• 대한원격탐사학회지
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• 제31권4호
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• pp.293-302
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• 2015

Water body extraction is significant for flood disaster monitoring using satellite imagery. Conventional methods have focused on finding an index, which highlights water body and suppresses non-water body such as vegetation or soil area. The Normalized Difference Water Index (NDWI) is typically used to extract water body from satellite images. The drawback of NDWI, however, is that some man-made objects in built-up areas have NDWI values similar to water body. The objective of this paper is to propose a new method that could extract correctly water body with built-up areas in before and after images of flood. We first create a two-element feature vector consisting of NDWI and a Near InfRared band (NIR) and then select a training site on water body area. After computing the mean vector and the covariance matrix of the training site, we classify each pixel into water body based on Mahalanobis distance. We also register before and after images of flood using outlier removal and triangulation-based local transformation. We finally create a change map by combining the before-flooding water body and after-flooding water body. The experimental results show that the overall accuracy and Kappa coefficient of the proposed method were 97.25% and 94.14%, respectively, while those of the NDWI method were 89.5% and 69.6%, respectively.

• 한국항해항만학회지
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• 제33권7호
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• pp.477-482
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• 2009

In this paper the order picking problem in warehouses is considered, a topic which has received considerable attention from the international academic body in recent years. The order picking problem deals with the retrieval of order items from prespecified locations in the warehouse, and its objective is usually the minimization of travel time or travel distance. Hence, a well-thought order picking policy in combination with an appropriate storage policy will enhance warehouse efficiency and reduce operational costs. This paper starts with a literature overview summarizing approaches to routing order pickers, assigning stock-keeping units to pick locations and designing warehouse layouts. Since the layout design might affect both storage and routing policies, the three factors are interdependent with respect to order picking performance. To test these interdependencies, a simulation experiment was set up, involving two types of warehouse layout, four types of storage policy, five well-known heuristics and five sizes of order picking list. Our results illustrate that from the point of view of order picking distance minimization it is recommended to equip the warehouse with a third cross aisle, although this comes at the cost of a certain space loss. Additionally, we propose a set of most appropriate matches between order picking heuristics and storage policies. Finally, we give some directions for further research and recommend an integrated approach involving all factors that affect warehouse efficiency.

• 한국지반환경공학회 논문집
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• 제11권2호
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• pp.5-11
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• 2010

폐광산 주변의 광미장, 폐석더미로 인해 주변 지역의 토양 및 농작물들은 중금속으로 오염 될 수 있다. 본 연구는 주변토양 용도별, 농작물 재배품목별, 광산과의 이격거리별로 분류하여 광산 주변 중금속 오염실태조사를 수행하였다. 갱구인근 지역에서 Zn와 Pb이 토양오염기준치를 초과하였으며 다른 지역에 비해 광미장 지역과 논 경작지 토양의 중금속농도가 비교적 높은 것으로 나타났다. 광산과의 이격거리에 따른 중금속 농도는 갱구에서 거리가 멀어질수록 점차 감소하였다. 토양과 쌀 시료의 중금속 상관관계는 As와 Cd이 상관관계성이 있는 것으로 나타났으나 다른 중금속들은 관계성이 없는 것으로 조사되었다.

• 한국측량학회지
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• 제7권2호
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• pp.45-51
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• 1989

랜즈왜곡은 상의 위치를 변화시키므로 이에 대한 보정은 사진측량의 정확도 향상에 중요한 의미를 지니고 있다. 본 연구는 기준점 성과와 space resection의 과정없이 단사진으로 보정계수 결정이 가능한 plumb line method를 이용하여 거리에 따른 측정용, 비측정용 카메라의 렌즈왜곡 보정계수를 구하고 이를 실제 피사체의 3차원 위치해석에 적용, 정확도 향상을 기하고자 함에 목적이 있다. 그 결과, 측정용 카메라는 큰 차이를 보이지 않으나 비측정용 카메라는 방사방향, 접선방향 왜곡 보정계수가 촬영거리에 따라 면하므로 촬영거리에 따른 보정계수 적용이 바람직하며, 비측정용 카메라에 이를 적용하였을 경우 오차가 약 30%∼76%까지 현저히 감소되었다.

