• Journal of the Society of Naval Architects of Korea
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• v.54 no.3
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• pp.267-273
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• 2017

Pressure hulls of submerged structures are generally designed as circular cylinders, spheres or cones with form of axisymmetric shell of revolution to withstand the high external pressure of deep ocean. The compressive buckling (implosion) due to hydrostatic pressure is the main concern of structural design of pressure hull and many design codes are provided for it. It is well-known that the buckling behavior of thin shell of revolution is very sensitive to the initial geometric imperfections introduced during the construction process of cutting and welding. Hence, the theoretical solutions for thin shells with perfect geometry often provide much higher buckling pressures than the measured data in tests or real structures and more precise structural analysis techniques are prerequisite for the safe design of pressure hulls. So this paper dealt with various buckling pressure estimation techniques for unstiffened circular cylinder under hydrostatic pressure conditions. The empirical design equations, eigenvalue analysis technique for critical pressure and collapse behaviors of thin cylindrical shells by the incremental nonlinear FE analysis were applied. Finally all the obtained results were compared with those of the pressure chamber test for the aluminium models. The pros and cons of each techniques were discussed and the most rational approach for the implosion of circular cylinder was recommended.

• Restorative Dentistry and Endodontics
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• v.42 no.4
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• pp.273-281
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• 2017

Objectives: The aims of this study were to quantify tug-back by measuring the pulling force and investigate the correlation of clinical tug-back pulling force with in vitro gutta-percha (GP) cone adaptation score using micro-computed tomography (${\mu}CT$). Materials and Methods: Twenty-eight roots from human single-rooted teeth were divided into 2 groups. In the ProTaper Next (PTN) group, root canals were prepared with PTN, and in the ProFile (PF) group, root canals were prepared using PF (n = 14). The degree of tug-back was scored after selecting taper-matched GP cones. A novel method using a spring balance was designed to quantify the tug-back by measuring the pulling force. The correlation between tug-back scores, pulling force, and percentage of the gutta-percha occupied area (pGPOA) within apical 3 mm was investigated using ${\mu}CT$. The data were analyzed using Pearson's correlation analysis, one-way analysis of variance (ANOVA) and Tukey's test. Results: Specimens with a strong tug-back had a mean pulling force of 1.24 N (range, 0.15-1.70 N). This study showed a positive correlation between tug-back score, pulling force, and pGPOA. However, there was no significant difference in these factors between the PTN and PF groups. Regardless of the groups, pGPOA and pulling force were significantly higher in the specimens with a higher tug-back score (p < 0.05). Conclusions: The degree of subjective tug-back was a definitive determinant for master cone adaptation in the root canal. The use of the tug-back scoring system and pulling force allows the interpretation of subjective tug-back in a more objective and quantitative manner.

• Journal of Korean Society of Forest Science
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• v.97 no.5
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• pp.516-524
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• 2008

We investigated on the distribution of nutrient contents (N. P and K) in current and one-year old needles of Korean pine, Pinus koraiensis, to understand the physiological effects of alternate bearing. One experimental set was designed with three types of cone number (one, three and five) under natural state and cone number of another one was controlled by thinning. Test samples were separated to collect into three fractions; current needles on the shoot and one-year old needles above and under the cone. On the branch without cone, N, P and K concentrations in needles on the shoot were higher than those in needles of one-year old branch. At natural state, needle P concentration was the lowest in needles on the five-cone branch in August. Macronutrient concentrations were the lowest in needles above the cone, which was remarkably observed in needle K concentration. Under cone thinning, N. P and K concentrations were the highest in needles on one-cone branch and the lowest in needles on five-cone branch. Needle nutrient concentrations were the lowest in needles above the cone, which was remarkably observed in the needle on five-cone branch. In conclusion, the current needles of the shoot and cones are a strong sink of nutrient like N. P and K, and the increase of cone number influences nutrient removal from needles.

