음이온 치환을 이용한 Li_1-xFeO_2-yF_y-Li_xMnO₂ (Mn/(Mn + Fe) = 0.8, 0≤y≤0.15) 양극 활물질의 합성 및 전기화학적 특성

허정배,박금재,이윤성,Heo, J.B.,Park, G.J.,Lee, Y.S. 한국전기화학회 2007 한국전기화학회지 Vol.10 No.4

산소자리에 치환된 불소가 $Li_{1-x}FeO_2Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8) 양극 활물질에 미치는 영향을 고찰하기 위해 다양한 양의 불소를 치환시킨 $Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8, $0.05{\le}y{\le}0.15$) 양극 활물질을 고상법을 이용하여 합성하였다. 불소 미치환 시료 및 치환양이 0.05와 0.1의 시료의 경우, $1-1.5\;{\mu}m$ 크기의 막대 형상 분말 형태에 50-100 nm정도의 작은 구형 입자들이 주위에 분포되어 있는 형태이었다. 반면, 불소 치환양이 0.15인 시료의 경우, 그 모양이 구형으로 변화되어지며 입자가 급격하게 성장하였다. 합성된 시료를 이용하여 제작된 셀들의 충 방전 수행 결과, $Li/Li_{1-x}FeO_{1.9}F_{0.1}-Li_xMnO_2$ 셀이 163 mAh/g의 가장 높은 초기용량을 보였으며 50 싸이클 후에도 95%의 높은 가역 특성을 보였다. 특히, 활물질내의 불소 치환양이 증가할수록 초기 방전용량도 같이 증가하였으나, 불소이온의 치환양이 일정량을 (y>0.1) 넘는 경우에는 산소 자리에 불소이온이 완전하게 치환되지 못하고 불순물로 존재함으로써 전지의 가역특성을 현저하게 저하시키는 요인으로 작용함을 확인하였다. In order to investigate the effect of fluorine ion in the $Li_{1-x}FeO_2Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8) cathode material, it was synthesized $Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8, $0.05{\le}y{\le}0.15$) cathode materials at $350^{\circ}C$ for 10hrs using solid-state method. $Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8, $0.0{\le}y{\le}0.1$ was composed many large needle-like particles of about $1-1.5\;{\mu}m$ and small particles of about 50-100 nm, which were distributed among the larger particles. However, $Li_{1-x}FeO_{1.85}F_{0.15}-Li_xMnO_2$ material showed slightly different particle morphology. The particles of $Li_{1-x}FeO_{1.85}F_{0.15}-Li_xMnO_2$ were suddenly increased and started to be a spherical type of particle shape. $Li/Li_{1-x}FeO_{1.9}F_{0.1}-Li_xMnO_2$ cell showed a high initial discharge capacity of 163 mAh/g and a high cycle retention rate of 95% after 50 cycles. The initial discharge capacity of $Li/Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ ($0.05{\le}y{\le}0.15$) cells increased according to the increase of F content. However, the cycleability of this cell was very rapidly decreased when the substituted fluorine content is over 0.1. We suggested that too large amount of F ion fail to substitute into the $Li_{1-x}FeO_2-Li_xMnO_2$ structure, which resulted in the severe decline of battery performance.

대학생의 인터넷중독 및 스마트폰 중독 정도와 미술 치료 인식에 대한 조사 연구

박혜원,송승윤,윤하영,이경현,이소영,이지원,진예은,최시온,허은서,황다빈,신주현,이인영 이화여자대학교 간호학회 2018 이화간호학회지 Vol.- No.52

Purpose: Investigate the level of Internet and smart phone addiction of college students and difference of their perception on the art therapy. Method: Data was collected using 4 categories of questionnaires. Participants of this study were 383 college students who are currently attending universities located in seoul, Kyung-Ki and Incheon. The Chi-square test, One-way Analysis of Variance, Scheffé test were performed using IBM SPSS Statistics 23.0 Result: First, the study has established that the status of attending universities, grade, people who living with, age affected the level of Internet addiction of college students. In terms of the level of smart phone addiction of college students, the status of attending universities, gender, age were the affective factors. Second, there was a significant difference on the perception of the advantages of the art therapy and the level of acknowledging it, depending on the level of Internet addiction. Finally, depending on the level of smartphone addiction, there was a significant difference in the level of perception of the art therapy, expectation toward the art therapy and the helpfulness of art therapy. The more the participants are close to the addicted level, the more they want to experience the art therapy. Conclusion: These results suggest. First, it is necessary to use bigger group of participants. Second, it is necessary to improve the research methods for college students. Third, nurse should offer holistic care toward the patients regarding their general characteristics by adapting this study. Finally, it is necessary to improve the art therapy programs for the college students who are addicted to the Internet and smartphone and to develop researches proving the effectiveness of these programs.

