• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.65-76
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• 2024

With the recent activation of the offshore wind power industry, there has been a development of power plants with a scale exceeding 400MW, comparable to traditional thermal power plants. Renewable energy, characterized by intermittency depending on the energy source, is a prominent feature of modern renewable power generation facilities, which are structured based on controllable inverter technology. As the integration of renewable energy sources into the grid expands, the grid codes for power system connection are progressively becoming more defined, leading to active discussions and evaluations in this area. In this paper, we propose a method for selecting optimal reactive power compensation capacity when multiple offshore wind farms are integrated and connected through a shared interconnection facility to comply with grid codes. Based on the requirements of the grid code, we analyze the reactive power compensation and excessive stability of the 400MW wind power generation site under development in the southwest sea of Jeonbuk. This analysis involves constructing a generation site database using PSS/E (Power System Simulation for Engineering), incorporating turbine layouts and cable data. The study calculates reactive power due to charging current in internal and external network cables and determines the reactive power compensation capacity at the interconnection point. Additionally, static and dynamic stability assessments are conducted by integrating with the power system database.

• Journal of the Korea Society of Computer and Information
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• v.29 no.4
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• pp.83-89
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• 2024

After the end of the service of Internet Explorer, the use of ActiveX ended, and the Non-ActiveX policy spread. HTML5 is used as a standard protocol for web pages established based on the Non-ActiveX policy. HTML5, developed in the W3C(World Wide Web Consortium), provides a better web application experience through API, with various elements and properties added to the browser without plug-in. However, new security vulnerabilities have been discovered from newly added technologies, and these vulnerabilities have widened the scope of attacks. There is a lack of research to find possible security vulnerabilities in HTML5-applied websites. This paper proposes a model for detecting tags and attributes with web vulnerabilities by detecting and analyzing security vulnerabilities in web pages of public institutions where plug-ins have been removed within the last five years. If the proposed model is applied to the web page, it can analyze the compliance and vulnerabilities of the web page to date even after the plug-in is removed, providing reliable web services. And it is expected to help prevent financial and physical problems caused by hacking damage.

• Journal of The Korean Society of Clinical Toxicology
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• v.21 no.2
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• pp.69-80
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• 2023

Purpose: Suicide ranks among the top causes of death among youth in South Korea. This study aimed to identify the characteristics of suicidal individuals treated at emergency departments between 2011 and 2020. Methods: A retrospective analysis was conducted using data from January 2011 to December 2020 in the Injury Surveillance Cohort, a prospective registry. Patients' sex, age, mortality, methods of self-harm, and previous suicide attempts were analyzed. The methods of self-harm were categorized into falls, asphyxiation, blunt injuries, penetrating injuries, poisoning, and others. Sub-groups with and without poisoning were compared. Results: The proportion of self-harm/suicide attempts increased from 2.3% (2011) to 5.0% (2020). The mortality rate decreased from 10.8% (2011) to 6.3% (2020). Poisoning was the most common method (61.7%). Mortality rates ranged from 42.0% for asphyxiation to 0.2% for blunt injuries. Individuals in their 20s showed a marked increase in suicide/self-harm attempts, especially in the last three years. A large proportion of decedents in their 70s or older (52.6%) used poisoning as a method of suicide. The percentage of individuals with two or more previous attempts rose from 7.1% (2011) to 19.7% (2020). The death rates by poisoning decreased from 7.7% (2011) to 2.5% (2020). Conclusion: Our findings underscore the urgent need for targeted interventions and suicide prevention policies. Managing and reducing suicide and self-harm in emergency settings will require a focus on poisoning, the 10-29 age group, and the elderly. This paper will be valuable for future policies aiming to reduce the societal burden of suicide and self-harm.

