• Korean Journal of Radiology
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• v.22 no.6
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• pp.867-879
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• 2021

Objective: To compare the screening performance of diffusion-weighted (DW) MRI and combined mammography and ultrasound (US) in detecting clinically occult contralateral breast cancer in women with newly diagnosed breast cancer. Materials and Methods: Between January 2017 and July 2018, 1148 women (mean age ± standard deviation, 53.2 ± 10.8 years) with unilateral breast cancer and no clinical abnormalities in the contralateral breast underwent 3T MRI, digital mammography, and radiologist-performed whole-breast US. In this retrospective study, three radiologists independently and blindly reviewed all DW MR images (b = 1000 s/mm² and apparent diffusion coefficient map) of the contralateral breast and assigned a Breast Imaging Reporting and Data System category. For combined mammography and US evaluation, prospectively assessed results were used. Using histopathology or 1-year follow-up as the reference standard, cancer detection rate and the patient percentage with cancers detected among all women recommended for tissue diagnosis (positive predictive value; PPV2) were compared. Results: Of the 30 cases of clinically occult contralateral cancers (13 invasive and 17 ductal carcinoma in situ [DCIS]), DW MRI detected 23 (76.7%) cases (11 invasive and 12 DCIS), whereas combined mammography and US detected 12 (40.0%, five invasive and seven DCIS) cases. All cancers detected by combined mammography and US, except two DCIS cases, were detected by DW MRI. The cancer detection rate of DW MRI (2.0%; 95% confidence interval [CI]: 1.3%, 3.0%) was higher than that of combined mammography and US (1.0%; 95% CI: 0.5%, 1.8%; p = 0.009). DW MRI showed higher PPV2 (42.1%; 95% CI: 26.3%, 59.2%) than combined mammography and US (18.5%; 95% CI: 9.9%, 30.0%; p = 0.001). Conclusion: In women with newly diagnosed breast cancer, DW MRI detected significantly more contralateral breast cancers with fewer biopsy recommendations than combined mammography and US.

• Land and Housing Review
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• v.15 no.4
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• pp.33-41
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• 2024

This research proposes a monitoring system using Unmanned Ground Vehicles (UGVs) to address the issue of ground subsidence in urban areas. In environments where Unmanned Aerial Vehicles (UAVs) face limitations due to urban obstacles, UGVs offer an effective alternative. This research aims to equip UGVs with various sensors, establish adaptive sensing management suitable for urban ground subsidence monitoring, and evaluate their effectiveness. The study involves creating a risk map by identifying areas with a high likelihood of subsidence and categorizing them into monitoring zones (M zones) that require frequent monitoring and saving zones (S zones) that allow for energy saving. A strategy is proposed to adjust the sensing intervals of the navigation sensor (NS), which detects the UGV's location, and the monitoring sensor (MS), which monitors subsidence-related factors, according to these zones. Tests simulating typical urban deep excavation scenarios confirmed that adjusting the sensing intervals of MS and NS reduces energy consumption substantially. The study highlights the importance of optimizing energy consumption based on the UGV's monitoring path, suggesting that this approach can enhance urban safety by effectively monitoring ground subsidence.

• Korea and Global Affairs
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• v.1 no.1
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• pp.71-96
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• 2017

This study speculates on responses to the nuclear threats of North Korea and mutual assistance and cooperation between South Korea, the U.S. and China for the unification of the Korean Peninsula. As for the North Koreas nuclear issue and unification of the Korean Peninsula, South Korea is the subject of national division, the U.S. is a responsible country in international issues and does not have diplomatic ties with North Korea. China is a traditional socialist nation and a supporter of North Korea. As North Korea's strategic weapons including nuclear weapons and ballistic missiles are international issues, to defend against Kim Jung-Eun's unexpected acts, the three countries should actively cooperate with each other and develop countermeasures. However, with respect to the road map of the North Koreas issue, there are subtle differences between the U.S. and China in recognition of and sanctions against North Korea as a resolution of the U..N. Security Council. The U.S. has continued a deterrence policy and sanctions against North Korea based on joint threats between South Korea and the U.S. while China has showed a negative position in the process of solving the North Korean nuclear issue because of the unstable security derived from the U.S. 's intervention in the Korean peninsula. North Korea should change its diplomatic policy in a more concrete way towards world peace although it has continued trade of strategic weapons with Middle Eastern countries to maintain its political system. For example, to restart the summit talks and open multilateral security channels. Although the issue of unification of the Korean peninsula should be resolved by South and North Korea themselves, it is strange that South and North Korea depend on the logic of powerful countries for the resolution of a national problem. As for North Koreas nuclear and the Unification issues, peaceful solutions presented by South Korea seem more persuasive than the solution presented by North Korea which did not secure any international support. However, South Korea, the U.S. and China need to develop uni-directional two-tract strategies for sanctions against North Korea and talks with North Korea for peace on the Korean peninsula, and should continue to support the economic independence of North Korea.

