• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.132-138
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• 2018

Aviation safety requires systematic national attention and management because aircraft accident produce greater undesired social impact, economical damage, and declining national credibility compare to other transportation accident. Specially, Republic of Korea has highly increased risk of air accident as a major air transportation point having small aerospace, connecting pacific ocean and Asia, and explosively increased air traffic produced by economical growth, operating numerous military aircraft for the South and North Koreas' confrontational situation. Also, greatly increased domestic and oversea air travels by Koreans and foreigners as well as air freight based on heightened Korea's national power, launching new low cost carriers, and popularized leasure aviation have produced large amount of aviation needs in various fields. However, national aviation safety management system gratifying increased aviation needs and aircraft operations is seem to be slow in progress. This paper will show optimized measures utilizing private, governmental, and military resources to prevent aircraft accident under circumstances of limited budget and an favorable conditions, then will propose several action items.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.422-425
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• 2008

TerraSAR-X is new radar satellite operated at X-band, multi polarization, and multi beam mode. Compared with C-band or L-band SAR, the X-band system inherently suffers from more temporal decorrelation, but is more sensitive to surface deformation monitoring due to short wavelength (3.1 cm) and high spatial resolution (1m-3m). It is generally expected that sensitivity to estimate surface movement using TerraSAR-X will be increased by the factor of 10, compared to current C-band system with low spatial resolution such as ERS-2, Envisat. Many urban areas are experiencing land subsidence due to water, oil and natural gas withdrawal, underground excavation, sediment compaction, and so on. Monitoring of surface deformation is valuable for effectively limiting damage areas. In addition high accuracy and spatially dense subsidence map can be achieved by X-band InSAR observation, promoting identification and separation of various subsidence processes and leading to enhanced understanding via mechanical modeling. In this study we will introduce some initial InSAR results using new TerraSAR-X SAR data for surface deformation monitoring.

• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.106-111
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• 2000

EP(Electrostatic Precipitator) has been used to keep the natural environment from fly-ash in the industrial fields and operated in intermittent PEC(Pulse Energized Control) mode to improve dust-collecting efficiency. Intermittent PEC mode induces low-frequency harmonic currents into power system, therefore EP transformer vibrates. This continuous transformer vibration developes transformer abnormal audio-noise and if it is too much or operates in the region of natural frequency, transformer will be damaged in the end. EP interruption caused by transformer damage results in power generation stopped, power quality down and economic loss. Therefore, this paper explains harmonic currents and transformer vibration-core vibration, winding vibration, and proposes the measures of suppressing the vibration with EP operated in intermittent PEC mode. And this results is proposed to be used for future EP transformer design or EP control method to operate EP-concerned equipment safely keeping from system faults caused by transformer vibration.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.3
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• pp.342-347
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• 2015

The launcher pod for missiles capable of carrying a range of different warheads has been designed to be mounted on the tracked vehicle of the hybrid weapon system (HWS). In the development of this launcher pod, its structure was designed to be resilient to damage caused by shock and vibration, as well as preventing assembly errors due to the spring-back of the main composite cover and interfacing parts. This study investigated the design of the newly developed launcher pod, with its hybrid composite-metal structure, through simulation and experiment. Both simulation and actual experiments showed that the structure of the launcher is resilient to vibration and shock. The launcher pod was also subjected to vibration and shock tests to verify its performance.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.6
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• pp.519-522
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• 2008

As industry of a semiconductor and LCD industry have been rapidly growing, precision technologies of machining such as etching and 3D measurement are required. Stylus has been important measuring method in traditional manufacturing process. However, its disadvantages are low measuring speed and damage possibility at contacting point. To overcome mentioned disadvantage, non-contacting measurement method is needed such as PMP(Phase Measuring Profilometry), WSI(white scanning interferometer) and Confocal Profilometry. Among above 3 well-known methods, WSI started to be applied to FPD(flat panel display) manufacturing process. Even though it overcomes 21t ambiguity of PMP method and can measure objects which has specular surface, the measuring speed and vibration coming from manufacturing machine are one of main issue to apply full automatic total inspection. In this study, We develop high speed WSI system and algorithm to reduce unknown noise. The developing WSI and algorithm are implemented to measure 3D surface of wafer. Experimental results revealed that the proposed system and algorithm are able to measure 3D surface profile of wafer with a good precision and high speed.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.535-542
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• 2007

The Geumho river watershed located in the middle of the Nakdong river has been threatened by high population growth and urbanization. Of concern specifically is the potential impact of future developments in the watershed on the reduction of base flow and the consequent risk of degradation of ecological habitats in Geumho river. Anticipated increase in imperviousness, on the other hand, is expected to elevate flood risk and the associated environmental damage. A watershed hydrology based modeling study is initiated in this study to assist in planning for sustainable future development in the Geumho river watershed. The Soil and Water Assessment Tool (SWAT) is selected to model the impact of urbanization in the Geumho river watershed on the hydrologic response thereof. The modeling results show that in general the likelihood that the watershed will experience high and low stream flows will increase in view of the urbanization so far achieved.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.1051-1065
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• 2020

