• 한국신뢰성학회지:신뢰성응용연구
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• 제17권3호
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• pp.236-245
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• 2017

Purpose: There is no established inspection system for composite wind blade during the fabrication stage even though the blades are one of the most important part at wind generation system, but phased array ultrasonic testing method has been continuously studied about wind turbine blade with composite. When wind turbine blade with complex shape by phased array probe is inspected, it is necessary to study for system keeping constant pressure using pressure device. Methods: In this paper, we propose constant pressure device for inspecting wind turbine blade by phased array ultrasonic test method. Design of the device controller is based on Hunt-Crossley model. We evaluate reliability of phased array ultrasonic inspection result that applicated constant pressure device. Result: Defect indication is precise and its error is small when constant pressure mechanism based on Hunt-Crossley model was used. Conclusion: When inspection is progressed using constant pressure mechanism, the reliability of composite wind blade inspection can be improved.

• 터널과지하공간
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• 제7권3호
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• pp.230-237
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• 1997

As concrete structure is getting old and decrepit, its inspection and diagnosis is getting important. Therefore, it is necessary to estimate the soundness of structure using non-destructive tests for effective repairs and maintenances. But, applications of non-destructive tests in tunnel have been used restrictively, due to accessibility only from one side in tunnel lining and presence of tunnel installations. Recently, the various non-destructive techniques have been studied. Especially, ground penetrating radar(GPR) and impact echo (IE) methods have been researched for tunnel inspection. In this study, the applicability of impact echo test in tunnel lining inspection has been investigated. This paper described the tunnel inspection for lining thickness and internal flaw using impact echo tests. Model tests were carried out using impact echo test systems on two concrete models, Model I is measuring for lining thickness, Model II is detecting for internal flaw. Also, the test were applied for lining inspections in a tunnel constructed by NATM. From the results of impact echo tests, we have concluded that impact echo test is a very useful and effective technique for inspecting the concrete tunnel linings.

• Journal of information and communication convergence engineering
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• 제21권2호
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• pp.130-138
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• 2023

The selection of the correct examination variables for diagnosing heart disease provides many benefits, including faster diagnosis and lower cost of examination. The selection of inspection variables can be performed by referring to the data of previous examination results so that future investigations can be carried out by referring to these selected variables. This paper proposes a model for selecting examination variables using an Artificial Bee Swarm Optimization method by considering the variables of accuracy and cost of inspection. The proposed feature selection model was evaluated using the performance parameters of accuracy, area under curve (AUC), number of variables, and inspection cost. The test results show that the proposed model can produce 24 examination variables and provide 95.16% accuracy and 97.61% AUC. These results indicate a significant decrease in the number of inspection variables and inspection costs while maintaining performance in the excellent category.

• 산업경영시스템학회지
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• 제18권34호
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• pp.185-191
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• 1995

In this research, a mathematical programming model is developed for the economic modeling of sampling plans based on two evaluation criteria : the outgoing quality and the average total inspection cost A fuzzy goal programming model and its solution procedure are proposed for the managers whose management objectives on the two evaluation criteria are not rigorous. To study the sensitivity of quality characteristic dependence on the resulting inspection plans, a numerical example is solved several times for a dependent model.

• 대한안전경영과학회지
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• 제26권2호
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• pp.23-31
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• 2024

In the military, ammunition and explosives stored and managed can cause serious damage if mishandled, thus securing safety through the utilization of ammunition reliability data is necessary. In this study, exploratory data analysis of ammunition inspection records data is conducted to extract reliability information of stored ammunition and to predict the ammunition condition code, which represents the lifespan information of the ammunition. This study consists of three stages: ammunition inspection record data collection and preprocessing, exploratory data analysis, and classification of ammunition condition codes. For the classification of ammunition condition codes, five models based on boosting algorithms are employed (AdaBoost, GBM, XGBoost, LightGBM, CatBoost). The most superior model is selected based on the performance metrics of the model, including Accuracy, Precision, Recall, and F1-score. The ammunition in this study was primarily produced from the 1980s to the 1990s, with a trend of increased inspection volume in the early stages of production and around 30 years after production. Pre-issue inspections (PII) were predominantly conducted, and there was a tendency for the grade of ammunition condition codes to decrease as the storage period increased. The classification of ammunition condition codes showed that the CatBoost model exhibited the most superior performance, with an Accuracy of 93% and an F1-score of 93%. This study emphasizes the safety and reliability of ammunition and proposes a model for classifying ammunition condition codes by analyzing ammunition inspection record data. This model can serve as a tool to assist ammunition inspectors and is expected to enhance not only the safety of ammunition but also the efficiency of ammunition storage management.

• Journal of Ship and Ocean Technology
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• 제2권1호
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• pp.42-57
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• 1998

Genetic Algorithm (GA) is applied to obtain optimal Inspection plan for fatigue deteriorating structures. The optimization problem is defined so as to minimize inspection cost in the 1ifs-time of the structure under the constraint that the increment of failure probability in each inspection interval is maintained below a target value. Optimization parameters are the inspection timing and the inspection quality. The inspection timing is selected from the discrete intervals such as one year, two years, three years, etc. The inspection quality is selected from the followings; no inspection, normal inspection, sampling inspection or precise inspection. The applicability of the proposed GA approach is demonstrated through the numerical calculations assuming a structure consisting of four member sets. Influences of the level of target failure probability, initial defect condition and stress increase due to plate thickness reduction caused by corrosion on inspection planning are discussed.

