• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.130-134
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• 1996

The characteristics of AE(Acoustic Emission) signal is related to cutting conditio, tool material, and tool geometry in metal cutting. The relation between AE signal and tool life was investigated experimentally. Experiment is carried out by gear shaping and SCM 420 workpiece. AE RMS voltage were increased according totool wear. It is suggested that maximum value of AE RMS voltage is an effective parameter to monitor tool life.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.157-165
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• 2016

In wartime conditionsmilitary combat vehicles are required to be driven on rough roads that have significant obstacles. A wheel type dog-horse robot with a rotary suspension system was applied to overcome the obstacles. To achieve real-time analysis, a simplified model was proposed by using velocity transformations. Through comparison with the multi-body dynamics model, the efficiency and accuracy of the proposed modeling was proven.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.116-121
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• 1994

지금까지 대형 구조물에 널리 사용되고 있는 Base Isolator는 특히, 지진하중에 대하여 상부 구조물의 지반분리(base isolation)을 이용한 지진제어를 목적으로 하기 때문에 Seismic Isolator라 한다. 일반적으로 면진베어링에는 LRB(Laminated Rubber Bearing) 방식과 R-FBI(resilient-friction base isolator) 방식으로 크게 나눌 수 있다. LRB 방식은 가장 널리 사용되는 면진베어링으로써 방진고무를 주된 재료로 하고 수직강성을 보강하기 위하여 steel plate를 조합하여 제작하며, 초기강성 및 에너지 소산능력을 증가시키기 위하여 단면중앙에 납(lead plug)를 삽입하기도 한다. R-FBI 방식은 방진고무 적층판 내부에 미끄럼판을 가지고 있으므로 LRB 방식에 비하여 더 큰 수평변위를 발생시킬 수 있다. 이번에 설계 제작한 면진베어링은 LNG 저장탱크의 Seismic Isolation을 목적으로 적용대상의 사양에 맞추어 설계 제작하고 성능평가 시험을 수행하여 LNG 저장탱크, 원자로, 대형 건축물등 지진으로부터 보호되어야 하는 대형구조물의 방진재로 적용할 수 있는가를 평가하고자 한다. 본 논문에서는 제작된 면진베어링의 설계를 검증하고 방진고무(HDR)재료의 물리적 특성시험, 축소모델에 의한 정적, 동적시험을 통하여 시험방법을 소개하고 이러한 시험결과를 기초로 하여 면진베어리의 성능을 평가하였으며, 면진베어링의 온도변화, 외부 수직하중의 변화등에 따른 특성변화와 LNG 저장탱크와 면진베어링의 체결방법에 따른 시험으로 체결방법을 검증하였으며, 대상물의 사양에 적합한가를 고찰하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.569-572
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• 1995

In this study, a hydraulic modulator of solenoid-flow type ABS, the master sylinder, and the wheel cylinder are modeled and simulated for increasing pressure characteristics of the brake. Response can be predicted by external force of the the master sylinder and pulses to the solenoid valve as input. For a demonstration of simulation result, experiment is done under the same condition as simulation condition after experimental apparatus of 1/4 car model is constructed. When factors of flow control valve are changed, the effect of each factor to response, how to improve response, and the most critical factors are considered from simulated result of time constant.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.2
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• pp.101-108
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• 2009

A fretting wear test rig for dry ambient condition, which employs a piezoelectric actuator, has been developed. It is driven and loaded in a very simple manner with acceptable experimental accuracy. By using the rig, Inconel 690 tube has been tested under the normal load of 10 and 15N with sliding amplitude of less than $100{\mu}m$ during $10^6$cycles. The wear resistance of the material has been characterized in terms of the wear coefficient based on the work rate model. SEM micrographs show the complex structures of the scars, which consist of risen peaks, plate-type thin layers and locally exposed bare surfaces. The cracks spread over the layers give clue to the fretting wear mechanism of the material.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.203-211
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• 2002

ABS (Anti-lock Braking System) is a safety device for preventing wheel locking in a sudden braking. It consists of hydraulic modulator, ECU(Electronic Control Unit) and angular velocity sensors. Its control methods are classified into three types; deceleration control, slip ratio control and deceleration/acceleration control. In this paper, ABS mounted vehicle is mathematically modeled and the proposed model is verified by actual cars experiments, and the braking characteristics of the control methods with pulse width modulation are compared and analyzed through computer simulations.

