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Yokimiko David,Mary Grace Baylon,Sudheer D. V. N. Pamidimarri,Kei-Anne Baritugo,채철기,김유진,김태완,김민식,나정걸,박시재 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.2
Coal is one of the major sources of energy, fuel, and other related chemicals. The processes to utilize coal for energy, fuel and other chemicals such as coal combustion, liquefaction, carbonization, and gasification pose a great threat to the environment by emitting toxic particles and CO2 to the atmosphere. Thus, biological beneficiation of coal can be a good strategy to utilize coal with environmental sustainability. Here, we report the screening of microorganisms able to degrade or depolymerize coal. These host strains are potential candidates for the development of biological treatment process of coal. A total of 45 microbial strains were isolated from sludge enriched with coal and were identified based on 16S rRNA sequencing. Four strains of three genera, Cupriavidus sp., Pseudomonas sp., and Alcaligenes sp., were further characterized for their abilities to degrade coal. The degree of coal degradation was analyzed by measuring the increase in absorbance at 450 nm by UV spectroscopy. These microorganisms were also able to increase the pH of the culture media as a response to the acidic nature of coal. Laccase-like activity was also found in these strains when tested for RBBR dye degradation. Since biological degradation of coal through the use of microorganisms is a good alternative to chemical combustion of coal, microbial strains isolated in this study can be potential biological catalysts for coal conversion into valuable chemicals.
John Thornton,David Grace 한국전자통신연구원 2004 ETRI Journal Vol.26 No.5
In a High Altitude Platform (HAP) cellular communications network, each cell may be served by a dedicated spot-beam antenna. The antennas’ beam properties and their spatial overlap control the co-channel interference. In prior literature, radiation patterns have been approximated by a main lobe followed by a constant sidelobe floor. A network of 121 cells has been studied and the method is here extended to the use of more realistic radiation patterns based on the theoretical aperture antenna patterns. This allows for the comparison of the effect of different aperture field tapers, which lead to reduced sidelobe levels and hence higher system capacity but also a more massive antenna payload.
Experimental Study of Capture Effect for Medium Access Control with ALOHA
Selahattin Kosunalp,David Grace,Tim Clarke 한국전자통신연구원 2015 ETRI Journal Vol.37 No.2
In this paper, we investigate the capture effect through experiments conducted with Iris nodes equipped with AT86RF230 radio transceivers. It is shown that the first arriving packet in a collision can capture the radio channel for equal power transmissions and may be decoded depending on the amount of overlap. A new 3-packet-capture scenario is introduced and implemented. To be able to understand the impact of capture on the throughput performance of wireless sensor networks, we present an analysis of the capture coefficient using our practical results. For real-world implementations, the throughput of pure ALOHA considering a finite number of users is presented in analytical form. The capture coefficient is then applied to pure ALOHA as a case study. Using analytical and practical implementations of the capture effect on ALOHA, a very good match in channel throughput performance enhancement is demonstrated over the non-capture effect case. TinyOS-2.x is used to program the nodes and to observe data exchange on a computer through a base station.
( Ju Hyun Oh ),( Grace Hyun J. Kim ),( David W Dai ),( S Sam Weigt ),( Jonathan G Goldin ),( Lila Pourzand ),( Jooae Choe ),( Fereidoun Abtin ),( Matthew S. Brown ),( Pangyu Teng ),( Jin Woo Song ) 대한결핵 및 호흡기학회 2021 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.129 No.-
Background Interstitial lung disease (ILD) includes a heterogeneous group of disease entities. Idiopathic pulmonary fibrosis (IPF) is ultimately fatal, and accurate diagnosis of IPF is critical to clinical decision making. Visual interpretation of chest high resolution CT (HRCT) is subjective and has limited reproducibility, especially with early disease. So we have previously developed attention-gated deep learning algorithm to diagnosis IPF and machine learning to predict IPF progression. The overall aim of IS-IPF is to collect the data from two centers of excellence and evaluate the robustness of the algorithm. We present the preliminary data of the patients studied following disease classification by the multidisciplinary review committees (MDCs) at UCLA and Asan Medical Center (AMC). Methods The IS-IPF study plans to include 234 IPF and 266 non-IPF cases from two large ILD centers (UCLA and AMC). Eligible patients were evaluated in ILD MDC, were >18 years old, had a HRCT, pulmonary function testing, and a committee diagnosis of IPF or non-IPF. Relevant demographic information was collected from the medical record. Results Total 185 IPF and 266 non-IPF patients’ HRCT images have been collected in the IS-IPF study. By center, 51 IPF and 133 non- IPF patients’ HRCT were collected from UCLA, and 134 IPF and 133 non-IPF patients’ HRCT were collected from AMC. On MDC diagnosis, non-IPF cohorts consisted of 33% hypersensitivity pneumonitis, and 67% other connective tissue disease-ILD. Mean age was 61 years (63 IPF and 58 non-IPF), and 63% were male (82% IPF and 57 % non-IPF). Up to date, the predicted FVC was 74.7% and the predicted DLco was 61.6 % in the IPF cohort. Data collection is on-going. Conclusions These well-characterized cohorts will be used to evaluate HRCT image signatures for distinguishing IPF from other ILD, and predicting patient-specific IPF progression within 2 years of diagnosis.
