• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.416-423
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• 2009

High-temperature steam electrolysis (HTSE) using solid oxide cell is a challenging method for highly efficient large-scale hydrogen production as a reversible process of solid oxide fuel cell (SOFC). The overall efficiency of the HTSE hydrogen and synthesis gas production system was analyzed thermo-electrochemically. A thermo-electrochemical model for the hydrogen and synthesis gas production system with solid oxide electrolysis cell (SOEC) and very high temperature gas-cooled reactor (VHTR) was established. Sensitivity analyses with regard to the system were performed to investigate the quantitative effects of key parameters on the overall efficiency of the production system. The overall efficiency with SOEC and VHTR was expected to reach a maximum of 58% for the hydrogen production system and to 62% for synthesis gas production system by improving electrical efficiency, steam utilization rate, waste heat recovery rate, electrolysis efficiency, and thermal efficiency. Therefore, overall efficiency of the synthesis production system has higher efficiency than that of the hydrogen production system.

• Annals of Clinical Neurophysiology
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• 제9권1호
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• pp.1-4
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• 2007

Vertigo is an illusion of rotation, which results from an imbalance within the vestibular system. This review focuses on two common presentations of spontaneous vertigo: acute prolonged spontaneous vertigo and recurrent spontaneous vertigo. Common causes of acute prolonged spontaneous vertigo include vestibular neuritis, labyrinthitis, and brainstem or cerebellar stroke. The history and detailed neurological/neurotological examinations usually provide the key information for distinguishing between peripheral and central causes of vertigo. Brain MRI is indicated in any patient with acute vertigo accompanied by abnormal neurological signs, profound imbalance, severe headache, and central patterns of nystagmus. Recurrent spontaneous vertigo occurs when there is a sudden, temporary, and largely reversible impairment of resting neural activity of one labyrinth or its central connections, with subsequent recovery to normal or near-normal function. Meniere's disease, migrainous vertigo, and vertebrobasilar insufficiency (VBI) are common causes. The duration of the vertigo attack is a key piece of information in recurrent spontaneous vertigo. Vertigo of vascular origin, such as VBI, typically lasts for several minutes, whereas recurrent vertigo due to peripheral inner-ear abnormalities lasts for hours. Screening neurotological evaluations, and blood tests for autoimmune and otosyphilis are useful in assessment of recurrent spontaneous vertigo that are likely to be peripheral in origin.

• 한국IT서비스학회지
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• 제12권3호
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• pp.151-163
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• 2013

It is no doubt that information technology is the key factor of national safety. Information technology is positively useful for national security such as crime prevention and detection, criminal investigation, disaster management, and national defense. However, it might be a threat to the security as we saw in the examples such as '3.4 DDoS attacks' and 'Nong-hyup Computer Network Failure.' Although the effect that information technology makes upon the national security is immense, the current legal system does not reflect these changes well. National security should be kept during 'prevention-response-recovery' process regardless it is in the online on offline. In addition, public administration for national security should be based on laws. However, the current legal system is lack of legislative basis on cyber and physical disaster, and the laws on the response to disaster might cause confusing. Therefore, this study examines the limitation of the current legal system on national security, and suggests directions for the development of the system based on the new establishment of the legal concept for 'national security'.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.89.1-89.1
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• 2011

According to green growth's policy, green-home dissemination's projects are promoting. Among them, stationary fuel cell systems are receiving attention due to high efficiency and clear energy. But it need absolutely to develop cost down technologies and improve system durability for commercialization of the fuel cell system. To achieve this objectives, in 2009, the Korean Government and "Korea Institute of Energy Technology Evaluation and Planning(KETEP)" launched into the strategic development project of BOP technology for practical applications and commercializations of stationary fuel cell systems, named "Technology Development on Cost Reduction of BOP Components for 1kW Stationary Fuel Cell Systems to Promote Green-Home Dissemination Project". This paper introduces a summary of improved BOP performances that has been achieved through the 2nd year development precesses(2010.06~2011.05) base on 1st year development precesses(2009.06~2010.05). The major elements for fuel cell systems are cathode air blowers, burner air blowers, preferential oxidation air blowers, fuel blowers, cooling water pumps, reformer water pumps, heat recovery pumps, mass flow meters, electrical valves, safety valves and a low-voltage inverter. Key targets of those elements are the reduction of cost, power consumption and noise. Invert's key targets are development the low -voltage technologies in order to reduce the number of unit cell in fuel cell system's stack.

