• Journal of Korean Society of Forest Science
• /
• v.87 no.2
• /
• pp.145-152
• /
• 1998

We conducted this study as a fundamental study on the response of various tree species against acid rain. The tree species used for this study were Zelkova serrata, Robinia pseudoacacia, Quercus acutissima, Prunus serrulata, Ginkgo biloba, Pinus koraiensis and Pinus densiflora. The leaves were examined for the pH changes by treatment time and the chlorophyll content into various pH solution in vitro. The results obtained were as follows ; 1. When the leaves were immersed in the solution of various pH(pH 3.0-pH 6.0) levels, the pH were changed to species specific pH ranges as pH 5.0~pH 5.5 of Z. serrata, pH 5.5~pH 6.0 of R. pseudoacacia, pH 4.5~pH 5.0 of Q. acutissima, pH 5.5~pH 6.0 of P. serrulata, pH 3.5~pH 4.5 of G. biloba, pH 3.5~pH 4.5 of P. koraiensis until 48 hours. However, in case of P. densiflora, it was difficult to find specific pH range of the species. Z. serrata, R. pseudoacacia and P. serrulata showed a little pH increasing by pH 2.0 solution treatment, while other species showed no change by the solution. 2. The amount of chlorophyll contents in Z. serrata, R. pseudoacacia and P. serrulata were decreased after immersing in the pH 2.0 solution. Chlorophyll content was almost constant in other pH levels. Other species showed almost constant chlorophyll contents in various pH levels and treatment time.

• Korean Journal of Food Science and Technology
• /
• v.24 no.3
• /
• pp.232-235
• /
• 1992

Effect of temperature and initial pH were studied on the pH change of MSG solution during heating. The heating temperature and initial pH of 2% MSG solution were in the range of $100{\sim}120^{\circ}C$ and $pH\;2{\sim}9$, respectively. The results showed that the pH of MSG solution was more rapidly decreased as the temperature increased and the initial pH decreased due to pyroglutamic acid formation from MSG thermal degradation. A linear relationship was obtained between pH decreased and logarithmic value of heating time and the decreasing rate constant of pH were calculated from the slope. The pH decreased$({\Delta}pH)$ after 3 hrs of heating was 1.2 at the initial pH 4 and $120^{\circ}C$ and 0.33 at pH 5 and $120^{\circ}C$ while little pH change measured at the range of $pH\;6{\sim}9$. Activation energy calculated for pH decrease during heating was 11.77 and 22.26 kcal/mole at pH 4 and pH 5, respectively.

• Korean Journal of Food Science and Technology
• /
• v.30 no.3
• /
• pp.557-561
• /
• 1998

This study was conducted to investigate the functionality of soybean protein isolates extracted in acidic range (pH 2.0 and 3.0), neutral range (pH 7.0) and alkaline range (pH 10.0 and 12.0). The protein content of soybean protein isolates extracted at pH 3.0 was maximum (93.31%), but that of pH 7.0 was minimum (73.93%). The extraction yield of soybean protein isolates extracted at pH 3.0 was minimum (0.36%), but that of pH 12.0 was maximum (47.54%). The functionality (solubility, water absorption, oil absorption, foam capacity, foam stability, emulsion capacity and gelation) of soybean protein isolates was significantly influenced by pH of extraction medium. The soybean protein isolates extracted at pH 2.0 and 3.0 were more soluble at acidic ranges and those of pH 3.0 and 7.0 were more soluble at neutral ranges, but those of pH 2.0, 3.0, 7.0, 10.0 and 12.0 were more soluble at alkaline ranges than other ranges. The soybean protein isolates extracted at pH 2.0 and pH 12.0 gave greater water absorption, oil absorption and foam capacity than those extracted at pH 3.0, pH 7.0 and pH 10.0. And the emulsion capacity of soybean protein isolates was increased by the increase of extraction pH.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.41 no.5
• /
• pp.19-27
• /
• 2004

A delay dependent fuzzy $H_2/H_{\infty}$ controller design method for delayed fuzzy dynamic systems is considered. Using delay-dependent Lyapunov function, the asymptotical stability and $H_2/H_{\infty}$ performance problem are discussed. A sufficient condition for the existence of fuzzy controller is presented in terms of linear matrix inequalities(LMIs). A simulation example is given to illustrate the design procedures and performances of the proposed methods.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.529-534
• /
• 2005

