• Childhood Kidney Diseases
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• v.1 no.2
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• pp.101-108
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• 1997

Purpose : The clinical characteristics of renovascular hypertension (RVHT) in children were analyzed. Methods : Medical records of 16 children diagnosed as RVHT on the basis of angiography during Jan. '86 to Jun. 94 in our hospital were reviewed retrospectively. Results : The mean age at the onset was 8.5 yrs and the sex ratio(M:F) was 7:9. The causes of RVHT were Takayasu arteritis in 6, Moyamoya disease in 5, and fibromuscular dysplasia in 3 patients. Abdominal bruit was noted in 6 patients (38%). Peripheral renin activity was raised in all tested patients. Bilateral renal arterial involvemnent was found in 9 patients (56%). Captopril renal scans showed good correlation with angiographic findings. Five patients were treated with antihypertensives only, and blood pressure was controlled completely in 2 and incompletely in 3. Percutaneous transluminal angioplasty was performed in 10 patients with 50% of success rate. However, hypertension was recurred due to restenosis or accompaning aortic stenosis in 3 patients. Surgical treatment was performed in 4 patients, and the blood pressure was controlled partially in 1 and poorly in the remaining 3. Conclusions : Takayasu arteritis, Moyamoya disease and fibromuscular dysplasia are the major causes of childhood RVHT in our country. The diagnosis of RVHT in children should be based on a set of tests individually selected for case by case. For the low curability of the current treatment modalities available, RVHT in children should not be regarded as 'curable' so far. We expect, however, that the outcome will be improved by more extensive application of the newly developed surgical technique.

• Asia pacific journal of information systems
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• v.21 no.4
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• pp.1-25
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• 2011

Internet-based commerce has undergone an explosive growth over the past decade as consumers today find it more economical as well as more convenient to shop online. Nevertheless, the shift in the common mode of shopping from offline to online commerce has caused consumers to have worries over such issues as private information leakage, online fraud, discrepancy in product quality and grade, unsuccessful delivery, and so forth, Numerous studies have been undertaken to examine the role of perceived risk as a chief barrier to online purchases and to understand the theoretical relationships among perceived risk, trust and purchase intentions, However, most studies focus on empirically investigating the effects of trust on perceived risk, with little attention devoted to the effects of perceived risk on trust, While the influence trust has on perceived risk is worth studying, the influence in the opposite direction is equally important, enabling insights into the potential of perceived risk as a prohibitor of trust, According to Pavlou (2003), the primary source of the perceived risk is either the technological uncertainty of the Internet environment or the behavioral uncertainty of the transaction partner. Due to such types of uncertainty, an increase in the worries over the perceived risk may negatively affect trust, For example, if a consumer who sends sensitive transaction data over Internet is concerned that his or her private information may leak out because of the lack of security, trust may decrease (Olivero and Lunt, 2004), By the same token, if the consumer feels that the online merchant has the potential to profit by behaving in an opportunistic manner taking advantage of the remote, impersonal nature of online commerce, then it is unlikely that the merchant will be trusted, That is, the more the probable danger is likely to occur, the less trust and the greater need to control the transaction (Olivero and Lunt, 2004), In summary, a review of the related studies indicates that while some researchers looked at the influence of overall perceived risk on trust level, not much attention has been given to the effects of different types of perceived risk, In this context the present research aims at addressing the need to study how trust is affected by different types of perceived risk, We classified perceived risk into six different types based on the literature, and empirically analyzed the impact of each type of perceived risk upon consumer trust in an online merchant and further its impact upon purchase intentions. To meet our research objectives, we developed a conceptual model depicting the nomological structure of the relationships among our research variables, and also formulated a total of seven hypotheses. The model and hypotheses were tested using an empirical analysis based on a questionnaire survey of 206 college students. The reliability was evaluated via Cronbach's alphas, the minimum of which was found to be 0.73, and therefore the questionnaire items are all deemed reliable. In addition, the results of confirmatory factor analysis (CFA) designed to check the validity of the measurement model indicate that the convergent, discriminate, and nomological validities of the model are all acceptable. The structural equation modeling analysis to test the hypotheses yielded the following results. Of the first six hypotheses (H1-1 through H1-6) designed to examine the relationships between each risk type and trust, three hypotheses including H1-1 (performance risk ${\rightarrow}$ trust), H1-2 (psychological risk ${\rightarrow}$ trust) and H1-5 (online payment risk ${\rightarrow}$ trust) were supported with path coefficients of -0.30, -0.27 and -0.16 respectively. Finally, H2 (trust ${\rightarrow}$ purchase intentions) was supported with relatively high path coefficients of 0.73. Results of the empirical study offer the following findings and implications. First. it was found that it was performance risk, psychological risk and online payment risk that have a statistically significant influence upon consumer trust in an online merchant. It implies that a consumer may find an online merchant untrustworthy if either the product quality or the product grade does not match his or her expectations. For that reason, online merchants including digital storefronts and e-marketplaces are suggested to pursue a strategy focusing on identifying the target customers and offering products that they feel best meet performance and psychological needs of those customers. Thus, they should do their best to make it widely known that their products are of as good quality and grade as those purchased from offline department stores. In addition, it may be inferred that today's online consumers remain concerned about the security of the online commerce environment due to the repeated occurrences of hacking or private information leakage. Online merchants should take steps to remove potential vulnerabilities and provide online notices to emphasize that their website is secure. Second, consumer's overall trust was found to have a statistically significant influence on purchase intentions. This finding, which is consistent with the results of numerous prior studies, suggests that increased sales will become a reality only with enhanced consumer trust.

