• Journal of Microbiology and Biotechnology
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• 제26권12호
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• pp.2076-2086
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• 2016

Fungal cytochrome P450 (CYP) enzymes catalyze versatile monooxygenase reactions and play a major role in fungal adaptations owing to their essential roles in the production avoid metabolites critical for pathogenesis, detoxification of xenobiotics, and exploitation avoid substrates. Although fungal CYP-dependent biotransformation for the selective oxidation avoid organic compounds in yeast system is advantageous, it often suffers from a shortage avoid intracellular NADPH. In this study, we aimed to investigate the use of bacterial glucose dehydrogenase (GDH) for the intracellular electron regeneration of fungal CYP monooxygenase in a yeast reconstituted system. The benzoate hydroxylase FoCYP53A19 and its homologous redox partner FoCPR from Fusarium oxysporum were co-expressed with the BsGDH from Bacillus subtilis in Saccharomyces cerevisiae for heterologous expression and biotransformations. We attempted to optimize several bottlenecks concerning the efficiency of fungal CYP-mediated whole-cell-biotransformation to enhance the conversion. The catalytic performance of the intracellular NADPH regeneration system facilitated the hydroxylation of benzoic acid to 4-hydroxybenzoic acid with high conversion in the resting-cell reaction. The FoCYP53A19+FoCPR+BsGDH reconstituted system produced 0.47 mM 4-hydroxybenzoic acid (94% conversion) in the resting-cell biotransformations performed in 50 mM phosphate buffer (pH 6.0) containing 0.5 mM benzoic acid and 0.25% glucose for 24 h at $30^{\circ}C$. The "coupled-enzyme" system can certainly improve the overall performance of NADPH-dependent whole-cell biotransformations in a yeast system.

• 한국시스템다이내믹스연구
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• 제10권1호
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• pp.77-95
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• 2009

The ever-increasing government budget constraints have led to a continued decline in the increase rate for defense spending, and the government's 5-year National Fiscal Management Plan has served to reinforce the verification and validation procedures for the Force Improvement Programs (FIP) budget requirements and performance. Additionally, as large programs are controlled in accordance with the Total Program Cost Management Guidelines, timely and credible feasibility study and performance measurement need to be conducted. Due to these internal and external circumstances, needs have surged for feasibility and economic effectiveness study for big ticket projects in the FIP sector, with an increasing number of studies conducted by external research institutes. However, questions have been raised regarding the credibility and thoroughness of the program analyses performed by these research institutes due to various restrictions. This paper analyzes and identifies the structural limitations and problems using a systems thinking approach, and examines the systemic characteristics of the program analysis system. It also presents policy intervention recommendations based on the theory of systems thinking, a method to regularize and reinforce the program analysis system. Policy interventions recommended to ensure alignment of the external studies to the clear analysis objectives and resolve the bottlenecks in the external analysis include training those in charge of external study commissioning for a short term intervention, and increasing the number of research institutes and consulting agencies utilizing analysis and evaluation experts who transition to the private sector from the military for a long term intervention. additionally presented are strategies and policy alternatives to best utilize these policy interventions. They will contribute to the stable funding of Force Improvement Programs and efficient utilization of defense budget.

• 한국농림기상학회지
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• 제15권4호
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• pp.201-209
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• 2013

기후 변화로 인해 벼 병해충 예찰과 방제가 더욱 어려워지면서 주곡인 쌀의 생산량이 지속적으로 감소하고 있다. 이 연구에서는 그래프 이론을 적용하여 전국 시 군 지역을 대상으로 행정구역 단위의 벼 병원균 확산 공간 연결망을 정량적으로 분석하였다. 병원균 확산 연결망의 중추적 경로는 서해 연안의 행정구역 간에 연결된 링크들인 것을 확인할 수 있었다. 서해 연안 지역들은 병원균에 대한 경관 저항성이 매우 낮았고, 서해 연안의 핵심지역들과 경남 경북의 핵심지역들을 연결시키는 허브지역들을 도출할 수 있었다. 연구 결과를 통해 병원균 확산을 예측하고, 병원균이 발생하였을 때 확산을 방지하기 위해 우선적으로 방제되어야 하는 지역이 어디인지를 구분할 수 있었다. 연구결과는 병해충 방제 공동대응을 위한 행정구역 단위의 방제 구역 할당과 통합적인 병해충 관리계획 수립에 있어 유용한 농업환경지리 공간 자료로 활용될 수 있을 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권9호
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• pp.4398-4417
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• 2017

