• Journal of Internet Computing and Services
• /
• v.6 no.4
• /
• pp.115-124
• /
• 2005

The packet loss problem that occurs in the mobile multicast (MoM) protocol due to designated multicast service provider(DMSP) handoff is investigated through simulation experiments for several DMSP selection policies. Then, two enhanced DMSP schemes are proposed to minimize the packet loss of the MoM protocol with single DMSP. The first scheme uses a backup DMSP and greatly reduces the packet loss rate at the expense of the increased network traffic. The second scheme utilizes the extended DMSP operation and shows many desirable features such as the almost zero packet loss rate and relatively low network traffic.

• Proceedings of the Korea Society of Information Technology Applications Conference
• /
• 2005.11a
• /
• pp.61-64
• /
• 2005

The packet loss problem that occurs in the mobile multicast (MoM) protocol due to designated multicast service provider (DMSP) handoff is investigated through simulation experiments for several DMSP selection policies. Then, two enhanced DMSP schemes are proposed to minimize the packet loss of the MoM protocol with single DMSP. The first scheme uses a backup DMSP and greatly reduces the packet loss rate at the expense of the increased network traffic. The second scheme utilizes the extended DMSP operation and shows many desirable features such as the almost-zero packet loss rate and relatively low network traffic.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.7
• /
• pp.41-46
• /
• 2004

Two multicast delivery schemes are proposed to minimize the packet loss that occurs in the mobile multicast (MoM) protocol due to the handoff and relocation. The proposed schemes use a primary designated multicast service provider (DMSP) and a redundant or non-redundant backup DMSP. The simulation results verify that the proposed schemes greatly reduce the packet loss rate at the expense of the increased network traffic or the extra protocol overhead related to the operation of the non-redundant backup DMSP.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.04a
• /
• pp.193-195
• /
• 2002

본 논문에서는 최근에 제안된 Hybrid 방식의 모바일 멀티캐스트 프로토콜 중 MOM, MMA, RBMOM, 그리고 TBMOM 프로토콜에 대해서 여러 가지 관점에서 성능을 비교하여 각 프로토콜의 장단점을 분석함과 동시에, 이들 방식이 공통적으로 가지는 DMSP(Designated Multicast Service Provider) 핸드오프 문제에 대해서 Smooth DMSP 핸드오프방식을 제안한다.

• Journal of Marine Life Science
• /
• v.6 no.1
• /
• pp.1-8
• /
• 2021

In marine ecosystems, the biosynthesis and catabolism of dimethylsulfoniopropionate (DMSP) by marine bacteria is critical to microbial survival and the ocean food chain. Furthermore, these processes also influence sulfur recycling and climate change. Recent studies using emerging genome sequencing data and extensive bioinformatics analysis have enabled us to identify new DMSP-related genes. Currently, seven bacterial DMSP lyases (DddD, DddP, DddY, DddK, DddL, DddQ and DddW), two acrylate degrading enzymes (DddA and DddC), and four demethylases (DmdA, DmdB, DmdC, and DmdD) have been identified and characterized in diverse marine bacteria. In this review, we focus on the biochemical properties of DMSP cleavage enzymes with special attention to DddD, DddA, and DddC pathways. These three enzymes function in the production of acetyl coenzyme A (CoA) and CO₂ from DMSP. DddD is a DMSP lyase that converts DMSP to 3-hydroxypropionate with the release of dimethylsulfide. 3-Hydroxypropionate is then converted to malonate semialdehyde by DddA, an alcohol dehydrogenase. Then, DddC transforms malonate semialdehyde to acetyl-CoA and CO₂ gas. DddC is a putative methylmalonate semialdehyde dehydrogenase that requires nicotinamide adenine dinucleotide and CoA cofactors. Here we review recent insights into the structural characteristics of these enzymes and the molecular events of DMSP degradation.

• Polymer(Korea)
• /
• v.32 no.2
• /
• pp.189-192
• /
• 2008

A styrylpyrylium salt (DHSP) was synthesized and then photodimerized to obtain a cyclobutane-type dimer (DHSP dimer). Methacryloyl group was incorporated into DHSP dimer to obtain DMSP dimer. Based on FT-IR analysis of a crosslinked DMSP dimer, it was considered that the cyclobutane structure reversed to styryl C=C bonds upon crack formation. Fluorescence measurement of DHSP in solid state (excitation at 385 nm) showed emission centered at 626 nm, while DHSP dimer revealed very weak emission. Fluorescent emission from microcracks in a film of crosslinked DMSP dimer was observed upon exposure to $330{\sim}385\;nm$ light.

