• 전기학회논문지
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• 제66권8호
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• pp.1285-1290
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• 2017

In this paper, we developed a core module of the steering system to control and operate the outboard ship with the automatic steering system, and implemented it as a complete integrated system. In particular, this paper presents the problem of the rudder sensor used in the existing system and implements the contactless rudder sensor as an improvement. In the case of existing rudder sensors, there is a problem that safety operation and economic loss of the ship operation is caused by malfunction due to immersion during use in outboard vessels. However, the proposed rudder sensor is separated from the rotary shaft to constitute a contactless type, and a circular magnet is fixed so that the rotating value can be detected and used by the Hall sensor to completely solve the flooding problem. As a result of the characteristic test, the voltage value from 1.8V to 3.2V was obtained between $-35^{\circ}$ and $+35^{\circ}$ degrees and satisfied the reference value. The proposed rudder sensor was mounted on the outboard ship, and all the performance of controller system were checked. According to the system proposed in this paper, it satisfies the Korean Standard Specification, which defines the speed of convergence in 30 seconds by switching from left to right in 7 seconds. We also confirmed that automatic steering was performed by comparing the compass sensor with the destination in the integrated controller at the start-up.

• 한국소음진동공학회논문집
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• 제15권3호
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• pp.251-258
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• 2005

The free vibration of a spinning flexible disk-spindle system supported by hydro dynamic bearings (HDB) in an HDD is analyzed by FEM. The spinning flexible disk is described using Kirchhoff plate theory and von Karman non-linear strain, and its rigid body motion is also considered. It is discretized by annular sector element. The rotating spindle which includes the clamp, hub, permanent magnet and yoke, is modeled by Timoshenko beam including the gyroscopic effect. The flexible supporting structure with a complex shape which includes stator core, housing, base plate, sleeve and thrust pad is modeled by using a 4-node tetrahedron element with rotational degrees of freedom to satisfy the geometric compatibility. The dynamic coefficients of HDB are calculated from the HDB analysis program, which solves the perturbed Reynolds equation using FEM. Introducing the virtual nodes and the rigid link constraints defined in the center of HDB, beam elements of the shaft are connected to the solid elements of the sleeve and thrust pad through the spring and damper element. The global matrix equation obtained by assembling the finite element equations of each substructure is transformed to the state-space matrix-vector equation, and the associated eigen value problem is solved by using the restarted Arnoldi iteration method. The validity of this research is verified by comparing the numerical results of the natural frequencies with the experimental ones. Also the effect of supporting structures to the natural modes of the total HDD system is rigorously analyzed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.572-578
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• 2003

The free vibration of a spinning flexible disk-spindle system supported by hydro dynamic bearings in a HDD is analyzed by FEM. The spinning flexible disk is described using Kirchhoff plate theory and von Karman non-linear strain, and its rigid body motion is also considered. It is discretized by annular sector element. The rotating spindle which includes the clamp, hub, permanent magnet and yoke, is modeled by Timoshenko beam including the gyroscopic effect. The flexible supporting structure with a complex shape which includes stator core, housing, base plate, sleeve and thrust pad is modeled by using a 4-node tetrahedron element with rotational degrees of freedom to satisfy the geometric compatibility. The dynamic coefficients of HDB are calculated from the HDB analysis program, which solves the perturbed Raynolds equation using FEM. Introducing the virtual nodes and the rigid link constraints defined in the center of HDB, beam elements of the shaft are connected to the solid elements of the sleeve and thrust pad through the spring and damper element. The global matrix equation obtained by assembling the finite element equations of each substructure is transformed to the state-space matrix-vector equation, and the associated eigenvalue problem is solved by using the restarted Arnoldi iteration method. The validity of this research is verified by comparing the numerical results of the natural frequencies with the experimental ones. Also the effect of supporting structures to the natural modes of the total HDD system is rigorously analyzed.

