Size-resolved culturable airborne bacteria sampled in rice field, sanitary landfill, and waste incineration sites

Heo, Yongju,Park, Jiyeon,Lim, Sung-il,Hur, Hor-gil,Kim, Daesung,Park, Kihong Royal Society of Chemistry 2010 Journal of environmental monitoring Vol.12 No.8

<P>Size-resolved bacterial concentrations in atmospheric aerosols sampled by using a six stage viable impactor at rice field, sanitary landfill, and waste incinerator sites were determined. Culture-based and Polymerase Chain Reaction (PCR) methods were used to identify the airborne bacteria. The culturable bacteria concentration in total suspended particles (TSP) was found to be the highest (848 Colony Forming Unit (CFU)/m<SUP>3</SUP>) at the sanitary landfill sampling site, while the rice field sampling site has the lowest (125 CFU/m<SUP>3</SUP>). The closed landfill would be the main source of the observed bacteria concentration at the sanitary landfill. The rice field sampling site was fully covered by rice grain with wetted conditions before harvest and had no significant contribution to the airborne bacteria concentration. This might occur because the dry conditions favor suspension of soil particles and this area had limited personnel and vehicle flow. The respirable fraction calculated by particles less than 3.3 μm was highest (26%) at the sanitary landfill sampling site followed by waste incinerator (19%) and rice field (10%), which showed a lower level of respiratory fraction compared to previous literature values. We identified 58 species in 23 genera of culturable bacteria, and the <I>Microbacterium</I>, <I>Staphylococcus</I>, and <I>Micrococcus</I> were the most abundant genera at the sanitary landfill, waste incinerator, and rice field sites, respectively. An antibiotic resistant test for the above bacteria (<I>Micrococcus sp</I>., <I>Microbacterium sp</I>., and <I>Staphylococcus sp</I>.) showed that the <I>Staphylococcus sp</I>. had the strongest resistance to both antibiotics (25.0% resistance for 32 μg ml<SUP>−1</SUP> of Chloramphenicol and 62.5% resistance for 4 μg ml<SUP>−1</SUP> of Gentamicin).</P> <P>Graphic Abstract</P><P>This study provides dominant types of airborne bacteria existing in different outdoor environments, leading to better understanding of their source and effects on human health. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0em00004c'> </P>

Aligned networks of cadmium sulfide nanowires for highly flexible photodetectors with improved photoconductive responses

Heo, Kwang,Lee, Hyungwoo,Park, Yongju,Park, Jinho,Lim, Hyun-Jin,Yoon, Duhee,Lee, Changhee,Kim, Miyoung,Cheong, Hyeonsik,Park, Jonghyurk,Jian, Jikang,Hong, Seunghun The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.5

<P>We developed a simple but efficient method to mass-produce highly flexible and high-performance photodetectors based on aligned cadmium sulfide (CdS) nanowire (NW) networks. In this method, the CdS NWs were selectively aligned along the molecular patterns on flexible substrates <I>via</I> a direct assembly method, and the aligned CdS NW patterns were utilized as the channels of flexible photodetectors. The photodetectors based on the aligned CdS NWs exhibited ∼10 times higher photosensitivity and ∼100 times faster photoresponse than those based on randomly oriented NW networks. In addition, the flexible photodetectors exhibited stable photoconductive characteristics even when these were bent down to the radius of curvature of 0.2 mm. This research may pave the way for the large-scale fabrication of low-cost and high performance flexible photodetectors based on the aligned NW networks.</P> <P>Graphic Abstract</P><P>We developed a simple method to mass-produce highly flexible and high-performance photodetectors based on <I>aligned</I>-cadmium sulfide nanowire networks. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm14359c'> </P>

Bi-Assisted CdTe/CdS Hierarchical Nanostructure Growth for Photoconductive Applications

Heo, Kwang,Lee, Hyungwoo,Jian, Jikang,Lee, Dong-Jin,Park, Yongju,Lee, Changhee,Lee, Byung Yang,Hong, Seunghun Springer US 2015 NANOSCALE RESEARCH LETTERS Vol.10 No.1

