• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.73-76
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• 2004

Tapping mode atomic force microscopy (TM-AFM) utilizes the dynamic response of a resonating probe tip as it approaches and retracts from a sample to measure the topography and material properties of a nanostructure. We present recent results based on numerical techniques that yield new perspectives and insight into AFM. It is compared that the dynamic models including van der Waals and Derjaguin-Muller-Toporov(DMT) or Johnson-Kendall-Roberts(JKR) contact forces demonstrates that periodic solutions can be represented with respect to the approach distance and excitation frequency.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.70-76
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• 2000

In the charge system, a contact type-convenient-charging method is insufficient because of the contact failure around moist environment and troublesome question to put in and pull out. For the solution of this problem, an electromagnetically coupled non-contact charger for the rechargeable cell is proposed using ZVS multi-resonant forward converter with synchronous rectifier. In this paper coupling coefficient(k), leaking inductance, coupling inductance and resonant frequency are observed for the air gap. By using the observed value, this circuit is designed and implemented. This proposed circuit is simulated by the PSPICE and experimented. The stress of a main switch and the output power are measured.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1343-1347
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• 2006

Non-contact modal testing for longitudinal modes of a pipe is discussed in this work. The suggested method can generate and measure longitudinal vibrations without mechanical contact by using the coupling phenomenon between deformation and magnetic field, known as the magnetostrictive effect. This effect has been used to generate and measure ultrasonic waves, but seldom used to deal with audible vibrations. In this investigation, the validity of the developed method in a typical vibration frequency range is checked with an inconel pipe being used in nuclear power plants.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1483-1487
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• 2006

In electric railway, image monitoring using high speed camera provides reliable, timely information of wear and geometry status, important in taking decisions for overhead contact wire maintenance. The contribution of this research is the development of a simple real-time monitoring system for use in measurement subsystem of contact wire and geometry of overhead contact wire in electric railway. The system has been consists of a high speed CMOS camera with resolution $1024{\times}1280$ pixels, line type laser source and PC-based image acquisition system with PCI Express slot. Vision acquisition software have been used in application programming interface for image acquisition, display, and storage with a frequency of sampling of 500 acquisitions per second.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.1089-1092
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• 2004

This paper deals with the development of a contact-type counting device using a piezoelectric polymer film as a sensor. The piezoelectric and vibration characteristics of the film under a bending vibration were investigated theoretically and experimentally. A counting device, which includes filters, an amplifier, an analog-digital converter, and a display, was designed and fabricated. The performance of the piezoelectric polymer sensor was evaluated in the sense of the responses to contact force, contact frequency, and contact speed. The life and the temperature effect were also investigated for the piezoelectric film sensor.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2003년도 춘계학술대회 발표 논문집
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• pp.12-17
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• 2003

본 연구에서는 MICP Etching system 을 이용한 Via contact 및 Deep contact hole etch process 특성을 연구하였다. Langmuir probe 를 이용한 MICP source 의 Plasma density & electron temperature 측정하였고 탄소와 플로우르를 포함하는 혼합 Plasma 를 형성하여 RF frequency, wall temperature, chamber gap, gas chemistry 등의 변화에 따른 식각 특성을 조사하였다. Plasma density 는 1000w 에서 $10^{11}$/$cm^3$ 이상의 high density plasma와 uniform plasma 형성을 확인하였고 $CH_{2}F_{2}$와 CO의 적절한 혼합비를 이용하여 Oxide to PR 선택비가 10 이상인 고선택비 조건을 확보하였다. 고선택비 형성에 따라 Polymer 형성이 많이 되었고 이를 개선하기 위하여 반응 챔버의 온도 조절을 통하여 Polymer 증착 방지에 효과적인 것을 확인하였다. MICP source를 이용하여 탄소와 플로우르의 혼합 가스와 식각 챔버의 온도 조절에 의한 선택비 증가를 확보하여 High Aspect Ratio Contact Hole Etch 가능성을 확보하였다.

