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High-Temperature–Short-Time Annealing Process for High-Performance Large-Area Perovskite Solar Cells
Kim, Minjin,Kim, Gi-Hwan,Oh, Kyoung Suk,Jo, Yimhyun,Yoon, Hyun,Kim, Ka-Hyun,Lee, Heon,Kim, Jin Young,Kim, Dong Suk American Chemical Society 2017 ACS NANO Vol.11 No.6
<P>Organic inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 degrees C for 4 s, the perovskite film with an average domain size of 1 pm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm(2) active area and 18% over a 1 cm(2) active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.</P>
Kim, Yongjung,Im, Myungshin,Jeon, Yiseul,Kim, Minjin,Hyun, Minhee,Kim, Dohyeong,Kim, Jae-Woo,Taak, Yoon Chan,Yoon, Yongmin,Choi, Changsu,Hong, Jueun,Jun, Hyunsung David,Karouzos, Marios,Kim, Duho,Kim, American Astronomical Society 2018 The Astrophysical journal Vol.855 No.2
<P>To date, most of the luminous quasars known at z similar to 6 have been found to be in maximal accretion with the Eddington ratios, lambda(Edd) similar to 1, suggesting enhanced nuclear activities in the early universe. However, this may not be the whole picture of supermassive black hole (SMBH) growth, since previous studies have not reached faint quasars that are more likely to harbor SMBHs with low lambda(Edd). To gain a better understanding of the accretion activities in quasars in the early universe, we obtained a deep near-infrared (NIR) spectrum of a quasar, IMS J220417.92+011144.8 (hereafter IMS J2204+0112), one of the faintest quasars that has been identified at z similar to 6. From the redshifted C IV lambda 1549 emission line in the NIR spectrum, we find that IMS J2204+0112 harbors a SMBH with a solar mass of about a billion and lambda(Edd) similar to 0.1, but with a large uncertainty in both quantities (0.41 dex). IMS J2204+0112 has one of the lowest Eddington ratios among quasars at z similar to 6, but a common value among quasars at z similar to 2. Its low lambda(Edd) can be explained with two scenarios; the SMBH growth from a stellar-mass black hole through short-duration super-Eddington accretion events or from a massive black hole seed (similar to 10(5) M-circle dot) with Eddington-limited accretion. NIR spectra of more faint quasars are needed to better understand the accretion activities of SMBHs at z similar to 6.</P>
DISCOVERY OF A FAINT QUASAR AT <i>z</i> ∼ 6 AND IMPLICATIONS FOR COSMIC REIONIZATION
Kim, Yongjung,Im, Myungshin,Jeon, Yiseul,Kim, Minjin,Choi, Changsu,Hong, Jueun,Hyun, Minhee,Jun, Hyunsung David,Karouzos, Marios,Kim, Dohyeong,Kim, Duho,Kim, Jae-Woo,Kim, Ji Hoon,Lee, Seong-Kook,Pak, IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.813 No.2
<P>Recent studies suggest that faint active galactic nuclei may be responsible for the reionization of the universe. Confirmation of this scenario requires spectroscopic identification of faint quasars (M-1450 > -24 mag) at z greater than or similar to 6, but only a very small number of such quasars have been spectroscopically identified so far. Here, we report the discovery of a faint quasar IMS J220417.92+011144.8 at z similar to 6 in a 12.5 deg(2) region of the SA22 field of the Infrared Medium-deep Survey (IMS). The spectrum of the quasar shows a sharp break at similar to 8443 angstrom, with emission lines redshifted to z = 5.944 +/- 0.002 and rest-frame ultraviolet continuum magnitude M-1450 = -23.59 +/- 0.10 AB mag. The discovery of IMS J220417.92+011144.8 is consistent with the expected number of quasars at z similar to 6 estimated from quasar luminosity functions based on previous observations of spectroscopically identified low-luminosity quasars. This suggests that the number of M-1450 similar to 23 mag quasars at z similar to 6 may not be high enough to fully account for the reionization of the universe. In addition, our study demonstrates that faint quasars in the early universe can be identified effectively with a moderately wide and deep near-infrared survey such as the IMS.</P>