• Journal of Educational Research in Mathematics
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• v.21 no.4
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• pp.327-344
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• 2011

This study is the first step for us toward improving high school students' capability of statistical inferences, such as obtaining and interpreting the confidence interval on the population mean that is currently learned in high school. We suggest 5 underlying concepts of 'discretion of contingency and inevitability', 'discretion of induction and deduction', 'likelihood principle', 'variability of a statistic' and 'statistical model', those are necessary to appreciate statistical inferences as a reliable arguing tools in spite of its occasional erroneous conclusions. We assume those 5 concepts above are to be gradually developing in their school periods and Korean mathematics textbooks of grades 1-12 were analyzed. Followings were found. For the right choice of solving methodology of the given problem, no elementary textbook but a few high school textbooks describe its difference between the contingent circumstance and the inevitable one. Formal definitions of population and sample are not introduced until high school grades, so that the developments of critical thoughts on the reliability of inductive reasoning could not be observed. On the contrary of it, strong emphasis lies on the calculation stuff of the sample data without any inference on the population prospective based upon the sample. Instead of the representative properties of a random sample, more emphasis lies on how to get a random sample. As a result of it, the fact that 'the random variability of the value of a statistic which is calculated from the sample ought to be inherited from the randomness of the sample' could neither be noticed nor be explained as well. No comparative descriptions on the statistical inferences against the mathematical(deductive) reasoning were found. Few explanations on the likelihood principle and its probabilistic applications in accordance with students' cognitive developmental growth were found. It was hard to find the explanation of a random variability of statistics and on the existence of its sampling distribution. It is worthwhile to explain it because, nevertheless obtaining the sampling distribution of a particular statistic, like a sample mean, is a very difficult job, mere noticing its existence may cause a drastic change of understanding in a statistical inference.

• Childhood Kidney Diseases
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• v.12 no.2
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• pp.194-201
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• 2008

