• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.5
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• pp.9-16
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• 2022

Syngas, also known as synthesis gas, synthetic gas, or producer gas, is a combustible gas mixture generated when organic material (biomass) is heated in a gasifier with a limited airflow at a high temperature and elevated pressure. The present research was aimed at modifying the existing LPG engine generator for fully operated syngas. During this study, the designed gasifier-powered woodchip biomass was used for syngas production to generate power. A 6.0 kW LPG engine generator was modified and tested for operation on syngas. In the experiments, syngas and LPG fuels were tested as test fuels. For syngas production, 3 kg of dry woodchips were fed and burnt into the designed downdraft gasifier. The gasifier was connected to a blower coupled with a slider to help the air supply and control the ignition. The convection cooling system was connected to the syngas flow pipe for cooling the hot produce gas and filtering the impurities. For engine modification, a customized T-shaped flexible air/fuel mixture control device was designed for adjusting the correct stoichiometric air-fuel ratio ranging between 1:1.1 and 1.3 to match the combustion needs of the engine. The composition of produced syngas was analyzed using a gas analyzer and its composition was; 13~15 %, 10.2~13 %, 4.1~4.5 %, and 11.9~14.6 % for CO, H₂, CH₄, and CO₂ respectively with a heating value range of 4.12~5.01 MJ/Nm³. The maximum peak power output generated from syngas and LPG was recorded using a clamp-on power meter and found to be 3,689 watts and 5,001 watts, respectively. The results found from the experiment show that the LPG engine generator operated on syngas can be adopted with a de-ration rate of 73.78 % compared to its regular operating fuel.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.153-163
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• 2023

This study is situated in the context of intelligent transport systems, where in-vehicle devices assist drivers to avoid accidents and therefore improve road safety. The vehicles present in a given area form an ad' hoc network of vehicles called vehicular ad' hoc network. In this type of network, the nodes are mobile vehicles and the messages exchanged are messages to warn about obstacles that may hinder the correct driving. Node mobilities make it impossible for inter-node communication to be end-to-end. Recognizing this characteristic has led to delay-tolerant vehicular networks. Embedded devices have small buffers (memory) to hold messages that a node needs to transmit when no other node is within its visibility range for transmission. The performance of a vehicular delay-tolerant network is closely tied to the successful management of the nodes' transit buffer. In this paper, we propose a message transit buffer management model for nodes in vehicular delay tolerant networks. This model consists in setting up, on the one hand, a policy of dropping messages from the buffer when the buffer is full and must receive a new message. This drop policy is based on the concept of intermediate node to destination, queues and priority class of service. It is also based on the properties of the message (size, weight, number of hops, number of replications, remaining time-to-live, etc.). On the other hand, the model defines the policy for selecting the message to be transmitted. The proposed model was evaluated with the ONE opportunistic network simulator based on a 4000m x 4000m area of downtown Bouaké in Côte d'Ivoire. The map data were imported using the Open Street Map tool. The results obtained show that our model improves the delivery ratio of security alert messages, reduces their delivery delay and network overload compared to the existing model. This improvement in communication within a network of vehicles can contribute to the improvement of road safety.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.3
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• pp.387-396
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• 2023

The representative equipments currently used for weather observations are meteorological masters and wind lidars. According to international regulations, meteorological masters can be used for standalone measurements, but in case of wind lidars, it is mandatory to install a meteorological master that matches the height of the bottom of the wind turbine blade or a 40m meteorological masters and correct the measurement data. Turbulence flow occurs frequently at altitudes below 100m due to its nature, and wind lidars are more susceptible to the effects of turbulence than meteorological masters. However, while the turbulence intensity for meteorological masters is specified by international regulations, there is no separated specification for wind lidars. This study collected data measured under the same conditions using both meteorological masters and wind LiDARs, analyzed the uncertainties and turbulence intensity ratio. The analysis of the data showed that there were partial sections where the proportion of turbulent flow intensity exceeded 3%. Therefore, it is suggested to include a specification for the turbulence intensity error rate for wind LiDARs in the international regulations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.9-16
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• 2024

In this paper, we aimed to convert the fire curve in volume units to a fire curve per unit area for application in the Fire Dynamic Simulator (FDS) surface heat release rate method. The fire curve was expressed dimensionlessly considering the total combustion characteristic time, and improvements were made to represent the appropriate ratios for the growth , steady, and decay phases concerning the fire intensity. Additionally, a correction function for combustion characteristic time varying with mass increase was derived. Also to control the growth time values according to the increase in mass, a function to correct the growth phase ratio was derived. Consequently, utilizing existing data, a formula was established to determine the reference mass for combustion materials and predict the fire curve based on mass increase.

