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Room-temperature synthesis of ZrSnO4 nanoparticles for electron transport layer in efficient planar hetrojunction perovskite solar cells

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Journal of Materials Science & Technology 2020年第7期42卷 38-45页

作者： Young Wook Noh In Su Jin sang hyun Park Jae Woong jung Department of Advanced Materials Engineering for Information&Electronics Kyung Hee University1732 Deogyeong-daeroGiheung-guYongin-siGyeonggi-do 446-701Republic of Korea

The interface engineering plays a key role in controlled optoelectronic properties of perovskite photovoltaic devices,and thus the electron transport layer(ETL)material with tailored optoelectronic properties remains a challenge for achieving high photovoltaic performance of planar perovskite solar cells(PSCs).Here,the fine and crystalline zirconium stanate(ZrSnO4)nanoparticles(NPs)was synthesized at low temperature,and its optoelectronic properties are systematically *** from the favorable electronic structure of ZrSnO4 NPs for applications in ETL,efficient electron transport and extraction with suppre s sed charge recombination are achieved at the interface of perovskite *** a result,the optimized ZrSnO4 NPs synthesized at room-temperature deliver the optimized power conversion efficiency up to 16.76%with acceptable *** work opens up a new class of ternary metal oxide for the use in ETL of the planar PSCs and should pave the way toward designing new interfacial materials for practical optoelectronic devices.

关键词： ZrSnO4 Electron transport layer Nanoparticles Perovskite solar cells

Managing the lifecycle of perovskite solar cells: Addressing stability and environmental concerns from utilization to end-of-life

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eScience 2024年第2期4卷 1-27页

作者： Hee jung Kim Gill sang Han hyun Suk jung School of Advanced Materials Science&Engineering Sungkyunkwan University2066Seobu-roJangan-guSuwon-siGyeonggi-do 16419Republic of Korea Division of Advanced Materials Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Republic of Korea SKKU Institute of Energy Science and Technology(SIEST) Sungkyunkwan UniversitySuwon 16419Republic of Korea

Perovskite solar cells(PSCs)have shown remarkable advancements and achieved impressive power conversion efficiencies since their initial introduction in ***,challenges regarding stability,quality,and sustainability must be addressed for their successful commercial *** review analyses the recent studies and challenges related to the operating life and end-of-life utilization of *** to enhance the stability and mitigate the toxic Pb leakage in operational and recycling approaches of discarded PSCs post their end-of-life are examined to establish a viable and sustainable PSC ***,future research directions are proposed for the advancements in the PSC *** goal is to ensure high efficiency as well as economic and environmental sustainability throughout the lifecycle of PSCs.

关键词： Levelized cost of electricity Metal electrode Pb leakage Perovskite Power conversion efficiency Solar cell life cycle

Impact of UV-A Radiation on Erythemal UV and UV-index Estimation over Korea

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Advances in Atmospheric Sciences 2015年第12期32卷 1639-1646页

作者： sang Seo PARK Yun Gon LEE jung hyun KIM Department of Atmospheric Sciences Yonsei University Department of Atmospheric Sciences Chungnam National University

Because total UV （TUV） in the UV-A region is 100 times higher than in the UV-B region, UV-A is a considerable compo- nent when calculating erythemal UV （EUV） and UV-index. The ratio of EUV to TUV in the UV-A value [EUV（A）/TUV（A）] is investigated to convert the EUV（A） from TUV（A） for broadband observation. The representative value of EUV（A）/TUV（A）, from the simulation study, is 6.9 × 10^- 4 changing from 6.1 ×10^-4 to 7.0 × 10^ -4 as aerosol optical depth, total ozone and solar zenith angle change. By adopting the observational data of EUV（B） and TUV（A） from UV-biometer measurements at Yonsei University [（37.57°N, 126.95°E）, 84 m above sea level], the EUV irradiance increases to 15% of EUV（B） due to the consideration of EUV（A） from the data of TUV（A） observation. Compared to the total EUV observed from the Brewer spec- trophotometer at the same site, the EUV（B） from the UV-biometer observes only 95% of total EUV, and its underestimation is caused by neglecting the effect of UV-A. However, the sum of EUV（B） and EUV（A） [EUV（A＋B）] from two UV-biometers is 10% larger than the EUV from the Brewer spectrophotometer because of the spectral overlap effect in the range 320-340 nm. The correction factor for the overlap effect adjusts 8% of total EUV.

