• 한국지진공학회논문집
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• 제24권1호
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• pp.49-57
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• 2020

In this study earthquake records were collected for rock conditions that do not reflect seismic amplification by soil from global earthquake databases such as PEER, USGS, and ESMD. The collected earthquake records were classified and analyzed based on the magnitude and distance of earthquakes. Based on the analyzed earthquakes, the design response spectrum shape, effective ground acceleration, and amplification ratios for each period band are presented. In addition, based on the analyzed data, the story shear force for 5F, 10F, 15F, and 20F were derived through an analysis of the elastic time history for multi-DOF structures. The results from analyzing the rock earthquake record show that the seismic load tends to be amplified greatly in the short period region, which is similar to results observed from the Gyeongju and Pohang earthquakes. In addition, the results of the multi-DOF structure analysis show that existing seismic design criteria can be underestimated and designed in the high-order mode of short- and medium-long cycle structures.

• Journal of Astronomy and Space Sciences
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• 제25권4호
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• pp.395-404
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• 2008

태양활동프록시(proxies)와 지구연평균 기온아노말리 시계열을 이용하여 기후변화에서 태양활동신호를 찾아보았다. 이를 위해 Lomb & Scargle의 피어리드그램(Periodgram)을 이용하여 태양활동프록시와 기온아노말리 시계열을 주기분석하였다. 또한 EMD(Empirical Mode Decomposition)과 MODWR MRA(Maxial Overlap Discrete Wavelet Transform Multi Resolution Analysis)를 적용하여 두 시계열을 성분분해하고 이들 중 비슷한 주기의 특성을 보이는 성분을 비교하였다. 태양활동프록시는 짧의 주기의 파워가 긴 주기의 파워에 비해서 큰 반면 기온아노말리는 긴 주기에서 더 큰 파워를 보였다 EMD에 의한 성분분해 결과는 약40년보다 긴 주기성을 갖는 성분을 분해해 낼 수 없었지만 잔차 성분은 비교할 수 있었다. MRA에 의한 성분분해를 통해 지구연평균 기온아노말리 시계열에서 태양활동의 변화에 의한 신호를 찾아내었다. 1960년부터 2007년까지 기온상승에 대한 태양의 기여도는 39%로 계산되었다. 기후민감성은 출력신호의 진폭에만 관계하여 기후시스템이 간단한 2계미분방정식으로 근사될 수 있는 가능성에 대해 토의하였다.

• 천문학회보
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• 제38권2호
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• pp.74.2-74.2
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• 2013

Recent spectroscopic observations have provided evidences for the multiple stellar populations having different abundances in some massive globular clusters (GCs). In particular, some of these GCs show clear separations of red giant-branches (RGBs) in calcium narrow band photometry. In order to confirm the differences in heavy element abundances and radial velocities among multiple RGBs, we have performed the low-resolution spectroscopy for the RGB stars in these GCs. The spectral data were taken from the multi-object spectroscopic mode with WFCCD mounted on the du Pont 2.5m telescope in Las Campanas Observatory. In this talk, we will present our progress in the spectroscopic analysis of the RGB stars in these GCs.

• 한국지진공학회논문집
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• 제24권4호
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• pp.169-178
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• 2020

In a previous paper, ambient vibration tests were conducted on a cable stayed bridge with resilient-friction base isolation systems (R-FBI) to extract the dynamic characteristics of the bridge and compare the results with a seismic analysis model. In this paper, a nonlinear seismic analysis model was established for analysis of the bridge to compare the difference in seismic responses between nonlinear time history analysis and multi-mode spectral analysis methods in the seismic design phase of cable supported bridges. Through these studies, it was confirmed that the seismic design procedures of the "Korean Highway Bridge Design Code (Limit State Design) for Cable Supported Bridges" is not suitable for cable supported bridges installed with R-FBI. Therefore, to reflect the actual dynamic characteristics of the R-FBI installed on cable-supported bridges, an improved seismic design procedure is proposed that applies the seismic analysis method differently depending on the seismic isolation effect of the R-FBI for each seismic performance level.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.229-234
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• 2002

Under the hostile influence of the extreme space environmental conditions due to the deep space and direct solar flux, the thermal control in space applications is especially of major importance. There are tight temperature range restrictions for electro-optical elements while on the other hand there are low power consumption requirements due to the limited energy sources on the spacecraft. So, we usually have strong requirement of thermal and power control module in space applications. In this paper, the design concept of a thermal and power control module in the MSC(Multi-Spectral Camera) system which will be a payload on KOMPSATII is described in terms of H/W & S/W. This thermal and power control module, called THTM(Thermal and Telemetry Module) in MSC, resides inside the PMU(Payload Management Unit) which is responsible for the proper management of the MSC payload for controlling and monitoring the temperature insides the EOS(Electro-Optic System) and gathering all the analog telemetry from all the MSC sub-units, etc. Particularly, the designed heater controller has the special mode of "duty cycle" in addition to normal closed loop control mode as usual. THTM controls heaters in open loop according to on/off set time designed through analysis in duty cycle mode in case of all thermistor failure whereas it controls heaters by comparing the thermistor value to temperature based on closed loop in normal mode. And a designed THTM provides a checking and protection method against the failure in thermal control command using the test pulse in command itself.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.216-219
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• 2004

In this study, the concept and techniques to generate the level lA, lB and 2A image products have been reviewed. In particular, radiometric and geometric corrections and bands registration used to generate level lA, lB and 2A products have been focused in this study. Radiometric correction is performed to take into account radiometric gain and offset calculated by compensating the detector response non-uniformity. And, in order to compensate satellite altitude, attitude, skew effects, earth rotation and earth curvature, some geometric parameters for geometric corrections are computed and applied. Bands registration process using the matching function between a geometry, which is called 'reference geometry', and another one which is corresponds to the image to be registered is applied to images in case of multi-spectral imaging mode. In order to generate level-lA image products, a simple radiometric processing is applied to a level-0 image. Level-lB image has the same radiometry correction as a level-lA image, but is also issued from some geometric corrections in order to compensate skew effects, Earth rotation effects and spectral misregistration. Level-2A image is generated using some geo-referencing parameters computed by ephemeris data, orbit attitudes and sensor angles. Level lA image is tested by visual analysis. The difference between distances calculated level 1 B image and distances of real coordinate is tested. Level 2A image is tested Using checking points.

