• 한국농공학회논문집
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• 제53권6호
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• pp.111-119
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• 2011

The main objective of this study was to evaluate the effects of control-release fertilizer (CRF) on pollutant loadings from a small watershed. The Baran watershed, 386 ha in size, was selected as the study site, and the AGNPS (Agricultural Non-point Source Pollution) model was used to evaluate the effects of fertilizer types. Digital maps of digital elevation (DEM), slope distribution, channel, flow direction, landuse, soil, and curve number were extracted from the study watershed. Model parameters related to hydrology and water quality were calibrated and validated by comparing model predictions with the observed data collected for 2 years (1999 to 2000). Calibration and validation resulted in $R^2$ values of 0.75-0.91 for all the water quality parameters. All the paddy fields (21.2 %) of the study watershed were sprayed by either CRF or NPK (standard fertilizer). In CRF application, total nitrogen (TN) load was 4.9% less than NPK application, however total phosphorus (TP) load was 0.7 % more than NPK application. In CRF application, considering only paddy fields in the study area, TN load was 38.7 % less than NPK application. Using CRF in paddy fields could be one of the ways to reduce pollutant loadings from agricultural watersheds, however, in order to confirm it, more researches about effects of using CRF are necessary.

• 한국물환경학회지
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• 제36권2호
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• pp.98-108
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• 2020

The purpose of this study was to evaluate water quality in Hapcheon dam via using the Hydrological Simulation Program-Fortran (HSPF) model and applied livestock reduction scenarios. Hapcheon dam watershed input data for the HSPF model were established using the stream, land use, digital elevation map and meteorological data and others. The HSPF model was calibrated and validated using the observed water quality data from 2000 to 2016. For water quality simulation, we calculated the generated and discharge loads of the population, livestock, industry and land use following the guideline provided by the Ministry of Environment. The pollutant data were obtained from National Institute of Environmental Research (NIER). The monthly discharge load were estimated by applying the delivery rate. The calibration and validation results showed that the annual mean BOD had a difference of 0.22 mg/L and an error of ±13 %, T-N had a difference of 0.66 mg/L and an error of ±16 % and T-P had a difference of 0.027 mg/L and an error of ±13 %. In order to evaluate the nonpoint pollutants management effects, we applied livestock reduction scenarios because livestock consists of the largest portion of pollutants. As a result of the 20 % of livestock reduction, BOD, T-N and T-P decreased by 3 %, 1 % and 3 %, respectively. When 40 % of livestock reduction was applied, BOD, T-N and T-P decreased by 5 %, 3 % and 4 %, respectively. Based on the results of this study, effective pollutant management methods can be applied to improve the water quality and achieve the target water quality of Hapcheon dam watershed.

• 한국수자원학회논문집
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• 제42권10호
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• pp.877-889
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• 2009

본 연구에서는 SWAT(Soil and Water Assessment Tool) 모형을 이용하여 미래 기후변화가 충주댐 유역(6,585.1 km$^2$)의 하천수질에 미치는 영향을 분석하고자 하였다. 미래 기상자료는 IPCC에서 제공하는 A2, A1B, B1 배출시나리오를 포함하는 ECHAM5-OM 모형의 결과를 과거 30년(1977-2006, baseline period) 기후자료를 바탕으로 편이보정(bias correction)과 Change Factor Method로 Downscaling 하였다. 6년(1998-2003) 동안의 일별 유출량 및 월별 수질(SS, T-N, T-P) 자료를 이용하여 모형의 보정 및 검증을 실시한 후, Downscaling된 ECHAM5-OM의 A2, A1B, B1 시나리오에 대해 2020s, 2050s, 2080s로 대별되는 미래의 수문학적 거동 변화 및 하천수질 변화를 전망하였다.

