• Journal of Intelligence and Information Systems
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• v.22 no.2
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• pp.81-96
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• 2016

As the internet has become widespread and easy to access everywhere, it is common for people to search information via online search engines such as Google and Naver in everyday life. Recent studies have used online search volume of specific keyword as a measure of the internet users' attention in order to predict disease outbreaks such as flu and cancer, an unemployment rate, and an index of a nation's economic condition, and etc. For stock traders, web search is also one of major information resources to obtain data about individual stock items. Therefore, search volume of a stock item can reflect the amount of investors' attention on it. The investor attention has been regarded as a crucial factor influencing on stock price but it has been measured by indirect proxies such as market capitalization, trading volume, advertising expense, and etc. It has been theoretically and empirically proved that an increase of investors' attention on a stock item brings temporary increase of the stock price and the price recovers in the long run. Recent development of internet environment enables to measure the investor attention directly by the internet search volume of individual stock item, which has been used to show the attention-induced price pressure. Previous studies focus mainly on Dow Jones and NASDAQ market in the United States. In this paper, we investigate the relationship between the individual investors' attention measured by the internet search volumes and stock price changes of individual stock items in the KOSDAQ market in Korea, where the proportion of the trades by individual investors are about 90% of the total. In addition, we examine the difference between industries in the influence of investors' attention on stock return. The internet search volume of stocks were gathered from "Naver Trend" service weekly between January 2007 and June 2015. The regression model with the error term with AR(1) covariance structure is used to analyze the data since the weekly prices in a stock item are systematically correlated. The market capitalization, trading volume, the increment of trading volume, and the month in which each trade occurs are included in the model as control variables. The fitted model shows that an abnormal increase of search volume of a stock item has a positive influence on the stock return and the amount of the influence varies among the industry. The stock items in IT software, construction, and distribution industries have shown to be more influenced by the abnormally large internet search volume than the average across the industries. On the other hand, the stock items in IT hardware, manufacturing, entertainment, finance, and communication industries are less influenced by the abnormal search volume than the average. In order to verify price pressure caused by investors' attention in KOSDAQ, the stock return of the current week is modelled using the abnormal search volume observed one to four weeks ahead. On average, the abnormally large increment of the search volume increased the stock return of the current week and one week later, and it decreased the stock return in two and three weeks later. There is no significant relationship with the stock return after 4 weeks. This relationship differs among the industries. An abnormal search volume brings particularly severe price reversal on the stocks in the IT software industry, which are often to be targets of irrational investments by individual investors. An abnormal search volume caused less severe price reversal on the stocks in the manufacturing and IT hardware industries than on average across the industries. The price reversal was not observed in the communication, finance, entertainment, and transportation industries, which are known to be influenced largely by macro-economic factors such as oil price and currency exchange rate. The result of this study can be utilized to construct an intelligent trading system based on the big data gathered from web search engines, social network services, and internet communities. Particularly, the difference of price reversal effect between industries may provide useful information to make a portfolio and build an investment strategy.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.9
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• pp.1159-1165
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• 2006

Our preliminary study showed that genistein and daidzein improved blood glucose level in type 2 diabetic mice by enhancing the glucose and lipid metabolism. The objective of this study was to evaluate whether genistein and daidzein are associated with alterations in antioxidant defense mechanism of type 2 diabetic mice. Male C57BL/KsJ-db/db (db/db) mice and age-matched non-diabetic littermates (db/+) were used in this study. The db/db mice were divided into control, genistein (0.02%, w/w) and daidzein (0.02%, w/w) groups. The relative weights of liver, epididymal adipose tissue and perirenal adipose tissue were significantly higher in the db/db group than in the db/+ group, whereas heart weight was lower. The genistein and daidzein supplement did not affect the organ weights in db/db mice. The blood glucose level was positively correlated with superoxide dismutase (SOD, r=0.380, p<0.05) and catalase (CAT, r=0.345, p<0.05) activities and negatively correlated with glutathione peroxidase (GSH Px, r= 0.404, p<0.05) activity in erythrocyte. Therefore, the erythrocyte SOD and CAT activities were significantly elevated in the db/db group compared to the db/+ group and the GSH-Px activity was lowered. However, the supplementation of genistein and daidzein reversed erythrocyte CAT and GSH-Px activities in type 2 diabetic mice. In this current study, the SOD activities in liver, kidney and heart were significantly not different between the groups. The CAT and GSH-Px activities in liver and GSH-Px activity in kidney were significantly higher in the db/db group than in the db/+ group, while the CAT activity in kidney, CAT and GSH-Px activities in heart were lowered. The supplementation of genistein and daidzein significantly attenuated the changes of CAT and/or GSH-Px activities in liver and heart. The supplementation of genistein and daidzein elevated GSH levels in kidney and heart compared to the db/db control group. The lipid peroxide levels in liver, kidney and heart were significantly lowered in the genistein and daidzein supplemented groups compared to the db/db control group. These results suggest that genistein and daidzein might be beneficial for the prevention of type 2 diabetic complication via suppressing changes of antioxidant enzymes activities with simultaneous reduction of lipid peroxidation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.7
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• pp.841-846
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• 2006

