Gas sensing characteristics of the FET-type gas sensor having inkjet-printed WS₂ sensing layer

Jeong, Yujeong,Shin, Jongmin,Hong, Yoonki,Wu, Meile,Hong, Seongbin,Kwon, Ki Chang,Choi, Seokhoon,Lee, Taehyung,Jang, Ho Won,Lee, Jong-Ho Elsevier 2019 Solid-State Electronics Vol.153 No.-

<P><B>Abstract</B></P> <P>This paper investigates the gas sensing characteristics of the MOSFET-type sensor having an inkjet-printed WS<SUB>2</SUB> sensing layer. The drain current of the gas sensor increases when NO<SUB>2</SUB> gas is injected into the test chamber since NO<SUB>2</SUB> gas is an oxidizing gas that extracts electrons from the sensing layer. On the contrary, the drain current decreases when H<SUB>2</SUB>S gas is injected into the test chamber since H<SUB>2</SUB>S gas is a reducing gas that donates electrons to the sensing layer. In both cases, the change of the drain current increases as the gas concentration increases. However, for other gases (NH<SUB>3</SUB> and CO<SUB>2</SUB>), the gas sensor has a small change of the drain current. The responses of the gas sensor to 10 ppm NO<SUB>2</SUB>, H<SUB>2</SUB>S, NH<SUB>3</SUB>, and CO<SUB>2</SUB> gases are 15.20%, 7.18%, 1.66%, and 3.02%, respectively. Therefore, the WS<SUB>2</SUB> sensor has a high selectivity for NO<SUB>2</SUB> gas among the four target gases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The drain current of the WS<SUB>2</SUB> gas sensor increases when NO<SUB>2</SUB> gas is injected, but decreases when H<SUB>2</SUB>S gas is injected. </LI> <LI> However, for other gases, the gas sensor has a small change of the drain current. </LI> <LI> As a result, the sensor has a high selectivity for NO<SUB>2</SUB> gas. </LI> </UL> </P>

Mechanical Properties and Biocompatibility of Electrospun Poly(ε-caprolactone)/Gelatin Scaffolds Loaded with Cellulose Fiber

Yujeong Jeong(정유정),Deuk Yong Lee(이득용) 한국고분자학회 2022 폴리머 Vol.46 No.6

18 wt% PCL/젤라틴(P/g)에 셀룰로오스 섬유(CF)를 첨가하여 P/g/CF 지지체를 전기방사하고, CF 농도에 따른 인장강도, 투습도, 수분흡수도, 세포독성 및 증식 특성을 조사하였다. CF 농도가 0에서 4 wt%로 증가함에 따라, 점도는 811에서 1121 cP로 증가하였고 섬유 직경은 462에서 869 nm로 증가하였다. 2 wt% CF가 첨가된 P/g/CF에서 4.8±0.8 MPa 최대 인장강도값이 관찰되었지만, CF 농도가 증가함에 따라 강도값은 감소하였다. FTIR 결과, CF농도가 증가함에 따라 지지체 내부의 CF와 젤라틴 간의 수소결합에 의하여 PCL 결정도가 감소하였다. 최적의 투습도와 물 흡수도는 CF농도가 각각 1%와 2%일 때 관찰되었다. 세포생존률과 세포 증식은 CF농도에 상관없이 P/g/CF지지체에서 유사하였다. 실험결과, 상처드레싱재로 적합한 최적의 특성을 가진 지지체는 CF농도가 2 wt%인 P/g/CF에서 관찰되었다. The cellulose fiber (CF)-loaded PCL/gelatin (P/g) scaffolds were electrospun to investigate the effect of CF content on the strength, moisture vapor transmission rate (MVTR), water uptake capacity (WUC), and cytotoxicity of the P/g/CF scaffolds. The fiber diameter gradually increased from 462 to 869 nm with increasing the CF content from 0 to 4 wt% due to the increase in viscosity from 811 to 1121 cP. The strength increased from 2.2±0.3 to 4.8±0.8 MPa as the CF content increased from 0 to 2 wt%, and decreased with additional CF doping. FTIR results revealed that PCL crystallinity decreased with increasing CF content due to H bonds between cellulose and gelatin. The highest MVTR (CF=1 wt%) and WUC (CF=2 wt%) values are observed. Excellent cell viability and proliferation were observed in P/g/CF scaffolds regardless of CF content. It can be concluded that P/g scaffolds loaded with 2% CF are highly suitable as wound dressings.

