• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2174-2181
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• 2004

The metal processing system usually consists of various components such as motors, work rolls, backup rolls, idle rolls, sensors, etc. Even a simple fault in a single component in the system may cause a serious damage on the final product. It is, therefore, necessary to diagnose the faults of the components to detect and prevent a system failure. Especially, the defects in a work roll are critical to the quality of strip. In this study, a new 3-D diagnosis method was developed for roll shape defects in rolling processes. The new method was induced from analyzing the rolling mechanism by using a rolling force model, a tension model, the Hitchcock's equation, and measurement of the strip thickness, etc. Computer simulation shows that the proposed method is very useful in the diagnosis of the 3-D roll shape.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.169-174
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• 2012

Reduction unit is one of the most important components for railway vehicle because torque of motor must be transmitted to wheels of vehicle by reduction unit. However, According to advanced studies, it has been often broke down due to the damage, fatigue and wear of gear. To solve this problem, defect diagnosis methods of gear have been mainly using the vibration diagnosis technology through vibration waveform and frequency analysis. However, We should know vibration characteristics of normal state reduction unit prior to defect diagnosis. So in this paper, We had analyzed vibration characteristics of reduction unit in order to utilize monitoring system development. Comparison of targets is the vibration characteristics of normal state reduction unit about Electric Multiple Unit(EMU) and the High-speed trains(KTX, KTX II).

• Journal of Yeungnam Medical Science
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• 제36권1호
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• pp.8-15
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• 2019

Connective tissue diseases (CTDs) can affect all compartments of the lungs, including airways, alveoli, interstitium, vessels, and pleura. CTD-associated lung diseases (CTD-LDs) may present as diffuse lung disease or as focal lesions, and there is significant heterogeneity between the individual CTDs in their clinical and pathological manifestations. CTD-LDs may presage the clinical diagnosis a primary CTD, or it may develop in the context of an established CTD diagnosis. CTD-LDs reveal acute, chronic or mixed pattern of lung and pleural manifestations. Histopathological findings of diverse morphological changes can be present in CTD-LDs airway lesions (chronic bronchitis/bronchiolitis, follicular bronchiolitis, etc.), interstitial lung diseases (nonspecific interstitial pneumonia/fibrosis, usual interstitial pneumonia, lymphocytic interstitial pneumonia, diffuse alveolar damage, and organizing pneumonia), pleural changes (acute fibrinous or chronic fibrous pleuritis), and vascular changes (vasculitis, capillaritis, pulmonary hemorrhage, etc.). CTD patients can be exposed to various infectious diseases when taking immunosuppressive drugs. Histopathological patterns of CTD-LDs are generally nonspecific, and other diseases that can cause similar lesions in the lungs must be considered before the diagnosis of CTD-LDs. A multidisciplinary team involving pathologists, clinicians, and radiologists can adequately make a proper diagnosis of CTD-LDs.

• 드라이브 ㆍ 컨트롤
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• 제20권4호
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• pp.54-63
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• 2023

High and intermittent loading cycles induce fatigue damage to transmission components, resulting in premature gearbox failure. To identify gearbox defects, numerous vibration-based diagnostics techniques, using several artificial intelligence (AI) algorithms, have recently been presented. In this paper, an optimized deep belief network (DBN) model for gearbox problem diagnosis was designed based on time-frequency visual pattern identification. To optimize the hyperparameters of the model, a particle swarm optimization (PSO) approach was integrated into the DBN. The proposed model was tested on two gearbox datasets: a wind turbine gearbox and an experimental gearbox. The optimized DBN model demonstrated strong and robust performance in classification accuracy. In addition, the accuracy of the generated datasets was compared using traditional ML and DL algorithms. Furthermore, the proposed model was evaluated on different partitions of the dataset. The results showed that, even with a small amount of sample data, the optimized DBN model achieved high accuracy in diagnosis.

• Smart Structures and Systems
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• 제13권5호
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• pp.869-890
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• 2014

In this study, a damage detection approach using train-induced vibration response of the bridge is proposed, utilizing only direct structural analysis by means of introducing soft computing methods. In this approach, the possible damage patterns of the bridge are assumed according to theoretical and empirical considerations at first. Then, the running train-induced dynamic response of the bridge under a certain damage pattern is calculated employing a developed train-bridge interaction analysis program. When the calculated result is most identical to the recorded response, this damage pattern will be the solution. However, owing to the huge number of possible damage patterns, it is extremely time-consuming to calculate the bridge responses of all the cases and thus difficult to identify the exact solution quickly. Therefore, the soft computing methods are introduced to quickly solve the problem in this approach. The basic concept and process of the proposed approach are presented in this paper, and its feasibility is numerically investigated using two different train models and a simple girder bridge model.

• 한국환경과학회지
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• 제29권5호
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• pp.551-558
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• 2020

This study aims to increase the ability to adapt to the ecosystem and promote a sustainable use of the natural environment, by classifying the types of damaged lands according to various factors, such as the characteristics of the target area and form, cause, and impact of damage. Moreover, the study suggests the development of evaluation categories and criteria by each type. The results obtained are as follows: first, for the assessment of damaged lands, the changed areas were identified utilizing land cover maps. Video analysis was performed to increase the accuracy, and 88 sites were obtained. Second, the types of damage were classified into ecological infrastructure and ecological environment, and the sub-factors of the cause of damage were classified into 12 factors. Third, each evaluation system for the types of damage was composed of four steps, considering each type of damage and the level of evaluators being higher than paraprofessionals. To supplement this study, it will be necessary to utilize the database of damaged lands other than the Seoul Metropolitan Area and conduct an on-site survey for verification in the future.

