• 한국음향학회지
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• 제33권2호
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• pp.118-125
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• 2014

역문제에 기반한 음향 온도 측정법에서는 단면의 음속 분포 계산이 필수적이며, 이를 위하여 단면 외곽에 위치한 센서들 간의 지연시간을 계측하고, 이를 입력으로 하는 전달행렬과 계수 벡터를 이용한 역문제를 이용하여 음속 분포를 예측한다. 그러나, 센서 개수의 부족으로 인하여 충분한 수의 음향 경로가 확보되지 못하면, 지연시간 벡터의 개수가 한정될 수 있다. 지연시간 벡터의 개수는 공간 해상도와 관련 있으며, 부족한 지연시간 벡터의 개수는 공간 해상도의 저하를 초래하여 정확한 온도 재구성 결과를 얻지 못할 수 있다. 본 연구에서는 이 문제를 해결하기 위하여, 실제 측정된 지연시간으로부터 온도장을 재구성 한 뒤, 임의의 경로에 해당하는 지연시간을 재구성 된 온도장으로부터 재형성하여 지연시간 벡터의 개수를 증가시켰다. 측정된 지연시간 벡터와 재형성 된 지연시간 벡터를 함께 사용할 경우, 음향 경로의 개수가 증가하므로 공간 분해능의 향상을 기대할 수 있다. 임의의 온도 분포를 가지는 2차원 단면을 수치 예제로서 채택하였고, 측정된 지연시간만을 이용한 결과와 재형성 된 지연시간을 함께 사용한 재구성 결과를 비교하였다. 그 결과, 재형성 된 지연시간과 측정된 지연시간을 함께 사용한 경우의 온도 재구성 오차가 측정된 지연시간만을 사용한 온도 재구성 오차보다 최대 15 % 감소하였다.

• 한국측량학회지
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• 제25권2호
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• pp.133-140
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• 2007

본 연구는 도시 발전에 따른 여러 가지 도시문제들을 예측하고 대처하기 위해 도시내 토지형태가 어떻게 변화되었는지 모니터하였다. 충주시가 촬영된 Landsat 위성영상을 대상으로 도로주변의 피복상태를 분석하고, 그 분포양상을 시계열로 비교분석하여 변화량을 계산하였다. 이를 위해 원격탐사의 공간분석기술과 GIS기술을 통합하여, 시각적으로 두 시기의 영상을 판독하고 정량적 면적변화를 추출하였다. 그 결과 위성자료와 지형공간정보들의 지속적인 분석과 통계분석을 통하여 도심지역의 발전 모형을 생성 할 수 있었다.

• 대한지리학회지
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• 제38권
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• pp.61-74
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• 1988

Changing patterns of population densities in urban centers are different between Western countries and non-Western countries. Although Seoul is located in a non-Western country, the result of this study shows that its pattern of population density falls into the category of Western cities. Through the examination of three population density gradient models, it is clear that no model can precisely explain the population distribution of Seoul over time. Some of the models partly indicate the actual population distrisbution. The Clark model is appropriate to denote population distribution in the center of Seoul at an early stage in development. The Sherratt model cannot adequately explain the population distribution of Seoul.

• Journal of Magnetics
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• 제5권3호
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• pp.81-84
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• 2000

A magneto-optical microscope magnetometer (MOMM) has been developed to simultaneously measure 2-dimensional array hysteresis loops of each local area of $320\times320-nm^2$ spots on ferromagnetic films, in addition to grabbing time-resolved domain evolution patterns. Using the system, spatial distribution of local coercivity can be quantitatively generated and then, compared directly with domain patterns grabbed at precisely the same position of a sample. It is clearly demonstrated that local coercivity distribution governs domain reversal behavior via a thermally activated relaxation process.

• 대한지리학회지
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• 제42권6호
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• pp.863-878
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• 2007

쯔쯔가무시증 환자 발생의 시 공간적 분포를 기후, 서식환경 변화 등 환경생태요인과 관련하여 질병지리적 측면에서 분석하였다. 쯔쯔가무시증은 1951년에 보고된 뒤 1986년에 재발했고, 1998년과 2004년부터 급증하였다. 계절별로는 11월(58%)과 10월(33.2%)에 주로 노인층에서 발병한다. 남부평야지대에 발생하던 쯔쯔가무시증은 점차 동부산지지대를 제외한 전국으로 확산되었으며, 경기도 화성시는 발병자가 급증한 대표지역이다. 발병자가 급증한 것은 기후와 토지이용 변화 등 환경생태요인이 복합적으로 작용한 결과로 본다. 전국적으로는 연평균기온이 상승하고 연평균강수량이 감소하면서 쯔쯔가무시증 환자가 증가하였다. 그러나 사례 조사지역인 화성시, 합천군 등에서는 여름철 기온이 상승하고 강수량 많은 해에 환자가 증가했다. 여름에 기온이 높고 상대적으로 건조하면 식생이 무성해져 털진드기의 생장과 번식이 활발해진다. 이어서 가을이 온화해지면서 털진드기 활동이 활발해지면서 환자가 급증한 것으로 본다. 농촌에서 환자가 많은 것은 1980년대 이후 토지이용 변화에 따라 마을과 경작지 주변에 늘어난 관목숲, 풀숲을 중심으로 쯔쯔가무시증의 매개체인 들쥐류와 털진드기가 번성하면서 질병을 확산시킨 결과로 본다.