<P>We developed a method to control the structure of CdTe nanowires by adopting Bi-mixed CdTe powder source to a catalyst-assisted chemical vapor deposition, which allowed us to fabricate CdTe/CdS hierarchical nanostructures. We demonstrated that diverse nanostructures can be grown depending on the combination of the Bi powder and film catalysts. As a proof of concepts, we grew CdTe/CdS branched nanowires for the fabrication of photodetectors. The hierarchical nanostructure-based photodetectors showed an improved photoresponsivity compared to the single CdTe nanowire (NW)-based photodetector. Our strategy can be a simple but powerful method for the development of advanced optoelectronic devices and other practical applications.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s11671-015-1037-6) contains supplementary material, which is available to authorized users.</P>

일차원 설계 방법론을 이용한 준등온압축기 공력 설계 및 해석에 관한 연구

정용주(Yongju Jeong),조성국(Seong Kuk Cho),허진영(Jin Young Heo),이정익(Jeong Ik Lee) 한국유체기계학회 2018 한국유체기계학회 학술대회 논문집 Vol.2018 No.7

Graphene–nanowire hybrid structures for high-performance photoconductive devices

Lee, Hyungwoo,Heo, Kwang,Park, Jaesung,Park, Yongju,Noh, Seunguk,Kim, Kwang S.,Lee, Changhee,Hong, Byung Hee,Jian, Jikang,Hong, Seunghun The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.17

<P>Graphene–CdS nanowire (NW) hybrid structures with high-speed photoconductivity were developed. The hybrid structure was comprised of CdS NWs which were selectively grown in specific regions on a single-layer graphene sheet. The photoconductive channels based on graphene–CdS NW hybrid structures exhibited much larger photocurrents than graphene-based channels and much faster recovery speed than CdS NW network-based ones. Our graphene–CdS NW structures can be useful because they were much faster than commercial CdS film-based photodetectors and had photocurrents large enough for practical applications.</P> <P>Graphic Abstract</P><P>We have developed a photoconductive channel based on graphene–CdS nanowire hybrid structures which exhibited large photocurrent and fast recovery speed. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm16565a'> </P>

미래 정보과 교육과정을 위한 빅 아이디어 제안

허희옥(Heeok Heo),강신천(Shinchun Kang),전용주(Yongju Jeon),김한일(Hanil Kim) 한국컴퓨터교육학회 2021 컴퓨터교육학회 논문지 Vol.24 No.2

