• Journal of the Korean housing association
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• v.27 no.4
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• pp.59-66
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• 2016

The purpose of this study is to examine the necessity of 'emergency plumbing equipment for preventing the spread of water leakage'. It reviews social and economic costs when there is spread of water leakage and finds out that those are enormous. Expansion of water leakage causes conflicts between neighbors, economic loss and inconvenience from damages on facilities like elevator and power failure. Next, it examines the inability of existing plumbing equipment when it comes to spread of water leakage. Newly defined 'Surface Leakage' means rapid leak in the surface, and 'Internal Leakage' means seeping out slowly and gradually buried in the pipeline. It will also be analyzed by separating the concept of a leak in the two concepts of a 'Surface Leakage' and 'Internal Leakage'. It proposes emergency plumbing equipment for preventing the spread of water leakage as a solution for the expansion of water leakage. It explains general concepts of emergency plumbing equipment for preventing the spread of water leakage. It will also examine the effectiveness of the user by performing a survey of 420 multi-level building their opinion on the effects of an emergency plumbing equipments to prevent the spread of water leakage.

• Journal of the Ergonomics Society of Korea
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• v.22 no.1
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• pp.31-42
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• 2003

This study describes a modification of the technique for human error analysis in nuclear power plants (NPPs) which adopts advanced Man-Machine Interface (MMI) features based on computerized working environment, such as LCOs. Flat Panels. Large Wall Board, and computerized procedures. Firstly, the state of the art on human error analysis methods and efforts were briefly reviewed. Human error analysis method applied to NPP design has been THERP and ASEP mainly utilizing Swain's HRA handbook, which has not been facilitated enough to put the varied characteristics of MMI into HRA process. The basic concepts on human errors and the system safety approach were revisited, and adopted the process of FMEA with the new definition of Error Segment (ESJ. A modified human error analysis process was suggested. Then, the suggested method was applied to the failure of manual pump actuation through LCD touch screen in loss of feed water event in order to verify the applicability of the proposed method in practices. The example showed that the method become more facilitated to consider the concerns of the introduction of advanced MMI devices, and to integrate human error analysis process not only into HRA/PRA but also into the MMI and interface design. Finally, the possible extensions and further efforts required to obtain the applicability of the suggested method were discussed.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.71-74
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• 1991

This paper is described an expert system which performs the network reconfiguration in order to operate distribution systems optimally using heuristic rules. The proposed network reconfiguration is able to not only eliminate abnormal states such as overload of transformers/lines and low voltage violation, but also achieve minimum power loss and optimum load balancing under normal states. In order to apply the network reconfiguration efficiently, an expert system is adopted a best-first tree searching strategy on the basis of heuristics, and is implemented in AI language Turbo PROLOG. Several examples are used to illustrate concepts described above.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.301-302
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• 2012

During a last decade, detonative combustion is promising combustion mechanism of high-speed propulsion systems, but is more rigorously considered in these days as a game-changer for the improvement of thermodynamic efficiency of propulsion and power generation systems. Regardless of the skepticism about the pressure loss associated with the strong shock waves, it is shown that the additional compression by the strong shock wave exhibits increased thermodynamics efficiency that is not achievable by conventional compression systems. Present talk will give an introduction to the concepts and the recent activities on the pressure gain combustors (PGC) researches based on detonation phenomena.

