• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제21권4호
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• pp.245-275
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• 2017

The present investigation deals, Dufour and heat source effects on radiative MHD slip flow of a viscous fluid in a parallel porous plate channel in presence of chemical reaction. The non-linear coupled partial differential equations are solved by using two term perturbation technique subject to physically appropriate boundary conditions. The numerical values of the fluid velocity, temperature and concentration are displayed graphically whereas those of shear stress, rate of heat transfer and rate of mass transfer at the plate are presented in tabular form for various values of pertinent flow parameters. By increasing the slip parameter at the cold wall the velocity increases whereas the effect is totally reversed in the case of shear stress at the cold wall. It is observed that the effect of Dufour and heat source parameters decreases the velocity and temperature profiles.

• 한국공간구조학회논문집
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• 제19권1호
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• pp.65-73
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• 2019

This paper assesses the structural performance (force-slip response, slip modulus, and failure modes) of a CLT-concrete composite by conducting fifteen push-out test specimens. In addition, non-linear 3D finite element analysis was also developed to simulate the load-slip behavior of the CLT-concrete specimens under shear load. All 15 test specimens simulating the effect of concrete thickness, connection angle and penetration depth with four different shear connector types were built and tested to evaluate the flexural performance. Experimental results show that the maximum shear capacity for the composite action is obtained when the fixing angle is $90^{\circ}$ and the penetration depth of 95mm for SC normal screw was used to achieve ductile failure compared to other shear connectors.

• Advances in concrete construction
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• 제15권5호
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• pp.313-319
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• 2023

In this paper, the analytic solution has been found by using truncation approach. With the help of suitable substitution, different physical parameters are yielded in their non-dimensional form. The governing boundary layer partial differential equations are reduced to a set of ordinary ones by using appropriate similarity transformations. The velocity profile across the domain have also been taken into account. The effect normal velocity profiles buoyancy parameter, slip parameter, shrinking parameter, Casson fluid parameter on the heat profile. It is found that the normal velocity profiles rise with the buoyancy parameter and for the slip parameter. It is observed that the normal velocity profile decreases with the increase of shrinking parameter. The reverse behiour is found for the Casson fluid parameter. The results are numerically computed, analyzed and discussed. For the efficiency of present model, the results are compared with earlier investigations.

• 한국실내디자인학회논문집
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• 제41호
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• pp.121-128
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• 2003

This study was purposed to find that the elderly in Daejeon city evaluated design details in bathroom, stairway, entrance etc. On the base of housing expenses and an administrative district, the elderly over 65 were chosen and interviewed by well-trained investigators and 583 case was analyzed through SPSS PC 10.0. The results of this study were as follows ; they said a bathtub was necessary, the floor was not slippery, the height of basin was not high and the grab bar around toilet was not in bathroom and emergency bell was not in house. The elderly pointed out that the non-slip floor, grab bar, bathtub in bathroom and non-slip floor in entrance and stairs should be designed carefully. By the condition of the elderly' health and independent daily living and experience of housing, the evaluation of importance on bathroom and approach design by the elderly were different.

• 대한기계학회논문집
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• 제17권10호
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• pp.2646-2653
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• 1993

A rotational torque calibration system is developed to measure rotational torque of power generating systems and to calibrate non-contact rotational torque measurement systems. The maximum capacity of the developed system is 4.5 N-m. It is composed of a DC motor, a DC generator, a control system, a master torque cell, a slip ling/brush set, supporters, a bed etc. The control system is characterized by the closed-loop control with differential intergrator. Rotational torque measurement test and unit response test are conducted to estimate the accuracy of the developed system. It is found that system maintain high consistency and accuracy with the maximum error of 0.25%, Therefore the developed system can be used to measure the rotational torque of power generating systems and to calibrate non-contact rotational torque measurement systems.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2000년도 추계학술대회
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• pp.86-86
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• 2000

차량의 한목 바퀴가 웅덩이나 수렁에 빠졌을 태 동력이 한쪽바퀴로만 전달되어 수렁에서 빠져 나을 수가 없게 된다 따라서, 이러한 주행 조건에서 용이하게 빠져 나오게 하기 위하여 좌, 우측 바퀴에 전달되는 동력을 동시에 전달하는 장치가 필요하다. 이 장치가 개발 하고자 하는 NSD(차동제한장치)이다. 따라서 본 연구에서는, 국내외 특허 자료 조사 및 외국기술 동향을 파악하고 장단점을 비교 검토, 미끄럼 제어 알고리즘을 이용한 Non Slip Mechanism 설계, 설계 데이터에 의한 주요 부품별 강도 해석 및 안전성 검토, 위 내용을 기초로 하여 외국 제품과 비교하여 손색이 없는, 다소 우수한 기능을 가진 한국형 NSD를 개발하였으며, 시제품 제작과 성능시험을 준비중에 있다.

