• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.1
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• pp.7-13
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• 2020

A significant growth in local air traffic volume is leading to airway congestion and flight delays especially for Incheon-China and Incheon-Europe sectors. A key method to increase the airway capacity is to place a supplemental airway parallel to the existing one and in cooperation between the aviation authorities between China and Korea, a dual airway track was implemented on December 6, 2018. Here, we use airline A's flight data to analyze the congestion change effect of the new airway. Results show total delay time to Europe is reduced 51% (13.4 to 6.6 minutes) as the delay distribution for 16-30 minutes, 31 minutes and greater decreased from 23.2% to 8.2% and 8.7% to 1.0% respectively. The delay to China also decreased but the drop is not as significant as flights to Europe. This is caused by the difference in flight distance, traffic volume, and characteristics of flights landing and transiting China. Flights to Europe show a broad distribution in altitude allocation and reduction in aircraft separation demonstrating the effectiveness of a dual airway track.

• Journal of Astronomy and Space Sciences
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• v.27 no.1
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• pp.43-54
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• 2010

This study was performed by the policy research project of Ministry of Land, Transport and Maritime Affairs, which title is "Developing safety standards and management of space radiation on the polar route". In this research, total six experiments were performed using Korean commercial flights (B747). Three of those are on the polar route and the other three are on the north pacific route. Space radiation exposure measured on the polar route is the average 84.7 uSv. The simulation result using CARI-6M program gives 84.9 uSv, which is very similar to measured value. For the departure flight using the north pacific route, the measured space radiation is the average 74.4 uSv. It seems that is not so different to use the polar route or not for the return flight because the higher latitude effect causing the increase of space radiation is compensated by the shortened flight time effect causing decreasing space radiation exposure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.870-873
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• 2001

The electron drift mobilitity of poly(4,4'-cyclohexylidenediphenyl carbonate)(PC-Z) doped with 3,5-dimethyl-3',5'-di-t-butylstilbenequinone(MBSQ) was measured by the time-of-flight technique. Energy gap of the polymer doped with 25wt% of MBSQ was 3.1 eV. The electron drift mobility was 2.98${\times}$10$\^$-6/$\textrm{cm}^2$/V$.$s at 293K. The electric field and temperature dependences of the electron drift mobility were discussed with Poole-Frenkel and Arrhenius formulations. The activation energy(E$\_$0/), Poole-Frenkel coefficient(${\beta}$) and effective temperature(T$\_$eff/) of the mobility are 0.815 eV, 1.73${\times}$10$\_$-4/ eV$.$cm$\^$1/2//V$\_$1/2/ and 6.43${\times}$10$^2$K, respectively.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.53-60
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• 2017

Most of present ultrasonic distance measurement technologies are based on the measurement of the TOF (: Time of Flight), the elapsed time during which the ultrasonic wave travels from its transmitter to receiver, to evaluate the distance the wave travels during that time. In this case, high distance measurement accuracy requires an accurate measurement of TOF. In order to acquire an accurate TOF, this paper proposes a method that produces the TOF by using a mathematical model of the received signal obtained from a mathematical model of ultrasonic transducer. The proposed method estimates the arrival time of the received signal retrospectively by comparing its wave form obtained after triggering point with its mathematical model in the sense of least-square. Experimental result shows that the effect of variation of triggering point can be decreased by implementing the proposed method.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.432-436
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• 2002

Benomyl, one of the known endocrine disrupting chemicals, was analyzed to understand the fate in the nature. Water, sediment and biota samples are acidified to hydrolyze benomyl into carbendazim then followed by extraction and concentration. The concentrations of carbendazim in the samples were determined by liquid chromatography/time-of-flight mass spectrometer. Analysis data showed that certain amount of carbendazim was accumulated in sediment. On the contrary, no sign of accumulation in biota was observed probably due to the increased degradation rate in vivo. It is, however, that no one can claim carbendazim is not harmful to biota, since carbendazim may give a negative effect against organisms at the point of intaking.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.3
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• pp.76-85
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• 2022