• 한국수정란이식학회지
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• 제12권1호
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• pp.57-66
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• 1997

This study was carried out to establish an effective and practical system for commercialization of embryo production techniques by analyzing several factors influencing in vivo embryo production on days and seasons of flushing in Korean native cattle. In vivo embryos were flushed 226 times from 128 donors. The results obtained for the factors influencing in vivo embryo production on days and seasons of flushing were as follows :1.The percentages of fertilized, transferable and freezable embryos by seasons were significantly different in both FSR-P and SUPER-OV(P<0.01). The percentages of them were highest in sunrrner with FS H-P and highest in autumn with SUPER -OV.2. The production of transferable and freezable embryos by flushing days was highest in 8 days with FSH-P, and there was no difference between 7 and 8 days for SUP ER-OV. 3. The failure rates of recovery were 17.0% in SUPER-OV and 21.2% in FSH-P, respectively. The donors superovulated but failed recovery were 8.5% in SUPER-OV and 12.9% in FSH-P, respectively. Nonsuperovulated donors was 8.4% and donors giving less than 2 eggs at recovery was 8.4% in both FSH -P and SUPER-OV 4. The donors returned to normal estrus after superovulation were 34.1% after 1 cycle,39.4% after 2 cycles, and 16.7% after 3 cycles by FSH-P, respectively. For SUPER-OV, they were 55.3, 33.0 and 9.6%, respectively. Generally, normal estrus after the treatment of superovulation was earlier and the occurrence of ovarian cyst was also lower in SUP ER-OV than in FSH-P.5.The percentages of blastocyst in embryos flushed at 7~8 days after estrus were 21. 9% and 54.3% in FSH -P and SUPER-OV, respectively. The development of embryos was faster in SUPER-OV than in FSH-P.(Key words : in vivo embryo, flushing days, superovulation, FSH-P, SUPER-OV)

• Journal of Communications and Networks
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• 제12권4호
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• pp.289-307
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• 2010

The problem of model selection arises in a number of contexts, such as subset selection in linear regression, estimation of structures in graphical models, and signal denoising. This paper studies non-asymptotic model selection for the general case of arbitrary (random or deterministic) design matrices and arbitrary nonzero entries of the signal. In this regard, it generalizes the notion of incoherence in the existing literature on model selection and introduces two fundamental measures of coherence-termed as the worst-case coherence and the average coherence-among the columns of a design matrix. It utilizes these two measures of coherence to provide an in-depth analysis of a simple, model-order agnostic one-step thresholding (OST) algorithm for model selection and proves that OST is feasible for exact as well as partial model selection as long as the design matrix obeys an easily verifiable property, which is termed as the coherence property. One of the key insights offered by the ensuing analysis in this regard is that OST can successfully carry out model selection even when methods based on convex optimization such as the lasso fail due to the rank deficiency of the submatrices of the design matrix. In addition, the paper establishes that if the design matrix has reasonably small worst-case and average coherence then OST performs near-optimally when either (i) the energy of any nonzero entry of the signal is close to the average signal energy per nonzero entry or (ii) the signal-to-noise ratio in the measurement system is not too high. Finally, two other key contributions of the paper are that (i) it provides bounds on the average coherence of Gaussian matrices and Gabor frames, and (ii) it extends the results on model selection using OST to low-complexity, model-order agnostic recovery of sparse signals with arbitrary nonzero entries. In particular, this part of the analysis in the paper implies that an Alltop Gabor frame together with OST can successfully carry out model selection and recovery of sparse signals irrespective of the phases of the nonzero entries even if the number of nonzero entries scales almost linearly with the number of rows of the Alltop Gabor frame.

• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 1998년도 종합학술발표회논문집
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• pp.151-165
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• 1998

인터넷 전자상거래가 가속화 되면서 기업간 인터넷을 이용한 전자상거래가 증가하고 있다. Business-To-Business 유형의 전자상거래는 인터넷 EDI 또는 글로벌 비즈니스 개념이 도입되어 관련 기술의 연구개발이 활발히 진행중이며 상용화된 서비스가 일부 제공되고 있다. 기업간 전자상거래 시 기업내부 인력이 외부 즉, 거래 대상 기업 또는 경쟁 관계의 기업에 자사의 영업 및 기업 비밀을 제공하는 것은 명백한 범법 행위이다. 또한 인트라넷 내부 즉, 기업 내부망에 연동된 시스템을 사용하는 직원들이 정해진 근무시간에 다른 용도로 시스템 및 전산망 자원을 사용한다면 이 또한 회사 내부적으로 규제 대상이 되어야 한다. 특히, 일과외 시간에 공적 또는 사적인 용도 외에 사용자와는 전혀 관련 없는 전자우편 주소로 암호화된 문서를 송수신하였다면 기업 책임자는 기업의 시스템 및 전산망 자원을 업무 및 개인 용도 외적으로 사용한 의심스러운 행위에 대하여 확인할 권한이 있다고 본다. 본 논문은 기업간 전자상거래 수행 과정에서 기업 내부망 즉, 인트라넷에서 적용될 수 있는 보안 정책 중 키 복구 메커니즘이 적용될 수 있는 부분을 중심으로 새로운 키 복구 정책, 시나리오, 시스템 구성 및 키 복구 프로토콜을 제안한다.

• Membrane and Water Treatment
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• 제5권4호
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• pp.265-279
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• 2014

Pervaporation is the most promising technique for the recovery of ethanol from the fermentation system. To date, extensive research has been conducted on the exploration of membrane materials with favorable properties. In this paper, we primarily review the performance of adsorbent-filled rubbery membranes. In addition, the fundamental mechanisms of ethanol and water molecules transportation through composite membranes are demonstrated, particularly from the perspective of cluster formation. Finally, future prospects are also analyzed to develop the guidelines for the future development of excellent membrane materials for ethanol concentration. This paper is not meant to be an exhaustive overview, rather a specialized summary that allows readers to select the information appropriated to their topics.

• Journal of Magnetics
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• 제21권1호
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• pp.125-132
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• 2016

High gradient magnetic separation (HGMS) is the most commonly used magnetic cell separation technique in biomedical science. However, parameters determining target cell capture efficiencies in HGMS are still not well understood. This limitation leads to loss of information and resources. The present study develops a bead-capture theory to predict capture efficiencies in HGMS. The theory is tested with CD3- and CD14-positive cells in combination with paramagnetic beads of different sizes and a generic immunomagnetic separation system. Data depict a linear relationship between normalized capture efficiency and the bead concentration. In addition, it is shown that key biological functions of target cells are not affected for all bead sizes and concentrations used. In summary, linear bead-capture theory predicts capture efficiency ($E_t$) in a highly significant manner.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2013년도 추계학술발표대회
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• pp.864-867
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• 2013

키 복구 시스템은 1994년 미국 NIST의 키 복구 제품 EES 개발이후 많은 나라에서 활발한 연구가 이루어지고 있는 분야이다. 국내에서도 단일 키 복구 시스템부터 다중 키 복구 시스템을 바탕으로 다양한 키 복구 방식들이 제안되고 있다. 하지만 기존 방식은 단일, 다중 기관시스템에 있어서 낮은 안전성의 문제점을 가지고 있다. 본 논문에서는 기존의 키 복구 시스템을 분석하고 다중 키 복구 기관을 기반으로 키를 N개로 나누어서 분산 보관하며, 키 복구 기관의 기능 상실, 결탁 등 문제에도 키 복구가 가능하도록 설계 하였다. 또한 ElGamal 방식을 이용하여 키 위탁, 키 복구, 합법적인 감청 절차를 제안하였다.