• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.5
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• pp.396-401
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• 2017

In this paper, we propose a solution for interference with Bluetooth when connecting Bluetooth and other devices. The random frequency hopping technique is a technique of generating a hopping pattern using the entire Bluetooth channel without considering the interference of the wireless LAN. The proposed adaptive frequency hopping technique is a technique for generating a hopping pattern of Bluetooth channel considering periodic carrier sensing of Bluetooth and considering WLAN interference. Simulation results show that the use of adaptive frequency hopping reduces the packet error rate as the Bluetooth carrier sensing interval decreases even in the congestion of WLAN interference. Especially, the frequency hopping technique improves the average packet error rate by about 13% compared to the adaptive frequency hopping technique.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.604-611
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• 2007

In this paper, we present an analysis of the throughput when there are multiple piconets and WLAN sharing the ISM bands. The analysis takes channel propagation characteristics and the capture effect. We also propose an algorithm which can be used to reduce the amount of channel scanning. By using traffic prediction of the interfering WLAN, we are able to maintain a reasonable performance in terms of fraction of time channel is wasted due to collisions or unused channel. Through computer simulation, we demonstrate that the proposed algorithm achieves reduced scanning frequency.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.3-12
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• 2001

Bluetooth stands for a technical specification for radio communication or a radio equipment that uses the Bluetooth specification of which the main purpose is to substitute the complicated communication cable of the informative device or electronic apparatus used at home or industrial fields, and was expected to be a mastermind of revolution in the short range radio communication. But the Bluetooth has recently been led to the mobile communication field which is somewhat apart from the primary purpose of Bluetooth and occur the question on its effectiveness. This paper review the situation of Bluetooth in the aspect of radio technical criteria and propose the direction for improvement of regulatory basis considering the prospection of the technical development of Bluetooth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.434-437
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• 2001

Bluetooth is currently a conceptual success with few tangible results, but in the future it will have significant implications for the end user and the wireless industry. For new entrants, Bluetooth presents an excellent opportunity to stake a claim in the wireless landscape, while for the incumbents it is primarily a tool to drive the demand for their wireless products and services. However, Bluetooth must still overcome many obstacles before it can become a universal catalyst for wireless data adoption. This paper describes the Bluetooth technology and provides a foundation for evaluating its potential as a wireless technology and a market driver.

• Journal of the Speleological Society of Korea
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• no.79
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• pp.7-16
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• 2007

블루투스란 근거리에 놓여 있는 컴퓨터와 이동단말기 가전제품 등을 무선으로 연결하여 쌍방향으로 실시간 통신을 가능하게 해주는 규격을 말하거나 그 규격에 맞는 제품을 이르는 말이다. 가정 및 사무실에서 사용되는 모든 정보기기에 장착되는 것을 목표로 무선망을 구성하여 어떠한 유/무선망과도 연동할 수 있게 한다. 따라서, 블루투스를 이용한 무선 네트워크가 완성되면 모든 정보기기간의 자유로운 데이터 교환이 이루어지며, 인터넷 브리지를 구성하면 현재 광케이블이나 ADSL, 모뎀 등을 통해 데스크탑 컴퓨터에 도달해 있는 인터넷 정보가 비로소 사용자의 손안에까지 도달할 수 있게 된다. 즉, 무선통신의 궁극적인 목표인 언제, 어디서나, 누구나, 어떤 형태의 정보도 교환한다는 목표에 대한 완성으로까지 볼 수 있다. 미국 시장조사 회사 가트너의 "블루투스 시장의 3단계 발전 전망"이라는 보고서에 따르면, 첫 단계에서는 어댑터 카드나 USB 단자 부착 PC, 고기능 휴대폰 등에 채택되고, 두 번째 단계에는 저가의 Mobile 제품, 무선전화, 개인휴대단말기, 가정용 네트워킹기기, 자동차 등으로 블루투스 탑재기기가 크게 증가할 것이고, 세 번째 단계에는 거의 모든 휴대기기에 채택되어 시장규모가 확대될 것으로 전망하고 있다. 블루투스는 현재 휴대폰, 노트북 컴퓨터, 디지털카메라, 휴대 게임기 등 휴대기기 제조업체는 물론 자동차 제조업체 등 전자, 정보홍신 이외 기업의 지지도 받고 있다.

