• Korean Journal of Human Ecology
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• v.15 no.2
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• pp.327-339
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• 2006

We have investigated the distribution of major local foods cultivated in Gwangju City and Jeollanam-Do in order to understand the food culture of Honam region. The local foods were divided into 4 classes: agricultural, aquatic, animal and other products. 124 species of local foods, including 51 agricultural products, 50 aquatic products, 6 animal products and 17 others, were identified from this region. In Jeollanam-Do area, the agricultural products have a variety of fruits and vegetables, and aquatic products have fishes. In particular, rice, cucumber, pear, anchovy, oyster, laver, oyster mushroom, shiitake mushroom, and honey were determined as major local foods in Jeollanam-Do area. Note that Mudeungsan watermelon is cultivated in Gwangju, and sweet smelt and cat fish caught only in Sumjin river and Tamjin river area. In recent years, pumpkin (Cucurbita maxima Duchesne), paprika, kiwi and melon were determined as major local foods in Jeollanam-Do. Furthermore, branding strategy of agricultural and animal products can be said to improve. Wild types of aquatic productions, mushrooms and wild edible greens have been decreasing, whereas cultivated production increasing. The kinds of special local foods in Gwangju City and Jeollanamdo area were influenced by geographical, religious and social factors.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.649-657
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• 1998

In this study, the effects of the various conditions of frosting and defrosting on the behavior of defrosting in a fin-tube heat exchanger have been examined experimentally. The electric heater is used for defrosting in a fin-tube heat exchanger It is shown that there are several local maxima in the water draining rate. The amount of residual water on the heat exchanger after the completion of defrosting is kept constant due to surface tension on the heat exchanger. Without considering the degradation of the thermal performance due to the frosting, the defrosting efficiency is improved with increasing amount of the frost irrespective of the frosting condition. The defrosting behavior is affected by the frosting density as well as the frost accumulation, which vary with the experimental operating conditions during the frosting period. The heat loss to the surrounding air decreases, and the melting and defrosting efficiencies show high values with decreasing heat input.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.04a
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• pp.471-477
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• 2003

This paper presents an algorithm that automatically extracts buildings among many different features on the earth surface by fusing LIDAR data with panchromatic aerial images. The proposed algorithm consists of three stages such as point level process, polygon level process, parameter space level process. At the first stage, we eliminate gross errors and apply a local maxima filter to detect building candidate points from the raw laser scanning data. After then, a grouping procedure is performed for segmenting raw LIDAR data and the segmented LIDAR data is polygonized by the encasing polygon algorithm developed in the research. At the second stage, we eliminate non-building polygons using several constraints such as area and circularity. At the last stage, all the polygons generated at the second stage are projected onto the aerial stereo images through collinearity condition equations. Finally, we fuse the projected encasing polygons with edges detected by image processing for refining the building segments. The experimental results showed that the RMSEs of building corners in X, Y and Z were ${\pm}$8.1cm, ${\pm}$24.7cm, ${\pm}$35.9cm, respectively.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.12a
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• pp.125-131
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• 2004

LiDAR 데이터의 필터링은 원 데이터로부터 건물, 수목 등과 같은 비지면점을 제거하는 과정이며, 이러한 필터링을 통해 DEM을 생성할 수 있다. 대표적인 필터링 방법들로는 분산을 이용한 linear prediction 기법, 주변 점들과의 경사관계를 이용한 slope-based 기법, morphology 필터, local maxima 필터 등이 있으며 이러한 기존의 기법들의 단점을 보완하기 위한 연구가 활발히 진행되고 있다. 대부분의 필터링 기법들은 필터의 크기(윈도우의 크기)와 같은 인자를 대상 지역에 적합하게 사용자가 직접 설정해주어야 한다. 더욱이 복잡한 지형, 지물이 존재하는 지역에 적용하기 위해서는 인자를 변형시켜줘야 하며 특히, 다양한 크기의 건물이 존재하는 지역에 대하여 적용하기 위해서는 가변적인 크기의 필터가 필요하다. 이에 본 논문에서는 다양한 크기의 건물이 존재하는 지역에 대하여 필터의 크기를 변화시키지 않고 필터링을 수행할 수 있는 연산기법을 제안하였다. 본 연구에서는 수목이나 자동차 등과 같은 작은 개체의 제거를 위해 고정된 작은 크기의 윈도우를 가지는 모폴로지 필터를 우선 적용한다. 그 후 건물과 같은 큰 개체의 포인트는 이웃 포인트와의 고도차이를 이용하여 인식하고 이웃에 위치하는 지면 포인트로 대체하며, 갱신된 값이 바로 다음 연산에 반영 되도록 한다. 또한 상, 하, 좌, 우 네 방향에 대하여 라인별로 독립된 연산을 수행한 후에 이들을 비교함으로써 오차를 보정한다.

