• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2011.07a
• /
• pp.424-427
• /
• 2011

방송 환경과 인터넷 환경이 융합되고 스마트 TV의 등장에 따라, 사용자는 복잡한 미디어 서비스 환경에 노출되었다. 이로 인해 사용자가 접하는 미디어 콘텐츠의 종류와 데이터의 양은 기하급수 적으로 증가 하고 있다. 웹과 인터넷을 기반으로 하는 정보기술은 모바일 전자 기술의 발달에 따라 데스크탑 이라는 공간적인 한계를 벗어나 유기적인 유비쿼터스 환경으로 변화하고 있으며, 정보 및 콘텐츠의 개념은 웹문서와 텍스트를 넘어서 UCC, 음악, 영화 등의 모바일 멀티미디어 콘텐츠들로까지 빠르게 확장되고 있다. 또한, N-스크린과 IPTV 서비스의 등장은 사용자로 하여금 장소와 시간에 관계없이 미디어를 취득할 수 있는 이득을 제공할 수 있으나 사용자가 선택은 더욱 힘들어 졌다. 방송 통신 융합 단말에서 콘텐츠에 대한 정보를 제공 받기 위해서는 TV-Anytime 인터페이스, MPEG Query Format 인터페이스, OPEN API 등이 사용 가능하다. TV-Anytime 인터페이스는 대용량 저장 장치를 갖는 방송 단말기에서 메타데이터를 제공 및 검색하기 위한 인터페이스를 제공하며, MPEG Query Format 인터페이스는 MPEG-7을 기반으로 하는 메타데이터를 검색하기 위한 인터페이스를 제공한다. 또한, OPEN API는 업체들을 중심으로 공개적으로 제공 되어지는 API로 개방과 참여를 목적으로 한다. 이에 본 논문에서는 사용자의 콘텐츠 사용 정보를 바탕으로 선호 정보를 생성하고, 이를 바탕으로 콘텐츠에 대해서 강화된 정보를 생성하기 위한 서비스를 설계 및 개발한다.

• Journal of Korea Multimedia Society
• /
• v.8 no.2
• /
• pp.225-232
• /
• 2005

A PDA has limitation of storage space and inconvenience of Pen-based equipment to input. To solve these problems, this paper implemented that previous Speech Recognition provides using XML(extensile Markup Language) Web Service and PDA Client is possible to use speech command by request Speech Recognition Web Service. This system consists of Mobile Client and Speech Recognition Web Service Provider. The Mobile Client transmits user information and speech data to the Speech Recognition Web Service Provider using DIME(Direct Internet Message Encapsulation). The Speech Recognition Web Service Provider returns recognition results and user name only to an authorized Mobile Client. So We are able to use speech service without installing Speech Recognition or Speech DB in PDA.

• Journal of Energy Engineering
• /
• v.6 no.1
• /
• pp.87-95
• /
• 1997

A chemical heat pump based on the reversible reactions between metal chlorides and ammonia gas is attractive alternative to compression system and liquid absorption systems in cooling and refrigerating fields. The advantages of chemical heat pump are no regulatory constants due to CFC refrigerants, utilization of gas, industrial waste heat, electricity, fuel oil etc. as heat sources and wide applications to energy storage system, large-scale energy managements for industrial process. The scale-up of chemical heat pump from laboratory prototype to pilot plants necessitates the interpretation of system performance and evaluation of dynamic behavior in the chemical reactor. This study contains the prediction of performance of chemical refrigerator according to operating condition, the dynamic simulations through reactor modelling, which is used for the calculation of reactive medium temperature and the conversion variation with reactor cooling temperature, and the effect survey of block parameters on the power of refrigerator.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.3
• /
• pp.384-392
• /
• 2015

This paper presents an economic assessment of large-scale Li-ion battery energy storage systems applied to Korean power system. There are many applications of the battery energy storage systems (BESSs) and they can provide various benefits to power systems. We consider BESSs to the energy time-shift application to Korean power system and evaluate the benefits from the application of BESS in the social perspective. The mixed integer programming (MIP) algorithm is used to resolve the optimal operation schedule of the BESS. The social benefits can include the savings of the fuel cost from generating units, deferral effects of the generation capacity, delay of transmission and distribution infra construction, and incremental CO2 emission cost impacts, etc. The economic evaluation of the BESS is separately applied into Korean power systems of the Main-land and Jeju island to reflect the differences of the load and generation patterns.

• The KIPS Transactions:PartD
• /
• v.12D no.4 s.100
• /
• pp.543-552
• /
• 2005

As random access memory chip gets cheaper, it becomes affordable to realize main memory-based database systems. The disk-based spatial indexing techniques, however, cannot direct apply to main memory databases, because the main purpose of disk-based techniques is to reduce the number of disk accesses. In main memory-based indexing techniques, the node access time is much faster than that in disk-based indexing techniques, because all index nodes reside in a main memory. Unlike disk-based index techniques, main memory-based spatial indexing techniques must reduce key comparing time as well as node access time. In this paper, we propose an efficient spatial index structure for main memory-based databases, called Tmr-tree. Tmr-tree integrates the characteristics of R-tree and T-tree. Therefore, Nodes of Tmr-tree consist of several entries for data objects, main memory pointers to left and right child, and three additional fields. First is a MBR of a self node, which tightly encloses all data MBRs (Minimum Bounding Rectangles) in a current node, and second and third are MBRs of left and right sub-tree, respectively. Because Tmr-tree needs not to visit all leaf nodes, in terms of search time, proposed Tmr-tree outperforms R-tree in our experiments. As node size is increased, search time is drastically decreased followed by a gradual increase. However, in terms of insertion time, the performance of Tmr-tree was slightly lower than R-tree.

