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Shear deformable finite beam elements for composite box beams

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Acta Mechanica Sinica 2014年第2期30卷 223-240页

作者： nam-Il Kim Dong-Ho choi Department of Architectural Engineering Sejong University Department of Civil and Environmental Engineering Hanyang University

The shear deformable thin-walled composite beams with closed cross-sections have been developed for coupled flexural, torsional, and buckling analyses. A theoretical model applicable to the thin-walled laminated composite box beams is presented by taking into account all the structural couplings coming from the material anisotropy and the shear deformation effects. The current composite beam includes the transverse shear and the restrained warping induced shear deformation by using the first-order shear deformation beam theory. Seven governing equations are derived for the coupled axial-flexural-torsional-shearing buckling based on the principle of minimum total potential energy. Based on the present analytical model, three different types of finite composite beam elements, namely, linear, quadratic and cubic elements are developed to analyze the flexural, torsional, and buckling problems. In order to demonstrate the accuracy and superiority of the beam theory and the finite beam elements developed by this study,numerical solutions are presented and compared with the results obtained by other researchers and the detailed threedimensional analysis results using the shell elements of ABAQUS. Especially, the influences of the modulus ratio and the simplified assumptions in stress-strain relations on the deflection, twisting angle, and critical buckling loads of composite box beams are investigated.

关键词： Thin-walled Composite box beam Deflection Twisting angle Buckling load Shear deformation

Theory of phonon-modulated electron spin relaxation time based on the projection reduction method

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Chinese Physics B 2014年第8期23卷 436-443页

作者： nam Lyong Kang Sang Don choi Department of Applied Nanoscience Pusan National University Department of Physics Kyungpook National University

This paper introduces a new method for a formula for electron spin relaxation time of a system of electrons interacting with phonons through phonon-modulated spin-orbit coupling using the projection-reduction method. The phonon absorption and emission processes as well as the photon absorption and emission processes in all electron transition processes can be explained in an organized manner, and the result can be represented in a diagram that can provide intuition for the quantum dynamics of electrons in a solid. The temperature （T） dependence of electron spin relaxation times （T1） in silicon is T1 ∝ T-1.07 at low temperatures and T1 ∝ T-3.3 at high temperatures for acoustic deformation constant Pad = 1.4 × 10^7 eV and optical deformation constant Pod = 4.0 × 10^17 eV/m. This means that electrons are scattered by the acoustic deformation phonons at low temperatures and optical deformation phonons at high temperatures, respectively. The magnetic field （B） dependence of the relaxation times is T1 ∝ B-2.7 at 100 K and T1 ∝ B-2.3 at 150 K, which nearly agree with the result of Yafet, T1 ∝ B-3.0- B -2.5.

关键词： electron spin resonance spin-orbit coupling projection-reduction method phonon scattering

Effective I/O Scheme Based on RTP for Multimedia Communication Systems

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Journal of Computer Science & Technology 2006年第6期21卷 989-996页

作者： nam-Sup Park Chong-sun Hwang Department of Computer Science and Engineering Korea Univcrsity Seoul Korea

The prime standard for audio/video transport in IP networks is the Real-time Transport Protocol （RTP） and it is targeted at useful services for the transport of real-time multimedia data. RTP was originally designed for use in multicast conferences, using the lightweight sessions model. RTP （in particular, the data part） is so tightly coupled to the application that a number of people have developed libraries that implement RTP. However, little is known about the RTP overheads between user area and kernel area within operating systenl. Actually, unnecessary copying between user area and kernel area lowers the system efficiency. In this paper, we present the design and implementation of Enhanced Multimedia Input/Output Scheme based on LINUX. We brought focus to the crossover architecture supporting RTP. Our contributions are able to be summarized into two components： 1） Enhanced Input/Output （EIO） scheme based on LINUX improves the transmission speed by reducing the overheads generated from data copy and context switch between user area and kernel area. And this enables server-based system to transport multimedia data more efficiently. 2） Furthermore, Enhanced Input/Output scheme with RTP （EIORTP） scheme supports efficient multimedia data transmission architecture. The two schemes improve the performance of massive multimedia data transmission.

