• Science of Emotion and Sensibility
• /
• v.26 no.4
• /
• pp.51-70
• /
• 2023

This study employed driving simulation to examine how takeover request (TOR) information modalities (visual, auditory, and visual + auditory) in Level-3 automated vehicles, and road types (straight and curved) influence the driver's control takeover time (TOT) and mental workload, assessed through subjective workload and heart rate variations. The findings reveal several key points. First, visual TOR resulted in the quickest TOT, while auditory TOR led to the longest. Second, TOT was considerably slower on curved roads compared to straight roads, with the greatest difference observed under the auditory TOR condition. Third, the auditory TOR condition generally induced lower subjective workload and heart rate variability than the visual or visual + auditory conditions. Finally, significant heart rate changes were predominantly observed in curved road conditions. These outcomes indicate that TOT and mental workload levels in drivers are influenced by both the TOR modality and road geometry. Notably, a faster TOT is associated with increased mental workload.

• Progress in Medical Physics
• /
• v.9 no.4
• /
• pp.267-276
• /
• 1998

Any detector inserted into a phantom should have such a geometry that it caused as small as possible perturbation of the electron fluence. Plane parallel chambers meet this requirement better than other chambers of configurations. IAEA protocol recommends the use of plane parallel chambers for this reason. However, the cylindrical chambers are widely used for convenient. The purpose of this study is to evaluate the absorbed dose due to the differences of four different dosimetry protocols such as IAEA protocol using cylindrical chamber, TG 21 protocol using cylindrical chamber, Markus protocol using plane parallel chamber, and TG 39 report for the calibration of plane parallel chamber in electron beams. Depth-ionization measurements for the electron beams of nominal energy 6, 9, 12, 15, and 18 MeV from Siemens accelerator with a 10$\times$10 cm$^2$ field size were made using a radiation field analyser with 0.125 cc ion chamber. Dosimetric measurements by IAEA and TG 21 protocol were made with a farmer type ionization chamber in solid water for each electron energy, respectively. Dosimetric measurements by Markus protocol were made with a plane parallel ionization chamber in solid water for each electron energy, respectively. The cavity-gas calibration factor for the plane parallel chamber was obtained with the use of 18 MeV electron beam as guided by TG 39 report. Dosimetric measurements by TG 39 were performed with a plane parallel ionization chamber in solid water for each electron energy, respectively. For all the energies and protocols, measurements were made along the central axis of the distance of 100 cm (SSD = 100 cm) with 10$\times$10 cm$^2$ field size at the depth of d$_{max}$ for each electron beam, respectively. In the case of 18 MeV, the discrepancy of 0.9 % between IAEA and TG 21 was found and the two protocols were agreed within 0.7 % for other energies. In the case of 18 MeV and 6 MeV, the discrepancies of $\pm$ 0.8 % between Markus and TG 39 was found, respectively and the two protocols were agreed within 0.5 % for other energies. Since the discrepancy of 1.6 % between cylindrical and plane parallel chamber was found for 18 MeV, it is suggested to get the calibration factor using other method as guided. by TG 39.9.

• Korean Journal of Organic Agriculture
• /
• v.23 no.4
• /
• pp.963-974
• /
• 2015

This study was conducted to determine the effects of organic vegetable cultivation on the soil physical properties in 33 farmlands under plastic greenhouse in Korea. We were investigated 5~8 farms per organic vegetable crops during the period from August to November 2014. The main cultivated vegetables were leafy lettuce (Lactuca sativa L.), Perilla leaves (Perilla frutescens var. Japonica Hara), cucumber (Cucumis sativus L.), strawberry (Fragaria ananassa L.) and tomato (Lycopersicon spp.). We have analyzed soil physical properties. The measured soil physical parameters were soil plough layer, soil hardness, penetration resistance, three soil phase, bulk density and Porosity. The measurement of the soil plough layer, soil hardness and penetration resistance were carried out direct in the fields, and the samples for other parameters were taken using the soil core method with approximately 20 mm diameter core collected from each organic vegetable field. Soil plough layer was average 36 cm and ranged between 30 and 50 cm, and slightly different depending on the sorts of vegetable cultivation. The soil hardness was $0.17{\pm}0.15{\sim}1.34{\pm}1.02$ in the topsoil, $0.55{\pm}0.34{\sim}1.15{\pm}0.62$ in the subsoil. It was not different between topsoil and subsoil, but showed a statistically significant difference between the leafy and fruit vegetables. Penetrometer resistance is one of the important soil physical properties that can determine both root elongation and yield. The increase in density under leafy vegetables resulted in a higher soil penetrometer resistance. Soil is a three-component system comprised of solid, liquid, and gas phases distributed in a complex geometry that creates large solidliquid, liquid-gas, and gas-solid interfacial areas. The three soil phases were dynamic and typically changed in organic vegetable soils under greenhouse. Porosity was characterized as range of $54.2{\pm}2.2{\sim}60.3{\pm}2.4%$. Most measured soils have bulk densities between 1.0 and $1.6gcm^{-3}$. To summarize the above results, Soil plough layer has been deepened in organic vegetable cultivation soils. Solid hardness (the hardness of the soil) and bulk density (suitable for the soil unit mass) have been lowered. Porosity (soil spatial content) was high such as a well known in organic farmlands. Important changes were observed in the physical properties according to the different vegetable cultivation. We have demonstrated that the physical properties of organic cultivated soils under plastic greenhouse were improved in the results of this study.

