• International Journal of Knowledge Content Development & Technology
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• 제12권1호
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• pp.35-47
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• 2022

This study adopted the descriptive survey research method. The population of this study comprised of the hearing impaired students in selected government secondary schools in Rivers state. The population of hearing impaired students in Rivers State is 257. A simple random sampling technique was used to select a sample size of 159. A self-developed instrument titled "Availability and Utilization of Library Information Resources Questionnaire (AULIRQ)" was utilized for data collection. 153 responses were collated, indicating a 96.2% response rate. The data collected was arranged and analyzed using frequency count, percentages, and mean and standard deviation. Finding reveals that information resources in the libraries understudied were inadequate and under-utilized. Also, it was established that among other barriers, under-funding is a major barrier to making information resources available for the physically challenged. It was recommended that schools offering special education for the hearing impaired should pace up in their developmental gap by providing such resources and ensure adequate funding by all stakeholders.

• 자원리싸이클링
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• 제27권6호
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• pp.3-10
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• 2018

텅스텐은 고융점금속으로 주로 초경합금으로 사용되고 있다. 알칼리용액에서 텅스텐은 $WO{_4}^{2-}$로 존재하는데 용액의 pH가 감소함에 따라 중합반응이 일어나며 텅스텐산으로 침전된다. 따라서 원광석 및 2차 자원으로부터 텅스텐 회수를 위한 습식 제련 기술은 산침출과 알칼리침출로 대별된다. 2차 자원에 함유된 금속의 종류와 함유량 및 텅스텐의 소재화를 고려해서 2차 자원으로부터 텅스텐을 고순도로 회수하기 위한 공정을 선택해야 한다.

• 컴퓨터교육학회논문지
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• 제10권4호
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• pp.103-112
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• 2007

본 연구는 교육정보화 사업을 통해 현재까지 보급된 초 중등학교 하드웨어, 소프트웨어에 대하여 문제점을 분석하고 교육정보자원 운영의 내실화 방안을 제시하는 것을 목적으로 한다. 관련된 문제를 규명하고 내실화를 위한 방안들을 도출해 내기 위해서 본 연구에서는 관련된 이전의 연구자료를 분석하고 설문 조사를 통하여 학교에서 교육 정보 자원의 사용에 대한 현 상태를 조사하였으며 학교 현장 및 국내 유관 부처를 방문하여 면담을 실시하였다. 이를 바탕으로 초 중등학교 교육정보자원 운영의 내실화 방안을 제시하였다. 본 연구의 결과를 통해 산출된 교육정보자원 운영의 내실화 방안들이 초 중등학교 및 정부부처에서 관련 정책을 수립하고 집행하는데 있어 유용한 자료로 활용되기를 기대한다.

• 한국항행학회논문지
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• 제24권2호
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• pp.121-127
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• 2020

본 논문에서는 광대역 스펙트럼 인지 무선망에서 인지사용자의 요구자원의 크기에 따라 스펙트럼 홀의 그룹핑 범위를 변화시키는 동적 스펙트럼 홀 그룹핑 방식을 제안하고, 광대역 인지사용자의 서비스를 위한 채널할당에 적용한다. 제안한 동적 스펙트럼 홀 그룹핑 방식은 인지사용자의 요구자원의 크기를 예측하여 필요한 양 만큼 주사용자의 스펙트럼 홀을 그룹핑함으로써 기존의 정적 스펙트럼 홀 그룹핑에 의해 발생 할 수 있는 스펙트럼 자원의 낭비를 개선 할 수 있다. 시뮬레이션을 통하여 동적 스펙트럼 홀 그룹핑 방식과 기존의 정적 스펙트럼 홀 그룹핑 방식에 의한 채널할당의 자원사용률을 비교하여, 허용할 수 있는 인지사용자의 서비스 성능에서 자원이용률을 크게 향상시킬 수 있음을 보인다.

• 한국입자에어로졸학회지
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• 제15권4호
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• pp.127-137
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• 2019

Recently, high electrochemical performance anode materials for lithium ion secondary batteries are of interest. Here, we present silicon-carbon-graphene (Si-C-GR) composites for high performance anode materials of lithium ion secondary battery (LIB). Aerosol process and heat-treatment were employed to prepare the Si-C-GR composites using a colloidal mixture of silicon, glucose, and graphene oxide precursor. The effects of the size of the silicon particles in Si-C-GR composites on the material properties including the morphology and crystal structure were investigated. Silicon particles ranged from 50 nm to 1 ㎛ in average diameter were employed while concentration of silicon, graphene oxide and glucose was fixed in the aerosol precursor. Morphology of as-fabricated Si-C-GR composites was generally the shape of a crumpled paper ball and the Si particles were well wrapped in carbon and graphene. The size range of composites was about from 2.2 to 2.9 ㎛. The composites including silicon particles larger than 200 nm in size exhibited higher performance as LIB anodes such as capacity and coulombic efficiency than silicon particles less than 100 nm, which were about 1500 mAh/g at 100 cycles in capacity and 99% in coulombic efficiency, respectively.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2022년도 추계학술대회
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• pp.105-105
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• 2022

