• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.272-274
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• 2002

The contribution of light in high-energy film dosimetry was examined using six commercially available solid water substitute phantoms. As six commercially available phantoms; RMI-451, Mix-DP, WE211, WE211-Black, PMMA and PMMA Black were evaluated in this study. It is difficult to evaluate the contribution of Cerenkov radiation and the optical permeability to the relative and/or absolute dosimetry using unpacked film in these phantoms. Therefore the contribution of Cerenkov radiation was estimated by the comparison between film densities in the shielded side (shutting off the light) and unshielded sides on a phantom. The effect of optical permeability was measured under ambient light by the time scale method. The results suggest that the use of black colored phantoms may improve the accuracy of dose measurement in film dosimetry.

• 한국농공학회논문집
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• 제46권7호
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• pp.47-53
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• 2004

Permeable polymer concrete can be applied to roads, sidewalks, river embankments, drain pipes, conduits, retaining walls, yards, parking lots, plazas, interlocking blocks, etc. This study was to explore a possibility of using blast furnace slag powder and stone dust of industrial by-products as fillers for Eco-permeable polymer concrete. Different mix proportions were tried to find an optimum mix proportion of the Eco­permeable polymer concrete. The tests were carried out at $20{\pm}1^{circ}C$ and $60{\pm}2\%$ relative humidity. At 7 days of curing, unit weight, coefficient of permeability, dynamic modulus of elasticity, compressive, flexural and splitting tensile strengths ranged between $1,821{\~}1,955 kg/m^{3}$, $0.056{\~}0.081\;cm/s$, $114{\times}0^{2}{\~}157{\times}10^{2}\;MPa,\;17.6{\~}24.7\;MPa,\;5.98{\~}7.94\;MPa\;and\;3.43{\~}4.70\;MPa$, respectively. It was concluded that the blast furnace slag powder and stone dust can be used in the Eco-permeable polymer concrete.

• 대한전기학회논문지
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• 제37권10호
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• pp.694-701
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• 1988

분포형 레일건은 전기자가 이동하는 공안 전기자전류를 거의 일정하게 유지할수 있으며 전류공급영성과 전기자 사이의 거리를 최소로 유지할수 있게 한다. 이 논문은 분포형 레일건에서 전류분포실효저항 및 전류의 실효확산 깊이에 영향을 미치는 인자를 규명한 것이다. 정상상태의 간단한 2차원 모델로 부터 레일의 전류분포와 실효저항을 나타내는 식을 유도하였다. 전류의 확산이 불충분한 조건에서 레일의 실효저항은 레일의 상대속도, 투자솔, 전기자와 전류공급영성과의 거리의 1/2승에 비례하고 도전솔의 1/2승에 반비례하였으며, 전류의 실효확산 깊이는 전기자와 전류공급영성과의 거리의 1/2승에 비례하고 투자솔, 도전솔 및 속도의 1/2승에 반비례하였다.

• 전기학회논문지
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• 제60권3호
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• pp.552-559
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• 2011

There is a method for offering continuous information by AF track circuits. Magnetic fields are formed by current through rails in the AF track circuit systems. So, the continuous information is received by the magnetic fields on a on-board antenna. Coating materials of spray on rails are researched to decrease defects such as head check, shelling, corrugation, squats and so on in Germany. Currently, a coating method of rail construction is proposed by using the ceramics in Korea. When deciding physical characteristic of the coating material of spray, researches are required about variation of flux density and resistivity by using the coating material of spray. In case that the flux density is much lower than existing value, the information for train control is not transmitted to the on-board antenna. In this paper, inductance on rails is calculated and a model is presented about variation of the magnetic field intensity and resistivity in the AF track circuit. Standard permeability of the coating material of spray is proposed. Also, standard resistivity of the coating material of spray is presented by analyzing short current.

• 한국도로학회논문집
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• 제16권1호
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• pp.31-39
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• 2014

PURPOSES : Surface treatment material for pavement preventive maintenance should be inspected field applicability. This study(Part II) aimed to checkup coating characteristics and performance analysis using lab and field tests. The hydrophobic - low viscosity filling material for pavement preventive maintenance is presented in Part I, which is a series of companion study. METHODS : Relative comparison between general asphalt mixtures and surface treatment asphalt mixtures are analyzed and measured for the field application such as indirect tensile strength ratio(TSR), abrasion resistance, crack propagation resistance, temperature resistance, coating thickness, permeability resistance and skid resistance in terms of british pendulum number(BPN). RESULTS : It is found that TSR, crack propagation resistance and permeability resistance is increased as against uncoated asphalt specimen. Abrasion resistance and temperature resistance is secured from the initial coating thickness point of view, which is about 0.2~0.3mm. Skid resistance on the surface treatment pavement is satisfied with the BPN criteria of national highway because of exposed aggregate and crack sill induced pavement deterioration and damage cracks. CONCLUSIONS : The hydrophobic - low viscosity surface treatment material for pavement preventive maintenance is validated on field applicability evaluation based on quantitative analysis of coating thickness and performance analysis using lab and field tests.

