• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.4
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• pp.1-8
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• 2004

The optimum design parameters of several hydraulic systems are obtained using the complex method that is one kind of constrained direct search method. First, the parameters of lead-lag controller of the direct drive servovalve is designed using the complex method to satisfy the steady-state error requirement. Second, the optimum locating point of hydraulic cylinder Is determined to minimize the cylinder force in the operation range of rotational sluice gate. For the third application case, the optimum piston area of hydraulic cylinder is determined to minimize the man power to elevate the manually operated sluice gate.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.392-395
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• 2010

최소질량형 제진장치는 초고층건물의 풍진동 제어시 질량체의 관성력을 최대한 효율적으로 이용하여 이동질량의 크기를 최소화한 제진장치라 할 수 있다. 본 연구의 최종목표는 순수 국내기술에 의한 능동제어(active control)와 수동제어(passive control)의 특성이 결합된 하이브리드 제진장치(hybrid control device)의 콘트롤러 설계기술 개발이다. 이를 위한 1차적인 목표로 여기에서는 국내에 설치된 기존의 능동진동제어장치의 전체적인 설계과정을 살펴본다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.346-347
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• 2019

본 논문에서는 3.3 [kW] on-board charger (OBC) 용 phasw-shifted full-bridge (PSFB) 컨버터의 고효율 및 고전력 밀도 달성을 위한 스위칭 주파수 설계 방안을 제안한다. 스위칭 주파수에 따라 달라지는 손실 양상 및 전력 밀도에 대해 분석하기 위해 각 스위칭 주파수 별 반도체 소자 손실과 수동 소자 손실을 계산하고, 수동 소자의 부피 변화에 따른 전력밀도 변화를 분석한다. 분석 결과를 바탕으로 고효율 및 고전력밀도 달성을 위한 시스템 설계 포인트를 선정하고 시뮬레이션을 통하여 설계 결과를 검증한다.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.450-458
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• 2019

Passive cavitation imaging method is used to observe the ultrasonic waves generated when a group of bubbles collapses. A problem with passive cavitation imaging is a low resolution and large side lobe levels. Since ultrasound signals generated by passive cavitation take the form of a pulse, the amplitude distribution of signals received across the receive channels varies depending on the direction of incidence. Both the centroid and flatness were calculated to determine weights at imaging points in order to discriminate between the main and side lobe signals from the signal amplitude distribution of the received channel data and to reduce the side lobe levels. The centroid quantifies how the channel data are distributed across the receive channel, and the flatness measures the variance of the channel data. We applied the centroid weight and the flatness to the passive cavitation image constructed using the delay-and-sum focusing and minimum variance beamforming methods to improve the image quality. Using computer simulation and experiment, we show that the application of weighting in delay-and-sum and minimum variance beamforming reduces side lobe levels.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.610-613
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• 2003

Ensuring technical ability is essential in the construction industry to increase competitiveness in the global market. A new paradigm is coming up in academic education system to cultivate the competent engineers. The major objective of this research is to suggest a positive learning pattern In order to overcome the limitations of the passive learning style. A case study, technical upgrading with a tower crane, us explained in terms of active learning process, results, and evaluation of students' performance.

• Proceedings of the Safety Management and Science Conference
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• 2004.05a
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• pp.183-190
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• 2004