This study was conducted to investigate the influence of laminaran from Eisenia bicyclis on serum lipid composition of rats fed high fat and cholesterol diets. Fourty male Sprague-Dawley rats weighing $70{\pm}2.5g$ of 4 weeks old were fed experimental diets for 6 weeks with high fat diet consisting of basal diet plus cholesterol (1%) and lard (10%) for the inducement of hyperlipidemia. The effect of laminaran supplements via drinking waters on serum lipid composition of rat were investigated for 5 weeks by administration of experimental diet group fed basal diet only as normal group, control group fed high fat diet, LL group fed high fat diet plus 0.25% laminaran containing water, and LH group fed high fat diet plus 0.5% laminaran containing water, respectively. As a results of experiments, it was found that LL and LH groups showed significant (p<0.05) decrease in body weight gain and liver weight as compared with control and it may caused by decreased FER. The weight of cecum and adipose tissue (EFP) of LL group showed a significantly (p<0.05) decreased patterns compared with control. It was also found that LL and LH diet groups affects the intestinal length and transit time of rat as significantly (p<0.05) increased in length of intestine and decreased in transit time. In addition, LL and LH diet groups showed a dramatic decrease in triglyceride, total and LDL-cholesterol, and significant increase in HDL-cholesterol compared with control diet group, by which results in decreased in AI. These results indicate that crude laminaran from Eisenia bicyclis has a strong hyperlipidemic and hypercholesterolemic activities in rat fed high fat and cholesterol diet.

• Journal of dental hygiene science
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• v.16 no.2
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• pp.142-149
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• 2016

The number of male dental hygienists has been continuously increasing in dental services. The purpose of this study aimed to identify the relationship between job stress, job satisfaction, and turnover intention in male dental hygienists and to provide basic data to improve their job satisfaction. The study population was 110 Korean male dental hygienists working for dental clinics or hospitals. The data were collected from November 10 to December 7, 2015. After an explanation about the objective of the study, 110 questionnaires were distributed via email, and 97 responses were analyzed using SPSS. Overall averages of job stress, job satisfaction and turnover intention in male dental hygienists were 3.05, 2.92, and 3.47 out of 5, respectively. Some sub-factors of job stress, including interpersonal relationships at the workplace and future prospects of dental clinics, were proven to have statistically significant negative influence on job satisfaction (p<0.001). Regression analysis was performed with job stress and job satisfaction as independent variables and turnover intention as a dependent variable. Results showed that job stress had a positive effect on turnover intention (p<0.01) while job satisfaction had a negative effect on turnover intention (p<0.001). Job satisfaction was revealed to have statistically significant negative influence on turnover intention (p<0.001). Some of sub-factors of job stress, including work environment and future prospects of dental clinics and professional position, had a positive effect on turnover intention (p<0.05). The study showed that higher job stress led to higher turnover intention, and higher job satisfaction led to lower turnover intention. Accordingly, job stress and job satisfaction are critical factors for turnover intention in male dental hygienists.

• Journal of The Korean Ophthalmological Society
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• v.59 no.12
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• pp.1114-1121
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• 2018

Purpose: We report the clinical outcomes of patients undergoing additional widening of the limbal incision to prevent disease recurrence after conjunctivo-limbal autograft combined with pterygial excision. Methods: We retrospectively compared 95 eyes with primary and 12 eyes with recurrent pterygia randomized to treatment via two surgical methods: conjunctivo-limbal autograft alone and combined with widening of the limbal incision to allow for pterygial removal. We widened the limbal incisions by 1 mm on both the superior and inferior limbal margins and removed the pterygia. The outcomes were compared between 39 eyes undergoing conjunctivo-limbal autograft alone and 68 eyes undergoing conjunctivo-limbal autograft with widening of the limbal incision. Results: The mean overall postoperative follow-up period was $29.6{\pm}10.5months$ and conjunctivo-limbal autograft alone group was $27.4{\pm}11.5months$, combined with widening of the limbal incision group was $30.7{\pm}9.7months$. Six pterygia (15.4%; four primary and two recurrent) developed in those undergoing conjunctivo-limbal autograft alone and two (2.9%; one primary and one recurrent) in those undergoing additional widening of the limbal incision; the recurrence rate differed significantly between the two groups (p < 0.05). In the group treated with conjunctivo-limbal autograft alone, the mean time to development of a new primary pterygium was $6.3{\pm}3.4months$ and that to development of a recurrent pterygium $4.3{\pm}2.5months$; the respective values for the group undergoing additional widening of the limbal incision were $12.1{\pm}2.6$ and $8.4{\pm}4.6months$; the recurrence rates differed significantly (p < 0.05). Conclusions: Conjunctivo-limbal autograft with additional widening of the limbal incision used to treat both new primary and recurrent pterygia was more effective in terms of reducing pterygial recurrence than conjunctivo-limbal aAutograft alone.

