• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.501-510
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• 2000

Recently, advanced signal analysis which is called "time-frequency analysis" has been used widely in nondestructive evaluation applications. Wavelet transform(WT) and Wigner Distribution are the most advanced techniques for processing signals with time-varying spectra. Wavelet analysis method is an attractive technique for evaluation of material characterization nondestructively. Wavelet transform is applied to the time-frequency analysis of ultrasonic echo waveform obtained by an ultrasonic pulse-echo technique. In this study, the feasibility of noise suppression of ultrasonic flaw signal and frequency-dependent ultrasonic group velocity and attenuation coefficient using wavelet analysis of ultrasonic echo waveform have been verified experimentally. The Gabor function is adopted the analyzing wavelet. The wavelet analysis shows that the variations of ultrasonic group velocity and attenuation coefficient due to the change of material characterization can be evaluated at each frequency. Furthermore, to assure the enhancement of detectability and naw sizing performance, both computer simulated results and experimental measurements using wavelet signal processing are used to demonstrate the effectiveness of the noise suppression of ultrasonic flaw signal obtained from austenitic stainless steel weld including EDM notch.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.4
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• pp.201-209
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• 2016

Damages of large embankment dams by recent strong earthquakes in the world highlight the importance of seismic security of dams. Some of recent dam construction projects for water storage and hydropower are located in highly seismic zone, hence the seismic performance evaluation is an important issue. While state-of-the-art numerical analysis technology is generally utilized in practice for seismic performance evaluation of large dams, physical modeling is also carried out where new construction technology is involved or numerical analysis technology cannot simulate the behavior appropriately. Geotechnical centrifuge modeling is widely adopted in earthquake engineering to simulate the seismic behavior of large earth structures, but sometimes it can't be applied for large embankment dams due to various limitations. This study proposes a dynamic centrifuge testing method for large embankment dams and evaluated its applicability. Scaling relations for a case which model scale and g-level are different could be derived considering the stress conditions and predominant period of the structure, which is equivalent to previously suggested scaling relations. The scaling principles and testing method could be verified by modified modeling of models using a model at different acceleration levels. Finally, its applicability was examined by centrifuge tests for an embankment dam in Korea.

• Asian Journal of Innovation and Policy
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• v.10 no.1
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• pp.90-107
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• 2021

This paper analyses how technological capabilities and entrepreneurship of technology-based start-ups affect their performance. In this paper, a multiple regression analysis was conducted on 248 technology-based start-ups. The effects of indicators of technological capacity like R&D intensity, R&D organization, technology competitiveness, patents, and certification were analyzed. Factors affecting sales were R&D intensity and technological competitiveness. Technology competitiveness and patents were the significant factors influencing product competitiveness. The factor that positively influenced organizational performance, customer performance, and achievement of start-up goals was technological competitiveness. The results of such an analysis should be designed to discover and foster long-term innovation potential, rather than relying on short-term financial performance.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.1
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• pp.147-156
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• 2009

The introduction and application of IT(Information Technology) to a company has become to be viewed as a key factor for the business competitiveness and improved productivity. This study presents an approach to evaluation of a company's informatization level, which is especially appropriate for small and medium enterprises. The proposed evaluation method, based on the traditional questionnaire approaches, considers the various characteristics of the company, e.g., types of business, characteristics of customers, and locations of supply chains etc. A web-based system was developed to enable users to obtain the evaluation results from the evaluation method. The system also provides a function to produce valuable strategies for informatization by utilizing the case base which will be cumulated by repetitive evaluation requests. Finally, a real case was analyzed in order to verify the practicality of the evaluation system.

• Journal of the Ergonomics Society of Korea
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• v.30 no.6
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• pp.765-773
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• 2011

Objective: This study aims towards exploring a model of the HCI evaluation methods to improve the usability of mobile device, based on a case of a Mobile PDA system in a Museum context. Background: Mobile PDA systems in a Museum context is widely utilized for the educational purposes, but it is criticized for low usability that the device only play a role in textbooks on legs without any interactive educational activities. Therefore, the usability improvements on the mobile PDA system should be considered. Method 1: This model was developed with a combination of the expert review and the user testing, and with a combination of the qualitative and quantitative studies. In more details, first of all, a qualitative study was conducted as a combination of three different methods: 1) expert review with heuristics, 2) interviews with persons working in a museum, and 3) contextual enquiry. Results 1: The experts review provided with critical usability issues, and the semi-constructive interview helped to understand the background of the mobile device. Lastly, the contextual enquiry showed user experience problems and directions of improving the device from user's perspective. Method 2: Based on the results of the qualitative study, a questionnaire was designed. Results 2: The analysis of the quantitative study was conducted to generalize the problems, and prioritize the direction of improving the device within the limitation of the cost and time in a museum. Conclusion: This study has implications in developing an example of a HCI evaluation model to improve the user experience of the mobile device as well as finding problems and directions of how to improve the mobile PDA systems in the museum. Application: In fact, most of the studies related to the evaluation of the mobile device have been conducted in a laboratory context due to the cost and time. This paper, however, attempted to apply to various HCI research techniques from different constituents in real context.

