• 한국분무공학회지
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• 제18권4호
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• pp.176-181
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• 2013

In this study, injection quantity, rate and spray image of multiple injections which are important design parameters for a piezo type injector have been investigated. Interval of injections and a number of injections in multiple injection strategy has been controlled to verify interaction of each injection. Spray characteristics of multiple injections have been researched through optical process with a high speed camera in a high pressure chamber. In addition, a method of RMS(Root Mean Square) process has been used for comprehending the distribution of injection easily. As a result, in case of piezo type injector, characteristics of injection quantity according to charging voltage and the difference of injection quantity between single and triple injection were confirmed. Also, injection rate for increasing injection duration was confirmed. And spray characteristics of multiple injections were improved; multiple injections were possible in a shorter time interval between each injection. With this study, a possibilities of more accurate multiple injection control would be expected.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.53-56
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• 2004

The mixing characteristics of a multiple transverse injection system in a scramjet combustor were studied with numerical methods. The distance among injectors on mixing characteristics were investigated. The three-dimensional Wavier-Stokes equations including k-w SST turbulence model were solved. It was shown that the mixing characteristics of a multiple transverse injection system were very different from those of a single and a dual injection system; the rear injection flow was strongly influenced by blocking effect due to the momentum flux of the front injection flow and thus had higher expansion and penetration than the front injection flow. The multiple injection system had higher mixing rate, higher penetration but had more losses of stagnation pressure than the single injection system.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.311-312
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• 2012

Homogeneous charge compression ignition combustion with multiple-injection strategy using dimethyl-ether was investigated in a single cylinder direct-injection compression-ignition engine. The combustion performance and exhaust emissions were tested by varying the post injection conditions. The experiments were carried out under low load and low speed conditions. By the late post injection near the top dead center, the combustion phase was retarded and lengthened, and the fuel conversion efficiencies improved without the drawbacks of exhaust emissions increment.

• 한국자동차공학회논문집
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• 제15권4호
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• pp.76-82
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• 2007

This paper described the effect of the multiple injections on the stability of combustion and emission characteristics in a direct injection diesel engine at various operating conditions. In order to investigate the influence of multiple injections in a diesel engine, the fuel injection timing was varied one main injection and two pilot injections at various conditions. The experimental apparatus consisted of DI diesel engine with four cylinders, EC dynamometer, multi-stage injection control system, and exhaust emissions analyzer. The combustion and emission characteristics were analyzed for the main, pilot-main injection, pilot-pilot-main injection strategies. It is revealed that the combustion pressure was smoothly near the top dead center and the coefficient of variations is reduced due to the effect of pilot injection. Also, $NO_x$ emissions are dramatically decreased with pilot injection because the decrease of rate of heat release. However, the soot is increased at early pilot injection and main injection.

• 한국자동차공학회논문집
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• 제19권3호
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• pp.99-105
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• 2011

This paper described the effect of the multiple injections on the emission characteristics and combustion stability in a common rail diesel engine. In order to investigate the influence of multiple injections in a passenger car diesel engine, the injection strategy was varied with pilot injection, post injection and one main injection at various conditions. Based on the experimental results, the combustion and emissions characteristics were analyzed for the various injection strategies such as main, pilot-main, double-pilot-main, double- pilot-main-post injection strategy. It is revealed that the $NO_X$, HC and CO emissions are reduced by double pilot and post injection at medium load, however, soot emission is increased. Also, in the case of multiple injection, the combustion pressure is increased smoothly near the TDC and the coefficient of variation and fuel consumptions are decreased.

• 한국산학기술학회논문지
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• 제18권4호
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• pp.711-717
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• 2017

디젤엔진은 저온 상태의 냉시동 조건에서 디젤 미립화 특성 악화로 인한 시동성 및 유해배출가스 생성의 문제를 안고 있다. 본 연구에서는 냉시동 시의 연소개선을 위한 방안으로 다단분사 전략 적용 시의 연소 특성을 파악하고자 하였다. 본 연구에서는 냉시동성 개선을 위해 방안으로 다단분사 적용 시의 연소 특성을 파악하고자 하였다. 정적 연소 챔버 내에 설치한 압력센서를 이용하여 취득한 연소압 및 열방출율, 직접 화염 가시화기법을 적용한 화염강도를 이용하여 연소현상을 분석하고자 하였다. 시험 결과 단일 분사 대비하여 다단 분사 적용 시, 주분사에 의한 최대 연소압력 및 열방출 상승률이 증가하며, 주분사에 의한 화염 감지 기간이 단축됨을 확인하였다. 파일럿 분사량 변경을 통해 분사량 증대 시 파일럿 연소에 의한 열방출 향상에 기인한 주분사에 의한 연소가 개선됨을 확인하였다. 또한 분사압력 증대 시 연료 미립화 개선으로 인한 연소개선을 화염 강도 증대를 통해 확인할 수 있었다. 다만 분사량 및 분사압 증대는 벽면적심현상으로 인한 HC, CO의 배출 수준 악화를 초래할 수 있으므로, 실제 엔진 개발 시 이에 대한 정밀한 선정이 필요할 것으로 판단된다.