• Journal of The Korean Ophthalmological Society
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• v.59 no.11
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• pp.1017-1023
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• 2018

Purpose: A recently introduced phacoemulsification system, the WhiteStar $Signature^{(R)}$ PRO, has demonstrated improved nucleus followability and cutting efficiency via an improved pump regulator with a higher reaction response and an automatic occlusion sensing system. In this study, we compared various phacoemulsification parameters between the new system and an older version of the device. Methods: A total of 80 eyes of 68 patients with cataracts who had undergone phacoemulsification by a single surgeon were included in this study. Forty eyes of patients underwent phacoemulsification using the older $Signature^{(R)}$ system (WhiteStar); these patients were classified as the control group. Another 40 eyes of patients underwent phacoemulsification with the newer enhanced system, the WhiteStar $Signature^{(R)}$ PRO; these patients were assigned to the experimental group. During the operation, operative parameters, including the effective phaco time (parameter of effective phaco time with a specific coefficient for the transversal movement expressed in seconds, EFX), ultrasound time (seconds [s]), effective phacoemulsification time (EPT, s), average phacoemulsification power (AVG, %), and balanced salt solution usage, were measured to determine the performance enhancement offered by the updated system. Central corneal thickness was measured before and after surgery to compare corneal edema. The relationships between the two groups were analyzed using an independent t-test. Results: The Signature $PRO^{(R)}$ system showed a lower EFX (p < 0.001), a shorter EPT (p < 0.001), and a smaller AVG (p < 0.001). Postoperative corneal thickness did not differ significantly between the two groups. Conclusions: Comparing the efficacy of the improved reaction speed of the device and automatic occlusion sensing system in performing phacoemulsification, the updated Signature $PRO^{(R)}$ system demonstrated superior followability and cutting efficiency regardless of nuclear cataract hardness.

• Ultrasonography
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• v.32 no.1
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• pp.59-65
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• 2013

Purpose: The purpose of this study is to establish the methodology regarding synthesis of ultrasound contrast agent imaging, and to evaluate the characteristics of the synthesized ultrasound contrast agents, including size or degradation interval and image quality. Materials and Methods: The ultrasound contrast agent, composed of liposome and SF6, was synthesized from the mixture solution of $21{\mu}mol$ DPPC (1, 2-Dihexadecanoyl-sn-glycero-3-phosphocholine, $C_{40}H_{80}NO_8P$), $9{\mu}mol$ cholesterol, $1.9{\mu}mol$ of DCP (Dihexadecylphosphate, $[CH_3(CH_2)_{15}O]_2P(O)OH$), and chloroform. After evaporation in a warm water bath and drying during a period of 12-24 hours, the contrast agent was synthesized by the sonication process by addition of buffer and SF6 gas. The size of the contrast agent was controlled by use of either extruder or sonication methods. After synthesis of contrast agents, analysis of the size distribution of the bubbles was performed using dynamic light scattering measurement methods. The degradation curve was also evaluated by changes in the number of contrast agents via light microscopy immediate, 12 hours, 24 hours, 36 hours, 48 hours, 60 hours, 72 hours, and 84 hours after synthesis. For evaluation of the role as an US contrast agent, the echogenicity of the synthesized microbubble was compared with commercially available microbubbles (SonoVue, Bracco, Milan, Italy) using a clinical ultrasound machine and phantom. Results: The contrast agents were synthesized successfully using an evaporation-drying-sonication method. The majority of bubbles showed a mean size of 154.2 nanometers, and they showed marked degradation 24 hours after synthesis. ANOVA test revealed a significant difference among SonoVue, synthesized contrast agent, and saline (p < 0.001). Although no significant difference was observed between SonoVue and the synthesized contrast agent, difference in echogenicity was observed between synthesized contrast agent and saline (p < 0.01). Conclusion: We could synthesize ultrasound contrast agents using an evaporation-drying-sonication method. On the basis of these results, many prospective types of research, such as anticancer drug delivery, gene delivery, including siRNA or microRNA, targeted molecular imaging, and targeted therapy can be performed.

