• 한국결정성장학회지
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• 제18권6호
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• pp.232-236
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• 2008

최근 실리콘 원료의 부족에 따른 가격상승으로 인하여 99.9999% 이상의 순도를 지닌 폴리 실리콘을 더 저렴하게 제조하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 순도 99%의 금속급 실리콘(MG-Si)을 원료로 산처리와 일방향 응고를 통해 고순도로 정제하는 연구를 수행하였다. MG-Si 럼프를 플레너터리 밀로 분쇄한 후 HCl/$HNO_3$/HF 산 수용액에서 처리하였다. 그 결과 Al, Fe, Ca, Mn 등과 같은 금속 불순물들의 실리콘 내 함량이 크게 감소하면서 실리콘의 순도는 99.995%까지 향상되었다. 정제된 실리콘 분말을 성형한 후 HEM로를 이용하여 용융시킨 뒤, 일방향 응고를 통하여 잉곳을 제조하였다. 성장시킨 다결정 실리콘 잉곳은 $0.3{\Omega}{\cdot}cm$의 비저항과 $3.8{\mu}{\cdot}sec$의 열 운반자 소멸시간(minority carrier life time)을 나타내었다.

• Journal of Dairy Science and Biotechnology
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• 제24권1호
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• pp.53-63
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• 2006

Nano and micro capsulation (NM capsulation) involve the incorporation for nanofood materials, enzymes, cells or other materials in small capsules. Since Kim D. M. (2001) showed that a new type of food called firstly the name of nanofood, which means nanotechnology for food, and the encapsulated materials can be protected from moisture, heat or other extreme conditions, thus enhancing their stability and maintaining viability applications for this nanofood technique have increased in the food. NM capsules for nanofood is also utilized to mask odours or tastes. Various techniques are employed to form the capsules, including spray drying, spray chilling or spray cooling, extrusion coating, fluidized bed coating, liposome entrapment, coacervation, inclusion complexation, centrifugal extrusion and rotational suspension separation. Each of these techniques is discussed in this review. A wide variety of nanofood is NM capsulated - flavouring agents, acids, bases, artificial sweeteners, colourants, preservatives, leavening agents, antioxidants, agents with undesirable flavours, odours and nutrients, among others. The use of NM capsulation for sweeteners such as aspartame and flavors in chewing gum is well known. Fats, starches, dextrins, alginates, protein and lipid materials can be employed as encapsulating materials. Various methods exist to release the ingredients from the capsules. Release can be site-specific, stage-specific or signaled by changes in pH, temperature, irradiation or osmotic shock. NM capsulation for the nanofood, the most common method is by solvent-activated release. The addition of water to dry beverages or cake mixes is an example. Liposomes have been applied in cheese-making, and its use in the preparation of nanofood emulsions such as spreads, margarine and mayonnaise is a developing area. Most recent developments include the NM capsulation for nanofood in the areas of controlled release, carrier materials, preparation methods and sweetener immobilization. New markets are being developed and current research is underway to reduce the high production costs and lack of food-grade materials.

• Journal of Microbiology and Biotechnology
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• 제25권3호
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• pp.366-374
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• 2015

Herein, we established a repeated-batch process for ethanol production from glycerol by immobilized Pachysolen tannophilus. The aim of this study was to develop a more practical and applicable ethanol production process for biofuel. In particular, using industrial-grade medium ingredients, the microaeration rate was optimized for maximization of the ethanol production, and the relevant metabolic parameters were then analyzed. The microaeration rate of 0.11 vvm, which is far lower than those occurring in a shaking flask culture, was found to be the optimal value for ethanol production from glycerol. In addition, it was found that, among those tested, Celite was a more appropriate carrier for the immobilization of P. tannophilus to induce production of ethanol from glycerol. Finally, through a repeated-batch culture, the ethanol yield (Y_e/g) of 0.126 ± 0.017 g-ethanol/g-glycerol (n = 4) was obtained, and this value was remarkably comparable with a previous report. In the future, it is expected that the results of this study will be applied for the development of a more practical and profitable long-term ethanol production process, thanks to the industrial-grade medium preparation, simple immobilization method, and easy repeated-batch operation.

