• Journal of radiological science and technology
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• v.15 no.2
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• pp.25-30
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• 1992

With transmitted dose through chest which has the problem of wide variations in absorption, simple film/screen combination method makes it diffucult to image lung field, mediastinum and retrocardiac areas. In order to overcome this, it is very common to use the high kilovoltage technique in diminishing the differences between high and low contrast. We have been adopting this method at department of diagnostic radiology, Seoul National University Hospital. To compare the image of it with that of low kilovoltage technique, we did radiographic tests using beans on the skin. We marked off into three anatomical categories such as lungs, mediastinum and near diaphragm, then attached a bean on a marked area at random. In order to compare with high and low, we took a radiography of high($120{\sim}140\;kVp$) and low($70{\sim}90\;kVp$) kilovoltage tehchniques, respectively at the same time. We have done experiments 320 cases. We evaluated the results of test in response to sensitivity(true positive) and specificity(true negative). In evaluating, we gave them points from 1 to 5 according to true or false. With given points by a radiologist having much experiences, we could acquire the percentage of sensitivity and specificity. The percentage made us to get the schematic table of ROC curve of those two methods. Consequently, high kilovoltage technique appeared 18% better than low kilovoltage technique for detecting beans with our apparatus.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.7
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• pp.583-591
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• 2018

In this paper, we propose a new deployment test equipment that is characterized for the deployment test of single large solar panel with tape spring hinge. To perform the deployment test on ground, a device that takes gravity compensation into account should be used to create a zero gravity environment similar to that in orbit. We analyzed the advantages and disadvantages of the most commonly used deployment test equipment in the past through simple conceptual design, analysis, and tests to judge whether it is applicable to the deployment of the solar panel to be tested. A dummy frame was proposed to reduce the air drag effect during on-ground test and a self-aligning ball bearing and adjusting screws were applied to the deployment test equipment to solve the alignment problem with the gravity axis. And a horizontal bearing for radial movement applied to compensate for the change of the axis of the tape spring hinge. From these, we solved the problems of the conventional deployment test equipment by developing and verifying the new deployment test equipment characterized for the solar panel to be deployed in this paper.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.2
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• pp.107-114
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• 1989

Model pile pull-out tests have been executed to investigate the characteristics of the critical relative displacement at which the critical pile skin resistance is mobilized. Test result shows that the critical relative displacement is neither constant nor pile size dependent, but it is the most closely related with the magnitude of the critical skin resistance. The empirical relationship between the two quantities has been established. Behavior of centrifuge physical models of skin-resistance-related problems has been investigated on a quantitative basis by a computational method. A pile downdrag problem has been employed as an example of the skin-resistance-related problems. A simple transfer function type method has been developed for the analysis of the downdrag. It is concluded from the analysis that centrifuge physical modeling of skin-resistance-related problems may lead to an erroneous result on an unconservative side, as may have been expected due to the violation of the similarity rule by the quantity of the critical relative displacement.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1726-1733
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• 2015

In order to study the effect of the high-altitude and dusty weather in northwest of China on the corona characteristics of transmission lines, a corona caged based experimental system with sandy and dusty flow condition is numerically investigated and designed. This system overcomes the difficulties caused by harsh environment and offers easy usage for off-site tests. The design parameters are mainly determined by the characteristics of strong sandstorm in northwest region and test requirements. By the comparison of numerical simulation of the particle diffusion in four programs with rectangular or circular air-duct, a practical technology, which introduces swirl to control the particle diffusion length, is obtained. Accordingly, the structure of round air-duct with swirl elbow in inlet and outlet of high level segment is selected as final program. Systems of control and measurement are designed at the same time. Field tuning results show that the test system could ensure the range of sandy and dusty coverage. The wind speed, sandy and dusty concentration could be controlled and meet the requirements of accuracy. The experimental system has many features, such as simple structure, easy to be assembled, disassembled, transported and operated, small space occupied.

