• Journal of Korean Society for Quality Management
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• v.52 no.3
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• pp.479-493
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• 2024

Purpose: The deterioration in the quality of failure history data due to differences in interpretation of failures among workers at power plants and the lack of consistency in the way failures are recorded negatively impacts the efficient operation of power plants. The purpose of this study is to propose a system that classifies power generation facilities failures consistently based on the failure history text data created by the workers. Methods: This study utilizes data collected from three coal unloaders operated by Korea Midland Power Co., LTD, from 2012 to 2023. It classifies failures based on the results of Soft Voting, which incorporates the prediction probabilities derived from applying the predict_proba technique to four machine learning models: Random Forest, Logistic Regression, XGBoost, and SVM, along with scores obtained by constructing word dictionaries for each type of failure using LIME, one of the XAI (Explainable Artificial Intelligence) methods. Through this, failure classification system is proposed to improve the quality of power generation facilities failure history data. Results: The results of this study are as follows. When the power generation facilities failure classification system was applied to the failure history data of Continuous Ship Unloader, XGBoost showed the best performance with a Macro_F1 Score of 93%. When the system proposed in this study was applied, there was an increase of up to 0.17 in the Macro_F1 Score for Logistic Regression compared to when the model was applied alone. All four models used in this study, when the system was applied, showed equal or higher values in Accuracy and Macro_F1 Score than the single model alone. Conclusion: This study propose a failure classification system for power generation facilities to improve the quality of failure history data. This will contribute to cost reduction and stability of power generation facilities, as well as further improvement of power plant operation efficiency and stability.

• Journal of Korean Academy of Nursing Administration
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• v.7 no.1
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• pp.111-126
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• 2001

The purpose of this study is to provide a basic data by evaluation the problems about nursing information system and identifying the need of improvement of it. Data were collected from April 6 to 15, 2000 through questionnaires taken by 218 nurses working in a general hospital using nursing information systems. The two structured questionnaires were used for the collecting the data. The data obtained were analyzed by using frequency, percentage, mean, standard deviation, t-test, one-way ANOVA, Pearson's correlation coefficients, and Cronbach's alpha coeffcients. The results are as follows: 1. In the problem of nursing information system, ${\lceil}$There are no appropriate programs for independent nursing information systems because there are no nurse informatists in the information department${\rfloor}$ scored highest. Also, ${\lceil}$There is a lack of manual for operation of the nursing information system${\rfloor}$, ${\lceil}$There is difficulty getting help when the system is in trouble${\rfloor}$, ${\lceil}$General information about using computers and managing problems are lacking${\rfloor}$, ${\lceil}$Unsatisfactory matters about the nursing information systems are not improved quickly.${\rfloor}$ received high scores. 2. In the need for improvement of the nursing information system, ${\lceil}$Nursing education and research${\rfloor}$ was the highest area of the system. 3. The problems of the nursing information system showed high positive correlation with the need for improvement of the system(p=.00).

• Korean Journal of Childcare and Education
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• v.13 no.3
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• pp.39-54
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• 2017

Objective: The purpose of this study was to examine natural groupings of the sub-factors of mother's reaction to children's negative emotions. The natural groupings were as follows; the emotion-coaching-reaction, the emotion-minimizing-reaction and oversensitive reaction. In addition, this paper also investigated individual differences in children's emotion regulation by clusters of sub-factors of mother's reaction to children's negative emotions. Methods: The subjects of this study consisted of 318 children. The data were analyzed using cluster analysis and one-way ANOVA. Results: The results suggested four proper clusters, according to the characteristics of mother's reaction to children's negative emotions. Cluster 1 was categorized as 'child centered-emotion coaching', cluster 2 was categorized as 'oversensitive-emotion coaching comorbid', cluster 3 was categorized as 'acception-emotion minimizing confused' and cluster 4 was categorized as 'emotion minimizing-unsupporting.' Additionally, the differences between Emotion regulations in each cluster showed distinct points of interest. In terms of the maladaptive emotion regulation, cluster 3 showed the highest level followed by cluster 4. And cluster 1 and 2 showed the lowest level. Conclusion/Implications: The results of this study helped to find a deeper understanding of the operation of specific clusters of mother's reaction to children's negative emotion and children's emotion regulation.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.92-98
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• 2015

This paper was carried out to prove the relation between static loads acting on the sluice(hydrostatic) and dynamic loads (additional loads) arising from opening or closing of sluice, through measuring the operation of shell-type roller gate by using the method of measuring of the completely opening water gate, as measured from one excitation state, it was confirmed to be capable of measuring the natural frequency reliable measurement results. Throughout the test, we prove that it's a reasonable way to estimate the default margin of safety when calculated by dividing the sum of the hydrostatic stress to the maximum stress and additional stress. The application of this paper's safety estimation method can be utilized as the basic data for the systematic and rational maintenance management of dams and submerged weirs in the future, and it is expected that this study can bring forth.