• Journal of the Korean Society of Radiology
• /
• v.15 no.4
• /
• pp.463-472
• /
• 2021

Demand for examinations using transvaginal transducer with high frequencies is increasing to observe pelvic organs in gynecological ultrasound tests. However, the quality control of the replacement probe in clinical trials is not properly implemented and the evaluation criteria have not been established. Therefore, 58 transvaginal transducers and 20 convex transducers were applied to the ATS-539 ultrasound phantom for 20 ultrasound devices currently in clinical use to obtain their respective images and measure them quantitatively and qualitatively. For quantitative measurements, vertical measurement, horizontal measurement, and focal zone and qualitative measurements, dead zone, axial·lateral resolution, sensitivity, functional resolution, gray scale·dynamic range were performed. Quantitative statistical analysis showed significant differences between the two transducers in the lateral measurement and local area (p<0.05). qualitative comparative analysis showed differences in sensitivity and functional resolution. This occurs due to the difference in frequency between transducers and the transducer's injection geometry. Based on the above experiments, the tolerance for horizontal measurement is raised to 10% (±8 mm), the tolerance for sensitivity is observed up to 6 cm deep, which is 12 cm deep,which is the level of the third quartile (75%). The permissible range of functional resolution is up to 6 (12 cm), 6 (12 cm), 11 (11 cm), 9 (9 cm), 6 (6 cm) target, which is the level of the third quartile (75%). It is considered reasonable to adjust the depth of targets in gray scale·dynamic range to measure at a depth of 2 cm, which is 50% of the depth of 4 cm. As above, the criteria for evaluating the quality of transvaginal transducer for use in the past have been proposed and it is expected that this study will be used as a basic data for the production of phantom exclusively for transvaginal transducer in the future.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.38 no.2
• /
• pp.156-163
• /
• 2002

In order to development the construction and dimension of fishing gear for gizzard shad coastal purse seine, first of all investigated to the sinking speed and underwater geometry of net, behaviour of fish school to the net during the fishing operation In the field. The results obtained are summarized as follows; 1. Average sinking speed of net was 13cm/sec in bunt, 9.0cm/sec and 9.5cm/sec in 170m and 280m of center, 4.9cm/sec in end wing side, therefore was fastest in start of shooting and decreased gradually during the shooting process. 2. The most of leadline was reached in bottom from the shooting immediately to hauling time and the mean depth of timber bar used equipment for the escaping prevention of fish school was within the 2.7m. 3. The fish school of gizzard shad was appearanced higher density and remained to the most time in bottom than the surface and repeated to vortical movement, and its tendency to distinct in rapid time of tide current. 4. Behaviour of fish school in the net was showed to the vortical movement by sinking and rising immediately with the shooting of net and then divide with the two shape to follow round the wall of net and no patterns straightly movement in the net, and tendency easily catched in fish school of the wall of net. 5. Escaping of fish school in the gap of wing side was to busy after that seting the timber bar, therefore its function for escaping prevention of fish school was very lowed. 6. Escaping behaviour of fish school was differenced with the depth of fishing ground, the above 20m escaped to busy through the below in ledline because the sinking speed of fish school is fast than the net.

