• Journal of Biosystems Engineering
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• 제37권2호
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• pp.100-105
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• 2012

Purpose: Methane production potential in aerobic digestion was assessed according to feed to inoculum (F/I) ratio for food waste only, and mixing ratio of two materials for food waste and swine manure to give a basic data for the design of anaerobic digestion system. Methods: Anaerbic digestion test was performed using a lab scale batch reactor at $35^{\circ}C$ for six different feed to inoculum (F/I) ratios (0.50, 0.72, 1.14, 1.50, 2.14 and 3.41), three food waste to swine manure ratios (100:0, 60:40 and 40:60) with two different loading concentrations (10g VS/L and 30g VS/L). Results: For food waste only, the highest biogas yield of 1008 mL/gVS was obtained at 0.50 of F/I. For the co-digestion of food waste and swine manure mixture, the highest biogas yield of 1148 mL/gVS was obtained at a mixing ratio of 40:60 with loading concentration of 10g VS/L. Conclusions: F/I ratio for the food waste only, mixing ratio of food waste and swine manure, and co-substrate loading rate affected the biogas production rate. For the low loading rate, there was not so much difference according to the mixing ratio of food waste and swine manure, but for the high loading rate higher biogas yield was acquired for the co-digestion of food waste and swine manure than for the food waste alone (mixing ratio, 100:0).

• Journal of the Korean Wood Science and Technology
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• 제48권2호
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• pp.136-153
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• 2020

In this paper, the influence of initial formaldehyde/urea (F/U) molar ratios on the performance of low molar ratio (1.0) urea-formaldehyde (UF) resin adhesives has been investigated. Two initial F/U molar ratios, i.e., the first and second initial molar ratios were used for the alkaline addition reaction. Three levels of the first initial F/U molar ratios (2.0, 3.0, and 4.0) and two levels of the second initial molar ratios (2.0 and 1.7) were employed to prepare a total of six UF resins with an identical final molar ratio (1.0). The basis properties, functional groups, molecular weight, crystallinity, and thermal curing properties of the UF resins were characterized in detail. Higher levels (3.0 and 4.0) of the first initial F/U molar ratio provided the UF resins with better properties (non-volatile solids content, viscosity, gelation time, pH, and specific gravity) than those of the resins prepared with the conventional level F/U molar ratio of 2.0. Statistical analysis suggested that combining the first and second initial molar ratio of 4.0 with 1.7 would result in UF resins with greater adhesion strength and lower formaldehyde emission than those of the resins prepared with other molar ratios. The results showed that higher levels of the first initial molar ratio resulted in a more branched structure, as indicated by GPC, FTIR, DSC, XRD, and greater adhesion strength than those of the other UF resins with an identical final molar ratio of 1.0.

• International Journal of Contents
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• 제8권4호
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• pp.56-63
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• 2012

In recent decades, analyzing the activities of human brain achieved some accomplishments by using the functional Magnetic Resonance Imaging (fMRI) technique. fMRI data provide a sequence of three-dimensional images related to human brain's activity which can be used to detect instantaneous cognitive states by applying machine learning methods. In this paper, we propose a new approach for distinguishing human's cognitive states such as "observing a picture" versus "reading a sentence" and "reading an affirmative sentence" versus "reading a negative sentence". Since fMRI data are high dimensional (about 100,000 features in each sample), extremely sparse and noisy, feature selection is a very important step for increasing classification accuracy and reducing processing time. We used the Fisher Discriminant Ratio to select the most powerful discriminative features from some Regions of Interest (ROIs). The experimental results showed that our approach achieved the best performance compared to other feature extraction methods with the average accuracy approximately 95.83% for the first study and 99.5% for the second study.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.130-135
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• 1995

We can consider that the study on early evaluation of strength of concrete is useful to raise safety of building and utility of quality control of concrete is useful to raise safety of building and utility of quality control of concrete. In this paper, was proposed to method early to predict strength of concrete with key parameters, such as Water/Cement(W/C) ratio and Sand / Aggregate(S/A) ratio. Through a series of experiment, the obtained results are summarized as follow. $\circled1$ The ratio of resistance was decteased as the increase of W/C ratio. $\circled2$ The maximum value for the ratio of resistance and compressive strength was presented in the case of 40% S/A ratio. $\circled3$ The relationship. of the ratio of resistance and compressive strength on 28days according to the change of W/C and S/A ratio is to be: $F_{28}=-0.00104R^2 + 2.263R - 935.5$ (W/C Ratio) $F_{28} = 0.007R^2 - 10.693R - 4269.1$ (S/A Ratio)

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.61-64
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• 2009

본 연구에서는 액체 로켓 엔진의 연소 시험을 통하여 O/F ratio가 연소 성능에 미치는 영향을 측정하였다. 사용된 분사기는 추력 200 N, 챔버 압 10 bar로 설계된 샤워헤드형 이며, 점화 방식은 촉매점화를 선택하였고. 과산화수소와 케로신을 추진제로 사용하였다. 본 실험을 통해서 로켓의 효율을 보다 증가시킬 수 있는 방법으로 O/F ratio가 연소 성능에 미치는 영향을 측정하여 O/F ratio의 운용조건을 알 수 있었다.

