• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.199-211
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• 2002

Digital substraction technique and computer-assisted densitometirc analysis detect minor change in bone density and thus increase the diagnostic accuracy. This advantage as well as high sensitivity and objectivity which precludes human bias have drawn interest in radiologic research area. The objectives of this study are to verify if Radiographic density can be recognized in linear pattern when density profile of standard periapical radiograph with the aluminium stepwedge as the reference, was investigated under varies circumstances which can be encountered in clinical situations, and in addition to that to obtain mutual relationship between the existing standard radiographic system, and future digital image systems, by confirming the corelationship between the standard radiograph and Digora system which is a digital image system currently being used. In order to make quantitative analysis of the bone tissue, digital image system which uses high resolution automatic slide scanner as an input device, and Digora system were compared and analyzed using multifunctional program, Brain3dsp. The following conclusions were obtained. 1. Under common clinical situation that is 70kVp, 0.2 sec., and focal distance 10cm, Al-Equivalent image equation was found to be Y=11.21X+46.62 $r^2=0.9898$ in standard radiographic system, and Y=12.68X+74.59, $r^2=0.9528$ in Digora system, and linear relation was confirmed in both the systems. 2. In standard radiographic system, when all conditions were maintained the same except for the condition of developing solution, Al-Equivalent image equation was Y=10.07X+41.64, $r^2=0.9861$ which shows high corelationship. 3. When all conditions were maintained the same except for the Kilovoltage peak, linear relationship was still maintained under 60kVp, and Al-Equivalent image equation was Y=14.60X+68.86, $r^2=0.9886$ in the standard radiograhic system, and Y=13.90X+80.68, $r^2=0.9238$ in Digora system. 4. When all conditions were maintained the same except for the exposure time which was varied from 0.01 sec. to 0.8 sec., Al-Equivalent image equation was found to be linear in both the standard radiographic system and Digora system. The R-square was distributed from 0.9188 to 0.9900, and in general, standard radiographic system showed higher R-square than Digora system. 5. When all conditions were maintained the same except for the focal distance which was varied from 5cm to 30cm, Al-Equivalent image equation was found to be linear in both the standard radiographic system and Digora system. The R-square was distributed from 0.9463 to 0.9925, and the standard radiographic system had the tendency to show higher R-square in shorter focal distances.

• The Korean Journal of Nuclear Medicine
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• v.38 no.1
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• pp.74-84
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• 2004

Purpose: Since I-125 emits low energy (27-35 keV) radiation, thinner crystal and collimator could be employed and, hence, it is favorable to obtain high quality images. The purpose of this study was to derive the optimized parameters of I-125 SPECT using a new simulation tool, GATE (Geant4 Application for Tomographic Emission). Materials and Methods: To validate the simulation method, gamma camera developed by Weisenberger et al. was modeled. Nal(T1) plate crystal was used and its thickness was determined by calculating detection efficiency. Spatial resolution and sensitivity curves were estimated by changing variable parameters for parallel-hole and pinhole collimator. Peformances of I-125 SPECT equipped with the optimal collimator were also estimated. Results: in the validation study, simulations were found to agree well with experimental measurements in spatial resolution (4%) and sensitivity (3%). In order to acquire 98% gamma ray detection efficiency, Nal(T1) thickness was determined to be 1 mm. Hole diameter (mm), length (mm) and shape were chosen to be 0.2:5:square and 0.5:10:hexagonal for high resolution (HR) and general purpose (GP) parallel-hole collimator, respectively. Hole diameter, channel height and acceptance angle of pinhole (PH) collimator were determined to be 0.25 mm, 0.1 mm and 90 degree. The spatial resolutions of reconstructed image of the I-125 SPECT employing HR:GP:PH were 1.2:1.7:0.8 mm. The sensitivities of HR:GP:PH were 39.7:71.9:5.5 cps/MBq. Conclusion: The optimal crystal and collimator parameters for I-125 Imaging were derived by simulation using GATE. The results indicate that excellent resolution and sensitivity imaging is feasible using I-125 SPECT.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.753-759
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• 2007

