• 한국항행학회논문지
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• 제14권4호
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• pp.545-552
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• 2010

본 논문에서는 산업체 공장 환경에서 예기치 않은 장애로 인해 발생하는 심각한 오류 원인을 정확히 판단하기 위한 다중 센싱 인터페이스 모듈과 다중 센싱 데이터의 신뢰성을 보장하기 위한 전송 신뢰성 향상방안에 대해 연구하였다. 다중 센싱 인터페이스 모듈에서는 여러 센서들로부터의 데이터를 획득하기 위해 USART, TWI, ADC, GPIO-I2C 통신 드라이버를 구현하였으며, 전송 신뢰성 향상방안으로는 (31, 23) reed-solomon 코드를 사용하였다. 이 시스템을 거리 $5m{\times}15m$ 실내 환경에서 실험한 결과 RS 코드를 사용하지 않은 시스템보다 약 5배 정도 신뢰성이 증가됨을 확인하였다. 이 결과들을 통해 산업 자동화 장비의 오류원인을 진단하기 위해 다중 센싱 인터페이스 모듈이 적합함을 증명하였다.

• 한국산업융합학회 논문집
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• 제25권6_3호
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• pp.1147-1154
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• 2022

Now that the development of autonomous driving is progressing, LiDAR has become an indispensable element. However, LiDAR is a device that uses lasers, and laser side effects may occur. One of them is the much-talked-about eye-safety, and developers have been satisfying this through laser characteristics and operation methods. But eye-safety is just one of the problems lasers pose. For example, irradiating a laser with a specific energy level or higher in a dusty environment can cause deterioration of the dust particles, leading to a sudden explosion. For this reason, the dust ignition proof regulations clearly state that "a source with a pulse period of less than 5 seconds is considered a continuous light source, and the average energy does not exceed 5 mJ/mm 2 or 35 mW" [2]. Energy of output optical power is limited by the law. In this way, the manufacturer cannot define the usage environment of the LiDAR, and the development of a LiDAR that can be used in such an environment can increase the ripple effect in terms of use in application fields using the LiDAR. In this paper, we develop a LiDAR with low optical power that can be used in environments where high power lasers can cause problems, evaluate its performance. Also, we discuss and present one of the directions for the development of LiDAR with laser power limited by dust ignition proof regulations.

• Transactions on Electrical and Electronic Materials
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• 제16권2호
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• pp.78-81
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• 2015

Pure ZnO and ZnO nanowires doped with 3 wt.% Ga (‘3GZO’) were grown by pulsed laser deposition in a furnace system. The doping of Ga in ZnO nanowires was analyzed by observing the optical and chemical properties of the doped nanowires. The diameter and length of nanowires were under 200 nm and several ${\mu}m$, respectively. Changes of significant resistance were observed and the sensitivities of ZnO and 3GZO nanowires were compared. The sensitivities of ZnO and 3GZO nanowire sensors measured at 300℃ for 1 ppm of ethanol gas were 97% and 48%, respectively.

• 한국군사과학기술학회지
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• 제15권4호
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• pp.442-449
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• 2012

Cognitive Radio(CR) is the technology that allocates the frequency by using dynamic spectrum access. We proposed a model to calculate the optimal level of the cognitive radiotelegraph, where secondary users opportunistically share the spectrum with primary users through the spectrum sensing. When secondary user with cognitive radio detects the arrival of a primary user in its current channel, the secondary user moves to the idle channel or be placed in the virtual queue. We assume that the primary users have finite buffers and the population of secondary users is finite. Using a two-dimensional Makov model with preemptive priority queueing, we could derive the blocking and waiting probability as well as the optimal level of cognitive radiotelegraph under a various range of parameter circumstances.

• 대한원격탐사학회지
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• 제32권6호
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• pp.741-746
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• 2016

알베도는 태양에너지의 흡수량을 결정하는 주요 기후 변수 중 하나로서, 이러한 알베도를 산출하는 것은 기후 변화 연구에 있어 중요한 과정이다. 이 때, 산출된 알베도 자료를 효율적으로 사용하기 위해서는 높은 공간해상도와 장기간의 일관성 있는 산출이 중요하게 고려된다. 따라서 본 연구에서는 Landsat 8을 기반으로 Landsat 7과의 일관성을 유지한 고해상도 지표면 광대역 알베도를 산출하였다. 먼저, Landsat 7과 Landsat 8의 채널 별 일관성을 분석한 결과, 상관계수(R)가 평균 0.96으로 높은 상관성을 보였다. 이러한 결과를 바탕으로 Landsat 7 알베도와 Landsat 8 반사도 채널 자료를 다중회귀분석에 적용하여 Landsat 8 광대역 알베도 전환 식을 도출하였다. 도출된 식을 통해 Landsat 8 지표면 광대역 알베도를 산출하고, Landsat 7 알베도 자료와 비교하여 검증하였다. 그 결과 R-square($R^2$)가 0.89, Root Mean Square Error (RMSE)가 0.003의 높은 정확도를 보였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.374-377
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• 2007

Dual-channel Radiometers for Earth and Atmosphere Monitoring (DREAM) was developed as the Korean first spaceborne microwave radiometer for earth remote sensing. It is the main payload of the Science and Technology SATellite-2 (STSAT-2). STSAT-2 will be launched by Korea Space Launch Vehic1e-l (KSLV-1) at NARO Space Center in Korea in 2008. The DREAM is a two-channel, total power microwave radiometers with the center frequencies of 23.8 GHz and 37 GHz. The bandwidths of radiometer are 600 MHz at 23.8 GHz and 1000 MHz at 37 GHz. The integration time is 200 ms and the required sensitivity is less than 0.5 K. In this paper, we summarize the specification and performance of the developed DREAM firstly. And we describe system integration and performance test of DREAM mounted on spacecraft.

