• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권2호
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• pp.709-730
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• 2017

To address the challenge of unprecedented growth in mobile data traffic, ultra-dense network deployment is a cost efficient solution to offload the traffic over some small cells. The overlapped coverage areas of small cells create more than one candidate access points for one mobile user. Signal strength based user association in IEEE 802.11 results in a significantly unbalanced load distribution among access points. However, the effective bandwidth demand of each user actually differs vastly due to their different preferences for mobile applications. In this paper, we formulate a set of non-linear integer programming models for joint user association control and user demand guarantee problem. In this model, we are trying to maximize the system capacity and guarantee the effective bandwidth demand for each user by soft-association control with a software defined network controller. With the fact of NP-hard complexity of non-linear integer programming solver, we propose a Kernighan Lin Algorithm based graph-partitioning method for a large-scale network. Finally, we evaluated the performance of the proposed algorithm for the edge users with heterogeneous bandwidth demands and mobility scenarios. Simulation results show that the proposed adaptive soft-association control can achieve a better performance than the other two and improves the individual quality of user experience with a little price on system throughput.

• 한국미생물·생명공학회지
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• 제20권5호
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• pp.597-606
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• 1992

Alcaligenes eutrophus 균주로 poly-Beta-hydroxybutyrate(PHB) 생산을 위한 연속배양 공정의 성능에 미치는 희석비율, 주입 포도당 및 염화암모늄농도의 영향에 대하여 연구하였다. 주입 기질농도가 일정할때( 주입 포도당농도=20g/l, 주입 염화암모늄농도=2g/l), 생체성장속도와 PHB생성속도는 희석비율이 각각 0.1, $0.06h^{-1}$에서 최고 값을 나타냈고, $0.13h^{-1}$에서 세포가 전부 배출되었다. 희석비율이 증가함에 따라 비PHB 생성속도는 계속 증가하였지만 PHB 축적비는 50%에서 25%로 감소하였다. 세포농도는 주입 염화암모늄농도가 2g/l일 때 최고값을 나타내었고, 그 이상의 농도에서는 감소하였다. 이 실험결과로 암모늄에 의한 기질저해가 있음을 알 수 있었다. 주입 포도당농도가 30g/l에서 세포농도는 최고값을 나타냈지만 PHB 농도는 계속 증가하였따. 모델속도식에 대한 매개변수는 도식적 방법과 매개변수 추정으로 구하였고 희석비율, 주입 포도당농도, 주입 염화암모늄농도의영향에 대하여 모사한 결과 실험데이타와 잘 일치하였다.

• 한국작물학회지
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• 제53권1호
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• pp.8-14
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• 2008

Ammonia ($NH_3$) volatilization from a silty clay loam paddy soil applied with non, straight urea, and coated urea, respectively, under transplanting in Milyang, Korea from 2002 and 2003 was simulated by a Water and Nitrogen Management Model (WNMM). Based on the data from the in-situ measurements, $NH_3$ volatilization during the rice growth was 6.04% and 1.46% of the applied nitrogen (N) from straight urea and coated urea, respectively. The bulk aerodynamic approach in WNMM satisfactorily predicted the difference in $NH_3$ loss during the given rice growing seasons from the two urea fertilizers. $R^2$ for the correlation between the predicted and observed NH3 loss during the calibration year (2002) was 0.53 less than 0.68 of the application year (2003). This difference could be due to the weather condition such as heavy rainfall and temperature during the calibration year.

• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.551-559
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• 2005

The recent rapid increase in genomic data related to many microorganisms and the development of computational tools to accurately analyze large amounts of data have enabled us to design several kinds of simulation approaches for the complex behaviors of cells. Among these approaches, dFBA (dynamic flux balance analysis), which utilizes FBA, differential equations, and regulatory events, has correctly predicted cellular behaviors under given environmental conditions. However, until now, dFBA has centered on substrate concentration, cell growth, and gene on/off, but a detailed hierarchical structure of a regulatory network has not been taken into account. The use of Boolean rules for regulatory events in dFBA has limited the representation of interactions between specific regulatory proteins and genes and the whole transcriptional regulation mechanism with environmental change. In this paper, we adopted the operon as the basic structure, constructed a hierarchical structure for a regulatory network with defined fundamental symbols, and introduced a weight between symbols in order to solve the above problems. Finally, the total control mechanism of regulatory elements (operons, genes, effectors, etc.) with time was simulated through the linkage of dFBA with regulatory network modeling. The lac operon, trp operon, and tna operon in the central metabolic network of E. coli were chosen as the basic models for control patterns. The suggested modeling method in this study can be adopted as a basic framework to describe other transcriptional regulations, and provide biologists and engineers with useful information on transcriptional regulation mechanisms under extracellular environmental change.