• Journal of Cardiovascular Imaging
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• v.31 no.4
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• pp.159-168
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• 2023

BACKGROUND: The gold standard for diagnosis of cardiac tumours is histopathological examination. Cardiovascular magnetic resonance (CMR) is a valuable non-invasive, radiation-free tool for identifying and characterizing cardiac tumours. Our aim is to understand CMR diagnosis of cardiac tumours by distinguishing benign vs. malignant tumours compared to the gold standard. METHODS: A systematic search was performed in the PubMed, Web of Science, and Scopus databases up to December 2022, and the results were reviewed by 2 independent investigators. Studies reporting CMR diagnosis were included in a meta-analysis, and pooled measures were obtained. The risk of bias was assessed using the Quality Assessment Tools from the National Institutes of Health. RESULTS: A total of 2,321 results was obtained; 10 studies were eligible, including one identified by citation search. Eight studies were included in the meta-analysis, which presented a pooled sensitivity of 93% and specificity of 94%, a diagnostic odds ratio of 185, and an area under the curve of 0.98 for CMR diagnosis of benign vs. malignant tumours. Additionally, 4 studies evaluated whether CMR diagnosis of cardiac tumours matched specific histopathological subtypes, with 73.6% achieving the correct diagnosis. CONCLUSIONS: To the best of our knowledge, this is the first published systematic review on CMR diagnosis of cardiac tumours. Compared to histopathological results, the ability to discriminate benign from malignant tumours was good but not outstanding. However, significant heterogeneity may have had an impact on our findings.

• Clinical Endoscopy
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• v.55 no.3
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• pp.426-433
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• 2022

Background/Aims: Cholangiogram interpretation is not used as a key performance indicator (KPI) of endoscopic retrograde cholangiopancreatography (ERCP) training, and national societies recommend different minimum numbers per annum to maintain competence. This study aimed to determine the relationship between correct ERCP cholangiogram interpretation and experience. Methods: One hundred fifty ERCPists were surveyed to appropriately interpret ERCP cholangiographic findings. There were three groups of 50 participants each: "Trainees," "Consultants group 1" (performed >75 ERCPs per year), and "Consultants group 2" (performed >100 ERCPs per year). Results: Trainees was inferior to Consultants groups 1 and 2 in identifying all findings except choledocholithiasis outside the intrahepatic duct on the initial or completion/occlusion cholangiogram. Consultants group 1 was inferior to Consultants group 2 in identifying Strasberg type A bile leaks (odds ratio [OR], 0.86; 95% confidence interval [CI], 0.77-0.96), Strasberg type B (OR, 0.84; 95% CI, 0.74-0.95), and Bismuth type 2 hilar strictures (OR, 0.81; 95% CI, 0.69-0.95). Conclusions: This investigation supports the notion that cholangiogram interpretation improves with increased annual ERCP case volumes. Thus, a higher annual volume of procedures performed may improve the ability to correctly interpret particularly difficult findings. Cholangiogram interpretation, in addition to bile duct cannulation, could be considered as another KPI of ERCP training.

• Journal of Food Hygiene and Safety
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• v.25 no.1
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• pp.43-48
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• 2010

This research was conducted to know application of Photostimulated luminescence (PSL) and Thermoluminesce(TL) methods by irradiation dose for leaching tea, sauces and starch approved in Korea. Leaching tea, sauces and starch powder were treated with $^{60}Co$ gamma ray at dose 0~10 kGy for detection trial whether they are irradiated or not by measuring PSL and TL for whole samples. PSL values were less than threshold value 700 and were, negative for non-irradiated samples but more than 5,000 and were positive for irradiated ones. PSL results of leaching tea and sauces showed the correct identification for non-irradiated and irradiated samples, respectively except starch samples. To enhance the reliability of the TL result, the first glow curve (TL1) was compared with the second glove curve (TL2) obtained after a re-irradiation step at 1 kGy. The TL ratio ($TL_1/TL_2$) was in good agreement with the reported TL threshold for both the non-irradiated (< 0.1) and irradiated (> 0.1) samples. TL results of leaching tea, sauces, starch showed the correct identification for non-irradiated and irradiated samples, respectively. This study was performed to know application of PSL and TL methods for leaching tea, sauces and starch, and the methods were able to detect the irradiation products.

