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Influence of operational parameters on the photocatalytic performance of DE-NOx process Via MIL-101(Fe)

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Progress in Natural Science:Materials International 2018年第6期28卷 689-695页

作者： hoang Phuc Nguyen tae ho kim Soo Wohn Lee Research Center for Eco Multi-Functional Nano Materials Sun Moon University Department of Environmental & Bio-Chemical Engineering Sun Moon University

Metal organic framework(MOF)has been paid great attention as a potential candidate for various applications in the field of energy and environment,particularly in air *** various MOFs,MIL-101(Fe) represents an interesting material possessing many advantages,including the ease of fabrication,high porosity,high specific surface area with open metal sites,making it a promising material in the field of harmful gas *** these advantages,MIL-101(Fe) was synthesized by facile microwave-solvothermal method and applied as a photocatalyst for the degradation of *** de-NOxefficiency of the synthesized powder was evaluated with respect to various operating parameters including substrates,sample doses,light spectrum and light intensity,initial NO concentration,and relative *** results have shown that the efficiency of NOxphotocatalytic degradation reaches to 77%under solar irradiation via 0.1 g of MIL-101(Fe) with optimum condition of reaction,(alumina substrate,350 ppb of initial NO concentration,40–50%of relative humidity).Then this work provides the optimum condition for the efficient photocatalytic degradation of NOx.

关键词： Metal-organic framework MIL-101 Gaseous pollutant NOx emission Photocatalyst

Mooring Tension and Motion Characteristics of A Submerged Fish Reef with Net in Waves and Currents Using Numerical Analysis

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China Ocean Engineering 2012年第2期26卷 261-276页

作者： tae ho kim David W.Fredriksson Judson DeCewc School of Marine Technology Chonnam National University Department of Naval Architecture and Ocean Engineering United States Naval Academy Annapolis Center for Ocean Engineering University of New Hampshire

A numerical model was used to analyze the motion response and mooring tension of a submerged fish reef system. The system included a net attached to a rigid structure suspended up from the bottom with a single, high tension mooring by fixed flotation. The analysis was performed by using a Morison equation type finite element model configured with truss elements. Input forcing parameters into the model consisted of both regular and irregular waves, with and without a steady current. Heave, surge and pitch dynamic calculations of the reef structure were made. Tension response results of the attached mooring line were also computed. Results were analyzed in both the time and frequency domain in which appropriate, linear transfer functions were calculated. The influence of the current was more evident in the tension and heave motion response data. This is most likely the result of the large buoyancy characteristics of the reef structure and the length of the mooting cable. Maximum mooting component tension was found to be 13.9 kN and occurred when the reef was subjected to irregular waves with a co-linear current of 1.0 m/s velocity. The results also showed that the system had little damping （in heave） with damped natural periods of 2.8 s. This combination of system characteristics promotes a possible resonating situation in typical open sea conditions with similar wave periods.

关键词： floating fish reef fish aggregating device numerical model waves and currents net structure

3D printed leech-inspired origami dry electrodes for electrophysiology sensing robots

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npj Flexible Electronics 2022年第1期6卷 61-70页

作者： tae-ho kim Chao Bao Ziniu Chen Woo Soo kim Additive Manufacturing Laboratory School of Mechatronic Systems EngineeringSimon Fraser UniversitySurreyBCCanada

In this study,based on inspiration drawn from origami and the suction mechanism of leeches,a dry electrode is developed for reliable blood pressure(BP)*** leech-inspired suction mechanism generated a local soft vacuum facilitating appropriate contact with the human ***,an electrocardiogram(ECG)sensor,termed a leech-inspired origami(LIO)sensor,was constructed using the developed dry *** LIO with a sensing robot system ensures reliable ECG signals with a signal-to-noise ratio of 21.7±0.56 *** the paired detection of ECG and photoplethysmography(PPG)through human-robot interaction,BP monitoring was *** average difference of the systolic BP between that estimated by the sensing robot and that monitored by the sphygmomanometer was 0.03 mmHg,indicating the reliable BP monitoring ability of the sensing *** LIO sensing system inspired by origami and leech behaviors makes BP sensing tools feasible,which in turn would further the development of a remote healthcare monitoring robotic system.

