• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.10
• /
• pp.7138-7145
• /
• 2015

In this study, experiments were conducted to investigate the correspondence between the output voltage of the photoelectric sensor and the frost height under heating and defrosting capacity test condition (dry bulb temperature $2^{\circ}C$, wet bulb temperature $1^{\circ}C$) described at KS C 9306, where a real heat exchanger was used as a test rig instead of a large-scale model. A digital microscope and a photoelectric sensor unit consisting of an emitter and a transistor (receiver) were installed in the front of it. A linear correlation is proposed to predict the frost height based on 150 experimental data, approximately 54% of the measured data are consistent with the predicted frost heights within a relative deviation of ${\pm}10%$, it yields good agreement with 90% of the measured data when the frost height larger than 0.3mm with in a relative deviation of ${\pm}10%$. Compared with Xiao's correlation, the slope namely, the change of frost height in accordance with the change of output voltage is consistent within the error of 2.3%. But vertical intercept shows big difference with Xiao's correlation, because it was developed with a large scale model instead of a real heat exchanger.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.3
• /
• pp.1764-1769
• /
• 2014

Numerical investigations have been conducted on the junction that connect the multi-tubular section and the single shell section in order to evaluate applicability of hybrid sections in wind turbine towers instead of conventional single shell towers. Major characteristics in structural details include extension of multi-tubular member into shell end section, installation of wing stiffeners, and different layout of floor beams. Elastic and nonlinear incremental analyses were conducted to examine stress concentration patterns and ultimate behaviors, respectively. Based on evaluation of structural performance due to vertical and horizontal forces, it has been confirmed that installation of floor beams and wing stiffeners sensitively affect ultimate strength of global wind tower.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.11
• /
• pp.5323-5329
• /
• 2013

Many companies have tried to develop the horizontally vibrating linear motor, for sliming the smart phone. Mathematical modeling and analysis is one of method to simulate the dynamic performance of the horizonatally vibrating linear motor. However, the horizontally vibrating linear motor vibrates in twisting mode because there are two kinds of force acting on the vibrating part. One is are the horizontal force by Lorentz force. The other is the vertical force by attraction force between magnet of vibrating part and bracket and the gravity force of vibrating part. However, those are very difficult to be included in mathematical modeling which generate the simulation errors. In this paper, we perform MFBD (multi flexible body dynamics) simulation using commercial dynamic analysis program "DAFUL". In our new model, the force effects those are neglected in mathematical model, are included. For the verification, the simulation results are compared with the experiment results with manufactured prototype.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.8
• /
• pp.5372-5383
• /
• 2015

The purpose of the present study was to figure out the effects of the result variables of hospital employees' conflicts on organizational effectiveness variables such as job satisfaction and organizational commitment. The present study was conducted with 305 subjects. The correlations among conflict, job satisfaction, and organizational commitment levels by conflict factor and by conflict type were analyzed using correlation analyses and multiple regression analyses were conducted to examine the effects of intra-organizational conflicts on conflict results while general and job related characteristics variable were controlled. According to the results of analyses, conflicts due to job satisfaction factors such as communication, leadership, and personality had significant negative effects on overall, intrinsic, and extrinsic job satisfaction levels and organizational commitment factors such as interdependence, leadership, and personality were significant conflict variables. By type, horizontal conflicts affected job satisfaction while vertical conflicts affected organizational commitment. When intra-organizational conflict levels were higher, job satisfaction and organizational commitment levels were lower and when job satisfaction levels were higher, organizational commitment levels were also higher

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.12
• /
• pp.5450-5456
• /
• 2011

In order to build a ship, painting on ship cargo tank is one of the most dangerous parts as it involves working in high altitudes and a closed ship cargo tank. Therefore, researchers have been developing devices that will enable mobile robots to operate on vertical walls. The wall-climbing robots have been widely used to attach on the wall such as suction types. These types can be utilized regardless of the wall material. However, it is required to adhere and control the suction cups. To moderate this drawbacks, this paper proposes an automatic painting robot that uses a permanent magnet mobile robot. Using the magnetic characteristics, this robot can move on the boat vertically and horizontally even while hanging on the ceiling of the ship cargo tank. Also, we made a prototype to test adhesive force of the permanent magnet wheel and mobile robot as well as the towing capacity and auto-piloting ability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.2
• /
• pp.944-951
• /
• 2011

