• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.61-72
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• 2011

In the benefits of ITS, there are intangible gains from real-time traffic information as well as classical gains such as travel time saving. These intangible gains are difficult to be estimated by existing transportation investment appraisal commonly used in SOC investment. The major reason is not because of the absence of methodology but because of the absence of generalized values of particular benefits from real time traffic information. This research explores the value of real-time traffic information on VMS that is the most representative of ITS services, by using CVM with Double Bounded Dichotomous Choice Question. Willingness-To-Pay (WTP) functions of drivers are built with survival functions using various types of probability distribution functions such as Exponential, Log-logistic, and Weibull functions. The results reveal that Log-logistic distribution is the most appropriate distribution model to estimate WTP, and the estimated coefficients are stable through LR (Likelihood Ratio) test. For the further study, it is recommended to perform statistical tests of temporal and spatial transferability that is not examined in this research due to the lack of data.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.93-107
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• 2013

Thermal conduction of the particulate composites or granular materials can be widely used in porous materials and geotechnical engineering. And it has continued to develop "effective thermal conductivity" of medium by modeling energy relationship among particles in medium. This study focuses on the development of the effective thermal conductivity at the unsaturated conditions of soils using the modified network model approach assisted by synthetic 3D random packed systems (DEM method, Discrete Element Method) at the particle scale. To verify the network model, three kinds of glass beads and the Jumunjin sand are used to obtain experimental values at various unsaturated conditions. The PPE (Pressure Plate Extractor) test is then performed to obtain SWCC (Soil-Water Characteristic Curve) of soil samples. In the modified network model, SWCC is used to adjust the equivalent radius of thermal cylinder at contact area between particles. And cutoff range parameter to define the effective zone is also adjusted according to the SWCC at given conditions. From a series of laboratory tests and the proposed network model, the modified network model which adopts a SWCC shows a good agreement in modeling thermal conductivity of granular soils at given conditions. And an empirical correlation between the fraction of the mean radius (${\chi}$) and thermal conductivity at given saturated condition is provided, which can be used to expect thermal conductivity of the granular soils, to estimate thermal conductivity of granular soils.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.205-214
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• 2012

Crack widths play an important role in the serviceability limit state. When crack widths are controlled sufficiently, the reinforcement corrosion can be reduced using only existing concrete cover thickness due to low permeability in the region of finely distributed hair-cracks. Thus, the knowledge about the tensile crack opening is essential in designing more durable concrete structures. Therefore, numerous researches related to the topic have been performed. Nevertheless accurate measurement of a crack width is not a simple task due to several reasons such as unknown potential crack formation location and crack opening damaging strain gages. In order to overcome these difficulties and measure precise crack widths, a displacement measurement system was developed using digital image correlation. Accuracy calibration tests gave an average measurement error of 0.069 pixels and a standard deviation of 0.050 pixels. Direct tensile test was performed using ultra high performance concrete specimens. Crack widths at both notched and unnotched locations were measured and compared with clip-in gages at various loading steps to obtain crack opening profile. Tensile deformation characteristics of concrete were well visualized using displacement vectors and full-field displacement contour maps. The proposed technique made it possible to measure crack widths at arbitrary locations, which is difficult with conventional gages such as clip-in gages or displacement transducers.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.12 no.1
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• pp.94-102
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• 2001

