• 대한원격탐사학회지
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• 제35권2호
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• pp.251-263
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• 2019

Sentinel-2 위성은 기존 Landsat 시리즈보다 높은 공간해상도, 시간해상도 및 13개의 가시광, Red-edge, 적외, 단파적외 영역을 포함하는 다중분광 영상을 제공하고 있다. 이는 Landsat 시리즈와의 비슷한 파장대역 구성으로 향후 Landsat 시리즈와 융합분석이 가능하다는 이점이 있다. 그 동안 Landsat 위성영상은 국내의 다양한 연구에 적용되고 있으나 Sentinel-2 광학 위성영상은 많은 활용 사례가 보고되지 않았다. Sentinel-2 광학 위성은 기존 Landsat 위성이 제공하는 Top-of-Atmosphere(TOA) 반사율 영상을 Level-1C(L1C)에서 제공하고 있으며, Level-2A(L2A)영상을 통해 Landsat 시리즈보다 한 단계 더 대기보정이 수행된 Bottom-of-Atmosphere(BOA) 반사율 영상을 제공할 예정에 있다. BOA 반사율 영상은 에어로졸 광학 두께(AOT: Aerosol optical thickness)와 대기 중 수증기(WV: Water Vapor) 자료를 Sentinel-2 영상으로부터 얻고 이를 보정하여 TOA 반사율 영상을 BOA 반사율 영상으로 변환을 가능하게 한다. 현재, 유럽 전역지역에서 L2A 자료를 무료로 다운로드 가능하며 이외 지역의 경우 L2A 자료의 실시간 제공이 예정되어 있다. 따라서, Sentinel-2 L2A 자료의 활용가능성이 국내에서 점점 커질 것으로 기대되는 바이며 농업지역에서 Sentinel-2 L2A 영상이 제공하는 BOA 반사율 자료의 활용가능성을 확인하기 위해 경상남도 합천군에서 촬영된 항공 초분광영상을 활용하여 Sentinel-2 L2A 자료를 모의해 보고 정량적인 분석을 통해 모의영상과 실제 촬영된 영상을 비교해보았다. 본 연구에서는 Sentinel-2 L2A 자료와 항공기 기반의 초분광 영상을 통해 모의된 Sentinel-2 영상에 대한 정량적인 비교를 수행하였으며, 가시광 영역대의 밴드와 식생지수에 대하여 참조 영상인 모의영상과 대기보정이 수행된 L2A 자료의 RMSE의 감소 및 상관관계의 증가 경향이 뚜렷하게 나타나는 것으로 확인되었다.

• 생물환경조절학회지
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• 제30권4호
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• pp.401-409
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• 2021

본 연구는 반밀폐형 토마토 재배 온실에서 광합성율 극대화를 위한 적정 탄산가스 시비 농도를 구명하고자 광합성 모델을 이용하여 잎의 최대 카복실화율(V_cmax), 최대 전자전달속도(J_max), 열파괴, 잎 호흡 등을 계산하고 실제 측정값과 비교하였다. 다양한 광도(PAR 200µmol·m^-2·s^-1 to 1500µmol·m^-2·s^-1)와 온도(20℃ to 35℃) 조건에서 CO₂ 농도에 대한 A-C_i curve는 광합성 측정 기기를 사용하여 측정하였고, 모델링 방정식으로 아레니우스 함수값(Arrhenius function), 순광합성율(net CO₂ assimilation, A_n), 열파괴(thermal breakdown), R_d(주간의 잎호흡)를 계산하였다. 엽온이 30℃ 이상으로 상승하였을 때 J_max, An 및 thermal breakdown 예측치가 모두 감소하였고, 예측 J_max의 가장 최고점은 엽온 30℃였으며 그 이상의 온도에서는 감소하였다. 생장점 아래 5번째 잎의 광합성율은 PAR 200-400µmol·m^-2·s^-1 수준에서는 CO₂ 600ppm, PAR 600-800µmol·m^-2·s^-1 수준에서는 CO₂ 800ppm, PAR 1000µmol·m^-2·s^-1 수준에서는 CO₂ 1000ppm, PAR 1200-1500µmol·m^-2·s^-1 수준에서는 CO₂ 1500ppm을 공급했을 때 포화점에 도달하였다. 앞으로 광합성 모델식을 활용하여 과채류 온실 재배 시 광합성을 높일 수 있는 탄산시비 농도를 추정할 수 있을 것으로 판단된다.

