• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.1
• /
• pp.41-52
• /
• 1992

An algorithm of transforming continuous-time state feedback gains into equivalent discrete-time feedback gains or vice versa is proposed using bilinear transformation. The proposed method is evaluated experimentally by an application control of a mobile crane system which is implemented by 16bits micro computer with A/D and D/A converters. It has been shown from the experimental result that the transformed feedback gains are virtually identical to the optimal discrete gain over range of significant sampling time. Since the transformed matrix is composed by a distinct relationship between continuous-time gain and discrete-time gain, it is noted that the proposed method can be regarded as an explicit gain transformation method compared to the other methods using series expansion.

• Natural Product Sciences
• /
• v.21 no.2
• /
• pp.141-145
• /
• 2015

Hesperidin, which is the most abundant flavonoid of Citrus unshiu (Rutaceae), has been reported to possess diverse activities and widely used as functional foods and cosmetics. For the development of functional products, extraction procedure is indispensable. Extraction conditions affect the composition of extract as well as its biological activity. Therefore, we tried to optimize extraction conditions such as extraction solvent, extraction time and extraction temperature for maximum yield of hesperidin using response surface methodology with threelevel-three-factor Box-Behnken design (BBD). Regression analysis showed a good fit of the experimental data and the optimal condition was obtained as ethanol concentration, 59.0%; temperature $71.5^{\circ}C$ and extraction time, 12.4 h. The hesperidin yield under the optimal condition was found to be $287.8{\mu}g$ per 5 mg extract, which was well matched with the predicted value of 290.5 μg. These results provides optimized extraction condition for hesperidin and might be useful for the development of hesperidin as functional products like health supplements, cosmetics and medicinal products.

• Journal of KSNVE
• /
• v.11 no.1
• /
• pp.147-155
• /
• 2001

This paper is concerned with the real-time automatic tuning of the multi-input multi-output positive position feedback controllers for smart structures by the genetic algorithms. The genetic algorithms have proven its effectiveness in searching optimal design parameters without falling into local minimums thus rendering globally optimal solutions. The previous real-time algorithm that tunes a single control parameter is extended to tune more parameters of the MIMO PPF controller. We employ the MIMO PPF controller since it can enhance the damping value of a target mode without affecting other modes if tuned properly. Hence, the traditional positive position feedback controller can be used in adaptive fashion in real time. The final form of the MIMO PPF controller results in the centralized control, thus it involves many parameters. The bounds of the control Parameters are estimated from the theoretical model to guarantee the stability. As in the previous research, the digital MIMO PPF control law is downloaded to the DSP chip and a main program, which runs genetic algorithms in real time, updates the parameters of the controller in real time. The experimental frequency response results show that the MIMO PPF controller tuned by GA gives better performance than the theoretically designed PPF. The time response also shows that the GA tuned MIMO PPF controller can suppress vibrations very well.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.516-519
• /
• 2004

As the optical communication industry is developed, the demand of optical communication part is increasing. ZrO$_2$ ceramic ferrule is very important part which can determines the transmission efficiency and information quality to connect the optical fibers. In general ZrO$_2$ ceramic ferrule is manufactured by grinding process because the demands precision is very high. And the co-axle grinding process of ZrO$_2$ ceramic ferrule is to make its concentricity all of uniform before centerless grinding. This paper deals with the analysis of the process parameters such as grinding wheel speed, grinding feedrate and regulating wheel speed as influential factors, on the concentricity and surface finish developed based on Taguchi's experimental design methods. Taguchi s tools such as orthogonal array, signal-to-noise ratio, factor effect analysis, etc. have been used for this purpose optimal condition has been found out. Thus, if possible be finding highly efficient and quality grinding conditions.

• Journal of Korean Traditional Oncology
• /
• v.20 no.1
• /
• pp.11-21
• /
• 2015

Objectives : The cancer incidence and cancer burden is increasing. In addition, the use of botanical agents in cancer care is increasing. This article aims to review a research strategy for botanical agents. Methods : The clinical studies of anticancer botanical agents and the papers about clinical research methodology of botanical agents were reviewed. Results : In phase I study, safety confirmation, optimal dose determination and drug interaction study are important. Most botanical agents have low toxicity and some have non-monotone dose response. Therefore, dose-response curve must be evaluated separately from the dose-toxicity curve to determine optimal dose. Although anticancer botanical agents can't shrink tumor size rapidly, they do extend survival. So, in phase II study, response should be evaluated by the survival. Conclusions : Clinical research of botanical agents in cancer is different from traditional methods and strategies. Considering the characteristics of botanical agents and experimental mechanism is necessary in conducting botanical based clinical trials.

