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A unified formulation of optimal guidance-to-collision law for accelerating and decelerating targets

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Chinese Journal of Aeronautics 2022年第7期35卷 40-54页

作者： Young-Won kim Boseok kim chang-Hun LEE Shaoming HE Department of Aerospace Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

This paper provides a unified formulation of optimal guidance-to-collision law for a target with an arbitrary acceleration or *** collision course for general target acceleration or deceleration is first determined from the engagement geometry in conjunction with the nonlinear engagement kinematics in the proposed *** heading error defined in the collision course is then adopted as a variable to be nullified for accomplishing the intercept *** proposed guidance law is derived based on the heading error dynamics and the optimal error dynamics to ensure optimality and finite-time *** illustrative examples,the proposed guidance command for a constant target acceleration and a target deceleration in the form of a quadratic function of speed are ***,the time-to-go prediction method is suggested for implementing the proposed *** characteristics of the proposed guidance command are analytically investigated to provide insight into the proposed *** key benefits of the proposed method lie in not producing unnecessary guidance commands near a target compared to other methods and ensuring optimality in guidance command even in the nonlinear engagement ***,numerical simulations are performed to validate the proposed method and to show our findings.

关键词： Guidance-to-collision law Optimal guidance Optimal error dynamics Target acceleration or deceleration Unified formulation

Development of RuS_(2) for near-infrared photodetector by atomic layer deposition and post-sulfurization

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Rare Metals 2022年第9期41卷 3086-3099页

作者： Tatsuya Nakazawa Donghyun kim Jaehyeok kim Yohei Kotsugi Taehoon Cheon Seung-Min Chung soo-Hyun kim Hyungjun kim School of Electrical and Electronic Engineering Yonsei UniversitySeoul03722Korea Isehara Technical Center Metallic Materials Development DepartmentTANAKA Kikinzoku Kogyo K.KIseharaKanagawa259-1146Japan Institute of Materials Technology Yeungnam UniversityGyeongsan-si38541GyeongbukKorea Chemical Materials Development Department TANAKA Kikinzoku Kogyo K.KTsukuba Technical CenterIbaraki300-4247Japan School of Materials Science and Engineering Yeungnam UniversityGyeongsan-si38541GyeongbukKorea Center for Core Research Facilities Daegu Gyeongbuk Institute of Science&TechnologyDaegu711-873Korea

The chalcogenides of platinum-group metals(PGMs)have been known to be present in minerals and the intermediate products of *** recent years,their applications in various fields,including catalysis,have been *** that certain PGM chalcogenides behave as compound semiconductors,they can be used as materials for *** this study,RuS_(2),featuring a bandgap suitable for near-infrared photodetectors,was prepared by forming Ru on a SiO_(2)/Si substrate via the atomic layer deposition method using[Ru(TMM)(CO)_(3)]as the *** was conducted at 800℃ for 1 h under H_(2)S ***-resolution transmission electron microscopy(HRTEM)and X-ray diffraction(XRD)analysis clearly confirmed that the as-deposited hexagonal close-packed(hcp)Ru transformed to cubic RuS_(2) after *** surface morphologies,chemical states,and electrical and optical properties of RuS_(2) were *** influence of the metallic Ru surface morphology prior to sulfurization on the reaction between Ru and H_(2)S was also *** evaluate the potential of using RuS_(2) as a photodetector,a photodetector was fabricated by forming electrodes on RuS_(2) to measure its photocurrent under near-infrared ***,RuS_(2) was proven to exhibit a short response time(59μs)and generate a photocurrent of 84 nA under near-infrared light at 940 nm.

关键词： RuS_(2) Sulfurization Atomic layer deposition Photodetector

Microstructure and corrosion resistance of a Mg2Sn-dispersed Mg alloy subjected to pulsed electron beam treatment

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Journal of Magnesium and Alloys 2020年第2期8卷 345-351页

作者： Daseul Lee Beomcheol kim soo-Min Baek Jisoo kim Hyung Wook Park Jung Gu Lee Sung soo Park School of Materials Science and Engineering Ulsan National Institute of Science and TechnologyUlsan 44919Republic of Korea School of Mechanical Aerospace and Nuclear EngineeringUlsan National Institute of Science and TechnologyUlsan 44919Republic of Korea School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea

We report that the corrosion resistance of a Mg-Sn-based alloy with MgzSn precipitates can be considerably improved by surface modification using pulsed electron beam *** alloy subjected to a pulse electron beam treatment showed a modified surface layer with a thickness of〜12 μm,appearing more resistant to corrosion attack than the bare surface of the *** 0.6 M NaCl solution,the alloys with and without the surface modification exhibited average corrosion rates of 4.3 and 8.1 mm y^-1,*** improved corrosion resistance was attributed to reduced cathodic activation,resulting from the surficial reduction of relatively noble Mg2Sn precipitates.

