• 한국소음진동공학회논문집
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• 제27권2호
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• pp.243-250
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• 2017

In this study, single number rating methods of sound absorption coefficients are discussed. After that the sound absorption performance of noise barriers which are classified by Korea Standard are analyzed according to several standards. The existing rating methods such as NRC (noise reduction coefficient), SAA (sound absorption average) or ${\alpha}_w$ (weighted sound absorption coefficient) from ASTM C423, KS F 3505 and ISO 11654 are introduced. The sound absorption performance of noise barrier is evaluated to compare NRC and ${\alpha}_w$ value. When the value is over 0.6 there are large variance between NRC and ${\alpha}_w$ value. As results, it is needed to unify single number rating methods of sound absorption coefficients for Korean standards on sound absorbing materials.

• Asian-Australasian Journal of Animal Sciences
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• 제13권10호
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• pp.1445-1449
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• 2000

A total of one hundred twenty pigs ($L{\times}Y{\times}D$, $50{\pm}0.78kg$) were employed for a 7-week feeding trial to determine the effect of inclusion levels of vitamin and mineral (VTM) premixes on growth performance, nutrient digestibility and pork stability in finishing pigs. Treatments were 100% (Control), 150%, 200%, and 250% of NRC (1998) requirements. Increasing dietary VTM premixes in finishing pigs had a linear (p<0.05) effect on ADG. It also had a linear effect (p<0.05) on the digestibility of calcium and a linear and quadratic effect (p<0.05) on the digestibility of phosphorus. As dietary VTM levels were increased from 100 to 250% NRC (1998), TBARS values of pork samples were linearly (p<0.05) lowered when stored at $1^{\circ}C$ for 2 or 3 weeks. There was also a trend reducing POV of pig meat as dietary VTM level was increased. In conclusion, it would appear that inclusion of VTM premixes at the level of 200-250% of NRC (1998) requirements gave positive effects on growth performance and pork stability in finishing pigs.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.337-340
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• 2004

In recent days, the beneficial effects of using fiber reinforced concrete, especially Steel Fiber Reinforced Concrete, have been on the rise. However, few studies on long-term behavior of SFRC are executed in spite of great demand of SFRC. The fact that SFRC is far better than NRC in various properties such as tensile strength, ductility, flexural toughness has been certified by many researchers. And, those advantages can be also applied to decrease the structures deterioration induced by creep and shrinkage. Furthermore, even though it is fact that SFRC is generally used in joint members to distribute concentrated stresses by fibers, SFRC is treated as NRC in designing especially for long-term behavior of structures. So this paper is about a study on the long-term response of SFRC applied to HPC about 40MPa. Therefore, in this paper, the test results of eighteen high-strength concrete specimens and steel fiber-reinforced concrete specimens, with steel fiber content of $1\%$ by volume were presented. The test result shows that SFRC is advantageous rather than NRC in long-term response.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1686-1697
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• 2022

As a part of probabilistic risk (or safety) assessment (PRA or PSA) of nuclear power plants (NPPs), the primary role of human reliability analysis (HRA) is to provide credible estimations of the human error probabilities (HEPs) of safety-critical tasks. Accordingly, HRA community has emphasized the accumulation of HRA data to support HRA practitioners for many decades. To this end, it is critical to resolve practical problems including (but not limited to): (1) how to collect HRA data from available information sources, and (2) how to inform HRA practitioners with the collected HRA data. In this regard, the U.S. Nuclear Regulatory Commission (NRC) and Korea Atomic Energy Research Institute (KAERI) independently initiated two large projects to accumulate HRA data by using full-scale simulators (i.e., simulator data). In terms of resolving the first practical problem, the NRC and KAERI developed two dedicated HRA data collection systems, SACADA (Scenario Authoring, Characterization, And Debriefing Application) and HuREX (Human Reliability data EXtraction), respectively. In addition, to inform HRA practitioners, the NRC and KAERI proposed several ideas to extract useful information from simulator data. This paper is the first of two papers to discuss the technical underpinnings of the development of the SACADA and HuREX systems.

• 방사성폐기물학회지
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• 제21권3호
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• pp.347-357
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• 2023

United States Nuclear Regulatory Commission (U.S. NRC) specifies regulations on obtaining licenses and describes the technical position on the average waste concentration, also known as Concentration Averaging and Encapsulation Branch Technical Position (CA BTP); CA BTP helps classify blendable waste and discrete items and address concentration averaging. The technical position details are reviewed and compared in a real environment in Korea. A few cases of concentration averaging based on the application of CA BTP to domestic radioactive waste are presented, and the feasibility of the application is assessed. The radioactive waste considered herein does not satisfy the Disposal Concentration Limit (DCL) of the second-phase disposal facility while applying the preliminary classification. However, if CA BTP is applied when the radioactive waste is mixed with other radioactive waste items in a large and heavy container, it can be disposed of at the second-phase disposal facility in Gyeongju Repository. To apply the CA BTP of the U.S. NRC, it is necessary to investigate the safety assessment conditions of the US and Korea.

