• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.385-390
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• 2005

LMTT (Linear Motor-based Transfer Techn-ology) is a horizontal transfer system for the yard automation, which has been proposed to take the place of AGV (Automated Guided Vehicle) in the maritime container terminal. The system is based on PLMSL (Permanent Magnetic Linear Synchronous Motor) that consists of stator modules on the rail and shuttle car. It is desirable to reduce the weight of LMTT in order to control the electronic devices with minimum energy. In this research, the DACE modeling, known as the one of Kriging interpolation, is introduced to obtain the surrogate approximation model of the structural responses. Then, the GRG(Generalized Reduced Gradient) method built in Excel is adopted to determine the optimum. The objective function is set up as weight. On the contrary, the design variables are considered as transverse, longitudinal and wheel beam's thicknesses, and the constraints are the maximum stresses generated by four loading conditions.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.82-86
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• 2002

The thermal characteristics of high-speed air spindle system with built-in motor are studied. Experiment and finite difference method analysis obtain temperature rise and temperature distribution of housing. For the analysis, air fluid film model is built and temperature rise and distribution in thermal steady state are computed for each rotational speed. Generally, it is said that the heat generation of air bearing is negligible. But the heat generation in air film by heat dissipation can not be negligible especially into high-speed region of the journal. In case that the heat generation of air spindle system is high, natural frequency of the spindle system becomes lower when the thermal state is in steady-state and it means the changes of air bearing stiffness due to the change of bearing clearance. It is shown that the temperature rise of air spindle system causes thermal expansion and induces the variation of bearing clearance. In consequence the stiffness of air bearing becomes smaller.

• Journal of the Korean Regional Science Association
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• v.11 no.1
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• pp.1-20
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• 1995

This paper studies the comparative advantage of competitive and specialized regional industries which are manufacturing, wholesale and retail trade, servies in the metropolitan area-Seoul, Inchun, Kyunggi-do of Korea, For the analysis of industries, the coefficient of specialization, the indices of competitiveness of labor and value-added, the growth rate are simultaneously examined under the criteria of the number of workers, value of shipment, value-added, This comperative synthetic analysis is different from the traditional approaches. This paper shows that the perfectly competitive advantage of specialized industries satisfying all of three criteria are 'other business related activities', 'recreational, cultural and sporting activities' in Seoul, 'machinery and outfits, n.e.c', 'retail trade, except of motor vehicles and motorcycles, repair of personal and household goods' in Inchun. We conclude that each should strategically develop the region-oriented specialized industry which has the comparative advantage. It is the reason why the concentration of industry in necessary for the leading of regional industry under the weaken local public finance. Moreover, such an industy should provide the increase of employment and income from the viewpoint of the activation of regional economy. The potential-specialized competitive industry requires the advanced structure of production under the criteria of value-added. For the development of the metropolitan area's economy, the highly advanced technology industry including computer and electronics should be induced through the loosening of metropolitan regulation. Research center(science park) supported by th private-public sector should be built for the increase of technology sector should be built for the increase of technology power of the small and medium enterprises, Also it is necessary that the small and medium enterprises strategically make the cooperative-large group in order to avoid the disadvantage from the size.

• Journal of Advanced Research in Ocean Engineering
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• v.1 no.2
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• pp.134-147
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• 2015

This study proposes a method to determine the effective angular velocity of each motor of a specific four-rows tracked vehicle (FRTV) in order to follow a given turning radius. The configuration of the four-rows tracked vehicle is introduced, and its dynamics analysis model is built using the DAFUL commercial software. The soil has been assumed to be hard ground, and the friction force between the ground and the tracked links is calculated using the Coulomb friction model. This paper uses a simulation to show that the error in the position increased with respect to the angle of the curvatures, so a method is proposed to compensate for the error in the motion of the motors. Various simulations are then carried out to verify the proposed formulation. The effects of the soil characteristics and the driving velocity will be further investigated in future studies.

• Journal of Power Electronics
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• v.9 no.3
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• pp.464-471
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• 2009

This paper introduces a new Motion-$SPM^{TM}$ (Smart Power Modules) module in Single In-line Package (SIP), which is a fully optimized intelligent integrated IGBT inverter module for up to 1kW low power motor drive applications. This module offers a sophisticated, integrated solution and tremendous design flexibility. It also takes advantage of pliability for the arrangement of heat-sink due to two types of lead forms. It comes to be realized by employing non-punch-through (NPT) IGBT with a fast recovery diode and highly integrated building block, which features built-in HVICs and a gate driver that offers more simplicity and compactness leading to reduced costs and high reliability of the entire system. This module also provides technical advantages such as the optimized cost effective thermal performances through IMS (Insulated Metal Substrate), the high latch immunity. This paper provides an overall description of the Motion-$SPM^{TM}$ in SIP as well as actual application issues such as electrical characteristics, thermal performance, circuit configurations and power ratings.

