• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.456-467
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• 2016

Wireless Access in Vehicular Environments (WAVE) communication technology, which provides vehicleto-vehicle and vehicle-to-infrastructure communication and offers safe and convenient service, has been developed for application to an Intelligent Transport System (ITS). This paper provides field test results on a study of the feasibility of WAVE technology application to railway communication systems. A test railway communication system based on WAVE technology has been built along the Daebul line and a newly developed EMU. Field tests have been carried out according to the communication function requirements for LTE - R. The test results show that the railway communication system based on WAVE technology meets the functional requirements: maximum transmission length is 730m, maximum transfer delay is 5.69ms, and maximum interruption time is 1.36s; other tests including throughput test, video data transmission test, VoIP data test, and channel switching test also produced results that meets the functional requirements. These results suggest that WAVE technology can be applied to the railway communication system, enabling Vehicle-to-Wayside communication.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.35-40
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• 2019

It is important to constantly provide service in real-time multimedia applications using multicast. Transmission path reconstruction occurs in hybrid multicast using Internet Protocol (IP) multicast and ALM in order to adapt the network status to things like congestion. So, there is a problem in which real-time QoS is reduced, caused by an increase in end-to-end delay. In this paper, we want to solve this problem through multi-layer transmission path construction. In the proposed method, we deploy the control server and application layer overlay host (ALOH) in each multicast domain (MD) for hybrid multicast construction. After the control server receives the control information from an ALOH that joins the MD, it makes a group based on the hop count and sends it to the ALOH in each MD. The ALOH in the MD performs the role of sending the packet to another ALOH and constructs the multi-layered transmission path in order of priority by using control information that is received from the control server and based on the delay between neighboring ALOHs. When congestion occurs in, or is absent from, the ALOH in the upper MD, the ALOH selects the path with the highest priority in order to reduce end-to-end delay. Simulation results show that the proposed method could reduce the end-to-end delay to less than 289 ms, on average, under congestion status.

• Korean Journal of Plant Resources
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• v.19 no.2
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• pp.252-258
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• 2006

The most effective conditions of In vitro culture and ex vitro sporophyte formation from prothallus were studied for mass propagation of Dyropteris varia. The most effective medium of prothallus proliferation was Murashige and Skoog's basal medium supplemented with 10:50mM of $NH_4^+:NO_3^-$ and 2% sucrose. The optimum pH level was 5.8 and prothallus growth was promoted on medium containing $0.6{\sim}0.8%$ agar. Almost of the tested growth regulators (NAA, IAA, 2,4-D, BAP, kinetin and 2ip) were inhibitory in prothallus proliferation as the concentration of growth regulators became higher. The highest number of sporophytes was obtained by transplanting prothallus on compost only than on any other soil compositions. Sporophyte formation was promoted remarkably by soaking prothallus with $100{\mu}M\;GA_3$ for 3 hours.

• Mass Spectrometry Letters
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• v.13 no.3
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• pp.49-57
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• 2022

During electrospray ionization mass spectrometry (ESI-MS) analysis of proteins, the addition of supercharging agents allows for adjusting the maximal charge state, affecting the charge state distribution, and increases the number of ions reaching the detector thus, improving signal detection. We postulate that in di-substituted arene isomers, molecules with higher polarizability values should generate greater interactions and hence elicit higher signal intensities. Polarizability is an electronic parameter which has been demonstrated to predict many chemical interactions. Many properties can be predicted based on charge polarization. Molecular polarizability is a vital descriptor for explaining intermolecular interactions. We employed DFT (density functional/Hartree-Fock hybrid model, B3LYP)-derived descriptors and computed molecular polarizability for ten disubstituted arene reagents, each set made up of three (ortho, meta, para) isomers, with reported use as supercharging reagents during ESI experiments. The atomic electronic inputs were ionization potential (IP), electron affinity (EA), electronegativity (𝛘), hardness (η), chemical potential (µ), and dipole moment (D). We determined that the para isomers showed the highest polarizability values in nine of the ten sets. There was no difference between the ortho and meta isomers. Polarizability also increased with increasing complexity of the substituents on the benzene ring. Polarizability correlated positively with IP, EA, 𝛘, η, and D but correlated negatively with chemical potential. This DFT study predicts that the para isomers of di-substituted arene isomers should elicit the strongest ESI responses. An experimental comparison of the three isomers, especially of larger supercharging molecules, could be carried out to establish this premise.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2A
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• pp.128-139
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• 2004

