• Journal of KIISE:Computing Practices and Letters
• /
• v.9 no.1
• /
• pp.77-85
• /
• 2003

The conversion into a new Local Area Network (LAN) environment without clear analysis of the problems with the conventional LAN environment nay bring about some improvement of performance, but in general, the result would not be as good as expected. Besides, in case new traffic or application programs are added In the near future, traffic overload similar to the past may incur. Therefore, the conversion into a new LAN environment should not only relieve the problems with the conventional environment but also be able to cope with future expansion of the network flexibly. In the present paper, in view of the above, the problems with protocols and traffic that may occur in the Bus-structured 10/100 Mbps shared Ethernet that has been widely used by many institutions are reviewed, and as a case study whether such conversion into a new LAN environment in order to increase the efficiency in the operation, management, and utilization of the network would be proper for the actual operational environment is implemented, and the results are analyzed.

• Clean Technology
• /
• v.22 no.4
• /
• pp.250-257
• /
• 2016

As an attempt to replacing petroleum-based chemicals with bio-based ones, synthesis of furfural from biomass-derived xylose attracts much attention in recent days. Conventionally, furfural from xylose has been produced via the utilization of highly corrosive, toxic, and environmentally unfriendly mineral acids such as sulfuric acid or hydrochloric acid. In this study, microwave-assisted biphasic reaction process in the presence of novel bio-based heterogeneous acid catalysts was developed for the eco-benign and effective synthesis of furfural from xylose. The microwave was irradiated for reaction acceleration and a biphasic system consisting of $H_2O$ : MIBK (1 : 2) was designed for continuous extraction of furfural into the organic phase in order to reduce the undesired side products formed by decomposition/condensation/oligomerization in the acidic aqueous phase. Moreover, sulfonated amorphous carbonaceous materials were prepared from wood powder, the most abundant lignocellulosic biomass. The prepared catalysts were characterized by FT-IR, XPS, BET, elemental analysis and they were used as bio-based heterogeneous acid catalysts for the dehydration of xylose into furfural more effectively. For further optimization, the effect of temperature, reaction time, water/organic solvent ratio, and substrate/catalyst ratio on the xylose conversion and furfural yield were investigated and 100% conversion of xylose and 74% yield of furfural was achieved within 5 h at $180^{\circ}C$. The bio-based heterogeneous acid catalysts could be used three times without any significant loss of activity. This greener protocol provides highly selective conversion of xylose to furfural as well as facile isolation of product and bio-based heterogeneous acid catalysts can alternate the environmentally-burdened mineral acids.

• Journal of Broadcast Engineering
• /
• v.25 no.2
• /
• pp.252-264
• /
• 2020

Korea has launched the world-wide first terrestrial UHD broadcast services on May 31, 2017. While the existing HDTV broadcast services use MPEG-2 TS (Tranport Stream) standard for multiplexing and delivering compressed media with additional data, the terrestrial UHD broadcast services use MMT (MPEG Media Transport) standard, which is the next-generation standard beyond MPEG-2 TS. However, the production cost of UHD contents is so high that only a part of the total broadcast time is filled with UHD contents and the UHD time portion is planned to be gradually increased. On the other hand, the ATSC 3.0 standard that uses MMT is not yet used in full-fledged broadcast services in North America. Hence MMT broadcast equipment is still at an early stage with high prices. In this paper we implemented a multi-thread software running on an ordinary PC that can be utilized to realize a low-cost converter that converts the output of an existing MPEG-2 TS multiplexer to an MMTP (MMT Protocol) packet stream. We also verified the functionality of the software through experiments.

• Journal of Internet Computing and Services
• /
• v.6 no.3
• /
• pp.45-54
• /
• 2005

Recently, researches on various base technologies for wireless Internet services have been conducted. In the WAP (Wireless Application Protocol) Forum, a WAP gateway which does mutual conversion between existent wired Internet protocols and WAP protocols was proposed. In this paper, CSA(Client Side Agent) and SSA(Server Side Agent) for WAP gateway environments are designed and implemented, as a way of improving communication efficiency in such restrictive environments as wireless communications. Located on mobile WAP devices(CSA) and a WAP Gateway(SSA), the agents perform communication efficiency improvement activities such as a packet header reduction mechanism and a data reduction mechanism using data differencing analysis in order to reduce the size of data transmission in wireless communication environments. The Internet phone emulator of Phone.com is used in order to make sure that the implemented agents work correctly, Experimental results show that the implemented agents reduce the size of data transmission significantly.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.6 no.8
• /
• pp.1187-1193
• /
• 2002

