• Clinical and Experimental Pediatrics
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• v.51 no.6
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• pp.660-664
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• 2008

The term tracheal bronchus refers to an abnormal bronchus that comes directly off of the lateral wall of the trachea (above the carina) and supplies ventilation to the upper lobe. Tracheal bronchi occur almost exclusively on the right trachea and are associated with other congenital anomalies. In addition, tracheai bronchus may be related to other inflammatory conditions with persistent wheezing, such as recurrent pneumonia, chronic bronchitis and bronchiectasis, which is a result of the relatively poor local drainage of the involved bronchi. An infant with recurrent wheezing is likely to be a challenge for a clinician in the evaluation of the etiology of airway obstruction and in the differential diagnosis of wheezy breathing. The authors report a case of an 8-month-old female infant with a ventricular septal defect, who presented with stridor and recurrent respiratory infection and finally was finally diagnosed with a tracheal bronchus using computed tomography and a bronchoscopy. Therefore, tracheal bronchus should be included in the differential diagnosis of any child who presents with chronic or recurrent respiratory tract symptoms such as coughing, wheezing, stridor and recurrent respiratory infection, particularly in children with other congenital deformities.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.3
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• pp.291-303
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• 2016

Recently, various forms of diverging sections in tunnels have been designed as the demand for underground passageway in urban areas increases. Therefore, the complexity of the ventilation system in tunnels with diverging sections requires a ventilation analysis method different from the conventional method for the straight tunnels. None of the domestic and foreign tunnel ventilation design standards specifies the method for the ventilation network analysis, and the numerical analysis methods have been most widely used. This paper aims at reviewing the ventilation network analytical method applicable as the design standard. The proposed method is based on the characteristic equations rather than the numerical analysis. Thanks to the advantages of easy application, the Hardy-Cross method has been widely applied in the fields of mine ventilation and tunnel ventilation. However, limitations with the cutting errors in the Taylor series expansion and the convergence problem mainly caused by the mesh selection algorithm have been reported. Therefore, this paper examines the applicability of the ventilation analysis method for network-type tunnels with the gradient method that can analyze flow rate and pressure simultaneously without the configuration of mesh. A simple ventilation analysis method for network-type tunnels is proposed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.503-515
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• 2017

Underground structures that have recently become larger are required to be stable not only during normal times but also during earthquakes. Especially, it is very important to maintain the stability of the subsea tunnels during the earthquake. The objective of this paper is to verify the effectiveness of the flexible segment, which is one of the breakthrough facilities to maintain the stability of the subsea tunnel during the earthquake using the shaking table test. Another goal of this paper is to propose the optimum position of the flexible segment through 3D dynamic numerical analysis based on the verified results from shaking table tests. The 1g shaking table test considering the similarity ratio (1:100) to the cross section of the selected artificial subsea tunnel was carried out considering the Geongju and Artificial seismic waves, longitudinal and lateral wave, and with/without flexible segments eight times or more. As a result of the shaking table test, it was confirmed that the flexible segment is effective in improving the seismic performance of the undersea tunnel in all the experimental results. In addition, 3D dynamic numerical analysis was performed to select the optimum position of the flexible segment which is effective for improving seismic performance. As a result, it was confirmed that the seismic acceleration is attenuated when the flexible segment is installed adjacent to the branch section in subsea tunnel.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.697-704
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• 2017

This study was carried out to investigate and alleviate the vibration problem of commercial high-speed trains. First, the measurement of the carbody vibration was performed, in order to determine the vibration level of the high-speed train. The measurement result showed that the vibration level of the driver cab was higher than that of the passenger car and that the vibration became bigger toward the trailing end of the train. The vertical vibration of the driver cab and passenger car was larger than the transverse vibration, and the maximum value of the vibration in the ballast section was larger than that in the concrete section. A dynamic analysis was carried out to improve the vibration of the KTX-Sancheon train. The results of the analysis showed that it is necessary to reduce the vibration of the driver cab and both ends of the passenger cars. To reduce the vibration of the driver cab, it was recommended that the stiffness of the secondary coil spring be reduced and the damping coefficient of the secondary vertical damper be increased. It was found that the failure of the suspension system could be the origin of the vibration problem of the high-speed train. The proper management of wheel wear plays an important role in the improvement of the operation efficiency and reduction of the carbody vibration of high-speed trains, and research is underway to change the present wheel profile to increase the mileage between wheel turning.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.4
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• pp.331-337
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• 2017

This study was carried out to analyze the community structure and distribution of macrobenthos at the intertidal zone of Jukbyeon in Uljin-gun during 2015-2016. The number of species were total 41 from 5 phyla. The species composition of Cnidaria 4, Mollusca 19, Annelida 3, Arthropoda 13, Echinodermata 2 and the individuals was $1,642inds./m^2$ and the weight was $1,959.42gWWt./m^2$ in the study area. The dominant species of the upper zones were Chthamalus challengeri and Nodilittorina radiata. Those of the lower zones were Mytilus galloprovincialis, Nipponacmaea schrenckii and Chlorostoma turbinata. The dominant species of the upper zones of winter and spring were C. challengeri, the summer and autumn of the N. radiata. Those of the lower zones were all seasonal of M. galloprovincialis. As a result of cluster analysis, those regions were divided in three groups, which were a group A of December 2015, August 2015 and February to August 2016 of intertidal zone lower, group B of December 2016 and May 2015 of intertidal zone lower, group C of intertidal zone upper.