• 한국콘텐츠학회논문지
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• 제12권7호
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• pp.114-122
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• 2012

우수한 특허기술을 보유한 지역 기업들에게 매출 성장과 시장 경쟁력을 강화하기 위해서는 디자인개발이 절실히 요구되고 있다. 이러한 중소기업의 요구를 해결하기 위하여 특허청과 충청북도의 매칭으로 지역 디자인 가치제고사업이 진행되고 있으며 이를 통해 디자인 가치를 향상시키고 있다. 본 연구는 S사에서 발주한 프로젝트로 '터널 내 환경에 적합한 LED LAMP 외관디자인 개발'을 사업수행 V사가 개발한 디자인으로, 특허기술을 바탕으로 외관 디자인개발을 성공적으로 수행함으로서 지원업체의 디자인 인지도와 제품의 경쟁력을 제고시키면서 시뮬레이션 개발과 함께 개량 특허를 창출한 사례이다. 터널내 LED LAMP의 효율적인 교체방법과 LED LAMP 반사 방법에 제안한 결과를 통해 수혜기업에서는 개인사업자에서 법인화를 진행하였고 제작 판매를 위해 제조기반시설 확충을 하여 현재 초기 제품이 완료되었다. 디자인과 특허의 융합으로 매출향상과 디자인 권리를 확보함으로써 기업 고유의 디자인 가치를 향상시켰다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권3호
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• pp.200-208
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• 1999

In this paper, the corona discharge is analyzed by Finite Element Method(FEM) combined with Flux-corrected Transport(FCT) algorithm. In the previous papers, Finite Difference Method(FDM) combined with FCT was used. Usually in the FDM, the regionof interest is discretized with structured grids. But to refine local regions with same resolution, much more grids are required for the structured grids than for unstructured grids than for unstructured grids. Therefore, we propose the FEM-FCT method to simulate the corona discharge. The proposed method has good flexibility in model shape and can reduce the computational cost by the local refinement where the physical quantities have steep gradients. Using the proposed method, we study the streamer growth of parallel plate electrodes which is initiated by the low and high perturbation density. We find that the varying the initial density of perturbation has very little effect on the streamer propagation. And the corona discharge of the rod-to-plane electrode is simulated. On the surface of the rod electrode, the high concentration of the electric field gives rise to many number of streamer seeds. The strong axial streamer propagate to the plane electrode. The weaker non-axial streamer repel each other and stop growing more. The results are very similar to those of the papers which used the FDM-FCT method on structured grids. Thus we can conclude that the proposed FEM-FCT method is more efficient than the conventional FDM-FCT method by virtue of the reduction in computational grids number.

• 대한구순구개열학회지
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• 제12권1호
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• pp.21-32
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• 2009

Generally, an adult cleft lip or/and palate patient shows some amount of maxillary deficiency due to limitation of bony growth caused by heavy scars resulted from previous operations such as a cheiloplasty and/or a palatoplasty at an early child age. To solve the problem, advancement of the maxilla is usually required during orthognathic surgery. However, severe tensional force resulted from heavy scars on the palate and/or the lip, as well as the bony defect at the cleft area limited sufficient advancement of the maxillary segment and finally caused relapse of the reposed maxilla. Therefore, distraction osteogenesis of the maxilla was introduced for the successful maxillary advancement inthose kinds of patients. As both hard and soft tissues can be simultaneously and gradually extended with this technique, tensional force caused by heavy scars opposed to forward movement of the maxilla can be reduced to an extent not to develop severe relapse of the advanced maxilla. Since distraction osteogenesis of the maxilla was applied as one of standard protocols for the treatment of the patients with severe maxillary hypoplasia dueto cleft lip and/or palate, the devices for the distraction was improved to control the vectors of distraction with better and more stable. We have treated a 23-year-old male cleft patient with a severe maxillary hypoplasia using a newly developed a maxillary distraction device and a RP model for a pre-operative simulation surgery. As a result, we could successfully move the maxilla as we designed pre-operatively and also reduce much of operation time. Therefore, we report of the case to share our experience with colleagues.

