• The Journal of Korean Society for Radiation Therapy
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• v.24 no.2
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• pp.107-114
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• 2012

Purpose: Unlike the existing linear accelerator with photon, proton therapy produces a number of second radiation due to the kinds of nuclide including neutron that is produced from the interaction with matter, and more attention must be paid on the exposure level of radiation workers for this reason. Therefore, thermoluminescence dosimeter (TLD) that is being widely used to measure radiation was utilized to analyze the exposure level of the radiation workers and propose a basic data about the radiation exposure level during the proton therapy. Materials and Methods: The subjects were radiation workers who worked at the proton therapy center of National Cancer Center and TLD Badge was used to compare the measured data of exposure level. In order to check the dispersion of exposure dose on body parts from the second radiation coming out surrounding the beam line of proton, TLD (width and length: 3 mm each) was attached to on the body spots (lateral canthi, neck, nipples, umbilicus, back, wrists) and retained them for 8 working hours, and the average data was obtained after measuring them for 80 hours. Moreover, in order to look into the dispersion of spatial exposure in the treatment room, TLD was attached on the snout, PPS (Patient Positioning System), Pendant, block closet, DIPS (Digital Image Positioning System), Console, doors and measured its exposure dose level during the working hours per day. Results: As a result of measuring exposure level of TLD Badge of radiation workers, quarterly average was 0.174 mSv, yearly average was 0.543 mSv, and after measuring the exposure level of body spots, it showed that the highest exposed body spot was neck and the lowest exposed body spot was back (the middle point of a line connecting both scapula superior angles). Investigation into the spatial exposure according to the workers' movement revealed that the exposure level was highest near the snout and as the distance becomes distant, it went lower. Conclusion: Even a small amount of exposure will eventually increase cumulative dose and exposure dose on a specific body part can bring health risks if one works in a same location for a long period. Therefore, radiation workers must thoroughly manage exposure dose and try their best to minimize it according to ALARA (As Low As Reasonably Achievable) as the International Commission on Radiological Protection (ICRP) recommends.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.754-760
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• 1999

The properties of the catalyst for a direct internal reforming type molten carbonate fuel cell were examined by ICP, BET, CHN, EDS, and $H_2$ chemisorption. Potassium and lithium, the components of carbonate electrolyte, were transported to the catalyst during the operation of fuel cell, and the amounts of the deposited alkali elements were reduced in the order of inlet, outlet, and the middle. From the direct correlation between the amount of alkali and the physical properties such as BET surface area and Ni dispersion, and from the observation of the lump of the alkali species on the poisoned catalyst, it was confirmed that the physical blocking of the catalyst by alkali deposition was the main reason for the deactivation. Although the amount of alkali species was greater at the inlet than at the oulet, the catalyst sampled from the outlet had lower activity. This was caused by the chemical interaction between the alkali species and the catalyst at the outlet where temperature was highest in the cell body, which was detected by FT-IR analyses.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.23-28
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• 2015

Lacquer sap extracted from lacquer trees exhibits good thermal stabilities and antimicrobial properties. To apply these superior properties to functional packaging, polyurushiol (YPUOH) powders were prepared and blended into LDPE (low density polyethylene) to prepare three different LDPE/YPUOH composite films via a twin screw extruder system. Their morphology, thermal and antimicrobial properties as well as barrier properties of the LDPE/YPUOH composite films were thoroughly investigated to find out applicablities of the films as functional packaging materials. Although the interfacial interaction between LDPE and YPUOH was relatively weak, LDPE/YPUOH composite films exhibited good dispersion of YPUOH in LDPE, resulting in the enhanced thermal stability with YPUOH loading. Due to the good antibacterial property of as-prepared YPUOH, LDPE/YUOH composite films also showed an excellent antibacterial activity (R) of 99.9% against E. coli. Furthermore, the moisture barrier property of LDPE/YPUOH composite films increased with increasing YPUOH contents. Incorporating the relatively low amount of YPUOH in LDPE resulted in the apparent enhancement in thermal stabilities, antibacterial and moisture barrier properties, which made them promising candidates as a functional filler for packaging materials.

