• Journal of the Korean Society for Precision Engineering
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• v.31 no.2
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• pp.113-117
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• 2014

Laser Assisted Machining (LAM) was often used in process of difficulty-to-cut materials. In previous study, Laser assisted machining was a straight path processing using 1-axis manipulator in laser module. But 1-axis manipulator in laser module was able to process only straight path. So, in this study, laser module in laser assisted machining equipped to 2-axis manipulator. 2-axis manipulator has two motors. First motor is machining direction motor and second motor is Vertical Motor. Machining direction motor rotates in the direction of machining and vertical motor rotates vertical direction in the direction of machining. Machining path of laser assisted machining was considered diagonal path and curved path of laser heat source. This study calculated the 2-axis manipulator's rotation angle in diagonal path and curved path.

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.412-421
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• 2018

The Line array sonar consisting of several hydrophones increases array gain and improves the performance for detecting the direction of the target compared to single hydrophone. However, line array sonar produces the bearing error that makes it difficult to determine the bearing of incoming source signal due to the relation between bearing angle of target and vertical angle of multipath signals. Vertical angles of multipath are varied with the geometry of receiver and target and various underwater environments, therefore it is necessary to consider the bearing error to estimate accurately the bearing of the target. In this study, acoustic modelling was performed to understand the effect of multipath signals on the target signal. The errors of bearing angle estimated from the bottom bounced signals are calculated with several environment. In addition, the expected bearing line, as a function of source-receiver range, compensated for the bearing error is predicted from the estimated bearing angle.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.2
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• pp.65-74
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• 2021

This study aims to assess the effect of postulated seismic loads on the structural integrity of a spent nuclear fuel dry storage facility. Firstly, three-dimensional modal and response spectrum analyses were carried out. With regard to the latter analysis, the effect of incident angles against two horizontal and one vertical response spectra was also considered. Results showed that even though two critical locations were predicted at the longitudinal axis central part of upper flow path as well as the end discontinuity part of upper and lower flow paths connector, their maximum principal stress values were less than the tensile strength. Moreover, since the influence of vertical angle was 87% higher than that of horizontal angle in particular, which should be carefully handled to demonstrate integrity of the facility.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.173-176
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• 1998

The surface wave launcher from the dielectric coated coaxial cable to dielectric slab is investigated. FDTD method using local subcell and contour-path model is applied to determine the fine geometrical features. The reflection coefficient in coaxial cable region is found using extract algorithm. In this paper, two structures are presented as coaxial slot surface wave launcher. One structure has a vertical launching angle, and the other has an arbitrary launching angle. The numerical results show that a certain launching angle is minimized the reflection coefficient.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1131-1137
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• 2015

Gallium nitride (GaN) is a promising material for next-generation high-power applications due to its wide bandgap, high breakdown field, high electron mobility, and good thermal conductivity. From a structure point of view, the vertical device is more suitable to high-power applications than planar devices because of its area effectiveness. However, it is challenging to obtain a completely upright vertical structure due to inevitable sidewall slope in anisotropic etching of GaN. In this letter, we design and analyze the enhancement-mode n-channel vertical GaN MOSFET with variation of sidewall gate angle by two-dimensional (2D) technology computer-aided design (TCAD) simulations. As the sidewall slope gets closer to right angle, the device performances are improved since a gradual slope provides a leakage current path through the bulk region.

