• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.3
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• pp.218-228
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• 2008

This paper describes on the real-time tracking of ship's dynamic behavior by AIS information in the coastal waters. The AIS data was received at a land station by using the antenna of AIS receiver mounted on the rooftop of the laboratory, Pukyong National University (PKNU), Busan, Korea, and stored as a NMEA format of serial output sentence of VDM(VHF Data-Link Message) and displayed on the ENC(Electronic Navigational Chart) of a PC-based ECDIS. In this study, the AIS receiver was mainly used to obtain the dynamic information that is necessary to evaluate and track the movement situation of training ship "KAYA" of PKNU in the coastal waters. The change of position with time for the ship turning under the rudder angle of port $30^{\circ}$ was correctly tracked with the turning circle of 940 m in diameter on the ENC of a PC-based ECDIS. Then, the dynamic information of the AIS system was updated every 6.29 seconds under the turning situation for the speed of 10.9 knots and every 21.65 seconds under the situation running at the speed of 11.05 knots on the straight line route of $155^{\circ}$, respectively. In case of AIS target tracking in the inshore zone behind large topographical obstructions, such as mountain and apartment buildings, the update rate of dynamic information was irregularly changed by the existence of land obstacles. However, the position tracking by AIS information under the situation existing no sea obstructions was achieved in real or near real-time and the instant presentation of course alternations for the ship was correctly monitored by using a PC-based ECDIS. From these results, we concluded that the PC-based ECDIS technology and methodology combined with the AIS information can be easily extended and applied to the surveillance and management for the fishing operation of fishing vessels in the coastal zone and in the EEZ fishing grounds.

• Journal of KSNVE
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• v.10 no.2
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• pp.345-352
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• 2000

Recently, it becomes to be very important to reduce the cabin noise of passenger ship, according to the trend of speedy and luxury ship. The noise reduction and control techniques should be considered as important factors from the viewpoint of the sound problem of cabin. Therefore, ship designer has to improve the sound quality as well as to redece the sound pressure level in cabins. In this paper, for the new approach of these problems, we tried to find the trends of noise and sound quality of high-speed coastal passenger ships. Loudness, roughness, fluctuation strength, and sharpness are selected as the parameters for the evaluation of sound quality. The parameters are calculated by using the sound measured in cabin while the ship is running. Furthermore we tried to find the trend of each parameter in cabins and compare with that of sound pressure level. As results, we find that the loudness is linearly proportional to sound pressure level. But, the other parameters show different trends which may be caused by ship motion on the wave and fluctuation of propelling power.

• Wind and Structures
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• v.24 no.5
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• pp.405-430
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• 2017

The aerodynamic characteristics of vehicles are critical to assess vehicle safety and passenger comfort for vehicles running on long span bridges in a windy environment. However, in previous wind-vehicle-bridge (WVB) system analysis, the aerodynamic interference between the vehicle and the bridge was seldom considered, which will result in changing aerodynamic coefficients. In this study, the aerodynamic coefficients of a high-sided truck on the ground (ground case) and a typical bridge deck (bridge deck case) are determined in a wind tunnel. The effects of existent structures including the bridge deck and bridge accessories on the high-sided vehicle's aerodynamic characteristics are investigated. A three-dimensional analytical framework of a fully coupled WVB system is then established based on the finite element method. By inputting the aerodynamic coefficients of both cases into the WVB system separately, the vehicle safety and passenger comfort are assessed, and the critical accidental wind speed for the truck on the bridge in a windy environment is derived. The differences in the bridge response between the windward case and the leeward case are also compared. The results show that the bridge deck and the accessories play a positive role in ensuring vehicle safety and improving passenger comfort, and the influence of aerodynamic interference on the response of the bridge is weak.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.609-617
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• 2017

Railways are one of the safest and most important transportation systems in the world. On the other hand, due to the increasing complexity of the railway system and the running distance of rail vehicles, railway accidents occur continuously every year. In particular, in the case of high-speed trains and freight trains, if the function of the axle bearing is lost due to abnormal overheating of the axle box bearing, the load on the axle becomes uneven. Therefore, abnormal overheating in the train axle box bearings can cause serious accidents or derailments. For this purpose, a Hot Box Detector (HBD) was installed in the track side of a high speed line to detect abnormal overheating. This paper proposes an EWMA technique-based axle temperature monitoring method to detect abnormal overheating quickly and efficiently. A statistical design of the proposed method was also performed. The proposed method has better performance compared to the current method in the case of abnormal overheating and the performance is improved by approximately 170% at the maximum.