F-free Y & Cu 전구용액 적용에 의한 YBCO coated conductors의 MOD 공정 개선

김영국,유재무,정국채,고재웅,조윤숙,허은옥,Kim, Y.K.,Yoo, J.M.,Chung, K.C.,Ko, J.W.,Cho, Y.S.,Heo, E.O. 한국초전도학회 2006 Progress in superconductivity Vol.8 No.1

Total Fluorine content in the precursor solution for MOD processing of YBCO coated conductors can be significantly reduced by synthesizing precursor solution with F-free Y & Cu precursor and Barium trifluoroacetate(TFA). It was shown that crack-free and uniform precursor films were formed after calcinations in humidified oxygen atmosphere. Less than 2 hours are required to finish the calcination process, and XRD measurement shows that $BaF_2,\;CuO,\;and\;Y_2O_3$ are major constituent of calcined precursor films. Film thickness after calcination was measured to be ${\sim}2.8$ um by applying slot-die coating method. In particular, addition of Samarium shows critical current of Ic=226 A/cm-w($Jc=3.4\;MA/cm^2$). Also discussed are recent developments in the reel-to-reel processing using F-free Y & Cu precursor solutions. It is shown that uniform and fast processing route to YBCO coated conductor with high Ic can be provided by employing F-free Y & Cu precursor solutions in MOD process.

가족공동체를 떠난 간호대학생들의 대학생활체험

김고은,김유은,김희진,조유진,안주영,허다연,홍서우,차지영,박송이 이화여자대학교 간호학회 2018 이화간호학회지 Vol.- No.52

Purpose: The purpose of this study was to understand and explain the experiences of college life among junior nursing students who live apart from their families. Methods: 14 junior nursing students living apart from their families for at least one semester were recruited through snowballing and convenience sampling. Participants were interviewed individually using open ended questions. Data were collected from July to October in 2017 until data saturation. Interviews were transcribed verbatim and analyzed by using hermeneutic phenomenological method proposed by van Manen. Results: Five essential theme clusters emerged: (1) faced with diverse problems while living apart from family, (2) depend on family when stressed, (3) adapt to college life by being independent and forming self-initiative lifestyle, (4) confront with difficulties once again when adapting to academic curriculum restructured by practicum, (5) pave the way to nursing career and feel proud of overcoming the difficulties independently. Conclusion: Although most participants faced diverse problems in college life, they tried to adapt independently by forming self-initiative lifestyle and overturn the difficulties to positive experiences. In conclusion, the process of living apart from families transformed participants into proactive individuals. Adopting counseling programs could support starting their junior years successfully.

Mole-controlled growth of Y-doped ZnO nanostructures by hydrothermal method

Heo, S.,Lee, Y.,Sharma, S.K.,Lee, S.,Kim, D.Y. Elsevier 2014 Current Applied Physics Vol.14 No.11

We investigated the mole-controlled growth of Y-doped ZnO (YZO) nanostructures by the hydrothermal synthesis techniques. Through controlling the aqueous solution's mole concentration, we could modify the morphological and structural properties of YZO. The shape of YZO becomes a nanometer-sized rod when using a relatively low mole concentration, whereas the morphology is changed to be flat and mosaic when using a relatively high mole concentration. Since the aqueous solution's mole concentration decides the amount of hydroxide, we ascribe the mole-controlled morphological changes to the alteration of chemical potential during the hydrothermal chemical reaction.

