• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.404-411
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• 2010

The present paper deals with the continuous work of extending multi-dimensional limiting process (MLP), which has been quite successfully proposed on two- and three-dimensional structured grids, onto the unstructured grids. The basic idea of the present limiting strategy is to control the distribution of both cell-centered and cell-vertex physical properties to mimic a multi-dimensional nature of flow physics, which can be formulated as so called the MLP condition. The MLP condition can guarantee a high-order spatial accuracy without yielding spurious oscillations. Recently, MLP slope limiter was proposed based on the MUSCL-type reconstruction in two-dimensional case and it can be readily extended to three-dimensional case. Through various numerical analyses and extensive computations, it is observed that the proposed limiters are quite effective in controlling numerical oscillations and very accurate in capturing both discontinuous and continuous multi-dimensional flow features on 3-D tetrahedral grids.

• 한국주조공학회지
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• 제20권2호
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• pp.80-88
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• 2000

Continuous casting equipment was designed to cast the metallic uranium rods, and a thermal analysis was carried out to calculate the temperature and solidification profiles. Fluid flow and heat transfer analysis model including the effects of phase change was used to simulate the continuous casting process by finite volume method. In the design of continuous casting equipment, the casting speed, pouring temperature and cooling conditions should be considered as significant factors. In this study, the effects of casting speed, pouring temperature, and air gap between the uranium and mold were investigate. The results represented that the temperature and solidification profiles of continuous casting equipment varied with the casting speed, pouring temperature, and air gap.

• 한국기계가공학회지
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• 제11권2호
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• pp.27-33
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• 2012

A marine propeller is designed for preventing cavitation priority. Cavitation is a phenomenon which is defined as the vibration or noise by dropping the pressure on the high-speed rotation of the propeller. There has to be a enough thrust on the low-speed rotation for preventing cavitation. Thus, it has to be considered in the increasing of the number of blade and the angle of wing to design the propeller. In addition, flow resistance will be increasing by narrowing the width between blades. So high quality surface roughness of the hub to minimize flow resistance is required. Interference problems with tool and neighboring surfaces often take place from this kind of characteristics of the propeller. During 5-Axis machining of these propellers, the excessive local interference avoidance, necessary to avoid interference, leads to inconsistency of cutter posture, low quality of machined surface. Therefore, in order to increase the surface quality, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. This study, by using a MC-space algorithm for interference avoidance and a MB-spline algorithm for continuous control, is intended to create a 5-Axis machining tool path with excellent surface quality. Also, an effectiveness is confirmed through a verification manufacturing.

• 한국응용과학기술학회지
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• 제19권4호
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• pp.327-334
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• 2002

Transesterfication of vegetable oils and methanol with alkaline catalyst was carried out to produce biodiesel fuel by continuous process. The process consists of two static mixers, one tubular reactor and two coolers and gave $96{\sim}99$% of methyl ester yield from soybean oil and rapeseed oil. Experimental variables were the molar ratios of methanol to vegetable oil, alkaline catalyst contents, flow rates, mixer element number. The optimum ranges of operating variables were as follows; reaction temperature of $70^{\circ}C$, l:6 of molar ratio of methanol to oil, O.4%(w/w) sodium hydroxide based on oil, static mixer elements number of 24 and 4 min. residence time.

• 한국응용과학기술학회지
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• 제26권4호
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• pp.394-399
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• 2009

The esterification of palmitic acid in Jatropha Oil using 8wt% p-TSA catalyst was done at the 1:8 molar ratio of oil to methanol and $65^{\circ}C$. The conversion of palmitic acid appeared to be 95.3% in 60min. After that, the continuous transesterification of the oil using 0.5wt% KOH, 0.8wt% TMAH mixed catalyst[40vol% KOH(0.5wt%) + 60vol% TMAH(0.8wt%)] and 1.1wt% TMAH was conducted with the flow rates and the molar ratios at $65^{\circ}C$. The overall conversion of Jatropha Oil increased with the decrease of flow rate and showed 95.6% with 9ml/min of flow rate at the 1:8 molar ratio of oil to methanol and $65^{\circ}C$. But it showed 87% with 15ml/min of flow rate at the same conditions. The recovery of methanol(%) appeared to be 86% at the 1:8 molar ratio of oil to methanol, mixed catalyst and $65^{\circ}C$.

• 한국정밀공학회지
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• 제15권3호
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• pp.50-60
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• 1998

This paper is concerned with the design of two residual control charts for real-time monitoring of the continuous flow processes. Two different control charts are designed under the situation that observations are correlated each other. Kalman-Filter based model estimation is employed when the process model is known. A black-box approach, based on Back-Propagation Neural Network, is also applied for the design of control chart when there is no prior information of process model. Performance of the designed control charts and traditional control charts is evaluated. Average run length(ARL) is adopted as a criterion for comparison. Experimental results show that the designed control chart using the Neural Network's modeling has shorter ARL than that of the other control charts when process mean is shifted. This means that the designed control chart detects the out-of-control state of the process faster than the others. The designed control chart using the Kalman-Filter based model estimation also has better performance than traditional control chart when process is out-of-control state.

