• Journal of The Korean Association of Information Education
• /
• v.23 no.5
• /
• pp.461-467
• /
• 2019

As the convergence solutions become more common, the use of Arduino and Raspberry Pi boards has been increasing. These control boards has to be executed under power blackout. In this environment, we take advantage of solar power system to overcome the power out. In this paper, we poposed a effficient power control strategy. Our experimental device is a DSLR shooting device executed based a predesigned interval time. The control module of our experimental device is the compound system of Raspberry Pi and Arduino boards. Arduino board send the force signals to wake up Raspberry Pi. We developed a new control strategy algorithm for the efficient use of solar power energy. In this paper, we mesured the efficiency of solar enery consuming of our system. We programmed a control system to send DSLR shooting signals. In experimentals, we ensured a stable consuming of electricity during 10 days. In the end, it was found that the consumption power of the Raspberry was reduced by about 81% when the Aduino was combined to save power.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.631-634
• /
• 2009

Recent advances in wireless communication, electronics, MEMS device, sensor and battery technology have made it possible to manufacture low-cost, low-power, multi-function tiny sensor nodes. A large number of tiny sensor nodes form sensor network through wireless communication. Sensor networks represent a significant improvement over traditional sensors, research on Zigbee wireless image transmission has been a topic in industrial and scientific fields. In this paper, we design a Zigbee wireless image sensor node and multimedia monitoring server system. It consists of embedded processor, memory, CMOS image sensor, image acquisition and processing unit, Zigbee RF module, power supply unit and remote monitoring server system. In the future, we will further improve our Zigbee wireless image sensor node and monitoring server system. Besides, energy-efficient Zigbee wireless image transmission protocol and interworking with mobile network will be our work focus.

• Plant Journal
• /
• v.13 no.4
• /
• pp.48-50
• /
• 2017

A program for analyzing the transient behaviors of industrial gas turbines was developed. Each component (compressor, combustor, turbine and ducts)of gas turbine is modeled as a fully module to enhance the expandability of the program. We used object-oriented programing for this purpose. The mass and energy balance equations are solved numerically by Multivariable Newton Raphson method. The characteristic maps for the compressor and turbine were used for predicting the performance of a gas turbine engine. Combustion in the combustor is assumed to be complete combustion. PID control is used to maintain constant rotational speed and turbine exhaust temperature by the control of the fuel flow rate and the changing of the compressor inlet guide vane angle at the same time. It was confirmed that stable control of the gas turbine was possible, even for a rapid load change.

• Journal of IKEEE
• /
• v.23 no.3
• /
• pp.785-792
• /
• 2019

In parallel operation of multiple power converter modules, equal power distribution among modules shall be made to improve the reliability of the system. In this paper, a novel droop method is proposed to present improved current distribution characteristics. In the proposed method, if the current in each module become greater than the current set-point value, the output voltage set-point is raised to improve the current distribution characteristics. Meanwhile, when the output voltage is to be managed within the tolerance range, the range of the usable control IC reference value ($v_{ref}$) will be reduced if the output voltage setting is always raised. Thus, in case the output voltage set-point among modules is reversed, the downward adjustment is introduced. The proposed method was experimentally validated with a 17.5V/500mA prototype of two boost converters operating in parallel.

• Korean Journal of Materials Research
• /
• v.29 no.1
• /
• pp.11-15
• /
• 2019

Severe wall thinning is found on the tube of a low-pressure evaporator(LPEVA) module that is used for a heat recovery steam generator(HRSG) of a district heating system. Since wall thinning can lead to sudden failure or accidents that lead to shutdown of the operation, it is very important to investigate the main mechanism of the wall thinning. In this study, corrosion analysis associated with a typical flow-accelerated corrosion(FAC) is performed using the corroded tube connected to an upper header of the LPEVA. To investigate factors triggering the FAC, the morphology, composition, and phase of the corroded product of the tube are examined using optical microscopy, scanning electron microscopy combined with energy dispersive spectroscopy, and x-ray diffraction. The results show that the thinnest part of the tube is in the region where gas directly contacts, revealing the typical orange peel type of morphology frequently found in the FAC. The discovery of oxide scales containing phosphate indicates that phosphate corrosion is the main mechanism that weakens the stability of the protective magnetite film and the FAC accelerates the corrosion by generating the orange peel type of morphology.

• Journal of the Korean Society of Safety
• /
• v.36 no.5
• /
• pp.79-85
• /
• 2021

A standard engineering model that reflects the current organization system and engineering operation process of domestic nuclear power plants was developed based on the Standard Nuclear Performance Model developed by the American Nuclear Energy Association. The level 0 screen, which is the main screen of the engineering model computer system, consisted of an object tree structure, which provided information that is phased down from a higher structure level to a lower structure level (i.e., level 3). The level 1 screen provided information related to the sub-process of the engineering operation, whereas the Level 2 screen provided information related to each engineering operation activity. In addition, the Level 2 screen provided additional functions, such as linking electronic procedures/guidelines, providing electronic performance forms, and connecting legacy computer systems (such as total equipment reliability monitoring system, configuration management systems, technical information systems, risk monitoring systems, regulatory information, and electronic drawing system). This screen level increased the convenience of user's engineering tasks by implementing them. The computerization of an engineering model that connects the entire engineering tasks of an establishment enables the easy understanding of information related to the engineering process before and after the operation, and builds a foundation for the enhancement of the work efficiency and employee capacity. In addition, KHNP developed an online training module, which operates as an e-learning process, on the overview and utilization of a standard engineering model to expand the understanding of standard engineering models by plant employees and to secure competitiveness.

