• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.1
• /
• pp.132-142
• /
• 2000

The objective of this study is to experimentally investigate the noise propagating characteristics, the noise reduction mechanism and the performance of a slotted tube attached at the exit plane of a circular convergent nozzle. The experiment is performed through the systematic change of the jet pressure ratio and the slot length under the condition of two kinds of open area ratios, 25% and 51%. The open area ratio calculated by the tube length equivalent for the slot length is defined as the ratio of the total slot area to the surface area of a slotted tube. The experimental results for the near and far field sound, the visualization of jet structures and the static pressure distributions in the jet passing through a slotted tube are presented and explained in comparison with those for a simple tube. The propagating characteristics of supersonic jet noises from the slotted tube is closely connected with the slot length rather than the open area ratio, and its propagating pattern is similar to the simple tube. It is shown that the slotted tube has a good performance to suppress the shock-associated noise as well as the turbulent mixing noise in the range of a limited jet pressure and slot dimension. The considerable suppression of the shock‘associated noise is mainly due to the pressure relief caused by the high-speed jets passing through the slots on the tube. Both the strength of shock waves and the interval between them in a jet plume are decreased by the pressure relief. Moreover, the pressure relief is divided into the gradual and the sudden relief depending upon the open area ratio of the slotted tube. Consequently, the shock waves in a jet plume are also changed by the type of pressure relief. The gradual pressure relief caused by the slotted tube with the open area ratio 25% generates the weak oblique shock waves. On the contrary, the weak normal shock waves appear due to the sudden pressure relief caused by the slotted tube with the open area ratio 51%.

• The KIPS Transactions:PartB
• /
• v.16B no.3
• /
• pp.233-238
• /
• 2009

This paper presents an approach to the classifications of small size document using the instance-based feature filtering Relief-F algorithm. In the document classifications, we have not always good classification performances of small size document included a few features. Because total number of feature in the document set is large, but feature count of each document is very small relatively, so the similarities between documents are very low when we use general assessment of similarity and classifiers. Specially, in the cases of the classification of web document in the directory service and the classification of the sectors that cannot connect with the original file after recovery hard-disk, we have not good classification performances. Thus, we propose the Extended Relief-F(ERelief-F) algorithm using instance-based feature filtering algorithm Relief-F to solve problems of Relief-F as preprocess of classification. For the performance comparison, we tested information gain, odds ratio and Relief-F for feature filtering and getting those feature values, and used kNN and SVM classifiers. In the experimental results, the Extended Relief-F(ERelief-F) algorithm, compared with the others, performed best for all of the datasets and reduced many irrelevant features from document sets.

• Journal of the Korean Geographical Society
• /
• v.45 no.4
• /
• pp.431-443
• /
• 2010

The morphometric characteristics of 13 alluvial fans in the southern parts of the Korean Peninsula are studied and relationships between their distributions and causes are discussed by comparing them with 690 alluvial fans in Japan, Taiwan and the Philippines. The relationships between the surface gradient of alluvial fans and source basin area, the surface gradient and the relief ratio of the source basin, and the source basin area and the relief ratio were investigated. The alluvial fans in South Korea have typical characteristics of the Asian fans, although their frequency and density are relatively low, and the size and the relief ratio of their source basins are relatively small and steep, respectively. Moreover 36 major Korean river basins without alluvial fans tend to have lower altitude and relief ratios. Contrary to the argument by Blair and McPherson, the natural depositional gaps on the gradient of alluvial fans were not found. The Gyeongju alluvial fan is probably a fluvial fan with gentle gradient, whereas the other Korean fans seem to be debris-flow related on the base of their gradients.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.2 no.4 s.7
• /
• pp.77-85
• /
• 2002

Korean government compensates 100% for natural disaster relief fund to public facilities, and provides 70 percents to crops through unit price calculation. This study estimated disaster damage according to the standard production cost of crops. Disaster damage was estimated according to the unit price of crops. Those crops are lettuce, pumpkin, red pepper, spinach, tomato and cucumber. As a result, the ratio of natural disaster relief fund to damage was revealed as $3.3%{\sim}13.8%$ with present method, 5.7%{$\sim}34.1%$ with suggested method. Suggested method is the first one considered damage ratio of crops, producer price and raising period.

