• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.89-94
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• 2021

Recently, manufacturing companies are introducing many intelligent production processes that apply IIoT/ICT to improve competitiveness, and a system that maintains availability, improves productivity, and optimizes management costs is needed as a preventive measure using environmental data generated from air ejectors. Therefore, in this study, a dedicated control board was developed and LoRa communication module was applied to remotely control it to collect and manage information about compressors from cloud servers and to ensure that all operators and administrators utilize common data in real time. This dramatically reduced M/S steps, increased system operational availability, and reduced local server operational burden. It dramatically reduced maintenance latency by sharing system failure conditions and dramatically improved cost and space problems by providing real-time status detection through wired and mobile utilization by maintenance personnel.

• Journal of Korean Society of Forest Science
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• v.105 no.4
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• pp.449-455
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• 2016

This study was conducted to provide the basic policy information for systematic forest road planning and maintenance management by surveying two different administrator groups. The survey results showed that the high priorities of forest road planning were silviculture, disaster prevention, and timber harvesting, and main forest road type was preferred for future use. Also 92.9% of the respondents expressed difficulties due to insufficient manpower and budget. The expected damage types due to forest road construction were threat-to-life by slope failure and dispute on crossing private land. The current main maintenance tasks on forest roads included drainage and road surface maintenance works. Main forest road facilities that should be needed after the construction were installation of additional drainage structures, and slope revegetation and stabilization.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.2
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• pp.79-88
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• 2014

In Republic of Korea, there are considerable vulnerability in electrical stimulating swallowing-assist equipments even though they are professional medical equipments and have high penetration rate with heavy frequency of use. Therefore, in this article, we developed Device Management and Safety Diagnosis Manual for Electrical Stimulating Swallowing-Assist Equipments system. For achieving this, we collected and analysed international standard data from international organizations like International Electrotechnical Commission(IEC). After literature reviews, we build maintenance worksheet and equipment procedure manual for electrical stimulating swallowing-assist equipments according to evidences we collected. These manual and protocol would be used as standard process and contribute to sustain accuracy, effectiveness of the devices, also decrease failure rate and assist to save medical documents.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.4
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• pp.179-188
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• 2011

This paper outlines a systematic guideline for remanufacturing process using the Failure Mode and Effect Analysis (FMEA) method in order to estimate the reliability and quality of the remanufactured alternator. The method is just a tool to help, but the remanufacturer must determine the optimal remanufacturing process and specific inspection and production that will turn the alternator as-good-as new and place the product into the market with reliability and quality equal to a new product. FMEA is a method that is widely used in industry and has shown its value and effectiveness in the above remanufacturing case study. Actions taken often result in a lower severity, occurrence or detection rating. Redesign may result in lower severity and occurrence ratings while inserting validation controls and maintenance can reduce the detection rating. The revised ratings are recorded with the originals on the FMEA template form. After these corrective actions and revisions have been established, evaluation of the ranks can be repeated, until the redesign and control parameters comply with safety standards.

• Journal of Chest Surgery
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• v.27 no.8
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• pp.669-676
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• 1994

Because the number of patients who require maintenance hemodialysis is increasing in number recently, angioaccess has become important to many vascular surgeons participating in the management of such patients.The authors created 269 arteriovenous fistulas[AVF] for angioaccess in 229 patients with chronic renal failure[CRF] at the Department of Thoracic and Cardiovascular Surgery in Chungnam National University Hospital during the period from August 1990 to March 1993. We analyzed the results of 260 operations for 220 patients except 9 patients who were lost during the follow up period. We performed snuffbox AVF in 171 cases, classic radiocephalic AVF in 46 cases, direct AVF at other site in 5 cases, forearm Gore-Tex AVF in 29 cases, and upper arm Gore-Tex AVF in 9 cases. We experienced 13 cases of operative failures, 11 cases of early complications, and 60 cases of late complications including obstructions during follow-up period. The 1 year, 2 year and 3 year patency rates of snuffbox AVF[Group 1], classic radiocephalic AVF[Group 2], and Gore-Tex AVF[Group 3] are like followings; 89, 84, 76% in group 1, 84, 75, 68% in group 2, and 79, 66, 55% in group 3. It showed a statistically significant difference between group 1, 2 and group 3.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.5
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• pp.343-350
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• 2016

