• Nuclear Engineering and Technology
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• v.47 no.5
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• pp.624-632
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• 2015

A self-diagnostic monitoring system is a system that has the ability to measure various physical quantities such as temperature, pressure, or acceleration from sensors scattered over a mechanical system such as a power plant, in order to monitor its various states, and to make a decision about its health status. We have developed a self-diagnostic monitoring system for an air-operated valve system to be used in a nuclear power plant. In this study, we have tried to improve the self-diagnostic monitoring system to increase its reliability. We have implemented three different machine learning algorithms, i.e., logistic regression, an artificial neural network, and a support vector machine. After each algorithm performs the decision process independently, the decision-making module collects these individual decisions and makes a final decision using a majority vote scheme. With this, we performed some simulations and presented some of its results. The contribution of this study is that, by employing more robust and stable algorithms, each of the algorithms performs the recognition task more accurately. Moreover, by integrating these results and employing the majority vote scheme, we can make a definite decision, which makes the self-diagnostic monitoring system more reliable.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.2 no.3
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• pp.36-47
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• 2003

Wideband Code Division Multiple Access (WCDMA) is one of the air interface techniques proposed for the third generation (3G) mobile communication system. WCDMA was selected because it fulfills the IMT-2000 requirements for higher data rate trans mission, support of multimedia capabilities and other flexible services due to its variable bit rates and larger bandwidth, improved capacity and coverage, efficient power control and support for advanced and improved detector structures. Performance evaluation of 3G wireless network through simulation plays an important role in the design and implementation of the actual system, aiding the wireless system designer by providing them the necessary performance conformance statistics prior to implementation. In accordance with this goal, a simulator engine was developed entirely on a MATLAB platform to emulate the behaviour of the WCDMA air interface for both the uplink and downlink in a real world fading mobile environment. This paper discuss the development of the simulator along with a brief description of its functionalities and user interface. The WCDMA air interface mode focused in this paper is in accordance to the 3GPPs frequency division duplex (FDD) mode and restricted to the physical layer description. Performance results for the selected cases for the downlink, uplink, varying mobile velocity and sampling rates are also provided.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.5
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• pp.435-442
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• 2014

This paper describes an improved design model that can be used to configure a non-contact pneumatic device to turn a large sheet at the in-line system. For rotational moving in the conveyor system, the conventional method is to turn the system itself. The improved non-contact pick-up system mainly uses 8 pairs of L-shaped latches and 12 swirl type heads. It is positioned above the upward air flow table. This system performs the non-contact gripping and side-edge contact support in the vertical and rotational directions to hold the self-weight of a large flat sheet. A non-contact air head can exert a sufficient gripping ability at 4N lower than the standard working pressure. The side latches support 60% of the lifting force required. Through structural and flow analysis, the working conditions were simultaneously considered in accordance with the deflection and flatness of the glass.

• Advances in aircraft and spacecraft science
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• v.8 no.4
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• pp.289-302
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• 2021

Ensuring flight safety for passengers as well as crew is the most important aspect of modern aviation, and in order to achieve this, it is necessary to be able to forecast the durability of individual components. The present contribution illustrates the results of a computational analysis to determine the possibility of analysing the prediction of bearing durability in on-board rotating equipment from the point of view of thermal fatigue.In this study, a method developed at the Air Force Institute of Technology was used for analysis, which allowed to determine the bearing durability from the flight altitude profile. Two aircraft have been chosen for analysis - a military M-28 and a civilian Embraer. As a result of the analysis were obtained: the bearing durability in on-board rotating devices, average operation time between failures, as well as failure rate. In conclusion, the practical applicability of this approach is demonstrated by the fact that even with a limited number of flight parameters, it is possible to estimate bearing durability and increase flight safety by regular inspections.

