• Korean Journal of Remote Sensing
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• v.33 no.3
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• pp.267-274
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• 2017

The purpose of this research was to develop and present methods to detect sinkholes which can exist underneath the surface of the ground. First, we buried a water tank with dimensions $1.8{\times}0.8{\times}0.8m$ at a distance of 1.8 m from the surface. This played the role of the sinkhole. Secondly, we created a square zone with sides 12 meters away from the buried water tank. Within this zone, we measured the gravity at 1-meter intervals using a Scintrex CG5 relative gravimeter with a resolution of 0.001 mGal. Additionally, we performed three-dimensional (3-D) gravity modeling to calculate the theoretical values of the relative gravity around our model sinkhole. The resulting values for the relative gravity around the sinkhole depended on the method used. The measured effect of gravity was 0.036 mGal and the effect calculated using 3-D modeling was 0.024 mGal. Our results suggest that sinkholes that are similar in size to the water tank used in this study can be detected using relative gravity surveys. Smaller sinkholes can be detected by reducing the intervals between the relative gravity measurements.

• Journal of Korean Neurosurgical Society
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• v.67 no.2
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• pp.137-145
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• 2024

In adult spinal deformity (ASD) surgery, mechanical failure (MF) has been a significant concern for spine surgeons as well as patients. Despite earnest endeavors to prevent MF, the absence of a definitive consensus persists, owing to the intricate interplay of multifarious factors associated with this complication. Previous approaches centered around global spinal alignment have yielded limited success in entirely forestalling MF. These methodologies, albeit valuable, exhibited limitations by neglecting to encompass global balance and compensatory mechanisms within their purview. In response to this concern, an in-depth comprehension of global balance and compensatory mechanisms emerges as imperative. In this discourse, the center of gravity and the gravity line are gaining attention in recent investigations pertaining to global balance. This narrative review aims to provide an overview of the global balance and a comprehensive understanding of related concepts and knowledge. Moreover, it delves into the clinical ramifications of the contemporary optimal correction paradigm to furnish an encompassing understanding of global balance and the current optimal correction strategies within the context of ASD surgery. By doing so, it endeavors to furnish spine surgeons with a guiding compass, enriching their decision-making process as they navigate the intricate terrain of ASD surgical interventions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1174-1182
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• 1999

Recently the shape information of the visual object in the scene is more important, as the completion of the MPEG-4 standard and the progress of the MPEG-7 standard. This paper represents the study of effective coding method of vertices that are used in the polygonal approximation to represent the feature of visual object. In the proposed method, we make the centers of gravity of triangles that are made using the vertices of polygonal approximation and encode them sequentially We can get a coding gain because the centers of the gravity of triangles have narrower dynamic ranges.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.531-536
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• 2022

Megacities are emerging all over the world and gradually becoming the center of an country. Therefore, Megacities are inevitably exposed to various threats such as existing, potential, supra-national, and non-military. In particular, as seen in the recent Ukraine-Russia war, national infrastructure systems has become a major target of enemies. However, considering the size of Megacities, various types of threats, and limited resources, it is impossible to completely protect all national infrastructure systems. Therefore, wisdom is necessary to identify and protect critical nodes. The critical node is the vital point to which the national infrastructure is connected. To this end, in this study, as a method for logically and systematically identifying critical nodes, Node centrality analysis method, which is a network theory, and the Center of Gravity analysis method, which is a military theory, were presented.

• Structural Engineering and Mechanics
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• v.88 no.3
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• pp.251-262
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• 2023

This paper presents a method for assessing the dynamic responses of gravity-based structures (GBS) under various seismic loads, with a focus on fluid-structure-ground interactions. Models of GBSs and their surrounding environments were developed, incorporating interaction effects among the structure, seawater, and seabed. Dynamic responses of the GBS subjected to three seismic loads-Chi-Chi, Northridge01, and Northridge02-were calculated, with consideration of both horizontal and vertical accelerations, as well as displacements. Parametric studies indicated that the primary factors affecting the dynamic responses of GBS were seismic loads characterized by significant input forces and accelerations. The frictional force on the ground had minimal impact on the horizontal and vertical displacements of the GBS. Weight emerged as a critical factor in anchoring the GBS to the ground and minimizing vertical accelerations and displacements.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.672-685
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• 2003

