• Title/Summary/Keyword: Photo Current

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A Study on the Characteristic of High Voltage Type Instantaneous Current Source for Laser Printer (Laser 프린터용 고압 순시 전류제어형 전원특성에 관한 연구)

  • 채영민;조종화;권중기;한상용
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.2
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    • pp.105-111
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    • 2004
  • In this paper, a new self-oscillated type high voltage power supply for the OPC(Organic Photo Conductor) charge is proposed, which has variable constant current source characteristics to improve the charge characteristic of the OPC roller. The proposed control method enables high quality printing characteristics regardless of the circumstance change such as ambient temperature or humidity by changing the current reference signal. To verify the proposed control method various experiments are performed.

Development of a Smartphone based Photo-realistic Virtual Reality Exposure Therapy System (스마트폰을 이용한 사진 기반 가상 현실 노출 치료 시스템 개발 및 시험적 적용)

  • Park, Jonghyeon;Park, Jin-young;Kim, Kwanguk Kenny
    • Journal of the Korea Computer Graphics Society
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    • v.22 no.3
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    • pp.75-87
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    • 2016
  • Virtual reality exposure therapy (VRET) has been used for a several decades. However, we are not aware any studies that used a smart-phone based virtual reality techniques. In this study, we suggested a new smart-phone based VRET that included photorealistic techniques. We also evaluated the current system with 32 healthy participants, and results suggested that the current system evoked different emotional valences in indoor/outdoor and familiar/unfamiliar environments. The meaning of current results and potential applications of VRET were discussed.

A Study of Electrical Characteristics of Nano-Structural Monolayers (나노구조 단분자막의 전기적 특성 연구)

  • Song, Jin-Won;Shin, Hoon-Kyu;Lee, Kyung-Sup;Choi, Yong-Sung
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.55 no.12
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    • pp.586-590
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    • 2006
  • Dendrimers represent a new class of synthetic macromoleculcs characterized by a regularly branched treelike structure. Multiple branching yields a large number of chain ends that distinguish dendrimers from conventional star-like polymers and microgels. The azobenzene dendrimer is one of the dendrimeric macromolecules that include the azo-group exhibiting a photochromic character. Due to the presence of the charge transfer element of the azo-group and its rod-shaped structure, these compounds are expected to have potential interest in electronics and photoelectronics, especially in nonlinear optics. In the present paper, we give pressure stimulation to organic thin films and detect the induced displacement current. Functional photoisometrization organic molecular the photo-stimulus to organic monomolecular L films and LB films of dendrimer and 8A5H were performed. The 8A5H organic monolayer in case of pressure stimulus occurred that positive course but in case of the photo-stimulus compared positive and negative. It is assumed that generation forms of displacement current were measured when photo-stimulus for impression.

The development of photo-diode dosimeter(PD-2000) for the diagnostic X-ray Energy (X선 진단영역 에너지 측정을 위한 Photo-Diode 선량계(PD-2000)의 개발)

  • Kim, Sung-Chul;Lee, Woo-Chul;Kim, Jung-Min
    • Journal of radiological science and technology
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    • v.23 no.2
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    • pp.27-32
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    • 2000
  • It was produced radiation dosimeter used photo-diodes for which ionization by x-ray was applied and evaluated the value of utility in clinics as compared with ion-chamber. The result obtained were as follows : 1. Comparison of ion-chamber with photo-diode dosimeter's x-ray output by the change of x-ray tube voltage, and the ratio of ion-chamber to diode was $0.96{\sim}1.02$ which was not affected by x-ray beam quality. 2. The ratio of ion-chamber to diode was 0.96 by change of tube current and 0.97 by change of exposure time that is not affected by x-ray quantity. 3. The ratio of ion-chamber to diode was $0.97{\sim}1.04$ by thickness and $0.93{\sim}1.10$ by radiation field that is little affected by second ray quantity. 4. Reproducibility of photo-diode dosimeter was 0.011(CV) and it is a good result. 5. Photo-diode dosimeter was affected by the surface angle of detector over 30 degrees. Produced dosimeter was small, light, and meets good result compared with ionization chamber. It was expected come into wide use in clinic.

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A Study on the Effects of the Optical Characteristics of backlight Sources on the Photo Leakage Currents of a-Si:H Thin Film Transistor (비정질 실리콘 TFT의 광누설 전류에 Backlight 광원의 광학적 특성이 미치는 영향에 대한 연구)

  • Im, S.H.;Kwon, S.J.;Cho, E.S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.04a
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    • pp.55-56
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    • 2008
  • The photo leakage currents of a conventional hydrogenated amorphous silicon(a-Si:H) thin film transistor(TFT) were investigated and analyzed in the case of illumination from various lightsources such as halogen lamp, cold cathode fluorescent lamp(CCFL) backlight, and white light emitting diode(LED) backlight The photo leakage characteristics showed the apparent differences in the leakage level and in the $I_{on}/I_{off}$ ratio in spite of the similar luminances of light sources. This leakage level is expected to be related to the wavelength of the lowest intensity peak from spectral analysis of light sources.

