• 대한치과교정학회지
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• 제51권1호
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• pp.32-42
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• 2021

Objective: To investigate the three-dimensional forces created by clear aligners on mandibular teeth during differential activation with en-masse retraction and/or intrusion in vitro. Methods: Six sets of clear aligners were designed for differential en-masse retraction and/or intrusion procedures in a first premolar extraction model. Group A0 was a control group with no activation. Groups A1-5 underwent different degrees of retractions and/or intrusions. Each group consisted of 10 aligners. Aligner forces were measured on a multi-axis force/torque transducer measurement system in real-time. Results: In the en-masse retraction groups (A1 and A2), lingual and extrusive forces were observed on the incisors; the canines mainly received distal forces; intrusive forces were seen on the second premolars; and the molars received mesial forces. In the en-masse retraction and intrusion groups (A3, A4, and A5), incisors also received lingual and extrusive forces; canines received distal and intrusive forces; mesial and extrusive forces were seen on the second premolars; and the second molars received distal and intrusive forces. The vertical forces on the incisors did not differ significantly among groups A1, A3, and A5. However, the vertical forces on the second premolars reversed from intrusion in group A1 to extrusion in groups A3 and A5. Conclusions: With clear aligners, the "bowing effect" is seen during en-masse anterior teeth retraction and can be partially relieved by performing en-masse retraction accompanied by anterior teeth intrusion. Vertical control of incisors remained unsolved during en-masse retraction, even when intrusive activation was added to the anterior teeth.

• 한국기계가공학회지
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• 제20권11호
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• pp.36-42
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• 2021

This study was conducted to analyze the effect of the gear specification and gear quality corresponding to the macro geometry on the gear transmission error. The two pairs of gears with large and small transmission errors were selected for calculation, and two pairs of gears were manufactured with different gear quality. The test gears were manufactured by two different gear specifications with ISO 5 and 8 gear quality, respectively. The transmission error measurement system consists of an input motor, reducer, encoders, gearbox, torque meter, and powder brake. To confirm the repeatability of the test results, repeatability was confirmed by performing three repetitions under all conditions, and the average value was used to compare the transmission error results. The transmission errors of the gears were analyzed and compared with the test results. When the gear quality was high, the transmission error was generally low depending on the load, and the load at which the decreasing transmission error phenomenon was completed was also lower. Even when the design transmission error according to the gear specification was different, the difference of the minimum transmission error was not large. The transmission error at the load larger than the minimum transmission error load increased to a slope similar to the slope of the analysis result.

• 한국전문물리치료학회지
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• 제29권4호
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• pp.262-268
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• 2022

Background: Virtual reality (VR) programs based on motion capture camera are the most convenient and cost-effective approaches for remote rehabilitation. Assessment of physical function is critical for providing optimal VR rehabilitation training; however, direct muscle strength measurement using camera-based kinematic data is impracticable. Therefore, it is necessary to develop a method to indirectly estimate the muscle strength of users from the value obtained using a motion capture camera. Objects: The purpose of this study was to determine whether the pedaling speed converted using the VR engine from the captured foot position data in the VR environment can be used as an indirect way to evaluate knee muscle strength, and to investigate the validity and reliability of a camera-based VR program. Methods: Thirty healthy adults were included in this study. Each subject performed a 15-second maximum pedaling test in the VR and built-in speedometer modes. In the VR speedometer mode, a motion capture camera was used to detect the position of the ankle joints and automatically calculate the pedaling speed. An isokinetic dynamometer was used to assess the isometric and isokinetic peak torques of knee flexion and extension. Results: The pedaling speeds in VR and built-in speedometer modes revealed a significantly high positive correlation (r = 0.922). In addition, the intra-rater reliability of the pedaling speed in the VR speedometer mode was good (ICC [intraclass correlation coefficient] = 0.685). The results of the Pearson correlation analysis revealed a significant moderate positive correlation between the pedaling speed of the VR speedometer and the peak torque of knee isokinetic flexion (r = 0.639) and extension (r = 0.598). Conclusion: This study suggests the potential benefits of measuring the maximum pedaling speed using 3D depth camera in a VR environment as an indirect assessment of muscle strength. However, technological improvements must be followed to obtain more accurate estimation of muscle strength from the VR cycling test.

