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A Comparison between Direct and Indirect Laser Sintering of Metals

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Journal of Materials Science & Technology 2008年第2期24卷 227-232页

作者： Montasser M.Dewidar jae-kyoo lim K.W.Dalgarno Department of Mechanical Design and Materials High Institute of EnergySouth Valley UniversityAswanEgypt Automobile Hi-Technology Research Intitute Faculty of Mechanical & Aerospace System EngineeringChonbuk National UniversityDuckjin 1-664-14JeonjuJB 561-756South Korea School of Mechanical and Systems Engineering Stephenson BuildingClaremont RoadNewcastle UniversityNewcastle upon Tyne NE1 7RUUnited Kingdom

Layer manufacture technologies are gaining increasing attention in the manufacturing for the production of polymer mould tooling. Layer manufacture techniques can be used in this potential manufacturing area to produce tooling either indirectly or directly, and powder metal based layer manufacture systems are considered as an effective way of producing rapid tooling. Mechanical properties and accuracy are critical for tooling. This paper reports the results of an experimental study examining the potential of layer manufacturing processes to deliver production tooling for polymer manufacture. A comparison between indirectly selective laser sintering and directly selective laser sintering to provide the tooling was reported. Three main areas were addressed during the study： mechanical strength, accuracy, and build rate. Overviews of the results from the studies were presented.

关键词： Selective laser sintering Layer manufacture Mould tooling Rapid tooling

Effect of Si_3N_4 Addition on the Mechanical Properties, Microstructures, and Wear Resistance of Ti-6Al-4V Alloy

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Journal of Materials Science & Technology 2007年第2期23卷 257-261页

作者： Ruihua HU Montasser M. Dewidar Hyo-Jin KIM jae-kyoo lim Henan University of Science and Technology Luoyang 471003 China Department of Mechanical Design Chonbuk National University Dokjin 1-664-14 Jeonju South Korea Department of Mechanical Design and Materials High Institute of Energy South Valley University Aswan Egypt Automobile High-Technology Research Institute Faculty of Mechanical and Aerospace System Engineering Chonbuk National University Dokjin 1-664-14 Jeonju South Korea

In order to improve the wear resistance of Ti-6Al-4V, different amounts of Si3N4 powder were added into the alloy powder and sintered at 1250℃. Porous titanium alloy with higher wear resistance was successfully fabricated. At sintering temperature, reaction took place and a new hard phase of Ti5Si3 formed. The mechanical properties of the fabricated alloys with different amounts of Si3N4 addition were investigated. The hardness of Ti-6Al-4V, which is the index of wear resistance, was increased by the addition of Si3N4. Amounts of Si3N4 addition have very significant influences on hardness and compressive strength. In present study,titanium alloy with 5 wt pct Si3N4 addition has 62% microhardness and 45% overall bulk hardness increase,respectively. In contrast, it has a 16.4% strength reduction. Wear resistance was evaluated by the weight loss during wear test. A new phase of Ti5Si3 was detected by electron probe microanalyzer （EPMA） and X-ray diffraction （XRD） method. The original Si3N4 decomposed during sintering and transformed into titanium silicide. Porous structure was achieved due to the sintering reaction.

关键词： Ti-6Al-4V Silicon nitride Sintering reaction Mechanical properties

Single-cell and spatial omics:exploring hypothalamic heterogeneity

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Neural Regeneration Research 2025年第6期20卷 1525-1540页

作者： Muhammad Junaid Eun Jeong Lee Su Bin lim Department of Biochemistry&Molecular Biology Ajou University School of MedicineSuwonSouth Korea Department of Biomedical Sciences Graduate School of Ajou UniversitySuwonSouth Korea Department of Brain Science Ajou University School of MedicineSuwonSouth Korea

Elucidating the complex dynamic cellular organization in the hypothalamus is critical for understanding its role in coordinating fundamental body functions. Over the past decade, single-cell and spatial omics technologies have significantly evolved, overcoming initial technical challenges in capturing and analyzing individual cells. These high-throughput omics technologies now offer a remarkable opportunity to comprehend the complex spatiotemporal patterns of transcriptional diversity and cell-type characteristics across the entire hypothalamus. Current single-cell and single-nucleus RNA sequencing methods comprehensively quantify gene expression by exploring distinct phenotypes across various subregions of the hypothalamus. However, single-cell/single-nucleus RNA sequencing requires isolating the cell/nuclei from the tissue, potentially resulting in the loss of spatial information concerning neuronal networks. Spatial transcriptomics methods, by bypassing the cell dissociation, can elucidate the intricate spatial organization of neural networks through their imaging and sequencing technologies. In this review, we highlight the applicative value of single-cell and spatial transcriptomics in exploring the complex molecular-genetic diversity of hypothalamic cell types, driven by recent high-throughput achievements.

