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>

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.

조혈모세포이식 환자에서 침습성 진균 감염에 대한 Micafungin의 예방 효과 및 안전성

김시현,이동건,최수미,권재철,박선희,최정현,유진홍,이성은,조병식,김유진,이석,김희제,민창기,조석구,김동욱,이종욱,민우성,박종원 대한감염학회 2010 감염과 화학요법 Vol.42 No.3

Background: Micafungin, a potent inhibitor of 1,3-β-D-glucan synthase, is a novel antifungal agent of the echinocandin class. In vitro study showed that micafungin was effective against Aspergillus species as well as Candida species, but clinical data on the prophylactic efficacy against invasive fungal infections (IFIs) other than candidiasis are still lacking. Materials and Methods: We identified 60 consecutive adult hematopoietic stem cell transplantation (HSCT) recipients who received at least 3 doses of micafungin during neutropenic period. Micafungin was started as an alternative in patients who were intolerant or had adverse events (AEs) to primary prophylactic antifungal agents. We retrospectively reviewed the medical records and analyzed the efficacy and safety of micafungin for prophylaxis against IFIs. Results: The patients either had autologous (n=9) or allogeneic (n=51: 1 syngeneic, 24 sibling, 26 unrelated donor) HSCT. Itraconazole oral solution (n=58) was the most frequently used first line antifungal agent for prophylaxis and was administered for median 11 days. The most frequent cause of switch to micafungin was vomiting (n=42). The duration of neutropenia and micafungin administration was median 13 and 12 days, respectively. A successful outcome was achieved in 45 (75%) patients. Empirical antifungal therapy was initiated in 13 (22%) patients. There were 2 cases (3.3%) of breakthrough fungal infections which comprised a probable invasive pulmonary aspergillosis and a possible invasive fungal sinusitis. There was no case of invasive candidiasis. A total of 53 (88%) patients experienced at least one AE regardless of causality during micafungin administration. The most frequent AEs were hypokalemia, vomiting, diarrhea, and elevated serum aspartate aminotransferase or alanine aminotransferase. Among the aforementioned AEs, only 1 case of diarrhea could be classified as a probable relation with micafungin when causality was assessed. There was no AEs that caused discontinuation of micafungin. Conclusions: Micafungin seems to be a safe and effective agent for prophylaxis of IFIs including aspergillosis as well as candidiasis in HSCT recipients. However, further large, prospective, and randomized comparative studies are warranted for aspergillosis.

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.

고품질 4H-SiC 단결정 성장을 위한 다공성 흑연 판의 역할

이희준,이희태,신희원,박미선,장연숙,이원재,여임규,은태희,김장열,전명철,이시현,김정곤,Lee, Hee-Jun,Lee, Hee-Tae,Shin, Hee-Won,Park, Mi-Seon,Jang, Yeon-Suk,Lee, Won-Jae,Yeo, Im-Gyu,Eun, Tai-Hee,Kim, Jang-Yul,Chun, Myoung-Chul,Lee, Si-Hyun 한국결정성장학회 2015 한국결정성장학회지 Vol.25 No.2

본 연구에서는 PVT법으로 4H-SiC 단결정 성장 시 다공성 흑연판을 사용하여 Si/C 비율이나 온도구배, 물질전달의 향상시킴으로써 고품질의 SiC 단결정 기판 제작을 목적으로 연구를 진행하였다. 연구에 사용된 SiC 소스 물질은 흑연 도가니에 넣어 흑연 단열재로 쌓인 구조로 실험을 하였다. 성장온도는 $2100{\sim}2300^{\circ}C$, 그리고 성장압력은 10~30 Torr의 압력으로 아르곤과 질소 분위기에서 성장시켰다. 종자정은 2인치의 $4^{\circ}$ off-axis 4H-SiC의 C면 (000-1)을 사용하였고 다공성 흑연판은 SiC 소스 물질 위에 삽입하였다. 4H-SiC 결정다형 안정화를 위한 C-rich 조건이나 균일한 온도구배를 만들어주기 위해 다공성 흑연판을 삽입하여 실험을 진행하였다. 일반적인 도가니의 경우, 성장된 wafer에서 6H-, 15R-SiC와 같은 다양한 결정다형이 관찰된 반면에 다공성 흑연판을 삽입한 도가니에서는 4H-SiC만 관찰되었다. 또한 다공성 흑연판을 삽입한 도가니에서 성장된 결정에서 MP나 EP의 낮은 결함밀도를 보였으며 결정성 또한 향상된 것을 학인하였다. The present research is focused on the effect of porous graphite what is influenced on the 4H-SiC crystal growth by PVT method. We expect that it produces more C-rich and a change of temperature gradient for polytype stability of 4H-SiC crystal as adding the porous graphite in the growth cell. The SiC seeds and high purity SiC source materials were placed on opposite side in a sealed graphite crucible which was surrounded by graphite insulator. The growth temperature was around $2100{\sim}2300^{\circ}C$ and the growth pressure was 10~30 Torr of an argon pressure with 5~15 % nitrogen. 2 inch $4^{\circ}$ off-axis 4H-SiC with C-face (000-1) was used as a seed material. The porous graphite plate was inserted on SiC powder source to produce a more C-rich for polytype stability of 4H-SiC crystal and uniform radial temperature gradient. While in case of the conventional crucible, various polytypes such as 6H-, 15R-SiC were observed on SiC wafers, only 4H-SiC polytype was observed on SiC wafers prepared in porous graphite inserted crucible. The defect level such as MP and EP density of SiC crystal grown in the conventional crucible was observed to be higher than that of porous graphite inserted crucible. The better crystal quality of SiC grown using porous graphite plate was also confirmed by rocking curve measurement and Raman spectra analysis.

