• Journal of the Korean Society of Radiology
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• v.5 no.2
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• pp.51-58
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• 2011

This research compared and analyzed the heart rate of the patient in which the LVEF value is 40% less than and normal patient. When as for LVEF 40% or less becomes to each heart rate and LVEF in a relation, we can know that the time to reach 100HU hangs long. Therefore, in patients, that is 40% less than, when setting up the Premonitoring delay, we could know to could give 5 primary solid phrases. It is seen that subsequently an addition injected 40cc as to Saline, to all patients by 4cc/sec speeds after injecting the capacity of Scan time ${\times}$ 4cc + 30cc with 4cc/sec speeds. And HR excludes 80 or greater in 40% less than, the contrast agent shows the large-scale difference. In addition, in 40% less than, it could predict that the time difference was big and the contrast agent was already out in the Left ventricle Wash- when the contrast agent reached 100HU and Scan was started There is a wide difference between under 40% LVEF and normal. when starting scan from low LVEF patients. So, Injection contrast media protocol Should be determined to CCTA. And then In case of low LVEF is recommended to more low Pitch than routine Pitch because we should reduce scan failed in accordance with low LVEF.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.1
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• pp.21-28
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• 2020

In this paper, a new type of electric wheelbarrow is proposed and developed. The developed electric wheelbarrow is equipped with an attitude reference system(ARS) sensor, which consists of 3-axis acceleration sensor and 2-axis Gyro sensor so that it can estimate pitch angle and roll angle. When an operator tilts the wheelbarrow up and down, the pitch angle is detected. The sign of the pitch angle is interpreted as the operator's intention for moving the wheelbarrow forward or backward and the controller drives the wheel of the wheelbarrow with the velocity according to the magnitude of the detected pitch angle. A cargo box of the wheelbarrow is designed to rotate and is controlled to maintain level always, so an operator can handle the electric wheelbarrow easily and safely. The wheelbarrow consists of an in-wheel motor, a DC motor, motor drives, an ARS sensor considering economical use in industrial field. Three experiments are performed to verify the feasibility and stability of the electric wheelbarrow.

• The Korean Journal of Air & Space Law and Policy
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• v.23 no.2
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• pp.115-136
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• 2008

The development of the aviation technology is beyond the people's imagination. For example, with some exaggeration, If the autopilot engage upon take off, You will realize that you are on the centerline of the foggy JFK runway 13R after 15 hours with only once or twice of intervention. But the more aviation technology develops, the more responsible the pilot will be who has the final authority of the aviation safety. In the JAL 706 accident caused by unidentified reason, the pilot increased pitch abruptly and overrode the control from the autopilot. The result of this process made the death of a flight attendant and some injuries of a few passengers. The district court found the pilot not guilty at the first trial on the ground that the control override was not connected to the possibility of foresight and avoidance of the human death. The pilot was proved to be innocent through the analysis of the DFDR and ADAS that the override did not precede the unidentified pitch up motion. The judicial precedent related to aviation accidents in Korea requires pilots' absolute and extended care compared to the ordinarily prudent or reasonably careful behaviors in the vehicle and medical accidents. Although there is some controversy about the standard care, the care required in the actual operation of high tech aircraft by a pilot should include objective and standard care and be judged by analysis of the scientific data. Although the pilot maintained the unusual hi speed that doesn't have safety margin and descended under turbulence in case of the JAL 706 accident, the court negatived its relation to the cause of pitch up. Also, the override of the control after initial pitch up might have caused the possibility of the death and injury, but the court denied it. Because of this complex cause of the aviation accidents, it is important for a court to figure out the core reason of the event and casual relationship with the pilot Now, It is required that the judgement of negligence in the aviation accidents should include an objective care with scientific data from simulated circumstances(or a simulator) as the Japanese court not from the theory of vehicle's negligence.

