• Progress in Superconductivity and Cryogenics
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• v.9 no.4
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• pp.46-49
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• 2007

This paper describes the sensitive cooling performance change of J-T refrigerator for cryosurgical probe due to its working fluid. The analytical results of using 50 bar nitrous oxide are compared with the case of 300 bar argon. Bio-heat equation is numerically solved to investigate the effect of the probe temperature and the cooling power of the J-T refrigerator. The refrigerator using 50 bar nitrous oxide has larger cooling power above 185 K than the one with 300 bar argon, which enables fast cooling at early stage of cryosurgery, but the biological tissue away from the probe tends to be cooled slowly after the probe reaches its lowest operating temperature. When the repeated freeze-thaw cycle is employed for main tissue destruction mechanism, using high pressure nitrous oxide is more advantageous than argon if the freezing operation is within 2-3 minutes. The probe with high pressure argon is more suitable for the case of longer freeze-thaw cycle with fewer repetitions.

• Journal of KIISE:Information Networking
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• v.32 no.5
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• pp.641-649
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• 2005

Metro networks use the existing circuit-switching technology like SONET/SDH. Such circuit-switching based networks are inefficient in tarrying Internet traffic with bursty nature. Therefore, metro networks can become a bottleneck In order to resolve this problem, the IEEE 802.17 working group has proposed the RPR (Resilient Packet Ring) technology. In addition to this, the RPR fairness mechanism has been defined to provide fairness among the stations in the RPR network. However, the current RPR fairness mechanism has the problem of inefficient use of the available bandwidth after when the congestion at a node is resolved. In this paper, we propose an improved bandwidth allocation mechanism in which, after the congestion resolution at a node, the node estimates the number of nodes transmitting data and measures the remaining bandwidth and fairly allocates the available bandwidth to active nodes. To show the performance of our proposed mechanism, we have performed simulation and showed that the proposed mechanism offers higher bandwidth utilization.

• Journal of Communications and Networks
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• v.6 no.4
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• pp.307-316
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• 2004

Wireless local area networks have known an increasing popularity during the past few years. However, as new user applications diverge from the traditional data-centric model, the introduction of efficient, QoS aware medium access methods becomes of utmost importance. EY-NPMA is a medium access protocol belonging to the contention paradigm that provides support for service differentiation and low collision rates. In this paper, we address a shortcoming of EY-NPMA as indicated by previous studies, namely the insensitivity of the protocol to different working conditions. In this work, we study and evaluate a mechanism that allows a network employing EY-NPMA to adapt its operating parameters according to the offered load. Simulation studies further document and confirm the positive characteristics of the proposed mechanism.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1225-1228
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• 2004

Principles and mechanism of energy transduction of dielectric polymer materials are well known from the various smart material related publications. However their introduction to industrial actuator applications is limited mainly due to difficulties guarantee controllability and reliability. Most of the previous publications have elaborates energy transduction physics of chunk of polymer while development of construction methods for feasible actuators made of the material is rarely proposed. In the present article, a conceptual design of multi-DOF linear polymer actuator construction that is to be controllable with moderate level of control work os introduced. In addition, numerical models that are developed with a unified energy based approach are presented not only for basic working mechanism analysis of the polymetric soft actuator but for providing analytical foundation to expend the concept toward design of multi-DOF actuator controls.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.7
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• pp.65-71
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• 2001

The development process of the polishing system for the aspherical lens mold for opto-electronics industry is described. The system uses the method that polishing tool is scanned on the surface under PC-NC control for the aspherical lens mold. The two axes interpolation of the minimum translation mechanism is applied to give uniform working condition by motion analysis. An aspherical surface is divided into multiple sections and each dwell time is calculated from the polishing rate model based on the Preston equation. As result of form error compensation experiment, initial form error is decreased about 25% while an average value of surface roughness is also reduced successfully from 180nm to 19nm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.105-108
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• 1995

So far,in deep drilling process there are several manufacturing problems such as hole deviation, hole over size, circularity,straightness and surface roughness. Whit regard to these problems, we atudied the abrasion process on carbided tip of BTA drill and got the follow test results through the abrasion characteristic test and analysis on cutting mechanism for the drill tooth and guide pad. 1) In SM55C drilling process, the most stable and reasonable drilling speed range for optmum abrasion characteristic of drill tooth was 60m.min. 2) The total drilling torque was about 60kg .deg.cm on condition drilling speed 60m/min and 0.15mm/rev. These results show that the theoretical burnising torque is well accord with the tested torque which is working on guide pad.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.648-655
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• 1993

The hydraulic coconut dehusking machine consists of three main parts ie. The frame , the power unit including the hydraulic accessories, the lifting and dehusking mechanisms. Two sets of the hydraulic coconut dehusking machine were developed . their hydraulic and electrical control circuits were connected in series to enable them operating contemporaneously. Two operators are required to operate the machine. Each of them put a coconut on the lifting mechanism in order to start the working cycle automatically. As a result, the nut are immediately pushed up and seized by the holding teeth under the supplement of the hydraulic reducing circuit. After that the dehusking mechanism started operating via the sequence circuit. At the end of the cycle, both mechanisms return to their original positions. Some remaining fibrous is taken out manually from the nut subsequently . The continuous dehusking speed was found to be 22.2 seconds per 2 coconuts.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.3
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• pp.3-7
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• 2005

This paper presents the experimental results to verify the atomization characteristics and environmental impact of cutting fluid. Even though cutting fluid improves the productivity through the cooling and lubricating effects, environmental impact due to cutting fluid usage is also increased on factory shop floor. Cutting fluid's aerosol via atomization process can generate human health risk such as lung cancer and skin diseases. Experimental results show that the generated fine aerosol of which particle size less than 10 micron appears near working zone under typical operation conditions. The aerosol concentration also exceeds NIOSH regulations. This research can be provided as a basis of environmental impact analysis for environmental consciousness.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.635-646
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• 2013

This technical paper contains the information of the Dye-Sensitized Solar Cells (DSSC) working principal where diffusion mechanism acts as electron transport to absorb the sunlight energy to generate the electrical energy. DSSC is photo electrochemical cell that implements the application of photosynthesis process. The performance of electron transport in DSSC has been reviewed in order to enhance the performance and efficiency of electron transport. The improvement of the electron transport also discussed in this paper.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.5
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• pp.400-405
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• 2013

The purpose of this study is to develop a composite platform for knowledge extractions, visualizations, and inference. Generally, the big data sets were frequently used in the healthcare and medical area. To help the knowledge managers/users working in the field, this study is focused on knowledge management (KM) based on Data Mining (DM), Knowledge Distribution Map (KDM), Decision Tree (DT), RDBMS, and SQL-inference. The proposed mechanism is composed of five key processes. Firstly, in Knowledge Parsing, it extracts logical rules from a big data set by using DM technology. Then it transforms the rules into RDB tables. Secondly, through Knowledge Maintenance, it refines and manages the knowledge to be ready for the computing of knowledge distributions. Thirdly, in Knowledge Distribution process, we can see the knowledge distributions by using the DT mechanism.Fourthly, in Knowledge Hierarchy, the platform shows the hierarchy of the knowledge. Finally, in Inference, it deduce the conclusions by using the given facts and data.This approach presents the advantages of diversity in knowledge representations and inference to improve the quality of computer-based medical diagnosis.