• Clinics in Shoulder and Elbow
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• 제27권2호
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• pp.183-195
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• 2024

Background: Reverse total shoulder arthroplasty (rTSA) has gained popularity in recent years and is indicated for a wide variety of shoulder pathologies. However, use of rTSA in patients with "weight-bearing" shoulders that support wheelchair use or crutches has higher risk. The aim of this study was to assess the results of rTSA in such patients. Methods: Between 2005 and 2014, 24 patients (30 shoulders) with weight-bearing shoulders were treated with rTSA at our unit. Patients had cuff arthropathy (n=21), rheumatoid arthritis (n=3), osteoarthritis (n=1), acute fracture (n=3), or fracture sequela (n=2). Postoperatively, patients were advised not to push themselves up and out of their wheelchair for 6 weeks. This study was performed in 2016, and 21 patients (27 shoulders) were available for a mean follow-up of 5.6 years (range, 2-10 years). The mean age at surgery was 78 years (range, 54-90 years). Results: Constant-Murley score improved from 9.4 preoperatively to 59.8 at the final follow-up (P=0.001). Pain score improved from 2/15 to 13.8/15 (P=0.001). Patient satisfaction (Subjective Shoulder Value) improved from 0.6/10 to 8.7/10 (P=0.001). Significant improvement in mean range of motion from 46° to 130° of elevation, 14° to 35° of external rotation, and 29° to 78° internal rotation was recorded (P=0.001). Final mean Activities of Daily Living External and Internal Rotation was 32.4/36. Only three patients showed Sirveaux-Nerot grade-1 (10%) glenoid notching and three grade 2 (10%). Conclusions: rTSA can be used for treatment of patients with weight-bearing shoulders. Such patients reported pain free movement, resumed daily activities, and high satisfaction rates.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.84-88
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• 2008

The roller bearings play an important role not only sustain radial or axial load of system, but carry out a rotatory movement as a various operating conditions. They happen that incipient faults which were caused by excessive load, manufacturing or assembling process's errors and many other reasons are created. The bearing faults make noise and vibration by a continuous collision of rotatory components, which can lower the quality and stability of auto-transmission. Therefore, it is important to detect the early fault as soon as possible. This paper presents a detecting method for the improvement in quality by developing the program which can be used to analyze and predict the vibrational characteristics caused by roller bearing faults. We completed development of the inspection system of vibration by appling the most efficient detecting methods and verified the system's reliability through experiments.

• 한국정밀공학회지
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• 제19권5호
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• pp.126-132
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• 2002

Misaligned shafts of the rotating machinery have caused noise, vibration. bearing failures, and stress concentration of coupling parts which decrease the efficiency and life of shaft systems. Therefore the proper shaft alignment of those system should be monitored continuously in dynamic condition. To solve these problems under dynamic condition a telemetry system is used. In this study, the condition of the least bending moment which is known by analyzing the structure and stress induced by misalignment is found. After the shaft is aligned by dial gage, a telemetry system with strain gages is installed on shaft. The relationship between bearing displacement and moment of coupling part influenced by misalignment is investigated. The moment derived from two shaft strain at the nearby coupling is measured. The bending strain is measured 5 times for average in static state as well as in dynamic state with 100∼700 rpm.

• 한국산학기술학회논문지
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• 제7권4호
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• pp.697-703
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• 2006

본 논문에서는 국내. 외에서 처음으로 시도되는 현장타설 팽이기초공법의 거동특성을 검토하기 위하여 기초형식을 현장타설 팽이기초(In-Situ TBF), 공장제작 콘크리트 팽이기초(PC-TBF) 전면기초, 무처리 원지반으로 나누어 모형토조실험을 수행하였다. 모형실험결과 현장타설 팽이기초와 공장제작 콘크리트 팽이기초의 거동특성은 거의 유사하게 나타났으며, 이들 팽이기초는 원지반 및 전면기초에 비하여 지지력 증대효과가 있는 것으로 나타났다. 또한, 기초 형식에 따른 지중연직응력 분포를 검토한 결과 팽이기초 설치시 지중연직응력의 영향범위가 감소하는 것을 확인할 수 있었다. 한편, 지반이 조밀할수록 팽이기초의 응력분산효과가 감소하는 것을 알 수 있었으며, 향후 다양한 지반조건에서 모형실험과 수치해석을 통해 보다 많은 검토가 수행되어야 할 것으로 판단된다.

