• Progress in Medical Physics
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• v.23 no.3
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• pp.138-144
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• 2012

Dose distribution throughout the clinical organ range of motion was analyzed using a respiratory-motion simulator that was equipped with a polymer gel dosimeter and EBT2 film. The normoxic polymer gel dosimeter was synthesized from gelatin, MAA, HQ, THPC and HPLC. The gel dosimeter and EBT2 film were irradiated with Co-60 gamma rays that were moved along the x-axis and y-axis in ${\pm}1.5cm$ steps at five-second intervals. The field size was $5{\times}5cm^2$. The SSD was 80 cm and set to 10 Gy at a depth of 2 cm. The PDD at a depth of 50 mm was 75.2% in the ion chamber, 82.3% in the static state and 86.1% in the dynamic state in the gel dosimeter. The penumbra for the dynamic state target, which was measured using the gel dosimeter, averaged 10.89 mm, this is a 40.5% increase over the penumbra of the static state target of 7.74 mm. In addition, when measuring with gel dosimetry, the value for the penumbra is 36.6% smaller in the static state and 29.4% smaller in the dynamic state compared to measuring with film. The aim of this study was to investigate the dosimetric properties of a normoxic polymethacrylic acid gel dosimeter in static and dynamic states and to evaluate the potentiality as a relative dosimeter for dynamic therapeutic radiation.

• Progress in Medical Physics
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• v.21 no.1
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• pp.113-119
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• 2010

Software for GafChromic EBT2 film dosimetry was developed in this study. The software provides film calibration functions based on color channels, which are categorized depending on the colors red, green, blue, and gray. Evaluations of the correction effects for light scattering of a flat-bed scanner and thickness differences of the active layer are available. Dosimetric results from EBT2 films can be compared with those from the treatment planning system ECLIPSE or the two-dimensional ionization chamber array MatriXX. Dose verification using EBT2 films is implemented by carrying out the following procedures: file import, noise filtering, background correction and active layer correction, dose calculation, and evaluation. The relative and absolute background corrections are selectively applied. The calibration results and fitting equation for the sensitometric curve are exported to files. After two different types of dose matrixes are aligned through the interpolation of spatial pixel spacing, interactive translation, and rotation, profiles and isodose curves are compared. In addition, the gamma index and gamma histogram are analyzed according to the determined criteria of distance-to-agreement and dose difference. The performance evaluations were achieved by dose verification in the $60^{\circ}$-enhanced dynamic wedged field and intensity-modulated (IM) beams for prostate cancer. All pass ratios for the two types of tests showed more than 99% in the evaluation, and a gamma histogram with 3 mm and 3% criteria was used. The software was developed for use in routine periodic quality assurance and complex IM beam verification. It can also be used as a dedicated radiochromic film software tool for analyzing dose distribution.

• Childhood Kidney Diseases
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• v.9 no.2
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• pp.183-192
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• 2005

Purpose : The long term disease course and prognostic factors were evaluated in childhood Henoch-$Sch{\ddot{o}}nlein$ puruura nephritis(HSPN). Methods : A total of 75 children(44 boys and 31 girls) with HSPN were included in this study. The onset age was $8.0{\pm}3.1$ years(2.3-l5.3 years), and the follow-up period was $4.3{\pm}3.6$ years(1.0-17.1 years). Kidney biopsy was done in 24 children(32$\%$). Initial clinical and laboratory findings were evaluated. In addition, polymorphisms of the renin angiotensin system(RAS) genes(insertion/deletion in intron 16 of ACE gene, M235T in AGT gene, and A1166C in AGTR gene) were analysed. The initial and last clinical states were classified into 4 groups as follows A, normal; B, minor urinary abnormalities; C, active renal disease (nephrotic-range proteinuria and/or hypertension with serum creatinine $\leq$1.5 mg/dL); D, renal insufficiency. Results : At the onset, the clinical states of the patients were B in 26(35$\%$), C in 46(61$\%$), and D, in 3(4$\%$). The distribution of the RAS gene polymorphism of HSPN were not different from that of 100 healthy control subjects. At the last follow-up, the clinical states of the patients were A in 23(31$\%$), B in 38(50$\%$), C in 9(12$\%$), and D in 5(7$\%$). A multiple logistic regression identified age at the onset and initial urine protein excretion as significant prognostic factors. Analysis of genotypes of the 3 RAS genes as prognostic values revealed no statistical significance. Conclusion : Older age at onset and severe proteinuria were identified as poor prognostic factors of childhood HSPN. Implication of the RAS gene polymorphism In HSPN could not be validated in this small-scale retrospective study. (J Korean Soc Pediatr Nephrol 2005;9:183-192)

