• 제목/요약/키워드: Density Test

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방사선 차폐용 고밀도 콘크리트 시공에 관한 연구 (A Study on the Construction of High Density Concrete for Radiation Shield)

  • 이제방;조용복;변형균;유건철;임병대
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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    • pp.399-404
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    • 1994
  • Heavyweight(or High density) concrete, which is generally for shiedling structures, differs from normal weight concrete by having a higher density and special compositions to improve its attenuation properties. There are setting 7 Beam Ports around the reactor of the KMRR Project(Korea Multi-purpose Research Reactor) conducted by the KAERI(Korea Atomic Energy Research Institute). High density(p=5.0t/$\textrm{m}^3$) and Heavyweight(p=3.5t/$\textrm{m}^3$) concrete were placed around the Beam Ports in order to shield radiation. This paper was discussed about construction of High density concrete. High density concrete was placed with method of Preplace Aggregate. Coarse metallic aggregate(steel shot) was used. Boron, boron carbide(B4C), was used to capture effctively the neutrom. The mock-up test was carried out. And the consturction of High density concrete was performed successfully.

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페놀 폼 단열재의 연기밀도 및 가스유해성 평가 (Evaluation of Smoke Density and Noxious Gas for Phenol Foam Insulation)

  • 박형주
    • 한국안전학회지
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    • 제25권1호
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    • pp.38-43
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    • 2010
  • The smoke density and noxious gas for phenol foam and polyurethane foam were measured according to test methods in ASTM E 662 and KS F 2271. It was observed that phenol foam had the possibility of application for sandwich panel and board compared with polyurethane foam. In the experimental results, phenol foam showed comparatively excellent property than polyurethane foam in smoke density and noxious gas. The polyurethane foam showed comparatively high smoke density and didn't meet the evaluation standard of noxious gas in KS F 2271. From the experimental results of smoke density and noxious gas, it can be said that phenol foam has both comparatively good safety and high possibility of application than polyurethane foam in the building fire of sandwich panel structure because of lower smoke density and noxious gas.

원전 시설용 콘크리트의 압축강도 및 건조밀도 특성 평가 (Evaluation for Mechanical Properties of Compress Strength and Dry Density of Concrete at NPP)

  • 이영대;김규용;신경수;남정수;이태규;최경철
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2011년도 추계 학술논문 발표대회
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    • pp.53-54
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    • 2011
  • The facilities producing the nuclear energy chosen for resolving the recent global energy problem have been increasingly constructed, and hence more frequent durability tests on radiation shielding concrete are required due to NPP(Nuclear Power Plant) life extension and increase of radioactive waste repositories. Bulk dry density is one of the critical factors ensuring the durability and performance of the radiation shielding concrete because the design of the radiation shielding reinforced concrete structures for NPPs is based on the bulk dry density of the concrete. Bulk density of unconsolidated shielding concrete can be calculated utilizing a test assuring to satisfy the bulk dry density, or existing credible data set. This study evaluated correlation between bulk density and bulk dry density of the concrete used for Korean NPPs (y=1.0913X-0.2458) and developed a correlation expression considering standard deviation of bulk dry density (y=1.0913X-0.3358).

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고집적 메모리에서 BLSFs(Bit-Line Sensitive Faults)를 위한 새로운 테스트 알고리즘 (A New Test Algorithm for Bit-Line Sensitive Faults in High-Density Memories)

  • 강동철;조상복
    • 전기전자학회논문지
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    • 제5권1호
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    • pp.43-51
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    • 2001
  • 메모리의 집적도가 올라갈수록 원치 않는 셀간의 간섭과 동시에 bit-line간의 상호 노이즈도 증가하게 된다. 그리고 높은 고장 검출율을 요구하는 고집적 메모리의 테스트는 많은 테스트 백터를 요구하게 되거나 비교적 큰 추가 테스트 회로를 요구하게 된다. 지금까지 기존의 테스트 알고리즘은 이웃 bit-line의 간섭이 아니라 이웃 셀에 중점을 두었다. 본 논문에서는 NPSFs(Neighborhood Pattern Sensitive Faults)를 기본으로 한 NBLSFs(Neighborhood Bit-Line Sensitive Faults)를 위한 새로운 테스터 알고리즘을 제안한다. 그리고 제안된 알고리즘은 부가 회로를 요구하지 않는다. 메모리 테스트를 위해 기존의 5개의 셀 레이아웃이나 9개의 셀 레이아웃을 사용하지 않고 NBLSF 검출에 최소한 크기인 3개의 셀 레이아웃을 이용하였다. 더구나 이웃 bit-line에 의한 최대의 상호잡음을 고려하기 위해 테스트 동작에 refresh 동작을 추가하였다(예 $write{\rightarrow}\;refresh{\rightarrow}\;read$). 또한 고착고장, 천이고장, 결합고장, 기존의 pattern sensitive 고장, 그리고 이웃 bit-line sensitive 고장 등도 검출될 수 있음을 보여준다.

