• KDI북한경제리뷰
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• v.22 no.4
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• pp.41-58
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• 2020

1998~2017년 북한의 교역을 관측한 결과, 북한의 대중 교역 비중은 꾸준히 증가하여 2017년에는 그 비중이 94.8%까지 높아진 것으로 관찰됐다. 즉, 동기간의 북한의 대중국 교역 의존도가 급증한 것을 확인 할 수 있다. 이러한 북한의 대중국 교역 의존도가 북한만의 특이한 교역 구조인지 확인하기 위해 본고는 ① 전세계, ② 아시아, ③ 중국 접경 국가를 비교군으로 설정하여 시계열 및 횡단면 비교를 각각 실시하였다. 먼저 시계열로 비교한 결과 1998~2017년 전 기간 동안 북한은 전세계, 아시아, 중국 접경 국가 보다 대중국 교역의존도가 현저히 높았던 것으로 나타났다. 또한 북한은 대중국 교역의존도 증가 추세 역시 가장 가파른 국가로 확인됐다. 예를 들어, 1998년 북한의 대중국 교역 의존도는 24.8%, 아시아 지역의 대중국 교역 의존도는 6.5%로 북한이 아시아 지역에 비해 약 3.8배 높았으나, 2017년의 경우 북한 94.8%, 아시아 19.4%로 약 4.9배 더 높은 것으로 나타나 지난 20년 동안 북한의 대중국 교역 의존도가 다른 전세계 국가들에 비해 가파르게 증가한 것으로 나타났다. 구체적으로 중국 접경 국가군에 소속된 개별 국가와 비교한 결과, 북한 다음으로 대중국 교역 의존도가 높고, 가파르게 증가한 국가는 몽골과 미얀마인 것으로 관찰된다. 그러나 몽골, 미얀마는 북한에 비해서 대중국 교역 의존도 증가 추세는 상대적으로 완만하다. 다음으로, 본고에서 설정한 최종 관측연도인 2017년 한해에 대해 횡단면 비교를 실시하였다. 횡단면 비교에서는 대중국 교역 의존도를 수출입 의존도로 세분화하여 비교하고, 대중국 GDP 의존도를 추가하여 비교했다. 그 결과 2017년 북한의 대중국 수출입 의존도 모두 전세계, 아시아, 중국 접경 국가들 중 가장 높은 순위를 기록했다. 특이한 점은 북한의 대중국 교역의존도는 수출보다 수입에서 높게 나타난 반면, 북한 다음으로 대중국 교역 의존도가 높은 몽골과 미얀마의 경우 수입보다 수출의 대중국 의존도가 높게 나타났다는 점이다. 대중국 GDP 의존도의 경우 북한은 중국 접경 국가들 중 몽골과 베트남 다음으로 의존도가 높은 국가로 확인된다. 추가적으로 2017년의 북한, 몽골 및 미얀마의 교역 특징을 알아보았다. 먼저 북한, 몽골, 미얀마의 대중 교역 품목을 비교한 결과 이들 3개국 모두 공통적으로 주로 석탄, 천연가스 등의 천연자원을 중국에 수출한다는 특징을 가진다. 그러나 수입의 경우 북한은 대두유와 같은 식량류와 합성 직물, 무선 전화기 등을 주로 수입하는 반면, 몽골과 미얀마는 산업 생산에 필요한 에너지 및 부속품을 주로 수입한다는 차이점이 있었다. 다음으로, 2017년 북한과 몽골, 미얀마가 가장 많이 교역한 중국의 성(省)을 비교해본 결과, 북한은 요녕성, 몽골은 내몽고자치구, 미얀마는 운남성과의 교역이 가장 많았다는 것을 확인 할 수 있었다. 이를 통해 대중 교역 의존도가 높은 3개 국가들이 중국과 국경을 접한 성(省)과 가장 교역을 많이 한다는 특징을 확인할 수 있었다.

• Korean Journal of Construction Engineering and Management
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• v.24 no.6
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• pp.66-73
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• 2023

The construction industry suffers losses due to failures in demand forecasting due to price fluctuations in construction raw materials, increased user costs due to project cost changes, and lack of forecasting system. Accordingly, it is necessary to improve the accuracy of construction raw material price forecasting. This study aims to predict the price of construction raw materials and verify applicability through the improvement of the Data Refactor technique. In order to improve the accuracy of price prediction of construction raw materials, the existing data refactor classification of low and high frequency and ARIMAX utilization method was improved to frequency-oriented and ARIMA method utilization, so that short-term (3 months in the future) six items such as construction raw materials lumber and cement were improved. ), mid-term (6 months in the future), and long-term (12 months in the future) price forecasts. As a result of the analysis, the predicted value based on the improved Data Refactor technique reduced the error and expanded the variability. Therefore, it is expected that the budget can be managed effectively by predicting the price of construction raw materials more accurately through the Data Refactor technique proposed in this study.

