• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.992-995
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• 2003

A haptic device operated by the user's hand can receive information on position and orientation of the hand and display force and moment generated in the virtual environment to the hand. For realistic haptic display, the detailed information on collision between objects is necessary. In the past, the point-based graphic environment has been used in which the end effector of a haptic device was represented as a point and the interaction of this point with the virtual environment was investigated. In this paper, the shape-based graphic environment is proposed in which the interaction of the shape with the environment is considered to analyze collision or contact more accurately. To this end. the so-called Gilbert-Johnson-Keerthi (GJK) algorithm is adopted to compute collision points and collision instants between two shapes in the 3-D space. The 5- DOF haptic hand controller is used with the GJK algorithm to demonstrate a peg-in-hole operation in the virtual environment in conjunction with a haptic device. It is shown from various experiments that the shape-based representation with the GJK algorithm can provide more realistic haptic display for peg-in-hole operations.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 Proceedings of 5th International Joint Symposium on Microeletronics and Packaging
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• pp.74-79
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• 2000

In an attempt to estimate the wetting properties of wettable metal layers by wetting balance method, an analysis of wetting curves of the coating layer was performed. Based on the analysis, wetting properties of UBM-coated Si-plate were estimated by the new wettability indices. The wetting curves of the one and both sides-coated UBM layers have the similar shape and show the similar tendency to the temperature. So the wetting property estimation of one side coating is possible with wetting balance method. For UBM of Si-chip, Cr/Cu/Au UBM is better than Ti/Ni/Au in the point of wetting time. At general reflow temperature, the wettability of high melting point solders(Sn-Sb, Sn-Ag) is better than that of few melting point ones(Sn-Bi, Sn-In).The contact angle of the one side coated plate to the solder can be calculated from the farce balance equation by measuring the static state force and the tilt angle.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권2호
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• pp.172-178
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• 2000

When we establish treatment planning of facial asymmetry, we must predict each asymmetrical element that will be changed upon coronal, axial, sagittal plane. At the visual point, prediction of the change of coronal plane is most important. It is important difference between Rt. and Lt. mandibular angle belonging to posterior coronal plane, as well as anterior coronal plane, such as upper and lower incisor, or midline of chin point. Several methods for control bulk of mandibular angle are additional angle shaving after osteotomy, grinding contact area between proximal and distal segment for decrease the volume, or bone graft for increase the volume. But, at the point of bimaxillary surgery, transverse position of posterior maxilla is an important factor for control it. So, we would report transverse movement of posterior maxilla for decrease asymmetry on the posterior coronal plane of face, that is, asymmetry of mandibular angular portion.

• 상하수도학회지
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• 제27권3호
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• pp.331-337
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• 2013

Post-chlorination for disinfection in portable water process is final process. The design factors of post-chlorination are inflow pipe line from tank of filtrated water to cleanwell, injection point of chlorine, appropriate shape of baffle in cleanwell for disinfection efficient improvement. Until now, we did not have the design standard for post-chlorination. we evaluated most suitable design method of post-chlorination process in portable water process by using computational fluid dynamics in this research. We found the result that the pipe to connect the cleanwell should be one. If pipe line split into two or more, uniform distribution of the flow is difficult. Second, optimal injection point of chlorine is the middle of pipe line to connect the cleanwell. Therefore, it is not economical to install chlorine contact basin in cleanwell. Third, the shape of baffle should be designed in order to water flows in one direction. And we found that it is better to design the low number of flow turning.

• 한국생산제조학회지
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• 제23권5호
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• pp.498-504
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• 2014

Displacements and strains are very important for material evaluation as critical factors to a machine's life cycle and safety. Typically, the strain gauge has been employed to measure displacement and strain. However, this contact-type measurement method has disadvantages that are not quantified under the test conditions of a specific object shape, surface roughness, and temperature. In this paper, the measurement of deflection and flexural strain due to the three-point bending test is presented, employing Digital Image Correlation (DIC) methods. In order to ensure measurement reliability, DIC and universal test machine methods were compared by measuring the deflections and flexural strains developed by such bending tests.

• 한국분무공학회지
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• 제27권2호
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• pp.77-83
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• 2022

In this study, the thickness of the liquid sheet formed by a low speed impinging jet onto a flat plate was measured by the direct contact method. The spatial distribution characteristics of the sheet thickness in the radial and circumferential directions, and the effects of jet velocity and liquid viscosity were analyzed. The measurement results were compared with the theoretical predictions. The wavy surface was observed in the case of low viscosity water, but not in the high viscosity aqueous glycerol solutions. The sheet thickness increased as the circumferential angle increased or the distance from the impinging point increased, but the thickness decreased as the circumferential angle increased around the impinging point. As the jet speed increased, the sheet thickness decreased, and the sheet thickness increased as the liquid viscosity increased. Comparison with the theoretical predictions showed that the measurement results agreed well in the case of low viscosity water or high viscosity liquids around the impinging point. The distribution characteristics of the sheet thickness can provide useful means for prediction of spray characteristics in splash plate injectors.

• 한국정밀공학회지
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• 제12권4호
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• pp.67-77
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• 1995

In modern industry the requirement of automation of manufacturing process increases so that unmanned system has been popular as an ultimate goal of modern manufacturing process. In unmanned manufacturing process the tool fracture is a very serious problem because it results in the damage of workpieces and can stop the operation of whole manufa- turing system. In this study, image processing technique is used to detect the fracture of insert tip of face milling using multi-point-tool. In order to acquire the image information of fracture shape of rotation insert tip. We set up the optical system using a light beam chopper. In this system we can reduce the image degradation generated from stopped image of rotating insert tip using image restoration technique. We calculated the mean square error to diagnose the condition of tool fracture, and determind the criteria of tool fracture using experimental and staticstical method. From the results of this study we've developed non- contact detection technique of tool fracture using image processing method and proposed the fracture direction of automation and unmanned system considering the optimal time of tool change milling.