Safety analysis of nuclear power plant (NPP) especially in accident conditions is a basic and necessary issue for applications and commercialization of reactors. Many previous researches and development works have been conducted. However, most achievements focused on the safety reliability of primary pressure system vessels. Few literatures studied the structural safety of huge concrete structures surrounding primary pressure system, especially for the fourth generation NPP which allows existing of through cracks. In this paper, structural safety reliability of concrete structures of HTR-PM in accidental double-ended break of hot gas ducts was studied by Exceedance Probability Method. It was calculated by Monte Carlo approaches applying numerical simulations by Abaqus. Damage parameters were proposed and used to define the property of concrete, which can perfectly describe the crack state of concrete structures. Calculation results indicated that functional failure determined by deterministic safety analysis was decided by the crack resistance capability of containment buildings, whereas the bearing capacity of concrete structures possess a high safety margin. The failure probability of concrete structures during an accident of double-ended break of hot gas ducts will be 31.18%. Adding the consideration the contingency occurrence probability of the accident, probability of functional failure is sufficiently low.

• Journal of Sensor Science and Technology
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• v.33 no.5
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• pp.298-304
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• 2024

In Korea, fires are the second most common type of disaster, causing large-scale damages. The installation of fire detectors is legislated to prevent fires and minimize damage. Conventional fire detectors have limitations in initial suppression of failures because they detect fires when large amounts of smoke and heat are generated. Additionally, frequent malfunctions in fire detectors may cause users to turn them off. To address these issues, recent studies focus on accurately detecting even small-scale fires using multi-sensor and deep-learning technologies. They also aim at quick fire detection and thermal decomposition using gas. However, these studies are not practical because they overlook the heavy computations involved. Therefore, we propose a fast and accurate fire detection system based on multi-sensor and deep-learning technologies. In addition, we propose a computation-reduction method for selecting sensors suitable for detection using the Pearson correlation coefficient. Specifically, we use a moving average to handle outliers and two-stage labeling to reduce false detections during preprocessing. Subsequently, a deep-learning model is selected as LSTM for analyzing the temporal sequence. Then, we analyze the data using a correlation analysis. Consequently, the model using a small data group with low correlation achieves an accuracy of 99.88% and a false detection rate of 0.12%.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.4
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• pp.40-47
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• 2007

The objective of this study is to analyze the propriety of the Biotope Area Factor's(BAF) application and propose an improvement plan. The BAP system, initially started by Seoul metropolitan city, is being settled in Korea. The BAF originated from the Biotop $Fl{\ddot{a}}chen$ Faktor(BFF) system of Berlin Germany. It was established as part of the Landscape Plan for the ecological function recovery in the high density built-up area with a sense of environmentally friendly urban management. The study compared the BAF's present condition of Ganddong-Gu, Seoul with Seoul's BAF system. Some problems appeared from the system application. Firstly, it may cause ecological damage if the site ranges are more than current BAF system limits. Secondly, the application of the current BAF system has the possibility of general redevelopment, but the partial improvement considering current standards of the high density built-up area's paving section is impossible. Lastly, division of the application object and application type are not divided well. In addition, the Seoul BAF which is currently applied across the board is based on the destruction of the natural area and low density built-up area. Accordingly, to improve these problems requires a complementary system protecting the ecological function prior to the application of the BAF and with restricted application to high density of BAF system built-up area.

• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.46-51
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• 2018

A basic sprinkler system is a fire extinguishing system that can be easily installed in a fire-vulnerable place such as a publicly used establishments. However, the publicly used establishments are not only complicated in structure, but also have a large amount of flammable interior materials, and the users are not normally in a normal state, which is a very dangerous fire-fighting object. Therefore, due to the low fire extinguishing performance of the basic sprinkler system installed in the publicly used establishments, the fire suppression control can not be performed quickly in case of fire, which may increase the life and property damage. In this study, the cases of quantitative changes of extinguishing water used in basic sprinkler system and the cases of addition of additives such as wetting agents, reinforced agents to improve extinguishing performance were compared. Experimental results showed that the extinguishing performance was improved as the quantity of extinguishing water increase and the reinforced agents showed similar performance to that of 60% increase in the amount of extinguishing water. The cooling time to $200^{\circ}C$ and oxygen concentration were improved up to 14.3% and 34.5%, respectively. In the case of using the wetting agent, the cooling time to $200^{\circ}C$ and oxygen concentration did not show any significant improvement, but showed the effect of preventing deep seated fire. In order to prevent loss of life and property, it is necessary to improve the performance of the basic sprinkler system by increasing amount of extinguishing water or using additives like reinforced agents.