• 구강회복응용과학지
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• 제33권2호
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• pp.114-118
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• 2017

목적: 이 연구의 목적은 타이타늄 구성요소를 가진 지르코니아 지대주가 내부연결 임플란트에 사용되었을 때 나사 풀림에 대해 알아보는 것이다. 열순환 후 타이타늄 소켓을 가진 지르코니아 지대주와 타이타늄 지대주의 나사 풀림과 제거력을 비교 분석하였다. 연구 재료 및 방법: 내측연결 임플란트와 내측연결 타이타늄 지대주, 타이타늄 소켓을 가진 외측연결 지르코니아 지대주를 준비하였다. 내부연결형 임플란트에 5개의 타이타늄 지대주를(대조군), 타이타늄 소켓을 가진 5개의 지르코니아 지대주(실험군)를 각각 연결하고 30 Ncm의 토크로 조인 후 열순환 처리 전후의 지대주 나사 제거력을 측정하였다. 각 시편들은 열순환 장치의 수조에서 $5^{\circ}C$와 $55^{\circ}C$의 물에 60초씩 교대로 2,000회의 열순환을 시행하였다. 각 시편의 나사 풀림을 조사하고 열순환 전후에 나사 제거력을 통계학적으로 분석하였다. 결과: 두 그룹 모두에서 열순환 후 지대주 나사 풀림을 보이지 않았다. 열순환 전후의 나사 제거력 차이는 대조군에서 $-1.34{\pm}2.53Ncm$, 실험군에서 $-1.26{\pm}2.06Ncm$ 로 나타났다. 독립표본 T 통계분석 결과 두 군간에 유의한 차이를 보이지 않았다(P > 0.05). 결론: 이 실험의 결과 내에서 내부연결 임플란트를 위한 지르코니아 지대주 내 타이타늄 소켓이 열순환 후 지대주 나사풀림에 타이타늄 지대주와 비교하여 유의한 영향을 나타내지 않았다.

• 한국전산구조공학회논문집
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• 제31권2호
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• pp.79-85
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• 2018

기존의 한방향 펌프는 순환과 배수를 위해 각각의 모터를 사용하지만, 양방향 펌프는 하나의 모터로 모터의 회전 방향에 따라 배수와 순환이 모두 가능하므로 원가절감이 가능하다. 하지만 양방향 펌프는 배수와 순환 시 펌프 케이싱 내부에서 역류와 흡입이 발생하여 유입된 물이 각각 배출구와 순환구로 원활하게 유출되지 못하는 단점이 있다. 본 연구에서는 주효과 분석을 통해 배출과 순환 시 유출되는 유량과 토크에 주요한 영향을 미치는 인자를 설계변수로 선택하여 실험계획법, 근사모델, 그리고 최적설계를 통해 펌프 케이싱 형상을 최적화함으로써 역류와 흡입은 개선하고 펌프의 토크 대비 배출구와 순환구의 유량을 증가시키는 효과를 거두었다.

• 대한치과보철학회지
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• 제57권4호
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• pp.328-334
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• 2019

목적: 0.9% NaCl solution 에 2주간 담근 레이저 처리 임플란트 표면의 친수성 증가현상을 확인하고 그것이 각 임플란트의 초기 치유기간 10일 후에 임플란트의 회전 제거력에 미치는 영향을 확인하고자 한다. 재료 및 방법: 지름 3 mm, 길이 8 mm 되는 10개의 선반 가공된 티타늄 임플란트를 대조군은 레이저 처리하고, 다른 실험군 10개는 레이저 처리 후 2주간 0.9% 생리적 식염수에 담근 후 뉴질랜드산 흰 토끼의 경골에 식립한후, 10일 후에 각각 회전 제거력을 측정하였다. 각 시편의 젖음각과 표면조성 및 형태를 분석하였다. 결과: 10일 후에 실험군의 회전 제거력이 대조군보다 의미있는 증가세를 보였다 (P = .002, < .05). 주사전자 현미경 성분분석과, 형태는 별다른 차이를 보이지 않았다. 결론: 식염수에 담그는 과정은 의미있는 회전 제거력의 증진을 초기기간(10일 후)에 나타낼 수 있다.

