of the wood using SEM-EDX analysis. XRD and FTIR analyses showed the appearance of magnetite peaks in the diffractogram and Fe-O functional groups. Based on the VSM analysis, treated sengon wood is classified as a superparamagnetic material with soft magnetic properties. Overall, 10% Fe3O4-FA treatment led to the highest increase in dimensional stability and density of sengon wood.

In-situ Deposition Rate Measurement System to Improve the Accuracy of the Film Formation Process (성막 공정 정밀도 향상을 위한 실시간 성막 속도 측정 시스템)

  • Somi Park;Seung-Yo Baek;Hyun-Bin Kim;Jonghee Lee;Jae-Hyun Lee
    • Applied Chemistry for Engineering
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    • v.34 no.4
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    • pp.383-387
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    • 2023
  • The quartz crystal microbalance (QCM), commonly used in high vacuum deposition, becomes difficult to use when a thick film is deposited on the quartz, affecting the crystal's inherent vibration. In this study, a non-destructive optical measurement method was developed to measure the film's deposition rate during the in-situ film deposition process. By measuring the scattered laser intensity caused by the dimer in the parylene gas passing through the gas flow path, it was successfully confirmed that the ratio of the dimer in the parylene gas increases as the pyrolysis temperature decreases. Additionally, it was noted that the film's thickness and haze increase as the pyrolysis temperature decreases by confirming the characteristics of the visible parylene films. Through the research results, we aim to utilize the stable in-situ film deposition rate measurement system to control the precise film deposition rate of parylene films.

Characteristics of Tin Oxide Thin Film Grown by Atomic Layer Deposition and Spin Coating Process as Electron Transport Layer for Perovskite Solar Cells (원자층 증착법과 용액 공정법으로 성장한 전자 수송층 산화주석 박막의 페로브스카이트 태양전지 특성)

  • Ki Hyun Kim;Sung Jin Chung;Tae Youl Yang;Jong Chul Lim;Hyo Sik Chang
    • Korean Journal of Materials Research
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    • v.33 no.11
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    • pp.475-481
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    • 2023
  • Recently, the electron transport layer (ETL) has become one of the key components for high-performance perovskite solar cell (PSC). This study is motivated by the nonreproducible performance of ETL made of spin coated SnO2 applied to a PSC. We made a comparative study between tin oxide deposited by atomic layer deposition (ALD) or spin coating to be used as an ETL in N-I-P PSC. 15 nm-thick Tin oxide thin films were deposited by ALD using tetrakisdimethylanmiotin (TDMASn) and using reactant ozone at 120 ℃. PSC using ALD SnO2 as ETL showed a maximum efficiency of 18.97 %, and PSC using spin coated SnO2 showed a maximum efficiency of 18.46 %. This is because the short circuit current (Jsc) of PSC using the ALD SnO2 layer was 0.75 mA/cm2 higher than that of the spin coated SnO2. This result can be attributed to the fact that the electron transfer distance from the perovskite is constant due to the thickness uniformity of ALD SnO2. Therefore ALD SnO2 is a candidate as a ETL for use in PSC vacuum deposition.

Evaluation of citrus fiber as a natural alternative to sodium tripolyphosphate in marinated boneless broiler chicken breast and inside beef skirt (transversus abdominis)

  • Kendal R. Howard;Cheyenne L. Runyan;Allen B. Poe;Andrew M. Cassens;Lea A. Kinman
    • Animal Bioscience
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    • v.37 no.1
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    • pp.116-122
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    • 2024
  • Objective: This research was conducted to evaluate the effects of citrus fiber (CF) as a natural alternative to sodium tripolyphosphate (STPP) in marinated broiler boneless chicken breast and inside beef skirt on overall retention rate, shear force, and consumer sensory attributes. Methods: Five different marinade formulations were targeted to include 0.9% salt, either 0.25% or 0.50% STPP or CF and water on a finished product basis. Water and salt only were considered the negative control (CON). Chicken breasts (n = 14) and inside beef skirt (n = 14) were randomly assigned to a treatment, raw weights recorded and then placed in a vacuum tumbler. Marinated weights were recorded, individually packed, and randomly assigned to either retail display for 10-day retention rate, shear force analysis, cook loss, or consumer sensory panel. Results: Pickup percentage, and overall retention was similar among treatments for chicken breast and inside beef skirt. Citrus fiber treatments resulted in higher cooking loss compared to the CON in chicken breast; though, CF050 resulted in similar cooking loss compared to STPP025 in inside beef skirt. No differences were found in sensory attributes for chicken breast, however, WBSF data showed CF025 was tougher than CF050, STPP050, and CON. Inside beef skirt with CF050 were least liked overall by the consumer panel. Conclusion: Citrus fiber included in marinades at a lower percentage rate can produce similar texture characteristics, and sensory properties compared with those marinated with STPP.