• 천문학회지
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• 제28권2호
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• pp.245-253
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• 1995

We have analyzed the time series of Ca II H,K and ${\lambda}8498$ line profiles taken for a sunspot (SPO 5007) with the Echelle spectrograph attached to Vacuum Tower Telescope at Sacramento Peak Solar Observatory. Each set of spectra was taken simultaneously for 20 minutes at a time interval of 30 seconds. A total of 40 photographic films for each line was scanned by a PDS at Korea Astronomy Observatory. The central peak intensity of Ca II H ($I_{max}$), the intensity measured at ${\Delta}{\lambda}=-0.1{\AA}$ from the line center of ${\lambda}8498(I_{{\lambda}8489})$, the radial velocity ($V_r$) and the Doppler width (${\Delta}{\lambda}_D$) estimated from Ca II H have been measured to study the dynamical behaviors of the sunspot chromosphere. Fourier analysis has been carried out for these measured quantities. Our main results are as follows: (1) We have confirmed the 3-minute oscillation being dominant throughout the umbra. The period of oscillations jumps from 180 sec in the umbra to 500 to 1000 sec in the penumbra. (2) The nonlinear character of the umbral oscillation is noted from the observed sawtooth shaped radial velocity fluctuations with amplitudes reaching up to $5{\sim}6\;km/sec$. (3) The spatial distribution of the maximum powers shows that the power of oscillations is stronger in the umbra than in the penumbra. (4) The spatial distributions of the time averaged < $I_{max}$ > and < $V_r$ > across the spot are found to be nearly axially symmetric, implying that the physical quantities derived from the line profiles of Ca II H and ${\lambda}8498$ are inherently associated with the geometry of the magnetic field distribution of the spot. (5) The central peaks of the CaII H emission core lead the upward motions of the umbral atmosphere by $90^{\circ}$, while no phase delay is found in intensities between $I_{max}$ and $I_{{\lambda}8498}$, suggesting that the umbral oscillation is of standing waves.

• Smart Structures and Systems
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• 제21권5호
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• pp.549-559
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• 2018

The dynamic behaviors of the bridge structures have great effects on the comfortability and safety of running high-speed trains, which can also reflect the structural degradation. This paper aims to reveal the characteristics of the dynamic behaviors induced by train loadings for a combined highway and railway bridge. Monitoring-based analysis of the acceleration and dynamic displacement of the bridge girder is carried out. The effects of train loadings on the vertical acceleration of the bridge girder are analyzed; the spatial variability of the train-induced lateral girder displacement is studied; and statistical analysis has been performed for the daily extreme values of the train-induced girder deflections. It is revealed that there are great time and spatial variabilities for the acceleration induced by train loadings for the combined highway and railway cable-stayed bridge. The daily extreme values of the train-induced girder deflections can be well fitted by the general extreme value distribution.

• 한국공간구조학회논문집
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• 제17권3호
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• pp.35-43
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• 2017

The Hong Nang Sida temple is a cultural heritage that must be preserved due to the historical and cultural values that are highly evaluated in the world. The main sanctuary of Hong Nang Sida temple, presumed to have been built in 11th to 12th centuries, has been exposed in the open air for a long time after the collapse. Therefore, it is necessary to reconstruct the original shape of the Hong Nang Sida temple to reflect the original shape. To do this, it is necessary to examine the overall structure according to the restoration shape. For this purpose, this study analyzes the construction and configuration types for main sanctuary Mandapa of Hong Nang Sida temple, and conducts structural modeling according to actual and restoration plans. The structural and behavioral characteristics are analyzed by comparing stress and displacement values by measurement locations. In addition, we will examine the vertical load distribution by the layers of each wall and cobel arch of the Mandapa using the load distribution method.

• Water Engineering Research
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• 제2권1호
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• pp.49-61
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• 2001

A grid-based KIneMatic wave soil-water EROsion and deposition Model(KIMEROM) that predicts temporal variation and spatial distribution of sediment transport in a watershed was developed. This model uses ASCII-formatted map data supported from the regular gridded map of GRASS (U.S. Army CERL, 1993)-GIS(Geographic Information Systems), and generates the distributed results by ASCII-formatted map data. For hydrologic process, the kinematic wave equation and Darcy equation were used to simulated surface and subsurface flow, respectively (Kim, 1998; Kim et al., 1998). For soil erosion process, the physically-based soil erosion concept by Rose and Hairsine (1988) was used to simulate soil-water erosion and deposition. The model adopts single overland flowpath algorithm and simulates surface and subsurface water depth, and sediment concentration at each grid element for a given time increment. The model was tested to a 162.3 $\textrm{km}^2$ watershed located in the tideland reclaimed ares of South Korea. After the hydrologic calibration for two storm events in 1999, the results of sediment transport were presented for the same storm events. The results of temporal variation and spatial distribution of overland flow and sediment areas are shown using GRASS.

• Journal of Information Display
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• 제12권1호
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• pp.23-27
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• 2011

The correlation between the temporal and spatial variations of the elastic constant and temperature change was examined for a light guide plate (LGP) adopted in the edge-lit light-emitting-diode backlight for mobile applications, using the micro- Brillouin light scattering method. The velocity of sound and the elastic constant $C_{11}$ of an LGP made from bisphenol-A polycarbonate (PC) were investigated as functions of temperature, time, and position on the LGP. The temporal variation of $C_{11}$ exhibited an exponential decay, while the spatial variation of $C_{11}$ reflected the temperature distribution on the LGP. The glass transition temperature of the PC LGP was found to be located at $155^{\circ}C$. The result showed that systematic transformation between the elastic property and the temperature is possible and that the temperature distribution on the bulk LGP can be accurately probed via the present experiment method, without using any special temperature measurement equipment.