• 대한산업공학회지
• /
• 제14권2호
• /
• pp.131-141
• /
• 1988

As flexible manufacturing technology has become available across a broad range of applications, an increasingly large number of firms have confronted decisions about when to adopt the FMS technology and the size of FMS at that time. For small to medium size firms that should invest under budget limitation and high investment risk, proper size of FMS adoption at proper time is very important. In this paper the discrete optimal control theory has been used to make decisions about the size and timing of FMS capacity expansion over a planning period. Sensitivity analysis is presented for analysing the behavior of the model to variations of model parameters.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2016년도 추계학술대회
• /
• pp.489-492
• /
• 2016

Transportation in the logistics, many business organizations are engaged in monitoring and tracking the vehicles in order to improve logistics services, reduce expenses and secure security in cargo transportation. It is saving time and money by tracking and monitoring vehicles which transport cargo in supply chain of logistics. Therefore the main issue of delivery flow is to improve services, and ensure the safety in transportation system. This article suggests the tracking and monitoring model to keep safety transports on ICT network. It focuses on precise delivery control by monitoring and tracking vehicles to save time and costs. The status of product movement is analyzed for proper decision making. The vehicle embedded with RFID is automatically tracked in the movement process by tracking and monitoring model. The main role keeps safety tracking to reduce costs and to deliver products at proper time and location.

• 소성∙가공
• /
• 제27권1호
• /
• pp.28-36
• /
• 2018

Electromagnetic forming is a type of high-speed forming process to deform a workpiece through a Lorentz force. As the high strain rate in an electromagnetic-forming simulation causes infeasibility in determining constitutive parameters, we employed inverse parameter estimation in the previous study. However, the inverse parameter estimation process required us to spend considerable time, which leads to an increase in computational cost. To overcome the computational obstacle, in this research, we applied two types of surrogate modeling methods and compared them to each other to evaluate which model is best for the electromagnetic-forming simulation. We exploited an artificial neural network and we reduced-order modeling methods. During the construction of a reduced-order model, we extracted orthogonal bases with proper orthogonal decomposition and predicted basis coefficients by utilizing an artificial neural network. After the construction of the surrogate models, we verified the artificial neural network and reduced-order models through training and testing samples. As a result, we determined the artificial neural network model is slightly more accurate than the reduced-order model. However, the construction of the artificial neural network model requires a considerably larger amount of time than that of the reduced-order model. Thus, a reduced order modeling method is more efficient than an artificial neural network for estimating the electromagnetic forming and for the rapid approximation of structural simulations which needs repetitive runs.

• Nuclear Engineering and Technology
• /
• 제55권8호
• /
• pp.2835-2843
• /
• 2023

After an emergency shutdown of a lead-bismuth fast reactor, thermal stratification occurs in the upper Plenum, which negatively impacts the integrity of the reactor structure and the residual heat removal capacity of natural circulation flow. The research on thermal stratification of reactors has mainly been conducted using an experimental method, a system program, and computational fluid dynamics (CFD). However, the equipment required for the experimental method is expensive, accuracy of the system program is unpredictable, and resources and time required for the CFD approach are extensive. To overcome the defects of thermal stratification analysis, a high-precision full-order thermal stratification model based on CFD technology is prepared in this study. Furthermore, a reduced-order model has been developed by combining proper orthogonal decomposition (POD) with Galerkin projection. A comparative analysis of thermal stratification with the proposed full-order model reveals that the reduced-order thermal stratification model can well simulate the temperature distribution in the upper plenum and rapidly elucidate the thermal stratification interface characteristics during the lead-bismuth fast reactor accident. Overall, this study provides an analytical tool for determining the thermal stratification mechanism and reducing thermal stratification.

• 한국식품영양학회지
• /
• 제21권1호
• /
• pp.97-105
• /
• 2008

An IPA model was used to evaluate customer service encounters at a large food court; also the gaps between importance and performance from were also evaluated from both perspectives. The findings of this study will be applied in order to improve service quality at various large food service operations. A total of 298 customers from a large shopping mall food court completed the study questionnaire, asking them to evaluate the important and performance attributes of service. Seven underlying dimensions were identified and labeled by factor analysis: factor 1 was "safety": factor 2 "time": factor 3 "atmosphere": factor 4 "quality of food": factor 5 "menu attributes": factor 6 "comfort": and the last and seventh factor was "comprehension". As a result of IPA analysis the overall mean scores between the importance attributes and performance attributes showed significant differences by independent t-tests(p<0.001). Quadrant I was classified with unnecessary items including interior design, proper lighting, suitable chairs, and proper room temperature. In quadrant II thirteen variables showed high scores for both importance and performance, such as various menu choices, hygienic food, dishes, chairs, food court, kitchen, and employees; proper ventilation, employee kindness, waiting time to order, and received food; automatic system for ordering-serving. Quadrant III included eight variables identified as low priority, including appearance of food, nutrient content of food, proper portions, new menu, proper music, proper location of cashier, services for children and efficiency of movement. In quadrant IV six variables were included as areas to focus management's efforts, such as food taste, proper food temperature, use of safe food materials, maintenance of food quality, existence of preferred foods, and proper food prices. These results suggest that food court customers have interests that are distinct from restaurant customers and may need to be treated differently. It is anticipated that this data will be useful to the foodservice industry in order to segment customer characteristics by different dinning behaviors.

