Reduction procedure effect on the electrochemical properties of conductive carbon black supported Pt-Pd electrocatalysts.

Park, Jae Young,Park, Soo-Jin,Jung, Yongju,Kim, Seok American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.3

<P>Conductive carbon black supported Pt-Pd nanocomposites were prepared to study a difference of simultaneously and sequentially reduced Pt-Pd nanocomposites using polyol method. The concentration of Pt-Pd alloyed metals on carbon blacks (CB) was adjusted to 20 wt%. The catalysts could be characterized by transmission electron microscopy, X-ray diffraction and thermogravimetric analysis. The electrochemical activities of Pt-Pd were measured by cyclic voltammograms. As a result, electrochemical active surface area (ESA) value of sequentially deposited Pt-Pd/CB was shown to 66 m2/g, which was higher than 55 m2/g of simultaneously deposited Pt-Pd/CB. Besides, average particle size of sequentially deposited Pt-Pd/CB was calculated to 1.7 nm which was smaller than 2.2 nm of simultaneously deposited Pt-Pd/CB.</P>

Temperature and Light Intensity Dependence of Polymer Solar Cells with MoO_3 and PEDOT:PSS as a Buffer Layer

Yongju Park,Seunguk Noh,이창희,Donggu Lee,Jun Young Kim 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.2

We analyzed the electrical characteristics of polymer solar cells with different buffer layers between the anode and the active layer. The current-voltage characteristics of the solar cells were measured in the temperature range from 200 K to 350 K at illumination intensities from 1 to 100 mW/cm^2. Devices structure with ITO/buffer layer/poly (3-hexylthiophene) (P3HT): [6,6]-phenyl-C_61-butyric acid methyl ester (PCBM)/LiF/Al - buffer layer being molybdenum oxide (MoO_3) or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) - showed different electronic transport behaviors with temperature change. A strong temperature dependence of short circuit current density of ITO/PEDOT:PSS/P3HT:PCBM/LiF/Al solar cells indicates that the device is limited by the transport properties of the hole injection layer, PEDOT:PSS. A thermally - activated transport of photo - generated charge carriers, influenced by recombination with shallow traps at the interface, describes the variation of the photo current.

Study of the Cesium Carbonate (Cs2CO3) Inter Layer Fabricated by Solution Process on P3HT:PCBM Solar Cells

Park, Yongju,Noh, Seunguk,Lee, Donggu,Kim, Junyoung,Lee, Changhee Informa UK (TaylorFrancis) 2011 MOLECULAR CRYSTALS AND LIQUID CRYSTALS - Vol.538 No.1

IEEE 802.15.4 Protocol 기반 원격 수도검침 System

선용주(Yongju Seon),이호응(Hoeung Lee),박수진(Soojin Park),박현주(Hyunju Park) 한국HCI학회 2008 한국HCI학회 학술대회 Vol.2008 No.2

본 논문은 원격 수도 검침을 위한 수도 사용량의 측정 방법 및 검침 시스템에 적합한 통신 환경을 제안 한다. 기존의 수도 검침 방법은 사람의 손으로 직접 사용량을 확인 및 기록하는 방식으로 수도 검침 값의 오차 및 인력 수급의 문제가 발생 하였다. 본 논문에서는 기존의 문제점을 해결하기 위해 Photo Interrupt Sensor를 이용하여 수도의 사용량을 Data로 전환 하며 원격지에서 Data 값의 확인을 위해 IEEE 802.15.4 Protocol을 활용하여 원격 검침 System에 적합한 무선 통신 환경을 제안 한다. In this paper, we present measurement method of the amount of used piped water and the communications environment for automatic piped water meter reading. The existing piped water meter reading which is carried out by the human in person by monitoring the amount of use and recording make the problem of an error of the figure and being short of staffed to carry out piped water meter reading. To solve the existing problem in this paper, the amount of used piped water is converted into data type by Photo Interrupt Sensor, and IEEE 802.15.4 Protocol is used to confirm the measurement in remote place.

전자기파 지향성 신호 전송(RF-DST) 제어를 위한 적응형 통신 채널 운용 기법

박용주(Yongju PARK),김혜정(Hyejung KIM),임용석(Yongseok LIM) 한국통신학회 2022 한국통신학회 학술대회논문집 Vol.2022 No.2

본 논문에서는 다수개의 통신 채널을 이용하여 웨어러블 디바이스 또는 센서 디바이스로의 지향성 데이터 전송 시에 신호 수신 효율 향상을 위한 최적 자원 할당 스케쥴링에 관하여 연구하였다. 지향성 신호 전송을 할 때, 주변 통신 채널 혼잡도를 계산하여 특정 채널 및 시간의 할당 슬롯(GTS, Guaranteed Time Slot)을 변경하는 기법을 제안하여 혼잡한 통신 채널구간에서의 지향성 신호 전송 시에 발생할 수 있는 통신 오류 등을 최소화하여 ISM 밴드 내의 여타 통신 간의 간섭을 최소화하는 기법을 연구하였다.

