• Fire Science and Engineering
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• v.29 no.4
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• pp.33-38
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• 2015

Loads applied on the floor are transferred through beams to columns. The beams can be designed as both end fixed or simple beams. The load bearing capacity of a beam depends on each boundary condition. However, when the load bearing capacity of a beam is evaluated in fire tests, all kinds of beams are tested using simple beam conditions. In this study, an analytical method performed using heat transfer theory and heat stress analysis based on the mechanical and thermal properties of SS-400 steel at high temperature. This method was used to clarify the differences between the two types of boundary conditions at normal and high temperature. The results show that the load bearing capacity of a both-end fixed beam at high temperature is superior to that of a simple beam. Therefore, the application of simple beam conditions in fire tests for evaluation of load bearing capacity is conservatively safe compared to fixed boundary conditions.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.83-84
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• 2012

본 연구는 3상 농형 유도전동기 보다 많은 특성을 가지는 다상 교류전동기의 구동 시스템 연구를 위하여 개발된 5상 3.0Kw 내부장착 영구자석 릴럭턴스 동기전동기(PMA-RSM)의 설계 및 제작에 대한 내용이다. 전동기 설계에는 Maxwell 2D/3D와 Simplorer의 EM Package 및 전동기 해석 프로그램을 활용하였다. 설계된 5상 PMA-RSM의 고정자와 회전자 구조의 특성과 제작된 전동기의 형태를 보여준다. 또한 고정자 권선방법으로 채택된 집중권에 대한 자계의 FEM 해석 결과와 기초적인 운전특성을 보여 준다.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.219-220
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• 2012

본 연구는 3상 보다 많은 장점을 가지는 다상 교류전동기를 연구하기 위하여 개발된 5상 1.5Kw 220V, 60Hz 농형 유도전동기의 특성 개선에 대한 연구결과이다. 연구용으로 개발된 5상 전동기는 정격운전에서 전압변동률, 속도변동률, 역율, 효율 및 운전특성 등이 많이 저하 되어 이에 대한 문제점의 개선를 요구하고 있었다. 이에 따라 기존에 개발된 고정자와 회전자의 철심 코아의 구조는 변화 하지 않고 그대로 고정된 상태를 유지하면서, 고정자 권선의 재설계와 제작을 되풀이하는 시행오차 법에 의해 최적의 전동기를 설계 제작하여 정밀 시험을 통하여 운전특성이 개선된 연구결과를 보여준다. 제시되는 특성실험 결과는 무부하시험, 구속시험, 부하특성실험, FFT 고조파 분석, 전동기의 정수 결정 및 등가회로이다.

• Computational Structural Engineering
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• v.11 no.3
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• pp.155-164
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• 1998

이 논문은 변단면을 고려한 수평 곡선보의 자유진동에 관한 연구이다. 진동시 곡선보 요소에 작용하는 합응력과 관성력의 동적평형방정식을 이용하여 변단면 원호형 수평 곡선보의 자유진동을 지배하는 상미분방정식을 유도하였다. 이 미분방정식을 원형 단면을 갖는 선형변변단면에 적용하여 고유진동수, 진동형 및 합응력을 산출하였다. 수치 해석예에서는 양단고정 및 양단회전 곡선보를 채택하였으며, 수치해석 결과로서 고유진동수와 단면비, 세장비 및 중심각 사이의 관계를 그림에 나타내었다. 또한 실험실 규모의 실험을 통하여 본 연구결과의 타당성을 보였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.417-425
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• 2007

The differential quadrature method(DQM) is applied to computation of eigenvalues of the equations of motion governing the free out-of-plane vibration for circular curved beams including the effects of rotatory inertia and transverse shearing deformation. Fundamental frequencies are calculated for the members with clamped-clamped end conditions and various opening angles. The results are compared with exact solutions or numerical solutions by other methods for cases in which they are available. The DQM provides good accuracy even when only a limited number of grid points is used.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.501-504
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• 1999

과거 벡터 제어의 모델링에 있어 무시되어온 철손의 영향이 최근 여러 논문들에서 연구되어졌으며, 이의 영향이 적지 않음이 밝혀졌다. 본 논문은 속도 센서리스에서의 철손으로 인한 영향을 보상, 직접 회전자 자속 제어와 직접 고정자 자속 제어에 적용하였다. 또한 센서리스 제어에서의 철손의 영향과 그 보상 방법을 보여주며, 시뮬레이션을 통해 이러한 제안의 타당성을 보인다.