본 논문은 차기 정보과 교육과정 구성을 위한 빅 아이디어를 제안하는 데에 그 목적이 있다. 빅 아이디어는 이해중심교육과정을 구성하는 핵심요소이다. 우리나라에서 빅 아이디어를 중심으로 한 이해중심교육과정은 이미 2015 개정 교육과정을 설계하는 과정에서 소개되었고, 실제로 교육과정에 빅 아이디어가 핵심개념으로 포함되었다. 하지만, 이 핵심 개념이 학생들의 영속적인 이해를 이끄는 빅 아이디어라기 보다는 학습 주제를 나타낸다는 지적이 있었다. 따라서, 본 연구는 Wiggins & McTighe가 제시한 이해중심교육과정을 고려한 정보과의 빅 아이디어를 도출하고 이에 포함되는 지식, 기능, 태도와 가치를 제시하기 위하여 수행되었다. 정보과 빅 아이디어를 도출하기 위하여, 문헌연구, 전문가 협의, 수정된 델파이 조사 방법을 이용하였다. 전문가 협의에 참여한 전문가는 연구진을 포함하여 총 12명이며, 수정된 델파이 조사에 참여한 전문가는 총 40명이다. 문헌연구와 전문가 협의를 통하여 빅 아이디어, 빅 아이디어에 포함된 지식, 기능, 태도와 가치를 도출하고 이 결과를 이용하여 델파이 조사지를 개발하였다. 수정된 델파이 조사는 총 2회 진행되었다. 본 연구의 결과로 도출된 빅 아이디어는 총 5가지이며, 이를 명사형으로 제시하면, 표현(representation), 추상화(abstraction), 자동화(automation), 네트워킹(networking), 디지털 감수성(digital sensitivity)이다. 빅 아이디어별로 학문 내 지식과 간학문적 지식을 제시하고, 통합적으로 적용할 수 있는 핵심 기능과 태도 및 가치를 제시하였다. 본 연구의 결과는 빅 아이디어를 중심으로 정보과 교육과정을 설계하거나 교사의 학교 수업 설계 및 운영을 위한 기초 자료로 활용될 수 있다. 아울러, 빅 아이디어를 중심으로 한 필수 학습요소 체계화, 이해중심 정보과 교육과정 설계, 교사교육 프로그램 연구 등을 후속 연구로 제안하였다. This study aims to identify big ideas for developing the next Informatics curriculum. The big idea is an essential component in constructing a curriculum based on understanding by design. Understanding by design as a curriculum theory was introduced in revising the national curriculum in 2015, and the big idea was provided as key concept in curriculum by subjects. However, there have been on-going debates that the key concepts are closer to the topics of subjects rather than the big ideas for learners to arrive at enduring understanding of a subject. Therefore, we conducted a study to identify big ideas of Informatics, and its related knowledge, skills, attitudes and values. For this, the study carried out the analysis of existing studies, expert meetings, and the modified Delphi study. 12 experts were participated in the expert meetings including researchers in this study, and 40 experts were engaged in the modified Delphi study. Through the analysis of existing studies and the expert meetings, the first draft of big ideas was identified, and a questionnaire of the 1<SUP>st</SUP> Delphi round was developed. The modified Delphi survey was carried out in 2 rounds. As a result, 5 big ideas were identified: representation, abstraction, automation, networking and digital sensitivity in the nouns. Also, disciplinary and interdisciplinary knowledge, skills, attitudes and values were identified for each big idea. The big ideas can be used to redesign Informatics curriculum, and design and implement classroom lessons. A few further studies were suggested as follows: construction of the essential learning elements for school education, development of Informatics curriculum based on understanding by design, and development of teacher education programs for curriculum reconstruction.

PVC 젤 기반 렌즈를 사용한 소형 경관조명

정은진(Eun-Jin Jung),허용해(Yong Hae Heo),정용주(Yongju Jung),김상연(Sang-Youn Kim),진경복(Kyoungbog Jin) 한국디지털콘텐츠학회 2024 한국디지털콘텐츠학회논문지 Vol.25 No.3

This study proposes a compact landscape illumination consisting of an electro-active varifocal lens, a laser, and a housing. The varifocal lens was developed using a polyvinyl chloride (PVC) gel-based electroactive polymer and a printed circuit board having a central hole, the perimeter of which was coated with copper. Depending on the applied voltage, the shape of the varifocal lens changed from convex to planar, which determined whether the light generated by the laser was collected or spread. Experiments were conducted to verify the mechanical, optical, and dielectric properties of the PVC gel. Another experiment investigated whether the shape of the PVC gel-based proposed lens changed from convex to planar, observing that the amount of convergence (or dispersion) of the light from the compact landscape illumination can be controlled by applying a voltage.

Inhalation of Carbon Black Nanoparticles Aggravates Pulmonary Inflammation in Mice

Saputra, Devina,Yoon, Jin-Ha,Park, Hyunju,Heo, Yongju,Yang, Hyoseon,Lee, Eun Ji,Lee, Sangjin,Song, Chang-Woo,Lee, Kyuhong Korean Society of ToxicologyKorea Environmental Mu 2014 Toxicological Research Vol.30 No.2

An increasing number of recent studies have focused on the impact of particulate matter on human health. As a model for atmospheric particulate inhalation, we investigated the effects of inhaled carbon black nanoparticles (CBNP) on mice with bleomycin-induced pulmonary fibrosis. The CNBPs were generated by a novel aerosolization process, and the mice were exposed to the aerosol for 4 hours. We found that CBNP inhalation exacerbated lung inflammation, as evidenced by histopathology analysis and by the expression levels of interleukin-6 protein, fibronectin, and interferon-${\gamma}$ mRNAs in lung tissues. Notably, fibronectin mRNA expression showed a statistically significant increase in expression after CBNP exposure. These data suggest that the concentration of CBNPs delivered (calculated to be $12.5{\mu}g/m^3$) can aggravate lung inflammation in mice. Our results also suggest that the inhalation of ultrafine particles like PM 2.5 is an impactful environmental risk factor for humans, particularly in susceptible populations with predisposing lung conditions.