Physical Properties of Cd2GeSe4 and Cd2GeSe4:Co2+ Thin Films Grown by Thermal Evaporation (진공증착법에 의해 제작된 Cd2GeSe4와 Cd2GeSe4:Co2+ 박막의 물리적 특성)

  • Lee, Jeoung-Ju;Sung, Byeong-Hoon;Lee, Jong-Duk;Park, Chang-Young;Kim, Kun-Ho
    • Journal of the Korean Vacuum Society
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    • v.18 no.6
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    • pp.459-467
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    • 2009
  • $Cd_2GeSe_4$ and $Cd_2GeSe_4:Co^{2+}$ films were prepared on indium-tin-oxide(ITO)-coated glass substrates by using thermal evaporation. The crystallization was achieved by annealing the as-deposited films in flowing nitrogen. X-ray diffraction spectra showed that the $Cd_2GeSe_4$ and the $Cd_2GeSe_4:Co^{2+}$ films were preferentially grown along the (113) orientation. The crystal structure was rhomohedral(hexagonal) with lattice constants of $a=7.405\;{\AA}$ and $c=36.240\;{\AA}$ for $Cd_2GeSe_4$ and $a=7.43\;{\AA}$ and $c=36.81\;{\AA}$ for $Cd_2GeSe_4:Co^{2+}$ films. From the scanning electron microscope images, the $Cd_2GeSe_4$ and $Cd_2GeSe_4:Co^{2+}$ films were plated, and the grain size increased with increasing annealing temperature. The optical energy band gap, measured at room temperature, of the as-deposited $Cd_2GeSe_4$ films was 1.70 eV and increased to about 1.74 eV and of the as-deposited $Cd_2GeSe_4:Co^{2+}$ films was 1.79 eV and decreased to about 1.74 eV upon annealing in flowing nitrogen at temperatures from $200^{\circ}C$ to $500^{\circ}C$. The dynamical behavior of the charge carriers in the $Cd_2GeSe_4$ and $Cd_2GeSe_4:Co^{2+}$ films were investigated by using the photoinduced discharge characteristics technique.

Microbiological and Sensory Characteristics of Vacuum Packed Korean Chilled Pork Loins for Export (한국산 수출용 진공포장 냉장 돈육 등심의 미생물학적 및 관능적 품질특성)

  • Choi, Y.S.;Park, B.Y.;Lee, J.M.;Kim, I.S.;Lee, S.K.;Kim, B.C.
    • Journal of Animal Science and Technology
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    • v.44 no.3
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    • pp.351-360
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    • 2002
  • The Korean fresh pork loins in vacuum packaged were obtained from three different Korean export companies and investigated for microbiological and sensory properties. The fresh pork loins were stored at 2$^{\circ}C$ for 50 days and analyzed with an interval of 5$\sim$10 days. The results were as follows: The overall numbers of total plate counts and coliform bacteria were higher in swab method than in meat sampling method. The total plate counts in the loins from the company I were maintained low levels ($\prec$10$^5$ cfu/$cm^2$ or $\prec$10$^5$ cfu/g) for entire storage periods(50 days at 2$^{\circ}C$), whereas the loins from the company III had high levels when they were compared to the domestic standard for the allowance limit. The samples from the company III showed that total plate counts were over 106 after about 30 days when determined by meat sampling method and total plate counts were over 106 after 15 days when determined by swab method. The overall numbers of coliform bacteria were also significantly lowest in the samples from the company I, whereas they were highest in the company III. Therefore, all meat companies will have to make an effort to prevent bacterial contamination in each stage such as slaughtering, marketing and consumer in order to ensure the production of safe meat and the extension of shelf-life. For fresh products, scores of intramuscular fat were higher in samples form the companies II and III than those from the company I when visibly evaluated with the standard. There were no significant differences in scores of meat color, drip and fresh meat flavor. However, the samples from the company I had the lowest score of off-flavor and highest score of overall acceptability. For cooked products, there were no significant differences in meat flavor, off-flavor, juiciness and overall acceptability.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 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.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. 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 fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (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 for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.