• 품질경영학회지
• /
• 제41권1호
• /
• pp.109-118
• /
• 2013

혼합물 성분비와 공정변수들에 관한 실험 자료가 주어진 경우에, 주어진 실험 자료를 잘 설명하는 적절한 결합모형을 찾는 것은 중요한 과제이다. 우선 모형 선택 기준에 부합하는 시작모형의 후보들을 교적모형의 범주에서 찾고, 다음으로 선택된 시작모형을 완전모형으로 간주하여, 모형의 간결성의 원칙에 따라서 완전모형의 부분모형으로 구성된 적절한 결합모형들을 찾는데, 일반적으로 여러 개의 결합모형들이 추천된다. 주어진 실험 자료에 대한 적절한 모형으로 여러 개의 모형이 추천된 경우에, 엔지니어들의 실용적인 관심사는 각각의 결합모형에 대한 반응변수의 기대값의 예측치와 예측치의 표준편차의 추정치를 동시에 최적으로 하는 최적조건의 찾기이다. 이를 위한 실용적인 방법으로 반응변수가 여러 개인 다중 반응표면 분석에서 동시 최적화 기법을 활용한 최적조건을 찾는 방법을 제안하고, 잘 알려진 혼합물성분-공정변수 실험 자료에 대해서 Design Expert 8.0을 활용하여 적절한 결합모형들을 찾고, 이 모형들을 동시에 최적화하는 최적조건 찾기가 예시된다.

• 대한토목학회논문집
• /
• 제31권5D호
• /
• pp.633-639
• /
• 2011

적정수준의 택시규모를 산정하기 위해 본 연구에서는 타코미터 데이터 분석을 통해 법인택시와 개인택시의 운행실태를 분석하였다. 대상예시지역으로 평택시를 선정하여, 도시특성을 기반으로한 택시총량산정 수리모형을 개발하였다. 개발된 도시특성기반 모형의 분석결과 결정계수(수정된 R제곱) 값이 0.970로 모형이 유의한 것으로 나타났다. 모형적용결과 평택시에 적합한 택시총량은 2014년까지 총1,794대로 이는 2009년 기준년도보다 214대 많은 것으로 분석되었다. 또한 실제 택시의 운영데이터를 기반으로한 실차율에 의한 택시총량산정 모형을 분석하였다. 실차율모형 적용결과 2014년까지 총1,224대로 이는 2009년 보다 356대 적은 것으로 분석이 되었다. 결론적으로 평택시의 택시총량은 실차율모형과 도시특성을 반영한 두 모델을 적용한 결과 2014까지 평택시의 택시총량공급계획은 2009년 1,580보다 71대 적은 1,509대로 분석되었다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
• /
• pp.789-794
• /
• 2002

The relationship is investigated between material modeling of concrete and the evaluation procedure of thermal stress by the hydration heat. In this respect, some important points are suggested to which special attention should be paid to reasonably evaluate the thermal stress using the widely-used structural analysis programs. This study indicates that proper material model should be used to draw incremental stress evaluation that takes into account the change of elastic modulus with time. Some correction techniques are also presented when using the program that don't have proper built-in procedure for the calculation of the thermal stress.

• 한국운동역학회지
• /
• 제24권4호
• /
• pp.375-383
• /
• 2014

The purpose of this study was to assess the inter-segmental trunk motion during which multi-segmental movements of the spinal column was designed to interpret the effect of segmentation on the total measured spine motion. Also it analyzed the relative motion at three types of the spine models in drop landing. A secondary goal was to determine the intrinsic algorithmic errors of spine motion and the usefulness of such an approach as a tool to assess spinal motions. College students in the soccer team were selected the ten males with no history of spine symptoms or injuries. Each subject was given a fifteen minute adaptation period of drop landing on the 30cm height box. Inter-segmental spine motion were collected Vicon Motion Capture System (250 Hz) and synchronized with GRF data (1000 Hz). The result shows that Model III has a more increased range of motion (ROM) than Model I and Model II. And the Lagrange energy has significant difference of at E3 and E4 (p<.05). This study can be concluded that there are differences in the three models of algorithm during the phase of load absorption. Especially, Model III shows proper spine motion for the inter-segmental joint motion with the interaction effects using the seven segments. Model III shows more proper observed values about dynamic equilibrium than Model I & Model II. The findings have shown that the dynamic stability strategy of Model III toward multi-directional spinal motion supports for better function of the inter-segmental motor-control than the Model I and Model II.

• 한국대기환경학회지
• /
• 제22권1호
• /
• pp.135-143
• /
• 2006

The objective of this study is to develop PSCF (potential source contribution function) program and determine the optimal values of control parameters to enhance the prediction of PSCF modeling. This study provides an important information and methodologies that can be used to get better results of locating influencing sources, especially unknown and fugitive sources. To determine proper values of control parameters in PSCF model, the diagnostic assessment on the results obtained by the various input conditions was carried out. PSCF model has created and improved from version 1.0 to version 7.0 since 200 I and the measured data (at least > 100) of receptor, and the values of control input parameters should be arranged and determined to obtain reliable results in PSCF modeling. The size of modeling domain must be determined to include enough trajectories to get reliable results. And the size of grid is recommended to be 2.5 $\sim$ 5 degrees for global scale, 0.2 $\sim$ 1 degrees for regional scale and 0.05 degree for local scale.