HCC : Clinical Outcome of Surgical Intervention in Hepatocellular Carcinoma
( Minjin Kim ),( Youn Hee Cho ),( Jeong Yeop Song ),( Yun Nah Lee ),( Sae Hwan Lee ),( Soung Won Jeong ),( Sang Gyune Kim ),( Jae Young Jang ),( Young Seok Kim ),( Hong Su Kim ),( Boo Sung Kim ),( Jae 대한간학회 2013 춘·추계 학술대회 (KASL) Vol.2013 No.1
Background: Currently, treatment of hepatocellular carcinoma is diverse and is affected by numorous factors. Although, the mainstay of treatment is surgical resection in patients with adequate liver function. The aim of this study is to evaluate the clinical outcome of surgical resection in hepatocellular carcinoma patients of single center and to define the role of surgical resection. Methods: From March 2002 to January 2013, a total of 163 patients with hepatocellular carcinoma treated with surgical resection at the Soonchunhyang university hospital, Bucheon, Korea were enrolled. We checked the patients` baseline characteristics and BCLC stage, Child-Pugh score, AFP, PIVKA II, laboratory findings. And we investigated the clinical outcome and prognostic factors of these patients. Survival and recurrence rates were evaluated by univariate and multivariate analysis using Cox`s proportional hazards model. Results: 31 patients were excluded because of reasons that expire on operation, O&C, intraoperative RFA. Mean age of 132 patients (male 108, female 24) was 54.58 old (54-76 old). The mean follow up period was 28.5 month (1-120) and the etiology was HBV (108), HCV (8), alcohol (8), others (8). Chronic liver disease patients were 44 (33.3%), liver cirrhosis patients were 88 (66.6%). Child- pugh score was A (80), B (8). C (0) in liver cirrhosis patients. Treatment methods were only operation (87), operation after TACE (36), TACE after operation (4), operation with chemotherapy (4), operation after RFA (1). The mean size of tumor was 4.39 cm (0.8-18 cm). The 2-, 5-, 10year diseas-free survival after surgical resection were 84.6%, 62.6%, 47.2%, respectively. The 2-, 5- and 10-year overall survival after resection were 93%, 87% and 65%. The disease free survival and overall survival according to treatment method were not significantly difference. Multivariated analysis revealed that total bilirubin and portal vein thrombosis were independent prognostic factors affecting disease-free survival (hazard ratio 1.283, 95% CI 1.106 to 1.489, P=0.001 and hazard ratio 4.196, 95% CI 1.706 to 10.322, P=0.002). Also portal vein thrombosis was the independent factor of poor overall survival (hazard ratio 4.434, 95% CI 1.151 to 17.077, P=0.030). In subanalysis, the 2 year overall survival between the group of only operation even though over the size 5 cm (14) and the group of operation after TACE downstaging (8) was not difference (86.7% vs. 85.7%). But the 2 year disease-free survival was difference between two groups (15.6% vs. 31.3%) Conclusions: Hepatectomy whether the combined with other treatment for hepatocellular carcinoma was a great treatment of choice. Portal vein thrombosis was significant prognostic factor of overall survival and disease free survival. Thus, in patients with portal vein thrombosis, special attention is required. In subgroup analysis, more cases of patient was needed to ensure the results.
