• Journal of KSNVE
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• v.6 no.3
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• pp.341-347
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• 1996

Vibration analysis is one of the most powerful tools available for the detection and isolation of incipient faults in mechanical systems. The methods of vibration analysis in use today and under continuous study are broad band vibration monitoring, time domain analysis, and frequency domain analysis. In recent years, great interest has been generated concerning the use of time- frequency repesentation and its application for a machinery diagnostics and condition monitoring system. The objective of the study described in this paper was to develop a new diagnostic tool for the rotating machinery. This paper introduces a new time frequency representation. Directional Winger-Ville Distribution, which analyese the time-frequency structure of the rotating machinery vibration.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.208-215
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• 2012

The acoustic noise around a launch pad by launches of space launch vehicles was analyzed. The magnitudes of sound noise at some points near launch pad were predicted by locating the sound source at the exhaust jet plume of the rocket engine and considering several factors such as the directivity of the sound propagation and atmospheric attenuation. Specifically, the launch noise of Korea Space Launch Vehicle-I (KSLV-I) was estimated, and was compared to the actual measurement results. The analysis results proved to be heavily affected by the characteristics of directivity of sound propagation and the analysis showed good agreements with the measurements when the directivity of the sound was appropriately adjusted.

• Proceedings of the KSEG Conference
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• 2002.04a
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• pp.201-210
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• 2002

서울시 북동부의 서울화강암에 대한 암반 공학적 특성 중 터널과 도로 건설시 중요하게 취급되는 절리의 방향성, 절리간격, 절리밀도, 암석의 일축압축강도, 그리고 RQD 값을 수락산과 불암산지역으로 구분하여 비교, 분석하였다. 이 중 절리의 방향성, 절리간격과 절리밀도는 선조사법, 원형조사법, 그리고 면적조사법을 이용하여 야외에서 직접 측정하였다. 암석의 일축압축강도와 RQD의 측정은 시추코아의 표본이 필요하지만 이번 연구에서는 간단히 응용할 수 있는 대비공식을 이용하여 계산하였다. 측정된 대표적인 절리의 방향성은 두 지역에서 모두 3조의 방향성이 나타났으며 즉 2조의 수직정방절리와 저각으로 경사하는 1조의 판상절리로 판명되었으며 두 지역에서 서로 유사한 방향성을 갖는다. 측정된 절리밀도는 0.039-0.066/cm이었으며, 평균절리길이는 1.30-4.52m, 그리고 평균절리간격은 10.3cm에서 최대 59.6cm로 측정된 절리의 방향에 따라 변화가 심하다 또한 슈미트 해머 타격값에 근거한 절리면의 일축압축강도는 217 MPa에서 335 MPa로 매우 강한 암체였으며, 평균절리간격에 기초하여 계산된 이론적 RQD 값은 73.1-98.7%의 값을 갖는 것으로 나타났다.

• Tunnel and Underground Space
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• v.28 no.3
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• pp.193-208
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• 2018

In order to interpret rock slope safely and effectively, the mechanical properties of the rock must be carefully investigated. However, due to the limitations of clinometer usage, a new measure of measurement is required to complement these limitations. In this study, a measuring device was developed to analyze the characteristics of joint orientation, and to apply the orientation of joint to the field. The developed measuring equipment is divided into analysis software and hardware. The hardware was composed of a measuring module that measures the joint orientation of rock and a transport module that transmits the measurement data. The software was developed to analyze the orientation of the joint from the data obtained from the measuring module and is named Drone Joint Orientation Survey Measurement. The developed measuring equipment was well field capable if it could not be measured by the inspector, such as in areas where access was difficult, and was capable of effectively analyzing the lab test results for the orientation of the joint.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.1
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• pp.88-103
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• 2009

The volatile and semi-volatile compounds of 5 accessions of domestic scented and 25 accessions of introduced scented were extracted by solid phase microextraction (SPME) and analyzed by gas chromatographymass spectrum (GC-MS). A total of 156 volatile and semivolatile compounds were identified from 30 accessions of aromatic rice, including 32 alcohols, 25 acids, 25 ketones, 21 hydrocarbon, 18 esters, 16 aldehydes, 4 ethers, 5 amines, 2 phenols, 2 bases, and 8 miscellaneous compounds. By UPGMA/Neighbor-join tree analysis, the thirty accessions of aromatic rice could be classified into seven groups according to the major odor or aroma compounds. Group I included indica type of Basmati varieties. Group II and Group IV included japonica type introduced scented. Group III consisted only Hyangmibyeo1ho in domestic scented. Group V and Group VII included indica type of Basmati and non-Basmati varities. Group VI included four of domestic scented of seven accessions excepted Basmati6129, Basmati 6311, and Seratus Malam.