• The Journal of Engineering Geology
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• v.34 no.2
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• pp.217-228
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• 2024

During deep drilling, confined aquifers can present various challenges such as the inability to remove cuttings, rapid groundwater influx, and mud loss. Particularly in flowing well conditions, it is essential to apply the suitable mud density since the aquifer can generates an overpressurized condition. This paper proposes a method for determining the suitable mud density while drilling (SMD) through confined aquifers using mud window analysis and applies it to a case study. The minimum mud density at each depth, which represents the lower limit of the mud window, is determined by the equivalent mud density pore pressure gradient (or by adding a trip margin) at that depth. The pore pressure gradient of a confined aquifer can be calculated using the piezometric level or well head pressure of the aquifer. As the borehole reaches the confined aquifer, there is a significant increase in pore pressure gradient, which gradually decreases with increasing depth. The SMD to prevent a kick can be determined as the maximum value among the minimum mud densities in the open hole section. After entering the confined aquifer, SMD is maintained as the minimum mud density at the top of the aquifer during the drilling of the open hole section. Additionally, appropriate casing installation can reduce the SMD, minimizing the risk of mud loss or invasion into the highly permeable aquifer.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.6
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• pp.196-207
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• 2023

As part of measures to address the climate crisis, buses are also being converted to electric and hydrogen buses. Local authorities need to prioritize carbon emissions when allocating newly introduced and converted electric and hydrogen buses, and as a method, consider the introduction of Low Emission Bus Zones (LEBZ) to propose the reduction of pollution from specific links. To introduce LEBZ, it is necessary to compare the carbon emissions before and after its implementation, yet there is a shortage of studies that focus solely on buses or analyze the effects of introducing LEBZ to specific links. In this paper, we utilized bus information system data to calculate and compare the effects of introducing LEBZ to bus priority lanes in Jeju. We categorized scenarios into five groups, with scenarios 1 through 4 involving the introduction of LEBZ, and scenario 5 designating cases where LEBZ was not introduced. Comparative results confirmed that in scenarios with LEBZ introduction, the reduction per km reached a maximum of 0.097t per km, whereas in cases without LEBZ, it amounted to 0.022t per km, demonstrating higher efficiency. It underscores the significance of conducting carbon emission calculations and comparing the effects of LEBZ introduction using bus information system data, which can be directly applied by local authorities to make informed and rational decisions.

• Journal of Ecology and Environment
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• v.47 no.4
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• pp.228-240
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• 2023

Growing complexity in ecosystem structure and functions, under impacts of climate and land-use changes, requires interdisciplinary understandings of processes and the whole-system, and accurate estimates of the changing functions. In the last three decades, observation networks for biodiversity, ecosystems, and ecosystem functions under climate change, have been developed by interested scientists, research institutions and universities. In this paper we will review (1) the development and on-going activities of those observation networks, (2) some outcomes from forest carbon cycle studies at our super-site "Takayama site" in Japan, and (3) a few ideas how we connect in-situ and satellite observations as well as fill observation gaps in the Asia-Oceania region. There have been many intensive research and networking efforts to promote investigations for ecosystem change and functions (e.g., Long-Term Ecological Research Network), measurements of greenhouse gas, heat, and water fluxes (flux network), and biodiversity from genetic to ecosystem level (Biodiversity Observation Network). Combining those in-situ field research data with modeling analysis and satellite remote sensing allows the research communities to up-scale spatially from local to global, and temporally from the past to future. These observation networks oftern use different methodologies and target different scientific disciplines. However growing needs for comprehensive observations to understand the response of biodiversity and ecosystem functions to climate and societal changes at local, national, regional, and global scales are providing opportunities and expectations to network these networks. Among the challenges to produce and share integrated knowledge on climate, ecosystem functions and biodiversity, filling scale-gaps in space and time among the phenomena is crucial. To showcase such efforts, interdisciplinary research at 'Takayama super-site' was reviewed by focusing on studies on forest carbon cycle and phenology. A key approach to respond to multidisciplinary questions is to integrate in-situ field research, ecosystem modeling, and satellite remote sensing by developing cross-scale methodologies at long-term observation field sites called "super-sites". The research approach at 'Takayama site' in Japan showcases this response to the needs of multidisciplinary questions and further development of terrestrial ecosystem research to address environmental change issues from local to national, regional and global scales.

