3D flexible Si based-composite (Si@Si₃N₄)/CNF electrode with enhanced cyclability and high rate capability for lithium-ion batteries

Kim, Si-Jin,Kim, Min-Cheol,Han, Sang-Beom,Lee, Gyu-Ho,Choe, Hui-Seon,Kwak, Da-Hee,Choi, Sun-Yong,Son, Byung-Goo,Shin, Myoung-Sun,Park, Kyung-Won Elsevier 2016 Nano energy Vol.27 No.-

<P><B>Abstract</B></P> <P>Despite extremely high capacity of Si-based anodes in lithium-ion batteries (LIB), Si-based materials have shown a structural collapse caused by a volumetric expansion/contraction during the cycling process. The conventional electrode structure, which consists of active materials, a current collector, a conducting agent, and a binder, actually showed a low loading of active material due to the other heavy components. In this study, we prepared a 3D flexible Si-composite electrode consisting of core (Si)-shell (Si<SUB>3</SUB>N<SUB>4</SUB>) NPs (Si@Si<SUB>3</SUB>N<SUB>4</SUB>) and carbon nanofibers (denoted as Si-composite/CNF). The Si-composite/CNF was directly utilized as an anode in the absence of the other components was electrochemically evaluated using a coin-type cell. The Si-composite/CNF showed a high capacity of 665mAhg<SUP>−1</SUP> at a fairly high current density of 10Ag<SUP>−1</SUP> and an extremely low capacity loss for 2000 cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We prepared Si-composite/CNF exhibits a 3D flexible Si-composite electrode. </LI> <LI> The electrode consists of core (Si)-shell (Si<SUB>3</SUB>N<SUB>4</SUB>) NPs (Si@Si<SUB>3</SUB>N<SUB>4</SUB>) and carbon nanofibers. </LI> <LI> The Si-composite/CNF was directly utilized as an anode. </LI> <LI> Si-composite /CNF exhibited high specific capacity and improved high rate cycling performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

SiC 단결정의 TSSG 공정을 위한 전이금속 특성 연구

이승준,유용재,정성민,배시영,이원재,신윤지,Lee, Seung-June,Yoo, Yong-Jae,Jeong, Seong-Min,Bae, Si-Young,Lee, Won-Jae,Shin, Yun-Ji 한국결정성장학회 2022 한국결정성장학회지 Vol.32 No.2

본 연구에서는 SiC 단결정의 TSSG 공정중 결정 품질을 저하시키지 않으면서도 의도하지 않은 질소 도핑(N-UID)을 쉽게 제어하기 위해 지금까지 Co 또는 Sc 전이금속을 첨가한 신규 용융조성을 제안한다. Co 또는 Sc의 특성을 파악하기 위해 Ar 분위기에서 1900℃ 온도에서 약 2시간 동안 열처리 실험을 수행했다. 용융조성은 Si-Ti 10 at% 또는 Si-Cr 30 at%를 비롯하여, 탄소 용해도에 효과적이라고 알려진 Co 또는 Sc을 각각 3 at% 첨가하였다. 열처리 후 도가니 단면을 가공하여 도가니-용융물 계면에서 발생한 Si-C 반응층을 관찰하고, 탄소황분석을 통해 조성에 따른 탄소 용해도를 간접적으로 분석하였다. 그 결과, Si-Sc 기반 용융조성이 TSSG 공정에 적합한 특성을 갖는 Si-C반응층을 형성하고 있었다. 또한 탄소황분석 결과에서도 Cr 다음으로 높은 탄소량이 갖는 것으로 분석되었다. Sc는 Cr에 비해 질소와의 반응성이 낮은 이점을 가지므로 TSSG 공정에 Si-Sc 용융조성을 적용하면, 본 연구에서 의도한 대로 SiC 단결정 성장속도와 질소 UID를 모두 제어할 수 있는 것으로 고려된다.

生涯敎育에 있어서 技術敎育의 立地

李時元 釜山敎育大學 1992 부산교육대학 논문집 Vol.28 No.1

This study aims to research the direction of development in the location of technical education for lifelong education. The summary of researching the direction of development the lifelong education which entered into this reason by aged men will be in need of the special introduction of skill, is followed. (a) Balance of skill (b) Permanence in skill (c) Idea of lifelong education (d) Elevate for men's mind (e) The view-point at technical on college training (f) Education of oldman, etc.