Multi-user Multiple-Input and Multiple-Output (MU-MIMO) has potential for prominently enhancing the capacity of wireless network by simultaneously transmitting to multiple users. User selection is an unavoidable problem which bottlenecks the gain of MU-MIMO to a great extent. Major state-of-the-art works are focusing on improving network throughput by using Channel State Information (CSI), however, the overhead of CSI feedback becomes unacceptable when the number of users is large. Some work does well in balancing tradeoff between complexity and achievable throughput but is lack of consideration of fairness. Current works universally ignore the rational utilizing of time resources, which may lead the improvements of network throughput to a standstill. In this paper, we propose TOUSE, a scalable and fair user selection scheme for MU-MIMO. The core design is dynamic-time-warping-based user selection mechanism for downlink MU-MIMO, which could make full use of concurrent transmitting time. TOUSE also presents a novel data-rate estimation method without any CSI feedback, providing supports for user selections. Simulation result shows that TOUSE significantly outperforms traditional contention-based user selection schemes in both throughput and fairness in an indoor condition.

• 한국의류학회지
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• 제26권11호
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• pp.1582-1592
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• 2002

The purpose of this study is to suggest production planning model for women's apparel manufacturer, which are relevant to the situation of Korean clothing industry. The research was based on simulation method. The basic model for the simulation was developed based on the empirical data from six production fm. After verifying the basic model, low alternative production plans went through trial run. In order to suggest the application of these alternative production plans for various style numbers and lot sizes, the simulation results were compared in terms of product efficiency and product cost. The four alternative plans were as follows: 1. The first alternative was to spread out work loads among workers in order to resolve bottlenecks in work flow. So this was suited to manufacturers that had constant production without regard to changing seasons. 2. The second alternative was to merge the skirt and trouser production, which require less work load, in one line. In this line, a few machine was justified by production improvement. It was suited to cases which producted various style suits. The third and fourth alternative were using another subcontractor for assembling inner shell garments. These was compatible in manufacturers which had to product more styles and sizes of trousers and skirts than those of upper garments. 3. The third alternative was to reassign the same workers in production line. Thus, production was increased. 4. The fourth alternative was to except two worker in production line, so expenses of worker's wage was decreased. The four alternatives could be one of the cost effective manufacturing plans according to manufacturer situations.

• 에너지공학
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• 제26권3호
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• pp.123-130
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• 2017

집단에너지 시스템은 높은 에너지 생산 효율과 발전 시 탄소배출량 절감 등의 이점이 있어 활용이 느는 추세다. 집단에너지 시스템은 도입 초기에는 열원 설비와 수요단지간의 개별 연결 형태였으나, 수요지가 증가하며 최근 네트워크 형태로 발전하고 있다. 집단에너지 시스템이 네트워크 형태로 구축하면 미활용 열을 수요가 발생한 곳에 송열하는 열 연계가 가능해지고, 이는 사업자의 수익성을 개선하여 산업에 긍정적 영향을 미친다. 이에 따라 본 연구에서는 열 연계 네트워크 설계를 위한 시뮬레이션을 진행하였다. 시뮬레이션을 거쳐 열 연계 네트워크에서 연중 최대 부하가 발생하는 링크를 크리티컬 링크(Critical Link)로 구분하였다. 또한, 크리티컬 링크의 연계 배관 용량 증감에 대한 민감도 분석을 통해 연계 배관 용량을 증가시키는 것이 열 연계 네트워크 효율에 영향을 미침을 제시하였다. 본 분석 결과를 바탕으로 크리티컬 링크 중 배관 용량의 증가 대비 열 연계량 효과가 높은 지역을 우선적으로 타 집단 에너지 사업자와 열 연계를 추진하면 상호 시너지 창출이 가능할 것이다.

• 한국화재소방학회논문지
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• 제24권3호
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• pp.33-38
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• 2010

피난 평가를 위해서 도면을 이용한 상용 시뮬레이션의 수행이 일반화되고 있다. 안전대책 수립에 있어서 피난소요시간 평가가 중요한 요소이며, 피난 동선상의 각 병목구간에서의 유출계수는 피난소요시간을 결정짓는 가장 중요한 요소가 된다. 본 논문은 상용 프로그램의 검증을 위하여 대규모 인원이 대피하는 지하역사에서 2개의 병목 구간인 계단 및 개찰구에서 실측 유출계수와 2가지 상용 프로그램의 유출계수를 비교하였다. 비교 결과 계단과 개찰구에서 서로 다른 모드로 시뮬레이션을 수행해야 함을 확인하였다. 유출계수의 경우 상용프로그램의 정확한 이해 없이 시뮬레이션을 수행하면 실측치와 큰 차이가 날 수 있었으며 이런 차이를 줄이기 위해서는 정확한 입력 조건을 결정할 수 있어야 한다. 결론적으로 상용 프로그램의 사용은 실측 데이터와 비교 검토하는 작업절차를 걸쳐야만 올바른 평가가 가능하다고 사료된다.

