• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.515-524
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• 2015

The number of occurrence of differential settlement and track irregularity at track transition zone recently comes to increase, which leads to frequent maintenance activities that have an impact on train operation. Such track transition zone damages are attributed to the change of mechanical properties of fill materials due to environmental factors such as rainfall and freeze, and thaw. Consequently, this study attempts to establish the soil water characteristic curve (SWCC) of fill materials, and conduct seepage analysis to assess the distribution of degree of saturation (DOS) for track transition zone in case of rainfall. The SWCC of fill materials was successfully obtained using filter paper test method. The results of seepage analysis revealed that rainfall intensity, the slope of backfill, backfill condition (fill or cut), and SWCC are significantly influential in controlling the distribution of DOS.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1139-1146
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• 2001

The reactor pressure vessel(RPV) is usually cladded with stainless steel to prevent corrosion and radiation embrittlement, and a number of subclad cracks have been found during an in-service-inspection. These subclad cracks should be assured for a safe operation under normal conditions and faulted conditions such as pressurized thermal shock(PTS). Currently available integrity assessment procedure for an RPV, ASME Code Sec. XI, are built on the basis of linear fracture mechanics (LEFM). In PTS condition, however, thermal stress and mechanical stress give rise to high tensile stress at the cladding and elastic-plastic behavior is expected in this area. Therfore, ASME Code Sec. XI is overly conservative in assessing the structural integrity under PTS condition. In this paper, the fracture parameter (stress intensity factor, K, and RT(sub)NDT) from elastic analysis using ASME Sec. XI and finite element method were validated against 3-D elastic-plastic finite element analyses. The difference between elastic and elastic-plastic analysis became significant with increasing crack depth. Therfore, it is recommended to perform elastic-plastic analysis for the accurate assessment of subclad cracks under TPS which causes plastic deformation at the cladding.

• Investigative Magnetic Resonance Imaging
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• v.17 no.1
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• pp.59-62
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• 2013

There are various types of foreign body reactions, such as inflammation, edema, fluid collection, hematoma, infection, abscess and granulomas. There are various imaging findings according to types of foreign bodies and depending on the lapse of time. Therefore, correct diagnosis of a foreign body reaction is difficult and easily confused with soft tissue neoplasm. The MRI is ideal for the detection of foreign bodies regardless of radiolucency or acoustic impedance. It is especially very useful in the evaluation of the surrounding tissue reaction. The authors report a case of a 26-year-old female patient with both forearm swelling due to self-injection of a mixture of powdered tablets and saline. The lesion shows numerous internal T1 and T2 dark signal intensity micro-spots with surrounding fluid collection, which are diagnosed as foreign bodies with surrounding inflammatory changes during an operation.

• Investigative Magnetic Resonance Imaging
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• v.24 no.3
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• pp.95-122
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• 2020

In this article, we evaluated the performance of radiofrequency (RF) coils in terms of the signal-to-noise ratio (S/N) and homogeneity of magnetic resonance images when used for ultrahigh-frequency (UHF) 7T magnetic resonance imaging (MRI). High-quality MRI can be obtained when these two basic requirements are met. However, because of the dielectric effect, 7T magnetic resonance imaging still produces essentially a non-uniform magnetic flux (|B₁|) density distribution. In general, heterogeneous and homogeneous RF coils may be designed using electromagnetic (EM) modeling. Heterogeneous coils, which are surface coils, are used in consideration of scalability in the |B₁| region with a high S/N as multichannel loop coils rather than selecting a single loop. Loop coils are considered state of the art for their simplicity yet effective |B₁|-field distribution and intensity. In addition, combining multiple loop coils allows phase arrays (PA). PA coils have gained great interest for use in receiving signals because of parallel imaging (PI) techniques, such as sensitivity encoding (SENSE) and generalized autocalibrating partial parallel acquisition (GRAPPA), which drastically reduce the acquisition time. With the introduction of a parallel transmit coil (pTx) system, a form of transceiver loop arrays has also been proposed. In this article, we discussed the applications and proposed designs of loop coils. RF homogeneous coils for volume imaging include Alderman-Grant resonators, birdcage coils, saddle coils, traveling wave coils, transmission line arrays, composite right-/left-handed arrays, and fusion coils. In this article, we also discussed the basic operation, design, and applications of these coils.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.2
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• pp.1027-1030
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• 2013

Background: Peritoneal washing cytology (PWC) that shows the microscopic intra-peritoneal spread of gynaecologic cancers is not used in staging but is known as prognostic factor and effective in planning the intensity of the therapy. False negative or false positive results clearly affect the ability to make the best decision for therapy. In this study we assessed levels of tumour markers, carcinoembryonic antigen (CEA), cancer antigen 125 (CA-125) and carbohydrate antigen (CA19-9), in peritoneal washing fluid to establish any possible contribution to the peritoneal washing cytology in patients operated for gynaecologic cancer. Materials and Methods: Preoperative tumour markers were studied in serum of blood samples obtained from the patients for preoperative evaluation of a gynaecologic operation. In the same group peritoneal tumour markers were studied in the washing fluid obtained for intraoperative cytological evaluation. Results: This study included a total of 94 patients, 62 with malignant and 32 with benign histopathology. The sensitivity of the cytological examination was found to be 21% with a specificity of 100%. When evaluated with CEA the sensitivity of the cytological examination has increased to 37%. Conclusions: In addition to examination of PWC, the level of CEA, a tumour marker, in peritoneal washing fluid can make a diagnostic contribution. Determining the level of CEA in peritoneal washing fluid will be useful in the management of gynaecologic cancers.