• Journal of Applied Reliability
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• v.15 no.4
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• pp.282-288
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• 2015

Purpose : The purpose of this study is to compare the RAM (reliability, availability and maintainability) value in the acquisition phase with operational period for air weapon systems. The objective is to determine if the value of RAM is sufficient in the field, and look for any difference from the target value to some extent. Methods : For a case study, the ${\bigcirc}{\bigcirc}$ training aircraft is selected. Data from the two acquisition sources are utilized. One is the operational data in domestic aircraft through research and development, and the other is the data from imported aircraft. The two different sources were collected independently and distinctly. Results : According to the analysis, the domestic aircraft shows high deviation in RAM value compare to the imported systems. This is due to the effort of continuous reliability improvement. In the aspect of maintainability, the result shows a slight deviation, and the availability meets the requirement. Conclusion : The results of this study can be used in finding a way that can be effectively applied to the sustainability in the weapon system. If the RAM performance is significantly lower than the target value, then it is necessary to improve the design activities so that they can achieve the RAM target value.

• Journal of Korean Society of Transportation
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• v.5 no.2
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• pp.81-95
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• 1987

In line with the continued growth of car ownership, the traffic problems in central area of metropoles such as Seoul would become increasingly degraded. comparing with most western cities, the problems in Seoul are characterized by the improportionately high rates of intersection delay, station congestion, traffic accidents caused by weaving conflicts and pedestrian congestion. It is caused by the lack of flexibility I street network, which is prerequisite for upholding the efficacy of traffic management and control, resulted from the simplicity of network graph in terms of connectivity, street density and distribution by width. This pattern has been resulted from the prolonged policy pursuing the street-widening of the nagging bottleneck in such a short period since the 1950s, comparing that most western cities had undergone over several centuries an age of horse-and-vehicle transportation. In order to improve the expected traffic problems in central area over the coming periods of motorization, it is imperative to restructure the street network in Central Seoul so that the efficacy of traffic management and control may be operative. Based upon the long-range planning the street network should be restructured by stages so that cenral traffic may be controled by one-way operation and most through-traffic be detoured around fringe area.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.504-518
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• 1998

Degree-Of-Freedom(DOF) for most power transmission system varies according to the operation status which consists of friction elements to change the power flow or to adjust the speed ratio such as clutches, brakes or one-way clutches. To simulate the dynamic characteristics of automatic power transmission system which is a typical example of such a variable DOF systems, many sets of governing equations and complicated phase decision routines are necessary. In this paper dynamic constraint theorem is derived explaining the torque transmission characteristics during the clutch engagement process and a robust stable algorithm is developed describing this phase transition phenomenon effectively by introducing the concept of direct torque and virtual damping. Finally, applying this algorithm to a passenger car automatic transmission gear consisting of several friction elements, an efficient simulation methods for such a complex system will be suggested that is very simple and systematic.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.6
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• pp.661-668
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• 2012

Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from $2.06m/s^2$ base excitation compared to stand-alone piezoelectric energy harvester without tip mass.

• Journal of environmental and Sanitary engineering
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• v.3 no.2 s.5
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• pp.79-90
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• 1988

Untill to-day the disposal of municipal refuse in Korea is entirely depending on dumping the refuse into concave land except a few case that bring about the secondary pollution by generating insects, offensive odour and the dust blow which cause adverse effects to dwelling community in the vicinity. It is widely recognized since Korea is ready to be advanced nation must be carried out the proper way of refuse disposal as meet with the environmental standard and ready to accept by general public. Refuse disposal that is practiced by world wide is known as sanitary landfill although it bears some what the expensive construction and operation costs rather than the plain dumping. The following statement is the construction of sanitary landfill in brief. When one takes a look at the Unites States which has huge territory normaly carry out the refuse disposal by anaerobic improved landfill method while the country has limitted land is experimenting various types of landfill which bring about the earier reuse of completed landfill site and minimise the secondary pollution. The author of this article consider out of several landfill methods the semi aerobic landfill will be widely applied in Korea in coming day, the following article will elaborate little more about the semi aerobic method.

• Journal of the Korean Society of Marine Environment & Safety
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• v.7 no.2
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• pp.1-11
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• 2001

Many investments and works being continued to preserve green ocean in each countries of the world. Especial1y, the researches on the prevention of marine oil pollution being strengthened. It is not easy to disclose sludge oils that were produced necessarily in the ships operation, so that they are transferred to shore treating facility after collected inside the ship＇s sludge tank mostly. However, this shore transferring method is not only costly and time consuming but also entails risk of oil pollution. In this regard, it will be the best way to manage the sludge oils inside ship itself. The purpose of this study is to device an ultrasonic breaking systems which recycle the sludge oil from ships into usable oil to be burnt. In this paper, the first place, matrix structures of sludge fuel oil(SFO) and sludge lubricating oil(SLO) with the irradiation time for ultrasonic vibrator were interpreted. And, erosion damage for vibrator horn tip which is one of important part of ultrasonic breaking systems was examined under such an environment of the sludge oils. The material for horn tip is being made of SS41 steel and its erosion phase was investigated with variation of the vibration amplitude of 50${\mu}{\textrm}{m}$ and 24${\mu}{\textrm}{m}$ as well as the change of temperature in the oil environments. It is suggested that the experimental results can be helpful to the development of sludge oil disposing systems for the vessel.