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Bacillus 발효액 Enzamin의 투여가 인체의 NK세포 활성도와 Hamster의 골밀도에 미치는 탐색연구 (Research on the Bacillus-fermented Enzamin Administration on Human NK Cell Activity and Bone Density of Hamster: A Pilot Study)

  • 류서원;藤井登起男;이형환
    • 한국자연치유학회지
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    • 제7권2호
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    • pp.63-69
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    • 2018
  • 목적: 본 연구는 Bacillus 발효액(ENM)을 섭취한 사람의 NK세포활성도와 Hamster의 골밀도, 골량과 골면적에 미치는 영향을 연구하는 것이 목적이었다. 방법: NK세포 활성도 측정과 x-ray를 통한 골밀도 검사를 하였다. 결과: NK 세포의 활성도는 대조군은 644.71 pg/ml, 임상군이 1796.37 pg/ml로 높게 나타나 유의성이 있었다(p<.004). 그리고 임상군은 섭취 전 검사에서 1110.37 pg/ml, 사후검사에서는 1796.37 pg/ml로 유의성이 있게 증가하였다(p<.001). ENM 먹인 후의 햄스터들의 행동관찰에서는 대조군과 임상군 간의 행동은 차이가 없이 정상적으로 행동하였다. 체중의 변화는 대조군에서는 최초 및 최종 27일째에 측정한 체중은 106 g로 거의 변동이 없었으며, 임상군은 최초 측정이 96.6 g, 최종 27일째는 114 g로 증가하여 유의성이 있었다. 햄스터 뒷다리를 X-선 촬영한 사진에서는 형태적인 변화는 관찰되지 않았다. 대조군의 골밀도는 0.059 g/cm3, 임상군은 평균 골밀도는 0.062 g/cm3로 0.003 g/cm3만큼 증가하였다. 골중량은 대조군은 0.175 g, 임상군은 0.196 g로 증가하였다. 골면적은 대조군은 2.95 cm2, 임상군은 3.14 cm2 으로 0.19 cm2만큼 증가하였다. 부검에서 대조군과 임상군은 모두 특기할만한 이상은 없고, 각 장기도 정상이었다. 결론: ENM 섭취는 NK세포활성도와 Hamster의 골밀도를 증가시키는 유용한 식품이라 생각한다.

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Al2O3 첨가에 따른 송전용 현수애자의 전기적 성능 평가 연구 (A Study on the Electric Performance of Porcelain Insulator with Al2O3 Addition in Transmission Line)

  • 최인혁;최장현;이동일;최연규;조한구;한세원;박영창
    • 한국전기전자재료학회논문지
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    • 제18권1호
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    • pp.96-103
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    • 2005
  • To analyze the reason of aging deterioration in transmission line insulators, we performed a various kind of test and investigated mechanical and electrical characteristics of insulators. Test samples consisted of K-1989(36,000lbs), K-1995(36,000lbs) and K-2001(36,000lbs) type insulators which have been used in domestic 154 kV transmission lines. As a result of this test, the facts turned out K-2001 insulator which contain 17 wt.% alumina has better physical characteristics than K-1989 insulator which contain 8 wt% alumina. Relativity density and fracture toughness of K-1989 porcelain are 94.2 % and 1.4 MPa\ulcornerm$^{1}$2// but relativity density and fracture toughness of K-2001 porcelain are 96 % and 1.7 MPa\ulcornerm$^{1}$2//. K-2001 insulators show a good performance not only in a physical property test but also in power arc test and steep front of wave flashover test which is performed to evaluate electrical characteristics.

시설노인의 골다공증 관련요인 연구 (A Study of Related Factors in the Bone Mineral Density of the Institutionalized Elderly)