• Journal of Environmental Impact Assessment
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• v.18 no.4
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• pp.195-208
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• 2009

The power plant is well known to influence air pollution as well as emission of green house gas. Because of increasing demand on electricity, the government set up the electric support action plan every 2 years. In this research, the impacts of power plants on the environment and region was studied. The study was focused on the establishment of power plant in Incheon area based on the 3rd electric support action plan. According to the 3rd electric support action plan, almost 80% of power plant in metropolitan area is planned to be built in Incheon area. The main influences of establishment of power plant are emissions of $SO_x$, $NO_x$ and PM and exceed the allocated local industry emissions, which means the emission allocation of other industry is difficult. In additions, the power plant exhaust $CO_2$ much more than other types of fuel such as waterpower generation, atomic power station. Although several supports are given in local government, these cannot cover the whole cost due to establishment of power plant. Subsequently, this study suggest the additional policy based on local consideration is needed and the current electricity distribution system should be reconsidered fundamentally in the lang term.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.2
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• pp.243-251
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• 2010

The military has been putting great efforts into applying data communication on existing voice communication systems being used in NCW(Network Centric Warfare). Data communication will be an effective choice in one of many effort to yield a minimum kill chain, comparing to legacy voice communications, when tactical units conduct their missions. However, the required budget will be enormous, in case of the replacement of a lot of legacy communication systems with new one. As a cost-effective alternative, the tactical data communication systems using the conventional radio systems instead of the development of new radio systems has been proposed. It is mandatory, though, to ensure QoS while maintaining data communication by making use of legacy radio systems already in use. This paper focuses on the performance issues experimented and analyzed for tactical data communication through the legacy radio systems as the first step towards guaranteed QoS. We have conducted various experiments such as the transmission error rate on certain tactical messages, performance evaluation of redundant transfers, the relationship between the transmission frame size and rate of error, the identification of error points in the transmission frame, and techniques to reduce the errors in both hopping and non-hopping modes. As a result of the performance experiments, The adaptive communication module which decides the redundant transmission or the Forward Error Correction(FEC) technique by analyzing channel status and current transmission status(hopping/non-hopping) of the legacy radio should be designed. the FEC technique in non-hopping, and the redundant transmission technique in hopping mode was recommended from the result of experiment with the frame size is 20bytes in non-hopping and 10Bytes frame size in hopping mode.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.133-140
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• 2018

In recent years, model-based design techniques have been used as a way to support cost reduction and safety certification in the development of avionics systems. In order to support performance analysis and safety analysis of aircraft and avionics equipment (item) using model based design, we developed a multi-domain simulation environment that inter-works with heterogeneous simulators. We present a multi-domain simulation environment that can verify air data computers and integrated multi-function probes at the aircraft level. The model was developed by Simulink and the flight simulator X-Plane 10 was used to verify the model at the aircraft level. Avionics model functions were tested at the aircraft level and the air data errors of the model and flight simulator were measured within 0.1%.

• Journal of Space Technology and Applications
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• v.2 no.3
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• pp.206-220
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• 2022

There are various systems that allow humans to safely maintain their space exploration missions and lives in completely different environments, such as the International Space Station, the Moon (the closest celestial body to Earth), and Mars (the only planet in the solar system for manned mission in the 2030s). Among them, when it comes to maintaining the basic breathing of humans, the human life support air management system is a key device system. Such an air management system can be used not only for space exploration but also for undersea bases and submarines on Earth where humans reside. The air management system basically consists of an oxygen generation system, a carbon dioxide removal system, and a harmful substance removal system. In this paper, in order to develop an air management system that can be used in an underwater residential platform, the development requirements of a ground test module to be used as an experimental facility were analyzed.

