• Proceedings of the Korean Nuclear Society Conference
• /
• 2002.10a
• /
• pp.91.2-91
• /
• 2002

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.1
• /
• pp.69-76
• /
• 2017

In this study, design of a small hybrid rocket is carried out using Failure Mode and Effects Analysis (FMEA) and Criticality Analysis(CA), which is a method for qualitative and semi-quantitative reliability analysis. In order to carry out FMEA, the structure of the hybrid rocket is divided into 31 parts and 72 potential failure modes. As a result of the FMEA, the relationship between potential failure modes, causes and effects, and their severity are evaluated qualitatively. Criticality analysis is followed for the failure modes, in which the criticality number is estimated using the failure rate information available from the handbook. Moreover, the failure modes with higher criticality and severity are chosen for improvement, and a series of design or material changes are made for the improvement of the hybrid rocket reliability.

• Nuclear Engineering and Technology
• /
• v.22 no.2
• /
• pp.128-138
• /
• 1990

This paper presents a prototype expert system (ESRCP) for Reactor Coolant Pumps. The purpose of this system is to diagnose RCP failures and to offer corrective operational guides to plant operators. The first symptoms for the diagnosis are the alarms which are related to the RCP domain. Alarm processing is required to find a primary causal alarm when multiple alarms occur. The system performs the alarm processing by rule-based deduction or priority factor operation. To diagnose the RCP failure, the system performs rule-based deduction or Bayesian inference. Various sensor readings are required as symptoms to infer a root cause. When the symptoms are insufficient or uncertain to diagnose accurately, Bayesian inference is performed.

• Proceedings of the KIEE Conference
• /
• 2008.10a
• /
• pp.75-76
• /
• 2008

전력거래소는 전격계통 안정된 운영과 공정한 전력시장 운영을 주요 임무로 하며, 이를 위하여 전국의 80여개의 발전소와 600여개 변전소로부터 발전량, 전압, 조류, 자단기 상태정보 등 다양한 전력계통 자료를 취득하고 있다 전력거래소의 중앙급전소에는 이와 같은 계통자료 취득은 물론 발전량 제어기능을 수행하기 위한 에너지관리시스템(이하 EMS 라 한다)을 운영하고 있으며, 발,변전소에는 현장의 전력설비와 연결되어 계통자료를 취득하여 EMS로 전송하는 원격소장치 (이하 RTU 라한다)를 운영하고 있다. 자료취득 경로는 모든 발전소와 34skv급 이상의 변전소의 경우 EMS와 RTU가 직접 연결되어 자료를 취득하며 154Kv급 이하 변전소는 12개 지역급전소의 자료취득제어시스템(이하 SCADA라 한다)를 경유하여 자료를 취득하고 있다. 전력계통의 대형화와 복잡화에 따라 계통해석기능 자동발전제어기능에 의한 계류운영으로 정보기술에 대한 의존도가 증가하고 있으며, 변동비 반영시장의 개선운영에 따라 공정한 전력시장 운영과 안정된 전력계통 운영을 위해 전력계통 취득자료의 신뢰도가 요구되고 있다. 따라서 EMS를 비롯한 RTU, 통신망 등 전력계통 자료취득 설비의 운영실적을 분석하여 각 시스템별 고장 고장원인 고장유형 등을 고찰하므로써 시스템 성능개선을 위한 설비투자와 운영개선에 반영하고자 한다.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.1
• /
• pp.59-64
• /
• 2016

This paper aims at the prototype-making of the intelligent switchgear with arc fault diagnosis function required to prevent the electrical fire. The main control unit of the intelligent switchgear consists of a single-phase power management device and a arc fault diagnosis device. The prototype of the single-phase power management device and the prototype of the arc fault diagnosis device in this paper. In the device, the cooperation function with the arc fault diagnosis device is developed to transmit the cause of the electrical fire to the remote server system.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.7
• /
• pp.93-102
• /
• 2017

