• 한국기계가공학회지
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• 제14권2호
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• pp.105-111
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• 2015

Car manufacturers and part manufacturers each have their own criteria with regard to strength, stiffness and NVH performance levels. Part manufacturers typically investigate such performances according to the part unit. To do this, the part manufacturer receives information from the relevant car maker. However, the information provided by the car maker is limited, making it difficult to develop a part which meets all of the design requirements specified by the car unit overall. To overcome this difficulty, the utilization of a VPG system is recommended for the designer. In this study, the durability performance of an optimized control arm as suggested in a previous study was investigated using the ETA-VPG, LS-dyna and FE/safe software packages. ETA-VPG provides several types of suspension and steering parts. In this study, a complete car is created using the library included in ETA-VPG, with the exception of the control arm. We also conducted a virtual proving ground analysis to predict the life cycle of the control arm.

• 한국기계가공학회지
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• 제13권5호
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• pp.116-122
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• 2014

In this study, 2 kinds of twist run models as exercise equipments are compared by durability analyses of fatigue and vibration. Maximum equivalent stresses are shown as 3.3 MPa and 16.6 MPa at the parts of stress concentrations at models 1 and 2. As the values becomes much lower than yield stress of this models, these models are shown to be safe designs. Model 1 becomes stronger than model 2 at natural frequency analysis. Fatigue lives become lowest at four axis parts and one axis part respectively in cases of models 1 and 2. Maximum damage probability at fatigue is shown to be 2.4% near the average stress of 0 in case of model 1 but this probability becomes 0.6 % in case of model 2. Model 1 has the maximum damage possibility 4 times more than model 2 at these states. As the result of this study is applied by the design of twist run, the prevention on fatigue damage and the durability are predicted.

• Physical Therapy Rehabilitation Science
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• 제1권1호
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• pp.1-5
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• 2012

Objective: Dual-task walking deficits impact functional daily life, which often requires walking while performing simultaneous tasks such as talking, thinking or carrying an object. This study is to find out the latest trend of dual-task training's influence on ambulatory abilities of a stroke patient. Design: Systematic review of randomized controlled trials. Methods: This literature review was conducted in Pubmed and Sciencedirect with the follwing key words:stroke, cerebro-vascular accident, hemiplegia, gait, rehabilitation, exercise. 7 studies were chosen in findings by search tool. 3 studies were case study, 3 studies were cross sectional observational study and 1 study was randomized controlled trial. Results: It was found that stroke patients have difficulties in doing 2 motor tasks simultaneously and when they do 2 tasks, one is done in a naturally preferred activity areas. Moreover, when simply applying dual-tasks, the walking speed decreased. Meanwhile, when applying them through training, the speed increased. This showed the improvement of effective task-implementation abilities after dual-task training using task-integration models. Conclusions: In the beginning of the 2000s, dual-tasks were implemented by simply combining walking and cognition or exercise task, and the results of this study suggest that subjects with stroke have difficulty performing dual task. However, the latest trend is to let patients do the dual-task training by combining it with virtual reality. Therefore, dual task training could be performed in a safe in the environment such as virtual reality or augment reality.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2009년도 추계학술발표대회 논문집
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• pp.213-216
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• 2009

The purpose of this study is analyzing temporal flow about 20 detailed performance items in the "Housing Performance Grading Indication System". This study try to figure out situations according grade in detailed performance item and to analyze change item about 112 cases(2 cases in 2006, 15 cases in 2007, 46 cases in 2008, 49 cases in 2009), from January 9, 2006 which system is undertaken, to October, 2009. This system consists of 5 main performance section, 14 performance categories and 20 detailed performance items. 5 main performance parts are Noise and Acoustics(Light-weight impact sound control, heavy-weight impact sound control, sound control of toilet, sound control of party wall), Long-life(flexibility, remodeling & maintenance, durability), Landscape & Indoor Environment(landscape, formaldehyde control & ventilation, daylighting, thermal environment), Welfare & Barrier-free(playground and community center, welfare space, barrier-free design), Fire Safety(fire safety, safe place, fire-resisting quality). Total efficiency about housing can understand systematically of 20 perfomance items though this research.

