• Journal of the Korean Society for Precision Engineering
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• v.26 no.11
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• pp.55-61
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• 2009

The wall thinning defect of nuclear power pipe is mainly occurred by the affect of the flow accelerated corrosion (FAC) of fluid. This type of defect becomes the cause of damage or destruction of in carbon steel pipes. Therefore, it is very important to measure defect which is existed not only on the welding part but also on the whole field of pipe. This study use dual-beam Shearography, which can measure the out-of-plane deformation and the in-plane deformation by using another illuminated laser beam and simple image processing technique. And this study proposes Infrared thermography, which is a two-dimensional non-contact nondestructive evaluation that can detect internal defects from the thermal distribution by the inspection of infrared light radiated from the object surface. In this paper, defect of nuclear power pipe were, measured using dual-beam shearography and infrared thermography, quantitatively evaluated by the analysis of phase map and thermal image pattern.

• Near Infrared Analysis
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• v.1 no.2
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• pp.29-33
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• 2000

The identification step of raw drug materials is an indispensible procedure in the GMP manufacturing process within the pharmaceutical industry. However, wet chemistry methods for identification of drug materials, used by the various Pharmacopeia are time-consuming and expensive steps. In this paper, near-infrared spectroscopy (NIRS) has been developed for identifying eleven drug substances including calcium pantothenate, cefaclor, cefoperazone, cephradine, dextromethorphan, ehtambutol, nicotinamide, pyrozinamide, tramadol, vitamin C, and vitamin E. Also the aim of ths work is to consturct a new algorithm for calibration model using soft independence modeling of class analogy (SIMCA) with Malinowskis Indicator Function (IND), which is used for finding the number of principal components of each class of the SIMACA model. The use of NIR technique with pattern recognition to qualify raw materials can make it possible to monitor process in real time as well as to control all procedures in the pharmaceutical industry. As the result, the samples identified of 183 different batches from 11 different compounds were separated clearly by SIMCA with 2nd derivative spectra in the NIR region of 1100∼2400 nm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1697-1702
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• 2004

In this paper, we proposed the design and calibration method for the near infrared Acousto-Optic Tunable Filter (AOTF). The theory and design principles of AOTF for the visible light are well known since I.C.Chang has developed the parallel tangent condition for the non-collinear AOTF. Deflection angle, frequency-wavelength relation, spectral resolution, etc. were calculated based on the theory of AOTF. From this result, important parameters - incident and acoustic angle - to fabricate AOTF were decided. We measured the spectral resolution and the relation between electrical driving frequency and the Optical wavelength of diffracted light to calibrate the near infrared AOTF. About 40 ∼ 80 MHz electrical frequency was required to get 1200 ∼ 2200 nm near infrared light. Spectral resolution was less than 10 nm in the near infrared region.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.596-597
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• 2017

In this study, the measurements of infrared (IR) signature were carried out using a small scale engine with the variation of the engine performance and target positions in the exhaust plume. The operating conditions of the engine were kept constant for each test, and the measured positions were sapced at refular intervals from the nozzle exit. The measured IR signature was calibrated by using a blackbody. The results of infrared signature measurements are shown in three bands for analysis of spectral characteristics. As the engine performance decreased and the distance from the nozzle exit increased, the IR signature decreased and the level of decrease varied according to the bands.

• Journal of Ocean Engineering and Technology
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• v.28 no.3
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• pp.254-259
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• 2014

The infrared signature of a ship is largely influenced by the ocean environment of the operating area, which has been known to cause large changes in the signature. As a result, the weather condition has to be clearly set for an analysis of the infrared signatures. It is necessary to analyze meteorological data for all the oceans where the ship is supposed to be operated. This is impossibly costly and time consuming because of the huge size of the data. Therefore, the creation of a standard environmental variable for an infrared signature research is necessary. In this study, we compared and analyzed sampling methods to represent ocean data close to the Korean peninsula. In order to perform this research, we collected ocean meteorological records from KMA (Korea Meteorological Administration), and sampled these in numerous ways considering five variables that are known to affect the infrared signature. Specifically, a simple random sampling method for all the data and 1-D, 2-D, and 3-D stratified sampling methods were compared and analyzed by considering the mean square errors for each method.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.116-120
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• 2010

The wheelset, an assembly of wheel and axle, is one of important parts in railway bogie, directly related with the running safety of railway rolling stock. In this investigation, the tensile failure behavior of railway axle materials was investigated. The tensile coupons were prepared from the actual rolling stock parts, which were operated over 20 years. The tensile testing was performed according to the KS guideline. During tensile testing, an infrared camera was employed to monitor temperature changes in specimen as well as demonstrate temperature contour in terms of infrared thermographic images. The thermographic images of tensile specimens showed comparable results with mechanical behavior of tensile materials. In this paper, the failure mode and behavior of railway axle materials were provided with the aid of infrared thermography technique.

