• 한국통신학회논문지
• /
• 제33권12A호
• /
• pp.1177-1184
• /
• 2008

Non-line-of-sight (NLOS) propagation can severely weaken the accuracy of ranging and localization in wireless location systems. NLOS bias mitigation techniques have recently been proposed to relieve the NLOS effects, but positively rely on the capability to accurately distinguish between LOS and NLOS propagation scenarios. This paper proposes an energy-capture-based NLOS identification method for LDR-UWB systems, based on the analysis of the characteristics of the channel impulse response (CIR). With this proposed energy capture method, the probability of successfully identifying NLOS is much improved than the existing methods, such as the kurtosis method, the strongest path compare method, etc. This NLOS identification method can be employed in adaptive modulation scheme to decrease bit error ratio (BER) level for certain signal-to-noise ratio (SNR). The BER performance with the adaptive modulation can be significantly enhanced by selecting proper modulation method with the knowledge of channel information from the proposed NLOS identification method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 B
• /
• pp.1050-1052
• /
• 1996

This paper presents a neuro-control algorithm for the speed control of a direct drive motor without the knowledge of the dynamics of the motor and the characteristics of a nonlinear load. In the field of motor control, it is not possible to directly use the back-propagation method in order to train a network since the desired output of the network is not known. Hence, we propose an extended back-propagation algorithm to force the closed loop system to give desired results. Experimental results shown that the proposed neuro-controller can reduce the unknown load effects and have the good velocity tracking capabilities.

• 전기학회논문지
• /
• 제63권10호
• /
• pp.1337-1346
• /
• 2014

Power system technologies in the area of smart grid are being converged with communication system technologies or information technologies(IT). This interdisciplinary action affects on two parts vigorously so that IT has become a essential part of power industry. But terminologies of two parts are confused and it is necessary that these are standardized to develop the industry. The writing system of the Open Korean Knowledge Dictionary for standardization of smart grid terminologies which are IEC TC 57 glossary and non-glossary is proposed. The writing system includes the process of collection, writing guideline and standardization of terminologies. Writing results of 90,000 terminologies for electricity, communication and computer fields including smart grid terminologies, which are registered in the Open Korean Knowledge Dictionary, are shown. The system provides the capability of collection and delivery of academic society opinions for the selected and interpreted terminologies through the internet for standardization and industry propagation of smart grid terminologies.

• 경영과정보연구
• /
• 제23권
• /
• pp.75-97
• /
• 2007

In the meantime hospital system of Korea has institutionally performed its errand in stable circumstance, however the system now faces with new environment of change of customer's satisfaction, of regime, deepening of competition, and opening market. Under the rapidly and complicatedly changing circumstance, the hospital system is required to promote getting a dominant position in the competition, enhancing outcome, creating value added, and customer satisfaction in both internally and externally likewise other organizations, as they continuously introduce a knowledge management and originate, accumulate, and put the knowledge to practical use. This organization capacity of knowledge management involves a process of management that requires great change of all organizations and individuals and it is brought up through four steps which are Initiation, Propagation, Integration, and Networking. The main factors of successful knowledge management are intension of the chief executive officer(CEO), organizational culture, appraisal and compensation of work, knowledge controlling system, and organizational structure, and each of these five stage has got different characteristic. To be successful by introducing knowledge management, hospital organization should be based on these premises. Not only CEO or the director of a hospital, but also the constituent members should be fully aware of knowledge, the characteristic of knowledge management, and successful factors of this operation. Should understand step-by-step characteristic of knowledge management, therefore able to analyse a situation of specific hospital and see which step corresponds to that hospital. By analysing, constituents should make up for the weak points and ready to move on to next step. CEO or the director of a hospital should be aware of knowledge management as a strategic factor which is able to get a dominant position in the rapidly changing environment, and also it should be firm in the director's intention to introduce the knowledge management into the hospital. By continuously carrying out education and training constituent members, the director of a hospital should promote their interest and participation in knowledge management, and build an organization culture that ultimately creates, accumulates, shares, and put the knowledge to practical use. The hospital organization needs to systematize an institution of objective compensation that corresponds to objective appraisal of knowledge management outcome. The hospital ought to build knowledge controlling system in stages, in order to take the initiative in rapidly changing environment. By considering the characteristic of hospital system, it is required to change the organizational structure into self-managing team which is a sort of horizontal structure that allows members to make decisions and take the responsibility by themselves. The limitation of this study is experimental study. Positive investigation about successful factors of hospital knowledge management and characteristic of each steps is expected with following study.

