• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.6
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• pp.1-7
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• 2001

To analyze the driving principle of PDP, the influence on the discharge characteristics of space charge was researched. Space charge generated by the priming discharge shortens delay time of the discharge which happens as follows and shorts response time. Such influences are valid up to about 30㎲ after generating priming discharge. This space charge decreases dicharge ignition voltage of the cell near priming cell and the influences are most greatly alerted on the discharge of cell which is adjacent most. And the dependency to spare charge strengthens because discharge ignition voltage drop grows by narrowing of discharge pulse width. But the influence on space charge was observed very slightly in pulse width 1㎲ or more. Therefore, to cause a steady discharge, pulse width should become 1㎲ or more at least without being influenced for space charge of the adjoining discharge.

• Journal of Digital Contents Society
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• v.11 no.2
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• pp.195-201
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• 2010

Globalization, conversions, and OSMU (One Source Multi Use) in modern cultural industry is expanding fast, and global competition is soaring with a changing environment today. In fact, the development of one nation depends on its cultural creativity. Yet, there is an increasing need for a connection between space and culture since globalization homogenizes a nation's unique cultural identity and provides low level of utilization in digital cultural contents in terms of saving, conserving and maintaining data. In order to invigorate the cultural industry, there must be some information that provides public culture contents, which they can be freely searched, displayed, and re-produced. Ultimately, these public culture contents should be able to provide Culture Space. This text discusses how individuals produce the Culture Space, which provides digital information of time and space, from a relationship between culture and space. It also introduces the public Culture Contents service framework in order to provide culture information and combined Culture Contents.

• Journal of Korea Spatial Information System Society
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• v.12 no.1
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• pp.49-56
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• 2010

Many researches of frequent pattern mining technique for detecting unknown patterns on spatial data have studied actively. Existing data structures have classified into tree-structure and array-structure, and those structures show the weakness of performance on dense or sparse data. Since spatial data have obtained the characteristics of dense and sparse patterns, it is important for us to mine quickly dense and sparse patterns using only single algorithm. In this paper, we propose novel data structure as compressed patricia frequent pattern tree and frequent pattern mining algorithm based on proposed data structure which can detect frequent patterns quickly in terms of both dense and sparse frequent patterns mining. In our experimental result, proposed algorithm proves about 10 times faster than existing FP-Growth algorithm on both dense and sparse data.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.56-56
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• 2021

하천단면이나 하상변동 추적 등 하천공간정보는 유량이나 강우 등 수문시계열 정보와 더불어 계획홍수위 산정이나 하천구조물 신설로 인한 하천의 변화를 추적하는 데 있어 근간을 이루는 주요 정보로 국가차원의 유지 및 관리가 필요하다. 국내의 하천공간정보는 RIMGIS, WAMIS, 하천 일람, WINS와 같은 웹기반 시스템에서 정보화 되어 관리되고 있다. 그러나, RIMGIS는 여러 가지 문제점을 노정하고 있어 개선을 적극적으로 검토해볼 시점이라고 볼 있다. 우선, RIMGIS는 구축이 10년 이상된 기술로 구성되어 온라인 시스템 실행속도가 느리고, 물관리 일원화 와중에 관리주체가 불분명해진 상태이며, 제공되는 정보도 하천망이나 유역 정도로 차원 및 정확도도 낮고 활용도 및 현행화도 부족한 상태이다. 또한 공간정보 관리 DB표준으로 효율적인 관계형 구조 대신 하천대장 등을 수치화한 개념의 레이어 단위의 주제도로 관리하다보니 자료중복이 불가피하여 시스템이 무겁고, 자료간 연관검색이 거의 불가하고, 신속한 하천지형 변화 업데이트가 어려운 상태이다. 최근 진행되고 있는 RIMGIS 개선 사업은 여전히 종래의 레이어 단위의 주제도들을 추가하거나 개정하는 데 머물고 있는 상태이다. 이러다 보니 현재 우리나라의 대표적인 하천정보시스템인 RIMGIS의 실무 활용도는 낮은 것으로 알려져 있다. 가장 실무활용도를 저하시키고 현행화 상의 문제로 지적되는 부분은 하천정비기본계획 수립 시 발생한 공간자료 관리 부실이다. 현재 RIMGIS에서는 하천기본계획보고서만 PDF 형태로 제공할 뿐, 실제 지형자료는 과업을 수행한 설계사에 개별 보관되어 활용도뿐만아니라 망실의 우려가 높은 상황이다. 본 연구에서는 하천기본계획수립 시 측량되는 단면을 포함한 다양한 공간자료를 관계형으로 표준화 DB에 효율적으로 저장할 수 있게 하는 방안을 제시하고자 한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.336-336
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• 2021