• Journal of Korean Society of Forest Science
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• v.87 no.3
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• pp.358-365
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• 1998

To offer the basic information for sustainable production of forest resources and conservation of the global environment, change in potential natural vegetation (PNV) associated with climate change due to doubling atmospheric carbon dioxide ($2{\times}CO_2$) was estimated with the global natural vegetation mapping system based an K${\ddot{o}}$ppen scheme. The system interpolates climate data spherically to each grid cell, determines the vegetation types onto the grid cell, and produces potential vegetation map and area on the globe and continents. The climate data consist of the current, ($1{\times}CO_2$) climate prior to AD 1958 observed at some 2,000 stations and the doubling ($2{\times}CO_2$) climate estimated from Meteorological Research Institute of Japan. The vegetation zone under the $2{\times}CO_2$ climate scenario expanded mainly toward the poles due to the rise in temperature. The changed PNV area on the globe amounts to 1/3 (4.91 billion (G) ha) of the total land area (15.04 Gha). Kappa statistic for judging agreement between the patterns of vegetation distribution under $1{\times}CO_2$ climate and $2{\times}CO_2$ climates shows good agreement (0.63) for the globe as a whole. The most stable areas are desert and ice. The potential forest area (PFA) was estimated at 6.82 Gha of the land area in $2{\times}CO_2$ climate scenario. In terms of continental changes in PFA, North America and Asis are increased under the $2{\times}CO_2$ climate. However, the potential forest arms of the other continents are decreased by the climate. Europe has no change in the PFA. Especially, the expansion of desert area in Oceania would be accelerated by the $2{\times}CO_2$ climate.

• The KIPS Transactions:PartD
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• v.13D no.7 s.110
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• pp.985-996
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• 2006

As the internet technologies develop, the geographic information system environment is changing to the web-based service. Since geospatial information of the existing Web-GIS services were developed independently, there is no interoperability to support diverse map formats. In spite of the same geospatial information object it can be used for various proposes that is duplicated in GIS separately. It needs intelligent strategies for optimal replica selection, which is identification of replication geospatial information objects. And for management of replication objects, OMG, GLOBE and GRID computing suggested related frameworks. But these researches are not thorough going enough in case of geospatial information object. This paper presents a model of location service, which is supported for optimal selection among replication and management of replication objects. It is consist of tree main services. The first is binding service which can save names and properties of object defined by users according to service offers and enable clients to search them on the service of offers. The second is location service which can manage location information with contact records. And obtains performance information by the Load Sharing Facility on system independently with contact address. The third is intelligent selection service which can obtain basic/performance information from the binding service/location service and provide both faster access and better performance characteristics by rules as intelligent model based on rough sets. For the validity of location service model, this research presents the processes of location service execution with Graphic User Interface.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.2052-2063
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• 1998

Various full-scale radio location systems have been developed since ground-based radio navigation systems appeared during World War II, and more recently global positioning systems (GPS) have been widely used as a representative location system. In addition, radio location systems based on cellular systems are intensively being studied as cellular services become more and more popular. However, these studies have been focused mainly on macrocellular systems of which based stations are mutually synchronized. There has been no study about systems of which based stations are asynchronous. In this paper, we proposed two radio location algorithms in microcellular CDMA systems of which base stations are asychronous. The one is to estimate the position of a personal station at the center of rectangular shaped area which approximates the realistic common area. The other, as a method based on road map, is to first find candidate positions, the centers of roads pseudo-range-distant from the base station which the personal station belongs to and then is to estimate the position by monitoring the pilot signal strengths of neighboring base stations. We compare these two algorithms with three wide-spread algorithms through computer simulations and investigate interference effect on measuring pseudo ranges. The proposed algorithms require no recursive calculations and yield smaller position error than the existing algorithms because of less affection of non-line-of-signt propagation in microcellular environments.