• 한국전기전자재료학회논문지
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• 제24권6호
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• pp.433-439
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• 2011

Poly Si TFTs (poly silicon thin film transistors) with p channel those are annealed HT (high temperature) with gate poly crystalline silicon and LT (low temperature) with metal gate electrode were fabricated on quartz substrate using the analyzed data and compared according to the activated grade silicon thin films and the size of device channel. The electrical characteristics of HT poly-Si TFTs increased those are the on current, electron mobility and decrease threshold voltage by the quality of particles of active thin films annealed at high temperature. But the on/off current ratio reduced by increase of the off current depend on the hot carrier applied to high gate voltage. Even though the size of the particles annealed at low temperature are bigger than HT poly-Si TFTs due to defect in the activated grade poly crystal silicon and the grain boundary, the characteristics of LT poly-Si TFTs were investigated deterioration phenomena those are decrease the electric off current, electron mobility and increase threshold voltage. The results of transconductance show that slope depend on the quality of particles and the amplitude depend on the size of the active silicon particles.

• 에너지공학
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• 제23권3호
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• pp.235-240
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• 2014

본 연구에서는 음식물쓰레기를 반탄화 하여 생성된 생성물의 특성 및 온도에 대한 영향을 비교하여 연료화 가능성을 파악하고자 하였다. 반응온도를 $180^{\circ}C{\sim}270^{\circ}C$ 조절하고 열전달방식을 질소가스 열전달방식과 열매체유 열전달방식으로 나누어 실험한 결과 생성물의 생산 수율과 수분함량은 온도가 높아짐에 따라 감소하였고 특히 $240^{\circ}C$이상에서는 수분감소 뿐만 아니라 열적변화도 확인 할 수 있었다. 반응온도가 낮을수록 열매체유 열전달방식이 수분감소에 더 좋은 열전달 효율을 보였지만 온도가 높아질수록 그 차이는 미미한 것을 확인할 수 있었다. 발열량의 경우 초기 660 Kcal/kg 에서 질소가스 열전달방식 6,400 Kcal/kg 간접방식 6,890 Kcal/kg 으로 상승 되었고, 원소분석결과 반응온도가 상승할수록 반탄화 생성물의 탄소원소의 함량증가와 산소원소 함량 감소를 확인 하였으며 석탄밴드 분석결과 저급석탄에 가까운 H/C와 O/C의 범위를 나타내었다. 음식물쓰레기를 반탄화를 통하여 연료개질이 가능하다는 것을 확인 할 수 있었으며, 반응온도가 높아질수록 저급석탄에 더 가까워짐을 확인할 수 있었다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권17호
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• pp.7085-7090
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• 2014

Objective: To make the clinical evaluation of a solid-state human papillomavirus (HPV) sampling medium in combination with an economical HPV testing method ($careHPV^{TM}$) for cervical cancer screening. Methods: 396 women aged 25-65 years were enrolled for cervical cancer screening, and four samples were collected. Two samples were collected by woman themselves, among which one was stored in DCM preservative solution (called "liquid sample") and the other was applied on the Whatman Indicating FTA $Elute^{(R)}$ card (FTA card). Another two samples were collected by physician and stored in DCM preservative solution and FTA card, respectively. All the samples were detected by $careHPV^{TM}$ test. All the women were administered a colposcopy examination, and biopsies were taken for pathological confirmation if necessary. Results: FTA card demonstrated a comparable sensitivity of detecting high grade Cervical Intraepithelial Neoplasia (CIN) with the liquid sample carrier for self and physician-sampling, but showed a higher specificity than that of liquid sample carrier for self-sampling (FTA vs Liquid: 79.0% vs 71.6%, p=0.02). Generally, the FTA card had a comparable accuracy with that of Liquid-based medium by different sampling operators, with an area under the curve of 0.807 for physician &FTA, 0.781 for physician &Liquid, 0.728 for self & FTA, and 0.733 for self &Liquid (p>0.05). Conclusions: FTA card is a promising sample carrier for cervical cancer screening. With appropriate education programmes and further optimization of the experimental workflow, FTA card based self-collection in combination with centralized $careHPV^{TM}$ testing can help expand the coverage of cervical cancer screening in low-resource areas.

