• Korean Journal of Agricultural Science
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• v.14 no.1
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• pp.81-97
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• 1987

Two nozzles with different size (Figure 2) were particularly designed to supply air through the swirl core into the central part of the liquid stream in the same parallel direction to produce a well-mixed air and water in the whirl chamber as spray liquid in bubble formation. Atomization was attempted to improve by using both the preliminary break-up process with less viscosity and less surface tension in the whirl chamber and the effects of increased frequency of the band of drops with the raised ambient air density in front of the nozzle orifice. The volumetric ratio between spray liquid and air on four levels was used to investigate the effects of air as a component of the mixture on atomization. The results of the experiment were summarized as follows; Droplet size became progressively finer as the operating pressure was increased in the range of $0.70kg/cm^2$ to $6.33kg/cm^2$, which was similar to the previous works. The new atomizing mechanism so-called 'air-center nozzle' gave a narrower range in droplet size distribution with smaller volumetric median diameter (VMD) than that of the existing spray system at a given pressure, which showed the possibility of improvement of atomization in a certain limit. The volumetric median diameter produced by the new atomizing mechanism was decreased from the central region toward the exterior edges across the spray pattern.

• Journal of Yeungnam Medical Science
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• v.9 no.2
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• pp.351-358
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• 1992

Hepatocellular carcinoma represents approximately 90% of the primary liver cancers. Recently, its incidence tends to be increased. Thirty seven cases from 1986 to 1991 diagnosed as hepatocellular carcinoma by resection were analized to know their histopathologic features and related clinical findings. The average age at the time of resection was 53.1 years, with frequent occurrence in third and fourth decades. Microscopically, the trabecular type was the most frequent growth pattern(35.1%) and classic hepatocyte-like cell type was the most frequent cell type(75.7%). The tumors are mainly moderately differentiated and frequently associated with liver cirrhosis. In comparison of cytologic differentiation with liver cirrhosis, there was a tendency for well-differentiated tumors to arise in cirrhotic livers more often than poorly differentiated tumors, and the tendency was statistically significant. But differentiation and tumor size did not show significant correlation. Also statistically significant correlation were not observed between the level of alpha-fetoprotein and tumor size, and between the level of alpha-fetoprotein and differentiation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.505-512
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• 2021

A 3D model was developed to calculate the UV intensity of a submerged-type UV disinfection reactor. Numerical experiments were conducted by inputting the design factors of an open channel-type disinfection reactor and a pipe-type disinfection reactor that were installed in an actual sewage treatment plant. The following data were obtained: The average UV intensity of the installed open channel-type reactor and pipe-type reactor was 7.87 mW/cm² and 13.09 mW/cm², respectively; the UV dose reflecting the UV irradiation time and taking into account attenuation effects such as mixing imbalance, lamp aging, temperature, and fouling, was expected to be 21.1 mJ/cm² and 24.8 mJ/cm², respectively, and these values are 5 % and 24 % higher than the target UV dose of 20 mJ/cm², respectively. By using the UV3D model, the optimal lamp position, which maximizes the average UV intensity without changing the size of the disinfection reactor or lamp output power, can be found. In this case, by only adjusting the lamp position, the average UV intensity can be increased by 0.9 % for the open channel-type and 0.5 % for the pipe-type, respectively. A better average UV intensity can be obtained by model simulation. By adjusting the horizontal and vertical ratio of the open channel-type reactor and by moving the lamp position, the average UV intensity can be increased by 7.4 % more than the present case.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.30 no.1
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• pp.77-99
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• 2019

In this study, development directions for smooth introduction of transferring non-specialized libraries to specialized libraries are suggested based on the analysis conducted on non-specialized library librarians and users to investigate and analyze the comparative requirements for specializing libraries, specialization topics, demand for spaces and programs for specialization and view of important factors of each area when operating specialized libraries in future. As a result, first, when introducing a specialized library, it is necessary to derive a specialized topic that can identify and provide the characteristics of the region and the status of existing library. And a demand analysis. Based on this, the subject should be selected through the demand survey of the local residents. Second, from the stand point of targeted subjects of specialized service, it is necessary to provide tailored services by understanding the service range for each age group based on local population distribution and library user analysis. Third, experience-type, lecture-type and view-type can be suggested for specialized programs, considering the characteristics of the specialized subject field. It is ideal to operate combination of the three based on the subject filed details. Also, the characteristics of the subject and the types of program should be considered for specialized spaces. Finally, in order to systematically operate and promote specialized libraries, allocating dedicated personnel, linking with other institutions and strategies of promotion and marketing should be considered.

