• 대한치과교정학회지
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• 제53권4호
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• pp.254-263
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• 2023

Objective: The evidence on the accuracy of bite registration using intraoral scanners is sparse. This study aimed to develop a new method for evaluating bite registration accuracy using intraoral scanners. Methods: Two different types of models were used; 10 stone models and 10 with acrylic resin teeth. A triangular frame with cylindrical posts at each apex (one anterior and two posteriors) was digitally designed and manufactured using three-dimensional (3D) printing. Such a structure was fitted in the lingual space of each maxillary and mandibular model so that, in occlusion, the posts would contact their opposing counterparts, enforcing a small interocclusal gap between the two arches. This ensured no tooth interference and full contact between opposing posts. Bite registration accuracy was evaluated by measuring the distance between opposing posts, with small values indicating high-accuracy. Three intraoral scanners were used: Medit i500, Primescan, and Trios 4. Viewbox software was used to measure the distance between opposing posts and compute roll and pitch. Results: The average maximum error in interocclusal registration exceeded 50 ㎛. Roll and pitch orientation errors ranged above 0.1 degrees, implying an additional interocclusal error of around 40 ㎛ or more. The models with acrylic teeth exhibited higher errors. Conclusions: A method that avoids the need for reference hardware and the imprecision of locating reference points on tooth surfaces, and offers simplicity in the assessment of bite registration with an intraoral scanner, was developed. These results suggest that intraoral scanners may exhibit clinically significant errors in reproducing the interocclusal relationships.

• 해양환경안전학회지
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• 제26권1호
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• pp.1-7
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• 2020

차량 및 화물 고박불량과 횡경사에 따른 화물의 이동으로 인한 여객선 침몰사고 이후 화물 고박의 중요성이 제기되었고 카페리선박의 구조 및 설비 등에 관한 기준이 개정되어 풍속 7 m/sec, 파고 1.5미터를 초과하는 해상상태에서는 평수구역을 운항하는 카페리여객선에 적재된 모든 차량은 고박을 실시해야 한다. 본 연구에서는 평수구역을 운항하는 여객선의 해상상태에 따른 선체운동을 계측하고 NSM(New Strip Method) 계산 결과와 비교 하였으며, 대상선박은 풍속 6 ~ 8 m/s, 파고 0.5 ~ 1.0미터의 해상상태에서 최대 1.41° 및 1.37°의 종 동요와 횡 동요를 하였고, 풍속 10 ~ 12 m/s, 파고 1.0 ~ 1.5미터의 해상상태에는 최대 1.49° 및 2.43°의 종 동요와 횡 동요를 하였다. 선체운동 결과를 반영하여 외력과 지지력을 비교해 본 결과 고박하지 않은 상태의 지지력이 더 강한 것으로 평가되어 해당 기상조건에서는 고박을 하지 않아도 차량이 미끄러지거나 전도되지 않는 것으로 평가되었다. 향후 다양한 선박의 선체운동 측정, 외력 및 지지력 비교를 통해 보다 합리적인 차량고박 기준 개정이 요구된다.

• 대한의용생체공학회:의공학회지
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• 제37권3호
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• pp.105-111
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• 2016

Introduction: Surgical robot is the alternative instrument that substitutes the difficult and precise surgical operation; should have intuitiveness operationally to transfer natural motions. There are limitations of hand motion derived from contacting mechanical handle in the surgical robot master interface such as mechanical singularity, isotropy, coupling problems. In this paper, we will confirm and verify the feasibility of intuitive Non-restraint master interface which tracking the hand motion using infra-red camera and only 3 reflective markers without the hardware handle for the surgical robot master interface. Materials & methods: We configured S/W and H/W system; arranged 6 infra-red cameras and attached 3 reflective markers on hands for measuring 3 dimensional coordinate then we find the 7 motions of grasp, yaw, pitch, roll, px, py, pz. And we connected Virtual-Master to the slave surgical robot(Laparobot) and observed the feasibility. To verify the result of motion, we compare the result of Non-restraint master and that of clinometer (and protractor) through measuring 0~180 degree, 10degree interval, 1000 samples and recorded standard deviation stands for error rate of the value. Results: We confirmed that the average angle values of Non-restraint master interface is accurately corresponds to the result of clinometer (and protractor) and have low error rates during motion. Investigation & Conclusion: In this paper, we confirmed the feasibility and accuracy of 3D Non-restraint master interface that can offer the intuitive motion of non-contact hardware handle. As a result, we can expect the high intuitiveness, dexterousness of surgical robot.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권2호
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• pp.61-66
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• 2003

In order to prevent roll-over and a rapid boil-off of LNG in tanks, the phase equilibria of carbon dioxide in liquefied natural gas components as binary mixtures at cryogenic temperatures have been experimentally measured using Fourier transform infrared spectroscopy in conjunction with a specially designed variable pressure/temperature cryostat cell (pathlength 2 mm; pressures up to 30 bar). Solid carbon dioxide has been found to be comparatively soluble in liquid nitrogen (3.25$\times$${10}^{-6}$ mole fraction), liquid methane (1.04$\times$${10}^{-4}$ mole fraction), liquid ethane (3.1$\times$${10}^{-2}$ mole fraction) and liquid propane (6.11$\times$${10}^{-2}$ mole fraction) at their normal boiling temperatures. The solubilities of carbon dioxide in various cryogens, which increased with increasing temperature, are much lower than those obtained by others using gas chromatography. The differences are attributed to infrared spectroscopy selectively measuring dissolved solute in situ whereas gas chromatography measures microscopic particulate solid in addition to dissolved solute.

