• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.42.2-42.2
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• 2021

Intraclusterlight (ICL) is diffuse light from stars that are bound to the clusterpotential, not to individual member galaxies. Understanding the formationmechanism of ICL provides critical information on the assembly and evolution ofthe galaxy cluster. Although there exist several competing models, the dominantproduction mechanism is still in dispute. The ICL measurement between z=1 and 2strongly constrains the formation scenario of the ICL because the epoch is whenthe first mature clusters begin to appear. However, the number of high-redshiftICL studies is small mainly because of observational challenges. In this study, based on deep HST WFC3/IR data, we measured ICL of 10 galaxy clusters atredshift beyond unity, which nearly doubles the sample size in this redshiftregime. With careful handling of systematics including object masking, skyestimation, flatfielding, dwarf galaxy contamination, etc., we quantified thetotal amount of ICL, measured the color profile, and examined the transitionbetween BCG and ICL.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.3
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• pp.143-152
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• 2002

As the multimedia application becomes ubiquitous, the size of message used for Inter Process Communication (IPC) grows up to cope with the requirements of multimedia applications. And the rapid development of new hardware platforms makes the portability of operating system more important. But the traditional micro-kernel operating system is Implemented platform dependently for better performance, and especially focused on handling short message. In this paper, we present the design and implementation of IPC mechanism in M3K (MultiMedia Micro-Kernel) to address the above problems. Our IPC mechanism provides enhanced performance and efficiently handles large message without performance degrading.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.3
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• pp.509-516
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• 2018

TCP is a well-known communication protocol which is widely used for reliable message transmissions. The urgent mechanism of TCP plays a key role to transmit messages with a high priority. If a high priority message occurs at the transmitting node, the urgent mechanism informs the receiving node about the presence of a high priority message prior to its transmission so that the receiving node can be prepared for handling this message in advance. This implies that the existing urgent mechanism of TCP does not guarantee an immediate or faster delivery of the high priority message itself. Therefore, the ability of priority-based transmission is required on TCP not only to ensure reliable transmissions of normal messages but also to offer a differentiated service according to the priority of message. This paper presents a priority-based transmission algorithm over TCP using a priority queue in a multi-threaded environment. The effectiveness of the proposed algorithm is explored using an experimental setup in which various messages with different priority levels are transmitted.

• Journal of KIISE:Information Networking
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• v.35 no.2
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• pp.120-129
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• 2008

The purpose of sensor network is gathering the information from sensor nodes. If there are selfish node that deliberately avoid packet forwarding to save their own energy, the sensor network has trouble to collect information smoothly. To solve this problem we suggest a mechanism which uses credit payment schema according to the amount of forwarding packets. Sensor nodes use credits to send their own message and they forward packets of other sensor nodes to get credits. To offer authenticity we combined the roles of sink node and server, also we used piggybacking not to send additional report message. The packet trace route is almost fixed because sensor node doesn't have mobility. In this case, it happens that some sensor nodes which don't receive forwarding packets therefore they can't get credit. So, we suggested the way to give more credits to these sensor nodes. Finally, we simulated the suggested mechanism to evaluate performance with ns2(network simulator). As a result, packet transmission rate was kept on a high rate and the number of arrival packets to sink node was increased. Also, we could verify that more sensor nodes live longer due to deceasing the energy consumption of sensor nodes.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.223-228
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• 2009

Efficient service discovery mechanism is a crucial feature for a hybrid ad-hoc network supporting extension of a wireless ad-hoc network to the Internet. We propose an efficient cross-layer service discovery mechanism using non-disjoint multi-path source routing protocol for hybrid ad-hoc networks. Our scheme has advantages of multi-path routing protocol and cross-layer service discovery. Intuitively, it is not difficult to imagine that the cross-layer service discovery mechanism could result in a decreased number of messages compared to the traditional approach for handling routing independently from service discovery. By simulation, we show that faster route recovery is possible by maintaining multiple routing paths in each node, and the route maintenance overhead can be reduced by limiting the number of multiple routing paths and by maintaining link/node non-disjoint multi-path.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.10
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• pp.1875-1882
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• 2008

Nowadays, usage of mobile unit which has a characteristic of low cost and high efficiency is being generalized because of frequent use of internet-based variable service and application in IEEE 802.16 WiMAX. A study for handling a security problem of high speed internet service is rising while the use of a mobile is being generalized. This paper suggests a security mechanism which provides safety from certification load of SS and a security attack as well as a basic function which is provided from IEEE 802.16e standard to satisfy security demand of IEEE802.16 WiMAX. The proposed mechanism exchangeskey material information for TEK and data code by using 난수(?) and secret value created by SS and BS, also reduces capacity load of BS not to perform an additional certificate procedure of BS by using the early certification information and certificate of SS.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.1
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• pp.71-75
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• 2008

