• Progress in Superconductivity and Cryogenics
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• v.25 no.4
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• pp.32-39
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• 2023

One of the main problems faced in developing India's first HTS power cable was that of shrinkage in length of the double-walled vacuum-insulated cryostat. The shrinkage was due to the evacuation of the annular vacuum space which results in a shorter working cable length. This work reports experimentally observed contraction during evacuation and analyses corrugated pipes/bellows which house the cable core of HTS cables. The effect of corrugation geometry including length, corrugation pitch and depth, diameters of corrugated pipes and thicknesses of pipes is studied numerically to realize the degree of shrinkage due to vacuum as well as chill down. Finally, necessary length compensation and associated cost is determined to tackle the shrinkage issue.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.45.2-45.2
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• 2010

We analyzed onset times of the largest six solar proton events during 1997-2006 of solar cycle 23, as observed at 1AU by two satellites of GOES/SEM (Geostationary Operational Environmental Satellites/the Space Environment Monitor) and SOHO/ERNE (Solar and Heliospheric Observatory/the Energetic and Relativistic Nuclei and Electron). We adopted the time shifted method suggested by Leon Kocharov and determined the path length by Sam Krucker's fitting method. We found some problems of those methods and tried to improve those. In this presentation, we will give details of the energy spectra of the 6 SPE events from the ERNE/HED, and onset time comparison among the SPE, flare, type II burst, and CME.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1048-1055
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• 2005

The formula to calculate a variation of optical path length of single crystal by the electric field was derived by this study. The formula was applied to $Bi_{12}SiO_{20}$ single crystal. The results are as follows. In case of the applied electric field in the body diagonal direction and the passing light along the same direction, the variation of optical path length had the largest value. The symmetry of the space distribution of optical path length satisfied $E3C_2\;8C_3$, the set of elements of the symmetry of $Bi_{12}SiO_{20}$ single crystal. The property which gave the largest influence to the variation of optical path length is the strain of length by the Inverse piezoelectric effect. The second influence, is the variation of the refractive index by the electro-optic effect. The variation of optical path length by the inverse piezoelectric effect and by the electro-optic effect have a reverse sign each other.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.8 s.101
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• pp.897-903
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• 2005

When driving on uniformly tining concrete pavement road, the whine noise which has high spectrum at the specific frequency related to the uniform tining space exist. In this paper, a randomization method of tining space for concrete pavements is proposed to reduce the whine noise. The proposed method is developed based on the LCG(linear congruential generator) algorithm. The design parameters used in the method are number of different tining space, ratio of each tining space, total linings of each size. sequence of actual tining under given constant drag length and texture. Monte Carlo simulations are used to validate the proposed method.

• Carbon letters
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• v.15 no.1
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• pp.25-31
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• 2014

A microstructure analysis is carried out to optimize the process parameters of a randomly oriented discrete length hybrid carbon fiber reinforced carbon matrix composite. The composite is fabricated by moulding of a slurry into a preform, followed by hot-pressing and carbonization. Heating rates of 0.1, 0.2, 0.3, 0.5, 1, and $3.3^{\circ}C/min$ and pressures of 5, 10, 15, and 20 MPa are applied during hot-pressing. Matrix precursor to reinforcement weight ratios of 70:30, 50:50, and 30:70 are also considered. A microstructure analysis of the carbon/carbon compacts is performed for each variant. Higher heating rates give bloated compacts whereas low heating rates give bloating-free, fine microstructure compacts. The compacts fabricated at higher pressure have displayed side oozing of molten pitch and discrete length carbon fibers. The microstructure of the compacts fabricated at low pressure shows a lack of densification. The compacts with low matrix precursor to reinforcement weight ratios have insufficient bonding agent to bind the reinforcement whereas the higher matrix precursor to reinforcement weight ratio results in a plaster-like structure. Based on the microstructure analysis, a heating rate of $0.2^{\circ}C/min$, pressure of 15 MPa, and a matrix precursor to reinforcement ratio of 50:50 are found to be optimum w.r.t attaining bloating-free densification and processing time.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.4
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• pp.176-180
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• 2015

