• JSTS:Journal of Semiconductor Technology and Science
• /
• v.16 no.5
• /
• pp.535-541
• /
• 2016

A low phase noise META-VCO based-on meta-structure was designed using 65 nm CMOS process. We used a meta-structure to get good phase noise characteristics. The measured phase noises are -67.8 dBc/Hz, -96.37 dBc/Hz, and -107.37 dBc/Hz at 100 kHz, 1 MHz, and 10 MHz offset respectively. The META-VCO operates 8.45~8.77 GHz according to VCTRL, and the output power is -19.12 dBm. The power consumption is 28 mW with 1.2-V supply voltage. The calculated FOM is -140.76 dBc/Hz.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.5
• /
• pp.85-95
• /
• 2021

Structure design sensitivity was evaluated using the orthogonal array experimental method for passive-type deck support frame (DSF) developed for float-over installation of the offshore plant. Moreover, approximation characteristics were also reviewed based on various meta-models. The minimum weight design of the DSF is significantly important for securing both maneuvering performance and buoyancy of a ship equipped with the DSF and guaranteeing structural design safety. The performance strength of the passive type DSF was evaluated through structure analysis based on the finite element method. The thickness of main structure members was applied to design factors, and output responses were considered structure weight and strength performances. Quantitative effects on the output responses for each design factor were evaluated using the orthogonal array experimental method and analysis of variance. The optimum design case was also identified from the orthogonal array experiment results. Various meta-models, such as Chebyshev orthogonal polynomial, Kriging, response surface method, and radial basis function-based neural network, were generated from the orthogonal array experiment results. The results of the orthogonal array experiment were validated using the meta-modeling results. It was found that the radial basis function-based neural network among the meta-models could approximate the design space of the passive type DSF with the highest accuracy.

• (The)Korea Educational Review
• /
• v.22 no.3
• /
• pp.67-87
• /
• 2016

The paper has tried to analyze the sense of 'meta-praxis' in the educational discourse. Against the dichotomy of theory vs practice, the senses of practice and 'meta-praxis' can be hold under the Greek conception of human activities such as theoria, poiesis and praxis. We can establish the meaning of meta-praxis contrasted with one of metaphysics, not with one of meta-theory. Some significant points included in the concept then have been minutely examined so as to lead us to get the recursive structure and practicability. The Buddhist notion such as 'Well-Rounded Discretion' and the linguistic one such as 'Grand Father' throw light on the educational practice and discourse. These are ones that we never fail to recognize in terms of 'meta-praxis'.

• Journal of Ocean Engineering and Technology
• /
• v.34 no.5
• /
• pp.316-324
• /
• 2020

This paper presents comparative studies of reliability analysis and meta-modeling using the sampling method of Monte Carlo simulation for the structure design of an automatic ocean salt collector (AOSC). The thickness sizing variables of structure members are considered as random variables. Probabilistic performance functions are selected from strength performances evaluated via the finite element analysis of an AOSC. The sampling methods used in the comparative studies are simple random sampling and Sobol sequences with varied numbers of sampling. Approximation methods such as the Kriging model is applied to the meta-model generation. Reliability performances such as the probability failure and distribution are compared based on the variation of the sampling method of Monte Carlo simulation. The meta-modeling accuracy is evaluated for the Kriging model generated from the Monte Carlo simulation and Sobol sequence results. It is discovered that the Sobol sequence method is applicable to not only to the reliability analysis for the structural design of marine equipment such as the AOSC, but also to Kriging meta-modeling owing to its high numerical efficiency.

