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Evaluation of defects in aluminum piston castings by using ultrasonics and computer tomography

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China Foundry 2012年第3期9卷 275-278页

作者： In-Sung Cho Jeong-Ho Hwang Jin-Seok Yang seung-mok yoo Chae-Ho Lim Korea Institute of Industrial Technology

Pistons used in automobile engines are made of aluminum alloy; and endurance of high pressure and high temperature is required. Recently, high strength pistons are needed to cope with the increase of pressure and temperature in the engine cylinder. A high strength piston is possible when the piston casting has little or no casting defects, such as micro-pores and cracks. Generally the defects can be evaluated by non-destructive testing (NDT), and the most efficient ways for evaluation are using ultrasonics and computer tomography. In the present study, two NDT methods were compared and evaluated to investigate the defects in the aluminum piston castings. Artificial defects were machined by using very small drill bits with diameters 1, 0.5, 0.3, 0.2 and 0.1 mm. The defects were investigated by using an ultrasonic tester and a computer tomography system. Defects smaller than 0.3 mm may not be found by using the ultrasonic test, but the defects may be found by using the computer tomography system. The investigation conditions for detecting small defects and the scanning time for in-line defect analysis are discussed in the present study.

关键词： piston ultrasonic test computer tomography aluminum defect

N, P co-doped 3D porous carbon with self-assembled morphological control via template-free method for potassiumion battery anodes

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Rare Metals 2024年第9期43卷 4243-4252页

作者： Jeehoon Yu Dae Kyom Kim Hong Geun Oh seung-Keun Park Youngjae yoo Department of Advanced Materials Engineering Chung-Ang University

The larger ionic radius of potassium ions than that of lithium ions significantly limits the accomplishment of rapid diffusion kinetics in graphite electrodes for potassium-ion batteries （PIBs）,resulting in comparatively poor rate performance and cycle ***,we report a high-rate performance and cycling stability amorphous carbon electrode achieved through nitrogen and phosphorous *** as-prepared N,P co-doped carbon electrodes have distinct 3D structures with large surface areas,hierarchical pore architectures,and increased interlayer spaces resulting from the direct pyrolysis of supramolecular self-assembled aggregates without *** obtained electrode N3P1 exhibits a reversible specific capacity of 258 m Ah·g-1at a current density of 0.1A·g-1and a good long-term cycle performance (96.1%capacity retention after 800 cycles at 0.5 A·g-1).Kinetic investigations show that the N3P1 electrode with the welldeveloped porous structure and large number of surface defects exhibits capacitive-driven behavior at all scan rates,which may be attributed by N and P ***-situ transmission electron microscopy analyses in the fully discharged and charged states demonstrate structural stability and reversibility owing to the expanded interlayer *** suggested synthesis approach is simple and effective for producing heteroatom-doped carbon materials for PIBs and other advanced electrochemical energy storage materials.

关键词： 3D porous structures Amorphous carbons Nitrogen and phosphorous co-doping Potassium-ion batteries

Machine-learned wearable sensors for real-time hand-motion recognition: toward practical applications

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National Science Review 2024年第2期11卷 231-263页

作者： Kyung Rok Pyun Kangkyu Kwon Myung Jin yoo Kyun Kyu Kim Dohyeon Gong Woon-Hong Yeo seungyong Han seung Hwan Ko Department of Mechanical Engineering Seoul National University IEN Center for Human-Centric Interfaces and Engineering Institute for Electronics and NanotechnologyGeorgia Institute of Technology School of Electrical and Computer Engineering Georgia Institute of Technology Department of Chemical Engineering Stanford University Department of Mechanical Engineering Ajou University George W.Woodruff School of Mechanical Engineering Georgia Institute of Technology Institute of Advanced Machinery and Design(SNU-IAMD) Seoul National University