• 한국운동역학회지
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• 제22권3호
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• pp.285-293
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• 2012

The aim of this study is to identify the appropriate movement for maintaining postural balance during Front Kick and Turning Side Kick motions. To do so, ten Taekwondo athletes: five skilled players(S, body mass: $65.0{\pm}5.8kg$, height: $172.3{\pm}3.7cm$, age: $20.0{\pm}1.2yrs$, career: $9.0{\pm}1.9yrs$) and five less-skilled players(LS, body mass: $67.1{\pm}5.5kg$, height: $173.2{\pm}5.1cm$, age: $19.4{\pm}1.7yrs$, career: $9.6{\pm}1.7yrs$) participated in this study. A three-dimensional motion analysis was performed on the participants using eight infrared cameras and two force plate(sampling frequency of 200 Hz and 2000 Hz for S and LS players, respectively). The participants' motions were divided into: a front-kick phase(P1) and a turning-side-kick phase(P2). For P2(p<.05), the range and root mean square(RMS) of the ground reaction torque and the M-L mean velocity of COP were greater for LS than for S; similarly, for P2(p<.05), the M-L range, A-P range, and velocity of the COP were greater for LS than for S. Further, the M-L range and maximum velocity of the COP was greater for failure than for success(p<.05). The femoral biceps muscle for bending the knee joint was significantly stronger in S than in LS(p<.05). It is expected that these results will be useful in developing a training program for improving the balance and stability of Taekwondo poomsae athletes and improve their front-kick and turning-side-kick motions.

• 대한치과보철학회지
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• 제45권6호
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• pp.769-779
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• 2007

Statement of problem. When TiN coating is applied to the abutment screw, occurrence of greater preload and prevention of the screw loosening could be expected due to decrease of frictional resistance. However, the proper thickness of TiN coating on abutment screw has not been yet reported. Purpose. The purpose of this study is to find out the appropriate TiN coating thickness by evaluating the detorque force and the surface change of titanium abutment screw with various TiN coating thickness. Material and methods. 1. Material Thirty five non-coated abutment screws were prepared for TiN coating. TiN coatings were prepared by Arc ion plating method. Depending on the coating deposition time(CDT), experimental groups were divided into 6 groups(CDT 30min, 60min, 90min, 120min, 150min, 180min) and those of 1 group was not coated as a control group. Each group was made up of 5 abutment screws. 2. Methods FE-SEM(Field Emission Scanning Electron Microscoper) and EDX(Energy Dispersive X-ray Spectroscopy) were used to observe the surface of the abutment screw. Electric scales was used to measure the weight of the abutment screw after the repeated closing and opening of 10 trials. Detorque force was measured with digital torque gauge, at each trial. Results. 1. As the coating deposition time increased, the surface became more consistent and smooth. 2. As for the abutment screws that were TiN coated for more than 60 minutes, no surface change was found after the repeated closing and opening. 3. The TiN coated abutment screws showed less weight change than the non-coated abutment screws. 4. The TiN coated abutment screws showed higher mean detorque force than the noncoated abutment screws. 5. The abutment screw coated for 60 minutes showed the highest mean detorque force. Conclusion. The coating layer of proper thickness is demanded to obtain consistent and smooth coating surface, resistance to wear, and increased detorque force of the abutment screw. In conclusion, the coating deposition time of 60 minutes indicated improved mechanical property, when TiN coating was conducted on titanium abutment screw.

