• Earthquakes and Structures
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• v.18 no.6
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• pp.691-707
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• 2020

One of the most important issues in structural systems is evaluation of the margin of safety in low and mid-rise buildings against the progressive collapse mechanism due to the earthquake loads. In this paper, modeling of collapse propagation in structural elements of RC frame buildings is evaluated by tracing down the collapse points in beam and column structural elements, one after another, under earthquake loads and the influence of column removal is investigated on how the collapse expansion in beam and column structural members. For this reason, progressive collapse phenomenon is studied in 3-story and 5-story intermediate moment resisting frame buildings due to the corner and edge column removal in presence of the earthquake loads. In this way, distribution and propagation of the collapse in progressive collapse mechanism is studied, from the first element of the structure to the collapse of a large part of the building with investigating and comparing the results of nonlinear time history analyses (NLTHA) in presence of two-component accelograms proposed by FEMA_P695. Evaluation of the results, including the statistical survey of the number and sequence of the collapsed points in process of the collapse distribution in structural system, show that the progressive collapse distribution are special and similar in low-rise and mid-rise RC buildings due to the simultaneous effects of the column removal and the earthquake loads and various patterns of the progressive collapse distribution are proposed and presented to predict the collapse propagation in structural elements of similar buildings. So, the results of collapse distribution patterns and comparing the values of collapse can be utilized to provide practical methods in codes and guidelines to enhance the structural resistance against the progressive collapse mechanism and eventually, the value of damage can be controlled and minimized in similar buildings.

• Tuberculosis and Respiratory Diseases
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• v.82 no.3
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• pp.194-200
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• 2019

Background: Tuberculosis (TB) is a major infectious disease in South Korea causing substantial disease burden, particularly in the elderly. This study aimed to identify the case detection rate of mobile TB screening for the elderly conducted in the Jeollanam-do region and to analyze risk factors of active TB. Methods: We screened the elderly population (${\geq}65$ years old) in Jeollanam-do from August to December 2017. Chest radiography was performed for all participants. Participants with TB presumptive signs were asked to submit sputum specimen(s). Sputum smear, culture, and polymerase chain reaction analyses were performed. Cascade analysis, chi-squared tests, and Fisher exact tests were used to evaluate screening performance. Results: In total, 12,402 participants were screened, and 211 (1.7%) were suspected to have active TB; 181 of the suspected patients (85.8%) underwent sputum smear test, and 16 (8.8%) patients were confirmed to have TB. The TB prevalence among the elderly was bacteriologically confirmed to be 129 per 100,000 individuals, which was similar to national TB notification data for the same age groups. The proportion of active TB cases increased with age, and differed based on sex and past TB history. However, TB-related symptoms, comorbidity status, and TB screening history within 12 months were not predictive of active TB. Conclusion: This study identified that the prevalence rate was similar to national TB notification data from the same age groups. Periodic, community-based, systematic TB screening among the elderly population is recommended.

• Earthquakes and Structures
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• v.15 no.6
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• pp.639-654
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• 2018

Rocking motion have been used for achieving the 'resilient buildings' against earthquakes in recent studies. Low-rise buildings, unlike the tall ones, because of their small aspect ratio tend to slide rather than move in rocking mode. However, since rocking is more effective in seismic response reduction than sliding, it is desired to create rocking motion in low-rise buildings too. One way for this purpose is making the building's structure rock on its internal bay(s) by reducing the number of bays at the lower part of the building's skeleton, giving it a mushroom form. In this study 'mushroom skeleton' has been used for creating multi-story rocking regular steel buildings with square plan to rock on its one-by-one bay central lowest story. To show if this idea is effective, a set of mushroom buildings have been considered, and their seismic responses have been compared with those of their conventional counterparts, designed based on a conventional code. Also, a set of similar buildings with skeleton stronger than code requirement, to have immediate occupancy (IO) performance level, have been considered for comparison. Seismic responses, obtained by nonlinear time history analyses, using scaled three-dimensional accelerograms of selected earthquakes, show that by using appropriate 'mushroom skeleton' the seismic performance of buildings is upgraded to mostly IO level, while all of the conventional buildings experience collapse prevention (CP) level or beyond. The strong-skeleton buildings mostly present IO performance level as well, however, their base shear and absolute acceleration responses are much higher than the mushroom buildings.