• 한국노년학
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• v.31 no.3
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• pp.505-526
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• 2011

The purposes of this paper were to examine the level of knowledge of and attitudes toward the elderly and investigate the differences in the level of knowledge of and attitudes about the elderly by selected socio-demographic factors and aging related factors in Korea and the United States. The research subjects were 1129 college students attending 10 schools in Korea and the United States(840 Korean students in 5 schools, located in Seoul City, Gyeonggi-Do, Chungcheong-Do in Korea and 289 American students in 5 schools located in the State of New York of the United States). They were interviewed, using the structured questionnaire, and the data were analyzed by SPSS 15.0 for Windows. The research questionnaire was composed of Fact on Aging Quiz Part 1(FAQ 1) developed by Palmore(1998), Semantic Differential Scale development by Sanders et al., and several socio-demographic and aging related variables. The results indicated that, first, the level of knowledge of the elderly for Korean students was 12.51/25 and for American students was 11.57/25, resulting that the knowledge level of the elderly in Korea was higher than that of the United States. In addition, the results of students' knowledge differences between korea and the United States showed that Korean students showed high ratio of correct answer in 9 questions while American students showed high ratio of correct answer in only 4 questions, resulting that Korean students have higher knowledge than American students. Second, the level of attitudes toward the elderly for Korean students was 77.54 and for American students was 70.07 in 20-140 points, resulting that the attitude level of the elderly among American students were more positive than that of Korean students. The results of students' attitudes differences between Korea and the United States showed that Korean students responded positive tendency in only one question while American students responded positive tendencies in 14 questions, resulting that American students were more positive attitudes toward the elderly than that of Korean students. Third, there is a significant correlation between the knowledge of and attitudes toward the elderly in both Korean and American students. Based on these results, implications for policy, practice, and research were further discussed.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.3
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• pp.30-39
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• 2012

In this paper, a safe driving assistance system is proposed by detecting the status of driver's doze based on face and eye detection. By the level of the fatigue, safe driving system alarms or set the seatbelt on vibration. To reduce the effect of backward light and too strong solar light which cause a decrease of face and eye detection rate and false fatigue detection, post processing techniques like image equalization are used. Haar transform and PCA are used for face detection. By using the statistic of the face and eye structural ratio of normal Koreans, we can reduce the eye candidate area in the face, which results in reduction of the computational load. We also propose a new eye status detection algorithm based on Hough transform and eye width-height ratio, which are used to detect eye's blinking status which decides doze level by measuring the blinking period. The system alarms and operates seatbelt on vibration through controller area network(CAN) when the driver's doze level is detected. In this paper, four algorithms are implemented and proposed algorithm is made based on the probability model and we achieves 84.88% of correct detection rate through indoor and in-car environment experiments. And also we achieves 69.81% of detection rate which is better result than that of other algorithms using IR camera.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.64-75
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• 2017

The role of a track subgrade is to provide bearing capacity and distribute load transferred to lower foundation soils. Track subgrade soils are usually compacted by heavy mechanical machines in the field, such that sometimes they are attributed to progressive residual settlement during the service after construction completion of the railway track. The progressive residual settlement generated in the upper part of a track subgrade is mostly non-recoverable plastic deformation, which causes unstable conditions such as track irregularity. Nonetheless, up to now no design code for allowable residual settlement of subgrade in a railway trackbed has been proposed based on mechanical testing, such as repetitive triaxial testing. At this time, to check the DOC or stiffness of the soil, field test criteria for compacted track subgrade are composed of data from RPBT and field compaction testing. However, the field test criteria do not provide critical design values obtained from mechanical test results that can offer correct information about allowable permanent deformation. In this study, a test procedure is proposed for permanent deformation of compacted subgrade soil that is used usually in railway trackbed in the laboratory using repetitive triaxial testing. To develop the test procedure, an FEA was performed to obtain the shear stress ratio (${\tau}/{\tau}_f$) and the confining stress (${\sigma}_3$) on the top of the subgrade. Comprehensive repetitive triaxial tests were performed using the proposed test procedure on several field subgrade soils obtained in construction sites of railway trackbeds. A permanent deformation model was proposed using the test results for the railway track.