• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4B
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• pp.421-428
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• 2008

For last decades, the rapid coastal erosion process spreading along Korean peninsular has become a nuisance especially for tourism and local economy. Global warming and sea-level rise demand persistently new coastal protection strategies against the conventional methods using armored structures. In a view of this, Kweon et al. (2007) has proposed a new type of horizontal steel plates for an ideal candidate as eco-friendly detached breakwater systems for global warming era. The breakwater is composed of piles and horizontal porous plates that was devised for the optimized blockage effects and wave energy dissipations. This system provides outstanding performances as wave barrier and added advantages such as a rapid installation, an easy relocation, a perfect water circulation for the stagnation of pollutions in sheltered regions. The present experimental study focuses on the performance evaluations of the proposed system in wind wave conditions as a wave dissipator and reflector. The reflection, transmission, and energy dissipation of the random waves has been discussed in detail based on a newly proposed relation between wave steepness and a plate width normalized by wave length that are major factors affecting the wave transmission.

• The Korean Journal of Nuclear Medicine
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• v.38 no.5
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• pp.338-343
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• 2004

Purpose: The purpose of this study was to develop a small animal PET using dual layer phoswich detector to minimize parallax error that degrades spatial resolution at the outer part of field-of-view (FOV). Materials and Methods: A simulation tool GATE (Geant4 Application for Tomographic Emission) was used to derive optimal parameters of small PET, and PET was developed employing the parameters. Lutetium Oxyorthosilicate (LSO) and Lutetium-Yttrium Aluminate-Perovskite(LuYAP) was used to construct dual layer phoswitch crystal. $8{\times}8$ arrays of LSO and LuYAP pixels, $2mm{\times}2mm{\times}8mm$ in size, were coupled to a 64-channel position sensitive photomultiplier tube. The system consisted of 16 detector modules arranged to one ring configuration (ring inner diameter 10 cm, FOV of 8 cm). The data from phoswich detector modules were fed into an ADC board in the data acquisition and preprocessing PC via sockets, decoder block, FPGA board, and bus board. These were linked to the master PC that stored the events data on hard disk. Results: In a preliminary test of the system, reconstructed images were obtained by using a pair of detectors and sensitivity and spatial resolution were measured. Spatial resolution was 2.3 mm FWHM and sensitivity was 10.9 $cps/{\mu}Ci$ at the center of FOV. Conclusion: The radioactivity distribution patterns were accurately represented in sinograms and images obtained by PET with a pair of detectors. These preliminary results indicate that it is promising to develop a high performance small animal PET.

• 기호학연구
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• no.57
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• pp.211-255
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• 2018

This paper attempts to "re-read" the webtoon Misaeng, which was once an important issue in the field of public discourse on "labor". Our hypothesis was that the dual actactial structure of Misaeng's hero Jang Geurae gave a dual structure to the entire text, which leads to the discovery of text meaning that was not mentioned in the existing discourse. This is based on the concept of 'meta-story character', which Hiroki Azuma talked in his postmodern literary theory. To verify this hypothesis we analyzed the text by applying the Parisian semiotics, more specifically J. Fontanille's theory. Jang Geurae is observed to be a actant of dual structure divided into 'character' of the enunciated level and 'player' of the enunciation level. Considering this characteristic of the hero, Misaeng can be interpreted as a metafiction that shows the 'shifting' between the subject of the enunciated level and the subject of the enunciation level. On the level of 'character' Jang's existence mode turns out to be "Deficiency (actualized)", but on the level of 'player' Jang 's existence mode turns out to be "Inanity(potentiallized)." His somatic responses also show a duality, which is represented by Fontanille's corps-actant model, where on the level of 'character' the somatic actant of Jang consists of 'Moi-chair(ego-flesh)' and 'Soi-idem(self-idem)', and on the level of 'player' it consists of 'Moi-chair(ego-flesh)' and 'Soi-ipse(self-ipse)'. The former mainly acts as a 'role' and takes charge of exteroceptive perception, while the latter mainly acts as 'attitude' and takes charge of interoceptive perception. Because of this dissociative nature of actant, Jang's two 'self' draw the re-adjustment of values without serious conflict between the collective norms and the individual identity. This is in sharp contrast with other characters who struggle with the conflict between the environment and "self". It becomes customary to adopt norms that are suspected to ineffective, but if you raise questions, the normative system can be updated. On one axis of Misaeng there are characters who have lost themselves in customs. On the other axis, there is Jang who can not help dismantling the existing ineffective norms and updating the normative system. Jang's existence mode seems to be one of many possible modes generated by this era where people share no longer solid community values, His actantial structure also communicates with readers of these days who put themselves more in subject of enunciation level than of enunciated level.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.45-53
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• 2022

