• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.1 s.94
• /
• pp.42-48
• /
• 1999

A control method for a robot hand grasping a object in a partially unknown environment will be proposed, where a proximate sensor detecting the distance between the fingertip and object was used. Particularly, the finger joints were driven servo-pneumatically in this study. Based on the proximate sensor signal the finger motion controller could plan the grasping process divided in three phases ; fast aproach, slow transitional contact and contact force control. That is, the fingertip approached to the object with full speed, until the output signal of the proximate sensor began to change. Within the perating range of the proximate sensor, the finger joint was moved by a state-variable feedback position controller in order to obtain a smooth contact with the object. The contact force of fingertip was then controlled using the blocked-line pressure sensitivity of the flow control servovalve for finger joint control. In this way, the grasping impact could be reduced without reducing the object approaching speed. The performance of the proposed grasping method was experimentally compared with that of a open loop-controlled one.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.28 no.6
• /
• pp.565-569
• /
• 2006

The purpose of this study was to assess the influence of the presence and impacted state of the mandibular third molars on the incidence of mandibular condyle fracture. A retrospective study was designed for patients presenting to the Department of Oral and Maxillofacial Surgery, Kyungpook National University Hospital and Tae-gu Fatima Hospital for treatment of mandibular fractures from January 2003 to January 2006. The independent variables in this study were the presence, degree of impaction of third molars, and the outcome variables were the incidence of mandibular condyle fractures. Hospital charts and panoramic radiographs were used to determine and classify these variables. The demographic data included age, sex, mechanisms of injuries and number of mandibular condyle fractures. The study sample comprised 136 mandibular condyle fractures in 105 patients. Result of this study demonstrated a statistically significant difference in ipsilateral condyle fractures and mandibular third molar absence(P=0.032) and bilateral condyle fractures without another fracture and mandibular third molar absence(P=0.028).

• The Journal of Korean Association of Computer Education
• /
• v.13 no.5
• /
• pp.81-90
• /
• 2010

Cloud computing is an Internet-based computing paradigm that provides services in a virtualized form composed of plenty of resources sharable. In Cloud computing environments, gossip protocols are engaged as a method to rapidly disseminate the state information for innumerable resources. Although gossip protocols provide a robust and scalable multicast, there is a drawback that requires redundant messages in satisfying 100% of reachability. In our study, we propose a Group-based Gossip Multicast Protocol in order to reduce the message overhead while delivering the state information efficiently. Furthermore, we verified the performance of the proposed protocol through experiments.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1583-1586
• /
• 2006

All non-dopant white organic light-emitting diodes (WOLEDs) have been realized by using solid state highly fluorescent red bis(4-(N-(1- naphthyl)phenylamino)phenyl)fumaronitrile (NPAFN) and amorphous bipolar blue light-emitting 2-(4- diphenylamino)phenyl-5-(4-triphenylsilyl)phenyl- 1,3,4-oxadiazole (TPAOXD), together with well known green fluorophore tris(8- hydroxyquinolinato)aluminum $(Alq_3)$. The fabrication of multilayer WOLEDs did not involve the hard-tocontrol doping process. Two WOLEDs, Device I and II, different in layer thickness of $Alq_3$, 30 and 15 nm, respectively, emitted strong electroluminescence (EL) as intense as $25,000\;cd/m^2$. For practical solid state lighting application, EL intensity exceeding $1,000\;cd/m^2$ was achieved at current density of $18-19\;mA/cm^2$ or driving voltage of 6.5-8 V and the devices exhibited external quantum efficiency $({\eta}_{ext})$ of $2.6{\sim}2.9%$ corresponding to power efficiency $({\eta}_P)$ of $2.1{\sim}2.3\;lm/W$ at the required brightness.