이온交換樹脂吸着劑의 製造 및 吸着特性

李時元 釜山敎育大學 1988 부산교육대학 논문집 Vol.24 No.1

β-Pinene was polymerized with Furfural in different proportions in the presence of anhydrous zinc chloride. It was established that anhydrous zinc chloride was found to be suitable for preparation of β-Pinece-Furfural (1:1) polymer and hence used for introducing functional groups. Two type of adsorbents were prepared from β-Pinene-Furfural polymer. A Phosphonic acid type adsorbent was prepared by phosphorylation of the polymer with phosphorous trichloride in the presence of anhydrous aluminum chloride followed by hydrolysis. A strongly acidic cation exchange resin was also prepared by sulfonation of the polymer at 60°C with 95% sulfuric acid for 6 hours. The matrix polymer and adsorbents synthesized were identified by means of infrared spectrophotometer. The adsorption of metal ion such as Fe (Ⅲ), Cr (Ⅲ), Cu (Ⅱ), Ni (Ⅱ), Zn (Ⅱ), Co (Ⅱ), on these adsorbents were discussed. And the distribution coefficients in hydrochloric acid solution and the elution behavior of several heavy metal ions were also discussed.

1T DRAM with Raised SiGe Quantum Well for Sensing Margin Improvement

Si-Won Lee,Seongjae Cho,Il Hwan Cho,Garam Kim 대한전자공학회 2023 Journal of semiconductor technology and science Vol.23 No.1

In this paper, a novel one-transistor dynamic random-access memory (1T DRAM) with a raised SiGe quantum well (QW) under one gate in the double-gate (DG) structure is proposed. The proposed structure can improve the poor performance of the retention time and sensing margin which is the problem of the conventional 1T DRAM. In write operation, the performance is improved through the band to band tunneling (BTBT) between body and drain and through valence band offset between SiGe and Si. Also by utilizing the physical barrier of oxide, read “1” retention time can be increased. The fabrication process is also proposed.

실과 교육을 위한 시설ㆍ설비의 개선 방안

이시원 韓國實科敎育硏究學會 2001 實科敎育硏究 Vol.7 No.1

The purpose of this study was to get data for managing the laboratory efficiently which is operated by a kind of open-system on a practical arts education in the elementary school. The practical arts lab. is designed to be divided into three spaces; space for performing main activity, space for cultivating plants, space for communicating information. In order to heighten the effect, of practical arts study open-system typed lab. model is adopted because it enables pupils to practice what they learned in all the areas.1

GIS를 이용한 산불발생위험지역 구분

이시영,안상현,원명수,이명보,임태규,신영철 한국지리정보학회 2004 한국지리정보학회지 Vol.7 No.2

산불로 인한 재해를 미연에 방지하고 피해를 저감하기 위해서는 산불발생위험지역을 사전에 파악하여 예방대책을 세울 필요가 있다. 따라서 본 연구에서는 산불발생인자에 따른 산불발생위험지역을 구분하고자 겸상북도 의성군에서 발생한 산불피해지역에 대하여 임상, 지형 등에 대하여 조사하였다. 조사된 요인들 간 독립성 유무를 상관분석을 이용하여 산불발생과 관련 있는 7개의 주제도를 선정하였으며, 선정된 주제도를 조건부확률과 지리정보시스템을 이용하여 산불발생확률을 계산하였다. 계산된 산불발생확률을 20개 등급으로 지수화하여 산불발생위험지역을 구분하였다. In order to decrease the area damaged by forest fires and to prevent the occurrence of forest fires, we are making an effort to improve prevention measures for forest fires. The objective of this study is to classify hazard regions where forest fires occur based on the factors that contribute to the occurrence of forest fires. Forest fire sites in the Uiseong-gun, Gyeongsangbuk-do were surveyed according to the factors of forest type and topographic characteristics where the forest fires occurred. We used a correlation analysis to determine the forest fire occurrence factors and a conditional probability analysis and GIS to determine a forest fire danger index. The resulting forest fire danger index was used in the classification of forest fire occurrence risk regions.