• International Journal of Advanced Culture Technology
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• v.8 no.3
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• pp.260-268
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• 2020

Currently, it is usually a 3D scanner processing method as a laser method. However, the laser method has a disadvantage of slow scanning speed and poor precision. Although optical scanners are used as a method to compensate for these shortcomings, optical scanners are closely related to the distance and precision of the object, and have the disadvantage of being expensive. In this paper, 3D scanner using variable focus lens-based structured light module with improved measurement precision was designed to be high performance, low price, and usable in industrial fields. To this end, designed a telecentric optical system based on a variable focus lens and connected to the telecentric mechanism of the step motor and lens to adjust the focus of the variable lens. Designed a connection structure with optimized scalability of hardware circuits that configures a stepper motor to form a system with a built-in processor. In addition, by applying an algorithm that can simultaneously acquire high-resolution texture image and depth information and apply image synthesis technology and GPU-based high-speed structured light processing technology, it is also stable for changes to external light. We will designed and implemented for further improving high measurement precision.

• Journal of Biosystems Engineering
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• v.19 no.2
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• pp.91-98
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• 1994

Planting, transplanting, and harvesting are important processes for the successful production of farm products in Korea because those require the high labor intensity during limitted period. Recently, many researches of using automatic control with a microcomputer are carried in the agricultural field, but are not much spread to the seeder development. Automatic sowing technology would be much attractive if there was a way to assure that each seed was count accurately in the seed metering device. Thus, an automatic seed metering device was designed and constructed to be controlled by microcomputer. This device could be improved in not only counting the number of seeds in but also sowing seeds between row spacings. Automatic seed metering device consisted of conveyor belt and temporary storage device. Performance of seed metering device depends on the apparatus including sensor, stepping motor and DC-solenoid. Research contents and results are summarized as follows. 1. The seed metering device involving seed hopper, sorter and temporary storage device was designed and constructed. 2. A seed counting system with six photo electric sensors, designed and built for this project, was adequate for tranferring and counting seeds accurately. 3. Operating algorithm for stepping motor and photo electric DC-solenoid was developed. The Seed metering device proved to be a smooth and accurate operating device using the algorithm. 4. The performance of second prototype metering device was examined with five kinds of seeds ; mung beans, red beans, white beans, black beans and corn to transfer and count the seeds. The error ratio of seed metering was less than 3.5%.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.240-247
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• 2008

Recently, railway corporations have built maintenance information systems and collected failure and maintenance data. For example Seoul Metropolitan Rapid Transit Corporation (SMRT) built the Electric Motor Unit-Information System (EMU-IS) which is the first maintenance information system in Korea. It has been operated from August, 2000. This paper deals with a case study on determining maintenance interval through reliability analysis using EMU-IS fault data. Door system is considered for the case study in which reliability is evaluated for operating time and distance and the overhaul interval is determined.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.104-110
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• 2012

The spindle with a built-in motor can be used to simplify the structure of machine tool system, while the rotor has unbalance mass inevitably. A high-speed spindle can be very sensitive to rotating mass unbalance which has harmful effect on many machine tools. Therefore, the balancing procedure to reduce vibration in rotating system is certainly needed for all high-speed spindles. So, it was performed with a spindle-bearing system for CNC automatic lathe by using numerical procedure. The spindle is supported by the angular contact ball bearings and the motor rotor is fixed at the middle of spindle. The spindle-bearing system has been investigated using combined methodologies of finite elements and transfer matrices. The balancing was performed through influence coefficient method and the comparison was made by whirl responses between before balancing and after balancing. As a result, balancing of simple spindle model reduced whirl orbit magnitude in case of a completely assembled spindle model.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.1
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• pp.19-26
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• 2016

In this study, a bidirectional DC-DC converter for idle stop and go (ISG) is developed to reduce fuel consumption. A three-phase non-isolated half-bridge converter is selected through a design method by considering efficiency and volume. According to the state of charge of the batteries at both the low-voltage and high-voltage sides, buck mode, which charges a low-voltage battery from the generated motor energy, and boost mode, which provides power to the motor from the low- and high-voltage battery sides, are required in the ISG system. Hence, an autonomous and seamless bidirectional control method using a variable current limiter is proposed for mode change. A 1.8 kW engineering sample of the proposed converter has been built and tested to verify the validity of the proposed concept. The maximum efficiencies, including gate driver and control circuit losses, are 96.4% in charging mode and 96.1% in discharging mode.