• 산업경영시스템학회지
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• 제40권4호
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• pp.183-190
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• 2017

This paper proposes a dynamic magnetic field emulator (DMFE), which can electrically emulate information for the magnetic stripes of most widely used credit cards. Payment transactions with most common credit cards are performed by reading the card's information, encoded in magnetic stripes, using the reader head of a point-of-sale (POS) system. A stripe-type permanent magnet is attached to the back side of the credit card, and information for payments or value-added service is reorganized by exposing it to strong magnetic field. The process of data recording and retrieving as stated above has been pointed out as a major cause of illegal credit card use, because the information on the magnetic stripe is always exposed, and is thus vulnerable to forgery or alteration. A dynamic magnetic field emulator displays card information only when necessary by using the principle of solenoidal magnets. The DMFE proposed in this paper can prevent fraudulent use if it is operated with a device, like a smart phone, or a separate user-authentication procedure. In addition, because it is possible to display various information as needed, it can be utilized for a smart multi-card application, in which information for multiple cards is stored in one card, and can be selected and used as needed. This paper introduces the necessity of the DMFE and its manufacturing principles. As a result, this study will be helpful for making various application cases in payment, which is a core area of the Fintech (a newly-coined word of finance and technology) industry.

• 한국전자통신학회논문지
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• 제15권2호
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• pp.259-266
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• 2020

자기 기어는 기계식 기어와 동일하게 기어의 특성을 나타내면서 각 회전자가 접촉하지 않아 마찰에 의한 소음 및 발열, 유지보수문제에서 기계식 기어보다 유리하다. 또한 권선계자를 사용하는 회전자를 적용할 경우 기어의 출력조절은 물론, 기어비 및 위급상황에서 자체적인 구동차단까지 가능하여 자기 기어의 활용가능성은 무한하다. 하지만 권선계자를 사용할 경우 영구자석과 철심간의 흡인력에 의한 코깅토크가 나타나게 되고 이는 회전자의 진동을 유발하는 토크 리플성분의 증가로 이어진다. 따라서 본 논문에서는 권선계자를 사용하는 회전자의 토크 리플을 저감하기 위해 회전자의 다양한 형상을 분석하였으며, 자기 기어의 토크 리플을 저감하기 위한 최적의 형상을 제시하였다.

• 한국초등과학교육학회지:초등과학교육
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• 제40권3호
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• pp.326-342
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• 2021

본 연구에서는 컴퓨팅 사고의 핵심인 알고리즘 표현을 실험 활동에 적용할 수 있도록 교사를 위한 실험 안내 자료를 개발하였다. 텍스트로 제시된 실험 매뉴얼을 순서도 기호를 사용하여 정보 시각화 프로세스에 따라 직선형, 분기형, 반복형 구조의 알고리즘 형태로 변환하였다. 그 예시로, 자석의 성질을 알아보는 실험을 알고리즘 표현을 적용하여 실험 안내 자료를 개발하였다. 개발된 실험 안내 자료는 정보의 적합성과 판단 여부가 표현된 분기 및 반복의 알고리즘 구조를 가지고 있다는 점과 실험 과정을 시각화하여 표현했다는 측면에서 기존의 순차적으로 표현된 실험 안내 자료와 차이가 있다. 본 연구에서 개발된 실험 안내 자료는 교사들의 알고리즘 사고에 대한 이해와 이를 적용한 실험 실행에 도움을 줄 수 있을 것이라 기대된다.

• 전기전자학회논문지
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• 제26권4호
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• pp.596-601
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• 2022

최근 친환경 선박 전환 추세에 따라 EGR 시스템 적용이 증가되고 있다. EGR 시스템의 주요 부품 중 하나인 EGR 블로워는 공력시스템과 이를 구동하는 e-모터 및 인버터 등으로 구성되며, 에너지밀도가 높고 효율 특성이 우수한 영구자석형 동기전동기가 적용되고 있다. 한편, EGR 블로워용 모터의 경우 국내 중소조선기자재 기업들의 개발이 활발하지만, 선박에 탑재되는 인버터는 까다로운 선급인증을 획득해야 되므로 주로 글로벌 선진기업에서 개발한 범용 인버터가 사용되고 있다. 범용 인버터는 자가 튜닝 등 편리한 구동 기능을 갖고 있지만, 최적 제어 실패 시, 사용자 입장에서 원인을 분석하기 어려운 단점이 있다. 본 연구에서는 EGR 블로워용 SPMSM의 최적제어를 위한 전류 벡터 제어 및 Tracking observer를 설계 및 검증하여 범용 인버터의 최적제어 실패원인을 분석하고자 한다.

