• Journal of Advanced Marine Engineering and Technology
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• v.20 no.4
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• pp.20-26
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• 1996

Recently, for the speed control of a diesel engine, some methods using the modern control theory such as LQ control technique, or $\textit{H}_{\infty}$control theory etc., have been reported. However, most of speed controlers of a diesel engine ever developed are still using the PID control algorithm. And, as another approach to the speed control of a diesel engine, the authors proposed already a new method to adjust the parameters of the PID controller by a model matching method. In the previous paper, the authors confirmed that the proposed new method is superior to Ziegler & Nichols's method through the analysis of results of the digital simulations under the assumption that the parameters of a diesel engine are known exactly. But, actually, it is very difficult to find out the value of parameters of a diesel engine accurately. And the parameters of a diesel engine are changigng according to the operating condition of a diesel engine. So, in this paper, a method to estimate the parameters of the PID controller for the speed control of a diesel engine by means of the model matching method are proposed. Also, the digital simulations are carried out in cases either with or without measurement noise. And this paper confirms that the proposed method here is superior to Ziegler & Nichols's method through the analysis of the characteristics of indicial responses.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.4
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• pp.27-35
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• 1996

The ship's propulsion efficiency depends upon a combibation of engine and propeller. The propeller has better efficiency as the engine has lower rotational speed. This situation led the engine manufacures to design the engine that has lower speed, longer stroke and a small number of cylinders. With this new trends the conventional mechanical-hydrualic governors for engine speed control have been replaced by digital speed controllers which adopted the PID control or the optimal control algorithm. But these control algorithms have not enough robustness to suppress the variations of the delay-time and the parameter perturbation especially in low speed engine. In this study we consider the perturbations of the engine parameters as the modeling uncetainties and design a robust speed controller for marine medium speed diesel engine by means of $ extit{H}_{infty}$control theory having the central solution. By comparing the results of the robust speed controller with those of mechanical governor and PID controller, the validity of the robust speed controller under parameter variations is confirmed. The speed control of the experimental diesel engine of carried out using actuator which is composed of PWM signal generator and D.C servo motor.

• YAKHAK HOEJI
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• v.32 no.1
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• pp.86-94
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• 1988

Some rheological properties of subfractions for dextran in the molecular weights range from $3{\times}10^4$ to $2{\times}10^6$ was investigated at room temperature. The dependence of the viscosity on concentration, shear rate, pH & ionic strength, temperature and solvent effect was observed. From the experimental data the Mark-Houwink viscosity equation in water at $25^{\circ}C$ was determined for samples having the molecular weight ranging from $3{\times}10^4$ to $2{\times}10^6$ as$[{\eta}]=3.1{\times}10^{-3}\;Mw^{0.39}(in\;dl/g)$. The intrinsic stiffness of the dextran backbone was estimated by evaluating the 'characteristic ratio' $C_{\infty}$, which is below the 0.082. In the concentrated region, the viscosity was decreased with increasing shear rate and was exponentially decreased with raising temperature, the viscosity showed the maximum value at neutral condition. From the experimental data, it was concluded that dextran chain, linked by the ${\alpha}-1$, 6-glucosidic linkage, behaves like a flexible random coil chain in aqueous solution, dextran solutions were pseudoplastic power law fluids among the empirical models of non-Newtonian behavior. Urea was an active reagent which increases the viscosity and swells dextran while pyrididine and glycerol were inactive reagents. Also, it could be estimated that the formation of gel structure is promote to the neutral state, the molecular weight larger than $2{\times}10^5$, when electrolytic concentration is IN and Ureas is use to solvent.

• Journal of Drive and Control
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• v.12 no.3
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• pp.1-10
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• 2015

In this paper, the authors propose a method to easily recognize and reproduce the robot motion made by an operator. This method is targets for applications similar to painting and welding, and it is based on a process of that identifies a family of plants, by control design and by conducting an experimental evaluation. In this study, the models and controllers for all joints of 3DOF robot system are obtained individually. And a robust control system for motion control of the individual joints is designed based on $H_{\infty}$ control framework. An experimental comparison is made between the proposed control method and existing PID control method. And the results indicate that the proposed designing method is more efficient and useful than conventional method.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.153-153
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• 2016