Objectives: The increased prevalence of antibiotic resistance is an outcome of evolution. Most patients presenting with odontogenic space infections also have associated systemic co-morbidities such as diabetes mellitus resulting in impaired host defense. The present study aims to compare the odontogenic spaces involved, antibiotic susceptibility of microorganisms, length of hospital stay, and the influence of systemic comorbidities on treatment outcome in diabetic patients. Materials and Methods: A 2-year prospective study from January 2012 to January 2014 was conducted on patients with odontogenic maxillofacial space infections. The patients were divided into two groups based on their glycemic levels. The data were compiled and statistically analyzed. Results: A total of 188 patients were included in the study that underwent surgical incision and drainage, removal of infection source, specimen collection for culture-sensitivity, and evaluation of diabetic status. Sixty-one out of 188 patients were found to be diabetic. The submandibular space was the most commonly involved space, and the most prevalent microorganism was Klebsiella pneumoniae in diabetics and group D Streptococcus in the nondiabetic group. Conclusion: The submandibular space was found to be the most commonly involved space, irrespective of glycemic control. Empiric antibiotic therapy with amoxicillin plus clavulanic acid combined with metronidazole with optimal glycemic control and surgical drainage of infection led to resolution of infection in diabetic as well as nondiabetic patients. The average length of hospital stay was found to be relatively longer in diabetic individuals.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.39-45
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• 2002

The effect of reefing-line length and reefing methods on drag and inflated shape of the conical ribbon parachute were experimentally investigated. Tests were performed to determine reefing-line length of the parachute models, demonstrate aerodynamic adequacy of the reefing method, and confirmed that performance met the design requirement. The reefing ratio, drag-area ratio, was decreased in relation to the decrease in the length of the reefing-line and the stability of the parachute models was increased with reefing. The test results were compared with the avilable similar data. Fair to good agreement was obtained.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.79-86
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• 2005

The role of the injector as an acoustic resonator is studied for the high performance rocket engine adopting the gas-liquid scheme injector. Acoustic behavior in the combustor with single injector is investigated numerically adopting linear acoustic analysis for cold condition. Acoustic-damping effect of the injector is evaluated by damping factor as a function of the injector length. From the numerical results, it is found that the injector can play a significant role in acoustic damping and the optimum length of the injector corresponds to half of a full wavelength of the longitudinal mode with the acoustic frequency to be damped in the chamber. In baffled chamber, the optimum lengths of the injector are calculated as a function of baffle length for both cold and hot conditions.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.1
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• pp.71-82
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• 2011

This paper presents the tensile strength of shotcrete steel fibers depending on the shape of steel fiber. The experimental and numerical analyses are performed in this study. In experimental study, a series of laboratory pullout tests are carried out by changing both the angle and the length of the embedded steel fiber according to the corresponding type of steel fiber in order to derive the optimal type of steel fiber. Results obtained from the experimental work are evaluated and compared with the numerical analysis results. The results clearly show that the pull-out strength of the steel fiber are increased with increasing the hook angle and embedded angle of steel fiber. It is also found that the pull-out strength of the steel fiber is larger in case of the short steel fiber body length.

• Journal of Animal Environmental Science
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• v.8 no.3
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• pp.171-176
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• 2002

Physical parameters of milk cow were measured to design and build RMS(Robotic Milking System) with a tape-measurer and body parameter measurer. The parameters are very important variables to design an RMS. For the working zone space of an RMS manipulator and the movement blunting of milk cow, an interval frame was installed on the stall bottom, and then cow's behavioral reactions were tested. The results from this study is summarized as follow. 1. On the general physical condition measurement, the maximum, minimum and average body length of cow which is related to the space that the manipulator could work into the RMS were 175cm, 144cm, and 163cm respectively. It appeared that the average distance between bottom and chest was 60cm. 2. The average length between fore teats, fore and hind teats and hind teats were 178mm, 150mm and 95mm respectively. It appeared that the average length between bottom and teat attachments was 544mm, and the average length between fore teats and tail-end was 331mm. 3. Although a cow kept a some extent length between hind legs for milking, it looked a stable pose. However, the cow kept a some extent distance between front legs for milking, it looked a unstable pose. Based on results of this test, an interval frame of stall bottom should be installed around the position which was located at its hind legs.