• Korean Journal of Remote Sensing
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• v.35 no.5_2
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• pp.873-881
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• 2019

There are limitations to the manager's investigation of all damage sites and establishment of management plan in terms of manpower and cost. Community mapping can be used to overcome these problems with the information. However, it is difficult to make decisions when multiple information are registered in multiple areas of damage. Because community mapping information are registered only with pictures and simple contents, it is so difficult for the manager to clearly understand the site situation. This study suggests a methodology to support decision-making processes during disaster management through system integration between the community mapping and the drone mapping. By applying the proposed method, decision makers can make a timely judgment effectively on the damage situation. It is expected that the proposed method will save time, manpower, and cost in the recovery phase.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.319-325
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• 2021

The 2011 East Japan Earthquake caused accidents at a number of nuclear power plants in Fukushima, highlighting the need for a study on the seismic safety of multiple NPP (Nuclear Power Plant) units. In the case of nuclear power plants built on a site that shows a similar seismic response, there is at least a correlation between the seismic damage of structures, systems, and components (SSCs) of nuclear power plants. In this study, a probabilistic seismic safety assessment was performed for the loss of essential power events of twin units. To derive an appropriate seismic damage correlation coefficient, a probabilistic seismic response analysis was performed. Using the external event mensuration system program, we analyzed the seismic fragility and seismic risk by composing a failure tree of multiple loss of essential power events. Additionally, a comparative analysis was performed considering the seismic damage correlation between SSCs as completely independent and completely dependent.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.8-17
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• 2003

The butt lap joint structures which are usually designed by the concept of slow crack growth damage tolerance, show frequently the behaviors of multiple site fatigue crack growth around the fastener hole edges due to the fretting between the two jointed parts. In this paper, experimental tests of fatigue crack growth have been performed of a bolted butt lap joint structure having an initial corner crack at the fastener hole edge, with different fretting conditions under a flight load spectrum. The obtained test results were reviewed to investigate the effects of fretting fatigue cracks on the damage tolerance crack growth life. Computations of corner crack growth were also carried out using an existed model to compare with test results.

• Journal of Trauma and Injury
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• v.30 no.1
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• pp.12-15
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• 2017

A 58-year-old male visited our emergency room for multiple traumas from explosion. On initial evaluation, hemopneumoperitoneum with liver laceration (grade 4) and colon perforation was identified. Hemopericardium with cardiac tamponade was also identified. Shrapnel was detected in the right ventricle. Damage control surgery was planned due to condition of hypotension. In operation room, control over bleeding was achieved after sternotomy, pericardiotomy, and laparotomy. Massive transfusion was done during operation. After gauze packing, operation was terminated with temporary closure (TC). Sanguineous fluid was drained profusely. Disseminated intravascular coagulopathy was confirmed through laboratory findings. No extravasation was discovered at hepatic angiogram. On re-operation, there was no active bleeding but oozing from sternotomy site was identified. Bone bleeding was impossible to control. Finally, reoperation was ended after gauze packing and TC all over again. The patient could survive for only a day after re-operation.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.2
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• pp.68-76
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• 2001

The purpose of this study is to computerize street tree management using a CAD program in order to manage the drawing record of street trees systematically and concurrently. The configuration of this program is composed of Reference Data, Data Inquiry, and Cost Assessment. The Reference Data includes characteristics of trees, monthly managements records, damage by blight and insects and usage of pesticides. The Data Inquiry includes an individual search of the tree index, simple searches and multiple searches. The Cost Assessment includes two main components, the data input with labor cost, manure ocst and pesticide cost and the assesment of management cost for prevention of blight and insects, pruning and fertilization. The results of this study are as follows: 1) When there are practices such as transplanting and removing of street trees it is immediately updated with the various situation. By creating an in progress a tree management system, up to the date information can be given to the manager for decision making. 2) To identify individual tree at the site or in drawing, the street name and numbers were used instead of coordinates. Tree tags are attached to the street trees individually. It can make DB management simple and easy. 3) By doing simple or multiple search with constructed DB, data can be provided quickly. 4) The result of this type of search are useful in the assessment of management cost very useful in regards to items such as the pruning, pesticides scattering and fertilization. 5) By using the AutoCAD software and existing PC without purchasing new equipment, the cost of system implementation can be minimized.

