• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.4
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• pp.109-115
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• 2005

In the study, Methods for operating measures in equipment security to find out dangerousness timely in the system and to need for the prevention and measures. The method for analyzing and reconstructing the causes of accident of equipment in site, and try to save the information of site in real-time and to analyze the state of equipment to look for the factors of accidents. By this analysis, one plan for efficiency of production, Equipment Fault Diagnosis Management and security is integrating and building module of using the Fuzzy Inference based on fuzzy theory. The case study is applied to the industrial electric motors that are necessarily used to all manufacturing equipment. Using the sensor for temperature is attached to gain the site information in real time and to design the hardware module for signal processing. In software, realize the system supervising and automatically saving to management data base by the algorithm based in fuzzy theory from the existing manual input system

• The Journal of Fisheries Business Administration
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• v.53 no.1
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• pp.73-84
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• 2022

The purpose of this study is the impact of national fishing port investment and typhoons on fisheries disaster damage. The dependent variables were the amount of damage to fishing ports, fishing boats, fisheries enhancement, external facilities, mooring facilities, functional facilities, fishing port and typhoons. The analysis period is from 2002 to 2018. Since the error term is in a simultaneous correlation, it was efficiently estimated by analyzing it with a seemingly unrelated regression (SUR) method. As a result of the analysis, external facilities have not significance to all models. Investing in mooring facilities increased the amount of damage to fishing ports for five years. Investing in functional facilities reduced the amount of damage to fishing ports and aquaculture over five years. Typhoons have significance to all models, and the amount of damage increased every time a typhoon occurred. Based on these results, as the influence of typhoons increases, it seems necessary to establish preventive measures. Timely investment and maintenance to enable the role and function of national fishing ports are considered important.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.539-542
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• 2003

A motor is the workhorse of our industry. The issues of preventive and condition-based maintenance, online monitoring, system fault detection, diagnosis, and prognosis are of increasing importance. Different internal motor faults (e.g., inter-turn short circuits, broken bearings, broken rotor bars) along with external motor faults (e.g., phase failure, mechanical overload, blocked rotor) are expected to happen sooner or later. This paper introduces the fault detection technique of induction motors based upon the stator current. The fault motors have rotor bar broken or rotor unbalance defect, respectively. The stator currents are measured by the current meters and stored by the time domain. The time domain is not suitable to represent the current signals, so the frequency domain is applied to display the signals. The Fourier Transformer is used for the conversion of the signal. After the conversion of the signals, the features of the signals have to be extracted by the signal processing methods like a wavelet analysis, a spectrum analysis, etc. The discovered features are entered to the pattern classification model such as a neural network model, a polynomial neural network, a fuzzy inference model, etc. This paper describes the fault detection results that use wavelet decomposition. The wavelet analysis is very useful method for the time and frequency domain each. Also it is powerful method to detect the features in the signals.

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.92-98
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• 2021

The noise management in the interior of the power plant is difficult because the interior is large and the noise level varies greatly from location to location. Therefore, a noise visualization system capable of analyzing the noise distribution is required in order to effectively manage the interior noise. A noise mapping system was developed that can model the inside of the turbine room and create a noise map by measuring the noise level at selected points. And in order to increase the reliability of the model, the model was modified through a method of comparing the noise map and the actual noise measurement results. Facility abnormalities can be determined through regular analysis of noise maps, and a method of effectively managing the interior noise is presented by comparing and analyzing the frequencies and levels of the current and previous noise at a specific point. By using the mapping system, it is possible to establish noise countermeasures that can improve the working environment, check the machine for abnormalities, and increase the reliability of the facility through preventive maintenance.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.291-299
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• 2011

Purpose: This study was designed to measure patient satisfaction and oral health-related quality of life and to assess an association between patients' satisfaction and oral health-related quality of life after implant surgery by using structural equation modeling. Materials and methods: A total of 257 participants who visited 6 dental clinics located in Daegu city for the purpose of implant treatment participated in this study. Six months after completion of implant surgery, the patients' satisfaction and oral health-related quality of life were surveyed. The effect of factors associated with patients' satisfaction such as functions and aesthetics, maintenance and cost on oral health-related quality of life after implant surgery was analyzed using AMOS 4.0. Results: Oral health-related quality of life was improved in all dimensions of OHIP-14 after implant surgery. Functions and aesthetics as well as maintenance had a significant effect on oral health-related quality of life (P<.05), while cost was not a critical factor influencing oral health-related quality of life. Conclusion: High satisfaction with functional aspects and maintenance aspects significantly affected good quality of life. The result of this study supported the fact that education and management for patients after implant therapy were positively related to good quality of life based on a theoretical model.