• 한국기계가공학회지
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• 제15권1호
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• pp.34-41
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• 2016

Bar camber is a phenomenon in which a material with a deformation gradient across its width is bent in the right or left direction in the roll gap. This paper proposes a dynamic setup approach for a side guide for reducing bar camber. A bar tracking scheme using a rotary encoder was adopted to fix an operation point for the side guide. The guiding pressure was utilized for measuring the actual width of the bar with camber. Based on the accurate position and width of the bar, the side guide was dynamically set and operated at the actual roughing train in a hot strip rolling mill. The amount of camber was reduced notably when the dynamic setup scheme was installed in the side guide. 78% of the bars tested had a camber in the range of ${\pm}20mm$, which was an improvement of 27% in terms of production yield.

• 한국군사과학기술학회지
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• 제21권4호
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• pp.429-436
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• 2018

The RCS value of maritime ship is indicator of ship's stealth performance and it should be particularly measured for navy ship to ensure survivability on the battlefield. In the design phase of the navy ship, a RCS prediction should be performed to reduce RCS value and achieve ROC(Required Operational Capability) of the ship through configuration control. In operational phase, the RCS value of the ship should be measured for verifying the designed value and obtaining tactical data to take action against enemy missile. During the measurement of RCS for the ship, ship motion can be affected by roll and pitch in accordance with sea state, which should be analyzed into threat elevation from view point of enemy missile. In this paper, we propose a method to measure and analyze RCS of ship in 3-dimensions using a ship motion measuring instrument and a fixed RCS measurement system. In order to verify the proposed method, we conducted a marine experiment using a test ship in sea environment and compared the measurement data with RCS prediction value which is carried by prediction SW($CornerStone^{TM}$) using CAD model of the ship.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.49-52
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• 2006

should be in English, A make out an economical, reliable and easy to adoptable instrument in turbine discharge measurement was restricted from lots of it's foundational condition. Not with standing the brilliant progress in new technology of these day, useful instrument for flow measurement in turbine is still ongoing. Nowaday, the increasing importance of renewable energy makes it more important that the measuring turbine efficiency as a decision making index of old turbines' replacement. In Turbine performance diagnosis, Kwater(Korea Water Corporation) got an enough ability and decent reputation for who has invested lots of time and effort for buildup and development. In Korea as a public corporation who should take a crucial roll in Turbine business, Kwater has introduced some developed new technology for other domestic concerned one. With this writing, I'd like to introduce ASFM system as a newly developed instrument that can cope with lots restriction in discharge measurement in turbine. Kwater adopted the system in 2005, and performed 2 times of trial test. The test result was good enough to use the system as a reference test method.

• 한국의류학회지
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• 제2권2호
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• pp.245-252
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• 1978

In order to obtain some information for solvent dyeing, polyethylene terephthalate (PET) was treated with water, tetrachloroethylene yarn (TCE), and water/TCE emulsion for three hours at the temperatures from $40^{\circ}$ to $140^{\circ}C$. The change of fine structure of substratum by measuring the shrinkage, the degree of crystallinity, the stress relacxation modulus and Young's modulus. The P.E.T. film was also treated in water (at $140^{\circ}C$) for 4 hours to stabilize the substratum. By means of film roll cyliderical method, the Disperse Blue 27 was diffused. Then, calculated the diffusion coefficient and examined the application of WLF equation. However, the temperature dependence of the shrinkage could be explain with WLF equation, the diffusion coefficient couldn't be applied the WLF equation when the substratum was stabilized. From the result, the effects on shrinkage were in the order of water

• 한국정밀공학회지
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• 제30권12호
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• pp.1321-1325
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• 2013

In this paper, we proposed an air bearing stage with active magnetic preloads in vertical directions compensating motion errors and attenuating vibrations to improve dynamic characteristics. This preloaded design gives simpler configuration of the stage, and active control of preload can be used for compensating motion errors by feedforward method. To improve dynamic characteristics, vibration of the table is monitored by an accelerometer, and controlled by a DSP based digital controller with integrator and band pass filters for suppressing roll and pitch vibration modes. The modes were evaluated by measuring frequency response functions, and compared with compensated responses. This showed effective results for suppressing poorly damped regenerative vibration of air bearings.

• Journal of Mechanical Science and Technology
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• 제18권3호
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• pp.379-387
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• 2004

A novel flatness sensing system which is called the Flatness Sensing Inter-stand Looper(FlatSIL) system is suggested and a self-tuning PI control system using the FlatSIL is designed for improving the flatness of hot strip in finishing mill processes. The FlatSIL system measures the tension along the direction of the strip width by using segmented rolls, and the tension profile is approximated through the tension of each segmented roll. The flatness control system is operated by using the tension profile. The proposed flatness control system as far as the tension profile-measuring device works for the full strip length during the strip rolling in finishing mills. The generalized minimum variance self-tuning (GMV S-T) PI control method is applied to control the flatness of hot strip which has a design parameter as weighting factor for updating the PI gains. Optimizing the design parameter in the GMV S-T PI controller, the Robbins-Monro algorithm is used. It is shown by the computer simulation and experiment that the proposed GMV S-T PI flatness control system has better performance than the fixed PI flatness control system.