• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.4
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• pp.467-473
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• 2017

In this paper, impact characteristics of a water entry gliding vehicle were analyzed using a finite element method. To guarantee the validity of analysis results, a convergence test was performed for several ratios of Euler and Largrange mesh sizes. The impact coefficient was calculated with respect to entry angles and angle of attacks. It can be observed that the impact coefficient was large at a high cross-section gradient and was also affected by cavitation. This study could be useful in the preliminary design stage of a water entry bomb development.

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.167-167
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• 2008

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.137-145
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• 2008

In this paper, novel CMOS charge pump having NMOS and PMOS transfer switches and a bulk-pumping circuit has been proposed. The NMOS and PMOS transfer switches allow the charge pump to improve the current-driving capability at the output. The bulk-pumping circuit effectively solves the bulk forward problem of the charge pump. To verify the effectiveness, the proposed charge pump was designed using a 80-nm CMOS process. The comparison results indicate that the proposed charge pump enhances the current-driving capability by more than 47% with pumping speed improved by 9%, as compared to conventional charge pumps having either NMOS or PMOS transfer switch. They also indicate that the charge pump reduces the worst-case forward bias of p-type bulk by more than 24%, effectively solving the forward current problem.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.18-24
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• 2014

In this paper, the optimum placement of airborne line-of-sight (LOS) datalink directional antenna to minimize the datalink loss within the operation range of unmanned aerial vehicle (UAV) is analyzed by using the electromagnetic (EM) simulation. In quick banking of UAV, the datalink loss is occurred due to the electromagnetic distortion and transmission loss by the fuselage blockage. In general, the banking angle of UAV is limited to prevent the datalink loss. However, in this case, there is the problem that the mission performance ability is largely limited by the banking radius increase. To solve this problem, the optimum placement to mount the airborne LOS datalink 1-axis directional antenna on both the top and bottom surfaces of fuselage is analyzed by using EM simulation. The 1-axis antenna with large vertical beamwidth is used because the banking angle of UAV is dependent on the vertical beamwidth of antenna. Also, there is the benefit to reduce largely the weight because the 1-axis antenna can be mounted instead of the 2-axis one.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1279-1284
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• 2012

Silica supported $Cs_{2.5}H_{0.5}PMo_{12}O_{40}$ catalyst was prepared through sol-gel method with ethyl silicate-40 as silicon resource and characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen adsorption-desorption and potentiometric titration methods. The $Cs_{2.5}H_{0.5}PMo_{12}O_{40}$ particles with Keggin-type structure well dispersed on the surface of silica, and the catalyst exhibited high surface area and acidity. The catalytic performance of the catalysts for benzene liquid-phase nitration was examined with 65% nitric acid as nitrating agent, and the effects of various parameters were tested, which including temperature, time and amount of catalyst, reactants ratio, especially the recycle of catalyst was emphasized. Benzene was effectively nitrated to mononitro-benzene with high conversion (95%) in optimized conditions. Most importantly, the supported catalyst was proved has excellent stability in the nitration progress, and there were no any other organic solvent and sulfuric acid were used in the reaction system, so the liquid-phase nitration of benzene that we developed was an eco-friendly and attractive alternative for the commercial technology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.661-672
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• 2017

This paper introduces the NLSE(Nonlinear Least Squared Estimator) using curved LOBs(Line Of Bearings) considering the earth curvature based on sphere to avoid the map conversion distortion and minimize the estimation error. This paper suggests a method improving a performance of the NLSE using curved LOBs by using an ellipsoid model. The analysis of the simulation results shows that the NLSE using curved LOBs has better performance than the conventional triangulation method and can improve its performance using a suggested method.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.721-730
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• 1993

Various catalysts of $Cu_xH_3-{_{2x}}PMo_{12}O_{40}{\cdot}_nH_2O$ with different x-values have been prepared and characterized by thermal analysis, X-ray powder diffraction, infrared spectroscopy, BET surface-area measurement, electron microscopy, and temperature programmed desorption of ammonia. The properties of these catalysts in acrolein oxidation have been investigated in a continuous-flow fixed-bed reactor. The catalysts lost their water of crystallization at about $200^{\circ}C$ and their constitutional water between 300 and $400^{\circ}C$. The Keggin structure of the catalysts was identified by infrared spectroscopy. The decomposition of Keggin anion, $(PMo_{12}O_{40})^{3-}$, was increased with the increase of substituted copper content and identifiable $MoO_3$ and $P_2O_5$ as decomposition products were observed. The conversion of acrolein decreased with the increase of x probably due to the decrease of specific surface area and of total amount of acid sites. But specific reaction rate and selectivity to acrylic acid were maximized at x=1.0, and it showed specific acid site distributions.

• Macromolecular Research
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• v.15 no.7
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• pp.693-696
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• 2007

• 한국IT서비스학회:학술대회논문집
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• 2009.05a
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• pp.453-458
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• 2009

정보화가 기업 경쟁력의 핵심 요소로 부각되고 있으며 기업 및 정부기관은 앞 다투어 정보화에 투자하고 있는 상황이다. 정보시스템 개발 프로젝트도 이제는 대형 프로젝트 수가 급증하고 있다. 최근 소프트웨어 CMMi 수준에 관한 인증 여부는 기업 경쟁력의 핵심적인 요인으로 그 중요성이 날로 강조되고 있다. 또한 PMI의 PMBOK는 프로젝트 관리의 바이블 격으로 업종 업태를 불문하고 광범위하게 적용되고 있는 상황이다. 프로젝트 관리자의 관점에서 볼 경우 CMMi 모델과 PMBOK 모델간의 중첩되는 부분, CMMi 프로세스를 실적용 시 관리영역에 대한 혼선 부분, 또한 PMBOK 상위지침의 구체성 미흡 부분에 대한 통합 및 조정이 필요하게 되었다. 현재 상용되는 개발방법론에는 관리적인 요소가 매우 미약하고, 국내에 아직까지 체계적으로 정립된 관리방법론이 없는 상황이다. 따라서, 본 논문에서는 프로젝트 관리자가 숙지해야 하는 프로젝트 관리영역, 프로젝트 관리단계, 제반 절차, 유관 정보시스템과의 연동(Interface) 등을 정보화 개발 프로젝트 생명주기(Life Cycle)에 맞춰 재구성 및 통합하여 프로젝트 관리자(Project Manager)에게 일관된 관점(Single Point of View)을 제시하여 프로젝트 생산성을 제고 하고자 한다.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.1
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• pp.76-83
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• 2016

State-of-the-art design S/W and other 3D systems are used for design and development of weapon system. It is possible to detect problems of design through 3D or VR(Virtual Reality) in advance, and then reduce the development cost by finding solutions before prototype production. Therefore, we can increase efficiency for supportability of weapon system. In this study, we first propose a design verification procedure. Then we verify design of weapon system, underwater guided weapon, as a case study. Finally, we suggest alternatives for underwater guided weapon under development with DMS(Digital Maintenance System) and ICIDO from the point of view of ILS(Integrated Logistics Support). Developed S/W, DMS, draws maintenance procedures for components. Commercial S/W, ICIDO, verifies cable maintainability.