Yew (Taxus cuspidata Sieb.) chose that grow as medicine, food, decorative plant in Korea's Kyong-Gi province surroundings. Extracts of yew extracted leaf of 250 g and stems of 300 g with 1,3-butylene glycol (1,3-BG), propylene glycol (PG) and water. As results, external appearance of leaf extract of yew was slightly brown clear extract. The pH was 5.3$\pm$0.5, and specific gravity was 1.012$\pm$0.05, and refractive index was 1.375$\pm$0.05. Also, appearance of stem's extract was slightly brown clear extract, and the pH was 5.4$\pm$0.5, and specific gravity was 1.016$\pm$0.05, and refractive index was 1.358$\pm$0.05. Oil of yew separated from seeds, and extracted polysaccharide high purity from fruits. As a result, specific gravity of oil was 0.987, and obtained 40％ of yield. Total polyphenols amount of yew extract is detected 0.563％ in leaves, 0.325％ in stems, whereas total tannins amount contained 0.054％ and 0.037％ each in leaves and stems. As effect in cosmetics, the anti-oxidative effect by DPPH method is 75.0％ in leaves, and stems was 64.0％. Collagen synthesis rate was shown high activity by 54.16％ in stem's extract, 33.18％ in leaves' extract. Also, PPE-inhibitory activities were 13.7％ and 23.5％ each in leaves and stems. Anti-inflammatory effect of yew seed oil displayed superior effect of 41 ％ than control. Polysaccharide's molecular weight that is gotten from fruits was 5$\times$10$^4$~ 3$\times$10$^{5}$ dalton, and got 20.0$\pm$5％ of yield.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.343-356
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• 2003

Yew (Taxus cuspidata Sieb.) chose that grow as medicine, food, decorative plant in Korea's Kyong-Gi province surroundings. Extracts of yew extracted leaf of 250 g and stems of 300 g with 1,3-butylene glycol (1,3-BG), propylene glycol (PG) and water. As results, external appearance of leaf extract of yew was slightly brown clear extract. The pH was 5.3$\pm$0.5, and specific gravity was 1.012$\pm$0.05, and refractive index was 1.375$\pm$0.05. Also, appearance of stem's extract was slightly brown clear extract, and the pH was 5.4$\pm$0.5, and specific gravity was 1.016$\pm$0.05, and refractive index was 1.358$\pm$0.05. Oil of yew separated from seeds, and extracted polysaccharide high purity from fruits. As a result, specific gravity of oil was 0.987, and obtained 40% of yield. Total polyphenols amount of yew extract is detected 0.563% in leaves, 0.325% in stems, whereas total tannins amount contained 0.054% and 0.037% each in leaves and stems. As effect in cosmetics, the anti-oxidative effect by DPPH method is 75.0% in leaves, and stems was 64.0%. Collagen synthesis rate was shown high activity by 54.16% in stem's extract, 33.18% in leaves' extract. Also, PPE-inhibitory activities were 13.7% and 23.5% each in leaves and stems. Anti-inflammatory effect of yew seed oil displayed superior effect of 41 % than control. Polysaccharide's molecular weight that is gotten from fruits was 5$\times$10$^4$~3$\times$10$^{5}$ dalton, and got 20.0$\pm$5% of yield.

• Korea Trade Review
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• v.45 no.3
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• pp.119-132
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• 2020

In this paper we explore the two analyses to know the urbanization effect on trade. First, the granger causality test to examine the relationship between trade and urbanization. The Granger causality test is a statistical hypothesis test for determining whether one time series is useful for forecasting another. The results indicated that the existence of a bidirectional causality running from trade to urbanization when six lags were applied. When eight lags were applied, we found unidirectional causality running from urbanization to trade. Second, gravity models were used to investigate the urbanization effect on trade. The production cost and specification are affected by the economies of scale, and the economies of scale increased as the greater geographically agglomeration. However, the gravity model to explain the bilateral trade flows ignores the urbanization variables. Therefore we added the urbanization variable represented as the geographically agglomeration into gravity model. The results show that the degree of urbanization of both countries has statistically positive effect on trade (export and import) and the bigger coefficients of trade partner's urbanization. The reason is that the trade share of industrial supplies, intermediate goods and capital goods is much higher than finished consumer goods. The urbanization is more important the improved the efficiency of production than demand market.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.957-965
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• 2013

This study simulated the egg vertical distribution of mackerel Scomber japonicus in Korean waters using general numerical models. All eggs were spawned naturally by raising broodfishes (May-June 2013), and the egg specific gravity was measured by a density-gradient column. CTD surveys provided environmental data (e.g., temperature and salinity) in May near Jeju Island, Korea. The egg specific gravity during the early stages ranged from 1.0203-1.0211. In general, the fertilized eggs showed a gradual decline in egg specific gravity until full development of the main organs, with a sudden increase just before hatching. Modeled egg vertical distributions were influenced more by wind speed than by egg buoyancy and vertical structure of the sea water. During calm and normal wind speeds, the eggs were distributed from the surface to 25-m depths. Under strong wind conditions (three times higher than the normal speed), the egg concentration on the surface decreased, and the egg distributional depth was deeper (~50 m).

• Proceedings of the Korea Society of Design Studies Conference
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• 2005.10a
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• pp.152-153
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• 2005