• Journal of the Society of Naval Architects of Korea
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• v.39 no.3
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• pp.75-80
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• 2002

In these days of severe struggle for existence, the world has changed a great deal to global and digital oriented period. The enterprises try to introduce new management and production system to adapt such a change. But, if the only new technologies are applied to an enterprise without definite analysis about manufacturing, failure fellows as a logical consequence. Hence, enterprise must analyze manufacturing system definitely and needs new methodologies to mitigate risk. This study suggests that the new approach, which is systems approach for process improvement, is organized to systems analysis, systems diagnosis, and systems verification. Systems analysis analyzes manufacturing systems with object-oriented methodology-UML(Unified Modeling language) from a point of product, process, and resource view. Systems diagnosis identifies the constraints to optimize the system through scientific management or TOC(Theory of constraints). Systems verification shows the solution with virtual manufacturing technique applied to the core problem which emerged from systems diagnosis. This research shows the artifacts to improve the productivity with the above methodology applied to forming shop. UML provides the definite tool for analysis and re-usability to adapt itself to environment easily. The logical tree of TOC represents logical tool to optimize the forming shop. Discrete event simulator-QUEST suggests the tool for making a decision to verify the optimized forming shop.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.981-985
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• 2004

In this paper we designed the motor control IP Core and evaluate its quality from the viewpoint of IP reuse. The most attractive merit of this methodology, so called IP-based hardware design, is hardware reuse. Although various vendors designed hardware with the same specification and got the same functional results, all that IPs is not the same quality in the reuse aspect. As tremendous calls for SoC have been increased, associated research about IP quality standard, VSIA(Virtual Socket Interface Alliance) and STARC(Semiconductor Technology Academic Research Center), has been doing best to make the IP quality evaluation system. And they made what conforms to objective IP design standard. We suggest the methodology to evaluate our own designed motor control IP quality with this standard. To attain our goal, we designed motor control IP that could control the motor velocity and position with feedback compensation algorithm. This controller has some IP blocks : digital filter, quadrature decoder, position counter, motion compensator, and PWM generator. Each block's functionality was verified by simulator ModelSim and then its quality was evaluated. To evaluate the core, We use Vnavigator for lint test and ModelSim for coverage check. During lint process, We adapted the OpenMORE's rule based on RMM (Reuse Methodology Manual) and it could tell us our IP's quality in a manner of the scored value form. If it is high, its quality is also high, and vice versa. During coverage check ModelSim-SE is used for verifying how our test circuits cover designs. This objective methods using well-defined commercial coverage metrics could perform a quantitative analysis of simulation completeness. In this manner, We evaluated the designed motor control IP's quality from the viewpoint of reuse. This methodology will save the time and cost in designing SoC that should integrate various IPs. In addition to this, It can be the guide for comparing the equally specified IP's quality. After all, we are continuously looking forward to enhancing our motor control IP in the aspect of not only functional perfection but also IP reuse to prepare for the SoC-Compliant motor control IP design.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.2
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• pp.232-242
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• 2003

Statement of problem : Fiber-reinforced posts have lower modulus of elasticity than titanium post or cast post-core. With this similar elasticity to that of dentin, fiber-reinforced posts have been known to have a tendency to reduce the risk of root fracture. However, there were few studies on the teeth restored with fiber-reinforced posts under the condition of reduced periodontal support. Purpose : The purpose of this study was to evaluate the fracture strength and failure mode of endodontically treated teeth restored with fiber-reinforced posts and titanium posts under the condition of reduced periodontal support. Material and method : Extracted human maxillary incisor roots were divided into 3 groups (group 1 carbon fiber post, group 2 : glass fiber post, and group 3 : titanium alloy post). After coronectomy and endodontic treatment, teeth were restored with each post systems and resin core according to the manufacturer's recommendation. Then, teeth with simulated periodontal ligament were embedded in the acrylic resin blocks at the level of 4 mm below the cemento-enamel junction. Each specimen was exposed to $10^5$ load cycles with average 30 N force in $36.5^{\circ}C$ water using a computer-controlled chewing simulator. Loads were applied at $45^{\circ}$ angle to the long axis of the teeth. After cyclic loading, teeth were subjected a compressive load until failure at a crosshead speed of 0.5 mm/min. Fracture strength (N) and failure mode were examined. The fracture strength was analyzed with one-way ANOVA and the Scheffe adjustment at the 95% significance level. Results and conclusion : The results were as follows. 1. There was no statistically significant difference in the mean fracture strength among the groups (P<.05). 2. Carbon fiber post and glass fiber post group showed less root fracture tendency than control group. 3. All specimens with root fractures showed fracture lines above the level of acrylic resin block, except for only one specimen in group 3.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2B
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• pp.105-116
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• 2003

The differentiated service architecture is based on a simple model by applying a per-class service in the core node of the network. However, due to the simplified network behavior, the network structure and provisioning were more complicated. If a service provider wants the dynamic provisioning or better bandwidth guarantee, signaling protocol with QoS parameters or admission control method should be deployed in DiffServ network. However, these methods increase the complexity. Therefore, we proposed DPM2 mechanism for admission control in the DiffServ network. In this paper, we describe and survey the admission control methods that are applicable to IP networks and propose also the dynamic provisioning mechanism based on the bandwidth broker and distributed measurement based admission control and movable boundary bandwidth management to support heterogeneous QoS services in differentiated service networks. For the performance evaluation for proposed mechanism, we used ns-2 simulator.