Unripen mandarin in Jeju Island is known to contain functional ingredients including various flavonoids. This Study was carried out to identify the components of Unripen mandarin extracts and Secondary metabolism by enzyme treatment on Unripen mandarin. We extracted Unripen mandarin using optimal extraction method and selected the most optimal enzyme among commercial enzymes for a Secondary metabolism. As a result, flavonoid components such as Hesperidine and Narirutin, which are known to be contained a lot in unripen mandarin, could be analyzed. However In this extraction method there were no other flavonoid components such as Nobiletin, Tangeretin known to contain in unripen mandarin. However as a result of secondary metabolism a new functional component called Prunin which was not known to be contained in unripen mandarin, was detected as a secondary metabolic product due to enzyme treatment. Through this, it can be confirmed that it would be possible to develop high-value-added products by enzyme treatment on unripen mandarin.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.3-8
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• 2001

The mineral industry of the United States is going through a challenging time. The US as an industrial nation faces with increasing demand in raw materials to fuel various industrial sectors but, at the same time, meeting environmental constraints associated with excavating and extracting these raw materials. In addition, gradual depletion of material resources. and the necessity of handling more complex forms of resources of primary origin have led to a decline in her resource productivity, once a strategic advantage of the U.S. As a result. the United States currently relies heavily upon foreign importation of various materials such as precious and strategic metals. However, since the US is the major consumer of most of these materials, the recovery of these values from scrap would help renew her position as a resource-producing nation, and ultimately help spur its domestic economy. Furthermore. recycling would also help maintain a clean environment and reduce energy consumption. In this paper. the author attempts to discuss opportunities and challenges lied ahead of the US mineral in relation to recovering their much-needed resources from secondary sources. The need and demand in various metals in the US will be reviewed and discussed. The implication of resource recovery from secondary sources will also be discussed. Extraction methods treating secondary sources are inherently different from those for primary sources. There is a need for new technologies which are metallurgically efficient and environmentally benign in treating secondary sources. Ways to meet such a need will be examined and key factors to be considered in approaching these challenges will be discussed.

• 자원리싸이클링
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• 제22권2호
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• pp.3-10
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• 2013

인듐은 희유금속으로 주로 ITO제조에 사용된다. 본 총설에서는 인듐을 함유한 2차자원을 침출한 용액으로부터 인듐을 분리하기 위한 용매추출, 이온교환 및 석출법에 대한 공정 조건 및 장단점을 조사했다. 보통 정도의 산성용액에서 인듐의 추출제로 D2EHPA가 가장 많이 사용되고 있으며, 매우 강한 염산용액에서는 아민계 추출제가 사용된다. 일반적으로 이온교환수지의 인듐 흡착량이 낮으므로, 인듐의 농도가 낮은 경우에 한해 이온교환은 용매추출보다 장점이 있다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 추계학술대회
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• pp.23-23
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• 2018

Taiwan, formerly known as Formosa, located on tropical and subtropical climate zones with abundant biological resources. According to the latest version of the Flora of Taiwan, there are 4339 species of vascular plants including 1054 endemic species. First, Taiwania (Taiwania cryptomerioides), named after its native island of Taiwan, have been isolated more than 500 secondary metabolites, including lignans, terpenoids, steroids, and flavonoids. Several of the metabolites are reported to have antibacterial, antifungal, antimite, antitermite and antitumor activities. In order to investigate plant secondary metabolic diversity toward industrial applications, we established deep transcriptome resources for non-model plants and fungi to produce terpenoid metabolites of economic importance. Second, many plants of Lauraceae have been utilized in folk medicine for their exciting bioactivities. The twigs and leaves from 27 tree species of Lauraceae grown in Taiwan were performed to evaluate potential bioactivity. The leaves of Cinnamomum osmophloeum are traditionally used in folk medicines, and many biological activities have been identified, such as antibacterial, antifungal, antitermite, antidiabetic, antihyperuricemia, antiinflammatory, and antioxidant activities. However, C. osmophloeum has nine chemotypes with various secondary metabolite profiles. In order to efficiently produce active compounds, we established the genetic markers to identify the chemotype plants. Finally, Cinnamomum kanehirae is the host of the medicinal mushroom Antrodia cinnamomea. Several in vivo and in vitro studies indicated that A. cinnamomea possesses a diverse range of biological activities. Because of the potential pharmacological application, we established the transformation system to enhance the triterpenoid contents production.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.381-385
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• 2004

본 인구에서는 레이놀즈응력모형을 이용하여 직사각형 개수로 흐름을 수치모의 하고 이차흐름의 생성 메커니즘을 제시하였다. 수치모의 결과 자유수면과 측벽의 접합부 근처에서 inner secondary flow가 발생하였다. 이는 최근 Grega 등(1995)과 Hsu 등(2000)에 의해 밝혀진 새로운 이차흐름이다. 또한 측벽에서의 전단력 분포를 계산한 결과 inner secondary flow에 의하여 수면 근처에서의 전단력 값이 증가하는 것으로 나타났다. 계산된 결과를 이용하여 와도 방정식에서 각 항의 크기를 비교하여 이차 흐름의 생성 메커니즘을 살펴보았다. 그 결과 벽 및 측벽 경계 부근에서는 난류의 비등방성에 의한 와도 생성항에 의해 이차 흐름이 생성되고, 경계와 멀리 떨어진 영역에서는 레이놀즈응력에 의한 와도 생성항이 이차흐름을 생성시키는데 중요한 역할을 하는 것으로 나타났다.