• Journal of Chest Surgery
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• 제37권3호
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• pp.245-251
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• 2004

심폐바이패스하 관상동맥우회술과 달리 심폐바이패스 없이 시행하는 관상동맥우회술의 경우 수술 후 혈액응고 기능이 항진되어 이식편의 혈전과 같은 문제가 발생되는 것이 우려된다. 비교연구를 통하여 심폐바이패스 없이 시행하는 관상동맥우회술 후 혈액응고기능이 항진되는지를 규명하고자 하였다. 2001년 11월부터 2002년 5월까지 관상동맥우회술을 시행받은 환자 중 심폐바이패스 없이 시행하는 관상동맥우회술을 시행받은 11명(I군, 연구군)과 같은 기간에 좌심실 심첨부와 중격의 무운동성으로 관상동맥우회술과 Dor 술식을 시행받은 11명의 환자들을(II군, 대조군)비교하였다. 술후 혈액응고기능이 항진되는지를 알아보기 위해 thromboelastography 검사를 수술 전, 술 후 1, 2, 3, 5일째 시행하여 r time, k time, $\alpha$ angle, MA값을 측정하였고 동시에 혈액응고기능검사, fibrinogen, D-dimer, protein S, protein C, antithrombin III, plasminogen, 혈소판 수 등을 시행하여 비교하였다. TEG검사의 각각의 변수값과 혈액응고기능검사 중 MA값, $\alpha$ angle, 혈소판수가 양 군 간 의미있는 차이를 보였다. MA값이 I군의 경우 술 후 3일과 5일째 140$\pm$72%와 153$\pm$98%로 증가하였으나 II군의 경우 87$\pm$27%와 78$\pm$28%로 감소하였다(p<0.05). $\alpha$ angle은 술후 3일째 I군이 122$\pm$92%로 증가하였고 II군이 69$\pm$23%로 감소하였다(p=0.09). 혈소판수는 술 후 3일째 I군이 63$\pm$55%였으며 II군이 33$\pm$13%였다(p<0.05). 심폐바이패스하 관상동맥우회술과 비교하여 심폐바이패스 없이 시행하는 관상동맥우회술의 경우 혈액응고기능이 항진되며 따라서 보다 적극적인 항응고치료의 필요성이 제기된다고 할 수 있다.

• 조명전기설비학회논문지
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• 제20권4호
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• pp.56-64
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• 2006

PM BLDC 전동기를 구동하려면 회전자 위치를 검출하는 센서가 필수적으로 요구된다. 그러나 주변 온도나 습도 등 작업 환경에 제한을 받는 곳에서는 센서의 고장 및 오동작으로 인한 전동기의 운전 정지 및 회전자 위치 검출오차에 의한 제어의 어려움이 발생할 수 있다. 따라서 3상 PM BLDC 전동기의 경우 3개의 센서를 이용하는 것이 일반적인 방법으로 사용되고 있지만 본 논문에서는 기존의 회전자 위치 검출 시 1개 또는 2개의 홀 센서만을 사용하여 기존의 방법과 동일한 성능을 가질 수 있는 알고리즘을 제안하였다. 그 결과 기존의 방법과 동일한 성능을 가지며 저가격, 보호회로 역할의 효과를 기대할 수 있다.

