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>

Wire Saw 슬러리로부터 Si, SiC 분리 및 제올라이트 합성에 대한 연구

한승열,이종대,박노국,이태진,류시옥 한국공업화학회 2004 응용화학 Vol.8 No.1

This study was focused on the separation of Si and from Wire Saw Slurry in Wire Saw Slicing process and synthesis of zeolite by mixing with water glass obtained from its process and Alumina. In order to separate Si and SiC from Wire Saw Slurry, Alkai disslution was used and then Na₂O showed superior dissoluble property of Si. At this time, SiC was separated as powder from Alkali apueous solution. Si was dissolved as a liquid in Alkali aqueous solution. After removing SiC powder, the powder formed was obtained from drying. Alkali aqueous solution and then it was the water glass (Na₂SiO₃)confirmed by XRD analysis. Water glass (Na₂SiO₃) and Alumina mixed with pure water made as a synthesis of zeolite through the crystallization by aging and hydrothermal reaction. The manufactured zeolite was Sodium Aluminum Silicate Hydrate confirmed by XRD analysis.

Wire Saw 슬러리로부터 Si와 SiC의 선택적 회수

한승열,이종대,전진혁,박노국,이태진,류시옥 嶺南大學校 工業技術硏究所 2004 工業技術硏究所論文集 Vol.32 No.1

This study was focused on the recovery of Si and SiC from wire saw slurry in wire saw slicing process. In order to separate Si and SiC from wire saw slurry, alkali dissolution method was used and then Na₂O showed superior dissolution property of Si. At this time, SiC was separated as powder from alkali aqueous solution. Si was dissolved as a liquid in alkali aqueous solution. After removing SiC powder, the powder was obtained by drying alkali aqueous solution and then it's XRD analysis showed that it was the water glass (Na₂SiO₃).

Expansion Analysis of Subsea Pipe-In-Pipe Due to High Temperature and High Pressure Product

HAN­SUK CHOI(최한석),HYUN-MO SON(손현모),SI-YOUNG KIM(김시영) 한국해양공학회 2002 韓國海洋工學會誌 Vol.16 No.5

본 논문은 고온 고압의 유류 수송용 이중배관의 팽창에 대한 해석적 방법에 대한 결과고찰과 해석, 그리고 설계시 응용이 가능한 현상에 대해 논하였다. 고온의 유류수송시 온도를 유지할 목적으로 내부의 수송 배관과 외부의 케이싱 배관사이에 절연체가 쓰여진다. 이런 이중배관의 팽창을 조사할 수 있는 간단한 해석적 방법이 개발되었다. 본 논문에서는 온도의 분포, 압력, 토질의 저항, 수송배관과 케이싱배관과의 상호작용 등이 고려되어졌으며, 이 해석적 방법은 심해의 이중배관 해석에 적합하게 개발되었다. 계산의 결과 분석에서 고온의 영향이 고압보다 현저한 것이 밝혀졌다.

男女大學生의 結婚觀(II) : 그들의 意識과 行動을 中心으로

柳時中,韓有常 경북대학교 사회과학대학 1984 社會科學 Vol.3 No.-

The purpose of this study is to examine some attitudes that college students assume toward marriage. In the article "College Students' Attitudes Toward Marriage: Their Spouse Selection Routes and Criteria" (Yu and Han, 1984) to appear in Oriental Culture Research, vol.11 (1984), the authors have advanced an analysis of prevailing spouse selection routes and criteria. As a sequel to Yu and Han (1984), this study tries to investigate problems concerning premarital sexual intercourse and postnuptial life planning that enter into the spouse selection process. Since Korea began to modernize itself, diverse changes have occurred in our society. Particularly, the Western free-sex trend seems to have continued its infiltration to such an extent that college students in Korea are seriously affected by the mood. Upon investigation, however, it has been found out that most college students still impart a high value to premarital virginity, and that only a small number of students are actually experiencing premarital coitus. Questionaires about postnuptial life planning were employed to analyze the attitudes that college students take toward independent family life, residence problem, double-income family, and family planning. The result was that the nuclear and double-income family was more favored by female students. It also turned out that, regardless of sex, most college students hoped to find their postnuptial residence in cities and to have fewer children than before.