초등교사의 실과 교수·학습에서 ICT 수행 실태 분석

이시원,김영은 부산교육대학교 교육대학원 2004 논문집 Vol.6 No.-

본 연구자는 실과교과가 정보통신기술을 사용한 수업의 효율성 및 필요성을 인지하고 적극적인 활용을 유도하는 차원에서 정보통신기술이 사용되고 있는 상황을 조사하고, 이들을 토대로 수업 현장에서 ICT 활용수업을 위해 선결되어야 할 과제를 찾아 제시하여, 실과교육의 학습 흥미 촉진과 학업태도의 긍정적 변화와 함께 자기 주도적 학습 능력의 신장을 가져 올 수 있다는 판단에서 본 연구를 수행하였다. 교사들은 현장에서 ICT를 활용 할 때 지침이 될 만한 보다 구체적이고 명확한 ICT 활용 방향을 제시해야 할 것이다. 또한 ICT 활용 수준은 남교사, 여교사 거의 동일한 높은 수준을 나타내고 있으며, 경력면에서 볼 때에는 남교사는 '3~20년' 사이의 교사들이 빈도가 높게 나타났고, 여교사들은 '3년 미만에서 10년 사이'의 교사들이 높은 빈도를 나타내고 있다. 또한 현재 실과 수업에 ICT를 활용하는데 결정적인 장애요인에 대해서는 남교사는 44명(49.44%)으로 '실과 교육용 소프트웨어의 부족'을 들었으며, 여교사는 29명(32.59%)으로 '부족한 수업시간'을 지적하고 있었다. 멀티미디어활용 정도에 대해서는 남교사는 '10~20년'의 경력을 가진 교사 21명(43.8%), 여교사는 '3~10년'의 경력을 가진 교사 27명(37.5%)이 활용 가능 빈도가 가장 높게 나타났다. 마지막으로 교사들은 실과 수업에서 지침이 될만한 보다 구체적이고 명확한 ICT 활용 방향과 물리적 환경의 조성, 교육용 소프트웨어의 개발과 보급, ICT 활용에 대한 연수 및 교육 프로그램의 필요, 실과 교사 분과회의 활성화 등이 원활이 이루어지는 것이 실과교육 현장에서 ICT 활용 수업이 제대로 이루어지기 위한 선결 과제라 할 수 있다. At this point of time that ICT education is getting gradually pervasive on the state leading level, this study sets the goal of analyzing an environment of ICT education in elementary school. This analysis is worth considering elementary school environment, situation and obstacles. Finally based on above results, it could be attributable following studies about basic structure of using ICT. The ICT application in real classroom turns self-directed learning and communication between students themselves, teachers and students and students, ICT and teachers into possibility. In this study, we can find out merits of using ICT through questionnaire. But many teachers are just only showing their own computers and there is only a few self-directed learning in usual classroom condition. Based on this survey, present condition of using ICT in practical art education has problems as following. Firstly there are lack of ICT using tools and poor condition. Secondly the developed software is not enough. Thirdly most teachers don't have knowledge and skills. To solve these problems, teachers could utilize it easier such as guiding them to using the ICT application though teacher training program. Most of all, teachers should recognize these problems and activate this ICT education through continuous study and efforts of self-developing. And for the association with the ICT practical education. We need the politic and economic supports.

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.

活性炭을 利用한 CYANIDE錯陰이온의 吸着特性에 關한 硏究

李時元,金達漢 부산교육대학교 과학교육연구소 1991 科學敎育硏究 Vol.16 No.-

The adsorption characteristics of complex anion compose of cadmium ion and cyanide ion on activated carbon from coconut shell by steam activation has been studied. From the adsortion of cadmium ion on activated carbon in the presence of cyanide ion, it was found that the following results; 1) Cadmium ion was adsorbed on activated carbon in the from of complex anion such as Cd (CN)_4^(2-). 2) The adsorption of cadmium cyanide compex anion was governed primarily by pCN and amount of adsorption increase with increaing cyanide ion : Cd^(2+) ratio. 3) In the case of lower concentration, the adsorption isotherms were found to conform with the Freundlich equation, but the other range was approximately expressed by q = 1.97C/1+0.45C^0.8

한국 프로농구 선수들의 컨디셔닝에 관한 조사 연구

이종희,최시원 경희대학교 체육과학연구소 2000 體育學論文集 Vol.28 No.-

This essay is for studying Korean professional basketball players' conditioning(general, eating habit, having nutrition food, training and taking break - 51 questions) and sports injury(11 questions) with analysis of survey. This survey answered from year 2000 Korean men's pro basketball 10 teams, except foreign hireling 23 players, registered by KBL 124 players. Get this results from 99 players except insincerity and no answered cases. 1.Behavior and preference of meals related with games. 2.The opinion about nutrition, conditioning control arid stamina food. 3.The method of physical and mental training. 4.Body weight change and break activity related with professional career and position. 5.Outbreak injury and the ability to deal with it related with professional career and position

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.