• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.142-142
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• 2016

무전해 니켈 도금은 산업기계 부품, 자동차 부품, 항공 및 전자 통신 부품 등에 이르기까지 산업 전반에서 폭넓게 사용되고 있다. 이는 무전해 니켈 도금 층이 우수한 균일성, 내마멸성, 내식성 등을 지녀 관련 연구가 지속적으로 활발하게 진행되어 왔기 때문이다. 특히, 최근에 이르기까지 도금 층이 얇고, 우수한 내마멸성 및 낮은 마찰계수를 활용한 무전해 니켈 도금은 산업현장에서 기계 부품들의 수명을 연장시키고, 그 성능을 개선시키는데 용이하게 적용되고 있다. 본 연구에서는 이와 같이 무전해 니켈 도금 층의 우수한 특성을 활용하여 해수 부식과 캐비테이션-침식 복합 환경 하에 놓여 있는 금속 재료의 손상을 방지하고자 하였다. 이는 선박의 경우 최근 고속화, 대형화 추세에 따라 부품의 내구성 향상과 연비 효율성이 더욱 강조되고 있으며, 그에 따라 해수 속에서 고속 회전으로 더욱 가혹해진 캐비테이션 침식-부식 환경하에 놓인 선박의 프로펠러, 펌프 임펠러 및 케이싱 등의 금속재료 자체를 보호할 수 있는 고성능 재료의 개발이 요구되고 있기 때문이다. 또한 해양환경 하에서 무전해 니켈 도금 층에 대한 캐비테이션 침식 손상에 대한 연구는 미비한 실정이다. 본 연구에서는 회주철 표면에 무전해 니켈 도금을 실시하여 캐비테이션 침식 손상을 방지하고자 하였다. 무전해 니켈 도금을 실시하기 전 도금 층을 균일하게 형성하기 위해 샌드 페이퍼 #1200까지 연마 후 알칼리 탈지 실시하고, 산세(10% HCl)와 수세를 순차적으로 실시하여 전처리하였다. 이후 무전해 니켈 도금은 황산니켈, 차아인산나트륨, 구연산, 아세트산나트륨 그리고 미량의 질산납으로 구성된 도금욕에서 pH 4-6, $80-90^{\circ}C$의 조건으로 실시하였으며, pH는 NaOH를 이용하여 조정하였다. 이렇게 제작된 무전해 니켈 도금 층에 대하여 천연 해수 속에서 ASTM-G32 규정에 의거한 캐비테이션 침식실험을 통해 내구성을 평가하였다. 캐비테이션 실험 후에는 무게 감소량, 표면 손상깊이, 침식 손상 경향 등을 종합적으로 분석 비교하였다. 그 결과, 회주철에 대하여 무전해 니켈 도금을 실시할 경우 현저한 캐비테이션-침식 저항성 향상이 관찰되었다.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.289-296
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• 2015

This convergence study was conducted to compare difference of risk behaviors and injury incidence between younger(under 65 years) and elderly(over 65 years). For this analysis we used law data of nation-wide community health survey data during August to October 2010. Data of drink-driving, seat belt use, injury incidence rate, type of injury, cause of injury were used for comparison. Seat belt use(85.16% vs 78.81%) was high but drink-driving(12.99% vs 13.24%) was low in elderly. Injury incidence was high especially in falls(1.07% vs 2.22%). In conclusion, elderly do less risk behaviors, but experienced much more injuries especially falls.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.5
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• pp.445-452
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• 2009

In this paper, damage detection procedure using the finite element model updating was formulated and applied to a small-scale frame structure. FE model updating is the analytical method which finds the mathematical model that generates the measured dynamic properties similarly, and can be effectively used for the damage detection and SHM. For model updating, several kinds of dynamic properties, such as the natural frequencies, mode shapes, and frequency response functions, can be used as the inputs. In this paper, two kinds of model updating procedures using the natrual frequency and the frequency response function, and the natrual frequency and the mode shapes, respectively, were applied to identify the location and the severity of damage of the test structure, which is a four-story two bay steel structure. Results from the damage detection showed that more accurate identification results was obtained when the natrual frequency and the frequency response function were used than when the natrual frequency and the mode shapes were used.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.239-244
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• 2020

The purpose of this study is to provide basic data for injury prevention measures through the risk factors of injury occurrence by comprehending injury characteristics of the trauma patients visiting a regional emergency medical center according to distribution based on external causes and injury severity score. This study was analyzed using SPSS-Window(ver. 20.1) for 2585 trauma patients who visited a regional emergency medical center and the research period is for four months from 1st of September, 2019 to 31th of December, 2019. The following were the results of the research. First, it is shown from the analyzed data that the proportion of males (61.3%) is greater than that of females (38.7%) and the group aged from 20 to 50 had a significantly higher occurrence rate of injury but in terms of injury severity, 50 takes up the great proportion(P<.001). Second, roads and traffic areas (35.1%) were the highest in the place of occurrence of injury(P<.001). Third, the time of injury occurrence was as high as 12-18 hours(35.8%)(P<.001). Fourth, the injury part was highest in the head and face (55.4%)(P<.001). Fifth, the type of injury was higher in open wounds (31.2%)(P<.001). Therefore, it is required to establish detailed injury prevention policies according to the characteristics of injury severity.

