Gas turbine engines are widely used as prime movers of generator and propulsion system in warships. This study addresses the problem of designing a DS-based PID controller for speed control of the LM-2500 gas turbine engine used for propulsion in warships. To this end, we first derive a dynamic model of the LM-2500 using actual sea trail data. Next, the PRC (process reaction curve) method is used to approximate the first-order plus time delay (FOPTD) model, and the DS-based PID controller design technique is proposed according to approximation of the time delay term. The proposed controller conducts set-point tracking simulation using MATLAB (2016b), and evaluates and compares the performance index with the existing control methods. As a result of simulation at each operating point, the proposed controller showed the smallest in , which means that the rpm does not change rapidly. In addition, IAE and IAC were also the smallest, showing the best result in error performance and controller effort.

본 연구에서는 막 축전식 탈이온 공정에 적용하기 위해 온도와 시간을 달리하여 술폰화 Poly(VDF-co-hexafluoropropylene) copolymers (PVDF-co-HFP)을 합성 후 캐스팅법에 의해 양이온교환막이 제조되었다. 술폰화 PVDF (SPVDF) 는 Fourier-transform infrared (FT-IR), 1H Nuclear magnetic resonance (1H NMR)를 통해 구조확인을 하였고, X-ray Photoelectron Spectroscopy (XPS)를 통해 화학조성에 대한 정량적 분석을 하였다. 막 성능은 함수율 및 이온교환용량과 전기 저항을 측정하였고. 60°C에서 7시간 술폰화한 SPVDF 멤브레인이 이온교환용량 0.89 meq/g, 함수율 21.5%, 전기저항 3.70 Ω ⋅cm2로 가장 우수하였다. 수중 이온제거 특성을 막 축전식 탈이온 방법(MCDI)으로 전압(0.9~1.5 V), 유속(10~40 mL/min)을 변수로 SPVDF의 탈염 특성을 확인하여 MCDI 공정에 적용가능 여부를 평가하였다. MCDI 충방전 시험 결과 최대 탈염제거 율은 62.5%이었다.

Methanol was directly produced by the partial oxidation of methane with four-component mixed oxide catalysts. Four-component(Mo-Bi-Cr-Si) mixed oxide catalysts were prepared by the co-precipitation and sol-gel methods. The catalyst prepared by the sol-gel method showed about eleven times higher surface area than that prepared by the co-precipitation method. From the O2-TPD experiment of the prepared catalysts, it was proven that there exists two types of oxygen species, and the oxygen species that participates in the partial oxidation reaction is the lattice oxygen desorbing around 750℃. The optimum reaction condition for methanol production was 420°C, 50 bar, flow rate of 115 mL/min, and CH4/O2 ratio of 10/1.5, providing methane conversion and methanol selectivity of 3.2 and 26.7%, respectively.

페롭스카이트 촉매와 Mo, Bi를 기본으로 하는 복합 산화물 촉매를 이용하여 천연가스의 주성분인 메탄의 부분산화를 통하여 메탄올을 직접 합성하였다. 페롭스카이트(ABO₃) 촉매는 A 및 B site 성분을 변화시키면서 사과산법으로 제조하였으며, Mo, Bi를 기본으로 하는 3성분계 복합 산화물 촉매는 공침법으로 제조하여 반응특성을 살펴보았다. 페롭스카이트 촉매에서 A site에 알칼리 금속인 Sr을, B site에 전이금속인 Cr을 도입한 SrCrO₃ 촉매가 400℃에서 메탄올 선택도 11%로 가장 우수한 결과를 보였다. Mo, Bi를 기본으로 하는 3성분계 복합 산화물 촉매의 경우 모든 촉매에서 메탄 전환율에는 큰 차이를 보이지 않았으며, Cr을 첨가한 Mo-Bi-Cr 복합 산화물 촉매가 400℃에서 메탄올 선택도 15.3% 로 가장 우수한 결과를 나타냈다. 3성분계 복합 산화물 촉매에서 촉매의 활성과 메탄올 선택도는 촉매의 표면적에 정비례하였다.

Aqueous gold nanoparticle dispersion was synthesized by chemical reduction method using diethanolamine as reducing agent and polyethyleneimine as dispersion stabilizer. The synthesis conditions for the stable dispersion of the gold nanoparticle suspension were determined by changing the amount of the reducing agent and dispersant during the wet chemical synthesis procedures. The face centered cubic lattice structure of the gold nanoparticles was confirmed by using X-ray diffraction and the morphologies of the nanoparticles were observed by transmission electron microscope. The synthesized gold nanoparticle dispersion was concentrated by evaporating the dispersion medium at room temperature followed by the addition of ethyleneglycol as humectant for the increase of the elastic properties to obtain gold nanoparticle inks for direct ink writing process. The line patterns were obtained with the gold nanoparticle inks during the writing procedures and the morphologies of the fine patterns were observed by scanning electron microscope.

Abstract Direct solid state synthesis by hot pressing has been applied in order to produce high efficiency bulk specimens. Single phase with 98.5% of theoretical density was successfully produced by direct hot pressing of elemental powders containing 1.2 at.% excess Zn. Thermoelectric properties as a function of temperature were investigated from room temperature to 600 K and compared with results of other studies. Transport properties at room temperature were also evaluated. Thermoelectric properties of single phase materials produced by direct synthesis were measured and are comparable to the published data. Direct solid state synthesis by hot pressing provides a promising processing route in this material

Magnetite (Fe3O4) has been prepared directly to avoid the reduction process prior to the H2 production from the high temperature water gas shift reaction of the simulated waste derived synthesis gas. Citric acid has been employed as a complexing agent for the direct synthesis of magnetite. Notably, without the reduction process, the catalyst prepared at the citric acid molar ratio of 1.0 showed 80% CO conversion at 350℃ at a gas hourly space velocity of 40,057 h-1.