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Thermal pyrolysis conversion of methane to hydrogen(H_(2)):A review on process parameters,reaction kinetics and techno-economic analysis

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Chinese Chemical Letters 2024年第8期35卷 62-73页

作者： Yi Herng Chan Zhe Phak Chan Serene Sow Mun Lock chung Loong Yiin Shin Ying Foong mee Kee Wong Muhammad Anwar Ishak Ven Chian Quek Shengbo Ge Su Shiung Lam PETRONAS Research Sdn.Bhd.(PRSB) Kawasan Institusi BangiLot 3288&3289Off Jalan Ayer ItamKajang 43000Malaysia PETRONAS Carbon Capture&Storage(CCS)Enterprise PETRONAS Twin TowersKuala Lumpur City CentreKuala Lumpur 50088Malaysia CO_(2)Research Center(CO2RES) Department of Chemical EngineeringUniversiti Teknologi PETRONASSeri Iskandar 32610Malaysia Department of Chemical Engineering and Energy Sustainability Faculty of EngineeringUniversiti Malaysia Sarawak(UNIMAS)Kota Samarahan 94300Malaysia Institute of Sustainable and Renewable Energy(ISuRE) Universiti Malaysia Sarawak(UNIMAS)Kota Samarahan 94300Malaysia Higher Institution Centre of Excellence(HICoE) Institute of Tropical Aquaculture and Fisheries(AKUATROP)Universiti Malaysia TerengganuKuala Nerus 21030Malaysia Co-Innovation Center of Efficient Processing and Utilization of Forest Resources College of Materials Science and EngineeringNanjing Forestry UniversityNanjing 210037China Center for Global Health Research(CGHR) Saveetha Medical CollegeSaveetha Institute of Medical and Technical Sciences(SIMATS)Saveetha UniversityChennai 602105India

Hydrogen(H_(2))is a promising renewable energy which finds wide applications as the world gears toward low-carbon ***,current H_(2) production via steam methane reforming of natural gas or gasification of coal are laden with high CO_(2) ***,methane(CH_(4))pyrolysis has emerged as a potential technology to generate low-carbon H_(2) and solid *** this review,the current state-of-art and recent progress of H_(2) production from CH_(4) pyrolysis are reviewed in *** such as funda-mental mechanism and chemistry involved,effect of process parameters on the conversion efficiency and reaction kinetics for various reaction media and catalysts are elucidated and critically ***-ature,among other factors,plays the most critical influence on the methane pyrolysis *** metal/salt could lower the operating temperature of methane pyrolysis to1000℃.Based on the reaction kinetics,metal-based cata-lysts were more efficient in lowering the activation energy of the reaction to 29.5-88 kJ/mol from that of uncatalyzed reaction(147-420.7 kJ/mol).Besides,the current techno-economic performance of the pro-cess reveals that the levelized cost of H_(2) is directly influenced by the sales price of carbon(by-product)generated,which could offset the overall ***,the main challenges of reactor design for efficient product separation and retrieval,as well as catalyst deactivation/poisoning need to be debottlenecked.

关键词： Pyrolysis Methane Hydrogen Reaction kinetics Techno-economic analysis

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Efficient nonlinear companding scheme for substantial reduction in peak-to-average power ratio of OFDM

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Journal of Systems Engineering and Electronics 2015年第5期26卷 924-931页

作者： Kasun Bandara Atul Sewaiwar yeon-Ho chung Department of Information and Communications Engineering Pukyong National University

Orthogonal frequency division multiplexing(OFDM)produces a high peak-to-average power ratio(PAPR) that adversely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear companding transform(NCT) function is proposed. With the proposed NCT function,the compression and expansion weights can be applied independently with suitably chosen function parameter values. As a result, the proposed function can easily maintain the average signal power approximately unchanged during the companding *** this regard, the proposed function is superior to previously proposed schemes. Also, the simulations show the outstanding PAPR reduction performance of the proposed function. It is demonstrated that the proposed scheme performs well with nonlinear transmitter amplifiers and delivers superior error performance, compared with error function and exponential function based schemes.