This paper reports results of a joint experimental and numerical investigation of the causes of near-transducer errors due to the combined effect of acoustic and ADCP-induced flow disturbance near the ADCP transducer. The laboratory study focused on an isolated ADCP (deployment without boat). Measurements of the flow disturbance produced by the ADCP in vertical and horizontal planes were obtained acquiring measurements with an Acoustic Doppler Velocimeter (ADV). Concurrent measurements with ADCP and ADV were made to infer additional near-transducer effects in the ADCP measurements. The numerical investigation was designed to extend the inquiry on the near-transducer potential errors when the ADCP is deployed from a boat. Large Eddy Simulation (LES) was conducted to obtain the extent and magnitude of the disturbances induced by the drag acting on a boat-mounted ADCP and by the blockage effect of the instrument and boat. It is found the velocities measured by the ADCP are biased low and differ substantially from the undisturbed channel flow solution within a limited layer beneath the instrument.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.8
• /
• pp.344-349
• /
• 2017

Wall-climbing robots have been developed for various purposes, such as cleaning skyscraper windows, maintaining large structures, and welding vessels. Conventional wall-climbing robots use movement systems based on wheels or legs. However, wheeled robots suffer from slipping effects, while legged systems require many actuators and control systems for the complex linkage structure, which also increases the weight of the robot. To overcome these disadvantages, we propose a new wall-climbing robot that walks based on gorilla locomotion. The proposed robot consists of a DC drive motor, a vacuum pump for adsorption, and a micro controller for controlling the system. The performance of the robot was experimentally verified on vertical and horizontal flat surfaces. The robot could be used for various functions in industrial sites or disaster areas.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.9
• /
• pp.6385-6390
• /
• 2015

With bending moment, torsional moment due to geometric properties as "Initial curvature" acts in horizontally curved I-girder. These behavior causes the secondary effect of bending in minor-axis because of interaction between bending and torsion. The bending and torsion interaction cause a loss of load bearing capacity by induced the early inelastic or plasticity condition in curved girder. Also eccentric load by movements of traffic can increase torsion. However, Equation of interaction between bending and torsion for straight girder, not deal with characteristics of curved girder behavior in previous studies, can be overestimated for ultimate strength in horizontally curved I-girder acting vertical force. Therefore, using more rational, obvious suggestion is required when design curved girder. In this study, we identified the bending-torsional moment interaction for the horizontally curved I-girder of the eccentric load acting by FEM analysis.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.5
• /
• pp.3014-3021
• /
• 2015

Shell-tube heat exchanger is widely applied in industrial field by easily manufacturing as to various size and flow patterns. In this study, by changing baffle's cut direction, tilt angle and rotational angle as well as by using SST (Shear Stress Transport) $k-{\omega}$ turbulence model in ANSYS FLUENT v.14, the heat transfer rate and pressure drop characteristics of inner shell will be analyzed to improve heat transfer ability. As a result of analysis, heat transfer performance according to cut direction of baffle has been improved with vertical model B and angle $45^{\circ}$ model C than horizontal model A. In addition, the tilt $10^{\circ}$ of the baffle and rotational angle $0^{\circ}-90^{\circ}-180^{\circ}-270^{\circ}$ of model D showed better result in heat transfer rate and pressure drop.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.3
• /
• pp.1489-1494
• /
• 2013

Tsunami happens rarely enough to allow a false sense of security, but when they do occur, there may be just minutes or hours for people to reach a safe location. Natural disasters like tsunami are inevitable and it is almost impossible to fully recoup damages caused by the disasters. However, it is possible to minimize the potential risk by developing early warning strategies. GIS modelling with its geoprocessing and analysis capability can play a crucial role in efficient mitigation and management of disaster. This study aims at developing integrated spatial information system processing model supporting tsunami evacuation action planning using geo-information technology such as GIS. The integration process classified into four phases. And in each phase, required input data and GIS processes are decided. The main effort in minimizing casualties in tsunami disaster is to evacuate people from the hazard area before tsunami strikes by means of either horizontal or vertical evacuation. The study provides essential spatial information for local decision making related with people's evacuation in tsunami-prone areas based on a modeling approach transferable to other coastal areas.