기후변화와 도시화로 인한 집중 호우와 불투수층 증가로 도시 홍수의 발생 빈도와 규모가 증가하고 있다. 인적, 물적 자원이 집중되어 있는 도시유역의 특성상 침수가 발생하면 이로 인한 직접적 피해 뿐만 아니라 사회경제적 2차 피해를 발생한다. 도시 홍수로 인한 피해를 줄이고 도시의 재해에 대한 회복력을 키우기 위해서는 관측과 더불어 정확한 모의 기술이 중요하다. 한편, 격자 기반 도시 홍수 모의는 집중 호우에 따른 침수의 시공간적 발생 양상을 물리적으로 해석하는 방법으로, 지표수-우수관거 이중배제 통합 모의, 수치기법, 병렬컴퓨팅, 수질 연계 모의 등의 측면에서 지금까지 많은 발전이 이루어져 왔다. 최근들어 원격탐사 기술의 발달로 공간해상도 1미터 수준 혹은 그 이상의 초고해상도 지형자료가 많은 지역에서 대해 가용해지고 있으며, 도시 홍수 해석에 이와 같은 초고해상도 자료를 적용하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 초고해상도 지형 및 토지 피복 자료의 공간해상도가 침수해석에 미치는 영향을 분석한다. 도시침수의 두가지 주요 요인인 내수침수와 외수범람 중에서 극한 강우에 의한 내수침수해석 사례만을 주요 연구 범위로 한다. 초고해상도 입력자료의 격자기반 도수 해석 모형으로는 운동파 기반의 2차원 지표 흐름 해석 모형을 적용하고, 초고해상도 모의의 효율적 계산을 위해 하이브리드 병렬 컴퓨팅 기술을 이용한다. 초고해상도 입력자료 적용 사례 대비, 공간해상도 저하에 따라 침수 면적이나 깊이 등에서 어떤 변화가 있는지 정량적으로 검토한다. 또한, 강우의 강도 및 공간분포가 초고해상도 도시 홍수 해석에 미치는 영향에 대해서 분석한다. 모의 결과로부터 도시 홍수 해석시 거리 단위(street-level) 정확도의 재현을 위해 적정한 공간해상도를 분석하고, 초고해상도 도시 홍수 모의를 이용한 기후변화에 따른 극한 홍수의 도시지역 영향 분석 및 회복력 개선 관련 연구의 가능성에 대해 논의한다.

• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.133-142
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• 2009

Recently, with the advance of wireless internet and the frequent use of mobile devices, demand for LBS(Location Based Service) is increasing, and research is required on spatial indexes for the storage and maintenance of spatial data to provide efficient LBS in mobile device environments. In addition, the use of flash memory as an auxiliary storage device is increasing in order to store large spatial data in a mobile terminal with small storage space. However, the application of existing spatial indexes to flash-memory lowers index performance due to the frequent updates of nodes. To solve this problem, research is being conducted on flash-memory based spatial indexes, but the efficiency of such spatial indexes is lowered by low utilization of buffer and flash-memory space. Accordingly, in order to solve problems in existing flash-memory based spatial indexes, this paper proposed FR-Tree (Flash-Memory based R-Tree) that uses the node compression technique and the delayed write operation technique. The node compression technique of FR-Tree increased the utilization of flash-memory space by compressing MBR(Minimum Bounding Rectangle) of spatial data using relative coordinates and MBR size. And, the delayed write operation technique reduced the number of write operations in flash memory by storing spatial data in the buffer temporarily and reflecting them in flash memory at once instead of reflecting the insert, update and delete of spatial data in flash-memory for each operation. Especially, the utilization of buffer space was enhanced by preventing the redundant storage of the same spatial data in the buffer. Finally, we perform ed various performance evaluations and proved the superiority of FR-Tree to the existing spatial indexes.

