• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.4
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• pp.142-150
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• 2006

In this study, GPR and lineament methods are used for the effective construction. GPR method is non-destructive testing to understand underground utility tunnel while lineament method is to understand locational environment. First, soil condition of the subject area is surveyed by location analysis. As the result of GPR survey, small-scale and large-scale of underground utility tunnel's location and scale were estimated. From the result of estimation, it is found that the main cause of underground utility tunnel's generation was not the effect of landslide or disturbed foundation from the excavation work but crack of shear & tension from the effect of fault movement which grew by insulation surroundings. From now on, this investigation method would be very useful in the survey and design stage on site for the effective construction and maintenance.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.2
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• pp.150-156
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• 2011

In this paper, infrared thermography measurement technique has been used to develop standard measurement technique for nondestructive testing of composite materials which is widely used in aerospace industries. To increase the defect detection rate, the related experiment used the lock-in IR-thermographiy method. Therefore it is of considerable interest in the field of non-destructive testing for fast discontinuity detection by using ultrasonic lock-in infrared thermography. The result also shows that as the investigation period of light source is lengthened according to the thickness of specimen, the possibility of detecting defects gets higher as well. However, the reason why the result values were not favorable when less than 50 mHz of light source was provided is because it was difficult to detect defects as the defect parts became a state of thermal equilibrium in general when thermal diffusivity affects the entire materials.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1258-1258
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• 2001

Estimation of sugar and reducing sugar content in molasses is very important task in sugar refineries. Conventional methods of determination of sugar content in molasses samples are highly time consuming and employ hazardous chemicals. Due to the physical properties of molasses, probability of error in conventional analytical techniques is high. These methods have proven to be inefficient for a process control in any sugar industry. Hence development of a rapid, inexpensive, physical and also accurate method for sugar determination in molasses will be highly useful. Near Infrared spectroscopy is being widely used worldwide as an analytical technique in food industry. The technique offers the advantage of being non-destructive and rapid. The present paper highlights the potential of near infrared reflectance spectroscopy as a rapid and automated analytical technique for determination of sugar and reducing sugar content in molasses. A number of molasses samples were collected during and after the sugar season from Havana Sugar Industry, Havana. The samples were chosen so as to obtain a wide range of concentration of sugar and reducing sugars. This was done in order to achieve a good calibration curve with widely spread data points. These samples were scanned in the region of 1100 - 2500 nm in diffuse reflectance mode. An indigenous ELICO NIR spectrophotometer, modified according to the requirements of sugar industry was used for this purpose. Each sample was also analyzed simultaneously by standard chemical methods. Chemical values were taken as reference for near infrared analysis. In order to obtain the most accurate calibration for the set of samples, various mathematical treatments were employed. Partial Least Square method was found to be most suitable for the analysis. A comparison is made between the actual values (chemical values) and the predicted values (NIR values). The actual values agree very well with the predicted values showing the accuracy of the technique. The validity of the technique is checked by predicting the concentration of sugar in unknown molasses samples using the calibration curve. The present investigation assesses the feasibility of the technique for on-line monitoring of sugars present in molasses in sugar industries.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.2
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• pp.97-104
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• 2007

An investigation has been made on the relationship between characteristics of Acoustic Emission (AE) signal in welding flaw and the stress corrosion defect in-service for the high pressure pipe steel. In order to tackle the problem of welding flaw in high pressure pipe, specimens were made by the aid of the application of both corrosion liquid usage and a quenching method after local heating. The amplitude of signal was $60{\sim}75\;dB$ in the territory which is suspected for defect, and the specimens which only have welding flaw showed gradients of 0.034, 0.034, 0.035. Moreover, there is a certain increase in gradient even though the differences are very slight. That is, corrosion specimens showed new gradients of 0.040, 0.039, 0.041 which put welding flaw and corrosion mechanism together. After pressurizing 3 minutes, AE signal has been detected from welding flaw easily in each part of the section. It is possible to predict the occurrence and also prevent the damage of stress corrosion crack which has characteristics of cleavage fracture.

• Geophysics and Geophysical Exploration
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• v.14 no.2
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• pp.152-157
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• 2011

The small-loop electromagnetic (EM) method is one of the rapid and non-destructive geophysical methods and has been used widely for many geophysical investigations, particularly for shallow engineering and environmental surveys. Especially in the shallow marine environment, the small-loop EM technique is very effective because of rapid and convenient data acquisition, large signal and low noise level. However, the method has been rarely applied in the very conductive marine environment since it's penetration or investigation depth might be considered too low. In this study, we demonstrated that the small-loop EM method can be effectively applied in the extremely conductive marine environment through the analysis of 1D small-loop EM data. Furthermore, we confirmed that the resistivity distribution under the sea bottom can be quantitatively predicted from the 1D inversion results of synthetic and field data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.11 s.170
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• pp.2014-2021
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• 1999