• Tunnel and Underground Space
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• v.28 no.4
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• pp.343-357
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• 2018

Algorithm which can analyze the slope failure behavior utilizing the comprehensive information of the dense point of joint poles and the joint set orientations, both of which are obtained statistically, and the defect pattern of pole distribution has been developed. This method overcomes the potential incorrectness of the hemispheric projection method utilizing the joint set orientations only and also enhances the reliability of slope failure analysis. To this end a method capable of calculating the joint dispersion index directly from the joint pole distribution, instead of contour map, has been devised. The representative orientations for the slope failure analysis has been determined by considering the number and orientations of cone angle-dependent joint sets as well as the joint dispersion index. By engaging these representative orientations to the hemispheric projection analysis more reliable slope failure examination has been carried out. Sensitivity analysis for the potentially unstable slope of plane failure mode has been performed. Significance of joint strength index and the external seismic loading on the slope stability has been fully analyzed.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1226-1228
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• 1997

펄스 레이저 증착법을 이용하여 MgO 기판 위에 YBCO 박막을 c 축으로 성장시켰다. 이를 위하여 다양한 두께의 YBCO 박막을 여러 온도에서 증착시킴으로서 두께와 온도에 따른 YBCO 박막의 방향성을 조사하였다. 레이저원으로는 Nd:YAG 레이저의 355 nm의 파장을 이용하였으며, 증착시 기판온도는 $700^{\circ}C$와 $750^{\circ}C$에서 박막의 두께를 $3,000{\AA}$, $10,000{\AA}$, $20,000{\AA}$ 등으로 변화시켜 증착하였다. 이렇게 증착되어진 박막의 표면은 SEM으로 관촬되어졌으며, Raman Spectrascopy로 박막을 분석하였고, XRD를 사용하여 그 박막의 배향성을 연구하였다. 본 논문에서는 이와 같은 분석과 연구를 통하여 증착되어진 다성분 박막의 배향성이 기판온도와 박막두께에 따라 민감하게 변화함을 체계적으로 분석하였으며, 그 결과 기판온도와 박막 두께에 따른 YBCO 박막의 a 축, c 축 성장의 의존성을 확인하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2117-2123
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• 2014

To cope with the explosive growth of traffic which is considered as one of the most biggest threat to current mobile communication systems, various solutions such as small cell and device-to-device communication have been exploited. Directional transmission in which transmission power of base station is focused onto the direction where the mobile station is located, can be used to increase throughput of the system. In this work, we develop a system-level simulator for cellular mobile communication systems using directional transmission and adaptive interference estimation scheme for directional transmission has been proposed. By using the developed simulator, the performance of cellular mobile communication systems with directional transmission is examined. Moreover, it is shown that the overall throughput of cellular system can be improved by utilizing directional transmission.

• Economic and Environmental Geology
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• v.52 no.3
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• pp.231-241
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• 2019

Kinematic analysis determines the stability of rock slope by analyzing the relationship between the slope face orientation and the discontinuity orientation. In this study, terrestrial LiDAR was used to obtain a large amount of discontinuity orientation data and then, the probabilistic characteristics of the orientation data obtained using terrestrial LiDAR were analyzed. Subsequently, the probabilistic kinematic analysis was carried out using the discontinuity orientations generated randomly from Fisher function in Monte Carlo simulation. In addition, the probabilistic kinematic analysis was also performed using the actual orientation data obtained from the terrestrial LiDAR to compare their results. Consequently, the results of both probabilistic analyses showed similar results. Therefore, if sufficient orientation data are provided by other means such as terrestrial LiDAR, the probabilistic analysis will show reasonable results using the actual field data without randomly generating orientation data. In addition, the deterministic kinematic analysis was also carried out using representative orientation of discontinuity sets. The analysis result of the probabilistic analysis showed similar results with the deterministic analysis because the dispersion of the discontinuity orientations in a joint set is not large.

• Journal of Industrial Convergence
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• v.22 no.5
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• pp.1-10
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• 2024

This study proposes a developmental policy direction for the online platform industry, moving away from the regulatory-centered discussions that have predominated thus far. To offer policy directions, the PEST-SWOT-AHP analysis model was employed. The study first categorizes the issues of the domestic online platform industry into political, economic, social, and technological aspects, which are then further categorized into 16 strengths, weaknesses, opportunities, and threats. The relative importance among these factors was measured, leading to the derivation of four final strategies. The analysis indicates that policy directions should prioritize addressing weaknesses, with 'improving regulations that hinder innovation' being the most important factor across all categories, while technological factors were consistently rated highly in importance apart from this. Accordingly, the policy direction for the domestic online platform industry suggests avoiding excessive regulation and instead emphasizing policy support centered around technological development. This study is significant in that it presents a macroscopic developmental direction for online platform policies that have not been discussed in existing academic research, and it provides professional and objective indicators through consensus among scholars and researchers. In the future, it is hoped that research will continue to propose detailed policy strategies and implementation systems based on a macroscopic perspective.