• 대한기계학회논문집A
• /
• 제21권2호
• /
• pp.327-336
• /
• 1997

This paper addresses an analytical approach to the mechanical error analysis and tolerance design of a four-bar path generator with lubricated joints. The mobility method is applied to consider lubrication effects and the four-bar path generator is stochastically modeled by using the clearance vector model for methanical error analysis. To show the validity of the proposed method, the mechanical errors obtained by applying the method to a four-bar path generator are compared with those by Monte Carlo simulation. Based on this analytical method, an optimal tolerance design problem is formulated and solved for the four-bar path generator.

• 한국전산유체공학회지
• /
• 제4권1호
• /
• pp.34-40
• /
• 1999

Drag reduction on vehicles are the main concern for the body shape designers in order to lower the fuel consumption rate and to aid the driving stability. The drag of bluff bodies like transportation vehicles is mostly pressure drag due to the flow separation, which can be minimized by controlling the location and size of the separation bubble. In the present study, the TURBO-3D code is incorporated with optimal algorithm based on analytical approximation method to obtain an optimal afterbody shape of the MIRA Model corresponding to the lowest drag coefficient. For this purpose three mutually independent afterbody angles are chosen as design variables, while the drag coefficient is chosen as an objective function. It is demonstrated in the present study that an optimal body shape having the lowest drag coefficient which is about 6% lower than that of the original shape has been successfully obtained within number of iterations of tile optimal design loop.

• 산업경영시스템학회지
• /
• 제17권30호
• /
• pp.135-145
• /
• 1994

There has been increasing interest in modeling the effect of buffer stock in automatic flow lines such as transfer line, assembly line and process line. The purpose of this paper is to determine the optimal buffer stock for a two-stage process line of industry that minimize a expected cost considering line efficiency and buffer stock Analytical method for the simplified model is applied and computer simulation is conducted to real numerical example.

• 대한산업공학회지
• /
• 제16권1호
• /
• pp.59-65
• /
• 1990

In the design of AGVS (Automated Guided Vehicle Systems), one of the important problem is to determine the number of AGVs required to provide a given level of transport service. At present, there are two kind of methods to determine the number of AGVs, the one is to use the mathematical model, the other is to use the simulation technique. Among these, simulation based technique is more reliable than analytical method. In this sense, this paper intend to determine the optimal number of AGVs using personal computer simulation by SIMAN Ver.3.5.

• 대한기계학회논문집A
• /
• 제20권1호
• /
• pp.180-188
• /
• 1996

The stress singularity of a sharp wedge contacting a half plane can be avoided by changing the wedge shape. Shape optimization is accomplished with the geometric strain method (GSM), an optimality criterion method. Several numerical examples are provided for different materials in the wedge and half plane to avoid stress singularity neal the sharp corner of the wedge. Optimum wedge shapes are obtained and critical corner angles are compared with the angles from analytical contact mechanics. Numerical results are well matched to analytical and experimental results. It is shown that shape optimization by the geometric strain method is a useful tool to reshape the wedge and to avoid a stress singulatiry. The method applies to more general geometries where the singular behavior would be difficult to avoid by classical means.

• 분석과학
• /
• 제34권4호
• /
• pp.180-190
• /
• 2021

This study compared the efficacy of chiral GC and chiral HPLC for the analysis of nicotine. To develop a suitable dispersive liquid-liquid microextraction (DLLME) method, the following parameters were optimized: pH, extraction solvent, dispersive solvent, type and quantity of salt, and laboratory temperature. The validation of the method was carried out by the established HPLC method. The LODs were 0.11 ㎍/mL and 0.17 ㎍/mL for the (S)- and (R)- enantiomers, respectively. The LOQs were 0.30 ㎍/mL and 0.44 ㎍/mL, respectively. The optimal calibration range was between 0.30-18 ㎍/mL and 0.44-4.40 ㎍/mL, respectively, and the correlation coefficient (r²) was 0.9978-0.9996. The intra-day accuracy was 79.9-110.6 %, and the intra-day precision was 1.3-12.0 %. The inter-day accuracy was 87.8-108.0 %, and the inter-day precision was 4.0-12.8 %. E-liquid and biological fluids (urine and saliva) were analyzed using the established method.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 1998년도 춘계 학술대회논문집
• /
• pp.67-74
• /
• 1998