• Restorative Dentistry and Endodontics
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• 제34권5호
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• pp.450-459
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• 2009

본 연구의 목적은 새로 개발한 점탄성 측정기를 사용하여 수종의 광중합 복합레진의 초기 동적 점탄성 변화를측정하는 것이다. 본 연구에 사용된 점탄성 측정기는 세 부분으로 구성되었다. 첫째, 시편이 놓여지는 parallel plates; 둘째, DC 모터와 크랭크로 이루어진 회전진동전단변형 (Oscillatory shear strain)을 발생시키는 부분; 셋째, 전자기적 토크센서를 이용한 응력 측정 부분으로 구성되었다. 본 점탄성 측정기는 최대 2 Ncm의 토크를 측정할 수 있으며, 광중합기의 스위치는 컴퓨터와 연동하여 데이터 획득을 시작할 때 동시에 켜지도록 하였다. 본 연구에서는 시판 중인 6종의 광중합 복합레진 [Z-100 (Z1), Z-250 (Z2), Z-350 (Z3), DenFil (DF), Tetric Ceram (TC), Clearfil AP-X (CF)]을 사용하였다. 점탄성 측정기를 사용하여 동적 회전전단실험을 시행하였다. 직경 3 mm인 유리막대로 구성된 parallel plates 사이에 $14.2\;mm^3$의 복합레진을 적용시켰으며, 6 Hz의 진동수와 0.00579 rad의 진폭으로 변형을 가하고 발생된 응력을 측정하였다. 광중합이 시작됨과 동시에 측정이 시작되었으며, 광중합 후 10초 동안 점탄성의 변화를 관찰하였다. 각 복합레진에 대해 5 회 반복하여 측정하였고, 실험은 $25{\pm}0.5^{\circ}C$에서 진행되었다. 측정된 변형-응력 곡선으로부터 복소전단탄성계수 G*, 저장전단탄성 계수 G', 손실전단탄성 계수 G"를 구하였고 G*가 10 MPa에 이르는 시간을 구하였다. 각 재료의 복소전단탄성계수 G*와 10 MPa에 이르는 시간에 대해 일원분산분석 (One-way ANOVA)과 사후검정 (Tukey 검정)을 시행하였다 (${\alpha}$= 0.05). 결과는 다음과 같다. 1.본 연구를 위해 제작한 점탄성 측정기는 광중합 복합레진의 중합 초기 10초 동안의 동적 점탄성 변화를 신뢰성 있게 측정 할 수 있었다. 2. 모든 복합레진은 광조사 개시 후 $1{\sim}2$초의 불응기를 지난 다음 급격한 전단탄성계수의 증가를 보였다. 3. 모든 복합레진은 광중합 10 초간 손실전단탄성계수보다 저장전단탄성계수의 높은 증가를 보였다. 4. 광중합 초기 10초 후 복소전단탄성계수 값은 $150.3{\sim}563.7\;MPa$로, Z-100이 가장 높았고, 그 다음 Clearfil, Z-250, Z-350, Tetric Ceram, DenFil의 순이었다. 5. 복소전단탄성계수가 10 MPa에 이르는 시간은 Z-100이 2.55초로 가장 빨랐고, DenFil이 4.06초로 가장 느렸다.

