• Structural Engineering and Mechanics
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• v.21 no.3
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• pp.351-367
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• 2005

Multi-span beams carrying multiple point masses are widely used in engineering applications, but the literature for free vibration analysis of such structural systems is much less than that of single-span beams. The complexity of analytical expressions should be one of the main reasons for the last phenomenon. The purpose of this paper is to utilize the numerical assembly method (NAM) to determine the exact natural frequencies and mode shapes of a multi-span uniform beam carrying multiple point masses. First, the coefficient matrices for an intermediate pinned support, an intermediate point mass, left-end support and right-end support of a uniform beam are derived. Next, the overall coefficient matrix for the whole structural system is obtained using the numerical assembly technique of the finite element method. Finally, the natural frequencies and the associated mode shapes of the vibrating system are determined by equating the determinant of the last overall coefficient matrix to zero and substituting the corresponding values of integration constants into the related eigenfunctions respectively. The effects of in-span pinned supports and point masses on the free vibration characteristics of the beam are also studied.

• Structural Engineering and Mechanics
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• v.22 no.6
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• pp.701-717
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• 2006

In the existing reports regarding free transverse vibrations of the Euler-Bernoulli beams, most of them studied a uniform beam carrying various concentrated elements (such as point masses, rotary inertias, linear springs, rotational springs, spring-mass systems, ${\ldots}$, etc.) or a stepped beam with one to three step changes in cross-sections but without any attachments. The purpose of this paper is to utilize the numerical assembly method (NAM) to determine the exact natural frequencies and mode shapes of the multiple-step Euler-Bernoulli beams carrying a number of lumped masses and rotary inertias. First, the coefficient matrices for an intermediate lumped mass (and rotary inertia), left-end support and right-end support of a multiple-step beam are derived. Next, the overall coefficient matrix for the whole vibrating system is obtained using the numerical assembly technique of the conventional finite element method (FEM). Finally, the exact natural frequencies and the associated mode shapes of the vibrating system are determined by equating the determinant of the last overall coefficient matrix to zero and substituting the corresponding values of integration constants into the associated eigenfunctions, respectively. The effects of distribution of lumped masses and rotary inertias on the dynamic characteristics of the multiple-step beam are also studied.

• Journal of Veterinary Clinics
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• v.27 no.4
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• pp.468-473
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• 2010

A 6-year-old intact male Doberman pinscher presented with a thin soft stool and urinary signs. On radiography, three masses were observed in the caudal abdomen. One mass was described as a large, round, mineralized mass, with an "eggshell" appearance. The second mass was located caudal to the mineralized mass, and the third mass was located between the two masses. The second and the third masses had a soft tissue density. Ultrasonography was performed to identify the features and the origins of the masses. The first mass contained a large amount of anechoic fluid and had a thin wall; it was determined to be a cyst. Strong acoustic shadowing artifact was created by the mineralized cystic wall. Caudal to the cyst, the second mass was shown to be the prostate. A hypoechoic stalk connected the prostate and the cyst, which represented the cyst as a paraprostatic cyst with mineralization. The third mass was the normal urinary bladder. The cyst was removed surgically and confirmed by histopathologic examination. This report described typical clinical findings, diagnostic imaging, and treatment of a paraprostatic cyst.

• Economic and Environmental Geology
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• v.17 no.1
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• pp.57-78
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• 1984

The object of this study is to offer the standarized data for the design and calculating engineering cost of the rock excavation an the construction of the 3rd and 4th Seoul Subway lines From Jnauary to March in 1983, this study was carried out by the both methods of the field and laboratary studies. In the field, the geological survey in the entire area of Seoul City and sites on the subway lines were carried out and also a site measure of uniaxial compressional strength of rock masses by using Schmidt hammer was done. The labartory studies were carsied out by a study of preuions surveyes, microscopic studies of the mineral composition and degree of weathering of rocks, and measure of uniaxial compressional strengths Finally an engineering classification of each rock masses of South Africa council for Scientific and Industrial Research, CSIR, after Bieniawski, 1974. was done. In this method of classification 6 parameters such as strength of intact rock material, rock quality designation, spacing of fractures, condition of fractures, groundwater conditions, and the effect of fracture strike and dip orientation in tunnelling were used to evaluate rating of each rock mass.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.3
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• pp.286-295
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• 2016