• Journal of Sensor Science and Technology
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• v.31 no.4
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• pp.255-259
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• 2022

In this study, we fabricated ZnS substrates with excellent transmittance in the mid-infrared region (3-5 ㎛) using hot pressing instead of conventional chemical vapor deposition (CVD). Diamond-like carbon (DLC) was coated on either one or both sides of the ZnS substrates to improve their mechanical properties and transmittance efficiency. To reduce the reflectance and further improve transmittance in the mid-infrared region, anti-reflection (AR) coating was designed for DLC/ZnS /AR and AR/ ZnS /AR structures. The coating structure, microstructure, and optical properties of the AR-coated ZnS substrates were subsequently investigated by employing energy dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier-transform infrared (FTIR) spectroscopy. The FTIR spectroscopy results demonstrated that, in the mid-infrared region, the average transmittance of the samples with AR coating on one and both sides increased by approximately 18% and 27%, respectively. Thus, AR coating improved the transmittance of the ZnS substrates.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1529-1529
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• 2001

The watercore in apple is very important factor in storage and sorting of fruit. Most consumers tend to prefer the apple included watercore in immediately after harvest, however the watercore causes fruit flesh to brown during storage and lose the worth after all. But it is practically impossible to judge to the naked eye whether an apple has watercore or not. Therefore, the rapid, accurate and non-destructive analysis method for discrimination of watercore should be settled without delay. In this study we attempted the discrimination and quantitative analysis of watercore in apple fruit using near-infrared transmittance spectroscopy ‘Fuji’ apple fruits produced in Kyungpook of Korea was used in this experiment. The watercore content in apple was evaluated by graphic treatment of culled slice sections(10 mm). NIR transmittance spectra were collected over the 500 to 1000 nm spectral region with a spectrometer (Sentronic Co., Germany). The calibration models were carried out by partial least squares (PLS) analysis between NIR spectra data of apples and chemical data of watercore content. The spectra were different in absorbance between apple included watercore and not included one. Apple included watercore had higher absorption band than sample not included one at 732 and 820 nm. The calibration model seems to be accurate to predict the watercore content in apple fruit, the correlation coefficient (R) and root mean square error of prediction (RMSEP) were 0.99 and 0.93%, respectively. This result indicates that the PLSR calibration model by using NIR transmittance spectroscopy could be used for discrimination of watercore in apple fruit.

• Near Infrared Analysis
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• v.1 no.2
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• pp.21-27
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• 2000

Temperature-dependent changes in near-infrared (NIR) spectra have been measured for oleic acid, and nonanoic acid in the pure liquid state. Particular attention has been paid to the 5400-4800 cm$\^$-1/ region where a number of combination bands appear. The NIR spectra of oleic acid show that a band at 5303 cm$\^$-1/ increases with temperature while that at 5270 cm/sup-1/ decreases. It ha been found from their second derivative spectra that these spectral changes take place stepwisely with two break points at 30 and 53$\^{C}$, which correspond to the phase transition temperatures oleic acid reported previously. Principle component analysis (PCA) has been carried out for the NIR spectra of oleic acid in the 5400-4800 cm$\^$-1/ region measured over a temperature range of 15-80$\^{C}$. core plots of the first and second principal components (PCs) show that the NIR spectra are classified into three groups; the spectra measured in the temperature range of 15-30$\^{C}$, those in the range of 31-53$\^{C}$, and those in the range of 54-80$\^{C}$. These temperature ranges correspond to those for quasi-smectic liquid crystal, disordered liquid crystal, and isotropic liquid of oleic acid in the pure liquid state. In other words, PCA provides unambiguous evidence for the phase transitions. similar studies have been carried out for petroselinic acid and nonanoic acid in the pure liquid states, but they do not show any evidence for phase transitions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.6
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• pp.577-585
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• 2010

This paper is a part of developing a software that predicts the infrared signal emitted from a ground object by considering solar irradiation. The radiance emitted from a surface can be calculated by using the temperature and optical characteristics of the surface object. The bidirectional reflectance distribution function (BRDF) is defined as the ratio of reflected radiance to incident irradiance. It is a very important surface reflection property that decides the reflected radiance from the object. In this paper, the spectral radiance received by a remote sensor over the mid-wave infrared(MWIR), and the long-wave infrared(LWIR) regions are computed and compared each other for several different materials. The results show that the optical surface properties such as the BRDF and the emissivity of the object surface can play a major role in generating the infrared signatures of various objects, and the largest infrared signal may reach up to 10 times the smallest one when the infrared signals obtained from a flat plate with different surface conditions under the sun light.