• Title/Summary/Keyword: Mixed-use

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Quadrilateral-Triangular Mixed Grid System for Numerical Analysis of Incompressible Viscous Flow (비압축성 점성 유동의 수치적 해석을 위한 사각형-삼각형 혼합 격자계)

  • 심은보;박종천;류하상
    • Korean Journal of Computational Design and Engineering
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    • v.1 no.1
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    • pp.56-64
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    • 1996
  • A quadrilateral-triangular mixed grid method for the solution of incompressible viscous flow is presented. The solution domain near the body surface is meshed using elliptic grid geneator to acculately simulate the viscous flow. On the other hand, we used unstructured triangular grid system generated by advancing front technique of a simple automatic grid generation algorithm in the rest of the computational domain. The present method thus is capable of not only handling complex geometries but providing accurate solutions near body surface. The numerical technique adopted here is PISO type finite element method which was developed by the present author. Investigations have been made of two-dimensional unsteady flow of Re=550 past a circular cylinder. In the case of use of the unstructured grid only, there exists a considerable amount of difference with the existing results in drag coefficient and vorticity at the cylinder surface; this may be because of the lack of the grid clustering to the surface that is a inevitable requirement to resolve the viscous flow. However, numerical results on the mixed grid show good agreements with the earlier computations and experimental data.

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Wear Analysis of Journal Bearings Operating in a Shaft During Motoring Start-up and Coast-down Cycles - Part II: Wear Analysis of two Journal Bearings Supporting a Misaligned Shaft (모터링 시동 및 시동정지 사이클에서 경사진 축을 갖는 저어널베어링의 마모 해석 - Part II: 경사진 축을 지지하는 두 저어널베어링의 마모해석)

  • Chun, Sang Myung
    • Tribology and Lubricants
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    • v.33 no.4
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    • pp.168-186
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    • 2017
  • This paper presents a wear analysis procedure for calculating the wear of journal bearings during the start-up and coast-down cycles of a motoring stripped-down single cylinder engine operating with a tilted shaft. In order to decide whether the lubrication state of a journal bearing is in the mixed-elasto-hydrodynamic lubrication regime, we utilize lift-off speed and MOFT (most oil film thickness) under mixed-elasto-hydrodynamic lubrication regime at the corresponding aligned shaft. We formulate an equation for the modified film thickness in a misaligned journal bearing considering the additional wear volume described in Part I of this study. For this, we use the calculation results of the degree of misalignment and tilting angle obtained after finding the eccentricities of the two bearings supporting the crankshaft of a single cylinder engine. In this Part II, we calculate the wear of journal bearings using the fractional film defect coefficient, the asperity load sharing factor, and the modified specific wear rate for the application of mixed-elasto-hydrodynamic lubrication regime. We show that the accumulated wear volume after turning the ignition switch on and off once, increases to ${\sigma}=39{\mu}m$ and then decreases from ${\sigma}=39{\mu}m$ with increasing in surface roughness.

Emerging issues and new frameworks for wind loading on structures in mixed climates

  • Solari, Giovanni
    • Wind and Structures
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    • v.19 no.3
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    • pp.295-320
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    • 2014
  • Starting from an overview on the research on thunderstorms in the last forty years, this paper provides a general discussion on some emerging issues and new frameworks for wind loading on structures in mixed climates. Omitting for sake of simplicity tropical cyclones and tornadoes, three main aspects are pointed out. The first concerns the separation and classification of different intense wind events into extra-tropical depressions, thunderstorms and gust fronts, with the aim of improving the interpretation of the phenomena of engineering interest, the probabilistic analysis of the maximum wind velocity, the determination of the wind-induced response and the safety format for structures. The second deals with the use of the response spectrum technique, not only as a potentially efficient tool for calculating the structural response to thunderstorms, but also as a mean for revisiting the whole wind-excited response in a more general and comprehensive framework. The third involves the statistical analysis of extreme wind velocities in mixed climates, pointing out some shortcomings of the approaches currently used for evaluating wind loading on structures and depicting a new scenario for a more rational scheme aiming to pursue structural safety. The paper is set in the spirit of mostly simplified analyses and mainly qualitative remarks, in order to capture the conceptual aspects of the problems dealt with and put on the table ideas open to discussion and further developments.