• 한국운동역학회지
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• 제31권3호
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• pp.199-204
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• 2021

Objective: The purpose of this study was to present a new idea of methodology to evaluate Poomsae performance using inertial measurement unit (IMU) sensors in terms of signal processing techniques. Method: Ten collegian Taekwondo athletes, consisting of five Poomsae elite athletes (age: 21.4 ± 0.9 years, height: 168.4 ± 11.3 cm, weight: 65.0 ± 10.6 kg, experience: 12 ± 0.7 years) and five breaking demonstration athletes (age: 21.0 ± 0.0 years, height: 168.4 ± 4.7 cm, weight: 63.8 ± 8.2 kg, experience: 13.0 ± 2.1 years), voluntarily participated in this study. They performed three different black belt Poomsae such as Goryeo, Geumgang, and Taebaek Poomsae repeatedly twice. Repeated measured motion data on the wrist and ankle were calculated by the methods of cosine similarity and Euclidean distance. Results: The Poomsse athletes showed superior performance in terms of temporal consistency at Goryeo and Taebaek Poomsae, cosine similarity at Geumgang and Taebaek Poomsae, and Euclidian distance at Geumgang Poomsae. Conclusion: IMU sensor would be a useful tool for monitoring and evaluating within-subject temporal variability of Taekwondo Poomsae motions. As well it distinguished spatiotemporal characteristics among three different Poomsae.

• Geomechanics and Engineering
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• 제35권5호
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• pp.499-509
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• 2023

The objective of this study is to perform outlier analysis to obtain the distribution of groundwater levels through the best model. The groundwater levels are measured in 10, 25 and 30 piezometers in Seoul, Daejeon and Suncheon in South Korea. Fifty-eight empirical distribution functions were applied to determine a suitable fit for the measured groundwater levels. The best fitted models based on the measured values are determined as the Generalized Pareto distribution, the Johnson SB distribution and the Normal distribution for Seoul, Daejeon and Suncheon, respectively; the reliability is estimated through the Anderson-Darling method. In this study, to choose the appropriate confidence interval, the relationship between the amount of outlier data and the confidence level is demonstrated, and then the 95% is selected at a reasonable confidence level. The best model shows a smaller error ratio than the GEV while the Mahalanobis distance and outlier labelling methods results are compared and validated. The outlier labelling and Mahalanobis distance based on median shown higher validated error ratios compared to their mean equivalent suggesting, the methods sensitivity to data structure.

• 제어로봇시스템학회논문지
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• 제8권12호
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• pp.1014-1022
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• 2002

An objective of Automated Highway Systems (AHS) is to increase the safety and throughput of the existing highway infrastructure by introducing traffic automation. AHS is an example of a large scale, multiagent complex dynamical system and is ideally suited for a hierarchical hybrid controller. We discuss a design issue of efficient hybrid controllers for the platoon maneuvers on AHS. For the modeling of a hybrid system including the merge and split operations, a safety distance policy is introduced for the merge and split operations. After that, the platoon system will be modeled by a hybrid system In addition, a hybrid controller for the proposed merge and split operation models is presented. Finally, the performance of the proposed hybrid control scheme is demonstrated via scenarios for platoon maneuvers.

• 대한기계학회논문집
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• 제15권1호
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• pp.98-106
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• 1991

본 연구에서는 로봇이용의 자동화를 위하여 가장 필수적인 과정인 로봇의 운 동경로 계획에 관하여 연구하고 작업영역 내에 장애물이 있는 경우에 로봇과 장애물과 의 충돌 회피를 위한 정량적인 양으로 두물체간의 최소거리 및 충돌깊이를 효율적으로 계산할 수 있는 방법을 제안하며 이를 이용하여 로봇이 장애물과 충돌하지 않고 주어 진 작업을 수행할 수 있는 로봇의 경로를 자동으로 생성함으로써 로봇을 보다 상위레 벨에서 운용하기 위한 기초를 마련한다.

• 설비공학논문집
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• 제16권6호
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• pp.506-513
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• 2004

The objective of this paper is to evaluate the economic performance of latent and sensible energy transportation systems. LCC (Life-Cycle Cost) analysis is a practical method and a guideline for evaluating the economic performance of considered systems during the Life-Cycle Period. By comparing the LCC of alternatives, The most ideal alternative is determined which has the lowest LCC. It is concluded that the cost of STA (Solution Transportation Absorption system) can be reduced by 67% to that of sensible energy transportation for study period with 10 km transportation distance.

• Journal of the Korean Data and Information Science Society
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• 제20권6호
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• pp.1207-1212
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• 2009

Basic objective in cluster analysis is to discover natural groupings of items or variables. In general, clustering is conducted based on some similarity (or dissimilarity) matrix or the original input text data. Various measures of similarities (or dissimilarities) between objects (or variables) are developed. We introduce a real application problem of clustering procedure in SPSS when the distance matrix of the objects (or variables) is only given as an input data. It will be very helpful for the cluster analysis of huge data set which leads the size of the proximity matrix greater than 1000, particularly. Syntax command for matrix input data in SPSS for clustering is given with numerical examples.