가구 제품 설계 및 디자인의 과정이 고도로 높은 기술력을 바탕으로 이루어지고 있으며, 국내의 가구 기업체도 우수한 기술력과 높은 품질로 경쟁력을 키우며 다양한 고객의 요구에 대응하여 고객만족을 꾀하여야 한다. 이의 기반이 되는 제품의 품질과 사양은 설계에서 시작되는데 아직 국내의 많은 가구기업들은 설계 및 제작 단계에서 많은 시간과 비용을 낭비하고 있다. 3D Modeling Solution은 설계오류가 적으며 시각적인 설계를 할 수 있어 최소의 인력으로 제품을 설계할 수 있는 장점이 있지만 너무 많은 기능으로 인해 사용자가 쉽게 적용하고 사용하기 어려운 단점을 가지고 있다. 본 연구에서는 Autodesk사의 Inventor와 Microsoft Visual Basic으로 Inventor에서 제공하고 있는 API함수를 이용하여 조립자동화를 위한 조립조건 생성, 조립자동화, 부품 재질변경, 수동조립 그리고 부품의 DB화를 구현하고 Add-ln 기능과 미리보기 기능을 구현하였다. 그리고 Actify사의 SpinFire Professional 프로그램을 이용해서 웹에서 모델링된 가구 부품이나 제품을 볼 수 있게 하였다.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.463-470
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• 2006

이 논문에서는 신경망 제어기와 MR 댐퍼를 이용하여 지진하중을 받는 지진격리 벤치마크 구조물의 응답 감소를 위한 반능동 제어방법이 제안되었다. 제안방법 중 신경망 제어기에는 적절한 제어력을 산출하기 위해 가격함수를 기반으로한 학습 알고리즘과 간편한 민감도 계산기법이 도입되었다. MR 댐퍼가 계산되어진 제어력과 비슷한 제어력을 낼 수 있도록 clipped 알고리즘을 이용하였고, 제안된 반능동 신경망 제어방법이 지진격리 장치가 설치된 벤치마크 구조물에 적용되었다. 수치해석에서는 벤치마크 문제를 정의한 논문에서 제공된 수동제어방법이나 예시제어방법과 제안 방법의 제어성능을 비교하였다. 수치해석 결과 제안방법은 지하 변위를 약간 증가시키지만, 각층의 가속도, base shear, building corner drift 등을 매우 효과적으로 줄이는 것으로 판명되었다.

• Journal of IKEEE
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• v.14 no.3
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• pp.232-235
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• 2010

A 60GHz active phase shifter with 65nm CMOS is presented by replacing passive switches in switched-line type phase shifter with active ones. Active-switch phase shifter is composed of active-switch blocks and passive delay network blocks. The active-switch phase shifter design is compact compare with the conventional vector-sum phase shifter. Active-switch blocks are designed to accomplish required input and output impedances whose requirements are different whether the switch is on or off. And passive delay network blocks are composed of lumped L,C instead of normal microstrip line to reduce the size of the circuit. An 1-bit phase shifter is fabricated by TSMC 65nm CMOS technology and measurement results present -4dB average insertion loss and 120 degree phase shift at 65GHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2468-2474
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• 2010

The purpose of this study was to investigate the effects of taping therapy and passive range of motion exercises for the elderly aged 65 above with shoulder pain and limited of range of motion. This study was a nonequivalent control group pretest-posttest design. Data were collected about shoulder pain, range of motion, hand dexterity from 40 of elderly(exp.:20, con.:20) in B city from August to September, 2009. Collected data were analyzed using SPSS Win 12.0. Shoulder pain was significantly decreased. Range of motion which was flexion, extension, abduction, horizontal abduction. and hand dexterity were significantly increased in the taping group and PROM group. Shoulder pain and hand dextrity was non significantly between taping group and PROM group. Range of motion which was extension more increased taping group than PROM group. It was proven that taping therapy and PROM was effective for shoulder pain, articular range of motion and hand dexterity.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.3
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• pp.31-35
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• 2022

Recently, with the 4th industrial revolution, the demand for high-density semiconductors for large-capacity data processing is increasing. Researchers are interested in researching the reliability of surface mount technology (SMT). In this study, the effect of PCB pad design on assembly and adhesion reliability of passive component was analyzed using design of experiment (DOE). The DOE method was established using the pad length, width, and distance between pads of the PCB as variables. The assembly defect rate of the passive element after the reflow process was derived according to the misplacement direction of the chip resistor. The shear force between the passive element and the PCB was measured using shear tests. In addition, the shape of the solder according to the pad design was analyzed through cross-sectional analysis.