Selective and potent small-molecule inhibitors of PI3Ks.

Jeong, Yujeong,Kwon, Daeil,Hong, Sungwoo Future Science 2014 Future medicinal chemistry Vol.6 No.7

<P>Class I PI3Ks are composed of four catalytic subunit variants (p110α, p110β, p110δ and p110γ). The PI3K pathway is among the most frequently activated pathways in many diseases, and has emerged as an attractive target for drug development, in particular for the treatment of many human cancers including breast, prostate, ovarian, gastric, colon and hepatocellular cancers. One of the challenges in the discovery of drugs that target kinases is designing small-molecule inhibitors that are sufficiently selective to minimize off-target activity and reduce the risk of potential toxicity. This review explores the current landscape of PI3K-selective inhibitor development and highlights recent advances in achieving selectivity for PI3Ks over other protein kinases, with an emphasis on available structural information.</P>

NO₂ Sensing Characteristics of Si MOSFET Gas Sensor Based on Thickness of WO₃ Sensing Layer

( Yujeong Jeong ),( Seongbin Hong ),( Gyuweon Jung ),( Dongkyu Jang ),( Wonjun Shin ),( Jinwoo Park ),( Seung-ik Han ),( Hyungtak Seo ),( Jong-ho Lee ) 한국센서학회 2020 센서학회지 Vol.29 No.1

This study investigates the nitrogen dioxide (NO₂) sensing characteristics of an Si MOSFET gas sensor with a tungsten trioxide (WO₃) sensing layer deposited using the sputtering method. The Si MOSFET gas sensor consists of a horizontal floating gate (FG) interdigitated with a control gate (CG). The WO₃ sensing layer is deposited on the interdigitated CG-FG of a field effect transistor(FET)- type gas sensor platform. The sensing layer is deposited with different thicknesses of the film ranging from 100 nm to 1 μm by changing the deposition times during the sputtering process. The sensing characteristics of the fabricated gas sensor are measured at different NO₂ concentrations and operating temperatures. The response of the gas sensor increases as the NO₂ concentration and operating temperature increase. However, the gas sensor has an optimal performance at 180℃ considering both response and recovery speed. The response of the gas sensor increases significantly from 24% to 138% as the thickness of the sensing layer increases from 100 nm to 1 μm. The sputtered WO₃ film consists of a dense part and a porous part. As reported in previous work, the area of the porous part of the film increases as the thickness of the film increases. This increased porous part promotes the reaction of the sensing layer with the NO₂ gas. Consequently, the response of the gas sensor increases as the thickness of the sputtered WO₃ film increases.

유아셀프리더십 프로그램이 유아의 자아개념과 조망수용에 미치는 영향

정유정(Jeong Yujeong),김규수(Kim Kyusoo) 한국열린유아교육학회 2009 열린유아교육연구 Vol.14 No.1

본 연구는 유아셀프리더십 프로그램을 적용한 후 유아의 자아개념과 조망수용 증진에 효과가 있는지를 알아보는 데 연구의 목적이 있다. 연구대상은 유치원 만 5세 유아 26명이며, 이들을 실험집단으로 하여 12주 동안 본 연구자가 고안한 유아셀프리더십 프로그램을 실시하였다. 본 연구 결과 본 프로그램에 참여한 실험집단의 유아들은 통제집단의 유아들보다 자아개념과 조망수용 능력에서 모두 통계적으로 유의한 차이가 나타나 본 연구에서 적용 한 유아셀프리더십 프로그램이 유아의 자아개념과 조망수용 능력 증진에 효과가 있음이 밝혀졌다. The purpose of this study is to know how self leadership program that is applied effects on self-concept and perspective-taking. The questions are set up to achieve the purpose of the study. These are below; 1. How does the application of self leadership program effect on young children's self-concept? 2. How does the application of self leadership program effect on perspective taking for young children? A system of contents for the program was composed of three sections which are self-management, natural rewards, and constructive thinking. Each section is composed of eight sub-sections. The procedure to prove effect of the program was done for fourteen weeks from fourth week of march, 2007 to fourth week of June, 2007. It was processed on teachers' training, pre-test, experiment management, and pro-test in order. Results of the study are below; First, the self leadership program for young children effects developing young children's self-concept. Second, the self leadership program for young children effects developing young children's perspective-taking.

