• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.110-121
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• 2016

Link-16 is a representative TDL operated by US air force and NATO and supports structure of Multi-net. Under Multi-net, military operation can be conducted effectively since terminal nodes in Link-16 hop over total frequency band simultaneously. As air traffic is rapidly increasing, new aeronautical system is introduced or existing system should be expanded to accommodate increasing air traffic and frequency band assigned for operating this system is scarce. It is scheduled to implement frequency remapping to solve frequency scarcity. With limited frequency band for operating Link-16, as frequency remapping is implemented, degradation of Multi-net performance can happen since multiple access interference in Link-16 is increasing so it is difficult to conduct multiple military operations. Thus, Group-based frequency hopping scheme is proposed to solve this problem. We verified the performance of the proposed scheme is improved.

• The KIPS Transactions:PartB
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• v.12B no.7 s.103
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• pp.829-840
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• 2005

Word Sense Disambiguation(WSD) is one of the most difficult problem in Korean information processing. We propose a WSD model with the capability to filter semantic information using the specific characteristics in dictionary dictions, and nth added information, useful to sense determination, such as statistical, distance and case information. we propose a model, which can resolve the issues resulting from the scarcity of semantic information data based on the word hierarchy system (thesaurus) developed by Ulsan University's UOU Word Intelligent Network, a dictionary-based toxicological database. Among the WSD models elaborated by this study, the one using statistical information, distance and case information along with the thesaurus (hereinafter referred to as 'SDJ-X model') performed the best. In an experiment conducted on the sense-tagged corpus consisting of 1,500,000 eojeols, provided by the Sejong project, the SDJ-X model recorded improvements over the maximum frequency word sense determination (maximum frequency determination, MFC, accuracy baseline) of $18.87\%$ ($21.73\%$ for nouns and inter-eojeot distance weights by $10.49\%$ ($8.84\%$ for nouns, $11.51\%$ for verbs). Finally, the accuracy level of the SDJ-X model was higher than that recorded by the model using only statistical information, distance and case information, without the thesaurus by a margin of $6.12\%$ ($5.29\%$ for nouns, $6.64\%$ for verbs).

• Animal Systematics, Evolution and Diversity
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• v.14 no.3
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• pp.173-192
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• 1998

This study was made as a part of the benethic fauna of Geojedo Island. The material was obtained from 17 localities (Fig. 1) along the coastal sea of Geojedo Island and it's adjacent waters during the years 1995-1998. This paper includes 38 species from a limited area of the southern part of Korea and includes 13 previously known species by Rho(1975-1991). Of these Didemnum (D.) pardum, Symplegma oceania, and Styela coriacea, are new to the Korean fauna, and 22 species are newly added to the fauna of Geojedo Island. We provided taxonomic notes and brief notes on the ascidian fauna, and the biogeographical distribution of Geojedo island. Its ascidian fauna are characterized by a high percentage of 18(47.4%) warm-water species and the extreme scarcity of eight(21.1%) boreal-water forms. This result may be attributable to the fact that Geojedo island and its adajacent waters are located under the influence of the warm Kuroshio Current.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.801-810
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• 2019

This study analyzes the impact on geomorphic changes downstream due to alternate bars developed weir upstream through laboratory experiments. The disturbance, such as a spur in the side wall, of the flow at the inlet of the channel triggers the development of alternate bar upstream at the beginning of the experiment, and gradually moved downstream with keeping their shapes over time. The bed in the downstream of weir in the mid of channel scoured due to the scarcity of sediment inflow because weir upstream traps it. Moreover, bar migration speed decreases as the bars approaches to the weir with time. However, as time increases, the alternate bars upstream migrate over the weir, and sediment in the eroded bed of the weir downstream are deposited. The phase of the bar upstream changes oppositely after passing through the weir. The phase of the bar downstream changes rapidly as the shape of alternate bar is clear upstream, which is affected by the strong disturbance. The phase of bar changes, and the bar migration speed decreases gradually with time, and finally stopped due to forcing effects on the bar by the disturbance. The faster the reaction of alternate bar with a long spur, the larger the bar height formed downstream and the shorter the bar length. This means that the larger the forcing effect of bar, the more it affects the bar migration. In addition, although the size of the alternate bar increases over time, the bar doesn't migrate downstream and a forced bar is generated.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.232-232
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• 2019