• Journal of Welding and Joining
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• v.15 no.4
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• pp.143-153
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• 1997

In this study, bending test was performed on the real-scale, built-up beam test model fabricated by the $CO_2$ arc spot welding to evaluate the applicability of the welding method to the production of the stiffened plate in car-carrying ship. The built-up beam models which were fixed at both ends in longitudinal direction or simply supported to the rigid foundation, depending on the restraint condition of the corresponding car decks considered, were subjected to simulated design vehicle loads or concentrated point loads. During the test, the central deflection and the longitudinal bending stresses were measured from several points on the longitudinal flange face to predict the section properties of the built-up beams. The longitudinal bending stress on each spot weld were also measured to calculate the average horizontal shear force subjected to spot welds. Test results revealed that the shear strength of spot welds with their current weld nugget size and welding pitch was adequate enough to withstand the horizontal shear forces under the design vehicle loads. Although the built-up beam fabricated by the arc spot welding was a discontinuous beam, its mechanical behavior was well explained by the continuous beam theory using the effective breadth of plate. Based on test results, the criterion for the size of spot weld of which the average shear stress might meet the allowable stress requirement of AWS Code could be established.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.10-15
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• 2023

Wet multi-disk clutch, a power switching device of the ducted fan, was optimized and results were analyzed. The clutch was divided into two types depending on whether a mechanical lock-up was applied or not. It was optimized under each design condition. Transfer torque capacity, friction material surface pressure, friction surface temperature, and drag torque were calculated as factors to optimize the clutch. The volume of separator plate and drag torque were used as the objective function for optimization. In the case of Type 1, which did not include a mechanical lock-up, the clutch could be operated regardless of the pitch angle of the ducted fan. However, the outer diameter of the friction surface was doubled, the volume was increased by 5~7 times, and the drag torque was increased by 7~12 times compared to those of Type 2, which included a mechanical lock-up.

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.194-205
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• 1994

In this research, we attempt to fabricate an excellent CFRC(Carbon Fiber Reinforced Carbon), which has good thermal and mechanical properties, with 8H/satin woven fabric prepreg, high modulus and high strength type continuous carbon fiber and raw coal tar pitch(RCTP) matrix or THF soluble fraction(THFSP) matrix which has good graphitizability. Green bodies were fabricated with hot press molding technique and CFRC samples were made after carbonization, impregnation, recarbonization and graphitization steps. For the purpose of characterization of the physical properties, SEM, polarized light microscope, TGA were observed, and tested flexural strength, modulus and ILSS. After heat treating the THFSP matrix up to $2300^{\circ}C$, the value of $C_0$/2 was 3.380$\AA$, which is analogous to the structure of natural graphite and the value of 2$\theta$ is $26.276^{\circ}$ approached to the Bragg's angle of natural graphite. As a result of TGA to test the high temperature air oxidation, the THFSP matrix, graphitized up to $2300^{\circ}C$, exhibited the best air oxidation resistance. And mechanical properties were increased up to 65~70% as fiber volume fraction increased. Because of the good orientation graphitizability, the fracture surface of THFSP matrix CFRC is very good.

• Journal of Korean Society of Forest Science
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• v.78 no.4
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• pp.381-395
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• 1989

The main purpose of this research is to provide scientific informations about standard wage and performance tariffs in forest management with special reference to working time for thinning. To identify relationships between net working time and tree characteristics, three geographically different sample plots were established at Yangsan, Bongpyung and Jinan and 460 oaks, 372 Japanese larches, 232 red pine and 240 pitch pine mere selected at each sample plots. The results of statistical analysis using multiple regression are as follows ; 1. Five independent variables of breast height diameter(DBH), mid-diameter(MD) large end diameter(LD), log-length(L), No. of branches(NOB) were stable independent of worker and tree species. 2. Comparing correlation coefficient of five independent variables, the best predictive variables, breast height diameter and No. of branches, were selected. Breast height diameter and No. of branches were identified as the most important independent variables in terms of effect on the dependent variable of the working time. 3. Comparing coefficient of determination (Rp) and residual mean square (MSEp), the best Linear regression equation for each tree species was selected as follower : $WT=a+b1{\times}NOB+b2{\times}DBF$ 4. Proportion of hang-up time to total working time in thinning were 66% in oak stand, 74%, in Japanese larch stand, 55%, in red pine stand and 52% in pitch pine stand, respectively. 5. Based on the best regression equation, a table of working time was made by strata of number of branches and breast height diameter. 6. Total working time using the best regression equation in Table 5 can be predicted in terms of felling time, limbing time, hang-up time, i.e., total working time increases by 11 to 13 seconds with every 1 centimeter increase in breast height diameter from 7 to 16 centimeter.

