• Nuclear Engineering and Technology
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• 제55권6호
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• pp.1988-1993
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• 2023

This experimental study investigated the effect of silica fume mixed in concrete blocks on laser-induced explosion behavior. We used a 5.3 kW fiber laser as a thermal source to induce explosive spalling on a concrete surface blended with and without silica fume. An analytical approach based on the difference in the removal rate and thermal behavior was used to determine the effect of silica fume on laser-induced explosive spalling. A scanner was employed to calculate the laser-scabbled volume of the concrete surface to derive the removal rate. The removal rate of the concrete mixed with silica fume was higher than that of without silica fume. Thermal images acquired during scabbling were used to qualitatively analyze the thermal response of laser-induced explosive spalling on the concrete surface. At the early stage of laser heating, an uneven spatial distribution of surface temperature appeared on the concrete blended with silica fume because of frequent explosive spalling within a small area. By contrast, the spalling frequency was relatively lower in laser-heated concrete without silica fume. Furthermore, we observed that a larger area was removed via a single explosive spalling event owing to its high porosity.

• 한국환경보건학회지
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• 제49권3호
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• pp.129-133
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• 2023

Background: With the rise in global mobility, aircraft indoor air quality has become a significant public health concern. This study focuses on the health implications of increased travel and bleed air-air drawn from aircraft engines for cabin pressurization and air conditioning. Objectives: This research aims to review the potential health effects related to exposure to aircraft cabin air, particularly the effects of bleed air during fume events. Methods: We conducted a literature review of existing studies on aircraft cabin air quality. We focused on both the immediate and health effects of exposure to cabin air, particularly those related to bleed air contaminants. Results: The review found a possible link between exposure to aircraft cabin air and certain health issues, especially in cabin crew and frequent flyers. There was an increased incidence of respiratory and neurological symptoms related to bleed air exposure. However, the cumulative health effects of frequent air travel remain inconclusive due to limited data. Conclusions: This study highlights the need for improving air quality in aircraft to protect public health. While further research is needed to understand the cumulative effects of frequent air travel, the reduction of exposure to bleed air contaminants should be a priority. These findings underline the need for regulatory changes and technological improvements in aircraft cabin air quality.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.893-896
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• 2008

본 연구는 황산염 환경하에서 메타카올린을 사용하여 제작된 시멘트 모르타르의 기초물성을 평가하기 위한 연구이다. 최근 열악한 환경에 노출되는 콘크리트 구조물이 증가함에 따라 콘크리트의 내구성에 대한 관심이 늘어나고 있다. 광물성 혼화재료를 첨가할 경우 콘크리트 내부의 조직을 치밀하게 하여 내구성을 좋게하는 방안이 있으며 현재에도 실리카흄, 플라이애쉬, 슬래그와 같은 기존의 광물질 혼화재료 이외에 새로운 혼화재료에 대한 연구가 활발히 진행되고 있는 실정이다. 따라서 본 연구에서는 열악한 환경에 노출된 콘크리트 열화에 대하여 아직 그 연구가 미비한 광물질 혼화재료인 메타카올린을 5%, 10%, 15%로 치환하여 시멘트 모르타르로 시편을 제작하였고, 이를 28일 표준양생을 시켜 담수, 해수, 10% 황산나트륨용액, 10% 황산마그네슘 용액에서 28일, 60일, 90일, 180일, 270일, 365일 동안 촉진양생 시켜 다양한 시편의 기초물성에 대한 실험을 수행하였다. 또한 현재 널리 쓰이고 있는 광물질 혼화재료인 실리카흄과 플라이애쉬를 가지고 같은 방법으로 실험을 한 후 메타카올린을 치환한 시편과의 비교 분석을 통하여 메타카올린의 내구적 성능을 평가하고자 한다.