• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.525-528
• /
• 1999

In this study, the new testing method for PSC-Beam will be proposed and performed. Transferable loading tester has many advantage compared with other testing method for PSC-Beam. Numerical analyses are performed and the results are compared with those of experimental studies for PSC-beam. Based on the results of this study, an improved testing method is usable for the assessment of load carrying capacity of PSC-Beam.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1991.04a
• /
• pp.105-110
• /
• 1991

The conventional high-frequency testing method is difficult to detect flaw in concrete because the high frequency stress wave is strongly attenuated due to the large grain size and heterogeneous structure. For restoration of this problem, we develop the stu요 of flaw detection in large concrete block containing various artificial flaws by low frequency spectrum anlysis of impact-echo waveforms. This impact-echo testing method is possible to determine the flaw size, shape and location in large concrete block even if required some attention in case of containing reinforcing steel bar.

• Journal of Magnetics
• /
• v.16 no.3
• /
• pp.276-280
• /
• 2011

This paper presents a non-destructive evaluation study on a radiator with cooling fins as a complex shaped specimen. Radiator structures are used in various heat exchangers, such as automobiles, air conditioners and refrigerators. An eddy current testing method, namely multi-frequency excitation and spectrogram method (MFES), was employed to detect a defect on the radiator tube surrounded by cooling fins. Overall, experimental results suggested that the influence of cooling fin is not as noticeable as that of the defect signals.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.11a
• /
• pp.701-707
• /
• 2000

In this work, we propose to employ magnetostrictive sensors to develop a new non-contacting modal testing method. Specific applications are made in the modal testing of a beam in bending. The role of bias magnetic fields in measuring bending waves is addressed and an approximate analysis to explain the principle to measure bending signals is carried out. The measured modal data by the present method agree well with those by conventional methods using accelerometers.

• International Journal of Highway Engineering
• /
• v.16 no.3
• /
• pp.35-41
• /
• 2014

PURPOSES : The dynamic modulus for a specimen can be determined by using either the non-destructed or destructed testing method. The Impact Resonance Testing (IRT) is the one of the non-destructed testing methods. The MTS has proved the source credibility and has the disadvantages which indicate the expensive equipment to operate and need a lot of manpower to manufacture the specimens because of the low repeatability with an experiment. To overcome these shortcomings from MTS, the objective of this paper is to compare the dynamic modulus obtained from IRT with MTS result and prove the source credibility. METHODS : The dynamic modulus obtained from IRT could be determined by using the Resonance Frequency (RF) from the Frequency Response Function (FRF) that derived from the Fourier Transform based on the Frequency Analysis of the Digital Signal Processing (DSP)(S. O. Oyadigi; 1985). The RF values are verified from the Coherence Function (CF). To estimate the error, the Root Mean Squared Error (RMSE) method could be used. RESULTS : The dynamic modulus data obtained from IRT have the maximum error of 8%, and RMSE of 2,000MPa compared to the dynamic modulus measured by the Dynamic Modulus Testing (DMT) of MTS testing machine. CONCLUSIONS : The IRT testing method needs the prediction model of the dynamic modulus for a Linear Visco-Elastic (LVE) specimen to improve the suitability.

• Journal of Internet Computing and Services
• /
• v.16 no.2
• /
• pp.85-98
• /
• 2015

Component technologies which enable quickly and effectively to develop software have begun to come into the spotlight since early 1990s. Currently, a number of software development works are performed on the J2EE/EJB environment. However component testing is a very complicated task, in addition it requires more efforts than the previous Java class testing. Thus many developers do not perform sufficiently testing works. In this paper we propose an automatic testing method for EJB components based on the in-container testing strategy and implement a testing tool. Since our method builds automatically the test environment for EJB components, it is possible for developers or testers to save their time and efforts at the test preparation phase. Therefore we are convinced that the reliability of EJB components can be increased through sufficient testings with our method.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.14 no.6
• /
• pp.445-451
• /
• 2021

Due to the recent spread and increasing damage of COVID-19, the most important measure to prevent infection is to find infected people early. Group testing which introduced half a century ago, can be used as a diagnostic method for COVID-19 and has become very efficient method. In this paper, we review the fundamental principles of existing group testing algorithms. In addition, the sparse signal reconstruction approach proposed by compressed sensing is improved and presented as a solution to group testing. Compressed sensing and group testing differ in computational methods, but are similar in that they find sparse signals. The our simulation results show the superiority of the proposed sparse signal reconstruction method. It is noteworthy that the proposed method shows performance improvement over other algorithms in the group testing schemes. It also shows performance improvement when finding a large number of defective samples.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.10
• /
• pp.2567-2586
• /
• 2012

Localization of sensor nodes is a key technology in Wireless Sensor Networks(WSNs). Trilateration is an important position determination strategy. To further improve the localization accuracy, a novel Trilateration based on Point In Triangle testing Localization (TPITL)algorithm is proposed in the paper. Unlike the traditional trilateration localization algorithm which randomly selects three neighbor anchors, the proposed TPITL algorithm selects three special neighbor anchors of the unknown node for trilateration. The three anchors construct the smallest anchor triangle which encloses the unknown node. To choose the optimized anchors, we propose Point In Triangle testing based on Distance(PITD) method, which applies the estimated distances for trilateration to reduce the PIT testing errors. Simulation results show that the PIT testing errors of PITD are much lower than Approximation PIT(APIT) method and the proposed TPITL algorithm significantly improves the localization accuracy.

• ETRI Journal
• /
• v.35 no.1
• /
• pp.109-119
• /
• 2013

Static testing of analog-to-digital (A/D) and digital-to-analog (D/A) converters becomes more difficult when they are embedded in a system on chip. Built-in self-test (BIST) reduces the need for external support for testing. This paper proposes a new static BIST structure for testing both A/D and D/A converters. By sharing test circuitry, the proposed BIST reduces the hardware overhead. Furthermore, test time can also be reduced using the simultaneous test strategy of the proposed BIST. The proposed method can be applied in various A/D and D/A converter resolutions and analog signal swing ranges. Simulation results are presented to validate the proposed method by showing how linearity errors are detected in different situations.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.8 no.2
• /
• pp.42-47
• /
• 2012

The containment local leakage rate testing in nuclear power plants is performed in accordance with ANSI/ANS 56.8-1994 in Korea. Two methods, the make-up flow rate and the pressure decay, are used for local leakage rate testing. Though ANSI/ANS 56.8-1994 does not define clearly the minimum test duration for the make-up flow rate method, it requires obtaining the data after reaching the stable condition. Thus the prerequisite stable condition for data acquisition and the testing time is differently applied to each NPPs. Therefore, this study presents a standardized test procedure for data stabilization and testing time through experiments to improve the test reliability.