• Journal of the Korean Institute of Gas
• /
• v.17 no.4
• /
• pp.39-44
• /
• 2013

There have been large explosions at some chemical plants recently. Accidents in chemical plants have been caused mainly by servicing for maintenance. There is a need to find a key target for effective injury prevention in maintenance. In this paper, facilities were selected as a key target and the risk priority numbers of the facilities were calculated in order to prioritize preventative measures. The research method was based on the followings; the list of the facilities is found through injury analysis. Then, the risk of each facility was calculated by the frequency of accidents and the working day loss through injuries. In addition, the risk of the facilities was calculated again by the frequency and the severity based on knowledge and experience of experts. As a result, the facilities in chemical plant maintenance are ranked in order of high to low risk priority number; reactor, dryer, tank lorry, etc. In the future, special measures and attention should be directed according to the risk priority number during the maintenance of chemical plants.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.10
• /
• pp.44-51
• /
• 2012

The purpose of this study is development of the diagnosis system to preventative maintenance in the on-board measuring systems for in-cab electric inspection systems of high speed railway. The on-board measuring systems can inspect precisely whether ground signal system operate stably. In this paper, we recognize characteristics of the track circuits and confirm whether the wave of current matches the on-board measuring data through the electric modeling method for high speed railway. it is necessary to develop GUI visual programs that can simulate abnormalities of the on-board measuring data in many ways, and the visual program is designed to diagnosis in the case of track circuit equipment's function decreased in advance.

• Journal of mucopolysaccharidosis and rare diseases
• /
• v.5 no.1
• /
• pp.8-11
• /
• 2021

Glutaric aciduria type 1 (GA1; OMIM #231670) is a rare autosomal recessive-inherited neurometabolic disorder caused by the deficiency of glutaryl-CoA dehydrogenase (GCDH), which is encoded by the GCDH gene. It results in the accumulation of glutaric acid (GA), 3-hydroxyglutaric acid (3-OH-GA), glutaconic acid, and glutarylcarnitine (C5DC). These metabolites are considered to damage the striatum through an excitotoxic mechanism. The treatments of GA1 known to date are metabolic maintenance treatment based on a low-lysine diet and emergency treatment during acute illness. However, treatment after the onset of neurological symptoms has limited effectiveness and is associated with poor outcomes, and the effect of treatment and disease course after treatment are not good. After the implementation of newborn screening, the incidence of acute encephalopathic crisis fell to 10%-20% with early diagnosis, preventative dietary management, and aggressive medical intervention during acute episodes. Recently, several cohort studies have been published on the natural course and treatment of GA1 patients. This mini review will cover the clinical symptoms, natural history, and treatment of GA1 through a literature review.

• 한국체육학회지인문사회과학편
• /
• v.55 no.1
• /
• pp.221-233
• /
• 2016

The purpose of this study was to prove a development and initial validation of the korean version of coach-athlete relationship maintenance scale that originated from the work of Rhind & Jowett(2012) in pro baseball. The items were then administered to 132 Participants(29 coaches and 103 athletes) completed the questionnaires of the coach-athlete relationship maintenance in First preliminary investigation. Maximum likelihood estimate was used to identify the latent underlying structure. In order to verify the validity of Korean version of coach-athlete relationship maintenance was administered to an independent sample of 273 coaches and athletes. Pro baseball coach-athlete relationship maintenance is consisted of six factors(25 items) with conflict management, motivational, preventative, openness/assurance, support, and social network. SPSS18.0 and AMOS16.0 were used to analyze the exploratory factor analysis, confirmatory factory analysis and internal consistency, test-retest with bootstrapping using of the data in this study. The results of the pro baseball coach-athlete relationship maintenance scale had six factors with 25 items, and each six factor was positively correlated. Overall, this study verified pro baseball coach-athlete relationship maintenance questionnaire. Thus, suggest that path of comparing the differences between the first division and farm team by using the test of the structural model invariance across the groups.

• Korean Journal of Construction Engineering and Management
• /
• v.19 no.5
• /
• pp.53-60
• /
• 2018

In particular, the investigation of tendons in PSC Box Girder Bridge should be done in a systematic way. It is important to identify preventative maintenance activities that should be carried out in order to analyze the risk factors by type of representative tensions and to reduce risks in the long term. However, in the current maintenance system, various methodologies for investigating and repairing tensions have been studied, but it is difficult to investigate precisely tensions. Therefore, to apply the risk assessment for screening of tensions to the domestic PSC Box Bridge, we presented a risk matrix evaluation index that is consistent with the state assessment and maintenance system.

• Korean Journal of Construction Engineering and Management
• /
• v.21 no.6
• /
• pp.46-55
• /
• 2020

The maintenance cost for highway pavement is gradually increasing due to the continuous increase in road extension as well as increase in the number of old routes that have passed the public period. As a result, there is a need for a method of minimizing costs through preventative grievance Preventive maintenance requires the establishment of a strategic plan through accurate prediction old Highway pavement. herefore, in this study, the XGBoost among machine learning classification-based models was used to develop a highway pavement damage prediction model. First, we solved the imbalanced data issue through data sampling, then developed a predictive model using the XGBoost. This predictive model was evaluated through performance indicators such as accuracy and F1 score. As a result, the over-sampling method showed the best performance result. On the other hand, the main variables affecting road damage were calculated in the order of the number of years of service, ESAL, and the number of days below the minimum temperature -2 degrees Celsius. If the performance of the prediction model is improved through more data accumulation and detailed data pre-processing in the future, it is expected that more accurate prediction of maintenance-required sections will be possible. In addition, it is expected to be used as important basic information for estimating the highway pavement maintenance budget in the future.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.222-222
• /
• 2012

