• 한국분무공학회지
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• 제23권2호
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• pp.58-65
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• 2018

An analytic strategy to control the variable valve actuation applied to two intake valves (flow port intake valve and swirl port intake valve) was performed in this study. we considered the variation in phasing of intake valve profiles by using the Cam-in-Cam technology. The analytic model was implemented in the GT-Power simulation program and analyzed the result of regulated emissions such as, NOx and Soot, especially with IMEP characteristics. Namely, we meticulously investigated the sources of having effect on the amount of NOx and soot formation under the test conditions with retard timing of both flow port and swirl port intake valves for decreasing the opening duration by 35CAD. Also, we analyzed the effect of incylinder pressure and temperature with NOx variations and in-cylinder pressure and temperature on NOx variations and normalized turbulent intensity. Through this analysis, some useful results on the combustion and flow characteristics of the swirl port and flow port control of the intake valve were obtained by this study.

• 천문학회보
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• 제46권1호
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• pp.35.2-35.2
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• 2021

Blue straggler stars (BSs) are "rejuvenated" main sequence stars first recognized by Allan Sandage from his observation of the prominent northern globular cluster M3 in the year of 1953. BSs are now known to be present in diverse stellar environments including open clusters, globular clusters, dwarf galaxies, and even the field populations of the Milky Way. This makes them a very useful tool in a wide range of astrophysical applications: Particularly BSs are considered to have a crucial role in the evolution of stellar clusters because they affect on the dynamics, the binary population, and the history of the stellar evolution of the cluster they belong to. Here we report a part of the preliminary results from our ongoing research on the BSs in the two metal-poor globular clusters (GCs) in the Large Magellanic Cloud (LMC), Hodge 11 and NGC1466. Using the high precision multi-band images obtained with the Advanced Camera for Survey (ACS) onboard the Hubble Space Telescope (HST), we extract time-series photometry to search for the signal of periodic variations in the luminosity of the BSs. Our preliminary results confirm that several BSs are intrinsic "short period (0.05 < P < 0.25 days)" variable stars with either pulsating or eclipsing types. We will discuss our investigation on the properties of those variable BS candidates in the context of the formation channels of these exotic main sequence stars, and their roles in the dynamical evolution of the host star clusters.

• 마케팅과학연구
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• 제8권
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• pp.207-232
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• 2001

본 연구는 고객만족에 있어서 전통적인 기대불일치 패러다임이 상황에 따라 변할 수 있다 라는 연구에 근거하여 고려되어 질 수 있는 상황을 밝혀보고자 하는 생각에서 출발하였다. 서비스의 주요 특징중의 하나인 이질성을 주요 상황으로 채택한 본 연구는 대상에 있어서도 공공서비스의 경우로 특정시켜 논의를 진행시켰다 SERVQUAL이 공공서비스에서도 서비스 품질을 측정할 수 있는 측정척도로써 사용 가능하다는 연구를 근거로 SERVQUAL의 차원을 이용하여 공공서비스의 기대, 성과, 불일치, 만족에 대한 측정을 하여 전통적인 기대불일치 패러다임이 공공서비스에도 적용되는지를 고찰했고, 다 항목으로 이질성의 지각정도를 측정 하여 이질성을 높게 느끼는 집단과 낮게 느끼는 집단간에 비교를 롱하여 이질성이 고객만족 형성과정에 영향을 미치는지를 검증해 보았다. 본 연구에서 이론적으로 검토되고 개발된 모형은 실증모형을 통해 각 구성개념들로 측정 되어 제시한 가설을 검증하는 근거로 사용되었다. 이 과정에서 변수간 다수의 인과관계를 동시에 고려하고, 또 이를 잠재요인과 연관하여 해석하는데 유용하게 쓰여지는 LISREL(공변 량구조분석) 모형에 의해 실증적으로 이론모형과 측정변수들이 검증되었다. 본 연구 결과 우리는 다음과 같은 점을 발견하였다. 첫째, 상황에 따라 고객만족형성과정 이 다르다는 것을 발견하였다. 이는 전통적으로 고객만족형성과정이 기대불일치 패러다임에 따라 설명되어 온 것에 대하여 상황 요인이 선행변수로 고려되어야 할 필요가 있다는 것이다. 둘째, 이러한 상황요인으로 우리는 서비스의 주요 특징 중의 하나인 이질성을 선행변수 로 고려하였는데 고객의 서비스 이질성 지각 정도에 따라 고객만족형성과정이 차이가 남을 발견하였다. 셋째, 우리는 공공서비스에도 이와 같은 고객만족형성과정이 적용될 수 있음을 발견하였다.