• Journal of Communications and Networks
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• 제9권4호
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• pp.446-456
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• 2007

Increased access to broadband networks has led to a fast-growing demand for voice and video over IP(VVoIP) applications such as Internet telephony(VoIP), videoconferencing, and IP television(IPTV). For pro-active troubleshooting of VVoIP performance bottlenecks that manifest to end-users as performance impairments such as video frame freezing and voice dropouts, network operators cannot rely on actual end-users to report their subjective quality of experience(QoE). Hence, automated and objective techniques that provide real-time or online VVoIP QoE estimates are vital. Objective techniques developed to-date estimate VVoIP QoE by performing frame-to-frame peak-signal-to-noise ratio(PSNR) comparisons of the original video sequence and the reconstructed video sequence obtained from the sender-side and receiver-side, respectively. Since processing such video sequences is time consuming and computationally intensive, existing objective techniques cannot provide online VVoIP QoE. In this paper, we present a novel framework that can provide online estimates of VVoIP QoE on network paths without end-user involvement and without requiring any video sequences. The framework features the "GAP-model", which is an offline model of QoE expressed as a function of measurable network factors such as bandwidth, delay, jitter, and loss. Using the GAP-model, our online framework can produce VVoIP QoE estimates in terms of "Good", "Acceptable", or "Poor"(GAP) grades of perceptual quality solely from the online measured network conditions.

• Transactions on Electrical and Electronic Materials
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• 제11권4호
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• pp.155-165
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• 2010

As a promising candidate to replace the conventional floating gate flash memories, polysilicon-oxide-nitride-oxidesilicon (SONOS)-type nonvolatile semiconductor memories have been investigated widely in the past several years. SONOS-type memories have some advantages over the conventional floating gate flash memories, such as lower operating voltage, excellent endurance and compatibility with standard complementary metal-oxide-semiconductor (CMOS) technology. However, their operating speed and date retention characteristics are still the bottlenecks to limit the applications of SONOS-type memories. Recently, various approaches have been used to make a trade-off between the operating speed and the date retention characteristics. Application of high-k dielectrics to SONOS-type memories is a predominant route. This article provides the state-of-the-art research progress of high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories. It begins with a short description of working mechanism of SONOS-type memories, and then deals with the materials' requirements of high-k dielectrics used for SONOS-type memories. In the following section, the microstructures of high-k dielectrics used as tunneling layers, charge trapping layers and blocking layers in SONOS-type memories, and their impacts on the memory behaviors are critically reviewed. The improvement of the memory characteristics by using multilayered structures, including multilayered tunneling layer or multilayered charge trapping layer are also discussed. Finally, this review is concluded with our perspectives towards the future researches on the high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2018년도 춘계학술대회 및 임시총회
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• pp.41-41
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• 2018

There has been an impetus in the development of biocontrol agents (BCAs) with the removal of a number of chemical compounds in the market, especially in the European Union. This has been a major driver in the development of Integrated Pest Management systems (IPM) for both pest and disease control. For control of mycotoxigenic fungi, there is interest in both control of colonization and more importantly toxin contamination of staple food commodities. Thus the relative inoculum potential of biocontrol agent vs the toxigenic specie sis important. The major bottlenecks in the production and development of formulations of biocontrol agents are the resilience of the strains, inoculum quality and formulation with effective field efficacy. It was recently been shown for mycotoxigenic fungi such as Aspergillus flavus, under extreme climate change conditions, growth is not affected although there may be a stimulation of aflatoxin production. Thus, the development of resilient biocontrol strains which can may have conserved control efficacy but have the necessary resilience becomes critical form a food security point of view. Indeed, under predicted climate change scenarios the diversity of pests and fungal diseases are expected to have profound impacts on food security. Thus, when examining the identification of potential biocontrol strains, production and formulation it is critical that the resilience to CC environmental factors are included and quantified. The problems in relation to the physiological competence and the relative humidity range over which efficacy can occur, especially pre-harvest may be increase under climate change conditions. We have examined the efficacy of atoxigenic strains of A. flavus and Clanostachys rosea and other candidates for control of A. flavus and aflatoxin contamination of maize, and for Fusarium verticillioides and fumonisin toxin control. We have also examined the potential use of fluidized-bed drying, nanoparticles/nanospheres and encapsulation approaches to enhance the potential for the production of resilient biocontrol formulations. The objective being the delivery of biocontrol efficacy under extreme interacting climatic conditions. The potential impact of climate change factors on the efficacy of biocontrol of fungal diseases and mycotoxins are discussed.