• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.737-741
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• 2003

The wind power system is spotlighted as one of the no-pollution power generation systems. The system uses winds as power source that are rotated the blade and the rotating power from blade generate the electricity power. Gearbox needs to transfer the wind powers that have the high-torque-low-speed characteristics to generator that have the low-torque-high-speed characteristics. Because the wind power system generally locates the remote place like seaside or mountainside and the gearbox installs on the limited and high placed space, the gearbox of the wind power system is required the optimal space design and high reliability. In this paper, the structure of the gearbox is proposed to achieve the optimal space and efficiency by compounding the planetary gear train that has the high power density and parallel type gear train that has the long service life. The design parameters that are affected the service life are studied. The gear ratio and face width are investigated as an affected parameter for design sensitivity of service life.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.2
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• pp.161-169
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• 2016

This paper is intended to propose a novel approach to select an optimal site for a small-scaled artificial recharge system installation using TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) with geospatial data. TOPSIS is a MCDM (Multi-Criteria Decision Making) method to choose the preferred one of derived alternatives by calculating the relative closeness to an ideal solution. For applying TOPSIS, in the first, the topographic shape representing optimal recovery efficiency is defined based on a hydraulic model experiment, and then an appropriate surface slope is determined for the security of a self-purification capability with DEM (Digital Elevation Model). In the second phase, the candidate areas are extracted from an alluvial map through a morphology operation, because local alluvium with a lengthy and narrow shape could be satisfied with a primary condition for the optimal site. Thirdly, a shape file over all candidate areas was generated and criteria and their values were assigned according to hydrogeologic attributes. Finally, TOPSIS algorithm was applied to a shape file to place the order preference of candidate sites.

• Journal of Korean Institute of Industrial Engineers
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• v.5 no.2
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• pp.9-14
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• 1979

Inventories of finished products exist in each stage of the channel between production and consumption. An inventory has several functions, which make it possible to produce by economic lot size and to elevate services for consumer by shortening delivery time, etc$\cdots$. Finished products may be inventoried in delivery-center as well as at the plant where production takes place. So, finshed products must be dealt with as multistage inventory problem, because an inventory functions differently according to its place. The purpose of this study is to determine how much to carry in stock and what stage to carry Though there may be several channels between production and consumption, this study deals with only one main channel, that is, series of ncomponents and determines the optimal inventory policy by introducing the concept of selling probabilities.

• Journal of Power System Engineering
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• v.5 no.3
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• pp.64-72
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• 2001

This paper describes an optimal design technology in a segment type vertical guide bearing for vertical rotating machinery. Segment type vertical guide bearings have widely used for vertical rotating machinery, however bearing problems, such as excessive vibration and temperature rise, frequently take place in the actual machine. Such excessive vibration magnitude and/or abnormal bearing metal temperature rise result in serious damage and economic losses. Thus the segment type vertical guide bearing should be designed to get optimal characteristics in order to maintain stable operation without bearing failure due to abnormal vibration and/or abnormal bearing metal temperature. The preload ratio is the most important parameter in designing the segment type vertical guide bearing. Because adjustment of the bearing preload by changing the bearing clearance could easily control both the bearing stiffness and the cooling effect. In the paper, the influence of the preload effects on the bearing metal temperature and the bearing stiffness has been investigated both theoretically and experimentally in order to find out an optimum preload ratio. Results show that the segment type vertical guide bearing has an optimum preload ratio at which the bearing stiffness reaches a masimum value while the bearing metal temperature is minimized.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.801-809
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• 2010

