• Journal of the Institute of Convergence Signal Processing
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• v.18 no.1
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• pp.21-24
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• 2017

Passive millimeter wave (MMW) imaging penetrates clothing to detect concealed objects. The distances extraction to the concealed objects is critical for the security and defense. In this paper, we address a passive stereo 3 mm MMW imaging system to extract the longitudinal distance to the concealed object. The concealed object area is segmented and extracted by the k-means clustering algorithm with splitting initialization. The distance to the concealed object is estimated by the corresponding centers of the segmented objects. In the experimental two pairs (each pair for horizontal and vertical polarization) of stereo MMW images are obtained to estimate distances to concealed objects.

• Journal of the Korean housing association
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• v.23 no.3
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• pp.53-61
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• 2012

Openness to outside is one of the most critical advantages for high-rise buildings. However, the effect of openness can be decreased if it is blocked by other high-rise buildings, especially built within the building complex of commercial district. The purpose of this study is to identify the horizontal openness of high-rise residential buildings by comparing 3 different cases of building arrangement type. A new method of evaluation has been introduced on the basis of distance to measure the openness including the matter of securing privacy. As a result of this study, comparative analysis was possible and relatively plentiful results of analysis could be drawn out. Through the process of analysis, this study set the evaluation indicators suitable to the analysis of openness of unit households. Thereby, the results of this study are expected to be used as useful basic data in planning high-rise mixed-use buildings.

• Journal of Astronomy and Space Sciences
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• v.35 no.2
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• pp.83-92
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• 2018

The summer polar lower thermosphere (90-100 km) has an interesting connection to meteors, adjacent to the mesopause region attaining the lowest temperature in summer. Meteors supply condensation nuclei for charged ice particles causing polar mesospheric summer echoes (PMSE). We report the observation of meteor trail with nearly horizontal transit at high speed (20-50 km/s), and at last with re-enhanced echo power followed by diffusive echoes. Changes in phase difference between radar receivers aligned in meridional and zonal directions are used to determine variations in horizontal displacements and speeds with respect to time by taking advantage of radar interferometric analysis. The actual transit of echo target is observed along the straight pathway vertically and horizontally extended as much as a distance of at least 24 km and at most 29 km. The meteor trail initially has a signature similar to 'head echoes', with travel speeds from 20 - 50 km/s. It subsequently transforms into a different type of echo target including specular echo and then finally the power reenhanced. The reenhancement of echo power is followed by fume-like diffusive echoes, indicating sudden release of plasma as like explosive process probably involved. We discuss a possible role of meteor-triggered secondary plasma trail, such as fireball embedded with electrical discharge that continuously varies the power and transit speed.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.732-738
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• 2014

Combined optical simulation of the ray-tracing technique and the finite difference time domain method was used to investigate the effect of the emitter orientation and the photonic crystal layer on the outcoupling efficiency (OCE) of bottom-emission type organic light emitting diodes (OLEDs). The OLED with a horizontal emitter exhibited an opposite interference effect to that of one with a vertical emitter, which suggested that the OCE would be very sensitive to the emitter orientation at a fixed emitter-cathode distance. The OLED with a horizontal emitter exhibited much larger OCE than that with a vertical emitter did, which was due to the substantial difference in the radiation pattern along with the different coupling with the surface plasmon excitation. The OCE with a horizontal emitter was increased by approximately 1.3 times by inserting a photonic crystal layer between the indium tin oxide layer and the glass substrate. The present study suggested that appropriate control of the emitter orientation and its combination to other outcoupling structures could be used to enhance the OCE of OLEDs substantially.

• Journal of Welding and Joining
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• v.8 no.3
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• pp.70-78
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• 1990

The harsh nature of welding environments makes welding a prime candidate for process automation. Among the variety of welding processes available, gas metal arc welding is one of the most frequently used methods, primarily because it is highly suited to a wide range of applications, and also to automation. Automatic seam tracking method is one of the most demanded techniques for automatic control of arc welding. In this study a seam tracking system has been developed by using the welding arc itself as a sensor. This paper described the principle and experimental result of the arc sensor system, as well as the development and application of the automatic CO_2$ welding for the horizontal fillet welding. A basic problem in horizontal fillet welding is the prevention of hanging bead formation such as undercut at the vertical plate and overlap at the horizontal plate. To produce the symmetric bead shape, the relationship of bead shape to welding parameters(welding velocity, weaving width, weaving speed, tip to workpiece distance) was also investigated.

