• Journal of Practical Engineering Education
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• v.8 no.1
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• pp.23-29
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• 2016

Our society is endemic in safety insensitivity, yet we have been concerned for safety education and disaster drill since the Sewol Ferry accident. However, the practical training costs very high, and it has its limit to increase reality. Recently, industry fields put emphasis on virtual reality (VR) as alternatives, so various contents are invented by using advantages of VR. The paper explores crucial application in 3-dimensional simulation for fire drill, suggests novel design, and contemplates about educative result through designing process. In order to construct and materialize the suggested system, practical 3D spatial information model and various disaster-drill scenarios are necessary. Also, to apply game elements for augmentation in users' utility, educations based on computer science and visual art are inevitable, which requires skills in programing and modeling respectively. Thus, this study investigates educational effect of convergence field through the suggested system designing process.

• The Journal of Engineering Geology
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• v.1 no.1
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• pp.121-136
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• 1991

The focal mechanism of the Hongsung Earthquake (1978. Oct. 7, M$_L$=5.0, Latitude 36.62N, Longitude 1 26.67E) was evaulated using the polarity distribution of the P-Waveforms. Through the non-linear computer process, the compatibility of polarity distributions of the 9 P-Waveforms observed at teleseismic distances from the Hongsung Earthquake epicenter was investigated to those of the focal mechanism determined from the varying strike, dip and rake angles. The resultant values for the strike and dip angle of the principal fault plane, which apparently matches very well the sunface lineament of the Hongsung region, are determined to be about 247 degree and 78 degree with uncertainties, respectively. However, the rake angle of the focal mechanism has wide range of 40 degree to 160 degree, which is mainly due to the poor coverage of the azimuthal angle of the observed seismic stations. Due to the consistency of principal stress axes, the resultant focal mechanism could support the current stress regime of that region, which may be caused by subduction of the Pacific Plate under the Eurasia Plate along the Japan Trench. It also provides information of seismic source characteristics of the part of the Korean Peninsula for aseismic design criteria such as Site Specific Response Spectrum and Strong Ground Motion Time History for the nuclear power plants and related nuclear waste disposal facility sites.

• Clinics in Shoulder and Elbow
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• v.20 no.3
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• pp.147-152
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• 2017

Background: To evaluate the clinical and functional outcomes of arthroscopic-assisted reduction and percutaneous screw fixation for glenoid fractures with scapular extension, and investigate the radiologic and clinical benefits from the results. Methods: We evaluated patients treated with arthroscopic-assisted reduction and percutaneous screw fixation for glenoid fractures with scapular extension from November 2008 to September 2015. Fractures with displacement exceeding one-fourth of the anterior-articular surface or more than one-third of the posterior-articular surface in radiographic images were treated by surgery. Clinical assessment was conducted based on range of motion, Rowe score, and Constant score of injured arm and uninjured arm at last follow-up. Results: Fifteen patients with Ideberg classification grade III, IV, and V glenoid fracture who underwent arthroscopic-assisted reduction using percutaneous screw fixation were retrospectively enrolled. There were no differences in clinical outcomes at final follow-up compared to uninjured arm. Bone union was seen in all cases within five months, and the average time to bone union was 15.2 weeks. Ankylosis in one case was observed as a postoperative complication, but the symptoms improved in response to physical therapy for six months. There was no failure of fixation and neurovascular complication. Conclusions: We identified acceptable results upon radiological and clinical assessment for the arthroscopic-assisted reduction and percutaneous fixation. For this reason, we believe the method is favorable for the treatment of Ideberg type III, IV, and V glenoid fractures. Restoration of the articular surface is considered to be more important than reduction of fractures reduction of the scapula body.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.6
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• pp.1147-1152
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• 2006