Bullying has recently become a serious social problem in Korean society. Bullying, which is defined as a phenomenon that one particular student is intensively and continuously harassed or ostracized by a group of students, is apt to produce harmful effects on bullies as well as victims. Bullying has many causes including those originated from the personality of victims and bullies. This study is designed to investigate the difference in personality trait between victims, bullies, victims/bullies, and neither. The subjects of this study were 215(115 male and 100 female) 6th-grade students in the primary school in Seoul. Questionnares were distributed to the students and their carers. The student carers were also asked to answer the questions for a survey called the Korean Personality Invertory for Children(KPI-C). SPSS was used for the statistical analysis of the collected test information；ANOVA, post hoc scheffe test, and T-test were used to analyze the differences between the tested groups. The result of the study is as follows. 1) The victims, bullies, victims/bullies and neither totaled respectively 11(5.1%), 56(26.0%), 11(5.1%) and 137(63.7%). 115 were male and 100 were female. 2) The frequency of victimized is as follows：1 time is 15(7.0%), 2 times is 4(1.9%) and more than 3 times is 3(1.4%). The frequency of bullying is as follows；1 time is 40(18.6%), 2 times is 17 (7.9%) and more than 3 times is 10(4.7%). 3) The differences between froups in KPI-C test is as follows. (1) The ESR(p=.00) scale was significantly lower in the victims group than in the neither group and the HPR(p=.00) scale and PSY(p<.01) scale were significantly higher in the former than in the latter. (2) The ESR(p=.00) scale was significantly lower in the victims/bullies group than in the neither group and the SOM(p=.00) scale and HPR(p=.00) scale were significantly higher in the formaer than in the latter. (3) The SOC(p=.00) scale, PSY(p<.01) scale and AUT(p=.00) scale were significantly higher in the victims group than in the bullies group. (4) There is statistically no difference between the bullies group and the neither group. To conclusion, Victims need to learn how to cope with harsh situations, or they will have to face difficulties in relationships. Even after they experience bullying, they may not realize why they have been bullied, or speak out for themselves.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.4
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• pp.231-238
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• 2007

In the previous study, the anti-oxidant activity of extract/fraction of Sueada asparagoides (SA) was investigated and the results showed that the ethylacetate (EtOAc) fraction and its aglycone fraction had the best performance on the free radical scavenging activity, reactive oxygen species scavenging (ROS) activity and cell protective activity (J. Soc. Cosme. Scientists Korea, 33(3), 145 (2007)). In this study, the stability of cream containing 0.3% SA EtOAc extract (called extract below) was evaluated. pH, viscosity and absorbance (363 nm) were measured under the 4 different temperatures ($0^{\circ}C,\;25{\circ}C,\;37{\circ}C\;and\;45{\circ}C$) and under the sun light at the 4 week intervals during the 12 weeks in total. The control cream without containing the extract did not show pH change under the different temperatures mentioned above. However, the pH of the cream the extract was decreased 0.08 at the temperature ranges of $0^{\circ}C\;to\;37^{\circ}C$. Under the $45^{\circ}C$ and sun light condition, the pH was decreased 0.51 and 0.66, respectively. The cream containing the extract did not show absorbance change at the temperature ranges of 0 to $37^{\circ}C$ for 12 weeks. Instead, the absorbance of the cream treated under $45^{\circ}C$ and sun light condition was decreased 7.6 % and 7.4 %, respectively. This decrease in absorbance is relatively small compared to the 48.3 % decrease of the extract sampled from the cream using ethanol solution. This indicates that the extract is stabilized in the cream. After treating the cream for 12 weeks under the different temperatures, the viscosity was measured for the cream containing the extract and control cream. The values were increased by 1,748 cPs in average compared to the initial value for the former and by 951 cPs in average for the latter. On the other hand, the viscosity of control cream treated under the sun light for 12 weeks was significantly decreased (4,022 cPs) relative to the cream containing the extract, which showed 2,484 cPs increase in viscosity. This indicates that the SA extract contributes to the stability of the emulsion product by protective effect to maintain the viscosity of the cream against sun light. In addition, any change in color or smell was not observed through 12 weeks of the experimental time period. Thus, it is concluded that it is still not clear in the stability of the cream containing the extract when it is stored for the long time. Accordingly, it is suggested that further study is needed to provide more information to the manufactures, who are seeking for the application of the extract to improve the anti-oxidant activity and stability of cosmetic products.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.170-175
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• 2009