• Childhood Kidney Diseases
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• v.9 no.2
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• pp.193-200
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• 2005

Purpose : An atrophic renal scar(RS) is one of the underlying causes for childhood hyper tension and chronic renal failure. The risk factors for atrophic renal scar were evaluated. Methods : 41 children, who presented with first febrile urinary tract Infection at the Ewha Womans University Hospital between 1995 and 2003 and had generalized atrophic RS on $^{99m}Tc-DMSA$ renal scan, were retrospectively studied. Atrophic RS was divided into severe atrophic RS(n=14) if relative uptake on renal scan was below 10$\%$, or mild atrophic RS(n=27) if relative uptake on renal scan was between 10-35$\%$. RS was defined as congenital if the scar was detected on the first renal scan, and as acquired if the scar developed on the follow-up renal scan from acute pyelonephritis of the first renal scan. The control group was consisted of randomly selected 41 children with segmental RS. The risk factors for atrophic RS such as the generation time, VUR, gender and ACE gene polymorphism were evaluated. Results : The age distribution of atrophic RS and segmental RS did not differ significantly (P>0.05). The rate of congenital RS in atrophic RS was 61.0$\%$(25/41), which was significantly higher than 9.8$\%$(4/41) of segmental RS(P<0.01). Atrophic RS developed mote frequently in male children(M:F 68.3$\%$ 31.7$\%$) than segmental RS(M:F 41.4$\%$ .58.5$\%$)(P<0.05). Vesicoureteral reflux(VUR) was found in 92.7$\%$(38/41) of 4he atrophic RS, which was significantly higher than 53.7$\%$(22/41) of segmental RS(P<0.05). In children without VUR, the male to female ratio did not differ between atrophic RS and segmental RS(P>0.05) But in children with VUR, there was a higher proportion of males with severe atrophic RS than segmental RS($85.7\%:45.5\%$) ACE gene polymorphism did not differ between the atrophic and segmental RS groups, irrespective of the presence of VUR(P>0.05). Conclusion : Most atrophic RSs were congenital which could not be preventable postnatally and the major risk factors were VUR and the male gender. ACE gene polymorphism was not the significant risk factor for an atrophic RS. (J Korean Soc Pedialr Nephrol 2005;9:193-200)

• Childhood Kidney Diseases
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• v.9 no.2
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• pp.213-221
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• 2005

Purpose : Urachal anomalies are rare but are known to develop several complications, especially infection. Moreover, uniform guidelines for management have not been presented because of the variable clinical characteristics of these anomalies. The purpose of this report is to review our experience with urachal anomalies and attempt to determine the optimal management. Methods : We retrospectively reviewed the records of fourteen children with a variety of urachal anomalies who had been treated from January 1996 to June 2005 at Dong Kang General Hospital. Results : The age distribution of the patients(mean age; 3.8 years) was six neonates, one infant, five preschool-age and two school-age children. The male to female ratio was 1:1. Six cases of urachal cyst, four cases of patent urachus, two cases of urachal sinus and two cases of urachal diverticulum were found. Three patients with patent urachus and one with urachal cyst had hydronephrosis. Other associated anomalies included an inguinal hernia in one patient with urachal sinus and a vesicoureteral reflux in one patient with urachal diver ticulum. As a first-line diagnostic tool, high-resolution ultrasound examination was performed in thirteen cases and computed tomography in one case. Surgical excision was performed in nine patients with urachal anomaly. Five cases out of six neonatal cases experienced spontaneous improvement during a three-month follow up period. Due to frequent infection of the umbilicus, surgical excision was performed on one neonate with urachal sinus. Conclusion : All patients with urachal anomalies should undergo investigation for associated anomalies. The neonate with urachal anomalies, especially patent urachus, do not require surgical excision unless the patient has multiple episodes of recurrent infection. (J Korean Soc Pediatr Nephrol 2005;9:213-221)

• Childhood Kidney Diseases
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• v.6 no.1
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• pp.48-55
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• 2002