Spectrum Sharing between High Altitude Platforms and Other Services in Ka-band
Oodo, Masayuki,Miura, Ryu,Grace, David 통신위성우주산업연구회 2005 Joint Conference on Satellite Communications Vol.2005 No.-
This paper addresses spectrum sharing issues with regard to High Altitude Platform (HAP)-based fixed service (FS) using Ka band (28/31 GHz). Currently, several strict restrictions have been imposed by the Radio Regulations on the use of the 28/31 GHz bands for the HAP-based FS because of concerns that the HAP-based FS could interfere in other services using the same-adjacent frequency bands. To facilitate the spectrum sharing/compatibility, this paper proposes a new HAP system model different from the model used in the current ITU-R study. Although the service coverage of the proposed HAP model is narrower than the current one, this model results in less interference from/to other services compared with the current model. This paper also deals with radiation patterns of HAP antennas which play an important roll in the interference evaluation. Measured radiation patterns of prototype HAP antennas are compared with the reference patterns which have been used in the ITU-R study. Good performance of the measured patterns is shown.
Practical Implementation and Stability Analysis of ALOHA-Q for Wireless Sensor Networks
Selahattin Kosunalp,Paul Daniel Mitchell,David Grace,Tim Clarke 한국전자통신연구원 2016 ETRI Journal Vol.38 No.5
This paper presents the description, practical implementation, and stability analysis of a recently proposed, energy-efficient, medium access control protocol for wireless sensor networks, ALOHA-Q, which employs a reinforcement-learning framework as an intelligent transmission strategy. The channel performance is evaluated through a simulation and experiments conducted using a real-world test-bed. The stability of the system against possible changes in the environment and changing channel conditions is studied with a discussion on the resilience level of the system. A Markov model is derived to represent the system behavior and estimate the time in which the system loses its operation. A novel scheme is also proposed to protect the lifetime of the system when the environment and channel conditions do not sufficiently maintain the system operation.
미니총설 : 바이오플라스틱 생산 미생물 플랫폼 제작을 위한 대사공학 전략 개발
박시재 ( Si Jae Park ),요키미코데이비드 ( Yokimiko David ),메리그레이스베일런 ( Mary Grace Baylon ),홍순호 ( Soon Ho Hong ),오영훈 ( Young Hoon Oh ),양정은 ( Jung Eun Yang ),최소영 ( So Young Choi ),이승환 ( Seung Hwan Lee ),이상엽 ( Sang 한국공업화학회 2014 공업화학 Vol.25 No.2
환경오염, 기후변화, 고갈되어가는 화석원료에 대한 문제를 해결하기 위해 재생가능한 자원으로부터 케미칼 및 고분자 등의 산업자원을 생산하는 친환경 공정개발에 많은 연구가 진행되고 있다. 최근에 재생가능한 바이오매스로부터 다양한 케미칼 및 고분자 등을 생산하는 바이오리파이너리 공정이 많은 관심을 받고 있으며, 석유화학기반산업을 보완 혹은 대체할 가능성이 매우 높은 친환경공정으로 생각되고 있다. 본 총설에서는 바이오리파이너리 공정에 핵심적인 촉매로 사용되고 있는 재조합 미생물의 개발의 최근 동향을 바이오나일론, 바이오폴리에스터의 생산을 위하여 개발되고 있는 재조합 미생물의 대사공학전략을 중심으로 살펴보고자 한다. As the concerns about environmental problems, climate change and limited fossil resources increase, bio-based production of chemicals and polymers from renewable resources gains much attention as one of the promising solutions to deal with these problems. To solve these problems, much effort has been devoted to the development of sustainable process using renewable resources. Recently, many chemicals and polymers have been synthesized by biorefinery process and these bio-based chemicals and plastics have been suggested as strong candidates to substitute petroleum-based products. In this review, we discuss current advances on the development of metabolically engineered microorganisms for the efficient production of bio-based chemicals and polymers.