This paper proposed modelling and design method in suspension system design to analyze sky hook damper system by adopting active robust control theory. Recent in the field of suspension system design it is general to adopt active control scheme for stiffness and damping, and connection with other vehicle stability control equipment is also intricate, it is required for control system scheme to design more robust, higher response and precision control equipment. It is known that sky hook suspension system is better than passive spring-damper system in designing suspension equipment. We analyze location of sensor and actuator in sky hook system and its motion equation, then design robust control system. Numerical example is shown for validity of robust control system design in active sky hook suspension system.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.4
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• pp.226-230
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• 2007

In the conventional desktop PC environment, keyboard and mouse are used to process the user input and monitor displays the visual information as an output device. In order to manipulate the digital information, we move the virtual cursor to select the desired graphical icon on the monitor The cursor represents the relative motion of the physical mouse on the desk. This desktop metaphor does not provide intuitive interface through human sensation. In this paper, we introduce a novel tangible interface which allows the user to interact with computers using a physical tool called "Smartpuck". SmartPuck system bridges the gap between analog perception and response in human being and digital information on the computer. The system consists of table display based on a PDP, SmartPuck equipped with rotational part and button for the user's intuitive and tactile input, and a sensing system to track the position of SmartPuck. Finally, we will show examples working with the system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.261-261
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• 2007

Wearable and ubiquitous micro systems will be greatly growing and their related devices should be self-powered in order to avoid the replacement of finite power sources, for example, by scavenging energy from the environment. With ever reducing power requirements of both analog and digital circuits, power scavenging approaches are becoming increasingly realistic. One approach is to drive an electromechanical converter from ambient motion or vibration. Vibration-driven generators based on electromagnetic, electrostatic and piezoelectric technologies have been demonstrated. Among various generator types proposed so far, piezoelectric generator possesses considerable potential in micro system. To overcome low mechanical-to- electric energy conversion, the piezoelectric device should activate in resonance mode in response to external vibration. Normally, the external vibration excretes at low frequency ranging 0.1 to 200 Hz, whereas the resonant frequencies of the devices are fixed as constant. Therefore, keeping their resonant mode in varying external vibration can be one of important points in enhancing the conversion efficiency. We investigated the possibility of use of multi-bender type piezoelectric devices. To match the external vibration frequency with the device resonant frequency, the various devices with different resonant frequency were chosen. Under an external vibration acceleration of 0.1G at 120 Hz, the device exhibited a peak-to-peak voltage of 2.8 V and a power of 0.5 mw in resonance mode.

• Korean Journal of Applied Biomechanics
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• v.23 no.3
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• pp.209-218
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• 2013

This study was to perform the kinetic analysis of forward $1\frac{1}{2}$ somersault on the platform diving. Six men's diving players of the Korea national reserve athletes participated in this study. The variables were analyzed response time, velocity, center of mass (COM), angle, center of pressure (COP) and ground reaction force (GRF) of motion. For measure and analysis of this study, used to synchronized to 4 camcorder and 1 force plate, used to the Kwon3D XP (Ver. 4.0, Visol, Korea) and Kwon GRF (Ver. 2.0, Visol, Korea) for analyzed of variables. The results were as follows; Time factor were observed in maximum knee flexion depending on the extent of use at phase 1 of take-off to execute the somersault. This enabled the subject to secure the highest possible body position in space at the moment of jumping to execute the somersault and prepare for the entry into the water with more ease. Regarding the displacement of COM, all subjects showed rightward movement in the lateral displacement during technical execution. Changes in forward and downward movements were observed in the horizontal and vertical displacements, respectively. In terms of angular shift, the shoulder joint angle tended to decrease on average, and the elbow joints showed gradually increasing angles. This finding can be explained by the shift of the coordinate points of body segments around the rotational axis in order to execute the half-bending movement that can be implemented by pulling the lower limb segments toward the trunk using the upper limb segments. The hip joint angles gradually decreased; this accelerated the rotational movement by narrowing the distance to the trunk. Movement-specific shifts in the COP occurred in the front of and vertical directions. Regarding the changes in GRF, which is influenced by the strong compressive load exerted by the supporting feet, efficient aerial movements were executed through a vertical jump, with no energy lost to the lateral GRF.

