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Assembly of charged aerosols on non-conducting substrates via ion-assisted aerosol lithography （IAAL）

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Particuology 2017年第4期15卷 17-23页

作者： Seunghyon Kang Wooik Jung dae Seong Kim Sei Jin Park Mansoo choi School of Mechanical and Aerospace Engineering Seoul National University Seou 108826 Republic of Korea Global Frontier Center for Multiscale Energy Systems Seoul National University Seou108826 Republic of Korea

The development of ion-assisted aerosol lithography （IAAL） has enabled fabrication of complex three- dimensional nanoparticle （NP） structures on conducting substrates. In this work, the applicability of the IAAL technique was investigated on non-conducting substrates. The NP structure growth process on a non-conducting substrate was found to self-terminate and the structures subsequently repel incoming charged NPs and scatter them away. Electric field calculations supported the experimental findings and confirmed that the electric field distortions owing to charge build-up within the structures prevented additional NP deposition thereon. To regulate the charge build-up without compromising the number of NPs available for assembly, a corona discharger and an ion trap were implemented. By varying the number of ions available in the assembly process, an optimum level of ion injection was found that allowed for a prolonged （〉120 rain） assembly of NP structures on non-conducting substrates without the unwanted scattering of NPs.

关键词： Nanoparticle assembly Non-conducting substrate Ion-assisted aerosol lithography Ion trap

Granular cell tumor of colon:Report of a case and review of literature

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World Journal of Gastroenterology 2004年第16期10卷 2452-2454页

作者： dae-KyungSohn Hyo-Seongchoi Yeon-SooChang Jin-MyeongHuh dae-HyunKim dae-YongKim Young-HoonKim hee-JinChang Kyung-HaeJung Seung-YongJeong Research Institute and Hospital National Cancer CenterGoyangGyeonggi 411-769Korea

Granular cell tumor (GCT) is uncommon in the colon and *** we report a case of GCT in the transverse colon.A 48-year-old male patient underwent a screening colonoscopy.A yellowish sessile lesion,about 4 mm in diameter,was found in the transverse *** endoscopic snare resection was performed without complication. Histological examination revealed the tumor consisted of plump neoplastic cells with abundant granular eosinophilic cytoplasm containing acidophilic periodic acid Schiff- positive,diastase-resistant *** analysis showed the tumor cells expressed S-100 protein and neuron-specific ***,the resected tumor was diagnosed as a *** GCTs are usually benign,endoscopic resection constitutes an easy and safe treatment. Colonoscopists should consider the possibility of GCT in the differential diagnosis of submucosal tumors of the colon.

关键词： Adenocarcinoma Colon Colonic Neoplasms Humans Intestinal Mucosa Male Middle Aged

Severity of ultrasonographic liver steatosis and metabolic syndrome in Korean men and women

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World Journal of Gastroenterology 2005年第34期11卷 5314-5321页

作者： Hyeon Chang Kim Sung hee choi Hae Won Shin Jae Youn Cheong Kwan Woo Lee Hyun Chul Lee Kap Bum Huh dae Jung Kim Department of Preventive Medicine Yonsei University College of Medicine Seoul South Korea Department of Internal Medicine Seoul National University College of Medicine Seongnam South Korea Department of Public Health Graduate School of Yonsei University Seoul South Korea Department of Gastroenterology Ajou University School of Medicine Suwon South Korea Department of Endocrinology and Metabolism Ajou University School of Medicine Suwon South Korea Department of Internal Medicine Yonsei University College of Medicine Seoul South Korea Huh's Diabetes Center and the 21~(st) Century Diabetes and Vascular Research Institute Seoul South Korea

AIM：To evaluate the association between the severity of liver steatosis and metabolic syndrome in apparently healthy Korean adults. METHODS： We examined 1022 men and women, aged 30-79 years, who participated in a health screening test. A standard interview, anthropometrics, biochemical studies, and abdominal ultrasonography were conducted for each participant. Metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel Ⅲ, with a modification for the waist circumference cut-off level. The severity of liver steatosis was evaluated using liver ultrasonography, and serum aspartate aminotransferase（AST）, alanine aminotransferase （ALT）, and γ-glutamyl transferase （γ-GT） levels were determined. RESULTS： Ultrasonographic liver steatosis was strongly associated with metabolic syndrome and common metabolic abnormalities. Compared with people without steatosis, people with mild, moderate, and severe steatosis had adjusted odds ratios for metabolic syndrome of 2.72 （95% CI, 1.01-2.94）, 2.89 （1.75-4.76） and 3.53 （1.25-9.98） in men, and 2.86 （1.64-5.01）, 3.19 （1.80-5.65） and 3.70 （0.82-16.73） in women, respectively. The serum AST level was not associated with metabolic syndrome. The serum ALT and γ-GT levels were significantly associated with metabolic syndrome in men but not in women.CONCLUSION： The occurrence of metabolic syndrome shows a stronger association with the severity of ultrasonographic steatosis than with the serum liver enzyme levels. The degree of fatty infiltration detected on ultrasonography can be used as an indicator of liver dysfunction attributable to metabolic abnormalities.