• Journal of Acupuncture Research
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• v.28 no.1
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• pp.15-28
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• 2011

Objectives : To understand the strength and weakness of traditional warm needle acupuncture based on existing research outcomes in Korea mostly and to suggest how to build the desirable warm needle acupuncture apparatus by overcoming demerits of traditional and currently existing ones. Methods : We searched warm needle relating papers in Korean with the key words of '온침, 화침, 열자극' by using DBpia, Journal of Korean Oriental Medical Society, Journal of Korean Acupuncture & Moxibustion Society and Journal of Society for Meridian and Acupoint. Degree dissertations in Korean were also searched with the same words through the search engine of Library of Kyung Hee University. We also searched with words of 'warm, thermal, heat, needle, acupuncture, temperature' via Pubmed and found a small number of English written papers and large number of Chinese written ones. To find english translated version of those papers, we googled with the same words with no success. Results : About 20 papers on warm needle acupuncture written in Korean were found and analyzed with respect to experimental factors that affected the thermal properties or the amount of heat stimulus of the acupuncture. More rigorous descriptions seemed to be required on the insertion depth, duration and manipulation of warm needle treatment. A basic heat transfer model was presented for the clarification of heat loss through the needle of warm needle acupuncture. Environmental factors such as air flow on the properties seems to be considered for the warm needle acupuncture. Conclusions : Papers on warm needle acupuncture were reviewed and analyzed based on their thermal properties and tools such as needles and moxa cones. Several suggestions were made on the descriptions relating the properties. Necessary specifications were introduced to aim modernized warm needle systems.

• Imaging Science in Dentistry
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• v.33 no.3
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• pp.137-141
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• 2003

Purpose: To evaluate the precision of measurements taken of dental implants in bucco-lingually sectioned views of the maxilla by linear tomograms of the panorama and to assess the visibility of the inferior wall of the maxillary sinus. Materials and Methods : Eighty sites prepared with implants of gutta percha cone in the sockets of the upper premolars and molars of 10 dry skulls were radiographically examined using linear tomograms of panorama, and scanned coronally and axially by computed tomography. The differences in mm between the measurements in bucco-lingually sectioned images of maxillary alveolar bone and the true length and width of the implanted gutta percha cones were compared as mean values (mean) and standard deviations (SD) for each radiographic technique. Linear tomography of panorama was compared with computed tomography for visualization of the relationship between the inferior wall of maxillary sinus and the end of each implant. Results: The deviations between the actual implant length and the measured values taken from the linear tomograms (0.44±0.39 mm) was significantly less than the measured values from the multiplanar reconstructed images of the axially scanned computed tomogram (1.21 ± 0.90 mm). There was statistically significant difference (p < 0.05) between two techniques in the differences between the measurements and true implant length. The relationship of the inferior border of maxillary sinus with end of implant was worse identified with the linear tomogram of panorama (68%) than the multiplanar reconstructed image of axially scanned computed tomogram (99%). Conclusion: We could not find any differences in the accuracy of length measurement between the linear tomogram of panorama and computed tomogram, but computed tomogram allowed for a better visualization of the inferior wall of the maxillary sinus than the linear tomogram.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.3
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• pp.429-438
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• 2018

Cone and T-bar penetrometers have been frequently used to estimate the undrained shear strength of clay. For small-size model tests, miniature penetrometers should be used but their correlation factors have not been well published. In this study, a testing setup was developed to derive empirical factors of the miniature cone and T-bar penetrometers. A 350mm-diameter chamber and kaolin clay were utilized to prepare soil specimens consolidated under four different pre-consolidation pressures controlling undrained shear strength. Two miniature cones with two diameters of 10-mm and 16-mm and a T-bar penetrometer with 10-mm diameter were used to investigate boundary effect, penetration rate effect, and diameter and shape effect. Unconsolidated-undrained triaxial tests were carried out with samples taken from the specimens to measure undrained shear strength. Finally, empirical factors for the penetrometers were constructed to correlate tip resistance to undrained shear strength.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.5
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• pp.1356-1361
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• 2004