In order to improve the emission of diesel engines, natural gas-diesel dual fuel combustion compression ignition engines are in the spotlight. In particular, a reactivity controlled compression ignition (RCCI) combustion strategy is investigated comprehensively due to its possibility to improve both efficiency and emissions. With advanced diesel direct injection timing earlier than TDC, it achieves spontaneous reaction with overall lean mixture from a homogeneous mixture in the entire cylinder area, reducing nitrogen oxides (NOx) and particulate matter (PM) and improving braking heat efficiency at the same time. However, there is a disadvantage in that the amount of incomplete combustion increases in a low load region with a relatively small amount of fuel-air. To solve this, sensitive control according to the diesel injection timing and fuel ratio is required. In this study, experiments were conducted to improve efficiency and exhaust emissions of the natural gas-diesel dual fuel engine at low load, and evaluate combustion stability according to the diesel injection timing at the operation point for power generation. A 6 L-class commercial diesel engine was used for the experiment which was conducted under a 50% load range (~50 kW) at 1,800 rpm. Two injectors with different spray patterns were applied to the experiment, and the fraction of natural gas and diesel injection timing were selected as main parameters. Based on the experimental results, it was confirmed that the brake thermal efficiency increased by up to 1.3%p in the modified injector with the narrow-angle injection added. In addition, the spray pattern of the modified injector was suitable for premixed combustion, increasing operable range in consideration of combustion instability, torque reduction, and emissions level under Tier-V level (0.4 g/kWh for NOx).

• The Korean Journal of Nuclear Medicine
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• v.38 no.4
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• pp.294-299
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• 2004

Purpose: Both human NIS and mutant $D_2R$ transgenes are proposed as reporting system in transplanted cell tracking. Using hepatoma cell lines, we constructed a dual reporter system containing human sodium-iodide symporter (hNIS) and dopamine 2 receptor ($D_2R$) and compared its characteristics. Materials and Methods: The recombinant plasmid ($pIRES-hNIS/D_2R$) was constructed with IRES (internal ribosome entry site) under control of the CMV promoter $pIRES-hNIS/D_2R$ was transfected to human hepatoma SK-Hep1 cell line with lipofectamine. HEP-ND ($SK-Hep1-hNIS/D_2R$) cells stably expressing hNIS and $D_2R$ was established by selection with G418 for two weeks. RT-PCR was performed to investigate the expression of both hNIS and $D_2R$ genes. The expressions of hNIS and $D_2R$ were measured by $^{125}I$ uptake assays and receptor binding assays. Specific binding of $D_2R$ to $[^3H]spiperone$ was verified by Scatchard plot with (+) butaclamol as a specific inhibitor. $K_d\;and\;B_{max}$ values were estimated. The correlation between hNIS and $D_2R$ expression was compared by using each clone. Results: Similar quantities of hNIS and $D_2R$ genes were expressed on HEP-ND as RT-PCR assays. HEP-ND cells showed 30 to 40 fold higher radioiodine uptakes than those of parental SK-Hep1 cells. $^{125}I$ uptake in HEP-ND cells was completely inhibited by $KClO_4$, a NIS inhibitor Specific binding to HEP-ND cells was saturable and the $K_d\;and\;B_{max}$ values for HEP-ND cells were 2.92 nM, 745.25 fmol/mg protein and 2.91nM, 1323 fmole/mg protein in two clones, respectively. The radioiodine uptake by hNIS activity and $D_2R$ binding was highly correlated. Conclusion: We developed a dual positron and gamma imaging reporter system of hNIS and $D_2R$ in a stably transfected cell line. We expect that $D_2R$ and hNIS genes can complement mutually as a nuclear reporting system or that $D_2R$ can be used as reporter gene when hNIS gene were used as a treatment gene.