• Journal of the Korean Arthroscopy Society
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• v.9 no.2
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• pp.167-173
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• 2005

Purpose: The purpose of this study is to evaluate the clinical results of posterior cruciate ligament (PCL) and posterolateral structure (PLS) reconstruction using bilateral hamstring tendon autografts. Materials and Methods: From October 2002 to March 2004, ten patients were received PCL and PLS reconstruction simultaneously using bilateral hamstring autografts. PCL was reconstructed using ipsilateral hamstring tendon and fixed with cross pins and Intrafix (Mitek, Norwood, MA). PLS was reconstructed using contralateral hamstring tendon. The mean follow up was 17 months. Clinical assessments consisted of Lysholm knee scores, International Knee Documentation Committee (IKDC) evaluation form and posterior stress radiographs. External rotation of tibia was evaluated at $30^{\circ}\;and\;90^{\circ}$ knee flexion using Noyes and Barber-Westin's classification. Contralateral harvest site morbity was evaluated using IKDC evaluation form and flexion power of the knee. Results: Mean posterior displacement of tibia using stress radiographs was improved from 13.3 mm to 3.7 mm. In tibial external rotation evaluation, 7 patients were functional, 2 patients were partially functional and one failure. The average Lysholm knee score improved from 54 preoperatively to 86 postoperatively. At the final IKDC evaluation, 8 patients were graded as nearly normal, 2 were graded as abnormal. In contralateral harvest site morbidity evaluation, 2 patients complained of numbness around the wound but negligible. Conclusion: PCL and PLS reconstruction using bilateral hamstring autografts was considered as a good treatment method with minimal contralateral harvest site morbidity.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.85-86
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• 2012

본 연구는 일반적으로 많이 사용되고 있는 단상 또는 3상 유도전동기 보다 많은 특성을 가지는 5상 1.5Kw 220V, 농형 유도전동기를 개발한 연구결과의 내용이다. 전동기 설계 방법에는 Maxwell 2D와 전동기 해석 및 설계 프로그램을 활용 하였다. 설계된 5상 농형 유도전동기의 고정자와 회전자 및 외형의 결과와 제작된 전동기의 형태가 제시 되었다. 5상 고정자 권선은 집중권을 채택하였으며, 이에 따른 제3 고조파 성분의 영향을 이론적으로 해석 하였으며, 시뮬레이션 결과와 실제 시스템의 운전특성을 보여준다.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.4
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• pp.437-442
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• 2014

Recently, the needs for the development and application of the micro marine robot (MMR) which has the advantages in terms of size and cost are increasing. However, the basis is very short in the domestic. While the obstacle avoidance sonar (OAS) which was optimized in terms of size and performance and has the ability of 4-directional detection was developed for the obstacle avoidance of the micro surface robot (MSR) fortunately, the problem that the detection performance is degraded according to the shape of the obstacle because of using the fixed sonar-beam with the limited beam width and detection range exists. To solve this problem, the MSR mechanism that implements the rotating sonar-beam using the spur gear and the servo motor is proposed in this paper. To verify the performance of the proposed mechanism, the wall-tracking of the MSR is considered and the comparison and analysis in term of detection performance and actuation command is performed with conventional fixed sonar-beam. The test results show the validity of the proposed mechanism.

• Journal of Korean Society of Steel Construction
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• v.15 no.5 s.66
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• pp.551-559
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• 2003

In steel frames, the analysis and design techniques are based on either idealized fixed or pinned connections. In this case, it has the advantage that the structural analysis and the design procedure were simplified, but there could be given different results of analysis between the real steel frame connections and the idealized fixed and pinned connection. This is because the real connections would be analyzed by semi-rigid, and have some transfer of moment and rotational constraint about the loads. In this study, structural analysis program with considered connections that have joint rigidity of fixed, pinned and semi-rigid, was developed. Then, the effects of joint rigidity on strength and displacement. in steel frames subjected to lateral forces and axial forces, were investigate, and the results were compared with those of the Midas Gen. w program.