关键词： cellular diversity hypothalamus multi-omics single-cell transcriptomics spatial transcriptomics

Novel N-doped multichannel carbon nanofiber architecture with porous CoS nanoprisms for high-performance potassium-ion batteries

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Rare Metals 2024年第3期43卷 971-983页

作者： jae Bong lim Seung-Keun Park Department of Advanced Materials Engineering Chung-Ang UniversityGyeonggi-do17546Republic of Korea Department of Intelligence Energy and Industry Chung-Ang UniversitySeoul06974Republic of Korea Western Seoul Center Korea Basic Science InstituteSeoul03759Republic of Korea

Potassium-ion batteries(PIBs)have gained significant attention as an alternative to lithium-ion batteries(LIBs)due to the abundance of potassium(K)and low ***,the difficulty in finding appropriate electrode materials that can efficiently store the larger K ions has hindered their practical ***,we report a novel anode material,N-doped multichannel carbon nanofibers embedded with porous CoS nanoprisms(CSP@NMCNF),for high-performance *** CSP@NMCNF was synthesized using a two-step strategy comprising of the electrospinning of Co acetate hydroxide nanoprism/binary polymer blend and a subsequent heat *** porous CoS nanoprisms with an anisotropic morphology were well aligned along the length axis of the N-doped multichannel carbon nanofibers,thus ensuring their structural stability during the repeated charge-discharge *** addition,numerous pores facilitated the transport of electrons and ***,the CSP@NMCNF anode exhibited excellent electrochemical performance,delivering a high specific capacity of 368 mAh·g^(-1)at 0.5 A·g^(-1)after 200 cycles and excellent rate capability(232 mAh·g^(-1)at 2.0 A·g^(-1)).

关键词： K-ion batteries Cobalt sulfide Multichannel structured composite Electrospinning Nanoprism Porous structure

Targeted therapy in gastric cancer:Personalizing cancer treatment based on patient genome

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World Journal of Gastroenterology 2014年第8期20卷 2042-2050页

作者： Sun Min lim jae Yun lim jae Yong Cho Division of Medical Oncology Department of Internal MedicineSeverance HospitalYonsei University College of MedicineSeoul 135-720South Korea Department of Medical Oncology Gangnam Severance HospitalYonsei University College of MedicineSeoul 135-720South Korea

Gastric cancer is the second leading cause of cancerrelated deaths *** cytotoxic chemotherapy has limited efficacy for metastatic gastric cancer,with an overall survival of approximately ten *** advances in high-throughput technologies have enabled the implementation of personalized cancer therapy for high-risk *** use of such high-throughput technologies,including microarray and next generation sequencing,have promoted the discovery of novel targets that offer new treatment strategies for patients lacking other therapeutic *** molecular pathways are currently under investigation as therapeutic targets in gastric cancer,including those related to the epidermal growth factor receptor family,the mesenchymal-epithelial transition factor axis,and the phosphatidylinositol 3-kinase-AKTmammalian target of rapamycin *** in molecular diagnostic tools further support the discovery of new molecular *** exist,however;not all patients can be tested for biomarkers,and numerous challenges hamper implementation of targeted therapy in clinical ***,the scale of tumor genomic profiling is rapidly outpacing our ability to appropriately synthesize all the information in order to optimally refine patient ***,clinicians must continue to educate themselves regarding new tools and frameworks,and to utilize multidisciplinary team science,comprised of oncologists,geneticists,pathologists,biologists and bioinformaticians,to successfully implement this genomic approach therapeutically.

关键词： Gastric cancer Targeted therapy Biomarker Microarray Sequencing

Characterization of Ga-doped ZnO Nanorods Synthesized via Microemulsion Method

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Journal of Materials Science & Technology 2013年第1期29卷 39-43页

作者： Sang kyoo lim Seong Hui Hong Sung-Ho Hwang Soonhyun Kim Hyunwoong Park Division of Nano & Bio Technology Daegu Gyeongbuk Institute of Science and Technology (DGIST) School of Energy Engineering Kyungpook National University

Gallium-doped ZnO （GZO） nanorods were synthesized by microemulsion method with different types of surfactants. The phase and morphology of the above nanorods were investigated by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, high resolution transmission electron microscopy （HR-TEM） and X-ray photoelectron spectroscopy （XPS）. SEM observations show that the ZnO nanorods have diameters around 70-200 nm and lengths up to several micrometers. The room temperature photoluminescence （PL） spectrum of GZO nanorods exhibited a sharp and strong ultraviolet bandgap at 383 nm and a relatively weaker emission associated with the defect level. Resistivity of GZO nanorods synthesized with sodium lauryl sulfate （SLS） and sodium benzene sulfonate （SBS） surfactants showed 2.84 Ω m and 14.2 Ω m, respectively.