• Journal of The Korean Ophthalmological Society
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• v.58 no.6
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• pp.706-711
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• 2017

Purpose: To analyze blinking patterns when watching an ultra-high definition (UHD) television and to compare the results between normal eyes and dry eyes. Methods: A total of 59 participants aged from 13 to 69 years were instructed to watch a colorful and dynamic video on a UHD television for 10 minutes. Before and after watching the UHD television, we measured the best corrected visual acuities, autorefraction, tear-break-up-time, degree of corneal erosion and conjunctival hyperemia via slit lamp biomicroscopy. In addition, questionnaires for the evaluation of eye fatigue and symptoms of a dry eye were completed. The definition of dry eye syndrome was that the tear-break-up-time of one of the eyes was less than 5 seconds, conjunctival injection, or marked corneal erosion. The number of blinks and the duration of blinking were both measured and analyzed at the early and late phases of video-watching. Results: After watching the UHD television in the normal eye group, the tear-break-up-time was significantly decreased (p < 0.001) and the degree of corneal erosion was significantly increased (p = 0.023). However, the subjective symptoms of participants were not aggravated (p = 0.080). There were no significant differences in blinking patterns in the dry eye group. On the other hand, in the normal eye group, the mean blinking time was significantly increased (p = 0.030). Conclusions: Watching an UHD television changes the tear-break-up-time, degree of corneal erosion, and blinking pattern in normal eyes, which may increase the risk of dry eye syndrome.

• Journal of The Korean Ophthalmological Society
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• v.58 no.3
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• pp.321-326
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• 2017

Purpose To identify the correspondence between the central sensitivity of several visual field (VF) tests and ganglion cell inner plexiform layer (GC-IPL) thickness in early glaucoma patients with parafoveal scotoma. Methods Fifty-seven eyes from 57 patients with glaucomatous optic neuropathy and parafoveal scotoma were analyzed using the standard automated perimetry (SAP) C10-2 test, the SAP C24-2 test, and the frequency doubling technology perimetry (FDT) C24-2 test. The correlation between the VF central sensitivity and the GC-IPL thickness from macular scans via optical coherence tomography was analyzed. Results The central sensitivity was $27.51{\pm}5.43dB$, $27.39{\pm}5.05dB$, and $22.09{\pm}5.08dB$ for SAP C24-2, SAP C10-2, and FDT C24-2, respectively. Mean GC-IPL thickness was $70.2{\pm}8.5{\mu}m$. Using regression analysis, the value of log $R^2$ between the logarithmic central sensitivity and GC-IPL thickness was 0.498, and the linear $R^2$ between the antilogarithmic central sensitivity and GC-IPL thickness in SAP C10-2 was 0.486, and both were statistically significant (p < 0.05). This relationship was stronger in early glaucoma patients compared to late glaucoma patients using SAP C10-2. Conclusions The structure-function relationship between GC-IPL thickness and central sensitivity was better with SAP C10-2, especially in early glaucoma patients, compared to other VF modalities.

• Korean Journal of Remote Sensing
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• v.21 no.6
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• pp.445-456
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• 2005

The land surface parameters should be determined with sufficient accuracy, because these play an important role in climate change near the ground. As the surface reflectance presents strong anisotropy, off-nadir viewing results a strong dependency of observations on the Sun - target - sensor geometry. They contribute to the random noise which is produced by surface angular effects. The principal objective of the study is to provide a database of accurate surface reflectance eliminated the angular effects from MODIS 250m reflective channel data over Korea. The MODIS (Moderate Resolution Imaging Spectroradiometer) sensor has provided visible and near infrared channel reflectance at 250m resolution on a daily basis. The successive analytic processing steps were firstly performed on a per-pixel basis to remove cloudy pixels. And for the geometric distortion, the correction process were performed by the nearest neighbor resampling using 2nd-order polynomial obtained from the geolocation information of MODIS Data set. In order to correct the surface anisotropy effects, this paper attempted the semiempirical kernel-driven Bi- directional Reflectance Distribution Function(BRDF) model. The algorithm yields an inversion of the kernel-driven model to the angular components, such as viewing zenith angle, solar zenith angle, viewing azimuth angle, solar azimuth angle from reflectance observed by satellite. First we consider sets of the model observations comprised with a 31-day period to perform the BRDF model. In the next step, Nadir view reflectance normalization is carried out through the modification of the angular components, separated by BRDF model for each spectral band and each pixel. Modeled reflectance values show a good agreement with measured reflectance values and their RMSE(Root Mean Square Error) was totally about 0.01(maximum=0.03). Finally, we provide a normalized surface reflectance database consisted of 36 images for 2001 over Korea.