• Korean Journal of Geomatics
• /
• v.1 no.1
• /
• pp.69-74
• /
• 2001

In conventional photogrammetry, three-dimensional coordinates are obtained from two consecutive images of a stationary object photographed from two exposure stations, separated by a certain distance. However, it is impossible to photograph moving objects from two stations with one camera at the same time. Various methods to overcome this obstacle were devised e. g. taking the left and right scenes simultaneously with one camera using a beam splitter attached to the front, thus creating a stereo scene in one image. A beam splitter consists of two outer mirrors and two inner mirrors. This paper deals with research where the optical principles of the beam splitter were evaluated based on light path phenomena between the outer mirrors and the inner mirrors. A mathematical model of the geometric configuration was derived for the beam splitter. This allows us to design and control a beam splitter to obtain maximum scale and maximum base-height ratio by stepwise application of the mathematical model. The results show that the beam splitter is a very useful tool for stereophotography with one camera. The optimum geometric configurations ensuring maximum scale and base-height ratio are closely related to inner and outer reflector sizes, their inclination angles and the offsets between the outer mirrors.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.33 no.4
• /
• pp.278-283
• /
• 2017

Purpose: The aim of this study was to evaluate the interdental distances of anterior, premolar, and molar teeth at the cementoenamel junction (CEJ) and 2 mm below the CEJ in healthy natural dentition with cone-beam computerized tomography (cone-beam CT) in order to provide valuable data for ideal implant positioning relative to mesiodistal bone dimensions. Materials and Methods: Two hundred patients who visited Dental Hospital, Wonkwang University, who had natural dentition with healthy interdental papillae, and who underwent cone-beam CT were selected. The cone-beam CT images were converted to digital imaging and communication in medicine (DICOM) files and reconstructed in three-dimensional images. To standardize the cone-beam CT images, head reorientation was performed. All of the measurements were determined on the reconstructed panoramic images by three professionally trained dentists. Results: At the CEJ, the mean maxillary interdental distances were 1.84 mm (anterior teeth), 2.07 mm (premolar), and 2.08 mm (molar), and the mean mandibular interproximal distances were 1.55 mm (anterior teeth), 2.20 mm (premolar), and 2.36 mm (molar). At 2mm below the CEJ, the mean maxillary interdental distances were 2.19 mm (anterior teeth), 2.51 mm (premolar), and 2.60 mm (molar), and the mean mandibular interproximal distances were 1.86 mm (anterior teeth), 2.53 mm (premolar), and 3.01 mm (molar). Conclusion: The interdental distances in the natural dentition were larger at the posterior teeth than at the anterior teeth and also at 2 mm below the CEJ level compared with at the CEJ level. The distances between mandibular incisors were the narrowest and the distances between mandibular molars were the widest in the entire dentition.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.644-647
• /
• 1996

In this study the theoretical minimum resolution analysis of an active vision system using laser range finder is performed for surrounding recognition and 3D data acquisition in unknown environment. The laser range finder consists of a slitted laser beam generator, a scanning mechanism, CCD camera, and a signal processing unit. A laser beam from laser source is slitted by a set of cylindrical lenses and the slitted laser beam is emitted up and down and rotates by the scanning mechanism. The image of laser beam reflected on the surface of an object is engraved on the CCD array. In the result, the resolution of range data in laser range finder is depend on distance between lens center of CCD camera and light emitter, view and beam angles, and parameters of CCD camera.

• Proceedings of the KIEE Conference
• /
• 1993.11a
• /
• pp.356-358
• /
• 1993

With a focused laser beam, we make a microscopic change on a thin film, and organize the overall system that can observe the change with a microscope. This system utilizes the energy of a laser beam which is focused by a simple lense system. That is a laser beam which has its waist at working distance of a lense. The microscopic change induced by the energy of laser beam focused through a lense can be observed in real time. The experiment with this system shows that the 10mW He-Ne 632.8nm laser can change the black vinyl instantaneously.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.10 no.1
• /
• pp.39-45
• /
• 2014

This paper proposes an architecture of a sensor network for gathering data under a powerful beam cluster tree architecture. This architecture is used when there is a need to gather data from sensor node where there is no sink node connected to an existing network, or it is required to get a series of data specific to an event or time. The transmit distance of the beam signal is longer than that of the usual sensor node. The nodes of the network make a tree network when receiving a beam message transmitting from the powerful root node. All sensor nodes in a sink tree network synchronize to the superframe and know exactly the sequence value of the current superframe. When there is data to send to the sink node, the sensor node sends data at the corresponding allocated channel. Data sending schemes under the guaranteed time slot are tested and the delay and jitter performance is explained.