• 한국해양학회지
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• v.30 no.6
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• pp.565-583
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• 1995

We have used a nonlinear quasi-geostrophic model to study effects of lateral friction and bottom topography on the motion of warm eddies. The two empirical orthogonal functions of the stream function, accounting for the vertical structure, represent the barotropic and first baroclinic dynamic modes. This model is integrated 360 days on a 1000 km ${\times}$ 1000 km domain with a resolution of 10 km ${\times}$ 10 km including both the thermocline and idealized topography of the East Sea. Prescribed inflow through the Korea Strait is compensated by outflow through the Tsugaru Strait. The balance between the nonlinear advection term and the planetary ${\beta}$-effect tends to make northward movement of warm eddy over a flat bottom. The motion of a warm eddy over a sloping topography can be dominated by the nonlinear advection, while nonlinearity plays a secondary role over a flat topography. For eddies dispersing over topography, the nonlinear tendency is a function of time. For a strong warm eddy, northward propagation can occur. For intermediate strength of eddies one might expect a balance between the nonlinear term and the topographic ${\beta}$-effect. As nonlinearity decreases with eddy dispersion, southward motion along the slope may occur by such as a topographic Rossby wave. Our numerical simulations have confirmed the importance of lateral friction on eddy motions, in such a way that the northward penetration of the warm eddy increases drastically by the decrease of the lateral friction. The northward motion of warm eddy can be prevented by reducing the Reynolds number sufficiently. We have also demonstrated the crucial role of topographic effects in the eddy motion process.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.742-750
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• 2020

The flow noise generated by hull appendages is directly related to the performance of the sonar in terms of self-noise and induces a secondary noise source through interaction with the propeller and rudder. Thus, the noise in the near field should be analyzed accurately. However, the acoustic analogy method is an indirect method that is not used to simulate the propagation of an acoustic signal directly; therefore, diffraction, reflection, and scattering characteristics cannot be considered, and near-field analysis is limited. In this study, the propagation process of flow noise in water was directly simulated by using the lattice Boltzmann method. The lattice Boltzmann method could be used to analyze flow noise by simulating the collision and streaming processes of molecules, and it is suitable for noise analysis because of its compressibility, low dissipation rate, and low dispersion rate characteristics. The flow noise source was derived using Reynolds-averaged Navier-Stokes equations for the hull appendages, and the propagation process of the flow noise was directly simulated using the lattice Boltzmann method by applying the developed flow-acoustic boundary conditions. The derived results were compared with Ffowcs Williams-Hawkings results and hydrodynamic pressure results based on the receiver location to verify the usefulness of the lattice Boltzmann method within the near-field range in comparison with other techniques.

• Journal of Pharmaceutical Investigation
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• v.31 no.3
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• pp.151-160
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• 2001

The purpose of this study is to investigate the interaction of progesterone with various cyclodextrins (CDs) in the aqueous solution and in solid state, and finally to formulate a parenteral aqueous formulation. CDs used were ${\alpha}-$, ${\beta}-$, and ${\gamma}-CD$, $2-hydroxypropyl-{\beta}-CD$ (HPCD), sulfobutyl $ether-{\beta}-CD$ (SBCD), $dimethyl-{\beta}-CD$ (DMCD) and $trimethyl-{\beta}-CD$ (TMCD). The solubility studies of progesterone were performed in the presence of various CDs as a function of concentration or temperature. The solubility of progesterone increased in the rank order of ${\alpha}-CD$ < ${\beta}-CD$ < ${\gamma}-CD$ < TMCD$ < HPCD < DMCD < SBCD. Addition of SBCD (200 mg/ml) in water increased the aqueous solubility $(9.36\;{\mu}g/ml)$ about 3,200 times, and lowering the temperature facilitated the solubilization of progesterone. However, the addition of HPCD and SBCD in 20:80 (v/v) polyethylene glycol 300-water and propylene glycol-water cosolvents markedly decreased the solubility of progesterone, compared with solubilizing effects in water. Physical mixtures and solid dispersions of progesterone with HPCD or SBCD were prepared, and evaluated by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), near IR spectroscopy and dissolution studies. By DSC and IR studies, it was found that progesterone was dispersed in HPCD in monotectic state and dissolved rapidly from both solid dispersions. Based on solubility studies, new aqueous progesterone fonnulations (5 mg/ml) containing SBCD (200 mg/ml) could be prepared and did not form precipitates even after 2 months at $4^{\circ}C$. The solution was transparent when mixed with normal saline and 5% dextrose injection at 1: 1, 1:10 and 1:20 (v/v) even after 7 days. Permeation rates of progesterone through a cellulose membrane from 20% PEG 300 solution $(50\;{\mu}g/ml)$ containing HPCD or SBCD were compared with oily formulation. Permeation of progesterone from oily formulation did not occur up to 8 hr, but aqueous formulations showed fast permeation rates from early stage of permeation study. The addition of HPCD or SBCD retarded the permeation rates of progesterone with the increase of CD concentrations, suggesting the possibility of a controlled absorption from the site administered intramuscularly. These results demonstrate that it is feasible to develop a new progesterone parenteral aqueous injection (5 mg/ml) using SBCD.

• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.562-584
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• 2004

This paper intends to identify the structure of homogeneous regions and functional regions in Seoul based on B.J.L. Berry's ‘general field theory of spatial behavior’. The structure of homogeneous regions by using socio-economic variables can explain how the structural elements of the city are arranged. It can be ssid that Seoul has shifted towards more complicated and differentiated features in terms of homogeneous regions. The different patterns are found between the northern part to Han River where old torn areas are located and the southern part to Han River where newly urbanized areas are located. Usually, the concentric pattern and the sectoral pattern coexist, which is enhanced moving from CBD to the outskirt area. The distribution of different social classes shows irregular pattern similar to the variation of living environment. The social gap is expected to be more widening between new towns and old towns. The analysis of spatial movement pattern shows no clear hierarchical order because of current shifts towards both multi-nuclear pattern and spatial dispersion. The functional regions show duplicated structure overlapping their boundaries each other. The ‘general field theory of spatial behavior’ strongly suggests that spatial interactions among sub-areas in the city are differentiated from the basic characteristics and function of each sub-area. The attributes of homogeneous regions and functional regions are interrelated in the characteristics of isomorphic nature.

• The Journal of the Korea Contents Association
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• v.10 no.3
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• pp.294-300
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• 2010

With the development of media technology, UCC actively working through the medium of the Net, the Internet space, which can influence politics instead of TV is drawing attention as the new leading media. As the one-sided media influence of TV is dwindling in the times of the Internet, the hegemony of the media is rapidly changing into UCC marked by two-way interaction. Especially, UCC has the characteristic that it has changed the people performing a role as the receptor of the media into the agent of enormous political influence as well as the freshness specific to its contents. This study was intended to investigate the types of diverse political influences of UCC in political practice as well as daily politics with a focus on the fact that it can newly project the world led by the media and their changes and exercise strong power in changing the society. Therefore, it attempted to investigate the political influence and ripple effect that UCC can exert by attempting to analyze what political influence UCC can exercise at diverse political situations including election. As a result, UCC led to four situations such as incentive-exploding type, issue-leading type, dispersion-switching type, direction-obeying type. This can be said to lead to the positive effect at the political field, such as implementing direct democracy through digital technology.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.4
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• pp.415-430
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• 1996

Spatio-temporal variations in zooplankton community and ropepod indicator species were investigated along with the interaction between zooplankton distribution and environmental factors in Chinhae Bay. Zooplankton samples were monthly collected at 7 stations from February to September in 1993. A NORPAC net was vertically hauled from bottom to surface, At the same station, environmental factors such as temperature, salinity and COD (chemical oxygen demand) were measured at two different water layers, surface and bottom. In August and September, salinity declined below 30.00‰ , while eutrophic parameters such as COD showed the higher concentrations than those in other months, with higher concentrations at inner bay stations. Salinities were, however, higher at bay mouth areas. These distributional patterns were believed to be caused by input and dispersion of organic matters from nearby land. Zooplankton communities were composed of 7~14. Of these, Noctiluca scintillans was predominant and occupied 90.6‰ of total zooplankton abundance. Cladocera and Copepoda were secondly abundant taxa. Among 6 to 10 copepod species appeared, Acartia omorii and A. hudsonics were most common species during the survey months except March and September. Species diversities were greater, in general, at inner bay than outer bay. The lowest diversity index was observed in February, while the highest in July. Cluster analysis could divide the study area into 2 or 4 zones for each month. Zone 1, mouth area of the bay, was characterized by the influence of offshore waters. Zone II was mixing area. Zone III and IV seemed to be affected by nearby land.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.307-316
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• 2019

In the agricultural sector, greenhouse gas emissions vary depending on the interaction of all ecosystem changes such as soil environment, weather environment, crop growth, and anthropogenic farming activities. Agricultural sector greenhouse gas emissions resulting from many of these interactions are highly variable. Uncertainty-based evaluation that defines the interval with confidence level of greenhouse gas emission and absorption is necessary to take account of the variance characteristics of individual emissions, but research on uncertainty evaluation method is insufficient. This study aims to decide on the effect of reducing N₂O emissions from upland soils using an uncertainty-based approach. An uncertainty-based approach confirmed whether there was a difference between confidence intervals in the 5 different fertilizer treatment groups to reduce greenhouse gas emissions. Unlike the statistically significant test with three repetition averages, the uncertainty-based approach method estimated in this study is able to estimate the confidence interval considering the distribution characteristics of the emissions, such as the dispersion characteristics of individual emissions. Therefore, it is considered that the reliability of emissions can be improved by statistically testing the variance characteristics of emissions such as the uncertainty-based approach. It is hoped that the direction of the uncertainty-based approach for the effect of reducing greenhouse gas emissions in agriculture will be helpful in the future development of agricultural greenhouse gas emission reduction technology, adaptation to climate change, and further development of sustainable eco-social system.