• Korean Journal of Radiology
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• 제22권8호
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• pp.1341-1351
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• 2021

Objective: To compare the quality of various polychromatic and monochromatic images with or without using an iterative metal artifact reduction algorithm (iMAR) obtained from a dual-energy computed tomography (CT) to evaluate total knee arthroplasty. Materials and Methods: We included 58 patients (28 male and 30 female; mean age [range], 71.4 [61-83] years) who underwent 74 knee examinations after total knee arthroplasty using dual-energy CT. CT image sets consisted of polychromatic image sets that linearly blended 80 kVp and tin-filtered 140 kVp using weighting factors of 0.4, 0, and -0.3, and monochromatic images at 130, 150, 170, and 190 keV. These image sets were obtained with and without applying iMAR, creating a total of 14 image sets. Two readers qualitatively ranked the image quality (1 [lowest quality] through 14 [highest quality]). Volumes of high- and low-density artifacts and contrast-to-noise ratios (CNRs) between the bone and fat tissue were quantitatively measured in a subset of 25 knees unaffected by metal artifacts. Results: iMAR-applied, polychromatic images using weighting factors of -0.3 and 0.0 (P_-0.3i and P_0.0i, respectively) showed the highest image-quality rank scores (median of 14 for both by one reader and 13 and 14, respectively, by the other reader; p < 0.001). All iMAR-applied image series showed higher rank scores than the iMAR-unapplied ones. The smallest volumes of low-density artifacts were found in P_-0.3i, P_0.0i, and iMAR-applied monochromatic images at 130 keV. The smallest volumes of high-density artifacts were noted in P_-0.3i. The CNRs were best in polychromatic images using a weighting factor of 0.4 with or without iMAR application, followed by polychromatic images using a weighting factor of 0.0 with or without iMAR application. Conclusion: Polychromatic images combined with iMAR application, P_-0.3i and P_0.0i, provided better image qualities and substantial metal artifact reduction compared with other image sets.

• Journal of the Institute of Electronics and Information Engineers
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• 제49권9호
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• pp.244-250
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• 2012

This paper describes a 4-Gb/s receiver circuit for a low-swing ground-referenced differential signaling system. The receiver employs a common-gate level-shifter and a continuous linear equalizer which compensates inter-symbol-interference (ISI) and improves voltage and timing margins. A bias circuit maintains the bias current of the level-shifter when the common level of the input signal changes. The receiver is implemented with a low-power 65-nm CMOS technology. When 4-Gb/s 400mVp-p signals are transmitted to the receiver through the channel with the attenuation of -19.7dB, the timing margin based on bit error rate (BER) of $10^{-11}$ is 0.48UI and the power consumption is as low as 0.30mW/Gb/s.

• Journal of the Korean Society of Radiology
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• 제13권7호
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• pp.961-968
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• 2019

The purpose of this study was to evaluate the usefulness of cerebral angiography in each energy level by using dual energy technique in CT. Methods were performed on 15 DE images and SE images of CT angiography. For the analysis of images, mean value, standard deviation, SNR and CNR value were determined by setting ROI on MCA, brain parenchyma tissue, and back ground. As a result of concurrent visual evaluation with Likert 5 point scale, the clearest MCA image was confirmed at DE 40 keV and SE 120 kVp(p>0.05). The SNR value of the SE image was measured to be similar to the 40 keV energy level of the DE image. The low energy level image of 40 keV and 50 keV was measured with a high SNR and the contrast ratio was higher than that of the high energy image.