关键词： Metabolic syndrome Liver steatosis Nonalcoholic fatty liver disease Ultrasonography

Tribology of multilayer coatings for wear reduction: A review

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Friction 2017年第3期5卷 248-262页

作者： Mahdi KHADEM Oleksiy V.PENKOV hee-Kyung YANG dae-Eun KIM Department of Mechanical Engineering Yonsei University Seoul 03722 Republic of KoreaCenter for Nano-Wear Yonsei University Seoul 03722 Republic of Korea Center for Nano-Wear Yonsei University Seoul 03722 Republic of Korea Department of Mechanical Engineering Yonsei University Seoul 03722 Republic of Korea

Friction and wear phenomena encountered in mechanical systems with moving components are directly related to efficiency,reliability and life of the ***,minimizing and controlling these phenomena to achieve the desired system performance is *** the numerous strategies developed for reducing friction and wear,coatings have been successfully utilized in various engineering applications to mitigate tribological *** of the benefits of coatings is that they may be fabricated using a variety of materials in several different forms and structures to satisfy the requirements of the operating *** many types,coatings that are comprised of a combination of materials in the form of a multilayer have been gaining much interest due to the added degree of freedom in tailoring the coating *** this paper,the properties and development status of multilayer coating systems for tribological applications were reviewed with the aim to gain a better understanding regarding their advantages and ***,focus was given to Ti-based and Cr-based coatings since Ti and Cr were identified as important elements in multilayer coating *** was given to materials,design concepts,mechanical properties,deposition method,and friction and wear characteristics of these types of coatings.

关键词： multilayer coating friction wear tribology

Formation and Thermal Stability of Large Precipitates and Oxides in Titanium and Niobium Microalloyed Steel

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Journal of Iron and Steel Research International 2008年第3期15卷 70-77页

作者： ZHUO Xiao-jun WOO dae-hee WANG Xin-hua LEE Hae-geon Metallurgical and Ecological Engineering School University of Science and Technology Beijing Belling 100083 China Graduate Institute of Ferrous Technology Pohang University of Science and Technology Pohan4g 790 784 South Korea

As-cast CC slabs of microalloyed steels are prone to surface and sub-surface cracking. Precipitation phenomena initiated during solidification reduce ductility at high temperature. The unidirectional solidification unit is employed to simulate the solidification process during continuous casting. Precipitation behavior and thermal stability are systematically investigated. Samples of adding titanium and niobium to steels have been examined using field emission scanning electron microscope （FE-SEM）, electron probe X-ray microanalyzer （EPMA）, and transmission electron microscope （TEM）. It has been found that the addition of titanium and niobium to high-strength low-alloyed （HSLA） steel resulted in undesirable large precipitation in the steels, i. e. , precipitation of large precipitates with various morphologies. The composition of the large precipitates has been determined, The effect of cooling rate on （Ti, Nb）（C, N） precipitate formation is investigated. With increasing the cooling rate, titanium-rich （Ti,Nb）（C,N） precipitates are transformed to niobium-rich （Ti,Nb）（C,N） precipitates. The thermal stability of these large precipitates and oxides have been assessed by carrying out various heat treatments such as holding and quenching from temperature at 800 and 1 200℃. It has been found that titanium-rich （Ti,Nb）（C,N） precipitate is stable at about 1 200 ℃ and niobium-rich （Ti,Nb）（C,N） precipitate is stable at about 800 ℃. After reheating at 1 200℃ for 1 h, （Ca,Mn）S and TiN are precipitated from Ca-Al oxide. However, during reheating at 800 ℃ for l h, Ca-Al-Ti oxide in specimens was stable. The thermodynamic calculation of simulating the thermal process is employed. The calculation results are in good agreement with the experimental results.

关键词： carbonitride microsegregation dendritic region unidirectional solidification heat treatment thermal stability

Asymptotic Results for Random Processes

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Acta Mathematicae Applicatae Sinica 2017年第2期33卷 363-372页

作者： hee-JIN MOON CHANG-HO HAN YONG-KAB choi Department of Mathematics and RINS Gyeongsang National University Jinju 660-701 South Korea

In this paper we establish asymptotic results and a generalized uniform law of the iterated logarithm （LIL） for the increments of a strictly stationary random process, whose results are proved by separating linearly positive quadrant dependent （LPQD） random process and linearly negative quadrant dependent （LNQD） one, respectively.