• Journal of the Korean Wood Science and Technology
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• 제51권6호
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• pp.470-480
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• 2023

This study aimed to develop a sound-absorbing composite using sugarcane bagasse (SB) and coffee silver skin (CS) as raw materials. The composite boards were manufactured by bonding the fibers with Melamine Urea-Formaldehyde adhesive, ensuring a consistent thickness of 30 mm. Various densities were employed, namely 380, 450, and 520 kg/m³. The samples were fabricated with different fiber ratios, including SB100%, SB75% with CS25%, and SB50% with CS50%. The sound absorption coefficient (SAC) and noise reduction coefficient (NRC) were measured using the impedance tube method within a frequency range of 63-6,300 Hz. The experimental results revealed that the mixing ratio of CS exerted a notable influence on enhancing the SAC, while the density of the composite board exhibited a significant impact on increasing both the SAC and NRC. Among the densities tested, the optimal value was observed at 520 kg/m³, yielding a SAC value of 0.65 at a frequency of 1,000 Hz and an NRC value of 0.55 for the SB50-CS50 composite plate. These findings underscore the importance of considering the CS mixing ratio and composite board density when aiming to optimize sound absorption properties.

• Journal of Radiation Protection and Research
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• 제37권3호
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• pp.116-122
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• 2012

미국 원자력규제위원회(U. S. NRC)에서 개발한 PAVAN 프로그램을 사용하여 기상자료의 통계처리방법에 따른 원자력발전소의 수명기간 중 발생할 수 있는 가상 사고시 단기 대기확산인자 값의 영향을 분석하였다. 대기확산을 평가하기 위한 기본요소는 기상자료이며, PAVAN에서는 대기안정도에 대한 풍향과 풍속의 발생빈도를 나타내는 결합빈도분포자료를 사용하여 평가한다. 고리와 월성 원자력발전소 부지에서 2006~2010년까지 5년간 관측된 기상자료를 사용하여 풍속등급의 분류방법(U. S. NRC 권고와 균등발생빈도 분류방법)과 평가에 적용되는 기상자료의 통계처리기간(1년, 2년, 3년, 4년, 5년)에 따른 결합빈도분포자료를 작성하여 단기 대기확산인자를 평가하였다. 평가결과, 두 원자력발전소 부지 모두 풍속등급의 분류에 따른 단기 대기확산인자 값의 영향은 미미한 반면 평가에 적용되는 기상자료의 분석기간은 상대적으로 중요한 영향을 나타냈는데, 최대값과 최소값의 비는 1.5배 이상의 차이를 보였다.

• 방사성폐기물학회지
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• 제14권3호
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• pp.235-243
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• 2016

우리나라를 포함한 많은 국가들에서 향후 원전 해체로 저준위폐기물이 대량으로 발생할 전망이다. 본 논문에서는 미국의 저준위방사성폐기물 처분 관련 규제 기준을 분석하고, 특히 원자력발전소의 운영 및 해체를 포함하는 전주기에서 발생하는 폐기물의 처분 옵션을 확장하는 방안으로 사용되고 있는 저준위방사성폐기물의 블랜딩에 대해 검토하였다. 2007년 미국 NRC는 미국 저준위폐기물 관리 프로그램에 대한 전략분석 결과, 방사선위험도와 성능평가에 기반한 새로운 저준위폐기물 관리 규제의 필요성을 제기하였는데, 특히 방사성핵종 농도가 다른 폐기물의 블랜딩을 처분에 대한 옵션을 다양화할 수 있는 안전한 방안으로 제시하였다. NRC는 블랜딩을 처분에 적합하도록 방사성핵종의 농도가 다른 저준위폐기물을 비교적 균일하게 혼합(mixing)하는 것으로 정의하였다. 2015년 2월 농도 평균과 포장에 대한 NRC BTP의 개정판으로 공표된 블랜딩에 대한 구체적인 기술요건을 분석하였고 국내 해체폐기물에 대한 적용 방안도 예시하였다. 대량으로 발생할 해체폐기물에 대해 블랜딩과 농도평균을 적용하면 처분 효율성을 향상시킬 수 있다. 바이오쉴드 콘크리트에 대한 농도평균 적용에 대해 예시하였다.

• 원자력산업
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• 제37권5호
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• pp.52-66
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• 2017

• 동위원소뉴스
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• 11호통권47호
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• pp.6-9
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• 2000