• Korean Journal of Materials Research
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• v.34 no.6
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• pp.283-290
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• 2024

The aggressive scaling of dynamic random-access memory capacitors has increased the need to maintain high capacitance despite the limited physical thickness of electrodes and dielectrics. This makes it essential to use high-k dielectric materials. TiO₂ has a large dielectric constant, ranging from 30~75 in the anatase phase to 90~170 in rutile phase. However, it has significant leakage current due to low energy barriers for electron conduction, which is a critical drawback. Suppressing the leakage current while scaling to achieve an equivalent oxide thickness (EOT) below 0.5 nm is necessary to control the influence of interlayers on capacitor performance. For this, Pt and Ru, with their high work function, can be used instead of a conventional TiN substrate to increase the Schottky barrier height. Additionally, forming rutile-TiO₂ on RuO₂ with excellent lattice compatibility by epitaxial growth can minimize leakage current. Furthermore, plasma-enhanced atomic layer deposition (PEALD) can be used to deposit a uniform thin film with high density and low defects at low temperatures, to reduce the impact of interfacial reactions on electrical properties at high temperatures. In this study, TiO₂ was deposited using PEALD, using substrates of Pt and Ru treated with rapid thermal annealing at 500 and 600 ℃, to compare structural, chemical, and electrical characteristics with reference to a TiN substrate. As a result, leakage current was suppressed to around 10^-6 A/cm² at 1 V, and an EOT at the 0.5 nm level was achieved.

• Publications of The Korean Astronomical Society
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• v.21 no.2
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• pp.67-74
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• 2006

We have developed a control electronics system for an infrared detector array of KASINICS (KASI Near Infrared Camera System), which is a new ground-based instrument of the Korea Astronomy and Space science Institute (KASI). Equipped with a $512{\times}512$ InSb array (ALADDIN III Quadrant, manufactured by Raytheon) sensitive from 1 to $5{\mu}m$, KASINICS will be used at J, H, Ks, and L-bands. The controller consists of DSP(Digital Signal Processor), Bias, Clock, and Video boards which are installed on a single VME-bus backplane. TMS320C6713DSP, FPGA(Field Programmable Gate Array), and 384-MB SDRAM(Synchronous Dynamic Random Access Memory) are included in the DSP board. DSP board manages entire electronics system, generates digital clock patterns and communicates with a PC using USB 2.0 interface. The clock patterns are downloaded from a PC and stored on the FPGA. UART is used for the communication with peripherals. Video board has 4 channel ADC which converts video signal into 16-bit digital numbers. Two video boards are installed on the controller for ALADDIN array. The Bias board provides 16 dc bias voltages and the Clock board has 15 clock channels. We have also coded a DSP firmware and a test version of control software in C-language. The controller is flexible enough to operate a wide range of IR array and CCD. Operational tests of the controller have been successfully finished using a test ROIC (Read-Out Integrated Circuit).

• Journal of KIISE:Information Networking
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• v.35 no.5
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• pp.409-414
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• 2008

In mobile ad hoc networks, most of on demand routing protocols such as DSR and AODV do not deal with traffic load during the route discovery procedure. To solve the congestion and achieve load balancing, many protocols have been proposed. However, the existing load balancing schemes has only considered avoiding the congested route in the route discovery procedure or finding an alternative route path during a communication session. To mitigate this problem, we have proposed a new scheme which considers the packet bursting mechanism in congested nodes. The proposed packet bursting scheme, which is originally introduced in IEEE 802.11e QoS specification, is to transmit multiple packets right after channel acquisition. Thus, congested nodes can forward buffered packets promptly and minimize bottleneck situation. Each node begins to transmit packets in normal mode whenever its congested status is dissolved. We also propose two threshold values to define exact overloaded status adaptively; one is interface queue length and the other is buffer occupancy time. Through an experimental simulation study, we have compared and contrasted our protocol with normal on demand routing protocols and showed that the proposed scheme is more efficient and effective especially when network traffic is heavily loaded.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.3
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• pp.62-73
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• 2008

