• Journal of Korea Port Economic Association
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• v.32 no.2
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• pp.137-156
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• 2016

This study analyzes the optimal service levels of exclusive container terminals in terms of the optimal berth occupancy rate and the ships' waiting ratios, based on the number of berths. We develop a simulation model using berth throughput data from pier P, Busan New Port, a representative port in Korea, and apply the simulation results to different numbers of berths. In addition to the above results, we analyze the financial data and costs of delayed ships and delayed cargoes for the past three years from the viewpoints of the terminal operation company (TOC), shipping companies, and shippers to identify the optimal service level for berth occupancy rates that generate the highest net profit. The results show that the optimal levels in the container terminal are a 63.4% berth occupancy rate and 10.6% ship waiting ratio in berth 4,66.0% and 9.6% in berth 5, and 69.0% and 8.5% in berth 6. However, the results of the 2013 study by the Ministry of Maritime Affairs and Fisheries showed significantly different optimal service levels: a 57.1% berth occupancy rate and 7.4% ship waiting ratio in berth 4; 63.4% and 6.6% in berth 5; and 66.6% and 5.6% in berth 6. This suggests that optimal service level could change depending on when the analysis is performed. In other words, factors affecting the optimal service levels include exchange rates, revenue, cost per TEU, inventory cost per TEU, and the oil price. Thus, optimal service levels can never be fixed. Therefore, the optimal service levels for container terminals need to be able to change relatively quickly, depending on factors such as fluctuations in the economy, the oil price, and exchange rates.

• Journal of the Geological Society of Korea
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• v.54 no.6
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• pp.657-675
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• 2018

The apparent thickening of the subducting slab in the shallow lower mantle has been attributed to slab buckling. However, the scaling laws have not been quantitatively evaluated for the buckling behavior of the subducting slab when phase transformations are considered. Thus, two-dimensional dynamic subduction experiments are formulated to evaluate the effect of phase transformations on the buckling behavior of the subducting slab. The model calculations show that the phase transformation from olivine to wadsleyite at a depth of 410 km plays an important role in the development of slab buckling; increased slab pull due to the endothermic phase transformation accelerates slab sinking in the upper mantle and the subducting slab reaches the lower mantle in a shorter time than that of the experiments without the phase transformation. However, the phase transformation from ringwoodite to perovskite plus $magnesiow{\ddot{u}}stite$ at a depth of 660 km retards slab sinking into the lower mantle and the subducting slab tends to be accumulated in the transformation (transition) zone. Buckling analyses show that the scaling laws predict the buckling amplitude and period of the subducting slab with small relative errors even if the phase transformations are considered. The universal phenomenon of the slab buckling can explain apparent slab thickening in the shallow lower mantle and transformation zone under the subduction zones such as Java-Sunda and Northeast Japan. In addition, the buckling behavior of the subducting slab may be related to the periodic compressions and extensions in the Cretaceous Gyeongsang basin.

• Korean Journal of Remote Sensing
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• v.24 no.4
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• pp.309-324
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• 2008

In this study the retrieval algorithms have been developed to retrieve total precipitable water (TPW) from Terra/Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) infrared measurements using a physical iterative retrieval method and a split-window technique over East Asia. Retrieved results from these algorithms were validated against Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I) over ocean and radiosonde observation over land and were analyzed for investigating the key factors affecting the accuracy of results and physical processes of retrieval methods. Atmospheric profiles from Regional Data Assimilation and Prediction System (RDAPS), which produces analysis and prediction field of atmospheric variables over East Asia, were used as first-guess profiles for the physical retrieval algorithm. We used RTTOV-7 radiative transfer model to calculate the upwelling radiance at the top of the atmosphere. For the split-window technique, regression coefficients were obtained by relating the calculated brightness temperature to the paired radiosonde-estimated TPW. Physically retrieved TPWs were validated against SSM/I and radiosonde observations for 14 cases in August and December 2004 and results showed that the physical method improves the accuracy of TPW with smaller bias in comparison to TPWs of RDAPS data, MODIS products, and TPWs from split-window technique. Although physical iterative retrieval can reduce the bias of first-guess profiles and bring in more accurate TPWs, the retrieved results show the dependency upon initial guess fields. It is thought that the dependency is due to the fact that the water vapor absorption channels used in this study may not reflect moisture features in particular near surface.

