• The Journal of Asian Finance, Economics and Business
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• v.8 no.10
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• pp.219-228
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• 2021

The study examines the behavior of stock prices after large price changes. It further examines the effect of firm size on stock returns, and the presence of the disposition effect. The study employs the event study methodology using daily price data from Pakistan Stock Exchange (PSX) for the period January 2001 to July 2012. Furthermore, to examine the factors that explain stock price behavior after large price movements, the study employs a two-way fixed-effect model that allows for the analysis of unobservable company and time fixed effects that explain market reversals or continuation. The findings suggest that winners perform better than losers after experiencing large price shocks thus showing a momentum behavior. In addition, the winners remain the winner, while the losers continue to lose more. This suggests that most of the investors in PSX behave rationally. Further, the study finds no evidence of disposition effect in PSX. The investors underreact to new information and the prices continue to move in the direction of initial change. The pooled regression estimates show that firm size is positively related to post-event abnormal returns while the fixed-effect model reveals the presence of unobservable firm-specific and time-specific effects that account for price continuation.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.1
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• pp.1-8
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• 2021

Low level wind shear, which often occurs at Jeju International Airport, is a phenomenon that occurs when the topological location and topographical characteristics of Jeju Island are combined with weather characteristics. Low level wind shears, which are caused by rapid changes in wind direction and wind speed, pose a threat to aircraft safety and also cause abnormal situations, such as aircraft go-around, diversion, and cancellation. Many meteorological studies have been conducted on weather patterns, occurrence periods and frequency of low level wind shears. However, researches related to aircraft operations are limited where here we study the similarities and differences between strong southwest winds and bidirectional tailwind type low level wind shears based on aircraft go-around cases at Jeju International Airport. The results are expected to be used to enhance safety when operating to Jeju International Airport, which includes pilot training that reflects the characteristics generated by wind changes, pilot prior notification, providing pilots with latest trends, and increasing extra fuel.

• Journal of Distribution Science
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• v.21 no.3
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• pp.93-100
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• 2023

Purpose: The purpose of this paper is to confirm whether stocks belonging to the distribution industry in Korea have reversals, following large daily stock price changes accompanied by large trading volumes. Research design, data, and methodology: We examined whether there were reversals after the event date when large-scale stock price changes appeared for the entire sample of distribution-related companies listed on the Korea Composite Stock Price Index from January 2004 to July 2022. In addition, we reviewed whether the reversals differed depending on abnormal trading volume on the event date. Using multiple regression analysis, we tested whether high trading volume had a significant effect on the cumulative rate of return after the event date. Results: Reversals were confirmed after the stock price shock in the Korean distribution industry and the return after the event date varied depending on the size of the trading volume on the event day. In addition, even after considering both company-specific and event-specific factors, the trading volume on the event day was found to have significant explanatory power on the cumulative rate of return after the event date. Conclusions: Reversals identified in this paper can be used as a useful tool for establishing a trading strategy.

• The Journal of Korean Physical Therapy
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• v.34 no.6
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• pp.321-325
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• 2022

Purpose: Temporomandibular disorder (TMD) is a condition defined as pain and dysfunction of temporomandibular joints and masticatory muscles. Abnormal interconnections between temporomandibular muscles and cervical spine structures can cause the changes of postural alignment and balance ability. The aim of this study was to investigate changes in static balance ability in subjects with painrelated TMD. Methods: This study conducted on 25 subjects with TMD and 25 control subjects with no TMD. Pressure pain thresholds (PPTs) of the masseter and temporalis muscles were measured using a pressure algometer. Static balance ability was assessed during one leg standing using an Inertial Measurement Unit (IMU) sensor. During balance task, the IMU sensors measured motion and transfer movement data for center of mass (COM) motion, ankle sway and hip sway. Results: PPTs of masseter and temporalis muscles were significantly lower in the TMD group than in the control group (p<0.05). One leg standing, hip sway, and COM sway results were significantly greater in the TMD group (p<0.05), but ankle sways were not different between group. Conclusion: We suggest pain-related TMD is positively related to reduced PPTs of masticatory muscles and to static balance ability. These results should be considered together with global body posture when evaluating or treating pain-related TMD.