In this paper, domestic standard revision plan of dynamic frequency method which is used both in unmanned automatic toll collection system and manned collection system of the express highway is presented. For such ETCS, the infrared rays (870 nm) of active frequency method and the frequency integrated method (5.8 GHz) are adopted and extended to be operated to the all around the Toll Gate. This standardization plan is based on inter connection reference model between OSI (Open System Interconnection) in process of ITS short range radio communication standardization of 5.8 GHz bandwidth to support traffic information and control system service, and the derived revision plan by starting from physical layer which support interoperability for multiple access between RSE (Road Side Equipment) and OBE (On Board Equipment), in which is categorized into physical layer, data link layer, and application layer. In case of radiation power, existing standard is divided by class1 (within 10 m) and Class2 (within 100 m) according to transmission lengthwhile it is operated with just single standard 'Class1' because of notification of Ministry of Information and Communication in 2004. In the case of the limitation value of incident power in communication area, considering operation plan of ETCS that is on actuality operation the measurements are reflected to the standard. In other wort this paper proposed the improvement standard of incident power, pseudo response in the communication area and radiated power in order to secure stability and compatibility among operator systems about the needed part on ETCS operation.

• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.293-304
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• 2011

The world of ubiquitous computing is one in which we will be surrounded by an ever-richer set of networked devices and services. Especially, mobile phone now becomes one of the key issues in ubiquitous computing environments. Mobile phones have been infecting our normal lives more thoroughly, and are the fastest technology in human history that has been adapted to people. In Korea, the number of mobile phones registered to the telecom company, is more than the population of the country. Last year, the numbers of mobile phone sold are many times more than the number of personal computer sold. The new advanced technology of mobile phone is now becoming the most concern on every field of technologies. The mix of wireless communication technology (wifi) and mobile phone (smart phone) has made a new world of ubiquitous computing and people can always access to the network anywhere, in high speed, and easily. In such a world, people cannot expect to have available to us specific applications that allow them to accomplish every conceivable combination of information that they might wish. They are willing to have information they want at easy way, and fast way, compared to the world we had before, where we had to have a desktop, cable connection, limited application, and limited speed to achieve what they want. Instead, now people can believe that many of their interactions will be through highly generic tools that allow end-user discovery, configuration, interconnection, and control of the devices around them. Serendipity is an application of the architecture that will help people to solve a concern of achieving their information. The word 'serendipity', introduced to scientific fields in eighteenth century, is the meaning of making new discoveries by accidents and sagacity. By combining to the field of ubiquitous computing and smart phone, it will change the way of achieving the information. Serendipity may enable professional practitioners to function more effectively in the unpredictable, dynamic environment that informs the reality of information seeking. This paper designs the Serendipity Service based on NFC (Near Field Communication) technology. When users of NFC smart phone get information and services by touching the NFC tags, serendipity service will be core services which will give an unexpected but valuable finding. This paper proposes the architecture, scenario and the interface of serendipity service using tag touch data, serendipity cases, serendipity rule base and user profile.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9A
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• pp.702-709
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• 2003

In this paper, we propose an efficient and QoS-aware MAC scheduling algorithm for Bluetooth, which considers both throughput and delay performance of each Master-Slave pair in scheduling decisions, and thus, attempts to maximize overall performance. The proposed algorithm, MTDPP (Modified Throughput-Delay Priority Policy), makes up for the drawbacks of T-D PP (Throughput-Delay Priority Policy) proposed in [6] and improves the performance. Since Bluetooth employs a master-driven TDD based scheduling algorithm, which is basically operated with the Round Robin policy, many slots may be wasted by POLL or NULL packets when there is no data waiting for transmission in queues. To overcome this link wastage problem, several algorithms have been proposed. Among them, queue state-based priority policy and low power mode-based algorithm can perform with high throughput and reasonable fairness. However, their performances may depend on traffic characteristics, i.e., static or dynamic, and they require additional computational and signaling overheads. In order to tackle such problems, we propose a new scheduling algorithm. Performance of our proposed algorithm is evaluated with respect to throughput and delay. Simulation results show that overall performances can be improved by selecting suitable parameters of our algorithm.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.4
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• pp.69-74
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• 2010

A new package substrate for dynamic random access memory(DRAM) devices has been developed using selective aluminum anodization. Unlike the conventional substrate structure commonly made by laminating epoxy-based core and copper clad, this substrate consists of bottom aluminum, middle anodic aluminum oxide and top copper. Anodization process on the aluminum substrate provides thick aluminum oxide used as a dielectric layer in the package substrate. Placing copper traces on the anodic aluminum oxide layer, the resulting two-layer metal structure is completed in the package substrate. Selective anodization process makes it possible to construct a fully filled via structure. Also, putting vias directly in the bonding pads and the ball pads in the substrate design, via in pad structure is applied in this work. These arrangement of via in pad and two-layer metal structure make routing easier and thus provide more design flexibility. In a substrate design, all signal lines are routed based on the transmission line scheme of finite-width coplanar waveguide or microstrip with a characteristic impedance of about $50{\Omega}$ for better signal transmission. The property and performance of anodic alumina based package substrate such as layer structure, design method, fabrication process and measurement characteristics are investigated in detail.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.4
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• pp.93-105
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• 2002