• Land and Housing Review
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• v.14 no.3
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• pp.93-106
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• 2023

This study attempted to simulate changes in the thermal environment according to the type of apartment complex in Korea using CFD techniques and evaluate the thermal environment by type of apartment. First, apartment complex types in the 2000s and 2010s were referred from previous studies and four types of apartment complex were extracted from. Second, the layout of the apartment complex and temperature changes were analyzed by the direction of wind inflow. Third, a standardized model was created from each type using tower type, plate type, and mixed driving. Last, CFD simulations were performed by setting up the inflow of wind from a total of eight directions. The temperature was relatively low in the type consisting of only the tower type and the type of placing the tower type in the center of the complex, regardless of the direction of the wind. It was due to the good inflow of wind from these types to the inside of the complex. It can be interpreted because wind flows easily into the complex in these types. The findings showed that wind flow and resulting temperature distribution patterns differed depending on the building type and complex layout type, confirming the need for careful consideration of the complex layout in the early design stage. The results are expected to be used as basic data for creating a sustainable residential environment in the early design stage of apartment complexes in the future.

• 한국해양학회지
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• v.24 no.3
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• pp.132-147
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• 1989

A total of 83 surface sediments and 55 sea water samples, collected from the southwestern sea of Cheju Island, were analyzed in order to understand their textural characteristics, geochemical composition and the clay mineralogical features. The sediments were subdivided into ten textural classes, namely clayey sand, slightly gravelly muddy sand, sandy clay, clay and mud. The coarse and fine-grained mixed sediments are distributed in the northern part and around the Island, whereas the fine-grained deposits are mainly distributed in the central and southern parts of the study area; small scale mud patches are distributed in the southwestern and northern parts of Cheju Island. The high concentration of total suspended matter in study area gradually increase toward the southwestern and northwestern offshore area. The concentration of geochemical elements is as follow: the content of Mn, Al, Zn, Cr, Cu and Sn increase toward the southern part which is covered mainly with fine-grained deoposits, whereas the content of Ca, Mg and Ag is higher in the northern area; the elements such as Ni, Na, Fe and Pb are more concentrated relatively in muddy deposits rather than in sandy sediments. The light minerals such as Na-Ca feldspars show a high content around the Socotra Rock, toward the Soheugsan and Cheju Islands, but the K-feldspars are relatively high around the Cheju Island. It was noticed that the provenance of these sediments is partly influenced by the geological characteristics near the island. X-ray diffractogram for clay minerals from the southeastern mud patch and around the Soheugsan Island shows the diagnostic calcite peak indicating that the greater part of these clay fraction may have been derived from present and ancient Hwangho River. The high concentration of smectite in the northern part near the Cheju and around the Soheugsan Islands, eastern side of Socotra Rock probably result from supplies smectite altered from volcanic materials distributed in the Cheju Island and Socotra Rock, whereas the samples near the Chuja and northern parts of the Cheju Island contain weak calcite peak and high concentration of kaolinite and chlorite which is closely related to the geolgical characteristics on the adjacenting land area.

• Proceedings of the KACD Conference
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• 2008.05a
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• pp.246-257
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• 2008

The purpose of this study was to investigate the influence of various occlusal loading sites and directions on the stress distribution of the cervical composite resin restorations of maxillary second premolar, using 3 dimensional (3D) finite element (FE) analysis. Extracted maxillary second premolar was scanned serially with Micro-CT (SkyScan1072; SkyScan, Aartselaar, Belgium). The 3D images were processed by 3D-DOCTOR (Able Software Co., Lexington, MA, USA). HyperMesh (Altair Engineering. Inc., Troy, USA) and ANSYS (Swanson Analysis Systems. Inc., Houston, USA) was used to mesh and analyze 3D FE model. Notch shaped cavity was filled with hybrid (Z100, 3M Dental Products, St. Paul, MN, USA) or flowable resin (Tetric Flow, Viva dent Ets., FL-9494-Schaan, Liechtenstein) and each restoration was simulated with adhesive layer thickness ($40{\mu}m$). A static load of 200 N was applied on the three points of the buccal incline of the palatal cusp and oriented in $20^{\circ}$ increments, from vertical (long axis of the tooth) to oblique $40^{\circ}$ direction towards the buccal. The maximum principal stresses in the occlusal and cervical cavosurface margin and vertical section of buccal surfaces of notch-shaped class V cavity were analyzed using ANSYS. As the angle of loading direction increased, tensile stress increased. Loading site had little effect on it. Under same loading condition. Tetric Flow showed relatively lower stress than Z100 overall, except both point angles. Loading direction and the elastic modulus of restorative material seem to be important factor on the cervical restoration.