Purpose : Voiding cystourethrography(VCUG) is required to detect vesicoureteral reflux(VUR), which may manifest as urinary tract infection(UTI) in children. It is well known that VCUG can cause UTI(post-VCUG UTI). In this study, risk factors for post-VCUG UTI and the preventive effect of antibiotics against this complication of VCUG were explored. Methods : Medical records of 284 patients who underwent VCUG at our hospital in 2007 were reviewed retrospectively. The incidence of post-VCUG UTI and risk factors for post-VCUG UTI, and the impact of antibiotic use on prevention of post-VCUG UTI were evaluated. According to antibiotics usage, we divided the enrolled patients into 4 groups of noantibiotics group, prophylactic antibiotics group(prophylactic antibiotics having been used before), antibiotics-for-VCUG group(antibiotics added for VCUG) and antibiotics-for-treatment group(treatment dose of antibiotics). Results : Seven of 284 children(2.5%) developed UTI after they underwent VCUG. Highgrade(grade$\geq$III) VUR was the only statistically significant risk factor(odds ratio[OR] 6.266, P=0.026) for post-VCUG UTI, while sex, age, and other anomalies of urinary system were not significant. Five post-VCUG UTI cases belonged to prophylactic antibiotics group. Antibiotics use (three groups using antibiotics vs. no-antibiotics group) or addition of antibiotics for VCUG (antibiotics-for-VCUG vs. other groups) did not have any effect on prevention of post-VCUG UTI. Conclusion : The risk factor for post-VCUG UTI was high-grade VUR. Antibiotics use did not prevent post-VCUG UTI in this study.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.129-141
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• 2006

The vertical soil pressure developed in the granular layer of asphalt pavement system is influenced by various factors, including the wheel load magnitude, the loading speed, and asphalt pavement temperature. This research observed the distribution of vertical soil pressure in pavement supporting layer by investigating measured data from soil pressure gage in the KHC Test Road. The existing specification of subbase and subgrade compaction was also evaluated with measured vertical pressure. The finite element analysis was conducted to verify the accuracy of results with measured data because it can maximize research capacity without significant field test. The test data was collected from A5, A7, A14, and A15 test sections at August, September, and November 2004 and August 2005. Those test sections and test data were selected because they had best quality. The size of influence area was evaluated and the vertical pressure variation was investigated with respect to load level, load speed, and pavement temperature. The lower speed, higher load level, and higher pavement temperature increased the vertical pressure and reduced the area of influence. The finite element result showed the similar trend of vertical pressure variation in comparison with measured data. The specification of compaction quality for subbase and subgrade is higher than the level of vertical pressure measured with truck load so that it should be lurker investigated.

• Journal of Korean Society of Rural Planning
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• v.24 no.3
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• pp.73-86
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• 2018

Agricultural or rural landscape provides various ecosystem services. However, the ecosystem services function is declining due to various environmental problems such as climate change, land use change, stream intensification, non-point pollution and garbage. The A1B scenario predicts that the mean air temperature of South Korea will rise $3.8^{\circ}C$ degrees celsius in 2100. Agricultural sector is very vulnerable to climate change, so it must be thoroughly predicted and managed. In Korea, the facility horticulture complex is 54,051ha in 2016 and is the 3rd largest in the world(MAFRA, 2014). Facilities of horticultural complexes are reported to cause problems such as groundwater decrease, vegetation and insects diversity reduction, landscapes damage and garbage increase, compared with the existing land use paddy fields. Heat island phenomenon associated with climate change is also accelerated by the high heat absorption of horticultural sites. Therefore, we analyzed the heat island phenomenon occurring in the facility of horticultural complex in Korea. As an improvement measurement, I examined how much air temperature is reduced by putting the channel and the open space. In the case of the Buyeo area, the Computational Fluid Dynamics (CFD) simulation was analyzed for the average summer temperature distribution in the current land use mode at $38.9^{\circ}C$. As an improvement measurement, CFD simulation after 10% of 6m water channel was found to have an effect of lowering the summer temperature of about $2.7^{\circ}C$ compared with the present average of $36.2^{\circ}C$. In addition, CFD simulations after analyzing 10% of the open space were analyzed at $34.7^{\circ}C$, which is $4.2^{\circ}C$ lower than the present. For the Jinju area, CFD simulations were analyzed for the average temperature of summer at $37.8^{\circ}C$ in the present land use pattern. As an improvement measure, CFD simulations after 10% of 6m water channel were found to have an effect of lowering the summer temperature of about $2.6^{\circ}C$ compared to the current average of $35.2^{\circ}C$. In addition, CFD simulations after analyzing 10% of the open space were analyzed at $33.9^{\circ}C$, which is $3.9^{\circ}C$ lower than the present. It can be said that the effect of summer temperature drop in open space and waterway has been proven. The results of this study are expected to be reflected in sustainable agriculture land use and used as basic data for government - level policy in land use planning for climate change.

