• Journal of Institute of Control, Robotics and Systems
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• v.20 no.1
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• pp.87-93
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• 2014

Conventional two-wheeled balancing robots are limited in terms of turning speed because they lack the lateral motion to compensate for the centrifugal force needed to stop rollover. In order to improve lateral stability, this paper suggests a two-wheeled balancing mobile platform equipped with a tilting mechanism to generate roll motions. In terms of static force analysis, it is shown that the two-body sliding type tilting method is more suitable for small-size mobile robots than the single-body type. For the mathematical modeling, the tilting-balancing platform is assumed as a 3D inverted pendulum and the four-degrees-of-freedom equation of motion is derived. In the velocity/posture control loop, the desired tilting angle is naturally determined according to the changes of forward velocity and steering yaw rate. The efficiency of the developed tilting type balancing mobile platform is validated through experimental results.

• Journal of Welding and Joining
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• v.26 no.2
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• pp.50-54
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• 2008

The wearplate with Cr-C has been used in condition of severe abrasion. Recently, the demand of wearplate made by hardfacing with Cr-C has increased in the world, but it is lack of supply and expensive due to low productivity. CMAW (Compound Metal Arc Welding) is very useful process of several welding methods to make wearplate. In this paper, twin torch CMAW to use twin torch at the same time was developed to improve productivity and to ensure quality of wear plate. When the distance between two touches was smaller than 30mm, arc blow was occurred. However when the distance was larger than 35mm, there was no arc blow any more. If the oscillation path of each torch was overlapped together, the melt through at the overlapped zone was occurred due to concentrated heat input in substrate. On the other hand, the turning point of each torch was open more than 5mm, separated bead was generated. Therefore twin torch CMAW which has adequate conditions was able to make wearplate having flatter surface at the bead connection than single torch.

• Korean Institute of Interior Design Journal
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• no.38
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• pp.108-115
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• 2003

Between 1890-1914, the fundamental changes of the housing in United Sates of America were provoked to attempt the housing developments to adapt modern social system. The worthy of notice is that F L. Wright's Prairie House had been tested and built during the period as 'the first and second era' Despite the transition period in America, this represents that Wright's Prairie House series were developed. There are possibilities that some of the reformers assertion for Housing Development, on behalf of Arts & Crafts Movement, led to Wright's early house inner space design. For this reason, this study is to examine Ideologies that Wright has been accepted between the turning point of America's Arts & Crafts Movement and Hull House Circle. In terms of the ideologies acceptance, the study is also to examine how to be represented his inner space design characteristics. As the result, between'Simplification'housing development and the traditional housing In America, F L. Wright sublimated his own architectural aesthetic as accepting all functional elements to consider inevitability in this period, such as the association between economical and rational space, the plan to led on free plane, the spatial side and the stability of family life and the community, through the unification space having the consecutiveness.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.1
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• pp.62-68
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• 2011

Rapid turning and accelerated movement of a rotorcraft leads to the slosh and vibration effect of fuel in the fuel tank. Due to the slosh load, the internal component of a fuel tank can be broken and fuel tank skin can be damaged. This is directly related to human survivability. Military specification(MIL-DTL-27422D) requires the verification of the stability of aircraft fuel tank and internal component against slosh & vibration load through the qualification test. This report shows the establishment of slosh and vibration test facility and KUH fuel tank qualification test result.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.180-187
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• 2007

This paper presents a mathematical vehicle model that is designed to analyze the dynamic performance and to develop various safety control systems. Wheel slip controllers for ABS is also formulated to improve the vehicle response and to increase the safety on slippery road. Validation of the model and controller is performed by comparison with a commercial software package, CarSim. The result shows that performances of developed vehicle model are in good accordance with those of the CarSim on various driving conditions. Developed ABS controller is applied to the vehicle model and CarSim model, and it achieves good control performance. ABS controller improves lateral stability as well as longitudinal one when a vehicle is in turning maneuver on slippery road. A driver model is also designed to control steer angle of the vehicle model. It also shows good performance because the vehicle tracks the desired lane very well.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.720-723
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• 2005

