• Title/Summary/Keyword: Differential sensing

검색결과 174건 처리시간 0.021초

Estimating Ocean Tidal Constituents Using SAR Interferometric Time Series over the Sulzberger Ice Shelf, W. Antarctica

  • Baek, Sang-Ho;Shum, C.K.
    • 한국측량학회지
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    • 제36권5호
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    • pp.343-353
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    • 2018
  • Ocean tides in Antarctica are not well constrained mostly due to the lack of tidal observations. Especially, tides underneath and around ice shelves are uncertain. InSAR (Interferometric Synthetic Aperture Radar) data has been used to observe ice shelf movements primarily caused by ocean tides. Here, we demonstrate that it is possible to estimate tidal constituents underneath the Sulzberger ice shelf, West Antarctica, solely using ERS-1/2 tandem mission DInSAR (differential InSAR) observations. In addition, the tidal constituents can be estimated in a high-resolution (~200 m) grid which is beyond any tidal model resolution. We assume that InSAR observed ocean tidal heights can be derived after correcting the InSAR data for the effect of atmospheric loading using the inverse barometric effect, solid earth tides, and ocean tide loading. The ERS (European Remote Sensing) tandem orbit configuration of a 1-day separation between SAR data takes diminishes the sensitivity to major tidal constituents including $K_1$ and $S_2$. Here, the dominant tidal constituent $O_1$ is estimated using 8 differential interferograms underneath the Sulzberger ice shelf. The resulting tidal constituent is compared with a contemporary regional tide model (CATS2008a) and a global tide model (TPXO7.1). The InSAR estimated tidal amplitude agrees well with both models with RMS (root-mean-square) differences of < 2.2 cm and the phase estimate corroborating both tide models to within $8^{\circ}$. We conclude that fine spatial scale (~200 m) Antarctic ice shelf ocean tide determination is feasible for dominant constituents using C-band ERS-1/2 tandem mission InSAR.

Security Analysis of the PHOTON Lightweight Cryptosystem in the Wireless Body Area Network

  • Li, Wei;Liao, Linfeng;Gu, Dawu;Ge, Chenyu;Gao, Zhiyong;Zhou, Zhihong;Guo, Zheng;Liu, Ya;Liu, Zhiqiang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제12권1호
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    • pp.476-496
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    • 2018
  • With the advancement and deployment of wireless communication techniques, wireless body area network (WBAN) has emerged as a promising approach for e-healthcare that collects the data of vital body parameters and movements for sensing and communicating wearable or implantable healthful related information. In order to avoid any possible rancorous attacks and resource abuse, employing lightweight ciphers is most effective to implement encryption, decryption, message authentication and digital signature for security of WBAN. As a typical lightweight cryptosystem with an extended sponge function framework, the PHOTON family is flexible to provide security for the RFID and other highly-constrained devices. In this paper, we propose a differential fault analysis to break three flavors of the PHOTON family successfully. The mathematical analysis and simulating experimental results show that 33, 69 and 86 random faults in average are required to recover each message input for PHOTON-80/20/16, PHOTON-160/36/36 and PHOTON-224/32/32, respectively. It is the first result of breaking PHOTON with the differential fault analysis. It provides a new reference for the security analysis of the same structure of the lightweight hash functions in the WBAN.

