• 한국산업융합학회 논문집
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• 제25권6_2호
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• pp.1111-1117
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• 2022

Recently, interest in the circular economy has emerged in the industry. As a result, interest in Re-manufacturing, which makes old equipment similar to new products, is growing. In the machine tool industry with many aging equipment, the Re-manufacturing industry is essential, and among them, research on the performance improvement of gear type oil pumps was conducted. The purpose was to achieve the target performance of flow rate and volume efficiency by changing the shape of the gear pump housing clearance and inlet/outlet, and Computational Fluid Analysis and Central Composite Design were conducted using ANSYS CFX 2022 R2 and MINITAB®. The level of each determined factor was determined. 20 design points were derived, and the Flow Rate at each design point was calculated, and the Theoretical Flow Rate was calculated to obtain Volumetric Efficiency. The optimal design point was obtained when the Flow Rate was 140 lpm and the Volumetric Efficiency was maximum, the optimal design point was obtained when both were maximum, and the Surface Plot for each factor was obtained to identify the tendency.

• International Journal of Automotive Technology
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• 제7권4호
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• pp.441-448
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• 2006

In-cylinder flows such as tumble and swirl play an important role on the engine combustion efficiencies and emission formations. The tumble flow, which is dominant in current high performance gasoline engines, is able to effect fuel consumptions and emissions under a partial load condition in addition to the volumetric efficiency under a wide open throttle condition. Therefore, it is important to optimize the tumble ratio of a gasoline engine for better fuel economy, lower emissions, and maximum volumetric efficiency. First step for optimizing a tumble ratio is to measure a tumble ratio accurately. For a tumble ratio measurement, many different methods have been developed and used such as steady flow rig, PIV, PTV, and LDV. However, it is not well known about the relations among the measured tumble ratios using different methods. The purpose of this research is to correlate the tumble ratios measured using three different methods and find out merits and demerits of each measurement method. In this research the tumble flow was measured, compared, and correlated using three different measurement methods at the same engine: steady flow rig; 2-dimensional PIV; and 3-dimensional PTV water flow rig.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 추계학술대회
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• pp.253-260
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• 2004

해상 구간에서의 선박 운항과 관련된 단위 비용이 선박 대형화에 비례하여 감소한다는 규모의 경제에 근거하여 최근 8,000 TED급 선박이 운항을 개시하였고, 10,000 TED급 이상 초대형선(mega ship)이 설계 단계에 있다. 본 연구에서는 운항비, 항만비용, 피더 비용 등에 대한 실증분석을 통하여 대형선의 기항지 축소에 따른 경제성을 분석한다.

• 한국추진공학회지
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• 제3권2호
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• pp.48-55
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• 1999

50㎾급 터보제너레이터 가스터빈 엔진에 리쿠퍼레이터가 부착되는 경우 성능 변화를 조사하였다. 리쿠퍼레이터는 군사 및 소형 자동차용 엔진에 경제적 연비와 배기가스 저감의 목적으로 많이 적용되어 왔다. 열역학적 관점에서 볼 때 재생사이클은 압축비 10이하 및 비교적 낮은 터빈 입구온도에서 사이클의 효율 상승에 기여하는 바가 큰 것으로 나타난다. 1축단순사이클 터보제너레이터 가스터빈 엔진에 리쿠퍼레이터를 부착하는 경우 리쿠퍼레이터 효율 $\varepsilon$ = 0.5에서 엔진의 효율은 상대적으로 약 30% 증가하는 것으로 나타났고 이때 열교환기내의 압력 손실은 5.2%로 설계하였다. 용이한 제작, 구조적 견고성, 최소의 누출 둥의 장점으로 튜브형의 열교환 시스템이 본 가스터빈 엔진에 적합한 것으로 판단되었다.

• 한국세라믹학회지
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• 제46권1호
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• pp.47-52
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• 2009

Lime paint surpassing others in execution efficiency, anti-bacterial, anti-mold and small quantity emission of VOCs(Volatile Organic Compounds) characteristics was developed using a limestone as raw materials. The lime paint prepared by mixing slaked lime($37{\sim}40\;wt%$), PVA:EVA(9 wt%:1 wt%), talc(23 wt%), $TiO_2$(14 wt%), zeolite (3 wt%), antifoaming agent(5 wt%), wetting agent (5 wt%) was indicated over 99.8% of anti-bacterial and anti-mold characteristics. Also, the environment-friendly function of the lime paint was confirmed by detection of small amount of TVOCs($0.01\;mg/m^2h$) and formaldehyde($0.008\;mg/m^2h$). Execution efficiency, economy-and environment-friendly characteristics of this lime paint can make up for defects of established paints. And, it also presents the advantage of a limestone as high value added materials.