• Journal of Korea Multimedia Society
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• v.7 no.1
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• pp.35-43
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• 2004

In this paper, we proposed a vehicle recognition and electronic toll collection system with detection and classification of vehicle identification mark and emblem as well as recognition of vehicle license plate to unman toll fee collection system or incoming/outcoming vehicles to an institution. In the proposed algorithm, we first process pre-processing step such as noise reduction and thinning from the rear side input image of vehicle and detect vehicle mark, emblem and license plate region using intensity variation informations, template masking and labeling operation. And then, we classify the detected vehicle features regions into vehicle mark and emblem as well as recognize characters and numbers of vehicle license plate using hybrid and seven segment pattern vector. To show the efficiency of the proposed algorithm, we tested it on real vehicle images of implemented vehicle recognition system in highway toll gate and found that the proposed method shows good feature detection/classification performance regardless of irregular environment conditions as well as noise, size, and location of vehicles. And also, the proposed algorithm may be utilized for catching criminal vehicles, unmanned toll collection system, and unmanned checking incoming/outcoming vehicles to an institution.

• Journal of Korean Neurosurgical Society
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• v.52 no.5
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• pp.491-494
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• 2012

We report a rare complication of iatrogenic spinal intradural following minimally invasive extradural endoscopic procedues in the lumbo-sacral spines. To our knowledge, intradural cyst following epiduroscopy has not been reported in the literature. A 65-year-old woman with back pain related with previous lumbar disc surgery underwent endoscopic epidural neuroplasty and nerve block, but her back pain much aggravated after this procedure. Postoperative magnetic resonance imaging revealed a large intradural cyst from S1-2 to L2-3 displacing the nerve roots anteriorly. On T1 and T2-weighted image, the signal within the cyst had the same intensity as cerebrospinal fluid. The patient underwent partial laminectomy of L5 and intradural exploration, and fenestration of the cystic wall was accomplished. During operation, the communication between the cyst and subarachnoid space was not identified, and the content of the cyst was the same as that of cerebrospinal fluid. Postoperatively, the pain attenuated immediately. Incidental durotomy which occurred during advancing the endoscope through epidural space may be the cause of formation of the intradural cyst. Intrdural cyst should be considered, if a patient complains of new symptoms such as aggravation of back pain after epiduroscopy. Surgical treatment, simple fenestration of the cyst may lead to improved outcome. All the procedures using epiduroscopy should be performed with caution.

• Journal of Navigation and Port Research
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• v.28 no.1
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• pp.43-49
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• 2004

Defects inspection of commodities are very important with those design and manufacturing process and essential to strengthen the competitiveness of those. If on-line automatic defects detection is performed without damaging to products, the production cost shall be curtailed through the reducing man-power, economical management of Q.C(Quality Control). In this paper, it is suggested three spatial filtering methods which can extract the necessary information in case of defects being on the surface of object like iron plate. In addition, the dependence of filtering characteristics on parameters such as the pitch and width of slits is analyzed and the surface defect detection system is constructed. Several experiments were carried out for determining the adequate spatial filtering method through comparing and analyzing effects of parameters like defect's size and shape, intensity of light, noise of coherent source and slit number.

• KSBB Journal
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• v.19 no.3
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• pp.192-199
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• 2004

In this work the production of glutathione (GSH) by yeast Saccharomyces cerevisiae and the monitoring of the process were studied. In shaking culture the production of GSH was high at initial pH value of 4 and at temperature of 30$^{\circ}C$. But when L-cysteine was added to the culture medium at the beginning of the cultivation, the productivity of GSH was low. In case 0,5% (v/v) of L-cysteine, glycine and glutamic acid were introduced to the culture medium in the exponential cell growth phase, high concentration of GSH (about 90 mg/L) was produced in the bioreactor. A fed-batch operation with stepwise glucose feeding strategy allowed to produce 102 mg/L of GSH. The cultivation processes were on-line monitored by a 2-dimensional fluorescence sensor. A few off-line data such as cell growth, cystein concentration, phosphate concentration and GSH productivity could be well correlated to the fluorescence intensity of some combinations of excitation and emission wavelengths.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1942-1950
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• 2013

This paper suggests a new method of detecting attacks of network traffic by visualizing original traffic data and applying multi-class SVM (support vector machine). The proposed method first generates 2D images from IP and ports of transmitters and receivers, and extracts linear patterns and high intensity values from the images, representing traffic attacks. It then obtains variance of ports of transmitters and receivers and extracts the number of clusters and entropy features using ISODATA algorithm. Finally, it determines through multi-class SVM if the traffic data contain DDoS, DoS, Internet worm, or port scans. Experimental results show that the suggested multi-class SVM-based algorithm can more effectively detect network traffic attacks.