• Korean Journal of Remote Sensing
• /
• v.27 no.1
• /
• pp.69-74
• /
• 2011

It may be an important issue to estimate population of a concerned country. In this study, an appropriate variable was selected to establish a model which fits best the relationship between the night time imagery of DMSP-OLS and population data. Exponential model was selected which was proposed by previous study. Accuracy validation was also performed for each variable extracted from the night time imagery of DMSP-OLS. Consequently, the model showed high accuracy when applied to the area of a certain amount of light was existed. However, further consideration should be necessary when to applied other country or other part of regions.

• Journal of the Economic Geographical Society of Korea
• /
• v.22 no.4
• /
• pp.458-471
• /
• 2019

DMSP-OLS nighttime satellite imagery could be used to derive the sum of lights (SOL) and built-up area, and the two indices have been widely employed to make the estimation of socio-economic variables and the dynamics of urban developments. Considering it, this research investigated the spatiotemporal patterns of economic growth and urbanized area in Jilin Province, China, using DMSP-OLS data for a time span between 1992 and 2012. This study found the SOLs of both the province and most cities to tend to grow during the period. While SOL-weighted centroids' means moved towards northwestern direction, urban-area centroids' means followed the trend of south-eastern migration. These directional patterns could be associated with the Northeast Revitalization Plan of Chinese governments. Nonetheless, a future study will need to consider SNPP VIIRS DNB imagery in order to overcome temporal limitation of DMSP-OLS data. In addition, it is also necessary to estimate socio-economic indices, e.g., growth regional domestic product, using a regression model developed with correlation relationship between economic statistics ad SOL.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.38 no.5
• /
• pp.323-330
• /
• 2005

Monthly distributions of fishing boats at night in the East Sea are described, using defense meteorological satellite program (DMSP)/operational linescan system (OLS) images and common squid (Todarodes pacificus) catches data. We also estimated temperature in 50m, which is main catch depth of the squid, by MCSST (multi-channel sea surface temperature). We examined DMSP/OLS, MCSST and other observation data from 1993 to 2000. We assumed that squid were caught in areas where fishing boats were located. Fishing boats at night appeared only near the Korea/Tsushima Strait from January to March. Fishing boats moved to the northward from April to Jun, distribution of fishing boats in spring appeared greater than those in winter. In summer (July-September), center of fishing grounds was formed near the Uleung Island in the south east coast of Korea. The north-south distribution range of fishing boats in October appeared to be greater than that in other months. In particular, we estimated main season of squid catches based on distribution range reflecting the number of fishing boats of north-south and east-west directions from September to December. Relationship between satellite estimate SST and in situ SST showed high correlation (0.91). The correlation between the SST and 50m depth temperature, estimated based on the satellite SST, was relatively high in February, April and October.

• Journal of Astronomy and Space Sciences
• /
• v.33 no.4
• /
• pp.305-311
• /
• 2016

The spatial size and variation of Arctic sea ice play an important role in Earth's climate system. These are affected by conditions in the polar atmosphere and Arctic sea temperatures. The Arctic sea ice concentration is calculated from brightness temperature data derived from the Defense Meteorological Satellite program (DMSP) F13 Special Sensor Microwave/Imagers (SSMI) and the DMSP F17 Special Sensor Microwave Imager/Sounder (SSMIS) sensors. Many previous studies point to significant reductions in sea ice and their causes. We investigated the variability of Arctic sea ice using the daily sea ice concentration data from passive microwave observations to identify the sea ice melting regions near the Arctic polar ice cap. We discovered the abnormal melting of the Arctic sea ice near the North Pole during the summer and the winter. This phenomenon is hard to explain only surface air temperature or solar heating as suggested by recent studies. We propose a hypothesis explaining this phenomenon. The heat from the deep sea in Arctic Ocean ridges and/or the hydrothermal vents might be contributing to the melting of Arctic sea ice. This hypothesis could be verified by the observation of warm water column structure below the melting or thinning arctic sea ice through the project such as Coriolis dataset for reanalysis (CORA).