The present investigation is concerned with the degradation characteristics of cast stainless steel(CF8M), exposed to the $\sigma$-phase degradation at $700^{\circ}C$. In the present paper, the degradation of CF8 M at $700^{\circ}C$ is evaluated by a non-destructive test, DL-EPR(double loop electrochemical potentiokinetic reactivation). The surface of specimens is observed by using scanning electron microscopy after DL-EPR test. Also. chromium contents of matrix, grain boundary and ferrite phase are analyzed by electron probe X-ray micro analyzer. Through the experiments, the following results are obtained 1) The degree of sensitization(DOS) of CF8M aged up to 15hr at $700^{\circ}C$ is increased with acing time while that is decreased with aging time from 15hr to 150hr. 2) The impact energy decreases with increase of $\sigma$-phase while DOS increases with $\sigma$-phase until aging time reaches to 15hr. After the aging time. 15hr, the $\sigma$-phase and the rate of impact energy with respect to aging time decreases. Therefore the degradation behavior of the CF8M can be evaluated by comparing SEM micrographs and the value of DOS.

• Tunnel and Underground Space
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• v.17 no.2 s.67
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• pp.83-89
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• 2007

Impact-echo test is a non-destructive testing method to determine dynamic properties of a material. This presentation introduces the experimental set-up and procedure of the test for rock specimens. In addition, the test results of domestic rocks collected in 5 different areas, a cement mortar and aluminium alloy are presented. The test results include resonance frequencies of P- and S-wave as well as damping ratios of the described 7 different materials. The differences between dynamic and static values of elastic moduli are about 10%, while the dynamic Poisson's ratios are greater than the static Poisson's ratios by at least 0.07. The damping ratio is dependent on the joint density and degree of weathering of a rock specimen.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3413-3420
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• 2021

Applying the available neutron flux for medical and industrial purposes is the most important application of research reactors. The neutron radiography system is used for non-destructive testing (NDT) of materials so that it is one of the main applications of nuclear research reactors. One of these research reactors is the 5 MW pool-type light water research reactor of Tehran (TRR). This work aims to investigate on materials and location of the beam tube (BT) of the TRR radiography system to improve the index parameters of BT. Our results showed that a through-type BT with 20 cm thick carbon neutron filter, 1.2 cm and 9.4 cm of the diameter of inlet (D₁) and output (D₂) BT, respectively gives thermal neutron flux almost 25.7, 5.6 and 1.1 times greater than the former design of the TRR (with D₁ = 1.8 cm and D₁ = 9.4 cm), previous design of the TRR with D₁ = 3 cm and D₁ = 9.4 cm, and another design with D₁ = 5 cm and D₁ = 9.4 cm, respectively. Therefore, the design proposed in this paper could be a better alternative to the current BT of the TRR.

• Journal of Conservation Science
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• v.36 no.6
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• pp.483-493
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• 2020

In this paper, we present a nondestructive analysis using X-ray and microscopic investigation to detect the structure, manufacturing technique and preservation status of the Goryeo lacquered box Inlaid with Mother-of-pearl Chrysanthemum and Scroll Design (Goryeo Lacquered Box). We confirm that the Goryeo Lacquered Box consists of the soft wood as the basic material. The soft wood was coated with textile and then lacquered. The box structure of the Goryeo Lacquered Box was formed of wooden boards with wood plants added to the side, after processing into a trefoil-shaped. The wooden sides of the Goryeo Lacquered Box were cut at regular intervals for easier processing into a curved shape. Moter-of-pearl, tortoiseshell, and metal wire were used to decorate the surface. mother-of pearl was the cutting processing, and tortoiseshell was used for back coloring. The metal line was constructed using one line and twist line.

• Smart Structures and Systems
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• v.31 no.1
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• pp.1-11
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• 2023

Assessment of the compressive strength of concrete plays a major role during formwork removal and in the prestressing process. In concrete, temperature changes occur due to hydration which is an influencing factor that decides the compressive strength of concrete. Many methods are available to find the compressive strength of concrete, but the maturity method has the advantage of prognosticating strength without destruction. The temperature-time factor is found using a LM35 temperature sensor through the IoT technique. An experimental investigation was carried out with 56 concrete cubes, where 35 cubes were for obtaining the compressive strength of concrete using a universal testing machine while 21 concrete cubes monitored concrete's temperature by embedding a temperature sensor in each grade of M25, M30, M35, and M40 concrete. The mathematical prediction model equation was developed based on the temperature-time factor during the early age compressive strength on the 1^st, 2^nd, 3^rd and 7^th days in the M25, M30, M35, and M40 grades of concrete with their temperature. The 14^th, 21^st and 28^th day's compressive strength was predicted with the mathematical predicted equation and compared with conventional results which fall within a 2% difference. The compressive strength of concrete at any desired age (day) before reaching 28 days results in the discovery of the prediction coefficient. Comparative analysis of the results found by the predicted mathematical model show that, it was very close to the results of the conventional method.