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김낙철(Nag-Cheol Kim),박형준(Hyoung-Jun Park) 산업기술교육훈련학회 2020 산업기술연구논문지 (JITR) Vol.25 No.4
Through sprinkler reaction time index (RTI) characterization, the lower the RTI, the faster the sprinkler reacts to fire. The optical properties of an optical fire sensor were combined with a silicon anisotropic etching-process technique to link the fire detection and sprinkler operating time. The sprinkler motion model adopted in this study with sprinkling density was three types: RTI 350, RTI 80, and RTI 80. An optical fiber cantilever-type sensor for fire detection with V-groove support was designed and manufactured. From the analysis results of measurement factors, such as the bending degree of the optical fiber cantilever-type, the frequency variation with the beam length, and the resonant frequency, the cantilever-type sensor can be used as an optical fire sensor for fire detection linking sprinkler RTI.
김낙철(Nag- Cheol Kim),박형준(Hyeong-Jun Park) 산업기술교육훈련학회 2010 산업기술연구논문지 (JITR) Vol.15 No.3
A single-mode fiber-optic accelerometer, using silicon anisotropic etching V-grooves, has been designed and constructed. It is an amplitude-modulation sensor, which is measured with electronic instrument. The beam lengths of the fabricated fiber-optic cantilever sensor were 17㎜~19㎜. The resonance frequencies were 200㎐, 250㎐, 300㎐ respectively. According to the measurement results, the output characteristic as a function of acceleration is showed the sensitive response in below 0.3g acceleration range and is showed the insensitive response in above 0.3g acceleration range. As a study results, this fabricated sensor can be used to take physical measurements for poor electromagnetic field and biomedical environment in low frequency range.
합금공구강재의 절삭음 음향주파수 분석에 의한 엔드밀 마모 검출에 관한 연구
이창희,김낙철,Lee Chang-Hee,Kim Nag-Cheol 한국융합신호처리학회 2004 융합신호처리학회 논문지 (JISPS) Vol.5 No.4
FMS, FMC, FA, IMS의 구축에 있어서 최하위 단위인 공작기계의 자동화가 중요하다. 이를 위해서는 공작기계의 공구 감시기능(tool monitoring system)이 수행되어야 한다. 본 논문은 공구 감시기능의 자동화를 위해 종전의 공구마모 검출방법과는 달리 엔드밀의 마모상태에 따라 발생하는 절삭음의 음향주파수 분석을 통해 마모정도를 검출하는 방법을 제안하였다. 즉, 머시닝센터에서 공구마모가 잘되는 합금공구강재를 사용하고 이때 발생하게 되는 절삭음(cutting sound)을 음향 분석하여 공구 마모와 관련이 있는 가진 주파수(tooth passing frequency)를 찾아내고 또한 이 주파수의 크기 값과 공구마모(flank wear) 변화를 연구하여 엔드밀의 마모 상태를 추정하였다 이를 위해 본 연구에서는 실험 장비를 구성하고 절삭속도, 엔드밀마모, 공구직경을 절삭조건으로 하여 측정된 절삭음을 FFT 처리하였다. 또한 측정된 값을 회귀분석으로 모델링한 결과 엔드밀 마모 검출오차범위가 5.8% 이내로 나타나 음향주파수 분석에 의한 엔드밀 마모검출 방법의 유효성을 확인할 수 있었다. The wear process of end mill is a so complicated process that a more reliable technique is required for the monitoring and controling the tool life and its performance. This research presents a new tool wear monitoring method based on the sound signal generated on the machining. The experiment carried out continuous-side-milling for using the high-speed steel end mill under wet condition. The sound pressure was measured at 0.5m from the cutting zone by a dynamic microphone, and was analyzed at frequency domain. The tooth passing frequency appears as a harmonics form, and end mill wear is related with the first harmonic. It can be concluded from the result that the tool wear is correlate with the intensity of the measured sound at tooth passing frequency estimation of end mill wear using sound is possible through frequency analysis at tooth passing frequency under the given circumstances.
조명희(Myung Hee Jo),김낙철(Nag Cheol Kim),김태수(Tae Soo Kim),정현열(Hyun Yeol Chung) 한국지리정보학회 2000 한국지리정보학회지 Vol.3 No.1
지리정보시스템(GIS)을 이용한 지도정보의 검색과 공간분석에 있어서 마우스나 키보드를 이용할 경우 수 차례의 동일한 작업을 반복하여 대상지역의 범위를 지정하고 있다. 본 연구에서는 이와 같은 반복작업을 제거하여 신속한 정보검색이 가능하도록 음성인식 기능을 이용한 검색시스템을 제안하고 이를 개인용 컴퓨터상에서 구현하였다. 특히 시스템의 실용화를 위한 검색화면 제어에 있어서는 OLE(object linking embedding)기법과 MFC(Microsof In retrieving and analyzing digital map information using mouse or key strokes, it needs several times of repeated mouse operation for designating the range of study area. In this study, we proposed a voice activated map information retrieval system for e
박형준(Hyung-Jun Park),김낙철(Nag-Cheol Kim),김인수(In-Soo Kim) 한국산업기술융합학회(구. 산업기술교육훈련학회) 2022 산업기술연구논문지 (JITR) Vol.27 No.3
This study analyzes the optical characteristics of the ITO thin film deposited using DC magnetron sputtering to study the characteristics of ITO transparent electrodes for organic solar cells deposited by sputtering. For the experiments, the pressure ranged from 1–3 mTorr, and the applied voltage ranged from 260–340 V at 10 V intervals. The results of light transmittance, refractive index, and surface images were analyzed using equipment such as a spectrophotometer, an elliptical polarization analyzer, and a scanning microscope. As a result, under a pressure of at least 1 mTorr, light transmittance of at least 90% was measured, and the refractive index of the thin film had an excellent value of at least 2. Therefore, optimal conditions were established for the application of ITO transparent electrodes for organic solar cells.