• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.688-693
• /
• 2007

Most frame structures cannot be manufactured in a single-piece form. Ideally, when a structure is built up by assembling multi pieces, assembly at the joints should be rigidly performed enough to have almost full stiffness, which is difficult for practical reasons such as manufacturing cost and time. In this research, we aim to develop a manufacturability-oriented compliance-minimizing topology optimization using a ground beam model incorporating additional zero-length elastic joint elements. In the present formulation, design variables control the stiffness of zero-length elastic joints, not the stiffness of beams. Because joint stiffness values at the converged state can be utilized to select candidate assembly locations and their strengths, the technique is extremely useful to design multi-piece frame structures. An optimal layout is also extracted based on the stiffness values.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.2
• /
• pp.82-89
• /
• 1985

A new non-inferior solution is obtained by investigating method of weight p- norm to explain the conception of MCO (multiple criterion optimization) problem. And then the optimum non-inferior solution is obtained by the weight minimization method applied to objective function of MOSFET NAND rATEAlso this weight minimization method using weight P- norm methods can be applied to non-convex objective function. The result of this minimization method shows the efficiency in comparison with that of Lightner.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.9
• /
• pp.796-803
• /
• 2008

Ultrasonic testing uses the directivity of the ultrasonic wave, which propagates in on direction. The directivity is expressed as the relationship between the propagate direction and its sound pressure. The directivity of an ultrasonic wave is related to the choice of probe arrangement, testing sensitivity and scanning pitch and correct measurement of defect size and location. This paper describes on the directivity measurement of ultrasonic wave using the visualization method. The directivity of shear wave emitted from the angle beam transducer were constant during propagation. The difference of directivity was existed between 2 MHz and 4 MHz angle beam transducers. When these experimental results were compared with the theory which was based on the continuous wave, it showed good agreement with theoretical directivity on the principal lobe.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.1
• /
• pp.9-17
• /
• 1992

Proper resource allocation is also a very important topic in power system problems, especially in operation and planning. One such is optimal maintenance problem in operation and planning. Least cost and highest reliability should be the subjects to be pursued. A probabilistic operation simulation model developed recently by authors is applied to the proboem of optimal maintenance scheduling. Three different methods are compared, marginal maintenance cost, levelized risk and maintenance space. The method by the marginal maintenance costs shows the least cost, the highest reliability and the highest maintenance outage rates. This latter characteristics may considerably influence the results of genetation planning, because the usual maintenance outages obtained from the other methods have shown to be lower.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.33 no.10
• /
• pp.396-401
• /
• 1984

This paper present a method of using simplified models for deriving suboptimal controllers to the original higher-order systems. Routh approximation method is a very useful technique for reducing the order of a linear systems. This method dose not require a knowlege of system eigenvalues and eigenvectors and possesses many desirable features such as preservation of reduced order model stability and minimum computational requirements. These properties are utilized to derive suboptimal controllers in this paper. In order to implement htese ocntrollers on the original system, the relationship between the state vectors of the original system and the reduced order models is required. A procedure fir evaluating an approximate aggregation matrix is also developed. A numerical example is given for the illustration of this method, shich is compared with the existing Model aggregation method in the resultant figures.

• Proceedings of the KAIS Fall Conference
• /
• 2011.12a
• /
• pp.266-268
• /
• 2011

본 논문은 폐타이어 열분해 잔류물인 char를 이용하여 수증기 활성화법으로 활성탄을 제조하였다. 활성화 온도가 증가할수록 비표면적은 증가하였으나 활성화 시간에 따른 비표면적은 3시간에서 최대를 보인 후 시간이 지속되면 비표면적은 감소하였다. 본 연구결과, 타이어열분해 잔류물 char를 이용한 활성탄 제조에 있어 최적의 실험조건은 활성화 온도 $850^{\circ}C$, 활성화 시간 3시간, 승온속도 $5^{\circ}C/min$이었으며 이 조건에서 제조한 활성탄의 비표면적은 $517.6m^2/g$으로 나타났다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.10
• /
• pp.7061-7070
• /
• 2015

Multi-Response Surface Optimization aims at finding the optimal setting of input variables considering multiple responses simultaneously. The Weighted Mean Squared Error (WMSE) minimization approach, which imposes a different weight on the two components of mean squared error, squared bias and variance, first obtains WMSE for each response and then minimizes all the WMSEs at once. Most of the methods proposed for the WMSE minimization approach to date are classified into the prior preference articulation approach, which requires that a decision maker (DM) provides his/her preference information a priori. However, it is quite difficult for the DM to provide such information in advance, because he/she cannot experience the relationships or conflicts among the responses. To overcome this limitation, this paper proposes a posterior preference articulation method to the WMSE minimization approach. The proposed method first generates all (or most) of the nondominated solutions without the DM's preference information. Then, the DM selects the best one from the set of nondominated solutions a posteriori. Its advantage is that it provides an opportunity for the DM to understand the tradeoffs in the entire set of nondominated solutions and effectively obtains the most preferred solution suitable for his/her preference structure.

• Geophysics and Geophysical Exploration
• /
• v.22 no.4
• /
• pp.186-194
• /
• 2019

Deterministic optimization, commonly used to find the geophysical inverse solutions, have its limitation that it cannot find the proper solution since it might converge into the local minimum. One of the solutions to this problem is to use global optimization based on a stochastic approach, among which a large number of particle swarm optimization (PSO) applications have been introduced. In this paper, I developed a geophysical inversion algorithm applying PSO method for the layered-earth resistivity inversion of the small-loop electromagnetic (EM) survey data and carried out numerical inversion experiments on synthetic datasets. From the results, it is confirmed that the PSO inversion algorithm could increase the inversion success rate even when attempting the inversion of small-loop EM survey data from which it might be difficult to find a best solution by applying the Gauss-Newton inversion algorithm.

• 한국생물공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.341-345
• /
• 2003

Effect of immobilization on the production of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) by Nicotiana tabacum cells was investigated using polyurethane foam as immobilization matrices. The cell activity and the hGM-CSF production were maintained for 16 days in spite of 3 times of media exchange. Under the same conditions of temperature and agitation rate, maximum concentrations of hGM-CSF in a 500-mL spinner flask and 100-mL Erleuneyer flasks were 17.3 ${\mu}g/L$ and 9.8 ${\mu}g/L$, respectively. Consequently high hGM-CSF production could be possible in spinner flask when the rate and amount of media exchange were optimized.

• Journal of the Korean Chemical Society
• /
• v.33 no.4
• /
• pp.388-398
• /
• 1989

A continuous-automated method for the determination of nitrite ion using gas-sensing membrane electrode was developed. The pH electrode of tubular PVC membrane type was used as a detector of this system. The slope of linear response of the electrode measured at optimum conditions for the continuous-automated determination of nitrite ion was 63.5 mV/decade. The concentration range of linear response and detection limit were 2.5 ${\times}10^{-4}{\sim}\;7.5{\times}10^{-2}$M and $8.0{\times}10^{-5}$M, respectively. This detection system was not only less interfering to acidic gas species than other methods but also less time consumable for determination.