There are POP3(Post Office Progocol 3) and IMAP4(Internet Message Access Protocol 4) for E-Mail service of wire Internet For mobile e-mail service that use wireless Internet, must use exclusive use mobile e-mail server in the case of POP3 e-mail or flow e-mail conversion and because e-mail is kept in sever side with remote file server in case of IMAP4 mail that is used by Web-Mail, utilization of mobile e-mail service is difficult by mobile client who there is no IMAP4 rules. This thesis embodying e-mail extraction engine for mobile that do to design markup language converter of XML base, and use Web-Mail of recently been generalizing IMAP4 base in mobile, presented mobile e-mail service method to do so that can use Web-Mail that is based on IMAP4 as well as POP3 mail service in mobile environment.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.4B
• /
• pp.351-360
• /
• 2003

All-optical network provede unlimited for bandwidth, the very low bit error rate, and the transparency to IP. Optical networks promise to be the next generation networks that can meet the higher bandwidth demands. However, the number of wavelengths is often not large enough to help a large amount of nodes. The blocking by wavelength contention can be reduced by wavelength conversion, which can't perfectly resolve all situations. Because of that, a lot of groups have proposed unique wavelength assingment algorithms and protocols. Most schemes don't support the priority concepts. This paper describes the unique priority scheme based on the throughput. In this paper, we apply our priority scheme to SWAP(Simple Wavelength Assignment Protocol) and show the performance of the proposed priority scheme. Our proposed priority scheme can be a better solution to solve an important problem about the blocking by wavelength contention into WDM optical networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2019.05a
• /
• pp.133-136
• /
• 2019

Recently, many industrial devices are facing protocol compatibility problems with external monitoring and control systems. This paper designed an industrial communication gateway that can support the transformation of industrial communication protocol using multi-layered communication module. Industrial communication gateways have a structure that connects individual communication modules using rs485 serial communication to multiple layers. Each communication module consisted of analog data card, a digital data card LAN, and a CAN-enabled card. The main board processor used Atmega micro-processor, and the rs485 serial slot was placed to have a multi-layer communication module structure. These additive layer type communication modules support analog and digital I/O functions and LAN and CAN for wide use in industrial communication control and monitoring.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.11a
• /
• pp.298-300
• /
• 2005

오늘날 공장 자동화에 이용되는 필드버스 네트워크는 많은 종류가 있으며 각각의 특징 및 장단점을 가지고 다양하게 이용되고 있다. 이러한 필드버스 네트워크용 프로토콜은 서로 다른 특징으로 인하여 관리자가 효율적으로 네트워크를 관리하는데 어려움이 크다. 본 논문에서는 이러한 이기종의 필드버스 네트워크를 통합할 수 있는 필드버스 네트워크 프로토콜 변환 게이트웨이를 설계 및 구현하였다.

• Proceedings of the Korean Information Science Society Conference
• /
• 1998.10a
• /
• pp.509-511
• /
• 1998

본 논문에서는 인터넷 실시간 프로토콜들을 이용한 응용으로써 미디어 변환 시스템에 관한 연구를 다루고 있다. 인터넷 실시간 프로토콜인 RTP, RTCP, RTSP를 설계 구현하였고, 이를 기반으로 한 오디오 및 비디오 스트림을 위한 미디어 변환 시스템을 구현하였다. 인터넷 실시간 프로토콜은 네트워크의 상황에 따른 정보를 이용하여 미디어 변환기를 제어한다.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.9
• /
• pp.2066-2070
• /
• 2009

$Cl_3CCONH_2$ coupled with $PPh_3$ was determined to be an effective reagent for the conversion of carboxylic acids to their corresponding acid chlorides. Subsequently, these acid chlorides were successfully trapped with amines in the presence of 4-picoline, yielding amides. This practical and efficient protocol can be utilized for the synthesis of biological amides in excellent yields.