• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.132-133
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• 2023

The safe evacuation of people during disasters is of utmost importance. Various life safety evacuation simulation tools have been developed and implemented, with most relying on algorithms that analyze maps to extract the shortest path and guide agents along predetermined routes. While effective in predicting evacuation routes in stable disaster conditions and short timeframes, this approach falls short in dynamic situations where disaster scenarios constantly change. Existing algorithms struggle to respond to such scenarios, prompting the need for a more adaptive evacuation route algorithm that can respond to changing disasters. Artificial intelligence technology based on reinforcement learning holds the potential to develop such an algorithm. As a fundamental step in algorithm development, this study aims to evaluate whether an evacuation algorithm developed by reinforcement learning satisfies the performance conditions of the evacuation simulation tool required by IMO MSC.1/Circ1533.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.5
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• pp.1-11
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• 2023

Due to climate change and aging of reservoirs, damage to embankment slopes is increasing. However, the safety diagnosis of the reservoir slope is mainly conducted by visual observation, and the time and economic cost are formidable to apply soil mechanical tests and slope stability analysis. Accordingly, this study presented a predicting method for the compaction and strength characteristics of the reservoir embankment soil using a portable static cone penetration test. The predicted items consisted of dry density, cohesion, and internal friction angle, which are the main factors of slope stability analysis. Portable static cone penetration tests were performed at 19 reservoir sites, and prediction equations were constructed from the correlation between penetration resistance data and test results of soil samples. The predicted dry density and strength parameters showed a correlation with test results between R² 0.40 and 0.93, and it was found to replace the test results well when used as input data for slope stability analysis (R² 0.8134 or more, RMSE 0.0320 or less). In addition, the prediction equations for the minimum safety factor of the slope were presented using the penetration resistance and gradient. As a result of comparing the predicted safety factor with the analysis results, R² 0.5125, RMSE 0.0382 in coarse-grained soil, R² 0.4182 and RMSE 0.0628 in fine-grained soil. The results of this study can be used as a way to improve the existing slope safety diagnosis method, and are expected to be used to predict the characteristics of various soils and inspect slopes.

• Journal of Korean Neurosurgical Society
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• v.67 no.2
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• pp.227-236
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• 2024

Objective : Numerous studies have indicated that early decompressive craniectomy (DC) for patients with major infarction can be life-saving and enhance neurological outcomes. However, most of these studies were conducted by neurologists before the advent of intra-arterial thrombectomy (IA-Tx). This study aims to determine whether neurological status significantly impacts the final clinical outcome of patients who underwent DC following IA-Tx in major infarction. Methods : This analysis included 67 patients with major anterior circulation major infarction who underwent DC after IA-Tx, with or without intravenous tissue plasminogen activator. We retrospectively reviewed the medical records, radiological findings, and compared the neurological outcomes based on the "surgical time window" and neurological status at the time of surgery. Results : For patients treated with DC following IA-Tx, a Glasgow coma scale (GCS) score of 7 was the lowest score correlated with a favorable outcome (p=0.013). Favorable outcomes were significantly associated with successful recanalization after IA-Tx (p=0.001) and perfusion/diffusion (P/D)-mismatch evident on magnetic resonance imaging performed immediately prior to IA-Tx (p=0.007). However, the surgical time window (within 36 hours, p=0.389; within 48 hours, p=0.283) did not correlate with neurological outcomes. Conclusion : To date, early DC surgery after major infarction is crucial for patient outcomes. However, this study suggests that the indication for DC following IA-Tx should include neurological status (GCS ≤7), as some patients treated with early DC without considering the neurological status may undergo unnecessary surgery. Recanalization of the occluded vessel and P/D-mismatch are important for long-term neurological outcomes.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.48-53
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• 2024

We predicted the calendar aging and long-term lifetime of lithium-ion batteries using an electrochemical-based SEI growth model. Numerical simulation was carried out employing the four different long-term SEI growth models (i.e., solvent diffusion limited model, electron migration limited model, Li-interstitial diffusion limited model, reaction limited model), and we calculated the capacity fade and loss of lithium inventory during calendar aging. The result showed that the electron migration limited model and Li-interstitial diffusion limited model showed lower capacity fade, while the solvent diffusion limited model and reaction limited model reached 80% of capacity fade within 10 years. During calendar aging, the lower storage temperature showed less capacity fade due to the hindrance of SEI growth rate. During cycling, the higher C-rate showed a shorter life cycle; however, the differences were not significant.