• 대한환경공학회지
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• 제34권9호
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• pp.613-622
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• 2012

본 연구에서는 MTMD의 합성을 통해 빠른 자성회수 및 재사용이 용이한 크롬 흡착제를 개발하였다. 합성을 위해 공침법 및 교대성장을 통한 발산법을 사용하였으며, methyl propionate 및 glutaric acid를 통해 덴드리머를 멀티터미널화 하였다. 합성된 시료의 특성분석은 XRD, FT-IR, TEM, EDS, TGA, Zeta potential analyzer를 통해 이루어졌다. MTMD의 자성코어는 마그네타이트 결정구조를 가졌으며, 4세대 덴드리머의 크기는 15 nm에서 20 nm로 확인되었다. TGA 분석결과 1세대 덴드리머의 유기전도성 가지의 비율은 약 7%였으며 1세대 증가시 3%의 중량 감소가 나타났고 멀티터미널화시 덴드리머의 포텐셜은 -25.26 mV에서 -6.53 mV까지 변화하였다. MTMD 흡착실험 결과 5분 이내에서 80% 이상의 크롬을 흡착하였으며 6.308 mg/g의 흡착능을 나타냈다. 자성 회수시 COOH D와 비교하여 회수시간이 2배 이상 단축되었으며 30분 이내에 100% 회수가 가능하였다. 크롬을 이용한 재생실험의 경우 4회 흡착에도 동일한 흡착능을 유지하였다.

• 대한의용생체공학회:의공학회지
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• 제26권6호
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• pp.393-398
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• 2005

An electromechanical type is the most useful mechanism in the various pumping mechanisms. It, however, requires a movement converting system including a ball screw, a helical cam, or a solenoid-beam spring, which makes the device complex and may lessen reliability. Thus, the authors have hypothesized that an electromagnetic actuator mechanism can eliminate the movement converting system and that thereby enhance the mechanical reliability and operative simplicity of an electro­pneumatic pump. The purpose of this study was to show a novel application of electromagnetic actuator mechanism in pulsatile pump and to provide preliminary data for further evaluations. The electromagnetic actuator consists of stators with a single winding excitation coil and movers with a high energy density neodymium-iron-boron permanent magnet. A 0.5mm diameter wire was used for the excitation coil, and 1000 turns were wound onto the stators core with parallel. A prototype of extracorporeal electro-pneumatic pump was constructed, and the pump performance tests were performed using a mock system to evaluate the efficiency of the electromagnetic actuator mechanism. When forward and backward electric currents were supplied to the excitation coil, the mover effectively moved back and forth. The nominal stroke length of the actuator was 10mm. The actuator dimension was 120mm in diameter and 65mm in height with a mass of 1.4kg. The prototype pump unit was 150mm in diameter, 150mm in thickness and 4.5kg in weight. The maximum force output was 70N at input current of 4.5A and the maximum pump rate was 150 beats per minute. The maximum output was 2.0 L/minute at a rate of 80bpm when the afterload was 100mmHg. The electromagnetic actuator mechanism was successfully applied to construct the prototype of extracorporeal electro­pneumatic pump. The authors provide the above results as a preliminary data for further studies.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.240-240
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• 2011

The first neutral beam injector (NBI-1) has been developed for the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. A first long pulse ion source (LPIS-1) has been installed on the NBI-1 for an auxiliary heating and current drive of KSTAR core plasmas. Performance of ion and neutral beam extractions in the LPIS-1 was investigated initially on the KSTAR NBI-1 system, prior to the neutral beam injection into the main plasmas. The ion source consists of a JAEA magnetic bucket plasma generator with multi-pole cusp fields and a set of KAERI prototype-III tetrode accelerators with circular apertures. The inner volume of plasma generator and accelerator column in the LPIS-1 is approximately 123 liters. Final design requirements for the ion source were a 120 kV/ 65 A deuterium beam and a 300 s pulse length. The extraction of ion beams was initiated by the formation of arc plasmas in the LPIS-1, called as an arc-beam extraction method. A stable ion beam extraction of LPIS-1 has been achieved up to an 100 kV/42 A for a 4 s pulse length and an 80 kV/25 A for a 14 s pulse length. Optimum beam perveance of 1.21 microperv has been found at an accelerating voltage of 80 kV. Neutralization efficiency has been measured by using a water flow calorimetry (WFC) method of calorimeter and an operation of bending magnet. The full-energy species of ion beams have been detected by using the diagnostic method of optical multichannel analyzer (OMA). An arc efficiency of the LPIS was 0.6~1.1 A/kW depending on the operating conditions of arc discharge.