• Knowledge Management Research
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• v.25 no.3
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• pp.47-71
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• 2024

AI-driven news recommendation systems are widely used today, providing personalized news consumption experiences. However, there are significant concerns that these systems might increase users' information bias by mainly showing information from limited perspectives. This lack of diverse information access can prevent users from forming well-rounded viewpoints on specific issues, leading to social problems like Filter bubbles or Echo chambers. These issues can deepen social divides and information inequality. This study aims to explore how AI-based news recommendation services affect users' perceived information bias and to create a foundation for ethical principles in AI services. Specifically, the study looks at the impact of ethical principles like accountability, the right to explanation, the right to choose, and privacy protection on users' perceptions of information bias in AI news systems. The findings emphasize the need for AI service providers to strengthen ethical standards to improve service quality and build user trust for long-term use. By identifying which ethical principles should be prioritized in the design and implementation of AI services, this study aims to help develop corporate ethical frameworks, internal policies, and national AI ethics guidelines.

• Investigative Magnetic Resonance Imaging
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• v.5 no.2
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• pp.123-129
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• 2001

Purpose: The purposes of this study are to evaluate normal MR spectroscopy (MRS) data of the cerebellum and pons, and to evaluate intra-unit and inter-unit differences of the results. Materials and methods: Nine normal volunteers (mean age 23 years) were studied with two 1.5 Tesla MR units (A and B units). A total of four sessions of MRS study were performed with two sessions in ea.ch MR unit in each volunteer. In each session, MRS data were obtained from bilateral cerebellar hemisphere and pons. MRS was performed using spin-echo single voxel technique with repetition time of 2000 ms, echo time of 288ms and 128 averagings. Voxel size was $2{\;}{\times}{\;}2{\;}{\times}{\;}1.5{\;}cm$ in the cerebellum and $1.5{\;}{\times}{\;}1.5{\;}{\times}{\;}1.5{\;}cm$ in the pons. Metabolite ratios of NAA/Cho, NAAcCr, NAAc(Cho+Cr) and Cr/Cho (both peak heights and the peak areas) were compared among the results of four sessions of MRS for evaluation of intra-unit and inter-unit differences. Results: In the cerebellum, mean (SO values of peak height NAA/Cho, NAA/Cr, NAA/(Cho+Cr) and Cr/Cho ratios obtained in the first session of A unit were $1.08{\pm}O.16,{\;}1.44{\pm}O.286,{\;}0.61{\pm}O.09{\;}and{\;}O.76{\pm}0.13$, respectively. Comparing with the results of the second session, intra-unit differences were 3-7%. In B unit intra-unit differences were 1-9%, except for 22% of Cr/Cho ratio. Inter-unit differences between A and B units were 1-26%. In the pons, mean ISD values of peak height NANCho, NANCr, NANICho + Cr) and Cr/Cho ratios obtained in the first session of A unit were $1.51{\pm}O.35,{\;}3.35{\pm}O.78,{\;}1.02{\pm}0.16{\;}and{\;}0.47{\pm}O.14$, respectively. Mean NAAfCho, NANCr and NAAI(Cho+ Cr} ratios of the pons were significantly higher than those of the cerebellum. Intra-unit differences were 2-21 % in A unit and 4-18 % in B unit. Inter-unit differences between A and B units were 1-18%. The mean values obtained by using peak area were generally higher and wider in range than those of peak height in both units. Conclusion: Mean NAAfCho, NAAlCr and NAAf(Cho+Cr) ratios of the cerebellum were significanHy lower than those of the pons. Intra-unit differences of most metabolites ratios were generally not significant, whereas inter-unit differences were greater than intra-unit differences in more metabolite ratios. Therefore, normal MRS data of the cerebellum and the pons should be obtained in every MR unit, before MRS applications in the diseases of the cerebellum and the pons.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.103-109
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• 2016