영아반 보육교사의 교사민감성에 영향을 미치는 변인 분석

정유정(Yujeong Jeong),김진욱(Jinwook Kim) 한국아동학회 2017 아동학회지 Vol.38 No.2

Objective: This study examined the correlation between variables influencing teacher sensitivity to infant classes in Educare Center teachers and teacher sensitivity, by classifying their personal psychological, socio-psychological, and work environment variables. Furthermore, it aimed to inquire the extent to which these variables influence teacher sensitivity. Methods: The study included 236 Educare Center teachers in charge of infant classes working in infant-caring facilities. Based on stepwise multiple regression analysis, a significance test was conducted for each variable. Results: Firstly, according to the correlations regarding teacher sensitivity to infant classes, for sensitive interaction, emotional stability showed significant positive correlation, while there were significant negative correlations with relationships with the director, colleagues,and parents; mean working hours in other places; and mean daily personal time. For insensitive interaction, there were significant negative correlations with emotional stability and mean daily break time, while there were significant positive correlations with relationships with the director, colleagues, and parents. Secondly, regarding the influences on teacher sensitivity to infant classes, for sensitive interaction, the most significant influences consisted in the relationships with colleagues and parents. On the other hand, for insensitive interaction, the most significant influences were the relationship with colleagues and emotional stability. Conclusion: Reducing interpersonal relationship stress and increasing the emotional stability of Educare Center teachers will increase their sensitivity level. Furthermore, the quality of care will be improved.

유치원의 일과 운영 프로그램에서 종일제와 시간연장제 집단간의 사회적 능력 및 정서지능의 차이

정유정(Jeong yujeong),이연희(Lee yeonhee),김규수(Kim kyusoo) 한국열린유아교육학회 2006 열린유아교육연구 Vol.11 No.6

본 연구는 유치원에서 일과 운영 프로그램에 따라 유아의 사회적 능력과 정서지능에 어떤 차이기 있는지를 알아보는데 연구의 목적을 두었다. 유치원 일과 운영 프로그램에 따라 유아의 사회적 능력과 정서지능 모두 통계적으로 유의미한 차이가 나타났다. 즉 종일반 프로그램에 비해 시간연장제 프로그램 유아들이 사회적 능력과 징서지능 점수가 높았다. 이와 같은 결과를 볼 때 오전부터 독립적으로 편성된 종일제 프로그램이 아닌 연장제반 유아들을 모아서 종일반을 편성 운영하는 종일반 프로그램은 혼합연령집단으로 구성하여 운영하더라도 유아의 사회 정서 능력에 도움을 주지 못한다고 볼 수 있다. e purpose of this study was to find the difference in children's social competence and emotional intelligence according to a daily management program. The study showed statistical differences in both social competence and emotional intelligence. That is, children's social competence and social emotional intelligence in the time extended program increased more than that of children in the full-day program. As we can see in the results, we concluded that the full-day program which is not independently placed in the morning but time extended program does not affect the young children's emotional and social competence development even though managing as a mixed age group.

3D 감시 기능을 갖는 스마트 순찰 드론

정유정(Yujeong Jeong),박재형(Jaeheong Park),이혁진(Hyukjin Lee),최정희(Junghee Choi),이해연(Hae-Yeoun Lee) 한국정보기술학회 2017 Proceedings of KIIT Conference Vol.2017 No.6

Stabilization of UF6 in KAERI : Focused on D-UF6 Sampling

YuJeong Choi,Jongjin Kim,Jeong-Guk Kim,Dae-Seok Hong 한국방사성폐기물학회 2019 한국방사성폐기물학회 학술논문요약집 Vol.2019 No.10

IAEA Concept for Exemption and Clearance

Jeong-Guk Kim,Won Hyuk Jang,MalGoBalGaeBitNaLa Yoo,Yujeong Choi,Jongjin Kim,Seeun Chang,Hee-Seoung Park,Dae-Seok Hong 한국방사성폐기물학회 2019 한국방사성폐기물학회 학술논문요약집 Vol.2019 No.05