In this paper, a new type of output feedback control, called a $H_2/H_{\infty}$ fnite memory control (FMC), is proposed for deterministic state space systems. Constraints such as linearity, unbiasedness property, and finite memory structure with respect to an input and an output are required in advance to design $H_2/H_{\infty}$ FMC in addition to the performance criteria in both $H_2$ and $H_{\infty}$ sense. It is shown that $H_2$, $H_{\infty}$, and mixed $H_2/H_{\infty}$ FMC design problems can be converted into convex programming problems written in terms of linear matrix inequalities (LMIs) with some linear equality constraints. Through simulation study, it is illustrated that the proposed $H_2/H_{\infty}$ FMC is more robust against uncertainties and faster in convergence than the existing $H_2/H_{\infty}$ output feedback control schemes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.2 s.93
• /
• pp.128-133
• /
• 2005

An iris-coupled partial H-plane filter as a new type of partial H-plane filter is proposed. The proposed filter can be compared with conventional H-plane filter and uses an iris-type evanescent waveguide as a coupling structure. Filter design technique based on numerical simulation is developed to design and compare the proposed filter and H-plane filter. Designed iris-coupled partial H-plane filter has the same frequency response as that of the conventional H-plane filter while its cross section is one quarter. A good agreement between measurements and theoretical prediction is achieved.

• Journal of the Korean Chemical Society
• /
• v.46 no.5
• /
• pp.427-436
• /
• 2002

Reaction of $trans-[FeHCl(dppe)_2]$ (1) with KSeCN led to the formation of $trans-[FeH(NCSe)(dppe)_2](2).$ Compound 2 $·CH_2Cl_2$ was structurally characterized by X-ray diffraction, in which the hydride ligand appears to be involved in the dihydrogen bonding of the type M-H${\cdot}$${\cdot}$${\cdot}$H-C.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.33B no.5
• /
• pp.10-16
• /
• 1996

In this paper, we consider a generalized mixed H_2/H_{\infty}$ output feedback problem. It is finding an internally stabilizing controller that minimizes a mixed $H_{2}$/ $H_{performance}$ measure. We show that a generalized mixed H_2/H_{\infty}$ system with two exogenous inputs and two controlled signals is transformed into auxiliary system with two exogenous inputs and one controlled signal. The two systems have equivalent performance. Therefore, a complete solution of generalized mixed H_2/H_{\infty}$ output feedback problem is achieved by existing results of mixed H_2/H_{\infty}$ control theory.

• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.7
• /
• pp.578-583
• /
• 2002

This paper presents a method for designing fuzzy $H_2/H_{\infty}$ controllers of nonlinear systems with time varying delay. Takagi-Sugeno fuzzy model is employed to represent nonlinear systems with time varying delay. Using a single quadratic Lyapunov function, the globally exponential stability and $H_2/H_{\infty}$ performance problem are discussed. A sufficient condition for the existence of fuzzy $H_2/H_{\infty}$ controllers is then presented in terms of linear matrix inequalities(LMls). The proposed fuzzy $H_2/H_{\infty}$ controllers minimizes the upper bound on the linear quadratic performance measure.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.560-564
• /
• 1996

A mixed H$^{2}$/$H^{\infty}$ controller design method for linear systems with time delay in all variables and parameter uncertainties in all system matrices is proposed. Robust $H^{\infty}$ performance and H$^{2}$ performance condition that accounts for model-matching of closed loop system and disturbance rejection is also derived. With expressing uncertain system with linear fractional transformation form, we transform the robust stability and performance problem to the H$^{2}$/$H^{\infty}$ optimization problem and design a mixed H$^{2}$/$H^{\infty}$ controller. Using the proposed method, mixed H$^{2}$/$H^{\infty}$ controller for underwater vehicle with time delay and parameter variations are designed. Simulations of a design example with hydrodynamic parameter variations and disturbance are presented to demonstrate the achievement of good robust performance.t performance.ance.