Hidden Markov Chain 모형과 이변량 코플라함수를 이용한 가뭄빈도분석

전시영,김용탁,권현한,Chun, Si-Young,Kim, Yong-Tak,Kwon, Hyun-Han 한국수자원학회 2015 한국수자원학회논문집 Vol.48 No.12

본 연구에서는 가뭄의 특성분석에 유리하며, 확률론적 접근이 가능한 은닉 마코프 모델(HMM) 기반의 가뭄 분석 기법을 적용하였다. HMM 기반의 가뭄의 심도뿐만 아니라 지속시간을 동시에 평가할 수 있도록 코플라 함수 기반의 이변량 가뭄빈도해석 기법을 도입하여 우리나라의 2015년 가뭄 빈도를 평가하였다. 가뭄빈도분석 결과 최근 40년 자료를 기준으로 영동지방에 비해 영서지방이 전체적으로 가뭄이 발생할 경우 가뭄의 심도가 큰 것으로 평가되었다. 심한가뭄의 발생 비율의 경우에 철원의 경우 10%를 상회하는 등 임진강 유역에서 상대적으로 심한가뭄의 발생비율이 크다는 것을 확인할 수 있었다. 한강유역 일부지점에서는 2014/2015년의 가뭄 지속기간 및 심도의 결합재현기간이 1,000년이 넘는 가뭄이 발생하고 있는 것으로 평가되었다. 특히 북한강 및 임진강 유역에 심한 가뭄이 발생하고 있으며 전반적으로 100년 이상의 기왕최대가뭄을 나타내고 있는 것으로 판단되었다. This study applied a probabilistic-based hidden Markov model (HMM) to better characterize drought patterns. In addition, a copula-based bivariate drought frequency analysis was employed to further investigate return periods of the current drought condition in year 2015. The obtained results revealed that western Kangwon area was generally more vulnerable to drought risk than eastern Kangwon area using the 40-year data. Imjin-river watershed including Cheorwon area was the most vulnerable area in terms of severe drought events. Four stations in Han-river watershed showed a joint return period exceeding 1,000 years associated with the drought duration and severity in 2014-2015. Especially, current drought status in Northern Han-river and Imjin-river watershed is most severe drought exceeding 100-year return period.

한강하구지역에서 월동하는 재두루미(Grus vipio)의 개체군 감소

이화수(Hwa-Su Lee),신주열(Ju-Yeol Shin),이시완(Si-Wan Lee),강태한(Tae-Han Kang),윤순영(Soon-Young Yoon),김정수(Jungsoo Kim) 한국조류학회II 2012 한국조류학회지 Vol.19 No.4

김포시와 고양시 일대의 한강하구 지역은 우리나라에서 재두루미의 가장 중요한 월동지 및 중간기착지로 알려져 있지만, 이 지역의 조류 서식환경은 심각한 개발압력과 인간의 간섭으로 인해 지속적으로 나빠지고 있다. 따라서 본 연구에서는 2007-2008년과 2011-2012년의 월동시기에 본 지역에 도래하는 재두루미를 대상으로 월동 개체군 크기 변화와 월동지역 내에서 과거와 현재의 취식지역 이용 현황 등을 조사하여 개발행위가 이들의 서식에 미치는 영향을 확인하였다. 본 지역에서 월동하는 재두루미 개체군은 평균 124.9개체(2007-2008년)에서 59.0개체(2011-2012년)로 감소하였으며, 주요 취식지역에서 확인된 개체수는 평균 77.7개체에서 24.1개체로 감소하여 월동개체군의 감소폭에 비해 주요 취식지역의 이용 개체수의 감소폭이 더 크게 나타났다. 유형별 분석에서는 가족군에 비해 무리군의 개체수가 많이 감소한 것으로 나타났으나, 홍도평 지역의 가족군 이용 개체수는 변화가 나타나지 않았다(Mann-Whitney test. Z=-0.26, p=0.979). 그리고 과거 다수의 재두루미가 주요 취식지역으로 이용하였던 송포동과 평동지역은 2012-2013년 조사에서는 거의 이용하지 않는 것으로 나타났다. 이는 위 지역의 개발행위(예: 제 2자유로 건설 등)와 깊은 연관성이 있는 것으로 생각된다. Han-river estuary in Gimpo and Goyang city is well known as one of the most important wintering and stopover sites for migrating White-naped Crane (Grus vipio) in Korea. Nowadays, habitat quality of this area is getting worse due to serious development pressure and high human disturbances. So, we wanted to know whether development actions affected total wintering population change in Han-river estuary and feeding group pattern of White-naped Crane in main feeding habitats between the 2007-2008 and 2011-2012 wintering period. Average wintering population was decreased 124.9 to 59.0 and population of main feeding site also decreased 77.7 to 24.1. But decrease rate of main feeding site population was higher than total wintering population. Non-family feeding population was more decrease than family feeding population in the flock type analysis. But family feeding population of Hongdopyong was maintained from past and present (Mann-Whitney test. Z=-0.26, p=0.979). However, almost all White-naped Crane din not use both feeding sites, Pyong-dong and Songpo-dong, where were deteriorated habitat quality by human act.

