• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.240-242
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• 1988

This paper proposes an improved ART (Algebraic Reconstruction technique) algorithm. This algorithm is an iterative one with iteration sequence criteria based on the discrepancy between measurement and pseudo-projection data. The simulation result using the proposed algorithm shows a significant improvement in convergency rate over the conventional ART algorithm.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.894-896
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• 1997

This paper presents the continuation power flow system that is under development. The continuation power flow system provides robust solutions of power flow equations at any operating point. The robust convergency enables one to find solutions even at the point where power flow jacobian becomes singular. Basic concept of an algorithm and its application to static voltage stability analysis are presented.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.3
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• pp.351-362
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• 1994

This paper presents a new method for solving a long term unit commitment problem including hydro and pumped storage hydro units in a large scale power system. The proposed method makes it possible to get variable power of hydro and pumpde storage hydro units and results in the better unit commitment with good convergency. Moreover this paper proposes an unit commitment algorithm to consider variable power of these units effectively by Lagrangian Relaxation method. By applying the proposed method to the test system and the real system, it is verified the usefulness of this method.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.78-85
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• 2000

Computer algorithms for the loadflow of the DC traction power supply system are examined. Algorithms to solve the nodal equation are reviewed and the two iterative methods to solve the nonlinear nature of the loadflow are analyzed and tested, which are so called conductance matrix method and current vector iterative mettled. The result of the analysis tells that the current vector iterative method makes faster convergency and needs less computing time, and it is verified by the test running of the programs based on each of the iterative methods.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.526-528
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• 2022

실외 자율주행 청소 로봇을 위한 인공지능기반 자율주행 시스템을 개발하였다. 개발된 시스템은 ROS(Robot Operationg System) 기반으로 이루어졌으며, 3D 라이다와, 초음파 센서를 활용하여 주변의 장애물을 감지하고 GPS와 영상을 활용하여 로봇의 위치 인식을 하여 자율 주행을 진행하였다. 자율주행 실험결과 영상과 RTK-GPS를 사용하여 정해진 경로를 ±20cm이내의 오차를 가지고 추종하면서 청소를 진행하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.622-622
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• 2013

Piezoelectric energy harvesting (PEH) device refers to a power device for acquiring mechanical energy from the environment surrounding us which would otherwise be wasted and for converting it into usable electrical energy. While much work has been done on developing ZnO nanogenerator (NG) with nanowire arrays, there are some issues of not only scaling up its output power but also optimizing structure for operating feasibly in various conditions. Efficiency of NG is highly dependent on fixed orientation. But in many cases, it is not easy to predict where the pressure and vibration may come from. Furthermore, the direction of the applied mechanical stress is usually non-stationary and can be random in various practical applications. Therefore an omnidirectional PEH is needed.In this work, we investigate an omnidirectional PEH device consisting ZnO nanowires. We deposited spiral patterned ZnO seed layer on Kapton film. We deposited thin Cr layer on the ZnO seed layer using DC-sputter to form a passivation layer to retard un-expected growth of ZnO nanowires. We grew ZnO nanowires along the spiral arms using hydrothermal method. ZnO nanowires have been selectively grown from the ZnO sidewall without Cr layer and have the average length of$5{\mu}m$ and the average diameter of 40nm. We reduced the defect in the as-grown ZnO nanowires by O2 plasma using asher and by thermal treatment using RTA. Consequently, each nanowire has different directions to each other. This isotropic design can lead to the omnidirectional power generation. The morphology of NG is characterized with FESEM. Maximum output power of the device is measured by using a picoammeter and a nanovoltmeter.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.505-511
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• 2017

The purpose of this study is to identify the characteristic of the length of sentence of sports news articles compared with other sections, other newspaper and sports events. In order to achieve this purpose, 4 daily newspapers(Chosun Ilbo, Dong-A Ilbo, Kyunghyang Shinmun and MKsports) were selected as research sources. The length of sentence of collected articles was analyzed by One way ANOVA and Scheffe as post-hoc. The results of these analyses are summarized into three as follows: First, the length of sentence of news articles has significant difference by sections. To put it concretely, the sentences in politics section were the longest, and then economy, editorials comes. The sports section has the shortest sentences. Second, the length of sports articles has significant difference by newspapers. In particular, MK sports which is a sports-oriented newspaper has the shortest in the length of sentence of sports articles than other newspapers such as Chosun, Dong-A and Kyunghyang. Third, the length of sentence of sports articles has significant differences by the sports events. More specifically golf is the longest, and then basketball, soccer and baseball follows.

• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.55-62
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• 2018

Recently, as the threat of cyber crime increases, the importance of security control to cope with cyber attacks on the information systems in the first place such as real-time detection is increasing. In the name of security control center, cyber terror response center and infringement response center, institutional control personnel are making efforts to prevent cyber attacks. Especially, we are detecting infringement accident by using network security equipment or utilizing control system, but it's not enough to prevent infringement accident by just controlling based on device-driven simple patterns. Therefore, the security control system is continuously being upgraded, and the development and research on the detection method are being actively carried out by the prevention activity against the threat of infringement. In this paper, we have defined the method of detecting infringement of major component module in order to improve the problem of existing infringement detection method. Through the performance tests for each module, we propose measures for effective security control and study effective infringement threat detection method by upgrading the control system using Security Information Event Management (SIEM).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.2
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• pp.31-44
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• 1983

This paper applies an optimization algorithm for the elastic truss structures. The acceleration technique utilized in this study is the geometric programming method developed by the Operation Research or the applied methematics. The applicability and the efficiency of the algorithm applied in this study are tested for four different trusses. Test results show that the optimum solutions are obtained after only one or seven iterations which is very small compared with other techniques and no oscillation is needed for the convergency. Test rusults also show that the Geometric Programming Method is also effective algorithm for the convergency of the Optimum Solution in case of only being compared with the number of iteration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.365-370
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• 2016

Recently, There are increasing number of studies that apply multi-carrier method, a land mobile communication method, to underwater channel environment in order to enhance the performance of underwater communication. Therefore, in this paper, in order to design a new system with improved communication performance compared to the multi-carrier method in underwater communication, we present that the RS(Resource Spreading) FMT-OFDM system has a diversity and repetition effect from resource spreading. Moreover, we verify the performance of RS FMT-OFDM system and existing FMT-OFDM system through simulations after modeling communication channels and setting the system parameter based on the data measured from the real sea. Our result indicate that, compared to the existing FMT-OFDM system, there has been an improvement in communication performance by 12dB based on BER $10^{-3}$ we also discovered that communication performance improves as the resource spreading rate increases.