With the results of observations in 2013 and 2014 including ocean buoys, in-situ investigations and wind data, we examined the spatio-temporal variation of cold water masses along the eastern coast of Korea. Usually, a cold water mass first appears along the northern part of the eastern coast from May to July, and then along the southern part of the eastern coast from late June to mid-August. Cold water masses appear 3~5 times a year and remain for 5~20 days in the southwestern part of the East Sea. A distinctive cold water mass appeared usually in mid-July in this area, the surface temperature of which was below $10^{\circ}C$ in some cases. During the appearance of a cold water mass in the southwestern part of the East Sea, the horizontal temperature gradient was large at the surface and a significant low water temperature below $8^{\circ}C$ appeared at the bottom level. This appearance of cold water masses clearly corresponded to southwesterly winds, which generated coastal upwelling.

• Korean Journal of Veterinary Service
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• v.21 no.1
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• pp.67-77
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• 1998

The bovine fat necrosis is often seen as an incidental lesion in the adipose tissues of the abdominal cavity. Most of affected animals, however, have been detected at the slaughter house or routine necropsy. The purpose of this study was to examine the occurrence and distribution of abdominal fat necrosis in Korean native cattle, and its pathologic features. Postmortem inspection at an Chonju abattoir during a three-month period in 1997 detected at necrosis lesions in 67(6.6%) of the 1,012 animals received for slaughter. The occurrence was mainly in alimentary tracts and perirenal. Both sexes were affected, but the lesion were predominantly occurred in female. Gross lesions were white or yellowish in color and formed hard lumps irregular in shape ranging from small nodules to large solid masses. On the cut surface, lesions were occasionally seen chalky calcified granules and some of the lesions contained oil-like fluid. The surface of irregular shaped masses constricted kidneys and intestinal loops. Microscopically, the masses were encapsulated by thickened fibrous tissue, which infiltrated deeply and divided them into many irregular lobules. Initial lesions presented mild inflammatory cell and fibrous proliferation. It became fibroplasia in progressive lesions and resembled chronic lesion, eventhough no grossly apparent inflammatory reaction. The hard consistency of masses, due to fibroplasia, can compress the intestines, urinary organs, and reproductive organs.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.490-498
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• 2010

HCFC-22 (chlorodifluoromethane, $CHClF_2$), one of the major components in various refrigeration, is emitted mostly from developing countries, as its consumption is not limited until 2013 by the Montreal Protocol. In addition, HFC-23 (trifluoromethane, $CHF_3$), a by-product in the manufacture of HCFC-22, is also a powerful greenhouse gas. Here, we discuss the regional emission characteristics of these compounds based on high-frequency in-situ measurements using the "Medusa" GC-MS system. HCFC-22 and HFC-23 baseline concentrations measured at Gosan (Jeju Island, Korea) from November 2007 to December 2008 increased by 1.8 ppt/yr and 0.6 ppt/yr, respectively. Pollution events of these compounds were observed, very frequently (e.g., ~2~3 times) at Gosan than baseline levels. All the measurement data were divided into four groups by simultaneously considering the ratio (HFC-23/HCFC-22) and concentration (HCFC-22) at Trinidad Head (TH, California, USA). The residence time of trajectories were then analyzed in each of the four groups. The results exhibited the existence of a strong correlation with air mass origin for each group: 1) Air masses originating from Siberia in the north and from the Pacific in the south had ratios of 0.08~0.12 and concentrations of 196.9~254.3 ppt which is highly comparable to background air at TH. 2) Air masses passing over the Southern China exhibited similar ratios but higher HCFC-22 concentrations. 3) Air masses passing over the Northern China had ratios of 0.12~0.21. 4) Air masses passing over Korea and/or Japan had ratios of 0.01~0.08. Our results suggest that the HFC-23/HCFC-22 ratio can be used as a good indicator for the assessment of the pollution with Chinese origin. We also confirmed differences in air masses traveling over Northern and Southern China, most likely due to differences in air mass travelling speed over these regions before arriving at Gosan. This signature may be treated as one of the critical components in identifying the emission sources from different parts of China.