• 한국정밀공학회지
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• 제29권12호
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• pp.1368-1375
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• 2012

In this paper, a method for prediction of spread is proposed to design proper roll profile taking into account spread in shape rolling of angle bar. The effect of the process variables on spread, such as draught ratio, bending angle and aspect ratio, is analyzed by FE-analysis and response surface method (RSM). Roll profiles for equal angle bar are designed with the spread predicted by the regression equation. Effectiveness of the designed roll profiles are verified by FE-analysis in which the flange length, strain distribution, mean strain and roll torque are compared with those by Geuze. Finally, the proposed method is applied to the design of roll profile for unequal angle bar. As a result, the final product can be obtained within the allowable tolerance of ${\pm}0.5mm$ in length. Therefore, it is found that the prediction of spread can improve the efficiency of design roll profile in shape rolling of angle bar.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.620-622
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• 2004

Mobility of an indoor wheeled robot is affected by adhesion force that is related to various floor conditions. When the adhesion force between driving wheels and the floor decreases suddenly, the robot has a slip state. In order to overcome this slip problem, optimal slip velocity must be decided for stable movement of wheeled robot. First of all, this paper shows that conventional PI control can not be applied to a wheeled robot of the light weigh. Secondly, reposed fuzzy logic applied by the Takagi-Sugeno model for the configuration of fuzzy sets. For the design of Takaki-Sugeno model and fuzzy rule, proposed algorithm uses FCM(Fuzzy c-mean clustering method) algorithm. In additionally, this algorithm controls recovered driving torque for the restrain the re-slip. The proposed fuzzy logic controller(FLC) is pretty useful with prevention of the slip phenomena through that compare fuzzy with PI control for the controller performance in the re-adhesion control strategy. These procedures are implemented using a Pioneer 2-DXE wheeled robot parameter.

• 대한물리치료과학회지
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• 제25권1호
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• pp.52-61
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• 2018

Background: The purpose of this study was to investigate the effect of open and close kinetic chain exercise on the muscle activity of pectoralis major and triceps. Method: Twenty healthy male college students were assessed three times over two weeks. The participants were randomly assigned to OKCE(Open Kinetic Chain Exercise) and CKCE(Close Kinetic Chain Exercise). On the first day, the 7th day and the last day, The MP(mean power) and PT(peak torque) of the PM(pectoralis major) and TR(triceps) during the exercise were measured with an electromyography device and the study was compared. Result: In the present study, it was found that Statistical analysis of the measured values at the end of experimental period revealed statistically significant differences in the MP and PT values of TR and PM. Conclusion: These findings suggest that CKCE and OKCE may be an effective physical therapy intervention for strengthening muscular activity in patients with low activity in the upper limb, including normal subjects, although it is not suitable for effective exercise by selecting either CKCE or OKCE.

• 산업기술연구
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• 제26권B호
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• pp.21-28
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• 2006

A diesel truck of 1 ton is re-powered by a gasoline engine and the fuelling system of gasoline engine modified to gasoline/CNG bi fuel system. The engine characteristics such as fuel economy and power are evaluated by driving rest, sloping test and dynamometer. The driving test prove the driving cost is saved by 55% and the maximum speed is raised by 13%, which is mainly due to the higher calorific value of CNG. The sloping test is done on the road of which slope is 15%. The truck shows the mean velocity of 88km/h, which means that a re-powered truck is working fine. The BHP are measured by dynamometer. The power and torque produced by a re-powered truck are reduced by 13% and 14% respectively from the power of gasoline engine. The BHP reduction is one of main problems which one has to solve in near future.

• Advances in Automotive Engineering
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• 제1권1호
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• pp.21-39
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• 2018

Clutch energy is the thermal energy dissipated on the clutch disc, and it reaches its highest level during drive-off as a result of the difference between the angular speeds of the flywheel and clutch disc, and the torque transmitted. The thermal energy dissipated effects the clutch life. This study presents a new drive-off and thermal model to calculate the clutch energy for a rear wheel driven heavy-duty vehicle and to analyze the effects of clutch energy on temperatures of clutch pressure plate, flywheel and clutch housing. Three different driver profiles are used, based on the release of the clutch pedal in modulation zone: i) the pedal travels with the same speed all the way, ii) the travel speed of the pedal increases, iii) the travel speed of the pedal decreases. Vehicle test is performed to check the accuracy of the model. When compared to a simpler model that is widely used in the literature to calculate the clutch energy, the model used in this study calculates the clutch energy and angular speed behaviors of flywheel and transmission input shaft in better agreement with experimental results. Clutch wear and total clutch life are also estimated using the mean specific friction power.