• 한국전기전자재료학회논문지
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• 제35권4호
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• pp.412-417
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• 2022

Capacitive-type humidity sensors with a high sensitivity and fast response/recovery times have attracted a great attention in non-contact respiration biological signal monitoring applications. However, complicated fabrication processes involving high-temperature heat treatment for the hygroscopic film is essential in the conventional ceramic-based humidity sensors. In this study, a non-toxic ceramic/metal halide (BaTiO₃(BT)/NaCl) humidity sensor was prepared at room temperature using a solvent-free aerosol deposition process (AD) without any additional process. Currently prepared BT/NaCl humidity sensor shows an excellent sensitivity (245 pF/RH%) and superior response/recovery times (3s/4s) due to the NaCl ionization effect resulting in an immense interfacial polarization. Furthermore, the non-contact respiration signal variation using the BT/NaCl sensor was determined to be over 700% by maintaining the distance of 20 cm between the individual and the sensor. Through the AD-fabricated sensor in this study, we expect to develop a non-contact biological signal monitoring system that can be applied to various fields such as respiratory disease detection and management, infant respiratory signal observation, and touchless skin moisture sensing button.

• 청정기술
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• 제14권2호
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• pp.136-143
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• 2008

본 연구에서는 오리멀젼(orimulsion)을 연소하는 발전소에서 배출되는 가시백연의 가시도 증가를 확인하고, 그 원인을 파악하고자 하였다. 오리멀젼을 연료로 사용하는 발전소에서는 미세 먼지입자와 황화합물이 포함된 연기를 발생한다. 발전소 공정데이터를 바탕으로 미세 먼지입자의 영향에 대해서는 모니터링을 통한 로그정규분포로 배출입자의 입도분포를 대입하였고, 황화합물 에어로졸 2차 입자의 주성분$(NH_4)_2SO_4$의 생성 화학방정식을 고려하였다. 연기에 의한 가시도를 정량적으로 평가하고자 미국의 EPA에서 개발된 대표적 시정모델인 PLUVUE-II 모델을 응용하였다. PLUVUE-II 모델이 단파장에만 모사되는 문제를 개선하여 가시광선 전 영역에서 계산이 가능하도록 하여 가시도에 따른 최대 연기거리를 광학적 방법으로 계산하였다. 모델링 결과로써 미세입자의 분포와 황화합물의 농도에 따른 최대 연기거리의 변화를 평가하였다. 연구 결과로 오리멀젼의 연소로 발생된 가시백연이 미세입자와 황화합물의 2차 입자에 의해 유발될 수 있음을 확인하였으며, 이러한 가시백연의 저감을 위해서는 미세입자의 크기와 황 화합물의 배출에 대한 제어가 필요하다고 판단된다.

• 한국환경보건학회지
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• 제48권2호
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• pp.116-122
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• 2022

Background: The recent COVID-19 pandemic is one of the worst disease outbreaks of the 21th century. Due to a lack of reliable antiviral therapeutics, wearing face masks is recommended to prevent airborne infection originating from virus-contaminated bioaerosols. Objectives: The aim of this study was to evaluate the filtration efficiencies of face masks that are commercially available in South Korea for a biological aerosol of Staphylococcus aureus (S. aureus) and murine coronavirus, a well-known surrogate for human coronaviruses. Methods: We collected six different kinds of commercial masks: two Korea Filter (KF)94 (KF94-1, KF94-2) masks, one surgical (Surgical-1) mask, one anti-droplet (KF-AD-1) mask, and two dust (Dust-1, Dust-2) face masks. S. aureus (ATCC 6538), a well-performing test bacteria and murine coronavirus (ATCC VR-764) were prepared under a suitable culture condition. Then, a mask biological filtration tester was used to examine the microbial filtration efficiencies of masks. Test microorganisms were quantitatively measured via cultivation methods and microbial filtration efficiencies were calculated appropriately. Results: All face masks showed over 99.6% filtration efficiency for S. aureus or murine coronavirus. There were no significant differences among the bacterial filtration efficiencies of the face masks. KF94-1 (99.97±0.08%) and Dust-1 mask (99.97±0.07%) showed the highest (over 99.9%) filtration efficiency for murine coronavirus. KF94-1 or Dust-1 masks showed a significant virus filtration efficiency compared to Surgical-1 mask (p<0.05; Mann-Whitney U test). Conclusions: All the commercially available face masks used in this study can filter S. aureus or murine coronavirus in bioaerosols efficiently, regardless of the mask type. Therefore, our results suggest that wearing a certified face mask is a reliable means to prevent the transmission of infectious airborne diseases via biological aerosols.

• 청정기술
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• 제14권4호
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• pp.242-247
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• 2008

화장품, 의약품, 전자소재 분야에서 생체적합, 생분해성 고분자로 널리 사용되는 폴리비닐피롤리돈(PVP)을 에어로젤 용매추출 방법에 의해 미세입자를 제조하였다. 용매로는 이 염화메탄올, 반용매로는 초임계 이산화탄소가 사용되었다. 온도, 압력, 이산화탄소 유량, 용액유량의 작업조건에 따라 0.184 - $0.249\;{\mu}m$입자크기를 얻었고, 그 입자크기에 영향을 미치는 초기구형 입자크기와의 상관관계를 규명하였다.