The extract of Platycarya strobilacea is known to possess a wide range of pharmacological activities including anti-inflammatory, anti-fungal, and anti-cancer properties. We have reported that the ethyl acetate fraction of Platycarya strobilacea (PS-ET fraction) has high potential as an antioxidant agent (J. Soc. Cosmet. Scientists Korea 34(4) 275, 2008). In this study, antibacterial activity of the fraction and stability of the cream containing 0.2% PS-ET fraction were investigated for the application to cosmetics. Antibacterial activity of PS-ET fraction against various skin pathogenic bacteria (Propionibacterium acnes, Staphylococcus aureus, and Pityrosporum ovale) was measured by minimum inhibitory concentration (MIC). MIC values of PS-ET fraction on P. acnes, S. aureus, and P. ovale were 0.13%, 0.06% and 0.25%, respectively. The results showed that the antibacterial activity of the fraction was the highest in the S. aureus. For the stability evaluation, pH and viscosity of the cream containing 0.2% PS-ET fraction were measured. The results showed that pH changes of the cream containing PS-ET fraction was lower than the control cream without PS-ET fraction. And the PS-ET fraction could repress the decrease of viscosity of the cream against sunlight treatment. These results suggest that the fraction of Platycarya strobilacea has high potential as bactericide against the skin pathogenic bacteria and could be added to improve the stability of cosmetic products.

• Childhood Kidney Diseases
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• v.5 no.1
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• pp.22-29
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• 2001

Purpose : 99mTc DMSA renal scan have been widely used not only for tile evaluation of renal scars but also for the diagnosis of acute pyelonephritis. Recent studies have shown SPECT images have higher accuracy than the planar images with some controversy. We evaluated the availability of the SPECT images adding to planar images for the diagnosis of acute pyelonephritis(APN) and renal scar in children with urinary tract infection (UTI). Methods : 130 children with UTI (260 kidney units) and 22 follow-up children (44 kidney units) were included between January 1, 1997 and July 31, 1999 at Ewha University Mokdong Hospital. Planar Anterior and posterior images and SPECT axial and coronal images of 99mTc DMSA renal scan were obtained with Starcam 4000-i U.S.A. GE at 3 hours after 99mTc DMSA I.V. injection. The data were analyzed by Chi square test after Yates's correction. Results : The detection rate of the acute pyelonephritis by SPECT images was 12.3$\%$ higher than that of planar images ($47.7\%\;vs\;35.4\%$) by the patient and 6.9$\%$ higher also ($31.9\%\;vs\;25.4\%$) by the kidney unit. 18 kidney units with negative planar images had focal defect in 10 kidney units (3.8$\%$) and multifocal defect in 8 kidney units (3.1$\%$) on SPECT images, but 1 kidney unit with positive planar image had negative SPECT image. SPECT images were superior to tile planar images in 17.3$\%$. identical in 82.3$\%$ and inferior in 0.4$\%$ to planar image. The detection rate of tile renal scars by SPECT images was 13.7$\%$ higher than planar images by the patient ($68.2\%\;vs\;54.5\%$) and 6.8$\%$ higher also ($43.2\%\;vs\;36.4\%$) by the kidney unit. SPECT images were superior to the planar images in 17.3$\%$ and identical in 82.3$\%$ to planar image. Conclusion SPECT images had shown higher detection rate and better image than planar images for the diagnosis of the acute pyelonephritis and the evaluation of the renal scars. (J. Korean Soc Pediatr Nephrol 5 : 22- 9, 2001)

• Childhood Kidney Diseases
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• v.5 no.1
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• pp.36-42
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• 2001

Purpose : Vesicoureteral reflux is the most commonly inherited disease detected in children with urinary tract infection. The incidence of vesicoureteral reflux among siblings of children with known vesicoureteral reflux is 8$\%$ to 45$\%$ according to different authors. Family screening of a patient with vesicoureteral reflux is important in order to prevent reflux nephropathy. The purpose of this study is to determine the incidence of vesicoureteral reflux in asymptomatic family of children with vesicoureteral reflux and the factors which influence the family history. Methods : The study group consisted of 27 families of patients with vesicoureteral reflux. The total number in the group were 79 persons. BUN, Cr, urineanalysis, voidingcystourethrography(VCUG) and 99mTc -dimercaptosuccinic acid(DMSA) renal scan were performed oil tile siblings. As for tile parents the same tests were performed except the VCUG. Results : The abnormality was detected in 7 of 27 families(25.9$\%$). Vesicoureteral reflux was detected in 5 of 20 siblings and renal scar ns detected in 3 of 32 parents. In children with vesicoureteral reflux, renal scar was detected in 24 of 32 children. Between the group with the abnormality in its family(Group A) and the group without the abnormality in its family(Group B), There was no difference of creatinine clearance between two groups. More renal scars were detected in group A according to the DMSA(A:100$\%$, B:75$\%$. t-test P<0.05). There was no difference of grade of VCUG between two groups. There was no difference between one site and both sites in two groups. In tile case of tile siblings with vesicoureteral reflux, there was high incidence of renal scar in a patient with vesicoureteral reflux according to the DMSA. Conclusion : It is important to screen vesicoureteral reflux and renal scar in case of urinary tract infection to prevent reflux nephropathy. This study implies that it is necessary to screen the family of a patient with vesicoureteral reflux especially with renal scar. (J, Korean Soc Pediatr Nephrol 5 : 36- 42, 2001)