Moxa-combustion therapy make use of heat stimulus and chemicals result form when cauterize the skin with moxa cones to medical cares. However, recently moxibustion have been utilized less than acupuncture for treatment of disease in a practicing oriental physicians. To determine variable parameters (the numbers, the times, the quantities, the locations) affected moxibustion's effects, the gastrin serum level in rats were observed. In experiment, male Spraque-Dawley rats (body wt. 140-160g) were selected. Anything is performed to normal group. Control group were only anesthetized with inhalation in normal group. Experimental group were anesthetized and cauterized with moxa at BL21 by way of direct moxibustion. The size of moxa cone is 1.6±0.2㎎. The moxibustion as 5 times a day for five days has shown most significant effects and the moxibustion as a aquantity of 1, 5, 10 times moxa united one respectly, inverse to quantity in effects. The moxibustion for five days has also shown an most significant effects. The moxibustion at unilateral acupoints BL21 have less effects than bilateral one and these effects had no difference between control group after vagotomy. This results indicate that moxibustion's effects are not direct proportion to moxa cone size and frequency but imply that there is adequate value of moxibustion.

• Journal of the Korean earth science society
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• v.28 no.7
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• pp.847-856
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• 2007

The Planetary nebula NGC 6881 displays quadrupole morphology and it also has a jet feature in its image. We investigated the line profiles of the optical region spectral emission lines, using the Hamilton Echelle Spectrograph (HES) at the Lick observatory. The HES data obtained in this study was the radiation coming from the inner region within the diameter of 4 second of arc. Expansion velocity was obtained, based on the strong emission line profiles of e.g. H, Hel, Hell, [OIII], [NII], [ArIII], [SII], and [SIII}, using the IRAF and StarLink/Dipso reduction packages. The HI recombination lines showed one single peak profile, while the He and forbidden strong lines displayed double peaks. The results of this study show that the outflow velocity of gas increases radially outwards due to the central stellar radiation pressure. It was concluded that three central rings appeared in the HST image are the result of a combined structure of bipolar cones (seen in e.g. HI lines) and a ring (seen in He, [SIII] lines) in projection.

• The Journal of Korean Society for Radiation Therapy
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• v.8 no.1
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• pp.29-35
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• 1996

We are often faced with the clinical situations that is inevitably extended SSD for electron beam therapy due to anatomical restriction or applicator structure. But there are some difficulties in accurately predicting output and properties. In electron beam treatment , unlike photon beam the decrease in output for extended SSD does not follow inverse-square law accurately because of a loss of side scatter equilibrium, which is particularly significant for small cone size and low energies. The purpose of our study is to analyze the output in changing with the energy, cone size, air gap beyond the standard SSD and to compare inverse-square law factor derived from calculated effective SSD, mominal SSD with measured output factor. In addition, we have analyzed the change of PDD for several cones with different SSDs which range from 100cm to 120cm with 5cm step and with different energies(6MeV, 9MeV, 12MeV, 16MeV, 20MeV). In accordance with our study, an extended SSD produces a significant change in beam output, negligible change in depth dose which range from 100cm to 120cm SSDs. In order to deliver the more accurate dose to the neoplastic tissue, first of all we recommend inverse-square law using the table of effective SSDs with cone sizes and energies respectively or simply to create a table of extended SSD air gap correction factor. The second we need to have an insight into some change of dose distribution including PPD, penumbra caused by extended SSD for electron beam therapy.

• Ocean and Polar Research
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• v.24 no.4
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• pp.491-500
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• 2002

Magnetic anomalies in the Dokdo and it's surroundings were investigated with respect to structure and origin of the Dokdo and surrounding seamounts. After normal and diurnal correction of measured magnetic data, crossover correction was applied to reduce errors between sets of magnetic anomalies. The errors from crossover operation result in decrease of about 51%, from 62.2 nT to 30.1 nT in standard deviation. Reduction-to-the-pole, second vertical derivative and analytic signal processing were applied to explore magnetic anomaly signatures in detail. Magnetic anomalies are most complicated in the 1st-Dok seamount, show SWW-NEE linear pattern in the 2nd-Dok seamount and lower to the 3rd-Dok seamount. Different magnetic anomaly patterns in three seamounts imply that three volcanic seamounts were formed at different times and are composed of rocks that were produced in different conditions. It seems that the 3rd-Dok seamount was first to form and followed by the 1st-Dok seamount. The complicated magnetic and second vertical derivative anomaly patterns in the 1st-Dok seamount may be due to subsidiary cones around crater or the presence of intruded magma bodies below sea surface and the Dokdo is probably a marginal subsidiary part of crater.