• Journal of the Korean Geographical Society
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• v.50 no.6
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• pp.571-605
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• 2015

This research revealed that 'Yipjiamlyu' in the Mukedeng's map is geographically 'a beginning point of underf low,' whose location is on the Heishigou's riverbed(E.L. 1,840m) in the NNE side of Daegakbong peak, and that 'Tomungangweon'(Heishigou) is one of the upstream reach of the Sungari River, which, according to historical documents and my fieldwork, Mukedeng also knew at the time of Yimjin(1712) Boundary Making and Demarcation(YBMD). These findings suggest the need to reinterpret the processes of YBMD. Mukedeng set up the Baekdusanjeonggyeobi on the mistaken assumptions on the linkage of 'Yipjiamlyu' and Tumen River. It should have been set up on the Daeyeonjibong peak. Mukedeng found the 'Yipjiamlyu' on the riverbed of 'Tomungangweon'(Heishigou), went downstream, and realized that this river did not flow into the Tumen River. During the search for the source of Tumen River, he found a water stream, and regarded it as the source of Tumen River. He speculated that the water at the 'Yipjiamlyu' flows through the underground to reappear at the his 'identified' source of Tumen River. Consequently, he adjured the construction of demarcation from Baekdusanjeonggyeobi through 'Yipjiamlyu' to the his 'identified' source of Tumen River. The water stream pointed as the source of Tumen River, however, was not part of the upstream reach of Tumen River. Actually, Korean officials, who were in charge of establishing boundary features, set up the demarcation from Baekdusanjeonggyeobi through Huanghuasongdianzi to the true source of Tumen River identified by themselves, which Mukedeng had not intended. The ambiguity of the location of 'Yipjiamlyu' caused a difference between Mukedeng's original request and Korean officials' implementation in the boundary demarcation. Throughout the whole processes of YBMD, Korea(Joseon) and China(Qing) both mistook the real geography of the river system. Their understanding on Yalu River system was correct. But the identification of the spring source of the Tumen River by Korean participants was the only geographically correct result related on this river system in YBMD.

• Korean Journal of Heritage: History & Science
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• v.54 no.4
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• pp.174-191
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• 2021

Gangdo (江都), a reproduction of Gaegyeong, was the capital of Goryeo for 39 years. However, due to the urgent wartime situation of the Mongol invasion and the geographical features of Ganghwa Island, the castle system and palace layout were somewhat different from those of Gaegyeong. Gangdo's castle can be understood as a triple castle system consisting of outer castle, middle castle, and inner castle. First, the outer castle was the first to be completed, and it was built at the forefront to prevent the Mongol army from invading in the first place. It is presumed that the section was between Huamdon and Hwadodon in the outer castle during the Joseon Dynasty. The middle castle can be seen as the present 'Middle Castle', a castle built of earth on the outskirts of the Ganghwa-mountain Castle. Considering the sophistication and robustness of the construction method confirmed in the archaeological research, this castle is thought to have been built under a meticulous plan. In other words, as the capital city, it was completed 'at last' as recorded in the Koryo History, after a long 18-year construction process to protect palaces, government offices, and private houses. The inner castle was a castle with the character of a palace. This corresponds to the Old Castle of Ganghwabu (江華府) during the Joseon Dynasty, and it almost coincided with the scale of the composition of Gaegyeong's palace castle. It was a complex functional space, featuring the integration of the palace and the imperial castle, where the main government offices and ancillary facilities, including the palace, were located. Based on the documentary record that these palaces were similar to Gaegyeong's palace, the palace map was overlapped with that of Gaegyeong. The central axis of the building from Seungpyeongmun (昇平門) to Seongyeongjeon (宣慶殿) coincided with Kim Sangyongsunjeol Monument in Ganghwa- Goryeo Palace. Therefore, it seems that the palace of Gangdo had the same basic structure as that of Gaegyeong. However, the inner palace and annexed buildings must have been arranged in consideration of the topographical conditions of Ganghwa, and this is estimated to be the Gunggol area in Gwancheong-ri.

