• 한국응용곤충학회지
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• 제2권
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• pp.44-46
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• 1963

죽림해충중에서 가장 피해가 심한 죽순나방을 대상으로 하여 신농약 8종과 약제살포시기를 조사한 바 다음과 같은 결과를 얻었다. 1) Endrin, Aldrin E.P.N은 부화 14일전 처리로서 약간의 부화유충의 식입방지로서 유효하였고 부화후 처리구에 있어서도 무처리구에 비하여 유효하였다. 2) Sevin Aldrin, EPN은 Endrin에 비하여 효과가 낮았으며 Sevin, Folidol, Diazinone은 별차가 없었다. 3) 부화전후의 일별처리 효과는 부화 5일후 처리에 가장 효과가 좋았다. 4) 본 시험은 1회의 시험성적이 되므로 동일시험이 수회반복되어 살충효과 및 살포적기가 완전히 구명되었으면 한다.

• 한국산업융합학회 논문집
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• 제22권3호
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• pp.259-264
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• 2019

In this study, we experiment by making and designing of compression ignition diesel engine witch has air cooling, 2-cylinder and 2-strokes. Also, we make controller witch can control injection timing and period by arbitrary manual operation for change of injection timing. We also study experimentally in change about pressure and power of combustion chamber by increasing density of air which comes into cylinder because of increasing scavenging pressure. Through this, we confirmed that output change and scavenging pressure can develop performance of the engine by scavenging efficiency of a chamber and development of volume efficiency.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.9-16
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• 2006

Variable valve timing is one of the attractive ways to control homogeneous charge compression ignition (HCCI) engine. Hot internal residual gas which can be controlled by variable valve timing(VVT) device, makes fuel evaporated easily, and ignition timing advanced. Regular gasoline was used as main fuel and di-methyl ether(DME) was used as ignition promoter in this research. HCCI engine operating range is limited by high combustion peak pressure and engine noise. High combustion pressure can damage the engine during operation. To avoid engine damage, the rich limits have to define using various methods. Peak combustion pressure, rate of cylinder pressure rise was considered to determine rich limit of engine operating range. Knock probability was correlated with the rate of cylinder pressure rise as well as the peak combustion pressure.

• International Journal of Automotive Technology
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• 제8권6호
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• pp.697-704
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• 2007

Recently, a variable valve timing system has been widely adopted in internal combustion engine in order to improve the fuel economy and torque at low engine speed. In addition, it is known that varying valve timing according to the various engine operations could reduce exhaust gas, especially NOx, because of residual gas by valve overlap. In this study, to improve the low exhaust gas and fuel economy at part load condition, the residual gas and back flow of exhaust gas due to valve overlap were calculated computationally. Moreover, the characteristics of engine performances and NOx formations were investigated with the experiment of combination of intake and exhaust valve timing condition. Under these various valve operating conditions, the effects of both the positive valve overlap and negative valve overlap(valve underlap) were examined simultaneously. Finally, the characteristics of cyclic THC emission were analyzed by using Fast Response FID(FR-FID) in the cylinder, intake port and exhaust port positions. Besides, the effect of the different gradients of the valve timing change on engine performance was investigated and an optimum control strategy was suggested.

• 한국컴퓨터산업학회논문지
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• 제4권12호
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• pp.1053-1068
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• 2003

본 논문에서는 강제적 접근 제어를 구현한 보안 데이터베이스 시스템에서 실시간 트랜잭션을 효율적으로 처리하기 위한 스케줄링 기법을 제안한다. 제안된 기법에서는 시간 비밀 채널의 발생을 방지하고자 보안 등급에 기초한 대기 큐와 시간 제약 조건을 만족시키는 트랜잭션의 수를 최대로 하기 위해 트랜잭션의 타입, 종료시한, 중요도를 고려한 우선순위 큐를 이용한다. 제안된 기법은 보안등급이 다른 트랜잭션들 간의 불간섭 성질을 유지시켜 시간 비밀 채널을 제거하였으며, 종료시한을 만족시키는 실시간 트랜잭션의 중요도의 합을 최대로 하는 장점을 가진다. 또한, 제안된 기법은 성능평가를 통해서 기존의 기법에 비해 트랜잭션의 종료시한 만족 비율이 30% 정도 향상됨을 보였다.

