• Archives of Plastic Surgery
• /
• v.46 no.4
• /
• pp.371-374
• /
• 2019

Umbilical preservation can be challenging, particularly in complex cases involving simultaneous ventral hernia repair and abdominoplasty. Although the umbilicus serves no functional purpose, removal of the umbilicus can draw unwanted attention to the abdominal area and can cause emotional distress to patients. There are several well documented options for umbilical reconstruction. We present a new umbilical reconstruction technique relevant for such cases. This neoumbilicoplasty allows for preservation of the original umbilicus with relocation and reconstruction using local flaps. The technique is relatively simple and the time needed is minimal. The result is a natural, well positioned umbilicus using the principles of spare part surgery.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.20 no.44
• /
• pp.123-128
• /
• 1997

A data base design framework for predictive a preventive-maintenance system is presented in this paper in order to effectively control machines and reduce accident rates in the workplace. The data base is designed to meet general management requirements to evaluate different maintenance strategies. There are seven data files: the equipment list maintenace pesonnel, maintenance history, maintenance specification, spare part, maintenance equipment, and maintenance schedules. Each data base file has several record based upon data acquisition.

• Communications of the Korean Mathematical Society
• /
• v.11 no.3
• /
• pp.601-611
• /
• 1996

In this paper, we introduce the notion of weakly associative BCI-algebras and investigate structure of it. Some of characterizations of elements of the quasi-associative part Q(X) of a BCI-algebra X are shown.

• Journal of Internet Computing and Services
• /
• v.18 no.1
• /
• pp.121-129
• /
• 2017

Demand forecasting is one of the most critical tasks in defense logistics, because the failure of the task can bring about a huge waste of budget. Up to date, ROK-MND(Republic of Korea - Ministry of National Defense) has analyzed past component consumption data with time-series techniques to predict each component's demand. However, the accuracy of the prediction still needs to be improved. In our study, we attempted to find consumption pattern using data mining techniques. We gathered an 18,476 component consumption data first, and then derived diverse features to utilize them in identification of demanding patterns in the consumption data. The results show that our approach improves demand forecasting with higher accuracy.

• Journal of the Korea Society for Simulation
• /
• v.21 no.3
• /
• pp.79-88
• /
• 2012

Recently, the study in efficient operation, maintenance, and equipment-design have been growing rapidly in military industry to meet the required missions. Through out these studies, the importance of Concurrent Spare Parts(CSP) are emphasized. The CSP, which is critical to the operation and maintenance to enhance the availability, is offered together when a equipment is delivered. Despite its significance, th responsibility for determining the range and depth of CSP are done from administrative decision rather than engineering analysis. The purpose of the paper is to optimize the number of CSP per item using simulation and multiple regression. First, the result, as the change of operational availability, was gained from changing the number of change in simulation model. Second, mathematical regression was computed from the input and output data, and the number of CSP was optimized by multiple regression and linear programming; the constraint condition is the cost for optimization. The advantage of this study is to respond with the transition of constraint condition quickly. The cost per item is consistently altered in the development state of equipment. The speed of analysis, that simulation method is continuously performed whenever constraint condition is repeatedly altered, would be down. Therefore, this study is suitable for real development environment. In the future, the study based on the above concept improves the accuracy of optimization by the technical progress of multiple regression.

• Korean System Dynamics Review
• /
• v.11 no.2
• /
• pp.119-138
• /
• 2010

This study introduces the system dynamics model that simulate total operational availability when 10 equipments made of 3 major components are serviced under the constrains of the maintenance capacity level and the number of spare parts. This simulation is designed on the base of reliability engineering concept so failures of components happens with the rule of engineering factors like the mean time between failure(MTBF) of component and the next failure time of one component is effected by the conditions of other components. We analysed availability of 10 equipments under 121 constrains and executed multiple regression analysis with the simulation result. The analysis provide the managerial insight in the service fields with operation many equipments.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.21 no.48
• /
• pp.113-122
• /
• 1998