Reducing drag of vehicles are the main concern for the body shape designers in order to lower fuel consumption rate and to aid the driving stability. The drag of bluff bodies like transportation vehicles is mostly pressure drag due to the flow separation, which can minimized by controlling the location and size of the separation bubble. In the present study, the TURBO-3D code is incorporated with optimal algorithm based on analytical approximation method to obtain optimal afterbody shape of the MIRA Model corresponding to the lowest drag coefficient. For this purpose three mutually independent afterbody angles are chosen as design variables, while the drag coefficient is chosen as an objective function. It is demonstrated in the present study that an optimal body shape having lowest drag coefficient which is about $6\%$ lower than that of the original shape has been successfully obtained within number of iterations of the optimal design loop.

• 한국환경과학회지
• /
• 제24권7호
• /
• pp.939-946
• /
• 2015

Hydraulic conductivity is an important parameter in the analytical model of groundwater. This study analyzed the groundwater movement characteristics by estimating optimal parameters according to hydraulic conductivity input methods with the MODFLOW model which is widely used. It first estimated the optimal parameters by dividing hydraulic conductivity zones by attitude. Next, it estimated optimal parameters by geological characteristic. It analyzed the groundwater movement characteristics by applying the recharge quantity and amount of evapotranspiration of drought periods and flood years with the estimated parameters. As the result was analyzed that there are differences of observation water level values according to hydraulic conductivity input methods but there is no big differences of overall groundwater movement characteristics by hydraulic conductivity input method, the two methods have found to be applicability in analyses of groundwater. So, it is judged that studies on more exact application of hydraulic conductivity and the application methods are needed.

• Ocean Systems Engineering
• /
• 제5권4호
• /
• pp.279-299
• /
• 2015

Suction anchors are widely adopted and play an important role in mooring systems. However, how to reliably predict the failure mode and ultimate pullout capacity of the anchor in sand, especially by an easy-to-use theoretical method, is still a great challenge. Existing methods for predicting the inclined pullout capacity of suction anchors in sand are mainly based on experiments or finite element analysis. In the present work, based on a rational mechanical model for suction anchors and the failure mechanism of the anchor in the seabed, an analytical model is developed which can predict the failure mode and ultimate pullout capacity of suction anchors in sand under inclined loading. Detailed parametric analysis is performed to explore the effects of different parameters on the failure mode and ultimate pullout capacity of the anchor. To examine the present model, the results from experiments and finite element analysis are employed to compare with the theoretical predictions, and a general agreement is obtained. An analytical method that can evaluate the optimal position of the attachment point is also proposed in the present study. The present work demonstrates that the failure mode and pullout capacity of suction anchors in sand can be easily and reasonably predicted by the theoretical model, which might be a useful supplement to the experimental and numerical methods in analyzing the behavior of suction anchors.

• Journal of Radiation Protection and Research
• /
• 제19권2호
• /
• pp.99-107
• /
• 1994

방사선방호의 최적화 검토에 대하여 계층화 의사결정법에 의한 의사결정과정의 예시적 방법론이 제시되었다. ICRP Publ. 55의 우라늄 광산 환기시스템 결정 사례의 방호데이터를 이용하여 주어진 방호선택대안 가운데 최적안을 도출하는 과정을 나타내었다. 이 AHP 방법은 방사선방호의 최적안 결정에 있어 방사선방호 관리자 또는 의사 결정자가 이해하기 쉽고 간편한 방법으로 판단된다.