• Progress in Medical Physics
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• v.9 no.4
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• pp.259-266
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• 1998

To achieve the 2D dose distribution around the designed high dose rate Ir-192 source substitution for Co-60 brachytherapy source, we determined the exposure rate constant and tissue attenuation factors as a large depth as a 20 cm from source center. The exposure rate constant is used for apparent activity in designed source with self-absorption and encapsulation steel wall. The tissue dose delivered from the 4401 segments of 2.5 mm in a diameter and 2.5 mm height of disk-type source layer. In the experiments, the tissue attenuation factors include the tissue attenuation and multiple scattering in a medium surrounding the source. The fitted the polynomial regression with 4th order for the tissue attenuation factors are very closed to the experimental measurement data within ${\pm}$1% discrepancy. The Meisberger's constant showed the large uncertainty in large distance from source. The exposure rate constant 4.69 Rcm$^2$/mCi-hr was currently used for determination of apparent activity of source and air kerma strength was obtained 0.973 for tissue absorbed dose from the energy spectrum of Ir-192 source. In our experiments with designed high dose rate brachytherapy source, the apparent activity of Ir-192 source was delivered from the 54.6 % of actual physical source activity through the self-absorption and encapsulation wall attenuations. This paper provides the 2-dimensional dose tabulation from unit apparent activity in a water medium for dose planning includes the multiple scattering, source anisotropy effect and geometric factors.

• Journal of Nutrition and Health
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• v.47 no.5
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• pp.364-373
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• 2014

Purpose: The purpose of this study was to develop a mercury database for food commonly consumed by Koreans. Methods: Target foods for a mercury database were selected from dietary survey data of the 2007-2009 Korean National Health and Nutrition Examination Survey (KNHANES). Data for mercury contents of foods were collected through literature review. Among 702 food items reported by 24 hr dietary recall method, the contents of mercury for 300 food items were selected with systematic evaluation from the literature, which provided analytical values, and those of 56 food items were imputed by using a conversion factor. Results: The mercury database developed in this study covered 50.7% of all kinds of consumed foods and 95.1% of total amount of food intake reported by 2007-2009 KNHANES. In the database, the geometric mean of mercury contents in food items was the highest in the fishes and shellfishes group ($41.13{\mu}g/kg$, n = 101) followed by mushrooms ($18.93{\mu}g/kg$, n = 12) and seaweeds ($5.92{\mu}g/kg$, n = 14), and the lowest in the meats group ($0.15{\mu}g/kg$, n = 17). Conclusion: The developed mercury database can be used to estimate the dietary mercury exposure of Korean people, and the method for development of a mercury database would be helpful to researchers in development of a new database for other food borne hazardous substances.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.117-129
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• 2012

Road safety audit is the preventive enhancement strategy for safety. : it gets rid of beforehand the potential factor of a traffic accident in the stage of road planning and design and it evaluates the appropriation for road geometric structure or safety facility to prevent traffic accident in the stage of operation after the construction. Since this strategy is introduced to our country in the early 2000s, various projects have been processed and it was legislated recently. And now, the evaluation of past project for its continuation is needed. Therefore, in this study the evaluation of road safety audit on existing freeway is performed. The spatial extent of this study is Yong-dong line on which the safety treatment was executed in 2005 and 2006. And, the temporal range of this study is each 2-year of before and after from 2005 and 2006. The empirical bayes method of observational evaluation studies is applied to analyze. As a result, there is an effect of improvement on most of treated sections. But there is ineffective or negligible on some sections. Compared with the detail of treatment on each section, the effect of multiple or various treatments is good for that section. On the other hand, the section on which effect doesn't appear is the result of single or unimportant treatments. Throughout these results, the concrete analysis can be performed and the countermeasures designed for the section on which effect doesn't appear. Also it is used as reference to the future plan and direction of road safety audit on existing freeway.

