• Title/Summary/Keyword: Contrast ratio

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Improved Compressive·Flexural Performance of Hybrid Fiber-Reinforced Mortar Using Steel and Carbon Fibers (강 및 탄소 섬유를 사용한 하이브리드 섬유보강 모르타르의 압축·휨성능 향상)

  • Heo, Gwang-Hee;Park, Jong-Gun;Seo, Dong-Ju;Koh, Sung-Gon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.5
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    • pp.48-59
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    • 2021
  • In this study, experiments were conducted to investigate the compressive·flexural performances of single fiber-reinforced mortar (FRM) using only steel fiber or carbon fiber which has different material properties as well as hybrid FRM using a mixture of steel and carbon fibers. The mortar specimens incorporated steel and carbon fibers in the mix proportions of 1+0%, 0.75+0.25%, 0.5+0.5%, 0.25+0.75% and 0+1% by volume at a total volume fraction of 1.0%. Their mechanical performance was compared and examined with a plain mortar without fiber at 28 days of age. The experiments of mortar showed that the hybrid FRM using a mixture of 0.75% steel fibers + 0.25% carbon fibers had the highest compressive and flexural strength, confirming by thus the synergistic reinforcing effect of the hybrid FRM. On the contrast, in the case of hybrid FRM using a mixture of 0.5% steel fibers + 0.5% carbon fibers witnessed the highest flexural toughness, suggesting as a result the optimal fiber mixing ratio of hybrid FRM to improve the strength and flexural toughness at the same time. Moreover, the fracture surface was observed through a scanning electron microscope (SEM) for image analysis of the FRM specimen. These results were of great help for images analysis of hybrid reinforcing fibers in cement matrix.

A Study on MR Imaging Method for The Patient with Inserting Shoulder Joint Suture Anchor (견관절 삽입술을 시행한 환자의 자기 공명 영상법에 관한 연구)

  • Park, Eui-Cheol;Bae, Seok-Hwan;Ryu, Yeun-Chul;Park, Young-Joon;Kim, Yong-Gwon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.4
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    • pp.513-519
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    • 2021
  • Metallic suture anchors are very useful and common fixation devices that are inserted into the target bone to sustain the tendon of a patient with musculus supraspinatus tendon ruptures. On the other hand, the presence of a metallic material prosthesis, such as a metal suture anchor, causes severe MR imaging artifacts, including field distortion, signal loss, and failure of fat suppression. The difference in magnetic susceptibility between metal and other organic materials causes magnetic field distortion surrounding the prosthesis. The resulting magnetic field inhomogeneity makes the images with a lower signal-to-noise ratio and distortion. For a patient with a suture anchor implanted, MR imaging is the golden standard for determining the postoperative prognosis, and a fat-saturation sequence is one of the imaging methods most affected by metal-induced artifacts. In this study, three fat-saturation sequences were compared. Artifact quantification and contrast comparison between the supraspinatus tendon and the surrounding muscle were presented. The images obtained using the STIR pulse sequence showed fewer susceptibility artifacts and better visibility in the supraspinatus tendon and the tissue area. Therefore, the STIR sequence is the most appropriate fat-saturation imaging method for patients with a metallic prosthesis.

Does epithelioid angiomyolipoma have poorer prognosis, compared with classic angiomyolipoma?