• The korean journal of orthodontics
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• v.13 no.2
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• pp.131-146
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• 1983

Faces of normal occlusion, open bite and class III malocclusion were measured using cephalogram in 190 male and female subjects. Using M.K.G., types of mandibular movement, amount of horizontal and vertical movement were studied in relation to occlusal types, and were compared with each other. The following conclusions were obtained. 1. Movement of protrusion was most different in relation to occlusal type. 2. In normal occlusion, maximal protrusion were horizontal 7.66mm, vertical 3.01mm in male, 6.41, 2.92mm respectively in female and maximal inferior position were -24.32, 33.63mm in male,-23.48, 32.27mm respectively in female. 3. Angle between maximal inferior position and horizontal plane were $53.51^{\circ}$ in male, $53.84^{\circ}$ in female. 4. Generally, amount of mandibular movement was greater in male than female. 5. In open bite, path of protrusion was nearly straight without curve $69.2\%$ in male, $70.2\%$ in female. 6. In class III malocclusion, angle and amount of protrusion were smaller than normal occlusion and path was directed anterior-superiorly in $22.7\%$. 7. There was no correlation coefficient between measurement of face and mandibular movement.

• ETRI Journal
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• v.45 no.5
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• pp.746-757
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• 2023

This study presents a novel safe landing algorithm for urban drone deliveries. The rapid advancement of drone technology has given rise to various delivery services for everyday necessities and emergency relief efforts. However, the reliability of drone delivery technology is still insufficient for application in urban environments. The proposed approach uses the "landing angle control" method to allow the drone to land vertically and a rapidly exploring random tree-based collision avoidance algorithm to generate safe and efficient vertical landing paths for drones while avoiding common urban obstacles like trees, street lights, utility poles, and wires; these methods allow for precise and reliable urban drone delivery. We verified the approach within a Gazebo simulation operated through ROS using a six-degree-of-freedom drone model and sensors with similar specifications to actual models. The performance of the algorithms was tested in various scenarios by comparing it with that of stateof-the-art 3D path planning algorithms.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.468-473
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• 2012

Cost is an important aspect in designing a target drone, however the poor performance of low cost IMU, GPS, and microcontrollers prevents the use of complex algorithms, such as ARS, or INS/GPS to estimate attitude angles. We propose an autopilot which uses rate gyro and GPS only for a target drone to follow a prescribed path for anti-aircraft training. The autopilot consists of an altitude hold, roll hold, and path following controller. The altitude hold controller uses vertical speed output from a GPS to improve phugoid damping. The roll hold controller feeds back yaw rate after filtering the dutch roll oscillation to estimate the roll angle. The path following controller operates as an outer loop of the altitude and roll hold controllers. A 6-DOF simulation showed that the proposed autopilot guides the target drone to follow a prescribed path well from the view point of anti-aircraft gun training.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.2
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• pp.9-15
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• 2014

'Visual segment surface' means a surface that extends from the missed approach point of non precision approaches (or the decision altitude location for approaches with vertical guidance and precision approaches) to the threshold to facilitate the identification of and protection from obstacles in this visual segment of the approach. Validation is the necessary final quality assurance step in the procedure design process, prior to publication. The purpose of validation is the verification of all obstacle and navigation data, and assessment of flyability of the procedure. This paper shows how to apply the protection for the visual segment of the approach procedure, and the results of the validation for visual segment surface conducted at an airport.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.18 no.1
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• pp.167-176
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• 1988

This study was designed to evaluate the morphology of the temporomandibular joint components and dentofacial characteristics of patients with clicking and painful temporomadibular joint. The materials consisted of 80 conventional pantomographs in normal an symptomatic individuals aged 18-23 and divided into 2 groups by symptom of temporomandibular joint. The results were as follows; 1. In morphologic analysis of condylar head, type Ⅰ (anterior, posterior smooth curve) was most dominant in both group(58.75%, 55.0%) and asymmetrical condylar shape was predominant in symptomatic group (18 cases, 45%). 2. In symptomatic group, the condylar width were slightly lesser and the ratio of condylar height to height of condyle-ramus were larger than those of normal group. 3. Vertical overlap of central incisor of symptomatic group was slightly larger than that of normal group. There was significant differences between each group in mandibular midline deviation. 4. The symptomatic group tended to steep mandibular plane angle and the degree of condylar path and condylar axis of normal group were larger than those of symptomatic group. 5. The condylar width was inversely correlated with inclination of condylar path and inclination of condylar path was correlated with condylar axis in both groups.