• Journal of the Microelectronics and Packaging Society
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• v.27 no.1
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• pp.25-29
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• 2020

This study demonstrates direct-patternable amorphous TiO_x resistive switching (RS) device and the fabrication method using photochemical metal-organic deposition (PMOD). For making photosensitive stock solutions, Ti(IV) 2-ethylhexanoate was used as starting precursor. Photochemical reaction by UV exposure was observed and analyzed by Fourier transform infrared spectroscopy and the reaction was completed within 10 minutes. Uniformly formed 20 nm thick amorphous TiO_x film was confirmed by atomic force microscopy. Amorphous TiO_x RS device, formed as 6 × 6 ㎛ square on 4 ㎛ width electrode, showed forming-less RS behavior in ±4 V and on/off ratio ≈ 20 at 0.1 V. This result shows PMOD process could be applied for low temperature processed ReRAM device and/or low cost, flexible memory device.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7B
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• pp.585-597
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• 2004

In this paper, we propose the functional models of optical burst switching (OBS) routers to apply GMPLS (Generalized Multiprotocol Label Switching) to optical networks based on OBS. In addition, we introduce a connection admission control (CAC) algorithms which are operated in this models and can accommodate the required QoS. Firstly, the characteristics of current GMPLS and OBS for the optical Internet are basically considered. With this consideration, the models are proposed to accept OBS features which include the recognition of data boundary with control information and the statistical multiplexing in terms of bursts. Secondly, we use an offset time decision (OTD) algorithm on behalf of controlling the connection admission with taking QoS parameters such as burst loss rate(BLR) and service-differentiation ratio(SDR) into consideration. The proposed CAC algorithms use the offered load of LSP (Label Switched Path), wavelength information, and QoS parameters as inputs of OTD algorithm. A call setup request will be accepted when the offset time decided by OTD algorithm is reasonable for guaranteeing its requested QoS. Simulation is used for performance evaluation. Results show the proposed schemes can guarantee the required QoS and those are better than the previous one in terms of channel utilization.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.6
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• pp.734-749
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• 1998

A numerical study t predict the characteristics on transient operation of the heat pipe cooling system with multiple heaters for electronic system has been performed. The heat pipe cooling system of 45 cm length and 16 mm diameter was composed of evaporator section with four heaters which simulate electronic components, insulated transport section, and condenser section with a conductor which was cooled under the constant heat flux boundary condition. Two test cases were investigated in present study; Case 1 indicated that the 1st and 2nd heaters among four heaters were heated off, while the 3rd and the 4th heaters were heated on. Case 2 was the inverse situation switched from heating locations of Case 1. Case 3 indicated that the 1st and 4th heaters among four heaters were heated off, while the 2nd and 3rd heaters were heated on. The results showed that the transient time to reach the steady state is shorter for Case 1 than for Case 2. Especially, the maximum temperature among the heaters which simulate electronic components during switching operation is relatively small compared to the maximum allowable operating temperature in electronic system. It is concluded that the heat pipe cooling system in present study operate with the good thermal reliability even for sudden switching situation of the heaters.

• Atmosphere
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• v.17 no.3
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• pp.241-253
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• 2007

This paper investigates summer precipitation change in East Asia according to switching surface boundary condition over South Korea and Shantung. Simulations are carried out by ECHO-G/S for 20 years (1980-1999). Surface condition over both areas in ECHO-G/S is represented by ocean (OCN experiment). In OCN experiment, the summer precipitation is considerably underestimated around the Korean peninsula (the dry region) and overestimated over the eastern Tibetan Plateau (the wet region). It may be related that the lack of the heat sources from the unrealistically prescribed land-sea mask weakens northward expansion of rainband and the development of convective precipitation. Moreover the simulated rainband retreats before June in connection with the early genesis of summer monsoon circulation. The systematic bias of the summer precipitation over the dry and wet regions are reduced comparing with the OCN experiment when the land-sea masks over South Korea and Shantung are realistically considered as land (LND experiment). These improvements can be explained by the thermodynamical dissimilarity between land and ocean. Enhanced warming by switching the areas from sea to land has led to develop the thermal low over Yellow Sea with the cyclonic circulation. Thus, this cyclonic circulation supports moistures from the south to the dry region and blocks to the wet region. The heat transport from the land surface to atmosphere plays a key role in the developing convective precipitation in local scale and maintaining the precipitation and the rainband. Therefore, this results indicate that the design of the realistic land-sea distribution is required for the accurate simulation of the regional precipitation.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.602-610
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• 2001

In the MPLS(Multiprotocol Label Switching) forwarding paradigm, once a packet is assigned to a FEC(Forwarding Equivalence Class), no further header analysis is done by subsequent routers; all forwarding is driven by the labels. This has a number of advantages over conventional network layer forwarding. The MPLS LER(Label Edge Router) is located at the boundary of MPLS domain and plays a role in connecting with the existing Internet as an ingress or an egress router. That is, the MPLS LER as an ingress router assigns a label to a packet which enters the MPLS network from the Internet by analyzing its header and forwards to a corresponding next router in MPLS domain. As an egress router, the MPLS LER turns the packets out of the MPLS network by performing the reverse operation. In this paper, we analyze the traffic performance of an MPLS LER system and estimate the IP(Internet Protocol) packet processing capacity of the system using queueing model and simulation. It is found that the maximum IP packet processing capacity of the system is estimated by 420,000 through 460,000 packets/sec.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.4
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• pp.292-297
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• 2003