FAULT DISPLACEMENT OF WENCHUAN EARTHQUAKE OBSERVED BY ALOS PALSAR

  • Won, Joong-Sun;Jung, Hyung-Sup
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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    • pp.418-421
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    • 2008
  • Wenchuan earthquake (Mw 7.9) occurred in Sichuan province, China, May 2008 had resulted in a huge fault displacement around the Lungmenshan fault. Preliminary results of the fault displacement observed by ALOS PALSAR interferometry are presented. The surface deformation by the Wenchuan earthquake was reported up to 10m consisting of thrust- and right-slip compnents. A significant reduction in ionospheric density was also reported. Twenty differential interferograms and twenty multiple aperture SAR interferometry (MAI) pairs were produced over four ALOS tracks. It was observed from differential interferograms that i) LOS deformation decreases steadily from northnorthwest of the Longmenshan fault to the fault, ii) the LOS deformation sharply increases at areas around the fault, and iii) the decrease of the LOS deformation is observed from the Longmenshan fault to the south-southeast of the fault. Horizontal movement of the reverse fault displacement can better be observed by MAI technique, and the MAI phases show that i) the south-southeast directional reverse fault displacement (negative along-track deformation for an ascending track) of the north-northwest block gradually increases to the Longmenshan fault, ii) the reverse fault movement of the south-southeast block is sharply reversed to the north-northwest of the fault, and iii) the northnorthwest movement gradually decreases to the south-southeast of fault. Although the Lonmenshan Fault line is a center of earthquake epicenter, the boundary of surface movement exists to the north-northeast of the fault. Since the ionosphere was not stable even forty days after the mainshock, MAI phases were seriously corrupted by ionospheric effect. It is necessary to acquire more data when the ionosphere recovered to a normal state.

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Measurement of Time-Series Surface Deformation at New Orleans Using Small Baseline Subset (SBAS) Method

  • Jo, Min-Jeong;Eom, Jin-Ah;Won, Joong-Sun
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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    • pp.49-52
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    • 2008
  • New Orleans located in the estuary of the Mississippi River was attacked by Hurricane Katrina and suffered big flood on August 2005. Since unconsolidated Holocene to middle Miocene strata is the main basement rocks, land subsidence has been occurred steadily due to soil compaction and normal faulting. It was reported that the maximum subsidence rate from 2002 to 2005 was -29 mm/yr. Many studies in the area have been carried out for understanding the subsiding and potential risks caused by ground subsidence are weighted by the fact that a large area of the city is located below the mean sea level. A small baseline subset (SBAS) method is applied for effectively measuring time-series LOS (Line-of sight) surface deformation from differential synthetic aperture radar interferograms in this study. The time-series surface deformation at New Orleans was measured from RADARSAT-1 SAR images. The used dataset consists of twenty-one RADARSAT-1 fine beam mode images on descending orbits from February 2005 to February 2007 and another twenty-one RADARSAT-1 standard beam mode images on ascending orbits from January 2005 to February 2007. From this dataset, 25 and 38 differential interferograms on descending and ascending orbits were constructed, respectively. The vertical and horizontal components of surface deformation were extracted from ascending and descending LOS surface deformations. The result from vertical component of surface deformation indicates that subsidence is not significant with a mean rate of -3.1${\pm}$3.2 mm/yr.

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Security Analysis of the Whirlpool Hash Function in the Cloud of Things

  • Li, Wei;Gao, Zhiyong;Gu, Dawu;Ge, Chenyu;Liao, Linfeng;Zhou, Zhihong;Liu, Ya;Liu, Zhiqiang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제11권1호
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    • pp.536-551
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    • 2017
  • With the advancement and deployment of leading-edge telecommunication technologies for sensing and collecting, computing related information, Cloud of Things (CoTs) has emerged as a typical application platform that is envisioned to revolutionize the daily activities of human society, such as intelligent transportation, modern logistics, food safety, environmental monitoring, etc. To avoid any possible malicious attack and resource abuse, employing hash functions is widely recognized as one of the most effective approaches for CoTs to achieve message integrity and data authentication. The Whirlpool hash function has served as part of the joint ISO/IEC 10118-3 International Standard by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). In this paper, we propose an effective differential fault analysis on Whirlpool in the byte-oriented random fault model. The mathematical analysis and experimental results show that 8 random faults on average are required to obtain the current 512-bit message input of whirlpool and the secret key of HMAC-Whirlpool. Our work demonstrates that Whirlpool and HMAC-Whirlpool are both vulnerable to the single byte differential fault analysis. It provides a new reference for the security analysis of the same structure of the hash functions in the CoTs.