• Childhood Kidney Diseases
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• v.9 no.2
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• pp.201-212
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• 2005

Purpose : Acute pyelonephritis is one of the most common causes of unexplained fever in children. It may lead to the development of progressive renal damage. However, the deteclion of acute pyelonephritis can be difficult, especially in infants. The objective of this study was to evaluate the diagnostic value of various lab tests and imaging studies for acute renal parenchymal changes in children with APN. We correlated the clinical and laboratory manifestations of acute pyelonephritis with the Imaging studies. Methods : We reviewed the records of 115 children (85 males and 30 females) who were hospitalized Outing the period of January 1998 to December 2002 with initial clinical symptoms suggestive of pyelonephritis. The patients' age, sex, duration of fever, laboratory findings, and causative organisms were compared with the findings of imaging studies (Technetium-99m dimercaptosuccinic acid renal scan, renal ultrasonography, intravenous pyelography, voiding cystourethrography). Results : No significant relation between the number of febrile days, leukocyte count, causative organism, and the renal abnormalities in the imaging studies were observed. On the other hand, both C-reactive protein and erythrocyte sedimentation rate levels were significantly elevated in children with positive dimercaptosuccinic acid renal scan. Furthermore, females and children older than 1 year presented with significantly higher rate of abnormal dimercaptosuccinic acid renal scan findings and vesicoureteral reflux presented by voiding cystourethrography. Conclusion : We recommend females and children older than 1 year who are suspected of acute pyelonephritis be evaluated carefully for renal involvement by performing imaging studies including dimercaptosuccinic acid renal scan and voiding cystourethrography. (J Koroan Soc Pediatr Nephrol 2005;9:201-212)

• Childhood Kidney Diseases
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• v.5 no.2
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• pp.164-175
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• 2001

Purpose : Alport syndrome is a hereditary nephrotic disease characterized by progressive nephrotic symptom, sensorineural hearing loss, ophthalmic abnormality, typical microscopic findings, and familial occurrence. In this study, we tried to find the risk factors related with its prognosis by taking a close observation on clinical symptoms of children with Alport syndrome reviewing retrospectively. Materials & methods : We chose children diagnosed as Alport syndrome in renal biopsy during 20 years(from 1980, Jan. until 1999, Dec.) who could receive follow up studies in tile department of pediatrics. They were divided into two groups by comparing renal function at the time of diagnosis and at current status. We compared several clinical aspects in them, and applied nonparametric test for statistical analysis. Results : The sex ratio(male:female) of 24 children was 3:1. The most common clinical symptom presented at their first visit was gross hematuria. Among those 24 children, 11 cases($46\%$) of progressing into chronic renal failure(Group II) were observed. Hypertension, proteinuria and edema were seen much frequently in group II. The level of serum protein, albumin, and creatinine clearance were decreased while BUN, creatinine were relatively increased. All the results were statistically significant. Conclusion Clinically significant risk factors related to prognosis in Alport syndrome were the presence of hypertension, edema, and proteinuria at the time of diagnosis. Also, the level of serum protein, albumin, BUN, creatinine, and glomerular filtration rate were proved to be important factors in predicting prognosis. We believe that studies on these possible risk factors would be of great help in treating and predicting prognosis of children suffering with Alport syndrome. (J Korean Soc Pediatr Nephrol 2001;5 : 164-75)