关键词： Magnesium alloy Mg2Sn Intermetallic compound Pulsed electron beam treatment Corrosion

“One stone,two birds”solvent system to fabricate microcrystalline cellulose–Ti_(3)C_(2)T_(x)nanocomposite film as a flexible dielectric and thermally conductive material

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Nano Research 2023年第2期16卷 3240-3253页

作者： Yong-Zhu Yan Shuwei Li Sung soo Park Wei-Jin Zhang Jun Seok Lee Jung Rae kim Dong Gi Seong chang-Sik Ha Department of Polymer Science and Engineering School of Chemical EngineeringPusan National UniversityBusan 46241Republic of Korea School of Chemical and Biomolecular Engineering Pusan National UniversityBusan 46241Republic of Korea Division of Advanced Materials Engineering Dong-Eui UniversityBusan 47340Republic of Korea

A strategy for fabricating microcrystalline cellulose–Ti_(3)C_(2)T_(x)(MCC–MXene)nanocomposite films with high relative permittivity,high thermal conductivity,and excellent mechanical properties was *** MCC–MXene nanocomposite film was fabricated by casting a solution containing N,N-dimethylacetamide/lithium chloride(DMAc/LiCl)-soluble MCC and DMAcdispersible MXene nanosheets,followed by humidity control *** MXene nanosheets greatly enhanced the permittivity of the nanocomposite films owing to interfacial ***,the nanocomposite film with 20 wt.%MXene content achieved a desirable permittivity of 71.4 at 102 Hz(a 770%improvement against that of neat cellulose),while the dielectric loss only increased by 1.8 times(from 0.39 to 0.70).The obtained nanocomposite films with 20 wt.%and 30 wt.%MXene exhibited remarkable in-plane thermal conductivities of 8.523 and 9.668 W∙m^(−1)∙K^(−1),respectively,owing to the uniform dispersion and selfalignment of the MXene layered ***,the uniformly dispersed MXene nanosheets in the MCC network with interfacial interaction(hydrogen bonding)and mechanical entanglement endowed the nanocomposite films with excellent mechanical properties and ***,the thermal stability,water resistance,and antibacterial properties of the nanocomposite films were effectively improved with the introduction of ***,using DMAc/LiCl as the solvent system not only improves the compatibility between MCC and MXene but also avoids the problem of easy oxidation of MXene in aqueous *** the high stability of the MCC–MXene solution and enhanced properties of the MCC–MXene films,the proposed strategy manifests great potential for fabricating natural biomass-based dielectric materials.

关键词： Ti_(3)C_(2)T_(x) microcrystalline cellulose flexible dielectric thermally conductive N,N-dimethylacetamide/lithium chloride(DMAc/LiCl) compatibility

Effects of an Urban Park and Residential Area on the Atmospheric CO_2 Concentration and Flux in Seoul,Korea

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Advances in Atmospheric Sciences 2013年第2期30卷 503-514页

作者： Moon-soo PARK Seung Jin JOO chang Seok LEE Center for Atmospheric and Environmental Modeling Seoul 151 919Korea Life and Environmental Engineering Seoul Women's UniversitySeoul 139 774Korea

The CO2 concentrations and fluxes over an urban forest site （Namsan） and an urban residential region （Boramae） in Seoul, Korea, during the non-growing season （2 4 March 2011）, the growing season （10-12 June 2011）, and the late-growing season （22-24 September 2011） were analyzed. The CO2 concentrations of two sites showed nearly the same diurnal variation, with a maximum value occurring during the night and a minimum value occurring during daytime, as well as the same seasonal variation, with a maximum value during the non-growing season （early spring） and a minimum value during the growing season （summer）. The CO2 flux over the urban forest did not show any typical diurnal variation during the non-growing season, but did show diurnal variation with a small positive value during the night and a large negative value during daytime in the growing and late-growing seasons due to photosynthesis in the urban forest. The CO2 flux over the urban residential region showed a positive daily mean value for all periods, with large values during the non-growing season and small values during the growing season, and it also showed diurnal variation with two maxima at 0600-1000 LST and 1800-2400 LST, and two minima at 0300-0600 LST and 1100-1500 LST, and was strongly correlated with the use of liquefied natural gas for cooking and heating by surrounding houses.