关键词： robot app system

A study on characteristics of shock train inside a shock tube

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Theoretical & Applied Mechanics Letters 2017年第6期7卷 366-371页

作者： Dong Wook kim tae ho kim Heuy Dong kim Department of Mechanical Engineering Andong National UniversityAndongKorea

Shock tubes are devices which are used in the investigation of high speed and high temperature flow of compressible gas. lnside a shock tube, the interaction between the reflected shock wave and boundary layer leads to a complex flow phenomenon. Initially a normal shock wave is formed in the shock tube which migrates toward the closed end of the tube and that in turn leads to the reflection of shock. Due to the boundary layer interaction with the reflected shock, the bifurcation of shock wave takes place. The bifurcated shock wave then approaches the contact surface and shock train is generated. Till date only a few studies have been conducted to investigate this shock train phenomenon inside the shock tube. For the present study a computational fluid dynamics （CFD） analysis has been performed on a two dimensional axi-symmetric model of a shock tube using unsteady, compressible Navier-Stokes equations. In order to investigate the detailed characteristics of shock train, parametric studies have been performed by varying different parameters such as the shock tube length, diameter, pressure ratio used inside the shock tube.

关键词： Shock tube Reflected shock wave Boundary layer separation Contact surface Shock train

A Study of the Vortical Flow over a Delta Wing with a Leading Edge Extension

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Journal of Thermal Science 2003年第4期12卷 299-303页

作者： Heuy-Dong kim Young-Ki Lee tae-ho kim Myoung-Hwan Sohn School of Mechanical Engineering Andong National University Andong 760-749 KoreaSchool of Mechanical Engineering Andong National University Andong 760-749 KoreaSchool of Mechanical Engineering Andong National University Andong 760-749 KoreaDepartment of Aerospace Engineering Korean Air Force Academy Chongwon-gun ChungBook-Do 363-849 Korea

The present paper describes computational and experimental work on the vortex flow characteristics of a sharp-edged delta wing with a leading edge extension (LEX). Experiment was carried out using a low-speed wind tunnel that has a test section of 3.5 m(W)×2.45 m(H)×8.7 m(L). The angle of attack of the delta wing ranges from 10° to 30°. The free stream velocity is fixed at 20 m/s, which corresponds to Reynolds number of 0.88×106. Computations using the mass-averaged implicit 3D Navier-Stokes equations were applied to predict the complicated vortical flow over the delta wing. The governing equations were discretized in space using a fully implicit finite volume differencing formation. The standard k-e turbulent model was employed to close the governing equations. The present computations predicted the experimented flow field with a good accuracy.

关键词： delta wing leading edge extension (LEX) vortex core vortex strength.

Comparison Between Full-Scale and Model Experiments of Oil Fences

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China Ocean Engineering 2009年第4期23卷 657-668页

作者： tae ho kim Duck Jong JANG Kyong Uk YANG Sun Chol NA Dae An kim School of Marine Technology Chonnam National UniversityYeosu Department of Maritime Police Science Chonnam National UniversityYeosu Korea Marine Environment Management Corporation

This study examines the performance of an air expansion oil fence system as deployed in two different configurations. Geometric and tension characteristics of the oil fence are investigated for （1） the system attached to two vessels and （2） the system attached to one vessel with spreading devices. Since full-scale testing can be time consuming and expensive, another component of the study was to examine how well models would perform. A scaling technique was developed and a set of experiments were conducted with a 1/20-th scale model of the oil fence in a towing tank facility. Performance resalts from the model tests were compared with those conducted at sea. The tension （N） in the full-scale results were represented by R = avb, where v is the current velocity in m/s and the values for a and b used for comparison purposes. Both sets of full-scale and model tests were conducted with an oil fence opening of 120 m and 160m. In the full-scale experiment with spreading devices attaahed to the forward ends of the oil fence, the horizontal distance of the spreading devices has a tendency to linearly increase as the current velocity increases when the warp length is as short as 50 m, but to linearly decrease as the current velocity increases when the warp length is extended to 100 m and 150 m. The spreading distance at uniform current velocitys in the model test increases as the warp length is extended. While there is no significant difference of spreading distance between the cases of 100 m and 150 m, the spreading distance becomes shorter when the warp length is 50 m.