关键词： kernel area system call EIO RTP EIORTP

A study on effects of ceramic foam filter on flow aspect through water modeling experiment

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China Foundry 2017年第3期14卷 216-225页

作者： Ho-Young Hwang Cheol-Hee nam Young-Sim choi Jun-Ho Hong Xun sun Cyber Manufacturing Process Group Korea Institute of Industrial Technology Incheon 21999 South Korea Department of Robotics and Virtual Engineering Korea University of Science and Technology Daejeon 34113 South Korea Materials Science and Engineering Kyoto University Kyoto 606-8501 Japan Shenyang Research Institute of Foundry Shenyang 110022 China

Casting defects that are closely related to entrapped air bubbles and metallic oxides occur very frequently in the sand mold casting process. Many researchers have shown that these defects can be reduced by adopting an appropriate gating system design. However, it is difficult for field engineers to identify a specific gating system that is more appropriate for their products. In this study, we tried to draw a comparison between two gating system designs with and without a ceramic foam filter. The ceramic foam filter was added to the horizontal runner just after the down sprue to prevent air bubble generation and reduce turbulence without a change of gating system design. The water modeling experiment was conducted with four different amounts of the initial volumes of water in the reservoir to verify the effects of initial pouring velocity. The results of the experiment applying the filter showed remarkably changed flow characteristics. The use of the filter was found to convert the flow pattern of water in the desired direction. The ceramic foam filter performed well to reduce flow velocity and stabilize the water *** flow pattern without a filter can be improved significantly even with the the use of just a 10 PPI irregular filter. Although the study confirmed that use of the filter may change the flow characteristics, it needs to be noted that the use of the ceramic filter alone cannot solve all the problems caused by a poorly designed gating system.

关键词： ceramic foam filter sprue gating system design sand mold casting casting defect

Omnidirectional color wavelength tuning of stretchable chiral liquid crystal elastomers

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Light(Science & Applications) 2024年第6期13卷 1062-1074页

作者： Seungmin nam Wontae Jung Jun Hyuk Shin Su Seok choi Department of Electrical Engineering Pohang University of Science and Technology(POSTECH)PohangKorea

Wavelength-tunable structural colors using stimuli-responsive materials,such as chiral liquid crystals(CLCs),have attracted increasing attention owing to their high functionality in various tunable photonic ***,on-demand omnidirectional wavelength control is highly desirable from the perspective of wavelength-tuning ***,despite numerous previous research efforts on tunable CLC structural colors,only mono-directional wavelength tuning toward shorter wavelengths has been employed in most studies to *** this study,we report the ideally desired omnidirectional wavelength control toward longer and shorter wavelengths with significantly improved tunability over a broadband wavelength *** using areal expanding and contractive strain control of dielectric elastomer actuators(DEAs)with chiral liquid crystal elastomers(CLCEs),simultaneous and omnidirectional structural color-tuning control was *** breakthrough in omnidirectional wavelength control enhances the achievable tuning freedom and versatility,making it applicable to a broad range of high-functional photonic applications.

关键词： tuning tunable directional

The J-shape association of serum total IgE levels with age-related cataract

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International Journal of Ophthalmology(English edition) 2018年第6期11卷 1009-1012页

作者： Sangshin Park nam-Kyong choi Center for International Health Research Rhode Island Hospital the Warren Alpert Medical School of Brown University Department of Pediatrics the Warren Alpert Medical School of Brown University Department of Health Convergence Ewha Womans University

AIM： To address the association between serum total IgE levels and age-related cataract in adults. METHODS： The study participants consisted of 1052 adults aged 40y or older in the Korean National Health and Nutrition Examination Survey 2010. We performed multivariable logistic regression analyses using the quartile cut-points of total IgE levels. RESULTS： The odds ratios （ORs） for nuclear and any cataract with ≥267 kU/L of serum IgE levels were 1.75 [95% confidence intervals （CI）, 1.04-2.96] and 2.00 （95%CI, 1.22-3.27）, respectively, comparing to 35-87 kU/L. Interestingly, participants with ≤35 kU/L of IgE levels （OR, 1.67; 95%CI, 1.02-2.72） also had higher risk for any cataract than those with 35-87 kU/L. The risk for any cataract （OR, 1.48; 95%CI, 1.03-2.13） was higher in participants with high total IgE levels （〉150 kU/L）, comparing to normal participants. CONCLUSION： Our findings indicate a J-shaped relationship between serum IgE levels and age-related cataract.

