• Laser Solutions
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• v.12 no.2
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• pp.26-30
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• 2009

Scanning Electron Microscopy (SEM) includes high voltage generator, electron gun, column, secondary electron detector, scan coil system and image grabber. Column includes electron lenses (condenser lens and objective lens). Condenser lens generates fringe field, makes focal length and control spot size. Focal length represents property of lens. Objective lens control focus. Most of the electrons emitted from the filament, are captured by the anode. The portion of the electron current that leaves the gun through the hole in the anode is called the beam current. Electron beam probe is called the focused beam on the specimen. Because of the lens and aperture, the probe current becomes smaller than the beam current. It generate various signals(backscattered electron, secondary electron) in an interaction with the specimen atoms. In this paper, we describe the result of research to develop the core elements for low-resolution SEM.

• Journal of Plant Biology
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• v.32 no.2
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• pp.121-134
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• 1989

This research is the palynotaxonomic revision to clarify palynological descriptions and relationships of taxa in Korean Verbenaceae. To do this, morphology, size, sculpture and aperture of pollen grain were investigated with scanning electron microscope. As a result, palynological key as to 5 genera 10 species drawn up. Palynological descriptions of Callicarpa dichotoma, Callicarpa mollis, Callicarpa chejuensis, Vitex chinensis and Caryopteris incana are near completion at first. Vervena officinalis are newly described and descriptions of Callicarpa japonica, Clerodendrum trichotomum, Vitex rotundifolia and Caryopteris divaricata are corrected. Palynological data of Korean Verbenaceae is useful to intrageneric relationships. Namely, as to genus Callicarpa, C. dichotoma and C. japonica are considered to be more advanced than C. mollis and C. chejuensis. As to genus Caryopteris, C. divaricata is more advanced than C. incana.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.635-639
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• 2003

When we carry out acoustic holography, step-by-step measurement provides us larger aperture size with same number of microphones. But when we carry out step-by-step measurement, it is blown that sound signal must be stationary. However, when transfer function between input and output signal is time-invariant, we can apply step-by-step measurement to acoustic holography even if sound signal is transient We have to do only some Processing on signals from step-by-step measurements to make the signal data of each step compatiable with other steps. This paper accounts for that processing method.

• Proceedings of the IEEK Conference
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• summer
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• pp.19-22
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• 2004

The goal of this study is to realize the PBG lowpass filter using novel PBG structure modification both upper layer and ground layer. It has been designed three aperture slots of ground layer for PBG structure which the center slot shape of ground is two type, rectangular and dumbbell. This PBG LPF has the character of the broader stopband and smaller size than typical LPF. The measurement results have matched the simulated ones. It has the cutoff frequency of each 4.465GHz and 3.52GHz and at least -20dB of the signal suppression at the stopband

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.411-414
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• 2009

We report single and two-stacked WOLED. Two-stacked WOLED structure adopts fluorescent blue EML and phosphorescent (red+green) EML. Current efficiency, EQE and color coordinate of two-stacked WOLED are 54.5cd/A, 28.8% and CIExy (0.322, 0.345), respectively. Those of single WOLED are also 20cd/A, 10% and CIExy (0.29, 0.37), respectively. Dual-plate OLED Display (DOD) employing the single WOLED shows high aperture ratio up to 67% in 2-inch panel of which pixel size is equivalent to that of 32 inch Full HD.

• Archives of Pharmacal Research
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• v.2 no.1
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• pp.1-8
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• 1979

The flow rate of various sand through circular orifice can be measured from a knowledge of a few easily measurable properties of the system. These are the orifice column and particle diameters, the angle of inclination of the orifice with the horizontal and an angle of repose of the granular sand material. Straight lines were obtained when the logarithm of the flow rate was plotted versus the logarithm of orfice diameter. No influence of excessive compaction and bed height was observed and the flow rate increased with decrease of particle diameter. The profile of flow developed the edge of the aperture in a way independent of its size. Linear relationship was observed between the angle of inclination of the orifice and the flow rate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.740-742
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• 2005

In the past, a mobile phone had only a function of communication. Recently, new functions such as an mp3 player and a camera are added in a mobile phone. For the application of a camera module to a mobile phone, the size of the camera module needs to become smaller than a general Digital Camera. Furthermore, it is also required that the performance of the camera module in a mobile phone be the same as that of a Digital Camera. In order to fulfill these requirements, the camera module should have functions such as Auto Focus, Zoom, the shutter and the aperture. Therefore, we introduce a simple and effective actuator and propose the shutter composed of solenoid.

• Korean Journal of Optics and Photonics
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• v.12 no.5
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• pp.382-388
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• 2001

KITSAT-3, launched at May 26 1999, has an earth observation optical payload named MEIS (Multi-spectral Earth Imaging System). The MEIS is a Managin mirror telescope of aperture size of 95mm, and it images the ground with the ground sampling distance of 13.8m over 48km at the altitude of 720km using three different observations bands. This paper first presents the design and then the optics, relating results of manufacturing, integration and test. Finally it briefly discusses the current status of MEIS operation.

• Korean Journal of Remote Sensing
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• v.38 no.4
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• pp.375-386
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• 2022

The city of Khartoum, the capital of Sudan, was heavily damaged by the flood of the Nile in 2020. Classification using satellite images can define the damaged area and help emergency response. As Synthetic Aperture Radar (SAR) uses microwave that can penetrate cloud, it is suitable to use in the flood study. In this study, Random Forest classifier, one of the supervised classification algorithms, was applied to the flood event in Khartoum with various sizes of the training dataset and number of images using Sentinel-1 SAR. To create a training dataset, we used unsupervised classification and visual inspection. Firstly, Random Forest was performed by reducing the size of each class of the training dataset, but no notable difference was found. Next, we performed Random Forest with various number of images. Accuracy became better as the number of images in creased, but converged to a maximum value when the dataset covers the duration from flood to the completion of drainage.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.144-145
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• 2021

Variable range of focal length of Moiré lens is designed to change the phase pattern, which is varifocal lens system using two thin layers with Moiré pattern and suitable to applied to AR/VR system because of the relatively simple structure, large aperture size, and wide variable range. We analyze the change of focal length region according to the phase pattern and verify the design to make the prototype patterns using DOE.