• 한국전자파학회논문지
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• 제18권5호
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• pp.563-568
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• 2007

본 논문에서 제안된 패키지 안테나는 900 MHz RFID 대역에 적용하기 위하여 미엔더 라인과 단락 핀을 부설하고 LTCC(Low Temperature Cofired Ceramic) 층의 공동 내부에 RFID BGA(Ball Grid Array) 칩을 장착하였다. BGA 칩과 안테나 사이에 발생되는 커플링과 혼신을 감소시키기 위한 격리 특성을 확보하기 위하여 접지면과 비아 펜스를 부설하여 Faraday Cage를 구현하였다. 제안된 안테나는 낮은 주파수 대역에서 패키지 단계의 안테나 구현에 관점을 두었다. 제안된 안테나의 크기는 $13mm{\times}9mm{\times}3.51mm$이며, 측정된 안테나의 공진 주파수는 0.893 GHz, 임피던스 대역폭은 9 MHz, 최대 방사 이득은 -2.36 dBi를 나타내었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.674-679
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• 2000

Designing of the squirrel cage AC Traction Motor has many difficulties which has to be small size in order to be suitable into bogie frame, high efficiency and light weight. It means that induction motor for tractive purpose has to be different magnetic and electric loading ratio from industrial induction motor. This paper is devoted to an examination of how this ratio affects overall design concept and hence the main design points for traction motor. Also studied is tile changed coefficients of the magnetic and electric loading ratio squirrel cage induction motor for the traction purpose which has been already identified from tile reference book for industrial purpose induction motor.

• 조명전기설비학회논문지
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• 제25권11호
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• pp.58-66
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• 2011

In this paper, the starting torque and efficiency characteristics of the induction motor (IM) for the electric vehicle (EV) are improved by changing the slot shapes of squirrel cage. The initial model of the induction motor is designed by the loading distribution method (LDM), and then the rotor with squirrel cage of NEMA class A is selected to optimize the slot shape by response surface method(RSM). The design variables of rotor slot shape are obtained by the RSM. Starting torque and efficiency were calculated by the equivalent circuit method. As a result, starting torque and efficiency of the optimized model shows good performance through whole-speed range.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.702-704
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• 2000

Designing of the squirrel cage AC Traction Motor has many difficulties which has to be small shape in order to be suitable into bogie frame, high efficiency and light weight. It means that induction motor for tractive efforts has to be different magnetic and electric loading ratio from industrial induction motor. This paper is devoted to an examination of how this ratio affects overall design concept and. hence the main design points for traction motor. Also studied is the changed coefficients of the magnetic and electric loading ratio squirrel cage induction motor for the traction purpose, which has been already identified from the referance book for industrial purpose induction motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.929-931
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• 1993

The design sensitivity analysis based on the finite element method is presented for the eddy current problem with a voltage source. Since, in this problem, the complex variable is used as the state variable, new approach to the sensitivity calculation for the complex variable system is required. Its result is applied to the design of the rotor slot shape of squirrel cage induction motor. As a analysis model, only one slot pitch of rotor is analyzed by using a Periodic boundary condition. The use of this minimal modelling method leads to much saving of calculation time. The design objective is to obtain the desired slip-torque characteristic. Because the shape of rotor slot has much influence on the slip torque characteristic, the design variables are taken on the interface shape between rotor core and rotor bar. The initial shape of rotor slot is the trapezoidal type with rounding corners. The obtained final shape is quite similar to the double squirrel cage type.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권1호
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• pp.34-38
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• 2005

The finite element method is very flexible for new shapes and provides flux distribution, magnetomotive force, eddy currents, and torques. However, it requires lengthy computational time in order to achieve desired accuracy. The magnetic equivalent circuit method takes less computation time than the finite element method. Therefore, the finite element method is mainly used to confirm the completed design. The magnetic equivalent circuit method is convenient for complicated analysis of the transient state of the induction motor. The magnetic equivalent circuit method is restricted to only one direction of magnetic flux. In this paper, the construction elements (that is, stator iron, rotor iron, yoke, air gap, etc.) of the squirrel cage induction motor were represented by a flux tube and the air gap magnetomotive force was calculated by the magnetic equivalent circuit method. Starting transient torque and phase current of the squirrel cage induction motor were verified by the theoretical calculation and the experiment.

• Ocean Systems Engineering
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• 제7권2호
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• pp.143-155
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• 2017

For complex flexible structures such as nets, the determination of drag forces and its deformation is a challenging task. The accurate prediction of loads on cages is one of the key steps in designing fish farm facilities. The basic physics with a simple cage, can be addressed by the use of experimental studies. However, to design more complex cage system for various environmental conditions, a reliable numerical simulation tool is essential. In this work, the current load on a cage is calculated using a Morison-force model applied at instantaneous positions of equivalent-net modeling. Variations of solidity ratio ($S_n$) of the net and current speed are considered. An equivalent array of cylinders is built to represent the physical netting. Based on the systematic comparisons between the published experimental data for Raschel nets and the current numerical simulations, carried out using the commercial software OrcaFlex, a new formulation for $C_d$ values, used in the equivalent-net model, is presented. The similar approach can also be applied to other netting materials following the same procedure. In case of high solidity ratio and current speed, the hybrid model defines $C_d$ as a function of Re (Reynolds number) and $S_n$ to better represent the corresponding weak diffraction effects. Otherwise, the conventional $C_d$ values depending only on Re can be used with including shielding effects for downstream elements. This new methodology significantly improves the agreement between numerical and experimental data.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제5권9호
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• pp.247-260
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• 2016

