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이정헌,조현정,Bayaraa Sukhbaatar,정현성 한국표면공학회 2025 한국표면공학회지 Vol.58 No.2
The development of efficient catalysts for the hydrogen evolution reaction (HER) plays a critical role in water splitting for green hydrogen production. Due to the high cost of platinum, which is commonly used as an HER catalyst, extensive research has recently been conducted on non-noble metal-based catalysts. In this study, NiS2 catalysts were synthesized via a hydrothermal method as non-noble metal HER catalysts, and their electrochemical catalytic properties were investigated. The morphology of the hydrothermally synthesized NiS2 catalysts was controlled to form either hollow or non-hollow structures by varying the amount of sulfur precursor, L-cysteine. Structural analysis and electrochemical performance comparisons were conducted accordingly. Linear sweep voltammetry (LSV) revealed that the hollow-structured NiS2 catalysts exhibited improved overpotential performance. Furthermore, kinetic analysis using Tafel plots indicated enhanced hydrogen adsorption kinetics in the hollow-structured NiS2 catalysts compared to their non-hollow counterparts.
이정헌,이규성,이진웅,김득중 대한치주과학회 2017 Journal of Periodontal & Implant Science Vol.47 No.6
Purpose: The physicochemical properties of a xenograft are very important because they strongly influence the bone regeneration capabilities of the graft material. Even though porcine xenografts have many advantages, only a few porcine xenografts are commercially available, and most of their physicochemical characteristics have yet to be reported. Thus, in this work we aimed to investigate the physicochemical characteristics of a porcine bone grafting material and compare them with those of 2 commercially available bovine xenografts to assess the potential of xenogenic porcine bone graft materials for dental applications. Methods: We used various characterization techniques, such as scanning electron microscopy, the Brunauer-Emmett-Teller adsorption method, atomic force microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and others, to compare the physicochemical properties of xenografts of different origins. Results: The porcine bone grafting material had relatively high porosity (78.4%) and a large average specific surface area (SSA; 69.9 m2/g), with high surface roughness (10-point average roughness, 4.47 μm) and sub-100-nm hydroxyapatite crystals on the surface. Moreover, this material presented a significant fraction of sub-100-nm pores, with negligible amounts of residual organic substances. Apart from some minor differences, the overall characteristics of the porcine bone grafting material were very similar to those of one of the bovine bone grafting material. However, many of these morphostructural properties were significantly different from the other bovine bone grafting material, which exhibited relatively smooth surface morphology with a porosity of 62.0% and an average SSA of 0.5 m2/g. Conclusions: Considering that both bovine bone grafting materials have been successfully used in oral surgery applications in the last few decades, this work shows that the porcine-derived grafting material possesses most of the key physiochemical characteristics required for its application as a highly efficient xenograft material for bone replacement.
양구 특산 백색 고령토의 사료 내 첨가가 육계의 육성성적, 영양소 이용율과 계육조성에 미치는 영향
이정헌,유영범,이준엽,오상집 강원대학교 동물생명과학연구소(구 강원대학교 동물자원공동연구소) 2007 동물자원연구 Vol.18 No.-
This study was conducted to evaluate the effect of dietary Yanggu original white kaolin supplementation on the growth performances, nutrients utilizability and meat composition of broiler. A total of 260 broiler chicks was alloted to 5 treatments with 4 replications and 13 chicks per replication. In addition to control group that fed diet without any kaolin supplementation, the treatments are designated by dietary supplementation as follows; white kaolin 400 mesh 1%(T1), white kaolin 10,000 mesh 1%(T2), white kaolin 400 mesh 0.8% + probiotics 0.2%(T3) and kaolin rizen(T4). The specific volume of 10,000 mesh white kaolin was higher than that of 400 mesh white kaolin (p<0.05) with no difference in pH between two different size white kaolins. Pellet durability of kaolins supplemented diet was improved, regardless of fat addition, compared to that of no kaolin supplemented diet. Both weight gain and feed intake of broilers in all the kaolin supplemented treatments were higher than that of control during d 0~21 period (p<0.05) but with no differences during d 22~40, On the other hand, kaolin supplementation into the control diet did not affect F/G of young broiler during d 1~21. Overall F/G of broiler was decreased by kaolin supplementation. Although there was no difference on ether extract, crude ash, total CHO and dry matter utilizabilities among all treatments, both crude protein and energy utilizabilities were improved by kaolin supplementation. Crude protein content of both broiler thigh and breast was the lowest in the kaolin and probiotics combined supplemented group(T3). In conclusion, the supplementation of physico-chemically treated white kaolin does affect growth performances, nutrients utilizability and meat composition of broilers. Therefore, the kaolin can be considered as a beneficial feed additive to improve broiler productivity.