• 한국항공우주학회지
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• 제38권3호
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• pp.221-227
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• 2010

일반적인 전술유도탄에서 표적획득 센서로 사용되는 김발형 탐색기(Gimballed Seeker) 는 탐색기의 표적획득부가 유도탄의 동체운동과는 독립적으로 관성좌표계 상에서 표적을 지향하게 하여 비례항법 유도명령 생성에 필요한 유도탄/표적간의 시선 각속도 정보를 직접 제공한다. 반면 최근에는 탐색기 전체가 유도탄 동체에 고정됨으로써 정비보수 용이, 고장수리 감소, 단가감소 측면 등에서 유리한 동체고정 탐색기(Strapdown Seeker)에 대한 연구가 부분적으로 수행되고 있다. 그런데 동체고정 탐색기에서는 비례항법에 필요한 시선각속도가 직접주어지지 않고 탐색기 영상 평면에 맺힌 표적영상으로부터 유도명령생성에 필요한 정보를 추출하여야 한다. 본 연구에서는 먼저 스트랩다운 탐색기로부터 주어지는 표적정보를 바탕으로 언센티드 칼만필터(Unscented Kalman Filter, UKF)를 적용하여 유도탄과 표적간의 상대운동을 추정한다. 추정된 상대운동 정보를 이용하여 유도명령을 생성하고 유도탄과 표적간의 조우운동을 시뮬레이션을 통하여 검증하였다.

• 한국의학물리학회지:의학물리
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• 제30권4호
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• pp.128-138
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• 2019

Purpose: Segmental analysis of volumetric modulated arc therapy (VMAT) is not clinically used for compositional error source evaluation. Instead, dose verification is routinely used for plan-specific quality assurance (QA). While this approach identifies the resultant error, it does not specify which machine parameter was responsible for the error. In this research study, we adopted an approach for the segmental analysis of VMAT as a part of machine QA of linear accelerator (LINAC). Methods: Two portal dose QA plans were generated for VMAT QA: a) for full arc and b) for the arc, which was segmented in 12 subsegments. We investigated the multileaf collimator (MLC) position and dosimetric accuracy in the full and segmented arc delivery schemes. A MATLAB program was used to calculate the MLC position error from the data in the dynalog file. The Gamma passing rate (GPR) and the measured to planned dose difference (DD) in each pixel of the electronic portal imaging device was the measurement for dosimetric accuracy. The eclipse treatment planning system and a MATLAB program were used to calculate the dosimetric accuracy. Results: The maximum root-mean-square error of the MLC positions were <1 mm. The GPR was within the range of 98%-99.7% and was similar in both types of VMAT delivery. In general, the DD was <5 calibration units in both full arcs. A similar DD distribution was found for continuous arc and segmented arcs sums. Exceedingly high DD were not observed in any of the arc segment delivery schemes. The LINAC performance was acceptable regarding the execution of the VMAT QA plan. Conclusions: The segmental analysis proposed in this study is expected to be useful for the prediction of the delivery of the VMAT in relation to the gantry angle. We thus recommend the use of segmental analysis of VMAT as part of the regular QA.

• 천문학회보
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• 제37권1호
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• pp.65.1-65.1
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• 2012

MIRIS (Multipurpose Infra-Red Imaging System) is the first Korean Infrared Space Telescope developed by KASI (Korea Astronomy and Space Science Institute), and is the main payload of STSAT-3 (Science and Technology Satellite-3). The FM (fight model) of MIRIS has been recently completed, and various performance tests have been made to measure system parameters such as readout noise, system gain, linearity, and dark current. Final thermal-vacumm test of the MIRIS and the vibration test of the electronics box have been performed. Band response tests showed good agreement with the initial design requirements. No significant dark difference was measured within the expected temperature variation range during observation in orbit. Using Pa-alpha band from a uniform source, the readout noise and system gain were measured by mean variance test. To obtain uniform flat image, flat fielding tests were made for each band, and the data will be compared to that obtained in orbit for calibration. The final version of MIRIS FM will be delivered in March, and it will be integrated into the satellite system for the AIT (Assembly Integration, Test) procedure. The launch of MIRIS is expected in November 2012.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.189-191
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• 2002

In the proton therapy using a gantry system, periodical verification of iso-center position is very important to assure precision of patient positioning system at any gantry angles in proton treatment. In the gantry system, there are three different types of iso-center; 1) in a geometrical view, 2) in an X-ray beam's eye view, 3) in a proton beam's eye view. Idealistically, they would be an identical point. They could, however, be different points. It may be a source of errors in patient positioning. At PMRC, we have established a system of verification for iso-center positions using a stainless ball of 2-cm in diameter and an imaging plate. This system provides the relation among a center of a patient target position, a center of proton irradiation field, and/or a center of X-ray field in accuracy of 50$\square$m in the 2) and 3) views, as images of a center of the stainless ball and a center of a 100 mm${\times}$100 mm-aperture brass collimator recorded on the imaging plate, which is setup at 1-cm behind the ball. In addition, it provides simultaneously the images of the ball and the collimator on an imaging intensifier (II), which is setup downstream of the proton or X-ray beam. We present a method of quality assurance (QA) for calibration of iso-center position in a rotation gantry system at PMRC and the performance of this system. A proton beam position on the 1$\^$st/ scatterer in the nozzle of the gantry affects less sensitive (reduced by a factor of 1/5) to the results of the iso-center position. The effect is systematically correctable. The effect of the nozzle (or the collimator) position is less than 0.5 mm at the maximum extraction (390 mm).