In this paper forest fire status information management system was developed under web environment using web GIS(geographic information system) technology. Though this system, general users can easily retrieval domestic forest fire status information and obtain that in visual way such as maps, graphs, and texts if they have only certain web browsers. Moreover, officials, who have system access authority, can easily control and manage all domestic forest fire status information through input interface, retrieval interface, and out interface of the system. This system can be considered as the first domestic system to manage forest fire status data and service them in visual through user friendly interfaces on web. In order to implement this system, IIS 5.0 of Microsoft is used as web server and Oracle 8i and ASP(active server page) are used for database construction and dynamic web page operation, respectively. Also, ArcGIS IMS(internet map server) of ESRI is used to serve maps by using Java and HTML as system development languages. Not only the domestic tendency of forest fire but also the forest fire status information of certain area and time such as the frequency and the loss can be presented through distribution maps, graphs and tables. Therefore, this system is supposed to play as a important role when the policy relate to domestic forest fire is established. In addition, the self consciousness of people against forest fire can be inspired and the foundation of scientific and systemic forest fire services can be obtained through this system in the future.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.363-363
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• 2014

Ruthenium (Ru) has attractive material properties due to its promising characteristics such as a low resistivity ($7.1{\mu}{\Omega}{\cdot}cm$ in the bulk), a high work function of 4.7 eV, and feasibility for the dry etch process. These properties make Ru films appropriate for various applications in the state-of-art semiconductor device technologies. Thus, it has been widely investigated as an electrode for capacitor in the dynamic random access memory (DRAM), a metal gate for metal-oxide semiconductor field effect transistor (MOSFET), and a seed layer for Cu metallization. Due to the continuous shrinkage of microelectronic devices, better deposition processes for Ru thin films are critically required with excellent step coverages in high aspect ratio (AR) structures. In these respects, atomic layer deposition (ALD) is a viable solution for preparing Ru thin films because it enables atomic-scale control of the film thickness with excellent conformality. A recent investigation reported that the nucleation of ALD-Ru film was enhanced considerably by using a zero-valent metallorganic precursor, compared to the utilization of precursors with higher metal valences. In this study, we will present our research results on the synthesis and characterization of novel ruthenium complexes. The ruthenium compounds were easy synthesized by the reaction of ruthenium halide with appropriate organic ligands in protic solvent, and characterized by NMR, elemental analysis and thermogravimetric analysis. The molecular structures of the complexes were studied by single crystal diffraction. ALD of Ru film was demonstrated using the new Ru metallorganic precursor and O2 as the Ru source and reactant, respectively, at the deposition temperatures of $300-350^{\circ}C$. Self-limited reaction behavior was observed as increasing Ru precursor and O2 pulse time, suggesting that newly developed Ru precursor is applicable for ALD process. Detailed discussions on the chemical and structural properties of Ru thin films as well as its growth behavior using new Ru precursor will be also presented.

• The Journal of the Korea Contents Association
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• v.9 no.3
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• pp.361-371
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• 2009

LAMS(learning activity management system)[1] is one of the useful tools for designing and managing effectively the learning activities such as web search, chat, forum, grouping, and board. Even if LAMS has been upgraded to support the methods for making e-Learning contents conveniently, it does not have a method to communicate with external educational contents (EEC) made by external tools like Flash, Java, Visual C++, and so on. LAMS, which has been operated on Web environment, should manage all EECs like video and dynamic educational contents as educational contents in LAMS database. However, the current LAMS does not support the functionalities which can provide information of EECs to LAMS database and can also access any information about EECs from the database yet. In this paper, we propose the communication mechanism between the LAMS and EECs for solving the problem. In special, the mechanism makes many statistical data by using the information, and provides them for reflecting in education, and can control various learning management that was impossible under the original LAMS. Based on the proposed mechanism, teachers using LAMS can make more various educational contents and can manage them in the system.