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.

實科敎育의 效率化에 關한 硏究 : 國民學校 工業工作 敎育을 中心으로 with reference to the Technical and Craft at the Primary School

李時元 釜山敎育大學 1981 부산교육대학 논문집 Vol.17 No.1

We are preparing and carring out the intensified vocational education as the policy to develop ,man-power in order to adapt to the highly industrialized society. This stydy is investigated to find out the effective method of vocational training education of primary school which is the basic vocational training education. The results of this study are as follows: (1) The taxt book with contents suited the should be edited for the effective vocational training education. (2) The basis of the technical and craft education should be carried out with the same part of art course. (3) The teaching materials must be reorganized. (4) It is a very urgent problem to be improved the teacher's quality. (5) Teacher's positive guidance attitude should be established. (6) In oredr to miprove the class standard, a proper plan should be considered. (7) It is absolutly necessary for the vocational training education to be expanded the school facilities. (8) It is a very urgent problem that we enlighten the parents about the importance of technical and craft education.

纖維狀活性炭을 利用한 生物活性炭의 吸着特性

李時元,孫晋彦,鈴木基之 東亞大學校 大學院 1989 大學院論文集 Vol.14 No.-

Activated carbon fiber(ACF) is an attractive adsorbent since it has a high specific external surface area like powdered activated carbon but is easier to handle since it is easily separated from fluid. Also since fiber radius is as small as about ten microns, intra-fiber diffusion of adsorbate cannot be the rate determining step even in liquid phase absorption and then it might provide a broad field of application in the water treatment area as well as in gas adsorption. When ACF is applied to water treatment, high external surface area provides a good environment for attached growth of bacteria and then an cooperative effect of adsorption and bacterial reaction may be emphasized. The adsorption equilibrium constant were determined from the first moments of the pulses and the second moments shelved that the axial dispersion was a controlling mechanism in broadening of the peaks. It is suggested that for biological activated carbon fiber there is a large contribution of bacterial activity to the adsorption equilibrium constant. Rate determining step in an ACF bed was the longitudinal dispersion of adsorbate in the column. Axial dispersion coefficient,?? was determined to be in proportional to flow rate and Pe=??independent of existence of bacteria, where ?? is the diameter of ACF.

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.

내시경 수술용 혈관집게 개발에 관한 연구

원시태,이정철 서울産業大學校 2005 논문집 Vol.54 No.1

Traditionally, open surgery requires a lot of time for operation and recovery. The comparision with open surgery and endo surgery is getting popular due to economy, time and cosmetics. This technique can reduce operation and recovery time. Scars due to operation are minimized by using small holes. Popular devices for endo surgery have stick shape, and surgeons are watching the inner space of patient through video scope. For that, the vessel holding is essential process, and endo-clip should hold the vessel tightly and stay in the patient body for very long time. The endo clip applier has the stick shape which can operate the endo clip. In order to improve performance of endo clip and applier, new technique and product was developed in this study, which provides 1) vessel clipping method by using elastic force of clip 2) moving method of clip forwarding and 3) counting method for remaining clip.

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 교육과정 운영에 있어 재량활동의 활용 가능성 탐구

이시원,변영기 부산교육대학교 교육대학원 1999 논문집 Vol.1 No.-

A practical course has undergone changes in the curriculum changes. In the 7th curriculum change that will be put in force from 2000, the practical course will not be taught to the 3rd and 4th grade student of the elementary school. The subject will be taught twice a week only to the 5th and 6th grade student. Of course, the subject is taught in the intergration course of the 1st and 2nd grade. The subject is cut off for the 2 years of the 3rd and 4th grade that is very important time because each subjects begins to be seperated from the previous intergration course. If the subject is not taught for the 2 years, we will have discontinuity or difficulty in the education. It will be good for us to find the solution of the problem, the discontinuity of the education. All grade have a discretional class twice a week. If we use the discretional class, we can solve the problem of discontinuity. The purpose of this paper is finding the theoretical ground of using the discretional class to solve the discontinuity. I analized the regulation of running the discretional class. I analized the previous researches that are reported in the model schools. I researched the theories on the pupils development steps. 1. In the research of the theories on the children development steps, I could find that children should have an experience activity, because the activity has a good effect on the children intelligence development. 2. In the way of running the class and the course, I could also find the likeness. The discretional class should be run in the similiar way- a topic research, a joint research in small groups, a study of an intergrated subject - as the practical course. 3. In the analysis of the regulation on the discretional class, I have found some similarities between the 8 meanings of the discretional class and the character of the practical course. 4. In the contents of the discretional class and the practical course, the two have also commonness-a physical labor activity, undertaking of partial responsibility, an environment protection activity, and thrift and saving. If we use the discretional class in the 3rd and 4th grade faithfully, we can prepare for the practical course in the 5th and 6th grade without any problems.

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.

活性炭에 의한 훼놀수용액의 吸着에 관한 速度論的 考察

李時元 釜山敎育大學 1983 부산교육대학 논문집 Vol.19 No.1

Using active carbon particles experiments in adsorption of phenol from aqucous solution were carried out and the adsorption rate and inter-particle distribution of local adsorption equilibrium were measued for two method. A circulation batch method in which the extraparticle concentration is kept coustant and an ordinary batch adsorption method. The date obtaind were compared with the respective numerical solutions of diffusion equations in which diffrent rate-controlling steps were assumed and intrapaticle diffusion kinetics accompanied by a adsorption were studied. 1) The calulated shape of intraparticle distribution of local adsorption equililbrium differ among the rate-controllirng steps assumed but these differences become clearer for the Batch circulation method than for the ordinry Betch adsorption method experiment. 2) The experimental data for the phenol adsorption shows best agreement with results calcutated from the equation assuming simultaneous pore and surface diffusion.