The persistence of drought periods and water scarcity is a growing public concern, as climate change projections indicate a more critical scenario in the future. The sustainability of water resources for the increasing population, and to ensuring crop production will unarguably be a daunting task for the water resources managers, with a projected 9.8 billion people by 2050 as well as the need to increase food production by 70 to 100%. Consequently, there is a need for significant irrigation water use for more crop production in the face of stiff competition among water users. However, the available natural resources are already over-constrained, and the allocation of more resources for food production is not feasible. Currently, about two-thirds of global water withdrawer is used by the agricultural sector while 48% of water resources in Korea is used for agricultural production. Despite the apparent ecological deficit and unfavorable conditions of resources utilization, a staggering amount of food waste occurs in the country. Moreover, wastage of food translates to waste of all the resources involved in the food production including water resources. Food waste can also be considered a serious potential for economic and environmental problems. Hence, exploring an alternative approach to efficient resources utilization in a more sustainable way can ensure considerable resources conservation. We hypothesized that reducing food waste will decline the demand for food production and consequently reduce the pressure on water resources. We investigated the food wastage across the food supply chain using the top-down datasets based on the FAO mass balance model. Furthermore, the water footprint of the estimated food wastage was assessed using the representative of selected food crops. The study revealed that the average annual food wastage across the food supply chain is 9.05 million tonnes, signifying 0.51 kg/capita/day and 48% of domestic food production. Similarly, an average of 6.29 Gm3 per annum of water resources was lost to food wastage, which translates to 40% of the total allotted water resources for agriculture in the country. These considerable resources could have been conserved or efficiently used for other purposes. This study demonstrated that zero food waste generation would significantly reduce the impact on freshwater resources and ensure its conservation. There is a need for further investigation on the food waste study using the bottom-up approach, specifically at the consumer food waste, since the top-down approach is based on estimations and many assumptions were made.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.408-408
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• 2019

The persistence of drought periods and water scarcity is a growing public concern, as climate change projections indicate a more critical scenario in the future. The sustainability of water resources for the increasing population, and to ensuring crop production will unarguably be a daunting task for the water resources managers, with a projected 9.8 billion people by 2050 as well as the need to increase food production by 70 to 100%. Consequently, there is a need for significant irrigation water use for more crop production in the face of stiff competition among water users. However, the available natural resources are already over-constrained, and the allocation of more resources for food production is not feasible. Currently, about two-thirds of global water withdrawer is used by the agricultural sector while 48% of water resources in Korea is used for agricultural production. Despite the apparent ecological deficit and unfavorable conditions of resources utilization, a staggering amount of food waste occurs in the country. Moreover, wastage of food translates to waste of all the resources involved in the food production including water resources. Food waste can also be considered a serious potential for economic and environmental problems. Hence, exploring an alternative approach to efficient resources utilization in a more sustainable way can ensure considerable resources conservation. We hypothesized that reducing food waste will decline the demand for food production and consequently reduce the pressure on water resources. We investigated the food wastage across the food supply chain using the top-down datasets based on the FAO mass balance model. Furthermore, the water footprint of the estimated food wastage was assessed using the representative of selected food crops. The study revealed that the average annual food wastage across the food supply chain is 9.05 million tonnes, signifying 0.51 kg/capita/day and 48% of domestic food production. Similarly, an average of $6.29Gm^3$ per annum of water resources was lost to food wastage, which translates to 40% of the total allotted water resources for agriculture in the country. These considerable resources could have been conserved or efficiently used for other purposes. This study demonstrated that zero food waste generation would significantly reduce the impact on freshwater resources and ensure its conservation. There is a need for further investigation on the food waste study using the bottom-up approach, specifically at the consumer food waste, since the top-down approach is based on estimations and many assumptions were made.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.133-133
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• 2016

지구온난화와 그에 따른 기후변화로 수자원부족현상이 전지구적으로 나타남에 따라 세계 각국은 물부족 현상을 극복하기 위해 다양한 대처방안을 찾고 있다. 가상수 이론은 전세계적 차원에서 상품에 내재된 가상수를 통해 물을 공급하고 배분함으로써 물부족을 해결할 수 있다는 주장으로서 물부족현상에 처한 세계 각국의 관심을 끌고 있다. 특히 향후 국제적 수준에서 물거래에 대한 조치가 예상됨에 따라 이에 가상수가 국가간에 얼마나 어떠한 형태로 이동하는지 '가상수 이동'에 대한 정보가 필요하게 되었다. 그럼에도 불구하고 지금까지의 가상수 흐름에 대한 정보는 미국이나 일본 등을 중심으로 한 자료뿐이었다. 한국을 중심으로 한국의 관심사를 반영한 가상수 이동에 대한 연구결과는 충분하지 않았다. 따라서 본 연구에서는 전세계적 수준에서의 가상수 이동추이를 한국을 중심으로 분석하도록 한다. 분석수준은 전세계적 수준과 국가간 수준이며, 분석기간은 1989년부터 2014년까지 총 26년이다. 분석 대상은 가상수 교역이 활발한 주요 16개국의 11개 농축산물이다. 분석을 위한 자료로는 UN과 세계식량기구의 자료를 활용해 데이터셋을 구축했다. 분석결과 전세계적 수준에서는 콩, 옥수수, 밀, 보리가 주요 가상수 수출입 품목으로 밝혀졌다. 시기별로는 1999년 까지는 밀의 교역이 압도적이었으나 1999년 이후 콩 가상수의 교역이 증가하고 있는 것으로 파악되었다. 가상수의 유형과 관련해서는 녹색가상수의 교역이 청색가상수보다 압도적으로 많았으며, 국가간의 가상수 이동량은 지속적으로 증가하고 있는 추세임을 알 수 있었다. 가상수의 주요 수출국은 미국을 비롯해 브라질, 아르헨티나, 호주 등 농업대국이 상위권을 차지했고, 주요 수입국은 중국, 일본, 한국 등 동북아시아 국가들이었다. 가상수 수출은 미국이 분석기간 내내 우위를 차지하나, 2000년대 이후 중국의 부상이 눈에 띄는 변화라고 할 수 있다. 가상수 수입과 관련해서는 2000년대 이후 중국의 가상수 수입 증가 추세가 두드러졌다. 국가간 수준의 분석에서는 한국과 미국, 한국과 중국, 한국과 호주 등 한국의 주요 가상수 교역국가간의 흐름을 분석했다. 국가간 수준의 분석에서 특기할 만한 점은 미국에서 한국으로 이동한 전체 가상수의 81퍼센트를 녹색가상수가 차지하며, 한국에서 중국으로 이동한 가상수의 74퍼센트가 축산물 가상수라는 점이었다. 본 연구의 분석결과를 기반으로 해 향후에는 가상수 이동 데이터베이스를 구축할 것이 요구되며, 가상수 이동추이의 변화가 가져올 시나리오에 대한 연구도 필요하다고 할 수 있다.

