• 한국측량학회지
• /
• 제25권6_1호
• /
• pp.517-528
• /
• 2007

Extraction of the coastal boundary is important because the boundary serves as a reference in the demarcation of maritime zones such as territorial sea, contiguous zone, and exclusive economic zone. Accurate nautical charts also depend on well established, accurate, consistent, and current coastline delineation. However, to identify the precise location of the coastal boundary is a difficult task due to tidal and wave motions. This paper presents an efficient way to extract coastlines by applying digital image processing techniques to Synthetic Aperture Radar (SAR) imagery. Over the past few years, satellite-based SAR and high resolution airborne SAR images have become available, and SAR has been evaluated as a new mapping technology. Using remotely sensed data gives benefits in several aspects, especially SAR is largely unaffected by weather constraints, is operational at night time over a large area, and provides high contrast between water and land areas. Various image processing techniques including region growing, texture-based image segmentation, local entropy method, and refinement with image pyramid were implemented to extract the coastline in this study. Finally, the results were compared with existing coastline data derived from aerial photographs.

• 한국농공학회지
• /
• 제35권4호
• /
• pp.86-94
• /
• 1993

In this study, a tentative decision-making matrix for village planning in reclaimed land was proposed. The evaluating conditions in the matrix are reclaimed farming acreage and distance. And the indexes for evaluation works are farming acreage required for increasing present farm size to target size in the base of, allowable commuting distance for farming from and effective controlling distance of each village. The village planning strategies are considered into four categories ; upkeep of present village scale, transfer of its superfluous farming acreage to a neighbouring village, enlargement of present village scale and new village construction in reclaimed land. As a case study, the proposed decision-making matrix was applied to 69 villages, which are contiguous to the potential farming area from reclamation works of Yongsan River Basin Comprehensive Development Project Phase Ill and so considered in this study as future farming villages there. From the application results, the following tactics for village planning may be proposed ; principally, upkeep or enlargement of present village scale, but, in an exceptional few cases of standard farming size being 3~5ha, new village construction of normal or satellite scale.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제7권8호
• /
• pp.2042-2060
• /
• 2013

In wireless sensor networks (WSNs), energy efficiency is one of the most essential design considerations, since sensor nodes are resource constrained. Group communication can reduce WSNs communication overhead by sending a message to multiple nodes in one packet. In this paper, in order to simultaneously resolve the transmission security and scalability in WSNs group communications, we propose a hierarchical cluster-based secure and scalable group key management scheme, called HRKT, based on logic key tree and route key tree structure. The HRKT scheme divides the group key into cluster head key and cluster key. The cluster head generates a route key tree according to the route topology of the cluster. This hierarchical key structure facilitates local secure communications taking advantage of the fact that the nodes at a contiguous place usually communicate with each other more frequently. In HRKT scheme, the key updates are confined in a cluster, so the cost of the key updates is reduced efficiently, especially in the case of massive membership changes. The security analysis shows that the HRKT scheme meets the requirements of group communication. In addition, performance simulation results also demonstrate its efficiency in terms of low storage and flexibility when membership changes massively.

• 대한원격탐사학회지
• /
• 제34권1호
• /
• pp.141-150
• /
• 2018

Crop type classification is essential for supporting agricultural decisions and resource monitoring. Remote sensing techniques, especially using hyperspectral imagery, have been effective in agricultural applications. Hyperspectral imagery acquires contiguous and narrow spectral bands in a wide range. However, large dimensionality results in unreliable estimates of classifiers and high computational burdens. Therefore, reducing the dimensionality of hyperspectral imagery is necessary. In this study, the Random Forest (RF) classifier was utilized for dimensionality reduction as well as classification purpose. RF is an ensemble-learning algorithm created based on the Classification and Regression Tree (CART), which has gained attention due to its high classification accuracy and fast processing speed. The RF performance for crop classification with airborne hyperspectral imagery was assessed. The study area was the cultivated area in Chogye-myeon, Habcheon-gun, Gyeongsangnam-do, South Korea, where the main crops are garlic, onion, and wheat. Parameter optimization was conducted to maximize the classification accuracy. Then, the dimensionality reduction was conducted based on RF variable importance. The result shows that using the selected bands presents an excellent classification accuracy without using whole datasets. Moreover, a majority of selected bands are concentrated on visible (VIS) region, especially region related to chlorophyll content. Therefore, it can be inferred that the phenological status after the mature stage influences red-edge spectral reflectance.