Discovery of a Faint Quasar at z ~ 6 and Implications for Cosmic Reionization
Yongjung Kim,Myungshin Im,Yiseul Jeon,Minjin Kim,Changsu Choi,Jueun Hong,Minhee Hyun,Hyunsung David Jun,Marios Karouzos,Dohyeong Kim,Duho Kim,Jae-Woo Kim,Ji Hoon Kim,Seong-Kook Lee,Soojong Pak,Won-Kee 한국천문학회 2016 天文學會報 Vol.41 No.1
Are Quasars Growing Fast in the Early Universe?: The Lowest Eddington Ratio Quasar at z~6
Yongjung Kim,Myungshin Im,Yiseul Jeon,Minjin Kim,Minhee Hyun,Dohyeong Kim,Jae-Woo Kim,Yoon Chan Taak,Yongmin Yoon,Changsu Choi,Jueun Hong,Hyunsung David Jun,Marios Karouzos,Duho Kim,Ji Hoon Kim,Seong- 한국천문학회 2017 天文學會報 Vol.42 No.2
Kim, Minjin,Kim, Jihwan,Lee, In-Ho,Han, Woo Hyun,Park, Yun Chang,Kim, Woo Youn,Kim, Bongsoo,Suh, Junho Royal Society of Chemistry 2019 Nanoscale Vol.11 No.12
<P>We report a ternary silver chalcogenide, Ag2Se0.5Te0.5, as a new topological material with improved quantum transport properties. Single-crystalline nanostructures of ternary silver chalcogenides Ag2SexTe1−x are synthesized with a tunable chemical composition <I>via</I> the chemical vapor transport method. Quantum transport studies reveal that Ag2Se0.5Te0.5 nanowires present topological surface states with higher electron mobility and longer mean free path compared to binary Ag-chalcogenides. First-principles calculations also indicate that Ag2Se0.5Te0.5 is a topological insulator, and the observed enhancement in transport properties could imply reduced bulk carrier contribution in the new ternary silver chalcogenide.</P>
Kim, Dohyeong,Im, Myungshin,Canalizo, Gabriela,Kim, Minjin,Kim, Ji Hoon,Woo, Jong-Hak,Taak, Yoon Chan,Kim, Jae-Woo,Lazarova, Mariana American Astronomical Society 2018 The Astrophysical journal Supplement series Vol.238 No.2
<P>We present medium-resolution spectra (R similar to 2000-4000) at 0.4-1.0 mu m and 0.7-2.5 mu m of 16 active galactic nuclei (AGNs) selected with red color in the near-infrared (NIR) of J - K > 2.0 mag at z similar to 0.3. We fit the H beta, H alpha, P beta, and P alpha lines from these spectra to obtain their luminosities and line widths. We derive the E(B - V) color excess values of the NIR-red AGNs using two methods, one based on the line-luminosity ratios and another based on the continuum slopes. The two E(B - V) values agree with each other at rms dispersion similar to 0.249. About half of the NIR-red AGNs have g' - K < 5 magnitude, and we find that these NIR-red, but blue in optical-NIR AGNs, have E(B - V) similar to 0, suggesting that a significant fraction of the NIR color-selected red AGNs are unobscured or only mildly obscured. After correcting for the dust extinction, we estimate the black hole (BH) masses and the bolometric luminosities of the NIR-red AGNs using the Paschen lines to calculate their Eddington ratios (lambda(Edd) ). The median Eddington ratios of nine NIR-red AGNs (log(lambda(Edd) ) similar or equal to -0.654 +/- 0.176) are only mildly higher than those of unobscured type 1 AGNs (log(lambda(Edd)) similar or equal to -0.961 +/- 0.008). Moreover, we find that the M-BH-sigma* relation for three NIR-red AGNs is consistent with that of unobscured type 1 AGNs at similar redshift. These results suggest that the NIR-red color selection alone is not effective at picking up dusty, intermediate-stage AGNs.</P>
Minjin Kim,Huiseon Kim,윤석인,Changkyu Lee,Dogyun Park,Myungsook Kim,JoungDu Shin 한국토양비료학회 2020 한국토양비료학회지 Vol.53 No.3
This experiment was conducted to select an optimum application rate of supplemented biochar pellet as slowrelease fertilizer during tomato cultivation. The supplemented biochar pellet was made through pellet millplaced with a combination (4:6) of biochar and pig manure compost with spraying the N-P-K solution. Thetreatments consisted of control as the recommended application rates of fertilizers and pig manure compost, N40%, N 50% and N 70% of the supplemented biochar pellet application based on the recommendedapplication rates of nitrogen. The highest nitrogen balance was 80.1% in the N 40%, while the highest carbonbalance was 80.8% in the N 50% during tomato cultivation. Mehlich III extractable P2O5 contents in the N50% was highest among the supplemented biochar pellet treatments. The highest stem diameter and plantheight were 10.7 mm and 169.3 cm in the N 70% at 90 days after transplanting. The fresh weight of fruit wasnot significantly different between the control and N 50% treatment. Therefore, it might be considered that anoptimum application rate was N 50% with considering chemical properties of soil and growth responses toapplication of supplemented biochar pellet during tomato cultivation