• Journal of Sensor Science and Technology
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• v.27 no.5
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• pp.352-356
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• 2018

This paper relates to a technology for monitoring a liquefied gas storage tank in the special gas field where demand is increasing owing to the continuous growth of related fields such as the semiconductor, display, and ICT convergence electronics industries. We have proposed a system for real - time monitoring using wireless sensor network technology, and implemented a system consisting of a sensor unit, transmitter module, and receiver module to be attached to a liquefied gas storage tank. The system was applied to LCO2 tanks among various liquefied gas storage tanks to verify the feasibility. The storage tanks employed in the experiments has capacities of 16,179 l and was 1,920 mm in inner diameter. Furthermore, the density was 1.03 g/l. The measured data were compared with reference data on the remaining gas level versus the $CO_2$ height of the surface, expressed using a conventional water meter, provided by an existing storage tank supplier. The experimental results show that the data is similar to the standard data provided by the tank supplier, and has a high accuracy and reliability within an error range of 0.03%.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2089-2098
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• 2015

With the continuous development in insulation of electrical equipment design, the reliability of the system has been enhanced. However, in the manufacturing process and during operation under continues stresses introduce local defects, such as voids between interfaces that can responsible to occurrence of partial discharge (PD), electric field distortion and accumulation of charges. These defects may lead to localize corrosion and material degradation of insulation system, and a serious threat to the equipment. A model of three layers of PI film with air gap is presented to understand the influence of interface and voids on exploitation conditions such as strong electrical field, PD activity and charge movement. The analytical analysis, and experimental results are good agreement and show that the lose contact between interfaces accumulate more residual charges and in consequences increase the electric field intensity and accelerates internal discharges. These residual charges are trapped charges, injected by the electrodes has often same polarity, so the electric field in cavities increases significantly and thus partial discharge inception voltage (PDIV) decreases. Contrary, number of PD discharge quantity increases due to interface. Interfacial polarization effect has opposite impact on electric field and PDIV as compare to void.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.74-82
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• 2015

The Admission Officer System is a selecting system that evaluates potential and talent of students in multiple aspects and selects whom each university wants to pick and fits the specific recruitment units. However, the issue about fairness of the system has been discussed continually. This study conducted online survey, using fairness checklist with 31 universities to know how admission officers perceive the fairness of the system and secure that. Also, three times of expert FGI were conducted, too. The result shows there are still many universities that adjustment for deviated evaluation in interview, separation of operating agency, stabilization of the statue of admission officers, analyzation of each evaluator's tendency, and so on are not achieved well. To assure the fairness of the admission officer system, securing validity by clearly defining the concept of fairness is proposed first. Stabilizing the statue of admission officers and continuous education training for them is also proposed to improve their professionality. Furthermore, expansion of education programs about the admission officer system in both quantity and quality is suggested for fairness of the system.

• Journal of the Korea Safety Management & Science
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• v.17 no.1
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• pp.13-19
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• 2015

Continued efforts to build up Safety Management System(SMS) and to improve its efficiency in airports, to which customers have direct access, are taken for granted due to continuous development of the aviation industry in both quantity and quality and rapid growth of air transportation market. This thesis proposed efficient operation methods of SMS for domestic airport organizations including Incheon International Airport(IIA), the largest airport in South Korea, aiming at strengthening aviation safety from the perspective of airport operators who play a pivotal role in service provider SMS. Those are consolidation of the existing safety management organizations and various improvements to promote voluntary incident reporting system. To draw a proposal for the improvements, conducted a research on domestic safety management status, carried out an analysis on operating conditions and did a research on ICAO regulations, domestic legal system as well as statistics data. Relevant studies and researches were also gathered and analyzed. A search for further improvements can also help increase operational efficiency and promoting a higher-level of safety awareness among operators can establish mature safety culture at airports.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1087-1091
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• 2008