• 한국소음진동공학회논문집
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• 제19권3호
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• pp.268-273
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• 2009

The roller bearings play an important role not only sustain radial or axial load of system, but carry out a rotatory movement as a various operating conditions. They happen that incipient faults which were caused by excessive load, manufacturing or assembling process's errors and many other reasons are created. The bearing faults make noise and vibration by a continuous collision of rotatory components, which can lower the quality and stability of auto-transmission. Therefore, it is important to detect the early fault as soon as possible. This paper presents a detecting method for the improvement in quality by developing the program which can be used to analyze and predict the vibrational characteristics caused by roller bearing faults. We completed development of the inspection system of vibration by applying the most efficient detecting methods and verified the system's reliability through experiments.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.401-406
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• 2013

This paper presents experimental evaluation of IRE (isolation roller bearing) seismic isolation device. From the combination of base isolation on the IRE system displacement response spectrum and acceleration response spectrum, the compressive strength and the coefficient of friction experiments. Also the IRE system is evaluated by environment test according to KS standards. Both the resonance and seismic experiments using a combination of the IRE and Natural Rubber Bearing (NRB) are performed in order to analyze the seismic isolation of the IRE system dynamic characteristics. For the given load and exciting frequency, the resonant frequency becomes lower, but the resonant magnification remains to be same. However, it is shown that when we consider the IRE only, the vibration on the table with the horizontal movement and the independent horizontal displacement due to the rolling motion of the plate and roller are significantly reduced. This result verifies that the proposed optimal design method of the IRE system is very effective.

• PNF and Movement
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• 제11권2호
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• pp.21-29
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• 2013

Purpose : The study was to evaluate the weight distribution, balance and gait function of stroke patients wearing lateral wedged insole to the shoe of the affected side. Methods : 27 patients with stroke (15 men, 12 women) participated in this study. Participants performed weight distribution, dynamic balance and gait ability with or without wedged insole on affected side in a random order. The balancia was used to evaluate the weight distribution. Deviation from the center line was analyzed by Dartfish during sit to stand to evaluate dynamic balance. The functional walk ability evaluated by 10 m walking velocity. Results : The asymmetry index of weight bearing improved significantly with wedged insole of affected side(p<.05). During sit to stand, center of gravity significantly moved from non-affected side to more mid line of body(p<.05). Improvement were shown in walking speed after wearing the wedged insole(p<.05). Conclusion : Wedged insole applied on affected side have a beneficial effect on weight distribution, dynamic balance and walking speed with stroke.

• Tribology and Lubricants
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• 제9권2호
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• pp.56-62
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• 1993

Al-Pb-Cu and Al-Si-Pb-Cu bearing alloys were produced by forced-stirring method and water-cooled copper mold casting to investigate the effect of the precipitation hardening on the wear properties. Sliding of produced alloy pin against a steel disc were performed under various applied loads. Lowering the wear rate and material transfer phenomena were explained by the strengthening of $\theta'$ precipitates on AI matrix. The transmission electron microscope observation reveals the role of the precipitates in the alloys with Cu. The movement of dislocations was hindered by precipitates which resulted in the reduction of plastic deformation at the worn surfaces.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.212-216
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• 2004

Bearingless motors are the rotational electric machine which utilize a common magnetic structure for rotation and magnetic suspension. Since the bearing function is combined with the motor, the shaft length can be shortened resulting in higher critical speeds. Relationship between suspension force and current of bearingless motor is clearly derived by prior research. However, relationship between displacement of rotor and suspension force is not precisely defined. In this paper, we present model of bearingless motor describing the radial force variation due to the movement of the rotor. Using a distributed magnetic circuit and maxwell stress tensor, we derived a mathematical expression for the radial force. For a slotless bearingless motor, we are able to find an analytical model presented in the form of stiffness. For a slotted motor, we can compute the stiffness by semi-analytical analysis. This model is validated by a finite-element-analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.404-409
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• 2002

A newly devised linear flexure bearing (KIMM-LFB) for reciprocating machines is disclosed having improved tight gas clearance maintaining capability for better system performance. KIMM-LFB is an integrated device comprising an axially moving diaphragm with circumferentially arranged arc-shaped flexure blades secured between rim and hub spacers, which turn out to have higher radial stiffness than the one with circumferential tangent cantilever flexure blades. It is expected for KIMM-LFB to play a key role in designing long life, special purpose reciprocating machines such as spacecraft borne cryogenic refrigerators (cryocoolers) by providing frictionless, non-wearing, linear movement and radial support for the machines as well as a gas clearance seal by maintaining extremely tight clearances between piston and cylinder.