关键词： quadrant dependence stationary random process law of the iterated logarithm

High-Performance Perovskite Quantum Dot Solar Cells Enabled by Incorporation with Dimensionally Engineered Organic Semiconductor

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Nano-Micro Letters 2022年第12期14卷 272-285页

作者： Seyeong Lim dae Hwan Lee Hyuntae choi Yelim choi Dong Geon Lee Sung Beom Cho Seonkyung Ko Jongmin choi Younghoon Kim Taiho Park Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Materials Science and Engineering Hanyang UniversitySeoul 04763Republic of Korea Center of Materials Digitalization Korea Institute of Ceramic Engineering and Technology(KICET)Jinju 52851Republic of Korea Department of Materials Science and Engineering Ajou UniversitySuwon 16499Republic of Korea Department of Energy Science and Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu 42988Republic of Korea Department of Chemistry Kookmin UniversitySeoul 02707Republic of Korea

Perovskite quantum dots(PQDs)have been considered promising and effective photovoltaic absorber due to their superior optoelectronic properties and inherent material merits combining perovskites and ***,they exhibit low moisture stability at room humidity(20-30%)owing to many surface defect sites generated by inefficient ligand exchange *** surface traps must be re-passivated to improve both charge transport ability and moisture *** address this issue,PQD-organic semiconductor hybrid solar cells with suitable electrical properties and functional groups might dramatically improve the charge extraction and defect *** organic semiconductors are typically low-dimensional(1D and 2D)and prone to excessive self-aggregation,which limits chemical interaction with *** this work,we designed a new 3D star-shaped semiconducting material(Star-TrCN)to enhance the compatibility with *** robust bonding with Star-TrCN and PQDs is demonstrated by theoretical modeling and experimental *** Star-TrCN-PQD hybrid films show improved cubic-phase stability of CsPbI_(3)-PQDs via reduced surface trap states and suppressed moisture *** a result,the resultant devices not only achieve remarkable device stability over 1000 h at 20-30%relative humidity,but also boost power conversion efficiency up to 16.0%via forming a cascade energy band structure.

关键词： CsPbI3 quantum dots Star-shaped organic semiconductors Hybrid perovskite quantum dots Solar cell stability High-efficiency photovoltaics

Establishment of a prediction tool for ocular trauma patients with machine learning algorithm

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International Journal of Ophthalmology(English edition) 2021年第12期14卷 1941-1949页

作者： Seungkwon choi Jungyul Park Sungwho Park Iksoo Byon hee-Young choi Department of Ophthalmology Pusan National University HospitalBusan 49241Republic of Korea Biomedical Research Institute of Pusan National University Hospital Busan 49241Republic of Korea Department of Ophthalmology School of MedicinePusan National UniversityBusan 49241Republic of Korea

AIM:To predict final visual acuity and analyze significant factors influencing open globe injury ***:Prediction models were built using a supervised classification algorithm from Microsoft Azure Machine Learning *** best algorithm was selected to analyze the predicted final visual *** retrospectively reviewed the data of 171 patients with open globe injury who visited the Pusan National University Hospital between January 2010 and July *** then applied cross-validation,the permutation feature importance method,and the synthetic minority over-sampling technique to enhance tool ***:The two-class boosted decision tree model showed the best predictive *** accuracy,precision,recall,F1 score,and area under the receiver operating characteristic curve were 0.925,0.962,0.833,0.893,and 0.971,*** increase the efficiency and efficacy of the prognostic tool,the top 14 features were finally selected using the permutation feature importance method:(listed in the order of importance)retinal detachment,location of laceration,initial visual acuity,iris damage,surgeon,past history,size of the scleral laceration,vitreous hemorrhage,trauma characteristics,age,corneal injury,primary diagnosis,wound location,and lid ***:Here we devise a highly accurate model to predict the final visual acuity of patients with open globe *** tool is useful and easily accessible to doctors and patients,reducing the socioeconomic *** further multicenter verification using larger datasets and external validation,we expect this model to become useful worldwide.

关键词： machine learning ocular trauma open globe injury predictive model vision preservation

Adoption of wide-bandgap microcrystalline silicon oxide and dual buffers for semitransparent solar cells in building-integrated photovoltaic window system

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Journal of Materials Science & Technology 2019年第8期35卷 1563-1569页

作者： Johwa Yang Hyunjin Jo Soo-Won choi Dong-Won Kang Jung-dae Kwon Surface Technology Division Korea Institute of Materials ScienceChangwon 641-831 Republic of Korea School of Energy Systems Engineering Chung-Ang UniversitySeoul 06974 Republic of Korea

We focused on developing penetration-type semitransparent thin-film solar cells(STSCs) using hydrogenated amorphous Si(a-Si:H) for a building-integrated photovoltaic(BIPV) window system. Instead of conventional p-type a-Si:H, p-type hydrogenated microcrystalline Si oxide(p-μc-SiOx:H) was introduced for a wide-bandgap and conductive window layer. For these purposes, we tuned the CO2/SiH4 flow ratio(R) during p-μc-SiOx:H deposition. The film crystallinity decreased from 50% to 13% as R increased from 0.2 to 1.2. At the optimized R of 0.6, the quantum efficiency was improved under short wavelengths by the suppression of p-type layer parasitic absorption. The series resistance was well controlled to avoid fill factor loss at R = 0.6. Furthermore, we introduced dual buffers comprising p-a-SiOx:H/i-a-Si:H at the p/i interface to alleviate interfacial energy-band mismatch. The a-Si:H STSCs with the suggested window and dual buffers showed improvements in transmittance and efficiency from 22.9% to 29.3% and from 4.62% to 6.41%, respectively, compared to the STSC using a pristine p-a-Si:H window.

关键词： Microcrystalline silicon oxide Building-integrated photovoltaics Semitransparent Thin film Solar cells