• Journal of Radiation Protection and Research
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• v.35 no.1
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• pp.34-42
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• 2010

With the expanded use of radiation in modern medical practices, the most important issue in regards to efforts to reduce individual exposure dose is quality assurance. Therefore in order to study the present condition of quality assurance, the Gwangju Metropolitan City area was divided into five districts each containing ten hospitals. Four experiments were conducted: a reproducibility experiment for kVp, mA, and examination time (sec) intensity of illumination; half-value layer (HVL) measurement; and beam perpendicularity test matching experiment. The tube voltage reproducibility experiment for all fifty hospitals resulted in a 95.33% passing rate and mA and examination time both resulted in a 77.0% passing rate. The passing rate for intensity of illumination was 86.0% and 52.0% for HVL, which was the lowest passing rate of all four factors. For the beam perpendicularity test matching experiment, generally the central flux is matched to within $1.5^{\circ}$. Of all fifty hospitals 30.0% were beyond $3^{\circ}$. The results of the survey showed that 58% responded that they knew about quality assurance cycle. All fifty respondents stated that they have not received any training in regards to quality assurance at their current place of employment. Although quality assurance is making relative progress, the most urgent issue is awareness of the importance of quality assurance. Therefore, the implementation of professional training focusing on safety management and accurate quality assurance of radiation will reduce the exposure to radiation for radiologists and patients and higher quality imaging using less dosage will also be possible.

• Journal of The Korean Astronomical Society
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• v.12 no.1
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• pp.41-70
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• 1979

From $B\ddot{o}hm$-Vitense's atmospheric model calculations, the relations, [$T_e$, (B-V)] and [B.C, (B-V)] with respect to heavy element abundance were obtained. Using these relations and evolutionary model calculations of Rood, and Sweigart and Gross, analytic expressions for some physical parameters relating to the C-M diagrams of globular clusters were derived, and they were applied to 21 globular clusters with observed transition periods of RR Lyrae variables. More than 20 different parameters were examined for each globular cluster. The derived ranges of some basic parameters are as follows; $Y=0.21{\sim}0.33,\;Z=1.5{\times}10^{-4}{\sim}4.5{\times}10^{-3},\;age,\;t=9.5{\sim}19{\times}10^9$ years, mass for red giants, $m_{RG}=0.74m_{\odot}{\sim}0.91m_{\odot}$, mass for RR Lyrae stars, $m_{RR}=0.59m_{\odot}{\sim}0.75m_{\odot}$, the visual magnitude difference between the turnoff point and the horizontal branch (HB), ${\Delta}V_{to}=3.1{\sim}3.4(<{\Delta}V_{to}>=3.32)$, the color of the blue edge of RR Lyrae gap, $(B-V)_{BE}=0.17{\sim}0.21=(<(B-V)_{BE}>=0.18),\;[\frac{m}{L}]_{RR}=-1.7{\sim}-1.9$, mass difference of $m_{RR}$ relative to $m_{RG},(m_{RG}-m_{RR})/m_{RG}=0.0{\sim}0.39$. It was found that the ranges of derived parameters agree reasonably well with the observed ones and those estimated by others. Some important results obtained herein can be summarized as follows; (i) There are considerable variations in the initial helium abundance and in age of globular clusters. (ii) The radial gradient of heavy element abundance does exist for globular clusters as shown by Janes for field stars and open clusters. (iii) The helium abundance seems to have been increased with age by massive star evolution after a considerable amount (Y>0.2) of helium had been attained by the Big-Bang nucleosynthesis, but there is not seen a radial gradient of helium abundance. (iv) A considerable amount of heavy elements ($Z{\sim}10{-3}$) might have been formed in the inner halo ($r_{GC}$<10 kpc) from the earliest galactic co1lapse, and then the heavy element abundance has been slowly enriched towards the galactic center and disk, establishing the radial gradient of heavy element abundance. (v) The final galactic disk formation might have taken much longer by about a half of the galactic age than the halo formation, supporting a slow, inhomogeneous co1lapse model of Larson. (vi) Of the three principal parameters controlling the morphology of C-M diagrams, it was found that the first parameter is heavy clement abundance, the second age and the third helium abundance. (vii) The globular clusters can be divided into three different groups, AI, BI and CII according to Z, Y an d age as well as Dickens' HB types. BI group clusters of HB types 4 and 5 like M 3 and NGC 7006 are the oldest and have the lowest helium abundance of the three groups. And also they appear in the inner halo. On the other hand, the youngest AI clusters have the highest Z and Y, and appear in the innermost halo region and in the disk. (viii) From the result of the clean separations of the clusters into three groups, a three dimensional classification with three parameters, Z, Y and age is prsented. (ix) The anomalous C-M diagrams can be expalined in terms of the three principal parameters. That is, the anomaly of NGC 362 and NGC 7006 is accounted for by the smaller age of the order of $1{\sim}2{\times}10^9$ years rather than by the helium abundance difference, compared with M 3. (x) The difference in two Oosterhoff types I and II can be explained in terms of the mean mass difference of RR Lyrae variables rather than in terms of the helium abundance difference as suggested by Stobie. The mean mass of the variables in Oosterhoff type I clusters is smaller by $0.074m_{\odot}$ which is exactly consistent with Rood's estimate. Since it was found that the mean mass of RR Lyrae stars increases with decreasing Z, the two Oosterhoff types can be explained substantially by the metal abundance difference; the type II has Z<$3.4{\times}10^{-4}$, and the type I has higher Z than the type II.