• Journal of Korea Multimedia Society
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• v.10 no.8
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• pp.1029-1038
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• 2007

A smart card based on the existing Java card platform executes and installs an application only when the power is supplied for a minute. And preparing for unexpected power outrage, the execution state of an application and all the data that are modified during execution are saved in the heap. This kind of frequent data update of an EEPROM data is a main cause of reducing the life-cycle of a smart card. This is because the smart card has been developed not considering the current situation that the power is always supplied, and by this time it has continuously kept its old architecture. This paper explains the high performance Java card system free power restriction. The system improves not only application saving mechanism, but memory architecture. In special, we deploy RAM for running an applet, as well as EEPROM for downloading an application. Through proposed mechanism, we can find out performance evaluation that the creation speed of an applet and the execution speed of a method increase up to 58% and 33% respectively.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.98-98
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• 2014

Due to the simple vertical structure of magnetic field, pores can be exploited to study the transport of mechanical energy by waves along the magnetic field to the chromosphere and corona. For a better understanding of physics of pores, we have investigated chromospheric traveling features running across two merged pores from their centers at the speed about 55 km s-1, in the active region AR 11828. The pores were observed on 2013 August 24 by using high time, spatial, and spectral resolution data from the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST). We infer a LOS velocity by applying the bisector method to the Ca II $8542{\AA}$ band and $H{\alpha}$ band, and investigate intensity and the line-of-sight velocity changes at different wavelengths and different positions at the pores. We find that they have 3 minutes oscillations, and the intensity oscillation from the line center is preceded by that from the core ($-0.3{\AA}$) of the bands. There is no phase difference between the intensity and the LOS velocity oscillations at a given wavelength. The amplitude of LOS velocity from near the core spectra is greater than that from the far core spectra. These results support the interpretation of the observed wave as a slow magnetoacoustic wave propagating along the magnetic field lines in the pores. The apparent horizontal motion and a sudden decrease of its speed beyond the pores can be explained by the projection effect caused by inclination of the magnetic field with a canopy.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.2
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• pp.224-229
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• 2005

Generally, genetic algorithm (GA) has too much time and space complexity when it is running in the typical processor. Therefore, we are forced to use the high-performance and expensive processor by this reason. It also works as a barrier to implement real device, such a small mobile robot, which is required only simple rules. To solve this problem, this paper presents and proposes enhanced processor-architecture for the faster GA processing. A typical processor architecture can be enhanced and specialized by two approaches: one is a sorting network, the other is a residue number system (RNS). A sorting network can improve the time complexity of which needs to compare the populations' fitness. An RNS can reduce the magnitude of the largest bit that dictates the speed of arithmetic operation. Consequently, it can make the total logic size smaller and innovate arithmetic operation speed faster.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.1
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• pp.81-88
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• 2011

A real time monitoring system from a PC has been developed which can be accessed through transmitted data, which incorporates an established low powered transport system equipped with a single chip combined with wireless sensor network technology from a three-axis acceleration sensor. In order to distinguish between static posture and dynamic posture, the extracted parameter from the rapidly transmitted data needs differentiation of movement and activity structures and status for an accurate measurement. When results interpret a static formation, statistics referring to each respective formation, known as the K-mean algorithm is utilized to carry out a determination of detailed positioning, and when results alter towards dynamic activity, fuzzy algorithm (fuzzy categorizer), which is the relationship between speed and ISVM, is used to categorize activity levels into 4 stages. Also, the ISVM is calculated with the instrumented acceleration speed on the running machine according to various speeds and its relationship with kinetic energy goes through correlation analysis. With the evaluation of the proposed system, the accuracy level stands at 100% at a static formation and also a 96.79% accuracy with kinetic energy and we can easily determine the energy consumption through the relationship between ISVM and kinetic energy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.169-170
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• 2006

The purpose of this study was to evaluate the smoothness of the gait pattern according to shoe, walking speed, and slope. Eleven male university students used three types(running shoes, mounting climbing boots, elevated forefoot walking shoes) of shoes at various walking speeds(1.19, 1.25, 1.33, 1.56, 1.78, 1.9, 2.0, 2.11, 2.33m/s) and gradients (0, 3, 6, 10%) on a treadmill. Three-dimensional motion analysis (Motion Analysis Corp, Santa Rosa, CA, USA) was conducted with 4 Falcon high speed cameras. The results showed that elevated forefoot walking shoes had the lowest value of normalized jerk at the heel, which means that elevated forefoot walking shoes had the smoothest walking pattern at the heel. In contrast, elevated forefoot walking shoes had greater normalized jerk at the center of mass (COM) at most walking speeds, which means that the smoothness of gait pattern at the center of mass is the lowest for the elevated forefoot walking shoes. This movement at the COM might even have a beneficial effect of activating muscles in the back and abdomen more than other shoes.

• Journal of Korean Society of Disaster and Security
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• v.13 no.1
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• pp.51-58
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• 2020

This paper analyzes the effect of airflow of ceiling air conditioner on the operation of sprinkler head using a simulation program. The simulation space is 10 m × 7 m × 3 m, and the size of the fire is 0.8 m × 0.8 m × 0.6 m. The cold air flow from the air conditioner is at 25℃ and the wind speed is divided into three cases : 10 ㎧, 8.5 ㎧, and 7.5 ㎧. Simulation results show that all cases had operating delays compared to when the air conditioner was not running, and the sprinkler head did not operate until 10 minutes had elapsed at 10 ㎧ wind speed. These results confirmed that the sprinkler head was delayed in the air conditioning space and the worst result of early evolution failure was observed in strong winds such as 10 ㎧.