• 열처리공학회지
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• 제13권5호
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• pp.355-359
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• 2000

Ion beam assisted deposition system was used to deposit CNx coatings with various thickness on the substrates of high-frequency induction hardened steels. Rolling contact fatigue tests were performed using Polymet RCF-1 machine with a constant supply of lubricant. Rolling contact fatigue life was substantially different in the steels with various thickness of CNx coatings. The optimum thickness of CNx coating was found to be $8.9{\mu}m$, showing the longest fatigue life, mainly caused by higher resistance to initiation of cracks and protective overcoat remaining to the surface failure during rolling contact fatigue. Cracks were initiated in the substrates under the surface of wear track and propagated to the surface, which eventually resulted in the failure. The reduction of fatigue life observed in the specimen with elimination of CNx coating during rolling contact fatigue was explained by the substrates deformation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
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• pp.197-200
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• 1995

Corrugation of railway track can be caused by the various dynamic behavior of travelling wheels and track. In this paper, the coupled vibrations of travelling wheel and railway track are analyzed as the cause of corrugations. To analyze the coupled vibrations, the track supported by the sleepers and the traveling wheel are identified to the elastically supported infinite beam and the spring-mass system which runs at constant speed. The Hertzian contact spring is considered betwen the infinite beam and spring-mass system. The dynamic responses of elastically supported infinite beam and spring-mass system are calculated. The cause and development of rail corrugation are discussed in the view point of contact force fluctuation affected by the elastic supports and the corrugated surface profile of the track. By the obtained results, the possibilities of resonance are checked between the excitation by the corrugated surface profile and the natural frequency of contact spring-moving mass system. It may be thought to a development of railway corrugation.

• 한국안광학회지
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• 제13권3호
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• pp.19-28
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• 2008

목적: 한국인 소프트 콘택트렌즈 착용자에서 나타나는 증상을 이해하고 증상과 눈물검사값과의 상관성을 조사하고자 하였다. 방법: 안과적 질환이 없고 소프트 콘택트렌즈 착용기간이 18.60${\pm}$16.92개월인 착용자 62명(남: 20명, 여: 42명, 평균연령은 23.95${\pm}$4.38세)을 대상으로 설문지 검사 및 3 종류의 눈물검사를 시행하고, 자각적 증상과 타각적 증상을 조사하여 상관성을 분석하였다. 결과: 소프트 콘택트렌즈 착용 중 나타난 자각적 증상의 빈도와 정도는 건조감, 충혈, 피곤함의 순으로 나타났다. 증상의 빈도는 건조감은 모래가 들어간 느낌과, 충혈은 열감과, 피곤함은 이물감과 상관성이 높았고, 증상의 정도는 눈부심은 시력변동과, 이물감은 모래가 들어간 느낌의 상관성이 높았으며 이러한 증상은 McMonnies' 설문검사값과 상관성이 있었다. 타각적 증상으로 결막충혈과 윤부충혈은 병적인 수준은 아니지만 주된 증상으로 나타났고 각결막염색은 발생빈도는 낮지만 눈물막파괴시간이 짧을수록 통계적으로 유의하게 발생빈도가 증가하였다. 결론: 한국인 소프트 콘택트렌즈 착용자의 경우 건조감, 충혈 및 피곤함을 많이 느끼고 이러한 증상은 서로 상관성을 갖고 있으며 콘택트렌즈 착용기간과 상관성이 있으나 자각적 증상과 타각적 증상의 발생은 상관성이 없는 것으로 사료된다.

• 한국운동역학회지
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• 제28권3호
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• pp.159-164
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• 2018

Objective: The aims of this study were to determine the impact peak force and kinematic variables in running speed and investigate the relationship between them. Method: Thirty-nine male heel strike runners ($mean\;age=21.7{\pm}1.6y$, $mean\;mass=72.5{\pm}8.7kg$, $mean\;height=176.6{\pm}6.1cm$) were recruited in this investigation. The impact peak forces during treadmill running were assessed, and the kinematic variables were computed using three-dimensional data collected using eight infrared cameras (Oqus 300, Qualisys, Sweden). One-way analysis of variance ANOVAwas used to investigate the influence of the running speed on the parameters, and Pearson's partial correlation was used to investigate the relationship between the impact peak force and kinematic variables. Results: The running speed affected the impact peak force, stride length, stride frequency, and kinematic variables during the stride phase and the foot angle at heel contact; however, it did not affect the ankle and knee joint angles in the sagittal plane at heel contact. No significant correlation was noted between the impact peak force and kinematic variables in constantrunning speed. Conclusion: Increasing ankle and knee joint angles at heel contact may not be related to the mechanism behind reducing the impact peak force during treadmill running at constant speed.