• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.549-556
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• 2009

This research analyzed the structural efficiency and application by improving the 100 mm width vertical joint to 150 mm and developing three connection methods to reduce the difficulty in assembling and handling PC walls. Moreover, nonlinear finite analysis was used for analyzing. From the analysis results, when double width connection was applied, the PC wall showed larger load capacity and ductility due to the steel bar sharing loads efficiently. Moreover, as the dimension of loops and the number of bars increased, the maximum load capacity increased as well. Also, among the double width connections, the largest capacity showed in the order of welding, ring and C type loop. However, in case of welding type loop connection, the ring type loop is more stable due to changes in different site conditions. Therefore, thorough quality control of welding is necessary.

• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.53-68
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• 2011

This paper presents the fundamental parameters for designing the NATM Composite Lining to be used in NATM tunnel construction. Firstly, the concept of NATM Composite Lining behaviour is introduced and reviewed in construction-performance. For the fundamental study, the optimal mix ratio tests and backfill material property tests to develop high-quality composite lining (PC panel lining) are fundamentally carried out. And the light-weight foamed mortar which is used for backfill material is developed. Full-scale loading tests to verify a performance of the NATM Composite Lining is also performed. From this research, it is clearly found that the NATM Composite Lining is very applicable method to considerably increase the stability and constructability of tunnel structure.

• Journal of the Korean Institute of Gas
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• v.8 no.4 s.25
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• pp.1-7
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• 2004

In this paper, the FE analysis has been presented for the leakage safety of the membrane LNG storage tank based on the thermal resistance effects between the insulation panel and prestressed concrete structure. The FEM calculated results show that the leakage safety of plywood and polyurethane materials does not guarantee any more due to a strength failure of the insulation structure. But the PC structure of outer tank may delay leaked LNG of 10 days even though the inner tank and insulation structure are simultaneously failed. This means that the membrane LNG storage tank may be safe because of the stiffness of the outer tank.

• Interaction and multiscale mechanics
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• v.2 no.1
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• pp.69-89
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• 2009

Reinforced and prestressed concrete (RC and PC) thin walls are crucial to the safety and serviceability of structures subjected to shear. The shear strengths of elements in walls depend strongly on the softening of concrete struts in the principal compression direction due to the principal tension in the perpendicular direction. The past three decades have seen a rapid development of knowledge in shear of reinforced concrete structures. Various rational models have been proposed that are based on the smeared-crack concept and can satisfy Navier's three principles of mechanics of materials (i.e., stress equilibrium, strain compatibility and constitutive laws). The Cyclic Softened Membrane Model (CSMM) is one such rational model developed at the University of Houston, which is being efficiently used to predict the behavior of RC/PC structures critical in shear. CSMM for RC has already been implemented into finite element framework of OpenSees (Fenves 2005) to come up with a finite element program called Simulation of Reinforced Concrete Structures (SRCS) (Zhong 2005, Mo et al. 2008). CSMM for PC is being currently implemented into SRCS to make the program applicable to reinforced as well as prestressed concrete. The generalized program is called Simulation of Concrete Structures (SCS). In this paper, the CSMM for RC/PC in material scale is first introduced. Basically, the constitutive relationships of the materials, including uniaxial constitutive relationship of concrete, uniaxial constitutive relationships of reinforcements embedded in concrete and constitutive relationship of concrete in shear, are determined by testing RC/PC full-scale panels in a Universal Panel Tester available at the University of Houston. The formulation in element scale is then derived, including equilibrium and compatibility equations, relationship between biaxial strains and uniaxial strains, material stiffness matrix and RC plane stress element. Finally the formulated results with RC/PC plane stress elements are implemented in structure scale into a finite element program based on the framework of OpenSees to predict the structural behavior of RC/PC thin-walled structures subjected to earthquake-type loading. The accuracy of the multiscale modeling technique is validated by comparing the simulated responses of RC shear walls subjected to reversed cyclic loading and shake table excitations with test data. The response of a post tensioned precast column under reversed cyclic loads has also been simulated to check the accuracy of SCS which is currently under development. This multiscale modeling technique greatly improves the simulation capability of RC thin-walled structures available to researchers and engineers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.25-32
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• 2023

In this study, a double wall system is introduced, which was invented to simplify the complicated manufacturing process of the existing precast concrete (PC) double wall systems and to remove defects such as laitance that may occur during the production of concrete panels. An experimental study was conducted to investigate the tensile resisting capacity of the steel tube which is embedded in the precast concrete panel to keep the spacing between PC panels and to prevent damage of the PC panels during transportation and casting concrete onsite. The experiment was planned to determine the detail of effective steel tube connection considering the steel plate treatment method according to the formation of the opening, the presence of embedded concrete, and the reinforcement welding for additional dowel action as key variables. As a result, the ultimate tensile strength increased by 20-30% compared to the control specimen (ST) except for the steel tube specimen (ST_CP) which has steel plates bent inward at the end part of the steel tube. Since the specimen (ST_CON) filled with concrete inside the control specimen has no additional process and cost for the steel tube connections compared to the control specimen during the production of the developed double wall system, it is determined to be the appropriate detail of steel tube connection.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.68-69
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• 2006

A new type of simulation training system for power system operation is presented in this paper It is based on transmission mimic board, double screen PC, mimic control panel, and real-time digital simulator, KEPS. The operating simulation includes the simulations of the control panel interface and the simulator. The mimic board displays transmission network summary information using a software view of the hardware based mimic board. The symbols, numbers and colors layout exactly match those of the KEPS draft case to provide operators a familiar and effective starting point. This paper describes the development of an innovative training system, utilizing the benefits of 3 dimension visualization s/w and communication-control s/w to create the appropriate operational environment and allow simulation of various power system operations without the restrictions of other training methods. Experiences gained in developing concepts and meeting considerable s/w challenges are outlined, and the potential of the simulator for future operations training discussed.