Remaining lifetime prediction of the underground gas pipeline plays a key role in maintenance planning and public safety. One of main causes in the pipeline failure is metal corrosion. This paper deals with estimating the pipeline reliability in the presence of corrosion defects. Because a pipeline has uncertainty and variability in its operation, probabilistic approximation approaches such as first order second moment (FOSM), first order reliability method (FORM), second order reliability method (SORM), and Monte Carlo simulation (MCS) are widely employed for pipeline reliability predictions. This paper presents a fuzzy inference based reliability method (FIRM). Compared with existing methods, a distinction of our method is to incorporate a fuzzy inference into quantifying degrees of variability in corrosion defects. As metal corrosion depends on the service environment, this feature makes it easier to obtain practical predictions. Numerical experiments are conducted by using a field dataset. The result indicates that the proposed method works well and, in particular, it provides more advisory estimations of the remaining lifetime of the gas pipeline.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.629-633
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• 2011

Recently, systems such as aircraft, trains and ships have become larger more complex. Therefore, the reliability calculation of these systems is more difficult. This paper presents a reliability calculation algorithm for a complex system with a solution that is difficult to analyze. When the system has a very complex structure, it is very difficult to find an analytical solution. In this case, we can assess system reliability using the failure enumeration method of the reliability path. In this research, we represent the reliability block diagram by an adjacent matrix and define the reliability path. We can find any system status by the failure enumeration of the reliability path, and thus we can calculate any kind of system reliability through this process. This result can be applied to RCM (Reliability-Centered Maintenance) and reliability information-management systems, in which the system reliability is composed of the reliabilities of individual parts.

• Journal of Korean Society for Quality Management
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• v.51 no.2
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• pp.297-313
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• 2023

Purpose: The purpose of this study is to investigate the causes of shifting errors reported in military tracked vehicles and to improve related quality to prevent recurrence. Methods: A systematic disassembly and inspection of the transmission is carried out and an experimental simulation is conducted to reproduce the shifting error phenomenon. Electrical characteristic tests are subsequently performed and microscopic observation is also carried out on the disassembled connector parts such as pins and fractured surfaces. Results: Oil contamination and swelling deformation are observed in the connector to the vehicle due to oil leakage of its counterpart connector to the transmission. This causes electrical contact failure between both connectors in the fastened state, and it is found that shifting error of the tracked vehicle could occur subsequently. To prevent the recurrence of this phenomenon, comprehensive quality improvement is conducted including product improvement of the wiring harness assembly and strengthening activities for quality control and preventive maintenance. Conclusion: This study is expected to be helpful as a prior case study for cause analysis and recurrence prevention in the event of similar cases in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1903-1910
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• 2009

In this paper, we were researched decision problem called an optimal release policies after testing a software system in development phase and transferring it to the user. The applied model of release time exploited infinite failure non-homogeneous Poisson process This infinite failure non-homogeneous Poisson process is a model which reflects the possibility of introducing new faults when correcting or modifying the software. The failure life-cycle distribution used the Weibull distribution which has the efficient various property which has the place efficient quality. Thus, optimal software release policies which minimize a total average software cost of development and maintenance under the constraint of satisfying a software reliability requirement becomes an optimal release policies. In a numerical example, after trend test applied and estimated the parameters using maximum likelihood estimation of inter-failure time data, estimated software optimal release time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.190-196
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• 2020

FRACAS(Failure Reporting, Analysis and Corrective Action System) has been applied in various industries to improve the reliability of the systems. FRACAS is effective in improving reliability by repeating failure analysis, proper corrective action, and result verification for identified failures. However, FRACAS has many limitations in terms of process, data collection and management to be integrated into the existing development environment. In the domestic defense industry, studies on the development of FRACAS system and process improvement have been conducted to solve the difficulties of applying FRACAS, but most of them are concentrated in the operation/maintenance phase. Since FRACAS should be conducted in consideration of TLCSM(Total Life Cycle System Management), it is necessary to study the reference architecture so that FRACAS can be applied from the early design phase. In this paper, we studied the TLCSM-based integrated architecture considering the system life cycle phases, FRACAS closed-loop process, and FRACAS essentials in order to effectively apply FRACAS throughout the life cycle of defense systems. The proposed architecture was used as a reference model for FRACAS in a shipboard combat system.