• Journal of Korean Society of Steel Construction
• /
• v.25 no.1
• /
• pp.35-45
• /
• 2013

The concrete-filled tube column has the excellent structural performance. But it is difficult to connect with column and beam because of closed section. It suggests that pipe should be produced by welding two sides together where two shapes are joined after a channel is pre-welded onto the three sides in order to form an internal diaphragm. The upper diaphragm of the connection used the horizontal plate and the lower diaphragm used the Vertical plate. This research performed 6 monotonic tension experiments describing the connection upside and downside in order to evaluate the structural capability of the offered connection. And the cyclic loading experiment was performed about 2 T-Type column to beam connections. As to the experimental result edge cutting geometry, there was no big effect. An increase in the number of holes of the plate ultimate strength was increased by 5% and The thickness of the plate increases, the maximum strength was increased by 4%. T-Type connections until it reaches the plastic moment showed a stable behavior.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.23 no.6
• /
• pp.272-278
• /
• 2013

In this study, a c-axis displacement and an internal stress of the sapphire crystal of 300 mm length have been analyzed numerically and the crystal length having no sub-grain defects have been predicted. The hot zone structures were modified with the crucible geometry change and the additional insulation layer installed above the crucible. The simulation results show that the c-axis displacement difference between the original hot zone and others originated from the sub-grain defect formations in the sapphire ingot. When the crystal grown by CZ (Czochralski) grower using the modified hot zone, the crystal length having no sub-grain defects was increased about 57 mm maximum than the original one. When the simulation results compared with the experimental one, the predicted crystal length having no sub-grain defects were well corresponded with the experiment one in c-axis wafer of the 300 mm sapphire ingot. Therefore the sapphire crystal of 250 mm length having no sub-grain defects was successfully grown by CZ process.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.31 no.4
• /
• pp.301-309
• /
• 2015

Purpose: When the edentulous area is restored by implant prostheses, the opposing hypofunctioned teeth will receive physiologic mechanical stimuli. This study evaluated the bone changes around the maxillary teeth opposing an implant restoration installed in the mandibular posterior area. Materials and Methods: Radiographs of the opposing teeth were taken at prostheses delivery (baseline), 3 and 6 months later. A customized film holding device was fabricated to standardize the projection geometry for the serial radiographs of the opposing teeth. The gray values of the region of interest of each digital image were compared according to time. Repeated measured analysis of variance was performed at the 95% significance level. Results: The gray values of the alveolar bone around the antagonist teeth of implants increased with time. The changes in gray values of the middle area were greater than those of the crestal area. However, the gray values of the mesial and distal areas were not different. The changes in gray values were different according to the unloaded time. Conclusion: A change in bone tissue will occur if a proper physiologic load is again applied to the bone tissues around a hypofunctioned tooth.

• Journal of Biomedical Engineering Research
• /
• v.16 no.3
• /
• pp.309-316
• /
• 1995

RF (radio-frequency) probes of Nuclear Magnetic Resonance are one of the important factors and should be designed and built properly depending upon the geometry of the samples and the information. In general there are two kinds of rf probes : one encircles the sample while the other is placed on the surface of the sample. However, in case that the samples on human internal organs have a tube shape, the two kinds of rf probes, as specified above, are usually unsuitable for the internal imaging due to the degradation of signal-to-noise ratios (SNR's). In this case a probe should be positioned as close to the area as possible by putting the probe in the tubelike sample to improve filling factor In the present study inside-out probes have been constructed in the three different shapes such as an anti-solenoidal, a saddle and a dual surface types. RF-field distributions have also been calculated depending upon the geometrical changes of anti-solenoid probes. Moreover, the performance of the inside-out probes has been checked by measuring SNR's of the images acquired. The inside-out probes constructed in this study produced better SWR's and rf-field uniformity in the area close to the probes in comparing with any other commercial probes. There is a high feasibility that the constructed probes in the present study are applicable to the diagnosis of human bodies.

• Journal of the Korea Concrete Institute
• /
• v.13 no.6
• /
• pp.619-628
• /
• 2001

In building construction, openings of the story-height deep beams are usually required for accessibility and service lines such as air conditioning ducts, drain pipes and electric units. It is known that the main parameters affecting the load bearing capacity of deep beams with web openings are size, shape, location and reinforcements of openings. However, there have been no pertinent theories and national design codes for predicting ultimate shear strength of reinforced concrete deep beams with web openings. In this study, the shear behavior of simply supported reinforced concrete deep beams with web openings subject to concentrated loads has been scrutinized experimentally. A total of 34 specimens, the geometry of openings, its reinforcements and shear span to depth ratio, being taken as the experimental variables, has been cast and tested in the laboratory. The effects of these structural parameters on the shear strength and crack initiation and propagation have been carefully checked and analyzed. From the tests, it has been observed that the failures of all specimens were due to shear mechanism and the ultimate strength of specimens varies according to the location of openings, by which the formation of compression struts between the loading points and supports are deterred. All of the test results of specimens have been compared with the formulas proposed by previous researchers. The results were closely coincident with the formulas given by Ray and Kong's equation except for some X series specimens having a larger dimension of openings beyond the geometric limits of proposed equations.