• Journal of electromagnetic engineering and science
• /
• v.10 no.4
• /
• pp.224-230
• /
• 2010

Wireless power transmission (WPT) is useful technology in near future. There are some kinds of the WPT technologies, WPT via radio waves, resonance coupling, and inductive. Especially the WPT via radio waves is used for multi-purposes from short range to long range application. However, unfortunately it is misunderstood that it is low efficiency and low power. In this paper, I show the theory of beam efficiency between transmitting antennas and receiving antennas and also show some high efficient applications of the WPT via radio waves. Especially, I pick up a wireless power charging system of an electric vehicle and show the experimental results. I show difference between the theory of beam efficiency and the experimental results of short range WPT. I indicate that reasons of poor beam efficiency in the experiment are (1) change of impedance caused by mutual coupling between transmitting antennas and receiving antennas, (2) oblique direction of microwave power to receiving antennas caused by short distance.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.6
• /
• pp.163-167
• /
• 2007

A field emission electron gun including 3 electrodes including one cathode and two anodes is very important for high resolution electron microscope. To have functions to control the initially-emitted electron beam, two anodes act as an electrostatic lens according to equipotential lines by adjusting the spot size, intensity, and working distance. To verify the action of the electron beam by the electrostatic lens by changing several parameters such as electrode shape, displacement and applied voltage to the electrodes, the two lenses were design and simulated and then their performances were analyzed with angular beam intensity(distribution), electrical optic axis variation and their stability.

• International Journal of Korean Welding Society
• /
• v.3 no.2
• /
• pp.7-14
• /
• 2003

During the manufacture of a ship, longitudinal deformation is produced by fillet welding on the Built­Up beam used to improve the longitudinal strength of a ship. This deformation needs a correcting process separate from a manufacture process and decreases productivity and quality. This deformation is caused by welding moment, which is the value multiplied the shrinking force due to welding by the distance from the neutral axis on a cross section of Built­Up beam. This deformation can be offset by generating a moment which is the same magnitude with and is located in an opposite direction to the welding moment on web plate by induction heating. Accordingly, this study clarifies the creation mechanism of the longitudinal deformation on Built­Up beam with FEM analysis and presents the preventative method of this deformation by induction heating basing the mechanism and verifies its validity through analysis and experiments. The induction heating used here is performed by deciding its location and quantity with experiments and simple equations and by applying them to a real structure.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.35 no.1
• /
• pp.26-30
• /
• 2009

Background and Objectives: To determine the anatomic position of the inferior alveolar nerve (IAN) canal in patients with mandibular prognathism using the cone-beam CT (CBCT). Materials and Methods: Fifty rami from 25 patients were evaluated. The images were taken by i-CAT and reconstructed 3-dimensionally using the Simplant 11 program. The linear distances between the IAN canal to the buccal cortex (a, $a^{\dag}$ and $a^{\ddag}$), from the IAN canal to the alveolar crest (b and $b^{\dag}$) and the anterior margin ($b^{\ddag}$) and finally the buccal cortical thickness (c, $c^{\dag}$ and $c^{\ddag}$) were measured at three reference planes (VP, OP and HP). Results: On the left side, the average distance of a, b and c were 7.12, 15.96 and 3.60 mm on the VP plane, respectively. On the OP, the distance of $a^{\dag}$, $b^{\dag}$ and $c^{\dag}$ was 6.11, 8.83 and 2.63 mm. For the HP, the distance of $a^{\ddag}$, $b^{\ddag}$ and $c^{\ddag}$ was 4.84, 10.11 and 2.30 mm. On the right side, the distance of a, b and c, on the VP, was 7.10, 16.13 and 3.42 mm, respectively. On the OP, the distance of $a^{\dag}$, $b^{\dag}$ and $c^{\dag}$ was 4.77, 8.75 and 2.68 mm. On the HP, the distance of $a^{\dag}$, $b^{\dag}$ and $c^{\ddag}$ was 4.55, 9.84 and 2.38 mm. Regarding the difference between genders, the distance in male's was longer than female's on the VP (p=0.019), and was thicker in males than females on the HP (p=0.002). Conclusion: The CBCT data provided accurate information about the location and course of the IAN.

• Journal of Korea Multimedia Society
• /
• v.21 no.2
• /
• pp.181-187
• /
• 2018

Line-laser beams are used for depth measurement of welding beads along the circumference of a pipe. For this, first we project a line-laser beam on an rotating pipe and take a sequence of images of the beam projected on the pipe using a CCD camera. Second, the projected line laser beam in each image is detected, converted into a thin curve. Finally measure the distance between the thinned curve and an imaginary line. When a line-laser beam is projected to a rough metal surface such as arc welding beads, the beam is severely scattered. This severe scattering makes the thinned curve perturbed. In this paper, we propose a thinning method robust against scattering of line lasers. First, we extract a projected line laser beam region using an adaptive threshold. Second, we model a thinned curve with a spline curve with control points. Next, we adjust the control points to fit the curve to the projected line-laser beam. Finally, we take a weighted mean of thin curves on a sequence of image frames. Experiments shows that the proposed thinning method results in a thinning curve, which is smooth and fit to the projected line-laser beam with small error.