• Journal of Information Processing Systems
• /
• v.13 no.3
• /
• pp.518-532
• /
• 2017

Due to the rapid growth of the amount of data, research on bigdata processing has been highlighted. For bigdata processing, CUBRID Shard is able to support query processing in parallel way by dividing the database into a number of CUBRID servers. However, CUBRID Shard can answer a user's query only when the query is required to gain accesses to a single CUBRID server, instead of multiple ones. To solve the problem, in this paper we propose a CUBRID based distributed parallel query processing system that can answer a user's query in parallel and distributed manner. Finally, through the performance evaluation, we show that our proposed system provides 2-3 times better performance on query processing time than the existing CUBRID Shard.

• Journal of The Korean Astronomical Society
• /
• v.38 no.2
• /
• pp.291-293
• /
• 2005

Using 13.7 m telescope of Qinghai station of NAO, PMO at Delin Ha, 43 IRAS sources were mapped with $^{13}CO\;J=1-0\;C^{18}O\;J=1-0$ and CO J=1-0. Each source has one or more cores. The distances of these cores range from 1 pc to several pc, and the masses from $10^2\;M_{\bigodot}$ to $10^5\;M_{\bigodot}$. High velocity outflows were detected. The mass, momentum and energy of these massive cores are larger than those of the low mass ones. With radio, IRAS, MSX data, stellar source distribution were investigated, and sourceless cores that deviate from infrared sources were identified. They are potential high mass star formation sites.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.64 no.4
• /
• pp.251-255
• /
• 2015

Chiller system plays an important role of maintaining room temperature constantly by supplying chilled water to Heating, Ventilating and Air Conditioning(HVAC)or area room cooler equipment during plant normal operation or accident condition. Chiller failures are one of the most frequently occurring equipment failures. If the types of chiller failures are analyzed and grouped thoroughly, it would be helpful to make chiller maintenance strategy at the plants. That would enhance equipment reliability of chiller in the end. In this paper, chiller failure data during three years were analyzed and categorized by specific failure code. In addition, the various proposals to improve equipment reliability of chiller were suggested such as Preventive Maintenance Optimization(PMO) strategy and performance monitoring reinforcement and so on.

• Environmental Analysis Health and Toxicology
• /
• v.23 no.3
• /
• pp.195-200
• /
• 2008

Hydroxylated polychlorinated biphenyl (OH-PCBs)는 PCB의 CYP-dependent oxidation의 대사물로서 잠재적 독성이 강하고 지질친화성을 가지며 생물군에 지속적인 축적성을 나타낸다. OH-PCBs의 해독화 효능을 조사하기 위하여 channel catfish 간에서 glucuronidation을 통한 해독작용 가능성을 평가하고 biphenyl 구조에 다양한 염소치환의 구조적 차이점에 따른 영향을 비교 분석하여 보았다. Kinetic parameters에서 $K_m$과 $V_{max}$는 $192{\sim}871{\mu}M$, $869{\sim}1774$ pmo1/min/mg으로써 4'-OH-PCB35와 4'-OH-PCB69이 가장 높은 속도의 glucuronidation을 나타냈으며, 구조적 차이점에서 phenolic group에 한 개의 염소치환이 존재할 경우보다 두 개의 염소치환이 존재할 경우에 OH-PCBs(p<0.001)의 glucuronidation에 대한 $V_{max}$를 현저하게 낮추는 결과를 보였다.

• Proceedings of the IEEK Conference
• /
• 2003.07b
• /
• pp.1003-1006
• /
• 2003

본 논문에서는 sub-micron 소자에서 SCE(Short Channel Effect) 억제를 위한 Halo 와 SSR(Super Steep Retrograde Well) 적용에 따른 analog 특성의 열화를 석하고 이를 개선하기 위해 Twist 이온주입과 In, Sb Halo 를 채택하였다. Analog 특성은 CMOS 의 amplifier 과 Comparator 로의 사용을 고려해 Drain Rout과 Early voltage를 이용해 나타내었으며 Digital 성능을 함께 고려하였다. 실험결과 NMOS 의 경우 45 twist Halo 조건에서, PMOS의 경우 As보다 Sb를 Halo 로 적용하는 경우 더 우수한 analog 특성을 나타내었다.

