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최민기,김민,강태운 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
산업발전 및 각종 자원 등의 수요가 증가함에 따라 오수, 폐기물, 매연 등이 배출되고 시간이 지남에 따라 더욱 심화되어 인간 생활에 직접적인 영향을 준다. 특히 암모니아를 발생시키는 농축산업과 화학공정 등에서 효율적으로 암모니아를 제거하기 위해 이온교환막에 금속착물을 도입했다. 암모니아 가스와 암모니아성 질소를 효율적으로 제거하기 위하여 방사선 그라프트막을 이용해 양이온막과 음이온 막을 제조 후 Cu, Al, Ag 금속이온을 착물시켜 기체상태와 액체상태의 암모니아의 흡착 특성에 대하여 알아보았다.
최민기,김주용 한국섬유공학회 2019 Fibers and polymers Vol.20 No.8
This study led to the development of an electro-coaxial air blown spinning system, which involves using a sheathcorenozzle for electrospinning, and the authors examined how the morphology of the fabricated nanofiber changedaccording to four process parameters. When the morphology changes of the nanofiber were analyzed using different processparameters, the increase in air flow rate was accompanied by the decrease in fiber diameter owing to shear force. On the otherhand, as the concentration of the solution increased, the diameter of the nanofiber increased owing to the force of attractionbetween polymer chains. In addition, the diameter of the nanofiber decreased at a higher voltage owing to increasingorientation and the whipping phenomenon. Finally, when the tip to collector distance (TCD) was too close, it was difficult toobtain a perfect fiber, and the fiber produced in such a scenario was excessively thick and flat. However, when the TCDexceeded a certain value, no change in diameter of the nanofiber was observed. An intelligent prediction model needs to bedeveloped to apply the results of this study to real processes.
최민기,구자양,안민우,이원영 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.4
We systematically investigated the effects of grain boundaries (GBs) at the electrolyte/cathode interface of two conventional electrolyte materials, i.e., yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC). We deposited additional layers by pulsed laser deposition to control the GB density on top of the polycrystalline substrates, obtaining significant improvements in peak power density (two-fold for YSZ and three-fold for GDC). The enhanced performance at high GB density in the additional layer could be ascribed to the accumulation of oxygen vacancies, which are known to be more active sites for oxygen reduction reactions (ORR) than grain cores. GDC exhibited a higher enhancement than YSZ, due to the easier formation, and thus higher concentration, of oxygen vacancies for ORR. The strong relation between the concentration of oxygen vacancies and the surface exchange characteristics substantiated the role of GBs at electrolyte/cathode interfaces on ORR kinetics, providing new design parameters for highly performing solid oxide fuel cells.
최민기,박호원,이시영,김해니,이주현 대한소아치과학회 2024 大韓小兒齒科學會誌 Vol.51 No.2
This study aimed to compare the fluoride-releasing ability and degree of microbial attachment of a newly developed glass-hybrid restorative material (GH) with those of a high-viscosity glass ionomer (HvGIC), resin-modified glass ionomer (RMGI), and composite resin (CR). In addition, the correlation between fluoride-releasing ability and microbial attachment between materials was evaluated. Specimens were prepared in a disc shape and divided into 4 groups according to the materials (GH, HvGIC, RMGI, and CR). The fluoride release experiments were performed in each group (n = 15). The amount of fluoride released was measured on days 1, 3, 7, 14, 28, and 42 after storage. For the microbial attachment experiment, 12 specimens were produced per group using Mutans Streptococci (S.mutans ), a cariogenic microorganism. S. mutans was cultured on the specimens for 24 hours, and the number of bacteria was measured. GH had the highest cumulative fluoride release and showed a significant difference when compared with RMGI (p = 0.001) and CR (p < 0.0001). Microbial attachment was the lowest in GH; however, no significant difference was observed between the materials (p = 0.169). There was no significant correlation between fluoride release from materials and microbial attachment (p > 0.05). From this perspective, remineralization of low-mineralized areas could be expected due to the high fluoride release of GH, and the effect of delaying the progression of dental caries could be predicted from the low cariogenic microbial attachment. Therefore, GH might be a useful restorative material for treating immature permanent teeth with hypomineralized enamel. However, further studies are needed about the degree of remineralization of hypomineralized areas after restoration and the capacity to recharge fluoride.
인화성액체를 촉진제로 사용한 방화화재의 감식기법에 관한 연구
최민기,한동훈,최돈묵 한국화재소방학회 2014 한국화재소방학회논문지 Vol.28 No.4
Flammable liquids residues in fire debris and pyrolysis products of flammable materials were analyzed by using Gasdetecting tube, Gas Chromatograph/Mass Spectrometers (GC/MS), and Pyrolyzer. Comparison studies between chemicalcomponents detected in debris fired with and without Flammable liquids were performed. Though Flammable liquidswere not present in debris, Gas detecting tube colors were also changed. Chemical components produced from conventionalcombustions were different from those produced from pyrolysis. Due to the difference of the reaction conditionsbetween combustions and pyrolysis, different chemical products were produced. Petrochemical products of PVC woodlinoleumblock could produce ignitable chemicals, such as toluene, ethylbenzene, undecane, and dodecane. So, for betterfire investigation more consideration of those chemicals will be porformed. 본 연구에서는 연소잔류물에 남아있는 미세한 인화성액체의 성분을 검출하기 위해 가스검지관, Gas Chromatograph/Mass Spectrometer (GC/MS), 열분해분석장비를 활용하였다. 일반적으로 연소했을 경우와 인화성액체를 첨가하여 연소된경우의 성분분석결과를 비교하였다. 결과적으로 인화성액체를 첨가하지 않고 연소 후 생성된 화재잔해물에서도 가스검지관이 반응하는 것을 확인할 수 있었다. 일반적인 연소와 열분해를 통해 생성된 화학성분의 차이가 있었으며, 이는 연소 환경의 차이로 인한 것으로 판단된다. 대표적인 석유화학제품인 우드데코타일(PVC) 시료는 인화성액체를 첨가하지않고 일반적으로 연소시켰을 경우에도 감정인의 정확한 판단을 방해할 수 있는 방해물질인 Toluene, Ethylbenzene,Undecane, Dodecane 등이 검출되는 것을 확인하였다.
기체구 분사 모델을 이용한 CNG DI 엔진의 연소특성 수치해석
최민기 한국분무공학회 2019 한국액체미립화학회지 Vol.24 No.4
This paper describes numerical study of combustion characteristics in CNG(compressed natural gas) DI(direct injection) engine using gaseous sphere injection model. Simulations were conducted using KIVA-3V Release 2 code. Gaseous sphere injection model, which is modified model of liquid fuel injection, was used to simulate the CNG direct injection. Until now, a very fine mesh smaller than the injector nozzle has been required to resolve the gas-jet inflow boundary. However, the gaseous sphere injection model simulates gaseous fuel injection using a coarse mesh. This model injects gaseous spheres as in liquid fuel injection and the gaseous spheres evaporate together without the latent heat of evaporation. Therefore, it does not require a very fine mesh and reduce calculation time. Combustion simulation were performed under various injection timings and injection pressures.