• Transactions on Electrical and Electronic Materials
• /
• 제18권5호
• /
• pp.287-297
• /
• 2017

Novel power system stabilizers (PSSs) have been proposed to effectively dampen low frequency oscillations (LFOs) in multi-machine power systems and have attracted increasing research interest in recent years. Due to this attention, recently, fractional order controllers (FOCs) have found new applications in power system stability issues. Here, a tilt-integral-derivative power system stabilizer (TID-PSS) is proposed to enhance the dynamic stability of a multi-machine power system by providing additional damping to the LFOs. The TID is an extended version of the classical proportional-integral-derivative (PID) applying fractional calculus. The design of the proposed three-parameter tunable TID-PSS is systematized as a nonlinear time domain optimization problem in which the tunable parameters are adjusted concurrently using a modified group search optimization (MGSO) algorithm. An integral of the time multiplied squared error (ITSE) performance index is considered as the objective function. The proposed stabilizer is simulated in the MATLAB/SIMULINK environment using the FOMCON toolbox and the dynamic performance is evaluated on a 3-machine 6-bus power system. The TID-PSS is compared with both classical PID-PSS (PID-PSS) and conventional PSS (CPSS) using eigenvalue analysis and time domain simulations. Sensitivity analyses are performed to assess the robustness of the proposed controller against large changes in system loading conditions and parameters. The results indicate that the proposed TID-PSS provides the better dynamic performance and robustness compared with the PID-PSS and CPSS.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2001년도 추계학술발표대회
• /
• pp.363-366
• /
• 2001

본 연구는 Lentinus edodes의 액체배양을 통하여 물리 ${\cdot}$ 화학적인 방법을 이용, 고농도의 탄수화물 복합효소를 얻어 hemicellulose와의 반응을 거쳐 고수율의 아라비 녹실란을 얻는데 그 목적이 있다. 온도 $24^{\circ}C$, pH 5.5. working volume 100mL, 접종비 5%. 200rpm이며 가장 적합한 C-source 로서는 glucose가 선택되었으며 N - source로서는 yeast extract가 선택되었다.

• 한국미생물·생명공학회지
• /
• 제27권5호
• /
• pp.404-409
• /
• 1999

The most favorable nitrogen source for the production of protease by Aspergillus oryzae PF was 2% soybean flour among sodium nitrate, ammonium sulfate, defatted soybean, skim milk, casein, peptone, and yeast extract. The production of protease from A. oryzae PF was higher at the concentration of 2% lactose than at variable concentration of glucose, sucrose, soluble starch, corn starch, potato starch, wheat starch, rice starch, cellulose, and gum arabic. Protease production was affected by the concentration of KH2PO4, Triton X-100, CaCo3, and MgSO4, and it was the highest at the highest at the concentration of 3% KH2PO4, 0.01% Triton X-100, 0.3% CaCO3, and 0.06% MGSO4.

• 한국미생물·생명공학회지
• /
• 제17권5호
• /
• pp.407-411
• /
• 1989

Oxytetracycline 생산균주인 Streptomyces rimosus를 maltose 2%, NH$_4$Cl 0.5%, yeast extract 0.4 %, MGSO$_4$.7$H_2O$ 0.2% 조성의 배지를 배양초기 PH 6.5로 하여 3$0^{\circ}C$, 72시간 진탕배양하여 얻은, 세포외 protease를 유안분획, Sephadex A-50 이온교환, Sephadex G-100 gel 여과를 행하여 정제하였다. 효소의 최적온도는 5$0^{\circ}C$이며, 최적 pH는 8.0이었으며, Co$^{2+}$ 이온에 의해 활성화되며 Hg$^{2+}$, Fe$^{2+}$ 및 EDTA에 의해 저해를 받으며 casein 분자량을 23,600으로 추정하여 구한 Km값은 2.7$\times$$10^{-4}$M이었다.