• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2017-2018
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• 2006

전력선 통신기술은 추가 배선이 필요 없는 유용성에도 불구하고 전력선 채널에 대한 정확한 채널 모델링과 전력선 모뎀의 전송 신뢰성에 대하여 많은 문제점을 나타내고 있다. 본 논문에서는 전송선로의 주파수에 대한 잡음과 임피던스 특성을 분석하고, 이의 해결을 위하여 전력선 채널에 Spread Spectrum 기법을 적용한 신호를 전송하였을 때의 시뮬레이션 결과와 구현된 FPGA 보드를 비교분석 하였다. 채널 모델링은 잡음과 감쇄 특성을 고려하였으며, Spread Spectrum 변조 방식을 적용한 전력선 모뎀의 FPGA를 구현하여 성능을 분석하였다.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.39.1-39.1
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• 2017

Protoplanetary disks (PPDs) are a natural consequence of star formation and play crucial roles in planet formation. Atacama Large Millimeter/submillimeter Array (ALMA) has provided sub-mm data for the PPDs with a high angular resolution and sensitivity, and it makes us enable to study PPDs in detail. We have developed Packages of Unified modeling for Radiative transfer, gas Energetics, and Chemistry (PUREC), which consists of a self-consistent thermo-chemical model and line and continuum radiative transfer models, in order to interpret and predict the ALMA observations for PPDs. In this talk, we introduce capabilities of PUREC.

• Journal of Korea Water Resources Association
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• v.33 no.S1
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• pp.11-19
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• 2000

The role of river in the global water cycles and the modelling the horizontal water transport by rivers in the global scale are discussed. Due to the consolidation of the various hydrological information of the planet, now it is possible to monitor and simulate the quantity of the water carried by rivers. Land surface models that were developed originally for giving the boundary condition of the atmospheric and/or climatic models can be fairly used for river runoff simulations at least monthly scale, and it is promissing the approach will be a powerful tool to investigate the future water resources management.

• The Bulletin of The Korean Astronomical Society
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• v.31 no.2
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• pp.68.2-68.2
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• 2006

• Journal of the Korean Professional Engineers Association
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• v.35 no.4
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• pp.14-18
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• 2002

Water must be readily available to support all lives life and to create our earth. At first thought, It may seem that water is always available, since the earth is literally surrounded by water, so called water planet. The manner in which water circulates between earth and atmosphere determines where ample water supplies can be found and used for all organisms. If no forces except gravity were at work, the earth's water would settle in to the ocean basins and remain there.

• Journal of Astronomy and Space Sciences
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• v.27 no.1
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• pp.1-10
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• 2010

The distance distribution in our planetary system has been a controversial matter. Two kinds of important issues on Titius-Bode's relation have been discussed up to now: one is if there is a simple mathematical relation between distances of natural bodies orbiting a central body, and the other is if there is any physical basis for such a relation. We have examined, by applying it to exo-planetary systems, whether Titius-Bode's relation is exclusively applicable to our solar system. We study, with the $X^2$ test, the distribution of period ratios of two planets in multiple planet systems by comparing it with that derived from not only Titius-Bode's relation but also other forms of it. The $X^2$ value between the distribution of the orbital period derived from Titius-Bode's relation and that observed in our Solar system is 12.28 (dof=18) with high probability, i.e., 83.3 %. The value of $X^2$ and probability resulted from Titius-Bode's relation and observed exo-planetary systems are 21.38 (dof=26) and 72.2 %, respectively. Modified forms we adopted seem also to agree with the planetary system as favorably as Titius-Bode's relation does. As a result, one cannot rule out the possibility that the distribution of the ratio of orbiting periods in multiple planet systems is consistent with that derived from Titius-Bode's relation. Having speculated Titius-Bode's relation could be valid in exo-planetary systems, we tentatively conclude it is unlikely that Titius-Bode's relation explains the distance distribution in our planetary system due to chance. Finally, we point out implications of our finding.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.6
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• pp.786-795
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• 2011

This paper described the characteristic of vibration in wind turbine system including gearbox housing, gear drive, blade, generator. Especially, in planetary gear set, planet gears are supported by flexible pin. So, in planet gear, to consider not only torsional movement but also lateral movement. And include housing movement, because wind turbine system is supported by mount. To find out the characteristic of vibration, take the excitation source and study campbell diagram in operating range. Results of campbell diagram, resonances are occurred at 81.2HZ, 104.7Hz by 2nd tooth passing frequency. And resonance are also occurred at 264.5HZ, 377Hz, 424.6Hz by 3th tooth passing frequency. From the result, take vibration reduced measures.

