• Journal of the Korean Geotechnical Society
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• v.35 no.12
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• pp.135-145
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• 2019

The slope collapse can be classified into internal and external factors. Internal factors are engineering factors inherent in the formation of slopes such as soil depth, slope angle, shear strength of soil, and external factors are external loading such as earthquakes. The external factor for earthquake can be expressed by various values such as peak ground acceleration (PGA), peak ground velocity (PGV), Arias coefficient (I), natural period (T_p), and spectral acceleration (S_aT=1.0). Specially, PGA is the most typical value that defines the magnitude of the ground motion of an earthquake. However, it is not enough to consider the displacement in the slope which depends on the duration of the earthquake even if the vibration has the same peak ground acceleration. In this study, numerical analysis of two-dimensional plane strain conditions was performed on engineered block, and slope responses due to seismic motion of scaling PGA to 0.2 g various event scenarios was analyzed. As a result, the response of slope is different depending on the presence or absence of sliding block; it is shown that slope response depend on the seismic wave triggering sliding block than the input motion factors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1694-1704
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• 2015

In this paper, a robust trajectory tracking control method of a wheeled mobile robot is newly proposed combining the PDC and the ISMC. The PDC is a relatively simple and easy control method for nonlinear system compared to the other non-linear control methods. And the ISMC can have robust and stable control characteristics against model uncertainties and disturbances from the initial time by placing the states on the sliding plane with desired nominal dynamics. Therefore, the proposed PDC+ISMC trajectory tracking control method shows robust trajectory tracking performance in spite of external disturbance. The tracking performance of the proposed method is verified through simulations. Even though the disturbance increases, the proposed method keeps the performance of the PDC method when there is no disturbance. However, the PDC trajectory tracking control method has increasing tracking error unlike the proposed method when the disturbance increases.

• Korean Institute of Interior Design Journal
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• v.21 no.1
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• pp.148-158
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• 2012

The objective of this study is to find a possible application of small space utilization of GangSo Housing, so called compact-but-effective housing, through analyzing that of Japanese small housing. We analyze openness of view and flexibility of spaces divided by the physical and architectural aspects as first component and the psychological and interior space aspects as second component. The results showed that Japanese small houses have various unit plan compared to uniformity of Korean houses. Openness of view in Japanese small housing is accomplished by letting in light from the outside using position and shape of the window, looking more spacious using courtyard, void spaces, or sliding door hanging from the ceiling, and creating deception of view using floor-wall plan and appropriate materials. Flexibility of spaces is achieved by combination of first and second components, multipurpose of space and furniture, and variety of storage methods. It is necessary to improve spatial efficiency with consideration of volume-metric planing rather than flat-plane and develop various unit plans to meet residents' needs and demands on compact-but-effective houses.

• Journal of the Korean housing association
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• v.27 no.1
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• pp.13-20
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• 2016

The paper takes the rural housings of the Chaoxian nationality of Ham-kyeongdo in the three provinces in Northeast China as research object, to discuss the spatial form andthe characteristic of the change in the housing. The research result shows that the dwellings' plane forms in the Tumen River, the coast of Yalu River and the Sino Russian border are mainly traditional "Jeong-ji central type (J)", while in Heilongjiang are mainly "Jeong-ji and corridor central type (J-C)". In the evolution of living space and behavior patterns, there appears sliding door and partition between Jeongjibang and kitchen in the former, and Badang space in the front of the Kang and the behavior pattern remains its original seat-type lifestyle mainly. While there forms Dikang space and living space in the process of different cultures blend and modernization in the later and appears some upright-type behavior patterns. There is distinct characteristic in regional changes in both.

• Smart Structures and Systems
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• v.7 no.2
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• pp.103-116
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• 2011

This paper is concerned with the trajectory tracking and vibration suppression of a single-link flexible arm by using piezoelectric materials. The dynamics of a single flexible arm with PZT patches as sensor and actuator is derived using extended Hamilton's principle. Resulting equations show that the coupled beam dynamics including beam vibration and its rigid in-plane rotation takes place in two different time scales. By using singular perturbation theory, the system dynamics is divided into two subsystems. Then, a composite control scheme is elaborated that makes the orientation of the arm track a desired trajectory while suppressing its vibration. The proposed controller has two parts: one is a tracking controller designed for the slow (rigid) subsystem, and the other one is a stabilizing controller for the fast (flexible) subsystem. The outputs considered for the system are angular position of the hub and voltage of the sensor mounted on the structure. To avoid requiring further measurements of beam vibration and also angular velocity of the hub for the fast and slow control laws, respectively, two sliding mode observers for estimating the unknown states are also designed.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.10
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• pp.186-194
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• 1996

