• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.15-18
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• 2003

The electric power, regenerated while railway vehicles braking or running downhill, makes U line voltage rise and the feeding system may not be secure. In order to keep away from these kind of insecurity, the regenerative energy should be consumed by loads or transmitted to the AC side via certain devices such as DC/AC converters. This paper introduces the developed regenerative inverter for electric railway.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.5 s.311
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• pp.60-67
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• 2006

Thermal analysis and prediction of electronic components is required to predict and optimize the reliability of onboard electronic unit employed in space vehicles. This paper introduces a methodology on thermal prediction that uses isothermal PCB model, thermal force model, thermal resistance matrix and superposition principle to calculate electronic devices temperatures undergoing thermal conduction environment. An example is Presented including a prediction result by this method and simulation results performed by commercial program.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2011.04a
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• pp.231-235
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• 2011

The purpose of this study was to analyze the types and characteristics of temporary small-sized housing units for single-person households. A document research method and case studies were used to analyze and classified the spatial characteristics and types of the temporary dwelling spaces since 2000. Findings of this study were as follows: temporary and simplified dwelling spaces were developed by the concept of impermanence for single-person households in modern society. In order to conform the concept of temporary dwelling for small-sized housing units of single-person households, the characteristics were divided into three aspects. 'Transporting' by wheel and rotation and vehicles, 'Transforming' by adapting, assembling disassembling, and folding unfolding, and 'Wearing Carrying' by inflatable and tented types. It attempted to resolve the concept of temporarity through the experiment so that they might apply to the space of contemporary city.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.41-43
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• 2017

AKARI performed about 10,000 spectroscopic observations with the Infrared Camera (IRC) during its mission phase. These IRC observations provide unique spectroscopic data at near- and mid-infrared wavelengths for studies of the next few decades because of its high sensitivity and unique wavelength coverage. In this paper, we present the current status of the activity for improving the IRC spectroscopic data reduction process, including the toolkit and related data packages, and also discuss the goal of this project.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.291-297
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• 1996

To visualize sound field or to identify noise sources, we can use many methods such as intensity method, acoustic holographic method, source identification method using line array, etc. Conventionally all these methods are performed with the assumption of stationary condition in space and time. But for moving source, spatial characteristics and frequency components are changing, so we need another processing algorithm. This paper shows some experimental results - sound field by moving noise sources. In the experiment cross type microphone line array is used for sensing pressure and cars and a motorcycle are used as moving sources that are assumed to have constant speed. The processing methods are acoustic holographic method, spherical beamforming and spectrogram.

• Journal of Navigation and Port Research
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• v.40 no.2
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• pp.51-56
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• 2016

Expressways mean the primary arterial highways with a high level of efficiency and safety. However, Gyeongbu and Namhae expressways connected with Busan ports are showing travel time delay by increased traffic including the medium/large-sized vehicles of about 20% compared to those of about 13% regardless of the peak periods. This study, thus, intends to analyze lane traffic characteristics in the basic 8-lane segments of the above-mentioned expressways, compute the planning and buffer times based on travel time reliability, find the lane speed showing a higher correlation with planning time between the lane speeds in the basic 8-lane segments, and finally suggest a correlation model for predicting the planning time in expressways.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.340-345
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• 2002

Passengers in automobile or train are exposed to a worse noise environment when they are in the tunnel than in the open field. This is due to a relatively higher space density of sound energy by multiple reflection phenomenon of noise generated by operation of transportation vehicles from tunnel wall compared to open field. In this study, noise characteristics of subway train running through a tunnel were investigated at straight/curved track and tunnel type(semi circular/box). Also the noise measured simultaneously at inner and outer sides of train running through a tunnel, so that the coherence of the various noise sources of subway train to inner noise was evaluated.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.198-203
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• 2003

Due to the low production cost and space availability which are originated from the structural simplicity of the torsion beam axle suspension, the suspension has been frequently used for sedan and SUV style vehicles. The design procedure of the suspension, however, requires significant amount of time which prohibits more efficient design of the suspension. In this study, an integrated procedure and constituting modules are explained and the performance of the corresponding program is exhibited. The integrated procedure enables one to save the design time and cost significantly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.581-587
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• 2011

Reliability estimation methods using attribute data are widely used in reliability evaluation of various systems such as nuclear energy plants, food and drug, and space launch vehicles. This paper shows sensitivity analysis and comparison results of reliability estimation methods including a parametric estimation method in open literature with respect to both sample size and sampling points of time. And ways to improve accuracy of each reliability estimation method were proposed from the sensitivity analysis results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.72-78
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• 2005

Considerable achievements on scramjet technology have been performed since the end of 1950's when the improvement of performance on ramjet engine was begun. From the viewpoint of rapid and economic efficiency, scramjet propulsion system is presently regarded as the most promising one considered to be applied to the atmospheric hypersonic airplanes and ballistic weapons and even the space launch vehicles. Histories and current trends on scramjet development of USA and Russia are investigated and suggested in this paper.