• Journal of Communications and Networks
• /
• 제15권1호
• /
• pp.8-14
• /
• 2013

For alleviating the low spectrum efficiency problem of orthogonal frequency division multiplexing (OFDM), due to the strong inter-cell-interference (ICI) at cell's edge, we introduce comb-spectrum code division multiple access (CS-CDMA) into broadband OFDM system at downlink channel for enabling the use of entire spectrum for seamless coverage. In addition, we develop a new method, called orthogonal cell code (OCC) scheme, to assist CS-CDMA for nullifying the ICI from contiguous cells. In system operation, each of the conventional cells is divided into an outer cell and an inner cell, and a mobile station (MS) should access to the CS-CDMA when it is in the outer cell and access to OFDM when it is in the inner cell. This study investigates the spectrum efficiency of using CS-CDMA and makes a comparison with that of long term evolution (LTE) in the following cases; (1) under an assumption of perfect channel state information and (2) based on channel estimates at a MS station. The results show the great advantage of utilizing the proposed system.

• ALGAE
• /
• 제24권2호
• /
• pp.85-91
• /
• 2009

The filamentous cyanobacterium Anabaena sp. Strain PCC 7120 produces a developmental patten of single hete- rocysts separated by approximately 10 vegetative cells. Heterocysts differentiate from vegetative cells and are spe- cialized for nitrogen fixation. The patS gene, which encodes a small peptide that inhibits heterocyst differentiation, is expressed in proheterocysts and plays a critical role in establishing the heterocyst pattem. Another key regulator of heterocyst development is the hetR gene. hetR mutants fail to produce heterocysts and extra copies of hetR on a plas- mid cause a multiple contiguous heterocyst phenotype. To elucidate the relationship between these two counter act- ing factors in the genetic regulatory pathway during heterocyst differentiation, the expression patterns of a patS-gfp and a hetR-gfp fusion were examined in a patS deletion and a hetR deletion strain. The results, in combination with the result from a hetR and patS double deletion strain, suggest patS and hetR are mutually antagonistic and the bal- ance between these two factors in tow different cell types (heterocysts and vegetative cells) may be critical during the decision making process on their cell fates.

• 대한원격탐사학회지
• /
• 제24권5호
• /
• pp.397-408
• /
• 2008

A wide variety of applications of imaging spectrometer have been proved using data from airborne systems. The Compact Airborne Imaging Spectrometer System (CAISS) was jointly designed and developed as the airborne hyperspectral imaging system by Korea Aerospace Research Institute (KARI) and ELOP inc., Israel. The primary mission of the CAISS is to acquire and provide full contiguous spectral information with high spatial resolution for advanced applications in the field of remote sensing. The CAISS consists of six physical units; the camera system, the gyro-stabilized mount, the jig, the GPS/INS, the power inverter and distributor, and the operating system. These subsystems are to be tested and verified in the laboratory before the flight. Especially the camera system of the CAISS has to be calibrated and validated with the calibration equipments such as the integrating sphere and spectral lamps. To improve data quality and its availability, it is the most important to understand the mechanism of imaging spectrometer system and the radiometric and spectral characteristics. The several performance tests of the CAISS were conducted in the camera system level. This paper presents the major characteristics of the CAISS, and summarizes the results of performance tests in the camera system level.