• 한국통신학회논문지
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• 제34권11A호
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• pp.831-843
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• 2009

본 논문에서는 기존의 협력 기법보다 뛰어난 성능과 주파수 효율을 얻을 수 있는 다중 릴레이 노드를 이용한 새로운 적응형 협력기법을 제안한다. 릴레이 선택은 K개의 릴레이 중 가장 뛰어난 채널 상태를 가진 잠재적 릴레이를 선택하는데 이용된다. 소스와 목적지, 소스와 릴레이, 릴레이와 목적지사이 채널의 순시 신호 대 잡음 비를 고려하여 적응형 협력 또는 비 협력 여부를 결정한다. 본 논문에서 제안하는 적응형 프로토콜은 만일, 직접 통신의 채널 상태가 복호 후 전달 기법보다 양호하다면 소스는 가용한 전력으로 목적지로 신호를 전달하며, 그렇지 않다면 소스는 저전력으로 모든 릴레이에게 신호를 브로드캐스트하며, 릴레이의 올바른 복호를 가정할 시 릴레이는 신호를 복호한 후 다시 목적지로 전송하게 된다. 그리고 소스는 남은 전력으로 신호를 전송한다. 본 논문에서는 우선 확률적 계산을 통해 주파수 효율성을 보이며, 릴레이 선택을 통한 적응형 협력 기법의 BER성능 분석을 한다. 최종적으로 수식적 결과를 통해 본 논문에서 제안하는 기법의 성능 향상을 검증한다.

• 한국자동차공학회논문집
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• 제20권3호
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• pp.119-125
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• 2012

Caliper intergrated Electric Parking Brake (EPB) is an automatic parking brake system, attached to rear caliper. Because EPB uses luxury vehicles recently, the drivers of vehicles are sensitive to the EPB noise. EPB is operated by the motor and gear, so noise is generated by motor and gear. In order to reduce noise, One of EPB manufacturers uses helical gear and changes the shape of EPB housing. But these methods are not optimized for reduction of interior noise. There are many noise transfer paths into vehicle interior and it is difficult to identify the noise sources. Therefore, in this study, we performed contribution analysis and modal testing in the vehicle system. It is possible to distinguish between air-borne noise and structure-borne noise in the vehicle interior noise by comparing interior noise peak with resonance mode map.

• 한국지반공학회논문집
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• 제33권4호
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• pp.47-56
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• 2017

잔교식 안벽의 내진설계는 보통 다중모드 스펙트럼 해석과 같은 단순 동해석 방법을 적용하여 수행된다. 이러한 단순 해석법은 구조물의 한계상태를 평가하는데 유용할 수 있다. 그러나, 과거에 발생한 잔교식 안벽의 지진피해사례를 살펴보면, 기초지반의 변형 또는 지반-말뚝 사이의 동적 상호작용이 구조물의 전체 거동에 큰 영향을 미치는 것으로 나타났다. 이러한 거동은 지반-말뚝-구조물 동적 상호작용을 정밀하게 모사할 수 있는 비선형 유효응력 해석을 수행하여 평가할 수 있다. 본 연구에서는 잔교식 안벽의 내진성능을 평가할 수 있는 3차원 수치 모델링 기법을 선정하고, 이를 Hyogoken Nambu 지진(1995)시 고베항의 잔교식 안벽 피해사례에 적용하여 그 적용성을 검증하였다. 해석결과, 본 연구에서 적용한 수치 모델링 기법이 안벽의 지진피해 거동을 잘 모사할 수 있으며, 지반의 과잉간극수압증가 및 지반-구조물과의 동적 상호작용이 안벽의 지진거동에 큰 영향을 주는 것으로 나타났다.

• 천문학회보
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• 제44권2호
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• pp.68.1-68.1
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• 2019

Turbulence plays a crucial role in controlling star formation as it produces density fluctuation as well as non-thermal pressure against gravity. Therefore, turbulence controls the mode and tempo of star formation. However, despite a plenty of previous studies, the properties of turbulence remain poorly understood. As part of the Taeduk Radio Astronomy Observatory (TRAO) Key Science Program (KSP), "mapping Turbulent properties In star-forming MolEcular clouds down to the Sonic scale (TIMES; PI: Jeong-Eun Lee)", we mapped the Orion A and the Ophiuchus clouds, in three sets of lines (13CO 1-0/C18O 1-0, HCN 1-0/HCO+ 1-0, and CS 2-1/N2H+ 1-0) with a high-velocity resolution (~0.1 km/s) using the TRAO 14-m telescope. The mean Trms for the observed maps are less than 0.25 K, and all these maps show uniform Trms values throughout the observed area. These homogeneous and high signal-to-noise ratio data provide the best chance to probe the nature of turbulence in two different star-forming clouds, the Orion A and Ophiuchus clouds. We present comparisons between the line intensities of different molecular tracers as well as the results of a Principal Component Analysis (PCA).