• Journal of Astronomy and Space Sciences
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• v.23 no.4
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• pp.453-464
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• 2006

Web camera is usually used for video communication between PC, it has small sensing area, cannot using long exposure application, so that is insufficient for astronomical application. But web camera is suitable for bright planet, moon, it doesn't need long exposure time. So many amateur astronomer using web camera for planetary imaging. We used ToUcam manufactured by Phillips for planetary imaging and Registax commercial program for a video file combining. And then, we are measure a property of web camera, such as linearity, gain that is usually using for analysis of CCD performance. Because of using combine technic selected high quality image from video frame, this method on take higher resolution planetary imaging than one shot image by film, digital camera and CCD. We describe a planetary observing method and a video frame combine method.

• Journal of Information Technology Services
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• v.19 no.3
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• pp.35-56
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• 2020

The purpose of this study is to measure corporate personality by analyzing the internal employees' corporate reviews and to identify the impact of the representative corporate personality on the relationship between job satisfaction of internal employees and the turnover rate of the company. To this end, we first created a dictionary of words representing the corporate personality with a Word2vec method based on words explaining five corporate personalities, such as reliability, initiative, practicality, activism, and femininity, obtained from the preceding study. Next, we analyzed reviews which were written by internal employees on their companies to measure the score of corporate personality at a review level, aggregated the review level scores for each company to calculate the company level score of corporate personality, and assigned to each company the corporate personality with the maximum score among the five such scores. Also, job satisfaction and turnover rate were measured from internal employees' corporate evaluation scores and the percentage of former employees of each company who left a review on the company, respectively. This study collected datasets of corporate reviews, employee information, and corporate information from Job-Planet from 2014 to 2017, conducted a technical statistic check and correlation analysis to confirm the suitability of the datasets, and performed linear regression analysis to evaluate the research model and verify hypotheses. As a result of the analysis, the job satisfaction of the internal staff has a significant negative impact on the corporate's turnover rate. In addition, companies having a personality of reliability, initiative and femininity also showed a significant cause-and-effect relationship between job satisfaction and turnover rate and among them, job satisfaction of companies having a personality, initiative, showed a greater impact on turnover rate. In sum, we not only proposed a novel method of measuring corporate personality, but also showed that corporates need to identify its corporate personality and to utilize a different strategy to reduce their employee's turnover rate depending on the corporate personality.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.3
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• pp.311-318
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• 2017

Four species of sea turtles (Chelonia mydas, Caretta caretta, Dermochelys coriacea, and Eretmochelys imbricata) have been recorded in Korean waters. However, nationwide surveys on the distribution and occurrence of each species have rarelybeen conducted in Korean waters. In this study, we comparatively analyzed the trends in occurrence of sea turtles and their morphological characteristics based on 148 reliable observations and stuffed specimen data and suggested Korean names for each species. Chelonia mydas (57 cases, 58.8%) and C. caretta (52 cases, 31.5%) were dominant species, and occupied > 90% of all observations. Most of observations of sea turtles in Korean waters were obtained through stranding (61 cases) and incidental catches (62 cases). A coastal set net was the main fishing gear for incidental catches (82%). Sea turtles were found mainly around Jeju-do and the Korea Strait from June to November. Most C. caretta found were adults, whereas most C. mydas were juveniles. Additionally, we provide detailed morphological characteristics of C. mydas (n=8) and C. caretta (n=4) using stuffed specimens. Finally, based on a literature search, we suggest appropriate Korean names, such as "Pureunbada-geobuk" for C. mydas, "Bulgeunbadageobuk" for C. caretta, "Jangsu-geobuk" for D. coriacea, and "Maeburibada-geobuk" for E. imbricate.