• Korean Journal of Clinical Pharmacy
• /
• v.33 no.1
• /
• pp.43-50
• /
• 2023

Background and Objective: With the advancement of cancer treatments and increased life expectancy, managing breakthrough cancer pain (BTcP) is essential to improve the quality of life for cancer patients. This study aimed to compare the major rapid onset opioids in Korea based on their characteristics and costs to determine the best option for each patient. Methods: Based on sales information from IQVIA-MIDAS, sublingual fentanyl tablet (SLF), fentanyl buccal tablet (FBT), and oral transmucosal fentanyl citrate (OTFC) were selected as the top three drugs for the treatment of BTcP in Korea, considering them the most comparable drugs. The cost and cost-pain relief ratio of the drugs for short-term (1 month) and long-term (1 year) treatment were compared and the ease of administration based on various factors, including pharmacokinetics, onset of action, and administration procedures were evaluated. Results: SLF was evaluated as the best overall in terms of rapid onset of action, ease of administration, and drug cost and also had the highest market share. SLF had the lowest cost pain relief ratio for both the initial and supplemental treatment for the 1-month pain intensity difference 15 (PID15) ratio. However, for the 1-month PID30 ratio, SLF was not superior to OTFC or FBT. The longer the breakthrough cancer pain duration, the more cost-effective the other rapid onset opioids. Conclusion: The rapid onset opioids that fit the patient's breakthrough cancer pain pattern have the best cost-effectiveness.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1998.10a
• /
• pp.81-88
• /
• 1998

• Geomechanics and Engineering
• /
• v.37 no.2
• /
• pp.135-147
• /
• 2024

A GIS-based landslide susceptibility mapping (LSM) was carried out using frequency ratio (FR), modified frequency ratio (M-FR), analytic hierarchy process (AHP), and modified analytic hierarchy process (M-AHP) methods to identify and delineate the potential failure zones along the Halong - Vandon expressway. The thematic layers of various landslide causative factors were generated for modeling in GIS, including geology, rainfall, distance to fault, distance to road, slope, aspect, landuse, density of landslide, vertical relief, and horizontal relief. In addition, a landslide inventory along the road network was prepared using data provided by the management department during the course of construction and operation from 2017 to 2019, when many landslides were documented. The validation results showed that the M-FR method had the highest AUC value (AUC = 0.971), which was followed by the FR method with AUC = 0.961. The AUC values were 0.939 and 0.892 for the M-AHP and AHP methods, respectively. The generated LSM obtained from M-FR method classified the study area into five susceptibility classes: very low (0), low (0-1), moderate (1-2), high (2-3), and very high (3-4) classes, which could be useful for various stakeholders like planners, engineers, designers, and local public for future construction and maintenance in the study area.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.2
• /
• pp.237-247
• /
• 2018

The basin characteristics reflect the attributes of geomorphological pattern of basin and stream networks affect the rainfall-runoff. In order to analyze the relationship between the basin runoff and stream morphometric characteristics, the morphometric characteristics were investigated for 27 water-level observation stations on 19 rivers in the Han River basin using Arc-map. The morphometric characteristics were divided into linear, areal and relief aspects for calculation while the annual mean runoff ratio as a basin response by rainfall was estimated using the measured precipitation and discharge to analyze the rainfall-runoff characteristics. The correlation among the morphometric parameters were schematized to analyze the correlations among them. The multiple regression equation for rainfall-runoff ratio was provided with morphometric parameters of stream length ratio, form factor ratio, shape factor, stream area ratio, and relief ratio and the coefficient of determination was 0.691. The RMSE and MAPE between the measured and the estimated annual runoff rates were found as 0.09, 11.61% respectively, the suggested regression equation showed good estimation.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11b
• /
• pp.254-261
• /
• 2000

Soil chemical properties, relief of field surface, SPAD values and grain yield were investigated in a 0.5ha paddy field in 1999 to obtain basic field information for precision agriculture. Descriptive statistics of field information showed that the coefficient of variation ranged from 1.63% to 38.7%. Field information showed a high spatial dependence for within paddy field. The ranges of spatial dependence were from 15m to 60m, respectively. Kriged maps enable the visualization and comparison the spatial variability of field information. The causes of spatial variability of the field information could be explained rationally by a field management map. Grain yield was negatively correlated with pH, relief values, whereas, was positively correlated with total C, total N, C/N ratio, mineralizable N, available P and exchangeable K, Ca at the significant level of 1 %.

• Journal of The Korean Society of Integrative Medicine
• /
• v.7 no.4
• /
• pp.151-159
• /
• 2019

Purpose : This study aimed to evaluate the effects of sitting questionmark exercise (SQE) and brugger's relief exercise (BRE) on pain, ROM, proprioception, NDI in 60 Patients with Chronic Cervical Pain (CCP). Methods : In this study the VAS and NDI were used to investigate changes in pain and disability with SQE and BRE. The pre and post intervention intra group differences were analysed with a paired t-test for mean values, and the inter group differences were analyzed with an independent t-test for mean values. Results : The pain of both of groups was lowered with statistical significance. Pain of SQE group is lower than that of BRE group with statistical significance. ROM in both groups was improved, but there is no significant difference between two groups. NDI in both of groups were significantly decreased after the intervention, but there was no significant difference between groups. there was NDI ratio (%) significant difference between each groups. Conclusion : SQE intervention may be considered a more effective clinical approach for reducing pain and restoring proprioception in patients with CCP.