• Journal of Communications and Networks
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• 제7권4호
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• pp.509-524
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• 2005

Due to the strict requirements of emerging applications, per-flow admission control is gaining increasing importance. One way to implement per-flow admission control is using an on­path resource reservation protocol, where the admission decision is made hop-by-hop after a new flow request arrives at the network boundary. The next-steps in signaling (NSIS) working group of the Internet engineering task force (IETF) is standardising such an on-path signaling protocol. One of the reservation methods considered by NSIS is reduced-state mode, which, suiting the differentiated service (DiffServ) concept, only allows per-class states in interior nodes of a domain. Although there are clear benefits of not dealing with per-flow states in interior nodes-like scalability and low complexity-, without per-flow states the handling of re-routed flows, e.g., after a failure, is a demanding and highly non-trivial task. To be applied in carrier-grade networks, the protocol needs to be resilient in this situation. In this article, we will explain the consequences of a route failover to resource reservation protocols: Severe congestion and incorrect admission decisions due to outdated reservation states. We will set requirements that handling solutions need to fulfill, and we propose extensions to reduced-state protocols accordingly. We show with a set of simulated scenarios that with the given solutions reduced-state protocols can handle re-routed flows practically as fast and robust as stateful protocols.

• ETRI Journal
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• 제34권2호
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• pp.199-209
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• 2012

In transport networks, a multi-ring architecture is very useful to facilitate network planning and to design and provide more resilient services for customers. Unlike traditional synchronous optical network multi-rings, the service resiliency of Ethernet-based multi-rings is significantly impacted by the ring hierarchy because a link or node failure in a certain level ring triggers filtering database flush actions in all higher level rings as well as in the ring with the failure, and consequently a large amount of duplicated data frames may be flooded. In this paper, we investigate how the ring hierarchy impacts the service resiliency of multi-ring networks. Based on extensive experiments on various single- and multiple-link failures, we suggest two effective inter-ring connection rules to minimize the transient traffic and to ensure more resilient multi-ring networks. In addition, we consider a flush optimization technique called e-ADV, and show that the combination of e-ADV and multi-ring structures satisfying our inter-ring connection rules results in a more attractive survivability performance.

• 한국정보통신학회논문지
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• 제16권5호
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• pp.899-905
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• 2012

FMCW 레이더 방식의 레벨게이지는 비 접촉성, 원거리 계측과 다양한 형상으로 구현이 가능한 장점 때문에 많은 연구와 개발이 되어왔으나 cm급의 고 해상도를 얻기 위해서는 GHz의 넓은 대역폭이 필요한 단점이 있다. 본 논문에서는 협대역 시스템으로 광대역 성능을 얻을 수 있는 톱니파 형태의 송신 파형을 제안하였다. 이 방식은 STFT(Short-time fourier transform)로 짧은 구간으로 나누어 처리하고 단일 정현파의 주파수 추정 알고리즘으로 해상도를 개선하고 있으며 실험을 통하여 300MHz의 FMCW레이더에서 8배까지 거리해상도가 개선되는 것을 보였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.323-323
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• 2010

Saw damage of crystalline silicon wafer is unavoidable factor. Usually, alkali treatment for removing the damage has been carried out as the saw damage removal (SDR) process for priming the alkali texture. It usually takes lots of time and energy to remove the sawed damages for solar grade crystalline silicon wafers We implemented two different mixed acidic solution treatments to obtain the improved surface structure of silicon wafer without much sacrifice of the silicon wafer thickness. At the first step, the silicon wafer was dipped into the mixed acidic solution of $HF:HNO_3$=1:2 ration for polished surface and at the second step, it was dipped into the diluted mixed acidic solution of $HF:HNO_3:H_2O$=7:3:10 ratio for porous structure. This double treatment to the silicon wafer brought lower reflectance (25% to 6%) and longer carrier lifetime ($0.15\;{\mu}s$ to $0.39\;{\mu}s$) comparing to the bare poly-crystalline silicon wafer. With optimizing the concentration ratio and the dilution ratio, we can not only effectively substitute the time consuming process of SDR to some extent but also skip plasma enhanced chemical vapor deposition (PECVD) process. Moreover, to conduct alkali texture for pyramidal structure on silicon wafer surface, we can use only nitric acid rich solution of the mixed acidic solution treatment instead of implementing SDR.