• Journal of Digestive Cancer Reports
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• v.9 no.1
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• pp.8-18
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• 2021

Although many guidelines for pancreatic cystic neoplasms focus on the management of intraductal papillary mucinous neoplasm of the pancreas (IPMN) at the highest oncological risk, there are many issues that surgeons need to consider at the time to plan the surgical procedures based on characteristics of IPMN subtypes, such as multiplicity of branch duct-IPMN (BD-IPMN) and intraductal spreading of main duct-IPMN (MD-IPMN). For multifocal BD-IPMN, partial pancreatectomy would be selected to remove BD-IPMN with predictors of malignancy, while the other lesions without risk factors can be left, although total pancreatectomy might be considered if the patients have a strong family history of pancreatic cancer. Partial pancreatectomy would be also adequate procedure for MD-IPMN if negative surgical margin for high-grade dysplasia or invasive carcinoma were achieved. It has become to be well-known that patients with BD-IPMN are at increased risk for developing not only IPMN-associated pancreatic ductal adenocarcinoma (PDAC) but also PDAC independent from the IPMN. Hence, the detection of a concomitant PDAC is also an important focus for strategies after resection of BD-IPMNs. Our recent analysis of patients after partial pancreatectomy for MD-IPMN with negative surgical margin identified an unexpected recurrence pattern, which we called "monoclonal skip" recurrence. MD-IPMN seems to be disseminated in the pancreatic ductal systems and MD-IPMN with identical genetic background was detected in the remnant pancreas even in a long time after index surgery. We proposed strategies of postoperative surveillance based on characteristics and natural history of each morphological subtype.

• Archives of Craniofacial Surgery
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• v.23 no.2
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• pp.64-70
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• 2022

Background: Anterolateral thigh (ALT) flaps are versatile soft tissue flaps that have become the standard soft-tissue flaps used for head and neck reconstruction. They provide a long vascular pedicle, constant vessel diameter, abundant soft tissue coverage, and minimal donor site morbidity. The ALT flap was initially designed on the basis of a septocutaneous (SC) perforator. However, more recent research has shown that a substantial number of ALT flaps are now based on musculocutaneous (MC) perforators, and the ratio between MC and SC perforators varies among studies. In this study, we analyzed the perforating pattern of ALT flaps along with their clinical outcomes during head and neck reconstruction in the Korean population. Methods: From October 2016 to July 2020, 68 patients who had undergone an ALT flap procedure for head and neck reconstruction were enrolled retrospectively. The perforating pattern of the cutaneous perforator vessel (MC perforator/SC perforator/oblique branch), pedicle length, and flap size were analyzed intraoperatively. Patient demographics and flap necrosis rates were also calculated. Results: The highest number of cutaneous perforator vessels supplying the ALT flap were the MC perforators (87%). The proportion of MC perforators was significantly higher than that of the SC perforators and oblique branches. Flap necrosis occurred in seven cases (11.86%); sex, hypertension, diabetes mellitus, coronary artery disease, perforator course, and history of radiotherapy did not significantly affect flap necrosis. Conclusion: The ALT free flap procedure remains popular for reconstruction of the head and neck. In this study, we observed that the majority of cutaneous vessels supplying the flaps were MC perforators (87%). When using the MC perforator during flap elevation, careful dissection of the perforator is required to achieve successful ALT flaps because intramuscular dissection is difficult. Perforator pattern and history of radiotherapy did not affect flap necrosis.

• The Journal of Korean Philosophical History
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• no.27
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• pp.387-415
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• 2009

The crisis of moral-ethical school subject is related to the scientific identity of moral education in Korean society. Because it's identity hasn't been established yet exactly. At past time 'National Ethics' included not only moral education, but also anti-Communist education and education of political ideology or propaganda. The scientific foundation of ethical education is on ethics, and it is a branch of philosophy. But to escape this fact, some scholars relating with ethical education claimed to need 'interdisciplinary approach' to ethical subject. As a result, they allowed other department to give their certificates. Futhermore it is at a crisis to be integrated into social subject. Philosophy as scientific origin of ethics has already not interdisciplinary character but the idea of integrated science. So there is no necessity for finding another scientific foundation. Now following the original goal of ethical education, they try to train the ability of moral judgement to solve various moral problems rationally, and to cultivate moral disposition that can practice the ideal and principles of life.