Statement of problem. In distal extension removable partial denture, the preservation of health of abutment teeth is very important, but abutment teeth are subjected to unfavorable stress under unilateral loading specially. Purpose. The purpose of this study was to investigate the biomechanical effects of mandibular removable partial dentures with various prosthetic designs under unilateral loading, using strain gauge analysis. Material and methods. Artificial teeth of both canines were anchored bilaterally in a mandibular edentulous model made of resin. Bilateral distal extension removable partial dentures with splinted and unsplinted abutments were fabricated. Group 1: Clasp-retained mandibular removable partial denture with unsplinted abutments Group 2: Clasp-retained mandibular removable partial denture with splinted abutments by 6-unit bridge. Group 3: Bar-retained mandibular removable partial denture Strain gauges were bonded on the labial plate of the mandibular resin model, approximately 2 mm dose to the abutments. Two unilateral vertical experimental loadings (30N and 100N) were applied subsequently via miniature load cell that were placed at mandibular left first molar region. Strain measurements were performed and simultaneously monitored from a computer connected to data acquisition system. For within-group evaluations, t-test was used to compare the strain values and for between-group comparisons, a one-way analysis of variance (ANOVA) was used and Tukey test was used as post hoc comparisons. Results. The strain values of group 1 and 2 were tensile under loadings. In contrast, strain values of group 3 were compressive in nature. Strain values increased as the applied load in increased from 30N to 100N (p<.05) except for right side in group 1. Under 30N loading, in left side, group 1 showed higher strain values than groups 2 and 3 in absolute quantity (p<.05). And group 2 showed higher strain values than group 1 (p<.05). In right side, group 1 and 2 showed higher strain values than group 3 in absolute quantity (p<.05). Under 100N loading in left side, group 1 showed higher strain values than groups 2 and 3 in absolute quantity (p<.05). And group 2 showed higher strain values than group 1 (p<.05). In right side, group 1 and 2 showed higher strain values than group 3 in absolute quantity (p<.05). Under 30N loading, group 2 and 3 showed higher strain values in right side than in left side. Under 100N loading, right side strain values were higher than left side ones for all groups. Conclusion. Splinting of two isolated abutments by bridge reduced the peri-abutment strain in comparison with unsplinted abutments under unilateral loading. Bar-retained removable partial denture showed the lowest strain of three groups, and compressive nature.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.4
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• pp.294-300
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• 2010

Purpose: The template-guided implant surgery offers several advantages over the traditional approach. The purpose of this study was to evaluate the accuracy of coordinate synchronization procedure with 5-axis milling machine for surgical template fabrication by means of reverse engineering through universal CAD software. Materials and methods: The study was performed on ten edentulous models with imbedded gutta percha stoppings which were hidden under silicon gingival form. The platform for synchordination was formed on the bottom side of models and these casts were imaged in Cone beam CT. Vectors of stoppings were extracted and transferred to those of planned implant on virtual planning software. Depth of milling process was set to the level of one half of stoppings and the coordinate of the data was synchronized to the model image. Synchronization of milling coordinate was done by the conversion process for the platform for the synchordination located on the bottom of the model. The models were fixed on the synchordination plate of 5-axis milling machine and drilling was done as the planned vector and depth based on the synchronized data with twist drill of the same diameter as GP stopping. For the 3D rendering and image merging, the impression tray was set on the conbeam CT and pre- and post- CT acquiring was done with the model fixed on the impression body. The accuracy analysis was done with Solidworks (Dassault systems, Concord, USA) by measuring vector of stopping’s top and bottom centers of experimental model through merging and reverse engineering the planned and post-drilling CT image. Correlations among the parameters were tested by means of Pearson correlation coefficient and calculated with SPSS (release 14.0, SPSS Inc. Chicago, USA) ($\alpha$ = 0.05). Results: Due to the declination, GP remnant on upper half of stoppings was observed for every drilled bores. The deviation between planned image and drilled bore that was reverse engineered was 0.31 (0.15 - 0.42) mm at the entrance, 0.36 (0.24 - 0.51) mm at the apex, and angular deviation was 1.62 (0.54 - 2.27)$^{\circ}$. There was positive correlation between the deviation at the entrance and that at the apex (Pearson Correlation Coefficient = 0.904, P = .013). Conclusion: The coordinate synchronization 5-axis milling procedure has adequate accuracy for the production of the guided surgical template.

• Journal of Food Hygiene and Safety
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• v.28 no.4
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• pp.349-353
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• 2013

This study was performed to evaluate the bactericidal efficacy of Fumagari OPP$^{(R)}$, fumigation disinfectant, containing 20% ortho-phenylphenol against Staphylococcus aureus (S. aureus). In this research, efficacy test of fumigant against S. aureus was carried out according to French standard NF T 72-281. S. aureus working culture suspension number (N value), all of the colony numbers on the carriers exposed with the fumigant (n1, n2, and n3), the number of bacterial test suspentions by pour plate method (N1), the number of bacterial test suspentions by filter membrane method (N2) and the mean number of bacteria recovered on the control-carriers (T value) were obtained from the preliminary test. In addition, the reduction number of S. aureus exposed with the fumigant (d value) was calculated using T value, the mean number of bacteria in recovery solution (n'1) and the mean number of bacteria on carriers plated in agar (n'2). N value was $4.0{\times}10^8$ CFU/mL, and n1, n2, and n3 were higher than 0.5N1, 0.5N2 and 0.5N1, respectively. Additionally, T value was $3.4{\times}10^6$ CFU/mL. In the bactericidal effect of the fumigant, the d value was 6.43 logCFU/mL. According to the French standard for the fumigant, the d value for the effective bactericidal fumigant should be over than 5 logCFU/mL. The results indicated that Fumagari OPP$^{(R)}$ had an effective bactericidal activity against S. aureus, then the fumigant can be applied to disinfect food materials and kitchen appliances contaminated with pathogenic bacteria.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.60-66
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• 2014