A Study on Improvement and Degradation of Si/SiO₂ Interface Property for Gate Oxide with TiN Metal Gate

Lee, Byung-Hyun,Kim, Yong-Il,Kim, Bong-Soo,Woo, Dong-Soo,Park, Yong-Jik,Park, Dong-Gun,Lee, Si-Hyung,Rho, Yong-Han The Korean Institute of Electrical and Electronic 2008 Transactions on Electrical and Electronic Material Vol.9 No.1

In this study, we investigated effects of hydrogen annealing (HA) and plasma nitridation (PN) applied in order to improve $Si/SiO_2$ interface characteristics of TiN metal gate. In result, HA and PN showed a positive effect decreasing number of interface state $(N_{it})$ respectively. After FN stress for verifying reliability, however, we identified rapid increase of $N_{it}$ for TiN gate with HA, which is attributed to hydrogen related to a change of $Si/SiO_2$ interface characteristic. In contrast to HA, PN showed an improved Nit and gate oxide leakage characteristic due to several possible effects, such as blocking of Chlorine (Cl) diffusion and prevention of thermal reaction between TiN and $SiO_2$.

학생선수용 체육진로흥미검사지의 다집단 동일성 검증

권형일(Kwon, Hyung-Il),한시완(Han, Si-Wan) 한국체육과학회 2017 한국체육과학회지 Vol.26 No.3

Career should be understood as a process of continuous changes and development, rather than a fixed choice at a certain time (Super, 1990). Career guidance for student-athletes should reflect cultural specificity that both study and exercise are required at the same time, and should be conducted systematically by utilizing proper tools suitable for each development stage. The purpose of this study is to test if sport career interest inventory (SCII) for student-athletes, which was developed in the previous studies (Kwon Hyung-il, Bang Shin-woong, Han Si-wan, Yoo Jeong-ae, 2016), can be used in common by a group, that is, by school and class. For the study, 342 subjects (172 high school students and 170 university students) received multi-group construct invariance test of SCII. As a result, configural invariance and measurement equivalence were tested. These results provide supportive materials for construct invariance of SCII and can be utilized for comparative study by school and class to explore career according to the change in grade of the students.

三天池의 環境과 微生物의 多樣性

한상국,이종운,배소현,장무웅,김시균 嶺南大學校 環境問題硏究所 1993 環境硏究 Vol.13 No.1

경상북도 경산시에 위치하고 있는 삼천지에 대한 환경요인 및 미생물상에 관하여 조사하였다. 삼천지 수계의 환경요인 분석결과, 그 평균값은 기온이 25.8℃, pH6.77, 경도 117.94mg/ℓ, 부유물질 4.5mg/ℓ, 용존산소량 3.3mg/ℓ, 생물학적 산소요구량 6.6mg/ℓ, 화학적 산쇼요구량 7.2㎎/ℓ, 염소이온 17.56㎎/ℓ, 황산이온 7.14㎎/ℓ로 나타났고, 중금속류는 Mn과 Zn만이 소량 검출되었으나 전반적인 오염도가 높아 수질환경 기준 IV급수에 해당하였다. 총 세균수는 3.32-8.85×?? No. inds/㎖의 분포를 나타냈고, 식물플랑크톤의 종구성은 규조류 33종, 녹조류 26종, 남조류 8종, 유글레나 13종, 와편모조류 6종 등 86종이 확인되었다. 규조류중 띠돌말과에 속하는 Fragilaria capucina, Synedra acus, S. familiaris 가 우점종이였다. Environmental factors and microflora of Samchun-impoundment in Kyongsan, Kyongpook were studied. Average data of environmental factors analysis are as followings : air temperature 25.8℃, pH 6.77, total hardness 117.94mg/ℓ, SS 4.5mg/ℓ, DO 3.3mg/ℓ, BOD 6.6mg/ℓ, COD 7.2mg/ℓ, ?? 17.56mg/ℓ, ?? 7.14mg/ℓ, Mn 0.05mg/ℓ, Zn 0.04mg/ℓ. Total bacteria in 4 site were 3.32×?? No. inds/㎖. Distribution and species of phytoplankton and zooplankton were 86 species including 33 species of bacillariophyceae, 26 of chlorophyta, 8 of cyanophyceae, 13 of euglenaceae, 6 of dinophyceae. Fragilaria capucina, Synedra acus, S. familiaris were dominant species.