• The Journal of Society for e-Business Studies
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• v.8 no.4
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• pp.69-88
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• 2003

In high dimensional data, most of clustering algorithms tend to degrade the performance rapidly because of nature of sparsity and amount of noise. Recently, partial dimensional clustering algorithms have been studied, which have good performance in clustering. These algorithms select the dimensional data closely related to clustering but discard the dimensional data which are not directly related to clustering in entire dimensional data. However, the traditional algorithms have some problems. At first, the algorithms employ grid based techniques but the large amount of grids make worse the performance of algorithm in terms of computational time and memory space. Secondly, the algorithms explore dimensions related to clustering using k-medoid but it is very difficult to determine the best quality of k-medoids in large amount of high dimensional data. In this paper, we propose an efficient partial dimensional clustering algorithm which is called CLIP. CLIP explores dense regions for cluster on a certain dimension. Then, the algorithm probes dense regions on a next dimension. dependent on the dense regions of the explored dimension using incremental projection. CLIP repeats these probing work in all dimensions. Clustering by Incremental projection can prune the search space largely and reduce the computational time considerably. We evaluate the performance(efficiency, effectiveness and accuracy, etc.) of the proposed algorithm compared with other algorithms using common synthetic data.

• 한국노년학
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• v.36 no.4
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• pp.1109-1124
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• 2016

We examined the effect of stereotype threat (STT) on spatial working memory and facial emotion recognition in Korean elderly. In addition, we investigated the role of expected moderator such as self-perception of aging. Seventeen seniors (male=7) received basic cognitive tests including K-WMS-IV, MMSE and answered self-report questionnaires including self-perception of aging, anxiety of aging, attitude toward aging and age identity on the first visit. On the second visit, they were exposed to negative stereotype by reading a script detailing cognitive decline related to aging while a control group was exposed to a neutral content. Following the exposure, they were tested on a spatial-working memory task (Corsi-block tapping task) and emotion recognition task (facial expression identification task). The results showed that the seniors exposed to STT showed significantly lower performance on emotion recognition task (p < .05) (i.e., especially on the more difficult facial stimuli). In addition, there was a significant interaction between STT and self-perception of aging (p< .05), indicating that those who have positive self-perception of aging did not show impairment in emotion recognition task and difficult spatial working memory task under STT. On the other hand, those with negative self-perception of aging showed impaired performance under STT. Taken together, the current study suggests that being exposed to STT could negatively influence cognitive and emotional functioning of elderly. Interestingly, having a positive self-perception of aging could protect the underperformance caused by STT.

• Korean Journal of Remote Sensing
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• v.30 no.6
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• pp.817-827
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• 2014

In the satellite remote sensing, the operational environment of the satellite sensor causes image degradation during the image acquisition. The degradation results in noise and blurring which badly affect identification and extraction of useful information in image data. This study proposes a maximum a posteriori (MAP) estimation using Point-Jacobian iteration to restore a degraded image. The proposed method assumes a Gaussian additive noise and Markov random field of spatial continuity. The proposed method employs a neighbor window of spoke type which is composed of 8 line windows at the 8 directions, and a boundary adjacency measure of Mahalanobis square distance between center and neighbor pixels. For the evaluation of the proposed method, a pixel-wise classification was used for simulation data using various patterns similar to the structure exhibited in high resolution imagery and an unsupervised segmentation for the remotely-sensed image data of 1 mspatial resolution observed over the north area of Anyang in Korean peninsula. The experimental results imply that it can improve analytical accuracy in the application of remote sensing high resolution imagery.

• Tunnel and Underground Space
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• v.30 no.5
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• pp.433-445
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• 2020

Professional TBM Operator is in short supply worldwide, and insufficient construction experience of new personnel using TBM can lead to a decline in response capabilities when various construction risks occur. The fact that the TBM construction quality greatly depends on the skill and experience of the TBM operator, and the decrease in productivity due to insufficient skilled manpower, and the decrease in safety due to the decrease in skill level are frequently discussed problems in the TBM industry. To this end, several overseas companies and organizations have developed simulators, and a simulator is being developed in Korea. The International Tunneling Association is planning a comprehensive training, including classroom training, e-learning, simulator training and field training. Given the progress at home and abroad, TBM driver training and formal recognition of training through certification or licensing is expected to become the norm in the near future.