关键词： erythemal UV total UV UV-B UV-biometer

Continuity control method of cutter posture vector for efficient five-axis machining

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Journal of Central South University 2011年第6期18卷 1969-1975页

作者： HWANG Jong-dae KIM sang-myung jung hyun-chul jung Yoon-gyo School of Mechatronics Changwon National University

During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to improve the efficiency of five-axis machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. By using an MC-space algorithm for interference avoidance, an MB-spline algorithm for continuous control was intended to create a five-axis machining tool path with excellent surface quality and economic feasibility. A five-axis cutting experiment was performed to verify the effectiveness of the continuity control. The result shows that the surface shape with continuous method is greatly improved, and the surface roughness is generally favorable. Consequently, the effectiveness of the suggested method is verified by identifying the improvement of efficiency of five-axis machining of an impeller in aspects of surface quality and machining time.

关键词： five-axis control machining configuration-space B-spline continuity control method impeller interference

Influence of undissolved second-phase particles on dynamic recrystallization behavior of Mg–7Sn–1Al–1Zn alloy during low-and high-temperature extrusions

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Journal of Materials Science & Technology 2021年第12期71卷 87-97页

作者： hyun Ji Kim sang-Cheol Jin Jae-Gil jung Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu41566Republic of Korea Implementation Research Division Korea Institute of Materials ScienceChangwon51508Republic of Korea

This study investigates the effects of fine and coarse undissolved particles in a billet of the Mg–7 Sn–1 Al–1 Zn(TAZ711)alloy on the dynamic recrystallization(DRX)behavior during hot extrusion at low and high temperatures and the resultant microstructure and mechanical properties of the *** this end,partially homogenized(PH)and fully homogenized(FH)billets are extruded at temperatures of250 and 450°*** PH billet contains fine and coarse undissolved Mg_(2) Sn particles in the interdendritic region and along the grain boundaries,*** fine particles(<1μm in size)retard DRX during extrusion at 250°C via the Zener pinning effect,and this retardation causes a decrease in the area fraction of dynamically recrystallized(DRXed)grains of the extruded *** addition,the inhomogeneous distribution of fine particles in the PH billet leads to the formation of a bimodal DRXed grain structure with excessively grown grains in particle-scarce *** contrast,in the FH billet,numerous nanosized Mg_(2) Sn precipitates are formed throughout the material during extrusion at 250°C,which,in turn,leads to the formation of small,uniform DRXed grains by the grain-boundary pinning effect of the *** the PH billet is extruded at the high temperature of 450°C,the retardation effect of the fine particles on DRX is weakened by their dissolution in theα-Mg matrix and the increased extent of thermally activated grain-boundary *** contrast,the coarse Mg_(2) Sn particles in the billet promote DRX during extrusion through the particle-stimulated nucleation phenomenon,which results in an increase in the area fraction of DRXed *** both low and high extrusion temperatures,the extruded material fabricated using the PH billet,which contains both fine and coarse undissolved particles,has a lower tensile strength than that fabricated using the FH billet,which is virtually devoid of second-phase *** lower strength of the former is attributed mai

关键词： Mg–Sn alloy Second-phase particle Extrusion Homogenization Dynamic recrystallization

Measurement of biological age may help to assess the risk of colorectal adenoma in screening colonoscopy

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World Journal of Gastroenterology 2017年第37期23卷 6877-6883页

作者： sang-jung Kim Beom Jin Kim hyun Kang Department of Internal Medicine Bundang Jesaeng Hospital Sungnam-si Department of Internal Medicine Chung-Ang University College of Medicine Department of Anesthesiology and Pain Medicine.Chung-Ang University College of Medicine

AIM To investigate the clinical utility of biological age(BA) measurement in screening colonoscopy for the detection of colorectal adenomas in the average-risk *** A consecutive series of asymptomatic subjects aged ≥ 30 years who underwent colonoscopy in routine check-ups were enrolled. Colorectal adenoma was classified according to size, number, and location. BAs were calculated using the MEDIAGETM Biological Age Measurement *** A total of 2696 subjects were investigated(1876 men and 820 women). The mean chronological age(CA) was 46.0 years and the mean BA was 44.7 years. Metabolic syndrome(MS) was diagnosed in 218 subjects(8.1%). The prevalence of overall colorectal adenoma was 23.1%(622/2,696). When the subjects were divided into four groups based on BA(≤ 39 years; 40-49 years; 50-59 years; ≥ 60 years), the prevalence of colorectal adenoma was increased as BA increased(P < 0.001). Colorectal adenoma located in the proximal colon was more prevalent in the BA-dominant group(BA-CA ≥ 5years) than the CA-dominant group(CA-BA ≥ 5 years)(P = 0.034). When the subjects were categorized into four groups according to MS and age gap between BA and CA, the incidence of colorectal adenoma increased with MS and BA-dominance(P < 0.05).CONCLUSION Measurement of BA may help to assess the risk of colorectal adenoma in screening colonoscopy.