• Asian-Australasian Journal of Animal Sciences
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• 제8권3호
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• pp.275-280
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• 1995

The effect of supplemented high protein diet intake on renal urea regulation in swamp buffalo was carried out in the present experiment Five swamp buffalo heifers weighing between 208-284 kg were used for this study. The animals were fed with a supplementary high protein diet and renal function and kinetic parameters for urea excretion were measured. This was compared to a control period where the same animals had been fed only with paragrass and water hyacinth. For 2 months the same animals were fed a mixed of paragrass, water hyacinth plus 2 kgs of a high protein supplement (protein 18.2% DM basis) per head per day. In comparison to the control period, there were no differences in the rate of urine flow, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), plasma urea concentration and filtered urea. In animals supplemented with high protein intake mean values of urea clearance, excretion rate and the urea urine/plasma concentration ratio markedly increased (p < 0.05) while renal urea reabsorption significantly decreased from 40% to 26% of the quantity filtered. In this same study group urea space distribution and urea pool size increased which coincided with an increase in plasma volume (p < 0.05). Plasma protein decreased while plasma osmolarity increased (p < 0.05). Both urea turnover rate and biological half-life of $^{14}C$-urea were not affected by a supplementary high protein intake. The results suggest that animals supplemented with high protein diets are in a state of dynamic equilibrium of urea which is well balanced between urea excreted into the urine and the amount synthesized. The limitation for renal tubular urea reabsorption would be a change in extra-renal factors with an elevation of the total pool size of nitrogenous substance.

• Smart Structures and Systems
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• 제20권3호
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• pp.273-283
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• 2017

This paper presents and compares three feedback control strategies for active control of noise inside a 3-D vibro-acoustic cavity. These are a) control strategy based on direct output feedback (DOFB) b) control strategy based on linear quadratic regulator (LQR) to reduce structural vibrations and c) LQR control strategy with a weighting scheme based on structural-acoustic coupling coefficients. The first two strategies are indirect control strategies in which noise reduction is achieved through active vibration control (AVC), termed as AVC-DOFB and AVC-LQR respectively. The third direct strategy is based on active structural-acoustic control (ASAC). This strategy is an LQR based optimal control strategy in which the coupling between the various structural and the acoustic modes is used to design the controller. The strategy is termed as ASAC-LQR. A numerical model of a 3-D rectangular box cavity with a flexible plate (glued with piezoelectric patches) and with other five surfaces treated rigid is developed using finite element (FE) method. A single pair of collocated piezoelectric patches is used for sensing the vibrations and applying control forces on the structure. A comparison of frequency response function (FRF) of structural nodal acceleration, acoustic nodal pressure, and piezoelectric actuation voltage is carried out. It is found that the AVC-DOFB control strategy gives equal importance to all the modes. The AVC-LQR control strategy tries to consume the control effort to damp all the structural modes. It is seen that the ASAC-LQR control strategy utilizes the control effort more intelligently by adding higher damping to those structural modes that matter more for reducing the interior noise.

• 대한의생명과학회지
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• 제17권4호
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• pp.337-345
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• 2011

It is well recognized that conventional coronary artery bypass grafting (ONCAB) often leads to major organ dysfunction including renal injury. Diabetes mellitus is a major cause of nephropathy and poor clinical outcomes. The aim of this retrospective study was to evaluate the occurrence of adverse outcomes including renal impairment between diabetic (n=75, DM group) and non-diabetic patients (n=72, Non-DM group) underwent off-pump coronary artery bypass grafting surgery (OPCAB). Fasting glucose, hemoglobin A1c, fructosamine, fibrinogen and serum osmolality levels in the DM group were higher than those of the Non-DM group at pre-operative (Pre-OP) period ($P$ <0.05). History of hypertension and renal impairment in the DM group was higher than that of the Non-DM group ($P$ <0.05). Potassium ($K^+$), blood urea nitrogen and creatinine levels were higher, whereas sodium ($Na^+$) and glomerular filtration rate (GFR) levels were lower in the DM group than the Non-DM group at peri-operative period ($P$ <0.05). Fasting glucose levels at Pre-OP period had positive correlations with blood urea nitrogen and creatinine levels at peri-operative period, but negative correlations with GFR levels at peri-operative period in the DM group ($P$ <0.05). Incidences of renal impairment, diuretic therapy or continuous renal replacement therapy and fever in the DM group were higher than those of the Non-DM group at post-operative period ($P$ <0.05). These results suggest that blood glucose level should be tightly controlled at peri-operative period to avoid renal dysfunction in diabetic patients.