  • 김희자
    • 지역사회간호학회지
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    • 제8권1호
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    • pp.31-44
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    • 1997
  • The purpose of this study was to measure and determine the relationship of femoral neck and lumbar bone mineral density with their and related factors. It were measured and determined the relationships among bone mineral density, bone mineral content in the lumbar and femoral neck, muscle strength (arm, back, leg), muscle endurance, instrumental activity of daily living (IADL), quality of life, cognitive perceptual variables(self efficacy, perceived health status), age, age at menopausal period. The twenty five subjects participating in this study consisted of twelve males and thirteen females at a C-institution in Chung Buk province. The mean age of subjects was 73.64 years. The data was collected from August, 1993 to September, 1993. The data was analyzed with $x^2-test$, t-test, Correlation, multiple regression using a SPSS pc+ program. 1. The mean femoral neck bone mineral density was $0.636g/cm^2$, 66.7% of young bone mineral density, the mean lumbar($L_2-L_4$) bone mineral density was $0.807g/cm^2$, 79.86% of young bone mineral density. The mean fermoral neck bone mineral content was 2.906g and the mean lumbar bone mineral content was 36.898g. 2. The mean muscle strength was 17.14kg(grip strength), 32.05kg(back lift strength), 17.14kg (leg lift strength) and the mean muscle endurance was 9.92times. 3. Men showed a significantly higher score (p<0.01) in muscle strength and muscle endurance than women, as well as a significantly higher score on self efficacy and perceived health status(p<0.05). 4. The femur neck bone mineral density had a significant correlation(p<0.0l) with leg lift strength, back lift strength, and their was a significant correlations (p<0.05) with arm strength and muscle endurance. Lumbar ($L_2-L_2$) bone mineral density had a significant correlation(p<0.05) with muscle endurance, grip strength and IADL. 5. With the multiple regression analysis the most significant predictor for lumbar bone mineral density were IADL, the most significant predictor for femoral neck bone mineral density was leg strength. This study concluded: As the mean bone mineral density and bone mineral content were low, the aged showed osteopenia. Bone mineral density, muscle strength and IADL were correlated. The aged could pro mote muscle strength, bone mineral density and IADL through Leg Press exercise which was safe and efficient for the aged. This Leg Press exercise contributed to prevention of osteoporosis and promoted the health of the aged.

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Effects of Tungsten Particle Size and Nickel Addition in DC arc Resistance of Cu-W Electrode

  • Kim, Bong-Seo;Jeong, Hyun-Uk;Lee, Hee-Woong
    • KIEE International Transactions on Electrophysics and Applications
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    • 제4C권2호
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    • pp.68-72
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    • 2004
  • The performance of copper-tungsten for electrodes used in an ultra high voltage interruption system was evaluated by means of an interruption test, which requires a large-scale apparatus and high cost. In this study, prior to the interruption test, the characteristics of a Cu-W electrode were estimated through the DC arc test, which is a simple, low cost procedure. The DC arc characteristics of a 20wt%Cu-80wt%W electrode were investigated with the change of tungsten powder size distribution and the addition of nickel. In specimens containing a high volume fraction of large sized tungsten particles, the relative density and hardness of sintered Cu-W electrodes increased while the electrical conductivity and the DC arc resistance decreased. Furthermore, the relative density became enhanced with the increase of the amount of nickel while the hardness and electrical conductivity diminished and the DC arc resistance worsened.

유도무기의 신뢰성 향상을 위한 비행환경 모사시험 방안 연구 (Flight Environment Simulation Test for Reliability Improvement of Precise Guided Missile)

  • 최승혁
    • 한국정밀공학회지
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    • 제33권10호
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    • pp.781-787
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    • 2016
  • We introduce FEST (Flight Environment Simulation Test) procedures for precise guided missiles to reliably improve systems. Flight vibration specification was established based on power spectral density curves calculated from flight test data of a high speed precise guided missile. A FEST pre-profile was developed according to flight vibration specification and delivered to a precise guided missile assembly. Vibration responses were measured by installing accelerometers on electronic components vulnerable to dynamic forces. The FEST profile was adjusted by comparing the vibration responses and the flight vibration specification. Subsequently, the FEST profile was repeatedly modified through trial and error, because the responses were similar to the flight environment. The modified FEST profile enabled performance testing of assembled precise guided missiles under simulated flight conditions on the ground, where unexpected errors could be corrected before the flight tests, leading to cost and risk reduction in the development of the precise guided missile system.

종속 오차에 대한 분포 변화 검정법 (Test for Distribution Change of Dependent Errors)

  • 나성룡
    • Communications for Statistical Applications and Methods
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    • 제16권4호
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    • pp.587-594
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    • 2009
  • 이 논문에서는 선형회귀모형의 오차항에 대한 변화점 검정 문제를 다룬다. 고정 혹은 변동 모형의 독립 변수와 약한 종속성을 가지는 오차항을 가정하는 관계로 통상적인 중회귀모형뿐만 아니라 ARMA 등의 시계열 모형까지 본 논문에서 포괄한다고 하겠다. 오차항의 분포 변화를 검정하기 위하여 회귀모형의 잔차에 기초한 확률밀도함수 추정값을 이용한다. 적절한 가정하에서 잔차를 이용한 검정이 실제 오차를 이용한 경우와 동일한 극한 분포를 가짐을 보였다.