단일밴드 중적외선 영상으로부터 표면온도 추정을 위한 상대온도추정알고리즘의 연구 (Retrieval of Relative Surface Temperature from Single-channel Middle-infrared (MIR) Images)

  • 박욱;원중선;정형섭
    • 대한원격탐사학회지
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    • 제29권1호
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    • pp.95-104
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    • 2013
  • 3-5 ${\mu}m$ 파장대의 중적외선 영상으로부터 정밀한 절대온도를 추정하기 위해서는 지표 복사율, 대기효과, 낮 영상의 경우 반사되는 태양빛에 대한 정보를 필요로 하며, 이는 온도 추정 시 오차를 발생시키는 주요 원인이 된다. 이 연구는 이를 해결하기 위해 상대적인 온도 차이를 추정하는 방법을 제안하고자 한다. 제안된 알고리즘의 기본 방향은 온도 추정을 위한 입력자료를 최소화 시키는 것이다. 이를 위해 인접한 지역에 위치한 두 대상물체가 받는 대기효과는 동일하다고 가정하였으며 MODTRAN 및 ASTER spectral library로부터 입력자료를 단순화 시키는 연구가 수행되었다. 시뮬레이션 연구 결과 제안된 상대온도추정알고리즘의 정밀도는 300 K의 온도에서 0.1의 지표 복사율 오차에 대해 2 K 이내의 비교적 높은 정밀도를 나타냈다. 그러나 낮 영상에서 저온인 경우에는 정밀도가 크게 감소하였다. 알고리즘의 검증을 위해 MODIS band 23 중적외선 낮 영상에 적용하였으며, 이를 MODIS LST 자료와 비교를 수행한 결과 $0.485{\pm}1.552$ K의 오차를 나타내었다. 이 결과로부터 제안된 알고리즘이 외부 입력자료를 필요로 하지 않고 단지 영상 만으로부터 비교적 높은 정밀도로 온도 추정이 가능함을 보였다. 그러나 제안된 알고리즘은 상대온도만을 알 수 있으며, 절대온도를 추정하기 위해서는 기준온도에 대한 정보가 필요하다는 한계점도 있다.

뉴로퍼지방식 광유도식 무인반송차의 경로추종 제어 (A Path-Tracking Control of Optically Guided AGV Using Neurofuzzy Approach)

  • 임일선;허욱열
    • 제어로봇시스템학회논문지
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    • 제7권9호
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    • pp.723-732
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    • 2001
  • 경로 추적의 성능을 향상시키기 위해서 이 논문에서는 광유도식 무인방송차(AGV)의 뉴로퍼지 컨트롤러를 제안한다. 2바퀴 각각 조향 기능이 있는 AGV의 전방과 후방에 센서들이 장작되어 있으며, 그 센서들의 정보를 이용하여 AGV의 경로를 유도하게 된다. 측정된 광센서가 연속적인 데이터가 아니기 때문에 광유도식 AGV 는 쉽게 경로를 이탈하게 되고 경로 추적 성능은 떨어지게 된다. 광센서의정보들은 on/off 신호에 의해 발생되므로 비연속적으로 얻어지게 되고, 동적 오착가 측정되어진다. 센서에 의해 정보를 얻은 후 동적 오차는 좌우측 바퀴의 각 속도를 이용한 데드 레코닝(Dead Reckoning) 방법에 의해 연속적으로 계산되어진다. 여기서, 추정 윤곽 오차는 측정 윤관오차를 윤곽오차의증북(Variation)의 합의로 정의된다. 뉴로퍼지 시스템은 퍼지 제어기와 신경회로망으로 이루어졌다. 추정 윤곽 오차를 줄이기 위해 역전파 (Back-Propagation) 학습에 의해 퍼지 맴버쉽 함수의 계수들은 적응적으로 조정된다. 제안된 기존의 퍼지 제어기와 비교분석된다. 성능 분석을 위해 제안된 제어 이론은 모의 실험에 의해 검증된다.