• Journal of Information Processing Systems
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• v.19 no.2
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• pp.149-163
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• 2023

Affected by external factors, errors in time series data collected by sensors are common. Using the traditional method of constraining the speed change rate to clean the errors can get good performance. However, they are only limited to the data of stable changing speed because of fixed constraint rules. Actually, data with uneven changing speed is common in practice. To solve this problem, an online cleaning algorithm for time series data based on dynamic speed change rate constraints is proposed in this paper. Since time series data usually changes periodically, we use the extreme learning machine to learn the law of speed changes from past data and predict the speed ranges that change over time to detect the data. In order to realize online data repair, a dual-window mechanism is proposed to transform the global optimal into the local optimal, and the traditional minimum change principle and median theorem are applied in the selection of the repair strategy. Aiming at the problem that the repair method based on the minimum change principle cannot correct consecutive abnormal points, through quantitative analysis, it is believed that the repair strategy should be the boundary of the repair candidate set. The experimental results obtained on the dataset show that the method proposed in this paper can get a better repair effect.

• Smart Media Journal
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• v.11 no.2
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• pp.53-62
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• 2022

Due to the accelerated global warming phenomenon after industrialization, the frequency of changes in the existing environment and abnormal climate is increasing. Agriculture is an industry that is very sensitive to climate change, and global warming causes problems such as reducing crop yields and changing growing regions. In addition, environmental changes make the growth period of crops irregular, making it difficult for even experienced farmers to easily estimate the growth stage of crops, thereby causing various problems. Therefore, in this paper, we propose a CNN model for estimating the growth stage of crops. The proposed model was a model that modified the pooling layer of ResNet, and confirmed the accuracy of higher performance than the growth stage estimation of the ResNet and DenseNet models.

• Journal of Yeungnam Medical Science
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• v.40 no.4
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• pp.328-334
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• 2023

An aging population and changes in dietary habits have increased the incidence of diabetes, resulting in complications such as diabetic foot ulcers (DFUs). DFUs can lead to serious disabilities, substantial reductions in patient quality of life, and high financial costs for society. By understanding the etiology and pathophysiology of DFUs, their occurrence can be prevented and managed more effectively. The pathophysiology of DFUs involves metabolic dysfunction, diabetic immunopathy, diabetic neuropathy, and angiopathy. The processes by which hyperglycemia causes peripheral nerve damage are related to adenosine triphosphate deficiency, the polyol pathway, oxidative stress, protein kinase C activity, and proinflammatory processes. In the context of hyperglycemia, the suppression of endothelial nitric oxide production leads to microcirculation atherosclerosis, heightened inflammation, and abnormal intimal growth. Diabetic neuropathy involves sensory, motor, and autonomic neuropathies. The interaction between these neuropathies forms a callus that leads to subcutaneous hemorrhage and skin ulcers. Hyperglycemia causes peripheral vascular changes that result in endothelial cell dysfunction and decreased vasodilator secretion, leading to ischemia. The interplay among these four preceding pathophysiological factors fosters the development and progression of infections in individuals with diabetes. Charcot neuroarthropathy is a chronic and progressive degenerative arthropathy characterized by heightened blood flow, increased calcium dissolution, and repeated minor trauma to insensate joints. Directly and comprehensively addressing the pathogenesis of DFUs could pave the way for the development of innovative treatment approaches with the potential to avoid the most serious complications, including major amputations.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.17-23
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• 2004