• 한국물환경학회지
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• 제22권2호
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• pp.203-208
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• 2006

A continuous feed and cyclic draw SBR process was developed to overcome flow rate fluctuation and to maximize organic matters utilization efficiency for nitrogen and phosphorus removal. The developed SBR process was operated with two parallel reactors. Influent was supplied to one reactor which was not obligately aerated. At the same time, the other reactor was just aerated without supplying influent. In addition this mode was changed periodically. Cycle time was 6hr and aeration time ratio($t_{aer}/t_{total}$) was 0.33, respectively. $COD_{cr}$ and SS removal efficiencies of 95% or higher were achieved. Nitrogen removal was so greatly influenced by influent $COD_{cr}/T-N$ ratio. At influent $COD_{cr}/T-N$ ratio of 5.7, removal efficiencies of ammonia-N, T-N and T-P were 96%, 78% and 55%, respectively. Influent $COD_{cr}/T-N$ of 4 or higher ratio was necessary to achieve 60% or higher nitrogen removal. Organic matters of influent was efficiently utilized in denitrification reaction and consumed COD has a good correlation with removed T-N(about 6.5 mgCOD/mgTN). Continuous feed and cyclic draw SBR process could be one of alternative processes for the removal of nutrients in rural area where $COD_{cr}/T-N$ ratio was low and fluctuation of flow rate was severe.

• 콘크리트학회논문집
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• 제26권2호
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• pp.219-227
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• 2014

이 연구는 생물의 서식기반 제공 효과가 있는 다공질의 부석 및 포러스 콘크리트와 대사 작용 및 항산화작용에 의해 유기 오염물질을 분해시켜 오염된 하천수의 수질정화 효과가 있는 유용미생물을 동시에 이용하여 장기간 연속흐름시험을 통한 수질정화 특성을 검토하고자 하였다. 특히 기존의 미생물 탈리 등의 문제점을 해결하기 위하여 이 연구에서는 16S rDNA 염기서열 분석법에 의해 동정된 유용 미생물을 포러스 콘크리트 제조과정에서 각 단계별로 3차 처리하였으며, 최적의 연속흐름 실험을 위한 농도 및 체류시간별에 따른 기초실험을 통하여 운전조건을 검토하였다. 실험 결과 유용미생물을 적용한 포러스 콘크리트는 수질 및 생물에 대한 독성이 없는 것으로 나타났다. 그리고 일반 포러스 콘크리트 보다 유용미생물을 적용한 포러스 콘크리트가 우수한 제거효율을 나타내었으며, 150일 이상 큰 변화를 나타내지 않아 장기간 운전이 가능할 것으로 판단된다. 이와 같이 유용미생물을 적용한 포러스 콘크리트의 장기간 연속흐름 실험으로 오염물질 처리성능에 대한 검토를 통하여 오염된 수질을 향상시킬 수 있을 것이라고 판단되며, 실험과정 중 나타난 문제점들이 보완된다면 하천에 적용하여 유입되는 비점오염원을 저감시킬 수 있을 것으로 기대된다.

• 한국의료질향상학회지
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• 제7권2호
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• pp.244-261
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• 2000

Background : In order to cope with changes in the management environment at hospitals, increased interests are drawn in patient foodservice system on Continuous Quality Improvement Activity as the method of approaching a quality food service and effective management. Thus, as a part of this activity, this study was conducted to evaluate job flow improvement that was already performed and the results of that process at the dietetic department of a university hospital, focusing on improving management. Method : On February 15 of 1998. the dietetic department formed a job flow-improvement to decide on the priority of job flow improvement, and prepared specific action strategies and schedule of the priority: after a 5 month process period, job improvement achieved on June 15. 1998. Also, economic achievement of the task was evaluated through labor productivity analysis and cost-benefit analysis. Results : The patient food service system which was managed decentralized at the present hospital was centralized, some steps of the food service process were integrated, and quality of patient food was improved. Also, as a solution of the problems expected when conducting job flow improvement was made on food service equipments and utensils. The result of evaluating the job flow improvement that labor productivity improved by 18.2% compared to before the improvement and the result of the analysis of cost-benefit showed that Benefit-Cost (B/C) ratio was 2.22. showing financial merit on the investment. Conclusions : Continuous Quality Improvement Activity needs to be initiated and conducted in the future in various areas of hospital foodservice system in order to actively adopt to ever changing hospital management environment. In order to achieve this goal, many researches and more efforts need to be put in by people in charge of hospital food service management, and interests and support are needed from hospital policy makers.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제4권1호
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• pp.93-100
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• 2000

This paper deals with some fundamental matters pertaining to estimation of critical quantities associated with continuous processes which are frequently related to the quality rating of the product. Specifically, it examines bounds on estimation and bounds on the estimation error variance. It draws on recent results from the theory of mathematical inequalities and their applications.