• 한국전산구조공학회논문집
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• 제32권6호
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• pp.409-416
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• 2019

본 논문에서는 폭발하중을 받는 철근콘크리트 슬래브의 비선형 해석을 위한 개선된 수치 모델을 제안한다. 제안된 모델은 2축 응력 상태를 반영한 등가 강도에 의해 정의된 응력-변형률 관계를 사용하여 응력 상태를 직접 결정하는 변형률 속도 의존 이등방성 구성 모델을 다룬다. 또한, 균열 발생 후 콘크리트와 철근 사이의 부착 슬립이 점차 확대되어 소성힌지 영역으로 집중된다. 2축 응력 상태에서 콘크리트의 균열 방향은 주응력 방향에 따라 달라지므로 이를 고려한 부착 슬립 모델을 해석에 도입하였다. 해석 모델의 검증을 위해 수치해석과 실험결과의 상관관계 연구(correlation studies)가 수행되었다. 해석결과는 재료모델의 2축 거동과 부착 슬립의 영향을 고려하는 것이 해석결과의 정확성 향상에 중요함을 보여주며 제안된 해석 모델이 철근콘크리트 슬래브 부재의 폭발해석에 효과적으로 사용될 수 있음을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.157-162
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• 2001

Fretting is a potential degradation mechanism of structural components and equipments exposed to various environments and loading conditions. The fretting degradation, for example, can be observed in equipments of nuclear, fossil as well as petroleum chemical plants exposed to special environments and loading conditions. It is well known that a cast stainless steel(CF8M) used in a primary reactor coolant(RCS) degrades seriously when that material is exposed to temperature range ken $290^{\circ}C{\sim}390^{\circ}C$ for long period. This degradation can be resulted into a catastrophical failure of components. In the present paper, the characteristics of the fretting fatigue are investigated using the artificially aged CF8M specimen. The specimen of CF8M are prepared by an artificially accelerated aging technique holding 1800hr at $430^{\circ}C$ respectively. Through the investigations, the simple fatigue endurance limit of the virgin specimen is not altered from that obtained from the fatigue tests imposed the fretting fatigue. The similar tests are performed using the degraded specimen. The results are not changed from those of the virgin specimen. The significant effects of fretting fatigue imposed on both virgin and degraded specimen on the fatigue strength are not found.

• Kyungpook Mathematical Journal
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• 제61권4호
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• pp.831-843
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• 2021

In this paper we look at the three dimensional stagnation point flow problem over a rough rotating disk. We study the theoretical behaviour of the stagnation point flow, or forced flow, in the presence of a slip factor in which convective instability stationary modes appear. We make a numerical investigation of the effects of slip on the behaviour of the flow components of the stagnation point flow where the disk is rough. We provide, for the first time in the literature, a complete convective instability analysis and an energy analysis. Suitable similarity transformations are used to reduce the Navier-Stokes equations and the continuity equation into a system of highly non-linear coupled ordinary differential equations, and these are solved numerically subject to suitable boundary conditions using the bvp4c function of MATLAB. The convective instability analysis and the energy analysis are performed using the Chebyshev spectral method in order to obtain the neutral curves and the energy bars. We observe that the roughness of the disk has a destabilising effect on both Type-I and Type-II instability modes. The results obtained will be prominently treated as benchmarks for our future studies on stagnation flow.

• Journal of Trauma and Injury
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• 제22권1호
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• pp.29-36
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• 2009

Purpose: The purpose of this study was to analyze the characteristics and severity of wrist injuries in snowboarding. Methods: December 2005 to February 2008, Snowboarders who experienced wrist injures were included in this study. On the basis of the medical records and radiographic evaluation, the severity of distal radius fracture was classified according to the Arbeitsgemeinschaft fur Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF) classification. Results: Most of the injured snowboarders were a either of the beginner (35 cases, 46.1%) or the intermediate (27 cases, 35.5%) level. The most common cause of injury in snowboarding was a slip down (60 cases, 78.9%). Comminuted and articular fractures classified as AO types A3, B, and C, which required surgical reduction, made up 42.3% of the distal radial fractures in snowboarders. When we analyzed the differences in severity between the educated and the non-educated groups, an A2 type injury in the AO classification was the most common type of injury in the educated group (20 cases, 38.5%), it means less severe fractures ocurred in the educated group (p=0.045). The most frequent injury mechanism of fractures was slip down (48 cases, 63.2%), and a slip down backwards was the dominant type of slip down (36 cases, 75.0%) (p=0.031). Conclusion: Among the snowboarders in this study who suffered self-down injury to the wrist, more fractures were associated with a backwards slip down than with a forward slip down due to over extension. For educated snowboarders the severity of fracture was lower than it was for uneducated snowboarders.