Synthesis of homogeneous and bright deep blue CsPbBr 3 perovskite nanoplatelets with solidified surface for optoelectronic material

Kim Taeyun,Suh Yo‐Han,Kim Kangyong,Kim Hyeonjung,Park Jongnam 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.8

Halide perovskite nanocrystals have easily tunable emissions throughout the visible spectrum, making them an extremely promising material for lightemitting applications. Whereas high quantum yield and long-term colloidal stability have already been achieved for nanocrystals emitting in the red and green spectral range, the blue region currently lags behind with low quantum yields and insufficient colloidal stability. In this study, we present a facile synthetic and postsynthetic approach for obtaining two-dimensional CsPbBr3 nanoplatelets (NPLs) with homogeneous-thickness control of their solidified surface, resulting in sharp photoluminescence and electroluminescence peaks with a deep-blue emission at 465-nm wavelength owing to quantum confinement. The subsequent addition of a solidifying ligand solution seals the surface defects likely stemming from vacancies within a subensemble of weakly emissive NPLs. The overall photoluminescence quantum yield of the blue-emissive colloidal dispersions is consequently enhanced by 65% 2%.

[실험실소개] 명지대학교 마이크로시스템 연구실

송현석(Hyeonseok Song),이강용(KangYong Lee),이정민(Jeongmin Lee),박유나(Yuna Park),정진원(JinWon Jeong),이대영(DaeYoung Lee),김대근(Daegeun KIM),정상국(Sang Kug Chung) 한국가시화정보학회 2018 한국가시화정보학회지 Vol.16 No.3

탄소성 보정계수의 보수성을 완화한 원전기기 피로해석 절차 연구

정재욱(JaeUk Jung),김종성(JongSong Kim),이강용(KangYong Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

Penalty factor(Ke) are need because an elastic analysis cannot explicitly account for strain concentration caused by plasticity effects. It is widely recognized that current Code Ke factor is overly conservative. Because, 1)The present code case only explain loading for mecanical load where significant elastic follow is possible. On the contrary, the thermal stress cannot illustrate with the only Code Ke.2)Generally the nuclear power piping is comprised of the weldment and base matal material such as over-mismatch. Nevertheless, the Code Ke uniformly evaluates the property of the piping. When additionally considering theraml stratification and environmental fatigue,these problems can lead to severe design limitation of lifetime. In this study, we research the influences with over-mismatch factor in a pipe using parametric study basis on adams equation(alternative rules).The results are closely examined and consolidated to introduce an additional term into the Code equation.

SNS 사용자간 다차원 상호관계분석

이경민 ( Kyungmin Lee ),남궁현 ( Hyun Namgoong ),김응희 ( Eung Hee Kim ),이강용 ( Kangyong Lee ),김홍기 ( Hong-gee Kim ) 한국인터넷정보학회 2011 인터넷정보학회논문지 Vol.12 No.2

최근, 온라인상에서 사용자간 관계형성 및 커뮤니케이션을 지원하는 Social Network Service(SNS)들이 주목을 받고 있다. SNS에서 형성되는 사용자 정보와 그들의 활동에 대한 정보는 사용자에 대한 특징적인 정보로서 추천과 같은 외부서비스에서 재사용될 수 있는 유용한 정보로 여겨진다. 기존의 사용자 기본 프로파일 정보를 통한 분석이나, 친밀도 및 유사도를 도출하기 위한 단편적인 분석 방법은 가공된 정보의 활용에 있어 한계점을 지닌다. 본 논문에서는 사용자의 SNS활동들로부터 사용자간 상호영향을 도출하고 다차원 상호관계(Multi-dimension interaction)를 표현 할 수 있는 통합 된 프로파일 모델을 정의하고 이를 도출하기 위한 시스템을 제안한다. 제안된 시스템은 대표적인 SNS인 트위터(Twitter.com)부터 사용자 정보를 수집하여 정보의 재가공을 수행한다. 본 논문의 실험에서는 가공된 정보를 통해 얻을 수 있는, 기존 방식에서는 드러나지 않던 사용자간의 새로운 관계들에 대해 설명한다. 가공된 정보는 특정 사용자의 통합 프로파일로서 컨텐츠 아이템 추천과 같은 외부서비스에서 활용가능 할 것으로 기대된다. Social Network Service(SNS) has become a hot trend as a web service which helps users construct social relationships in the web and enables online communication. The information about user activities and behaviors obtained from the SNSs is expected to be an useful knowledge source for other services such as recommendation services. Most of previous researches on SNS rely on analyzing overall network topology and surveying the activities in a one-dimensional aspect. This paper propose a system for measuring multi-dimensional interaction through the activities in a SNS. The proposed system delivers an unified profile (consisting of profile and multi-dimension interaction) model from user-activities in Twitter.com. At the experimental section, some meaningful perspectives on a set of the unified profiles are described.

