• Journal of Digital Convergence
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• v.19 no.12
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• pp.165-173
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• 2021

The purpose of this study was to provide directions to help enter and expand long-distance routes by analyzing the characteristics of AirAsia X's network construction with Malaysia Airlines. To this end, long-distance route data was extracted from the OAG Schedule Analyzer and the network was analyzed on a two-period basis using SNA. Since AirAsia X's entry into long-range routes, Malaysia Airlines has steadily reduced its routes across the entire region. On the other hand, it is analyzed that AirAsia X is building an expanded network by increasing its network in Northeast Asia instead of ultra-long range routes. Studies have shown that LCCs also have potential growth in the long-distance route market of less than 7,000 km. The results of this study may help LCC establish a long-distance market entry and network deployment strategy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.1037-1048
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• 2018

In this paper, we investigated the international guidelines and actual disposal maneuver cases to prepare KOMPSAT-2 post mission disposal. And then, disposal maneuver plan was established using current propellant of KOMPSAT-2 and verification was also performed to find out whether the international guidelines are satisfied. As a result, the lifetime of KOMPSAT-2 was 3.6 years when 45kg propellant was used to decrease perigee altitude to 300km. And if more than 14.5kg propellant consumed for same strategy, KOMPSAT-2 can satisfy the international guidelines. Finally, re-entry survivability analysis was performed and it represented that heat resistant objects, such as propellant tank and reaction wheel, could be survived but total ground casualty probability was less than international guidelines.

• Biomolecules & Therapeutics
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• v.30 no.4
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• pp.360-367
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• 2022

Tropomyosin receptor kinase A (TrkA) protein is a receptor tyrosine kinase encoded by the NTRK1 gene. TrkA signaling mediates the proliferation, differentiation, and survival of neurons and other cells following stimulation by its ligand, the nerve growth factor. Chromosomal rearrangements of the NTRK1 gene result in the generation of TrkA fusion protein, which is known to cause deregulation of TrkA signaling. Targeting TrkA activity represents a promising strategy for the treatment of cancers that harbor the TrkA fusion protein. In this study, we evaluated the TrkA-inhibitory activity of the benzoxazole compound KRC-108. KRC-108 inhibited TrkA activity in an in vitro kinase assay, and suppressed the growth of KM12C colon cancer cells harboring an NTRK1 gene fusion. KRC-108 treatment induced cell cycle arrest, apoptotic cell death, and autophagy. KRC-108 suppressed the phosphorylation of downstream signaling molecules of TrkA, including Akt, phospholipase Cγ, and ERK1/2. Furthermore, KRC-108 exhibited antitumor activity in vivo in a KM12C cell xenograft model. These results indicate that KRC-108 may be a promising therapeutic agent for Trk fusion-positive cancers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.98-105
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• 2023

This paper studies the effects of global climate change on Gyeonggi Bay and appropriate adaptation strategies. Located along the west coast of Korea, Gyeonggi Bay is renowned as one of the five most important global tidal flats (wetlands). Due to climate change in Gyeonggi Bay, the water temperature is predicted to increase by 1.44 ℃ by the year 2100, the salinity to decrease by 1.1 PSU, the sea level to rise by 35.2 cm, and approximately 150.5 km² of the coast to be submerged due to the rising sea levels. Adaptation strategies to combat negative impacts of climate change on the ecological environment of Gyeonggi Bay include 1) supporting the self-adaptation capability of Gyeonggi Bay's natural environment to be sustainable, and 2) protecting lowlands adjacent to tidal flats and low-lying areas of the coast against human involvement to reserve more space for upslope shifts of biota with rising sea levels.

• Korean Journal of Environment and Ecology
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• v.18 no.2
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• pp.175-183
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• 2004

They are raising the necessity to prepare the conservational management strategy for the trail on the ridge of the Baekdudaegan where deterioration of natural environment along the trail as the rapid increase of visitors to the Baekdudaegan. The purpose of this study, followed after the Kwon and Lee(2003), is to research the deterioration condition of the trail between Namdeogyusan and Sosagogae on the Baekdudaegan. To accomplish the purpose, not only trail condition such as altitude, entire width, bare width, maximum depth and slope of trail, but also deterioration types of trail were surveyed at the total 182 points for 32.3km in length. Furthermore, impact rating class, which could be effective means to check the step and extent of deterioration process, was judged on each points of trail. Results informs us that the deterioration condition of the trail between Namdeogyusan and Sosagogae is not reached the level of grave concern yet, but some points and sections of trail are in urgent need of the integrated and organized maintenance. And some managerial strategies of trail were proposed in connection with the maintenance for trail on the Baekdudaegan ridge.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.3
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• pp.147-154
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• 2011

