• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 봄 학술발표회 발표논문집
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• pp.155-160
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• 2003

Indoor air quality can be affected by indoor sources, ventilation, decay and outdoor levels. Although technologies exist to measure these factors, direct measurements are often difficult. The purpose of this study was to develop an alternative method to characterize indoor environmental factors by multiple indoor and outdoor measurements. Daily indoor and outdoor $NO_2$ concentrations were measured for 30 consecutive days in 28 houses in Brisbane, Australia, and for 21 consecutive days in 37 houses in Seoul, Korea. Using a mass balance model and regression analysis, penetration factor (ventilation rate divided by the sum of ventilation rate and deposition constant) and source strength factor (source strength divided by the sum of ventilation rate and deposition constant) were calculated using multiple indoor and outdoor measurements. Subsequently, the ventilation rate and $NO_2$ source strength were estimated. Geometric means of ventilation rate were 1.44 ACH in Brisbane, assuming a residential $NO_2$ deposition constant of 1.05 $hr^{-1}$, and 1.36 ACH in Seoul, with the measured residential $NO_2$ deposition constant of 0.94 $hr^{-1}$. Source strengths of $NO_2$ were 15.8 $\pm$ 18.2 ${\mu}g$/$m^3$.hr and 44.7 $\pm$ 38.1${\mu}g$/$m^3$.hr in Brisbane and Seoul, respectively. In conclusion, indoor environmental factors were effectively characterized by this method using multiple indoor and outdoor measurements.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2004년도 International Conference Current Challenges and Advances in Environmental Health
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• pp.45-50
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• 2004

Indoor air quality can be affected by indoor sources, ventilation, decay and outdoor levels. Alt hough technologies exist to measure these factors, direct measurements are often difficult. The purpose of this study was to develop an alternative method to characterize indoor environmental factors by multiple indoor and outdoor measurements. Daily indoor and outdoor NO2 concentrations were measured for 30 consecutive days in 28 houses in Brisbane, Australia, and for 21 consecutive days in 37 houses in Seoul, Korea. Using a mass balance model and regression analysis, penetration factor (ventilation rate divided by the sum of ventilation rate and deposition constant) and source strength factor (source strength divided by the sum of ventilation rate and deposition constant) were calculated using multiple indoor and outdoor measurements. Subsequently, the ventilation rate and NO2 source strength were estimated. Geometric means of ventilation rate were 1.44 ACH in Brisbane, assuming a residential NO2 deposition constant of 1.05 hr-1, and 1.36 ACH in Seoul, with the measured residential NO2 deposition constant of 0.94 hr-1. Source strengths of N02 were 15.8 ${\pm}$ 18.2 ${\mu}$g/m3${\cdot}$hr and 44.7 ${\pm}$ 38.1 ${\mu}$g/m3${\cdot}$hr in Brisbane and Seoul, respectively. In conclusion, indoor environmental factors were effectively characterized by this method using multiple indoor and outdoor measurements.

• 한국세라믹학회지
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• 제45권7호
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• pp.430-437
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• 2008

Porous self-bonded silicon carbide (SBSC) ceramics were fabricated at temperatures ranging from 1700 to $1850^{\circ}C$ using SiC, silicon (Si), and three different carbon (C) sources, including carbon black, phenol resin, and xylene. The effects of the Si:C ratio and carbon source on porosity and strength were investigated as a function of sintering temperature. Porous SBSC ceramics fabricated from phenol resin showed higher porosity than the others. In contrast, porous SBSC ceramics fabricated from carbon black showed better strength than the others. Regardless of the carbon source, the porosity increased with decreasing the Si:C ratio whereas the strength increased with increasing the Si:C ratio.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.85-89
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• 2001

The problem of the transient interaction of a plane acoustic shock wave which has an infinitely steep wave front with a cylindrical or spherical elastic shell has been studied analytically from early fifties based on the integral transform and series solution techniques. Huang adopted an inverse Laplace transform, and used a finite number of terms of the infinite series expansion of the equations for the shells. In the 1990s, the results have been used by many authors for validation of computer codes. The object of this paper is to discuss the interaction between a moving source and submerged spherical shells. Since the center of source is moving the first contact location between the waves and shell changes depending on the source velocity and distance. These are considered in the analysis. Furthermore, constant source strength and decreasing strength are considered in the analysis. Radial velocities at several locations on the structure are obtained and the results are discussed.