Purpose: Thin glomerular basement membrane nephropathy (TGBMN) is recognized as the leading cause of microscopic hematuria in both children and adults. However thinning of glomerular basement membrane (TCBM) has been found in healthy adult and also is known to be associated with various renal diseases such as Alport syndronh, IgA nephropathy and mesangial proliferative glomerulonephritis. The association of TGBM with minimal change nephrotic syndrome (MCNS) has been very rare so that the present study was undertaken to determine the relationship between TGBM and MCNS. Methods: The study population consisted of 49 children with biopsy- proven MCNS who have been admitted to the pediatric department of Kyungpook University Hospital during the past 5 years from 1997 to 2001. Group I consisted of 8 children associated with TGBM and Group II 41 children without TCBM. Various parameters such as age of illness, duration from discovery of illness to the time of biopsy, family history of hematuria and other laboratory tests were compared between these two groups and the following results were obtained. Results: Age distribution showed slightly older age in Group I ($7.1{\pm}3.5$ years) compared to Group II ($4.8{\pm}2.9$ years). However this was not statistically different (P=0.056). Family history of hematuria was noted in 2 cases in Group II. Though statistically not significant, hematuria was seen in 2 out of 8 cases ($25\%$) in MCNS children with TGBM, compared to 7 out of 41 cases ($17\%$) with MCNS children without TGBM. Other parameters such as BUN, creatinine, 24 hours urine protein excretion, serum protein, albumin, cholesterol, and T4/T8 ratio, showed no difference. Also renal biopsy finding showed no significant difference and the thickness of glomerular basement membrane in Croup I was $188{\pm}30nm$. Conclusion: TGBM was found in 8 out of 49 children with MCNS ($16.3\%$). And this high frequency of occurrence indicates that these association is not an incidental findings. Typical clinical findings of TCBMN was not noted in all of the 8 children with MCNS associated with TGBM, suggesting that thinning of glomerular basement membrane (TCBN) is secondary to rather than the cause of MCNS. (J Korean Soc Pediatr Nephrol 2002;6: 48-55)

• 한국해양학회지
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• v.23 no.1
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• pp.24-40
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• 1988

In the Korea Ocean Nodule Development (KONOD)-1 area between the Clarion and Clipperton fracture zones of the northeastern equatorial Pacific, the pelagic sediment layer can be divided into two or three units on air-gun seismic profile. The acoustic units can be also correlated with those in the DSDP site 163 core. The topmost unit (unit I) is acoustically transparent and consists of zeolitic clay and radiolarian ooze of late Oligocene to middle Eocene age. Unit IIA is well-stratified and transparent in the lower part. consisting of the radiolarian ooze intercalated with chert beds and zeolitic clay of early Eocene to Paleocene age. Unit IIB is stratified with layers of silicified and compacted flinty-cherty nannofossil chalk (late Cretaceous) on top of the acoustic basement. Units I and IIA form the Line Islands Formation that overlies an unnamed formation of unit lIB. The entire layers and the unit I layer propressively thin northward, except near the Line Islands Ridge. The distribution of sediment layer has been controlled by the equatorial Cenozoic CCD and the northward spreading of the Pacific plate. The change of CCD corresponding to the subsidence and migration of the plate has determined the sediment composition of the DSDP 163 core passed across the equator of high sedimentation suite. The late Cretaceous sedimentary layer (unit IIB) in the 163 core was formed above the CCD south of the equator. The unit IIA resulted from rapid subsidence of the Pacific plate below the CCD in the Paleocene. The unit IIA is seen only in the west of 149 W. Both the units IIA and I were probably formed during the Pacific plate passing and after leaving the equatorial region respectively since early Eocene. In the south of the KONOD-l area, the unit I was redistributed by bottom current, a branch of the Antarctic Bottom Water flowing eastward guided by the Clipperton fracture zone. The activities of bottom currents were prolonged for a long geological time. Turbidite layers occur more than 350 km from the Hawaiian Ridge to near the Clarion fracture zone. They originated directly from the Hawaiian Ridge, filling the topographic lows.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.739-752
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• 2006