• Journal of Trauma and Injury
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• v.23 no.2
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• pp.107-112
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• 2010

Purpose: Recently, the change to a more complex social structure has led to an increased frequency of traumas due to violence, accident and so on. In addition, the severity of the traumas and the frequency of penetrating injuries have also increased. Traumas to cervical and abdominal areas, what are commonly seen by general surgeons, can have mild to fatal consequences because in these areas, various organs that are vital to sustaining life are located. The exact location and characteristics of the injury are vital to treating patients with the trauma to these areas. Thus, with this background in mind, we studied, compared, and analyzed clinical manifestations of patients who were admitted to Wonju Christian hospital for penetrating injuries inflicted by themselves or others. Methods: We selected and performed a retrospective study of 64 patients who had been admitted to Wonju Christian Hospital from January 2005 to December 2009 and who had cervical or abdominal penetrating injuries clearly inflicted by themselves or others. Results: There were 51 male (79.7%) and 13 female (20.3%) patients, and the number of male patients was more dominant in this study, having a sex ratio of 3.9 to 1. The range of ages was between 20 and 86 years, and mean age was 43.2 years. There were 5 self-inflicted cervical injuries, and 19 self-inflicted abdominal injuries, making the total number of self-inflicted injury 24. Cervical and abdominal injuries caused by others were found in 11 and 29 patients, respectively. The most common area involved in self-inflicted injuries to the abdomen was the epigastric area, nine cases, and the right-side zone II was the most commonly involved area. On the other hand, in injuries inflicted by others, the left upper quadrant of the abdomen was the most common site of the injury, 14 cases. In the neck, the left-side zone II was the most injured site. In cases of self-inflicted neck injury, jugular vein damage and cervical muscle damage without deep organ injury were observed in two cases each, making them the most common. In cases with abdominal injuries, seven cases had limited abdominal wall injury, making it the most common injury. The most common deep organ injury was small bowel wounds, five cases. In patients with injuries caused by others, six had cervical muscle damage, making it the most common injury found in that area. In the abdomen, small bowel injury was found to be the most common injury, being evidenced in 13 cases. In self-inflicted injuries, a statistical analysis discovered that the total duration of admission and the number of patients admitted to the intensive care unit were significantly shorter and smaller, retrospectively, than in the patient group that had injuries caused by others. No statistically significant difference was found when the injury sequels were compared between the self-inflicted-injury and the injury-inflicted-by-others groups. Conclusion: This study revealed that, in self-inflicted abdominal injuries, injuries limited to the abdominal wall were found to be the most common, and in injuries to the cervical area inflicted by others, injuries restricted to the cervical muscle were found to be the most common. As a whole, the total duration of admission and the ICU admission time were significantly shorter in cases of self-inflicted injury. Especially, in cases of self inflicted injuries, abdominal injuries generally had a limited degree of injury. Thus, in our consideration, accurate injury assessment and an ideal treatment plan are necessary to treat these patients, and minimally invasive equipment, such as laparoscope, should be used. Also, further studies that persistently utilize aggressive surgical observations, such as abdominal ultrasound and computed tomography, for patients with penetrating injuries are needed.

• Radiation Oncology Journal
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• v.23 no.4
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• pp.211-216
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• 2005

Purpose: It has been reported that all-trans retinoic acid (ATRA) can inhibit glioma growing in vitro. However, clinical trials with ATRA alone in gliomas revealed modest results. ATRA has been shown to increase radiosensitivity in other tumor types, so combining radiation and ATRA would be one of alternatives to increase therapeutic efficacy in malignant gliomas. Thus, we intended to know the role of catalase, which is induced by ATRA, for radiosensitivity if radiation-reduced reactive oxygen species (ROS) is removed by catalase, the effect of radiation will be reduced. Materials and Methods: A rat glioma cell line (36B10) was used for this study. The change of catalase activity and radiosensitivity by ATRA, with or without 3-amino-1, 2, 4-triazole (ATZ), a chemical inhibitor of catalase were measured. Catalase activity was measured by the decomposition of $H_2O_2$ spectrophotometrically Radiosensitivity was measured with clonogenic assay. Also ROS was measured using a 2, 7-dichlorofluorescein diacetate spectrophotometrically. Results: When 36B10 cells were exposed to 10, 25 and $50{\mu}M$ of ATRA for 48 h, the expression of catalase activity were increased with increasing concentration and incubation time of ATRA. Catalase activity was decreased with increasing the concentration of AT (1, $10{\mu}M$) dose-dependently. ROS was increased with ATRA and it was augmented with the combination of ATRA and radiation. ATZ decreased ROS production and increased cell survival in combination of ATRA and radiation despite the reduction of catalase. Conclusion: The increase of ROS is one of the reasons for the increased radiosensitivity in combination with ATRA. The catalase that is induced by ATRA doesn't decrease ROS production and radiosensitivity.

• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.111-120
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• 2011

A purpose of study is to develop optimization and radiation dose exposure reference level by measuring actual radiation dose in condition of quality control of mammography equipment for 39 clinics. The result were as follows. First, we measured T-test separating radiology from general clinic. According to the test, mAs was measured at average 78.58 mAs; radiology at 80.16 mAs and general clinic at 77.22 mAs. And, kerma rate was measured at average 7.71 mGy/mR; radiology at 8.94 mGy/mR and general clinic at 6.66 mGy/mR. HVL was measured at average 0.42 mmAl; radiology at 0.40 mmAl and general clinic at 0.43 mmAl. Average glandular dose was measured at average 1.14 mGy; radiology at 1.09 mGy and general clinic at 1.19 mGy. Second, we measured value of mAs, HVL, processing method and so on dividing two groups. And, we compared and analyzed average value measured using T-test. As a result, there was significance level in SID(P<0.05). There was significance level in mAs(P<0.05). Because processor was measured at 1.00 mGy and CR at 1.17 mGy according to the processing method of radiology. Third, according to the correlation analysis, radiology had significance level between average glandular dose and mAs and general clinic had significance level between average glandular dose and SID(P<0.05). Forth, as a result of regression analysis, mAs affected 22.7%t of average glandular dose and SID affected 21.7% of average glandular dose, which had significance level(P<0.05). And, mAs affected 29.0% of average glandular dose in radiology and SID affected 29.1% of average glandular dose in general clinic, which was most influential.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.62-68
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• 2014

Purpose: After I-131 therapy, SPECT/CT is useful in identifying location of thyroid remnants and metastasis of thyroid cancers. An excessive uptake of thyroid leads to a ringing artifact in the SPECT images. The aim of this study is to investigate and suggest a proper post filters to remove ringing artifact and produce better image quality. Materials and Methods: A low-cost, customized thyroid-mimicking phantom, consisting of an acrylic bottle and a hollow sphere was used for SPECT/CT Discovery (GE Healthcare, USA). It was filled with I-131 solution. The ratio of hollow sphere to background were varied as 50:1, 200:1, 1000:1 and 4000:1. Acquired images were reconstructed by OSEM (2 iterations, 10 subsets) with and without Evolution (resolution recovery correction, GE). Three different post-filters were applied; Butterworth (cut off: 0.38 to 0.58 with intervals of 0.05), Hanning (cut off: 0.8 to 1 with intervals of 0.05) and Gaussian (FWHM: 3 to 5 with intervals of 0.5) filters. Contrast, background variability, air area variability, and full width half maximum (FWHM) were compared. Results: Higher contrasts were obtained from the SPECT images with Evolution than without Evolution. In the case of images without Evolution, image distortion such as star artifact was generated. For all sphere-to-background ratio, the Butterworth filter showed better constrasts and FWHMs than other two filters, but the ringing artifact was still generated in all studies except 50:1 and it was decreased as cutoff value was increased. The ringing artifact didn't appear with Hanning and Gaussian filters at all studies, however constrats and FWHMs with Gaussian was worse than Hanning filter. For the images having ringing artifacts, the background variability and air area variability were increased. Conclusion: In this study, we suggested that it is desirable to use Hanning filter when the ringing artifact is generated and to use Butterworth filter when ringing artifact is not generated in I-131 SPECT.