As the Internet usage grows, people want to access the Internet while they are moving. To satisfy this requirement economically, IEEE 802.11 Wireless LANs(WLANs) are rapidly deployed. In order to support mobility, WLANs must provide smooth handoff mechanism. Recent studies show, however, handoff delay of WLANs exceeds 300ms, most of which is due to slow scanning mechanism finding a new AP. With this handoff delay, current WLANs is not suitable to provide seamless realtime interactive services such as VoIP sevice. In this paper, we analyze the current handoff method of IEEE 802.11 and we propose a new handoff algorithm which can decrease time needed for searching a new AP and thus reduce overall handoff time. We show by simulation that the proposed algorithm has shorter handoff delay than current handoff method.

• International Journal of Computer Science & Network Security
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• v.23 no.4
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• pp.172-178
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• 2023

When the mobile device moves from the coverage of one access point to the radio coverage of another access point it needs to maintain its connection with the current access point before it successfully discovers the new access point, this process is known as handoff. During handoff the acceptable delay a voice over IP application can bear is of 50ms whereas the delay on medium access control layer is high enough that goes up to 350-500ms. This research provides a suitable methodology on medium access control layer of the IEEE 802.11 network. The medium access control layer comprises of three phases, namely discovery, reauthentication and re-association. The discovery phase on medium access control layer takes up to 90% of the total handoff latency. The objective is to effectively reduce the delay for discovery phase to ensure a seamless handoff. The research proposes a scheme that reduces the handoff latency effectively by scanning channels prior to the actual handoff process starts and scans only the neighboring access points. Further, the proposed scheme enables the mobile device to scan first the channel on which it is currently operating so that the mobile device has to perform minimum number of channel switches. The results show that the mobile device finds out the new potential access point prior to the handoff execution hence the delay during discovery of a new access point is minimized effectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.439-447
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• 2000

현재 방범 시스템은 적외선, 초음파 둥의 I-지기의 신호에 의존하여 외부로부터의 침입을 감지하고 있으나 방범 시스템이 설치된 환경에 따라 이런 감지기의 정확성이 달라지므로 오 동작의 가능성을 포함하며 신뢰성이 저하되고 있다. 실제 외부로부터의 침입을 확인하기 위해서는 화상과 음성 그리고 감지기의 신호를 조합하여 정확한 판단이 가능하지만 화상을 전송하기 위해서는 고가의 회선비용을 부담해야만 한다. 하지만 인터넷을 이용하여 화상을 전송하는 제품들이 출시되면서 Real-time 화상감시가 가능해졌다. 이런 화상감시 제품들은 Netscape, MS Explorer와 같은 표준 Web Browser을 통해 Real-time으르 전세계 어디서나 화상을 감시할 수 있다는 장점을 가지고 있다. 적용분야는 호텔주변, 관광지의 여러 명소에 설치 후 홈페이지에 링크시켜 홍보용으로 사용하거나 공장 주요시설, 교통상황 둥의 중요지역의 Monitoring에 활용하고 있다. 그러나 방범 시스템에 적용하기에는 감지기의 확장성, 방범 관제센터 시스템과의 연동이 부족하여 본 고에서는 현재 출시된 화상감시 시스템과 기존 방범시스템을 Integration하여 방범의 최종 목표인 화상과 감지기 신호의 조합에 따른 정확한 방범시스템의 구현에 대해서 기술하고자 한다. 화상방범시스템의 구현은 크게 두 가지로 나누어지며 첫째는 화상감시 시스템과 방범시스템간의 통신을 설계하는 것으로 기존 대부분의 방범시스템이 사용하는 RS-485 통신 프로토콜을 재설계하여 화상감시 시스템과의 통신을 설계하였으며 둘째는 화상감시시스템과 관제센터 시스템간의 통신을 설계하는 것으로 현재 화상감시 시스템의 TCP/IP 프로토콜을 이용한 socket 통신으로 관제센터 시스템과의 실시간 데이터 전송을 가능하게 했다. 이 시스템을 활용할 경우 고객들은 반드시 관제센터시스템의 인증을 거쳐야 하므로 고객의 DataBase를 축적할수 있으며 이 정보를 활용하여 인터넷 화상방범 서비스 Potal Site구축이 가능하다는 장점이 있다.