• 전자공학회논문지
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• 제50권12호
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• pp.3-13
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• 2013

이 논문에서는 OFDM 시스템의 시간 영역 동기를 위한 2가지 방법을 제안한다. 이것은 심벌타이밍 판정의 모호함의 원인이되는 플레토와 사이드로브를 제거하기 위하여 부 심벌간에 1심벌 옵셋을 두고 타이밍 메트릭을 구하는 방법과 플레토 현상을 경감시킬 수 있는 전력감소지수(Reduction Factor, ${\rho}$), 제동상수(Break Constant, ${\beta}_k$) 그리고 심벌이식깊이(Implant Depth, ${\delta}_I$)등의 파라메터를 사용하여 CP(Cyclic Prefix) 구간의 전력을 수정하는 방법이다. 제안된 2가지 방법은 기존에 제안된 심벌타이밍 동기화기법들과 컴퓨터모의시험을 통해서 성능평가가 이루어졌으며, 제안된 방법들은 다중경로의 레일레이 페이딩채널에서 기존의 시스템에 비해서 더 우수한 통계적 특성을 나타내었다.

• 대한기계학회논문집B
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• 제26권12호
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• pp.1655-1662
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• 2002

Recently, many researches have been performed to improve the performance of the combustion and emission in a D.I.Diesel engine. And many new techniques have been introduced and developed to reduce NO$_{x}$ and soot exhausted from diesel combustion. Some of these methods have the peculiar injection timing which is not used to traditional timing. To optimize these injection timing, characteristics of swirl flow and interaction of swirl with injection in the diesel engine should be investigated more carefully. Therefore, in this study, 2-zone energy method is adopted for the understanding of swirl flow in condition of moving piston, and then flame visualizations and image process are performed. From these studies, the characteristics of the swirl flow generated by SCV was investigated and the effect of swirl on injection timing was elucidated. As the results, velocity distribution caused by swirl flow increase the space utilization rate of flame plums. And flame plums of weak momentum are remained inside of combustion chamber by the swirl flow.w.

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.106-113
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• 2016

Lean burn engine, classified into port injection and direct injection, is recognized as a promising way to meet better fuel economy. Especially, LPG direct injection engine is becoming increasingly popular due to their potential for improved fuel economy and emissions. Also, LPDi engine has the advantages of higher power output, higher thermal efficiency, higher EGR tolerance due to the operation characteristics of increased volumetric efficiency, compression ratio and ultra-lean combustion scheme. However, LPDi engine has many difficulties to be solved, such as complexity of injection control mode (fuel injection timing, injection rate), fuel injection pressure, spark timing, unburned hydrocarbon and restricted power. This study is investigated to the influence of spark timing, fuel injection position and fuel injection rate on the combustion stability of LPDi engine. Piston shape is constituted the bowl type piston. The characteristics of combustion is analyzed with the variations of spark timing, fuel injection position and fuel injection rate (early injection, late injection) in a LPDi engine.

• 한국자동차공학회논문집
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• 제24권1호
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• pp.47-52
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• 2016

Miller timing is one of the promising ways which can improve the fuel consumption of internal combustion engines. Indeed, Miller timing employing an early intake valve close is widely applied to large diesel and gas engines to enhance performance and reduce NOx emissions. In this study, performance evaluation is carried out by 1-D cycle simulation in order to estimate the effect of Miller CAM timing before BDC for a 32 L turbocharged diesel engine. To optimize Miller CAM timing, a single stage turbocharger is matched with an early intake valve close since boost pressure is a significant parameter that can control compression work in a turbocharged engine. The engine simulation result shows that there is enough potential to improve fuel consumption rate and also reduce NOx emissions at the same time.Abstract here.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.115-122
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• 1998

For digital engine control timings, such as ignition, are based on the crank shaft angle. Therefore, it is very important that the angle of the crank shaft can be detected with accuracy for optimal ignition timing. Sequential multi-point injection(MPI) systems that have independent injection events for each cylinder, are used to inject an accurate quantity of fuel, and to cope with varying engine status promptly. In this study the distributorless ignition timing. A crankshaft position sensor has been installed such that it generates a number of pulses per crankshaft revolution to permit accurate detection of the crank shaft angle. An event detecting algorithm has been developed, which detects the crank shaft pulses generated by the position sensor, and the software outputs the required control signals at given crank angle values. We clarified that the hardware method is the best way to increase the performance of the control system, because the event detecting duration T(1+2)max becomes zero.