• Korean Chemical Engineering Research
• /
• 제47권5호
• /
• pp.572-579
• /
• 2009

본 연구에서는 분진폭발에 있어서 기초적 현상을 규명하고 분진의 화염구조와 메커니즘에 대하여 실험적으로 조사하였다. 실험장치는 길이 1.8 m, 단면이 0.15 m의 정방형인 수직연소관을 사용하였으며, 덕트 내를 전파하는 상방 분진층류화염과 화염면에 대하여 고속카메라를 사용하여 가시화하였다. 또한 슐리렌, 이온프로브, 열전대 등을 사용하여 예열대 및 반응대의 두께를 측정하였다. 석송자 분진화염의 예열대 두께는 4~13 mm로 탄화수소가스의 예혼합기 화염보다도 수배 크다. 입자화상유속법(PIV)에 의한 해석 결과, 예열대에서의 미연소 입자의 체류 시간은 입자의 열분해가스 생성에 필요하며, 체류시간은 화염전파속도, 입자속도 및 예열대 두께에 의존하는 것을 알았다.

• Steel and Composite Structures
• /
• 제25권3호
• /
• pp.361-374
• /
• 2017

In this study, the influences of triaxial magnetic field on the wave propagation behavior of anisotropic nanoplates are studied. In order to include small scale effects, nonlocal strain gradient theory has been implemented. To study the nanoplate as a continuum model, the three-dimensional elasticity theory is adopted in Cartesian coordinate. In our study, all the elastic constants are considered and assumed to be the functions of (x, y, z), so all kind of anisotropic structures such as hexagonal and trigonal materials can be modeled, too. Moreover, all types of functionally graded structures can be investigated. eigenvalue method is employed and analytical solutions for the wave propagation are obtained. To justify our methodology, our results for the wave propagation of isotropic nanoplates are compared with the results available in the literature and great agreement is achieved. Five different types of anisotropic structures are investigated in present paper and then the influences of wave number, material properties, nonlocal and gradient parameter and uniaxial, biaxial and triaxial magnetic field on the wave propagation analysis of anisotropic nanoplates are presented. From the best knowledge of authors, it is the first time that three-dimensional elasticity theory and nonlocal strain gradient theory are used together with no approximation to derive the governing equations. Moreover, up to now, the effects of triaxial magnetic field have not been studied with considering size effects in nanoplates. According to the lack of any common approximations in the displacement field or in elastic constant, present theory has the potential to be used as a bench mark for future works.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
• /
• pp.112-114
• /
• 1991

This paper describes an application of neural network to diagnose defect of induction motor and investigates possibility to construct defect diagnosis system to be operated without special knowledge. For defect diagnosis, frequency spectrum of vibration is utilized. Learning method of applied neural network is back propagation.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
• /
• pp.131-134
• /
• 1990

A back-propagation neural network based system for a fault diagnosis of a chemical process is developed. Training data are acquired from FCD(Fault-Consequence Digraph) model. To improve the resolution of a diagnosis, the system is decomposed into 6 subsystems and the training data are composed of 0, 1 and intermediate values. The feasibility of this approach is tested through case studies in a real plant, a naphtha furnace, which has been used to develop a knowledge based expert system, OASYS (Operation Aiding expert SYStem).

• 한국안전학회지
• /
• 제13권1호
• /
• pp.77-84
• /
• 1998

Hazard and operability (HAZOP) analysis is one of the safety analysis method that is used in the chemical complex, because it can systematically identify causes and consequences of all the deviation that could occur. Since this method needs to hire specialized experts, it is costly and time-consuming. Therefore HAZOP Expert System has been developed to automate this analysis. This approach introduced object-oriented method and knowledge representation which is hierarchical tree of units to supply flexibility in the system, functional semantic network, propagation equation and rule-chaining method to set up the expert system for automating HAZOP analysis.

• 대한기계학회논문집
• /
• 제17권12호
• /
• pp.3124-3134
• /
• 1993

Diagnosis is composed of two different but interrelated steps ; retrieving the sensory responses f the system and reasoning the state of the system through the given sensor data. This paper explains the probabilistic nature of reasoning involved in the diagnosis when the uncertainties are inevitably included in experts' diagnostic decision making. Uncertainties in decision making are experts' personal experiences, preferences, and system's coherent characteristics. In order to ensure a consistent decision based on the same responses from the system, expert system technology is adopted with the Bayesian reasoning scheme.