• Journal of Korea Multimedia Society
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• v.20 no.2
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• pp.271-278
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• 2017

This paper introduces a user-friendly PLC (programmable logic controller) monitoring and control system of heavy machinery using Android based smartphone. The proposed system will control diesel generator and many such like machine without a dedicated PC with respect to similar system and offers a new communication protocol for handling it. The smartphone controls the generator via Wi-Fi, through which it connects to the Raspberry pi which will be installed in the PLC panel to setup the communication between them. Furthermore, Raspberry pi connects to two devices, one is PLC which gives the status and current information of the machine and to ON/OFF the machine. This proposed system used RS485 as a key mediator for data exchanging between Raspberry PI(master) and PLC(slave). RS485 allows multiple devices (up to 32) to communicate at half duplex on single pair of wires and provides a long connectivity area (up to 1200 meters) as compared to another device. This proposed system specially focused on accurate data flow between smartphone and PLC panel.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.199.1-199.1
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• 2012

TRIO-CINEMA(TRiplet Ionospheric Observatory-Cubesat for Ion, Neutron, Electron & MAgnetic field)는 지구근접공간에서의 미세 자기장 변화 및 중성입자의 검출을 목적으로 경희대학교와 UC Berkeley가 공동 개발하는 초소형위성이다. 초소형위성은 내부 공간이 협소하여 효율적인 공간배치 및 위성체발사 시 진동에도 견딜 수 있도록 harness가 제작되어야 한다. CINEMA는 OBC, EPS, 배터리, 수신기, IIB(Instrument Interface Board), MAGIC(MAGnetometer Imperial College) board, HVPS(High Voltage Power Supply)로 구성된 avionics bus와 MAGIC, STEIN(Supra Thermal Electron, Ion, Neutral)의 payload, Solar panel, UHF와 S-band 안테나로 구성되어 있다. Solar panel에서 생산된 전력은 EPS를 통해 배터리에 저장되고 PC104를 통해 avionics stack의 각 board로 전력이 분배된다. IIB는 탑재체 파트와 연결되어 이를 제어하고 HVPS에서 STEIN에 공급되는 고전압은 특수 와이어를 통해 연결되며 UHF 안테나와 S-band 안테나는 RF 케이블로 수신기와 송신기가 연결되어 있다. 각각의 harness는 케이블타이와 lacing tape로 위성체와 고정되며 커넥터는 고정 지지대를 제작하여 나사로 체결하였다. CINEMA에 적용된 harness는 진동시험과 열진공시험을 통해 harness와 시스템의 안정성이 검증 되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.3
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• pp.241-246
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• 2004

We have designed LED display system using ARM7TDMI processor and implemented hangul input and output. This system is easily extensible because controller board and LED matrix board were designed one module. Possible Input Methods of LED display system are PC, PDA and remote controller's wired and wireless communication. We have ported QT/Embedded 2.3.7 with touch panel Input at embedded board of Linux OS 2.4.18 and PXA255 Processor based. QT Application which we coded is able to input displaying text using ethernet communication on embedded system. Many of indicating text data is able to be saved because only korean alphabet codes are stored for data which users want displaying.

• Human Ecology Research
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• v.56 no.6
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• pp.493-506
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• 2018

This study analyzes factors that determine the usage of digital information by senior consumers in the mobile environment. Senior consumers are alienated from digital information in South Korea; therefore, there have been increasing attempts to resolve this digital divide and reduce the digital information usage gap between young adults and senior consumers. The study used panel data from the National Information Society Agency (2017); there were 1,463 participants, aged 50-79 years. SPSS 19.0 was used to conduct the statistical analyses for frequency, factor analysis, Cronbach' ${\alpha}$ analysis, descriptive analysis and hierarchical multiple-regression analysis. The results are as follows. First, negative attitude toward information society negatively influenced the mobile digital information usage in diversity context. Second, average monthly income, degree of digital device usage motivation, positive attitude toward digital device usage, digital literacy of PC & Mobile, and family support positively influenced the mobile digital information usage in diversity context. Third, negative attitudes toward information society negatively influenced the mobile digital information usage in quality context. Forth, average monthly income, degree of digital device usage motivation, positive attitude toward digital device usage, digital literacy of PC & mobile, and family support positively influenced the mobile digital information usage in quality context. The study results can help further understand mobile usage behaviors among senior citizens and the implications on their quality of life in the digital information era.