关键词： C02 concentration C02 flux Seoul urban forest urban residential region

Antiviral efficacy of adefovir dipivoxil versus lamivudine in patients with chronic hepatitis B sequentially treated with lamivudine and adefovir due to lamivudine resistance

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World Journal of Gastroenterology 2007年第30期13卷 4072-4079页

作者： Yeon Seok Seo Ji Hoon kim Jong Eun Yeon Jong-Jae Park Jae Seon kim Kwan soo Byun Young-Tae Bak chang Hong Lee Division of Gastroenterology and Hepatology Department of Internal Medicine Korea University College of Medicine Seoul Korea Division of Gastroenterology and Hepatology Department of Internal Medicine Konkuk University College of Medicine Seoul Korea

AIM： To compare the antiviral efficacy of adefovir （ADV） in lamivudine （LMV）-resistant patients with LMV treatment in nucleoside-naive patients, using serum samples collected sequentially during the course of treatment progressing from LMV to ADV.METHODS： Forty-four patients with chronic hepatitis B （CHB） were included. The patients were initially treated with LMV and then switched to ADV when LMV resistance developed. Antiviral efficacy was assessed by measuring the following： reduction in serum HBV DNA from baseline, HBV DNA negative conversion （defined as HBV DNA being undectable by the hybridization assay）, and HBV DNA response （either HBV DNA level ≤ 10^s copies/mL or a ≥ 2 log10 reduction from baseline HBV DNA level）.RESULTS： After two and six months of treatment, HBV DNA reduction was greater with LMV compared to ADV treatment （P = 0.021）. HBV DNA negative conversion rates were 64% and 27% after one month of LMV and ADV treatment respectively （P = 0.001）. Similarly, HBV DNA response rates were 74% and 51% after two months of LMV and ADV treatment respectively （P = 0.026）. The time taken to HBV DNA negative conversion and to HBV DNA response were both delayed in ADV treatment compared with LMV.CONCLUSION： The antiviral efficacy of ADV in LMV-resistant patients is slower and less potent than that with LMV in nucleoside-naive patients during the early course of treatment.

关键词： Chronic hepatitis B Lamivudine Adefovir Treatment efficacy

Fabrication and Characterization of Electrodeposited Ni-SiC-h/BN Composite Coatings

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Journal of Materials Science & Technology 2014年第8期30卷 796-802页

作者： Gobinda Gyawali Hyung-Suk kim Khagendra Tripathi Tae-Ho kim soo Wohn Lee Research Center for Eco-Multifunctional Nano Materials Sun Moon UniversityAsanRepublic of Korea Department of Environmental Engineering Sun Moon UniversityChungnam 336-708Republic of Korea

Ni—SiC—h/BN composite materials were prepared by electrodeposition technique with the dispersion of SiC（10 g/L） and h/BN nanosheets（10 g/L） in a nickel sulfamate electrolytic *** ratio of sodium dodecyl sulfate（SDS） and cetyltrymethyl ammonium bromide（CTAB） surfactants were used to evaluate the effect of surfactants on the properties of the electrodeposited composite *** coating samples were characterized by scanning electron microscopy,X-ray diffraction,Vickers microhardness test,scratch and tribology *** results revealed that the co-deposition of nanoparticles was significantly influenced by surfactants during electrodeposition *** or polyhedral nickel crystallites were observed at higher ratio of SDS/CTAB while smaller oval grains with refined surface morphologies were obtained at lower ratio of SDS/CTAB *** addition,wt%of particles co-deposition was increased,and Vickers microhardness,wear and coefficient of friction of the electrodeposited composite coatings were improved at increased CTAB and decreased SDS contents in the electrolyte during electrodeposition process.