• Tuberculosis and Respiratory Diseases
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• v.46 no.4
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• pp.473-480
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• 1999

Background: Early diagnosis of tuberculosis is critical, especially in Korea, an area where tuberculosis is endemic. Because antibody responses to some membrane proteins of Mycobacterium tuberculosis are not comparable, and the policy of BCG vaccination and the prevalence of tuberculosis are different from country to country, the usefulness of the serological diagnostic tests is questionable in Korea, even though they have been confirmed to be useful in other countries. In the specific context of Korea, we tried to evaluate the validity of the ICT Tuberculosis Test (ICT), a membrane-based antibody kit that purports to detect the 5 M. tuberculosis complex-specific antigens including 38-kDa protein. Method: 68 patients with tuberculosis were tested : 37 had no history of previous tuberculosis, and 31 were reactivated cases. The control group comprised 77 subjects : 25 healthy adults, 35 hospital workers with frequent contact with tuberculosis patients, and 17 in-patients with non-tuberculous respiratory diseases. Results: The diagnostic sensitivities of the ICT were 87% and 73% in patients with versus without previous history of tuberculosis, respectively. The sensitivities of smear-positive and smear-negative patient groups were 81% and 73%, respectively. Both of the two patients with extrapulmonary tuberculosis tested positive through the ICT. The specificities of the ICT were 88%, 94%, and 94% in healthy adults, hospital workers, and non-tuberculous patients, respectively, with an overall specificity of 92%. Conclusion: It is suggested that when combined with traditional techniques, the ICT is an useful tool for the diagnosis of pulmonary tuberculosis. The procedure is simple, easy to perform, rapid, and needs no equipment. It shows 73% sensitivity and 92% specificity for the diagnosis of tuberculosis.

• Tuberculosis and Respiratory Diseases
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• v.46 no.4
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• pp.481-488
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• 1999

Background: The routine application of the combined regimen of corticosteroid-antituberculosis therapy to the tuberculous pleurisy remains controversial. Steroid therapy to tuberculous pleurisy could be effective on the acceleration of absorption of pleural effusion and symptom improvement, but there has been debate about the effect of prednisolone on the prevention of pleural adhesion. So we studied the efficacy of combined regimen of prednisolone-antituberculosis therapy on the absorption of pleural effusion and prevention of pleural adhesion. Method: A prospective, randomized study was performed in 82 patients, 50 patients(non-steroid group) were treated with only antituberculosis regimen for 6 months and in 32 patients(steroid group) prednisolone(30mg/day) were administered in addition to antituberculosis regimen for one months and tapered for another month. The amount of pleural effusion was compared at the beginning of treatment, 2nd month, 6th month and final visit with chest X-ray findings which were graded from grade 0(complete absorption) to grade 6(near total haziness). Results: The amount of pleural effusion of steroid group at 2nd month, 6th month and final visit was lesser than that of non-steroid group(P<0.05). The incidence of the complete absorption of the pleural effusion was 3/32(9.4%) in steroid group, 1/50(2%) in non-steroid group at 2nd month after treatment; and 12/32(37.5%) in steroid group, 6/50(12%) in non-steroid group at 6th month after treatment(P<0.05). At final observation, the incidence of residual pleural thickening was 15/32(47%) in steroid group and 37/50(74%) in non-steroid group(P<0.05). No serious side effects were noted during the treatment with prednisolone. Conclusion: The administration of prednisolone in conjunction with antituberculosis chemotherapy improved the absorption of pleural effusion and decreased the residual pleural thickening.