  • Lee, Wonchul;Choi, Se Young;Lee, Chanwoo;Yoo, Sangjun;You, Dalsan;Jeong, In Gab;Song, Cheryn;Kim, Kun Suk;Hong, Bumsik;Hong, Jun Hyuk;Ahn, Hanjong;Kim, Choung-Soo
    • Investigative and Clinical Urology
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    • v.59 no.6
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    • pp.357-362
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    • 2018
  • Purpose: Classic angiomyolipoma (AML) is common benign kidney tumor. However, some studies have claimed that epithelioid angiomyolipoma (EAML) has malignant potential. We compared the patient characteristics and prognosis of EAML and classic AML to demonstrate predicting factors and poorer prognosis of EAML. Materials and Methods: The medical records of 231 patients who were diagnosed with EAML (n=27, 11.7%) or classic AML (n=204, 88.3%), were reviewed. All patients underwent computed tomography (CT) scans before operation or needle biopsy. We assessed the age, sex, tumor size, body mass index, comorbidities, and Hounsfield unit (HU) according to each CT phase. We defined the unfavorable group as patients with recurrence, metastasis and death due to tumor progression. Logistic regression analysis was used to predict EAML. Results: EAML patients were younger (41.2 years vs. 49.1 years, p=0.001), predominantly male (55.6% vs. 28.4%, p=0.005), and had a larger tumor (7.5 cm vs. 4.2 cm, p<0.001). The median pre-contrast HU was not significantly different between EAML and classic AML ($29.9{\pm}23.7$ vs. $14.7{\pm}41.0$, p=0.071). In multivariable analysis, younger age (odds ratio [OR], 0.96; p=0.032), male sex (OR, 3.33; p=0.013), and tumor larger than 4 cm (OR, 3.8; p=0.009) were significant predictive factors. Five patients (18.5%) had unfavorable outcomes, two patients had lymph node metastasis, and three patients had lung metastasis. Conclusions: Patient and tumor characteristics can be helpful in determining the type of AML preoperatively. Younger age, male sex, and larger tumor mass may increase the possibility of diagnosing EAML. EAML has malignant potential and requires careful follow-up.

Effect of Corrugation Fluting on the Compressive Strength of Corrugated Fiberboard Box for Food Packaging (골판지의 골 성형이 식품포장용 골판지 상자의 압축강도에 미치는 영향)

  • Kim, Cheong;Her, Jae-Young;Lee, Kwang-Geun
    • Food Engineering Progress
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    • v.14 no.2
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    • pp.106-111
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    • 2010
  • In this study, we performed corrugation fluting experiments to examine the relationship between high-low corrugation of a corrugated medium and compressive strength of corrugated containers for food packaging. A low-grade corrugated medium was found to suffer from weak tensile resistance and to be prone to stealing, which tends to produce low corrugation. In contrast, a medium with a large corrugation deviation often caused slimming during fluting and produced irregular corrugations. Experiments of high-low corrugation distribution according to corrugated medium grades indicate that a high grade medium shows a smaller ratio of low corrugation. The thickness of corrugated fiberboard is weakly correlated to the basis weight of medium, yet positively correlated to the medium thickness (y=3.9732x+4.2712, $R^{2}=0.8142$) and inversely proportional to the medium density (y=-3.1213x+6.8736, $R^{2}=0.9919$). Compressive strength of a corrugated fiberboard box is low, if made of corrugated medium with large low corrugation distribution. Compressive strength showed 13% variation with respect to medium grades and 21% variation for various test samples. The corrugation fluting of a corrugated medium is related to physical properties such as basis thickness and density.

Resistance to Sulfate Attack of Concrete Containing LCD glass powder Using Industrial By-products (산업부산물을 활용한 LCD 유리 미분말 혼입 콘크리트의 황산염침식 저항성)

  • Kim, Seong-Kyum;Song, Jae-Ho
    • Journal of the Society of Disaster Information
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    • v.15 no.2
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    • pp.239-248
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    • 2019
  • Purpose: This study aims to enhance the resistance against sulfate attack compared to ordinary Portland cement (OPC) concrete by using liquid crystal display (LCD) as binder. Method: The fundamental properties including compressive strength and porosity of concrete replaced by LCD up to 15% at increments of 5% and in turn, the weight, volume, and strength loss of LCD-mixed concrete was analyzed. Results: For the concrete substituted by 5% of LCD, it showed the highest compressive strength at 28 days of curing, and particular at immersion of $Na_2SO_4$ solution, it was achieved the lowest loss of weight, volume and strength due to an decreased porosity at capillaries. In contrast, there is no distinct difference of the sulfate attack resistance between LCD-mixed concretes under exposure of $MgSO_4$ solution, excepted for OPC concrete. Conclusion: In this study, comparison of resistance to sulfate attack between LCD-mixed concretes, and it would be proposed the possibility of LCD usage as binder through long-term verification with extended replacement ratio and identification of changes of hydrates in the cement matrix.