• Korean Journal of Remote Sensing
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• v.39 no.5_4
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• pp.1075-1084
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• 2023

Satellite-derived data is collected by observing the Earth and is used in various fields such as national defense, natural disasters, location-based services, infrastructure, environment, energy, marine, and insurance. This study aims to present the virtuous cycle structure of the satellite information data industry and the business ecosystem model of the industry. As a research method, cases were collected and categorized from the following areas: literature, online, application, and content. The results show that the ecosystem model of the satellite information data industry provides an approach to content services in public and commercial areas, and develops various algorithmic technologies to facilitate content production and services at the level of complex general-purpose technologies. Second, in terms of content typology, satellite information data can be subdivided into monitoring content, urban space monitoring content, and satellite information content. Third, the consumption value of satellite content could be subdivided into informational value, environmental, social and governance (ESG) value, educational value, and content value. In order to expand the global content market, Korea will need to focus on creating an ecosystem for the satellite information industry and discovering differentiated content. It will also need to increase the popularization and accessibility of data to the general public and promote the Korean K-Satellite Information Data Industry ecosystem through government support, policy efforts, and policies such as establishing legal systems, increasing investment, and training human resources.

• Journal of the Korea Society for Simulation
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• v.32 no.4
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• pp.77-84
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• 2023

In the agricultural sector, power sources are being developed that use alternative energy sources such as electric tractors and hydrogen tractors, away from internal combustion engine tractors. As parts such as engines and transmissions used in conventional internal combustion engine tractors are replaced with motors and batteries, the center of gravity changes, and thus the risk of rollover should be considered. The purpose of this study is to analyze the overturn angle of the main parts of the electric tractor through dynamic simulation to minimize the overturn accident and to derive the optimal arrangement of parts to improve stability. A total of nine dynamics simulations were conducted by designing three components of the PTO motor, drive motor and the battery pack, and three factors of the arrangement method. As a result of the experiment, it was confirmed that Type3 Level3, in which the drive motor and the PTO motor are located at the front and rear of the tractor, and two battery packs are located in the middle of the tractor, has a high rollover angle. As a result of this study, the stability increased as the center of gravity was placed backward and located below. Future research needs to be done to find the optimal location of parts considering their performance and placement efficiency.

• Tunnel and Underground Space
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• v.33 no.6
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• pp.445-471
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• 2023

Long-term safety over millennia is the top priority consideration in the construction of disposal sites. However, ensuring the mechanical stability of deep geological repositories for spent fuel, a.k.a. radwaste, disposal during construction and operation is also crucial for safe operation of the repository. Imposing restrictions or limitations on tunnel support and lining materials such as shotcrete, concrete, grouting, which might compromise the sealing performance of backfill and buffer materials which are essential elements for the long-term safety of disposal sites, presents a highly challenging task for rock engineers and tunnelling experts. In this study, as part of an extensive exploration to aid in the proper selection of disposal sites, the anticipation of constructing a deep geological repository at a depth of 500 meters in an unknown state has been carried out. Through a review of 2D and 3D numerical analyses, the study aimed to explore the range of properties that ensure stability. Preliminary findings identified the potential range of rock properties that secure the stability of central and disposal tunnels, while the stability of the vertical tunnel network was confirmed through 3D analysis, outlining fundamental rock conditions necessary for the construction of disposal sites.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.1-10
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• 2023

Due to the development of the industrial revolution, regulations on exhaust emissions have been continuously strengthened to reduce the rapidly increasing greenhouse gas emissions. The use of environmentally friendly fuels is essential to meet these regulations. Hydrogen has been attracting attention as a future environmentally friendly fuel, but due to its material properties, it faces significant challenges in handling and storage. As an alternative, ammonia has been proposed. Ammonia can be easily liquefied at room temperature compared to hydrogen and has a high energy density. In order to examine the applicability of ammonia as an engine fuel, experiments were conducted to investigate the effects of changes in combustion control parameters in a direct injection ammonia combustion engine. The experiments were conducted by varying two variables: spark timing and excessive air ratio. Observations were made on combustion stability and the trends of exhaust emissions such as nitrogen oxides and unburned ammonia under the conditions of an engine speed of 1,500 rpm and medium to high loads (brake torque of 200 Nm). By optimizing the combustion control parameters, conditions for stable combustion even when using ammonia as the sole fuel were identified, and plans are underway to apply strategies for future expansion of the operating range.

