• The Journal of the Acoustical Society of Korea
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• v.12 no.1
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• pp.12-19
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• 1993

진동시험 동안 구조물은 진동시험기로부터 높은 진동에너지를 받게 되는데 공급되는 에너지를 시험물에 전달하기 위해서는 시험물에 따라 다양한 종류의 진동시험치구가 필요하게 된다. 이중에서 T-형상 진동시험치구는 진동시험축에 대해 3방향으로 시험물을 설치할 수 있고, 형상이 간단하며, 또한 값이 저렴하므로 많은 설계자들은 T-형상 치구를 설계하여 사용한다. 그러나 이 치구는 수직판이 어떤 주파수에서 평판처럼 공진현상을 일으키기 때문에 동역학적으로 설계하기가 어렵다. 본 논문에서는 진동시험치구의 기능을 향상시키기 위해 모우드 시험(Model Testing)기법을 사용하는 방법과 시험결과를 근거로 설계변경을 위해 수직보강판, 수평보강판, 그리고 천연 고무패드를 사용하여 이것들이 치구의 동특성에 미치는 영향을 기술하며 그 결과를 치구설계 때 응용 가능하도록 한다.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.606-611
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• 2015

초기 화재 진압을 위해 사용되는 스프링클러(sprinkler) 설비는 스프링클러헤드의 형태에 따라 살수 분포가 달라진다. 화점의 발생 위치는 특정하기 어려우므로 스프링클러의 살수범위(spray coverage)가 넓게 퍼지는 형태가 되는 것이 확률적으로 가장 큰 효율성을 가진다. 본 연구에서는 EDISON_전산열유체 시스템의 다상유동 해석자를 활용하여 스프링클러헤드의 형태에 따라 살수각과 국부 유동장을 분석하였다. 3차원 형상을 가지는 스프링클러헤드 형상을 2차원 단면으로 나누어 해석하였으며 프레임(frame)과 반사판(deflector)의 형상에 따른 유동장의 변화를 살펴보았고 살수각(spray angle)을 정량적으로 나타내었다. 최종적으로 최대 최소의 살수각을 갖는 2차원 스프링클러헤드를 형상화하였고 이를 중첩하여 살수 범위를 넓게 갖는 스프링클러헤드를 3차원 모델링하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.3
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• pp.327-336
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• 2016

Manufacturers of aircraft engines have introduced computer-aided manufacturing (CAM) software to operate and control computerized numerical control (CNC) machine tools. However, the generation of a CAM model is a time consuming and error-prone task since machining procedure and operational details are manually defined. For the automatic generation of a CAM model, feature recognition techniques have been widely studied. However, their recognition coverage is limited so that complex shapes such as a jet engine cannot be fully developed. This study presents a novel approach to quickly generate a CAM model from a CAD model using shape search techniques. Once an operator sets a machining operation as a reference operation, the same shapes as the shapes referenced by the operation are searched. The reference operation is copied to the positions of the searched shapes. The proposed method was verified through experiments with a jet engine compressor case.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.257-261
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• 2022

Additive manufacturing (AM, also known as 3D printing) applied to the construction industry is implemented and verified for various effects since advantages such as high design freedom, improving worker safety, and predictable construction period. However, due to the low maturity compared to the existing technology, studies are underway to solve new problems that occur in the overall of AM technology. In this paper, we confirm the effect of low construction surface flatness on the stacked features in the process of on-site AM construction. In particular, unstable AM features are determined through quantitative analysis by laser scanning, and a construction strategy is proposed for the surface flattening.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.4
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• pp.266-274
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• 2003

Distance Fourier descriptors of local target boundary and feature information fusion using multiple MLPs (Multilayer perceptrons) are proposed. They are used to identify nonoccluded and partially occluded targets in natural FLIR (forward-looking infrared) images. After segmenting a target, radial Fourier descriptors as global shape features are defined from the target boundary. A target boundary is partitioned into four local boundaries to extract local shape features. In a local boundary, a distance function is defined from boundary points and a line between two extreme points. Distance Fourier descriptors as local shape features are defined by using distance function. One global feature vector and four local feature vectors are used as input data for multiple MLPs to determine final identification result of the target. In the experiments, we show that the proposed method is superior to the traditional feature sets with respect to the identification performance.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1081-1088
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• 2022

The harmonics of synchronous generators increase iron and copper loss, which is the cause of fever. For harmonic reduction, the armature winding method is used as a distribution winding, a short pitch winding. In this paper, we want to improve the waveform of the instrument voltage by reducing the harmonics in a new way to the shape of the permanent magnet. The method cuts both ends of the permanent magnet and adjusts the air gap by increasing and decreasing the area according to the set value. By varying the distribution of magnetic flux density, the resulting electromotive voltage and strain were compared. This compares the shape-changing models of permanent magnets and shows an effective deformation method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.761-768
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• 2013

New warheads are designed and developed to be highly lethal when used as part of ballistic missile payloads. There are many trades associated with the design of a central warhead core, mainly dealing with the projectiles or penetrators. Obviously, a payload-type configuration is very susceptible to kills from one projectile because of the high impacts required for bomblet or submunition payloads. Based on these requirements, the optimum kill vehicle configuration will have the smallest mass and relative velocity that will kill all the submunitions. The designs of the penetrator shape and size are directly related to the space and weight of the warhead. The shape, size, L/D, penetrator material, and manner in which they are inserted inside the surrounding explosive segments are critical in achieving successful penetrator design. The AUTODYN-3D code was used to study the effect of penetrator penetration. The objective of numerical analysis was to determine the penetration characteristics of the penetrator produced by hypervelocity impacts under different initial conditions such as initial velocity, shape, and L/D of the penetrator.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.811-812
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• 2012

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.34-35
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• 2022

항로표지인 등부표는 항해자에게 해역환경 및 위험요소에 관한 정보전달을 위해 형상 및 광원의 섬광을 이용하고 있으며, 이때 광원의 섬광은 다양한 주기를 가지고 동작한다. 최근 주요항만에는 다양한 항만시설이 배치됨에 따라 배후광이 증가하고 있으며, 또한 복잡한 해안을 따라 다수의 항로표지들이 배치되어 있어, 등부표의 정보 전달 시인성을 높이기 위해 다양한 점멸 방식이 운용중이다. 대표적으로 동기점멸과 순차점멸 방식이 있으며, 이에 관련하여 국내외 항만 및 타분야 관련 규격 및 적용사례 등에 대해 조사 분석하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.500-506
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• 2009

This study, is aimed to support the valve design engineer by a CAE simulation on the body of a PFA-lined plug valve, and focuses on static stress analysis, location of the weak point on bending and stiffness of the valve body. To determine whether the valve body can resist being transformed by loads, 1 simulated the stress distribution using CAD/CAE softwares. The 'step' file converted by CAD software after solid modeling is imported to the CAE software. Through simulation procedure, it is shown that the designed-solid-model fur a valve body has stiffness on bending and torsion but has weakness for side bending moment. Also, it is expected that the valve design engineer will understand the basic process of CAE and will be able to apply on his task.