• Journal of radiological science and technology
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• v.29 no.4
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• pp.241-247
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• 2006

Recently, interests and utilization on Computed Radiography(CR) and Digital Radiography(DR) tends to increase owing to an introduction of Picture Archiving and Communication System(PACS) and an accuracy control of special medical equipment for a breast imaging examination. This study was intended to compare and analyze a detector's imaging quality by each system to be used for the breast imaging examination by using ACR Phantom used at the accuracy control. As an evaluation method, a significance and reliability of image's value using the ACR Phantom was analyzed by using SPSS program. The results are followed. 1. For the fiber, there was 3.9 score in Screen-Film, 4.2 score in CR($50{\mu}m$), 3.2 score in CR($100{\mu}m$), and 4.2 score in DR. There was the high score in the order of CR($50{\mu}m$), DR, Screen-Film, and CR($100{\mu}m$)(P<0.05). 2. For the calcification, there was 2.7 score in Screen-Film, 2.5 score in CR($50{\mu}m$), 2.0 score in CR($100{\mu}m$), and 2.9 score in DR. There was the high score in the order of DR, Screen-Film, CR($50{\mu}m$), and CR($100{\mu}m$).(0.025(P<0.05). 3. For Mass, there was 3.8 score in Screen-Film, 3.8 score in CR($50{\mu}m$), 3.6 score in CR($100{\mu}m$), and 4.5 score in DR. There was the high score in the order of DR, CR($50{\mu}m$), Screen-Film, and CR($100{\mu}m$) (P<0.1). 4. As the total score, there was 10.4 score in Screen-Film, 10.6 score in CR($50{\mu}m$), 8.7 score in CR($100{\mu}m$), and 11.3 score in DR. There was the high score in the order of DR, $CR(50{\mu}m$), Screen-Film, and $CR(100{\mu}m$). As shown in the above results, it can be known that DR and Screen-Film System has higher image quality than CR. But, DR has unstability caused by element, and Screen-Film has the low image quality caused by artifact as disadvantages. When Dual-Side CR($50{\mu}m$) was used among CR systems which had the problem of low image quality, it was indicated that there was no difference with Screen-Film System. Because the radiation imaging examination tends to become digitalized, each system for the breast imaging examination will need to be developed and supplemented.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.2
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• pp.195-202
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• 2010

The evaluation of organic matters and nutrients removal was investigated for the synthetic wastewater and the high strength of dairy wastewater. Two different systems were performed for this research. System A composing of a single RBC with tapered aeration was fed with the synthetic wastewater for 74 days with 173L/day of influent, 200% of internal return and 100% of sludge return for the period 1 and 2. The feed conditions were maintained 346L/day of influent, 50% of internal return and sludge return for the period 3. The dairy wastewater was introduced to evaluate treatment efficiency for system B composing of dual RBCs and tapered aeration tanks for 50 days of experimental run time, in which hydraulic rates were maintained at the constant ratios of 346L/day, 50% of internal return and 50% of sludge return. The spiral string media made of nylon fibre was attached by Bacillus sp. in RBC for both systems. The specific area of string media was $1.4m^2$/m and biomass was maintained at the concentrations of 23g/m. The synthetic wastewater was supplied by 1,800mg/L of glucose, 500mg/L of $NH_4Cl$, and 500mg/L of $KH_2PO_4$ to system A. The dairy wastewater was supplied to system B from dairy production plant. The average influent concentrations were 1,334mg/L of BOD, 2,014mg/L of CODcr, 160mg/L of T-N, and 12mg/L of T-P in system A. The average influent concentrations of parameters were 1,006 mg/L for BOD, 1,875mg/L for $COD_{cr}$, 51.6mg/L for T-N and 8.9mg/L for T-P in system B. Results indicated that removal efficiencies of BOD and $COD_{cr}$ were more than 90% however, the removal efficiency of T-N was 87%, and that of T-P was 82% for system A. Removal efficiencies were 98.5% of BOD, 91.3% of nitrogen and 89% of phosphorus for system B. The removal efficiencies of organic matters, T-N and T-P were higher in system B than in system A. The effluent quality issued by the stringent national legislations for the discharge of the high strength of dairy products wastewater can be improved using sequential RBCsand tapered aeration reactors rather than a single RBC and tapered aeration reactors with Bacillus sp.

