• Journal of the Society of Naval Architects of Korea
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• v.59 no.5
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• pp.306-313
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• 2022

Most submarines use the cross-plane, which is convenient and inexpensive, but the number of submarines equipped with an X-plane is increasing recently. This study focuses on designing the control system of the X-plane submarine with various control methods and analyzing the effect of each controller. First, a maneuvering simulation environment for a subjected submarine is established. The dynamics and the operating range of control surfaces are considered. Second, a depth and heading control system of the submarine, which can be divided into three parts, is designed: guidance, controller, and control allocation. The guidance system generates a smooth desired depth and heading. The controller is designed using Proportional-Integral-Differential (PID), Linear Quadratic Regulator (LQR), and H-infinity (H∞) control methods. A linear control allocation method is used to distribute control moment calculated by the controller to the control surfaces. Finally, the designed control system is applied to a subjected X-plane submarine, and a depth and heading control simulations are performed. Each control method is compared and analyzed under various simulation conditions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2285-2291
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• 2011

In this paper, H.264 high profile intra frame encoder, which integrates intra prediction, context-based adaptive variable length coding(CAVLC), and DDR2 memory control module, is proposed. The designed encoder can be operated in 440 cycle for one-macroblock. In order to verify the encoder function, we developed the reference C from JM 13.2 and verified the developed hardware using test vector generated by reference C. The designed encoder is verified in the FPGA (field programmable gate array) with operating frequency of 200 MHz for DMA (direct memory access), operating frequency of 50 MHz of Encoder module, and 25 MHz for VIM(video input module). The number of LUT is 43099, which is about 20 % of Virtex 5 XC5VLX330.

• Journal of Biosystems Engineering
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• v.19 no.2
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• pp.91-98
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• 1994

Planting, transplanting, and harvesting are important processes for the successful production of farm products in Korea because those require the high labor intensity during limitted period. Recently, many researches of using automatic control with a microcomputer are carried in the agricultural field, but are not much spread to the seeder development. Automatic sowing technology would be much attractive if there was a way to assure that each seed was count accurately in the seed metering device. Thus, an automatic seed metering device was designed and constructed to be controlled by microcomputer. This device could be improved in not only counting the number of seeds in but also sowing seeds between row spacings. Automatic seed metering device consisted of conveyor belt and temporary storage device. Performance of seed metering device depends on the apparatus including sensor, stepping motor and DC-solenoid. Research contents and results are summarized as follows. 1. The seed metering device involving seed hopper, sorter and temporary storage device was designed and constructed. 2. A seed counting system with six photo electric sensors, designed and built for this project, was adequate for tranferring and counting seeds accurately. 3. Operating algorithm for stepping motor and photo electric DC-solenoid was developed. The Seed metering device proved to be a smooth and accurate operating device using the algorithm. 4. The performance of second prototype metering device was examined with five kinds of seeds ; mung beans, red beans, white beans, black beans and corn to transfer and count the seeds. The error ratio of seed metering was less than 3.5%.

• ETRI Journal
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• v.28 no.3
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• pp.282-290
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• 2006

In vertically overlaid cellular systems, a temporary traffic concentration can occur in a hot-spot area, and this adversely affects overall system capacity. In this paper, we develop an adaptive hot-spot operating scheme (AHOS) to mitigate the negative effects from the nonuniform distribution of user location and the variation in the mixture of QoS requirements in orthogonal frequency division multiple access downlink systems. Here, the base station in a macrocell can control the operation of picocells within the cell, and turns them on or off according to the system overload estimation function. In order to determine whether the set of picocells is turned on or off, we define an AHOS gain index that describes the number of subcarriers saved to the macrocell by turning a specific picocell on. For initiating the picocell OFF procedure, we utilize the changes in traffic concentration and co-channel interference to the neighboring cells. According to computer simulation, the AHOS has been proved to have maximize system throughput while maintaining a very low QoS outage probability under various system scenarios in both a single-cell and multi-cell environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.4
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• pp.399-402
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• 2016

We propose a thin electromagnetic wave absorber using varactor diodes combined with intentionally introduced multiple slits, which enables continuous sweep of an absorption frequency band throughout relatively wide frequencies. The absorption frequency range of conventional electrically tunable absorbers has been restricted by high capacitance of varactor diodes. In order to overcome the problem, we introduce parasitic capacitance and connect them with varactors in series, which reduces the total capacitance dramatically. As a result, we can raise the operating absorption frequency up to the X-band region. Moreover, we can also control the operating frequencies by modifying the number of slits with little change in an entire frequency sweep range. Good agreement between simulated and measured results show the validity of our proposal.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.103-109
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• 2019

The automotive electronic system should provide a method that can be safely performed by loading a number of application programs having time constraints in several electronic control devices. In this paper, we propose a timing protection mechanism for AUTOSAR, which is a real - time operating system specification for automotive field, in order to observe the deadline of each task when scheduling real - time tasks. We propose a dynamic non-preemption algorithm to guarantee a flexible deadline for fixed priority or dynamic priority tasks, and a location where execution time can be monitored for errors, and suggest ways to implement the AUTOSAR time protection mechanism.