• Restorative Dentistry and Endodontics
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• v.33 no.3
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• pp.246-257
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• 2008

The purpose of this study was to investigate the influence of various occlusal loading sites and directions on the stress distribution of the cervical composite resin restorations of maxillary second premolar, using 3 dimensional (3D) finite element (FE) analysis. Extracted maxillary second premolar was scanned serially with Micro-CT (SkyScan1072; SkyScan, Aartselaar, Belgium). The 3D images were processed by 3D-DOCTOR (Able Software Co., Lexington, MA, USA). HyperMesh (Altair Engineering, Inc., Troy, USA) and ANSYS (Swanson Analysis Systems, Inc., Houston, USA) was used to mesh and analyze 3D FE model. Notch shaped cavity was filled with hybrid (Z100, 3M Dental Products, St. Paul, MN, USA) or flowable resin (Tetric Flow, Vivadent Ets., FL-9494-Schaan, Liechtenstein) and each restoration was simulated with adhesive layer thickness ($40{\mu}m$). A static load of 200 N was applied on the three points of the buccal incline of the palatal cusp and oriented in $20^{\circ}$ increments, from vertical (long axis of the tooth) to oblique $40^{\circ}$ direction towards the buccal. The maximum principal stresses in the occlusal and cervical cavosurface margin and vertical section of buccal surfaces of notch-shaped class V cavity were analyzed using ANSYS. As the angle of loading direction increased, tensile stress increased. Loading site had little effect on it. Under same loading condition, Tetric Flow showed relatively lower stress than Z100 overall, except both point angles. Loading direction and the elastic modulus of restorative material seem to be important factor on the cervical restoration.

• The Journal of Engineering Geology
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• v.19 no.4
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• pp.529-541
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• 2009

Hydrochemical, stable isotopic ($\delta^{18}O$ and dD) and noble gas isotopic analyses of seven hot spring water samples, eleven groundwater samples and six surface water samples collected from the Icheon and Pocheon area were carried out to find out hydrochemical characteristics, and to interpret the source of noble gases and the geochemical evolution of the hot spring waters. The hot spring waters show low temperature type ranging from 21.5 to $31.4^{\circ}C$ and the pH value between 6.69 and 9.21. Electrical conductivity of hot spring waters has the range from 310 to $735\;{\mu}S/cm$. Whereas the hot spring water in the Icheon area shows the geochemical characteristics of neutral pH, the $Ca-HCO_3$(or $Ca(Na)-HCO_3$) chemical type and a high uranium content, the hot spring water in the Pocheon area shows the characteristics of alkaline pH, the $Na-HCO_3$ chemical type and a high fluorine content. These characteristics indicate that the hot spring water in the Icheon area is under the early stage in the geochemical evolution, and that the hot spring water in the Pocheon area has been geochemically evolved. The $\delta^{18}O$ and ${\delta}D$ values of hot spring waters show the range of $-10.1{\sim}-8.69%o$ and from $-72.2{\sim}-60.8%o$, respectively, and these values supply the information of the recharge area of hot spring waters. The $^3He/^4He$ ratios of the hot spring waters range from $0.09\;{\times}\;10^{-6}$ to $0.65\;{\times}\;10^{-6}$ which are plotted above the mixing line between air and crustal components. Whereas the helium gas in the Icheon hot spring water was mainly provided from the atmospheric source mixing with the mantle(or magma) origin, the origin of helium gas in the Pocheon hot spring water shows a dominant crustal source. $^{40}Ar/^{36}Ar$ ratios of hot spring water are in the range of an atmosphere source.

• The Korean Journal of Nuclear Medicine
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• v.35 no.1
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• pp.69-74
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• 2001

Purpose: $^{99m}Tc$-HMPAO is a radiopharmaceutical for imaging cerebral blood flow. HMPAO (RR, SS)-4.8-diaza-3,6,6,9-tetramethylundecan-2,10- dione bisoxime) has three stereoismers such as, meso-. d-, and l-HMPAO. Techentium complexes of meso-HMPAO and d,l-HMPAO are known to have different in vivo brain uptakes. In this study, enantiomers of HMPAO (d-HMPAO and l-HMPAO) were separated from d,l-HMPAO. These enantiomers were labeled with $^{99m}Tc$ and the biodistribution studies were performed in mice. Materials and Methods: An intermediate imine product was produced from 2,3-butanedione monooxime and 2,2-dimethyl-1,3-propanediamine (54% yield) and was reduced into a mixture of three isomers (35% yield). The meso-isomer was separated from d,l-mixture by repeated fractional crystallization (11 % yield). The d- and l-enantiomers were subsequently separated by co-crystallization with optical isomers of tartaric acid (25% and 5% yield. respectively). Each enantiomeric HMPAO was labeled with $^{99m}Tc$ by reacting with $SnCI_2{\cdot}2H_2O\;and\;^{99m}Tc$-pertechnetate. Biodistribution study was performed 1 hr after tail vein injection to ICR mice. Results: Radiochemical purities of each compound were over 80%. In biodistribution study. the brain uptakes of d,l- d- and l-form were 1.34, 1.12 and 1.67% ID/g, respectively. In case of l-lsomer the brain uptake was higher (1.5 fold) than d-isomer. Conclusion: We successfully purified each enantiomeric HMPAO. In biodistribution study of stereoismers of $^{99m}Tc$-HMPAO in mice, l-HMPAO may show better brain image than d,l-HMPAO which was supplied in a commercial kit.