• Journal of the Institute of Convergence Signal Processing
• /
• v.22 no.3
• /
• pp.122-127
• /
• 2021

Flow features near the ship bow such as wave breaking, small scale phenomena have been studied using numerical methods. In this study, the bow shaped wedge was adopted which is from previous paper [1, 2] and the conditions of simulation were Re = 1.64 × 10⁵) and Fr = 2.93. Star CCM+, one of the commercial CFD programs has been used for the simulations. Simulation results such as wave profiles near the ship bow, shape of plunging jet, air entrainment, and wave breaking process have been compared with previous experimental and numerical studies. Overall results showed good agreements with previous studies. Profiles of bow waves showed that overturning jet has been created and broken along the wedge. Plunging wave breaking has been observed along the wedge and four components of plunging wave breaking process were shown. It is confirmed that velocity near the overturing jet significantly increased during plunging wave breaking.

• The Journal of Korean Society for Radiation Therapy
• /
• v.22 no.1
• /
• pp.53-60
• /
• 2010

Purpose: We try to calculate EDW-factor easily with the formula applies essential data of EDW-factor and evaluate the validity through a measurement. Materials and Methods: We used the given value of GSTT (Golden Segmented Treatment Table) for the calculation of the EDW-factor. As to the experimental device, 0.6 cc farmer-type ion-chamber, an electrometer and water- phantom were used. A measurement was made at the maximum dose depth of the photon beam energy 6 MV and 15 MV under the condition that SSD (Source to Surface Distance) was 100 cm. The angle of the EDW (Enhanced Dynamic Wedge) which we use in an experiment was 60 degree, 30 degree, 20 degree in the Y1-OUT direction. We used Eclipse planning system (Varian, USA) as RTP system and the EDW-factor was calculated about all fields and EDW direction. In order to show the EDW-factor feature, a measurement was made at the selected field that verify the influence of the dependability about X, Y jaw and off-axis field. Results: When we change the Y1 field, it influence on the EDW-Factor and measured value. But the error between measured values and calculated values was less than 1%. The experimental result indicated the tendency that the error of the result of calculation and measured value becomes smaller as the EDW angle become smaller whether the calculation point (measurement point) and iso-center are same or not. The influence of the field size and energy did not show up. We simulated with the same condition using the RTP system. And we found that it makes no difference between the MU which is calculated manually by applying the EDW-Factor obtained from the commercial program and the value which is calculated by using RTP system. Conclusion: We excluded fitting value from well-known EDW-Factor formula and calculated EDW-factor with the formula applies essential data of EDW-factor only. As a result, there are no significant difference between the measured value and calculated value and it showed errors less than 1%. Also, we implemented the commercial program to calculate EDW-Factor conveniently without measure a factor on each field.

• Journal of Veterinary Clinics
• /
• v.28 no.3
• /
• pp.328-331
• /
• 2011

Two dogs presented to the Dueckso Animal Hospital with a history of intermittent lameness of the left forelimb. On physical examination, a visible antebrachial deformity that resulted in gross external rotation of approximately $90^{\circ}$ was observed in two dogs. Medial-lateral radiographic views revealed distal ulnar subluxation, cranial bowing of the radius, radial and ulnar shortening, and external rotation of the paw. A distal ulnar ostectomy and distal radial closing wedge osteotomy were performed in two dogs. A proximal ulnar osteotomy was performed, adjacent to the elbow joint in case 1. Then, the osteotomized site was supported with an intramedullary pin. A T-plate and cortical screws were applied to the proximal and distal radial segments after derotating the distal segment internally. Postoperative radiographic view verified the correction of the angular deformity in two dogs. The follow-up was completed by physical examination 6 and 10 months after surgery respectively. There was no evidence of lameness of the left forelimb in two dogs. Gross observation of the limb revealed an apparent appropriate correction of the rotational and angular deformity in two dogs.