关键词： companding orthogonal frequency division multiplexing(OFDM) peak-to-average power ratio(PAPR)

Crystallographically vacancy‐induced MOF nanosheet as rational single‐atom support for accelerating CO_(2)electroreduction to CO

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Carbon Energy 2024年第8期6卷 49-62页

作者： Jin Hyuk Cho Joonhee Ma Chaehyeon Lee Jin Wook Lim Youngho Kim Ho yeon Jang Jaehyun Kim Myung‐gi Seo Youngheon Choi Youn Jeong Jang Sang Hyun Ahn Ho Won Jang Seoin Back Jong‐Lam Lee Soo Young Kim Department of Materials Science and Engineering Korea UniversitySeoulRepublic of Korea Department of Chemical and Biomolecular Engineering Sogang UniversitySeoulRepublic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)PohangRepublic of Korea Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoulRepublic of Korea Lotte Chemical R&D Center DaejeonRepublic of Korea Department of Chemical Engineering Hanyang UniversitySeoulRepublic of Korea School of Chemical Engineering and Material Science Chung‐Ang UniversitySeoulRepublic of Korea

To attain a circular carbon economy and resolve CO_(2)electroreduction technology obstacles,single‐atom catalysts(SACs)have emerged as a logical option for electrocatalysis because of their extraordinary catalytic *** SACs,metal–organic frameworks(MOFs)have been recognized as promising support materials because of their exceptional ability to prevent metal *** study shows that atomically dispersed Ni single atoms on a precisely engineered MOF nanosheet display a high Faradaic efficiency of approximately 100%for CO formation in H‐cell and three‐compartment microfluidic flow‐cell reactors and an excellent turnover frequency of 23,699 h−1,validating their intrinsic catalytic *** results suggest that crystallographic variations affect the abundant vacancy sites on the MOF nanosheets,which are linked to the evaporation of Zn‐containing organic linkers during ***,using X‐ray absorption spectroscopy and density functional theory calculations,a comprehensive investigation of the unsaturated atomic coordination environments and the underlying mechanism involving CO^(*)preadsorbed sites as initial states was possible and provided valuable insights.

关键词： 2‐dimensional material carbon dioxide reduction metal-organic frameworks single‐atom catalysts vacancy sites

Effects of heavy rainfall on the composition of airborne bacterial communities

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Frontiers of Environmental Science & Engineering 2018年第2期12卷 117-126页

作者： Gwang Il Jang chung yeon Hwang Byung Cheol Cho Microbial Oceanography Laboratory School of Earth and Environmental Sciences and Research Institute of Oceanography Seoul National University Seoul 08826 Republic of Korea Division of Polar Life Sciences Korea Polar Research Institute Incheon 21990 Republic of Korea

Wet deposition scavenges particles and particle-associated bacteria from the air column, but the impact of raindrops on various surfaces on Earth causes emission of surface-associated bacteria into the air column. Thus, after rainfall, these two mechanisms are expected to cause changes in airborne bacterial community composition （BCC）. In this study, aerosol samples were collected at a suburban site in Seoul, Korea before and after three heavy rainfall events in April, May, and July 2011. BCC was investigated by pyrosequencing the 16S rRNA gene in aerosol samples. Interestingly, the relative abundance of non-spore forming Actinobacteria operational taxonomic units （OTUs） was always higher in post-rain aerosol samples. In particular, the absolute and relative abundances of airborne Propionibacteriaceae always increased after rainfall, whereas those of airborne Firmicutes, including Carnobacteriaceae and Clostridiales, consistently decreased. Marine bacterial sequences, which were temporally important in aerosol samples, also decreased after rainfall events. Further, increases in pathogen-like sequences were often observed in post-rain air samples. Rainfall events seemed to affect airborne BCCs by the combined action of the two mechanisms, with potentially adverse effects on human and plant health.