• The Journal of the Petrological Society of Korea
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• v.23 no.3
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• pp.279-292
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• 2014

Nd isotopic compositions analyzed from the Phanerozoic granitoids of Korea are integrated and discussed. Variations in Nd isotopic compositions can be explained either by temporal trend or by regional differences. Among the three active periods, first two periods during the Permian-Triassic and Jurassic seem to show variations from rather high ${\varepsilon}_{Nd}(t)$ values at the beginning to lower ${\varepsilon}_{Nd}(t)$ values during the later stages. Such trends probably reflect melting of the subducting oceanic crust and producing magma with higher proportion of depleted mantle derived materials during the early stage of subduction process, and subsequent magmas with greater proportion of old continental crust with progress of subduction. However, the Cretaceous-Paleogene period of active magmatism displays higher ${\varepsilon}_{Nd}(t)$ values during the advanced stage of the igneous activities, which is opposite to the previous active periods. The other explanation is that such differences in ${\varepsilon}_{Nd}(t)$ reflect regional differences, based on the observations that such high-${\varepsilon}_{Nd}(t)$ granitoids distribute in the northeastern Gyeongbuk Province and Gyeongsang Basin. If this is the case, the regions with highr ${\varepsilon}_{Nd}(t)$ values may have distinct crustal evolution histories, e.g. younger average age. The choice between the two hypothesis could be made through further studies.

• Journal of the Korea Convergence Society
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• v.10 no.2
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• pp.133-139
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• 2019

A Convergence Research Study of Southern Fujian Region in China during the Song Dynasty analyzing the Export of Ceramics During the Song Dynasty in China ceramics made in the Southern Fujian (also known as Minnan) region were exported to different countries in Southeast Asia including the Philippines, Thailand and more. They were even exported to Korea, Japan and through trade they traveled as far as Africa. Ceramics was one of the three main sea route export item of China at the time and there were active commercial trading between Korea as well as other countries, enabling ceramics to develop rapidly. The harmonious reciprocal relationship between the geographical, political, cultural, economical characteristics of Southern Fujian enabled a unique type of celadon ware widely recognized to develop. Ceramics of this region is one of a kind in terms of history when we relate it to research on integrating different elements. It suggests a unique convergence of culture when we study its forms and its industrial characteristics. The study attempts to analyze the influence of geography, politics, economy and culture on the different phenomena found in ceramics. Different paradigms associated with changes of environment reflect on continued development in the field of ceramics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.23-28
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• 2019

The structural integrity of a surface metal coating was evaluated through numerical results to improve the efficiency and reduce the damage caused by cavitation in ships and marine plants. The goal was to ensure structural strength and performance, even if the thickness of the wing is reduced to reduce the weight of the material and surface coating. Analytical methods were used for four models: a non-coating model, one with the same thickness after coating, one with a thickness reduction of 3% after coating, and one with thickness reduction of 5% after coating. With a thickness reduction of 5% after coating, the stress was increased to 12%, and the safety factor was 0.99%, so the structural integrity was insufficient. However, a better material or a thicker coating could allow a sufficient safety factor to be secured. The structural integrity was improved by the coating, and even when the weight was reduced up to 5%, the structural integrity could be sufficiently secured due to the coating effect.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.2
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• pp.1-14
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• 2019

