• Design & Manufacturing
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• v.10 no.2
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• pp.24-28
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• 2016

In this study, relevant to impact extrusion process of the rectangular batter case for electric vehicles, numerical and experimental analyses were conducted to reduce the earring defects induced in the unevenness of metal flow. Since the earring is caused by the non-uniform metal flow induced in the friction and aspect ratio in the bottom section. As a way to reduce the earring, variable land die concept was applied. In order to analyze numerically the complex metal flow by using commercial finite element package, DEFORM 3D, impact extrusion process was simplified in upsetting mode at bottom section and extrusion mode at land section. The impact extrusion experiments were conducted to verify the assessment of process parameter for impact extrusion. As results, variable land die which has longer longitudinal section makes reduce earring defects. In addition, it was confirmed that the effect that slug shape like dog-bone also can reduce the earring. This study is expected to be able to present the useful design guidelines for manufacturing the battery case.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.2
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• pp.1-13
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• 2014

In IEEE 802.11p/1609-based vehicular networks, vehicles are allowed to exchange safety and control messages only within time periods, called control channel (CCH) interval, which are scheduled periodically. Currently, the length of the CCH interval is set to the fixed value (i.e. 50ms). However, the fixed-length intervals cannot be effective for dynamically changing traffic load. Hence, some protocols have been recently proposed to support variable-length CCH intervals in order to improve channel utilization. In existing protocols, the CCH interval is subdivided into safety and non-safety intervals, and the length of each interval is dynamically adjusted to accommodate the estimated traffic load. However, they do not consider the presence of hidden nodes. Consequently, messages transmitted in each interval are likely to overlap with simultaneous transmissions (i.e. interference) from hidden nodes. Particularly, life-critical safety messages which are exchanged within the safety interval can be unreliably delivered due to such interference, which deteriorates QoS of safety applications such as cooperative collision warning. In this paper, we therefore propose a new interference-aware Dynamic Safety Interval (DSI) protocol. DSI calculates the number of vehicles sharing the channel with the consideration of hidden nodes. The safety interval is derived based on the measured number of vehicles. From simulation study using the ns-2, we verified that DSI outperforms the existing protocols in terms of various metrics such as broadcast delivery ration, collision probability and safety message delay.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.249-263
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• 1997

This paper addresses the parts route selection and economic design in flexible manufactuirng system (FMS). Parts are processed through several stage workstations according to operation sequences. The machine of each workstation can do multiple operation functions. And the operation stage of a part can be processed in several workstations, which are non-identical in functional performance. The objective of this paper is to determine the processing routes of parts, number of machine at each workstation, number of vehicle and makespan time. Two models are suggested. One is assumed that the operation stage of parts can be processed at the only one among several available workstations. Other is assumed that the operation stage of parts is allowed to be processed at several workstations. Parts are transported by automated guided vehicles (AGVs). The decision criteria is to minimize the sum of processing cost, travel cost, setup cost and overhead cost. The formulation of models is represented. A solution algorithm is suggested, and a numerical example is shown.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.46
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• pp.19-32
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• 1998

This paper addresses the processing route of parts and economic design in flexible manufacturing systems (FMSs) employing AGVs for Transport. Parts are processed through several workstations according to operation sequences. The machine of each workstation can do multiple operation functions. The operation stage of a part can be processed in several workstations, which are non-identical in functional performance. The objective of this paper is to determine the processing route of parts, number of machines at each workstation, number of vehicles. The model is assumed that the operation stage of parts can be processed at the only one among several available workstations. Parts are transported by automated guided vehicle system(AGVS). The decision criteria is to minimize the sum of processing cost, travel cost, operating cost. A model formulation is represented. A solution algorithm is suggested by using mathematical programming and simulation technique, and a numerical example is shown.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.220-229
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• 2023

The development of logistics technology due to the 4th Industrial Revolution and logistics 4.0 has changed the logistics environment from offline to online, and the growth of the online market has accelerated due to the recent increase in non-face-to-face delivery due to COVID-19. Such growth in the online market has expanded the logistics market for delivery, and contributes to creating an advanced logistics ecosystem as last mile services and logistics technologies begin to grow together. As traffic and environmental problems arise as a result, interest in transportation means of cargo increases, and changes to cargo electric vehicles and delivery cycles are being considered. However, since mass transportation of transportation focused on terminal delivery such as cargo electric vehicles and delivery cycles is limited in handling large quantities in urban areas, methods for efficiently transporting cargo while considering the environment are being devised. In order to solve such environmental problems and increase the efficiency of logistics delivery in urban areas, technologies using underground spaces based on existing urban railroads are being developed. In this study, a study was conducted on the establishment of evaluation criteria for selecting a test bed, which is a space for applying the system.

