• 한국자동차공학회논문집
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• 제22권6호
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• pp.96-103
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• 2014

Liquefied Petroleum Gas(LPG) has attracted attention as a alternative fuel. The lean-burn LPG direct injection engine is a promising technology because it has an advantage of lower harmful emissions. This study aims to investigate the effect of combustion strategy and excess air ratio on combustion and emission characteristics in lean-burn LPG direct injection engine. Fuel consumption and combustion stability were measured with change of the ignition timing and injection timing at various air/fuel ratio conditions. The lean combustion characteristics were evaluated as a function of the excess air ratio with the single injection and multiple injection strategy. Furthermore, the feasibility of lean operation with stratified mixture was assessed when comparing the combustion and emission characteristics with premixed lean combustion.

• Design & Manufacturing
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• 제16권3호
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• pp.50-57
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• 2022

The qualities of the products produced by injection molding are strongly influenced by the process variables of the injection molding machine set by the engineer. It is very difficult to predict the qualities of the injection molded product considering the stochastic nature of the manufacturing process, since the processing conditions have a complex impact on the quality of the injection molded product. It is recognized that the artificial neural network(ANN) is capable of mapping the intricate relationship between the input and output variables very accurately, therefore, many studies are being conducted to predict the relationship between the results of the product and the process variables using ANN. However in the condition of a small number of data sets, the predicting performance and robustness of the ANN model could be reduced due to too many input variables. In the present study, the ANN model that predicts the length of the injection molded product for multiple combinations of process variables was developed. And the accuracy of each ANN model was compared for 8 process variables and 4 important process inputs that were determined by the feature selection. Based on the comparison, it was verified that the performance of the ANN model increased when only 4 important variables were applied.

• 지질공학
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• 제25권1호
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• pp.67-81
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• 2015

선형 또는 군집형으로 배치된 양수정 배열 조건에서 최적의 복수 주입정 위치를 결정하는 최적화 프로그램을 개발하였다. 다양한 목적함수를 제시하였으며 담금질모사 기법을 이용하여 목적함수를 만족시키는 주입정의 최적 위치를 평가하였다. 주입수의 회수율의 최대화를 목적함수로 설정할 경우, 우물 배열에 관계없이 두 개의 주입정을 모두 우물 군집 내부에 설치하는 것이 가장 효율적인 것으로 나타났다. 회수율의 최대화와 동시에 기존 양수정의 양수량을 고르게 증가시키는 통합목적함수를 고려하여 두 개의 주입정을 설치할 경우, 우물 배열에 관계없이 우물 배열의 양측면부가 주입정 위치로 적합한 것으로 분석되었다. 주입정 위치 최적화를 위한 다수의 시나리오 분석 결과, 최적의 결과에 근접하는 지역적 최솟값 또는 최댓값이 다수 존재하는 것으로 나타났으며, 이는 주입정의 최적 위치를 현장의 조건에 맞게 선택적으로 결정할 수 있는 개연성이 존재하는 것을 의미한다. 결론적으로, 본 연구는 담금질모사 기법이 다양한 목적함수에 부합하는 복수 주입정의 최적 위치 평가에 성공적으로 이용될 수 있음을 보여 주었다.

• Korean Journal of Acupuncture
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• 제38권4호
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• pp.250-266
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• 2021

Objectives : This study was conducted to suggest new alternative methods to improve pharmacopuncture and Korean medicine research by analyzing the injection route, pharmacological effect, and status studies of Chinese herbal injections. Methods : 130 types of marketed and licensed Chinese herbal injection were searched from National Medical Products Administration (NMPA) of China. CNKI, PubMed, EMBASE, and the 2020 edition of the Chinese Pharmacopoeia were used to collect additional information. 'Herbal injection' and 'Chinese herbal injection' were used as keywords. All data were collected mainly on the treatment of Chinese herbal injection. But data which were not related to the relevant research or Chinese herbal injection were excluded. Results : Intramuscular injection accounted for more than half of the single injection route (51%). Acupoint and intramuscular injections accounted for 55% of dual injection routes. Acupoint, intravenous, and intramuscular injections accounted for the largest proportion (76%) of the multiple routes of injections. As for the pharmacological effect, injection for cardiovascular diseases accounted for 29%. About the number of raw herbal materials, single herbal material was the most common. Twelve intervention studies all tested intravenous injections, and half of them investigated cardiocerebrovascular diseases. All were given by intravenous injection. In the side effect section, the most common symptoms were nausea and vomiting. Conclusions : Through the results, it is expected to be used for research and development of new pharmacopuncture and herbal medicine.

• 한국지반신소재학회논문집
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• 제19권4호
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• pp.11-20
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• 2020

본 연구에서는 연약지반의 개량 및 부등침하가 일어난 건물의 복원 등에 사용할 수 있는 컴팩션 그라우팅 공법을 소개하였다. 기존 컴팩션 그라우팅 공법에서 사용되는 펌프는 1공씩 주입하는 시스템으로 시공 효율성이 저하되고,아날로그 주입방식으로 현장 작업자가 수동으로 시공을 관리하여 일관된 품질관리가 어려웠다. 기존 시공에서의 문제점을 해결하기 위하여 펌프와 품질관리 시스템을 개발하였다. 품질관리 시스템은 주입재료의 자동 배합 시스템, 다중 동시 주입 펌프, 주입관리 모니터링 시스템으로 구성하였다. 현장 시험을 통해 품질관리 시스템의 성능을 검증하였고 컴팩션 그라우팅 공법의 시험시공 후 품질 시험을 통하여 지반개량 성능을 확인하였다. 따라서 개발된 통합 품질관리 시스템을 활용한다면 시공 및 품질 확인이 어려운 현장에서 일관된 품질의 보장과 시공의 효율성 및 안정성을 향상시킬 수 있을 것으로 기대된다.