• Tuberculosis and Respiratory Diseases
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• v.64 no.6
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• pp.427-432
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• 2008

Background: A paradoxical response is defined as the radiological and clinical worsening of a previous lesion or the development of new lesion after initial improvement during theprocess of antituberculous treatment. The related factors for the development of a paradoxical response in patients with tuberculous pleurisy are not certain. Methods: We selected patients with tuberculous pleurisy who had been treated for more than 4 months. The changes onthe serial chest X-ray findings before and after treatment were reviewed. Paradoxical responses were regarded as any worsening or development of new lesion at least 2 weeks after the initiation of treatment. The baseline clinical characteristics and laboratory findings of the peripheral blood and pleural fluid were compared between the patients with a paradoxical response and the patients without a paradoxical response. Results: Paradoxical responses appeared in sixteen patients (21%) among the 77 patients.It took a mean of 38.6 days after the treatment and the time to resolve the paradoxical response was a mean of 32.1 days. For the patients with a paradoxical response, the median age was younger (30.5 years vs 39.0 years, respectively) and the lymphocytic percentage of white blood cells in the pleural fluid was higher (82.1% vs 69.6%, respectively) than for the patients without a paradoxical response. Conclusion: The development of a paradoxical response during the treatment of patients with tuberculous pleurisy was not rare and this was related with the age of the patients and the percentage of lymphocytic white blood cells in the pleural fluid.

• Tuberculosis and Respiratory Diseases
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• v.62 no.1
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• pp.19-26
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• 2007

Background: Toxocariasis is a common cause of eosinophilia and eosinophilic lung disease in Korea. We analyzed the characteristics of eosinophilic lung disease in toxocariasis. Method: One hundred and forty one patients with eosinophilia caused by a toxocara larval infection were evaluated from September 1, 2001 through March 30, 2006. The plain chest x-ray, chest CT(computed tomography), and bronchoalveolar larvage(BAL) were examined. A diagnosis of toxocariasis was made by ELISA using that secretory-excretory antigen from the T. canis larvae. Results: Toxocarial eosinophilic lung diseases was diagnosed in 32 out of 141 patients. Ground glass attenuation was the main feature on the CT scans in 23 out of 141 patients (71.9%). Thirteen patients (40.6%) had a random in zonal distribution on CT. Pleural effusion was observed in 9 patients (28.1%). Twenty eight patients (87.5%) complained of respiratory symptoms. Eleven patients (34.4%) had gastrointestinal symptoms and 12 patients (37.5%) had liver infiltration. Conclusions: The most common findings of the chest CT in patients with toxocariasis was a randomly distributed ground grass attenuation. A toxocara infection should be considered in a differential diagnosis of patients who exhibit pulmonary infiltration with eosinophilia in Korea.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.746-751
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• 2002

Fluidized bed combustion is a coal combustion technology that can reduce both SOx and NOx emission; SOx is removed by limestone that is fed into the combustion chamber and the NOx is reduced by low temperature combustion in a fluidized bed combustor and air stepping, but $N_2O$ generation is quite high. $N_2O$ is not only a greenhouse gas but also an agent of ozone destruction in the stratosphere. The calcium oxide(CaO) is known to be a catalyst of $N_2O$ decomposition. This study of $N_2O$ decomposition reaction in fixed bed reactor packed over CaO bed has been conducted. Effects of parameters such as concentration of inlet $N_2O$ gas, reaction temperature, CaO bed height and effect of $CO_2$, NO, $O_2$ gas on the decomposition reaction have been investigated. As a result of the experiment, it has been shown that $N_2O$ decomposition reaction increased with the increasing fixed bed temperature. While conversion of the reaction was decreased with increasing $CO_2$ concentration. Also, under the present of NO, the conversion of $N_2O$ decomposition is decreased. From the result of kinetic study gained the heterogeneous reaction rate on $N_2O$ decomposition. In the case of $N_2O$ decomposition over CaO, heterogeneous reaction rate is. $\frac{d[N_2O]}{dt}=\frac{3.86{\times}10^9{\exp}(-15841/R)K_{N_2O}[N_2O]}{(1+K_{N_2O}[N_2O]+K_{CO_2}[CO_2])}$. In this study, it is found that the calcium oxide is a good catalyst of $N_2O$ decomposition.