Measuring Recreation Benefits of Dam Reservoirs in Korea - A Mixed Logit Approach - (댐호수의 특성별 휴양가치 분석)

  • Kwon, Oh Sang;Kim, Won Hee;Lee, Hae Jin;Heo, Jeong Hoi;Park, Doo-Ho
    • Environmental and Resource Economics Review
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    • v.14 no.4
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    • pp.867-891
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    • 2005
  • The purpose of this study is estimating the recreation benefits of the largest 10 dam reservoirs in Korea. A mixed logit or random parameters log it model is constructed and estimated. Not only the recreation value of each dam lake but also the values of the main characteristics of the lakes such as the amount of water reserved, and the availability of boating and fishing are estimated. It is shown that recreation value is not less than other benefit such as irrigation, industrial, municipal use, hydro power, or even flood control benefit.

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Study on liquid carbonation using the recycling water of ready-mixed concrete (레미콘회수수를 이용한 액상탄산화에 관한 연구)

  • Lim, Yun-Hui;Lee, Ju-Yeol;Choi, Chang-Sik;Hong, Bum-Ui;Park, Jin-Won;Lee, Dae-Young;Park, Byung-Hyun
    • Journal of the Korean Applied Science and Technology
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    • v.30 no.4
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    • pp.770-778
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    • 2013
  • In this study, a liquid carbonation method was applied for producing precipitate calcium carbonate by liquid-liquid reaction. We recycled the recycling water of ready-mixed concrete, one of construction waste for use source of carbonate ion. A supernatant separated from the recycling water of ready-mixed concrete, as a result of ICP analysis of a cation, $Ca^{2+}$ was contained up to 1100 ppm. We used MEA as a $CO_2$ absorbent for the liquid carbonation. A precipitate $CaCO_3$ was produced at more than MEA 20 wt%. The precipitate $CaCO_3$ as a final product was separated and dried. The result of XRD was confirmed the generation of $CaCO_3$ to calcite structure.

Mixed Reality(MR) Technology Trends and Development Prospect (혼합현실(Mixed Reality) 기술 동향과 발전 전망)

  • Moon, Hyung-Nam;Cho, Hee-in;Han, Youngmi
    • The Journal of the Convergence on Culture Technology
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    • v.3 no.3
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    • pp.21-25
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    • 2017
  • In this paper, we review relevant technologies of Mixed Reality(MR) and show important components of perspective that can overcome technical limitations of the current MR. An MR technology combines real and virtual objects in a real environment, and runs interactive in real time, and is regarded as an emerging technology in a large part of the future of Information Technology(IT). We've grouped the major obstacles limiting the wider use of MR technologies into three themes: technological limitations (i,e., tracking, rendering, authoring, and registration), user interface(UI) limitations(i.e., UI metaphor for MR interaction), and social acceptance issues.

Risk and Effectiveness of Using Thrombin in Microvascular Free Tissue Transfer

  • Ki, Sae Hwi;Kim, Han Joon
    • Archives of Reconstructive Microsurgery
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    • v.23 no.1
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    • pp.1-7
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    • 2014
  • Purpose: Recent studies have reported on application of fibrin glue composed of fibrinogen and thrombin to nerve anastomosis, which can be another candidate for vessel anastomosis. However, no research regarding the risk and effectiveness of thrombin in microvascular free tissue transfer has been reported. Therefore, the aim of study is to determine the risk and effectiveness of thrombin on microvascular free tissue transfer through clinical cases. Materials and Methods: Twenty-five patients underwent free flap reconstruction for soft tissue defect or bone exposure in our institute from March 2011 to February 2014. In the group using thrombin, dissolved powder thrombin (5,000 IU/amp) was mixed with 10 mL normal saline. Saline mixed with thrombin was applied on the flap, recipient, and around vessel anastomosis. In the control group, free flap was performed using the same method, except using thrombin. We analyzed the results between the two groups. Results: All flaps survived. The group using thrombin included 14 patients and the control group included 11 patients. Hematoma was found in two cases, respectively, in each group. The group using thrombin showed lower incidence of hematoma than the control group. No difference in survival rate of the flap was observed between the thrombin group and the control group. Conclusion: Results of this study showed that use of saline mixed with thrombin in free tissue transfer may be safe and effective for prevention of hematoma formation in the recipient site.