• The Journal of the Acoustical Society of Korea
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• 제25권3E호
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• pp.101-109
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• 2006

Besides dorsal-aspect target strength (TS) of the fish, side-aspect TS information is also acoustically important parameter in fisheries acoustics. In this study, the side-aspect TS of 11 black sea bream (Acanthopagurus schlegeli) were measured using a split beam echosounder of 120, 200, and 420 kHz; total length of the fish ranged from 12.4 to 23.7 cm, and wet weight from 27.5 to 229.8g. For the precise TS measurement with side-aspect angle, we used anesthetized and tethered specimens of known size while being rotated through $360^{\circ}C$ by means of a carousel structure. The side-aspect TS measurements of the fish were conducted by rotating the fish in the horizontal plane at 50 interval. The ping interval was 0.2 second and elapsed time at each angle was 30-60 second. As a result, the measured side-aspect TS data were fitted by sinusoidal function. The relationships between fish length and near full side-aspect TS were as follows: $TS_{120kHz}= 21.46 log (TL)-67.5 (r = 0.70), \;TS_{200 kHz}= 31.03 log (TL)-76.9 (r=0.83),\;TS_{420 kHz}= 30.79 log (TL)-72.2 (r = 0.77)$. For comparison, theoretically estimated side-aspect TS from the Kirchhoff ray mode (KRM) model, which based on swimbladder and body morphology, were compared with the measured TS.

• The Korean Journal of Ceramics
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• 제5권4호
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• pp.324-330
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• 1999

$Si_3N_4$-$TiB_2$ with 2 wt% $Al_2O_3$ and 4 wt% $Y_2O_3$ additives was hot pressed in a flowing $N_2$ environment with varying $TiB_2$ content from 10 to 50 vol%. Variations of mechanical (hardness, fracture toughness, and flexual strength), and tribological properties as a function of $TiB_2$ content were investigated. As the content of $TiB_2$ increased, relative density decreased due to the chemical reaction of $TiB_2$in $N_2$ environment. The reduction of density causes mechanical properties to be degraded with an increase of $TiB_2$ in $Si_3N_4$. Tribological properties were dependent of microstructure as well as mechanical properties, however, they were degraded strongly by the chemical reaction of $Si_3N_4$-$TiB_2$ during hot pressing in $N_2$ environment. SEM and TEM observations, and X-ray diffraction analysis that the chemical reaction products at the interface are TiCN, Si, and $SiO_2$. Also, the comparison of XRD patterns of the $Si_3N_4$-40 vol% $TiB_2$ composites hot pressed at $1,750^{\circ}C$ for 1 hour between in $N_2$ and in Ar gas was made. The XRD peaks of Si and $SiO_2$ were not found in Ar, but still a weak peak of TiCN was presented.

• Smart Structures and Systems
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• 제25권5호
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• pp.605-617
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• 2020

The existence of damages in structures causes changes in the physical properties by reducing the modal parameters. In this paper, we develop a two-stages approach based on normalized Modal Strain Energy Damage Indicator (nMSEDI) for quick applications to predict the location of damage. A two-dimensional IsoGeometric Analysis (2D-IGA), Machine Learning Algorithm (MLA) and optimization techniques are combined to create a new tool. In the first stage, we introduce a modified damage identification technique based on frequencies using nMSEDI to locate the potential of damaged elements. In the second stage, after eliminating the healthy elements, the damage index values from nMSEDI are considered as input in the damage quantification algorithm. The hybrid of Teaching-Learning-Based Optimization (TLBO) with Artificial Neural Network (ANN) and Particle Swarm Optimization (PSO) are used along with nMSEDI. The objective of TLBO is to estimate the parameters of PSO-ANN to find a good training based on actual damage and estimated damage. The IGA model is updated using experimental results based on stiffness and mass matrix using the difference between calculated and measured frequencies as objective function. The feasibility and efficiency of nMSEDI-PSO-ANN after finding the best parameters by TLBO are demonstrated through the comparison with nMSEDI-IGA for different scenarios. The result of the analyses indicates that the proposed approach can be used to determine correctly the severity of damage in beam structures.