In this paper we consider the CSP requirements determination problem of new equipment(machine) system. For the newly procured equipment systems, mathematical analyses are made for the system which is constructed with the consumable parts to derive the associated CSP requirement determination model in mathematical expression. Based on these analyses, a mathematical model is derived for making an optimal CSP requirement determination subject to tile constraint of satisfying any given operational availability limitation. We assume that the failure of a part follows a Poisson process. Firstly, the operational availability concept in CSP is defined and the relation between the general system availability and the operational availability is established. Secondly, the problem is formulated as the cost minimization problem that should satisfy the operational availability limitation, and then, using the generalized Lagrange multipliers method, the optimal solution procedure is derived.

• Journal of Powder Materials
• /
• v.24 no.6
• /
• pp.494-507
• /
• 2017

A three-dimensional physical part can be fabricated from a three-dimensional digital model in a layer-wise manner via additive manufacturing (AM) technology, which is different from the conventional subtractive manufacturing technology. Numerous studies have been conducted to take advantage of the AM opportunities to penetrate bespoke custom product markets, functional engineering part markets, volatile low-volume markets, and spare part markets. Nevertheless, materials issues, machines issues, product issues, and qualification/certification issues still prevent the AM technology from being extensively adopted in industries. The present study briefly reviews the standard classification, technological structures, industrial applications, technological advances, and qualification/certification activities of the AM technology. The economics, productivity, quality, and reliability of the AM technology should be further improved to pass through the technology adoption lifecycle of innovation technology. The AM technology is continuously evolving through the introduction of PM materials, hybridization of AM and conventional manufacturing technologies, adoption of process diagnostics and control systems, and enhanced standardization of the whole lifecycle qualification and certification methodology.

• The Journal of the Korea Contents Association
• /
• v.9 no.8
• /
• pp.166-177
• /
• 2009

As the aged have increased due to the progress of medical science and the low birth-rate, the various cultures and industries for them are on the rise. The aged want to enjoy the diverse social activities and the culture content for spending their spare time. But they are liable to be restricted by the activities due to the physical, psychological, and mental disorder. This paper suggests a tangible bicycle game content and interface with the function of training and improving the lower part of body that is necessary to the old people's movement. The suggested game content can attract the interest of the aged by the familiar device, bicycle, and the game design for the old people. We develop the sensory interface for augmenting the immersion in the game. The aged can enjoy their spare time doing both game and exercise through the sensory interface and the real-time display of 3D graphics.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.41 no.1
• /
• pp.50-58
• /
• 2018

Intermittent demand is a demand with a pattern in which zero demands occur frequently and non-zero demands occur sporadically. This type of demand mainly appears in spare parts with very low demand. Croston's method, which is an initiative intermittent demand forecasting method, estimates the average demand by separately estimating the size of non-zero demands and the interval between non-zero demands. Such smoothing type of forecasting methods can be suitable for mid-term or long-term demand forecasting because those provides the same demand forecasts during the forecasting horizon. However, the smoothing type of forecasting methods aims at short-term forecasting, so the estimated average forecast is a factor to decrease accuracy. In this paper, we propose a forecasting method to improve short-term accuracy by improving Croston's method for intermittent demand forecasting. The proposed forecasting method estimates both the non-zero demand size and the zero demands' interval separately, as in Croston's method, but the forecast at a future period adjusted by binomial weight according to occurrence probability. This serves to improve the accuracy of short-term forecasts. In this paper, we first prove the unbiasedness of the proposed method as an important attribute in forecasting. The performance of the proposed method is compared with those of five existing forecasting methods via eight evaluation criteria. The simulation results show that the proposed forecasting method is superior to other methods in terms of all evaluation criteria in short-term forecasting regardless of average size and dispersion parameter of demands. However, the larger the average demand size and dispersion are, that is, the closer to continuous demand, the less the performance gap with other forecasting methods.