Soft electromechanical sensors have led to a new paradigm of electronic devices for novel motion-based wearable applications in our daily lives. However, the vast amount of random and unidentified signals generated by complex body motions has hindered the precise recognition and practical application of this technology. Recent advancements in artificial-intelligence technology have enabled significant strides in extracting features from massive and intricate data sets, thereby presenting a breakthrough in utilizing wearable sensors for practical applications. Beyond traditional machine-learning techniques for classifying simple gestures, advanced machine-learning algorithms have been developed to handle more complex and nuanced motion-based tasks with restricted training data sets. Machine-learning techniques have improved the ability to perceive, and thus machine-learned wearable soft sensors have enabled accurate and rapid human-gesture recognition, providing real-time feedback to users. This forms a crucial component of future wearable electronics, contributing to a robust human–machine interface. In this review, we provide a comprehensive summary covering materials, structures and machine-learning algorithms for hand-gesture recognition and possible practical applications through machine-learned wearable electromechanical sensors.

关键词： wearable sensor soft electronics artificial intelligence machine learning human–machine interfaces gesture recognition

Long cycle-life aqueous Zn battery enabled by facile carbon nanotube coating on Cu current collector

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Carbon Energy 2024年第6期6卷 151-164页

作者： Beom-Keun Cho Sung-Ho Huh So Hee Kim seungho Yu Jong-Seong Bae Jung-Keun yoo seung-Ho Yu Department of Chemical and Biological Engineering Korea UniversitySeoulRepublic of Korea Advanced Analysis Center Korea Institute of Science and Technology(KIST)SeoulRepublic of Korea Energy Storage Research Center Korea Institute of Science and Technology(KIST)SeoulRepublic of Korea KIST School Division of Energy and Environment TechnologyKorea University of Science and TechnologySeoulRepublic of Korea Busan Center Korea Basic Science Institute(KBSI)BusanRepublic of Korea Carbon Composites Department Composites Research DivisionKorea Institute of Materials Science(KIMS)ChangwonRepublic of Korea

As an alternative to Li-ion batteries,aqueous Zn batteries have gained attention due to the abundance of Zn metal,low reduction potential(-0.76 V *** hydrogen electrode),and high theoretical capacity(820 mAh g^(-1))of multivalent Zn2+***,the growth of Zn dendrites and the formation of irreversible surface reaction byproducts pose challenges for ensuring a long battery lifespan and ***,the Cu foil coated with a single-walled carbon nanotube(SWCNT)layer using a facile doctor blade casting method is *** SWCNT-coated Cu foil demonstrates a significantly longer battery lifespan compared to the bare Cu in the half-cell *** operando optical microscopy imaging,we are able to provide intuitive evidence that Zn deposition occurs between the carbon nanotube(CNT)coating and Cu substrate,in agreement with the computational ***,with various imaging techniques,the flat morphology and homogeneous distribution of Zn beneath the SWCNT layer are *** addition,the full-cell using CNT-coated Cu exhibits a long cycle life compared to the control group,thereby demonstrating improved electrochemical performance with limited Zn for the cycling process.

关键词： aqueous Zn battery carbon nanotube operando imaging surface coating

Survival benefit of concurrent chemoradiotherapy for advanced ampulla of Vater cancer

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World Journal of Clinical Cases 2024年第2期12卷 267-275页

作者： Chae Hwa Kwon Hyung Il Seo Dong Uk Kim Sung Yong Han Suk Kim Nam Kyung Lee seung Baek Hong Ji Hyun Ahn Young mok Park Byeong Gwan Noh BioMedical Research Institute Pusan National University HospitalBusan 49241South Korea Department of Surgery Pusan National University School of Medicine and Biomedical Research InstitutePusan National University HospitalBusan 49241South Korea Department of Internal Medicine Pusan National University School of Medicine and Biomedical Research InstitutePusan National University HospitalBusan 49241South Korea Department of Radiology Pusan National University School of Medicine and Biomedical Research InstitutePusan National University HospitalBusan 49241South Korea Department of Pathology and Biomedical Research Institute Pusan National University HospitalBusan 49241South Korea