In rural areas, composting is a source of non-point pollutants. However, as the quantitative distribution and loading have not been estimated, it is difficult to determine the effect of composting on stream water quality. In this study, composting datum acquired by unmanned aerial vehicle(UAV) was verified by using terrestrial LiDAR, and the management status and load change of the composting was investigated by UAV with manual control flight, thereby obtaining the basic data to determine the effect on the water system. As a result of the comparative accuracy assessment based on terrestrial LiDAR, the difference in the digital surface model(DSM) was within 0.21m and the accuracy of the volume was 93.24%. We expect that the accuracy is sufficient to calculate and utilize the composting load acquired by UAV. Thus, the management status of composting can be investigated by UAV. As the total load change of composting were determined to be $1,172.16m^3$, $1,461.66m^3$, and $1,350.53m^3$, respectively, the load change of composting could be confirmed. We expect that the results of this study can contribute to efficient management of non-point source pollution by UAV.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.925-939
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• 2018

Absorbed shortwave radiation at the surface is an important component of energy analysis among the atmosphere, land, and ocean. In this study, the absorbed shortwave radiation was calculated using a radiation model and surface broadband albedo data for application to Geostationary Earth Orbit Korea Multi-Purpose SATellite (GEO-KOMPSAT-2A; GK-2A). And the results (GWNU algorithm) were compared with CERES data and calculation results using pyranometer and MODIS (Moderate Resolution Imaging Spectroradiometer) data to be selected as the reference absorbed shortwave radiation. This GWNU algorithm was also compared with the physical and statistical algorithms of GOSE-R ABI and two algorithms (Li et al., 1993; Kim and Jeong, 2016) using regression equation. As a result, the absorbed shortwave radiation calculated by GWNU algorithm was more accurate than the values calculated by the other algorithms. However, if the problem about computing time and accuracy of albedo data arise when absorbed shortwave radiation is calculated by GWNU algorithm, then the empirical algorithms explained above should be used with GWNU algorithm.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.383-393
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• 2019

The purpose of this study was to investigate the improvement effect of turmeric (Curcuma longa L.) on the hepatic functional enzyme and catalase activity of streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley (SD) male rats were divided into four groups (n=6), and fed experimental diets containing turmeric meal [basal diet+5% turmeric (BT), basal diet+STZ+5% turmeric (ST)], and control (basal diet, BD), BS groups (basal diet+STZ). Serum concentrations of creatinine and blood urea nitrogen (BUN) were significantly decreased (p<0.05) by 5% turmeric supplementation diet. The activities of akaline phosphatase (ALP), lactate dehydrogenase (LDH), aspartate transaminase (AST), alanine transaminase (ALT), amylase and lipase were decreased in the BD, BT and ST group than BS group. The catalase (CAT) activity was significantly increased (p<0.05) in turmeric supplementation diet (BT, ST group) than diabetic group (BS). Furthermore, the activities of amylase and lipase in the sera of turmeric diet group were significantly decreased (p<0.05). In vivo experiments with diabetic rats showed that ingestion of turmeric supplementation diet were effective in creatinine concentration, and hepatic functional enzyme activities.

• Journal of Life Science
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• v.29 no.10
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• pp.1120-1125
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• 2019

The short-lived nematode Caenorhabditis elegans has been used as a model organism for many studies, including lifespan extension. To screen common seaweeds for natural anti-aging agents, the lifespan of C. elegans (N2 wild-type strain) was measured by its hatch rate, growth rate, survival rate, chemotaxis, brood size, and egg-laying time after exposure to nematode growth medium (NGM) containing seaweed extracts. Approximately 30 animals synchronized at the first larval stage were incubated until they reached their adult stages before laying their eggs and were transferred to fresh NGM every 3 days. We also identified the major active compound from the seaweed by gas chromatography-mass spectrometry and tested its optimal dose for longevity. Of 13 common seaweed species, an ethanol extract of the brown seaweed Hizikia fusiformis showed the greatest effect on hatching, growth, and survival rates. The lifespan of C. elegans was significantly expanded 1.54-fold and 1.23-fold in the presence of the ethanol extract (0.05 mg/ml) and the main active component, fucosterol (0.05 mg/ml), respectively. Exposure to the ethanol extract also increased chemotaxis 1.13-fold, decreased brood size 0.74-fold, and shortened egg-laying time 0.96-fold. These results suggest that the aquaculturable H. fusiformis may be a promising source of a diet supplement to support health care.