• Journal of Biosystems Engineering
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• v.28 no.1
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• pp.59-64
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• 2003

This study was carried out to develop database system using internet fur greenhouse. The database system consisted of group monitor, client monitor. server monitor and DBMS. The results of the study are summarized as follows. 1. The monitoring module, as data collection system for database. could monitor the state of the control device and the greenhouse environment. 2 The group monitor was connected to the house monitors by RS-485 communication method. Data received by the group monitor were sent to the server monitor and then stored in database server by TCP/IP and MIDAS. 3. The data of database consisted of on growing environment. control devices, operation and cultivation data in greenhouse. It was developed using MS-SQL server. 4. Remote monitoring of greenhouse was realized in a client/server environment. The client module. which was named as the client monitor. made requests to access the measurement data of greenhouse through the remote data module of the server monitor in internet environment.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1353-1356
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• 2000

최근 B2B 시스템 통합 및 전략적 제휴가 시장을 변화시키고 있고 관련 기업들의 효율적인 연계요구가 증가됨에 따라 기업간 시스템들의 연동이 중요한 문제로 부각되고 있다. 워크플로우 표준화 단체인 WfMC 에서도 이러한 문제 해결의 일환으로 인터넷을 통한 워크플로우 관리 시스템간 연동을 위한 표준인 Wf-XML Interoperability standard 를 발표하였다. 본 논문은 Wf-XML 표준 및 관련 연구들을 조사하고 WfMC 표준에는 정의되어 있지 않으나 시스템간의 신뢰성있는 연동을 위해 고려할 사항 중에서 동기적 및 비동기적 상호연동을 위한 요구사항들을 분석한다. TCP/IP 를 기반으로 한 HTTP 프로토콜을 전송 프로토콜로 채택하는 경우 여러 오퍼레이션들을 일괄처리하기 위해서는 비동기적인 상호연동(asynchronous interoperation)을 위한 별도의 메커니즘이 필요하다. 본 연구에서는 Wf-XML 문서를 HTTP 프로토콜을 사용하여 전송하는 경우 일괄처리요청(batch request) 및 그 밖의 동기적 또는 비동기적 요청들을 처리하기 위한 상호연동 모델을 분석하고 분산 워크플로우 시스템의 일종인 ICU/COWS에서의 적용방안에 관해서 논의한다.

• Molecules and Cells
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• v.41 no.2
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• pp.150-159
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• 2018

Animals use their odorant receptors to receive chemical information from the environment. Insect odorant receptors differ from the G protein-coupled odorant receptors in vertebrates and nematodes, and very little is known about their protein-protein interactions. Here, we introduce a mass spectrometric platform designed for the large-scale analysis of insect odorant receptor protein-protein interactions. Using this platform, we obtained the first Orco interactome from Drosophila melanogaster. From a total of 1,186 identified proteins, we narrowed the interaction candidates to 226, of which only two-thirds have been named. These candidates include the known olfactory proteins Or92a and Obp51a. Around 90% of the proteins having published names likely function inside the cell, and nearly half of these intracellular proteins are associated with the endomembrane system. In a basic loss-of-function electrophysiological screen, we found that the disruption of eight (i.e., Rab5, CG32795, Mpcp, Tom70, Vir-1, CG30427, Eaat1, and CG2781) of 28 randomly selected candidates affects olfactory responses in vivo. Thus, because this Orco interactome includes physiologically meaningful candidates, we anticipate that our platform will help guide further research on the molecular mechanisms of the insect odorant receptor family.