• The Journal of Information Systems
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• v.33 no.1
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• pp.115-131
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• 2024

Purpose This study aims to analyse the impact of the development of fintech and the emergence of internet primary banks due to the increasing use of smartphones on the performance of traditional local banks from both financial and non-financial perspectives. Return on equity (ROE) and return on assets (ROA) are used to assess the performance differences between the two types of banks and how these differences are affected by their financial characteristics. Design/methodology/approach Using return on equity (ROE) and return on assets (ROA) as indicators, we identified the differences in operating performance between the two types of banks. In addition, this study analysed the impact of financial characteristics on profitability through regression analysis with various control variables. We further studied the impact of non-financial characteristics (customer reviews, social media reactions, etc.) on operating performance. Findings The net interest margin ratio of local banks had a positive impact, while the marketable securities ratio of Internet primary banks had a negative impact. The non-financial analysis shows that the number of customer reviews and social media reactions have a significant impact on the performance of Internet primary banks, suggesting that customer satisfaction and positive market perception are important factors in the performance of Internet primary banks.

• Journal of Biomedical Engineering Research
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• v.29 no.1
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• pp.32-39
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• 2008

This paper reports on a realtime OS based master-slave configuration robot control system for laparoscopic surgery robot which enables telesurgery and overcomes shortcomings with conventional laparoscopic surgery. Surgery robot system requires control system that can process large volume information such as medical image data and video signal from endoscope in real-time manner, as well as precisely control the robot with high reliability. To meet the complex requirements, the use of high-level real-time OS (Operating System) in surgery robot controller is a must, which is as common as in many of modem robot controllers that adopt real-time OS as a base system software on which specific functional modules are implemened for more reliable and stable system. The control system consists of joint controllers, host controllers, and user interface units. The robot features a compact slave robot with 5 DOF (Degree-Of-Freedom) expanding the workspace of each tool and increasing the number of tools operating simultaneously. Each master, slave and Gill (Graphical User Interface) host runs a dedicated RTOS (Real-time OS), RTLinux-Pro (FSMLabs Inc., U.S.A.) on which functional modules such as motion control, communication, video signal integration and etc, are implemented, and all the hosts are in a gigabit Ethernet network for inter-host communication. Each master and slave controller set has a dedicated CAN (Controller Area Network) channel for control and monitoring signal communication with the joint controllers. Total 4 pairs of the master/slave manipulators as current are controlled by one host controller. The system showed satisfactory performance in both position control precision and master-slave motion synchronization in both bench test and animal experiment, and is now under further development for better safety and control fidelity for clinically applicable prototype.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2773-2778
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• 2015

In this paper, the compact antenna with three folded patches for use in a number of bands of LTE, WCDMA, US-PCS, and WLAN at the same time is proposed. As the changes in widths of the 3 patches to widen the insufficient bandwidth are given, it is optimized for $S_{11}$<-6dB(VSWR<3). The CPW with a number of advantages is used in the proposed antenna. The proposed antenna is designed and fabricated with FR4 substrate to the size of $44.9{\times}35{\times}1mm^3$. Fabricated antenna has within $S_{11}$<-6dB under operating bands. And measured characteristics of radiation patterns and gains are shown under operating bands.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.4
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• pp.194-202
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• 2019

Reliability analysis of the components frequently starts with the data that manufacturer provides. If enough failure data are collected from the field operations, the reliability should be recomputed and updated on the basis of the field failure data. However, when the failure time record for a component contains only a few observations, all statistical methodologies are limited. In this case, where the failure records for multiple number of identical components are available, a valid alternative is combining all the data from each component into one data set with enough sample size and utilizing the useful information in the censored data. The ROK Navy has been operating multiple Patrol Killer Guided missiles (PKGs) for several years. The Korea Multi-Function Control Console (KMFCC) is one of key components in PKG combat system. The maintenance record for the KMFCC contains less than ten failure observations and a censored datum. This paper proposes a Bayesian approach with a Dirichlet mixture model to estimate failure time density for KMFCC. Trends test for each component record indicated that null hypothesis, that failure occurrence is renewal process, is not rejected. Since the KMFCCs have been functioning under different operating environment, the failure time distribution may be a composition of a number of unknown distributions, i.e. a mixture distribution, rather than a single distribution. The Dirichlet mixture model was coded as probabilistic programming in Python using PyMC3. Then Markov Chain Monte Carlo (MCMC) sampling technique employed in PyMC3 probabilistically estimated the parameters' posterior distribution through the Dirichlet mixture model. The simulation results revealed that the mixture models provide superior fits to the combined data set over single models.