• Journal of Environmental Science International
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• v.31 no.4
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• pp.295-309
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• 2022

The purpose of this study was to evaluate the operational characteristics of wastewater treatment using Sequencing Batch Reactor (SBR) with Aerobic Granular Sludge (AGS) separator in the pilot plant. Pilot plant experiments were conducted using SBR with AGS separator and pollution removal efficiencies were evaluated based on the operational condition and surface properties of AGS. The results of the operation on water quality of the effluent showed that the average concentration of total organic carbon, suspended solids, nitrogen, and phosphorus was 6.89 mg/L, 7.33 mg/L, 7.33 mg/L, and 0.2 mg/L, respectively. All these concentrations complied the effluent standard in Korea. The concentration of mixed liquor suspended solid (MLSS) fluctuated, but the AGS/MLSS ratio was constant at 86.5±1.3%. Although the AGS/MLSS ratio was constant, sludge volume index improved. These results suggested that the particle discharged fine sludge and increased the AGS praticle size in the AGS. Optical microscopy revealed the presence of dense AGS at the end of the operation, and particles of > 0.6 mm were found. Compared to those of belt-type AGS separator, the required area and power consumption of the hydrocyclone-type AGS separator were reduced by 27.5% and 83.8%, respectively.

• Journal of Environmental Science International
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• v.30 no.12
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• pp.1081-1092
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• 2021

In this study, the effect on the stability of Aerobic Granular Sludge (AGS) caused by an AGS separator was investigated. The AGS separator was a hydrocyclone. The main factors of the AGS separator were filter pore size (0.125~0.600 mm), conical-to-cylindrical ratio (1.5~3.0), and operating time (1~20 min). The AGS/mixed liquor suspended solid (MLSS) ratio gradually increased to 0.500 mm (AGS/MLSS: 84.3±3.0%). AGS was best separated at the conical-to-cylindrical ratio of 2.5 (AGS/MLSS: 84.7±3.3%). As the operating time increased, the AGS separation performance also tended to increase. The shortest AGS separator run time, but the highest AGS separation performance was 10 min (87.0±2.5%). AGS stability was evaluated by operating the selected AGS separator and sequencing batch reactor. The average removal efficiencies of TOC, TCOD_Cr, SS, TN, and TP were 95.7%, 96.9%, 93.0%, 89.0%, and 96.2%, respectively, which met the effluent standards in Korea. In addition, the AGS/MLSS ratio tended to remain constant, and the sludge volume index demonstrated a tendency to decrease from 140 mL/g to 70 mL/g. During the operation, the particles of AGS in optical microscope observations gradually increased.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.202-204
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• 2021

The Internet of Things (IoT) is a term first used by Kevin Ashton, director of MIT's Auto ID Center, in 1999, and refers to the connection of things to the Internet. Bluetooth, one of the wireless networks, is a technology developed as an industry standard for personal short-range wireless communication first developed by Ericsson in 1994. Since the Raspberry Pi has Bluetooth built-in, a wireless network is possible. This paper implements a module for the Internet of Things by implementing serial communication in the Bluetooth built-in Raspberry Pi 3 B+. There was a problem that Bluetooth communication was impossible between raspberries, so the discovery function was activated and serial communication was added to successfully link the communication.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.25-27
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• 2006