• 한국광학회지
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• 제14권1호
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• pp.97-102
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• 2003

이차원 표면 플라즈몬의 공명 흡수와 포토 마스크를 이용하여 11-MUA(11-Mercaptoundecanoic acid)와 11-MUOH(11-Mercaptoundecanol) 둥으로 이루어진 자기조립 단분자막(Self-Assembled Monolayer; SAM)의 다채널 영상을 얻었다. 통상의 Photoresist를 이용한 리토그래피 대신에 Thiol bonding의 광산화를 이용하여 패터닝 과정을 줄이고, 백색광 및 대역통과 필터(λ$_{0}$=633nm)를 이용하여 입사광으로써 레이저를 사용할 때 나타나는 간섭무늬를 줄였다. 이로부터 나타나는 이차원 영상의 명암을 정량적으로 보정하면 수 나노미터(nm) 두께의 변화를 측정할 수 있다. 또한 표면 플라즈몬 공명법은 국소화된 근접장 (소산장)을 이용하는 방법으로서, 통상 많이 이용되는 형광법 등에서 나타나는 광탈색(Photobleaching)이나 소광(Quenching) 현상이 없이 시료의 처리가 간단하고, 영상 신호의 시간에 따른 변화가 극히 적으며, 실시간으로 신호의 변화를 측정할 수 있다는 장점이 있다.

• 한국전자파학회논문지
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• 제23권10호
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• pp.1166-1172
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• 2012

본 논문에서는 상용 EM 시뮬레이션을 이용하여 안테나의 위상 응답 특성인 어레이 매니폴드를 계산하는 방법을 제안하고 실제 측정값과 비교하여 그 유효성을 검증하였다. EM 시뮬레이션을 적용하여 확보된 어레이 매니폴드는 point source에 의한 이상적인 이론값과 비교 시 안테나 자체와 안테나가 장착되는 플랫폼에 의한 영향을 정확히 계산할 수 있으며, 보정시 전계강도가 큰 주변의 FM/TV 등의 방송 신호나 다중 반사에 의한 왜곡 등을 배제시킬 수 있는 장점이 있다. 또한, 방향 탐지 시스템의 성능을 예측하기 위해서 세밀한 간격으로 수신 신호를 시뮬레이션하고 그 중 일부를 어레이 매니폴드로 적용한 후 파라볼릭 추정 방법을 이용하여 대상 신호원의 방향을 예측하는 방법을 제안하였다. 제안된 방법은 수신 신호의 SNR이 비교적 낮은 조건에서도 정확하게 측정 결과를 예측할 수 있어 방향 탐지 분야에 다양하게 활용될 수 있을 것으로 기대된다.

• Journal of Radiation Protection and Research
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• 제14권2호
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• pp.23-29
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• 1989

이중관 형태의 라돈 표준선원을 제작하여 루카스셀의 계수치 (cph)를 라돈농도로 나타내기 위한 환산인자를 측정한 결과 라돈 표준선원을 실온으로 하였을 때는 0.031$\pm$0.001 (pCi/l)/(cph/Cell)였다. 사무실 내에서 라돈과 라돈 자핵종의 농도를 측정한 값은 $^{222}Rn,\;{\rightarrow}^{218}Po\;{\rightarrow}^{214}Pb,\;{\rightarrow}^{214}Bi$ 의 평균 농도가 각각 0.87, 0.53, 0.35, 0.26 pCi/l 였다. 이때 전체 방사평형인자와 WL의 평균 값은 각각 0.40, 3.33${\times}10^{-3}$ 이며 측정 지점에서 연간 피폭되는 방사선량으로 환산하면 약 30 mren 이다.