• Journal of Ocean Engineering and Technology
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• v.27 no.5
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• pp.63-69
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• 2013

The mooring lines of a floating type offshore plant are known to show wide banded and bimodal responses. These phenomena come from a combination of low and high frequency random load components, which are derived from the drift-restoring motion characteristic and wind- sea, respectively. In this study, fatigue models were applied to predict the fatigue damage of mooring lines under those loads, and the result were compared. For this purpose, seven different fatigue damage prediction models were reviewed, including mathematical formula. A FPSO (floating, production, storage, and offloading) with a $4{\times}4$ spread catenary mooring system was selected as a numerical model, which was already installed at an offshore area of West Africa. Four load cases with different combinations of wave and wind spectra were considered, and the fatigue damage to each mooring line was estimated. The rain flow fatigue damage for the time process of the mooring tension response was compared with the results estimated by all the fatigue damage prediction models. The results showed that both Benasciutti-Tovo and JB models could most accurately predict wide banded bimodal fatigue damage to a mooring system.

• Earthquakes and Structures
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• v.8 no.1
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• pp.275-304
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• 2015

The objective of this paper is to investigate the validity of transmitting boundaries in dynamic analysis of soil-structure interaction problems. As a case study, the proposed Baghdad metro line is considered. The information about the dimensions and the material properties of the concrete tunnel and surrounding soil were obtained from a previous study. A parametric study is carried out to investigate the effect of several parameters including the peak value of the horizontal component of earthquake displacement records and the frequency of the dynamic load. The computer program (Mod-MIXDYN) is used for the analysis. The numerical results are analyzed for three conditions; finite boundaries (traditional boundaries), infinite boundaries modelled by infinite elements (5-node mapped infinite element) presented by Selvadurai and Karpurapu, 1988), and infinite boundaries modelled by dashpot elements (viscous boundaries). It was found that the transmitting boundary absorbs most of the incident energy. The distinct reflections observed for the "fixed boundaries" disappear by using "transmitted boundaries". This is true for both cases of using viscous boundaries or mapped infinite elements. The type and location of the dynamic load represent two controlling factors in deciding the importance of using infinite boundaries. It was found that the results present significant differences when earthquake is applied as a base motion or a pressure load is applied at the surface ground. The peak value of the vertical displacement at nodes A, B, E and F (located at the tunnel's crown and side walls, and at the surface above the tunnel and at the surface 6.5 m away from tunnel's centre respectively) increases with the frequency of the surface pressure load for both cases 1 and 2 (traditional boundaries and mapped infinite elements respectively) while it decreases for case 3 (viscous boundaries). The modular ratio Ec/Es (modulus of elasticity of the concrete lining to that of the surrounding soil) has a considerable effect on the peak value of the horizontal displacement at node B (on the side wall of the tunnel lining) increase about (17.5) times, for the three cases (1, 2, and 3).

• Journal of the Society of Naval Architects of Korea
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• v.54 no.4
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• pp.329-334
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• 2017

As the motion response of heave for floating bodies on the water surface is relatively large near the natural frequency, it is necessary to predict its value accurately from the stage of initial design. Bodies accelerating in fluid experience force acted upon by the fluid, and this force is quantified by using the concept of added mass. For predicting the natural frequency of heave we need to know the added mass, which is given as a function of frequency, and hence the natural frequency can be obtained through only by iteration process, as was pointed out by Lee (2008). His method was applied to circular cylinders, and two dimensional cylinders of Lewis form by making use of the Ursell-Tasai method in the previous works, Lee and Lee (2013), Kim and Lee (2013), and Song and Lee (2015). In this work, a similar algorithm employing the concept of strip method is adopted for predicting the heave natural frequency of KCS(KRISO Container Ship), and the obtained computational result was compared with other existing experimental data, and the agreement seems reasonable. Furthermore, through the error analysis, it is shown that why the frequency corresponding to the local minimum of the added mass and the natural frequency are very close. And it seems probable that we can predict the heave natural frequency if we know only the local minimum of added mass and the corresponding frequency under a condition, which holds for ship-like bodies in general.