Recently increasing usage of smartphones makes the Internet of Things (IoT) a leading technology that can collect and share data through sensor networks and wireless communication such as low-power Bluetooth (BLE). BLE-based application can provide operators more precise information on Automatic Door system by remotely diagnosing the system faults through wireless sensor networks and sensors around the Automatic Door. In this paper, a smart device with extended BLE module is implemented which can monitor and Control the system states and faults remotely without on-site diagnostic. while maintaining system integrity so that increase efficiency of time and costs for system management. We can use the results of this research as a basis in evaluating reliability of data between devices, extending communication module in Controller of obsolete Door systems, and establishing centralized monitoring systems in near future with multi-channel Door Controls.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.6
• /
• pp.706-714
• /
• 2020

Currently, 90 % of the world's population breathes air with a fine dust content exceeding the World Health Organization's annual average exposure limit (10 ㎍/㎥). Global efforts have been devoted toward reducing secondary pollutants and ultra-fine dust through regulations on nitrogen oxides released over land and sea. Domestic efforts have also aimed at creating clean marine environments by reducing sulfur emissions, which are the primary cause of dust accumulation in ships, through developing and distributing environment-friendly ships. Among the technologies for reducing harmful emissions from diesel engines, electrostatic precipitator offer several advantages such as a low pressure loss, high dust collection efficiency, and NOx removal and maintenance. This study aims to increase the durability of a ship by improving equipment quality through failure mode effects analysis for the preventive maintenance of an electrostatic precipitator that was developed for reducing fine dust particles emitted from the 2,427 kW marine diesel engines in ships with a gross tonnage of 999 tons. With regard to risk priority, failure mode 241 (poor dust capture efficiency) was the highest, with an RPN of 180. It was necessary to determine the high-risk failure mode in the collecting electrode and manage it intensively. This was caused by clearance defects, owing to vibrations and consequent pin loosening. Given that pin loosening is mainly caused by vibrations generated in the hull or equipment, it is necessary to manage the position of pin loosening.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.12
• /
• pp.102-109
• /
• 2019

This paper describes the design of the circuit card assembly to eliminate the communication error on a servo control unit installed in the automated resupply vehicle K56. K56 is a weapon system that automates the supply and loading of ammunition on the K-55A1 self-propelled artillery. As the core item responsible for ammunition movement control, the servo control unit is required to have good communication stability and reliability, but the conventional unit has recognized a problem that communication error intermittently occurs, resulting in an emergency stop phenomenon. We analyzed the communication signal of the servo control unit and identified the failure cause of the circuit card assembly to solve this problem. In addition, the signal interference in data/address line of the circuit card assembly was confirmed through analysis of the failure cause, and redesigned to avoid the interference, such as adjustment of the distance between communication lines and position change. Finally, the proposed cause analysis and redesign were verified through the component of servo control unit and attachment test on K56. We expected these study results to be used as reference for the design of other similar items.

• Proceedings of the Korea Multimedia Society Conference
• /
• 1998.04a
• /
• pp.400-405
• /
• 1998

현재 네트워크 환경과 컴퓨터시스템 환경에서의 고장 또는 장애에 의해서 통신이 않되는 경우에는 사용자들의 불편이 가중되고 있는 실정이다. 네트워크의 확장으로 인하여 네트워크를 관리하기 위한 도구들이 개발되어 왔다. 이 문제를 해결하기 위해서 본 논문에서는 네트워크 및 컴퓨터시스템 환경에서 발생하는 장애에 대한 원인 분석과 이에 따른 장애의 진단과 처치를 위하여 전문가시스템의 기법을 도입하였다. 장애의 원인을 탐색하기 위하여서는 추론기관과 지식베이스를 구성하였으며, 장애요인에 대한 지식은 장애를 하나의 객체로 하는 기법을 사용하였다.

• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.482-483
• /
• 2006

배전급 가스절연개폐기(이하 개폐기)에서 발생하는 고장을 예방하기 위해서는 개폐기 내부에서 발생하는 부분방전 신호로부터 방전의 원인을 추정하는 것이 중요하다. 본 논문에서는 개폐기 내부의 결함을 다양하게 모의하여 방전원에 대한 신호 패턴을 분류하고 방전 원인별로 특성을 분석하였다.