Multi-Parameter Maximal Operators Associated with Finite Measures and Arbitrary Sets of Parameters

Heo ,, Y. Springer Science + Business Media 2016 Integral equations and operator theory Vol.86 No.2

<P>In this paper we examine various singular maximal operators, extending the class of operators which have been studied extensively in the past. It extends work that has been done in the one-parameter to the multi-parameter setting. We obtain the -boundedness properties of the multi-parameter maximal operators associated with finite measures and arbitrary sets of parameters by assuming some Fourier decay and a certain geometric condition.</P>

간호대생들의 임상실습 스트레스, 학업적 자기효능감 및 진로정체감에 대한 연구

최유빈,최민지,이은형,이연우,우소연,하희주,허예지,박수현,허미래,이가현 이화여자대학교 간호과학대학 2015 이화간호학회지 Vol.- No.49

Purpose: The purpose of this study was to investigate clinical practice stress, academic self-efficacy, and career identity among undergraduate students in nursing practicum. Method: This study was a descriptive correlational design using the survey method. The study included 267 undergraduate students attending to 5 college in Seoul. The data was gathered from August 2014 to October 2014 and the data were analyzed using IBM SPSS statistics version 22.0 Program with descriptive statistics, t-test, analysis of variance with Scheffe test, and Pearson’s correlation coefficient. Results: Situational characteristics of Clinical Practice Stress(CPP) was significantly different with regards to task difficulties and efficacy self-confidence of academic self-efficacy(ASE) (r= .179, p= .003; r= .166, p= .006). Statistically significant positive relationship was founded between Personal characteristics of CPP and self-confidence of ASE (r= .239, p< .01). External regulators of CPP was significantly different according to self-confidence and task difficulties (r= .175, p= .003; r= .132, p= .028). The self-confidence and efficacy for self-confidence of ASE were a significantly correlated with Career Identity; The Career identity also was a significantly correlated with all sub-categories of CSS scale(r= -0.208, p< 0.01; r= -0.369, p< 0.01; r= -0.153, p< .011) Conclusion: This study showed positive statistical relationships associated with clinical practice stress, academic self-efficacy, and career identity as a preliminary evidence-based study for guiding education in nursing curriculum. Further research should be need for students’ future as a professional nurse.

시뮬레이티드 어닐링을 이용한 젖소의 급이량 산정

허은영,김동원,한병성,김용준,이수영 한국농업기계학회 2002 바이오시스템공학 Vol.27 No.5

자유드로잉 제품과 패드를 설치한 드로잉 제품의 특성

고관영,명노훈,하종성,이창수,최창권,최병용,허기영,김광수,김동수,장종훈,장윤철,김세환,오정민,하민정,박향자 울산과학대학 2000 연구논문집 Vol.27 No.1

본 연구는 자체 제작한 전체 패드가 부착된 드로잉 금형을 이용하여 SUS, 연강, AI, 6:4황동 판재를 드로잉 가공하여 생산된 제품의 특성을 자유드로잉 하여 얻은 제품의 특성과 비교 분석하였다. SUS 판재의 경우 제품에 발생하는 현상은 벽 주름, 구변주름, 수직 파단, 드로잉상처, 이어링이 발생하였으며 길이변화는 펀치어깨부분에서 가장 많이 늘어남을 볼 수 있었고 벽 주름 부분에 있어서 접혀진 부분은 상대적으로 적게 늘어남을 볼 수 있었다. 연강 판재는 SUS 판재에서 보여준 현상을 나타내었으나 SUS 판재에 비해 수직 파단은 적게 일어난 반면 이어링이 더 크게 일어났다. AI 판재의 경우 수직 파단은 일어나지 않았으나 플랜지 주름과 밑면터짐이 발생하였다. 6:4황동의 경우는 전체패드의 AI 판재 드로잉에서와 같이 밑면터짐과 플랜지 주름의 발생이 일어났다.

플랜지가 있는 제품에서 부분패드의 영향에 관한 연구

고관영,허주환,문정효,장재석,김동윤,정민섭,김주찬,박기용,이강연,조명우,이권진,조영호,이효걸,김주호,이경희 울산과학대학 2000 연구논문집 Vol.27 No.1

본 논문에서는 기존의 Motion-JPEG 기반 감시시스템에서 낮은 동영상 압축성능 문제를 해결하기 위한 새로운 동영상 압축기법을 제안하였다. 제안된 방법에서는 현재 프레임의 JPEG 데이터 중 변화된 압축 데이터만이 실시간으로 추출하고 저장된다. 제안된 방법에 의해 저장된 데이터는 기존의 JPEG과는 다른 고유의 포맷을 가지기 때문에, 동영상 데이터는 더욱 안전하게 유지될 수 있다. 실험을 통해, 제안된 동영상 압축기법의 압축률이 기존의 Motion-JPEG 기반 감시시스템에 비해 3배정도 높다는 것을 확인할 수 있었다.