关键词： IgE allergy cataract eye

Surgical treatment of liver metastasis with uveal melanoma:A case report

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World Journal of Clinical Cases 2021年第28期9卷 8498-8503页

作者： Young-Hun Kim nam-Kyu choi Department of Surgery Chosun University HospitalGwangju Metropolitan City 61453South Korea Department of Surgery Division of Hepatobiliary Surgery and Liver TransplantationChosun University HospitalGwangju Metropolitan City 61453South Korea

BACKGROUND Uveal melanoma is the most common primary intraocular malignant tumor affecting the eyes in *** half of all primary uveal melanoma tumors metastasize;yet,there are currently no effective treatments for metastatic uveal *** the time of diagnosis,less than 4%of patients with uveal melanoma have detectable metastatic *** melanoma disseminates hematogenously,with the most common site of metastasis being liver(93%),followed by lung(24%)and bone(16%).CASE SUMMARY A 57-year-old woman was diagnosed with a dysplastic nevus on her eyelid,which was histologically confirmed as malignant melanoma after *** patient had no evidence of metastasis to other organs and received both radiation therapy and *** systemic treatment,a metastatic left neck lymph node was found and another round of chemotherapy was performed after *** emission tomography-Computed Tomography tracking after completion of chemotherapy revealed two metastatic liver *** patient underwent partial liver resection and showed no signs of recurrence at 1 year after *** Surgery is an effective treatment for metastatic uveal *** patients with liver metastatic lesions,hepatectomy improves outcome.

关键词： Uveal melanoma Metastatic melanoma Liver metastasis Hepatectomy Prognosis Case report

Primary duodenal dedifferentiated liposarcoma:A case report and literature review

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World Journal of Clinical Cases 2022年第6期10卷 2007-2014页

作者： Nah Ihm Kim Ji Shin Lee Chan choi Jong Hee nam Yoo Duk choi Hee Joon Kim sung sun Kim Department of Pathology Chonnam National University HospitalGwangju 61469South Korea Department of Pathology Chonnam National University Hwasun HospitalHwasun 58128South Korea Department of Surgery Chonnam National University HospitalGwangju 61469South Korea

BACKGROUND Dedifferentiated liposarcoma(DDLPS)is an extremely rare neoplasm that exhibits various *** tumor is characterized by immunoreactivity to MDM2 and CDK4 and can be confirmed by detecting MDM2 amplification via fluorescence in situ hybridization(FISH).Herein,we report an unusual case of DDLPS arising from the *** SUMMARY A 64-year-old man presented with repeated abdominal pain and weight *** studies revealed a mass of the duodenum involving the *** patient was treated with pylorus-preserving ***,the tumor showed a high-grade *** demonstrated that the tumor cells were positive for MDM2 and CDK4 ***2 amplification was detected via FISH,leading to the final diagnosis of *** surgery,the patient was treated in the intensive care unit due to peritonitis,and died 60 d after *** To the best of the authors’knowledge,this is the first case of primary duodenal DDLPS in Korea and the third case in the English-language *** must be taken not to misdiagnose DDLPS as another high-grade *** should be in the differential diagnosis list.

关键词： Liposarcoma Primary Small bowel Duodenum Immunohistochemistry Case report

Sandwich-structure transferable free-form OLEDs for wearable and disposable skin wound photomedicine

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Light(Science & Applications) 2019年第1期8卷 96-110页

作者： Yongmin Jeon Hye-Ryung choi Jeong Hyun Kwon Seungyeop choi Kyung Mi nam Kyoung-Chan Park Kyung Cheol choi School of Electrical Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Department of Dermatology Seoul National University Bundang Hospital(SNUBH)Seongnam 13620Republic of Korea

Free-form optoelectronic devices can provide hyper-connectivity over space and ***,most conformable optoelectronic devices can only be fabricated on flat polymeric materials using low-temperature processes,limiting their application and *** paper presents free-form optoelectronic devices that are not dependent on the shape or *** medical applications,the transferable OLED(10μm)is formed in a sandwich structure with an ultra-thin transferable barrier(4.8μm).The results showed that the fabricated sandwich-structure transferable OLED(STOLED)exhibit the same high-efficiency performance on cylindricalshaped materials and on materials such as textile and *** the neutral axis is freely adjustable using the sandwich structure,the textile-based OLED achieved both folding reliability and washing reliability,as well as a long operating life(>150 h).When keratinocytes were irradiated with red STOLED light,cell proliferation and cell migration increased by 26 and 32%,*** the skin equivalent model,the epidermis thickness was increased by 39%;additionally,in organ culture,not only was the skin area increased by 14%,but also,reepithelialization was highly *** on the results,the STOLED is expected to be applicable in various wearable and disposable photomedical devices.

关键词： optoelectronic structure transfer