Many sensor operating systems have memory limitation constraint; therefore, stack memory areas of threads resides in a single memory space. Because most target platforms do not have hardware MMY (Memory Management Unit), it is difficult to protect each stack area. The method to solve this problem is to exchange original stack handling instructions in binary code for wrapper routines to protect stack area. In this exchanging phase, instruction corruption problem occurs due to difference of each instruction length between stack handling instructions and branch instructions. In this paper, we propose the algorithm to call a target routine without instruction corruption problem. This algorithm can reach a target routine by repeating branch instructions to have a short range. Our solution makes it easy to apply security patch and maintain upgrade of software of sensor node.

• Journal of Astronomy and Space Sciences
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• v.31 no.3
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• pp.235-240
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• 2014

The communications link in a space program is a crucial point for upgrading its performance by handling data between spacecraft bus and payloads, because spacecraft's missions are related to the data handling mechanism using communications ports such as a controlled area network bus (CAN Bus) and a universal asynchronous receiver and transmitter (UART). The NEXTSat-1 has a lot of communications ports for performing science and technology missions. However, the top level system requirements for the NEXTSat-1 are mass and volume limitations. Normally, the communications for units shall be conducted by using point to point link which require more mass and volume to interconnect. Thus, our approach for the novel communications link in the NEXTSat-1 program is to use CAN and serializer and deserializer low voltage differential signal (SerDesLVDS) to meet the system requirements of mass and volume. The CAN Bus and SerDesLVDS were confirmed by using already defined communications link for our missions in the NEXTSat-1 program and the analysis results were reported in this study in view of data flow and size analysis.

• Korean Journal of Organic Agriculture
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• v.28 no.4
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• pp.535-553
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• 2020

In this study, the characteristics of the waste sector CDM project were analyzed through cluster analysis of the waste sector CDM project and the analysis of the CDM investment cost in waste sector using CDM project data registered with UNFCCC since 2008 when EU ETS phase 2 began. As of September 2020, 772 cases of CDM projects in waste disposal and disposal are registered. Biogas technology is the largest, followed by livestock manure processing and biomass production technology. The results of the cluster analysis are summarized as follows: First, on average, projects utilizing AWMS technology are small in size and relatively low in investment costs. This is judged to be relatively low investment costs due to previously attracted foreign investment capital. Second, the average investment cost of CDM projects considered along with waste (No.13), the energy industry (No.1) and agriculture (No.15) was higher than those involving only waste. The analysis of the factors determining the investment cost of the waste sector CDM project showed that, as with cluster analysis, the AWMS technology, which is a livestock manure treatment technology, was lower in the investment cost than those that use other technologies. As a result of multiple regression analysis, the investment cost of the CDM project was analyzed lower in the order of biomass, AWMS, LFG and biogas. Also, the higher the investment cost for CDM projects linked to waste, energy and agriculture, and the better the investment environment, the higher the investment cost. Although no statistical feasibility was obtained, the larger the annual emission reduction, the lower the CDM investment cost.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.85-85
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• 2019

Objective: In this study, the anti-stress effects of extract of Hydrangeae Dulcis Folium (EHDF) or ethalonic extract of Opuntiaficus-indica (EOF) of natural extracts from Jeju Island were investigated. Methods: We performed measurement of whole-body cortisol level and behavioral experiments including the novel tank test (NTT) or the open field test (OFT) to assess stress responses in zebrafish. To induce physical stress, we used the net handling stress (NHS). Fish were treated with EOF or EHDF for 6 min before they were exposed to stress. And then, we sacrificed fish for collecting body fluid from whole-body or conducted behavioural tests, including novel tank test and open field test, were evaluated to observe anxiety-like behaviours and locomotion. We used the cortisol enzyme-linked immunoassay kit to measure the amount of cortisol in each zebrafish sample. Results: The results indicate that increased anxiety-like behaviours in novel tank test and open field test under stress were prevented by treatment with both EOF and EHDF (P < 0.05). Moreover, compared with the unstressed group, which was not treated with NHS, the whole-body cortisol level was significantly increased by treatment with NHS. Compared with the NHS-treated stressed control group, pre-treatment with each EHDF and EOF for 6 min significantly prevented the NHS-increased whole-body cortisol level (P < 0.05). Conclusions: In conclusion these results suggest that both EOF and EHDF pretreatment may prevent stress responses and that its mechanism of action may be related to its positive effects on cortisol release.