• Earthquakes and Structures
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• v.5 no.6
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• pp.679-702
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• 2013

During an earthquake, soils filter and send out the shaking to the building and simultaneously it has the role of bearing the building vibrations and transmitting them back to the ground. In other words, the ground and the building interact with each other. Hence, soil-structure interaction (SSI) is a key parameter that affects the performance of buildings during the earthquakes and is worth to be taken into consideration. Columns are one of the most crucial elements in RC buildings that play an important role in stability of the building and must be able to dissipate energy under seismic loads. Recent earthquakes showed that formation of plastic hinges in columns is still possible as a result of strong ground motion, despite the application of strong column-weak beam concept, as recommended by various design codes. Energy is dissipated through the plastic deformation of specific zones at the end of a member without affecting the rest of the structure. The formation of a plastic hinge in an RC column in regions that experience inelastic actions depends on the column details as well as soil-structure interaction (SSI). In this paper, 854 different scenarios have been analyzed by inelastic time-history analyses to predict the nonlinear behavior of RC columns considering soil-structure interaction (SSI). The effects of axial load, height over depth ratio, main period of soil and structure as well as different characteristics of earthquakes, are evaluated analytically by finite element methods and the results are compared with corresponding experimental data. Findings from this study provide a simple expression to estimate plastic hinge length of RC columns including soil-structure interaction.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.7 no.1
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• pp.23-27
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• 2009

Purpose : The purpose of this study was to examine the effects of different medium frequency currents on afferent fibers. Methods : Thirty healthy volunteers who had no known history of neurological disorders were equally assigned to one of three groups; 2500Hz, 4000Hz, and control and each group was applied to the left wrist in palmer cutaneous branch of radial nerve by different medium frequency currents for 15 min. We measured the changes of thresholds for tactile, two-point discrimination, and thresholds for pain. Results : The results showed that the medium frequency currents stimulation increased thresholds for tactile, two-point discrimination, and thresholds for pain. However, there is no statistically significant difference between group 2500Hz and group 4000Hz. Conclusion : This may explain thresholds for tactile, two-point discrimination, and thresholds for pain plain medium frequency currents stimulation inhibits the excitability of afferent fibers, but the effect of the frequency difference within medium frequency currents is not demonstrated.

• Steel and Composite Structures
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• v.25 no.3
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• pp.315-326
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• 2017

In this work, thermoelastic dynamic behavior of functionally graded carbon nanotube reinforced composite (FG-CNTRC) cylinders subjected to mechanical pressure loads, uniform temperature environment or thermal gradient loads is investigated by a mesh-free method. The material properties and thermal stress wave propagation of the nanocomposite cylinders are derived after solving of the transient thermal equation and obtaining of the time history of temperature field of the cylinders. The nanocomposite cylinders are made of a polymer matrix and wavy single-walled carbon nanotubes (SWCNTs). The volume fraction of carbon nanotubes (CNTs) are assumed variable along the radial direction of the axisymmetric cylinder. Also, material properties of the polymer and CNT are assumed temperature-dependent and mechanical properties of the nanocomposite are estimated by a micro mechanical model in volume fraction form. In the mesh-free analysis, moving least squares shape functions are used to approximate temperature and displacement fields in the weak form of motion equation and transient thermal equation, respectively. Also, transformation method is used to impose their essential boundary conditions. Effects of waviness, volume fraction and distribution pattern of CNT, temperature of environment and direction of thermal gradient loads are investigated on the thermoelastic dynamic behavior of FG-CNTRC cylinders.

• Archives of Reconstructive Microsurgery
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• v.22 no.2
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• pp.78-81
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• 2013

Neurofibroma may present as a solitary lesion or as multiple lesions. Although there is no site of predilection for solitary lesions, occurrence on the hand is rare. Plexiform neurofibroma can develop in isolation or more commonly as a part of neurofibromatosis type 1. In those that apper in isolation, trauma has been suggested as a precipitating factor. A 68-year-old male farmer had experienced repetitive prior episodes of trauma in the involved finger. He presented with a painless mass on the dorsal aspect of the fifth finger. Physical examination showed a protruding mass measuring approximately $15{\times}20mm$ which was not tenderness to palpation and any skin changes or pigmentation. Ultrasonography showed a cystic mass on the dorsal aspect of the middle phalanx. Microsurgical dissection was applied in order to seperated the lesion from the ulnar side of the dorsal branch of the digital nerve. Pathologic examination of the specimens revealed neurofibroma. At three-month follow-up, motor and sensory function were intact, and range of motion was fully recovered. Traumatic solitary neurofibroma is a rare tumor of the hand, especially in the finger. Hand surgeons should be aware of the diagnostic possibilities of this tumor based on examination, history taking and imaging studies.