• 대한조선학회논문집
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• 제47권2호
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• pp.113-121
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• 2010

Recently, as container ships become larger and faster, rudder cavitations are more frequently observed near the gap between the horn and rudder plates of the ships to cause serious damages to the rudder surface of the ship. The authors already have suggested through a series of model experiments and numerical computations that employment of an appropriate blocking device for gap flow may retard the gap cavitation. For examples, a cam device installed near the outer edges of the vertical gap or a water-injection device combined with a pair of half-round bars installed inside the gap can considerably reduce the gap cavitation. However, it is also found that effective blocking of the flow through the vertical gap results in growth of the cavitation near the horizontal gap instead. In the present study, effectiveness of the simultaneous blocking of the flow through the horizontal and vertical gaps of a horn type rudder in minimizing the damage by gap cavitation is studied. Additional blocking disks are inserted inside the horizontal gaps on the top and bottom of the pintle block and numerical computations are carried out to confirm the combined effect of the blocking devices.

• 한국축산식품학회지
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• 제32권1호
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• pp.118-124
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• 2012

본 연구는 햄 및 소시지류에서의 Clostridium perfringens에 대한 정량적 미생물 위해평가(Quantitative microbial risk assessment; QMRA)를 국제기준(Codex)의 원칙과 지침에 따라 수행하였으며, 오염수준에 대한 직접적인 분석결과와 현재의 국내 유통환경, 관련제품의 특성, 섭취량 및 소비행태 등을 반영한 노출평가용 "product-retail-consumption pathway" frame-work 모델을 구성하였고, 이를 바탕으로 엑셀(Excel)기반 노출평가용 시뮬레이션 모델을 개발하여 제시하였다. 개발된 모델을 시뮬레이션 프로그램인 @RISK를 활용하여 위해(risk) 수준을 산출하였으며, 그 결과 국내에서 1일 1인이 햄 및 소시지류의 섭취를 통한 Cl. perfringens에 의한 식중독발생 확률은 평균적으로 $3.97{\times}10^{-11}{\pm}1.80{\times}10^{-9}$으로 추정하였다. 또한 본 연구에서 수행한 QMRA결과를 바탕으로 현재수준에서의 한계점과 미래에 더욱 발전된 국내 QMRA 연구 및 활용을 위한 제언을 추가하였다

• 한국습지학회지
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• 제22권4호
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• pp.321-327
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• 2020

산업발전과 인구증가, 생활수준의 향상으로 하·폐수 발생량 및 하수처리장 연계처리수가 매년증가 하고 있다. 연계처리수는 저유량 고농도의 특징을 가지고 있다. 따라서 하수처리장 운영에 큰 영향을 미치고 연계처리수를 처리하기 위해 많은 비용도 사용되는 것으로 나타났다. 본 연구에서는 연계처리수의 유입 유량을 개별 반응조로 전량 유입시킬 경우 방류수 수질이 적게 상승한 시나리오를 도출했고, 모델링 결과 유입하수, 무산소조에 유입시킬 경우 방류수 수질이 가장 적게 상승하는 것을 확인할 수 있었다. 이와 같은 결과를 바탕으로 연계처리수의 유입 유량을 유입하수와 무산소조로 분배하여 유입시킬 경우에 대하여 분배 비율에 대한 다양한 시나리오를 생성했다. 다양한 시나리오를 통해 모델링을 진행한 결과 유입하수(80%), 무산소조(20%)의 비율로 연계처리수의 유입유량을 분배 유입 시킬 경우 TN, TP의 수질이 가장 적게 상승하는 것으로 나타났다.