Polyethylene pipes has useful benefits which are anti-corrosive and flexible material, so it is used to gas pipes but also class 3 water pipes of nuclear power plant, process pipes of petrochemical plant and chemical plant. So the usage of polyethylene pipes is widely increased. But it has been limited for the usage of polyethylene, because it can not be directly detected to fusion joints by using non destructive evaluation. Polyethylene pipes are connected by two methods, one is butt fusion and the other is electrofusion. Butt fusion is widely used to connecting the pipes. It is proposed to method for determining the reliability of joints in this study that is detection of the melt flow zone at fusion joints. In this study, middle density polyethylene is used, outside diameter of the test specimen is 225mm and thickness is 20.5mm. Speed of ultrasonic of this test specimen is 2,200m/s. Test specimens were fabricated by varying the heating time which means from 0% to 130% applying time through heating plate to polyethylene for detecting melt flow zone. Also 4 additional test specimens were made, one was made that not scrapping attached surface of pipes but applying 100% of the proper heating time and the others were made to include of soil, gravel and vinly tape paper at fusion joints, that were also applied 100% of proper heating time. Ultrasonic testing to measure the melt flow zone of 20 test specimens was conducted by using 3.5MHz and 5.0MHz ultrasonic probes and melt flow zone measuring was conducted to three times at different point to one specimen. To differentiate the melt flow zone signal, post image processing was equally conducted to all test results and image levels, contrast, sharpen, threshold were adopted to all teat results and the test results were displayed gray scale. From the results, for the shorter heating times the reflection area of multiple echo have been increased, so the data was obtained from the position where it can be eliminated as much as possible. At 80% of proper heating time(168 sec.), the signal of melt flow zone was obtained clearly, so measuring could be conducted. From 7% of proper heating time(15 sec.) to shorter heating times. we could not obtain the signal because test specimen was not fused. From the result, we can verify that measuring of melt flow zone by using phased array ultrasonic imaging method is possible. And we can verify to complete and incomplete butt fusion by measuring the melt flow zone.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.621-628
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• 1997

Background : As the pleural inflammation progresses, exudative pleural fluid becomes loculated rapidly with pleural thickening. Complete drainage is important to prevent pleural fibrosis, entrapment and depression of lung function. Intrapleural urokinase instillation therapy has been advocated as a method to facilitate drainage of gelatinous pleural fluid and to allow enzymatic debriment of pleural surface. This study was designed to investigate the predictors of effectiveness of intrapleural urokinase in the treatment of loculated pleural effusion. Method : Thirty-five patients received a single radiographically guided pig-tail catheter ranging in size from 10 to 12 French. Twenty-two patients had tuberculous pleural effusions, and 13 had non-tuberculous postpneumonic empyemas. A total of 240,000 units of urokinase was dissolved in 240 ml of normal saline and the aliquots of 80mL was instilled into the pleural cavity via pig-tail catheter per every 8hr. Effectiveness of intrapleural urokinase instillation therapy was assessed by biochemical markers, ultrasonography, and technical details. A greater than 50% improvement on follow-up chest radiographs was defined as success group. Result : Twenty-seven of 35 (77.1%) patients had successful outcome to urokinase instillation therapy. Duration of symptoms before admission was shorter in success group ($11.8{\pm}6.9day$) than in failure group ($26.62{\pm}16.5day$) (P<0.05). Amount of drained fluid during urokinase therapy was larger in success group ($917.1{\pm}392.7ml$) than in failure group ($613.8{\pm}259.7ml$) (P<0.05). Pleural fluid glucose was higher in success group ($89.7{\pm}35.9mg/dl$) than in failure group ($41.2{\pm}47.1mg/dl$) (P<0.05). Pleural fluid LDH was lower in success group ($878.4{\pm}654.3IU/L$) than in failure group ($2711.1{\pm}973.1IU/L$) (P<0.05). Honeycomb septated pattern on chest ultrasonography was observed in six of eight failure group, but none of success group (P<0.05). Conclusion : Longer duration of symptoms before admission, smaller amount of drained fluid during urokinase therapy, lower glucose value, higher LDH value in pleural fluid examination, and honeycomb septation pattern on chest ultrasonograph were predictors for failure group of intrapleural urokinase instillation therapy.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.335-344
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• 2023

Brachydiplax chalybea flavovittata, a climate-sensitive biological indicator species, was first observed and recorded at Jeju Island in Korea in 2010. Overwintering was recently confirmed in the Yeongsan River area. This study was aimed to predict the potential distribution patterns for the larvae of B. chalybea flavovittata and to understand its ecological characteristics as well as changes of population under global climate change circumstances. Data was collected both from the Global Biodiversity Information Facility (GBIF) and by field surveys from May 2019 to May 2023. We used for the distribution model among downloaded 19 variables from the WorldClim database. MaxEnt model was adopted for the prediction of potential and future distribution for B. chalybea flavovittata. Larval distribution ranged within a region delimited by northern latitude from Jeju-si, Jeju Special Self-Governing Province (33.318096°) to Yeoju-si, Gyeonggi-do (37.366734°) and eastern longitude from Jindo-gun, Jeollanam-do (126.054925°) to Yangsan-si, Gyeongsangnam-do (129.016472°). M type (permanent rivers, streams and creeks) wetlands were the most common habitat based on the Ramsar's wetland classification system, followed by Tp type (permanent freshwater marshes and pools) (45.8%) and F type (estuarine waters) (4.2%). MaxEnt model presented that potential distribution with high inhabiting probability included Ulsan and Daegu Metropolitan City in addition to the currently discovered habitats. Applying to the future scenarios by Intergovernmental Panel on Climate Change (IPCC), it was predicted that the possible distribution area would expand in the 2050s and 2090s, covering the southern and western coastal regions, the southern Daegu metropolitan area and the eastern coastal regions in the near future. This study suggests that B. chalybea flavovittata can be used as an effective indicator species for climate changes with a monitoring of their distribution ranges. Our findings will also help to provide basic information on the conservation and management of co-existing native species.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.32-41
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• 2004

