Highly safe lithium-ion batteries (LIBs) are required for large-scale applications such as electrical vehicles and energy storage systems. A highly stable cathode is essential for the development of safe LIBs. LiFePO4 is one of the most stable cathodes because of its stable structure and strong bonding between P and O. However, it has a lower energy density than lithium transition metal oxides. To investigate the high energy density of phosphate materials, vanadium phosphates were investigated. Vanadium enables multiple redox reactions as well as high redox potentials. LiVPO4O has two redox reactions (V5+/V4+/V3+) but low electrochemical activity. In this study, LiVPO4O is doped with fluorine to improve its electrochemical activity and increase its operational redox potential. With increasing fluorine content in LiVPO4O1-xFx, the local vanadium structure changed as the vanadium oxidation state changed. In addition, the operating potential increased with increasing fluorine content. Thus, it was confirmed that fluorine doping leads to a strong inductive effect and high operating voltage, which helps improve the energy density of the cathode materials.

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.

This paper investigates to design a controller for maritime autonomous surface ship (MASS) by means of adaptive super-twisting algorithm (ASTA). A input-out feedback linearization method is considered for multi-input multi-output (MIMO) system. Sliding Mode Controller (SMC) is suitable for MASS subject to ocean environments due to its robustness against parameter uncertainties and disturbances. However, conventional SMC has inherent disadvantages so-called, chattering phenomenon, which resulted from the high frequency of switching terms. Chattering may cause harmful failure of actuators such as propeller and rudder of ships. The main contribution of this work is to address an appropriate controller for MASS, simultaneously controls surge and yaw motion in severe step inputs. Proposed control mechanism well provides convergence bewildered by external disturbances in the middle of steady-state responses as well as chattering attenuation. Also, the adaptive algorithm is contributed to reducing non-overestimated value of control gains. Control inputs of surge and yaw motion are displayed by smoother curves without excessive control activities of actuators. Finally, no overshoot can be seen in transient responses.

In anion exchange membrane fuel cells, Pd nanoparticles are extensively studied as promising non-Pt catalysts due to their electronic structure similar to Pt. In this study, to fabricate Pd nanoparticles well dispersed on carbon support materials, we propose a synthetic strategy using mixed organic ligands with different chemical structures and functions. Simultaneously to control the Pd particle size and dispersion, a ligand mixture composed of oleylamine(OA) and trioctylphosphine(TOP) is utilized during thermal decomposition of Pd precursors. In the ligand mixture, OA serves mainly as a reducing agent rather than a stabilizer since TOP, which has a bulky structure, more strongly interacts with the Pd metal surface as a stabilizer compared to OA. The specific roles of OA and TOP in the Pd nanoparticle synthesis are studied according to the mixture composition, and the oxygen reduction reaction(ORR) activity and durability of highly-dispersed Pd nanocatalysts with different particles sizes are investigated. The results of this study confirm that the Pd nanocatalyst with large particles has high durability compared to the nanocatalyst with small Pd nanoparticles during the accelerated degradation tests although they initially indicated similar ORR performance.

본 연구에서는 후처리 기능화를 통해 아민이 함유된 ZIF-8-A를 제조하고, 이를 이산화탄소 흡착제로 적용하였다. 첨가한 3-amino-1,2,4-triazole의 함량에 따라 15, 37, 61, 그리고 74 %의 아민기를 포함한 ZIF-8-A를 제조하였으며, 다양한 분석을 통해 이들의 물성특성을 조사하였다. 그 결과, 아민 함량에 따라 ZIF-8-A의 게이트 크기 조절되고 가스 투과도 및 선택도에 영향을 미치는 것을 확인하였다. ZIF-8-A61%는 기존 ZIF-8 대비 CO2/N2 및 CO2/CH4에 대한 선택도가 3.4 및 4.7배 증가하였으며, 이는 구조내 가스 투과를 위한 게이트 사이즈의 조절 및 아민과 이산화탄소의 상호작용에 기인한 것으로 판단하였다.

To search a new pig pheromonal odorant, the N1-allyl-N2-(tetrahydrofuran-2-ylmethyl)oxalamide molecule predicted by ligand based approach and molecular docking method was synthesized by nucleophilic addition-elimination reaction (AdNU-E) between N-allyloxalamic acid ethylester and tetrahydrofurylmethylamine. According to the evaluation results for efficiency of pig estrus control, the synthesized pig pheromonal N1-allyl-N2-(tetrahydrofuran-2- ylmethyl)oxalamide molecule advanced the estrus by 11.3 days (p<0.05) compared with the non-pheromone group. And from these results, it is predicted that the synthesized pig pheromonal compound will be able to increase the reproduction efficiency of pig.

The effects of reaction temperature and precursor concentration on the microstructure and magnetic properties of nanoparticles synthesized as final products of iron acetylacetonate in chemical vapor condensation (CVC) were investigated. Pure phase was obtained at temperature above and crystallite size of nanoparticles decreased with lowering precursor concentration. Also, the coercivity decreases with decreasing crystallite size of nanopowder. The lowest coercivity was 7.8 Oe, which was obtained from the nanopowder sample synthesized at precursor concentration of 0.3M. Then, the crystallite size of nanoparticles was 8.8 nm.