• 한국산학기술학회논문지
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• 제13권6호
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• pp.2452-2457
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• 2012

산업현장에서는 품질검사 과정 중의 잘못된 불량판정을 감소시키기 위하여, 각 제품단위에 대하여 불량판정이 나왔을 경우 복수의 검사를 반복하여 수행하는 경우가 있다. 본 논문은 총 두 번까지의 연속된 검사를 허용하는 품질검사 프로세스에 대한 분석을 다루고 있다. 본 논문에서는 제품검사의 단계와 품질판정 상태를 모델링하는 수학적 도구로서 마르코프 체인이 사용되었다. 그리고 산업체의 생산관리 시스템에서 수집된 불량 판정률을 마르코프 체인 모델의 데이터로 사용하였다. 또한 본 논문은 제품의 품질 특성 별 최종 비율과 제품의 폐기율에 대한 이러한 연속적인 이중검사 허용 프로세스의 영향에 대하여 분석을 수행하였다. 분석 결과, 연속이중검사 허용이 정상 제품에 대한 불량판정을 줄이며, 그 결과 재료, 노동 및 기타 비용을 줄이는 데 기여할 수 있다는 것을 확인하였다

• 산업경영시스템학회지
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• 제40권4호
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• pp.96-104
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• 2017

A one-shot system (device) refers to a system that is stored for a long period of time and is then disposed of after a single mission because it is accompanied by a chemical reaction or physical destruction when it operates, such as shells, munitions in a defense weapon system and automobile airbags. Because these systems are primarily related with safety and life, it is required to maintain a high level of storage reliability. Storage reliability is the probability that the system will operate at a particular point in time after storage. Since the stored one-shot system can be confirmed only through inspection, periodic inspection and maintenance should be performed to maintain a high level of storage reliability. Since the one-shot system is characterized by a large loss in the event of a failure, it is necessary to determine an appropriate inspection period to maintain the storage reliability above the reliability goal. In this study, we propose an optimal inspection policy that minimizes the total cost while exceeding the reliability goal that the storage reliability is set in advance for the one-shot system in which periodic inspections are performed. We assume that the failure time is the Weibull distribution. And the cost model is presented considering the existing storage reliability model by Martinez and Kim et al. The cost components to be included in the cost model are the cost of inspection $c_1$, the cost of loss per unit time between failure and detection $c_2$, the cost of minimum repair of the detected breakdown of units $c_3$, and the overhaul cost $c_4$ of $R_s{\leq}R_g$. And in this paper, we will determine the optimal inspection policy to find the inspection period and number of tests that minimize the expected cost per unit time from the finite lifetime to the overhaul. Compare them through numerical examples.

• 상하수도학회지
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• 제38권2호
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• pp.83-93
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• 2024

In this study, we present a sewer pipe inspection technique through a combination of active sonar technology and deep learning algorithms. It is difficult to inspect pipes containing water using conventional CCTV inspection methods, and there are various limitations, so a new approach is needed. In this paper, we introduce a inspection method using active sonar, and apply an auto encoder deep learning model to process sonar data to distinguish between normal and abnormal pipelines. This model underwent training on sonar data from a controlled environment under the assumption of normal pipeline conditions and utilized anomaly detection techniques to identify deviations from established standards. This approach presents a new perspective in pipeline inspection, promising to reduce the time and resources required for sewer system management and to enhance the reliability of pipeline inspections.

• 한국전산구조공학회논문집
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• 제33권6호
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• pp.411-417
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• 2020

Building Information Modeling(BIM)기술을 유지관리 단계에서 활용하기 위해서는 상당량의 유지관리 데이터와 BIM기반 정보모델 객체들이 연계되어 운용되어야 한다. 본 연구에서는 교량 점검데이터를 표현하기 위해 확장된 IFC기반의 BIM모델과 온톨로지를 연계하여 정보를 관리하는 방법을 제시하였다. 이를 위해 현재의 IFC버전은 교량 객체를 제대로 표현할 수 없기 때문에 교량을 위한 IFC엔티티를 확장하였으며, 확장된 IFC기반의 정보모델을 생성하는 방법을 제시하였다. 또한, 교량 점검데이터에 대한 기본 개념을 추출하고, 교량 점검데이터를 위한 온톨로지(Ontology)를 생성하였다. 추출된 기본 개념들은 제시된 온톨로지에서 시멘틱 웹의 트리플(Triple) 방식으로 관계를 형성되었다. 마지막으로, 생성된 IFC기반의 BIM모델은 제시된 온톨로지와의 통합을 위하여 시멘틱 데이터 형식으로 변환되었다. 확장된 IFC기반 BIM모델은 제시된 교량 점검데이터 관리를 위한 온톨로지와 통합되었고, 실제 교량 점검데이터를 기반으로 테스트모델을 생성하였다. SPARQL query를 통해 목적에 맞는 교량 점검데이터가 추출됨을 확인하여 실효성을 검증하였다.