Purpose : To measure the NMR relaxation properties of MnPC, to observe the characteristics of liver enhancement patterns on MR images in experimentally implanted rabbit VX2 tumor model, and to estimate the possibility of tissue specific contrast agent for MnPC in comparison with the hepatobiliary agent. Materials and Methods : Phthalocyanine (PC) was chelated with paramagnetic ions, manganese (Mn). 2.01 g (5.2 mmol) of phthalocyanine was mixed with 0.37 g (1.4 nlmol) of Mn chloride at $310^{\circ}C$ for 36 hours and then purified by chromatography ($CHCl_3:\;CH_3OH=98:2$, volume ratio) to obtain 1.04 g $(46\%)$ of MnPC (molecular weight = 2000 daltons). The T1/T2 relaxivity (R1/R2) for MnPC were determined at a 1.5 T (64 MHz) MR spectrometer. VX2 tumor model was experimentally implanted in the liver parenchyma of rabbits. All MR studies were performed on 1.5 T. The human extremity radio frequency coil of a bird cage type was employed. MR images were acquired at 17 to 24 days after VX2 carcinoma implantation.4 mmol/kg MnPC and 0.01 mmol/kg Mn-DPDP were injected via the ear vein of rabbits. T1-weighted images were obtained with spin-echo (TR/TE=516/14 msec) and fast multiplanar spoiled gradient recalled (TR/TE : 80/4 msec, $60^{\circ}$ flip angle) pulse sequence. Fast spin-echo (TR/TE=1200/85 msec) was used to obtain the T2-weighted images. Results : The value of T1/T2 relaxivity (R1/R2) of MnPC was $7.28\;mM^{-1}S^{-1}$ and $55.56\;mM^{-1}S^{-1}$ respectively at 1.5 T (64 MHz). Because the T2 relaxivity of MnPC that bonded strongly, covalently manganese with phthalocyanine was very high, the signal intensity of liver parenchyma was decreased on postcontrast T2-weighted images and we could easily distinguish the VX2 carcinoma within the liver parenchyma. When MnPC was administrated intravenously, the tumor margin delineation was more remarkable than Mn-DPDP-enhanced images. The enhancement of liver parenchyma with MnPC persisted at relatively high levels over at least one hour after injection of the contrast agents. Conclusion : The hepatic uptake and biliary excretion of MnPC, which are similar to Mn-DPDP, suggest that this agent is a new liver-specific agent. Also, MnPC seems to be used as a dual contrast agent (T1 and T2) with high T2 relaxivity. However, it is warranted that MnPC needs further investigation as a potential contrast agent for MR imaging of the liver. That is, further characterizations of MnPC are needed in vivo and in vitro before clinical trials. The diagnostic potential of MnPC will also have to be examined more in the animal models of additional types.

• Clinical and Experimental Pediatrics
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• v.48 no.10
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• pp.1139-1142
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• 2005

Purpose : The aim of this study was to investigate the epidemiologic and clinical profiles of Kawasaki disease(KD) in children 8 years of age and older. Methods : For the epidemiologic study of KD in Korea, data of total 15,692 KD patients were collected from 1994 to 2002 on a 3 year basis, by the retrospective survey. Among them, data of 211 KD patients 8 years of age and older were analyzed and compared with those of the KD patients less than 8 years of age. Results : 211 patients 8 years of age and older(1.3% of total KD patients) with the mean age of 9.8 years, included 142 cases aged 8-10 years, 42 cases aged 10-12 years, and 27 cases aged 12 years and older. The male-to-female ratio was 1.9 : 1, the recurrence rate was 3.8%, and the prevalence of cases in sibling was zero. Coronary arterial(CA) abnormalities were detected by echocardiography in 25.4% of the cases, including 7.6% of CA aneurysm cases. There was 1 case complicated by myocardial infarction. Conclusion : Comparing with the data of the KD patients less than 8 years of age, data of 211 patients 8 years of age and older showed significantly higher incidences of CA abnormalities(25.4% : 19.8%) and CA aneurysms(7.6% : 4.0%).

