• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.352-352
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• 2008

폐 자기회로 구조를 갖는 Meander 형태의 Inductor 설계를 위해 HFSS 프로그램을 이용하여 Meander Inductor를 시뮬레이션 하였다. Meander Inductor의 turn 수(N) 및 폭(W), 두께(T), 랩(G)의 변화에 따른 인덕턴스(L), S-parameter(S)와 Q-factor(Q)의 변화를 HFSS 를 통해 측정하였다. Al2O3 기판과 MgO의 두께는 각각 680um, 50um로 고정하였고, silver electrode를 이용하여 Meander 타입의 Inductor를 설계하였다. Meander Inductor의 turn수(6,7,8turn)의 변화를 측정한 결과, 8턴이었을 때 Q-factor가 19로서 가장 높은 결과를 얻었다. L의 결과 값은 공진 주파수와 의 관계에 의해 6turn일 때 L값은 17GHz에서 공진현상이 나타났다. 또한 W, G, T에 변화를 주어 설계한 뒤 시뮬레이션의 결과 값을 측정하였다. 그 값을 서로 비교한 결과, 변수들의 변화에 따라 L값과 Q-factor가 변화되었다. 이 논문에서는 각 변수에 따른 meander inductor의 특성을 HFSS 시뮬레이션을 통해 비교하고자 한다.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.588-594
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• 2001

본 연구를 통해 초음속 전투기 날개의 공력-구조를 동시에 고려한 다학제간 설계를 수행하였다. 공력해석을 위해 사용된 3 차원 Euler Code는 수렴 속도를 개선하기 위해 Multigrid를 적용하였으며, 3차의 transfinite interpolation을 사용하여 O-H type의 공력해석 격자계를 생성하였다. 구조 분야는 절점당 54개의 자유도를 가지는 9 절점 쉘 혼합 유한요소(9-node shell mixed finite element)를 사용하여 해석을 수행하였다. 설계변수는 공력쪽으로 날개의 평면형상에 관련된 변수 3개, 구조쪽은 날개 윗면과 아래면의 표피두께에 관련된 4개의 설계변수 사용하였으며, D-optimality 조건을 만족시키는 실험점들에 대해 공력해석과 구조해석이 연동된 정적 공탄성 해석을 수행한 후, 반응면 기법을 이용하여 목적함수와 제약조건에 대한 반응면을 구성하였다. 단일점 설계를 수행한 후 이를 바탕으로 3개의 설계점을 동시에 고려한 다점 설계를 수행하였으며, 공력만을 고려한 설계 결과와 공력-구조를 동시에 고려한 다학제간 설계결과의 비교를 통해 다학제간 설계의 타당성과 우수성을 입증하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.155-160
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• 2021

In this paper, we investigated the aptness of embroidered textile dipole antenna as a wearable antenna. We designed an 2.45GHz ISM band embroidered textile dipole antenna on polyester textile. We investigated its characteristics depends on 3 variables, thickness of textile(ttextile), distance between textile and surface of body(gbody) and conductance of surface of body(𝜎body). Thickness of textile(ttextile) was affecting on the antenna resonance frequency(fo). As the conductance of surface of body(𝜎body) was increased the antenna resonance frequency(fo) and the antenna gain were increased slightly. The increment of the distance between textile and surface of body(gbody) caused relatively large increment of the antenna resonance frequency(fo) and the antenna gain. From the results, in the case of designing an embroidered textile dipole antenna as a wearable antenna we should consider carefully the two variables, distance between textile and surface of body(gbody) and thickness of textile(ttextile). Due to its large variation, the distance between textile and surface of body(gbody) may be a technical barrier in designing embroidered textile dipole antenna.

• Journal of the Korean Magnetics Society
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• v.24 no.5
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• pp.152-159
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• 2014

Magnetic gear can transmit torque without any mechanical contact among rotational parts in rotating mechanical systems. Especially, magnetic gear using rare-earth PMs can be used in variety of industry application because of their great power efficiency. Thus, recent trend shows that magnetic gear can be replaced with common mechanical gear. This paper deals with comparison and torque analysis for magnetic gears with parallel and Halbach magnetization according to various design parameters. Using a two dimensional (2D) finite element (FE) analysis, suitable gear ratio is selected. We performed analysis for magnetically connected inner and outer torque with respect to various design parameters including thickness of inner and outer PM, steel pole angle, segments of Halbach array and magnetization pattern of inner and outer PMs. Finally, we can obtain improved design model having parallel and Halbach magnetization with larger torque, compared with an initial design model.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.121-128
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• 2016

In order to suggest a reasonable design for the circular concrete filled tube steel column-foundation connection applying high-tension bolts, Overall structural behavior and characteristics according to various variables of column-foundation connection are numerically analyzed using a commercial FE analysis program, ABAQUS. To that goal, finite element analysis is conducted on the basis of the previous study replacing anchor bolts to high-tension bolts, and the analytical results are validated by comparison with experimental results. Also, the various variables(embedded depth and grade of anchor, and height and thickness of rib) involved in behavior of the column-foundation connection are selected through analyzing the current design criteria, and the characteristics of the column-foundation connection are compared and analyzed according to the various variables. In case of the anchor bolts, Applying the high-tension bolts is more advantage and securing the embedded depth beyond 0.5D is recommendable. In case of the rib, a minimum of 0.5D for rib's height and $0.4t_b$ for rib's thickness should be secured to develop the structural performance.