• New & Renewable Energy
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• v.4 no.4
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• pp.3-9
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• 2008

In design PV (photovoltaic) system, there are many important factors to consider for best site selection. It is essential to understand to know the amount of sunlight available and how to minimize the shadings. This study presents basic concepts for understanding sun's position and insolation. also it gives easy tools for topography analysis. Finally, this study shows some theoretical calculations of power generation losses by topographic obstacle's elevations and disadvantages in economic feasibility, that is about 7million won loss per year for case of 10 degree topography elevation with assuming average Korea's topography elevation as 5 degree.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.200-205
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• 2003

The Canard rotor/wing (CRW) aircraft concepts offer great potential for application by allowing the use of a common propulsion system for high-speed cruise and low-speed powered lift. Using the rotor for lift in both flight modes increases its utility. In the hovering mode, the exhausted gas from an gas turbine engine is accelerated through the duct system and it provides the tipjet power for rotor system enough to lift the aircraft. In the cruise mode, the rotor is fixed and the exhausted gas is extracted through the main nozzle, such that the aircraft is able to flight with high speed. The duct system was designed using 1-D fanno line flow theory and empirical data. However, the empirical data of the pressure loss coefficient for various bending and dividing ducts were not enough to design our duct system adaptively. Therefore, using 3-D CFD analysis we obtained the pressure loss coefficient for our duct models and chose the appropriate bending or diving duct type. In this paper, we used the CFD-ACE+ software package for the CFD analysis and the modeling of duct system. Through the 3-D CFD analysis, we investigated also the pressure loss and the velocity distributions of the designed whole duct system as well as the blade duct. Comparing the 3-D CFD result with 1-D analysis result, we lessened the uncertainty of the designed duct system and speculated the problem that was not concerned in design state.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1609-1618
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• 2015

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings' power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.223-225
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• 2008

In order to apply SFCLs into electric power systems, the urgent issues to be settled are as follows, such as initial installation price, operation and maintenance cost due to ac loss of superconductor and the life of cryostat, and high voltage and high current problems. We designed novel hybrid SFCLs which combine superconductor and conventional electric equipments including a vacuum interrupter, an electro-magnetic contactor and a current limiting reactor. The main purpose of the hybrid SFCL is to drastically reduce total usage of superconductor by adopting current commutation method by use of the superconductor and the fast switch. According to protective coordination and performance, we investigated two concepts of Hybrid SFCLs. First is a half cycle fault current limitation type and second is a non-half cycle fault current limitation type. We concluded that the non-half cycle fault current limitation type is batter than the other.

• Journal of the Korea Society for Simulation
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• v.29 no.4
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• pp.47-54
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• 2020

North Korea has recently developed and deployed missiles with various ranges as asymmetrical forces. Among them, short-range ballistic missiles with improved accuracy are expected to aim at achieving tactical goals by hitting important military facilities in Korea with a small number of missiles. Damage to the air force airfields, one of North Korea's main targets of missiles attack, could limit the operation of air force fighters essential to gaining air superiority. Based on the attack by the short range ballistic missiles, the damage probability of military airfields was simulated. And as the one of the concepts of passive defense, the way to reduce the loss of combat power was studied through the changes of the air force squadrons deployment. As a result, the effective deployment plan could be obtained to reduce the amount of power loss compared to the current deployment.

• Research in Community and Public Health Nursing
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• v.12 no.1
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• pp.261-268
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• 2001

Recently, social concerns about addiction problems not only to substances like alcohol and drug but also to gambling or internet have been increasing. Addiction is caused by a combined influence of biological, psychological. and social factors. However, addiction may also occur due to weak will-power or poor education on addiction. Even though addicted behavior provides temporal mood change such as euphoria, satisfaction. or relaxation. it leads to serious physical and mental disorder of the addicted person and its family members, which possibly results in fatal consequences. Nurses are in an environment to meet and take care of those who are addicted or vulnerable to addiction in order to help the clients to recover or to prevent people from addiction. Despite the importance of nurses role in addiction problems, there is a lack of consistency of addiction is often interchangeably used with other similar concepts in the society. In this study, a concept analysis of addiction was performed to more clearly and comprehensively understand addiction and to develop effective nursing intervention methods for addicted clients. The analysis is conducted according to a series of processes described by Walker and Avant. The defining attributes of addiction identified in this study are as follows: 1) existence of object 2) control loss 3) withdrawal symptoms 4) continued use despite adverse consequences.