This test was performed to evaluate the bactericidal efficacy of a fumigation disinfectant containing 20% ortho-phenylphenol against Pseudomonas aeruginosa (P. aeruginosa) and Enterococcus hirae (E. hirae). In preliminary tests, P. aeruginosa and E. hirae working culture suspension number (N value) were $2.8{\times}10^8$ and $4.0{\times}10^8CFU/mL$, respectively. And all the colony numbers on the carriers exposed to the fumigant (n1, n2, n3) were higher than 0.5N1 (the number of bacterial test suspentions by pour plate method), 0.5N2 (the number of bacterial test suspentions by filter membrane method) and 0.5N1, respectively. In addition, the mean number of P. aeruginosa and E. hirae recovered on the control-carriers (T value) was $2.8{\times}10^8$ and $3.4{\times}10^6CFU/mL$, respectively. In the bactericidal effect of the fumigant, the reduction number of $2.8{\times}10^8$ (d value) was 6.46 and 5.19 logCFU/mL, respectively. According to the French standard for the fumigant, the d value for the effective bactericidal fumigant should be over than 5 logCFU/mL. With the results from this study, the fumigation disinfectant containing 20% ortho-phenylphenol has an effective bactericidal activity, then the fumigant can be applied to disinfect food materials and kitchen appliances contaminated with the pathogenic bacteria.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.6
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• pp.427-446
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• 2008

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2006 has been accomplished. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environments. The conclusions are as follows. (1) The research trends of fluid engineering have been surveyed as groups of general fluid flow, fluid machinery and piping, etc. New research topics include micro heat exchanger and siphon cooling device using nano-fluid. Traditional CFD and flow visualization methods were still popular and widely used in research and development. Studies about diffusers and compressors were performed in fluid machinery. Characteristics of flow and heat transfer and piping optimization were studied in piping systems. (2) The papers on heat transfer have been categorized into heat transfer characteristics, heat exchangers, heat pipes, and two-phase heat transfer. The topics on heat transfer characteristics in general include thermal transport in a cryo-chamber, a LCD panel, a dryer, and heat generating electronics. Heat exchangers investigated include pin-tube type, plate type, ventilation air-to-air type, and heat transfer enhancing tubes. The research on a reversible loop heat pipe, the influence of NCG charging mass on heat transport capacity, and the chilling start-up characteristics in a heat pipe were reported. In two-phase heat transfer area, the studies on frost growth, ice slurry formation and liquid spray cooling were presented. The studies on the boiling of R-290 and the application of carbon nanotubes to enhance boiling were noticeable in this research area. (3) Many studies on refrigeration and air conditioning systems were presented on the practical issues of the performance and reliability enhancement. The air conditioning system with multi indoor units caught attention in several research works. The issues on the refrigerant charge and the control algorithm were treated. The systems with alternative refrigerants were also studied. Carbon dioxide, hydrocarbons and their mixtures were considered and the heat transfer correlations were proposed. (4) Due to high oil prices, energy consumption have been attentioned in mechanical building systems. Research works have been reviewed in this field by grouping into the research on heat and cold sources, air conditioning and cleaning research, ventilation and fire research including tunnel ventilation, and piping system research. The papers involve the promotion of efficient or effective use of energy, which helps to save energy and results in reduced environmental pollution and operating cost. (5) Studies on indoor air quality took a great portion in the field of building environments. Various other subjects such as indoor thermal comfort were also investigated through computer simulation, case study, and field experiment. Studies on energy include not only optimization study and economic analysis of building equipments but also usability of renewable energy in geothermal and solar systems.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.2
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• pp.135-144
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• 2010

Purpose: The purpose of this study is that through production of phantom for respiration gated radiotherapy, assessing appropriacy of exposure dose for the therapy using RPM (Real-time Position Management). Materials and Methods: We located measurement object on the phantom for respiration gated radiotherapy made of 2 linear actuator, acrylic panel, stanchion, iron plate ets. to drive (up, down, front, back). Using 4D CT scan, we analyzed patient's respiration and reproduced the movement by computer. On the phantom, we located a 2D-Array (PTW) and an White water phantom (4.5 cm) and used DMLC (interval 2 cm) in the field size $10{\times}10\;cm$, then exposed 21EX X-ray 100 MU, in the case of phantom was (1) static (2) moving (3) gated using RPM respectively gantry $0^{\circ}$ and $90^{\circ}$ We measured with a 0.125 CC ionization chamber (PTW) on the phantom (7.5 cm) in the same condition. Results: Ionization chamber: There were within 0.3% of error with gating respiration and approximately 2% of error without gating in the same condition. 2D-Array: Gantry $90^{\circ}$, field size $10{\times}10\;cm$, using DMLC. There were within 3% of error with gating respiration and approximately 16% of error without gating. Conclusion: The phantom for respiration gated radiotherapy makes plans considering patient's movement, quantitative analysis of exposure dose and proper assessment therapy for IMRT patients using RPM possible.