• Journal of Internet Computing and Services
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• v.25 no.2
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• pp.79-92
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• 2024

ChatGPT, as a representative chatbot leveraging generative artificial intelligence technology, is used valuable not only in scientific and technological domains but also across diverse sectors such as society, economy, industry, and culture. This study conducts an explorative analysis of user sentiments and needs for ChatGPT by examining global social media discourse on Reddit. We collected 10,796 comments on Reddit from December 2022 to August 2023 and then employed keyword analysis, sentiment analysis, and need-mining-based topic modeling to derive insights. The analysis reveals several key findings. The most frequently mentioned term in ChatGPT-related comments is "time," indicative of users' emphasis on prompt responses, time efficiency, and enhanced productivity. Users express sentiments of trust and anticipation in ChatGPT, yet simultaneously articulate concerns and frustrations regarding its societal impact, including fears and anger. In addition, the topic modeling analysis identifies 14 topics, shedding light on potential user needs. Notably, users exhibit a keen interest in the educational applications of ChatGPT and its societal implications. Moreover, our investigation uncovers various user-driven topics related to ChatGPT, encompassing language models, jobs, information retrieval, healthcare applications, services, gaming, regulations, energy, and ethical concerns. In conclusion, this analysis provides insights into user perspectives, emphasizing the significance of understanding and addressing user needs. The identified application directions offer valuable guidance for enhancing existing products and services or planning the development of new service platforms.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.3
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• pp.18-32
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• 2024

This study aims to analyze the summer human thermal environment in Jeju City's outdoor parking lots by measuring microclimate data and comparing pavement and vegetation albedoes and elements through computer simulations. In measured cases, results due to albedo showed no significance, but there was a significant difference between sunny and shaded areas by trees. The sunny area had a PET (physiological equivalent temperature) in the 'very hot' level, while the shaded area exhibited a 2-step lower 'warm' level. UTCI (universal thermal climate index) also showed that the sunny area was in the 'very strong heat stress' level, whereas the shaded area was 1-step lower in the 'strong heat stress' level, confirming the role of trees in reducing incoming solar radiant energy. Simulation results, using the measured albedoes, closely resembled the measured results. Regarding vegetation, scenarios with a wide canopy, high leaf density, and narrow planting spacing were effective in mitigating the human thermal environment, and the differences due to tree height varied across scenarios. The scenario with the lowest PET value was H9W9L3D8 (tree height 9m, canopy width 9m, leaf area index 3.0, planting spacing 8m), indicating a 0.7-step decrease compared to the current landscaping scenario. Thus, it was confirmed that, among landscaping elements, trees have a significant impact on the summer human thermal environment compared to ground pavement.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.403-409
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• 2024

In this paper, the guidelines for the design of an Artificial Intelligence(AI) based Integrated Process Safety Management(PSM) system to enhance workplace safety using data from process safety reports submitted by hazardous and risky facility operators in accordance with the Occupational Safety and Health Act is proposed. The system composed of the proposed guidelines is to be implemented separately by individual facility operators and specialized process safety management agencies for single or multiple workplaces. It is structured with key components and stages, including data collection and preprocessing, expansion and segmentation, labeling, and the construction of training datasets. It enables the collection of process operation data and change approval data from various processes, allowing potential fault prediction and maintenance planning through the analysis of all data generated in workplace operations, thereby supporting decision-making during process operation. Moreover, it offers utility and effectiveness in time and cost savings, detection and prediction of various risk factors, including human errors, and continuous model improvement through the use of accurate and reliable training data and specialized datasets. Through this approach, it becomes possible to enhance workplace safety and prevent accidents.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.6
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• pp.920-926
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• 2010

Marine alga, Chlorella vulgaris, was extracted by chloroform-methanol (2:1, v/v) solvents for lipid extraction at $35^{\circ}C$ for five hours (HCM-35) and its process was compared with conventional lipid extraction condition such as chloroform-methanol (2:1, v/v) at $65^{\circ}C$ for one hour (CM-65). This low temperature extraction process showed that 80% of total lipid was extracted and its residues contained relatively unchanged amounts of intact proteins and other minerals as well as amino acid profiles. Interestingly enough, the weight fraction of carbohydrate in the residues slightly increased due to less denaturation at low process temperature. The biological activities of the residues such as cytotoxicity and immune cell growth activation were not much changed after being extracted. The sensory evaluation were found to be very favorable for being used as a food additive and/or food supplement. This result could also help to maintain the economic feasibility of utilizing marine resources in food and other relevant industries.