• Title/Summary/Keyword: 재질 시험

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Strength Properties of Old Korean Larch Pile (고(古)부재 잎갈나무 말뚝의 재질 특성)

  • Hwang, Kweonhwan;Park, Byung-Su
    • Journal of the Korean Wood Science and Technology
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    • v.35 no.6
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    • pp.23-30
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    • 2007
  • Round piles of Korean larch were excavated from the foundation of ex-Chosunchongdokbu (ex-Chosun Governer-General Building), which was constructed in 1916 and dismantled later in 1996. By the record (Huh, 1996), the Korean larch logs were logged from the Yalu river area near Mt. Baekdu in North Korea. At present, however, Korean larch is not so popular in South Korea. The latewood ratio profiles and strength properties (longitudinal compression, shear, longitudinal tensile, and bending) were obtained. The ratio of latewood from pith to bark increased up to 25 years, and then it showed constant tendency at 40% with some variances. From the microscopic observation, however, the latewood ratio decreased from the heartwood to the sapwood. Compression strength was greater and bending strength was a little lower than the previous reports (references 13~15), which might be attributed to the strength reduction of old structural members by aging or damage in the compression specimens than the bending ones. The flat-grained specimens for the shear and tension test showed higher coefficient of variation (COV) than the edge-grained ones. For the better comparison of results, in case of shear and tensile strength tests, the strength values of the edge-grained specimens were thought to be adopted rather than those of flat-grained ones.

The Corrosion Behavior of Cold-Rolled 304 Stainless Steel In Salt Spray Environments (염분분사환경에서 냉연 304 스테인레스강의 부식거동)

  • Chiang, M.F.;Young, M.C.;Huang, J.Y.
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.9 no.2
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    • pp.93-98
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    • 2011
  • Saline corrosion is one of the major degradation mechanisms for stainless steel type 304 (SS304) dry storage cask during the spent fuel interim storage period. Slow strain rate test (SSRT) and neutral salt spray test (NSS) were performed at $85^{\circ}C$ and $200^{\circ}C$ with 0.5 wt% sodium chloride mist sprayed on the cold-rolled SS304 specimens of different degrees of reduction in this study. The weight changes of the NSS specimens tested at $85^{\circ}C$ for 2000 hours differed greatly from those at $200^{\circ}C$. The weight loss of NSS specimens was not significant at $85^{\circ}C$ but the weight gain decreased gradually with increasing the cold-rolled reduction. The yield strength (YS) and ultimate tensile stress (UTS) values obtained from the SSRT tests for lightly cold-rolled specimens in the salt spray environment at $85^{\circ}C$ and $200^{\circ}C$ are slightly lower than in air. But for those with 20% reductions, the specimen strengths were no longer changed by the saline corrosion. The preliminary results demonstrated that the quality and performance of cold-rolled SS304 is acceptable for fabrication of dry storage casks. However, more work on the corrosion behavior of cold-rolled stainless steel in the saline atmosphere is needed to better understand its long-term performance.

Specimens and method for evaluating the moisturizing ability of lip makeup products (립메이크업 제품의 보습능 평가용 시편과 측정법)

  • Sung, Jee Eun;Jung, Jung Hui;Ryu, Hee-Wook
    • Journal of the Korean Applied Science and Technology
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    • v.34 no.4
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    • pp.727-736
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    • 2017
  • In this study, the method of evaluation of moisturizing ability of cosmetics using specimens was studied as an alternative method of clinical tests. Cosmetic spreadability, surface drying, and moisture loss rate of four specimens (Japanese cake (Maru mochi), Garaetteok, wheat flour, and agar) were evaluated. Also, the water loss rate of the specimens and the transepidermal waterloss were analyzed for 10 kinds of lip make-up products (5 kinds of lipstick, 3 kinds of lip balm, 2 kinds of lip gloss). The moisture loss rate (moisture evaporation sensitivity) of the agar specimen was highest in the order of agar> Garaetteok> Japanese cake> wheat flour. Agar specimens are the most suitable in terms of spreadability, surface crack, and raw material supply. Containers for the preparation of agar specimens are suitable for plastic materials with low heat transfer, which can produce convex, smooth surface specimens. In the evaluation of moisturizing ability of lip makeup products, there was a strong correlation between the water loss rate and the transepidermal waterloss rate measured with agar specimens. These results show that the proposed method can be used as one of the useful alternative test methods.

Aerodynamic Heating Analysis and Flight Test of KSR-III Rocket (KSR-III 공력가열 해석 및 비행시험)

  • Kim, Seong-Lyong;Lee, Jun-Ho;Kim, In-Sun;Cho, Kwang-Rae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.8
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    • pp.54-63
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    • 2004
  • The inner surface temperatures of the KSR-III Sounding Rocket launched at 29th November 2002 were measured in the flight test, and the aerodynamic heating rate and outer surface temperature were calculated. The used program is the MINIVER code, which calculate the boundary layer equation based on the theoretical analysis, and its calculation is simulated on the flight time histories. The analysis considered the inner surface heat transfer with one dimensional solid heat conduction. The results showed that the major interior heat transfer is the radiation heat transfer, and the maximum outer surface temperature due to aerodynamic heating reached to $223^{\circ}C$ at fin and the maximum heating rate is about $133kW/m^2$ at nose cap. The whole analysis proved that the surface temperature remained below the allowable temperature, and the KSR-III thermal design satisfies the thermal environmental conditions.

