• The Journal of Korean Physical Therapy
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• 제22권2호
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• pp.15-23
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• 2010

Purpose: This study was done to establish reference data for temporo-spatial, kinematic and kinetic parameters for normal Koreans as they age. Methods: Normal adults and children without a previous history of musculoskeletal problems were enrolled in this study. The normal subjects were divided by age into three groups: Group I: children ($11.95{\pm}0.29$ years); Group II: young adults ($23.90{\pm}3.67$ years); Group III: older adults ($71.40{\pm}4.08$ years). The temporo-spatial and kinematic data were measured using 6 MX3 cameras while each subject walked through a 10 m walkway at a self-selected speed. The kinetic data were measured using 2 force plates and were calculated by inverse dynamics. Results: Motion patterns are typically associated with a specific phase of the gait cycle. Our results were as follows: 1. There were significant differences between the different age groups in temporo-spatial parameters such as cadence, double support, time of foot off, stride length, step length, and walking speed. 2. There were significant differences between the groups in kinematic parameters such as range of motion (ROM) of the hip, knee and ankle in the sagittal plane, ROM of the pelvis, hip and knee in the coronal plane and ROM of the pelvis, hip and ankle in the transverse plane. 3. There were significant differences between the groups in kinetic parameters such as joint moments of force, joint mechanical power generation or absorption and ground reaction forces. Conclusion: The results of this study can be utilized (a) as a reference for kinematic and kinetic data of gait analysis in normal Koreans, and (b) as an aide in evaluating and treating patients who have problems relating to gait.

• 한국레이저가공학회지
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• 제16권3호
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• pp.11-21
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• 2013

As parts are becoming more complex and smaller with the development of new materials, high-quality laser precision processing is getting the limelight. Laser enables quick processing and less deformation of materials. It also enables welding with diverse materials. In this study, the pole rod and tap for the secondary battery were laser-welded using cross and coaxial nozzles. The results of the comparative analysis of cross and coaxial nozzles according to the processing parameters showed that the coaxial nozzle had more sensitive welding characteristic to the nozzle position or pressure than the cross nozzle. This indicated that the processing parameters should be carefully determined for the welding with the coaxial nozzle. The pole rod and tap were welded together in a form of T joint to improve the output of the secondary battery, and the cross nozzle had a better welding characteristic than the coaxial nozzle.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.193-214
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• 2017

In this paper, we study the problem of network utility maximization in a CSMA based multi-hop wireless network. Existing work in this aspect typically adopted continuous time Markov model for performance modelling, which fails to consider the channel conflict impact in actual CSMA networks. To maximize the utility of a CSMA based wireless network with channel conflict, in this paper, we first model its weighted network capacity (i.e., network capacity weighted by link queue length) and then propose a distributed link scheduling algorithm, called CSMA based Maximal-Weight Scheduling (C-MWS), to maximize the weighted network capacity. We derive the upper and lower bounds of network utility based on C-MWS. The derived bounds can help us to tune the C-MWS parameters for C-MWS to work in a distributed wireless network. Simulation results show that the joint optimization based on C-MWS can achieve near-optimal network utility when appropriate algorithm parameters are chosen and also show that the derived utility upper bound is very tight.

• 터널과지하공간
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• 제27권5호
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• pp.324-332
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• 2017

본 연구에서는 암반 절리 내 점성유체 주입시 주입 설계변수가 주입 성능에 미치는 영향을 평가할 목적으로 UDEC 프로그램을 사용하여 1차원 선형유동 해석을 수행하였다. 주입 설계변수로는 주입 압력, 유체 압축률, 주입재의 항복강도 및 점성도의 시간의존성, 주입 압력에 의한 절리의 역학적 변형을 설정하였으며, 주입재의 침투거리 및 주입 유량을 통해 주입 성능을 평가하였다. 수치해석 결과는 이론해를 통하여 파악한 주입 성능양상과 유사한 결과를 보였다. 주입재의 항복강도 및 점성도의 시간의존성을 고려하지 않을 경우, 주입재의 누적 주입량은 시간의존성을 고려한 해석에 비하여 약 1.2배 크게 평가되었다. 또한, 수리-역학 연계해석결과로부터 주입 압력에 의한 절리의 역학적 변형이 발생하는 경우, 절리 간극이 일정한 수리유동 해석에 비하여 누적 주입량이 약 4.4배 늘어나는 결과를 보였다.

• 터널과지하공간
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• 제22권6호
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• pp.438-448
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• 2012

이 연구는 암석 절리면의 거칠기 측정을 위하여 범용의 일안반사식 디지털카메라를 이용한 사진측량의 방법론 및 적용성을 고찰하였다. 암석 절리면에 대한 사진측량 및 레이저 프로파일러에 의한 측정을 통하여 다양한 이차원적 거칠기 단면을 구성하고 통계적 거칠기 파라미터를 산정한 결과 디지털 사진측량이 레이저 프로파일러에 비하여 거칠기를 과소평가 하는 것으로 나타났다. 거칠기의 정도에 따른 거칠기 파라미터의 변화양상은 두 측정법에서 매우 유사하게 나타났다. 카메라의 촬영방향은 거칠기 측정에 큰 영향을 미치지 못하는 것으로 분석되었다. 디지털 사진측량은 현장에서 비교적 큰 제약 없이 저비용으로 다양한 규모의 거칠기를 측정하는 데에 활용할 수 있을 것으로 기대된다.