• 대한치과보철학회지
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• 제36권1호
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• pp.81-103
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• 1998

The purpose of this study was to compare and evaluate the differences in masticatory performance, muscle activity, and patterns of occlusal contact between persons with natural dentition and removable partial denture wearers. Twenty healthy adult subjects with more than 28 teeth and thirteen removable partial denture wearers that classified Kennedy classification I was selected. The degree of pulverized rice and peanut was measured and analyzed by means of sieving method to compare the masticatory performance. For the muscle activity, EMG was recorded in selected muscles(Temporalis and masseter muscle) during mastication and resting state. The occlusal record in maximal intercuspation was taken with a silicone occlusal bite registration material for analysis of the patterns of occlusal contact. The obtained results were as follows: 1. When chewed peanuts, masticatory performance ratio at 10-sieve size was 81.31% in natural dentition group. In removable partial denture wearer, 27.01% without RPD and 69.09% with RPD. When chewed rice, 42.04%, 11.87%, and 21.58%, respectively. The differences of masticatory performance ratio between groups were statistically significant at the 0.05 level. 2. The mean EMG value in resting state was $1.06{\mu}V$ on temporal muscle, $0.98{\mu}V$ on masseter muscle in natural dentition group. In removable partial denture wearers, $1.13{\mu}V$ on temporal muscle, $1.05{\mu}V$ on masseter muscle without RPD and $1.11{\mu}V$ on temporal muscle, $1.04{\mu}V$ on masseter muscle with RPD. 3. The mean EMG value during mastication was $45.64{\mu}V$ in natural dentition group, and in removable partial denture wearers, $22.06{\mu}V$ without RPD and $31.01{\mu}V$ with RPD when chewed peanuts. When chewed rice, $45.24{\mu}V,\;25.53{\mu}V\;and\;32.14{\mu}V$, respectively. The differences of mean masticatory EMG value between groups were statistically significant at the 0.05 level. 4. The number of posterior occlusal contact point was 20.15 in natural dentition group and 11.92 in removable partial denture wearers. The area of perforated surface was $16.50mm^2$ in natural dentition group and $6.06mm^2$ in removable partial denture wearers. The area of contact surface was $78.93mm^2,\;51.52mm^2$, respectively. 5. The area of contact surface was effective to masticatory performance ratio in natural dentition group and removable partial denture wearers (p<0.05). From these results, it is concluded that in partially edentulous patient, masticatory efficiency can be improved by removable partial denture wearing, and for efficient mastication, tight occlusal contact surface shoud be maintained by maximum support that is provided from mucosa.

• 조명전기설비학회논문지
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• 제19권3호
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• pp.44-50
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• 2005

본 논문에서는 산화아연(이하 ZnO) 피뢰기 열화진행의 한 요인으로 예측되는 전극과 ZnO소자 사이에서 발생하는 방전광 현상에 관한 연구를 수행하였다. 이를 위해 $8/20[{\mu}s]$, 최대 10[kA]의 뇌임펄스전류를 발생시키는 뇌임펄스전류 발생장치를 설계${\cdot} $제작하였다. 실험결과, 상${\cdot}$하부의 전극 부근에서 발생하는 방전광의 형상은 인가되는 뇌임펄스의 극성에 따라 다르게 나타났으며 상대적으로 (-)극의 전극부근에서 방전광이 더 강하고 활발하게 발생하는 것으로 관찰되었다. 또한 전극의 면적에 따른 방전광의 세기는 전극의 면적이 증가할수록 감소하는 것으로 관측되었다. 동시에 전극과 소자의 접촉상태도 방전광의 발생과 매우 밀접한 관계가 있는 것으로 확인되었다. 따라서 배전급 ZnO피뢰기의 기존 전극구조는 보완이 필요하며 ZnO피뢰기 제품의 성능향상 및 지속적인 성능유지를 위해서는 환형구조 대신 내부면적이 있는 원판구조로 교체하는 것이 바람직하다고 판단된다.

• International Journal of Control, Automation, and Systems
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• 제6권5호
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• pp.677-688
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• 2008

In this paper, the general problem of impedance control for a robotic manipulator with a moving flexible base is addressed. Impedance control imposes a relation between force and displacement at the contact point with the environment. The concept of impedance control of flexible base mobile manipulator is rather new and is being considered for first time using singular perturbation and new sliding mode control methods by authors. Initially slow and fast dynamics of robot are decoupled using singular perturbation method. Slow dynamics represents the dynamics of the manipulator with rigid base. Fast dynamics is the equivalent effect of the flexibility in the base. Then, using sliding mode control method, an impedance control law is derived for the slow dynamics. The asymptotic stability of the overall system is guaranteed using a combined control law comprising the impedance control law and a feedback control law for the fast dynamics. As first time, base flexibility was analyzed accurately in this paper for flexible base moving manipulator (FBMM). General dynamic decoupling, whole system stability guarantee and new composed robust control method were proposed. This proposed Sliding Mode Impedance Control Method (SMIC) was simulated for two FBMM models. First model is a simple FBMM composed of a 2 DOFs planar manipulator and a single DOF moving base with flexibility in between. Second FBMM model is a complete advanced 10 DOF FBMM composed of a 4 DOF manipulator and a 6 DOF moving base with flexibility. This controller provides desired position/force control accurately with satisfactory damped vibrations especially at the point of contact. This is the first time that SMIC was addressed for FBMM.