• Journal of Korean Society for Atmospheric Environment
• /
• v.11 no.1
• /
• pp.77-84
• /
• 1995

To prevent or reduce air pollutant from methanol fueled vehicles, methanol oxidation reaction was carried out using a heteropoly acid catalysts. Catalytic activities of catalysts have been experimented at atmospheric pressure in a fixed bed flow reactor. Catalysts were characterized by XRD, IR, thermal analysis, N $H_{3}$-TPD and GC pulse technique. Acidities of catalysts were highly affected by poly-atoms. Methanol conversion was much higher on catalyst with W than on catalyst with Mo as a poly-atoms. With the increase of copper content(X) in C $u_{x}$ $H_{{3-2x}}$PMo catalyst, acidity was decreased and oxidation ability was increased. Methanol conversion and product distribution were affected by the acidity and oxidation ability of catalyst. Especially, supported PdSiW(1wt%) catalyst has a very good methanol conversion and C $O_{2}$ selectivity as high as a commertial 3-way catalyst.t.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.3
• /
• pp.181-185
• /
• 2003

Influence of post gate oxidation anneal on Negative Bias Temperature Instability (NBTI) of PMOSFE has been investigated. At oxidation anneal temperature raised above 950$^{\circ}$C, a significant improvement of NBTI was observed which enables to reduce PMO V$\_$th/ shift occurred during a Bias Temperature (BT) stress. The high temperature anneal appears to suppress charge generations inside the gate oxide and near the silicon oxide interface during the BT stress. By measuring band-to-band tunneling currents and subthreshold slopes, reduction of oxide trapped charges and interface states at the high temperature oxidation anneal was confirmed.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.4
• /
• pp.810-816
• /
• 2009

The interactions between four Keggin-type POMs (${SiW_{12}O_{40}}^{4-},\;{PW_{12}O_{40}}^{3-},\;{SiMo_{12}O_{40}}^{4-},\;and\;{PMo_{12}O_{40}}^{3-}$) and glassy carbon (GC) and highly oriented pyrolytic graphite (HOPG) surfaces are investigated in a systematic way. Electrochemical results show that molibdate series POMs adsorb relatively stronger than tungstate POMs on GC and HOPG surfaces. Adsorption of POMs on HOPG electrode surfaces is relatively stronger than on GC surfaces. ${SiMo_{12}O_{40}}^{4-}$ species exhibits unique adsorption behaviors on HOPG surfaces. Surface-confined ${SiMo_{12}O_{40}}^{4-}$ species on HOPG surfaces exhibit unique adsorption behaviors and inhibit the electron transfer from the solution phase species. The catalytic activity of the surface-confined POMs for hydrogen peroxide electroreduction is also examined, where ${PW_{12}O_{40}}^{3-}$ species adsorbed on GC surfaces exhibits the highest catalytic efficiency among the investigated POM modified electrode systems.

• Journal of the Korean Chemical Society
• /
• v.20 no.2
• /
• pp.136-140
• /
• 1976

The photocyclodehydrogenation reaction of o-terphenyl type compounds has been interpreted with perturbational molecular orbital theory. Results show that the mobile bond order for the first excited state is a good reactivity index and this approach is also consistent with the orbital symmetry conservation rule of Woodward and Hoffmann.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.20 no.6
• /
• pp.794-802
• /
• 2017

Unmanned Aerial Vehicles (UAVs) have been considered as valuable aerial reconnaissance systems and our army wants capability-enhanced UAVs installed in our territory, hoping that the UAVs will provide enemy information in detail. The enemy information acqcuired by UAVs would be shared by our army's legacy systems. In this article, we made a research on the interoperability between UAVs and Ground Fighting Vehicles (GFVs), laying emphasis on what kinds of tactical information could be exchanged by two different weapon systems. Also, it needs to be addressed that their upper-level commanding systems play a significant role in such operation.