• Journal of Astronomy and Space Sciences
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• v.24 no.4
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• pp.397-408
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• 2007

Diplexer is one of core devices needed to communicate with satellite using single ground antenna by separating uplink and downlink signal. This paper presents the design of the S-band diplexer for LEO TT&C application, especially for KOMPSAT (KOrea Multi-Purpose SATellite). To cope with requirements such as high handling power, low insertion loss, air-cavity resonator with high quality factor was considered as one of design drivers. Design was started with predicting unloaded Q and equivalent circuit from the structure of air-cavity resonator. For the convenience of adjustment, the coupling factor placed between resonators was estimated from COTSEM (Electro-Magnetic) simulator, EESOF $ADS^{TM}$, and expressed with 2-order polynomial regression. To improve the isolation between transmitting part (Tx) and receiving part (Rx), the inductive and capacitive attenuation poles were inserted between $4^{th}\;and\;6^{th}$ resonator respectively. The fabricated diplexer consists of two bandpass filters and each filter has eight resonants. From the measurement, it was shown that major requirements such as 0.5dB of insertion loss, 20dB of return loss and 100dB of isolation were fully satisfied within passband.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.65-71
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• 2016

Currently developing the OBC of the next-generation LEO satellite by Korea Aerospace Research Institute adopts the LEON2-FT/AT697F processor to achieve high performance. And various communication devices such as SpaceWire, MIL-STD-1553B, DMAUART and CAN Master are integrated to the separated standard communication FPGAs within the OBC, where they can be controlled by the processor and flight software (FSW) through PCI interface. The Actel 1553BRM IP core is used for the 1553B in the next-generation LEO OBC and the B1553BRM wrapper from Aeroflex Gaisler is used for connecting it to the AMBA bus in FPGA. This paper presents the design and development of PCI-based 1553B communication software, and describes the handling mechanism of 1553B operation in FSW task level. Also it shows the test results on real-hardware and simulator.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2008-2015
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• 2010

Ns-2 is a proven simulator which is widely utilized to evaluate the performance of wired and wireless network. Ns-2.33 version introduced the extended version including the modules which the core functions of existing 802.11 PHY and MAC layer are implemented. However, if the error rate, one of most important parameters to evaluate a performance of wireless network, is applied to the extended version, the simulation is ceased with several fatal errors. Furthermore, a packet error is detected and discarded on MAC layer in the traditional protocol architecture, but there is the problem which can't identify information about a packet with error by processing packet error on PHY layer in this version. In this paper, we modify the extended version to resolve the above mentioned problems. And also we perform ns-2 simulation using the modified version on the IEEE 802.11p based vehicular ad-hoc networks, and then analyze effects of error rate.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.96-102
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• 1998

The use of computers as part of nuclear safety systems elicits additional requirements-software verification and validation (v/v), hardware qualification-not specifically addressed in general industry fields. The computer used in nuclear power plants is a system that includes computer hardware, software, firmware, and interfaces. To develop the computer systems graded with nuclear safety class, the developing environments have to be required in advance and the developed software have to be verified and validated in accordance with nuclear code and standards. With this requirements, the test facility for Inadequate Core Cooling Monitoring System (ICCMS) as one of safety systems in the nuclear power plants was developed. The test facility consists of three(3) parts such as Input/Output (I/O) simulator, Plant Data Acqusition System (PDAS) cabinets and supervisory computer. The performance of the system was validated by manual test procedure.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.157-166
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• 2009

There is a growing interest in ubiquitous-related research and applications. Among them, GPS-based LBS have been developed and used actively. Recently, with the increase of large size buildings and disastrous events, indoor spaces are getting attention and related research activities are being carried out. Core technologies regarding indoor applications may include 3D indoor data modeling and localization sensor techniques that can integrate with indoor data. However, these technologies have not been standardized and established enough to be applied to indoor implementation. Thus, in this paper, we propose a method to build a relatively simple 3D indoor data modeling technique that can be applied to indoor location based applications. The proposed model takes the form of 2D-based multi-layered structure and has capability for 2D and 3D visualization. We tested three prototype applications using the proposed model; CA(cellular automata)-based 3D evacuation simulation, network-based routing, and indoor moving objects tracking using a stereo camera.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1354-1362
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• 2015

Heterogeneous network technology is expected to be a core technology for 5G mobile communications. 5G mobile network would be composed of many base stations even have mobility, then the operator should connect base stations through the wireless backhaul technology. This paper presents Ultra Wide Area Wireless Backhaul Network System with massive array antenna. We conducted link budget analysis for Ultra Wide Area Wireless Backhaul Network and performance analysis of massive array antenna system through the transmission simulator based on beamforming technology. In wide area ($10km^2$) wireless backhaul system composed of massive antenna, we achieved 5 bps/Hz average spectral efficiency with 1 W transmission power per beam.