• 대한원격탐사학회지
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• 제36권2_2호
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• pp.277-292
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• 2020

본 연구에서는 천수만 황도 갯벌 지역을 대상으로 UAV 자료와 객체기반영상분석 방법을 사용하여 대축척 갯벌 표층 퇴적상 분류도를 작성하고, 정확도 검증을 수행하여 정밀한 표층 퇴적상 분류의 가능성과 보다 정확한 분류 방법에 대해 제시하였다. 이를 위해 고해상도 UAV 자료에서 가시광 영역의 정사영상과 수치표고모델(DEM), 조류로 밀도 등 퇴적상 분류 시 영향을 주는 요인들을 추출하고, 통계학적 분석 방법을 통해 퇴적상에 따른 요인들의 주성분을 분석하였다. 주성분 요인을 바탕으로 퇴적상 분류 시 사용할 입력 자료를 (1) 가시광 영역의 스펙트럼, (2) 지형 고도와 조류로 밀도, (3) 가시광 영역의 스펙트럼과 지형 고도 및 조류로 밀도로 구분하였으며, 이를 기반으로 객체기반영상분석 분류방법에 입력 자료를 적용하여 대축척 갯벌 표층 퇴적상 분류도를 추출하였다. 입력 자료의 조건에 따라 표층 퇴적상 분류를 수행한 결과, folk 분류 기준을 따르는 6가지의 표층 퇴적상으로 분류하였고, 가시광 영역의 스펙트럼과 지형 고도, 조류로 밀도를 사용할 경우 전체 정확도가 63.04%, Kappa 지수가 0.54로 가장 효과적으로 표층 퇴적상을 분류하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2019년도 춘계학술발표대회
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• pp.82-85
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• 2019

An adaptive power control scheme is proposed for the cognitive relay networks with joint overlay and underlay spectrum sharing model. The transmit power of the secondary user is adjusted adaptively according to the spectrum sensing results and the interference channel condition. The outage probability of the secondary user is compared by Monte - Carlo simulations between the fixed power control scheme and pure overlay or underlay spectrum sharing schemes. The results show that, by employing the adaptive power control strategy, the interference probability of the secondary user to the primary user is decreased by 70 % ~ 80 % under the same outage probability. Also, the outage probability of the secondary user is reduced by 1 ~ 2 orders of magnitude under the same interference probability. Thus, the performance of the spectrum sharing is improved effectively.

• 대한원격탐사학회지
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• 제15권4호
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• pp.321-327
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• 1999

As an example of many possible applications of OSMI data, we present a method to detect red tides. In Korean waters, red tides usually occur in the South Sea where the turbidity is usually high due to strong tidal mixing in the shallow sea. The conventional case 1 chlorophyll algorithm cannot be applied since it cannot distinguish chlorophyll from SS (suspended sediments). In October 1998, a red tide outbreak occurred off the coast of KunSan. We analyzed the SeaWiFS data of the outbreak. The standard SeaWiFS chlorophyll algorithm OC-2 was poor in identifying the red tides. However, comparison of spectra of normalized water-leaving radiance indicates that red tide pixels can be distinguished from sediment-laden pixels. Channel 443 and 555 were effective in showing the spectral characteristics. We suggest K490 algorithm as an example in summarizing the information of the spectra and thereby in distinguishing the red tide pixels. Further development is desirable.

• Molecules and Cells
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• 제19권2호
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• pp.268-278
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• 2005

We investigated the effect of cytosolic and extracellular $Ca^{2+}$ on $Ca^{2+}$ signals in pancreatic acinar cells by measuring $Ca^{2+}$ concentration in the cytosol($[Ca^{2+}]_c$) and in the lumen of the ER($[Ca^{2+}]_{Lu}$). To control buffers and dye in the cytosol, a patch-clamp microelectrode was employed. Acetylcholine released $Ca^{2+}$ mainly from the basolateral ER-rich part of the cell. The rate of $Ca^{2+}$ release from the ER was highly sensitive to the buffering of $[Ca^{2+}]_c$ whereas ER $Ca^{2+}$ refilling was enhanced by supplying free $Ca^{2+}$ to the cytosol with $[Ca^{2+}]_c$ clamped at resting levels with a patch pipette containing 10 mM BAPTA and 2 mM $Ca^{2+}$. Elevation of extracellular $Ca^{2+}$ to 10 mM from 1 mM raised resting $[Ca^{2+}]_c$ slightly and often generated $[Ca^{2+}]_c$ oscillations in single or clustered cells. Although pancreatic acinar cells are reported to have extracellular $Ca^{2+}$-sensing receptors linked to phospholipase C that mobilize $Ca^{2+}$ from the ER, exposure of cells to 10 mM $Ca^{2+}$ did not decrease $[Ca^{2+}]_{Lu}$ but rather raised it. From these findings we conclude that 1) ER $Ca^{2+}$ release is strictly regulated by feedback inhibition of $[Ca^{2+}]_c$, 2) ER $Ca^{2+}$ refilling is determined by the rate of $Ca^{2+}$ influx and occurs mainly in the tiny subplasmalemmal spaces, 3) extracellular $Ca^{2+}$-induced $[Ca^{2+}]_c$ oscillations appear to be triggered not by activation of extracellular $Ca^{2+}$-sensing receptors but by the ER sensitised by elevated $[Ca^{2+}]_c$ and $[Ca^{2+}]_{Lu}$.