• 한국추진공학회지
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• 제23권2호
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• pp.1-12
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• 2019

액체로켓엔진에서의 추력조절을 위해 기체주입식 가변추력 방법에 대한 기초적인 연구를 수행하였다. 기체주입식 가변추력은 간단한 구조로 추력을 조절할 수 있을 뿐만 아니라 밀도 감소에 비례하여 증가된 분사차압에 의해 미립화 성능 증가라는 장점을 갖는다. 본 연구에서는 기체주입식 와류형 분사기를 이용하여 액체 질량유량과 기체주입량의 변화에 따른 분무 불안정, 분무형상, 분무각, 분열 길이와 같은 분무특성을 살펴보았다.

• 농업생명과학연구
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• 제52권6호
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• pp.111-125
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• 2018

본 연구에서는 변량방제기술을 적용한 농용 회전익기를 이용하여 살포한 입자의 구간비행 상태에서의 거리별 살포 패턴을 측정함으로써 무인 항공방제의 농약 부착률과 입자경의 분포 균일도를 평가하였다. 비행을 등속으로 유지하는 안내비행과 자동비행 모드에서 유효살포폭 3.6m로 인접비행 구간과 살포폭이 일부 중첩된 피복률에 대한 가로방향 분포의 변이계수는 30% 정도를 보였고, 비행방향 진로위치에 대한 피복률의 변이계수는 10% 미만으로 매우 균등한 것으로 평가되었다. 따라서 살포작업시 기체의 지면속도(ground speed)의 변이를 보상하는 변량살포기술은 균일도 측면에서 우수한 것으로 판명되었으며, 또한 입자경의 분포에 있어서 체적중위직경(VMD)과 개체중위직경(NMD) 모두 항공방제에 적절한 크기와 균일한 분포를 보였다. 따라서 농용 회전익기를 이용하여 소필지의 항공방제작업을 무인화 하는데 있어, 변량방제장치를 적용함으로써 소규모 필지의 균일 정밀방제를 도모하고자 하였다.

• 한국화재소방학회논문지
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• 제33권5호
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• pp.28-36
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• 2019

본 연구에서는 분사 형태(Spray pattern)가 중실원추형(Full cone) 및 중공원추형(Hollow cone)인 2유체 미립화기를 이용하여 공급 기체 및 미분무가 헵탄 풀화재(Heptane pool fire) 소화 성능에 미치는 영향을 검토하였다. 2유체 미립화기의 공급 기체로 30 lpm (Liter per minute; L/min)의 공기 또는 질소를 이용하였으며, 물을 공급하지 않은 경우(즉, 공기 또는 질소만 분사한 경우)와 물 0.085 lpm을 공급한 경우(즉, 미분무와 공급 기체를 함께 분사한 경우)에 대해 실험을 수행하였다. 실험 결과, 공급 기체만 분사한 경우보다 미분무와 공급 기체를 함께 분사한 경우에, 그리고 중공원추형인 경우보다 중실원추형인 경우에 빠르게 화재 소화 가능함을 확인하였다. 또한, 중실원추형의 경우, 미분무와 공급 기체 함께 분사 시 화재 소화 성능에 미분무의 영향은 지배적이었으나 공급 기체의 영향은 미비한 것으로 관찰되었다. 반면, 중공원추형의 경우, 중실원추형과 달리 미분무와 공급 기체 함께 분사 시 공급 기체로 질소를 공급한 경우가 공기를 공급한 경우에 비해 평균 화재 소화 시간이 확연하게 짧아지는 것으로 측정되었고, 이를 통해 미분무 뿐 아니라 공급 기체도 화재 소화 성능에 지대한 영향을 미칠 수 있음을 확인하였다.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.879-894
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• 2004

The image processing technique is simple and, in principle, can handle particles with various shapes since it is based on direct visualization. Moreover, a wide measurement area can be covered with appropriate optical arrangement. In the present paper, various techniques of image processing for sizing and counting particles are reviewed and recent developments are introduced. Two major subjects are discussed in detail: identification of particles (i.e., boundary detection and pattern recognition) and determination of in-focus criteria. Finally, an overall procedure for image processing of spray particles is suggested.