Decision making in Environmental Impact Assessment (EIA) and Consultation on the Coastal Area Utilization (CCAU) is footing on the survey reports, thus requires concrete and accurate information on the natural habitats. In spite of the importance of reporting the ecological quality and status of habitats, the accumulated knowledge and recent techniques in ecology such as the use of investigated cases and indicators/indices have not been utilized in evaluation processes. Even the EIA report does not contain sufficient information required in a decision making process for conservation and development. In addition, for CCAU, sampling efforts were so limited that only two or a few stations were set in most study cases. This hampers transferring key ecological information to both specialist review and decision making processes. Hence, setting the effective number of sampling stations can be said as a prior step for better assessment. We introduced a few statistical techniques to determine the number of sampling stations in macrobenthos surveys. However, the application of the techniques requires a preliminary study that cannot be performed under the current assessment frame. An analysis of the spatial configuration of sampling stations from 19 previous studies was carried out as an alternative approach, based on the assumption that those configurations reported in scientific journal contribute to successful understanding of the ecological phenomena. The distance between stations and number of sampling stations in a $4{\times}4$ km unit area were calculated, and the medians of each parameter were 2.3 km, and 3, respectively. For each study, approximated survey area (ASA, $km^2$) was obtained by using the number of sampling stations in a unit area (NSSU) and total number of sampling stations (TNSS). To predict either appropriate ASA or NSSU/TNSS, we found and suggested statistically significant functional relationship among ASA, survey purpose and NSSU. This empirical approach will contribute to increasing sampling effort in a field survey and communicating with reasonable data and information in EIA and CCAU.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.32-38
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• 2020

This study examined the problems of existing vehicles to propose alternatives to improve the crashworthiness of railway freight cars through collision acceleration analysis using a one-dimensional collision analysis method. A collision scenario of railway shunting and crash accidents was selected from the collision accident cases and international standards. A one-dimensional collision simulation using LS-DYNA was performed according to those scenarios. As a result, the acceleration level of the freight wagon was calculated to be under 2g and was predicted to meet the EN 12663 standard in the shunting situation. On the other hand, the result of crash simulation with an impact velocity between 10 and 15 km/h revealed the shock absorber capacity of the railway coupler to be insufficient in a crash situation, resulting in increased acceleration, and carbody deformation could be predicted. As a method of improving the crashworthiness, a deformation tube-type energy absorber was applied to the coupler system, and collision analysis was performed again with new energy absorption strategy. Overall, the simulation showed that the acceleration level was decreased by 12% of the conventional freight-car energy absorption system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1032-1039
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• 2012

The present paper deals with precise relative positioning of formation satellites with long baseline in low Earth orbit making use of L1/L2 dual frequency GPS carrier phase measurements. Kinematic approach means to describe the motion of objects without taking its mass/dynamics model into consideration. The advantage of the kinematic approach is that information about dynamics of the system is not applied, which gives more flexibility and could improve the scientific interest of the observations made by the mission. The ionosphere terms, which are not canceled by double differenced measurement equation in the case of the long baseline, are explicitly estimated as unknown parameters by extended Kalman filter. The estimated float ambiguities by EKF are solved by existing efficient integer vector search strategy under integer least square condition. For the integer vector search, we employ well known MLAMBDA. Finally, The feasibility and accuracy of processing scheme are demonstrated using the GPS measurements for two satellites in low Earth orbit separated by baselines of 100 km.

• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.237-245
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• 2015

A strategy is needed for a regional survey of geosynchronous orbits (GSOs) to monitor known space objects and detect uncataloged space objects. On the basis of the Inter-Agency Debris Committee's recommendation regarding the protected region of geosynchronous Earth orbit (GEO), target satellites with perigee and apogee of $GEO{\pm}200km$ and various inclinations are selected for analysis. The status of the GSO region was analyzed using the satellite distribution based on the orbital characteristics in publicly available two-line element data. Natural perturbation effects cause inactive satellites to drift to two stable longitudinal points. Active satellites usually maintain the designed positions as a result of regular or irregular maneuver operations against their natural drift. To analyze the detection rate of a single optical telescope, 152 out of 412 active satellites and 135 out of 288 inactive satellites in the GSO region were selected on the basis of their visibility at the observation site in Daejeon, Korea. By using various vertical view ranges and various numbers of observations of the GSO region, the detection efficiencies were analyzed for a single night, and the numbers of follow-up observations were determined. The orbital estimation accuracies were also checked using the arc length and number of observed data points to maintain the GSO satellite catalog.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.465-473
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• 2005

In the analysis of the foreign cases on the use of Transit Signal Priority(TSP), the reduction in bus travel time ranged from 6 to $32\%$. This study demonstrates how TSP can be applied to Ulsan Metropolitan City. TSP techniques were used on the bus routes that run eastward for 4.07 kilometers along Munsoo-Ro, a major artery in the most congested part of the city. The simulation was performed on one hour of peak traffic time, using the two TSP strategies of Early Green and Extended Green. The use of the Early Green strategy resulted in an average decrease in travel time ranging from 18.1 to $25.8\%$ and an increase in average travel speed ranging from 30.9 to $40.1\%$. The Extended Green strategy resulted in an average decrease in travel time ranging from 18.1 to $30.3\%$ and an increase in an average travel speed of approximately $30.1\%$. This study demonstrates that TSP is effective in decreasing travel time and increasing travel speed of the bus system in Korea.