• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.459-466
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• 2006

The objective of this study is to improve the accuracy of damage detection using natural frequency and modal strain energy. The following approaches are used to achieve the goal. First, modal strain energy is introduced and newly GA-based damage detection technique using natural frequency and modal strain energy is proposed. Next, to verify efficiency of the proposed technique, damage scenarios for free-free beams are designed and the vibration modal tests as damage cases are conducted. Finally, feasibility of proposed technique is verified in comparison with a GA-based damage detection technique using natural frequency and mode shape.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.43-48
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• 2007

In this study, an ANN-based damage detection algorithm using acceleration signals is developed for alarming locations of damage in beam-type structures. A new ANN-algorithm using output-only acceleration responses is designed for damage detection in real time. The cross-covariance of two acceleration signals measured at two different locations is selected as the feature representing the structural condition. Neural networks are trained for potential loading patterns and damage scenarios of the target structure for which its actual loadings are unknown. The feasibility and practicality of the proposed method are evaluated from laboratory-model tests on free-free beams for which accelerations were measured before and after several damage cases.

• 대한기계학회논문집
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• 제19권9호
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• pp.2105-2113
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• 1995

The compressive tests under impact conditions were performed to establish a design guide for impact damage tolerance. The composition of layup was selected for the real cases of composite aircraft structure. The energy level of visible of visible damage threshold was determined as 7 Joules. It was found that the normalized bending stiffnesses in the direction of closely fixed boundary affected the area of damage. Graphite/epoxy used in the tests exhibited 60% reduction in compression strength at the energy level of visible damage threshold. Wet-conditioned specimens represented 9% reduction in residual compressive strength in comparison with room temperature ambient specimens. In this study, a design factor of 2.1 was proposed for the low velocity impact damage.

• Smart Structures and Systems
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• 제25권1호
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• pp.47-56
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• 2020

This paper proposes a model-based approach for structural damage identification and quantification. Using pseudo modal strain energy and mode shape vectors, a damage-sensitive objective function is introduced which is suitable for damage estimation and quantification in shear frames. Whale optimization algorithm (WOA) is used to solve the problem and report the optimal solution as damage detection results. To illustrate the capability of the proposed method, a numerical example of a shear frame under different damage patterns is studied in both ideal and noisy cases. Furthermore, the performance of the WOA is compared with particle swarm optimization algorithm, as one the widely-used optimization techniques. The applicability of the method is also experimentally investigated by studying a six-story shear frame tested on a shake table. Based on the obtained results, the proposed method is able to assess the health of the shear building structures with high level of accuracy.

• Journal of Chest Surgery
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• 제22권3호
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• pp.402-415
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• 1989

Extracorporeal circulation leads to functional disorder and structural damage of organs, especially hematologic and pulmonary system, mainly by sequestration of neutrophils and deposition of macrophages at lung. Then, proteases are secreted, which insult vascular basement membrane of pulmonary capillary and alveolar septa of the lung. Among these, the most important protease at lung is elastase, because major component of lung is elastin. For prevention of lung injury, inactivators or antidotes to elastase should be necessary and Alpha 1-Proteinase Inhibitor is the elastase inactivator. Clinical experimental study was carried out to investigate the immediate postoperative change of serum Alpha 1-PI level following cardiopulmonary bypass for 20 heart cases [congenital 16 cases, acquired 4 cases] and 10 control [subtotal gastrectomy] cases. Also preliminary study was performed for 31 cases of open heart patients. The results were as follows: l. Immediate postoperative serum levels of Alpha 1-PI was significantly decreased at open heart surgery group [P< 0.005], but not decreased at control group. 2. There were no significant difference in change of serum Alpha 1-PI level between and membrane and bubble oxygenator group.Z 3. There were no significant difference in changes of serum Alpha 1-PI level between CHD and AHD. Alpha 1-PI is consumed at lung during cardiopulmonary bypass and increase after operation compensatedly and protect multiple organic damage especially lung. Therefore, Alpha 1-PI can be indicator for evaluation of prevention and treatment of pump-lung syndrome.

• Smart Structures and Systems
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• 제5권1호
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• pp.95-117
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• 2009

In this paper, the time series based damage detection algorithms developed by Nair, et al. (2006) and Nair and Kiremidjian (2007) are applied to the benchmark experimental data from the National Center for Research on Earthquake Engineering (NCREE) in Taipei, Taiwan. Both acceleration and strain data are analyzed. The data are modeled as autoregressive (AR) processes, and damage sensitive features (DSF) and feature vectors are defined in terms of the first three AR coefficients. In the first algorithm developed by Nair, et al. (2006), hypothesis tests using the t-statistic are applied to evaluate the damaged state. A damage measure (DM) is defined to measure the damage extent. The results show that the DSF's from the acceleration data can detect damage while the DSF from the strain data can be used to localize the damage. The DM can be used for damage quantification. In the second algorithm developed by Nair and Kiremidjian (2007) a Gaussian Mixture Model (GMM) is used to model the feature vector, and the Mahalanobis distance is defined to measure damage extent. Additional distance measures are defined and applied in this paper to quantify damage. The results show that damage measures can be used to detect, quantify, and localize the damage for the high intensity and the bidirectional loading cases.