• Progress in Medical Physics
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• v.21 no.1
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• pp.42-51
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• 2010

Imaging studies using MRI, PET, and/or MEG have been primary evaluation methods to quantitatively assess cognitive function. Recent advances in computational technology and information technology may allow a novel evaluation methodology to quantitate cognitive function more cost-effectively. In this study, we developed a software package composed of a series of tests to evaluate cognitive ability combined with a user-friendly touch screen input device. This cognitive assessment tool can quantitate concentration, numeric memory, associative memory, topological memory, visual and muscular reaction, and acoustic reaction over a relatively short testing time. We performed an empirical study on eighty normal subjects aged 20 and 59 years old using the developed evaluation methods. Age-related cognitive deterioration after 40 years old was confirmed. There was no difference in cognitive ability between male and female in the same age group. This study demonstrates the feasibility of a simple but effective evaluation software tool to quantitatively assess cognitive ability. This methodology may provide improved accessibility and reduced costs to perform cognitive function studies to compare between various subject groups.

• The Korean Journal of Nuclear Medicine
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• v.16 no.2
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• pp.1-24
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• 1982

Several recent advances in our knowledge of thyroid physiology have broad application to the diagnosis and management of thyroid disorders. For in the thyroid, more than other endocrine organs, pathophysiology can be translated directly into the diagnosis and management of thyroid disease. Graves' disease is a syndrome including goiter with hyperthyroidism, exophthalmos and dermopathy. The pathogenesis of Graves' disease is not yet clearly identified, but various autoantibodies to the thyroid gland and immunopathologic studies indicate that autoimmune processes are involved in the pathogenesis of the disease. The diagnosis and management of Graves' disease are largely dependent on radionuclide techniques as radioimmunoassay, radioactive iodine therapy and so on. Several laboratory tests are also developed to determine the remission of this disase including TRH stimulation test, $T_3$ suppression test and detection of thyroid stimulating immunoglobulins. Autoimmune thyroiditis is almost certainly a primary immunologic disease and the incidence tends to increase recently, mainly due to the application of biopsy technique in thyroid diseases. Thyroid nodules have been a great challenge to physicians because of the possibility of malignancy. But recently, cytologic examination of thyroid aspirate provides a very simple and also reliable diagnostic method in patients with thyroid nodules. In 163 patients with thyroid nodules, only 19.3% was revealed to be malignant. Therefore cytologic examination of thyroid aspirate and thyroid biopsy should be included in the diagnosis of nodular patients prior to surgical intervention. In this paper, a comprehensive review is presented on the pathogenesis, clinical features, laboratory findings and therapeutic modalities of various thyroid diseases on the basis of over 80 researches performed during the past 20 years at radioisotope clinic, Seoul National University Hospital.

• Journal of Korean Society of Transportation
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• v.17 no.5
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• pp.19-32
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• 1999

In this study, the trip characteristics of workers in the city are systematically analyzed. The trip behaviors and socioeconomic characteristics of workers are analyzed using Person Trip Survey Data of 1988 and 1992 in Taegu Metropolitan area. With the results of behavioral analyses, the daily travel pattern of workers is shown as one tour contained two trips and it is relatively simple and stable. Also the rate using the same mode in a day is Presented as high ratio. So, it can be explained that the choice of worker\`s first trip is fixed his/her travel mode for his/her daily travel mode. Based on these analyses, the mode choice model for workers is developed by applying the Multi-nominal Logit Model with the choice set of bus, taxi, and car. The explanatory variables of this model include sex, age, auto, travel time, and cost. Empirical tests of the model show encouraging results. After that, the temporal transferability of the model is examined by the Pairwise t-test and five indexes far the model of 1988 and 1992. The results of examination are satisfied with each significance level of the explanatory variables and five indexes. Therefore. it can be concluded that the temporal transferability of this model developed in this study is resonable.