• 한국자기학회지
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• 제5권6호
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• pp.947-951
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• 1995

페라이트는 높은 자기적 손실을 이용하여 전자파 흡수체로 사용하고 있다. 전자파 흡수체는 미세조직이 균일하고 미세할수록 흡수특성이 향상된다. 유기산염 열분해법으로 합성한 분말을 사용하여 Cu-Ni-Zn 페라이트를 제조하였다. 복소유전율과 복소투자율은 밀도가 높고, 입자의 크기가 미세할수록 상승하였다. 페라이트의 정합두께는 소결온도가 높을수록 얇아졌다. Cu-Ni-Zn 페라이트의 전자파 흡수능은 정합두께가 6.75 mm 일 때 160 MHz 부터 640 MHz 까지의 주파수에서 20dB 이상의 값이엿다.

• 보존과학회지
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• 제36권4호
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• pp.255-263
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• 2020

Paulownia coreana has various advantages as a convenient workability, aesthetic outlook, beautiful patterns, low weight and high strength, and its permeability. P. coreana has been widely used for storage but there are no empirical researches proving its functionality in a field of conservation science until now. In this study, the seasonal and daily temperature and relative humidity control, and microbe and insect repellent activity were evaluated under the controlled and uncontrolled circumstances from 2015 to 2016. The results showed to be mainly excellent in relative humidity control and the buffering effect was good to adjust the average daily relative humidity range from the outside. With respect to the antimicrobial properties of P. coreana, we observed that its water-soluble extract produced visible zones of inhibition against five bacteria. However, it was difficult to predict the antimicrobial and/or insecticidal properties.

• 한국농공학회논문집
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• 제47권7호
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• pp.25-33
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• 2005

This study was performed to develop environment-friendly porous polymer concrete utilizing recycled aggregates [RPPC] for permeable pavement of uniform quality with high permeability and flexural strength as well as excellent freezing and thawing resistance. The void ratios of RPPC are in the range of 15$\sim$$24\%$, showing the tendency that it is reduced to a great extent as the mixing ratio of the binder increases. The compressive and flexural strength of RPPC are in the range of 19$\sim$26 MPa and 6.2$\sim$7.4 MPa, respectively. Also, it shows a tendency to increase as the mixing ratio of the binder and filler increases. The permeability coefficients of RPPC are in the range of $6.3\times$$10_{-1}$$\sim$$1.5\times$$10_{-2}$cm/s. The flexural loads of RPPC are in the range of 18$\sim$32 KN. The weight reduction ratios obtained from the test for freezing and thawing resistance are in the range of 1.1$\sim$$2.4\%$ after 300 cycles of repeated freezing and thawing of the specimen for all mixes. The relative compressive strengths of RPPC after 300 cycles of freezing and thawing against the compressive strength before freezing and thawing test are in the range of 89$\sim$$96\%$.

• 한국도로학회논문집
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• 제20권3호
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• pp.47-57
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• 2018

PURPOSES : The permeable pavement type has been rapidly developed for solving problems regarding traffic noise in the area of housing complex and heavy rainwater drainage in order to account for the climate change. In this regards, the objective of this study is to figure out the characteristics of pavement types. METHODS : The laboratory test for deriving optimum asphalt content (OAC) was conducted using the mixtures of the permeable asphalt surface for the pavement surface from Marshall compaction method. Based on its results, the pavement construction at the test field was conducted. After that, the site performance tests for measuring the traffic noise, strength and permeability were carried out for the relative evaluation in 2 months after the traffic opening. The specific site tests are noble close proximity method (NCPX), Light falling deflectometer test (LFWD) and the compact permeability test. RESULTS : The ordered highest values of the traffic noise level can be found such as normal dense graded asphalt, drainage and porous structure types. In the results from LFWD, the strength values of the porous and drainage asphalt types had been lower, but the strength of normal asphalt structure had relatively stayed high. CONCLUSIONS :The porous structure has been shown to perform significantly better in permeability and noise reduction than others. In addition to this study, the evaluation of the properties and the determination of the optimum thickness for the subgrade course under the porous pavement will be conducted using ground investigation technique in the further research.

• Journal of the Korean Wood Science and Technology
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• 제46권6호
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• pp.637-644
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• 2018

The air permeability of yellow poplar log cross section before and after organosolv pretreatment was investigated, and the moisture absorption of control and organosolv pretreated rectangular parallelepiped specimens was investigated in this study. It was revealed that the diameters of through pores were enlarged and the number of bigger pore was increased by the organosolv pretreatment. The air permeabilities of the cross sections of yellow poplar log were changed from 1.61 darcy to 23.30 darcy, but their weights were reduced by 5 percent. The equilibrium moisture content of control wood specimen at the exposed relative humidity were 5.9 % at 32 %, 9.7 % at 58 %, 14.8 % at 80.5 %, 19.7 % at 90 %, 25.7 % at 95 % and 29.9 % at 100%. The equilibrium moisture content of the specimens pretreated with the parameter of sulfuric acid catalyst of 0.5 % (w/w) were 19.5 % at 32 %, 29.3 % at 58 %, 39.6 % at 80.5 %, 59 % at 90 %, 111.3 % at 95 % and 111.3 % at 100 %, while those pretreated with the parameter of sulfuric acid catalyst of 1.0 % (w/w) were 17.4 % at 32 %, 23.9 % at 58 %, 27.7 % at 80.5 %, 40.6 % at 90 %, 68.8 % at 95 % and 110.0 % at 100 %. The moisture absorption of organosolv pretreated rectangular parallelepiped specimens was higher than that of control specimen.