• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.681-688
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• 2018

As environmental regulations have been strengthened and high fuel efficiency has been in demand in recent years, the number of ships using natural gas as a fuel is increasing. The demand for ships using LPG or methanol, which are emerging as eco-friendly vessel fuels, is also increasing. In this perspective, ME-LGI engines using LPG or methanol as a fuel have attracted considerable attention. Ships equipped with an ME-LGI engine are required to check the reliability of the fuel injection valve during shipping. This means that the development of a fuel injection valve tester is essential for the commercialization of ME-LGI engine. This study conducted the conceptual design of a fuel injection valve tester for ME-LGI engines using a system engineering process in the order of requirements analysis, functional analysis, and design synthesis. In the requirement analysis stage, the operating process of fuel injection valve was analyzed, and the necessity of checking the sealing oil leakage was then derived. In the functional analysis stage, the functions and flow of them were defined at each functional level. In the design synthesis stage, the equipment for each function was set and the process block diagram based on it was derived. In addition, preliminary risk analysis was performed as a part of system analysis and control, and safety measures were added to the conceptual design. This study is expected to be a good reference material for the concept design of other systems in the future because it shows the application process of a system engineering process to the conceptual design in detail.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.1040-1048
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• 2016

Recently, the studies of integrated reliability analysis for combat systems are actively progressing. Especially, the research of integrated reliability analysis is emphasized to overcome limitations of the previous studies. In this paper, we propose a calculation technique for integrated hit probability based on front and side hit probabilities that analyzed in previous studies to improve the time-effectiveness. Also, we find out the integrated reliability of each component based on the integrated hit probability which is calculated, and we propose the method which applied the reliability block diagram technique to analyze the whole combat system of the reliability by function kills. For verifying the proposed method, we applied the proposed method to armored fighting vehicle model. The proposed method considers crew which does not considered the element in the previous study and expects to enhance the accuracy of reliability analysis and the time-effectiveness compared with the previous study.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.527-532
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• 2007

In this paper, we suggest those two design plans for power supply method of Hot Standby Sparing System; one is the plan using MTBF based on Constant Failure Rate, and the plan using Reliability Function is the other. Traditionally, RBD (Reliability Block Diagram) is used for reliability prediction which is required to meet any requirements before system operation. However, the system that has redundancy, such as Hot Standby Sparing System, Is not suitable for system reliability modeling using combination model, such as RBD. In this paper, therefore, we demonstrate that for redundancy controller, redundancy modeling design toward fault occurrence design is more effective to build up a system with higher reliability and achieve the effectiveness of loss cost due to maintenance and failure occurred in operation, rather than combinational modeling design.

• Smart Structures and Systems
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• v.6 no.1
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• pp.29-38
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• 2010

An ElectroMagnetic Actuator (EMA) is designed and assessed numerically and experimentally. The EMA has the advantage to be without contact with the structure so it could be applied to light and small mechanism. Nevertheless, the open-loop instability and the nonlinear dynamic behavior with respect to the excitation frequency could limit its application field. The EMA is designed and dimensioned as a function of the experimental structure to be controlled. An inverse model of the EMA is proposed in order to implement a linear action block for the used frequency range. The control strategy is a fuzzy controller with displacements and velocities as inputs. A fuzzy controller of Takagi-Sugeno type is used. The air gap is estimated by using a modal approximation of the displacements issued from all measurements. Several configurations of control are assessed by using numerical simulations. The block diagram used for numerical simulations is implemented under Dspace$^{(R)}$ environment. The implemented controller was tested experimentally in the context of impact perturbations. The results obtained show the effectiveness of the developed procedures and the robustness of the implemented control.

• Journal of the Korean Society of Systems Engineering
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• v.10 no.1
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• pp.73-80
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• 2014

Designing test case flows for water crossing operation of a wheeled vehicle is a new attempt for which very limited experiences exist. In this paper, a Function Flow Block Diagram(FFBD) and a Classification Tree Method(CTM) were combined to see if this method is viable to generate the test case flows at the functional analysis stage. It was found that this method can be practically used for the very complicated test case generation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.1
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• pp.61-69
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• 2002

This paper describes a converting algorithm between programmable languages of a software PLU. It is based on IEC 61131-3 standard and PC. The proposed control logic is designed by the software model and common element with data type, variables, POUs(program organization unit) and execution control unit commonly used within programmable languages of IEC 61131-3 Standard. The generation method of object file is proposed on five programmable language based on IEC 61131-3. It is represented as fo11ows; 1) the generation method using conversion algorithm from LD to IL with FBD(function block diagram), 2) the generation method using f code generation algorithm from SFC using the SFC execution sequence with FBD and ST(structured text). The proposed control logic generator was implemented by Visual C++ 6.0 and MFC on MS-windows NT 4.0.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06b
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• pp.184-186
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• 2012

Function Block Diagram (FBD)는 산업용 컴퓨터인 Programmable Logic Controller (PLC)의 표준 프로그래밍 언어 중 하나이다. 다양한 시험 기법들의 오류 검출 효과성을 평가하기 위해 뮤테이션 분석 기법이 널리 쓰이고 있는데, FBD 모델 대상 뮤테이션 분석 기법에 대한 연구는 이루어지지 못하였다. 본 연구에서는 FBD 모델 대상 뮤테이션 분석 기법의 토대가 되는 FBD 모델 뮤테이션 연산자를 제안한다. 이를 위해서 FBD 모델의 특성, 다양한 FBD 모델링 오류, 기존의 뮤테이션 분석 기법에 관한 연구를 포괄적으로 분석하여 FBD 모델에 적합한 뮤테이션 연산자를 정의한다. 실제 산업계에서 쓰이는 FBD 모델을 대상으로 뮤테이션 연산자를 적용하고 평가한다.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.265-266
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• 2007

본 논문에서는 안전등급 PLC(Programable Logic Controller) LD/FBD(Ladder/Function Block Diagram) 프로그램을 C-코드로 변환하는 C-코드 발생기의 시험에 관해서 다룬다. 개발된 C-코드 발생기는 로직 분석, 오류 검출, C-코드 생성 등 각 부분 별로 시험 항목을 설정하고 검증하는 방법에 대해서 서술한다. 또한 C-언어로 작성된 사용자 정의 함수/함수 블록에 관한 시험 항목을 기술한다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.1
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• pp.1-7
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• 2007

This paper addresses a the maintenance system based on the concept of RAMS (Reliability, Availability, Maintenance, Safety) for the effective maintenance of the urban transit. A systematic approach for developing a cost-effective maintenance strategy based on the component reliability of the system in question is performed according to the following steps : definition of function, functional failures of the systems, construction of RBD (Reliability Block Diagram), and the calculation of reliability indices. The developed preventive maintenance system generates maintenance plan and repair request based on the analysed RAMS data of components and maintenance experience.

• Journal of Wind Energy
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• v.9 no.4
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• pp.5-8
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• 2018

Optimum performance and reliable operation of wind turbines and/or wind farms are crucial parameters for stakeholders such as OEMs, operators, owners and investors. The efficiency and life time of wind power heavily depends on operation and maintenance efforts. Every manufacturer or owner wants to have wind turbines with high reliability, which can be defined as the probability that a wind turbine will perform its designed function for a certain period of time under stated conditions. In this regard, IEC WG26 is now developing a technical specification defining information categories from which reliability metrics can be identified and reported.