• Korean Journal of Heritage: History & Science
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• v.51 no.3
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• pp.72-87
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• 2018

This study highlights a drainage gate and a ditch, which existed around the whole area of the western shore of Wolji Pond(月池) and focuses on a possible connection between the drainage facility on the western shore and the historical drainage system of Wolji Pond. Specifically, it primarily considered locations and the form of a drainage gate, the relationship between northwestern ditch of Wolji Pond and the drainage gate, and the establishment period and the character of the drainage facility on the western shore. The drainage gate found in excavation in 1975 is determined as the same facility as Surakgu(水落口) recorded on an actual measurement drawing, 1922. Therefore, it is highly probable that there were already the drainage facility in the western shore of Wolji Pond before the 1920s. The drainage gate constructed by processing rectangular stones has four drainage holes for controlling water level. The way of the drainage through the drainage holes is the same as that of the northern shore of Wolji Pond. From a cadastral map drawn in 1913, it is found that the ditch existed in northwest of Wolji Pond. The ditch was proximate to the drainage gate and shared the same axes. Hence, the ditch and the drainage gate are determined as a organic facility connected to the drainage system of Wolji Pond. In particular, the ditch existed in northwest of Wolji Pond is the basis for judging that the drainage facility in the western shore were established before the 1910s. Water flowed in through drainage holes of the drainage gate is drained into the northwest of Wolji Pond, through the ditch. The establishment period and the intention of the drainage facility on the western shore can be interpreted in two aspects. First, they might be 'a agricultural irrigation facility in the Joseon era', given that Wolji Pond was recorded as a agricultural reservoir, and that the whole northwestern area of Wolji Pond was used as farm land areas. Second, they might be 'a drainage facility for controlling the water level in creating Wolji Pond', given that the drainage gate was annexed to the lower shore forming the waterline of Wolji Pond, and that the hight of drainage holes on top of the drainage gate was similar to the full water level of Wolji Pond. Considering the related grounds and circumstance, the latter possibility is high.

• Journal of the Korea Society of Computer and Information
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• v.29 no.9
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• pp.125-136
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• 2024

This study presents an automated Python algorithm for analyzing rainfall characteristics to establish critical rainfall thresholds as part of a landslide early warning system. Rainfall data were sourced from the Korea Meteorological Administration's Automatic Weather System (AWS) and the Korea Forest Service's Automatic Mountain Observation System (AMOS), while landslide data from 2020 to 2023 were gathered via the Life Safety Map. The algorithm involves three main steps: 1) processing rainfall data to correct inconsistencies and fill data gaps, 2) identifying the nearest observation station to each landslide location, and 3) conducting statistical analysis of rainfall characteristics. The analysis utilized power law and nonlinear regression, yielding an average R² of 0.45 for the relationships between rainfall intensity-duration, effective rainfall-duration, antecedent rainfall-duration, and maximum hourly rainfall-duration. The critical thresholds identified were 0.9-1.4 mm/hr for rainfall intensity, 68.5-132.5 mm for effective rainfall, 81.6-151.1 mm for antecedent rainfall, and 17.5-26.5 mm for maximum hourly rainfall. Validation using AUC-ROC analysis showed a low AUC value of 0.5, highlighting the limitations of using rainfall data alone to predict landslides. Additionally, the algorithm's speed performance evaluation revealed a total processing time of 30 minutes, further emphasizing the limitations of relying solely on rainfall data for disaster prediction. However, to mitigate loss of life and property damage due to disasters, it is crucial to establish criteria using quantitative and easily interpretable methods. Thus, the algorithm developed in this study is expected to contribute to reducing damage by providing a quantitative evaluation of critical rainfall thresholds that trigger landslides.