• Journal of National Security and Military Science
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• s.15
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• pp.57-86
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• 2018

The ROKAF has been training for a number of exercise for victory in the war, but the lack of aviation ammunition has become a big issue every year. However, due to the limitation of defense resources, there are many difficulties in securing and stockpiling ammunition for the war readiness. Therefore, there is a need to find a way to secure aviation ammunition for war readiness in a more economical way, so In this study, we analyze the precedent research case and the case of the reduction of the purchase cost of weapon system of other countries, and then I have suggested a plan that is appropriate for our situation. As a result of examining previous research cases for this study, there were data that KIDA studied in 2012, Precision-guided weapons acquisition cost reduction measures pursued by US Air Force And the use of procurement agencies that are being implemented by NATO member countries. Based on this study, the following four measures were proposed to reduce the purchase cost of aviation ammunition. First, the mutual aid support agreement was developed to sign the ammunition joint operation agreement. Second, join the NATO Support & Procurement Agency (NSPA) Third, it builds a purchasing community centered on the countries operating the same ammunition Fourth, participating in the US Air Force's new purchase plan for ammunition and purchase it jointly. The main contents of these four measures are as follows. 1. the mutual aid support agreement was developed to sign the ammunition joint operation agreement. Korea has signed agreements on mutual logistics support with 14 countries including the United States, Israel, Indonesia, Singapore, Australia, and Taiwan. The main purpose of these agreements is mutual support of munitions and materials, also supporting the training of the peace time and promoting exchange and cooperation. However, it is expected that there will be many difficulties in requesting or supporting mutual support in actual situation because the target or scope of mutual aid of ammunition is not clearly specified. Thus, a separate agreement on the mutual co-operation of more specific and expanded concepts of aviation ammunition is needed based on the current mutual aid support agreements 2. join the NATO Support & Procurement Agency (NSPA) In the case of NATO, there is a system in which member countries purchase munitions at a low cost using munitions purchase agencies. It is the NATO Purchasing Agency (NSPA) whose mission is to receive the purchasing requirements of the Member Nations and to purchase them quickly and efficiently and effectively to the Member Nations. NSPA's business includes the Ammunition Support Partnership (ASP), which provides ammunition purchase and disarming services. Although Korea is not a member of NATO, NSPA is gradually expanding the scope of joint procurement of munitions, and it is expected that Korea will be able to join as a member. 3. it builds a purchasing community centered on the countries operating the same ammunition By benchmarking the NSPA system, this study suggested ways to build a purchasing community with countries such as Southeast Asia, Australia, and the Middle East. First, it is necessary to review prospectively how to purchase ammunition by constructing ammunition purchasing community centered on countries using same kind of ammunition. 4. participating in the US Air Force's new purchase plan for ammunition When developing or purchasing weapons systems, joint participation by several countries can reduce acquisition costs. Therefore, if the US Air Force is planning to acquire aviation ammunition by applying it to the purchase of aviation ammunition, we will be able to significantly reduce the purchase cost by participating in this plan. Finally, there are some limitations to the method presented in this study, but starting from this study, I hope that the research on these methods will be actively pursued in the future.

• Journal of Environmental Health Sciences
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• v.34 no.5
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• pp.361-368
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• 2008

Objective to assess whether exposure to air pollutants is associated with postneonatal infant death, using a timeseries methodology, between 1999 and 2003 in Seoul, Korea.. Methods We investigated the short-term effects of air pollution for 548,725 live births during the study period. The daily count of postneonatal infant deaths from all causes and from SIDS (sudden infant death syndrome) by birth order was analyzed by a Generalized Additive Poisson model, with controlling for the effects of seasonal trends, air temperature, relative humidity, barometric pressure, and day of the week as covariates. Results During the study period, we observed 699 deaths from all causes and 47 deaths from SIDS. We did not find any significant associations between daily mortality and ambient levels of air pollutants except for CO and $NO_2$. The estimated relative risk of postneonatal infant death from all causes was 1.17 (95% CI=1.04-1.32) and 1.16 (95% CI=1.03-1.29) by IQR (interquartile range) for CO and $NO_2$ respectively. Also, we observed no clear trend of the mortality effects of air pollution by birth orders. Conclusion In conclusion, our findings suggest that air pollution, in general, influenced adversely postneonatal infant death from all-cause and SIDS although it was not statistically significant. This study may support that the rationale.