최근 지구온난화 및 기후변화의 영향으로 수재해가 증가하고 있으며, 강우의 경향성이 변화하고 있다. 태풍 및 집중호우로 인한 피해보다 장기간의 연속적인 강우의 발생으로 인한 피해가 더욱 크며, 기존 수공구조물의 설계기준은 연속적인 호우로 인한 피해를 고려하지 못하고 있는 실정이다. 거대홍수란 집중호우, 태풍, 이상홍수 및 돌발홍수로 인한 홍수피해의 여파가 끝나기도 전에 또 다른 강우사상으로 인하여 거대한 홍수가 발생하는 시나리오적 상황을 의미한다. 본 연구에서는 기상청에서 제공하는 한강권역 30년 동안의 (1986 ${\infty}$ 2015년) 강우자료를 이용하여 거대홍수 발생횟수, 경향성, 설계기준을 초과하여 발생하는 거대홍수 초과빈도를 분석하였다. 최소 무강우 시간 정의(Inter Event Time Definition, IETD)를 이용하여 거대홍수를 산정하고, Mann-Kendall test 및 이중누가우량분석(double mass analysis)을 통하여 거대홍수의 경향성 분석을 실시하였다. 본 연구의 결과는 기존 수공구조물의 설계기준의 취약점을 보완할 수 있을 것이라 판단되며, 태풍, 집중호우, 거대홍수 등으로 발생하는 홍수피해를 줄이기 위한 방재 사업의 우선순위 결정에 대한 근거 자료로 활용할 수 있을 것이라 기대된다.

• Journal of the Chungcheong Mathematical Society
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• v.24 no.1
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• pp.19-34
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• 2011

A bounded linear operator T on a complex Banach space X is said to have property (I) provided that T has Bishop's property (${\beta}$) and there exists an integer p > 0 such that for a closed subset F of ${\mathbb{C}}$ ${X_T}(F)={E_T}(F)=\bigcap_{{\lambda}{\in}{\mathbb{C}}{\backslash}F}(T-{\lambda})^PX$ for all closed sets $F{\subseteq}{\mathbb{C}}$, where $X_T$(F) denote the analytic spectral subspace and $E_T$(F) denote the algebraic spectral subspace of T. Easy examples are provided by normal operators and hyponormal operators in Hilbert spaces, and more generally, generalized scalar operators and subscalar operators in Banach spaces. In this paper, we prove that if T has property (I), then the quasi-nilpotent part $H_0$(T) of T is given by $$KerT^P=\{x{\in}X:r_T(x)=0\}={\bigcap_{{\lambda}{\neq}0}(T-{\lambda})^PX$$ for all sufficiently large integers p, where ${r_T(x)}=lim\;sup_{n{\rightarrow}{\infty}}{\parallel}T^nx{\parallel}^{\frac{1}{n}}$. We also prove that if T has property (I) and the spectrum ${\sigma}$(T) is finite, then T is algebraic. Finally, we prove that if $T{\in}L$(X) has property (I) and has decomposition property (${\delta}$) then T has a non-trivial invariant closed linear subspace.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.63-74
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• 1999

A sliding mode fuzzy control (SMFC) algorithm is presented for vibration of large structures. Rule-base of the fuzzy inference engine is constructed based on the sliding mode control, which is one of the nonlinear control algorithms. Fuzziness of the controller makes the control system robust against the uncertainties in the system parameters and the input excitation. Non-linearity of the control rule makes the controller more effective than linear controllers. Design procedure based on the present fuzzy control is more convenient than those of the conventional algorithms based on complex mathematical analysis, such as linear quadratic regulator and sliding mode control(SMC). Robustness of presented controller is illustrated by examining the loop transfer function. For verification of the present algorithm, a numerical study is carried out on the benchmark problem initiated by the ASCE Committee on Structural Control. To achieve a high level of realism, various aspects are considered such as actuator-structure interaction, modeling error, sensor noise, actuator time delay, precision of the A/D and D/A converters, magnitude of control force, and order of control model. Performance of the SMFC is examined in comparison with those of other control algorithms such as $H_{mixed 2/{\infty}}$ optimal polynomial control, neural networks control, and SMC, which were reported by other researchers. The results indicate that the present SMFC is an efficient and attractive control method, since the vibration responses of the structure can be reduced very effectively and the design procedure is simple and convenient.

• Korean Journal of Veterinary Research
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• v.51 no.4
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• pp.253-257
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• 2011