BACKGROUND Currently,there is no standard adjuvant therapy for patients with resected ampulla of Vater(AoV)*** To evaluate the effectiveness of adjuvant concurrent chemoradiotherapy(CCRT)in patients with advanced AoV cancer who underwent curative *** This single-centered,retrospective study included 29 patients with advanced AoV cancer who underwent pancreaticoduodenectomy between 2006 and *** impact of CCRT on advanced AoV cancer was *** The 1-,3-,and 5-yr recurrence-free survival(RFS)rates for patients with advanced AoV cancer were 82.8%,48.3%,and 40.8%,respectively,and the overall survival(OS)rates were 89.7%,62.1%,and 51.7%,***-cular invasion was found to be a significant risk factor for RFS and OS in patients with advanced AoV cancer in the univariate analysis,whereas T stage and lymph node metastasis were significantly associated with OS in the multivariate *** to the patients who did not receive adjuvant CCRT,those who received adjuvant CCRT did not show statistically significant improvements in the RFS and OS,although they had a significantly lower average age and significantly higher platelet-to-lymphocyte *** Adjuvant CCRT did not improve survival outcomes in patients with advanced AoV *** findings contribute to existing knowledge on the effectiveness of CCRT in this patient population and provide important insights for clinical decision-making.

关键词： Advanced ampulla of Vater cancer Adjuvant concurrent chemoradiotherapy Recurrence Survival Vater cancer

Application of ferrate(VI) in the treatment of industrial wastes containing metal-complexed cyanides : A green treatment

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Journal of Environmental Sciences 2009年第10期21卷 1347-1352页

作者： seung-mok Lee DIWAKAR Tiwari Department of Environmental Engineering Kwandong University Department of Chemistry School of Physical Sciences Mizoram University

Ferrate（VI） was employed for the oxidation of cyanide （CN） and simultaneous removal of copper or nickel in the mixed/complexed systems of CN-Cu, CN-Ni, or CN-Cu-Ni. The degradation of CN （1.00 mmol/L） and removal of Cu （0.095 mmol/L） were investigated as a function of Fe（Ⅵ） doses from 0.3-2.00 mmol/L at pH 10.0. It was found that Fe（Ⅵ） could readily oxidize CN and the reduction of Fe（Ⅵ） into Fe（Ⅲ） might serve efficiently for the removal of free copper ions. The increase in Fe（Ⅵ） dose apparently favoured the CN oxidation as well as Cu removal. Moreover, the pH dependence study （pH 10.0-13.0） revealed that the oxidation of CN was almost unaffected in the studied pH range （10.0-13.0）, however, the maximum removal efficiency of Cu was obtained at pH 13.0. Similarly, treatment was carded out for CN-Ni system having the initial Ni concentration of 0.170 mmol/L and CN concentration of 1.00 mmol with Fe（Ⅵ） dose 2.00 mmol at various pH values （10.0-12.0）. Results showed a partial oxidation of CN and partial removal of Ni. It can be observed that Fe（Ⅵ） can partially degrade the CN-Ni complex in this pH range. Further, Fe（Ⅵ） was applied for the treatment of simulated industrial waste/effluent waters treatment containing CN, Cu, and Ni.

关键词： cyanide metal-complexed cyanide oxidation copper nickel ferrate(Ⅵ)

Mismatching between nest volume and clutch volume reduces egg survival and fledgling success in black-tailed gulls

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Current Zoology 2016年第5期62卷 451-456页

作者： Who-seung LEE Jeong-Chil yoo Korea Institute of Ornithology and Department of Biology Kyung Hee University Seoul 02447 Korea Center for Stock Assessment Research University of California Santa Cruz Santa Cruz CA 95080 USA