• Journal of the Economic Geographical Society of Korea
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• v.26 no.4
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• pp.359-374
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• 2023

The main purpose of this paper is to explore the relationship between the transformation of Chinese regional development policy and trends in spatial inequality in mainland China. More specifically, it has attempted to identify the effects of Chinese regional development policies on regional economic inequality by investigating the coefficient of variation and Gini coefficient with GRDP in the province level. Regional inequality in China had increased from 1979 economic reform, but has eased since the 10th Five Year Plan(2001~2005) due to large-scale state investments in the western, central and northeastern regions. However, the analysis is likely to be resulted from the national level. Trends in regional inequality are differentiated in accordance with the eastern, central, northeastern and western regions. For example, regional inequality in the central region has increased, whereas other three regions has decreased since the 10th Five Year Plan. It has played a role in cutting down regional inequality in the national level. In particular, the central region has kept inequality since the 12th Five Year Guideline. It has led to the convergence of the regional economies in the national level. It has stemmed from some limits to greater regional policies in the Central region enforced in the 11th Five Year Guideline(2005~2010).

• Journal of IKEEE
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• v.28 no.1
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• pp.110-115
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• 2024

This paper analyzed the V_th (Threshold Voltage) variations in 3D NAND Flash memory with tapered O/N/O (Oxide/Nitride/Oxide) structure and O/N/F (Oxide/Nitride/Ferroelectric) structure, where the blocking oxide is replaced by ferroelectric material. With a tapering angle of 0°, the O/N/F structure exhibits lower resistance compared to the O/N/O structure, resulting in reduced V_th variations in both the upper and lower regions of the WL (Word Line). Tapered 3D NAND Flash memory shows a decrease in channel area and an increase in channel resistance as it moves from the upper to the lower WL. Consequently, as the tapering angle increases, the V_th decreases in the upper WL and increases in the lower WL. The tapered O/N/F structure, influenced by V_fe proportional to the channel radius, leads to a greater reduction in V_th in the upper WL compared to the O/N/O structure. Additionally, the lower WL in the O/N/F structure experiences a greater increase in V_th compared to the O/N/O structure, resulting in larger V_th variations with increasing tapering angles.

• Analyses & Alternatives
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• v.8 no.1
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• pp.87-109
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• 2024

At the 8th Party Congress in 2021, North Korea announced a plan to build 50,000 housing units in Pyongyang, and this paper analyzes the economic effects and related informal costs of of the project. Currently, Pyongyang is experiencing a significant housing shortage. It is estimated that the number of households in Pyongyang increased by 184,000 between 1994 and 2020, while the estimated new housing supply during the period was only 30,000. Pyongyang's 50,000 housing units construction project is characterized by the goal of improving the living conditions of workers, the application of the new city construction method, and the largest state-led housing construction since the Arduous March. The project is expected to generate economic effects such as increasing workers' motivation to work, increasing tourism resources, and generating income from related industries. On the one hand, a significant portion of the construction cost of the 50,000-unit housing project in Pyongyang is passed on to companies and households in the form of informal cost such as quasi-taxes and manpower mobilization. In addition, there may be congestion in the power supply and sewerage facilities that occur when moving in. If these costs are not taken into account, the feasibility of a housing construction project may not be properly assessed, making it difficult to sustain it in the long term.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.78-88
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• 2024

Ship-radiated noise received by passive sonar that can measure underwater noise can be identified and classified ship using Detection of Envelope Modulation on Noise (DEMON) analysis. However, in a low Signal-to-Noise Ratio (SNR) environment, it is difficult to analyze and identify the target frequency line containing ship information in the DEMONgram. In this paper, we conducted a study to extract target frequency lines using semantic segmentation among deep learning techniques for more accurate target identification in a low SNR environment. The semantic segmentation models U-Net, UNet++, and DeepLabv3+ were trained and evaluated using simulated DEMONgram data generated by changing SNR and fundamental frequency, and the DEMONgram prediction performance of DeepShip, a dataset of ship-radiated noise recordings on the strait of Georgia in Canada, was compared using the trained models. As a result of evaluating the trained model with the simulated DEMONgram, it was confirmed that U-Net had the highest performance and that it was possible to extract the target frequency line of the DEMONgram made by DeepShip to some extent.