• Journal of Sensor Science and Technology
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• v.23 no.4
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• pp.266-271
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• 2014

Chemical sensors are used in various industrial facilities such high-risk and prevent the leakage of substances, important in life and environmental protection and the safe use of industry, used for management. In particular, high-temperature environments such as power generation equipment of the rotating part due to leakage generated by the various oil, power plants Shut Down, fire, work environment (exposure to various chemical solution and gas leak) and various water, air and soil pollution causes. Thus, over the long term through various channels such as crops and groundwater contamination caused by the slow, serious adverse effect on the ecosystem. In this paper, synthetic lube oil and high pressure hydraulic fluid leakage and immediately detect a new Printed Electronic implementation of technology-based film-type sensors, and its performance test. Thus, industrial accidents and environmental pollution and for early detection of problems, large accidents can be prevented. Experimental results of the synthetic lube oil and high pressure hydraulic fluid solution after the contact time depending on the experiment and the oil solution of the sensor material of the conductive porous PE resistance value by a chemical reaction could be confirmed that rapid increase. Also implemented in the film-type oil sensor electrical resistance change over time of the reaction rate and the synthetic lube oil is about 2 minutes or less, the high pressure hydraulic fluid is less than about 1 minute was. Therefore, more high-pressure hydraulic fluid such as a low volatility synthetic lube oils are the resistance change and the reaction rate was confirmed to be the slowest.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.184-191
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• 2016

In recent years, there are a number of studies that have been carried out to explore the alternative for Mineral Oil (MO) as dielectric insulating fluid in transformers due to the increasing tight regulation on safety and environment. Vegetable oils have been identified as suitable candidate since it is biodegradable, non-toxic and high flash/fire points which ensure more in-service safety. Among the types of vegetable oils considered for transformers application are Palm Oil (PO) and Coconut Oil (CO). This paper presents an experimental study on the lightning breakdown voltages of PO and CO under non-uniform electric field based on needle-sphere electrodes configuration at 3 small gap distances. The type of PO used in this study is Refined Bleached and Deodorized Palm Oil (RBDPO) Olein. The main focus of this study is to examine the lightning breakdown performance of RBDPO and CO under different test conditions and assess its suitability as dielectric insulating fluid in transformers. The effect of voltage polarities (positive and negative) and testing methods (rising-voltage, up-and-down and multiple-voltage) were investigated. The data obtained from all tests were analysed by Weibull distribution in order to determine the withstand voltages for each type of oils. It was found that the breakdown voltages of RBDPO and CO are comparable with MO under positive lightning impulse. Under negative lightning impulse, the breakdown voltage of MO is slightly higher than RBDPO and CO. There is no significant effect of testing methods and voltage polarities on lightning breakdown voltages of RBDPO and CO. Based on the statistical analysis, it is found that the breakdown voltages of RBDPO and CO at 1% probability are slightly lower than MO.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.3
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• pp.249-254
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• 2017

The paper presents a new short-term dynamic displacement estimation method based on an acceleration and a geophone sensor. The proposed method combines acceleration and velocity measurements through a real time data fusion algorithm based on Kalman filter. The proposed method can estimate the displacement of a structure without displacement sensors, which is typically difficult to be applied to earthquake or fire sites due to their requirement of a fixed rigid support. The proposed method double-integrates the acceleration measurement recursively, and corrects an accumulated integration error based on the velocity measurement, The performance of the proposed method was verified by a lab-scale test, in which displacement estimated by the proposed method are compared to a reference displacement measured by laser doppler vibrometer (LDV).

• Journal of The Korean Society of Clinical Toxicology
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• v.18 no.1
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• pp.34-41
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• 2020

Purpose: This study evaluated aggressive hyperbaric oxygen therapy (HBOT) by understanding various exposure routes of acute carbon monoxide (CO) poisoning, the risk factors causing acute cardiovascular, and neurological toxicity caused by poisoning. Methods: A retrospective study was conducted based on the medical records of 417 acute CO poisoning patients who visited the emergency care unit from March 2017 to August 2019. The exposure routes, HBOT performance, age, sex, medical history (hypertension, diabetes mellitus, ischemic heart disease, heart failure), intentionality, loss of consciousness (LOC), intake with alcohol or sedatives, and initial test results (carboxyhemoglobin (COHb), troponin-I, electrocardiography, echocardiography, brain MRI) were examined. Comparative analysis of the clinical information was conducted between the groups that showed acute cardiovascular toxicity and neurological toxicity, and groups that did not. Results: Among 417 patients diagnosed with acute CO poisoning, 201 cases (48.2%) were intentional, and charcoal briquette was the most common route (169 patients (40.5%)). Two hundred sixteen cases (51.8%) were accidental, and fire was the most common route (135 patients (32.4%)). The exposure route was more diverse with accidental poisoning. Three hundred ninety-nine patients were studied for acute cardiovascular toxicity, and 62 patients (15.5%) were confirmed to be positive. The result was statistically significant in intentionality, LOC, combined sedatives, initial COHb, HTN, and IHD. One hundred two patients were studied for acute neurological toxicity, which was observed in 26 patients (25.5%). The result was statistically significant in age and LOC. Conclusion: Active HBOT should be performed to minimize damage to the major organs by identifying the various exposure routes of CO poisoning, risk factors for acute cardiovascular toxicity (intentionality, LOC, combined sedatives, initial COHb, HTN, IHD), and the risk factors for acute neurological toxicity (age, LOC).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.383-390
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• 2013