We fabricated a single crystal silicon thin film transistor for active matrix organic light emitting displays(AMOLEDs) using silicon on insulator wafer (SOI wafer). Poly crystal silicon thin film transistor(poly-Si TFT) Is actively researched and developed nowsdays for a pixel switching devices of AMOLEDs. However, poly-Si TFT has some disadvantages such as high off-state leakage currents and low field-effect mobility due to a trap of grain boundary in active channel. While single crystal silicon TFT has many advantages such as high field effect mobility, low off-state leakage currents, low power consumption because of the low threshold voltage and simultaneous integration of driving ICs on a substrate. In our experiment, we compared the property of poly-Si TFT with that of SOI TFT. Poly-Si TFT exhibited a field effect mobility of 34 $\textrm{cm}^2$/Vs, an off-state leakage current of about l${\times}$10$\^$-9/ A at the gate voltage of 10 V, a subthreshold slope of 0.5 V/dec and on/off ratio of 10$\^$-4/, a threshold voltage of 7.8 V. Otherwise, single crystal silicon TFT on SOI wafer exhibited a field effect mobility of 750 $\textrm{cm}^2$/Vs, an off-state leakage current of about 1${\times}$10$\^$-10/ A at the gate voltage of 10 V, a subthreshold slope of 0.59 V/dec and on/off ratio of 10$\^$7/, a threshold voltage of 6.75 V. So, we observed that the properties of single crystal silicon TFT using SOI wafer are better than those of Poly Si TFT. For the pixel driver in AMOLEDs, the best suitable pixel driver is single crystal silicon TFT using SOI wafer.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.2
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• pp.164-170
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• 2002

Sliding mode control, as a typical method of variable structure control, has the robust characteristics for the uncertainty and the disturbance of the nonlinear system. Because, however, sliding mode control input includes a sign function that Is discontinuous on the predefined switching surface, its applications are primarily limited by the need of alleviation or reduction of chattering. In this paper, we propose a chattering alleviation strategy based on a special nonlinear function and a fuzzy system. By using the proposed control scheme, we can reduce the steady state error. Its tracking performance is as fast as that of conventional method using the fixed boundary layer. Especially, in the proposed method, we can adjust the trade-off between the steady state error and the degree of chattering by regulating the proper range of the output variable of the fuzzy system. To verify the validity of the proposed algorithm, the analysis of the control method using the fixed boundary layer and the computer simulations are shown to compare with them.

• Journal of the Korean Institute of Educational Facilities
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• v.19 no.2
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• pp.41-50
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• 2012

This study aims to analyze chlidcare philosophy and the architectural characteristics of communal childcare cooperative nurseries(parent cooperative childcare facilities), and also to examine their mutual relationship. The communal childcare cooperative is an ideal childcare method to break away from employee-supported childcare system and cooperatively solve childcare problems in the family community system. The child-rearing philosophy of the communal childcare can bring spontaneous and creative development amidst 'daily life' and 'play' by switching from knowledge and skill-oriented education and puts an emphasis on physical environments in child's growth. The features of architecture related the childcare philosophy derived from this study are as follows: the way of participation and self-help, the extension of spatial scope and focuses on outside space, architecture of house-like residence rather than educational facility, spatial 'overlapping' focusing on transitional space and multi-purpose space rather than spatial partitions, the pursuit of creativity through play is realized in the incompletion and unspecification of space evolving over time.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.154-162
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• 2002

The effect of nonlinear friction in the low velocity is dominant in precise controlled mechanisms and it is difficult to model. This paper is concerned with the compensation for friction using the variable structure system approach as nonmodel based method. The problem of chattering in the sliding mode controller is suppressed by the implementation of the boundary layer concept. And the estimation for friction using sliding mode observer makes the upper bound of matched uncertainty reduced. Accordingly, the effect of chattering can be more suppressed. And the sliding surface is constructed by adding an integral component to the switching function that is made by using error dynamics. This sliding surface guarantees the good tracking performance. Experimental results for a XY table system show that the proposed method has a good performance especially in the low velocity.

• Journal of Power Electronics
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• v.12 no.3
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• pp.377-386
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• 2012

An interleaved bridgeless buck-boost AC/DC converter is presented in this paper to achieve the characteristics of low conduction loss, a high power factor and low harmonic and ripple currents. There are only two power semiconductors in the line current path instead of the three power semiconductors in a conventional boost AC/DC converter. A buck-boost converter operated in the boundary conduction mode (BCM) is adopted to control the active switches to achieve the following characteristics: no diode reverse recovery problem, zero current switching (ZCS) turn-off of the rectifier diodes, ZCS turn-on of the power switches, and a low DC bus voltage to reduce the voltage stress of the MOSFETs in the second DC/DC converter. Interleaved pulse-width modulation (PWM) is used to control the switches such that the input and output ripple currents are reduced such that the output capacitance can be reduced. The voltage doubler topology is adopted to double the output voltage in order to extend the useable energy of the capacitor when the line voltage is off. The circuit configuration, principle operation, system analysis, and a design example are discussed and presented in detail. Finally, experiments on a 500W prototype are provided to demonstrate the performance of the proposed converter.