• Current Industrial and Technological Trends in Aerospace
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• v.7 no.1
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• pp.97-104
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• 2009

Successful separation of satellites from launch vehicles and release its appendages such as solar arrays and antennas are one of the most important tasks for mission accomplishment during in-orbit maneuver. Especially, specific release devices called NEA(Non-Explosive Actuator) have been widely adopted to perform safe separation and release due to its outstanding performance of low functional shock (below 500g), no contamination and easy handing as opposed to the pyroshock device. In the paper, various kinds of NEA and its history of development are reviewed along with a summary on the domestic research trend.

• Journal of the Korea Safety Management & Science
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• v.9 no.4
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• pp.99-112
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• 2007

In most recent years, the business competition has spreads over all fields of corporations and their management area regardless of time and place, which makes the survival environment of each enterprise fiercer. In order to secure a high position in the competitive market, the various firms has implemented many methods related to price, quality, and service efficiency. However, the implementation with only low price or high quality might be helpless to hold a high position in modem market. Moreover more attention should be paid to the internal business processes of an organization. Therefore, a new and different method should be searched or developed in order to win the competitive power among other enterprises. This research will focus on the improvement of the business processes within the non-manufacturing industry by applying Lean Six Sigma methodology. DMAIC method will be applied to improve the inbound and outbound logistics processes, manage the inbound and outbound vehicles, and control the receiving and shipping activities.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.4
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• pp.241-247
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• 2010

Recently, indoor air quality (IAQ) has been one of the major concerns of people. Indoor parking lots are subject to be exposed to high concentrations of air pollutants emitted from vehicles. This study was performed to investigate indoor air quality (IAQ) at indoor parking lots. Sampling sites were selected 5 indoor parking lots. Target indoor air quality parameters include a number of criteria pollutants such PM$_{10}$, CO, CO$_2$, and HCHO. In addition, a variation of IAQ according to ventilation system operating was measured at C site (underground parking lot). In general, all pollutants were maintained below indoor air quality maintenance standards. The indoor air quality at indoor parking lots was affected by the availability of the ventilation facility and their operation frequency. At the underground parking lot (C site) with ventilation system, TVOC concentration according to ventilation system operating were found to be lower operating (488.2 ${\mu}g/m^3$) than non-operating (1,401.2 ${\mu}g/m^3$).

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.4
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• pp.54-63
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• 2002

In recent years, mechanical systems such as high speed vehicles and railway trains moving on elastic beam structures have become a very important issue to consider. In this paper, a general approach, which can predict the dynamic behavior of a constrained mechanical system moving on a flexible beam structure, is proposed. Various supporting conditions for the foundation support are considered for the elastic beam structure. The elastic structure is assumed to be a non-uniform and linear Bernoulli-Euler beam with a proportional damping effect. Combined differential-algebraic equation of motion is derived using the multi-body dynamics theory and the finite element method. The proposed equations of motion can be solved numerically using the generalized coordinate partitioning method and predictor-corrector algorithm, which is an implicit multi-step integration method.

• IE interfaces
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• v.14 no.2
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• pp.111-119
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• 2001

A tandem AGV system is based on partitioning all the stations into non-overlapping single vehicle closed loops with additional stations provided as an interface between adjacent loops. For an efficient use of this configuration, it is required to solve the load routing problem(LRP), which is primarily based on the fact that a load may be handled by several vehicles and moved through several loops before it reaches its destination. In this paper, a heuristic based on genetic algorithm(GA) is first developed to solve LRP. The first model obtains the optimal route of each job and the optimal direction of each loop when the vehicle in each loop travels unidirectionally. The second GA model obtaines the optimal polling sequence of the empty vehicle in each loop, when the vehicle can move bidirectionally.