• 제어로봇시스템학회:학술대회논문집
• /
• 1999.10a
• /
• pp.57-60
• /
• 1999

An optimal control technique designed for simultaneous tracking and quality control for batch processes. The proposed technique is designed by transforming quadratic-criterion based iterative learning control(Q-ILC) into linear quadratic control problem. For real-time quality inferential control, the quality is modeled by linear combination of control input around target qualify and then the relationship between quality and control input can be transformed into time-varying linear state space model. With this state space model, the real-time quality inferential control can be incorporated to LQ control Problem. As a consequence, both the quality variable as well as other controlled variables can progressively reduce their control error as the batch number increases while rejecting real-time disturbances, and finally reach the best achievable states dictated by a quadratic criterion even in case that there is significant model error Also the computational burden is much reduced since the most computation is calculated in off-line. The Proposed control technique is applied to a semi-batch reactor model where series-parallelreactions take place.

• Applied Microscopy
• /
• v.7 no.1
• /
• pp.1-12
• /
• 1977

Ultrastructural changes of Entamoeba histolytica, a concomitant strain YS-9, which was treated in the immune serum was examined. The amoebae in the serum became immobilized state from about 30 minutes of the treatment and recovered at about 60-90 minutes. In the cells of control group, helix structures were scattered throughout the cytoplasm. The particles comprising the helix structure averaged 20 nm in diameter. At the beginning stage of the immobilization, helical aggregates(chromatoid body) which associated with vacuoles appeared abundantly in the cytoplasm, but gradually tended to aggregate along peripheral region of the cell, specially in intactly immobilized state. Each parallel array of aggregates measured about 45 nm in width. When the cells became remobilize, pseudopodia appeared again, but helical aggregates disappeared and numerous helix structures were observed in the cell periphery. Distribution of glycogen particles showed no change, and acid phosphatase activities were seen in both the immobilized and the control group. The reaction was markedly noticed in the vacuoles.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.7
• /
• pp.485-490
• /
• 2007

The LNG BOG re-liquefaction system for LNG carriers was designed based on the Claude refrigeration cycle and the thermodynamic analysis was carried out in order to find the design point of the three heat exchangers constituting the system. The thermodynamic analysis revealed that the system state could be defined by the three cold endpoint temperatures of the three-pass heat exchanger. Hence the iso-lines of the specific liquefaction work, taken as the performance indicator, were presented in terms of those three temperatures and discussed. The system was found most economical when those three temperatures approached a single temperature of $-140^{\circ}C$ and thus this system state could be taken as the design point for the heat exchangers.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.10a
• /
• pp.130-133
• /
• 2008

The formability of DP steels can be affected by not only initial texture but also deformation texture evolved during plastic deformation. To investigate the evolution of deformation texture during deep drawing, deep drawing process for DP steels was carried out experimentally. A rate sensitive polycrystal model was used to predict texture evolution during deep drawing process. In order to evaluate the strain path during deep drawing, a steady state was assumed in the flange part of deep drawn cup. A rate sensitive polycrystal model successfully predicted the texture development in DP steels during deep drawing process. It was found that the final stable orientations were strongly dependent on the initial location in the blank.

• Transactions of Materials Processing
• /
• v.17 no.7
• /
• pp.517-522
• /
• 2008

A visco-plastic self-consistent (VPSC) polycrystal model has been applied to simulate texture simulation and anisotropic properties of DP steels during deep drawing process. In order to evaluate the strain path during deep drawing, a steady state was assumed in the flange part of deep drawn cup. The final stable orientations were strongly dependent on the initial location in the blank. The evolution of anisotropy of DP steel sheets has been demonstrated through comparison of plastic strain rate vector at the different plastic strain levels.

• 한국전산유체공학회:학술대회논문집
• /
• 2000.10a
• /
• pp.72-77
• /
• 2000

This paper presents the results of the application of a computational fluid dynamics algorithm for the simulation of plasma flows of arc-heated jet. The underlying physical model is based on the axisymmetric form of the conservation equations that are coupled with an arc model including Ohm heating, electromagnetic forces. The arc model given as a source term in fluid dynamic equations is determined by a solution of electric potential field governed by an elliptic partial differential equation. The governing equation of electric field is loosely coupled with fluid dynamic equations by an electric conductivity that is a function of state variables. However, the electric fields and flow fields cannot be solved In fully coupled manner, but should be solved iteratively due to the different characteristics of governing equations. With this solution approach, several applications of arc flow analysis will be presented including Arc Thruster and Circuit Breaker.