• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.119-126
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• 2002

A reliability analysis is performed to investigate the influence of the uncertainty from few in-situ samples and inherent heterogeneity of the ground on the probability of failure for a rock cut slope. The results are compared with those of deterministic slope stability analysis. The random variables used are unit weight of the rock, the angle of potential slope of failure, and cohesion and internal friction angle of joints. It was found that the rock slope in which the factor of safety satisfied the minimum safety factor in the deterministic analysis has high probability of failure in the reliability analysis when the weak geological strata are involved in the cut slope. The probability of failure of rock slope is most sensitive to the mean and standard deviation of cohesion in rock joint among the random soil parameters included in the reliability analysis. Sensitivities of the mean values are larger than those of standard deviations, which means that accurate estimation of the mean for the in-situ geotechnical properties is important.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1209-1216
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• 2008

In order to maximize spectrum efficiency and data rate MIMO(Multiple Input Multiple Output) is adopted to wireless system. OFDM-based WiMAX and LTE accommodate MIMO as mandatory technology. STC(Space Time Coding) and SM(Spatial Multiplexing) are used in downlink while in uplink C-MIMO(Collaborative MIMO) is used to improve data throughput. In this paper conventional pairing schemes, RPS(Random Pairing Scheduling) and DPS(Determinant Pairing Scheduling) are analyzed. From the analysis the performance of DPS algorithm is better than that of RPS because DPS measures orthogonal factor between paired users. However, there are potential problems such as hardware complexity and performance. To overcome the issues Power-Based Scheduling(PBS) algorithm is proposed for C-MIMO. PBS can provide higher performance compared to RPS and dramatically reduce hardware complexity compared to DPS

• Clean Technology
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• v.26 no.2
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• pp.102-108
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• 2020

In recent years, packed column has been widely used in separation processes, such as absorption, desorption, distillation, and extraction, in the petrochemical, fine chemistry, and environmental industries. Packed column is used as a contacting facility for gas-liquid and liquid-liquid systems filled with random packed materials in the column. Packed column has various advantages such as low pressure drop, economical efficiency, thermally sensitive liquids, easy repairing restoration, and noxious gas treatment. The performance of a packed column is highly dependent on the maintenance of good gas and liquid distribution throughout a packed bed; thus, this is an important consideration in a design of packed column. In this study, hydraulic pressure drop, hold-up as a function of liquid load, and mass transfer in the air, air/water, and air-NH₃/water systems were studied to find the geometrical characteristic for raschig super-ring experiment dry pressure drop. Based on the results, design factors and operating conditions to handle noxious gases were obtained. The dry pressure drop of the random packing raschig super-ring was linearly increased as a function of gas capacity factor with various liquid loads in the Air/Water system. This result is lower than that of 35 mm Pall-ring, which is most commonly used in the industrial field. Also, it can be found that the hydraulic pressure drop of raschig super-ring is consistently increased by gas capacity factor with various liquid loads. When gas capacity factor with various liquid loads is increased from 1.855 to 2.323 kg^-1/2 m^-1/2 S^-1, hydraulic pressure drop increases around 17%. Finally, the liquid hold-up related to packing volume, which is a parameter of specific liquid load depending on gas capacity factor, shows consistent increase by around 3.84 kg^-1/2 m^-1/2 S^-1 of the gas capacity factor. However, liquid hold-up significantly increases above it.

• Korean journal of food and cookery science
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• v.28 no.6
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• pp.721-729
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• 2012

This paper aimed to investigate the influence of consumer lifestyle on consumer selection of bakery cafe attributes. Data were collected through a self-administered questionnaire by 403 random consumers between the ages 20s and 30s in several bakery cafes in Seoul and Gyonggi area. Different methods of statistical analysis had been used such as frequency analysis, factor analysis, k-means clustering analysis, cross tabulation, one way ANOVA and Duncan's multiple range test with SPSS for Window 13.0 package. First, when analyzing the 16 questions of comsumer lifestyles, four factors were extracted: 'dining out-oriented factor', 'achievement-oriented factor', 'brand-oriented factor', and 'health-oriented factor'. Second, the respondents were divided into three groups by k-means cluster analysis: no interest group, dining-out & value oriented group, and health-brand oriented group. Third, consumer's bakery cafe attributes were categorized into five factors including 'food', 'convenience and image', 'store promotion', 'positive dining experience', and 'menu & merchandises'. Finally when analyzing the differences in the selection of bakery cafe attributes according to consumer's lifestyles, it showed a significant differences.

• Journal of the Korean Data and Information Science Society
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• v.26 no.4
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• pp.923-930
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• 2015

There exist many competition systems to determine a winner. Many sports games use the 1-in-2 tournament or its modified version to determine a winner. In this paper, we propose a competition system that can be used when there are many candidates and many random referees to evaluate the candidates. These competitions can be found in the cyber space where many users score many competing apps. We study fairness of our proposed competing system called a multi-stage random tournament in terms of equal probabilities. We also formulate the influence factor of a specific referee under some specific conditions.