• 한국인터넷방송통신학회논문지
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• 제23권4호
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• pp.183-188
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• 2023

게임 오브젝트의 상속 및 여러 가지의 컴포넌트를 이용하여 시스템 아키텍처의 시각화, 우수한 코드 재사용 및 빠른 프로토타이핑이 가능하다. 반면에 객체는 게임 오브젝트와 컴포넌트 간의 높은 대기 시간, 정적 형변환과 널 포인터등의 많은 참조에 의존하기 마련이다. 게임 제작시에 여러 클래스에 대한 객체의 의존도를 낮추고 코드의 재사용이 가능하도록 설계하는 것은 중요한 일이다. 따라서 의존성 주입(Dependency Injection)과 GoF(Gang of Four)가 제안한 디자인 패턴들을 적용하여 클래스의 모듈성을 더욱 높일 수 있도록 게임을 설계하였다. 이러한 의존성은 게임 오브젝트의 속성이고 주입은 초기화 패스에서만 발생하므로 게임 루프에서 성능 저하나 성능 페널티는 미세하다. 따라서 본 논문에서는 서바이벌 게임의 설계와 구현에 있어서 API(Application Programming Interface)를 효과적으로 재사용하는 효율적인 설계방법을 제안하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.219-219
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• 2013

The effect of an electron blocking layer (EBL) on V-I curves in GaN/InGaN multiple quantum well is investigated. For the first time, we found that curves were intersected at 3.012 V and analyzed the reason for intersection. The forward voltage in LEDs with an p-AlGaN EBL is larger than without p-AlGaN EBL at low injection current because the Mg doping efficiency for p-GaN layer was higher than that of p-AlGaN layer. However, the forward voltage in LEDs with an p-AlGaN EBL is smaller than without p-AlGaN EBL at high injection current because the carriers overflow from the active layer when injection current increases in LEDs without p-AlGaN EBL and in case of LED with p-AlGaN EBL, the carriers are blocked by EBL.

• Advances in Computational Design
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• 제4권4호
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• pp.367-379
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• 2019

Multiple Inputs and Multiple Outputs (MIMO) Fuzzy logic model is developed to predict the engine performance and emission characteristics of pongamia pinnata biodiesel with hydrogen injection. Engine performance and emission characteristics such as brake thermal efficiency (BTE), brake specific energy consumption (BSEC), hydrocarbon (HC), carbon monoxide (CO), carbon dioxide ($CO_2$) and nitrous oxides ($NO_X$) were considered. Experimental investigations were carried out by using four stroke single cylinder constant speed compression ignition engine with the rated power of 5.2 kW at variable load conditions. The performance and emission characteristics are measured using an Exhaust gas analyzer, smoke meter, piezoelectric pressure transducer and crank angle encoder for different fuel blends (Diesel, B10, B20 and B30) and engine load conditions. Fuzzy logic model uses triangular and trapezoidal membership function because of its higher predictive accuracy to predict the engine performance and emission characteristics. Computational results clearly demonstrate that, the proposed fuzzy model has produced fewer deviations and has exhibited higher predictive accuracy with acceptable determination correlation coefficients of 0.99136 to 1 with experimental values. The developed fuzzy logic model has produced good correlation between the fuzzy predicted and experimental values. So it is found to be useful for predicting the engine performance and emission characteristics with limited number of available data.

• 대한조선학회논문집
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• 제58권1호
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• pp.24-31
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• 2021

In this study, we present experimental observations of artificial supercavitation generated by the injection of compressed air at multiple locations on the body. Experiments were conducted at a cavitation tunnel equipped with a special facility to remove injected air before returning to the test section. Artificial supercavitation, which is generated at a relatively low speed compared to natural supercavitation, is formed asymmetrically on the axis of the body due to the buoyancy effect. In order to accelerate the development of the supercavity and increase the area covering the body, an experimental device capable of additional injection from the body was designed and its performance was evaluated through the model test. The shapes of the supercavity generated by multi-injections of different combinations according to different flow speeds were analyzed using high-speed shadow images. The results show that multiple injections at suitable locations can effectively increase the length of the supercavity and consequently improve propulsion efficiency.

• 한국연소학회지
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• 제18권1호
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• pp.7-12
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• 2013

A quasidimensional program is developed for a four stroke cycle homogeneous GDI (Gasoline Direct Injection) engine. It includes models for spray, burning rate and chemistry to predict knock and emissions. With early injection a homogeneous GDI engine goes through spark ignited, turbulent premixed combustion as in PFI (Port Fuel Injection) engines. The cylinder charge is divided into unburned and burned zone with the latter divided into multiple zones of equal mass to resolve temperature stratification. Validation is performed against measured pressure traces, NOx and CO emissions at different load and RPM conditions. Comparison is made between an empirical knock model and predictions by the chemistry model in this work.