• 구강회복응용과학지
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• 제16권3호
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• pp.197-210
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• 2000

Surface roughness is one of implant surface topography and it's found that surface roughness characterizations, such as surface energy, oxide layer thickness and its chemical composition, are closely correlated if the roughness is changed. Several studies showed the importance of analyzing surface structure so the surface structure of thread implant was analyzed to measure the implant quality exactly. In this study, surface roughness of 4 implants - MK $II^{(R)}$(Nobel Biocare), $RBM^{(R)}$(Life-Core, USA), $Osseotite^{(R)}$(3i, USA), $TPS^{(R)}$(Life-Core, USA) - were measured using $Accura^{(R)}$ and 40 implants were installed into 4 sets of ten bovine ribs based on the parameters from the measurements. From this test, the following conclusions for the initial stability were drawn by measuring and comparing RFA, Periotest Value (PTV), Removal Torgue Value (RTV). 1. $R_a$ value in surface roughness measurement was increasing by the order of $MKII^{(R)}$, $Osseotite^{(R)}$, $RBM^{(R)}$, $TPS^{(R)}$ and $R_q$ value was the same order. 2. $R_q$ value in each section was observed to increase by the order of $MKII^{(R)}$, $Osseotite^{(R)}$, $RBM^{(R)}$, $TPS^{(R)}$ in top and $MKII^{(R)}$, $RBM^{(R)}$, $Osseotite^{(R)}$, $TPS^{(R)}$ in mid-section but the value of $MKII^{(R)}$ bottom was the lowest, followed by $Osseotite^{(R)}$, $RBM^{(R)}$ and $TPS^{(R)}$. 3. RFA increased by the order of $RBM^{(R)}$(7042Hz), $MKII^{(R)}$(7047Hz), $Osseotite^{(R)}$(7076Hz), $TPS^{(R)}$(7168Hz) and there was no significance between each group. 4. PTV was increasing by the order of $MKII^{(R)}$(-1.62), $TPS^{(R)}$(-1.92), $Osseotite^{(R)}$ & $RBM^{(R)}$(-2.08) and there was no significance, either. 5. Removal torque in RTV measurement showed the increasing order of $MKII^{(R)}(5.31kgf{\cdot}cm)$, $Oeeotite^{(R)}(5.71kgf{\cdot}cm)$, $TPS^{(R)}(5.92kgf{\cdot}cm)$ and $RBM^{(R)}(7.24kgf{\cdot}cm)$ and there was no significance among groups. Above observations explains that surface roughness does not make any impact on the initial stability of implants installation.

• 한국정보전자통신기술학회논문지
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• 제11권2호
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• pp.150-155
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• 2018

국내 논 작업의 기계화율은 약 90% 이상 되었지만, 밭 작업의 기계화율은 약 60%이며, 수확작업의 기계화율은 10%내외로 밭 작업의 기계화율의 제고가 필요한 실정이다. 그러므로 본 연구는 트랙터 부착 수확작업기 개발을 위한 기초연구로써 마늘, 양파 등 땅속작물수확기의 견인작업에 따른 트랙터 차축의 부하 신호를 측정하고 주행속도에 따른 차축 소요 동력을 분석하였다. 밭 작업용 트랙터 차축의 소요 동력을 측정하기 위하여 휠 센서와 데이터 수집 시스템을 설치하였으며, 두 개의 작업속도에서 견인작업을 수행하며 소요 동력을 계측하였다. 계측한 데이터는 일원 분산분석을 수행하여 트랙터 주행 속도가 차축 소요 동력에 미치는 영향을 분석하였다. 소요 동력 분석 결과, 트랙터 부착 작업기의 작업속도가 증가할수록 트랙터의 소요 동력이 증가됨을 알 수 있었으며, 트랙터 동력전달시스템의 최적설계를 위해서는 다양한 수확작업에 따른 소요동력 분석이 필요함을 알 수 있다.