• Korean Journal of Occupational Health Nursing
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• v.11 no.2
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• pp.108-120
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• 2002

This study analyzed the managerial efficiency of 11 organizations, the branch centers of a occupational health service organization in Korea, using the Data Envelopment Analysis (DEA) method. The DEA is a good method for evaluating health services since it can handle multiple inputs and outputs simultaneously, and also identify the sources and amount of inefficiency. The author approached this study using two efficient models: the monetary value model and the real value model. The DEA method based on the monetary value model included cost factors, while the real value model excluded cost factors. The input variables used were manpower of physicians, medical technicians, nurses, industrial hygienists and administrators; labor, maintenance, and material expenses. The output variables used were the number of medical examinations, workplace evaluations, group health management services and income from each service. The major results were as follows: First, in the monetary value model, 6 out of 11 organizations (54.6%) showed an efficiency score of 1.0, which means that they have been operating in very efficient ways. However, 5 organizations (46.4%) showed themselves to be relatively inefficient. Second, in the real value model, 7 out of 11 organizations (63.4%) showed an efficiency score of 1.0, which means they have been operating efficiently, while 4 organizations (46.4%) showed themselves to be relatively inefficient. Third, the reliability of DEA method were analyzed by comparing the results of the monetary value model and real value model. The results of 8 out of 11 organizations were same in terms of being efficient or not. Thus, the DEA could be a valid application method for occupational health service organizations. Fourth, the organizations that displayed common inefficiency in both the monetary value model and in the real value model 3, 9, and 10, were also considered to be managed inefficiency from expertise opinion. In summary, this study evaluated the efficiency of occupational health service organizations applying the DEA method with different variables, and found that the results of analysis could be valid in terms of both modeling and expert sense. In the future, the DEA method will be used as a useful tool to identify and evaluate the efficiency of occupational health service organizations through more applications and refinements.

• Journal of the Korean Society of School Health
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• v.15 no.2
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• pp.205-218
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• 2002

Objectives : Because elementary school children are sensitive and prevalent to dental caries, oral health care program for the elementary school children (ESOHCP) should be met the first priority for the national oral health care program. This study was performed to proposed the guidelines for executing the efficient ESOHCP through the evaluation of present oral health care and education status based on the attitudes and opinions of health teachers. Methods : Subjects were 181 health teachers those are a part of the total 273 elementary school health teachers in Busan. From April to June 2001, questionnaire survey on the teacher's attitude and opinion, present status of oral health care and education in their own school was done. Data was analyzed by $\chi^2$-test, t-test, ANOVA using SAS (ver 6.21) program. Results : Mean age of the teachers was 40 years (24~58 years) and mean scale of the subject school was 32 classes (5~58 classes). Above 90% of them agreed with the necessity and importance of ESOHCP, but actual level of concerning was lower. They gained the informations about oral health mainly from media (33%), PC net (26%), academic society (25%), and more used internet (p=0.012) in younger generation. Though most of them (96%) had a specified school dentist, only 58% had the experience of periodic oral health examinations in their own school. The major experienced ESOHCP was fluoride brushing and contest to choose the best healthy teeth. Oral health education given by the teachers was not professional but their own. About half (42%) of the teachers had never taken education during last one year. Major education materials were VTR tape (79%), teeth model (64%), CD (55%), booklet (50%), etc., and the teachers' preference was also VTR tape (43%) and CD (41%). When they need education materials, they frequently request to dentist's association (36%), academic society (35%), but rarely to dental clinics or dentists (6%). They prefer that two times (46%) of annual oral health education, with the contents of regular brushing (53%), but lower regular visit to clinics (13%). The interest to oral health care (p=0.016) increased with teacher's age. And, they agreed regular students education in case of higher interest(p=0.044). Intention about join in the model school program was decreased with scale of school (p=0.002). Conclusions : This result showed that the present status of ESOHCP is still insufficient. It considered that the health teachers' interest and role is most important for the maintenance and success of ESOHCP. The professional and efficient education program would be focused on the health teachers to induce drive on ESOHCP.