• Korean Journal of Head & Neck Oncology
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• v.36 no.2
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• pp.69-72
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• 2020

We report a surgically challenging case of a large lipoma located from the temple, across the zygomatic region to the buccal area, resembling two different masses. An 82-year-old man presented with two persistently growing soft masses at his left temple and cheek. A computed tomographic scan revealed a single large radiolucent mass extending from the submuscular layer of the left temple crossing beneath the zygomatic arch to the buccal region, rather than two individual masses. Excision was performed through upper gingivobuccal and temporal incisions. The mass was dissected through both incisions, cut in half, and extracted from both sides. No complications were observed. The biopsy result was consistent with a lipoma. Four months later, the scars were inconspicuous, and the patient was satisfied. Considering the size, shape, and location, this is a rare and intriguing case. The bi-directional approach allowed for successful total excision without any complications, leaving inconspicuous scars.

• Ocean and Polar Research
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• v.27 no.3
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• pp.277-288
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• 2005

Spatial distribution and vertical structures of water masses around the Antarctic continental margin are described using synthesized hydrographic data. Antarctic Surface Water (AASW) over the shelf regime is distinguished from underlying other water masses by the cut-off salinity, varying from approximately 34.35 to 34.45 around Antarctica. Shelf water, characterized by salinity greater than the cut-off salinity and potential temperature less than $-17^{\circ}C$, is observed on the Ross Sea, off George V Land, off Wilkes Land, the Amery Basin, and the Weddell Sea, but in some shelves AASW occupies the entire shelf. Lower Circumpolar Deep Water is present everywhere around the Antarctic oceanic regime and in some places it mixes with Shelf Water, producing Antarctic Slope Front Water (ASFW). ASFW, characterized by potential temperature less than about $0^{\circ}C$ and greater than $-17^{\circ}C$, and salinity greater than the cut-off salinity, is found everywhere around Antarctica except in the Bellingshausen-Amundsen sector. The presence of different water masses over the Antarctic shelves and shelf edges produces mainly three types of water mass stratifications: no significant meridional property gradient in the Bellingshausen and Amundsen Seas, single property gradient where ASFW presents, and a V-shaped front where Shelf Water exists.

• Geomechanics and Engineering
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• v.21 no.3
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• pp.227-236
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• 2020

Non-destructive exploration using elastic waves has been widely used to characterize rock mass properties. Wave propagation in jointed rock masses is significantly governed by the characteristics and orientation of discontinuities. The relationship between spatial heterogeneity (i.e., joint spacing) and wavelength for elastic waves propagating through jointed rock masses have been investigated previously. Discontinuous rock masses can be considered as an equivalent continuum material when the wavelength of the propagating elastic wave exceeds the spatial heterogeneity. However, it is unclear how stress-dependent long-wavelength elastic waves propagate through a repetitive rock-joint system with multiple joints. A preliminary numerical simulation was performed in in this study to investigate long-wavelength elastic wave propagation in regularly jointed rock masses using the three-dimensional distinct element code program. First, experimental studies using the quasi-static resonant column (QSRC) testing device are performed on regularly jointed disc column specimens for three different materials (acetal, aluminum, and gneiss). The P- and S-wave velocities of the specimens are obtained under various normal stress levels. The normal and shear joint stiffness are calculated from the experimental results using an equivalent continuum model and used as input parameters for numerical analysis. The spatial and temporal sizes are carefully selected to guarantee a stable numerical simulation. Based on the calibrated jointed rock model, the numerical and experimental results are compared.