• 한국컴퓨터정보학회논문지
• /
• 제19권11호
• /
• pp.91-96
• /
• 2014

사물인터넷은 다수의 센서를 통해 다양한 데이터를 수집하므로 센서의 생존 시간을 최대화하고 데이터를 효율적으로 수집해야한다. 또한 특정 영역에서의 연속적인 데이터 수집은 해당 센서들의 에너지 소비를 증가시키고 이벤트에 급격한 변화가 없을 경우 비슷한 데이터를 계속적으로 전송해야한다. 이러한 문제를 해결하기 위해 본 연구에서는 배치된 센서들을 동일 크기의 그리드로 나누고 단일 그리드 내에서 잔존 에너지, 센서의 밀도, 그리고 위치를 고려하여 최적의 헤드노드를 선택하는 알고리즘을 제시한다. 이 알고리즘의 목표는 그리드의 수명을 최대화하는 것이다. 시뮬레이션 결과 기존 기법들에 비해 단순하면서 에너지를 효율적으로 사용함을 확인할 수 있었다.

• 한국콘텐츠학회논문지
• /
• 제15권8호
• /
• pp.424-433
• /
• 2015

본 연구는 조음거리와 발성유형에 따른 영유아의 자음 음운인식 능력에서의 차이를 규명해 보기 위해 한국어 장애음을 대상으로 반복측정 실험설계를 통해 진행되었다. 집단 내 변인인으로서의 조음거리는, 연음과 경음의 자질을 갖는 1음절 초성의 조음 위치에 의해 구분된 조음점 간 거리로서 음운인식 수행도의 차이에 구조적으로 영향을 미치는지를 확인하고자 하였다. 실험결과, 음운차이 인식 수행력에서 조음거리를 변인으로 한 주효과를 확인하였는데, 그 거리가 멀어질수록 수행력이 점강하였다. 이는 동일위치나 근접거리 조음점 조건의 음운인식 수행도가 조음점 간 거리가 먼 조건에서의 수행도에 비해 민감한 반응을 보임으로써, 당해 조음점에 인접한 말소리들을 인식하는 능력이 우선 발달하는 결과를 시사함은 물론, 조음 유사성이 조기 음운습득에 영향을 끼칠 수 있음을 말해준다 하겠다. 아울러 집단 간 요인에서도 연령효과를 확인할 수 있었는데, 연령이 높을수록 조음거리에 영향을 덜 받는 경향이 있었으며 인접거리 조건에서는 남아대비, 여아의 수행력이 우수함을 알 수 있었다. 발성유형 중 긴장성을 피험자 내 변인으로 설정한 조건의 주효과는 나타나지 않았지만 연령의 주효과 및 성별과의 상호작용을 통해 연령상승에 따른 긴장음의 인식률의 유의한 상승을 관찰하였고, 긴장음 내에서는 여아의 변별력이 더 우수함을 확인할 수 있었다.

• 치과방사선
• /
• 제27권1호
• /
• pp.73-86
• /
• 1997

This study was performed to assess the analyzing methods developed to detect clinically and quantitatively longitudinal bone changes. Through preliminary experiment, accuracy of Cu-Eq value conversion to the mass of HA was examined. For main experiment, 15 intraoral radiograms taken at soon, 1st, 2nd, 4th, and 6th week after implantation of mixture in extracted sites of 3 cases were used. We took the radiograms with copper step wedge as test object and HA phantom X -ray taking was standardized by using Rinn XCP device customized directly to the individual dentition with resin bite block. The images inputted by Quick scanner into computer were digitized and analyzed by NIH image program. The stability of the copper equivalent transformation and the usefulness of two analyzing methods by ROI and Reslice were examined. Obtained results as follows: 1) On the Cu equivalent images, the coefficient of variation in the measurement of Cu-Eq. value of ROI ranged from 0.05 to 0.24 and showed high reproducibility. 2) All results obtained by resliced contiguous image were coincident with those obtained from the assessment by ROI and formation of plot profile. 3) On the stacked and resliced image at the line of interest, we could analyze directly and quantitatively the longitudinal changes at several portions by plot profile and qualitatively by surface plot. 4) Implant area showed marked resorption till 2 weeks after implantation and showed significant increase in Cu-Eq. value at 6th week(p<0.01) and periapical area showed increase in Cu-Eq. value at 6th week compared to after-operation's.