• 한국전기전자재료학회논문지
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• 제28권3호
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• pp.196-200
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• 2015

In this paper, we fabricated flexible antenna radiator using the CNT/PVDF (carbon nanotube / polyvinylidene fluoride) composite film. We used polymer film as a matrix material for the flexible devices, and introduced CNTs for adding conductivity into the film resulting in obtaining performances of the antenna radiator. Spray coating method was used to form the CNT/PVDF composite radiator, and pattern formation of the radiator was done by shadow mask during the spray coating process. We investigated the electrical properties of the CNT/PVDF composite films with the CNT concentration, and also estimated the radiator performance. Finally we discuss the feasibility of the CNT/PVDF composite radiator for the flexible antenna.

• Food Science and Biotechnology
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• 제18권1호
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• pp.185-189
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• 2009

Microencapsulation of flavor was carried out by molecular inclusion process using $\beta$-cyclodextrin (${\beta}CD$). ${\beta}CD$-flavor complex was prepared at various flavor-to-${\beta}CD$ ratios (1:6-1:12) to determine the effect of ${\beta}CD$ concentration on the inclusion efficiency. Maximum total oil retention and minimal surface oil content were obtained at flavors to ${\beta}CD$ ratio of 1:10. The physical properties and controlled release pattern of flavors from ${\beta}CD$-flavor complex were measured and compared with spray-dried microcapsules prepared using carbohydrate wall system. ${\beta}CD$-flavor complex showed higher total oil retention and surface oil contents, smaller mean particle size, lower moisture uptake, and higher oxidation stability than spray-dried microcapsule. Oxidative stability of flavor was correlated with hygroscopicity of wall materials. The controlled release mechanism was highly affected by temperature and characteristics of wall materials.

• 한국분무공학회지
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• 제2권2호
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• pp.16-23
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• 1997

In this research a novel two-reference-beam double pulse holographic technique for the measurments of particle sizes and velocities was developed. This holographic method features the capability of separation of the first and second particle images by using two reference beams instead of one and the change of the polarization direction of laser light. The developed holographic system was tested through the measurements of droplet sizes and velocities in the spray created by two high speed impinging jets. The overall spray pattern clearly revealed the inherent wave nature. Smaller and faster droplets were generated with larger impingement angle, higher jet velocity. and smaller orifice diameter.

• 한국분무공학회지
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• 제4권4호
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• pp.17-23
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• 1999

Recently, many researchers have been studied a D.I. diesel engine because of the exhaust gas restriction and fuel consumption performance. It is well known that the fuel injection characteristics are the key factors on the diesel combustion and exhaust emission. In this study, the fuel injection characteristics of 5-hole injector and the combustion characteristics are investigated with the amount of fuel by means of the visualization method and visualization D.I. diesel engine system. As the results of the experiments, the spray pattern of the fuel injection and the diffusion flame of a D.I. diesel engine are clarified. In addition, combustion phenomena with operation conditions such as engine speed and engine load are made clear.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1127-1134
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• 2002

Fine ceramic particles of zirconia toughened alumina (ZTA), titania toughened alumina (TTA), and zirconia-titania toughened alumina (ZTTA) have been synthesized by ultrasonic spray pyrolysis (USP) at various temperatures from starting salt solutio ns of various compositions aiming for the development of catalytic material. These particles were characterized for properties such as shape, size and size distribution, diffraction pattern, and chemical and phase composition of elements by scanning electron microscopy (SEM), particle size analyzer (PSA), x-ray diffraction (XRD), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Chemical compositions and sizes of ceramic composites have been controled by the stoichiometry of salt solutions and the flow rate of spraying solutions. The optimum experimental conditions for the various composite particle syntheses have been proposed.

• 약학회지
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• 제47권2호
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• pp.78-84
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• 2003

Local anesthetics are used to reduce pain, but they are so frequently injected to patients. So, we prepared lidocaine solid lipid microspheres (SLM) as long acting abdominal injection using spray drying method and evaluated drug entrapment, particle size, SEM, zeta potential and in vitro and in vivo drug release pattern, The particle sizes of SLM were 30∼100$\mu$m and it is enough to inject into abdominal tissue. The entrapment efficiency of SLM was over 95％ as spray drying method. Surfactant and PC decreased the burst effect by 20∼30％. In in vivo test, C-6 showed controlled release concentration profile in plasma for 8 days and C-5 sustained longer than we expected.