• Journal of Chest Surgery
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• 제54권6호
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• pp.535-538
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• 2021

Schwannomas are rare benign tumors that develop in Schwann cells lining peripheral nerves. Schwannomas of the brachial plexus are especially rare, accounting for 5% of all cases. Although several treatments can be considered, the exact method of treatment is unclear owing to the scarcity and sporadic occurrence of schwannomas. Tumor resection is performed in most cases, and nerve damage is inevitable in cases of neuroinvasive schwannoma. In this case series, we present our successful use of transposition of cable-grafted nerves for the treatment of schwannomas. We performed cable-grafted nerve interposition in addition to tumor resection, leading to increased recovery of nerve damage. To relieve postoperative symptoms and minimize sequelae, precise surgical tumor resection followed by nerve interposition using a cable-grafted nerve may be recommended.

• 대한관절경학회지
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• 제8권2호
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• pp.94-97
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• 2004

목적: 관절경하 후방 십자 인대 재건술시 지혈대의 필요성에 대한 언급된 문헌이 없어 지혈 대 없이 시행하는 본원의 관절경하 후방십자인대 재건술 결과 및 술기에 대해 보고하고자 한다. 대상 및 방법: 1998년 1월부터 2003년 5월까지 본원에서 후방십자인대 손상으로 관절경을 시행한 75례중 외측 측부인대 및 후외측 측부인대와 같은 동반손상으로 인해 관절외적 시술로 지혈대를 시행한 환자 16례와 술후 추시관찰이 12개월 이하인 10례를 제외한 49례의 단독 후방 십자 인대 손상 환자를 대상으로 하였고 자가 골-슬개건-골을 이용하여 재건한 경우 13례, 동종 골-슬개건-골을 이용하여 재건한 경우 19례, 동종 아킬레스 건을 이용하여 재건한 경우 17례였다 평가방법은 49례를 Lysholm knee scoring scale을 이용하여 비교하였다. 결과: 지혈대 없이 관절경하 후방 십자 인대 재건술을 한 경우 수술시간은 평균 105분 소요되었으며, 출혈로 인해 시야가 혼탁하여 지혈대를 사용한 경우는 없었다. 모든 환자에서 수술 부위의 부종, 국소 종창, 울혈, 환부 감염등은 관찰되지 않았다. Lysholm knee scoring scale을 이용한 평가 결과는 자가 골-슬개건-골을 이용한 경우는 평균 74점(fair) , 동종 아킬레스 건을 이용한 경우 75점(fair) , 동종 슬개건-골을 이용한 경우는 76점(fair)였다 결론: 관절경하 후방십자인대 재건술시 지혈대를 사용하지 않아도 수술에 어려움은 없으므로 지혈대 없이 재건술을 시행함으로써 지혈대로 인해 야기되는 합병증을 방지할 수 있을 것으로 생각된다.

• 한국조리학회지
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• 제12권2호
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• pp.151-167
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• 2006

This study shows the differences among residents’ consciousness for general infectious disease and sterilization mediated by vermin. We categorized both industry-related people who work in restaurants, hygiene service shops, whole sales, government organizations, PC shops, factories, department stores and non-industry-related people who work in schools, general offices into two groups for this study. The discovery of vermin held 86% of total exam cases. The vermin included mosquitoes, cockroaches, ants, flies, and so on. People thought these vermin might mediate bacteria infection to human. 80.3% of persons thought mite might exist in blankets, beds and couches. Among 66.6% of total experience of vermin damage, the main damage came from mosquitoes. Frequently used methods of prevention from vermin damage were as follows: "spray of effective chemicals", "install traps" and " report to a prevention company" in order. It indicated that people did not take special actions to repel vermin in spite of their knowing seriousness of damage. Furthermore, just half cases were executed regular sanitization.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권4호
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• pp.339-344
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• 2004

The purpose of this study was to evaluate neurosensory disturbance associated with implant surgery performed by implant practitioner (n=47) composed of trained oral surgeon, periodontist, prosthodontist. The incidence, type and duration of sensory disorder were investigated. Anatomical factor of the patient and experience of operator were also evaluated. The result revealed high incidence of inferior alveolar nerve damage (45%) regardless of experience of implant practitioner. The sensory disturbance sustained within 6 months for 61% of cases, which revealed almost normal recovery of nerve function. Initial neurologic sign after nerve damage was not coincide with their consequence of recovery. Half of the practitioners tried surgical intervention to the implants such as removing the fixture, partial unscrewing or re-implant shorter fixture, of which trial regarded as effective measure for 53% of cases. The result indicates that the objective method of sensory nerve evaluation should be introduced to the implant practitioners and the importance of informed consent for possibility of nerve damage in mandibular implant fixation.