• Tunnel and Underground Space
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• v.34 no.1
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• pp.15-27
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• 2024

In this case study, detailed survey of the Excavation Damaged Zone (EDZ) evaluation for the deep geological repository for high level nuclear waste was conducted. Oversea and Domestic case studies were compiled and investigated. EDZ is considered a crucial factor in the performance assessment of spent fuel disposal, leading to numerous studies worldwide aiming to understand the characteristics of the EDZ and quantitatively assessment of its extent through field and laboratory tests at Underground Research Laboratory (URL) sites. To enhance the understanding of EDZ, this study begins with defining and exploring the history of EDZ, compiling factors influencing EDZ, and summarizing the impacts caused by EDZ. Subsequently, an analysis of EDZ and rock properties is performed, followed by presenting generalized outcomes, limitations drawn from previous research, and proposing future research directions.

• Journal of the Korean Arthroscopy Society
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• v.15 no.1
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• pp.58-68
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• 2011

Acromioclavicular (AC) joint dislocations are common injuries in active individuals secondary to direct force on the lateral aspect of the adducted shoulder. Complete disruption of the acromioclavicular and coracoclavicular (CC) ligaments may occur, depending on the magnitude of the insulting force. Most of these injuries are successfully treated without surgery. However, for the treatment of cases in which surgical management is warranted, there are more than 100 surgical techniques available without a gold standard technique. We review the anatomy of the acromioclavicular joint, the diagnosis of disorders of this joint, and the different treatment options in this article.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2807-2808
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• 2003

말초 신경계에서 손상된 신경은 그 손상된 정도에 따라 재생의 정도가 달라진다. 이러한 신경 재생의 정도를 확인할 수 있는 방법으로 초미세 전극 어레이 기술이 연구되고 있는데 이것은 전기신호경로(via hole)를 초미세 전극어레이를 제작하여, 손상된 신경의 근위부(proximal stump)와 원위부(distal stump) 사이에 직접 삽입하여 선경으로부터 재생되어온 신경 섬유의 전기적 전도 선호를 측정 및 기록하는 것이다. 이는 신경 재생을 관찰하는 방법으로서 신경보철(neural prostheses) 기술에 이용된다. 따라서, 본 논문에서는 손상된 신경의 재생을 관찰하기 위한 implantable microelectrode array system을 설계하고, 원 신호인 선경 전도 신호의 특성과 제작된 이식형 초미세전극(implantable microelectrode)의 특성을 고찰하며, 동물 실험을 통하여 그 성능을 검증하였다.

• Composites Research
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• v.35 no.6
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• pp.439-446
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• 2022

In this study, fiber-reinforced composite coil springs for automobiles were manufactured using the braiding method, and mechanical tests and damage evaluation were performed to confirm their safety. Through the analysis of the load-displacement behavior, the stiffness of the springs was evaluated to meet the specifications. In addition, the distribution of voids and the impregnation rate on the spring wire section were analyzed to clearly understand the criteria for the mechanical properties of the composite material. Moreover, the tested springs were visually inspected to confirm the damaged parts, and the failure mode was analyzed by observing crack initiation and propagation behavior of cross-sectional samples taken from the crack and failure adjacent areas of springs using SEM.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.165-174
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• 2011

This research aims at the optimal constitution of sensors required to identify the structural shortcoming of roller-coaster. In this research we analyzed the dynamic characteristics of roller-coaster by three dimensional FE modelling, decided on the appropriate location and number of sensors through optimal transducer theory, abstracted the mathematical value of modal features before and after damage on the basis of optimally placed and numbered sensors. and then presented it as a primary information about the basic structure which would be applied to damage estimation. As a target structure, the roller-coater at Seoul Children's Grand Park was chosen and built as a model reduced by one twentieth in size. In order to consider the Kinetics features particular to the roller-coaster structure, we made an exact three-dimensional FE modelling for the model structure by means of Spline function. As for the proper location and number of sensors, it was done by applying EIM and EOT. We also estimated the damage from the combination of strength, flexibility, and model corelation after abstracting the value of modal features. Finally the optimal transducer theory presented here in this research was proved to be valid, and the structural damage was well identified through changes in strength and flexibility. As a result, we were able to present the optimal constitution of sensors needed for the analysis of dynamic characteristics and the development of techniques in dynamic characteristics, which would ultimately contribute to the development of health monitoring for roller-coaster.

• 열병합발전
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• s.51
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• pp.11-16
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• 2006