• Journal of Chest Surgery
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• v.57 no.3
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• pp.315-318
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• 2024

The HeartWare Ventricular Assist Device (HVAD) was widely used for mechanical circulatory support in patients with end-stage heart failure. However, there have been reports of a critical issue with HVAD pumps failing to restart, or experiencing delays in restarting, after being stopped. This case report describes 2 instances of HVAD failure-to-restart during heart transplantation surgery and routine outpatient care. Despite multiple attempts to restart the pump using various controllers and extensions, the HVAD failed to restart, triggering a hazard alarm for pump stoppage. In one case, the patient survived after receiving a heart transplantation, while in the other, the patient died immediately following the controller exchange. These cases highlight the rare but life-threatening complication of HVAD failure-to-restart, underscoring the importance of awareness among clinicians, patients, and caregivers, and adherence to the manufacturer's guidelines and recommendations for HVAD management.

• Analytical Science and Technology
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• v.37 no.4
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• pp.251-260
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• 2024

As polymers became very important in our lives, their negative impact on general health and the environment raised a serious issue. Here, enhancing their life term is presented as a compromise solution between the need and harm. In the study, six PVC films, the plain and five filled with improvers, underwent radiation exposure for 300 hours at room temperature to investigate their photodegradation rates. The modified films were embedded with organotin(IV) complex derivatives (Ph₃SnL, Ph₂SnL₂, Bu₃SnL, Bu₂SnL₂, and Me₂SnL₂ (where L is levofloxacin)), and their effectiveness was evaluated. The PVC films were compared before and after exposure to various tests including UV-Vis spectroscopy, gel content analysis, theoretical calculations, and EDX microscopy. Findings indicated that the presence of organotin(IV) complex derivatives, particularly Ph3SnL, notably decreased UV light absorbance and the amount of gel content in PVC sheets in comparison to untreated PVC. Furthermore, EDX analysis showed that the PVC-Ph₃SnL blend exposed to radiation exhibited the highest chlorine content, reaching 30 %. This blend demonstrated superior efficacy in stabilizing the polymeric materials.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.602-613
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• 2010

Background: As life expectancy has been increased, the cardiac valve disease has been increased. In past, mechanical valve for valve replacement surgery was used widely, but it has many weaknesses, such as hemorrhage, teratogenic effect caused by warfarin, acute mechanical failure, taking warfarin during life, etc. So, the tissue valve is used widely and researches for durability of tissue valve are in progress. Tissue valves being used are all imported in Korea, and there is a lack of information on its geometry and design. So, we studied the geometry of porcine aortic and pulmonary valve, and tried to suggest theoretical basis for making the aortic and pulmonary valve. Material and Method: We harvested aortic and pulmonary valves of 25 pigs and measured the geometry of valve at fresh and glutaraldehyde (GA) fixed state. In each group, we measured the diameter of the base, diameter of commissure, valve height, commissural height, etc. Also, for making implantable porcine and bovine pericardial valve, we designed the valve stent form, thickness, height, and leaflet size, form, thickness by different size of valve. Result: The aortic and pulmonary valve geometry and ratio were measured in each group. The right coronary cusp of aortic valve and right facing cusp of pulmonary valve was bigger than other cusps and non coronary cusp was smaller than others (RCC: NCC : LCC=1 : 0.88 : 1). Valve height was correlated to the leaflet size. We designed the outer diameter of stented porcine aortic valve from 19 mm to 33 mm and designed stent height and width, using previous measured ratio of each structure, stent thickness, working thickness (for making valve). Also, we designed the size of stent and form for stented bovine pericardial valve, considering diameter of valve, leaflet length, height and leaflet minimum coaptation area. Conclusion: By measuring of 25 pig's aortic and pulmonary valve geometry and ratio, we can make theoretical basis for making implantable stented porcine valve and bovine pericardial valve in various size. After making implantable valve using these data, it is necessary to do in vivo and in vitro researches, furthermore.