최근 반도체 시장의 300 mm/450 mm wafer 급 이상의 첨단공정에서는 진공 펌프의 대용량화 및 에너지 절감을 위한 저소비 전력화 요구와 함께 공정 중 진공 펌프의 성능저하 및 이상 징후 발생 감지 혹은 예지 요구 및 예지 보수 기술이 높아지고 있는 추세이다. 이에 현재 경험에 의존하던 진공 펌프의 predictive and preventative maintenance (PPM) 주기 설정 기술이 매우 필요함을 알 수 있다. 본 연구에서는 지식경제부에서 지원하는 산업원천기술개발사업에 참여기관으로 수행하면서 한국표준과학연구원에서 주관기관으로 진행하는 스마트형 진공 배기 진단 제어 시스템 개발 과제를 통해 (유)우성진공에서 자체 개발하는 저진공 펌프에 적용 예정중인 smart형 PMS에 대해 소개하고자 한다. 진공 환경을 조성하는 핵심장치인 진공 펌프 상태는 진공 공정 환경 조성에 가장 주요한 변수이므로 이에 따른 상태 진단 기술은 진공 공정 제어 정밀도와 공정 신뢰성 확보에 필수적이며, (유)우성진공에서 자체 개발하는 드라이펌프 및 스크류펌프 등 저진공 펌프의 정밀한 실시간 상태진단을 통해 예지 보수 기술 및 신뢰성을 확보하고자 한다.

• Structural Monitoring and Maintenance
• /
• v.2 no.2
• /
• pp.145-164
• /
• 2015

Bridge scour is the predominant cause of overwater bridge failures in North America and around the world. Several sensing systems have been developed over the years to detect the extent of scour so that preventative actions can be performed in a timely manner. These sensing systems have drawbacks, such as signal inaccuracy and discontinuity, installation difficulty, and high cost. Therefore, attempts to develop more efficient monitoring schemes continue. In this study, the viability of using optical dissolved oxygen (DO) probes for monitoring scour depths was explored. DO levels are very low in streambed sediments, as compared to the standard level of oxygen in flowing water. Therefore, scour depths can be determined by installing sensors to monitor DO levels at various depths along the buried length of a bridge pier or abutment. The measured DO is negligible when a sensor is buried but would increase significantly once scour occurs and exposes the sensor to flowing water. A set of experiments was conducted in which four dissolved oxygen probes were embedded at different soil depths in the vicinity of a mock bridge pier inside a laboratory flume simulating scour conditions. The results confirmed that DO levels jumped drastically when sensors became exposed during scour hole evolution, thereby providing discrete measurements of the maximum scour depth. Moreover, the DO probes could detect any subsequent refilling of the scour hole through the deposition of sediments. The effect of soil permeability on the sensing response time was also investigated.

• Journal of Korean society of Dental Hygiene
• /
• v.18 no.6
• /
• pp.957-967
• /
• 2018

Objectives: The aim of this study was to confirm health behaviors that affect periodontal health status. Based on these results, we also intended to provide information for the prevention of gingivitis prior to periodontitis and establish strategies for maintaining healthy periodontal tissues. Methods: Data for this descriptive study were extracted from the Korea National Health and Nutrition Examination Survey 2013-2015. A total of 2,710 adults, aged 19-39 years were included in this study. Complex logistic regression analyses were performed to confirm relationships between health behaviors and periodontal health, after adjusting for socio-demographics, oral and systemic health status. Results: Dental clinic visits (odd ratio [OR] = 1.761, 95% confidence interval [CI]; 1.391-2.229), use of floss (OR = 1.504, 95% CI; 1.213-1.865), and non-smoking (OR = 1.269, 95% CI; 1.040-1.549) were found to support periodontal health. Conclusions: Dental visits for continued professional oral health care, self-oral care including interdental flossing, and a non-smoking habit, are necessary for periodontal health maintenance. Additionally, the results suggest that physical activities such as regular walking can help. These methods should be considered as the primary preventative care strategies for minimizing the occurrence of gingival inflammation.

• Korean Journal of Construction Engineering and Management
• /
• v.20 no.6
• /
• pp.34-43
• /
• 2019

The maintenance cost for road pavement is gradually increasing due to the continuous increase in road extension as well as increase in the number of old routes that have passed the public period. As a result, there is a need for a method of minimizing costs through preventative grievance preventive maintenance requires the establishment of a strategic plan through accurate prediction of road pavement. Hence, In this study, the deep neural network(DNN) and the recurrent neural network(RNN) were used in order to develop the expressway pavement damage prediction model. A superior model among these two network models was then suggested by comparing and analyzing their performance. In order to solve the RNN's vanishing gradient problem, the LSTM (Long short-term memory) circuits which are a more complicated form of the RNN structure were used. The learning result showed that the RMSE value of the RNN-LSTM model was 0.102 which was lower than the RMSE value of the DNN model, indicating that the performance of the RNN-LSTM model was superior. In addition, high accuracy of the RNN-LSTM model was verified through the comparison between the estimated average road pavement condition and the actually measured road pavement condition of the target section over time.