• Communications for Statistical Applications and Methods
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• v.24 no.2
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• pp.173-191
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• 2017

This study develops a new type of latent class analysis (LCA) in order to explain the associations between one latent variable and several other categorical latent variables. Our model postulates that the prevalence of the latent variable of interest is affected by another latent variable composed of other several latent variables. For the parameter estimation, we propose deterministic annealing EM (DAEM) to deal with local maxima problem in the proposed model. We perform simulation study to demonstrate how DAEM can find the set of parameter estimates at the global maximum of the likelihood over the repeated samples. We apply the proposed LCA model in an investigation of the effect of and joint patterns for drug-using behavior to violent behavior among US high school male students using data from the Youth Risk Behavior Surveillance System 2015. Considering the age of male adolescents as a covariate influencing violent behavior, we identified three classes of violent behavior and three classes of drug-using behavior. We also discovered that the prevalence of violent behavior is affected by the type of drug used for drug-using behavior.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.103-112
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• 2017

Application of the supercritical condition in reactor core cooling needs to be properly justified based on the extreme level of parameters involved. Therefore, a numerical study is presented to compare the thermalhydraulic performance of supercritical and single-phase natural circulation loops under low-to-intermediate power levels. Carbon dioxide and water are selected as respective working fluids, operating under an identical set of conditions. Accordingly, a three-dimensional computational model was developed, and solved with an appropriate turbulence model and equations of state. Large asymmetry in velocity and temperature profiles was observed in a single cross section due to local buoyancy effect, which is more prominent for supercritical fluids. Mass flow rate in a supercritical loop increases with power until a maximum is reached, which subsequently corresponds to a rapid deterioration in heat transfer coefficient. That can be identified as the limit of operation for such loops to avoid a high temperature, and therefore, the use of a supercritical loop is suggested only until the appearance of such maxima. Flow-induced heat transfer deterioration can be delayed by increasing system pressure or lowering sink temperature. Bulk temperature level throughout the loop with water as working fluid is higher than supercritical carbon dioxide. This is until the heat transfer deterioration, and hence the use of a single-phase loop is prescribed beyond that limit.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.241-243
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• 2003

This paper presents an algorithm that automatically extracts buildings among many different features on the earth surface by fusing LIDAR data with panchromatic aerial images. The proposed algorithm consists of three stages such as point level process, polygon level process, parameter space level process. At the first stage, we eliminate gross errors and apply a local maxima filter to detect building candidate points from the raw laser scanning data. After then, a grouping procedure is performed for segmenting raw LIDAR data and the segmented LIDAR data is polygonized by the encasing polygon algorithm developed in the research. At the second stage, we eliminate non-building polygons using several constraints such as area and circularity. At the last stage, all the polygons generated at the second stage are projected onto the aerial stereo images through collinearity condition equations. Finally, we fuse the projected encasing polygons with edges detected by image processing for refining the building segments. The experimental results showed that the RMSEs of building corners in X, Y and Z were ${\pm}$8.1㎝, ${\pm}$24.7㎝, ${\pm}$35.9㎝, respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.3
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• pp.173-179
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• 2015

In this paper, object-based classification of urban areas based on a combination of information from lidar and aerial images is introduced. High resolution images are frequently used in automatic classification, making use of the spectral characteristics of the features under study. However, in urban areas, pixel-based classification can be difficult since building colors differ and the shadows of buildings can obscure building segmentation. Therefore, if the boundaries of buildings can be extracted from lidar, this information could improve the accuracy of urban area classifications. In the data processing stage, lidar data and the aerial image are co-registered into the same coordinate system, and a local maxima filter is used for the building segmentation of lidar data, which are then converted into an image containing only building information. Then, multiresolution segmentation is achieved using a scale parameter, and a color and shape factor; a compactness factor and a layer weight are implemented for the classification using a class hierarchy. Results indicate that lidar can provide useful additional data when combined with high resolution images in the object-oriented hierarchical classification of urban areas.

• Korean Journal of Remote Sensing
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• v.37 no.1
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• pp.1-11
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• 2021

This study measures the change of ice flow velocity of David Glacier, one of the fast-moving glaciers in East Antarctica that drains through Drygalski Ice Tongue. In order to effectively observe the rapid flow velocity, we applied the offset tracking technique to Sentinel-1A SAR images obtained from 2016 to 2020 with 36-day temporal baseline. The resulting velocity maps were averaged and the two relatively fast points (A1 and A2) were selected for further time-series analysis. The flow velocity increased during the Antarctic summer (around December to March) over the four years' observation period probably due to the ice surface melting and reduced friction on the ice bottom. Bedmap2 showed that the fast flow velocities at A1 and A2 are associated with a sharp decrease in the ice surface and bottom elevation so that ice volumetric cross-section narrows down and the crevasses are being created on the ice surface. The local maxima in standard deviation of ice velocity, S1 and S2, showed random temporal fluctuation due to the rotational ice swirls causing error in offset tracking method. It is suggested that more robust offset tracking method is necessary to incorporate rotational motion.

• Structural Engineering and Mechanics
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• v.77 no.3
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• pp.355-368
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• 2021

The time-varying mean (TVM) component of non-stationary wind speeds is commonly extracted utilizing empirical mode decomposition (EMD) in practice, whereas the accuracy of the extracted TVM is difficult to be quantified. To deal with this problem, this paper proposes an approach to identify and extract the optimal TVM from several TVM results obtained by the EMD. It is suggested that the optimal TVM of a 10-min time history of wind speeds should meet both the following conditions: (1) the probability density function (PDF) of fluctuating wind component agrees well with the modified Gaussian function (MGF). At this stage, a coefficient p is newly defined as an evaluation index to quantify the correlation between PDF and MGF. The smaller the p is, the better the derived TVM is; (2) the number of local maxima of obtained optimal TVM within a 10-min time interval is less than 6. The proposed approach is validated by a numerical example, and it is also adopted to extract the optimal TVM from the field measurement records of wind speeds collected during a sandstorm event.