• 한국전자통신학회논문지
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• 제8권12호
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• pp.1857-1864
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• 2013

21세기 테크노피아 시대에서 주택 자동화의 범위를 정의하기는 쉽지 않다. 최근, 주택자동화는 첨단화된 디지털 통신기술을 기반으로 기존의 주택자동화 개념을 넘어, 주택 에너지 관리, 주택 통합 검침 그리고 주택 헬스 케어 등 다양한 영역으로 그 범위를 넓히고 있다. 하지만 이들 방법론들은 통합된 표준 없이 독립적으로 제안되기 때문에, 효율성과 경제성을 저하시키고 콤팩트한 설계를 어렵게 하고 있다. 따라서 본 연구에서는 각기 다른 방향에서 접근이 이루어지고 있는 이들 방법론들을 조사, 분석하여, 경제성과 효율성을 제고하고, 공간적으로 콤팩트한 설계를 가능케 하는 차세대 주택자동화시스템의 설계 및 방법론을 제시하고자 한다.

• 한국자동차공학회논문집
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• 제21권4호
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• pp.83-88
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• 2013

Recently, PCCI (premixed charge compression ignition) combustion is studied to reduce both NOx and PM because of homogeneous mixture formation and lower combustion temperature. It has also merit of increasing thermal efficiency owing to better air-fuel mixure. However, it is well known that PCCI combustion has a weakness in fuel economy because PCCI combustion tends to start before TDC. Therefore, it is necessary to find an optimal conditions for PCCI combustion which maintains reduction of NOx, PM and increase of thermal efficiency. In this study, pPCCI combustion was realized by adding early injection strategy to a conventional diesel engine. In addition, the characteristics of pPCCI combustion was analized by comparing conventional diesel injection strategy. The results show that NOx and PM per power in pPCCI combution were reduced compared to a conventional diesel combustion.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.541-544
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• 2005

This study presents the integrated modeling approach to simulate the proton exchange membrane (PEM) fuel cell system for vehicle application. The fuel cell system consisting of stack and balance of plant (BOP) was simulated with MATLAB/Simulink environment to estimate the maximum system power and investigate the effect of BOP component sizing on system performance and efficiency. The PEM fuel cell stack model was established by using a semi-empirical modeling. To maximize the net efficiency of fuel cel1 system, multi-variable optimization code was adopted. Using this method the optimized operating values were obtained according to various system net power levels. The fuel cell model established was co-linked to AVL CRUISE, a vehicle simulation package. Through the vehicle simulation software, the fuel economy of fuel cell powered electric vehicle for two types of driving cycles was presented and compared. It is expected that this study tan be effectively employed in the basic BOP component sizing and in establishing system operation map with respect to net power level of fuel cell system.

• 한국시스템다이내믹스연구
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• 제11권2호
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• pp.45-75
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• 2010

Today, the logistics industry has played a critical role in national economy activities. The low cost and high efficiency of the logistics industry are meaningful in the improvement of national competitiveness and the logistics industry. However, efficiency of logistics is lower than that of the United States and Japan since most quantities are processed in road transportation in Korea. With regard to this, existing studies expected a saving of social and environmental costs due to a decrease of road transportation as well as improvement of logistics productivity due to bulk transportation through activation of rail and costal transport. For the expectation, the existing multimodal transport systems should be improved first. Therefore it aimed to develop scenario-based simulation models of multimodal transport systems for decision makers in charge of improvement in the logistics area. For model development, this study utilized Thinking Process and System Dynamics(TP-SD) methodology.

• 한국항행학회논문지
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• 제17권1호
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• pp.132-141
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• 2013

본 논문에서는 공기제동의 문제점을 보완하기 위한 유지보수와 환경문제, 효율성, 경제성 등을 개선하기 위하여 정지에서 고속영역까지의 전 영역에서 전기제동을 사용하는 방법이 제시되었다. 전기적으로 완전제동을 위한 2가지 방법으로 인버터 출력전압의 증대에 의한 방법과 전동기와 인버터 사이에 직렬저항을 삽입하는 방법을 통하여 경제적이며 실제 적용이 가능한 제어방법인 직렬저항을 삽입하는 방법을 적용하기로 하였다. 직렬저항에 의한 전력손실을 감소시키기 위한 직렬저항을 단락 하는 방법을 사용하여 효율을 개선하고 전 영역에서의 제동력확보는 실험환경 내에서 우수한 인버터의 단자전압을 상승시키는 방법과 동일한 특성을 보였다.