The reduction of the maximum acceleration which causes shock for a missile is very important to prevent abnormal operation of a missile and decrease size and cost of missile components. Because the maximum acceleration created by operation of an ejection gas generator occurs in the initial ejection stage, the design parameters which affect initial ejection stage were examined. The igniter and the nozzle closure were selected as design parameters of a gas generator. The maximum acceleration created by the gas generator was examined experimentally by changing of the design parameters. Finally the reduction effect of the maximum acceleration was compared quantitatively by static fire test of a gas generator. The maximum acceleration of the best model which was applied to each optimal design parameter was about 68% reduced than that of the reference model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.8
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• pp.806-812
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• 2010

Fuel tanks for rotorcraft have a great influence on the survivability of crews. The philosophy of crashworthy rotorcraft design evolved from the long term effort of the US Army. US army established MIL-DTL-27422D for specifying detail requirements related to crash resistant fuel tank especially for military rotorcraft to prevent post crash fire which is the greatest threat to life in rotorcraft crash. Crashworthiness of the rotorcraft fuel tank could be guaranteed through the crash impact tests which are specified in the MIL-DTL-27422D. Fuel tanks for Korea Helicopter Program have been developed and tested according to MIL-DTL-27422D with minor modifications of flexible fittings. The present study shows some results of the mandatory crash impact tests of the fuel tanks to verify their performances.

• Smart Media Journal
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• v.9 no.1
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• pp.38-44
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• 2020

Due to the high dependence on electric energy, electric fires make up a significant portion of fires in Korea. Electric arcs by short circuits or poor contact cause three of four electrical fires. An electric arc is a discharge phenomenon of electrical current between the insulators, which instantaneously produces high temperature. In order to reduce the fire due to electric arc, this study aims to predict the electric arc risk. We collected arc data from the arc detectors and converted into graphs based on temporal arc data. We used machine learning for training converted graph with different number of temporal arc data. To measure the performance of the learning model, we use the test data. In the results, when the number of temporal arc data was 20, the prediction rate was high as 86%.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.4
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• pp.74-80
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• 2014

This paper describes the development of the dual-thrust flight motor for enhancing the hit probability of unguided rockets. We designed dual-thrust flight motor by shape modification of the double base propellant with high burning rate, and confirmed the dual-thrust performance by static firing tests. The test results showed the thrust ratio of about 1:7.6 between sustaining phase and boosting phase, and had a quietly normal dual-thrust characteristics. And the results showed that there was not the fire extinction phenomenon of propellant due to the pressure drop.

• Steel and Composite Structures
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• v.51 no.1
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• pp.25-41
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• 2024

The measurement of pile bearing capacity is crucial for the design of pile foundations, where in-situ tests could be costly and time needed. The primary objective of this research was to investigate the potential use of fuzzy-based techniques to anticipate the maximum weight that concrete driven piles might bear. Despite the existence of several suggested designs, there is a scarcity of specialized studies on the exploration of adaptive neuro-fuzzy inference systems (ANFIS) for the estimation of pile bearing capacity. This paper presents the introduction and validation of a novel technique that integrates the fire hawk optimizer (FHO) and equilibrium optimizer (EO) with the ANFIS, referred to as ANFIS_FHO and ANFIS_EO, respectively. A comprehensive compilation of 472 static load test results for driven piles was located within the database. The recommended framework was built, validated, and tested using the training set (70%), validation set (15%), and testing set (15%) of the dataset, accordingly. Moreover, the sensitivity analysis is performed in order to determine the impact of each input on the output. The results show that ANFIS_FHO and ANFIS_EO both have amazing potential for precisely calculating pile bearing capacity. The R² values obtained for ANFIS_FHO were 0.9817, 0.9753, and 0.9823 for the training, validating, and testing phases. The findings of the examination of uncertainty showed that the ANFIS_FHO system had less uncertainty than the ANFIS_EO model. The research found that the ANFIS_FHO model provides a more satisfactory estimation of the bearing capacity of concrete driven piles when considering various performance evaluations and comparing it with existing literature.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.16-23
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• 2020

Water pipes are important facilities and consist of pipes of various specifications and materials. The annual average number of earthquakes in Korea is steadily increasing. Therefore, in case of the water pipe, it is estimated necessary to prepare for earthquakes. Damages to the water pipe by the earthquake can cause problems such as water supply and fire suppression, and cause damage to life and property. In Korea, however, it is difficult to find examples of seismic performance evaluation of water pipes based on experimental study. Damage to the water pipes by the earthquake is caused by the displacement-controlled behavior of the ground which is the liquifaction and fault lines. Especially, The damage to the water pipes by the earthquake is concentrated on the joint of the pipe. In particular, piping less than 200mm in diameter was found to be dangerous. Thus, in this study, the seismic and settlement performance of iPVC buried water pipes with fixed joints with a clamp of 150mm was evaluated with a test approach.