Purpose : To evaluate changes in total cerebral blood flow (tCBF) with aging, parenchymal volume changes and vascular abnormalities, using 2 dimensional (D) phase-contrast magnetic resonance imaging (PC MRI). Materials and Methods : Routine brain MRI including T2 weighted image, time-of-flight (TOF) MR Angiography (MRA) and 2D PC MRI were performed in 73 individuals, including 12 volunteers. Normal subjects (12 volunteers, and 21 individuals with normal MRI and normal MRA) were classified into groups according to age (18-29, 30-49 and 50-66 years). For the group with abnormalities in brain MRIs, cerebral parenchymal volume changes were scored according to the T2 weighted images, and atherosclerotic changes were scored according to the MRA findings. Abnormal groups were classified into 4 groups: (i) mild reduction in volume, (ii) marked reduction in volume by parenchymal volume and atherosclerotic changes, and (iii) increased volume and (iv) Moya-moya disease. Volumetric flow was measured at the internal carotid artery (ICA) and vertebral artery bilaterally using the velocity-flow diagrams from PC MRI, and combined 4 vessel flows and tCBF were compared among all the groups. Results : The age-specific distribution of tCBFs in normal subjects were as follows: $12.0{\pm}2.1ml/sec$ in 18-29 years group, $11.8{\pm}1.9ml/sec$ in 30-49 years group, $10.9{\pm}2.2ml/sec$ in 50-66 years group. The distribution of tCBFs in the different subsets of the abnormal population were as follows: $9.5{\pm}2.5ml/sec$ in the group with mild reduction in volume, $7.6{\pm}2.0ml/sec$ in the group with marked reduction in volume, and $7.3{\pm}1.2ml/sec$ and $7.0{\pm}1.1ml/sec$ in the increased parenchymal volume and Moya-moya disease groups respectively. Conclusion : Total cerebral blood flow decreases with increasing age with a concomitant reduction in parenchymal volumes and increasing atherosclerotic changes. It is also reduced in the presence of increased parenchymal volume and Moya-moya disease.2D PC MRI can be used as a tool to evaluate tCBF with aging and in the presence of various conditions that can affect parenchymal volume and cerebral vasculature.

• The Journal of Korean Medicine
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• v.20 no.3 s.39
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• pp.45-53
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• 1999

Since Radix Stemonae was recorded hypothennal and a little toxic in the 'Myngyubelrok (名醫別錄)', it has been recorded as having the same nature in many herbal books. However, the security of Radix Stemonae when used to treat respiratory disease over a long term has not been studied until now. Therefore, the objective of this study is to determine the effects of Radix Stemonae on the main organs if Radix Stemonae is administrated over a long term. In order to investigate the histological changes of the liver and kidneys of rats after oral administration of Radix Stemonae extract, the experimental rats were subdivided into control, 1, 3, 5, 7, 21, 28 and 35 days after administration groups, and 10 rats per group were used in this study. The control group was sufficiently supplied with water and solid forage. The other groups were administrated the reagent at 5mg/kg once a day by oral injection. Several times each day, the experimental groups were carefully observed for any changes of general condition, toxic symptoms, activity, appearance and the number of dead rats. The experimental groups were weighed and narcotized. For the histological observation, the tissues of liver and kidneys of the experimental groups were collected, stained by hematoxylin-eosin stain, and evaluated by observing the changes of gross appearance and by observing microscopic findings. 1. This drug, during the experimental term, did not induce any toxicological effect in mortality, abnormal symptoms or changes of body weight except for the 1 day after administration groups whose body weights were decreased, compared to the control group. 2. No gross changes of the liver and kidneys were observed in this study. 3. No histological changes of the liver were detected in 1 day after administration groups. However, dilation of the central vein was observed in 3, 5 and 7 days after administration groups and chronic passive congestion of the liver was demonstrated in the 21 days after administration groups. In the 28 and 35 days after administration groups, a centrolobular disposition of fatty tissue (adipose cell) was observed. 4. No histological changes of the kidneys were observed in this study. It is evaluated that if Radix Stemonae is administrated for a long term, it induces toxicity in the liver. So, to examine the toxicity of Radix Stemonae on the liver and kidney, it is necessary that the studies of biochemistry and electron microscopic findings about Radix Stemonae be systematically performed.

• Journal of Oral Medicine and Pain
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• v.3 no.1
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• pp.3-10
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• 1977

Few changes were found in the mouths of 52 smokers were examined as a part of program to evaluate the oral health of Korean smokers. 52 smokers and 30 non-smokers were performed careful oral examination. In many of smokers, heavy, black deposits are found on the buccal and lingual surfaces of the teeth and leukoplakia were obsreved in 2 subjects and varied merely in the severity of the involvement. Cytologic studies were carried out on 60 oral smears from the hard palate, buccal mucosa, and gingiva. Smears were taken wit a wood spatula scraped over the mucosal surface. After fixation the slides were stained using the papanicolau cells without nuclei. The cornified cells were smaller than the noncornified cells and stained a deep brown or orange as compared with the blue or red of the large, round or polygonal cells in nonkeratinized regions of oral mucosa. Abnormal cell forms, suggestive of malignancy were not found in smears from the mucosa of smokers. Cells with large hyperchromatic nuclei and elongated, spindle-type cells with large nuclei were not observed.