Inhalation of Carbon Black Nanoparticles Aggravates Pulmonary Inflammation in Mice

Devina Saputra,Jin-ha Yoon,Hyunju Park,Yongju Heo,Hyoseon Yang,Eun Ji Lee,Sangjin Lee,Chang-Woo Song,Kyuhong Lee 한국독성학회 2014 Toxicological Research Vol.30 No.2

An increasing number of recent studies have focused on the impact of particulate matter on human health. As a model for atmospheric particulate inhalation, we investigated the effects of inhaled carbon black nanoparticles (CBNP) on mice with bleomycin-induced pulmonary fibrosis. The CNBPs were generated by a novel aerosolization process, and the mice were exposed to the aerosol for 4 hours. We found that CBNP inhalation exacerbated lung inflammation, as evidenced by histopathology analysis and by the expression levels of interleukin-6 protein, fibronectin, and interferon-γ mRNAs in lung tissues. Notably, fibronectin mRNA expression showed a statistically significant increase in expression after CBNP exposure. These data suggest that the concentration of CBNPs delivered (calculated to be 12.5 μg/m3) can aggravate lung inflammation in mice. Our results also suggest that the inhalation of ultrafine particles like PM 2.5 is an impactful environmental risk factor for humans, particularly in susceptible populations with predisposing lung conditions.

A cluster of lung injury associated with home humidifier use: clinical, radiological and pathological description of a new syndrome

Hong, Sang-Bum,Kim, Hwa Jung,Huh, Jin Won,Do, Kyung-Hyun,Jang, Se Jin,Song, Joon Seon,Choi, Seong-Jin,Heo, Yongju,Kim, Yong-Bum,Lim, Chae-Man,Chae, Eun Jin,Lee, Hanyi,Jung, Miran,Lee, Kyuhong,Lee, Moo BMJ Publishing Group Ltd 2014 Thorax Vol.69 No.8

<P><B>Background</B></P><P>Over a few months in the spring of 2011, a cluster of patients with severe respiratory distress were admitted to our intensive care unit (ICU). Household clustering was also observed. Extensive laboratory investigations failed to detect an infectious cause.</P><P><B>Methods</B></P><P>Clinical, radiological and pathological investigations were conducted and the Korean Center for Disease Control performed epidemiological studies.</P><P><B>Results</B></P><P>The case series consisted of 17 patients. Their median age was 35 (range 28–49) years. Six were pregnant at presentation and four had given birth 2 weeks previously. All presented with cough and dyspnoea. In the majority of patients (14/17), multifocal areas of patchy consolidation were identified in the lower lung zones on the initial CT. As the condition progressed, the patchy consolidation disappeared (10/13) and diffuse centrilobular ground-glass opacity nodules started to predominate and persist. Pathological specimens (11/17) showed a bronchiolocentric, temporally homogenous, acute lung injury pattern with sparing of the subpleural and peripheral alveolar areas. Ten patients required mechanical ventilation, eight of whom subsequently received extracorporeal life support. Four of the latter underwent lung transplantation. Five of the six patients in the ICU who did not receive lung transplantation died. An epidemiological investigation revealed that all patients had used humidifier disinfectants in their homes.</P><P><B>Conclusions</B></P><P>This case series report showed that lung injury and respiratory failure can occur as a result of inhaling humidifier disinfectants. This emphasises the need for more stringent safety regulations for potentially toxic inhalants that might be encountered in the home.</P>