• The Korean Journal of Nuclear Medicine
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• v.26 no.2
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• pp.307-311
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• 1992

Anorexia, nausea, and vomiting are one of the most frequent symptoms in viral hepatits patients. These may be due to poorly detoxified substances by dysfunctioned hepatocytes or by gastritis, but the pathophysiology is not totally understood. The symptoms interfere with adequate nutrient intake and are managed by metoclopramide, which accelerates gastric emptying. Thus delayed gastric emptying may well be a contributing factor to such symptoms. To determine such a relationship, we measured gastric emptying time in 11 normal subjects,9 acute (AVH), and 12 chronic B viral hepatitis (CVH) patients. All were males with a mean age of 23 years. An egg was labeled with 0.5 mCi of $^{99m}Tc-sulfur$ colloid, fried, then eaten between 2 slices of bread with 100 cc of water. Anterior and posterior images were taken at 20 minute intervals over a 2 hour period. A geometric mean of activity pertaining to the gastric region was measured, and $T_{1/2}$ was calculated from the time activity curve. $T_{1/2}$ for normal the group was $57.8{\pm}6.3$ minutes while that for the AVH and CVH group was $58.2{\pm}8.2$ (p=0.40) and $64.1{\pm}10.5$ (p=0.09), respectively. There was 1 AVH Patient and 4 CVH patients with prolonged $T_{1/2}$. Anorexia and nausea was seen in 71% and 46% of the patients, respectively. 80% and 60% of the patients with prolonged $T_{1/2}$ had anorexia and nausea, respectively.

• Journal of Korean Society for Geospatial Information Science
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• v.1 no.1 s.1
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• pp.141-152
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• 1993

This study aims to generate digital elevation model from digital satellite imagery. Digital elevation model is being increasingly used for geo-spatial information system database development and for digital map production. Image matching technique was applied to acquire conjugate image coordinates and the algorithm for digital elevation model generation is presented in this study The exterior orientation parameters of the satellite imagery is determined by bundle adjustment and standard correlation was applied for image matching conjugate of image points. The window as well as the searching area have to be defined in image matching. Different sizes of searching area were tested to study the appropriate size of the searching area. Various coordinate transformation methods were applied to improve the computation speed as well as the geometric accuracy. The results were then statistically analysed after which the searching area is determined with the safety factor. To evaluate the accuracy of digital elevation model, 3-D coordinates were extracted from 1/5000 scale topographic map and this was compared to the digital elevation model generated from satellite imagery. The algorithm for generation of digital elevation model generated from satellite imagery is presented in this study which will prove effective in the database development of geo-spatial information system and in digital elevation modelling of large areas.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.7-15
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• 2012

Semiconductor packages are increasingly moving toward miniaturization, lighter and multi-functions for mobile application, which requires highly integrated multi-stack package. To meet the industrial demand, the package and silicon chip become thinner, and ultra-thin packages will show serious reliability problems such as warpage, crack and other failures. These problems are mainly caused by the mismatch of various package materials and geometric dimensions. In this study we perform the numerical analysis of the warpage deformation and thermal stress of 4-layer stacked FBGA package after EMC molding and reflow process, respectively. After EMC molding and reflow process, the package exhibits the different warpage characteristics due to the temperature-dependent material properties. Key material properties which affect the warpage of package are investigated such as the elastic moduli and CTEs of EMC and PCB. It is found that CTE of EMC material is the dominant factor which controls the warpage. The results of RSM optimization of the material properties demonstrate that warpage can be reduced by $28{\mu}m$. As the silicon die becomes thinner, the maximum stress of each die is increased. In particular, the stress of the top die is substantially increased at the outer edge of the die. This stress concentration will lead to the failure of the package. Therefore, proper selection of package material and structural design are essential for the ultra-thin die packages.