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.143-152
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• 2001

This paper presents are monotonic and cyclic behavior of steel plates. The effects of design parameters, initial deflection and aspect ratio, width-thickness ratio are studied by using FEM analysis. The results obtained from the monotonic loadings show that the aspect ratio(a/b) on the strength is to be neglected in the range of $(a/b){\leq}1.0$. The major cause of the reduction in strength sbbjected to cyclic loadings are width-thickness ratio and displacement amplitude. Based on the results, this paper presents some new strength curve with considering the cyclic deteriorations. The results are also discussed about the deformation capacity accordance with the width-thickness ratio and displacement amplitude.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.834-844
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• 2000

In this study, an off-design performance analysis procedure is developed based on Two-zone model and TEIS model. In Two-zone model, there are both primary zone and secondary zone for an isentropic core flow and an average of all non-isentropic streamtubes respectively. The level of the core flow diffusion in an impeller is calculated by using TEIS model which regards the impeller as two successive rotating elements in series. At impeller exit, the mixing process occurs with an increase in entropy, that is to say, a decrease in total pressure. In loss models including Two-zone and TEIS model, some empirical parameters have a great influence on overall performance curve. So these parameters' influences on the overall performance curve are investigated and compared with experimental data.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1406-1407
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• 2006

본 논문에서는 기존의 250V급 트렌치 전극형 파워 MOSFET을 구조적으로 개선하여, 600V 이상의 순방향 항복 전압을 갖는 파워 MOSFET을 설계 하였다. 본 논문에서 제안한 구조로 기존의 250V급 트렌치 전극형 파워 MOSFET에 비하여 더욱 높은 순방향 항복 전압을 얻었다. 또한, 기존의 LDMOS 구조로 500V 이상의 항복 전압을 얻기 위해서 $100{\mu}m$ 이상의 크기를 필요로 했던 반면에, 본 논문에서 제안한 소자의 크기(vertical 크기)는 $50{\mu}m$로서, 소자의 소형화 및 고효율화 측면에서 더욱 우수한 특성을 얻었다. 본 논문은 2-D 공정시뮬레이터 및 소자 시뮬레이터를 바탕으로, 트렌치 옥사이드의 두께 및 폭, 에피층의 두께 변화 등의 설계변수와 이온주입 도즈 및 열처리 시간에 따른 공정변수에 대한 시뮬레이션을 수행하여, 본 논문에서 제안한 구조가 타당함을 입증하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.315-329
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• 2018

Recently, RC transfer slab systems have been used widely to construct high-rise wall-type apartments for securing parking space or public space. However, it is problem that the design method and structural performance evaluation method developed for thin RC flat slab are still used in the design of the transfer slab whose thickness is very thick and therefore structural behavior is expected to be different from RC flat slab. Thus, for the rational design of the transfer slab, the ultimate shear behavior of the RC transfer slab system is required to be analyzed properly. Accordingly, in the present study, the two-way shear behavior of the transfer slab was analyzed using nonlinear FEM according to various design parameters such as thickness of the transfer slab, strength of concrete, shear span ratio, and reinforcement ratio. In addition, the two-way shear strength evaluations of RC transfer slab by the existing evaluation methods were verified by comparing those with the results of nonlinear FEM analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.259-272
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• 2019

Steel-concrete single-leaf blast-resistant doors are protective structures consisting of a steel box and reinforced concrete slab. By the domestic blast-resistant doors, the structure is not designed efficiently because few studies have examined the effects of variables, such as the blast pressure, rebar ratio, and steel plate thickness on the structural behavior. In this study, the structural behavior of the doors was analyzed using the FE method, and the support rotation and ductility ratio used to classify the structural performance were reviewed. The results showed that the deflection changes more significantly when the plate thickness increases than when the rebar spacing is a variable. This is because the strain energy absorbed by the door is reduced considerably when the plate thickness increases, and as a result, the maximum deflection becomes smaller. According to a comparison of the calculated values of the support rotation and the ductility ratio, the structural performance of the doors could be classified based on the support rotation of one degree and ductility ratio of three. On the other hand, more explosion tests and analytical studies will be needed to classify the damage level.