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도시 그린웨에이 대한 감지(感知)와 평가 연구 -정주시(郑州市) 동풍거(东风渠) 그린웨이를 중심으로- (A Study on Residents' Perception and Evaluation of Urban Greenway -Centered on the Greenway of Zhengzhou Dongfeng Canal-)

  • 장림;문정민
    • 디지털융복합연구
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    • 제20권5호
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    • pp.919-929
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    • 2022
  • 그린웨이는 일종의 새로운 형태의 건강 공공 공간이다. 사용자들은 그린웨이에서 여가활동, 운동, 관람과 필요한 교통 이동을 한다. 그러나 현재까지는 그린웨이 사용자들이 그린웨이에 대한 평가 및 감지에 연관된 연구가 매우 부족하며, 인본적 관점에서 그린웨이 환경에 대한 종합적인 탐구가 아직 이루어지지 않고 있다.본 연구에서는 현재 중국도시의 대표적인 그린웨이에 대한 연구와 그린웨이의 실제 현황을 결합하고 대량의 문헌을 참고하였으며 시맨틱디퍼렌셜법(semantic differential method) 과 다원회귀분석 방법을 활용하여 동풍거(东风渠) 그린웨이를 분석하였다. 이를 통하여 그린웨이 사용자들의 감지(感知)의 관점에서 출발하여 그린웨이 환경에 미치는 영향 요소 및 그에 따른 영향평가를 탐구하고 여러 가지 측면에서 정주시(郑州市) 동풍거(东风渠) 환경의 최적화에 대한 개선 사항을 건의하였다. 본 연구의 가장 핵심적인 결론은 시맨틱디퍼렌셜법(semantic differential method)에서 도출된 데이터 결과가 그린웨이를 사용하는 주민들의 평가로부터 실질적으로 실현 가능한 데에서 기인한 것이며, 사용 후 평가된 피드백 결과는 앞으로 이와 같은 그린웨이 계획 설계에 신뢰할 수 있는 참고적 자료를 제공해줄 수 있다.

Voltammetric Studies of Anion Transfer Reactions Across a Microhole Array-Water/PVC-NPOE Gel Interface

  • Hossain, Md. Mokarrom;Girault, Hubert H.;Lee, Hye-Jin
    • Bulletin of the Korean Chemical Society
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    • 제33권5호
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    • pp.1734-1740
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    • 2012
  • Voltammetric characterization of hydrophilic anion transfer processes across a 66 microhole array interface between the water and polyvinylchloride-2-nitrophenyloctylether gel layer is demonstrated. Since the transfer of hydrophilic anions including $Br^-$, $NO_3{^-}$, $I^-$, $SCN^-$ and $ClO_4{^-}$ across the liquid/gel interface usually sets the potential window within a negative potential region, a highly hydrophobic organic electrolyte, tetraoctylammonium tetrakis(pentafluorophenyl)borate, providing a wider potential window was incorporated into the gel phase. The transfer reaction of perchlorate anions across the microhole-water/gel interface was first studied using cyclic voltammetry and differential pulse voltammetry. The full voltammetric response of perchlorate anion transfer was then used as a reference for evaluating the half-wave transfer potentials, the formal transfer potentials and the formal Gibbs transfer energies of more hydrophilic anions such as $Br^-$, $NO_3{^-}$, $I^-$, and $SCN^-$. The current response associated with the perchlorate anion transfer across the micro-water/gel interface versus the perchlorate concentration was also demonstrated for sensing applications.

The Detection of Yellow Sand Dust Using the Infrared Hybrid Algorithm

  • Kim, Jae-Hwan;Ha, Jong-Sung;Lee, Hyun-Jin
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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    • pp.370-373
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    • 2005
  • We have developed Hybrid algorithm for yellow sand detection. Hybrid algorithm is composed of three methods using infrared bands. The first method used the differential absorption in brightness temperature difference between $11\mu m\;and\;12\mu m$ (BID _1), through which help distinguish the yellow sand from various meteorological clouds. The second method uses the brightness temperature difference between $3.7\mu m\;and\;11\mu m$ (BID_2). The technique would be most sensitive to dust loading during the day when the BID _2 is enhanced by reflection of $3.7\mu m$ solar radiation. The third one is a newly developed algorithm from our research, the so-called surface temperature variation method (STY). We have applied the three methods to MODIS for derivation of the yellow sand dust and in conjunction with the Principle Component Analysis (PCA), a form of eigenvector statistical analysis. PCI shows better results for yellow sand detection in comparison with the results from individual method. The comparison between PCI and MODIS aerosols optical depth (AOD) shows remarkable good correlations during daytime and relatively good correlations over the land.

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