The SliM (sliding memory plane) array processor has been proposed to alleviate disadvantages of existing mesh-connected SIMD(single instruction stream- multiple data streams) array processors, such as the inter-PE(processing element) communication overhead, the data I/O overhead and complicated interconnections. This paper presents the deisgn and implementation of SliM image processor ASIC (application specific integrated circuit) chip consisting of mesh connected 5 X 5 PE. The PE architecture implemented here is quite different from the originally proposed PE. We have performed the front-end design, such as VHDL (VHSIC hardware description language)modeling, logic synthesis and simulation, and have doen the back-end design procedure. The SliM ASIC chip used the VTI 0.8$\mu$m standard cell library (v8r4.4) has 55,255 gates and twenty-five 128 X 9 bit SRAM modules. The chip has the 326.71 X 313.24mil$^{2}$ die size and is packed using the 144 pin MQFP. The chip operates perfectly at 25 MHz and gives 625 MIPS. For performance evaluation, we developed parallel algorithms and the performance results showed improvement compared with existing image processors.

• The Journal of Advanced Prosthodontics
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• v.5 no.3
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• pp.333-340
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• 2013

PURPOSE. This study was accomplished to assess the biomechanical state of different retaining methods of bar implant-overdenture. MATERIALS AND METHODS. Two 3D finite element models were designed. The first model included implant overdenture retained by Hader-clip attachment, while the second model included two extracoronal resilient attachment (ERA) studs added distally to Hader splint bar. A non-linear frictional contact type was assumed between overdentures and mucosa to represent sliding and rotational movements among different attachment components. A 200 N was applied at the molar region unilaterally and perpendicular to the occlusal plane. Additionally, the mandible was restrained at their ramus ends. The maximum equivalent stress and strain (von Mises) were recorded and analyzed at the bone-implant interface level. RESULTS. The values of von Mises stress and strain of the first model at bone-implant interface were higher than their counterparts of the second model. Stress concentration and high value of strain were recognized surrounding implant of the unloaded side in both models. CONCLUSION. There were different patterns of stress-strain distribution at bone-implant interface between the studied attachment designs. Hader bar-clip attachment showed better biomechanical behavior than adding ERA studs distal to hader bar.

• Tunnel and Underground Space
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• v.5 no.2
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• pp.104-113
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• 1995

Shear strength of the discontinuity on which the pre-failure of rock slope was occurred during surface excavation was measured through the direct shear test using core samples obtained in-situ. Internal friction angle was increased as the roughness of discontinuity surface(JRC) was increased. Results of the tilt test using core samples of higher JRC also showed very similar trend as those of the direct shear test. When the samples replicated from natural cores were used int he tilt test, results of friction angles showed almost perfect continuation of the residual friction angles from the direct shear test. However, when the gouge material existed in the discontinuity the internal friction angle strongly depended upon the rate of filling thickness to the height of asperity irrespective of the JRC. Based on the results of both direct shear test and tilt test internal friction angle and cohesion of discontinuity, which reflect the in-situ conditions fo pre-sliding failure and also can be used for the optimum design of support system, were assessed. Two kinds of support measures which were expected to increase the stability of rock slope were considered; lowering of slope face angle and installation of rock cable. But, it was found that the first method might lead to more unstable conditions of rock slope when the cohesion of discontinuity plane was negligibly low and in that case the support systems of any kind which could exert actual resisting force were needed to ensure the permanent stability of rock slope.

• The Journal of Engineering Geology
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• v.11 no.3
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• pp.295-301
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• 2001

Geological and geophysical surveys were performed to examined the cause of the rock-mass slide occurred at the opening site of the Wanglim tunnel of the Seoul-Pusan High Speed Railway. The results of geophygical survey and geometrical analysis for the geological structures indicate that the rock-mass slide was triggered by the heavy rainfall which increases the groundwater level and results in high pore pressure in the N60$^{\circ}$ E-trending major fractured zone of the slope, and that the foliation dipping toward the vertical open face of the slope acted as a main sliding plane during movement.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.660-670
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• 2009

Neighboring construction becomes mainstream of Ground excavation in downtown area. This causes the displacement, deformation, stress condition, etc of the ground surroundings. Therefore Neighboring construction have an effect on Neighboring structure. All these years a lot of Neighboring construction carried out, and the accumulation of technology also get accomplished. But earth retaining structure collapse happens yet. Types of earth retaining structure collapse are 12. 1. Failure of anchor or strut system, 2. Insufficiency of penetration, 3. H-pile Failure on excessive bending moment, 4. Slope sliding failure, 5. Excessive settlement of the back, 6. Deflection of H-pile, 7. Joint failure of coupled H-pile, 8. Rock failure when H-pile penetration is rock mass, 9. Plane arrangement of support systems are mechanically weak, 10. Boiling, 11. Heaving, 12. Over excavation. But field collapses are difficult for classification according to the type, because collapse process are complex with various types. When we consider the 12 collapse field, insufficient recognition of ground condition is 4 case. Thorough construction management prevents from fault construction. For limitations of soil survey, It is difficult to estimate ground condition exactly. Therefore, it should estimate the safety of earth retaining system, plan for necessary reinforcement, according to measurement and observation continuously.