• The Korean Journal of Zoology
• /
• v.34 no.4
• /
• pp.433-451
• /
• 1991

척추동물(7목 23종)의 췌장에서 insulin( B)세포, glucagon(A)세포, somatostatin( D)세포 및 pancreatic polypeptide( PP)세포 등을 면역세포화학법으로 동정하여 이들의 출현율, 분포양상 및 형태 등을 계통별로 비교하였다. 파충강의 거북목, 양서강의 유미목 및 어강의 악상대목 들을 제외한 모든 종에서 췌도의 형성을 관찰할 수 있었으며, 췌도를 구성하는 내분비세포의 크기에는 계통간의 차이가 있었다. B세포는 파충강의 것이 가장 크고, 양서강, 어강의 순이 었으며 A와 PP세포는 양서강, 파충강 및 어강의 순서였다. D세포는 양서강의 것이 가장 윤고, 다음이 어장이었으며, 파충강의 것이 가장 작았다. 이들 세포의 모양은 B세포의 경우 양서강과 어장에서는 원형, 난원형 및 방추형이었으며, 파충강에서는 원추형 및 단기형 등 다양한 모습이었다. A세포는 어강에서는 원헝, 난원형 및 방추형이 고르게 나타났고, 파충강과 양서 강에서는 원주형, 다각형 및 쐐기형이 나타났다. D세포는 모든 동물에서 원형, 난원형 및 방추형이 관찰되었고, 특히 파충강에서는 원추형및 쐐기형도 나타났다. PP세포는 주로 방추형 및 반원형이 대다수이였으며 간혹 원형 또는 다각형 등의 모습도 나타났다. 각 내분비세포의 출현율은 파충강 열 어강 들에서는 B, A, D 및 PP세포 순이었으나, 양서 강에서는 B, A, PP 및 D세포 순으로 나타났다. B와 PP세포는 양서강, 어강 및 파충강 순서로 출현하였고, A세포는 파충강, 어강 및 양서강의 순서이었으며 D세포는 어강, 파충강 및 양서강의 순서였다. 췌도 내에서의 세포의 분포 위치는 세포의 종류에 따라 차이를 보여 B세포의 경우 대다수 동물들에서 중앙부에 균등하게 분포하였으나 A, D및 PP세포는 주로 췌도 주변부에 분포하였고, 어강에서의 D세포는 췌도 중앙부에서도 관찰되었다. 일반적으로 파충강 및 양서 강에서는 외분비 선포조직에서초 내분비세포들이 출현하였으나, 어강에서는 내분비세포가 전혀 출현하지 않았다. 양서강 및 어강 들의 일부 수에서는 췌관상피에서도 드물게 나타났다.

• The Korean Journal of Quaternary Research
• /
• v.23 no.1
• /
• pp.1-24
• /
• 2009

Paleosol layers lying on top of the terrace in Jeongdongjin area appear to have been deposited under generally well-drained condition with periodic waterlogging. From a 4.5m-long profile observed, a total of 6 stratigraphic units were identified. Grain-size analysis indicates the dominance of silty and clay materials with some portions with high sand content. Major mineralogical elements are quartz, feldspar, mica and chlorite. Geo-chemical composition shows little change throughout the stratigraphy with some fluctuation in chemical weathering index. Marked increase in magnetic susceptibility is recognizable where stratigraphic unit changes. Soil- wedge layer is developed around 50cm below the surface with concentration of grains of AT tephra (c. 25,000 BP). An OSL date of c. 110,000 BP was obtained from a sand layer lying below the paleosol.

• Economic and Environmental Geology
• /
• v.27 no.6
• /
• pp.571-577
• /
• 1994

It has been controversial whether the United States Atlantic margin, which developed during Mesozoic separation of Africa and North America, is a volcanic or non-volcanic rifted margin. To understand its nature, the basement images of multi-channel seismic profiles off the southeastern United States continental margin have been examined. One of prominent results is the presence of seaward-dipping reflector (SDR) wedges, the most diagnostic feature of volcanic rifted margins. Two sets of SDR wedges appear to exist here; one along the basement hinge zone ('the hinge SDR wedge') and another seaward of the East Coast magnetic anomaly ('the outer SDR wedge'). Seaward of the basement hinge zone, the lower crustal high-velocity body previously known as the 7.2 km/s layer and the underlying smooth Moho configuration are also observed. Based on the comparison of these basement images with the crustal structures of the well-known volcanic rifted margin, the southeastern United States Atlantic margin can now be characterized as a typical volcanic rifted margin.