Evapotranspiration (ET) is an important factor while simulating daily streamflow in hydrological models. The LAI (Leaf Area Index) value reflecting the conditions of vegetation generally affects considerably in the estimation of ET, for example, when using FAO Penman Monteith equation. Recently in evaluating the vegetation condition as a fixed quantity, the remotely sensed LAIs from MODIS satellite data are avaliable, and the time series values of spatial LAI coupled with land use classes are utilized for ET evaluation. The 4 years (2001-2004) MODIS LAI data were prepared for the evaluation of continuous hydrological model, SLURP (Semi-distributed Land Use-based Runoff Processes). The model was applied for simulating the dam inflow of Chungjudam watershed ($6661.58\;km^2$) located in the upstream of Han river basin of South Korea. From the model results, the FAO Penman Monteith ET was affected by the MODIS LAIs. Especially for the ET of deciduous forest, the Total ET was 33.9 % lager than coniferous forest for the 3.8 % lager of LAI. The watershed average LAI caused a 7.0 % decrease in average soil moisture of the watershed and 14.3 % decrease of ground water recharge.

• Journal of the military operations research society of Korea
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• v.36 no.2
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• pp.1-10
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• 2010

Learning rate is generally applied to estimate an appropriate production labor cost. Learning effect is obtained from repetitive work during the production period under 3 assumptions ; homogeneous production, same producer, quantity measure in continuous unit. However, production breaks occur frequently in Korean defense industry environment because of budget constraint and annual requirements. In this case previous learning effect can not be applied due to learning loss. This paper proposed the application of learning rate when a production break occurs in Korea defense industry. To obtain a learning loss, we surveyed various learning loss factors for different production breaks(6, 12, 18 months) from 4 defense industry companies. Then, we estimate the first unit labor hours in re-production phase after production break using Anderlohr method and Retrograde method with the result of the survey. This work is the first attempt to show a method which defines and evaluates the learning loss factors in Korean defense industry environment.

• Journal of Applied Reliability
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• v.5 no.2
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• pp.261-272
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• 2005

In evaluation of electronic reliability on the PCB(Printed Circuit Board), electrochemical migration is one of main test objects. The phenomenon of electrochemical migration occurs In the environment of the high humidity and the high temperature under bias through a continuous aqueous electrolyte. In this paper, the generating mechanism of electrochemical migration is investigated by using water droll acceleration test under various waters. The waters used in the water drop test are city water, distilled water and ionic water. It found that the generated velocity of electrochemical migration depended on the temperature of water and the electrolyte quantity which included in the various waters.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.783-787
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• 2013

The separation and capture process of carbon dioxide from power plants is garnering interest as a method to reduce greenhouse gas emissions. In this study, aqueous alkanolamine solutions were studied as absorbents for $CO_2$ capture. The solubility of $CO_2$ in aqueous alkanolamine solutions was investigated with a continuous stirred reactor at 313, 333 and 353 K. Also, the heat of absorption ($-{\Delta}H_{abs}$) between the absorbent and $CO_2$ molecules was measured with a differential reaction calorimeter (DRC) at 298 K. The solubility and heat of absorption were determined at slightly higher than atmospheric pressure. The enthalpies of $CO_2$ absorption in monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), and 2-amino-2-methyl-1-propanol (AMP) were 88.91, 70.44, 44.72, and 63.95, respectively. This investigation showed that the heat of absorption is directly related to the quantity of heat for absorbent regeneration, and is dependent on amine type and $CO_2$ loading.

• Journal of the Korean Institute of Gas
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• v.10 no.1 s.30
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• pp.7-12
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• 2006

The quantity of gas which can be supplied by LPG storage tank become a standard of selection. In the absence of the maximum evaporation rates from LPG storage tanks by tank capacity, continuation using time, air temperature, it is in a problem for the dissemination of LPG Storage tanks. In this paper, we showed the maximum evaporation rates from LPG storage tanks by tank capacity, air temperature, continuous using time and remaining level.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.131-138
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• 2003

This paper considered the structural mechanism of transitional boundary layer by the experimental approach. In order to measure the turbulence quantity in the boundary layer, we made a wind tunnel with 400${\times}$190${\times}$2500 mm test section and a flat plate with well fabricated leading edge. Hot wire anemometer was used for acquiring the continuous turbulence signal which is processed by special software. The results of experiment show that the region where turbulence spot is dominant moves from near wall to overall layer and thus the anisotropy of velocity fluctuation shows so large value. Also the turbulence energy originally contained in low frequency band comes up to the high frequency band. Finally the turbulence model needs minimum two length scales to consider the pre-transition region.