关键词： Zinc oxide Nanorod Microemulsion Gallium Surfactants

Diurnal Variation of Tropical Convection during TOGA COARE IOP

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Advances in Atmospheric Sciences 2005年第5期22卷 685-702页

作者： jae-Young BYON Gyu-Ho lim School of Earth and Environmental Sciences Seoul National University Seoul South KoreaSchool of Earth and Environmental Sciences Seoul National University Seoul South Korea

Diurnal variation of tropical convection and kinematic and thermodynamic conditions was investigated for different large-scale environments of the convectively active and inactive periods by using satellite observations and surface measurements during the Intensive Observation Period （IOP） of the Tropical Ocean Global Atmosphere/Coupled Ocean-Atmosphere Response Experiment （TOGA/COARE）. During the convectively active period, the features of nocturnal convection appear in vertical profiles of convergence, vertical velocity, heat source, and moisture sink. The specific humidity increases remarkably in the middle troposphere at dawn. On the other hand, the altitude of maximum convergence and that of the upward motion is lower during the convectively inactive period. The specific humidity peaks in the lower troposphere in the daytime and decreases in the middle troposphere. Spectral analyses of the time series of the infrared （IR） brightness temperature （TBB） and amounts of rainfall suggest multiscale temporal variation with a prominent diurnal cycle over land and oceanic regions such as the Intensive Flux Array （IFA） and the South Pacific Convergence Zone （SPCZ）. Over land, the daily maximum of deep convection associated with cloud top temperature less than 208 K appears at midnight due to the daytime radiative heating and the sea-land breeze. Over the ocean, convection usually tends to occur at dawn for the convectively active period while in the afternoon during the inactive period. Comparing the diurnal variation of convection with large-scale variables, the authors inferred that moisture in the middle troposphere contributes mostly to the development of nocturnal convection over the ocean during the convectively active period.

关键词： diurnal variation tropical convection rainfall large-scale environment

Effect of ZnO Electrodeposited on Carbon Film and Decorated with Metal Nanoparticles for Solar Hydrogen Production

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Journal of Materials Science & Technology 2016年第10期32卷 1059-1065页

作者： Young Kwang Kim Hye-Jin Seo Soonhyun Kim Sung-Ho Hwang Hyunwoong Park Sang kyoo lim Division of Nano and Energy Convergence Research Daegu Gyeongbuk Institute of Science and Technology (DGIST) School of Energy Engineering Kyungpook National University

In this study, we prepared horn-like ZnO structures on carbon films（ZnO/CF） by electrodeposition and decorated the ZnO horns with different metals（Ag, Au, and Pt） via photodeposition（M-ZnO/CF）. Using M-ZnO/CF as photocatalysts, we examined ways to enhance solar hydrogen production from various points of view, such as modifying the intrinsic physical properties and thermodynamics of the materials, and varying the chemical environment during M-ZnO/CF fabrication. In particular, we focused on the effects of the carbon film and metals in M-ZnO/CF hybrid photocatalysts on solar hydrogen production. The type of metal nanoparticles is an important factor in solar hydrogen production because the deposition rate and electrical conductivity of each metal affect the proton-water reduction ability.

关键词： Solar hydrogen production ZnO horn Carbon film Metal nanoparticle Electrodeposition

Optimization of post-warranty sequential inspection for second-hand products

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Journal of Systems Engineering and Electronics 2017年第4期28卷 793-800页

作者： Dae-Kyung Kim jae-Hak lim Dong Ho Park Department of Statistics Chonbuk National University Department of Management & Accounting Hanbat National University Industry Academic Cooperation Foundation Hallym University

This paper considers an optimal sequential inspection schedule for a second-hand product after that the free nonrenewable warranty is expired. The length of warranty is prespecified and during the warranty period, the product is minimally repaired by the dealer when it fails. Following the expiration of the non-renewing warranty, the product is inspected and upgraded sequentially a fixed number of times at the expenses of the *** each inspection, the failure rate of the product is reduced proportionally so that the product is upgraded. The product is assumed to deteriorate as it ages and the replacement of the product occurs when a fixed number of inspections are rendered. In addition,the intervals between two successive inspections are assumed to decrease monotonically. The main objective of this paper is to determine the optimal improvement level to upgrade the product at each inspection so that the expected maintenance cost during the life cycle of the product is minimized from the perspective of the customer. Under the given cost structures, we derive an explicit formula to obtain the expected maintenance cost incurred during the life cycle of the product and discuss the method to find the optimal level of the improvement analytically in case the failure times follow the Weibull distribution. Numerical results are analyzed to observe the impact of relevant parameters on the optimal solution.

关键词： second-hand product sequential inspection upgrade action life cycle of the product expected maintenance cost free non-renewable warranty