• Smart Structures and Systems
• /
• v.32 no.2
• /
• pp.123-133
• /
• 2023

This paper proposes a thermography-based coating thickness estimation method for steel structures using model-agnostic meta-learning. In the proposed method, a halogen lamp generates heat energy on the coating surface of a steel structure, and the resulting heat responses are measured using an infrared (IR) camera. The measured heat responses are then analyzed using model-agnostic meta-learning to estimate the coating thickness, which is visualized throughout the inspection surface of the steel structure. Current coating thickness estimation methods rely on point measurement and their inspection area is limited to a single point, whereas the proposed method can inspect a larger area with higher accuracy. In contrast to previous ANN-based methods, which require a large amount of data for training and validation, the proposed method can estimate the coating thickness using only 10- pixel points for each material. In addition, the proposed model has broader applicability than previous methods, allowing it to be applied to various materials after meta-training. The performance of the proposed method was validated using laboratory-scale and field tests with different coating materials; the results demonstrated that the error of the proposed method was less than 5% when estimating coating thicknesses ranging from 40 to 500 ㎛.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.12
• /
• pp.2305-2310
• /
• 2011

This paper describes a design of dual band balanced amplifier using a lefted handed meta-material transmission line structure for high frequency application. Meta-material transmission lines have been known to have dual band frequency responses. A dual band branch line hybrid coupler is designed using the meta-material transmission lines, and measured at first. Two identical dual band amplifiers are also designed, built and tested using the same meta-material transmission structure. The proposed dual band balanced amplifier is composed of those dual band branch line hybrid coupler and amplifiers. In order to suggest an design example, a prototype of dual band balanced amplifier is built and measured at the dual frequencies, 1800MHz($f_1$) and 2300MHz($f_2$). The simulation and measurement show that the fabricated balanced amplifier operates well at the desired dual frequencies bands with the gain of 11.12dB and 17.67dB at $f_1$ and $f_2$, respectively, with a good agreement with the simulation results.

• Journal of Ocean Engineering and Technology
• /
• v.29 no.5
• /
• pp.351-358
• /
• 2015

This paper presents an effective damage detection method using a meta model. A meta model is an approximation model that uses the relations between the design and response variables. It eliminates the need for repetitive analyses of computationally expensive models during the optimization process. In this study, a response surface model was employed as the meta model. The surface model was estimated using the correlation of the stiffness and natural frequencies of the structures. The locations and values of the damages were identified using a meta model-based damage detection method. Two numerical examples (a cantilever beam and jacket structure) were considered to verify the performance of the proposed method. As a result, the damages to the structures were accurately detected.

• Journal of Convergence for Information Technology
• /
• v.11 no.1
• /
• pp.109-117
• /
• 2021

In this paper, the meta-model based approximate optimization was carried out for the structure design of an ocean automatic salt collector in order to minimize the structure weight. The structural analysis was performed by using the finite element method to evaluate the strength performance of the ocean automatic salt collector in its initial design. In the structural analysis, it was evaluated the strength performance of the design load conditions. The optimum design problem was formulated so that design variables of main structure thickness would be determined by minimizing the structure weight subject to strength performance constraints. The meta-models used in the approximate optimization were the response surface method, Kriging model, and Chebyshev orthogonal polynomials. Regarding to the numerical characteristics, the solution results from approximate optimization techniques were compared to the results of non-approximate optimization. The Chebyshev orthogonal polynomials among the meta-models used in the approximate optimization showed the most appropriate optimum design results for the structure design of the ocean automatic salt collector.

• Journal of information and communication convergence engineering
• /
• v.6 no.4
• /
• pp.470-474
• /
• 2008

A well-designed computer network technology produces benefits on several fields within the organization, between the organizations(suborganizations) or among different organizations(suborganizations). Network technology streamlines business processes, decision process. Graphs are useful data structures capable of efficiently representing a variety of networks in the various fields. Metagraph is a like graph theoretic construct introduced recently by Basu and Blanning in which there is set to set mapping in place of node to node as in a conventional graph structure. Metagraph is thus a new type of data structure occupying its popularity among the computer scientists very fast. Every graph is special case of Metagraph. In this paper the authors introduce the notion of Meta-Networking as a new network technological representation, which is having all the capabilities of crisp network as well as few additional capabilities. It is expected that the notion of meta-networking will have huge applications in due course. This paper will play the role of introducing this new concept to the network technologists and scientists.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.51-52
• /
• 2013

In this paper, circularly polarized microstrip for the S-band with a center frequency of 3.5GHz have been studied using the meta-structure of the resonator Designed antenna using CST studio, the meta-structure resonator was etched in the ground plane for miniaturization and circulary polarization was implemented with slot in center of the patch.