• 한국입자에어로졸학회지
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• 제5권2호
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• pp.83-90
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• 2009

This paper describes a condensation-evaporation method (CEM) to produce size-controlled spherical silver nanoparticles by perturbing coagulation and coalescence processes in the gas phase. Polydisperse silver nanoparticles generated by the CEM were first introduced into a differential mobility analyzer (DMA) to select a group of silver nanoparticles with same electrical mobility, which also enables to make a group of nanoparticles with elongated structures and same projected area. These silver nanoparticles selected by the DMA were then in-situ sintered at ${\sim}600^{\circ}C$, and then they were observed to turn into spherical shaped nanoparticles by the rapid coalescence process. With the assistance of modified converging-typed quartz reactor, we can also produce the 10 times higher number concentration of silver nanoparticles compared with a general quartz reactor with uniform diameter. Finally, the spherical silver nanoparticles with 30 nm were electrostatically deposited on the surface of silicon substrate with the coverage rate of ~4%/hr. This useful preparation method of size-controlled monodisperse silver nanoparticles developed in this work can be applied to the various studies for characterizing the physical, chemical, optical, and biological properties of nanoparticles as a function of their size.

• 한국군사과학기술학회지
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• 제18권3호
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• pp.335-342
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• 2015

Laboratory facilities for biology are designed as biosafety level 1, biosafety level 2, biosafety level 3, and biosafety level 4. Biosafety level designations are based on a composite of the design features, construction, containment facilities, equipment, practice and operation procedures required for working with agents from the various risk groups. Generally, biosafety level 3 means the facility that is appropriate for the experiments using pathogens which can cause serious diseases by aerosol transmission. The biosafety level assigned for the specific work to be done is driven by professional judgement based on a risk assessment, rather than by automatic assignment according to the particular risk group designation of the pathogenic agents to be used. In this paper, we introduced the biosafety level 3 facility operated in ADD(Agency for defense development). It contains the overview of facility, microbiological experiment, animal experiment, decontamination and waste disposal. Biosafety level 3 laboratory in ADD has served the vital role in the research of biological agents and antidote development.

• 대한의용생체공학회:의공학회지
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• 제30권5호
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• pp.438-443
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• 2009

Nebulizer is designed to atomize medicinal fluid for patient with small particles(0.5-$5{\mu}m$) and also able to deliver particles from devices to the lungs when patient inhales air. Several particle size measurements are currently used to size aerosol particles. The most commonly used test is the cascade impactor method in as a standard. But, other methods for comparative particle size distribution data such as the particle size range and reproducibility are acceptable. Therefore, in this study a new test methode is suggested for nonventilatory nebulizer evaluation equipment.

• 한국환경보건학회지
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• 제47권2호
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• pp.123-130
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• 2021

Objectives: Control methods against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) aerosols have been introduced. Airborne spreading theories for SARS-CoV-2 were analyzed in this study. Methods: Control methods for airborne microorganisms were discussed. Studies on theoretical estimations for airborne spreading of SARS-CoV-2 were presented and analyzed. Analytic calculations were conducted for explaining control techniques for airborne microorganisms. Results: Control methods for SARS-CoV-2 aerosols can include physical or biological procedures. Characterization of SARS-CoV-2 aerosols and massive clustering infection cases of COVID-19 support the airborne spreading theories of SARS-CoV-2. It is necessary to consider the disadvantages of control methods for airborne microorganisms. Conclusions: A study on control methods against bioaerosols is necessary to prevent the spreading of viruses. Airborne spreading theories of SARS-CoV-2 were supported by the current evidence, but further studies are needed to confirm these theories.

• Food Science and Biotechnology
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• 제17권3호
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• pp.447-456
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• 2008

Limonene, pinene, and isoprene are abundant and ubiquitous volatile organic compounds (VOCs) which are found in various natural products and also produced from various manufacture processes. Limonene and pinene are major components of food additives and household products for enrichment of good flavors and elimination of malodors, and isoprene is a basal motif of monoterpenes such as limonene and pinene. They have shown many beneficial effects such as chemopreventive, chemotherapeutic, and antioxidant activities. Upon certain conditions, however, adverse effects of these compounds on human health have also been reported. Although they do not seem to have acute and severe toxicity to human, they can easily generate secondary organic aerosols (SOAs) when they react with oxygen and/or ozone, which have shown certain toxic effects on experimental animal models as well as on humans. Numerous household and scented products containing limonene, pinene, and isoprene are widely used in these days. However, biological consequences upon exposure to these products are largely unknown. The aim of this review is to summarize and analyze the current understanding on the biological effects of VOCs, in particular limonene, pinene, and isoprene, as well as their SOAs.

• 대한의용생체공학회:의공학회지
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• 제33권4호
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• pp.177-183
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• 2012

The inspiratory flow rate of a human is changed with the amount of the workload. The flow characteristic is affected by the inspiratory flow rate. In the flow field of airway, the both of turbulence intensity and secondary flow affect the deposition pattern of particles which is important for the drug-aerosol targeting. Thus the analysis of the flow characteristic in a human airway is important. The purpose of this study is to investigate the effects of the inspiratory flow rate on the flow characteristics in a human airway. The tubular airway is consistent with the oral cavity, pharynx, larynx and trachea. The relatively inspiratory flow rate is used at each case of human states regarding the workload. By the effect of geometric airway changes, transition to turbulent airflow after the larynx can occur with relaminarization further downstream. The low Reynolds number k-${\omega}$ turbulence model is used for analysis with flow regime. As the inspiratory flow rate is larger, the turbulence kinetic energy and secondary flow intensity increase in airway. On the other hand, the area of recirculation zone is smaller.