• The Journal of the Acoustical Society of Korea
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• v.32 no.1
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• pp.14-21
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• 2013

The erosion, suspension, and transport of sediment frequently occur in the coastal waters and estuarine. These processes often generate the so-called fluid mud layer, which is defined as a high-concentration aqueous suspension of fine grained sediment (> 10 g/l), consisting mainly of silt and clay-size particles. Therefore the high-resolution ultrasound is mostly used to detect or monitor the fluid mud layer. Because the sound attenuation tends to increase rapidly with the suspended sediment concentration, it is necessary to consider the accurate attenuation correction to estimate the backscattering strengths from the suspended sediment layers. In this paper, the volume backscattering strengths with various suspended sediment concentrations were measured using 5-MHz ultrasound signal in a small-scale water tank. The sound attenuation due to the viscosity and scattering from suspended sediment particles was predicted by the Richard's model and applied to the sonar equation to estimate the volume backscattering strengths from the suspended sediment concentrations. For the case that the additional attenuation was not considered, the volume backscattering strengths increased to the concentration of 20 g/l, and over this point, the backscattering strengths were roughly constant. However, for the case that the attenuation due to the suspended sediment concentration was considered, the backscattering strengths increased with the concentration.

• Journal of Biomedical Engineering Research
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• v.30 no.5
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• pp.401-411
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• 2009

In this paper, we correct pulse wave velocity(PWV) with heart-rate and derive regression equations to estimate intima-media thickness(IMT). Widely used methods for diagnosis of arteriosclerosis are IMT and PWV. Arterial wall stiffness determines the degree of energy absorbed by the elastic aorta and its recoil in diastole but there is not correlation between sclerosis and IMT in an existing study. In this study, we will correct PWV with heart-rate and get regression equation to estimate IMT using heart-rate correction index(HCI). We executed experiments for this study. Made up question of physical condition and measured electrocardiogram(ECG), photoplethysmogram (PPG) of finger-tip and toe-tip and ultrasound image of carotid artery. Calculated PWV and IMT using ECG, PPG and ultrasound image. We found that every p-value between PWV and IMT is not significant(<0.05). But p-value between IMT and HCI which is a corrected PWV using heart-rate is significant(>0.01). We use HCI and various measured parameter for estimating regression equation and apply backward estimation to select parameters for regression analysis. Result of backward estimation, found that only HCI is possible to derive proper regression equation of IMT. Relationship between PWV and IMT is the second order. Result of regression equation of E-H PWV is $R^2$=0.735, adj $R^2$=0.711. This is the best correlation value. We calculate error of its analysis for verification of earlobe PWV regression equation. Its result is RMSEP=0.0328, MAPE(%) = 4.7622. Like this regression analysis, we know that HCI is useful parameter and relationship between PWV, HCI and IMT. In addition, we are able to suggest possibility which is that we can get different parameter of prediction throughout just one measurement.

• Journal of radiological science and technology
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• v.31 no.2
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• pp.141-147
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• 2008

Thyroid nodules are a common disease in clinical practice. Fine needle aspiration (FNA) is an accurate and safe method for the diagnosis of thyroid nodules. One of the limitations of FNA is the variable rate of unsatisfactory specimens, especially in small sized, deep seated or complex cystic nodules. To overcome this problem, ultrasound-guided FNA (US-FNA) has been widely used. In this study, the clinical usefulness of US-FNA cytology in thyroid nodules was investigated. Female to male ratio was 6.58:1. The incidence of nodules were 157 (43.1%) cases on the right, 130 (35.7%) cases on the left and 9 (2.5%) cases in isthmus. Total 139 cases (38.2%) belong to less than 1cm and 225 cases (61.8%) belong to more than 1cm. As for the echo type in the nodules, solid types were 255(70.1%), cystic type 39 (10.7%) cases, and the percentage of mixed type was 19.2%. The results show that US-FNA reduces the possibility of unsatisfactory cytologic specimens and the rate of false-negative diagnosis, and improves the diagnostic accuracy in investigation thyroid nodules.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.5
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• pp.426-431
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• 2007