• Journal of Korea Port Economic Association
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• v.35 no.2
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• pp.1-20
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• 2019

This study aims to establish a method for activating Korean ship finance through an analysis on the development of Chinese ship finance market, which has grown rapidly in recent years. It focuses on its main institutions, laws and policies, strengths and weaknesses, market share, and development status. Because 80.7% of South Korea's economy depends upon foreign trade and 99.7% of the South Korea's traded volume is transported by ships, shipping has assumed an important role in Korean economy. However, since the global financial crisis, Korean shipping and shipbuilding industry has been facing difficulties and Hanjin, the biggest Korean shipping company, went bankrupt in 2017. One of the key aspects of the competitiveness of the shipping and shipbuilding industry is acquiring competitive shipping assets; therefore, stable and smooth supply of ship finance is crucial for the development of the shipping and shipbuilding industry. Given this background, the study analyzed how the Chinese ship finance market has grown rapidly in the past 30 years and identified the problems, strengths, and weaknesses of the Chinese ship finance. The analysis on the status of the Chinese ship finance market is expected to suggest a direction for establishing methods for activating the Korean ship finance market, which is facing scarcity of finance, even as the global ship finance market has remained depressed since the global financial crisis. Although this study focused exclusively on the Chinese market, future research can draw conclusions from a comparative analysis that includes the Japanese ship finance market; the conclusions obtained would contribute to the establishment of long-term policies and plans for Korean ship finance.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.3
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• pp.133-140
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• 2022

We investigate the performance of deep learning-based Korean language models on a task of predicting the score range of Korean essays written by foreign students. We construct a data set containing a total of 304 essays, which include essays discussing the criteria for choosing a job ('job'), conditions of a happy life ('happ'), relationship between money and happiness ('econ'), and definition of success ('succ'). These essays were labeled according to four letter grades (A, B, C, and D), and a total of eleven essay score range prediction experiments were conducted (i.e., five for predicting the score range of 'job' essays, five for predicting the score range of 'happiness' essays, and one for predicting the score range of mixed topic essays). Three deep learning-based Korean language models, KoBERT, KcBERT, and KR-BERT, were fine-tuned using various training data. Moreover, two traditional probabilistic machine learning classifiers, naive Bayes and logistic regression, were also evaluated. Experiment results show that deep learning-based Korean language models performed better than the two traditional classifiers, with KR-BERT performing the best with 55.83% overall average prediction accuracy. A close second was KcBERT (55.77%) followed by KoBERT (54.91%). The performances of naive Bayes and logistic regression classifiers were 52.52% and 50.28% respectively. Due to the scarcity of training data and the imbalance in class distribution, the overall prediction performance was not high for all classifiers. Moreover, the classifiers' vocabulary did not explicitly capture the error features that were helpful in correctly grading the Korean essay. By overcoming these two limitations, we expect the score range prediction performance to improve.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.2
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• pp.83-88
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• 2022

The purpose of this study is to present an analysis and implications for the metaverse-based virtual real estate transaction service. Through blockchain-based technology and metaverse, the world we live in is expanding naturally. Therefore, changes in the environment and perceptions of market participants are also very important factors. The concept and thinking about the existing asset value change and investment are also changing. This means that you can generate profits through value and investment in intangible assets. The service user aspect is a case of investing in the future value of virtual real estate that if more users participate rather than the present value, the principle of supply and demand will be applied to increase the number of consumers and the price will naturally rise according to the principle of scarcity. The service provider provides a technical platform for the service to directly transact the portion of the virtual area considered of interest directly through the virtual real estate purchase business. As the number of participants increases as well as funds and transaction fees, various revenue models such as advertisements can be discovered and provided. It plays the role of providing jobs and information through new services. As a stakeholder, governments can exploit the emergence of new technologies and products to create people and services and secure economic benefits. Of course, various institutional supports should be provided so that new services can settle in the market while mitigating risk factors. This study is meaningful in that it contributes to the establishment of a domestic metaverse-based environment and related research and is utilized in the study of virtual space real estate services.