• 한국태양에너지학회 논문집
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• 제26권2호
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• pp.19-25
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• 2006

Methane hydrate, non-polluting new energy resource, satisfies requirement and considered as a precious resource that can prevent the global warming. Fortunately, there are abundant resources of methane hydrate distribute in the earth widely. Therefore, developing the techniques that can utilize these gases effectively is highly desired. The work in this paper here is to develop a skill which can transport and store methane hydrate. As a first step, the equilibrium experiment was carried out by increasing temperatures in the cell at fixed pressures. The influence of gas consumption rates under variable degree of subcooling, stirring and water injection has been investigated formation to clarify kinetic characteristics of the hydrate. The results of present investigation showed that the enhancements of the hydrate formation in terms of the gas/water ratio are closely related to operational pressure, temperature, degrees of subcooling, and water injection.

• 한국연소학회지
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• 제15권4호
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• pp.22-28
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• 2010

The Direct Quadrature Method of Moments (DQMOM) has been presented for the solution of population balance equation in the wide range of the multi-phase flows. This method has the inherently interesting features which can be easily applied to the multi-inner variable equation. In addition, DQMOM is capable of easily coupling the gas phase with the discrete phases while it requires the relatively low computational cost. Soot inception, subsequent aggregation, surface growth and oxidation are described through a population balance model solved with the DQMOM for soot formation. This approach is also able to represent the evolution of the soot particle size distribution. The turbulence-chemistry interaction is represented by the laminar flamelet model together with the presumed PDF approach and the spherical harmonic P-1 approximation is adopted to account for the radiative heat transfer.

• Journal of Chest Surgery
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• 제10권1호
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• pp.59-64
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• 1977

Mediastinal tumor are frequently encountered in clinical practice. Hanten, in 1955, reported-2 adult patients with spontaneous rupture of mediastinal dermoid cysts into the pleural cavity and also, Thompson, in 1963, reported 2 child patients with spontaneous rupture of mediastinal teratoma into the pleural cavity. Mediastinal teratomas have also been reported rupture into other contiguous structures, such as the bronchus, aorta, pericardium, SVC and esophagus. This report presents an instance of spontaneous rupture of an anterior mediastinal teratoma into the right pleural cavity of a 43 year old female. Despite variable diagnostic procedures, the true nature of the lesion was not determined until a thoracotomy and window formation was performed for adequate drainage of empyema thoracis. Removal of the teratoma and mediastinal window formation resulted in complete cure.

• KSBB Journal
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• 제10권2호
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• pp.119-125
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• 1995

균류를 이용하는 생물공정의 생산성, 분리성, 유변 학적 성질에 영향을 미치는 중요한 변수인 균류의 형태를 fractal 차원을 사용하여 정량화하였다. 산업적으로 중요한 균류인 Aspegillus oryzae와 Aspergil Ius niger가 초기의 접종 포자량과 탄소원의 놓도를 변화시켜 액상배지에서 성장하는 경우 디지탈 영상 분석장치를 사용하여 fractal 차원을 계산하였다. 균 샤가 형성하는 구체의 특성과 fractal로 표현된 균사 의 형태와의 상관관계를 구하였다. 일반적으로 낮은 fractal 차원의 균사가 낮은 밀도(compactness)의 구체를 형 성하고 외부의 모양이 불규칙 척 이 었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.744-749
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• 2005

The train configuration is based on one unit like basic 4 cars to multiple unit operation. Each unit has unique node such as train formation number. Some equipments(TC, CC) of TCMS are connected to the master TC through the LonWorks network. When the train is consist of multiple unit, TCMS has to implement quick network for data communication overall train. But a variable time delay is generated when it is performed communication with point to point type using train formation number. In this paper we propose new method to know the node information of adjacent unit. that is to add digital input signals notifying cab direction at any cabin. Also, we provide the optimized screen design that all collected information via network is displayed by each unit.

• 한국정밀공학회지
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• 제12권2호
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• pp.87-96
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• 1995

The cutting force is the most important variable to understand the mechanics of ultra-precision machining. Most dynamometers, however, monitor the static cutting force only. But it is necessary to measure the dynamic cutting force to clarify the machinability of the material, the formation of the chip, chatter and the wear of the tool. In this research, measurement of the dynamic cutting force in order to clarify the machin-ability of the material, the formation of the chip, chatter and the wear of the tool has been conducted. A combined-type dynamometer which could measure the static cutting force and the dynamic cutting force by use of strain gauges and a piezo-film accelerometer has been developed. An analysis of the dynamometer also has been carried out.

• 대한기계학회논문집
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• 제16권2호
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• pp.348-355
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• 1992

Casting structures and properties are determined by the solidification speed in the metal mold. The heat transfer characteristics of the interface between the mold and the casting is one of the major factors that control the solidification speed. According to Sully's research, the thermal resistance exists due to the air-gap formation at the mold-casting interface during the freezing process and the interface heat transfer coefficient is used to describe the degree of it. In this study, one-dimensional Stefan problem with air-gap resistance in the cylindrical geometry is considered and heat transfer characteristics is numerically examined. The temperature distribution and solidification speed are obtained by using the modified variable time step method. And the effects of the major parameters such as mold geometry, thermal conductivity, heat transfer coefficient and initial temperature of casting on the thermal characteristics are investigated.