• Polymer(Korea)
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• v.26 no.5
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• pp.691-700
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• 2002

Interstitial therapy using biodegradable polymeric device loaded with anticancer agent can deliver the drug to the tumor site at high concentration, resulting in an increase of therapeutic efficacy. 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, carmustine) is most commonly used as chemotherapeutic agent for brain tumors. The design of implantable device is regarded as an important factor lot the efficient delivery of antitumor agent to targeting site. In order to control the release profile of drug, the release pattern of BCNU with the changes of various dimension and additives was investigated. The PLGA wafers containing 3.85, 10, 20 and 30% of BCNU were prepared in various shape (diameter of 3, 5 and 10 mm, thickness of 0.5, 1 and 2 mm) by direct compression method. In vitro drug release profile of BCNU-loaded PLGA wafers could be controlled by changing the dimension of wafers such as initial drug content, weight, diameter, thickness, volume and surface area of wafers, as well as PLGA molecular weight and additives. Drug release from BCNU-loaded PLGA wafers was facilitated with an increase of BCNU-loading amount or presence of poly(N-vinylpyrrolidone)(PVP) or sodium chloride (NaCl). The effects of various geometric factors and additives on the BCNU release pattern were confirmed by the investigation of mass loss and morphology of BCNU-loaded PLGA wafers.

• Cross-Cultural Studies
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• v.49
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• pp.229-248
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• 2017

This paper is a study on French of Lee Sang's poems called metaphysical scandals in Korean poetry. Is poetic language he used a common poetic word or a non-poetic word in French? What kind of harmony do words and sentences composed of French have with Korean, Chinese character, and non-poetic word? Based on these questions, we analyzed a command of French, that is symbolic, geometrical, and pictorial French as well as repetitive and parallel constitution used in form of words and sentences. In Lee Sang's poems, as a result, the use of French is seen as a mixture of non-poetic word. It shows characteristics that reject traditional native language and the creation of poetry. In his poems, French is also an important factor of avant-garde poetic material and experimental creation technique. In his poems, French is used as a special tool to express internal conflicts of the poet. Lee Sang showed experimental style that could not be found in modern Korean literature by using signifier and signifed that french language has.

• Journal of the Korean GEO-environmental Society
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• v.23 no.2
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• pp.25-36
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• 2022

In this study, seepage control effect of relief well was evaluated quantitatively on embankment of small fill dam and levee. Seepage analysis of dam and levee were carried out according to the permeability of fill material and foundation and to analyze behaviour characteristics of seepage. The up-lift pressure at toe of embankment was analyzed which is generated by seepage according to relief well installation condition. The relief well could reduce pore water pressure which is to cause piping or up-lift pressure at foundation ground of embankment and it does not be influenced on geometric condition such as dam height and slope incline. In case of relative low permeable ground, the pore water pressure reduction effect of relief well was decreased compare with high permeable ground but it shows pore water pressure reduction effect compare with no relief well condition. The reduction effect of relief well shows relative gap according to diameter and penetration length of relief well and the installation length of relief well is the most effective factor for seepage control.

• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.59-67
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• 2006

The centrifuge and 1-g shaking table tests were performed simultaneously to compare the dynamic behaviors of loose sands of the same geotechnical properties. The prototype soils were 10 m thick liquefiable loose sands. The geometric scaling factors were 20 for 1-g and 40 for centrifuge tests. The excess pore pressure, surface settlement, and acceleration in the soil were measured at the same locations in the 1-g and centrifuge tests. The total excess pore pressure from development to dissipation was measured. In the centrifuge test, viscous fluid was used as the pore water to eliminate the time scaling difference between dynamic time and dissipation time. In the 1-g tests, the steady state concept was applied to determine the unit weight of the model soil, and two different time scaling factors were applied for the dynamic time and the dissipation time. It is concluded that the 1-g tests can simulate the excess pore pressure of the prototype soil if the permeability of the model soil is small enough to prevent dissipation of excess pore pressure during shaking and the dissipation time scaling factor is properly determined.