• Journal of Korean Society of Transportation
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• v.26 no.5
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• pp.227-235
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• 2008

This study analyzed the efficiency of a trunk with branches and a trunk with feeders route system comparing the user cost and operator cost of those route systems. Basically, a trunk with branches is more efficient than a trunk with feeders in the passengers' perspective if the transit system of a trunk and feeders are the same. In the case that the trunk system is hierarchically higher than the feeder system, a trunk with feeders has the competitive edge over a trunk with branches if the saving of travel cost induced by using the trunk line is larger than the increasing waiting and transfer cost. This result is consistent with the previous research by Park et al.(2007c), which analyzed the efficiency of hierarchical structure in a grid transit network. If the travel demand of each origins and destinations is low, increasing headway according to the travel demand can increase passenger load or operating efficiency in a trunk with feeders route system. In this case, a trunk with feeders route system is more prevalent as the operating cost, route length, and number of destinations increases, while it is less prevalent as the transfer cost and passengers' time value of the waiting time increases. In cases that central business district, which is located in the middle of a trunk line, generates travel demand, a trunk with feeders is more efficient than a trunk with branches with the increasing travel demand from and to the CBD. Therefore it can be concluded that to have a dual operating system between CBD and suburban is more efficient than one type transit system. The efficiency of that system can be increased through an efficient transfer system that can reduce the transfer cost.

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.15-21
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• 1993

This paper describes the design and development of a KrF excimer laser stepper and discusses the detailed system parameters and characterization data obtained from the performance test. We have developed a deep UV step-and-repeat system, operating at 248 nm, by retrofitting a commercial modules such as KrF excimer laser, precision wafer stage and fused silica illumination and 5X projection optics of numerical aperture 0.42. What we have developed, to the basic structure, are wafer alignment optics, reticle alignment system, autofocusing/leveling mechanisms and environment chamber. Finally, all these subsystem were integrated under the control of microprocessor-based controllers and computer. The wafer alignment system comprises the OFF-AXIS and the TTL alignment. The OFF-AXIS alignment system was realized with two kinds of optics. One is the magnification system with the image processing technique and the other is He-Ne laser diffraction type system using the alignment grating on the wafer. 'The TTL alignment system employs a dual beam inteferometric method, which takes advantages of higher diffraction efficiency compared with other TTL type alignment systems. As the results, alignment accuracy for OFF-AXIS and TTL alignment system were obtained within 0.1 $\mu\textrm{m}$/ 3 $\sigma$ for the various substrate on the wafers. The wafer focusing and leveling system is modified version of the conventional systems using position sensitive detectors (PSD). This type of detection method showed focusing and leveling accuracies of about $\pm$ 0.1 $\mu\textrm{m}$ and $\pm$ 0.5 arcsec, respectively. From the CD measurement, we obtained 0.4 $\mu\textrm{m}$ resolution features over the full field with routine use, and 0.3 $\mu\textrm{m}$ resolution was attainable under more strict conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.419-425
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• 2019

The objective of this study was to investigate the cooling performance characteristics of a hybrid refrigeration system in a heavy duty vehicle. The tested hybrid refrigeration system had additionally an electric compressor besides the present mechanical compressor for selective use according to the operating conditions. The applied electric compressor was a scroll type and with 18.0 cc displacement. In order to analyze the performance characteristics of the hybrid refrigeration system with respect to the cooling capacity and Coefficient of Performance (COP), other components, including two different types of compressors, were installed and tested under various operating conditions such as compressor speed and air flow rate of the evaporator. When the electric compressor was operated at 4,500 rev/min, the cooling capacity was about 4.0kW and COP was 3.5. When the mechanical compressor was operated, whereas the cooling capacity was higher than the electric controlled compressor, COP was lower due to the larger displacement and higher power consumption. To analyze the hybrid system operating characteristics due to reasonable cooling capacity with electric compressor operation, the mechanical compressor and electric compressor were operated by turns every 10 minutes under certain system operating conditions. Because surge pressure occurred when both compressors were switched on, the operating strategy required some time to balance the system pressure.