HEAT TRANSFER CHARACTERISTICS OF THREE PHASE FLUIDIZED BEDS

KANG, YONG,SUH, IL SOON,KIM, S. D. 충남대학교 공업교육연구소 1986 論文集 Vol.8 No.3

Heat transfer characteristics of two(liquid-gas, liquid-solid)and three(liquid-gas-solid)phase fluidized beds have been studied in a 15.2cm-ID column fitted with an axially mounted cylindrical heater. Effects of gas velocity (0-12 cm/s), liquid velocity (0-16 cm/s), particle size (1.7-8.0 mm) and liquid viscosity (0.001-0.039 Pa·s)on heat transfer coefficient were determined. The heat transfer coefficient increased with fluid velocities and particle size and it decreased with liquid viscosity in two and three phase fluidized beds. The bed porosity at which the maximum heat transfer occurred decreased with particle size but increased with liquid viscosity. The coefficient were correlated in terms of experimental variables. Modified Nusselt number from the present and previous studies has been correlated with modified Prandtl and Reynolds numbers.

FRACTAL ANALYSIS OF PRESSURE FLUCTUATIONS IN A THREE PHASE BUBBLE COLUMN REACTOR OPERATING AT LOW PRESSURE

Kang, Yong,Shim, Jung Seob,Kim, Sang Done,Ko, Myung Han,Kim, Sang Do 한국화학공학회 1996 Korean Journal of Chemical Engineering Vol.13 No.3

Pressure fluctuations in a three phase bubble column reactor operating at relatively low pressure (92 KPa) have been analyzed by adopting the spectral and fractal analyses to get the engineering informations for the on-line control and fault diagnosis of the reactors. The mean value, standard deviation, skewness and kurtosis of the pressure fluctuations have been obtained. The local fractal dimension has been determined from the Pox diagram obtained by means of the rescaled range analysis of the pressure fluctuations based on the fractional Brownian motion. The local fractal dimension of pressure fluctuations has increased and thus the pressure fluctuation signals have become less persistent and irregular, with increases in the gas flow rate reaction temperature, particle size and solid content in the slurry phase. The local fractal dimension has been well correlated in terms of the operating variables.

Purification and Characterization of Cyclodextrin Glucanotransferase from Paenibacillus sp. JK-12

Kang, Yong,Kim, Sung-Koo,Jun, Hong-Ki The Korean Society of Food Science and Nutrition 2002 Preventive Nutrition and Food Science Vol.7 No.3

Extracellular cyclodextrin glucanotransferase (CGTase) from Paenibacillus sp. JK-12 was purified through sev-eral purification steps consisting of ammonium sulfate precipitation and chromatographies on DEAE-sephadex A-50 and Mono QIM HR5/5. The purified CGTase exhibited a single band on SDS-PAGE and was estimated to be approximately 82 kDa. The isoelectric point of the enzyme was 7.2 as determined by isoelectric focusing. The CGTase from Paenibacillus sp. JK-12 had a transglucosylation activity at the C-2 position of L-ascorbic acid. The optimum pH and temperature for the CGTase activity were 8.0 and 5$0^{\circ}C$, respectively. The enzyme activity was stable from pH 6.0 to 9.() and at temperatures up to 55$^{\circ}C$ at pB 8.0, having 80% residual activity. The activity of the CGTase was strongly resistant to metals such as A $g^{+}$ and $Ba^{2+}$ but slightly inhibited by H $g^{+}$, N $i^{2+}$ and $Mg^{2+}$. The enzymeproduced $\alpha$ -cyclodextrin ($\alpha$-CD) and $\beta$-CD as the main products from starch, but not ${\gamma}$-CD.X>-CD.