• 정보보호학회논문지
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• 제30권6호
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• pp.1247-1254
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• 2020

스마트홈 시대가 도래하면서 실생활의 다양한 곳에 기밀성을 제공하거나 인증을 수행하는 장비들이 존재하게 되었다. 이에 따라 암호화 장비 및 인증 장비에 물리적인 공격으로부터의 안전성이 요구되고 있다. 특히 외부에서 인위적으로 오류를 주입하여 비밀 키를 복구하거나 인증 과정을 우회하는 오류 주입 공격은 매우 위협적인 공격 방법의 하나다. 오류 주입 공격에 사용되는 오류원은 레이저, 전자파, 전압 글리치, 클락 글리치 등이 있다. 오류 주입 공격은 오류가 주입되는 횟수에 따라 단일 오류 주입 공격과 다중 오류 주입 공격으로 분류된다. 기존의 다중 오류 주입 시스템은 일반적으로 단일 오류원을 사용하였다. 단일 오류원을 여러 차례 주입하도록 구성된 시스템은 물리적인 지연 시간이 존재한다는 점과 추가적인 장비가 필요하다는 단점이 존재한다. 본 논문에서는 이종(異種) 오류원을 사용하는 다중 오류 주입 시스템을 제안한다. 그리고 제안하는 시스템의 효용성을 보이기 위해 Riscure사의 Piñata 보드를 대상으로 다중 오류 주입 공격을 수행한 결과를 보인다.

• International Journal of Precision Engineering and Manufacturing
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• 제1권1호
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• pp.133-145
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• 2000

Plastic molding designers are frequently faced with optimizing multiple defects in injection molded parts. these defects are usually in conflict with each other, and thus a tradeoff needs to be made reach a final compromised solution. In this study, an automated injection molding design methodology has been developed to optimize multiple defects of injection molded parts. Two features of the proposed methodology are as follows: one is to apply the utility theory to transform the original multiple objective optimization problem into single objective optimization problem with utility as objective function, the other is an implementation of a direct search-based injection molding optimization procedure with automated consideration of process variation. The modified complex method is used as a general optimization tool in this research. The developed methodology was applied to an actual molding design and the results showed that the methodology was useful through the CAE simulation using a commercial injection molding software package. Applied to production, this study will be of immense value to industry in reducing the product development time and enhancing the product quality.

• 한국수정란이식학회지
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• 제11권3호
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• pp.211-216
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• 1996

A series of experiments were designed to determine the feasibility of single dose of FSH as an effective superovulation method in rabbits. The superovulation treatments examined comparatively were as follows: 1) a single injection of 100 IU PMSG, 2) Multiple injections of 1 IU Super-OV of 2X daily for 3 days, 3) Multiple injections of 6.6 rng Folltropin-V 2X daily for 3 days, 4) Multiple injections of 13.3 rng Folltropn-V l$\times$ daily for 3 days, 5) Single injection of 40 mg Folltropin-V solved in 10% PVP, and 6) Single injection of 40 mg Folltropin-V dissolved in 25% PVP. The results obtained were as follows: The nurnher of ovulation points in the single injection of 40 mg Folltropin-V dissolved in 25% PVP and multiple injections of 6.6 mg Folltropin-V 2X daily for 3 days was averaged 44.6 and 39.2, respectively, which were significantly (P<0.05) more than in a single dose of PMSG or multiple doses of Super-OV. The number of total ova recovered in the single injection of 40 mg Folltropin-V dissolved in 25% PVP and multiple injections of 6.6 mg Folltropin-V 2X daily for 3 days was averaged 30.4 and 25.9, respectively, which were significantly (P<0.05) more than in the single dose of PMSG or multiple doses of Super-OV. A similar result was obtained for the number of fertilized ova recovered from the above six treatments. From the above results it was concluded that a single injection of 40 mg Folltropin-V dissolved in 25% PVP could be an effective and simple method for superovulation in rabbits.

• 상하수도학회지
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• 제32권3호
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• pp.211-220
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• 2018

The water containing soluble manganese may cause problems such as discolored water, unpleasant taste, fouling or scaling of pipes in water distribution system, and so on. Conventional water treatment processes using sand filtration or sedimentation after oxidation, however, cannot often meet manganese standard for drinking water. Two types of oxidants, potassium permanganate ($KMnO_4$) and sodium hypochlorite (NaOCl), were utilized at the same time for manganese oxidation, and then the precipitated manganese oxides were removed by low pressure membrane filtration in this study. In batch experiments, the multiple injection of both oxidants showed more effective manganese removal than did the single injection using either of them. Moreover, the deterioration of manganese removal at low temperature was less serious for the multiple injection than that for the single injection. Manganese removal by the continuous system of oxidation by multiple injection combined with membrane filtration was higher than those by batch experiments at the same oxidation conditions. In addition, less membrane fouling was observed for membrane filtration with oxidation during continuous membrane filtration than membrane filtration without oxidation. These results indicate that the oxidation by multiple injection coupled with membrane filtration was efficient and applicable to actual water treatment for manganese removal.