Deep-sea surface sediments acquired by multiple corer from 69 stations in the Clarion-Clipperton fracture zone of the northeast equatorial Pacific, were examined to understand the correlation of mass physical properties and sedimen-tological processes. The seabed of the middle part ($8-12^{\circ}N$) of the study area is mainly covered by biogenic siliceous sediment compared with pelagic red clays in the northern part ($16-17^{\circ}N$). In the southern part ($5-6^{\circ}N$), water depth is shallower than carbonate compensation depth (CCD). The mass physical properties such as grain size distribution, mean grain size, water content, specific grain density, wet bulk density, void ratio, and porosity of sediments are distinctly different among the three parts of the study area. Surface sediments in northern part are characterized by fine grain size and low water contents possibly due to low primary productivity and high detrital input. Conversely, sediments in the middle part are characterized by coarse grain size and high water contents, which might be caused by high surface productivity and deeper depth than CCD. The sediments show low water contents and high density in the southern part, which can be explained by shallower depth than CCD. Our results suggest that the variations in mass physical properties of sediments are influenced by combined effects including biogenic primary productivity of surface water, water depth, especially with respect to CCD, sedimentation rate, detrital input, and the geochemistry of the bottom water (for example, formation of authigenic clay minerals and dissolution of biogenic grains).

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.753-770
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• 2006

In urban areas, groundwater pollution is heavily affected by urbanization with land use types. This study aims to characterize groundwater quality and contamination in Sasang industrial area of Busan Metropolitan City where metalworking, machinery and footwear factories are located. Busan Metropolitan City is the highest in the utilization of groundwater resources among the metropolitan cities in Korea. $K^+,\;Na^+,\;Ca^{2+},\;Mg^{2+},\;Cl^-,\;SO_4^{2-}\;and\;HCO_3^-$ concentrations, and electrical conductivity (EC), total dissolved solids (TDS) and salinity are high in the areas near the Nakdong River. The results are attributed to the influence of salt water which intruded into the coastal sediments during sedimentation. In addition, the dominant chemical type of Ca-Cl indicates the influence of salt water in the geological formations as well as anthropogenic pollution. $SiO_2$ ion is interpreted to originate from both water-silicate mineral reactions and the decomposition of cement concretes. Trichloroethylene (TCE) was detected at 12 sites of total 18 sites. However, tetrachloroethylene (PCE) was detected at f sites and 1.1.1-trichloroethane (TCA) at 3 sites. According to the factor analysis, factor 1 was explained by 49.8%, factor 2 19.8%, and factor 3 11.0% with total 80.6% explanation. pH, TDS, salinity, $Ca^{2+},\;K^+,\;Mg^{2+},\;Na^+,\;Al^{3+},\;As^{3+},\;Cl^-\;and\;Fe^{2+}$ were positively highly loaded to factor 1. The chemical components loaded to factor 1 represent the chemical characteristics of both industrial pollution and influence by salt water. Based on the cluster analysis and distribution pattern of chemical components, the concentration of $Na^+,\;Ca^{2+},\;Cl^-,\;SO_4^{2-}\;K^+,\;and\;Mg^{2+}$ is high in the riverside area of the Nakdong River composed of coastal sediments that is influenced by salt water. The downstream area of the Hakjang Stream is judged to be affected by both salt water and artificial pollution. The other part of the study area is interpreted by anthropogenic pollution.

• Economic and Environmental Geology
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• v.47 no.3
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• pp.205-217
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• 2014

As Mt. Backdu is expected to erupt, the social and economic impacts of the eruption on the Korean peninsula as well as on the world become a research topic of interest. If the volcano erupts, South Korea can be directly impacted by volcanic ash, which will bring out secondary damages in various ways. Given that the direct damage is a basis to estimate indirect and secondary damages, this paper was to review a method to estimate direct damages, called catastrophe risk models, and estimate the direct damages of available eruption scenarios of Mt. Baekdu. Based on the results, the damages by volcanic ash will occur mostly around Gangwon province if the Mt. Backdu erupts. Thus the inventory lists and their damage functions of Gangwon provinces were collected. In particular agricultural and forestry products were surveyed based on the land use. Direct damages were estimated using volcanic ash distribution of eruption scenarios, inventory information and their damage functions. In result, a scenario in winter caused the damage of 299.8 billion KRW (20.4% of total agricultural production in 2010) and 28.9 billion KRW (9.0% of total forestry production in 2010) in agriculture and forestry, respectively. The damages in agriculture was larger, and it is due to the damage functions which show the agricultural products are more vulnerable to volcanic ash than forestry products. Also the agricultural production (1,471.7 billion KRW in 2010) are more than 4.5 times the forestry production (322.3 billion KRW in 2010) in Gangwon province. Inje and Gangnung had the most damages in the scenario in winter. Inje had the most damage due to the thick ash deposit (8.5 mm in average) despite the low production. On the other hand, Goseong had a low damage compared to the ash thickness larger than 20mm, owing to the low production. The direct damage estimated through this process can be used to estimate indirect damages.