Production of 2-O-α-D-Glucopyranosyl L-Ascorbic acid by Cylodextrin Glucanotransferase from Paenibacillus sp. JK-12

Kang,Yong,Kim,Sung Koo,Jun,Hong Ki 한국생명과학회 2000 한국생명과학회 학술발표회 Vol.27 No.-

The strain Paenibacillus sp. JK-12 capable of producing high level of extracellular cyclodextrin glucanotransferase[EC 2.4.1.19 ; CGTase] was isolated from soil. The CGTase from Paenibacillus sp. JK-12 produced 2- 0 - α - D-glucopyranosyl L-ascorbic acid(AA-2G) efficiently using amylose as substrate and L-ascorbic acid(AA) as an acceptor. The optimum pH and temperature for the production of CGTase was 8.0 and 37℃, respectively. the optimum carbon, nitrogen and phosphorous sources were dextrin, polypeptone and KH₂P0₄, respectively. For the CGTase from Paenibacillus sp. JK-12, the presence of carbonate salts(such as K₂C0₃, Na₂C0₃, NaHC0₃) in the medium is obligatory. The most preferable carbonate salt was NaHC0₃. It was examined that the effect of metal ion for the cell growth and the production of CGTase. Paenibacillus sp. JK-12 when the presence of Mn^(2+), Fe^(2+), K^+ and Mg^(2+) increased the production of CGTase. On the other hand, Cu^(2+), Zn^(2+) and Cd^(2+) strongly inhibited the prodution of CGTase. The optimum substrate and its ratio (AA:amylose) for the production of AA-2G were amylose and 4:1(w/w), respectively and the most preferable concentration of substrates was 35%.

Gas - Phase Resistance to the Vaporization of Mercuric Halides in High - Temperature Atmospheric Gaseous Condition

Kang, Yong,Seo, Yong Chil,Yang, Hee Chul,Kim, Joon Hyung 한국화학공학회 1996 NICE Vol.14 No.4

Gas-phase resistances to the vaporization of three mercury halides into atmosphere at elevated temperatures were evaluated. Lab-scale vaporization experiments for mercuric bromide, mercuric iodide and mercuric chloride were performed and the results were analyzed to evaluate gas-phase resistance to vaporization of three mercuric halides using the vaporization and condensation model. Overall mass transfer coefficients, k for the sunple mercuric halides, were in the range between 4.8 x 10 fi and 1.6 x 10 g-mole sec cm z arm at the temperatures from the subliming to boiling temperatures and were much smaller than interfacial mass transfer wefficients, k. It was estimated that resistance of pure gasphase mass transfer is much larger than that of the phase transition between condensed and gas phases. It could be therefore said that gas-phase mass transfer coefficients, k2 which could be determined as a function of temperatures.

Particle Flow Behavior in Three - Phase Fluidized Beds

Kang, Yong,Cho, Yong Jun,Ko, Myung Han,Woo, Kwang Jae,Kim, Sang Done 한국화학공학회 1999 Korean Journal of Chemical Engineering Vol.16 No.6

Non-uniform flow behavior of fluidized solid particles in three-phase fluidized beds has been analyzed by adopting the stochastic method. More specifically, pressure fluctuation signals from three-phase fluidized beds (0.152m ID × 2.5m in height) have been analyzed by resorting to fractal and spectral analysis. Effects of gas flow rate (0.01-0.07m/s), liquid flow rate (0.06-0.18m/s) and particle size (0.001-0.006m) on the characteristics of the Hurst exponent, spectral exponent and Shannon entropy of pressure fluctuations have been investigated. The Hurst exponent and spectral exponent of pressure fluctuations attained their local maxima with the variation of liquid flow rate. The Shannon entropy of pressure fluctuation data, however, attained its local minima with the variation of liquid flow rate. The flow transition of fluidized solid particles was detected conveniently by means of the variations of the Hurst exponent, spectral exponent and Shannon entropy of pressure fluctuations in the beds. The flow behavior resulting from multiphase contact in three-phase fluidized beds appeared to be persistent and can be characterized as a higher order deterministic chaos.