AN APPROACH TO THE TRAINING OF A SUPPORT VECTOR MACHINE (SVM) CLASSIFIER USING SMALL MIXED PIXELS

  • Yu, Byeong-Hyeok;Chi, Kwang-Hoon
    • Proceedings of the KSRS Conference
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    • 2008.10a
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    • pp.386-389
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    • 2008
  • It is important that the training stage of a supervised classification is designed to provide the spectral information. On the design of the training stage of a classification typically calls for the use of a large sample of randomly selected pure pixels in order to characterize the classes. Such guidance is generally made without regard to the specific nature of the application in-hand, including the classifier to be used. An approach to the training of a support vector machine (SVM) classifier that is the opposite of that generally promoted for training set design is suggested. This approach uses a small sample of mixed spectral responses drawn from purposefully selected locations (geographical boundaries) in training. A sample of such data should, however, be easier and cheaper to acquire than that suggested by traditional approaches. In this research, we evaluated them against traditional approaches with high-resolution satellite data. The results proved that it can be used small mixed pixels to derive a classification with similar accuracy using a large number of pure pixels. The approach can also reduce substantial costs in training data acquisition because the sampling locations used are commonly easy to observe.

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Antioxidant Activities of Mixed Grains (혼합잡곡의 항산화 활성 비교)

  • Kang, Dong Seok;Cho, Moon Gu
    • The Korean Journal of Food And Nutrition
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    • v.29 no.5
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    • pp.635-642
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    • 2016
  • The purpose of this study was to investigate the levels of antioxidant activities in some traditional and a few super food mixed rice. Amongst nine chosen samples, traditional five grains were analyzed and results revealed highest content of crude-protein ($8.05{\pm}1.11%$) and lowest crude-fat content ($1.74{\pm}0.29%$); however, the calories was found to be relatively low ($358.05{\pm}0.34kcal$) in the samples. Total polyphenols, flavonoids and tannins were extracted from nine samples with 80% methanol and biochemical activity was measured. The content of total polyphenols, flavonoids and total tannin was $206.5{\sim}452.0{\mu}g/mL$, $0.126{\sim}0.340{\mu}g/mL$, and $548.1{\sim}774.8{\mu}g/mL$, respectively. The traditional five grains showed the highest values except for DPPH radical scavenging activity. DPPH radical scavenging activity was 5 to 40.3% higher in eight samples than the traditional five grains sample. From these results, it is conjectured that a mixture of five grains, might exhibit equal or considerably higher effect as healthy diet when compared to super food. The results from this study would serve as basic data for the use of traditional mixed grains rice diet for good health.

Effect of NaCl on the Mixed Micellar Properties of Sodium Dodecyl Sulfate(SDS) with Tetraethylene Glycol Monododecyl Ether(TGME) (Sodium Dodecyl Sulfate(SDS)와 Tetraethylene Glycol Monododecyl Ether(TGME)의 혼합미셀화에 미치는 NaCl의 효과)

  • Lee, Byung-Hwan
    • Journal of the Korean Chemical Society
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    • v.39 no.12
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    • pp.896-901
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    • 1995
  • The critical micelle concentrations(CMC$^*$) of the mixed surfactant systems of Sodium dodecyl sulfate(SDS) with Tetraethylene glycol monododecyl ether(TGME) in the aqueous solutions of NaCl at $25^{\circ}C$ were determined as a function of the overall mole fraction of $SDS(\alpha1)$ by the use of surface tension method. Various thermodynamic parameters for the micellization of SDS/TGME mixed surfactant systems were calculated and analyzed by means of the equations derived from the nonideal mixed micelle model, based on the pseudo-phase separation model.

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