The driving force for collaboration networks in environmental engineering in South Korea

Jaebeom Park,Jeryang Park,Yongju Choi 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.2

Here, for the first time, coauthor network and cluster analysis were utilized in the environmental engineering field to identify the driving force for scientific collaboration among individuals and the formation of clusters. Papers published in South Korean domestic environmental engineering journals from 2004 to 2018 were assessed, which enabled identification of unique network characteristics that represent not only the field of study, but also the regional boundaries of the data source. Despite being limited to a single country, the study identifies network characteristics, such as scale invariance, that are typically found in other coauthor networks. Nine clusters were identified, the identity of which could be defined by two variables: research interests and author affiliations. The clusters were divided by the sameness or geographical proximity of author affiliations and problem-oriented research topics. These also describe the inter-cluster relationships, validating the notion that the two variables are the major driving force for collaboration networks. This study substantially advances the understanding of scientific collaboration in the environmental engineering field and can guide future studies, such as the role of coauthor networks in environmental engineering within or outside of regional boundaries and the role of networks in domestic publications in other fields of study.

CORRECTION TO "ON CYCLE DOUBLE COVER CONJECTURE"

Bae, Yongju;Park, Chan-Young KYUNGPOOK UNIVERSITY 1991 Kyungpook mathematical journal Vol.31 No.2

▷초록없음◁

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>

나트륨 실측치와 식품교환표 및 식품성분표를 이용한 추정치의 비교

권용주(Yongju Kwon),이무용(Mooyong Rhee),김지영(Jeeyoung Kim),권광일(Kwangil Kwon),김소진(Sojin Kim),신희준(Heejun Shin),박성수(Seongsoo Park),이은주(Eunju Lee),박혜경(Hyekyung Park),박용순(Yongsoon Park) 한국식품영양과학회 2010 한국식품영양과학회지 Vol.39 No.4

나트륨의 과잉섭취가 고혈압의 주요한 위험요인으로 알려져 있는데, 한국인의 성인 하루 평균 소금 섭취량은 영양섭취기준보다 3배 이상 높다. 본 연구에서는 식품교환표를 이용하여 14일간의 식단을 작성하고 조리된 음식의 나트륨 함량을 실제로 측정한 후 식품교환표와 식품성분표에서 계산된 나트륨 추정치와 비교하여, 각각 방법의 정확성 및 문제점을 파악하고자 하였다. 그 결과를 요약하면 아래와 같다. 하루 식단의 나트륨 함량에서 식품교환표로 계산한 추정치는 실측치와 유의한 차이가 났으나, 식품성분표는 실측치와 유사하였다. 음식별 절대값의 비교에서는 식품교환표로 계산한 나트륨 추정치와 식품성분표로 계산한 나트륨 추정치가 모두 실측치와 유의한 차이가 났다. 음식군별 절대값 비교에서는 양념류의 나트륨 함량이 많은 주요리, 부식, 국물요리에서 상당히 유의한 차이가 났으며, 식품교환표로 계산한 추정치, 식품성분표로 계산한 추정치, 실측치간의 차이가 큰 음식들이 모두 주요리, 부식, 국물요리였다. 이상의 결과에 따르면, 단순히 하루 식단의 나트륨 함량 비교에서 식품교환표에 비해 식품성분표의 나트륨 함량이 더 정확하다고 생각할 수 있지만, 음식별 또는 음식군별로 추정치와 실측치간의 차이를 절대값으로 비교한 결과, 식품교환표와 식품성분표의 나트륨 함량 모두 실측치와 차이가 컸다. 특히 나트륨 과잉 섭취의 주요 원인으로 보고되는 양념류의 차이로 장류, 김치 등의 사용이 많은 한국음식에서 식품교환표와 식품성분표를 이용한 추정치와 실측치의 차이가 컸다. 따라서 고혈압 및 신장질환 환자를 위한 저염식단작성시 식품교환표나 식품성분표를 사용할 때 실제 소금량과의 차이를 고려해야한다. Excessive intake of sodium is known as a risk factor for hypertension, and Korean adults consume sodium 3 times higher than Dietary Reference Intakes (DRIs). The purpose of this study was to evaluate the difference on sodium content between analyzed and estimated by food composition table and food exchange list. Seven days of low salt diet and seven days of high salt diet were prepared, and sodium contents were estimated by food composition table and food exchange list and measured by atomic absorption spectrophotometer. Sodium contents of diet per day estimated by food exchange list significantly differed from analyzed content, but those estimated by food composition table were not. However, when absolute differences from analyzed content were compared by dishes in the low and high salt diet periods, there were significant differences among estimated sodium content by food composition table and food exchange list and analyzed sodium content. The discrepancy between those results was due to that absolute value was used to compare sodium contents of dishes but not to compare sodium contents of days. In addition, main dish, side dish, and soup were significantly different among estimated sodium content by food composition table and food exchange list and analyzed sodium content. Actual sodium contents of Jap-Chae Deop-Bap and Roasted chicken with oyster sauce differed to a great extent from estimated contents by food exchange list and food composition table. In conclusion, actual sodium contents of Korean dishes were significantly different from those estimated by food composition table and food exchange list, and thus these differences in salt content should be considered on planning of low-salt menu for hypertensive patients.

모바일 기기의 무선전력전송 표준화 동향

박용주(Yongju PARK),박찬근(Chan-keun Park) 한국정보과학회 2023 정보과학회지 Vol.41 No.9