Ship motion is a complex controlled process with several hydrodynamic parameters that vary in wide ranges with respect to ship load condition, speed and surrounding conditions (such as wind, current, tide, etc.). Therefore, to effectively control ships in a designed track is always an important task for ship masters. This paper presents an effective adaptive autopilot ships that ensure the optimal accuracy, economy and stability characteristics. The PID control methodology is modified and parameters of a PID controller is designed to satisfy conditions for an optimal objective function that comprised by heading error, resistance and drift during changing course, and loss of surge velocity or fuel consumption. Designing of the controller for course changing process is based on the Model Reference Adaptive System (MRAS) control theory, while as designing of the automatic course keeping process is based on the Self Tuning Regulator (STR) control theory. Simulation (using MATLAB software) in various disturbance conditions shows that in comparison with conventional PID autopilots, the designed autopilot has several notable advantages: higher course turning speed, lower swing of ship bow even in strong waves and winds, high accuracy of course keeping, shorter time of rudder actions smaller times of changing rudder direction.

• Journal of Ocean Engineering and Technology
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• v.31 no.2
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• pp.155-163
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• 2017

Submerged bodies moving underwater behave differently based on their type and assigned mission. This paper describes the dynamic characteristics, including the stability, turning ability, and operational ability, of submerged bodies in relation to design parameters such as the tail cone angle, shape of the control plate, and length of the parallel middle body. A submerged body operated in other countries is adopted as a reference for the dynamic characteristics, its principal dimensions and the shape of the bare hull and appendages are used for comparison. This paper suggests a few candidate hull forms based on changes in the typical design parameters. Finally, the dynamic characteristics for these candidate hull forms are defined.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.311-312
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• 2006

In this paper, steering systems for mobile robot with permanent magnet wheels are discussed. The mobile robot with permanent magnet wheels can have three different types of steering and driving configurations; two-wheels, three-wheels, four-wheels. By a Two-WD(Wheel Driving) system, driving and steering characteristics are controlled by ratio of each wheel speeds. Three-WD system is steered by a front wheel and driven by rear wheels. Four-WD system has better stability than two wheel system. Usually the permanent magnet wheel has nearly none slip. Thus turning radius of the mobile robot with three-WD and four-WD System will be increased and the steering and driving system will be complicated. To solve this problem, two magnet wheels with two dummy wheels are used in this study. fuming radius of the developed mobile robot is small and the structure of the robot is simple. It is possible to move forward, backward, to turn left and right, and to rotate freely with two-WD. This study proved that two-WD system is very suitable fur the mobile robot with permanent magnet wheels.

• Journal of Navigation and Port Research
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• v.44 no.3
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• pp.264-274
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• 2020

The Ro-Ro ferry ship capsized and sank to the bottom of the sea because of the rapid turning for several reasons, such as lack of stability due to the center of gravity rise from the extension and rebuilding of the stern cabin, excessive cargo loading, and shortage ballast, poor lashing, etc. The purpose of this study was to investigate and analyze the cause of the ship's rapid flooding, capsizing, and sinking accident according to rapid turning scientifically and accurately using the Fluid-Structure Interaction( FSI) analysis technique. Several tests were conducted for this cause investigation of the flooding and sinking accident correctly and objectively, such as the realization of the accurate ship posture tracks according to the accident time using several accident movies and photos, the validation of cargo moving track, and sea water inflow amount through the exterior openings and interior paths compared with the ship's posture according to the accident time using the floating simulation and hydrostatic characteristics program calculation, and the performance of a full-scale ship flooding·sinking simulation.

• Korean Journal of Culture and Social Issue
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• v.19 no.1
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• pp.19-44
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• 2013

The present study aimed at investigating how Korean housekeeper in midlife revaluate their lives. For this purpose, 14 housekeepers whose youngest child was at least older than high school students were interviewed in a semi-structured retrospective method. The interview was focused on relational, psychological, and economical aspects of the participants before and after marriage each. The interview usually continued one and a half to two hours. The phenomenological method describing personal meaning of experiences was referred to for data analyses by transforming retrospective life story of participants into key meaningful units. According to main retrospective contents of each stage of development, the participants' childhood and adolescence was characterized by familial circumstances, formation of personality and value, and career choice. Main themes of their early adulthood were spouse selection and marriage, marital adaptation, and family relationships. Their midlife focused on children, economic and emotional stability, family relationships, acceptance of their spouse and themselves, and health and religion. Life styles of the participants were analyzed in terms of turning events, meanings of current life, and cumulative effects of life events. These findings were discussed in terms of developmental pattern in relation to the established theory of development.