• 상하수도학회지
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• 제11권1호
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• pp.88-98
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• 1997

To obtain design and operating parameters for advanced water facilities, pilot test consisted of ozonation and GAC filtration was conducted at midstream of Nakdong River. Even though the concentrations were very low, 62 chemicals were detected above $0.005{\mu}g/L$ in raw water. In the preozonation, natural organic matters which could produce THMs and organics such as phenols and amines were effectively removed. The performance of TOC removal of GAC filtration with ozonation was better than GAC filtration alone and adsorption capacity of GAC adsorbers were ranged 3~6mg-TOC/g-carbon. And also the life of GAC adsorber for removing TOC was predicted more than 1 years if ozonation is introduced. This indicates that biological degradation of organics happened in GAC filters. Most organics detected at ppt level were removed below detection limit by GAC filtration with ozonation. These results show that ozonation and GAC filtration are the reliable and safe process for organic contaminants and chlorinated byproducts control at Nakdong River.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.786-791
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• 2006

Two stroke low speed diesel engines are mainly used for marine propulsion or power plant prime mover. These have many merits such as higher thermal efficiency, mobility and durability. However various annoying vibrations sometimes occur in ships or at the plant itself. Of these vibrations, torsional vibration is very important and it should be carefully investigated during the initial design stage for engine's safe operation. In this paper authors suggest a new estimation method of for shaft's can be calculated equivalently from accumulated fatigue cycles number due to torsional vibration. The 6S70MC-C($25,320ps{\times}91rpm$) engine for ship propulsion was selected as a case study, and the accumulated fatigue cycles numbers for shafting life time converted from the measured angular velocity and torsional vibration stress was calculated. This new method can be realized and confirmed in test model ship with two stroke low speed diesel engine.

• 한국자동차공학회논문집
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• 제20권4호
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• pp.133-141
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• 2012

This study investigates structural and fatigue analyses of bike brake. Maximum equivalent stress of the model of mountain bike is 4 times as much as the model of general bike at static analysis. In cases of mountain and general bikes, maximum damage frequency at load of 'SAE bracket history' with the severest change of load becomes as much as 16 times than the most stable load of 'Sample history' among the nonuniform fatigue loads. In case of mountain bike, the possibility of maximum damage becomes 3% at the load of 'Sample history' with the average stress of 0 to $-3{\times}10^4$MPa and the amplitude stress of 0 to $10^4$MPa. In case of general bike, the possibility of maximum damage becomes 3% at the load of 'Sample history' with the average stress of 0 to $-0.8{\times}10^4$MPa and the amplitude stress of 0 to $0.2{\times}10^4$MPa. This stress state can be shown as 5 to 6 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The analysis result of this study can be effectively utilized for the safe design of bike brake.

• Journal of Welding and Joining
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• 제14권2호
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• pp.36-45
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• 1996

Fatigue strength of the spot welded lap joint is considerably influenced by corrosive environments. Particularly, the chloride and the sulfide are most injurious to strength of the spot welded lap joint. Therefore, there is a need to evaluate its effect to corrosion fatigue strength for safe life design of spot welded structures. In order to evaluate their corrosion fatigue strength, corrosion fatigue tests on the spot welded lap joints of the uncoated and the coated high strength steel sheets were conducted in air and in 10% NaCl solution. Corrosion fatigue strength of the uncoated specimens were entirely lower than the coated one in NaCl solution, but those of the coated specimens in NaCl solution were lower than in air. And stress distribution in single spon welded lap joint subjected to tension-shear load was investigated by the finite element method. Using these results, we tried to evaluate corrosion fatgue strength of the various spot welded lap joints with maximum stress $\sigma_{max}$ at edge on loading side of the spot welded lap joint. We could find that corrosion fatigue strength could be quantitatively and systematically rearranged by $\sigma_{max}$.

• 대한기계학회논문집A
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• 제27권6호
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• pp.930-937
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• 2003

The extension of design life among power plants is increasingly becoming a world-wide trend. Kori #1 unit in Korea is operating two cycle. It has two man-ways for tube inspection in a steam generator which is one of the important components in a nuclear power plant. Especially, stud bolts fur man-way cover have damaged by disassembly and assembly several times and degradation for bolt materials for long term operation. It should be evaluated and compared by ASME Code criteria for integrity evaluation. Integrity evaluation criteria which has been made by the manufacturer is not applied on the stud bolts of nuclear pressure vessels directly because it is controlled by the yield stress of ASME Code. It can apply evaluation criteria through FEM analysis to damaged female threads and to evaluated safety fer helical-coil method which is used according to Code Case-N-496-1. From analysis results, we found .that it is the same results between stress intensity which got from FEM analysis on damaged female threads over 10％ by manufacture integrity criteria and 2／3 yield strength criteria on ASME Code. It was also confirmed that the helical-coil repair method would be safe.

• 한국전자통신학회논문지
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• 제11권3호
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• pp.245-252
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• 2016

유치원 통학을 위한 서비스 플랫폼은 비콘 장치, 버스에 장착되는 게이트웨이, 이동통신망 네트워크, 그리고 애플리케이션 서버로 구성된다. 본 논문에서 유치원 통학 서비스의 필요성을 이해하고, 유치원 원아의 비콘 규격 인식 자를 접속하고, 게이트웨이 리소스트리 기능들을 설계한다. 서비스 연동을 위해서, 통학 알림 기능이 부모님의 휴대폰 앱을 통하여 처리된다. 서비스 플랫폼은 등록된 비콘 데이터 수집과 운영 관리 기능들을 확인 할 수 있다.