블루투스는 무선 홈 네트워킹을 구성하는 하나의 기술로 자리를 잡았지만, 기존의 홈 네트워킹을 구성하는 IRDA, 무선랜, Home RF, ZigBee 등에 비하여 블루투스 사용으로 인한 큰 이득이 없어 이용되지 않는 것이 현재 블루투스가 직면한 문제이다. 비슷한 통신반경을 지원하는 IRDA와 비교하면 가격과 전력소비에서 블루투스의 이점이 떨어지고, 다중 연결을 지원하는 장점에도 불구하고 10m 내의 전송 반경으로는(저 전력 사용 시) 집안을 전부 커버할 수 없기 때문에 무선랜에 비해 홈 네트워킹에서 이용성이 떨어지는 것이 사실이다. 하지만 이런 블루투스의 AD-HOC 라우팅을(1:1 혹은 1:다) 위한 블루투스 프로토콜 스택에 라우팅 프로토콜 스택을 추가함으로써 블루투스가 장착된 정보 가전기기는 주변으로부터 라우팅 정보를 수집하게 되고 라우팅 테이블을 구성할 수 있게 된다. 그러므로 전송 범위의 이상적인 설계에서 무선랜보다 넓어지게 되므로 홈 네트워킹에서 블루투스 사용의 단점이 보안됨은 물론 집안을 하나의 WEB처럼 구성할 수 있게 된다. 이에 다른 기술에 비한 저렴한 가격, 접속의 용이성, 저 전력 소비 둥과 같은 기존의 장점에 전송 거리의 단점이 보안된 블루투스 라우팅 프로토콜 기술은 IRDA, 무선랜보다 기술적 우위를 가짐으로써 홈 네트워킹에 적용이 많아지리라 예상할 수 있다. 더 나아가 블루투스 기술이 포함되어 있는 모바일 기기가 정점 늘어남에 따라 모바일 기기와의 연동에 의한 홈 네트워킹이 실생활에 적용되리라 예측되며, 집뿐만 아니라 어디에서나 다른 모바일 기기와 연결되어 네트워크를 이루는 유비쿼터스 네트워킹이 실현 될 수 있으리라 본다.-filtered CU)과는 비슷한 결과를 보였다. 결과적으로 제안된 방법은 전통적인 켑스트럴 평균 차감법에 기반하여 효과적인 채널 정규화가 가능하다는 것을 보였다.ttention since the operation of local autonomy in Korea. This trend focuses on ′visual landscape planning′, and it is expected to grow drastically in the near future. Therefore, it is recommended that we promote the more elaborate methodology of ′visual landscape planning′, which also includes the ecological and cultural aspects of the environment. 7월 시료에는 ethane, ethyl formate, trans-2-hexenal의 순서로 그 함량이 많았으며, hydrocarbon류가 전체성분의 30.42%를 차지하였다. 8월 시료는 benzyl alcohol, ethyl formate 및 trans-2-hexenal의 순서로 많이 함유되어 있었으며, ester류가 35.60%를 차지하였다. 또한 9월 시료에도 ester류가 32.92%를 차지하였으며 ethyl acetate, benzyl alcohol, ethane 및 trans-2-hexenal의 순서로 함량이 높았다.to isolate the major component of silkworm powder, which exerts blood glucose-lowering e

• Weed & Turfgrass Science
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• v.3 no.4
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• pp.370-377
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• 2014

Research was initiated to evaluate cool-season grass (CSG) overseeding effects on coverage and species transition in Korean lawngrass (Zoysia japonica Steud.) and to determine CSGs and their seeding rate for a practical overseeding. Treatments were comprised of Kentucky bluegrass (KB, Poa pratensis L.), perennial ryegrass (PR, Lolium perenne L.), tall fescue (TF, Festuca arundinacea Schreb.) and their mixtures. Significant differences were observed in turfgrass coverage and species transition. Since overseeding, the coverage was highest in PR, followed by TF and lowest in KB. The highest coverage in polystand was associated with Mixture IV (TF 50 + PR 50) at a seeding rate of $150gm^{-2}$ which had highest PR and TF, but without KB. Regarding turfgrass transition, zoysiagrass recovery continued to come back up to 80% from late March. But it reduced after early October. Zoysiagrass in monostand was greatest in KB and lowest in TF, but variable in polystand. For the fast and great coverage in winter, it would be the best to apply with PR at $100gm^{-2}$ and equal combination of PR and TF by 1/2 in the mixture at $150gm^{-2}$. For the smooth spring transition to zoysiagrass, however, KB application at $50gm^{-2}$ is recommended.