Work situational awareness test (WSAT) has been utilized to estimate the fatigue risk of workers who worked with time pressure or latent accident risks at their work environment. Thus researchers decided to use WSAT to estimate fatigue risk of cabin crews of an airline in Korea and to analyze empirically how such risk might have an effect on cabin crew's safety behavior. This was because there had not been enough research on accessing cabin crews' fatigue and analyzing its risk for the flight safety. In addition, the mediation effect of cabin crew's planning was also analyzed through Sobel-test by researchers among external factors such as lack of concentration, attention deficit, distraction and safety behavior. According to empirical analysis, it was found attention deficit and distraction of cabin crews due to fatigue during the flight had a significant negative effect on their planning. Planning was also proven to have mediation effect to cabin crew's safety behavior.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.275-278
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• 2013

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.72-77
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• 2014

There are two main technologies to implement cloud effect in flight simulator, cloud modeling using particle system and texture mapping. In former case, this approach may cause a low frame rate while unrealistic cloud effect is observed in latter case. To Solve this problem, in this paper, we propose how to apply fog effect into camera to display more realistic cloud effect with high frame rate. The proposed method is tested with massive terrain database environment through implemented software by using OpenSceneGraph. As a result, compared to texture mapping method, the degree of difference on frame rate is 1 or 2Hz while the cloud effect is significantly improved as realistic as particle system.

• International Journal of Advanced Culture Technology
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• v.10 no.3
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• pp.339-345
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• 2022

In this paper, the effect of porosity on the acoustic phase velocity of the 3D printed Kelvin closed-cell structure was investigated using the spectral phase analysis. Since Kelvin cells bring about the large amount of scattering, acoustic pulses in ultrasonic measurements undergoes a distortion of waveforms due to the dispersion effect. In order to take account on the dispersion, mathematical expressions for calculating the phase velocity of longitudinal waves propagating normal to the plane of the Kelvin structure are suggested by introducing a complex wave number based on Fourier transform. 3D Kelvin structure composed of identical unit-cells, a polyhedron of 14 faces with 6 quadrilateral and 8 hexagonal faces, was developed and fabricated by 3D CAD and 3D printer to represent the micro-structure of porous materials such as aluminum foam and cancellous bone. Total nine samples of 3D Kelvin structure with different porosity were made by changing the thickness of polyhedron. Ultrasonic pulse of 1MHz center frequency was applied to the Kelvin structures for the measurement of the phase velocity of ultrasound using the TOF(time-of-flight) and the phase spectral method. From the experimental results, it was found that the acoustic phase velocity decreased linearly with the porosity.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.6
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• pp.563-572
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• 2017

The purpose of the study is to investigate the effect of flight height, flight speed, exposure time of camera shutter and autofocusing on the visual resolution of the image in order to obtain ultra-high resolution images with a GSD less than 1cm. It is also aimed to evaluate the ease of recognition of various types of aerial targets. For this purpose, we measured the visual resolution using a 7952*5304 pixel 35mm CMOS sensor and a 55mm prime lens at 20m intervals from 20m to 120m above ground. As a result, with automatic focusing, the visual resolution is measured 1.1~1.6 times as the theoretical GSD, and without automatic focusing, 1.5~3.5 times. Next, the camera was shot at 80m above ground at a constant flight speed of 5m/s, while reducing the exposure time by 1/2 from 1/60sec to 1/2000sec. Assuming that blur is allowed within 1 pixel, the visual resolution is 1.3~1.5 times larger than the theoretical GSD when the exposure time is kept within the longest exposure time, and 1.4~3.0 times larger when it is not kept. If the aerial targets are printed on A4 paper and they are shot within 80m above ground, the encoded targets can be recognized automatically by commercial software, and various types of general targets and coded ones can be manually recognized with ease.