• Food Science of Animal Resources
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• v.41 no.4
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• pp.563-588
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• 2021

Increasing meat demand in terms of both quality and quantity in conjunction with feeding a growing population has resulted in regulatory agencies imposing stringent guidelines on meat quality and safety. Objective and accurate rapid non-destructive detection methods and evaluation techniques based on artificial intelligence have become the research hotspot in recent years and have been widely applied in the meat industry. Therefore, this review surveyed the key technologies of non-destructive detection for meat quality, mainly including ultrasonic technology, machine (computer) vision technology, near-infrared spectroscopy technology, hyperspectral technology, Raman spectra technology, and electronic nose/tongue. The technical characteristics and evaluation methods were compared and analyzed; the practical applications of non-destructive detection technologies in meat quality assessment were explored; and the current challenges and future research directions were discussed. The literature presented in this review clearly demonstrate that previous research on non-destructive technologies are of great significance to ensure consumers' urgent demand for high-quality meat by promoting automatic, real-time inspection and quality control in meat production. In the near future, with ever-growing application requirements and research developments, it is a trend to integrate such systems to provide effective solutions for various grain quality evaluation applications.

• ETRI Journal
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• v.31 no.5
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• pp.554-564
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• 2009

In information security and network management, attacks based on vulnerabilities have grown in importance. Malicious attackers break into hosts using a variety of techniques. The most common method is to exploit known vulnerabilities. Although patches have long been available for vulnerabilities, system administrators have generally been reluctant to patch their hosts immediately because they perceive the patches to be annoying and complex. To solve these problems, we propose a security vulnerability evaluation and patch framework called PKG-VUL, which evaluates the software installed on hosts to decide whether the hosts are vulnerable and then applies patches to vulnerable hosts. All these operations are accomplished by the widely used simple network management protocol (SNMP). Therefore, system administrators can easily manage their vulnerable hosts through PKG-VUL included in the SNMP-based network management systems as a module. The evaluation results demonstrate the applicability of PKG-VUL and its performance in terms of devised criteria.

• Educational Technology International
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• v.9 no.1
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• pp.97-114
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• 2008

This research has three purposes: The first purpose is to verify whether SGRs(Student-Generated Rubrics) are effective for learner achievement in higher education or not. The second one is to analyze the agreements between an instructor's evaluations and peer group assessments with SGRs in real classroom situation. The final purpose is to propose the possibility of students' more objective self-evaluation with the use of SGRs. It appears that rubrics are effective tools to improve learner achievement in adult education and to promote the agreement between the instructor's and peer's evaluations, even though learners do not develop SGRs. In addition, this research has demonstrated that most students are not very accurate self-assessors, and they often overestimate themselves. This study can be helpful for novice instructors, especially for those who try to assess their students more fairly, to develop the SGRs as an evaluation tool appropriate for their own situation, and to give more reliable feedback to students.

• Journal of Power Electronics
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• v.17 no.2
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• pp.501-513
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• 2017

The fundamental small-signal modeling of lithium-ion (Li-ion) batteries and a parameter evaluation approach are investigated in this study to describe the dynamic behaviors of small signals accurately. The main contributions of the study are as follows. 1) The operational principle of the small signals of Li-ion batteries is revealed to prove that the sinusoidal voltage response of a Li-ion battery is a result of a sinusoidal current stimulation of an AC small signals. 2) Three small-signal measurement conditions, namely stability, causality, and linearity, are proved mathematically proven to ensure the validity of the frequency response of the experimental data. 3) Based on the internal structure and electrochemical operational mechanism of the battery, an AC small-signal model is established to depict its dynamic behaviors. 4) A classical least-squares curve fitting for experimental data, referred as Levy's method, are introduced and developed to identify small-signal model parameters. Experimental and simulation results show that the measured frequency response data fit well within reading accuracy of the simulated results; moreover, the small-signal parameters identified by Levy's method are remarkably close to the measured parameters. Although the fundamental and parameter evaluation approaches are discussed for Li-ion batteries, they are expected to be applicable for other batteries.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.87-95
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• 2021

In this study, seven companies(A~G) designated as new construction technology selected and evaluated KS F 2622: Method of test for performance evaluation of membrane roofing systems that are similar to field application conditions. As a result of the test, it was confirmed that although all test specimens exceeded KS standards in the basic physical, it was difficult to obtain field quality performance in weak areas such as joints and vertical parts of the adhesive coating method in water-tightness, sagging resistance, swelling resistance tests except for fatigue(crack behavior) tests.