关键词： Aerosol BacteriaCommunity composition PyrosequencingRain

Effect of modified fasting therapy on body weight, fat and muscle mass, and blood chemistry in patients with obesity

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Journal of Traditional Chinese Medicine 2016年第1期36卷 57-62页

作者： Koh-Woon Kim Mi-yeon Song Seok-Hee chung Won-Seok chung Department of Korean Rehabilitation Medicine College of Korean Medicine Kyung Hee University

OBJECTIVE: The aim of this study was to investigate the effects and safety of modified fasting therapy using fermented medicinal herbs and exercise on body weight, fat and muscle mass, and blood chemistry in obese ***: Twenty-six patients participated in a14-day fast, during which they ingested a supplement made from fermented medicinal herbs and carbohydrates(intake: 400-600 kcal/d). The schedule included 7 prefasting relief days and 14 days of stepwise reintroduction of food. The patients also took part in an exercise program that incorporated Qigong, weight training, and walking exercises. The efficacy of treatments was observed by assessing body fat mass and muscle mass, and alanine aminotransferase(ALT), aspartate aminotransferase(AST),cholesterol, and triglycerides in each study *** symptoms or side effects were ***: Body weight and body fat mass both decreased significantly by(5.16 ± 0.95) and(3.89 ±0.79) kg(both P < 0.05), while muscle mass decreased by an average of(0.26 ± 0.22) kg, without statistical significance. ALT levels were significantly decreased(P < 0.05), while AST levels decreased without statistical significance(P = 0.052). The levels of total cholesterol and triglycerides were also significantly decreased(both P < 0.05). There were few adverse events except for mild dizziness, which did not affect everyday ***: These results suggest that modified fasting therapy using fermented medicinal herbs and exercise could be effective and safe on obese patients.

关键词： Obesity Fasting Houttuynia Cordata Saururus Chinensis Exercise Blood chemicalanalysis Medicine, Korean traditional

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Operational Implementation of the ATOVS Processing Procedure in KMA and Its Validation

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Advances in Atmospheric Sciences 2003年第3期20卷 398-414页

作者： Myoung-Hwan AHN mee-Ja KIM Chu-Yong chung Ae-Sook SUH RemoteSensing Research Laboratory/Meteorological Research Institute RemoteSensing Research Laboratory/Meteorological Research InstituteRemoteSensing Research Laboratory/Meteorological Research InstituteRemoteSensing Research Laboratory/Meteorological Research Institute Seoul 156-720KoreaSeoul 156-720KoreaSeoul 156-720KoreaSeoul 156-720Korea

The Korea Meteorological Administration (KMA) has processed the data from the advanced TOVS (ATOVS) onboard NOAA-16 satellite since May 2001. The operational production utilizes the AAPP (ATOVS and AVHRR Processing Package) of EUMETSAT and IAPP (International ATOVS Processing Package) of the University of Wisconsin. For the initial guess profiles, the predicted fields (usually 6 to 12 hour forecasted fields) from the global aviation model of NOAA/NCEP are used. The average number of profiles retrieved from the ATOVS data is about 1,300 for each morning and afternoon orbit at about 18 and 06 UTC, respectively. The retrieved temperature and dew point temperatures are provided to forecasters in real time and used for initialization of prediction models. With the advanced microwave sensor (AMSU; Advanced Microwave Sounding Unit), accuracy of the ATOVS products is expected to be better than that of the TOVS products, especially in cloudy conditions. Indeed, the preliminary results from a validation study with the collocated radiosonde data during a 8-month period, from May to December 2001, for the East Asia region show an improved accuracy of the ATOVS products for cloudy skies versus the TOVS, especially for higher altitudes. The RMS (Root Mean Square) difference between the ATOVS products and radiosonde data is about 1.3°C for both clear and cloudy conditions, except for near the ground and at higher altitudes, at around 200 hPa. There is no significant temporal variation of the error statistics at all pressure levels. In case of the water vapor mixing ratio, the largest difference is shown at lower altitudes, while the accuracy is much better for the clear sky cases than the cloudy sky cases. The bias and RMSE at lower altitudes is about 0.557 g kg−1 and 2.5 g kg−1 and decrease significantly with increasing altitude.