• Proceedings of the KWS Conference
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• 1996.10a
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• pp.139-141
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• 1996

Among various welding parameters, the welding current which is inversely proportional to the tip-to-workpiece distance in GMAW is an essential parameter to monitor the GMAW process of horizontal fillet joints. For the case of weld defect such as overlap in horizontal fillet welding, therefore, the signal processing for process monitoring or automatic seam tracking should be modified by considering the weld pool surface geometry including the corresponding weld defect. In other words, the adequate signal processing algorithm is indispensible to improve the performance of the arc sensor. However, arc sensor algorithm already developed usually focus on weld seam tracing but do not considering the weld qualities. In this paper, various experiments were carried out to investigate the tendencies of the weld defects when weaving motion is added, and the experimental method based on 2$^n$ factorial design was proposed for deriving the mathematical model between the leg length and the various welding conditions. Moreover, a signal processing method based on the artificial neural network(Adaptive Resonance Theory) was proposed far discriminating the current signal of sound weld beads from that of weld beads with overlap. Finally, the algorithm for weld seam tracking combined with the mathematical modeling and the signal processing method was carried out to track the weld line in conjunction with the improvement of the weld qualities. The reliability of the proposed algorithms were evaluated through various experiments, which showed that the proposed algorithms could be effectively used for arc welding automation.

• Korean Journal of Applied Biomechanics
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• v.15 no.3
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• pp.175-183
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• 2005

This study investigates the kinetic characteristics of the Driggs motion in horse vaulting by stages through the three-dimensional video analysis of YTY and TABARA who won a high score and a low score respectively from the Driggs motion in horse vaulting during the Daegu Universiade 2003, which involves putting one's hands on the horse vaulting rotating sideways, stretching and rotating backward in the air, and twisting 900 degrees, so as to help develop the techniques of Korean gymnastic athletes. From the analyses of the duration of body center, horizontality, vertical position and horizontality, vertical speed and angle factors for each of four phases from the contact of the board to the takeoff from the horse vaulting. I arrived at the following conclusions: 1. It was found that the motion of bending oneself forward while rapidly stretching the knee joint when taking off from the board increases the horizontal speed of body center and shortens the time of the first jump. 2. It was found that S1 who won a high score shortened the time of the contact and takeoff from the horse vaulting and enlarged the shoulder joint angle for full blocking motion. It was also found that horizontal speed decreased while vertical speed increased when you rapidly stretch the right elbow joint while taking off from the horse vaulting. 3. It was found that horizontal distance was shortened to increase the height and time of staying in the air during the second jump.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.1
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• pp.21-29
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• 1998

In order to investigate the fish behavior in the water tank, the three dimensional positioning system with two CCD cameras was designed. The positioning system was tested at the vertical circulation water channel with observational part of 1,500L$\times$1,500W$\times$500H mm and the circular water tank with 2,050ø sub(1)$\times$1,850ø sub(2)$\times$400H mm. The observational error of vertical direction was larger than that of horizontal direction, and the observational error became enlarged in all directions according to the increase of depth and distance from the visual axis. The maximum observational errors of horizontal and vertical directions at the circulation channel ranged from -1.7 cm to 1.8 cm (2.4%) and zero to 2.1 cm (4.2%), respectively. But the errors of horizontal and vertical directions at the circular tank ranged from -1.3 cm to 1.3 cm (1.3%) and zero to 1.3 cm (3.3%), respectively.

• Fisheries and Aquatic Sciences
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• v.27 no.2
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• pp.76-86
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• 2024

The bio-logging method could be a valuable approach to studying the underwater movement of marine fish. We investigated the horizontal and vertical movement patterns of two yellowtails Seriola quinqueradiata weighing 8.7 kg and 9.5 kg with a popup satellite archival tag from October 2020 to January 2021 in the East Sea of Korea. Our results showed that a yellowtail migrated northward in October and November, and then shifted southward in mid-December. The average swimming depth and temperature of the fish monitored over 82 days were 24.9 ± 9.3 m (average ± SD) and 16.5 ± 1.9℃, respectively, and the total traveled distance was 1,172.4 km. The fish swam significantly deeper during the daytime (33.70 ± 14.80 m) than at nighttime (20.65 ± 8.44 m) from November to December (p < 0.05). These results suggest that the horizontal migratory route of yellowtails in accordance with the East Korea Warm Current which is the main branch of Tsushima Warm Current in the fall and early winter seasons, and showed significant diel vertical movement patterns from November to December.

• Journal of Korea Foundry Society
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• v.14 no.6
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• pp.558-565
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• 1994

The horizontal continuous casting process with the heated mold was applied to obtain the unidirectionally solidified rods($4{\sim}8mm$ dia.) of pure copper with good surface quality. The results could be summarized as follows. 1. The unidirectional solidification of pure copper rods with good surface(mirror surface) quality could be obtained by placing the S/L interface inside the heated mold cavity even though the cast copper rods were covered with thin copper oxide layer. 2. The casting speed for 4mm dia. rods with mirror surfaces was affected significantly by the mold-cooler distance rather than the cooling flow rate when other casting conditions were fixed. 3. The casting speed was the main factor affecting the oxidation of copper during the continuous casting and the thickness of copper oxide layer decreased almost linearly as the casting speed increased.