• 대한치과보철학회지
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• 제43권4호
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• pp.528-543
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• 2005

Statement of problem: Repeated delivery and removal of abutment cause some changes such as wear, scratch or defect of hexagonal structure. It may increase the value of rotational freedom(RF) between hexagonal structures. Purpose: The purpose of this study was to evaluate surface changes and rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment after repeated delivery and removal under SEM and toolmaker's microscope. Materials and methods: Implant systems used for this study were 3i and Avana. Seven pail's of implant fixture, abutment and abutment screws for each system were selected and all fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. Each one was embedded beneath the platform of fixture. Surfaces of hexagonal structure before repeated closing and opening of abutment were observed using SEM and rotational freedom was measured by using toolmaker's microscope. Each abutment was secured to the implant future by each abutment screw with recommended torque value using a digital torque controller and was repeatedly delivered and removed by 20 times respectively. After experiment, evaluation for the change of hexagonal structures and measurement of rotational freedom were performed. Result : The results were as follows; 1. Wear of contact area between implant fixture and abutment was considerable in both 3i and Avana system. Scratches and defects were frequently observed at the line-angle of hexagonal structures of implant fixture and abutment. 2. In the SEM view of the external hexagon of implant fixture, the point-angle areas at the corner edge of hexagon were severely worn out in both systems. It was more notable in the case of 3i systems than in that of Avana systems. 3. In the SEM view of the internal hexagon of abutment, Gingi-Hue abutment of 3i systems showed severe wear in micro-stop contacts that were machined into the corners to prevent rotation and cemented abutment of Avana systems showed wear in both surface area adjacent to the corner mating with external hexagon of implant fixture. 4 The mean values of rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment were 0.48$\pm$0.04$^{\circ}$ in pre-tested 3i systems and 1.18$\pm$0.25$^{\circ}$ after test, and 1.80$\pm$0.04$^{\circ}$ in pre-tested Avana systems and 2.61$\pm$0.16$^{\circ}$ after test. 5. Changes of rotational freedom after test shouted statistical)y a significant increase in both 3i and Avana systems(P<0.05, paired t-test). 6. Statistically, there was no significant difference between amount of increase in the rotational freedom of 3i systems and amount of increase in that of Avana ones(P>0.05, unpaired t-test). Conclusion: Conclusively, it was considered that repeated delivery and remove of abutment by 20 times would not have influence on screw joint stability. However, it caused statistically the significant change of rotational freedom in tested systems. Therefore, it is suggested that repeated delivery and remove of abutment should be minimal as possible as it could be and be done carefully Additionally, it is suggested that the means or treatment to prevent the wear of mating components should be devised.

• 대한화장품학회지
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• 제45권2호
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• pp.131-138
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• 2019

Carbonylated proteins (CPs)은 단백질의 염기성 아미노산 잔기들과 지질 과산화 중 생성되는 알데히드 화합물과의 화학적 반응을 통하여 만들어진다. CP는 UVA와 청색 광선 영역의 빛을 흡수하여 흥분하며, CP의 감광 반응을 통해 superoxide anion radicals ($^{\cdot}O_2{^-}$)이 생성되고 각질층(Stratum corneum, SC)에서 reactive oxygen species (ROS) 생성을 통해 새로운 protein carbonylation이 진행되는 것이 알려졌다. 또한, superoxide anion radicals이 SC에서 CP를 생성하며 색상과 수분 기능을 포함한 피부 상태에 영향을 미치는 것으로 보고되었다. 따라서, 본 연구의 목적은 피부 각질층에 존재하는 stratum corneum carbonylated protein (SCCP)의 생성량과 피부 탄력 개선의 상관정도를 알아보는 것이었다. 이를 위하여 46명의 건강한 피험자들을 대상으로 8주간 피부임상실험을 진행하였다. 8주간 진행한 피부임상시험은 피험자를 두 그룹으로 나누어, 한 그룹은 아무것도 함유하지 않은 크림을 사용하고, 다른 그룹은 탄력개선 원료가 함유된 크림을 사용하였다. 임상시험 측정 항목은 DUB scanner를 이용한 진피 치밀도 측정, Primos를 이용한 주름 측정을 진행하였으며 탄력 측정은 dermal torque meter (DTM310)와 Balistometer (BLS780)를 통해 진행하였다. SCCP측정은 피험자의 뺨에서cyanoacrylate를 이용한 skin surface biopsy (SSB)방법을 이용하여 각질을 채취한 후, 비침습적인 검출 방법을 이용해 SCCP의 양을 조사하였다. 측정은 0주, 4주, 8주 총 3회에 걸쳐서 진행하였으며 각 주차의 측정값을 각각 분석하여 종합적인 결과를 비교하였다. 그 결과, SC에 존재하는 CP의 양은 피부 주름 및 피부 탄력성과 관련된 생물학적 인자의 수치가 개선됨에 따라 감소하는 것을 확인하였다. 이를 통해 항노화 효과에 있어서 탄력 개선과 CP양의 상관관계를 확인하여, 차후 피부 항노화 시험방법에 응용할 수 있음을 확인하였다.