實科學習 評價方法 改善에 關한 硏究 : 技能面을 中心으로 With reference to skill domain

李時元,鄭模根 釜山敎育大學 1985 부산교육대학 논문집 Vol.21 No.1

The purpose of this study was to analyze the problems of skill evelution coming out in the course of the evelution of practical arts traning ot the scene of primary school and to contrive the models of proper evelution methods as to the skill evelution on the ground of the problems. The investigaton method used for this study was means of questionaires. The results obtaineP are summarized as fallows; 1. The result of sending the questionaire to the teachers who have a lot of experience to do practical arts evelution; a) absolute satisfied techers are 4.8% b) somewhat satisfied ones are 47.1% c) suspicious ones are 4.2% 2. The items which teachers feel difficults in pratical arts evelution; a) the obscurity of evelution criterion establishment is 38.6% b) the lack of proper evelution models is 28% 3. Skill evelution measuring instruments; a) seef-made ones are 36% b) others-made ones are 60.3% 4. When the reason why teachers don't make skill evelutions is asked, the result is as follows; a) the reason for the few chances of practical arts training is 43.2% b) the reason for the lack of proper evelution models is 29.5% In the hight of the above problems, if practical arts training is to be developed as a main role in class in order to meet the educational purpose, an urgent problem is supposed to develop a rational evelution criterion establishment and a proper evelution model, which are essential to pratial arts training evelution.

固定化 微生物에 依한 Alcohol 醱酵의 速度論的 考察

李時元 釜山敎育大學 1986 부산교육대학 논문집 Vol.22 No.1

Continuous reactors containing immobilized cells of Z-mobilis were utilized for the continous production of ethanol from glucose. The values of the diffusion coefficient of glucose were calculated by means of equation of Crank. Effect of diffusion resistance on reaction by using an immobilized Z-mobilis entrapped by sodium alginate gel was studied. Over all reaction rates of ethanol production by immobilized cells were measured. Diffusion seemed to be restricted by cells. Intraparticle effective diffusivity of substrate depends upon cell density.

절수에 의한 mongolian gerbil의 체중 변화에 관한 연구

이경열,송치원,김무강,조성환,류시윤,김상근,박배근 충남대학교 수의과대학 동물의과학연구소 1996 動物醫科學硏究誌 Vol.4 No.-

Recently, the mongolian gerbils have been used in neurology and the study of water metabolism because of their easy onset of epileptic seizure and typical resistance to water deprivation. The sebaceous glands which are under the control of the gonadal hrmones are differently developed from the other laboratory animals. However the physiological data on the changes of body weight following water deprivation in mongolian gerbils is not available until now. In order to investigate the effect of the water deprivation on the body weight, the animals were deprived of water for 15 days. The body weights were measured daily by the torsion balance. The mean, the standard deviation, the standard error and the coefficient of variance of the body weights were calculated. The correlation was examined. The potential regression equation was y = 61.5458 - 2.0533 * x + 0.0487 * x^2. The regression coefficient was 0.993. The results obtained were as follows : 1. The body weights of the mongolian gerbils were continuously decrased from the 1st day to the 15th day after the water deprivation. 2. The mean body weight on the water deprivation was 63.0±7.00g and that at the 15th day was 41.4 ± 5.42g. 3. The coefficients of the variance showed the highest (13.09) at the 15th day and the lowest (10.10) at the 10th day. the coefficients of the variance kept decreasing until the 10th day and thereafter gradually increased until the 15th day. 4. The changing rate of the body weight kept continuously decreasing from the 1st day to the 15th day showing the daily loss of 1.0 - 3.3%. 5.The deviations (M - QBW) between the measured values (m) and the theorical values (QBW) using the regression equation showed the highest (1.494) at the 1st day and the lowest (0.053) at the 13th day. 6. The sum of the devitions was 0.179 and that of the deviation square was 1.15. The sum of the deviation rates between the mesaured body weights and the theorical ones was 0.484. 7. The daily body weight loss showed the highest at the 1st day by 2.053g and the lowest at the 15th day by 0.591g. 8. The specific body weight changing rates which were the rate of the body weight changing velocity to the changed body weight were decreased from 0.033% at the 1st day to 0.014% at the 15th day.