When a high-energy ultrasound propagates through a solid body that contains a crack or a delamination, the two faces of the defect do not ordinarily vibrate in unison, and dissipative phenomena such as friction, rubbing and clapping between the faces will convert some of the vibrational energy to heat. By combining this heating effect with infrared imaging, one can detect a subsurface defect in material in real time. In this paper a realtime detection of the brazing defect of thin Inconel plates using the UIR (ultrasonic infrared imaging) technology is described. A low frequency (23 kHz) ultrasonic transducer was used to infuse the welded Inconel plates with a short pulse of sound for 280 ms. The ultrasonic source has a maximum power of 2 kW. The surface temperature of the area under inspection is imaged by an infrared camera that is coupled to a fast frame grabber in a computer. The hot spots, which are a small area around the bound between the two faces of the Inconel plates near the defective brazing point and heated up highly, are observed. And the weak thermal signal is observed at the defect position of brazed plate also. Using the image processing technology such as background subtraction average and image enhancement using histogram equalization, the position of defective brazing regions in the thin Inconel plates can be located certainly.

• Food Science of Animal Resources
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• v.25 no.2
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• pp.162-167
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• 2005

This study was carried out to investigate the effect of ultrasound treatment on the quality, amino acid and fatty acid composition of fried chicken meat The moisture content of raw chicken meat was higher than fried chicken meat, but the crude protein and fat were lower than those of fried chicken meat The moisture and crude fat of ultrasonic fried chicken meat were higher than those of control. The crude protein of breast meat was higher than leg meat, but the moisture and crude fat were lower than leg meat The ultrasonic treatment did not affect on calorie of the fried chicken meat The pH of leg meat was higher than breast meat, and the fried loss of breast meat was higher than leg meat Frying loss of the leg meat was higher than that of control when ultrasonic treated The Hunters $L^{\ast}$ value of ultrasonic treated breast meat was higher than control, but the leg meat were not significantly different between ultrasonic treatment and control. The $a^{\ast}$ value of leg meat was higher than breast meat, and $b^{\ast}$ value of breast meat was higher than leg meat And the $b^{\ast}$ value of ultrasonic treatment was higher than control. The glutamic acid and aspartic acid were major amino acids in chicken meat The palmitic acid $(C_{16:0})$ and oleic acid $(C_{18:1})$ by fried were decreased, and the linoleic acid $(C_{18:2})$ was increased But the fatty acid composition by ultrasonic treatment were not changed.

• Korean Journal of Food Science and Technology
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• v.49 no.5
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• pp.507-512
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• 2017

The physicochemical properties of maize starch sonicated at various amplitudes (100, 200, and 300 W) and times (10, 30, and 50 min) were examined. The amount of enzyme-susceptible starch increased marginally after sonication. Sonication increased the amount of oil absorbed in the starch although the degree of oil absorption decreased with an extension of the sonication time, implied that different types and extent of damages occurred. Scanning electron microscopy revealed that ultrasound sonication did not form pores on the surfaces, but caused damages such as depression and erosion. Pasting viscosity of starch decreased with an increase in the severity of sonication conditions because of the weakened polymer network. X-ray diffraction suggested that the crystalline domains in starch were not susceptible to sonication and were more resistance to degradation. Sonicated starch formed more pin-holes on the surfaces in the initial glucoamylase reaction; subsequently, as the reaction proceeded, porous starch with enlarged pores was formed and finally, disrupted granular fragments were observed.

• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.721-728
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• 2019

The purpose of this study was to evaluate the relationship between bone mineral density (BMD) and body composition (BC) or backmuscle strength (BS). Sixty-one participants were measured by BMD using ultrasound bone densitometry and Inbody for BC (i.e., SLM=Soft lean mass, SMM=Skeletal muscle mass, FS=Fitness score. et al.), BS after self-questionnaire for life cycle. This study was performed after approving Institutional Review Board and obtaining the informed concent from all participants. Participants was divided into two group by BMD T-score; $T-score{\geq}-1.0$, T-score<-1.0. Statistical analysis was performed by using SPSS ver. 22.0(USA), Spearma test for correlation between BMD and BC or BS. BMD or SLM, BS was increased with increasing physical activity or body mass index. SMM or SMM, FS of BMD $T-score{\geq}-1.0$ group was higher than that of T-score <-1.0 group as well as BS(p>0.05). BMD T-score was correlated positively with SLM(r= 0.424) or SMM(r= 0.431) in men, as well as in women(p<0.05). BS was correlated positively with SLM or SMM, FS. BS was significantly positive correlated with BMD in women group (r= 0.591, p= 0.001), but not in men group. We concluded that BMD is the relationship with SLM or SMM, as well as BS in women.