• Journal of Magnetics
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• v.18 no.4
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• pp.481-486
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• 2013

An electromagnetic launcher (EML) system accelerates and launches a projectile by converting electric energy into kinetic energy. There are two types of EML systems under development: the rail gun and the coil gun. A railgun comprises a pair of parallel conducting rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail, but the high mechanical friction between the projectile and the rail can damage the projectile. A coil gun launches the projectile by the attractive magnetic force of the electromagnetic coil. A higher projectile muzzle velocity needs multiple stages of electromagnetic coils, which makes the coil gun EML system longer. As a result, the installation cost of a coil gun EML system is very high due to the large installation site needed for the EML. We present a coil gun EML system that has a new structure and arrangement for multiple electromagnetic coils to reduce the length of the system. A mathematical model of the proposed coil gun EML system is developed in order to calculate the magnetic field and forces, and to simulate the muzzle velocity of a projectile by driving and switching the electric current into multiple stages of electromagnetic coils. Using the proposed design, the length of the coil gun EML system is shortened by 31% compared with a conventional coil gun system while satisfying a target projectile muzzle velocity of over 100 m/s.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.381-388
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• 2003

The material deficiencies in the form of pre-existing defects can initiated cracks and fractures. The stress distribution and fatigue crack initiation life of engineering materials may be associated with the size, the shape and the relative location of defects contained in the component. The objective of this study is to investigate the effect of arbitrarily located hole defect around the rivet hole of a wing section in monolithic aluminum and Al/GFRP laminates under cyclic bending moment during a service load. The stress distribution and the fatigue crack initiation behavior near a rivet hole of on the relationships between stress concentration factor ($K_t$) and relative position of defects were considered. The test results indicated the features of different stress field. Therefore, the stress concentration factor ($K_t$) and the fatigue crack initiation behavior was illustrated different behavior according to each position of hole defect around the rivet hole in monolithic aluminum and Al/GFRP laminates.

• Smart Structures and Systems
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• v.26 no.4
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• pp.419-433
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• 2020

Investigation of structural integrity has been a critical issue in the field of civil engineering for years. Visual inspection is one of the most available methods to explore deteriorative components in structures. Still, this method is not applicable to invisible damage of structures. Alternatively, system identification methods are capable of tracking modal properties of structures over time. The deviation of these dynamic properties can serve as indicators to access structural integrity. In this study, a modal tracking technique using frequency-domain system identification from seismic responses of structures is proposed. The method first segments the measured signals into overlapped sequential portions and then establishes multiple Hankel matrices. Each Hankel matrix is then converted to the frequency domain, and a temporal-average frequency-domain Hankel matrix can be calculated. This study also proposes the frequency band selection that can divide the frequency-domain Hankel matrix into several portions in accordance with referenced natural frequencies. Once these referenced natural frequencies are unavailable, the first few right singular vectors by the singular value decomposition can offer these references. Finally, the frequency-domain stochastic subspace identification tracks the natural frequencies and mode shapes of structures through quick stabilization diagrams. To evaluate performance of the proposed method, a numerical study is carried out. Moreover, the long-term monitoring strong motion records at a specific site are exploited to assess the tracking performance. As seen in results, the proposed method is capable of tracking modal properties through seismic responses of structures.

• Journal of Chest Surgery
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• v.30 no.11
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• pp.1142-1144
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• 1997

A case of fatal hematemesis due to an aberrant right subclavian arterioesophageal fistula which is a rare complication of the vascular ring is presented. A 42-year-old man with multiple injury by traffic accident presented severe upper gastrointestinal bleeding and was taken emergent operation. He was keeping tracheostomy tube and nasogastric tube for 7 weeks. We could find an aberrant right subclavian arterioesophageal fistula through left thoracotomy which was made by irritation of the prolonged nasogastric ube. We carried division of the aberrant right subclavian artery and fistulectomy. He was doing well postoperatively. But massive bleeding occurred at the fifth postoperative day. We performed emergent reoperation at CCU and found the tear point on the suture site of the aorta, which might be developed due to irritation of the chest tube andfor infection of the surrounding tissues. He was expired at the 8th postoperative day due to ischemic brain damage.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.546-553
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• 2007

The objective of the present paper is to evaluate the effect of the evolution of contact surface profile by fretting wear on the contact stress distribution and fatigue crack initiation site of press-fitted shaft by means of an analytical method based on experimental data. A finite element analysis was performed to analyze the stress states of press-fitted shaft, considering the worn contact surface profiles of shaft. The evolutions of contact stress as wearing of contact surface were analyzed by finite element analysis and fatigue crack nucleation sites were evaluated by fretting fatigue damage parameter (FFDP) md multiaxial fatigue criteria. It is found that the stress concentration of a contact edge in press-fitted sha손 decreases rapidly at the initial stage of total fatigue life, and its location shifts from the contact edge to the inside due to fretting wear as increasing of fatigue cycles. Thus the transition of crack nucleation position in press-fitted shaft is mainly caused by stress change of a contact edge due to the evolution of contact surface profile by fretting wear. Therefore, it is suggested that the nucleation of multiple cracks on fretted surface of press fits is strongly related to the evolution of surface profile at the initial stage of total fatigue life.