• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.2
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• pp.23-30
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• 2003

It is very important to detect and evaluate the surface or subsurface flaws because of their influences on mechanical properties of materials. Rayleigh wave and creeping wave are commonly used for the detection of surface and subsurface flaws. These techniques, however, have following problems. Each amplitudes are remarkably affected by the surface condition and evaluation of echo pattern is usually difficult because shear wave mode propagate in the material at the same time. On the other hand, surface SH-wave which is horizontally polarized shear wave traveling along near surface layer is an attractive technique for the surface or subsurface material characterization and this technique is useful to solve the problems mentioned above. In this paper, The stability and transmission coefficient of SH waves through a viscous fluid layer is theoretically studied and simulated. Its results agreed well with the theoretical expectation for the experimental verification. These experimental results show that viscosity of couplants, thickness of couplant and surface roughness are closely related to transfer efficiency in surface SH angle beam method.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.2
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• pp.359-364
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• 2008

Using multi beam echo sounder, side scan sonar and scuba diving equipment, ceramic type, uneven type and semicircle-ramus type reefs into sandy bottom were ascertained, the depth of submersion in 7.2-10.3m on the coast of Gangneung, East of Korea, forty uneven type artificial reefs(AR) were totally buried into the sandy bottom. Two of five semicircle-ramus type ARs had only of their top area exposed. For most of the 45 ceramic reefs, only the upper 25-150cm of ARs were visible. The burial pattern is different in west and east side of the reefs, where the east side is deeply buried compared to the west side. From these results. it is recommended that sufficient analysis of bottom structure and materials especially in the sandy sea area should be undertaken in order to determine the best type of artificial reefs to be deployed and the best location for depoloyment.

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.38-44
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• 2014

In this paper, we designed a multiband monopole antenna for next-generation WLAN system. In conventional WLAN system, UWB antennas were used together, and, because the radiation occurs in different parts depending on the antenna structure, it has the disadvantage of having an unstable impulse response characteristic due to dispersion characteristics. Although a UWB antenna that has suitable radiation pattern for WLAN band, it does not have good impedance matching and has severe echo. Therefore, in this paper, a monopole antenna was designed by using CPW power feed so that various impedances can be easily implemented when designing an antenna and more parameters can be derived that can be used for design for optimal performance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.1
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• pp.30-38
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• 2014

Hydro-acoustic survey was carried out to investigate the spatial characteristics of fish distribution near two artificial reefs (AO: large octagonal semi-sphere and AC: combined custom built) having different types in Jeju marine ranching area. The survey system consisted of scientific echo sounder (EK60), DGPS system, and ECDIS (Mecys). Field survey was conducted on August and October 2012 with star survey and line transect survey line method, and species composition was investigated from gill net fishing survey. The acoustic signals from individual fishes and small fish schools were mainly recorded around AO, but large and strong signals from large fish school were mainly detected in the top layer of and the water column near AC. The echogram suggest that the fish aggregation for the two types of AO and AC exist the significant difference in fish species and spatial distribution pattern.

• Journal of Veterinary Clinics
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• v.29 no.1
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• pp.98-102
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• 2012

A 1.5-year-old male Golden Retriever was presented with worsening lameness of two month duration. Abnomral findings of blood works and serum chemistry included anemia, thrombocytopenia, hypercalcemia and hyperglobulinemia. Radiography revealed osteolysis of polyostotic regions including right femur and tibia, bilateral ilium, and spinous processes from the 13th thoracic vertebra to 5th lumbar vertebra. Enlarged multiple lymph nodes and mixed echo pattern of muscular region ventral to vertebra were observed with ultrasonography. Because concentrations of both parathyroid hormone and parathyroid hormone related peptide were all within reference ranges, humoral hypercalcemia by tumor was ruled out and extensive osteolysis was considered as the cause of hypercalcemia. Based on radiographic and ultrasonographic study, lymphoma, multiple myeloma and osteomyelitis were included in differential diagnosis. Fungal serologic test was negative. Monoclonal gammopathy was not found on serum protein electrophoresis. Cytological and histopathological examinations of the lytic lesions revealed neoplastic lymphoid proliferation, and B cell type clonal expansion was detected by polymerase chain reaction for the antigen receptor gene rearrangement. The case was diagnosed as B cell lymphoma involving polyostotic regions.

• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.120-127
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• 1997

Depositional environment off the Shihwa Dam has been studied to investigate the change of sedimentation process and the pollution. In order to understand how the sediments are distributed, polluted and modified, depositional factors have been analyzed and compared with the previous data. Study area, located off the Shihwa Dam, was surveyed to collect 25 bottom samples and 2 cores in 1996 and echo-sounding in 1997. These sediments were analyzed for the study of the global characteristics of sediment such as grain size and organic matter. Among these samples, the selected twenty surface sediments were analyzed for the comparison with their contents of metallic elements (Al, Mn, Fe, V, Cr, Co, Ni, Cu, Zn, Cd, Pb, As). According to field and lab analysis of sediments, three sedimentological zones have been generally identified around study area; near the dam (sandy Silt), near the dike (Sand) and offshore (silty Sand) zones. Textural parameters show that the content of silt and clay is dominant near the dam excepting the dike zone of LNG Storage Base and offshore (Palmido). The total concentration of Mn, Ni, Fe, Zn and Cd in bulk sediments was increased after the construction of the dam, while the content of Mn and Cr were higher near tidal channel than in the offshore area. Meanwhile, the annual increasing pattern of some heavy metal has appeared in this area. Based on this primary study, modification of the depositional environment may be caused by the construction of the dam and LNG Storage Base. Additionally, environmental evaluation on organic/inorganic factors has been suggested for interpreting environmental changes caused by coastal development in the nearshore such as the Shihwa coastal area.