• Archives of Plastic Surgery
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• v.40 no.3
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• pp.181-186
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• 2013

Background Partial or complete necrosis of a skin flap is a common problem. Polydeoxyribonucleotide (PDRN) can be extracted from trout sperm and used as a tissue repair agent. The aim of this study was to investigate whether PDRN could improve the survival of random pattern skin flaps in rats. Methods Twenty-two male Sprague-Dawley rats were randomly divided into two groups: the PDRN treatment group (n=11) and the control group (n=11). Caudally pedicled random pattern skin flaps were elevated on their dorsal skin and resutured. The treatment group received daily intraperitoneal administration of PDRN (8 mg/kg/day), and the control group received fluid vehicle (NaCl 0.9%, 8 mg/kg/day) from day 0 to day 6. On day 7, the flap survival was evaluated and the harvested tissue surrounding the demarcation line of the necrotic area was stained with H&E, anti-rat vascular endothelial cell growth factor (VEGF) antibody, and PECAM-1/CD31 antibody. Results The average necrotic area of the flap in the PDRN group was significantly smaller when compared with that of the control group. Histologic and immunohistochemical evaluation showed that granulation thickness score and VEGF-positive staining cells were marked higher in the PDRN group than in the control group. PECAM-1/CD31-positive microvascular densities were significantly higher in the PDRN group when compared with the control group. Conclusions This study confirms that PDRN improves the survival of random pattern skin flaps in rats. These results may represent a new therapeutic approach to enhancing flap viability and achieving faster wound repair.

• Smart Media Journal
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• v.5 no.1
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• pp.38-43
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• 2016

As smart environment is spread out in our living environments, the needs of an approach related to Human Computer Interaction(HCI) is increases. One of them is head pose estimation. it related to gaze direction estimation, since head has a close relationship to eyes by the body structure. It's a key factor in identifying person's intention or the target of interest, hence it is an essential research in HCI. In this paper, we propose an approach for head pose estimation with pre-defined several directions by random forest classifier. We use canny edge detector to extract feature of the different facial image which is obtained between input image and averaged frontal facial image for extraction of rotation information of input image. From that, we obtain the binary edge image, and make two accumulated histograms which are obtained by counting the number of pixel which has non-zero value along each of the axes. This two accumulated histograms are used to feature of the facial image. We use CAS-PEAL-R1 Dataset for training and testing to random forest classifier, and obtained 80.6% accuracy.

• Archives of Craniofacial Surgery
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• v.20 no.4
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• pp.239-245
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• 2019

Background: Lidocaine spray is a local anesthetic that improves random-pattern skin flap survival. The fractional ablative carbon dioxide laser (FxCL) produces vertical microchannels that delivers topically applied drugs to the skin. In this study, we hypothesized that FxCL therapy would enhance the lidocaine effect to improve random-pattern skin flap survival in rats. Methods: McFarlane random-pattern skin flaps were elevated in 48 rats, which were divided into four groups according to treatment: FxCL+lidocaine, FxCL, lidocaine, and nontreatment (control). On postoperative day 7, necrotic flap areas, the number of capillary vessels, and neutrophil count were evaluated. Anti-rat vascular endothelial growth factor (VEGF) and CD31 antibody activity were also evaluated by immunohistochemical staining. Results: Flap survival rate was $53.41%{\pm}5.43%$, $58.16%{\pm}4.80%$, $57.08%{\pm}5.91%$, and $69.08%{\pm}3.20%$ in the control, lidocaine, FxCL, and FxCL+lidocaine groups, respectively. Mean neutrophil count in the intermediate zone excluding the necrotic tissue was $41.70{\pm}8.40$, $35.43{\pm}6.41$, $37.23{\pm}7.15$, and $27.20{\pm}4.24cells/field$ in the control, lidocaine, FxCL, and FxCL+lidocaine groups, respectively. Anti-rat VEGF and CD31 antibody activity were the highest in the FxCL+lidocaine group. Conclusion: FxCL with lidocaine had a positive effect on random-pattern skin flap survival in rats. Thus, FxCL with lidocaine spray should be considered as a new treatment option to improve flap viability.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.133-140
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• 2014

The experiment was designed to compare the char combustion kinetics of pulverized Indonesia coals commonly utilized in Korea power plants. The reaction rate of coal char has been formulated using the external and internal effectiveness factors to describe the diffusion effect quantitatively. The Random Pore Model (RPM) was used for applying internal specific surface area as a function of carbon conversion ratio. Reaction rate was obtained from reaction time using the Wire Heating Reactor (WHR) which can heat and measure the char particle temperature at the same time. BET and TGA were used to obtain physical properties such as internal specific surface area and structural parameter. Three kinds of Indonesia Sub-bituminous coals "BARAMULTI, ENERGYMAN, AGM" were used in order to derive the activation energy and pre-exponential factor. The results of this study showed that the effect of internal diffusion than that of external diffusion is the dominant as comparison of kinetics was reflected in external and internal effectiveness factors. For three kinds of coal char, finally, activation energy of intrinsic kinetics indicates 110~118 kJ/mol.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.846-855
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• 2021

Eco-friendly and renewable energy sources are actively being researched in recent times, and of shore wind power generation requires advanced design technologies in terms of increasing the capacities of wind turbines and enlarging wind turbine installation vessels (WTIVs). The WTIV ensures that the hull is situated at a height that is not affected by waves. The most important part of the WTIV is the leg structure, which must respond dynamically according to the wave, current, and wind loads. In particular, the wave load is composed of irregular waves, and it is important to know the exact dynamic response. The dynamic response analysis uses a single degree of freedom (SDOF) method, which is a simplified approach, but it is limited owing to the consideration of random waves. Therefore, in industrial practice, the time-domain analysis of random waves is based on the multi degree of freedom (MDOF) method. Although the MDOF method provides high-precision results, its data convergence is sensitive and difficult to apply owing to design complexity. Therefore, a dynamic amplification factor (DAF) estimation formula is developed in this study to express the dynamic response characteristics of random waves through time-domain analysis based on different variables. It is confirmed that the calculation time can be shortened and accuracy enhanced compared to existing MDOF methods. The developed formula will be used in the initial design of WTIVs and similar structures.