• Clinical and Experimental Pediatrics
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• v.51 no.12
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• pp.1320-1323
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• 2008

Purpose : The aim of this study was to investigate the epidemiologic status of Kawasaki disease (KD) in infants ${\leq}6months$ of age. Methods : For the epidemiologic study of KD in Korea, data from 22,674 KD patients were collected from 1997 to 2005 on a 3-year basis by a retrospective survey. From this survey, data of 1,739 KD patients ${\leq}6months$ of age were analyzed and compared with those of KD patients >6 months of age. Results : A total of 1,739 patients ${\leq}6months$ of age, including 1,088 males and 651 females, represented 7.7% of total KD patients. These subjects included 22 patients aged <1 month, 171 patients aged 1-2 months, 304 patients aged 2-3 months, 407 patients aged 3-4 months, 372 patients aged 4-5 months, and 463 patients aged 5-6 months. Their mean age of onset was 4.3 months, and the male-to-female ratio was 1.67:1. Incidences of coronary arterial (CA) abnormalities (21.0% versus 18.7%) and CA aneurysms (4.7% versus 3.1%) detected by echocardiography showed differences between patients with KD younger and older than 6 months, respectively. Conclusion : Comparison of data from KD patients >6 months old with data from 1,739 KD patients ${\leq}6months$ old showed significantly higher incidences of CA abnormalities and CA aneurysms in the younger patients.

• Journal of radiological science and technology
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• v.32 no.3
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• pp.313-323
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• 2009

Diffusion-weighted imaging (DWI) has been demonstrated to be a practical method for the diagnosis of various brain diseases such as acute infarction, brain tumor, and white matter disease. In this study, we used two techniques to examine the average signal intensity (SI) and apparent diffusion coefficient (ADC) of the brains of patients who ranged in age from 10 to 60 years. Our results indicated that the average SI was the highest in amygdala (as derived from DWI), whereas that in the cerebrospinal fluid was the lowest. The average ADC was the highest in the cerebrospinal fluid, whereas the lowest measurement was derived from the pons. The average SI and ADC were higher in $T_2^*$-DW-EPI than in FLAIR-DW-EPI. The higher the b-value, the smaller the average difference in both imaging techniques; the lower the b-value, the greater the average difference. Also, comparative analysis of the brains of patients who had experienced cerebral infarction showed no distinct lesion in the general MR image over time. However, there was a high SI in apparent weighted images. Analysis of other brain diseases (e.g., bleeding, acute, subacute, chronic infarction) indicated SI variance in accordance with characteristics of the two techniques. The higher the SI, the lower the ADC. Taken together, the value of SI and ADC in accordance with frequently occurring areas and various brain disease varies based on the b-value and imaging technique. Because they provide additional useful information in the diagnosis and treatment of patients with various brain diseases through signal recognition, the proper imaging technique and b-value are important for the detection and interpretation of subacute stroke and other brain diseases.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.9 no.1
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• pp.39-47
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• 2006

Purpose: We proposed a new classification of pediatric intussusception based on clinical and radiologic findings. Methods: Data from 88 consecutive patients with intussusception were reviewed. We retrospectively analyzed six factors; patient age, sites of intussusception, symptoms, therapeutic methods, existence of enlarged mesenteric lymph nodes, and ultrasonographic (US) findings from clinical records. Results: 1) There was one neonatal case (1.1%), the others (98.9%) were infants and children. 2) These 87 infant and child cases consisted of 14 cases (16.1%) of small bowel intussusception (SBI) and 73 cases (83.9%) of ileo-colic intussusception (ICI). Of the 14 SBI cases, 12 cases were symptomatic and 2 cases were asymptomatic. The symptomatic group comprised 8 transient cases (66.7%), 3 operative cases (25.0%), and 1 enema-reduction case (8.3%). Two asymptomatic cases were incidentally captured by computed tomography. Of the 73 ICI cases, 19 cases (26.0%) required operation, and 54 (74.0%) enema-reduction. 3) When transient SBI cases were compared with operated SBI cases, enema-reduced and operated ICI cases, the age ($38.0{\pm}22.9$ months) of transient SBI cases were significantly higher than those of the others (p=0.003). Mean mass size ($20.8{\pm}2.7mm$) in transient SBI was significantly smaller than in the others (p=0.0001). 4) No correlation was found between the existence of enlarged mesenteric lymph nodes and therapeutic method or concomitant illness. 5) Most of the target types observed by US were in transient SBI cases, the remainder were in the enema-reduced ICI cases. In terms of the doughnuts type, all 8 cases (34.8%) with an external hypoechoic rim thickness of >8.9mm were treated surgically. Conclusion: Pediatric intussusception may be classified based on clinical and radiologic findings, which are likely to indicate appropriate therapies.