Design, manufacturing and performance test of restorated airplane of Buhwal (부활호 복원 설계, 제작 및 성능 연구)

  • Park, Chanwoo;Kim, Byungsoo;Cho, Taehwan;Cho, Hwankee;Ok, Ju Seon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.7
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    • pp.552-560
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    • 2013
  • Airplane Buhwal is the first light airplane which is designed and made in South Korea. Restoration of airplane Buhwal is designed based on the one made by Korean Airforce in 2004 but there are some changes also. It uses aluminum main wing, electronic indicator, BRS(Ballistic recovery parachute) and black box for improved performance. In this paper, for the restorated Buhwal, major design changes are introduced, structure, aerodynamic and stability analysis are reviewed and improved performances which is proven through flight test are shown. This study will be a big help for domestic light airplane development.

Changes in Material Properties of Used Gas Turbine Blade Made of Single- Crystal Superalloy (가스터빈 단결정 블레이드 사용품의 특성변화)

  • Yoo, Keun-Bong;Lee, Han-Sang;Song, Gyu-So;Lee, Kyu-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.12
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    • pp.1909-1915
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    • 2010
  • The material properties of gas turbine components change during the daily start/stop thermal cycle because of exposure to the hot combustion gas. Recently, single-crystal Ni-based superalloys have been used to manufacture many hot-gas components for gas turbines. However, the user needs to depend on the manufacturer for maintenance issues because of the lack of data required for predicting blade life and material degradation. In this study, we investigate the time-dependent degradation of first-stage blades at various operating facilities to collect the basic data for life assessment and damage analysis. The blade material is a single-crystal Ni-based superalloy, CMSX-4, and the EOH (equivalent operating hours) are 25,000 and 52,000, respectively. We prepared the test specimen directly from used blades and carried out mechanical tests and microstructural observations.

Human Body Vibration Analysis under Consideration of Seat Dynamic Characteristics (시트 동특성을 고려한 인체 진동 해석)

  • Kang, Juseok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.12
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    • pp.5689-5695
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    • 2012
  • In this study, vibration properties of seat and human body are analyzed through test and numerical analysis methods by taking into account the viscoelastic characteristics of polyurethane foam as seat material which is applied for vehicle. These viscoelastic characteristics which show nonlinear and quasi-static behavior are obtained by compression test. In addition, the viscous elastic property of polyurethane foam is modelled mathematically by using convolution integral and nonlinear stiffness model. In order to analyze the performance on ride comfort of seat, vertical vibration model is established by using dynamic model of seat and vertical vibration model of human body at ISO5982, and so the related motion equations are derived. A numerical analysis simulation is applied by using the nonlinear motion equation with Runge-Kutta integral method. The dynamic responses of seat and human body on the input of vibration acceleration measured at the floor of the railway vehicle are examined. The variation of the index value at ride comfort on seat design parameters is analyzed and the methodology on seat design is suggested.

A Verification Study on the Demand Performance of Fabric Duct for Localization Development of Naval Vessel (해군 수상함 국산화개발 천 덕트의 요구성능 검증연구)

  • Jung, Young In;Choi, Sang Min;Jung, Hyun Sub;Sim, Min Sub
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.8
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    • pp.468-474
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    • 2020
  • Metal ducts for transporting air conditioning and heating inside ships have recently been replaced by cloth ducts that have the advantage of delivering air evenly to the compartments, with excellent noise reduction in major compartments, such as combat command rooms, steering rooms, and sound detector cabins. Since the performance requirements of fabric ducts for vessels are strict, and the entire length of the ducts was imported from Korea, the government wants to create economic effects through localization of fabric ducts. Air permeability and fire prevention performance tests verified the applicability to naval vessels of fabric ducts developed by Hyundai Heavy Industries and HiDact, and performance requirements presented in the POS were verified. As a result of the tests, the fabric ducts met the requirements for air permeability and fireproof performance.

Numerical Analysis of Sunroof Buffeting using STAR-CCM+ (STAR-CCM+를 이용한 썬루프 버페팅 유동 소음 해석)

  • Bonthu, Satish Kumar;Mendonca, Fred;Kim, Ghuiyeon;Back, Young-R.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.3
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    • pp.213-218
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    • 2014
  • CFD flow simulation of vehicles with open sunroof and passenger window help the automotive OEM(original equipment manufacturer) to identify the low frequency noise levels in the cabin. The lock-in and lock-off phenomena observed in the experimental studies of sunroof buffeting is well predicted by CFD speed sweep calculations over the operating speed range of the vehicle. The trend of the shear layer oscillation frequency with vehicle speed is also well predicted. The peak SPL from the CFD calculation has a good compromise with the experimental value after incorporating the real world effects into the CFD model by means of artificial compressibility and damping correction. The entire process right from modeling to flow analysis as well as acoustic analysis has been performed within the single environment i.e., STAR-CCM+.

Protector Design and Shock Analysis for a Launch-Reconnaissance Robot (발사형 정찰로봇을 위한 보호체 설계 및 충격해석)

  • Kang, Bong-Soo;Park, Moon-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.8
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    • pp.971-976
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    • 2011
  • This paper presents the design concepts of a protector for a launch-reconnaissance robot that is to be deployed for data-collection in hazardous regions. The protector protects the reconnaissance robot inside from shock induced during the process of launch, flight, and landing. Since the outer shells of the protector are automatically opened wide by the unlocking mechanism during the landing stage, the reconnaissance robot can easily exit the protector and move around to carry out its mission. We carefully simulated a finite-element model of the protector with the robot and compared the results with the actual dynamic behavior of the system. Shock- response tests using a droptable showed that the proposed protector filled with silicon material successfully attenuated external shock.