• Smart Structures and Systems
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• 제5권4호
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• pp.427-442
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• 2009

In this paper, the acceptability of system identification results for health monitoring of instrumented bridges is addressed. This is conducted by comparing the confidence intervals of identified modal parameters for a bridge in California, namely Truckee I80/Truckee river bridge, with the change of these parameters caused by several damage scenarios. A challenge to the accuracy of the identified modal parameters involves consequences regarding the damage detection and health monitoring, as some of the identified modal information is essentially not useable for acquiring a reliable damage diagnosis of the bridge system. Use of strong motion data has limitations that should not be ignored. The results and conclusions underline these limitations while presenting the opportunities offered by system identification using strong motion data for better understanding and monitoring the health of bridge systems.

• 한국조경학회지
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• 제41권1호
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• pp.44-50
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• 2013

조경수 관리시 발생하는 병충해 등의 문제에 대한 자문을 받기 위하여 관리 담당자는 나무병원에 진단 및 처방을 의뢰하고 있는데, 본 연구는 국내에서 수목진단센터로 인증된 서울대학교 식물병원, 충북대학교 식물종합병원 및 강원대학교 수목진단센터의 온라인 상담게시판에 등록된 조경수 관련 질의와 답변을 검토하여 조경관리자 및 관계자들이 주로 질의하는 조경수 관리상의 문제와 의문이 무엇인지 분석하고자 하였다. 그 결과, 질의자 중에 조경관계자가 81.4%로 대다수를 차지했으나, 질의시 조경수 진단에 필수적인 수목관리 이력 및 주변환경 설명을 한 경우가 11.5%에 불과할 정도로 조경관계자들이 수목진단에 관한 기초적 지식이나 관심이 부족함을 확인하였다. 그리고 조경수 관련 질의 263건 중 생리피해 질의가 94건, 35.8%로 가장 많은 건수를 나타냈다. 이어서 충해, 병해 순이었다. 표징이 없고 다양한 스트레스에 의해 발생하는 생리적 문제의 특성상 진단 및 처방의뢰를 가장 많이 하게 되는 것으로 판단된다. 생리피해의 원인으로는 수분스트레스와 온도스트레스가 가장 많은 편이었으며, 병해는 그 병의 종류가 다양하였고, 생리적 원인이 수반되는 복합피해도 많은 편이었다. 충해는 나방류에 의한 경우가 가장 많았다. 이와 같은 결과를 고려할 때, 조경 기술자와 학생이 조경수 관리의 필수 지식과 정보를 습득하고 관심도를 고취할 수 있도록 대학이나 기술자 교육기관에서 조경수 관리교육을 반드시 실시하여야 하며, 특히 수목 생리에 대한 심도있는 학습 기회 제공과 기술자 스스로의 노력이 요구된다. 또한 조경업에 대한 이해와 조경식재 기술 및 현장의 실정을 이해하는 조경식재 및 관리에 대해 전문적으로 자문할 수 있는 기관의 구성이 이루어져야 한다. 그리고 아직 기반이 갖추어지지 않은 조경수 관리분야의 체계성과 전문성 도모를 위해 집중적인 기술자 육성과 학계와 업계 등 관계자들의 연구가 필요하다.

• Clinical and Experimental Pediatrics
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• 제53권11호
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• pp.931-935
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• 2010

Juvenile idiopathic arthritis (JIA) is comprised of a heterogeneous group of several disease subtypes that are characterized by the onset of arthritis before the age of 16 years and has symptoms lasting at least 6 weeks. The previous classification of JIA included seven different categories, whereas its current classification was compiled by the International League of the Association for Rheumatology, and replaced the previous terms of "juvenile chronic arthritis" and "juvenile rheumatoid arthritis," which were used in Europe or North America, respectively, with the single nomenclature of JIA. As mentioned above, JIA is defined as arthritis of unknown etiology that manifests itself before the age of 16 years and persists for at least 6 weeks, while excluding other known conditions. The clinical symptoms of JIA can be quite variable. Several symptoms that are characteristic of arthritis are not necessarily diagnostic of JIA and may have multiple etiologies that can be differentiated with careful examination of patient history. The disease may develop over days or sometimes weeks, thereby making the diagnosis difficult at the time of presentation. To make a clinical diagnosis of JIA, the first step is to exclude arthritis with known etiologies. Of note, late treatment due to excessive delay of diagnosis can cause severe damage to joints and other organs and impair skeletal maturation. Therefore, early detection of JIA is critical to ensure prompt treatment and to prevent long-term complications including the likelihood of disability in childhood.

• 한국방재학회 논문집
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• 제1권2호
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• pp.63-74
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• 2001

본 논문에서는 모의실험을 이용하여 진동감시를 통한 거대 구조물에서의 비파괴 손상탐지의 타당성을 입증하였다. 트러스 형식의 구조물에 대한 비파괴 손상탐지 이론을 정립하였다. 이 이론의 타당성 조사를 위하여 16개의 격간과 246개의 요소로 구성되어 있는 3차원 트러스 구조물을 유한요소로 모델링 하였으며, 이 모델을 이용하여 모의 손상을 가하였다. 손상의 경우는 총 4가지로 대상 구조물의 한 곳에서 손상이 발생한 경우부터 세 곳에서 손상이 발생한 경우까지를 고려하였다. 주어진 모달 매개변수를 이용하여 미세 손상 뿐 아니라 큰 손상에 대해서도 결과가 잘 일치함을 알 수 있었다.