• Resources Recycling
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• 제24권3호
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• pp.51-58
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• 2015

In order to recover tin from the waste tin plating solution, we used the ion exchange method using three types of ion exchange resins. The ion exchange resin with tertiary functional group(Lewatit TP 272) has not adsorption ratio of tin. The ion exchange resin with iminodiacetic functional group(Lewatit TP 207) has high adsorption ratio of tin, but impurity content in the recovered tin solution was relatively high. Whereas, in case of the ion exchange resin with functional group of ethylhexyl-phosphate(Lewatit VP OC 1026), adsorption ratio of tin was less than that of Lewatit TP 207. However, it was possible to remove impurities in the recovered tin solution by controlling the pH of the solution. High purity tin solution can be recovered by removing the organic materials with water washing process.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.453-462
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• 2017

PURPOSE. The purpose of this study was to investigate the in vitro cytotoxicity of thermoplastic denture base resins and to identify the possible adverse effects of these resins on oral keratinocytes in response to hot water/ food intake. MATERIALS AND METHODS. Six dental thermoplastic resin materials were evaluated: three polyamide materials (Smile tone, ST; Valplast, VP; and Luciton FRS, LF), two acrylic materials (Acrytone, AT; and Acryshot, AS), and one polypropylene resin material (Unigum, UG). One heat-polymerized acrylic resin (Vertex RS, RS) was chosen for comparison. After obtaining extracts from specimens of the denture resin materials (${\phi}=10$ mm and d=2 mm) under different extraction conditions ($37^{\circ}C$ for 24 hours, $70^{\circ}C$ for 24 hours, and $121^{\circ}C$ for 1 hour), the extracts (50%) or serial dilutions (25%, 12.5%, and 6.25%) in distilled water were co-cultured for 24 hours with immortalized human oral keratinocytes (IHOKs) or mouse fibroblasts (L929s) for the cytotoxicity assay described in ISO 10993. RESULTS. Greater than 70% viability was detected under all test conditions. Significantly lower IHOK and L929 viability was detected in the 50% extract from the VP ($70^{\circ}C$) and AT ($121^{\circ}C$) samples (P<.05), but only L929 showed reduced viability in the 50% and 25% extract from LF ($37^{\circ}C$) (P<.05). CONCLUSION. Extracts obtained from six materials under different extraction conditions ($37^{\circ}C$, $70^{\circ}C$, and $121^{\circ}C$) did not exhibit severe cytotoxicity (less than 70% viability), although their potential risk to oral mucosa at high temperatures should not be ignored.

• Journal of Fashion Business
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• 제15권3호
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• pp.51-66
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• 2011

The purpose of this study is to investigate the effect of the traditional color sentiment on the contemporary clothing color by studying the pictures of street fashion of Dalian in China, in view of the clothing color of women in their 20-30 years of age having highest purchasing power, along with traditional Chinese color. The clothing color is various in frequency depending on the items in street fashion. Due to the seasonal impact of summer, the most frequent item was one-piece dress with the Multi of various color patterns, followed by White, Black, PB, R and B category. In the top color, the White was most prevalent color due to the seasonal factor, followed by Black, Grey, Multi, R, Y, RP category. Achromatic color is more dominant with the ratio of 7:3, comparing with its counterpart, which consists of R and Y category of V, B, P, VP tone. In the bottom color, Dp tone of PB shows most high frequency, followed by Black. This results illustrate that Chinese women prefer blue jeans and to be looked as slimmer by using of the dark colors. In the accessories, colors of bags and shoes show different results. The bag colors show the high frequency of Dk tone, YR category, and the chromatic colors are little bit dominant than achromatic ones with the ratio of 5.3:4.7. On the contrary, the shoes colors show the highest frequency in Black, the achromatic colors are more dominant than chromatic ones with the ratio of 6.6:3.4. These results somewhat diverge from the international color trend. Color trend in Dalian street fashion in which the high frequency of V tone is observed through all the colors of the items followed by P, VP, Lgr tone in sequence. In the light of Chinese traditional color preference, this result denotes that the traditional color preferences of red, yellow are still affecting the contemporary color choices of clothing in Chinese women. The high incidence of PB category in the bottom and one-piece dress does not seem to have its origin form traditional Chinese color sentiment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제29권8호
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• pp.483-488
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• 2016