• Proceedings of the ESK Conference
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• 1997.04a
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• pp.61-71
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• 1997

큰 사고가 일어날 때마다 '안전관리는 그 무엇보다도 중요하다'라고 강조하지만 우리나라 안전 관리의 현 상황은 열악하다고 할 수밖에 없다. 많은 중소기업이나 심지어 대기업에서도 무의식적 으로 등한시하거나 별로 크게 중요하게 여기는 것 같지는 않은 데, 이것은 현재의 사고발생율과 강도율들을 살펴 보면 누구나 쉽게 공감할 수 있을 것이다. 이러한 맥락에서 이 논문은 안전의 또 하나의 사각지대인 호텔관련업에서의 종사원들은 과연안전에 대하여 어떤 사고방식을 가지고 있으며, 실제 그들의 안전사고는 어떤 것들이며, 안전교육의 효과는 어떠한 가 등을 중점적으로 연구하였다. 실증적 분석에서는 안전관리가 어떻게 이루어 지고 있는 가에 대한 설문조사를 통하여 조사분석하였다. 조사 표본대상으로는 우리나라의 특급 호텔4개와 1개의 콘도미니엄 종사원들을 대상으로 하여 설문지를 배포하여 총 207명에 대한 답변을 토대로 분석을 하였다. 부상내용은 칼종류에 베임이 제일 많았으며, 안전사고의 주원인은 불안전한 자세와 불안전한 행동으로서 이에 대한 교육이 요구된다. 직업과 관련된 육체적 고통으로는 만성피로가 가장 많았다. 그외 구두가 발에 피로감을 주지말 것, 주방의 미끄럼방지, VDT증후군예방, 안전체조 및 구호복창 등의 사항들을 안전사고 예방을 위해 주의해야할 사항으로 요약할 수 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.2
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• pp.241-248
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• 2013

In this study, bearings were developed for a high-power propulsion motor operating in inclined operation conditions through a simulation and similitude-experimental methods using commercial rotating machinery dynamics analysis software. The developed journal bearing is electrically insulated and has low thermal conductivity because each part is connected with 2-4 -mm-thick epoxy plates. To realize an appropriate oil thickness, an oil lift system is adopted, and a half separated structure is applied to ensure the feasibility of maintaining very heavy components. This study discusses some of the key design aspects of sleeve bearing design for high-torque and low-speed propulsion motor applications. Furthermore, the conditions of variable slope tests are examined to prevent oil leakage from the bearing lip seal on the test rig.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.95-102
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• 2011

Anti-icing system can immediately respond when snowing is expected or the snow comes down on the road surface. It has been recognized that the system can reduce traffic accidents and congestion by quickly removing the frozen road surface area. However, it is very difficult to implement this system due to the expensive equipment installation and operation cost, Recently, there was a developed program for predicting the freezing area using three-dimensional model and tracking the sun path. But, there is no objective analysis method and all developed approaches are different so that the general standard of anti-icing system is needed. In this study, we proposed the decision criteria for determining application priorities of the anti-icing system based on weather and road conditions, i.e., geometric and topographic conditions. Regional climate survey, topographical analysis, and dynamic vehicle simulation considered road geometry and skid resistance was conducted to standardize the installation method of anti-icing system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.385-393
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• 2016

This paper presents the new position estimation method which contains the optical displacement sensor and the dead reckoning based position estimation algorithm for automation of hull cleaning robot. To evaluate feasibility of the proposed position estimation method on the hull cleaning robot, it was applied on the small scale robot model which has an identical drive method with the hull cleaning robot and then a set of the position estimation experiments were performed. The experimental results of the position estimation demonstrate that the estimated results with the optical displacement sensors is more accurate than used rotary encoder method. In addition, it continuously calculated the robot position quite close to the real robot driving path. In a follow-up study, the proposed position estimation method will be complemented and exploited on the actual hull cleaning robot by adding additional sensor modules that correct measurement errors.