Amikacin is a semisynthetic derivative of kanamycin and primarily active against aerobic Gram-negative-pathogens with limited activity against Gram-positive bacteria. Meager study was reported on pharmacokinetic data on multi-days administration of amikacin. Hence, pharmacokinetics study was done in five clinically healthy goats (n = 5), after intravenous bolus injection of amikacin sulfate at the dose rate of 10 mg/kg body weight daily for three consecutive days. The amikacin concentrations in plasma and pharmacokinetics-parameters were analyzed by using microbiological assay technique and noncompartmental open-model, respectively. The mean peak plasma concentrations (Mean ${\pm}$ SD) of amikacin at time zero ($Cp^{0}$) was $114.19{\pm}20.78$ and $128.67{\pm}14.37{\mu}g/mL$, on day 1st and 3rd, respectively. The mean elimination half-life ($t_{1/2}ke$) was $1.00{\pm}0.28h$ on day 1st and $1.22{\pm}0.29h$ on day 3rd. Mean of area under concentration-time curve ($AUC_{0{\rightarrow}{\infty}}$) was $158.26{\pm}60.10$ and $159.70{\pm}22.74{\mu}g.h/mL$, on day 1st and 3rd respectively. The total body clearance ($Cl_{B}$) and volume of distribution at steady state (Vdss) on day 1st and 3rd were $Cl_{B}=0.07{\pm}0.02$ and $0.06{\pm}0.01L/h.kg$ and $Vdss=0.10{\pm}0.03$ and $0.11{\pm}0.05L/kg$, respectively. No-significant difference was noted in both drug-plasma concentration and pharmacokinetics-parameters, respectively. Amikacin concentration in plasma was found higher up-to 4 h and 6 h onward on down-ward trends favour to reduce toxicity. Which also support the pharmacokinetic-pharmacodynamic way of dosing of aminoglycosides and hence, amikacin may be administered 10 mg/kg intravenously daily to treat principally Gram-negative pathogens and limitedly Gram-positive-pathogens.

• Bulletin of the Korean Mathematical Society
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• v.55 no.3
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• pp.957-965
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• 2018

We study the class $C{\mathcal{V}} ({\Omega})$ of analytic functions f in the unit disk ${\mathbb{D}}=\{z{\in}{\mathbb{C}}$ : ${\mid}z{\mid}$ < 1} of the form $f(z)=z+{\sum}_{n=2}^{\infty}a_nz^n$ satisfying $$1+\frac{zf^{{\prime}{\prime}}(z)}{f^{\prime}(z)}{\in}{\Omega},\;z{\in}{\mathbb{D}}$$, where ${\Omega}$ is a convex and proper subdomain of $\mathbb{C}$ with $1{\in}{\Omega}$. Let ${\phi}_{\Omega}$ be the unique conformal mapping of $\mathbb{D}$ onto ${\Omega}$ with ${\phi}_{\Omega}(0)=1$ and ${\phi}^{\prime}_{\Omega}(0)$ > 0 and $$k_{\Omega}(z)={\displaystyle\smashmargin{2}{\int\nolimits_{0}}^z}{\exp}\({\displaystyle\smashmargin{2}{\int\nolimits_{0}}^t}{\zeta}^{-1}({\phi}_{\Omega}({\zeta})-1)d{\zeta}\)dt$$. Let $z_0,z_1{\in}{\mathbb{D}}$ with $z_0{\neq}z_1$. As the first result in this paper we show that the region of variability $\{{\log}\;f^{\prime}(z_1)-{\log}\;f^{\prime}(z_0)\;:\;f{\in}C{\mathcal{V}}({\Omega})\}$ coincides wth the set $\{{\log}\;k^{\prime}_{\Omega}(z_1z)-{\log}\;k^{\prime}_{\Omega}(z_0z)\;:\;{\mid}z{\mid}{\leq}1\}$. The second result deals with the case when ${\Omega}$ is the right half plane ${\mathbb{H}}=\{{\omega}{\in}{\mathbb{C}}$ : Re ${\omega}$ > 0}. In this case $CV({\Omega})$ is identical with the usual normalized class of convex univalent functions on $\mathbb{D}$. And we derive the sharp upper bound for ${\mid}{\log}\;f^{\prime}(z_1)-{\log}\;f^{\prime}(z_0){\mid}$, $f{\in}C{\mathcal{V}}(\mathbb{H})$. The third result concerns how far two functions in $C{\mathcal{V}}({\Omega})$ are from each other. Furthermore we determine all extremal functions explicitly.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3777-3787
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• 2012

Three kinds of 3D isomorphous and isostructural coordination polymers, namely, $\{[Ln_2(PDA)_3(H_2O)_3]{\cdot}0.25H_2O\}_{\infty}$ (Ln = La(1), Sm(2), and Gd(3)) ($PDA^{2-}$ = pyridine-2,6-dicarboxylate anion) have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. In these MOFs, Ln(III) centers adopt eight-coordinated and nine-coordinated with the $N_1O_7$ and $N_2O_7$ donor sets to construct distorted trianglar dodecahedron geometry and tricapped trigonal prism configurations, respectively. Based on the building block of tetranuclear homometallic $Ln_4C_4O_8$ unit (16-membered ring), 1-3 are connected into highly ordered 2D sheets via O-C-O linkers and further constructed into 3D architectures through hydrogen bonds. Crystallographic parameters suggest that the lanthanide contraction effect exist in these coordination polymers. Luminescent properties of the lanthanide-based MOFs (metal-organic frameworks) have been measured at room temperature, which reveal that they presenting ionselective characters toward certain metals, such as $Mg^{2+}$, $Cd^{2+}$ and $Pb^{2+}$ ions.