• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2002년도 제18회 학술발표대회 논문초록집
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• pp.46-49
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• 2002

Three-dimensional flow characteristics in a liquid fuel ramjet combustor were investigated using the PIV method. The combustor has two rectangular inlets that loin a 90-degree angle each other. Three cases of test combustors are made in which those inlet angles are 30 degree, 45degree and 60 degree. The experiments were performed in a water tunnel test with the same Reynolds number as Mach 0.3 at the inlet. PIV software was developed to measure the characteristics of the flow field in the combustor. Accuracy of the developed PIV program was verified with a rotating disk experiment and standard data. The characteristics of the internal flows of the combustor are large swirling flows which appear symmetric with respect to the symmetric section. This is attributed to the fact that the flows introduced from the right and left intakes collide with each other, thus forming symmetrically large vortices. A large and complex three-dimensional recirculating flow was measured behind the intakes. An inlet angle of 30 degrees is the most suitable angle as a frame he]der in the performed experimental ranges.

• 설비공학논문집
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• 제13권8호
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• pp.771-779
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• 2001

In this study, a simulation program has been developed to predict the performance of a parallel flow condenser of an air conditioning system for an automobile. The well-known correlations for he heat transfer rates and the pressure drops are included in this model. It is fond that the numerical model can predict the heat transfer rate and the pressure drop accurately. As the condensing pressure increases of fixed air inlet temperature, the heat transfer rate increases and the pressure drop decreases. The effect of he degree of subcooling on the performance of the condenser is greater than that of the degree of super-heating because the ratio of the area occupied by he tow-phase refrigerant the total area is significantly affected by he degree of subcooling rather than the degree of superheating.

• 한국게임학회 논문지
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• 제17권5호
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• pp.71-80
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• 2017

본 연구는 온라인 게임 플레이어의 유형에 따라 몰입 및 충성도에 어떠한 차이가 나타나는지 분석하였다. 한 주간 이용시간 2시간 이상의 게임 플레이어가 2시간미만 이용자보다 통계적으로 유의하게 몰입도가 높게 나타났으며, 한 주간 3시간 이상 게임을 하는 플레이어는 한 주간 1시간미만 플레이어에 비해 충성도가 높게 나타났다. 6달 이상 게임을 한 플레이어가 6달 미만으로 게임을 한 플레이어보다 통계적으로 몰입도가 높게 나타났으며, 6~9개월 게임을 한 플레이어가 3개월 미만 플레이어보다 충성도가 높게 나타났다. 또한 높은 레벨과 계급을 지니고 있는 게임 플레이어가 낮은 레벨의 게임 플레이어보다 몰입도와 충성도가 높은 것으로 조사되었다.

• 한국산림과학회지
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• 제95권3호
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• pp.350-357
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• 2006

인공강우발생장치를 이용하여 산불발생지를 대상으로 산불발생 후 경과년수에 따라 각 지역에 대한 강우강도 및 경사별로 지표유출량을 관측하여 산불발생지의 지표유출 특성을 구명하고, 또한 지표유출량과 강우강도, 경사, 경과년수와의 관계를 분석하였으며, 그 결과는 다음과 같다. 1. 산불발생연도별 지표유출량은 강우강도가 30 mm/hr씩 증가함에 따라서 2.2~3.2배 증가하였으며, 경사가 $10^{\circ}$씩 증가함에 따라서는 1.5~1.9배 증가하였다 2. 산불발생지에서 지피식생이 80% 이상 피복되더라도 초기강우 때의 지표유출량은 다소 많이 발생하여, 식생에 의한 유출량 감소효과는 높지 않았다. 3. 산불발생 후 경과년수에 따라 강우강도 및 경사별로 구분한 지표유출량은 산불발생 3년 후의 경우 발생당년에 비해 22.3%~41.8%로 감소하였고, 산불발생당년에는 강우강도 및 경사별로 지표유출량에 많은 차이가 있었으나 시간이 경과할수록 그 차이가 작아졌다. 4. 산불발생지사변에서의 지표유출량에 대해 각 인자간의 영향성을 분석한 결과, 강우강도, 경사, 경과년수의 각각의 주효과와 강우강도${\times}$경사, 강우강도${\times}$경과년수의 상호작용 효과에 대해서는 차이를 보였고, 경사${\times}$경과년수, 강우강도${\times}$경사${\times}$경과년수의 상호작용 효과에 대해서는 차이가 없었다. 지표유출량에 영향을 미치는 인자의 영향도는 강우강도가 가장 큰 영향을 미치고 다음이 경사, 경과년수의 순이었다.