• Nuclear Engineering and Technology
• /
• v.54 no.8
• /
• pp.3059-3072
• /
• 2022

A Jacobian-Free Newton Krylov Two-Nodal Coarse Mesh Finite Difference algorithm based on Nodal Expansion Method (NEM_TNCMFD_JFNK) is successfully developed and proposed to solve the three-dimensional (3D) and multi-group reactor physics models. In the NEM_TNCMFD_JFNK method, the efficient JFNK method with the Modified Incomplete LU (MILU) preconditioner is integrated and applied into the discrete systems of the NEM-based two-node CMFD method by constructing the residual functions of only the nodal average fluxes and the eigenvalue. All the nonlinear corrective nodal coupling coefficients are updated on the basis of two-nodal NEM formulation including the discontinuity factor in every few newton steps. All the expansion coefficients and interface currents of the two-node NEM need not be chosen as the solution variables to evaluate the residual functions of the NEM_TNCMFD_JFNK method, therefore, the NEM_TNCMFD_JFNK method can greatly reduce the number of solution variables and the computational cost compared with the JFNK based on the conventional NEM. Finally the NEM_TNCMFD_JFNK code is developed and then analyzed by simulating the representative PWR MOX/UO₂ core benchmark, the popular NEACRP 3D core benchmark and the complicated full-core pin-by-pin homogenous core model. Numerical solutions show that the proposed NEM_TNCMFD_JFNK method with the MILU preconditioner has the good numerical accuracy and can obtain higher computational efficiency than the NEM-based two-node CMFD algorithm with the power method in the outer iteration and the Krylov method using the MILU preconditioner in the inner iteration, which indicates the NEM_TNCMFD_JFNK method can serve as a potential and efficient numerical tool for reactor neutron diffusion analysis module in the JFNK-based multiphysics coupling application.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.2
• /
• pp.176-183
• /
• 2022

High-purity waste CNTs were mixed into cement mortar to manufacture heat-generating concrete that can use low voltage power, and carbon fiber and waste cathode materials were also used improve the conductivity of the mortar. The waste CNTs were analyzed to have a high concentration of multi-walled CNTs, and substituted liquid type waste CNTs were used during mortar mixing in order to increase dispersibility. The temperature change of the mortar with CNT was evaluated when using electric power below DC 24 V in order to utilize a small self-generation facility such as small solar power module when the mortar heats up and to minimize electromagnetic waves. When liquid-type waste CNTs were applied and a voltage of DC 24 V was introduced, it rose to 60 ℃ in a 200 × 100 × 50 mm mortar block specimen. The field applicability of self heating mortar with waste CNT was sufficient and also the amount of change in heat energy in mortar with liquid type waste CNT, carbon fiber and waste cathode materials is more effective compared to it of other variables.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2021.10a
• /
• pp.199-201
• /
• 2021

The Internet of Things (IoT) is a technology that can organically connect people and things without time and space constraints by using communication network technology and sensors, and transmit and receive data in real time. The IoT used in all industrial fields has limitations in terms of storage allocation, such as device size, memory capacity, and data transmission performance, so it is important to manage power consumption to effectively utilize the limited battery capacity. In the prior research, there is a problem in that security is deteriorated instead of improving power efficiency by lightening the security algorithm of the encryption module. In this study, we proposes a low-power security architecture that can utilize high-performance security algorithms in the IoT environment. This can provide high security and power efficiency by using relatively complex security modules in low-power environments by executing security modules only when threat detection is required based on inspection results.

• Nuclear Medicine and Molecular Imaging
• /
• v.42 no.6
• /
• pp.469-477
• /
• 2008

Purpose: The goal of this paper is to present the design and performance of a position encoding circuit for $16{\times}16$ array of position sensitive multi-anode photomultiplier tube for small animal PET scanners. This circuit which reduces the number of readout channels from 256 to 4 channels is based on a charge division method utilizing a resistor array. Materials and Methods: The position encoding circuit was simulated with PSpice before fabrication. The position encoding circuit reads out the signals from H9500 flat panel PMTs (Hamamatsu Photonics K.K., Japan) on which $1.5{\times}1.5{\times}7.0\;mm^3$ $L_{0.9}GSO$ ($Lu_{1.8}Gd_{0.2}SiO_{5}:Ce$) crystals were mounted. For coincidence detection, two different PET modules were used. One PET module consisted of a $29{\times}29\;L_{0.9}GSO$ crystal layer, and the other PET module two $28{\times}28$ and $29{\times}29\;L_{0.9}GSO$ crystal layers which have relative offsets by half a crystal pitch in x- and y-directions. The crystal mapping algorithm was also developed to identify crystals. Results: Each crystal was clearly visible in flood images. The crystal identification capability was enhanced further by changing the values of resistors near the edge of the resistor array. Energy resolutions of individual crystal were about 11.6%(SD 1.6). The flood images were segmented well with the proposed crystal mapping algorithm. Conclusion: The position encoding circuit resulted in a clear separation of crystals and sufficient energy resolutions with H9500 flat-panel PMT and $L_{0.9}GSO$ crystals. This circuit is good enough for use in small animal PET scanners.