关键词： Chronological age Biological age Colorectal adenoma Age gap

Emission of particulate and gaseous pollutants from household laser processing machine

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Journal of Environmental Sciences 2021年第5期33卷 148-156页

作者： hyun Sik Ko sang Bin Jeong Sooyeol Phyo Jiwon Lee Jae Hee jung Department of Mechanical Engineering Sejong UniversitySeoul 05006Republic of Korea Center for Environment Healthand Welfare ResearchKorea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Graduate School of Energy and Environment Korea UniversitySeoul 02841Republic of Korea Department o f Materials Science and Engineering Korea UniversitySeoul 02841Republic of Korea

Indoor air quality(IAQ) directly affects the health of occupants. Household manufacturing equipment(HME) used for hobbies or educational purposes is a new and unexplored source of air pollution. In this study, we evaluated the characteristics of particulate and gaseous pollutants produced by a household laser processing equipment(HLPE). Various target materials were tested using a commercial HLPE under various operating conditions of laser power and sheath air flow rate. The mode diameters of the emitted particles gradually decreased as laser power increased, while the particle number concentration(PNC) and particle emission rate(PER) increased. In addition, as the sheath air flow rate quadrupled from 10 to 40 L/min, the mode diameter of the emitted particles decreased by nearly 25%, but the effect on the PNC was insignificant. When the laser induced the target materials at 53 m W, the mode diameters of particles were 2.0 × 10^(4) particles/cm^(3). Particularly, analyses of sampled aerosols indicated that harmful substances such as sulfur and barium were present in particles emitted from leather. The carcinogenic gaseous pollutants such as acrylonitrile, acetaldehyde, 1,3-butadiene, benzene, and C 8 aromatics(ethylbenzene) were emitted from all target materials. In an actual indoor environment, the PNC of inhalable ultrafine particles(UFPs) was > 5 × 10^(4) particles/cm^(3) during 30 min of HLPE operation. Our results suggest that more meticulous control methods are needed, including the use of less harmful target materials along with filters or adsorbents that prevent emission of pollutants.

关键词： Indoor air quality(IAQ) Emission Laser processing Ultrafine particles(UFPs) Volatile organic compounds(VOCs)

Intramedullary spinal cord metastasis from pancreatic neuroendocrine tumor

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World Journal of Gastroenterology 2014年第38期20卷 14063-14067页

作者： jung Ho Kim Chang Lim hyun sang Hoon Han Department of Internal Medicine Gachon University Gil Medical Center Department of Pathology Jeju National University School of Medicine Department of Internal Medicine Jeju National University School of Medicine

Intramedullary spinal cord metastasis(ISCM) is very rare and its optimal treatment remains controversial. Pancreatic neuroendocrine tumor(pNET) is a rare tumor that usually presents with hepatic metastasis. Hepatic failure due to tumor progression is the major cause of death in cases of pNET. To date,no report has described a case of ISCM from pNET. Although spinal cord metastasis of a solid tumor is uncommon,it is a critical condition that can cause a potentially irreversible loss of neurologic function. Here,we report the case of a 45-year-old man who presented with leg weakness and voiding difficulty,and was found to have ISCM from pNET. Surgical treatment prevented further neurological deterioration. This is the first case report of ISCM from pNET.

关键词： Intramedullary Spinal cord neoplasm Metastasis Neuroendocrine tumor Pancreas

Dual function of a high-contrast hydrophobic-hydrophilic coating for enhanced stability of perovskite solar cells in extremely humid environments

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Nano Research 2017年第11期10卷 3885-3895页

作者： Jin Sun Yoo Gill sang Han Seongha Lee Min Cheol Kim Mansoo Choi hyun Suk jung jung-Kun Lee School of Advanced Materials Science amp Engineering Sungkyunkwan University Suwon 440-746 Republic of Korea Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Department of Mechanical and Aerospace Engineering Seoul National University Seoul 08826 Republic of Korea

In spite of a continuous increase in their power conversion efficiency （PCE） and an economically viable fabrication process,organic-inorganic perovskite solar cells （PSCs） pose a significant problem when used in practical applications：They show fast degradation of the PCE when exposed to very humid *** this study,the stability of PSCs under very humid conditions is greatly enhanced by coating the surface of the PSC devices with a multi-layer film consisting of ultrahydrophobic and relatively hydrophilic layers.A hydrophobic composite of poly（methyl methacrylate）（PMMA）,polyurethane （PU）,and SiO2 nanoparticles successfully retards the water molecules from very humid ***,the hydrophilic layer with moderately PMMA captures the residual moisture within the perovskite layer;subsequently,the perovskite layer *** dual function of the coating film keeps the PCE of PSCs at 17.3% for 180 min when exposed to over 95% humidity.

关键词： perovskite solar cell stability surface coating ultrahydrophobic self-recovery