• Journal of Yeungnam Medical Science
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• 제38권3호
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• pp.225-230
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• 2021

Background: We aimed to analyze the effectiveness of albumin to globulin ratio (AGR) in predicting postoperative febrile urinary tract infection (fUTI) after ureteroscopic lithotripsy (URS) and retrograde intrarenal surgery (RIRS). Methods: From January 2013 to May 2018, 332 patients underwent URS and RIRS. The rate of postoperative fUTI and risk factors for postoperative fUTI were analyzed using logistic regression. Patients were divided into postoperative fUTI and non-postoperative fUTI (non-fUTI) groups. AGR with other demographic and perioperative data were compared between the two groups to predict the development of fUTI after URS. Results: Of the 332 patients, postoperative fUTI occurred in 41 (12.3%). Preoperative pyuria, microscopic hematuria, diabetes mellitus, hypoalbuminemia, and hyperglobulinemia were more prevalent in the fUTI group. Patients in the fUTI group had larger stone size, lower preoperative AGR, longer operation time, and longer preoperative antibiotic coverage period. In a multivariable logistic analysis, preoperative pyuria, AGR, and stone size were independently correlated with postoperative fUTI (p<0.001, p=0.008, and p=0.041, respectively). Receiver operating curve analysis showed that the cutoff value of AGR that could predict a high risk of fUTI after URS was 1.437 (sensitivity, 77.3%; specificity, 76.9%), while the cutoff value of stone size was 8.5 mm (sensitivity, 55.3%; specificity, 44.7%). Conclusion: This study demonstrated that preoperative pyuria, AGR, and stone size can serve as prognostic factors for predicting fUTI after URS.

• Journal of Nutrition and Health
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• 제27권6호
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• pp.574-582
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• 1994

The effects of age and dietary fatty acid composition on prostagladin production was investigated in Sprague-Dawley strain male rats. Animals weighing 88.6$\pm$2.2g were fed 10% dietary fat(W/W, 20% of total energy). The P/S ratios of dietary lipid were three levels(0.5, 1, 2) and there were three different levels of n-6/n-3 fatty acid ratio(2, 4, 8) in each P/S ratio. The experimental period were 1 month and 12 months, respectively. The results of this study were as follows. As the age of rats increased, the plasma thromboxane B2 production increased, but aorta 6-keto prostaglandin F1$\alpha$ decreased. When a higher amount of n-3 fatty acid was fed in each P/S ratio, the relative percentage of linolenic acid and EPA in platelet increased.

• Journal of electromagnetic engineering and science
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• 제15권2호
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• pp.120-122
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• 2015

This study presents a new, simple method for improving the front-to-back (F/B) ratio of a microstrip patch antenna (MSA) based on surface wave suppression. The back radiation of the MSA is significantly reduced by using the meandered ground plane edges and placing split-ring resonators (SRRs) in the middle of the meandered slots. By loading SRRs near the center of the meandered ground plane edges, some parts of the diffracted back-lobe power density can be reduced further. Compared to the F/B ratio of a conventional MSA with a full ground plane of the same size, an improved F/B ratio of 18 dB has been achieved experimentally for our proposed MSA.

• 대한기계학회논문집
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• 제18권10호
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• pp.2533-2542
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• 1994

This paper suggests a simple approach to determining the screw characteristics for a three0dimensional flow in a channel with a finite aspect ratio(ratio of a width to a depth, W/H) by introducing a Total Shape Factor($F_t$) to correct a two-dimensional flow analysis for a channel with an infinite aspect ratio. In the present study, the Total Shape Factor($F_t$) was defined as a ratio of a net flow rate obtained by the three-dimensional analysis to that by the two-dimensional analysis. In the proposed approach, the quantity, $ \frac{{\partial}F_t}{\partial(H/W)}$ turns out to be almost constant and to play an important role in understanding the effects of the flights. Therefore, $ \frac{{\partial}F_t}{\partial(H/W)}$ are extensively reported in this paper in terms of several dimensionless parameters. This simple approach with such database will be very useful for extruder designers to predict the screw characteristics.

• Asian Pacific Journal of Cancer Prevention
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• 제16권16호
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• pp.7085-7088
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• 2015

Background: The high incidence of prostate cancer as the most common malignancy in males in many countries raises the question of developing reliable detection tests. The prostate specific antigen (PSA) test is the most widely used for screening for prostate cancer; however, its low specificity elevates the number of unnecessarily biopsies. Serum human kallikrein-2 (hK2) is considered as a promising marker, and especially its ratio to fPSA, for predicting the presence of malignancy to select the best choice referring to biopsy or surveillance. In this study, we investigated the role of hK2 and its combinations with other markers to discriminate prostate cancer from benign diseases in Syrian patients. Materials and Methods: In this prospective oriented cross-sectional cohort study, serum samples were collected from patients referred to many Hospitals in Damascus, Syria, between May 2011 and March 2012, and diagnosed with biopsy proven benign prostate hyperplasia (BPH) or prostate cancer (PCa). Serum was analyzed for hK2, PSA and fPSA, and the ratios of fPSA/PSA and hK2/fPSA were calculated. Results: We found that mean hK2/fPSA ratios were significantly higher (P=0.01) in prostate cancer patients than in the BPH or control groups. Also the ratio hk2/fPSA gave the largest area under the curve (AUC:0.96) which was significantly larger than for fPSA/PSA (AUC:0.41) indicative of higher specificity. Conclusions: Our results demonstrate that the ratio of hK2/fPSA might be superior to the use of fPSA/PSA alone. The hK2 could be shown to enhance the early detection of prostate cancer; especially the ratio hK2/fPSA improves specificity and hence may reduce the number of negative biopsies.