• Speech Sciences
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• v.8 no.2
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• pp.39-48
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• 2001

The purpose of this study was to examine changes in acoustic characteristics after drinking alcoholic beverages and singing in order to establish guidelines for vocal hygiene of both singers and non-singers. 21 university students (10 males and 11 females) vocalized /a/ before drinking, after drinking and after singing. Changes in vocal range and acoustic characteristics were analyzed by Dr. Speech 4.0 (Tigers Electronics). No significant difference was observed in vocal range following drinking. However, there was statistically significant changes in vocal range after singing. We may infer that appropriate amount of singing functioning as vocal warm-up, rather than drinking alone, resulted in improvement in their abilities to lengthen vocal folds. This is directly related to the ability to produce high-pitched sounds. Changes in jitter in female voices after singing was the only acoustic factor that was significant. Changes in Shimmer and NNE was not significant either after drinking nor singing. Subjects who were judged to perform better in singing were marked by minimum acoustic changes, which may due to their well-trained vocal fold function. The results of this study may address the necessity for vocal function exercises for the patients with neurogenic voice disorders including dysarthria. The need for more extensive research with a larger number of subjects including professional voice users is also addressed.

• 보존과학연구
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• s.25
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• pp.171-195
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• 2004

This research presents an evaluation of the weathering and deterioration state of the Wanggung-ri five-storied stone pagoda in the Iksan (National Treasure No. 289) and suggests conservational schemes. A deterioration map of the pagoda was drawn from the aspects of petrological, physical, chemical, biological, structural and artificial weathering.The rock properties consisting of the pagoda were medium-grained biotite granite that had leucocratic phenocryst developed in parts. The body of each story suffered severely from the secondary contamination that turned the colors into light grey, pitch dark, yellowish brown, and reddish brown as well as granular decomposition, exfoliation and peel-off. The roof stones were heavy exfoliated or peeled off in most of the cases. In addition to the fine cracks, there were layered cracks on the corners. The roof stones of the3rd and 4th story in the north and west side had some stones fall-off, while those of the 2ndstory in the north side had steel reinforcement filled for a fixing purpose. Those of the 5th story showed big gaps that must have originated from cracks and were easily subject to granular decomposition and rainfall. The inside clay filler was missing in the lower part of the roof stones of the 4th and 5th story and the supporting stones, which were thus covered by light grey or pitch dark sediments. The contact area of the materials was about 70 % in the parts where there was a space due to the filler missing and washigher than 90 % in the lower parts of the pagoda. About 90 % or more of the roof stones surface of each story were covered by aerial plants that formed a thick biological mat. Thus it seemed necessary to come up with the conservational measures to remove the plans living on the surface of the stone materials, with the plans to prevent rain from falling inside, and with the water repellent and hardening treatments to postpone the surface weathering of the rock properties. All those measures and plans must be based on the results of long-term monitoring and thorough detail investigations.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.1
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• pp.35-44
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• 2015

Thermomechanical pulping process uses large amounts of energy, mostly electricity to run electrical facilities. Thermomechanical pulp (TMP) made from Pinus densiflora also has a big drawback that refining consumes 90 per cent of the total energy used in TMP process. This study explored to draw up a way to save refining energy through different thermal treatment at the stages of presteaming and refining. Presteaming temperature was $80^{\circ}C$, $100^{\circ}C$, and $120^{\circ}C$. After presteaming at each temperature, refining was carried out at $100^{\circ}C$, $120^{\circ}C$, and $140^{\circ}C$ respectively. In a presteaming stage, steaming temperature over $120^{\circ}C$ greatly contributed to the decrease of refining energy leading to earlier attainment of a target freeness, irrespective of refining temperature. In addition, NaOH treatment with presteaming enhanced better development of fiber properties during refining than presteaming without NaOH. High temperature refining at $140^{\circ}C$ produced a high strength paper, and wood chips treated by alkali responded better to refining than at over $120^{\circ}C$. Improved softening effect on wood chips led to the decrease in shives contents but it gave no effect on pitch contents of TMP.