• Journal of Korean Society of Transportation
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• v.20 no.3
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• pp.69-82
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• 2002

The objective of this study is to evaluate the performance of macroscopic traffic flow models with the analytical and field data. Five candidate models were selected as follows ; Lax Method Model, Upwind Scheme Model, Hilliges'Model, Papageorgiou's Model, and Cell-Transmission Model. In the analytical test scenario, the traffic condition was assumed that could cause the building and dissipation of queue, and each model was compared with analytical solutions and the numerical results. An analytical test indicated that both simple continuum and high order continuum models are able to reproduce queue building and dissipating behavior in a reasonable way A field test has shown that Upwind and Papageorgiou's model show similar performances. Considering the simplicity in model formulation and numerical computation, we firstly recommend Upwind scheme model , and secondly Papageorgiou's model that performed will to represent traffic flow in tests as candidate models for further development of simulation model for Naebu expressway in Seoul.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.05a
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• pp.194-194
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• 2003

The International Agency for Research on Cancer (IARC, 1989) has classified whole diesel exhaust as probably carcinogenic to humans. Diesel exhaust particulate matter (DPM) adsorbs different chemical substances including PAHs and nitroarenes. DPM is emphasized because it is a major component of diesel exhaust, it is suspected of contributing to a health hazard. Diesel exhaust is a complex mixture of carbon particles and associated organics and inorganics, and it is not known what fraction or combination of fractions cause the health effects [cancer effects, noncancer effects (respiratory tract irritation/inflammation and changes in lung function)] that have been observed with exposure to diesel exhaust. In order to identify which chemical classes are responsible for the majority of the observed biological activities, we performed a particular biological/chemical analysis. Respirable particulate matter (PM2.5: <2.5mm) was collected from diesel engine exhaust using a high-volume sampler equipped with a cascade impactor. Particulate oganic matter was extracted by the dichloromethane/sonication method and the crude extract was fractionated according to EPA recommended procedure into seven fractions by acid-base partitioning and silica gel column chromatography. We examined genotoxic potentials of diesel exhaust particulate matter using novel genotoxicity tests, which are rapid, simple and sensitive methods for assessing DNA-damage at the DNA and chromosomal level (comet assay, in vitro MN test and Ames test). Higher genotoxic potency was observed in non polar fractions and several PAHs were detected by GC-MS, such as 1,2,5,6 dibenzanthracene, chrysene, 1,2-benzanthracene, phenanthrene and fluoranthene.

• Korean Journal of Environmental Agriculture
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• v.32 no.2
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• pp.128-135
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• 2013

BACKGROUND: This study was performed to develop a single residue analytical method for new herbicide metazosulfuron in crops. METHODS AND RESULTS: Brown rice, apple, mandarin, Kimchi cabbage and soybean were selected as representative crops, and clean-up system, partition solvent and extraction solvent were optimized. Instrumental limit of quantitation (ILOQ), linearity of calibration curve and method limit of quantitation (MLOQ) were determined based on the chromatography and whole procedures. For recovery tests, brown rice, apple, mandarin, Kimchi cabbage and soybean samples were macerated and fortified with metazosulfuron standard solution at three levels (MLOQ, 10 MLOQ and 100 MLOQ). And then those were extracted with acetonitrile, concentrated, and partitioned with ethyl acetate. Then the extracts were concentrated again and cleaned-up through $NH_2$ (aminopropyl) SPE cartridge with acetone : dichloromethane (1% acetic acid) (20 : 80, v/v) before concentration and analysis with HPLC. CONCLUSION(S): ILOQ of metazosulfuron was 2 ng (S/N${\geq}$10) and good linearity was achieved between 0.05 and 12.5 mg/Kg of metazosulfuron standard solutions, with coefficients of determination of 0.9999. MLOQ was 0.02 mg/Kg. Good recoveries from 74.1 to 116.9% with coefficients of variation (C.V.) of less than 10% were obtained, regardless of sample type, which satisfies the criteria of Korea Food and Drug Administration (KFDA). Those results were reconfirmed with LC-MS (SIM). The method established in this study is simple, economic and efficient to be applied to most of crops as an official and general method for residue analysis of metazosulfuron.