• Journal of the Korean Society of Physical Medicine
• /
• v.6 no.4
• /
• pp.497-504
• /
• 2011

Purpose : Chronic cervical pain is a common source of disability in society. There has been no research regarding the amount of pressure for the deep cervical flexors during cranio-cervical flexion exercise (CCFE). The purpose of this study is to determine optimal pressure levels to facilitate deep cervical muscles (longus colli & longus capitis) during cranio-cervical flexion exercise, using ultrasound measurement of the muscles. Methods : Using a cross-sectional design, the study was performed in an experimental group of 19 subjects (7 men, 12 women) with no cervical pain. Participants were instructed to perform the CCFE, and during the five incremental stages of the test, changes in thickness, as compared to resting baseline values, were measured using ultrasonography for sternocleidomastoid muscle (SCM) and deep cervical muscles (DCF). Results : Both DCF and SCM muscles demonstrated an increase in recruitment with each progressive phase of the test. In comparing the different pressure increments, the most significant changes found in DCF thickness were between phase 2 and phase 3 (p<.05). However no differences were found between pressure increments for SCM thickness (p>.05). Conclusion : The results suggest 26 mm Hg as the optimal pressure level during cranio-cervical flexion exercise for facilitation of deep cervical flexor.

• Journal of the Korean Society of Food Culture
• /
• v.28 no.2
• /
• pp.204-211
• /
• 2013

The purpose of this study was to determine the optimal mixing conditions for two different amounts of turmeric (Curcuma longa L.) powder and olive oil for the processing of chicken sausage. The experiment was designed according to the central composite design of response surface methodology, with ten experimental points, including two replicates for turmeric powder and olive oil. The physicochemical and mechanical analysis of each sample, including water holding capacity, moisture content, lightness, redness, yellowness, hardness, chewiness, gumminess, and cohesiveness, showed significant differences. The results from sensory evaluations also showed very significant differences in color, flavor, tenderness, chewiness, and overall quality. The optimal formulation, calculated by numerical and graphical methods, was 1.89 g of turmeric powder and 9.77 g of olive oil. Under these conditions, the model predicted pH-6.01, salinity-0.20, WHC-94.88, $L^*$ value-61.13, $b^*$ value-37.45, hardness-$36.66{\times}10^2$ (N), springiness-8.70 (mm), chewiness-$26.88{\times}10^3$ ($N{\times}mm$).

• Korean Management Science Review
• /
• v.29 no.1
• /
• pp.143-152
• /
• 2012

Location area planning (LAP) problem is to partition the cellular/mobile network into location areas with the objective of minimizing the total cost in location management. The minimum cost has two components namely location update cost and searching cost. Location update cost is incurred when the user changes itself from one location area to another in the network. The searching cost incurred when a call arrives, the search is done only in the location area to find the user. Hence, it is important to find a compromise between the location update and paging operations such that the cost of mobile terminal location tracking cost is a minimum. The complete mobile network is divided into location areas. Each location area consists of a group of cells. This partitioning problem is a difficult combinatorial optimization problem. In this paper, we use particle swarm optimization (PSO) to obtain the best/optimal group of cells for 16, 36, 49, and 64 cells network. Experimental studies illustrate that PSO is more efficient and surpasses those of precious studies for these benchmarking problems.

• International Journal of Reliability and Applications
• /
• v.15 no.2
• /
• pp.125-150
• /
• 2014

Accelerated life tests (ALTs) are extensively used to determine the reliability of a product in a short period of time. Test units are subject to elevated stresses which yield quick failures. ALT can be carried out using constant-stress, step-stress, progressive-stress, cyclic-stress or random-stress loading and their various combinations. An ALT with linearly increasing stress is ramp-stress test. Much of the previous work on planning ALTs has focused on constant-stress, step-stress, ramp-stress schemes and their various combinations where the stress is generally increased. This paper presents an optimal design of ramp soak-stress ALT model which is based on the principle of Thermal cycling. Thermal cycling involves applying high and low temperatures repeatedly over time. The optimal plan consists in finding out relevant experimental variables, namely, stress rates and stress rate change points, by minimizing variance of reliability function with pre-specified mission time under normal operating conditions. The Burr type XII life distribution and time-censored data have been used for the purpose. Burr type XII life distribution has been found appropriate for accelerated life testing experiments. The method developed has been explained using a numerical example and sensitivity analysis carried out.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.6
• /
• pp.894-902
• /
• 2003

Prebiotics (peptides, N-acetyglucoamine, fructo-oligosaccharides, isomalto-oligosaccharides and galactooligosaccharides) were added to skim milk in order to improve the growth rate of contained Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium longum and Bifidobacterium bifidum. The purpose of this research was to study the potential synergy between probiotics and prebiotics when present in milk, and to apply modern optimization techniques to obtain optimal design and performance for the growth rate of the probiotics using a response surface-modeling technique. To carry out response surface modeling, the regression method was performed on experimental results to build mathematical models. The models were then formulated as an objective function in an optimization problem that was consequently optimized using a genetic algorithm and sequential quadratic programming approach to obtain the maximum growth rate of the probiotics. The results showed that the quadratic models appeared to have the most accurate response surface fit. Both SQP and GA were able to identify the optimal combination of prebiotics to stimulate the growth of probiotics in milk. Comparing both methods, SQP appeared to be more efficient than GA at such a task.