Jo Mar 24, 2026
Selective laser melting (SLM) technique is one of the most representative advanced manufacturing techniques.
Since SLM process parameters affect the multiple quality attributes of SLM parts, it is very important to perform optimization and effect evaluation of SLM process parameters. The SLM process optimization problem is ascribable to a multiobjective optimization one for optimizing multiple quality attributes.
Yang Won Chol, a researcher at the Faculty of Material Science and Technology, proposed a reasonable methodology for optimization of multiple quality attributes and effect evaluation of SLM process parameters using a TOPSIS-based comprehensive quality index and Taguchi method, and applied it to determine the optimal values and effects of process parameters such as laser power, scan speed and overlap rate for separately and simultaneously improving the multiple quality attributes such as tensile strength, hardness and relative density of AlSi10Mg alloy fabricated by the SLM.
He found that the optimal values of process parameters are laser power of 320 or 360 W, scan speed of 600 mm/s and overlap rate of 0.35, and the ES ranking of process parameters is scan speed, overlap rate and laser power.
For more information, please refer to his paper “Taguchi optimization and effect evaluation of process parameters using TOPSIS based comprehensive quality index of selective laser melted AlSi10Mg alloy” in “The International Journal of Advanced Manufacturing Technology” (SCI).
...
Jo Mar 23, 2026
Solar hydrogen production by water splitting is one of the promising solutions to mitigate energy crisis and climate change as a green technology to convert solar energy into a form of renewable and storable fuel. Photocatalytic water splitting is considered an appealing approach and an economically feasible means of producing green H2 due to its low cost and simplicity of fabrication.
In the past several decades, many photocatalysts for water photolysis have been developed. However, the number of photocatalysts with water splitting activity under visible light is limited and simultaneous generation of H2 and O2 is almost impossible. Z-scheme water splitting system can alleviate thermodynamic requirements and choice of narrow band gaps materials.
Printable photocatalyst plates have potential usage in water splitting system for practicality of solar hydrogen production. On the printable Z-scheme photocatalyst plates, conductive nanoparticles can be inserted as a conductive mediator between hydrogen evolution photocatalyst (HEP) and oxygen evolution photocatalyst (OEP) to promote water splitting.
Kim Chol Gu, a researcher at the Faculty of Chemical Engineering, proposed a printable SrTiO3:La, Rh/ATO/BiVO4:Mo photocatalyst plate incorporating cost-effective Antimony-doped tin oxide (ATO) nanoparticles as a conductive mediator for Z-scheme water splitting.
The photocatalyst plates achieve an apparent quantum efficiency of 6.8% at a wavelength of 420 nm, with solar-to-hydrogen conversion efficiency (STH) of 0.26%.
For more information, you can refer to his paper “Z-scheme photocatalyst plates using antimony-doped tin oxide (ATO) as a conductive mediator for solar water splitting” in “Chemical papers” (SCI).
...
Jo Mar 22, 2026
Methanol is a very important primary raw material for the petrochemical and energy industries. It is used to produce basic chemicals including formaldehyde, acetic acid, methyl formate, dimethyl ether, methyl and dimethylamineand dimethylamine carbonate and it is widely used in the chemical, pesticide, medical, dye and paint industries.
The ever-increasing production of chemicals creates some serious environmental problems due to the emission of greenhouse gases and wastes, and at present, environmental protection is of great importance for economic development. Therefore, production processes should be designed and operated aiming at reducing environmental pollution, and to this end, the environmental impacts of production processes should be evaluated quantitatively.
Pak Kyong Song, a researcher at the Faculty of Chemical Engineering, evaluated and compared the potential environmental impacts of two gas-to-methanol (GTM) process options according to the CO2 feed location using CO2 recycle ratios.
The results showed that, as the recycle ratio increases, both the potential environment impact (PEI) rate of the chemical process and the energy generation process decrease, and the total rate PEI output of the process and PEI generation rate decrease as a whole.
Also, process option 1 has lower PEI rates than process option 2 and it is therefore more environmentally friendly.
For more information, please refer to his paper “Potential Environmental Impact Evaluation of the Methanol Synthesis Process by Gas-to-Methanol Technology” in “ACS Omega” (SCI).
...
Jo Mar 20, 2026
It is very important to theoretically analyse and numerically simulate the ground stability of welded structures, which are of recent worldwide interest.
Packing density and confining pressure have a great effect on the mechanical behavior of sand. Therefore, several kinds of models have been proposed and each of them has their own features.
Fabric anisotropy variable and density function also have a great effect on the mechanical property of anisotropic sand.
Jong Yong Kwang, a researcher at the Faculty of Material Science and Technology, based on the anisotropic critical state theory (ACST), developed a modified anisotropic hypoplastic model by incorporating the relation between fabric anisotropy variable and density function into the nonlinear part of the constitutive model.
He validated the applicability of the improved model by comparing it with the existing model and experimental data.
The results showed that the modified model can well predict the critical state response of anisotropic sand.
You can find more information in his paper “An Anisotropic Critical State Hypoplastic Model Considering the Relation Between Fabric Anisotropy Variable and Density Function” in “Mechanics of Solids” (SCI).
...
Jo Mar 19, 2026
Developing an effective, cheap and safe hydrogen storage system is one of the key areas for efficient operation of the hydrogen-based economy.
This area has witnessed many successes by new engineering solutions. However, in order to make rapid technological progress, it is necessary to develop novel materials that can outperform the currently used ones.
Perovskite-type compounds for designing and discovering new materials with target functions can be used for luminescence, photocatalytics, photovoltaics and H2 storage applications.
Jo Son Il, a section head at the Faculty of Material Science and Technology, provided atomic insights into materials properties of double perovskite-type hydride LiNaMg2H6 for H2 storage application.
The results showed that LiNaMg2H6 hydride can be a potential H2 storage material because of its high H2 storage capacity, mechanical and dynamical stabilities and suitable H2 desorption temperature.
If further information is needed, please refer to his paper “Atomic insights into the material properties of double-perovskite-type hydride LiNaMg2H6 for H2 storage applications” in “RSC Advances” (SCI).
...
Jo Mar 18, 2026
Transparent conducting oxide (TCO) films have been widely used as transparent electrodes in the optoelectronic devices such as flat panel displays and thin-film solar cells. Among them, Al-doped ZnO (AZO) films are being studied most due to their rich resources of Al and good electrical and optical properties.
The sputtering ambient has an influence on the microstructure, composition and electrical and optical properties of ZnO based films deposited by sputtering.
Some studies showed that adding appropriate amount of H2 into sputtering ambient leads to enhancement of the electrical properties of films. This encouraged many attempts to improve the properties of doped ZnO films by adding H2. However, there is little literature that dealt with the effects of H2 content on the properties of doped ZnO films deposited at low temperature and at high temperature.
Ri Kang Hyon, a section head at the Faculty of Material Science and Technology, compared the influence of H2 addition to sputtering ambient on the microstructural and electrical properties of AZO films deposited by r.f. magnetron sputtering at low temperature (100 ℃) and high temperature (400 ℃).
The results showed that for the AZO films prepared at comparatively low temperature around 100 ℃, small addition of H2 to sputtering ambient was favorable for enhancing the electrical properties of films, but for those at high temperature around 400℃, any addition of H2 was unfavourable at all.
For more information, please refer to his paper “Influence of hydrogen addition to sputtering ambient on the properties of AZO films deposited by sputtering” in “Physica Scripta” (SCI).
...