关键词： ATOVS Processing and validation temperature and humidity profiles

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Multiple-Object Tracking Using Histogram Stamp Extraction in CCTV Environments

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Computers, Materials & Continua 2023年第12期77卷 3619-3635页

作者： Ye-yeon Kang Geon Park Hyun Yoo Kyungyong chung Division of AI Computer Science and Engineering Kyonggi UniversitySuwon16227Korea Contents Convergence Software Research Institute Kyonggi UniversitySuwon16227Korea

Object tracking,an important technology in the field of image processing and computer vision,is used to continuously track a specific object or person in an *** technology may be effective in identifying the same person within one image,but it has limitations in handling multiple images owing to the difficulty in identifying whether the object appearing in other images is the *** tracking the same object using two or more images,there must be a way to determine that objects existing in different images are the same ***,this paper attempts to determine the same object present in different images using color information among the unique information of the ***,this study proposes a multiple-object-tracking method using histogram stamp extraction in closed-circuit television *** proposed method determines the presence or absence of a target object in an image by comparing the similarity between the image containing the target object and other *** this end,a unique color value of the target object is extracted based on its color distribution in the image using three methods:mean,mode,and interquartile *** Top-N accuracy method is used to analyze the accuracy of each method,and the results show that the mean method had an accuracy of 93.5%(Top-2).Furthermore,the positive prediction value experimental results show that the accuracy of the mean method was 65.7%.As a result of the analysis,it is possible to detect and track the same object present in different images using the unique color of the *** the results,it is possible to track the same object that can minimize manpower without using personal information when detecting objects in different *** the last response speed experiment,it was shown that when the mean was used,the color extraction of the object was possible in real time with 0.016954 *** this,it is possible to detect and track the same object in real time when using the proposed

关键词： Data mining deep learning object detection object tracking real-time object detection multiple object image processing

Temporary severe oculomotor nerve palsy after reconstruction of orbital medial wall fracture: a case report of nonfamiliar complication

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International Journal of Ophthalmology(English edition) 2022年第6期15卷 1032-1034页

作者： yeon Woong chung Tae Yoon La Department of Ophthalmology St.Vincent's HospitalCollege of Medicinethe Catholic University of KoreaSuwon 16247Republic of Korea

Dear Editor, Commonly known complications following reconstruction of an orbital fracture include diplopia, hemorrhage, and displacement or infection of the orbital implant, and some studies have reported ptosis cause... 详细信息

关键词： fracture orbital dip

New prognostic model for patients with advanced gastric cancer:Fluoropyrimidine/platinum doublet for first-line chemotherapy

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World Journal of Gastroenterology 2021年第48期27卷 8357-8369页

作者： Dong-Hoe Koo Min-Hee Ryu Mi-yeon Lee mee-Sun Moon Yoon-Koo Kang Division of Hematology/Oncology Department of Internal MedicineKangbuk Samsung HospitalSungkyunkwan University School of MedicineSeoul 03181South Korea Department of Oncology Asan Medical CenterUniversity of Ulsan College of MedicineSeoul 05505South Korea Division of Biostatistics Department of R&D ManagementKangbuk Samsung HospitalSeoul 03181South Korea

BACKGROUND New prognostic factors have been reported in patients with metastatic or recurrent gastric cancer(MRGC),necessitating modifications to the previous prognostic *** To develop a new model,MRGC patients who received fluoropyrimidines/platinum doublet chemotherapy between 2008 and 2015 were *** A total of 1883 patients was divided into a training set(n=937)and an independent validation set(n=946).RESULTS Multivariate analysis showed that the following six factors were associated with poor overall survival(OS)in the training set:Eastern Cooperative Oncology Group performance score≥2 and bone metastasis(2 points each),peritoneal metastasis,high alkaline phosphatase level,low albumin level,and high neutrophil-lymphocyte ratio(1 point each).A prognostic model was developed by stratifying patients into good(0-1 point),moderate(2-3 points),and poor(≥4 points)risk *** the validation set,the median OS of the three risk groups was 15.8,10.1,and 5.7 mo,respectively,and those differences were significant(P<0.001).CONCLUSION We identified six factors readily measured in clinical practice that are predictive of poor prognosis in patients with *** new model is simpler than the old and more easily predicts OS.

关键词： Stomach neoplasms Chemotherapy Prognosis Validation Gastric cancer