• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2002.10a
• /
• pp.267-272
• /
• 2002

Pitting corrosion is a very common occurrence in marine structures. Therefore, the 3-D finite element analysis is carried out to determine the stress intensity factors at the pit depth and also at the surface of the pit. The pits are modeled as a part of sphere, based on the pit depth and the pit diameter as specified by the Ship Structural Committee. The pit depth and pit diameter are function of the percentage of pitting that the plate is subjected to. A dog-bone shaped specimen is subjected to different intensities of pitting and the stress intensity factors are determined under axial tensile loads.

• Korean Journal of Heritage: History & Science
• /
• v.33
• /
• pp.36-67
• /
• 2000

Square-shaped moated burial precincts(方形周溝墓) can be classified into type I that has bridges only at the comers, type II that has bridges at the comers and sides, type III that has bridges only at the sides, type IV that is surrounded by the moat without bridges, type V that has its sides less than those of type I ~ V by 1 or 2, and type VI that has the round-shaped ground. But the time differences among the types are not known yet. For the burial appliances of square-shaped moated burial precincts, there are stone coffins, pit burials and jar burials. The major burial appliances situated in the mound are stone coffins and pit burials, and jar burials are subsidiary appliances that were buried at the shoulder part of the mound or at precincts. According to the case of Gwanchang-ri KM423, grave mounds, which arc closely related with the burial appliances, were built by heaping up the earth in and around the precinct as low as only enough to protect the burial appliances. Considering the relics unearthed in the burial compartment of KM437, the time when square-shaped moated burial precincts were formed is estimated to be the age when Songguk-ri type earthenware and clay stripes earthenware co-existed. It was the early Iron Age when ironware began to sp read in this country. Emerging first in that age, square-shaped moated burial precincts were presumably formed until around the end of BC or the beginning of AD, when KM404 and KM423, which were unearthed with plain earthenware, grey earthenware and ironware, were formed. When analyzing the form of small-sized graveyards in precincts, the unearthed relics and the locations, the people who formed square-shaped moated burial precincts were considered as those who had a culture comprising clay stripes earthenware, which appears newly in the Songguk-ri type earthenware of native, and ironware, and a settled agricultural society based on paddy fields and labor forces of family units.

• The Korean Journal of Malacology
• /
• v.27 no.2
• /
• pp.91-97
• /
• 2011

This study examines the morphological features of larval and postlarval shells of the paedomorphic bivalve Crenella decussata Montagu, 1808 from the Sea of Japan. During the early morphogenesis of the shell of C. decussata the following characteristics appear: prodissoconch I -the anterior and posterior provincular teeth, a broad primary ligament pit located on the chondrophore; nepioconch - the anterior and posterior juvenile teeth,primary lateral teeth, fine commarginal and radial sculpture. Larvae of C. decussata distinctly differ from other mytilid larvae by a D-shaped shell, absence of umbo, astraight hinge margin, and homogeneous fine-grained sculpture without co-marginal lines of growth. These shell characters indicate lecithotrophic development of this species. Some morphostructures are revealed which might be used in crenellin taxonomy.

• Parasites, Hosts and Diseases
• /
• v.52 no.5
• /
• pp.569-573
• /
• 2014

In a paleo-parasitological analysis of soil samples obtained from V-shaped pits dating to the ancient Baekje period in Korean history, we discovered Ascaris lumbricoides, Trichuris trichiura, and Clonorchis sinensis eggs. In light of the samples' seriously contaminated state, the V-shaped pits might have served as toilets, cesspits, or dung heaps. For a long period of time, researchers scouring archaeological sites in Korea have had difficulties locating such structures. In this context then, the present report is unique because similar kind of the ancient ruins must become an ideal resource for successful sampling in our forthcoming paleoparasitological studies.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.26 no.1
• /
• pp.1-7
• /
• 2016

RE : YAG ($RE=Nd^{3+}$, $Er^{3+}$) single crystals are laser diodes and generally grown by Czochralski method with controlling the various growth parameter. Since the defects occurred by temperature gradient or the rotation speed of solid-liquid growth interface act as the decline of crystal optical property during the growth procedure, crystalline quality improvement via defects analysis is necessary. The etch pit density (EPD) analysis was used to confirm the surface defect of grown RE : YAG single crystal and to select the area of transmission electron microscopy (TEM) analysis. Defects in the specimen produced by tripod polishing method such as buckling, rod shaped, bend contours by internal stress, segregation and others were observed by using 200 kV TEM and 300 kV FE-TEM.

• Progress in Medical Physics
• /
• v.10 no.3
• /
• pp.133-140
• /
• 1999

In this paper, as a preliminary study for developing a full 3D electron dose calculation algorithm, We developed 2.5D electron dose calculation algorithm by extending 2D pencil-beam model to consider three dimensional geometry such as air-gap and obliquity appropriately. The dose calculation algorithm was implemented using the IDL5.2(Research Systems Inc., USA), For calculation of the Hogstrom's pencil-beam algorithm, the measured data of the central-axis depth-dose for 12 MeV(Siemens M6740) and the linear stopping power and the linear scattering power of water and air from ICRU report 35 was used. To evaluate the accuracy of the implemented program, we compared the calculated dose distribution with the film measurements in the three situations; the normal incident beam, the 45$^{\circ}$ oblique incident beam, and the beam incident on the pit-shaped phantom. As results, about 120 seconds had been required on the PC (Pentium III 450MHz) to calculate dose distribution of a single beam. It needs some optimizing methods to speed up the dose calculation. For the accuracy of dose calculation, in the case of the normal incident beam of the regular and irregular shaped field, at the rapid dose gradient region of penumbra, the errors were within $\pm$3 mm and the dose profiles were agreed within 5%. However, the discrepancy between the calculation and the measurement were about 10% for the oblique incident beam and the beam incident on the pit-shaped phantom. In conclusions, we expended 2D pencil-beam algorithm to take into account the three dimensional geometry of the patient. And also, as well as the dose calculation of irregular field, the irregular shaped body contour and the air-gap could be considered appropriately in the implemented program. In the near future, the more accurate algorithm will be implemented considering inhomogeneity correction using CT, and at that time, the program can be used as a tool for educational and research purpose. This study was supported by a grant (＃HMP-98-G-1-016) of the HAN(Highly Advanced National) Project, Ministry of Health & Welfare, R.O.K.