• Journal of KIISE:Computing Practices and Letters
• /
• v.14 no.4
• /
• pp.378-388
• /
• 2008

Flash memory has been attracting attention as the next mass storage media for mobile computing systems such as notebook computers and UMPC(Ultra Mobile PC)s due to its low power consumption, high shock and vibration resistance, and small size. A storage system with flash memory excels in random read, sequential read, and sequential write. However, it comes short in random write because of flash memory's physical inability to overwrite data, unless first erased. To overcome this shortcoming, we propose an SSD(Solid State Disk) architecture with two novel features. First, we utilize non-volatile FRAM(Ferroelectric RAM) in conjunction with NAND flash memory, and produce a synergy of FRAM's fast access speed and ability to overwrite, and NAND flash memory's low and affordable price. Second, the architecture categorizes host write requests into small random writes and large sequential writes, and processes them with two different buffer management, optimized for each type of write request. This scheme has been implemented into an SSD prototype and evaluated with a standard PC environment benchmark. The result reveals that our architecture outperforms conventional HDD and other commercial SSDs by more than three times in the throughput for random access workloads.

• Smart Media Journal
• /
• v.4 no.2
• /
• pp.62-67
• /
• 2015

During several decades, hard disk drive(HDD) has been used in most computer systems as secondary storage and, however, the performance enhancement of HDD is limited by its mechanical properties. On the other hand, although the flash memory based solid state drive (SSD) has more advantages over HDD such as high performance and low noise, SSD is still too expensive for common usage and expected to take several years to replace HDD completely. Therefore, SSD caching mechanism using the SSD as a cache of high capacity HDD has been highlighted lately. The representatives of SSD caching mechanisms are typically bcache, dm-cache, Flashcache, and EnhanceIO. Each of them has its own internal mechanism and implementation, and this makes them to show their own pros. and cons. In this paper, we analyze the characteristics of each SSD caching mechanisms and compare the performance of them under various workloads. We expect that our contribution will be useful to enhance the performance of SSD caching mechanisms.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.202.1-202.1
• /
• 2014

최근 대용량 에너지 저장장치로 사용하고자 하는 리튬-공기전지는 리튬 음극과 액체 전해질 사이의 화학적 불안정성이 문제가 되고 있다. 또한 리튬이온전지는 액체전해질의 사용으로 인해 폭발 등의 안정성 문제가 대두되고 있는 실정이다. 때문에 리튬-공기전지에서 리튬 음극을 액체 전해질로부터 보호할 수 있으며, 리튬이온전지의 액체전해질과 대체하였을 때 전극과도 안정한 고체전해질의 연구가 필요하다. 고체전해질은 구조적으로 crystalline, glassy, 폴리머로 나눌 수 있는데, 이 중 crystalline 구조의 고체전해질은 glassy 및 폴리머 고체전해질에 비해 상온에서 비교적 이온전도도가 높다고 알려져 있다 [1]. 그러나 이온전도도가 높은 황화물 및 질화물 고체전해질은 수분에 민감한 반면 [2,3], 산화물 계열의 물질은 안정할 것으로 예상된다. 본 연구에서는 이온전도도가 높은 산화물인 lithium lanthanum titanate ($Li_{0.5}La_{0.5}TiO_3$, LLTO)를 고체전해질로 선정하여 다양한 환경에서 화학적 안정성에 관해 연구하였다. LLTO와 각종 용액과의 화학적 안정성을 살펴보기 위해 고체전해질을 DI water, 1 M $LiPF_6$ Ethylene Carbonate (EC)-Dimethyl Carbonate (DMC) (50:50 vol.%), 0.57 M LiOH (pH=13), 0.1 M HCl (pH=1)에 immersion하고 무게, 표면형상, 상(phase), 이온전도도 등의 변화를 관찰하였다. 또한 LLTO와 전극간의 반응성을 알아보기 위해 LLTO 분말과 음극물질인 $Li_4Ti_5O_{12}$ 및 양극물질인 $LiCoO_2$ 분말을 혼합한 후 $300^{\circ}C{\sim}700^{\circ}C$의 온도범위에서 열처리하여 반응을 가속화 한 후 상변화 현상을 살펴보았다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.8
• /
• pp.1486-1491
• /
• 2017

In this paper, we propose a private multimedia caching scheme based on wireless local area network (WLAN) to improve the quality of service for high capacity and high quality multimedia streaming services which are recently increasing and to reduce the traffic load of core networks. The proposed caching scheme stores multimedia in the storage device mounted on WLAN APs and provides streaming services on its own without Internet connection in accordance with the request from clients. We have implemented a test network based on real commercial networks and measured the performance of the proposed caching scheme in terms of frames per second (FPS) and buffering time. According to the performance measurement results, the proposed caching scheme can reduce the average buffering time by 73.3% compared to the conventional streaming scheme. In addition, the proposed caching scheme can also improve the average FPS by 71.3% compared to the conventional streaming scheme.

• Proceedings of KOSOMES biannual meeting
• /
• 2008.05a
• /
• pp.191-195
• /
• 2008

In Ansan (the headquarter of KORDI ; Korea Ocean Research & Development Institute), KOSC(Korea Ocean Satellite Center) is being prepared for acquisition, processing and distribution of sensor data via L-band from GOCI(Geostationary Ocean Color Imager) instrument which is loaded on COMS(Communication, Ocean and Meteorological Satellite); it will be launched in 2009. The basis equipment of KOSC(Electric power, Network, Security) has been constructed in 2007. KOSC is being constructed data processing and management system, GOCI L-band reception system, etc. The final object of KOSC is that maximize the application of GOCI.