• The Journal of the Acoustical Society of Korea
• /
• v.40 no.4
• /
• pp.270-277
• /
• 2021

In the power ultrasound fields, the flange position for fixing the transducer is an important factor influencing on electro-mechanical efficiency of the transducer. We suggested a practical method that can determine the installation position of the flange for different resonance modes of the bolt-clamped type Langevin ultrasonic transducer. A semicircular wedge-shaped jig was manufactured and moved along the lateral surface of the transducer. The vibration characteristics were examined after a constant pressure was applied to the semicircular wedge-shaped jig. By observing the change of the input admittance of the transducer depending on the position of the pressure application, the optimum position for the flange installation could be determined. The resonant modes of the transducer were calculated by a Mason's equivalent circuit, and the particle velocity distribution for each resonance mode was calculated by a transmission line model. Since the optimum positions determined from an experimental result show a good correspondence with the node positions of the vibration modes calculated by the transmission line model, the validity of the suggested method was verified.

• Journal of The Geomorphological Association of Korea
• /
• v.18 no.4
• /
• pp.35-57
• /
• 2011

Minor erosional forms in the bedrock river, like potholes, are not just research subject for the professional geomorphologis. In addition, these features attract general public and make them understand the social contribution and importance of geomorphologic research activities. In this paper, the studies on bedrock minor forms in Korea was reviewed. For further researches, some of major erosional processes and minor forms in bedrock rivers were discussed in detail. Cavitation, plucking, hydro-wedging, and abrasion by passing sediment particles are the major processes to create the longitudinal or transverse minor forms like pothole, furrows, flutes, and runnels. Especially the definition of furrows and runnels are explained to prevent the confusion with pothole, weathering pits and grooves. To make a progress in research on bedrock minor forms the quantitative relationship between the variables should be studied. New techniques for scientific estimation of erosion rates and exposure ages of bedrock surfaces should be used in this field.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.2 s.54
• /
• pp.81-94
• /
• 2007

In most experimental researches on the liquefaction phenomenon, an earthquake as a random vibration has been regraded as a sinusoidal wave or a triangular wave with an equivalent amplitude. Together with the development in the part of signal control and data acquisition, dynamic experimental equipments in the soil dynamics have also developed rapidly and further more, several real earthquakes have been simulated in the large model test such as shaking table tests and centrifuge tests. In Korea, several elementary laboratory tests to simulate the real earthquake load were performed. From these test results, it was reported that the sinusoidal wave cannot reliably reflect the soil dynamic behavior under the real earthquake motion. In this study, 4 types of dynamic motions such as the sinusoidal wave, the triangular wave, the incremental triangular wave and several real earthquake motions which were classified with shock-type and vibration-type were loaded to find something new to explain the change of the excess pore water pressure under the real earthquake load. Through the detailed investigation and comparison on all test results, it is found that the dynamic flow is generated by the soil plastic deformation and the velocity head of dynamic flow is changed the pressure head in the un-drained condition. It can be concluded that the change of the excess pore water pressure is related to the pressure head of dynamic flow. Lastly, a new hypothesis to explain such a liquefaction initiation phenomenon under the real earthquake load is also proposed and verified.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.3 s.49
• /
• pp.125-134
• /
• 2006

Conventional methods for the assessment of liquefaction potential were primary for severe earthquake regions $(M{\geq}7.5)$ such as North America and Japan. In Korea, an earthquake related research has started in 1997, but most contents in the guidelines were still quoted from literature reviews of North America and Japan, which are located in strong earthquake region. Those are not proper in a moderate earthquake regions including Korea. Also the equivalent uniform stress concept (Seed & Idriss, 1971) using regular sinusoidal loading which is used, in a conventional method for the assessment of liquefaction potential, can't reflect correctly the dynamic characteristics of real irregular earthquake motions. In this study, cyclic triaxial tests using irregular earthquake motions are performed with different earthquake magnitudes, relative densities, and fines contents. Assessment of liquefaction potential in moderate earthquake regions is discussed based on various laboratory test results. From the results, screening limits in seismic design were re-investigated and proposed using normalized maximum stress ratios under real irregular earthquake motions. Also from the tests using constant wedge loading and incremental wedge loading, the characteristics of liquefaction resistance of saturated sand under irregular ground motions are investigated.