• Advances in Energy Research
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• v.2 no.1
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• pp.33-45
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• 2014

Photocatalytic hydrogen generation by water splitting ($H_2O_{(1)}{\rightarrow}H_2_{(g)}+1/2O_2_{(g)}$) has been studied on photocatalysts based on Zn, Cd, Fe and Cu, synthesized by coprecipitation. Iron and copper nanoparticles were incorporated as cocatalysts to enhance the photocatalytic activity of the ZnCd solid solution. The effect of the different synthesis parameters (temperature, elemental atomic ratios, amount of Cu and Fe incorporated in the catalyst and calcination temperature) on the photocatalytic production of hydrogen has been studied in order to determine the best experimental synthesis conditions. The catalysts have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and BET. The experiments of photocatalytic water splitting were performed in aqueous solution of the photocatalysts previously dispersed in a soft ultrasound bath. The photocatalysts were irradiated under different lights ranging from 220 to 700 nm. The photocatalytic activity was found to be clearly dependent on the specific area of the photocatalyst.

• Journal of radiological science and technology
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• v.23 no.1
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• pp.63-76
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• 2000

License system of radiologic technologists has been started since 1965 in Korea. This study is to explore directions on radiotechnologists' license system classified by subspecialty. For this purpose, the authors surveyed on radiotechnologists' license system classified by subspecialty, with the subject related to radiotechnologic societies. Additionally, data on qualification and license system associated with medical and health care field were collected. The results are as follows. 1. The main body for subspecialty system for radiologic technologists should be the Korea Radiologic Technologists Association and the Association should maintain a close cooperation with radiotechnologic societies. 2. A radiologic technologist should be a basic role once they pass the license examination. In addition, they can get a special qualification by subspecialty in radiologic technology. 3. Radiotechnologists' license system classified by subspecialty will be keep priorities in order and done systematically. Execution order is as follows ; This study proposes that radiotechnologists responsible for ultrasonography, computed tomography(CT), magnetic resonance imaging(MRI) and security management be started for the first stage. For the second stage, radiotechnologists for mammography, angio-cardiography, digital imaging, maxillo-facial and dental radiography, nuclear medicine, radio-therapeutic field should be in force. 4. Professional education course(basic and intensive) and clinical training program have to be made for the eligibility of radiotechnologists' license system classified by subspecialty. 5. Eligibility system of radiotechnologists' license system classified by subspecialty(non-government or government) has to be made. Further more, inquiry commission to investigate eligibility for radiotechnologists' license system should be established.

• Computers and Concrete
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• v.33 no.4
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• pp.399-407
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• 2024

This study nondestructively examined the evolution of crack density in ultra-high performance concrete (UHPC) upon cyclic loading. Uniaxial compression was repeatedly applied to the cylindrical specimens at levels corresponding to 32% and 53% of the maximum load-bearing capacity, each at a steady strain rate. At each stage, both P-wave and S-wave velocities were measured in the absence of the applied load. In particular, the continuous monitoring of P-wave velocity from the first loading prior to the second loading allowed real-time observation of the strengthening effect during loading and the recovery effect afterwards. Increasing the number of cycles resulted in the reduction of both elastic wave velocities and Young's modulus, along with a slight rise in Poisson's ratio in both tested cases. The computed crack density showed a monotonically increasing trend with repeated loading, more significant at 53% than at 32% loading. Furthermore, the spatial distribution of the crack density along the height was achieved, validating the directional dependency of microcracking development. This study demonstrated the capability of the crack density to capture the evolution of microcracks in UHPC under cyclic loading condition, as an early-stage damage indicator.