Characteristics of chemical water quality and the empirical model analysis before and after the construction of Baekje Weir (금강수계 백제보 건설 전·후의 화학적 수질특성 및 경험적 모델 분석)

  • Kim, Yu-Jin;Lee, Sang-Jae;An, Kwang-Guk
    • Korean Journal of Environmental Biology
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    • v.37 no.1
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    • pp.48-59
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    • 2019
  • This study analyzed the water quality characteristics and developed empirical models prior to and after the construction of Baekje Weir, in the Geum River watershed between 2004-2017. The comparative evaluation of the surface water chemistry before and after the four major river projects on the weirs indicated that total phosphorus (TP), based on annual data, rapidly decrease after the construction of the weir while the total nitrogen(TN) decreased. Conversely, chlorophyll-a (CHL) concentration, which is a good indicator of primary productivity, increased after the construction of the weir together with an increase in specific conductivity. Simply put, the construction of the weir led to the decrease in concentrations of N and P due to the increased water residence time (WRT), whereas the CHL :TP ratio greatly increased in magnitude. The regression analysis of the empirical model indicated that CHL had no significant relation (r=0.068, p=0.6102, n=58) with TP before the weir construction, but had a relation with TP after the weir construction (r=0.286, p<0.05, n=56). Therefore, such conditions resulted in an increase in primary productivity on a given unit of phosphorus, resulting in frequent algal blooms. In contrast, seasonal suspended solids (SS) and TP increased during the monsoon period, compared to the pre-monsoon, thereby showing positive correlations (r>0.40, p<0.01, n=163) with precipitation. If the government consistently discharges water from the weir, the phosphorus concentration will be increased due to its reversion to a lotic waterbody from a lentic waterbody hereby reducing algal blooms in the future.

Effects of dietary humic acid and enzymes on meat quality and fatty acid profiles of broiler chickens fed canola-based diets

  • Disetlhe, Amogelang R.P.;Marume, Upenyu;Mlambo, Victor;Hugo, Arno
    • Asian-Australasian Journal of Animal Sciences
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    • v.32 no.5
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    • pp.711-720
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    • 2019
  • Objective: This study was conducted to assess the effect of potassium humate and enzymes (Xylanase+Amylase+Protease) inclusion in diets on carcass characteristics, meat quality and fatty acid profiles of broilers fed canola-based diets. Methods: Two hundred and twenty broilers randomly allotted to 5 dietary treatments: the control (commercial broiler diet); CM (17.5% canola meal inclusion); CMEnz (17.5% CM inclusion+0.3 g/kg Axtra XAP); CMPh (17.5% CM inclusion+1.5% Potassium Humate, PH); and CMEnzPh (17.5% CM inclusion+1.5% PH+0.3 g/kg Axtra XAP) were slaughtered at day 42 for assessment of carcass and meat quality parameters. Results: Diet had no effect on carcass traits apart from breast muscle weight and breast muscle index. The highest breast muscle weight was observed in broilers fed CMEnz ($487.6{\pm}17.5g$) followed by those fed the control diet ($474.37{\pm}17.5g$). Diet also had no significant dietary effect on pH, temperature, drip loss and shear force values of the breast muscle. However, diet significantly affected meat colour and water-holding capacity. Broilers in the control and CMPh groups ($52.94{\pm}0.67$ and $52.91{\pm}0.67$) had the highest (p<0.05) values for lightness ($L^*$), whilst those fed CMEnzPh had the lowest value ($47.94{\pm}0.67$). In contrast, CM group had the lowest (p<0.05) value for redness ($a^*$) with CMEnzPh group having the highest values. The proportion of polyunsaturated fatty acids (PUFAs), n-6 and n-3 fatty acids and the PUFA/saturated fatty acid ratio were increased in CM-based diets containing enzymes and humic acid. Conclusion: It can, therefore, be concluded that CM can be included in broiler diets in the presence of enzymes and humic acid with positive effects on meat quality and important fatty acids that are beneficial to the health of consumers.