• Journal of Veterinary Clinics
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• v.27 no.4
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• pp.474-482
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• 2010

Hepatocellular carcinoma (HCC) is a primary hepatic neoplasms in dogs. Three types of HCC such as massive, nodular and diffuse form were reported. Massive HCC is most common and has relatively better prognosis than other forms because this type of HCC can be removed surgically and has low frequency of relapse or metastasis. Diagnostic image can provide useful information for shape and internal structure of the hepatic mass as well as the location and adhesion or invasiveness of the mass to establish surgical plan to remove the mass safely. In this study, we investigated diagnostic features of massive HCC in 5 dogs. Radiography showed soft tissue mass in cranial abdomen in 3 dogs. On ultrasonography, all dogs had a solitary hepatic mass with mixed echo pattern with anechoic cysts, which represented necrosis and hemorrhage. The radiographic and ultrasonographic findings of affected hepatic lobe were compared with the macroscopic findings through laparotomy. Computed tomography was performed to check metastasis and figure out the origin of the mass in two dogs. Ultrasonography is useful and relatively sensitive examination for diagnosis and planning for surgery in canine massive HCC.

• Journal of Wetlands Research
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• v.7 no.2
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• pp.121-132
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• 2005

To classify the surface sedimentary facies using IKONOS image collected over Hwangdo tidal flat in Cheonsu Bay, the optical reflectance was compared for characterizing various sedimentary environments such as grain size, tidal channel pattern and area ratio of surface remnant water. The intertidal DEM (Digital Elevation Model) was generated by echo-sounder for analyzing the relationship between IKONOS image and sedimentary environments including topography. The boundary of the optical reflectance between mud-mixed facies and sand facies was distinct, and discrimination of the associated sandbar feature was also possible. The mud-mixed facies coupled with intricate tidal channels is confined to the relatively hi호 topography of Hwangdo tidal flat. The boundary between mud and mixed flat was indistinct in IKONOS optical reflectance but it would have a difference in the area ratio of surface remnant water. The dark area in the image represented the well developed sand facies having a lot of surface remnant water due to the relatively low surface topography. The overall accuracy of characterizing the surface sediment facies by maximum likelihood classification method was 86.2 %. These results demonstrate that high spatial resolution satellite imagery such as IKONOS coupled with knowledge of grain size, surface remnant water and tidal channel network can be effectively used to characterize the surface sedimentary facies (mud, mixed and sand) network of the tidal flat environments.

• Investigative Magnetic Resonance Imaging
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• v.18 no.2
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• pp.87-106
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• 2014

Purpose : To describe how a robust implementation of a radial 3D gradient-echo sequence with stack-of-stars sampling can be achieved, to review the imaging properties of radial acquisitions, and to share the experience from more than 5000 clinical patient scans. Materials and Methods: A radial stack-of-stars sequence was implemented and installed on 9 clinical MR systems operating at 1.5 and 3 Tesla. Protocols were designed for various applications in which motion artifacts frequently pose a problem with conventional Cartesian techniques. Radial scans were added to routine examinations without selection of specific patient cohorts. Results: Radial acquisitions show significantly lower sensitivity to motion and allow examinations during free breathing. Elimination of breath-holding reduces failure rates for non-compliant patients and enables imaging at higher resolution. Residual artifacts appear as streaks, which are easy to identify and rarely obscure diagnostic information. The improved robustness comes at the expense of longer scan durations, the requirement for fat suppression, and the nonexistence of a time-to-center value. Care needs to be taken during the configuration of receive coils. Conclusion: Routine clinical use of radial stack-of-stars sequences is feasible with current MR systems and may serve as substitute for conventional fat-suppressed T1-weighted protocols in applications where motion is likely to degrade the image quality.

• Journal of Yeungnam Medical Science
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• v.2 no.1
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• pp.87-93
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• 1985

Intraabdommal abscess usually causes distress with fever, leukocytosis, pain and toxicity. Diagnosis of intraabdominal abscess is occasionally difficult and It has high morbidity. However radiologic method, such as ultrasonography, CT scan, or RI scan are helpful to early detection of intraabdominal abscess. Among these methods, ultrasonography is a non-invasive technique and performed without discomfort to patient. And also differential diagnosis between cystic and solid lesion is very easy and sequential ultrasonography in same patient is valuable for the evaluation of treatment effect. We analyzed the ultrasonic features of 48 cases with intra-abdominal abscesses and the results are as follows; 1. In total 48 cases, the intra-abdominal abscesses were 30 cases, the retroperitoneal abscesses, 5 cases, and the visceral abscesses, 13 cases. 2. The causes of the intra-abdominal abscesses were perforating appendicitis (25 cases), postoperative complications (5 cases), pyogenic and amebic hepatic abscesses (13 cases), and the others (5 cases). 3. Round or oval shaped lesions were 26 cases (54%), irregular shape, 18 cases (38%), and multiple abscess formation in 4 cases (8 %). 4. The size of the lesions were between 5 and 10cm in diameter in 54% of total 48 cases, and the most frequent feature of the echo-pattern of the lesions was cystic with or without internal echogenicity (69%).