• Food Science and Preservation
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• v.9 no.3
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• pp.321-326
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• 2002

Paeksulkis(Korean rice cake) containing 0-0.5% chitosan were prepared for test the quality of microbiological, mechanical and sensory characteristics. The pH of Paeksulkis was 5.65 without chitosan and that was about 7.0 with 0.05-0.5% level of chitosan. In Hunter's color values of Paeksulkis of control, the lightness(L) was 84.28, redness(a) was -1.56 and yellowness(b) was 7.68. The lightness(L), redness(a) and yellowness(b) were increased with increasing concentration of chitosan in Paeksulkis. In mechanical characteristics of Paeksulkis, cohesiveness and springiness were the highest in control group while strength, hardness, gumminess and brittlenes were higher in chitosan added group than control group. In sensory evaluation of Pasksulkis, control group obtained the highest score in color, texture, after swallowing and overall quality(p<0.05) but chitosan added group obtained higher scores in moisture than control(p<0.05). Total bacterial counts(TBC) of Paeksulgis immediately before storage were 4.2∼9.2$\times$10$^2$CFU/g and those of control increased for 2 weeks, reached at 7.4$\times$10$\^$5/ CFU/g and then decreased about 1 log cycle for 2 weeks during storage at 5$\^{C}$. TBC of Paeksulgis added 0.3∼0.5% of chitosan were 2 log cycles lower than that of control at the end of storage at 5$\^{C}$. TBC of Pasksulgis control increased to 10$\^$8/ CFU/g during storage at 20$\^{C}$ but that of 0.5% chitosan added group was 1 log cycle lower than control at the end of storage. Shelf-life extension of Paeksulkis by chitosan was more effective during storage at 5$\^{C}$ than at 20$\^{C}$.

• Science of Emotion and Sensibility
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• v.21 no.3
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• pp.141-150
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• 2018

The purpose of this study is to investigate three-dimensional embroidery techniques for creating conductive fabric materials. Such techniques can increase the efficiency of energy harvesting by increasing the fabric's area during rubbing and brushing. We also investigate the fabric structure of the triboelectric energy harvesting type. Two experiments were conducted for this purpose. In Experiment I, the three-dimensional embroidery technique(satin technique, file technique) and the conductive fabric material(copper-based MPF, nickel-based MPF) were selected as the main variables affecting the efficiency of triboelectric energy harvesting from the human body. Four samples were fabricated according to a combination of two variables. In Experiment II, the harvesters fabricated by the three-dimensional embroidery method showing the highest efficiency were subjected to brushing processes and the voltages generated after processing were analyzed. As a result, in both conductive fabric materials, the pile embroidery fabric structure showed a higher efficiency than the satin structure. These results show the triboelectric energy harvesting principle, which is proportional to the charge density and the generated voltage. It can be seen that the structure of pile embroidery fabric with a large friction area is advantageous for increasing efficiency compared to satin embroidery-fabric structure with a relatively small friction area. Moreover, the energy harvesting efficiency after brushing was higher than that before processing due to the increased friction area, and it was found that the brushing method is advantageous for increasing the triboelectric-energy harvest.

• Journal of Bio-Environment Control
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• v.22 no.2
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• pp.100-107
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• 2013

Unlike general microwave, QRD (Quadratic Residue Diffusor) Microwave used in this study is known as a new technology that enhances the sterilization effect with low power because it is possible to induce the average sterilization by changing wavelength phase difference. Therefore, basic research was conducted on the function that could sterilize culture media for plant factory by using environmentally friendly and low energy consuming QRD Microwave. The results are as follows: It was confirmed that there was no external deformation in the polyurethane foam and rock wool medium when changing the microwave level between 2 and 8 kW in different water content of culture media. However, PDA solid media at 2 kW were not dissolved in 60 and 180 seconds. All of the media were dissolved in other processing. There was little difference in the microwave irradiation level and surface temperature of the strain according to the processing time between Bacillus sp. and Burkholderia sp. In the sterility test according to the microwave irradiation level and processing time, it was confirmed that both Bacillus sp. and Burkholderia sp. grew in the microwave level 2 kW regardless of time. In the microwave level 6 kW, all experimental groups except the processing of Burkholderia sp. for 60 seconds were sterilized, and all of Bacillus sp. was killed in the all experimental groups. In the microwave level 8 kW, it was confirmed that both Bacillus sp. and Burkholderia sp. were sterilized regardless of time. The temperature in microwave-processed media after contaminating strains to each medium was maintained at more than 100 in polyurethane foam and rock wool medium after 60 seconds. In general, it was shown that it was possible to sterilize after 60 seconds. Therefore, it is considered that Bacillus sp. and Burkholderia sp. which are the biggest problems in the plant factory can be adequately sterilized by QRD Microwave used in this study.