• 구강회복응용과학지
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• 제24권1호
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• pp.41-56
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• 2008

상용 임플란트의 표면을 개질하기 위해 물리적, 화학적 방법을 이용한 새로운 표면이 증가하고 있으며 이에 대한 골반응도 다를 것으로 예상할 수 있지만 대부분의 연구는 단순히 기계절삭형 임플란트와의 비교만을 하고 있다. 본 연구에서는 4종의 다른 개질된 표면을 가진 상용 임플란트를 가토의 경골에 식립한 후 생역학적, 조직형태학적으로 비교하였다. 연구 결과, 모든 임플란트는 6주 후 안정적인 골유착을 이루고 있었으며 4종의 표면개질의 차이에 의한 공진주파수 및 조직형태학적 골반응의 차이는 없었으며 표면개질을 비교하기 위해 피질골 하방으로 증식한 골을 비교하는 것이 유용하였다. 생역학적, 조직형태학적 골반응에 비해 미세단층촬영(micro-CT)를 이용하는 비교법은 유용성과 정확도가 낮은 것으로 나타났다.

• Journal of Biosystems Engineering
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• 제36권2호
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• pp.79-88
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• 2011

The purpose of this study was to analyze power requirement of an agricultural tractor by major field operations. First a survey was conducted to obtain annual usage ratio of agricultural tractor by field operation. Plowing, rotary tillage, and loader operations were selected as major field operations of agricultural tractor. Second, a power measurement system was constructed with strain-gauge sensors to measure torque of four driving axles and a PTO axle, speed sensors to measure rotational speed of the driving axles and an engine shaft, pressure sensors to measure pressure of hydraulic pumps, an I/O interface to acquire the sensor signals, and an embedded system to calculate power requirement. Third, the major field operations were experimented under fields with different soil conditions following planned operation paths. Power requirement was analyzed during the total operation period consisted of actual operation period (plowing, rotary tillage, and loader operations) and period before and after the actual operation (3-point hitch operating, forward and reverse driving, braking, and steering). Power requirement of tractor major components such as driving axle part, PTO part, main hydraulic part, and auxiliary hydraulic part were measured and calculated to determine usage ratio of agricultural tractor power. Results of averaged power requirement for actual field operation and total operation were 23.1 and 17.5 kW, 24.6 and 19.1 kW, and 14.9 and 8.9 kW, respectively, for plowing, rotary tillage, and loader operations. The results showed that rotary tillage required the greatest power among the operations. Averaged power requirement of driving axles, PTO axle, main hydraulic part, and auxiliary part during the actual field operation were 8.1, 7.8, 3.4, and 1.5 kW, respectively, and the total requirement power was about 70 % (20.8 kW) of the rated power. Averaged power requirement of driving axles, PTO axle, main hydraulic, and auxiliary hydraulic for the total operation period were 6.5, 6.0, 2.1, 0.9 kW, respectively, and total requirement power was about 52 % (15.5 kW) of the rated power. Driving axles required the greatest amount of power among the components.