• 대한핵의학회지
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• 제32권1호
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• pp.32-49
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• 1998

O-15 표지 물 동적 PET을 이용하여 비균일 심근조직의 혈류를 정확히 추정하기 위하여 일차구획 모델을 변형한 두 개의 혈류 모델을 고안하였다. 첫 모델에서는 혈류, PTI, 조직회수 분획($F_{MM}$)을 추정하였고, 두 번째 모델에서는 혈류, PTI, 그리고 분배계수를 추정하였다. 비균일 심근조직의 비균일성을 나타낼 지표를 도입하여 여러 종류의 비균일 조직을 모사하고 이 지표로 비균일성을 표현하였다. 우리 모델을 적용하여 PTI가 혈류분포의 비균일성과 상관이 적음을 확인하고 분배계수를 변수로 취급한 두 번째 모델에서 추정한 분배계수가 비균일성을 나타냄을 알았다. 분배계수는 비균일성에 따라 굽은 선형(curvilinear)으로 감소하였다. 분배계수와 함께 추정된 혈류도 비균일성이 커지면 참값보다 작게 추정되었다. 추정된 분배계수로 혈류 추정값의 과소평가플 보정하여 추정값의 바이어스를 바로잡을 수 있었다. O-15 표지 물 동적 PET으로 심근혈류를 측정할 때 분배계수를 변수로서 혈류와 함께 추정하여 비균일성을 나타내는 지표로 쓰고 동시에 혈류 추정값을 참값에 가까운 값을 얻는데 쓸 수 있다고 본다. 혈류분포의 비균일성 정도를 수치적으로 표시할 수 있는 지표를 임상에 적용하면 허혈성 심근 질환의 혈류 비균일성을 해석할 수 있을 것으로 생각한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.292-297
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• 2001

This paper discusses the effect of varying LiBr solution circuits flow rates for a direct fired double effect commercial absorption chiller in the parallel flow configuration. The effects of solution flow rates have been investigated for generator, condenser, solution heat exchanger, absorber and evaporator. According to the result of this work, it was found that sensible heat rate of generator increases and refrigerant vapor generated in that decreases when inlet solution flow rate of that increases. As solution flow rate of absorber increases, the degree of superheat increases because of decreasing solution heat exchanger efficiency. The flashing vapor at the top of absorber increases in proportion to the degree of superheat whileas decreases cooling capacity inversely.

• 한국가시화정보학회지
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• 제7권1호
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• pp.29-34
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• 2009

During the past three or four decades, the characteristics of turbulent flow have been studied extensively because of their scientific and academic importance. This research deals with the periodic flow oscillation without swirling flow in a 180 degree circular tube using hot wire anemometry, microphone and accelerometer. The frequency regions are observed through the structured oscillation from spectrum. This work carried out to measure the sound level for each Reynolds number, $6{\times}10^4$, $8{\times}10^4$ and $1{\times}10^5$ respectively at the test tube without swirl flow.

• 지식경영연구
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• 제19권2호
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• pp.21-45
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• 2018

With the widespread use of smartphones and the development of information technology, an online service called SNS(social network service) has emerged, and as an increasing number of people began to use SNS, extensive research has been conducted on SNS. SNS is an important factor for adolescents who are developing social skills that help them to adapt to the society, and for adults who are stepping into the society. The present study investigates the effects of information search, self-disclosure, interaction, and playfulness, all of which are motivational factors for SNS use, on flow in SNS, and empirically analyzes the degree of these variables influence according to flow in SNS and individual's personal nature(extrovert, introvert). The analysis results showed that information search, self-disclosure, interaction, and playfulness were positively correlated with flow in SNS, and flow in SNS was positively correlated with social skills. The degree of influence varied depending on the individual's personal nature(extrovert, introvert). These findings may provide important insights for researchers studying SNS, SNS managers, and company officials using SNS.

• 설비공학논문집
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• 제10권1호
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• pp.56-65
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• 1998

In this paper, experimental investigation of capillary tube performance for R-407C is performed. The experimental setup is made of real vapor-compression refrigerating system. In this study, mass flow rate is measured for capillary tubes of various diameter and length as inlet pressure and degree of subcooling are changed. These data are compared with the results of a numerical model. The mass flow rates of the numerical model are less than by 14% compared with the measured mass flow rates. It is found that mass flow rate and length for R-407c are less than those of R-22 under the same condition. Also based on this experimental study and the numerical model, a set of capillary tube selection charts for R-407C is constructed.

• 한국자동차공학회논문집
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• 제8권2호
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• pp.33-40
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• 2000

In order to investigate the exhaust structure and secondary oxidation of unburned hydrocarbon (HC) in the exhaust port, a numerical simulation was performed with 3-dimensional flow model and oxidation mechanism optimized for port oxidation. To predict the exhaust and oxidation process with consideration of flow, mixing, and temperature, 3-dimensional flow model and HC oxidation model were used with a commercial computational program, STAR-CD. The flow model were with moving grid for valve motion, which could predict the change of flow field with respect to valve lift. Optimization was performed to predict the HC oxidation with temperature range of 1200~1500K, low HC and oxygen concentration, existence of intermediate species, as typical in port oxidation. The constructed model could predict the port oxidation process with oxidation degree of 14~48% according to the engine operation conditions.