센서네트워크는 스마트홈, 스마트 팩토리 등 다양한 분야에서 센서 데이터 기반으로 활용되고 있다. 이러한 센서네트워크는 그 활용 분야에 따라 시스템 아키텍처, 요구사항, 설계 등이 달라지게 된다. 현재 해양 환경은 지상 환경에 비해 접근하기가 굉장히 어렵고 높은 파고, 안개, 염분 등의 열악한 조건을 가지고 있어 센서네트워크의 응용분야가 굉장히 적은 단점이 있다. 따라서 본 논문에서는 연근해 가두리 양식장 모니터링을 위한 센서네트워크 시스템의 요구사항 분석과 아키텍처를 제안하고 이를 기반으로 연근해 가두리 양식장 모니터링을 위한 시스템을 설계한다. 또한 본 논문에서 설계한 시스템에 대해 실제 개발을 통해 운용하면서 얻은 결과를 제시한다. 본 연구를 기반으로 개발한 시스템은 연근해 가두리 양식을 위해 수집한 수중 데이터를 중심으로 양식에 필요한 각종 연관성 분석을 통해 가두리 양식에 적합한 수중 환경조건을 도출하고, 모니터링 및 관리할 수 있는 기능을 제공한다.

• Journal of Korean Neurosurgical Society
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• 제60권6호
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• pp.611-619
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• 2017

Objective : In addition to bone bridging inside a cage or graft (intragraft bone bridging, InGBB), extragraft bone bridging (ExGBB) is commonly observed after anterior cervical discectomy and fusion (ACDF) with a stand-alone cage. However, solid bony fusion without the formation of ExGBB might be a desirable condition. We hypothesized that an insufficient contact area for InGBB might be a causative factor for ExGBB. The objective was to determine the minimal area of InGBB by finite element analysis. Methods : A validated 3-dimensional, nonlinear ligamentous cervical segment (C3-7) finite element model was used. This study simulated a single-level ACDF at C5-6 with a cylindroid interbody graft. The variables were the properties of the incorporated interbody graft (cancellous bone [Young's modulus of 100 or 300 MPa] to cortical bone [10000 MPa]) and the contact area between the vertebra and interbody graft (Graft-area, from 10 to $200mm^2$). Interspinous motion between the flexion and extension models of less than 2 mm was considered solid fusion. Results : The minimal Graft-areas for solid fusion were $190mm^2$, $140mm^2$, and $100mm^2$ with graft properties of 100, 300, and 10000 MPa, respectively. The minimal Graft-areas were generally unobtainable with only the formation of InGBB after the use of a commercial stand-alone cage. Conclusion : ExGBB may be formed to compensate for insufficient InGBB. Although various factors may be involved, solid fusion with less formation of ExGBB may be achieved with refinements in biomaterials, such as the use of osteoinductive cage materials; changes in cage design, such as increasing the area of polyetheretherketone or the inside cage area for bone grafts; or surgical techniques, such as the use of plate/screw systems.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.705-713
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• 2021

케이지 조립체는 발사대의 사격 플랫폼 역할을 하므로 목표물에 대한 사격 정확성을 확보하기 위한 정확한 조준이 필수적이다. 그러나 천무 발사대의 방향성 오류로 인한 케이지의 비정상적인 회전으로 장비에 대한 품질 문제가 지속적으로 발생하였다. 이러한 무기체계의 품질문제는 우리 군의 전력 손실에 큰 영향을 미칠 수 있다. 본 연구에서는 현재 운용중인 천무 발사대 케이지의 방향성 오류 현상을 대상으로 결함 고찰 및 원인분석을 수행하여, 개선방안을 도출하였다. 또한 케이지 방향 결정 신호 흐름 구성 분석을 통해 방향성 오류 발생이 가능한 예상 원인을 모두 도출하여 소프트웨어 방어 설계를 통해 방향성 상실 문제를 완전 차단하고자 하였다. 본 연구를 통해 데이터의 불특정한 신호를 방지하여 레졸버의 신호오류를 개선하였다. 또한 데이터의 왜곡을 최소화하기 위하여, 방향성 판단방식을 개선하였다. 마지막으로 케이지 회전방향에 대한 데이터가 저장오류나 통신오류로부터 영향을 받지 않도록 방향성 저장공간과 확인방식을 개선하였다. 개선사항에 대한 신뢰성은 체계 적용성 검증을 수행하여 입증되었다. 본 연구는 향후 유사무기체계에 대한 고장분석 및 설계에 참고자료가 될 것으로 기대된다.