• Preventive Nutrition and Food Science
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• v.21 no.4
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• pp.310-316
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• 2016

In this study, the anti-osteoarthritis effects of Cynanchum wilfordii, Phlomis umbrosa, and Angelica gigas extract (CPAE), observed and confirmed in previously clinical studies were further investigated by in vitro and in vivo studies. Anabolic biomarkers related to healthy cartilage maintenance, such as aggrecan, type II collagen ${\alpha}$-1 (Col2a1), sex determining region Y-box-9 (Sox-9), and catabolic biomarkers related to osteoarthritis, such as cyclooxygenase-2 (Cox-2), matrix metalloproteinase-13 (Mmp13), and nuclear factor kappa-light-chain-enhancer of activated B cells ($Nf{\kappa}b$), were evaluated by quantitative reverse transcriptase polymerase chain reaction and reporter gene assay. In vitro study results showed significant changes in both anabolic and catabolic biomarkers. For anabolic factors, significant changes in the level of aggrecan (P<0.05), Col2a1 (P<0.05), and Sox-9 (P<0.01) activation were shown after treatment of cartilage cells with CPAE (50 ng/mL) with similar efficacy compared to insulin growth factor, the positive control (100 ng/mL). For catabolic factors, significant changes in the inhibition activity of Cox-2 (P<0.05), Mmp13 (P<0.01), and $Nf{\kappa}b$ (P<0.05) were shown for CPAE (50 ng/mL) with similar efficacy compared to Celecoxib, the positive control ($10{\mu}M$). In the in vivo carrageenan-induced paw edema model study results showed that CPAE-treated groups (100 mg/kg) and Celecoxib-treated groups (60 mg/kg) showed comparably significant efficacy of inhibition by 37.1% and 52.1%, respectively. Furthermore, CPAE (200 mg/kg) showed similar effect to Celecoxib (60 mg/kg) with an inhibition rate of 54.3%. This result confirms that CPAE effectively inhibited the inflammation-induced osteoarthritis symptoms.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.1-11
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• 2021

Recently, the importance of preventive maintenance has been emerging since failures in a complex system are automatically detected due to the development of artificial intelligence techniques and sensor technology. Therefore, prognostic and health management (PHM) is being actively studied, and prediction of the remaining useful life (RUL) of the system is being one of the most important tasks. A lot of researches has been conducted to predict the RUL. Deep learning models have been developed to improve prediction performance, but studies on identifying the importance of features are not carried out. It is very meaningful to extract and interpret features that affect failures while improving the predictive accuracy of RUL is important. In this paper, a total of six popular deep learning models were employed to predict the RUL, and identified important variables for each model through SHAP (Shapley Additive explanations) that one of the explainable artificial intelligence (XAI). Moreover, the fluctuations and trends of prediction performance according to the number of variables were identified. This paper can suggest the possibility of explainability of various deep learning models, and the application of XAI can be demonstrated. Also, through this proposed method, it is expected that the possibility of utilizing SHAP as a feature selection method.

• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.136-143
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• 2009

The injuries as a result of fall accidents is the one of the most common kind of injuries in Korea, especially fall from height is the top most common kind for fatal injuries. Futhermore, the number of fall injuries in manufacturing industry has been steadily increasing from 2000 to 2007. In 2007 the number of fall fatal injuries increased 10.6 % in comparison with the number in 2006. These numbers are 6~17 times higher than those for foreign countries such as the U.K and the USA. So, it is needed to make a study to reduce these numbers for manufacturing industry. To get the goals, we did research as followings. First, this study analyzed statistics by industry, by fall height, by common agent and so on to gain an insight into real aspect of fall injuries. It showed that ladder is the commonly cited agent for manufacturing industry, and 3 risky activities ; the ladder work, the load/unload work, and the maintenance work. Secondly, this study made a survey of manufacturing workers for their understandings of the most 3 risky activities. It showed that 'tendency to work easily' and 'difficulty of applying measures due to inherent working conditions' are main reasons for workers not to implement the preventive measures against the fall accidents. Thirdly, this study tested the slip characteristics of ladder base and lungs. The tests were done based on ANSI standard and KS. In addition to the standard condition, this study performed slip tests in wet and sandy conditions and compared the results with the those of standard condition. It showed that friction coefficient is standard condition > wet condition > sandy condition, and the friction coefficient of ladder for sandy condition is measured to be reduced by 63.9% compared with that for standard condition. Finally, this study developed safety work models for using of portable ladders in consideration of the safety standards of foreign countries such as the U.K, the USA, and the Australia.