Quality and Antioxidant Properties of Cookies Supplemented with Cabbage Powder (양배추 분말을 첨가한 쿠키의 품질 및 산화방지 활성)

  • Lee, Yeong Mi;Lee, Jun Ho
    • Food Engineering Progress
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    • v.21 no.1
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    • pp.93-98
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    • 2017
  • The feasibility of incorporating cabbage powder (CP) as a value-added food ingredient into convenient food products was investigated using cookie as a model system. CP was incorporated into cookies at amounts of 0, 2, 4, 6, and 8% (w/w) based on total weight of wheat flour. pH level and moisture content of cookie dough decreased and increased significantly, respectively, with increasing levels of CP (p<0.05), whereas density was not directly affected by levels of CP incorporation. The spread ratio of cookies and their hardness increased significantly while the loss rate decreased significantly with increasing levels of CP (p<0.05). In terms of color, lightness and yellowness decreased while redness increased significantly (p<0.05) with increasing levels of CP. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activities were significantly elevated by CP addition, and they increased significantly as CP concentration increased in the formulation (p<0.05). Finally, consumer acceptance test indicated that the higher than 4% of CP incorporation had an adverse effect on general consumer preferences. In contrast, cookies with moderate levels of CP (2%) were recommended based on overall scores to take advantage of the antioxidant properties of CP without sacrificing consumer acceptability.

A Study on Feasibility of Total Variation Algorithm in Skull Image using Various X-ray Exposure Parameters (다양한 X-ray 촬영조건을 이용하여 획득한 skull 영상에서의 Total Variation 알고리즘의 가능성 연구)

  • Park, Sung-Woo;Lee, Jong-In;Lee, Youngjin
    • Journal of the Korean Society of Radiology
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    • v.13 no.5
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    • pp.765-771
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    • 2019
  • Noise in skull X-ray imaging is inevitable, which reduces imaging quality and diagnostic accuracy and increases errors due to the nature of digital imaging devices. Increasing the dose can attenuate noise, but that could lead to big problems with higher exposure dose received by patients. Thus, noise reduction algorithms are actively being studied at low doses to solve dose problems and reduce noise at the same time. Wiener filter and median filter have been widely used, with the disadvantages of poor noise reduction efficiency and loss of much information about imaging boundary. The purpose of this study is to apply total variation (TV) algorithm to skull X-ray imaging that can compensate for the problems of previous noise reduction efficiency to assess quantitatively and compare them. For this study, skull X-ray imaging is obtained using various kVp and mAs using the skull phantom using the X-ray device of Siemens. In addition, contrast to noise ratio (CNR) and coefficient of variation (COV) are compared and measured when noisy image, median filter, Wiener filter and TV algorithm were applied to each phantom imaging. Experiments showed that when TV algorithms were applied, CNR and COV characteristics were excellent under all conditions. In conclusion, we've been able to see if we can use TV algorithm to improve image quality and CNR could be seen to increase due to the decrease in noise as the amount of increased mAs. On the other hand, COV decreased as the amount of increased mAs, and when kVp increased, noise was reduced and the transmittance was increased, so COV was reduced.

Association Between Job Stress and Fatigue Symptoms Among Fire-Fighting Officials (소방공무원의 직무스트레스와 피로수준과의 관련성)

  • Lee, Kwang-Sung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.2
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    • pp.496-506
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    • 2021
  • This study examined the relationship between job stress and fatigue symptom of fire-fighting officials. The study subjects were 330 fire-fighting officials working at five fire stations in the D metropolitan city. The study survey was a structured self-administered questionnaire from September 1 to October 31, 2019. The level of fatigue symptoms and job stress were significantly higher (p<.0.001). By the sub-region, the level of fatigue symptoms and job demand were significantly higher (p=0.046), but the decision latitude, the supervisor support, and co-worker support were lower (p=0.006, p<0.001, and p<0.001, respectively). The level of fatigue symptom showed a significant positive correlation with the total score of job stress (r=0.348, p<0.05) and the job demand (r=0.301, p<0.05). In contrast, it showed a significant negative correlation with the decision latitude (r=-0.306, p<0.05), supervisor support (r=-0.340, p<0.05), and co-worker support (r=-0.355, p<0.05). Multivariate logistic regression showed that the odds ratio of the high-risk fatigue group was significantly higher in the high-risk group of job stress than in the low group of job stress (ORs=3.03, 95% CI=1.13~8.12). These findings suggest that the level of fatigue symptoms of fire-fighting officials is related significantly to job stress.