• Journal of Yeungnam Medical Science
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• v.6 no.2
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• pp.79-90
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• 1989

Computerized Tomography is now well established and important noninvasive method of diagnosting mediastinal mass lesions because of its superior imaging of their size, location and internal composition. Authors ana lysed and present CT findings of 30 surgically proven mediastinal tumors and cysts that were studied and treated at the Yeungnam University Hospital during recent 6 years. The most common tumor was thymona(9 cases), and teratoma(6 cases), lymphoma(6 cases), bronchogenic cyst(4 cases), neurogenic tumor (4 cases), pericardial cyst(1 case) were next in order of frequency. There were 5 cases of thymoma showing homogenous solid density mass, 2 cases were malignant thymoma and myasthenia gravis was present in 2 cases. A case of thymolipoma and a case of thymic carcinoma were included. All teratomas were cystic masses but pathognomic fat, and calcified density were seen only in 4 cases. 5 cases were located in anterior mediastinum and 1 case was in posterior mediastinum. Lymphoma(3 Hodgkin's and 3 non-Hodgkin's) appeared as irregular lobulated mass in anterior mediastinum. Neurogenic tumor(2 ganglioneuroma and 2 neurilemmoma) appeared as homogenous density mass located in posterior mediastinum. Among the 4 bronchogenic cysts, 2 were located in retrotracheal area, 1 was located in subcarinal and 1 was in parathoracic area. One case of pericardial cyst was oval shaped cystic mass located in left pericardiac border.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.182-197
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• 1993

Algal community on the subtidal rocky zone of the South Sea of Korea was divided into two or three sequencing zones. The upper subtidal zone was characterized by the wave exposure-tolerant surf wrack(Pachymeniopsis, Gigartina), which formed dense swirling carpet. Its vertical range was from the surface to $3{\sim}5$ meters in depth, and more deeply extended in turbid waters including Sorido, Yokchido, Pijindo, Manjedo. The mid subtidal zone ranging from 5 to 25 meters in depth was characterized by a large brown algal forest (Ecklenia, Sargassum). But it was generally unrecognizable in that turbid waters, in which the vertical limit of vegetation was at most $10{\sim}15$ meters in depth. The low subtidal zone was characterized by a general lack of algal species and was not easily distinguished from the mid or sometimes from the upper zone. There was a distinct difference in abundance of vegetation between turbid waters and clear waters including Munsom, Kwantaldo, Yosodo, Hongdo, Ch'ujado. In turbid waters the vegetation was much poorer because the tubidity caused from the muddy sediment inhibited an algae to settle down and to grow up. On the basis of the phytogeographical methods using UPGMA, the 10 studied islands were classified into two groups, Munsom and the others. This floristic discontinuity between the two groups might be caused from the difference of water temperature.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.42-51
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• 2007

An AC electrical railroad system has rapidly changing dynamic single-phase load, and at a feeding substation, three-phase electric power is transformed to the paired directional single-phase electric power. There is a great difference in electrical phenomenon between the load of AC electrical railroad system and that of general power system. Electric characteristics of AC electrical railroad's trainload are changed continuously according to the traction, operating characteristic, operating schedule, track slope, etc. Because of the long feeding distance of the dynamic trainload, power quality problems such as voltage drop, voltage imbalance and harmonic distortion my also occur to AC electrical railroad system. These problems affect not only power system stability, but also power quality deterioration in AC electrical railroad system. The dynamic simulation model of AC electrical railroad system presented by PSCAD/EMTDC is modeled in this paper, andthen, it is analyzed voltage drop for AC electrical railroad system both with single-phase distributed STATCOM(Static Synchronous Compensator) installed at SP(Sectioning Post) and without.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.93-102
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• 2018

This paper reports a Surge Protective Device (SPD) that is used to protect an automatic metering interface (AMI) power supplies of communication equipment on a low-voltage distribution system from a lightning current. The surge protective device (SPD) can be classified as one-port SPDs and two-port SPDs with decoupling elements depending on the connection type. The protection of internal systems against the lightning current may require a systematic approach consisting of coordinated SPDs. To deal with this, the definition of a lightning protection zone (LPZ) was studied and interpreted through a theoretical review. Because the lightning current resulting from a lightning surge is considerably high, there is limited protection from one SPD; therefore, coordinated cascaded MOV-based SPDs are installed to solve this problem. Regarding the power grid mentioned in this paper, a class II SPD for the low-voltage distribution system installed on the border of LPZ1 and LPZ2, which establish a protection coordination with the Arrester (LA, SA) that corresponds to the LPZO installed on the MOF stage connected to one system were designed to protect various communication (control) equipment, including the automatic meter reading system inside the branch-type electric supply panel of a building, not the incoming side of one system. In addition, performance-related tests were done by a comparison with the existing method through testing, and the optimal design was achieved for the 1-port SPD that uses a series connection and can bleed load current without any decoupling element.

• The KIPS Transactions:PartD
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• v.14D no.6
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• pp.585-596
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• 2007

XML data generally consists of a hierarchical tree-structure which is reflected in mechanisms to store and retrieve XML data. Therefore, when storing XML data in the database, the hierarchical relationships among the XML elements are taken into consideration during the restructuring and storing of the XML data. Also, in order to support the search queries from the user, a mechanism is needed to compute the hierarchical relationship between the element structures specified by the query. The structural join operation is one solution to this problem, and is an efficient computation method for hierarchical relationships in an in database based on the node numbering scheme. However, in order to process a tree structured XML query which contains a complex nested hierarchical relationship it still needs to carry out multiple structural joins and results in another problem of having a high query execution cost. Therefore, in this paper we provide a preprocessing mechanism for effectively reducing the cost of multiple nested structural joins by applying the concept of equivalence classes and suggest a query path reduction algorithm to shorten the path query which consists of a regular expression. The mechanism is especially devised to reduce path queries containing branch nodes. The experimental results show that the proposed algorithm can reduce the time requited for processing the path queries to 1/3 of the original execution time.