关键词： oil fence spreading devices tension horizontal distance

Synthesis and characterization of red-emitting Yb/ho-CaSiO3 upconversion phosphors

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Progress in Natural Science:Materials International 2022年第5期32卷 594-601页

作者： Bina Chaudhary Yuwaraj K.Kshetri Dhani Ram Dhakal Soo Wohn Lee tae-ho kim Department of Fusion Science and Technology Sun Moon University Research Center for Green Advance Materials Sun Moon University Department of Environmental and Bio-Chemical Engineering Sun Moon University

host material plays an important role in obtaining efficient photon upconversion and downshifting ***, fluoride and oxyfluoride glasses-based materials are used for high-efficiency photon ***, the poor thermal stability of fluoride glasses and the toxicity of fluorine ions limit their applications. In this report, Yb/ho-doped CaSiO3wollastonite phosphors have been demonstrated as efficient red-emitting upconversion phosphors. The phosphors have been synthesized by microwave hydrothermal process followed by heat treatment at 1050°C in the air environment. 2M phase of the β-wollastonite has been confirmed by X-ray diffraction and Raman spectroscopy while the existence of the Yb and ho dopants in the CaSiO3lattice has been confirmed by X-ray photoelectron spectroscopy. The synthesized samples showed strong red upconversion emission centered at 662 nm and near-infrared downshifting emissions at 2016 nm upon 980 nm excitation. The emissions were found to depend significantly on the ho concentration. Temporal evolution of the main emission bands was investigated to show that the energy transfer upconversion from Yb to ho ions was responsible for the efficient upconversion and downshifting phenomenon.

关键词： Wollastonites Upconversion Downshifting Red-emitting phosphors

Spectroscopic properties of Er3+/ho3+/Tm3+ doped α-SiAlON ceramics under 793 nm excitation

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Progress in Natural Science:Materials International 2021年第6期31卷 891-897页

作者： Bina Chaudhary Dhani Ram Dhakal tae-ho kim Soo Wohn Lee Yuwaraj K.Kshetri Department of Fusion Science and Technology Sun Moon University Research Center for Eco-Multifunctional Nano Materials Sun Moon University Department of Environment and Bio-Chemical Engineering Sun Moon University

This paper reports the first demonstration of super broadband infrared downshifting emission extending from1640 nm to 2200 nm with the full width at half maximum of ～ 417 nm in lanthanides(Er3+, ho3+, and Tm3+)-doped α-SiAlON ceramics upon 793 nm excitation. Using α-Si3N4ceramic as a precursor the lanthanides-dopedα-SiAlON ceramics were synthesized by the hot-press method. The lanthanides induced no significant secondary phases in the sintered α-SiAlON ceramics. Strong two-photon upconversion emission bands centered at 547,671 and 694 nm have also been observed upon 793 nm excitation. The time-resolved measurements of the upconversion emissions confirm that the efficient energy transfer among the Er3+, ho3+and Tm3+ions as well as the ground state absorption in Er3+and Tm3+are responsible for the observed spectroscopic properties.

关键词： α-SiAlON Upconversion Downshifting 793 nm excitation

Blue TiO2 polymorph: An efficient material for dye-sensitized solar cells fabricated using a low-temperature sintering process

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Progress in Natural Science:Materials International 2018年第5期28卷 548-553页

作者： Huy Hao Nguyen Gobinda Gyawali tae ho kim Sami Bin Humam Soo Wohn Lee Department of Environmental and Bio-chemical Engineering Sun Moon University Division of Basic Engineering Sun Moon University Division of Mechanics and ICT Convergence Engineering Sun Moon University

Recently,surface-disordered or non-stoichiometric TiO2,such as blue TiO2(B-TiO2),has received much attention owing to its unique properties,such as structural disorder near the surface and the existence of Ti3+ions and oxygen ***,surface-disordered TiO2has been applied for microwave absorption,photocatalysis,in photoelectrochemical sensors and rechargeable lithium-ion *** this work B-TiO2,a polymorph consisting of nanoparticles,nanotubes and nanosheets,was successfully synthesized and employed as a semiconductor layer in dye-sensitized solar cells(DSSCs)fabricated using a low-temperature heat treatment process(120°C).Based on the analyses of the experimental results regarding the structure and those from the characterization of B-TiO2,and its application to DSSCs,it has been found that the B-TiO2material has an effect on electron-hole pair *** conversion efficiency of the B-TiO2DSSC(BTiO2-DSSC)was 6.18%,whereas that of the TiO2-P25 DSSC(P25-DSSC)was 3.61%,and that of the TiO2polymorph DSSC(PTiO2-DSSC)which is the precursor of B-TiO2was 4.51%.

关键词： Surface-disordered TiO2 Blue TiO2 Dye-sensitized solar cell(DSSC) Oxygen vacancy Efficiency