关键词： Ni-SiC-h/BN Composite coating Surfactant Microstructure Scratch Wear

Stabilizing lithium deposition within bimodal porous SiO_(2)-TiO_(2) microspheres as 3D host structure

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Nano Research 2024年第11期17卷 10179-10188页

作者： Noeul kim Jae Hun Choi Min kim Dae soo Jung Yun Chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seoul 136-713 Republic of Korea Energy Storage Materials Center Korea Institute of Ceramic Engineering and Technology Soho-ro Jinju-si Gyeongnam-do 52851 Republic of Korea

Three-dimensional (3D) host materials for lithium metal anodes (LMAs) have gained attention because they can mitigate volume expansion and local current density through their large surface area and suppress the dendritic growth of lithium. Recent research on 3D host materials has focused on conductive materials;however, the benefits of 3D host materials cannot be fully utilized because lithium deposition begins at the top of the structure. Herein, we fabricate SiO_(2)-TiO_(2) composite microspheres with bimodal pore structures (bi-SiTiO) by simple spray pyrolysis. These microspheres effectively store lithium within the structure from the bottom of the electrode while preventing lithium dendrite formation. Focused ion beam-scanning transmission electron microscopy (FIB-STEM) analysis reveals that the lithiophilic properties of composite microspheres enhanced their effectiveness in storing lithium, with small pores acting as “lithium-ion sieves” for a uniform lithium-ion flux and large pores that provide sufficient volume for lithium deposition. The bi-SiTiO composite microspheres exhibit a high Coulombic efficiency of 98.5% over 200 cycles at 2.0 mA·cm^(−2) when operated in a lithium half-cell. With a high lithium loading of 5.0 mAh·cm^(−2), the symmetrical cell of the bi-SiTiO electrode sustains more than 900 h. A full cell coupled with an LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) (NCM811) cathode also exhibits enhanced electrochemical properties in terms of cycling stability and rate capability.

关键词： lithium metal battery spray pyrolysis three-dimensional(3D)host materials bimodal pore structure lithiophilic materials

Effects of betaine on etnanol-stimulated secretion of IGF-I and IGFBP-1 in rat primary hepatocytes: involvement of p42/44 MAPK activation

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World Journal of Gastroenterology 2006年第11期12卷 1718-1722页

作者： Myeong soo Lee Myung-Sunny kim soo Young Park chang-Won Kang Complementary Medicine Peninsula Medical School Universities of Exeter and PlymouthExeterEX2 4NTUnited Kingdom Korea Food Research Institute Kyongki-do 463-746Republic of Korea Department of Animal Resources and Biotechnology Chonbuk National University Jeonju 561-756Republic of Korea Department of Physiology College of Veterinary Medicine Chonbuk National UniversityJeonju 561-756Republic of Korea

AIM： To evaluate the effects of betaine on the ethanolinduced secretion of IGF-I and IGFBP-1 using radioimrnunoassay and Western blotting, respectively, in primary cultured rat hepatocytes. METHODS： Hepatocytes isolated from male SpragueDawley rats were incubated with various concentrations of ethanol and PD98059 procedures. The hepatocytes were also treated with different doses of betaine （10^-5, 10^-4, and 10^-3 mol/L）. We measured IGF-I and IGFBP-1 using radioimmunoassay and Western blotting, respectively. RESULTS： The ethanol-induced inhibition of IGF-I secretion was attenuated by betaine in a concentration-dependent manner in primary cultured rat hepatocytes. At 10^-3 mol/L, betaine significantly increased IGF-I secretion but decreased IGFBP-1 secretion. In addition, p42/44 rnitogen-activated protein kinase （MAPK） activity was accelerated significantly from 10 min to 5 h after treatment with 10^-3 mol/L betaine. Furthermore, the changes in IGF-1 and IGFBP-1 secretion resulting from the increased betaine-induced p42/44 MAPK activity in primary cultured rat hepatocytes was blocked by treatment with the MAPK inhibitor PD98059. Betaine treatment blocked the ethanol-induced inhibition of IGF-I secretion and p42/44 MAPK activity, and the ethanol-induced increase in IGFBP-1 ***： Betaine modulates the secretion of IGF-I and IGFBP-1 via the activation of p42144 MAPK in primary cultured rat hepatocytes. Betaine also alters the MAPK activations induced by ethanol.

关键词： Betaine IGF-I IGFBP-1 p42/44 MAPK Hepatocytes Ethanol