Ultrasound imaging by using piezoelectric materials, such as lead zirconium titanate (PZT) has been one of the most preferred modes of imaging in the medical field due to its simple, low cost and non-ionizing radiation in comparison to other imaging techniques. Recently, the market demand for portable ultrasound is becoming larger with applications in developing countries, disaster area, military, and emergency purposes. However, most of ultrasound probes used is bulky and high power consumable, so unsuitable for such applications. In this study, the 3 layered ceramic specimen consisted of 128 pitches of $420{\mu}m$ in width and $450{\mu}m$ in thickness were prepared by using the Ti-rich PZT compositions co-fired at $1,050^{\circ}C$. Their electrical and ultrasound pulse-echo properties were investigated and compared to the single layer specimen. The 3 layered ultrasound probe showed 1.584 V of Vp-p, which is 3.2 times higher than single layered one, implying that it would allow effectively such a portable ultrasound probe system. The result were discussed in terms of higher capacitance, lower impedance and higher dielectric coefficient of the 3 layered ultrasound probe.

• Journal of the Korea Institute of Building Construction
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• 제10권1호
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• pp.137-145
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• 2010

The mechanical properties of stone structures are generally characterized according to the strength of the stone used. An ultrasonic velocity method that does not damage cultural heritages is used to measure the strength of stone. However, there is no correction involved for surface roughness and thickness of the stone in the ultrasonic method currently used. In addition, a contact agent such as grease can cause contamination on the surface of a cultural heritage. Accordingly, this study suggests an indirect method of strength estimation formula for stone structures based on the surface roughness of the structure, its thickness, and the type of contact agent. (1) Rock strength estimation formula using ultrasonic velocity method of dabbed finish : $f_{su}=30.51\;Vp^{0.82}(R^2=95)$ (2) Rock strength estimation formula using ultrasonic velocity method of harsh finish : $f_{su}=61.52\;Vp^{0.32}(R^2=92)$.

• Imaging Science in Dentistry
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• 제37권2호
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• pp.65-68
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• 2007

Purpose: To compare the leakage and scattered radiation from hand-held dental X-ray unit with radiation from fixed dental X-ray unit. Materials and Methods: For evaluation we used one hand-held dental X-ray unit and Oramatic 558 (Trophy Radiologie, France), a fixed dental X-ray unit. Doses were measured with Unfors Multi-O-Meter 512L at the right and left hand levels of X-ray tube head part for the scattered and leakage radiation when human skull DXTTR III was exposed to both dental X-ray units. And for the leakage radiation only, doses were measured at the immediately right, left, superior and posterior side of the tube head part when air was exposed. Exposure parameters of handheld dental X-ray unit were 70 kVp, 3 mA, 0.1 second, and of fixed X-ray unit 70 kVp, 8 mA, 0.45 second. Results: The mean dose at the hand level when human skull DXTTR III was exposed with portable X-ray unit $6.39{\mu}Gy$, and the mean dose with fixed X-ray unit $3.03{\mu}Gy$ (p<0.001). The mean dose at the immediate side of the tube head part when air was exposed with portable X-ray unit was $2.97{\mu}Gy$ and with fixed X-ray unit the mean dose was $0.68{\mu}Gy$ (p<0.01). Conclusions: The leakage and scattered radiation from hand-held dental radiography was greater than from fixed dental radiography.

• Journal of IKEEE
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• 제21권4호
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• pp.331-337
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• 2017

In this paper, we present the design of a 20MHz bandwidth 3rd-order continuous-time low-pass sigma-delta modulator with low-noise and low-power consumption. The bandwidth of the system is sufficient to accommodate LTE and other wireless network standards. The 3rd-order low-pass filter with feed-forward architecture achieves the low-power consumption as well as the low complexity. The system uses 3bit flash quantizer to provide fast data conversion. The current-steering DAC achieves low-power and improved sensitivity without additional circuitries. Cross-coupled transistors are adopted to reduce the current glitches. The proposed system achieves a peak SNDR of 65.9dB with 20MHz bandwidth and power consumption of 32.65mW. The in-band IM3 is simulated to be 69dBc with 600mVp-p two tone input tones. The circuit is designed in a 0.18-um CMOS technology and is driven by 500MHz sampling rate signal.