• Journal of Aquaculture
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• v.14 no.3
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• pp.181-195
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• 2001

To stabilize the lantern cage culture system of Patinopecten yessoensis(Jay) in the eastern coast of Korean peninsula, optimum conditions such as time of transplantation, rearing density and depth, and time of harvest were identified. During the period from January 1991 to December 1998, the water temperature ranged from 4.7 to 21.4$^{\circ}C$ at 15-30 m depth and 4.9 to 25.7$^{\circ}C$ at the surface; these thermal ranges were within the optimal ranges (5-23$^{\circ}C$) prevailing at 15-30 m depth at surface water. Annual thermal changes indicated that the prevailing temperature during the years 1993 and 1996 was near optimum, but higher during the years 1994, 1997 and 1998, when mass mortality and growth retardation occurred. Salinity (32.0- 34.4$\textperthousand$) and dissolved oxygen (4.14 -8.11 $\mu\textrm{g}$/l) at 15 m depth were well within the optimum ranges. The chlorophyll concentrations (0.06 - 2.73$\mu\textrm{g}$/l) indicated that the study area was oligotrophic, although mass mortality did occur, when chlorophyll concentrations were high, especially in summer. Hence water temperatures and chlorophyll concentration are major factors related to survival and growth of the scallop. In terms of the shell height maximum growth occurred during spring (March-May; 8 - l3$^{\circ}C$) and fall (October-December; 11-l7$^{\circ}C$) in the lantern cage culture. Slow growth was recorded during late winter January-february; less than 7$^{\circ}C$) and mid-summer (August- September; more than 18$^{\circ}C$). Daily growth of shell height and total weight were 0.02∼0.24 mm and -0.07∼0.90 g at the rearing density of 12 individuals per net. Optimal .earing density in the lantern cage (ø50${\times}$20 cm) was 10∼15 individuals with the shell height of 5∼6 cm. The fastest growth rates were observed at 15∼20 m depth; however, it is recommended that 20∼30 m would be optimal. The scallops require 22 months to attain the commercial size of 10 cm shell height and 140 g total weigh, and are best harvested and sold during March-April.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.173-184
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• 2003

Beetles belonging to the families Scolytidae, Platypodidae, Bostrichidae, and Lyctidae intercepted from imported timbers at Busan port were investigated from March 1 to November 30 in 2000. In addition, hosts imported country were examined. A total of 52 species of within 23 genera was intercepted from nineteen species of timbers or logs from fifteen countries. In Scolytidae, 35 species of 16 genera in three subfamilies were identified 12 species in Xyleborus, 6 species in Ips, 3 species in Trypodendron, 2 species in Arixyleborus, and 12 species of all different genera including Alinphagous. Scolytidae were intercepted from 16 species of timbers in 13 genera imported from 11 countries. The highest beetles were intercepted from Malaysian lauan. In Platypodidae, 9 species of one genus (Platypus) were intercepted from 6 species of timbers in 4 genera imported from 6 countries including Australia. The highest numbers were intercepted from Malysian lauan. In Bostrychidae, 5 species of 4 genera in two subfamilies were intercepted from 6 species of timbers in 4 genera imported from four countries. In Lyctidae, Trogoxylon sp., Minthea sp., and Minthea rugicollis were intercepted from 3 species of timbers in 2 genera imported from 3 countries.

• Progress in Medical Physics
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• v.14 no.2
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• pp.131-140
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• 2003

As the importance of accuracy in measurings of 3-D anatomical structures continues to be stressed, an objective and quantitative of assessing image quality and accuracy of 3-D volume-rendered images is required. The purpose of this study was to evaluate the quantitative accuracy of 3-D rendered images obtained with MDCT, scanned at various scanning parameters (scan modes, slice thicknesses and reconstruction slice thickness). Twelve clinically significant points that play an important role for the craniofacial bone in plastic surgery and dentistry were marked on the surface of a dry human skull. The direct distances between the reference points were defined as gold standards to assess the measuring errors of 3-D images. Then, we scanned the specimen with acquisition parameters of 300 mA, In kVp, and 1.0 sec scan time in axial and helical scan modes (pitch 3:1 and 6:1) at 1,25 mm, 2.50 mm, 3.75 mm and 5.00 mm slice thicknesses. We performed 3-D visualizations and distance measurements with volumetric analysis software and statistically evaluated the quantitative accuracy of distance measurements. The accuracy of distance measurements on the 3-D images acquired with 1.25, 2.50, 3,75 and 5.00 mm slice thickness were 48%, 33%, 23%, 14%, respectively, and those of the reconstructed 1.25 mm were 53%, 41%, 43%, 36% respectively. Meanwhile, there were insignificant statistical differences (P-value<0.05) in the accuracy of the distance measurements of 3-D images reconstructed with 1.25 mm thickness. In conclusion, slice thickness, rather than scan mode, influenced the quantitative accuracy of distance measurements in 3-D rendered images with MDCT. The quantitative analysis of distance measurements may be a useful tool for evaluating the accuracy of 3-D rendered images used in diagnosis, surgical planning, and radiotherapeutic treatment.