• 대한방사선기술학회지:방사선기술과학
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• 제30권2호
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• pp.147-151
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• 2007

AAPM TG43 프로토콜에서 선원 강도의 측정은 공기커마강도로 권고하고 있다. 본 연구는 제조사에서 제공되는 공기커마강도의 정확성이 ${\pm}5%$ 범위 이내에 있는지 측정으로 검증하는데 목적이 있다. Standard imaging사의 MAX-4001 Electrometer와 HDR 1000 Plus, 그리고 6 french bronchial Applicator를 재료로 사용하여, 이온함의 중심축의 바닥으로부터 10 mm 지점에서 90 mm 지점까지 이온화 전류를 측정하였다. 측정된 이온화 전류 곡선에서 최대 이온화 전류를 나타내는 거리를 교정의 기준점으로 정하고, 이 이온화 전류 측정치로부터 공기커마강도를 구하였다. 이온화 전류 곡선의 정점인 최대 이온화 전류에 대응하는 거리는 50 mm이었다. 이 거리는 UW-ADCL의 교정 검증서의 선원의 기준점과 완전히 일치하였다. 측정으로 계산된 공기커마강도는 제조사에서 제공된 교정치보다 약 0.5% 더 높게 측정되었다. 제조사에서 제공되는 교정 검증서의 공기커마강도는 신뢰할 수 있는 정확성을 가졌다는 결과를 얻었다. 측정에서 우물형 이온함 안의 dead space의 길이와 선원의 dwell position으로 이동 오차 그리고 산란선의 영향 등을 고려하면, 정확한 측정과 교정의 결과를 얻을 수 있다고 생각된다.

• International Journal of Concrete Structures and Materials
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• 제5권2호
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• pp.119-123
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• 2011

Presented in the paper are findings of a project that examined the effect of slag grade and cement source on the performance of concrete mixtures. Slag cement contents were 20, 40, and 60 percent of the total cementitious material content. Two grades of slag cement were examined (Gr. 100 and Gr. 120) along with two sources of Type I cement. Compressive strength, durability, and permeability were measured. The results showed that the cement source affected the early age strength of the mixtures. At 28 days of age, mixtures containing Gr. 120 slag cement had higher compressive strengths than mixtures containing Gr. 100 slag cement, but by 90 days of age, the trend reversed. As for the chloride ion penetrability, mixtures cast with Gr. 100 slag cement passed fewer coulombs at 28 and 90 days of age than similar mixtures containing Gr. 120 slag. Mixtures containing Gr. 120 slag had the greatest durability factors.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.117-118
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• 2016

This paper evalutes properties of extruding cement panel using Ca-extracted convert slag and air-cooled blast furnace slag. Flexural strength of extruding cement panel has measured in air dry and autoclave curing as basic study for use as silicious source. As a result, when Ca-extracted converter slag replaces 25% in autoclave curing, flexural strength measures 13.1MPa better than panel control mix. In result of using air-cooled blast furnace slag, Ca-extracted air-cooled blast furnace slag dose not show increase of flexural strength.

• 대한조선학회논문집
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• 제47권2호
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• pp.196-209
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• 2010

For the analysis of Acoustic Target Strength(TS) that indicates the scattered acoustic intensity from the underwater vehicles, an analysis program that is applicable to scatterers insonified by spherical wave source in near field is developed. In this program, the Physical Optics(PO) method is embedded as a base component. To increase the accuracy of the program, multiple bounce effects based on Geometrical Optics(GO) method are applied. To implement multiple bounce effects, GO method is used together with PO method. In detail, GO method has a concern in the evaluation of the effective area, and PO method is involved in the calculation of Acoustic Target Strength for the final effective area that is evaluated by GO method. For the embodiment of near field spherical wave source originated multiple bounce effects, image source concept is implemented additively to the existing multiple bounce algorithm which assumes plane wave insonification. Various types of models are tested to evaluate the reliability of the developed program and finally, a submarine is analyzed as an arbitrary scatterer.

• 한국의류학회지
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• 제2권2호
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• pp.237-243
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• 1978

Dermatophytes such as Trichophyton mentagrophytes, Trichophyton rubrum and Epidermophyton floccosum are used in this study to confirm (a) The Dermatophytes could utilize the wool, cotton and nylon fiber as a nutrient source. (b) The degree of damage of fibers by the Dermatophytes growth. The results of the experiment are summarized as follows; 1. Dermatophytes could not utilize the wool, cotton and nylon fiber directly as a nutrient source without the exogenously applied nutrients. 2. It was presumed that Dermatophytes could utilize the knitted wool fabric as their nutrient source when nutrient was exogenously applied. since the knitted wool fabric was greatly damaged by T. mentagrophytes and T. rubrum growth. 3. The tensile strength of knitted wool fabric was significantly decreased by T. mentagrophytes and T. rubrum, but not by E. floccosum. However, the tensile strength of knitted nylon fabric was not particularly affected by the Dermatophytes. 4. The burst strength of knitted wool fabric was decreased by T. mentagrophytes ($77\%$). T. rubrum ($53\%$). and E. floccosum ($15\%$). Though the burst strength of knitted cotton fabric was decreased by Dermatophytes about $20\%$, that of knitted nylon fabric was not affected. 5. Observing the damaged wool fiber by scanning microscope, the inner part of wool fiber was permeated by T. mentagrophytes and T. rubrum.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.452-452
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• 2006