• 로봇학회논문지
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• 제11권1호
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• pp.26-32
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• 2016

A variable release torque-based compliance spring-clutch (VCSC) is presented. VCSC is a safe joint to reduce the impact of collisions between humans and robots. It is composed of four functional plates, balls, springs to make some functions in compliant movement, release mechanism, gravity compensation during its work. Also, it can estimate torque applied to a joint by using distance sensor and parameters of cam profile. The measured variable torque of prototype is 4.3~7.6 Nm and release torque is 4.3 Nm. In our future studies, a calibration for torque estimation will be conducted.

• Journal of Korean Dental Science
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• 제8권1호
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• pp.16-27
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• 2015

Purpose: The purpose of this study was to evaluate the correlation between the clinical symptoms of temporomandibular disorder and findings in the magnetic resonance imaging (MRI). Materials and Methods: Clinical data and MRI images were collected from a total of 240 German patients. Clinical symptoms were briefed as joint clicking, crepitus and pain. MRI findings were further defined according to the condyle position, condyle degeneration, disc positon, disc degeneration and the presence of osteophyte/sclerosis/synovitis. Hypermobility was separately recorded. Correlation analysis between parameters was performed. Result: Joint clicking had a positive correlation with unilateral disc degeneration, osteophyte, sclerosis and synovitis. Crepitus had a significant correlation with bilateral osteophyte. Pain was not correlated with any MRI findings except hypermobility. Conclusion: Selective correlations between the MRI findings and clinical symptoms were elucidated. The results of this study imply that condyle-disc deformities could be advanced without pain, and that joint clicking and crepitus could be clinical symptoms of condyle-disc degeneration.

• Applied Microscopy
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• 제46권3호
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• pp.167-169
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• 2016

Solder/electroless nickel immersion gold (ENIG) joint sample which is comprised of dissimilar materials with different mechanical properties has limited the level of success in preparing thin samples for transmission electron microscopy (TEM). This short technical note reports the operation parameters for ultramicrotomy of solder joint sample and TEM analysis results. The solder joint sample was successfully sliced to 50~70 nm thick lamellae at slicing speed of 0.8~1.2 mm/s using a boat-type $45^{\circ}$ diamond knife. Ultramicrotomy can be applied as a routine sample preparation technique for TEM analysis of solder joints.

• Structural Engineering and Mechanics
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• 제56권3호
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• pp.355-367
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• 2015

This paper deals with a new designed joint system for single-layer spatial structures. As the stability of these structures is greatly influenced by the joint behaviour, the aim of this paper is the characterization of the joint response in bending through Finite Element Method (FEM) analysis using ABAQUS. The behaviour of the joints studied here was influenced by many geometrical factors, such as bolts and plate sizes, distance between bolts and end-plate thickness. The study comprised five models of joints with different values of those parameters. The numerical results were compared to the results of previous experimental tests and the agreement was good enough. The differences between the numerical and experimental initial stiffness are attributed to the simplifications introduced when modelling the bolt threads as well as the presence of residual stresses in the test specimens.

• 대한물리치료과학회지
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• 제10권2호
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• pp.42-52
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• 2003

An assessment of the subtalar joint in cerebral palsies can contribute to predict the function of ambulation in CP children. Ambulation is one of the most important function to guarantee the CP children independent life. This paper is to investigate some relationships between the function of standing and walling and the assessment of the subtalar joint in children with Cerebral palsy. And also to present the correlation between the ambulation and the Gross Motor Function Measures in children with cerebral palsy. Sixty-eight children with cerebral palsy were participated in this study. Evaluations of the subtalar pint parameters were performed by the goniometer and the angle finder, and the GMFM scores were measured by their teacher and researcher trained technically. A regression analysis was applied to figure out the relationship between the subtalar pint parameters(ROM and RCSP) and the function of standing and walking. A correlation analysis was employed to see how much the subtalar pint parameters could be predicted from GMFM scores in walling and standing. The results were as follows: 1) The significant differences were not observed between the total ROM, RCSP and the function of standing(F=8.065, p<.001) and walking(F=6.511, p<.001) in CP children. 2) The subtalar pint parameters(total ROM, RCSP) have the lower relevance to the function of standing and walling in CP children.(p>.05) 3) The total ROM and RCSP in both feet have the significant differences between the CP children and the normal children.(p<.001) 4) The GMFM scores were significantly correlated with the function of walling and standing in CP children.(r=247, p<.05) In this research, it is found that the significant relevance between the quantitative analysis of subtalar pint in children with cerebral palsy and the gross motor function of ambulation in standing and walling. However, it is difficult to predict the direct relationship of subtalar pint parameters and the function of ambulation, because subtalar pint scores and GMFM are only measured as quantities not qualities. Therefore, it is more reasonable to investigate the influence of subtalar pint parameters on ambulation in children with cerebral palsies, adding to the multifocal assessment of the children, rather than vice versa.