Limitation of optical phase conjugation for implementation of wideband and long-haul WDM transmission system is symmetric distribution of optical power and local dispersion with respect to optical phase conjugator (OPC). This limitation forces OPC to place at midway of total transmission length. This paper shows that the limitation of optical phase conjugation is overcame by applying optimal net residual dispersion (NRD) into transmission links based in inline dispersion management (DM). Optimal NRD related with OPC position is decided by combination of precompensation and postcompensation. It is confirmed that optimal NRD depends on launch power of WDM channels and system performance criterion as well as OPC position. That is, in case of 1 dB eye opening penaty (EOP) as a performance criterion for WDM channels with 0 dBm launch power, it is confirmed that OPC is allowed to place at anywhere of 1000 km by applying best NRD related with exact OPC position into transmission links. And, it is confirmed that, under 3 dB EOP criterioin for WDM channels with 3 dBm launch power, OPC is allowed to place at 350~700 km by applying NRD between 100 ps/nm and 200 ps/nm into transmission links, though that NRD value is not best combination of precompensation and postcompensation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.148-154
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• 2012

For a successful checkpointing strategy, we should place checkpoints so as to optimize fault-tolerance capability of real-time systems. This paper presents a novel scheme of checkpoint placement for real-time systems with periodic multi-tasks. Under the influence of transient faults, multi-tasks are scheduled by the Rate Monotonic (RM) algorithm. The optimal checkpoint intervals are derived to maximize the probability of task completion. In particular, this paper is concerned about the general case that the deadline of a task is longer than the period. Compared with the special condition that the deadline is equal to or less than the period, this general case causes a more complicate test procedure for schedulability of the RM algorithm with respect to a given set of checkpoint re-execution vectors. The probability of task completion is also derived in a more complex form. A case study is given to show the applicability of the proposed scheme.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.5
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• pp.273-280
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• 2011

In this paper, we describe the structural reinforcement approach of the throwing-type firefighter assistance robot which can be thrown into a fire site to monitor inside the place and search trapped people while ensuring a firefighter's safety. The reinforcement design is focused on high strength with low weight for the robot. The in-depth structural analysis of the platform is carried out to track down the weakest part, especially with the 1.8m height of drop test. The analysis is verified by comparing with the 1.8m height of the drop test of the throwing-type firefighter assistance robot. The optimal approach for improving the strength of the weakest part aims at topological equivalent and equivalently stress distributed shape.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.296-299
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• 1987

The purpose of this paper is to increase the lamp efficacy by filling the optimal Nitrogen gas pressure in the outer enclosure of metal halide lamp. This study presents a new model of Langmuir in the outer enclosure of discharge lamp. In this paper, in the first place, the diameter of Langmuir sheath and the total gab loss were calculated. Secondly, the each gas loss was computed if the arbitrary gas pressure is filled, With the calculated data, flash over which affects the lamp efficacy, lamp life and color rendering was considered. In case of the established discharge lamp, the gab pressure has been filled by experience only roughly. The gas loss is converted into the radiation output. Therefore, the lamp efficacy is improved by reducing the gas loss.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.977-979
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• 1996

This paper presents an algorithm to control the undesirable sway of a suspended load in the crane system that has a trade-off between positioning the load and suppressing the sway of the load. The aim is to transport the load to a specified place with small sway angle as quickly as possible. Dynamic model is based on a simple pendulum driven by a velocity drive that is mostly used for actuating a trolley in industry. Proposed algorithm is composed of two parts : one is a off-line optimal trajectory generator, the other on-line tracking control. The former produces optimal trajectories minimizing energy under the speed constraint of velocity drive. The latter controls outputs to track the generated trajectories. Digital simulations and experiments are performed on a pilot crane to demonstrate the performance of the proposed control algorithm.

• Journal of information and communication convergence engineering
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• v.19 no.3
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• pp.161-165
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• 2021

Since the first commercialization of beacon-based services in 2011, various services have been provided to improve Bluetooth performance, and research has been conducted to accurately recognize user locations using beacons. The various measurement methods of indoor positioning systems (IPS) include methods using receiver signal strength indicator (RSSI) the strength of which varies greatly in accuracy depending on whether there are obstacles such as cement walls or doors. In this paper, we present a method to provide accurate positioning services even in the presence of obstacles in indoor spaces. To this end, we connect the HM-10 module supporting the beacon with Arduino Uno, to place beacons in three directions in real-world indoor space, and derive an optimal trilateration equation. Based on the derivation, we select the optimal expression for calculating the distance between the beacon and the moving station and use it to verify the coordinate determination for the moving station.