A longstanding suggestion posits that parents prefer to match nest volume and clutch size （clutch volume）, but few studies have tested this in colonial seabirds that nest in the open. Here, we demonstrate the effects of nest-clutch volume matching on egg survival, hatching, and fledgling success in black-tailed gulls Larus crassirostris on Hongdo Island, Korea. We show that the volume mismatch, defined as the difference between nest volume and total egg volume （the sum of all eggs＇ volume in the clutch）, was positively related to egg and chick mortality caused by predation, but was not significantly related to hatching success incurred by insulation during the incubation period. Although nest volume was negatively related to laying date, we found that the mismatch was positively related to laying date. Our results support the claim that well-matched nest-clutch volume may contribute to survival of eggs and chicks, and ultimately breeding success.

关键词： black-tailed gulls clutch size egg survival fledgling success nest volume.

Influence of the wastewater composition on denitrification and biological P-removal in the S-DN-P process: (c) Dissolved and undissolved substrates

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Journal of Environmental Sciences 2009年第8期21卷 1074-1079页

作者： Hee-Jeong Choi Chul-Ho Choi seung-mok Lee Diwakar Tiwari Department of Environmental Engineering Kwandong University Department of Chemistry School of Physical Sciences Mizoram University

The denitdfication and P-removal in the sorption-denitrification-P-removal （S-DN-P） process were carded out under various wastewater compositions. It is noted that P-removal largely depends on the wastewater composition as well to the quantity of the substrates present in wastewater fraction. Three different wastewater fractions are obtained as： raw wastewater, dissolved wastewater （obtained with filtration using 0.45 μm filter）, and undissolved wastewater （i.e., infiltrate obtained by above filtration）. The ratio of P-release/CODtotal-consumption clearly inferred that undissolved wastewater possess very low value i.e., 0.0008 followed by raw wastewater 0.008 and dissolved wastewater 0.03. When this ratio was nearby 0.01, enhanced P-removal was observed. Moreover, the ratio of P-uptake to NO3^--N decomposition for raw wastewater was two times for dissolved wastewater. Interestingly, it was observed that the P-removal and denitrification depend not only on the dissolved substrates but also the undissolved substrates present in the wastewater. The result of the P-removal obtained with this S-DN-P process did not show a big difference of 36%, 34% and 30%, respectively, for raw, dissolved and undissolved wastewater.

关键词： denitrification polyhydroxybutyrate sequencing batch biofilm reactor sorption denitrification P-removals

Stick-and-play system based on interfacial adhesion control enhanced by micro/nanostructures

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Nano Research 2021年第9期14卷 3143-3158页

作者： Jung II yoo seung Hyun Kim Heung Cho Ko School of Materials Science and Engineering Gwangju Institute of Science and Technology(GIST)Gwangju 61005Republic of Korea

The evolution of membrane-type electronics has facilitated the development of stick-and-play systems,which confer diverse electrical functions to various planar or arbitrary curvilinear *** stick-and-play concept is based on the development of thin electronic devices in a printable format and their subsequent transfer to target *** development of this technology requires control of the interfacial adhesion of the electronic prints for retrieval from a carrier and transfer to the target ***,we discuss the transfer printing for membrane-type electronics,starting from an overview of materials available for flexible substrates,transfer printing of electronic prints for retrieval,and assembly for further ***,we explain the stick-and-play concept based on fabricated membrane-type electronics;"stick" and “play"refer to the transfer of electronic devices and the performance of their electronic functions,*** particular,we broadly survey various methods based on micro/nanostructures,including gecko-inspired,interlocking,cephalopod-sucker-inspired,and cilia structures,which can be employed to stick-and-play systems for enhancing interfacial adhesion with complex target surfaces under dynamic and wet ***,we highlight the stick-and-play system application of micro/nanostructures for skin-attachable biomedical electronics,e-textiles,and environmental monitoring electronics.

关键词： transfer printing interfacial adhesion flexible electronics stick-and-play system bioinspired adhesive