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Smart LCD using a-Si photo sensor

  • Hong, Sung-Jin;Kim, Jin-Hong;Shin, Kyung-Ju;Chai, Chong-Chul;Choi, Jung-Ye;Park, Cheol-Woo;Suk, Jun-Hyung
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.280-284
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    • 2005
  • Recently, the demands of the high quality LCD display device have increased. We have developed the smart LCD that photo sensor is integrated in. Amorphous silicon TFTs have photo leakage current characteristics when the channel of TFTs are lighted on. This characteristic has applied in our device. We expect that photo sensor integrated LCDs have lots of merits in mobile display device, note PC panel and LCD TV.

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A Study on the Effects of the Optical Characteristics of Backlight Sources on the Photo Leakage Currents of a-Si:H Thin Film Transistor (비정질 실리콘 TFT의 광누설 전류에 Backlight 광원의 광학적 특성이 미치는 영향에 대한 연구)

  • Im, Seung-Hyeok;Kwon, Sang-Jik;Cho, Eou-Sik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.9
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    • pp.844-847
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    • 2008
  • The photo leakage currents of a conventional hydrogenated amorphous silicon(a-Si:H) thin film transistor(TFT) were investigated and analyzed in case of illumination from various light sources such as halogen lamp, cold cathode fluorescent lamp(CCFL) backlight, and white light emitting diode(LED) backlight. The photo leakage characteristics showed the apparent differences in the leakage level and in the $I_{on}/I_{off}$ ratio in spite of the similar luminances of light sources. This leakage level is expected to be related to the wavelength of the lowest intensity peak from the spectral characteristics of light sources.

Photo-triggered Theranostic Nanoparticles in Cancer Therapy

  • Abueva, Celine DG.
    • Medical Lasers
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    • v.10 no.1
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    • pp.7-14
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    • 2021
  • In cancer therapy, it is often desirable to use precision medicine that involves treatments of high specificity. One such treatment is the use of photo-triggered theranostic nanoparticles. These nanoparticles make it possible to visualize and treat tumors specifically in a controlled manner with a single injection. Several novel and powerful photo-triggered theranostic nanoparticles have been developed. These range from small organic dyes, semiconducting and biopolymers, to inorganic nanomaterials such as iron-oxide or gold nanoparticles, carbon nanotubes, and upconversion nanoparticles. Using photo-triggered theranostic nanoparticles and localized irradiation, complete tumor ablation can be achieved without causing significant toxicity to normal tissue. Given the great advances and promising future of theranostic nanoparticles, this review highlights the progress that has been made in the past couple of years, the current challenges faced and offers a future perspective.

Self-aligned Offset Gated Poly-Si TFTs by Employing a Photo Resistor Reflow Process (Photo Resistor Reflow 방법을 이용한 오프셋 마스크를 이용하지 않는 새로운 자기 정합 폴리 실리콘 박막 트랜지스터)

  • Park, Cheol-Min;Min, Byung-Hyuk;Han, Min-Koo
    • Proceedings of the KIEE Conference
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    • 1995.07c
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    • pp.1085-1087
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    • 1995
  • A large leakage current may be one of the critical issues for poly-silicon thin film transistors(poly-Si TFTs) for LCD applications. In order to reduce the leakage current of poly-Si TFTs, several offset gated structures have been reported. However, those devices, where the offset length in the source region is not same as that in the drain region, exhibit the asymmetric electrical performances such as the threshold voltage shift and the variation of the subthreshold slope. The different offset length is caused by the additional mask step for the conventional offset structures. Also the self-aligned implantation may not be applicable due to the mis-alignment problem. In this paper, we propose a new fabrication method for poly-Si TFTs with a self-aligned offset gated structure by employing a photo resistor reflow process. Compared with the conventional poly-Si TFTs, the device is consist of two gate electrodes, of which one is the entitled main gate where the gate bias is employed and the other is the entitled subgate which is separate from both sides of the main gate. The poly-Si channel layer below the offset oxide is protected from the injected ion impurities for the source/drain implantation and acts as an offset region of the proposed device. The key feature of our new device is the offset lesion due to the offset oxide. Our experimental results show that the offset region, due to the photo resistor reflow process, has been successfully obtained in order to fabricate the offset gated poly-Si TFTs. The advantages of the proposed device are that the offset length in the source region is the same as that in the drain region because of the self-aligned implantation and the proposed device does not require any additional mask process step.

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Risk Factors Related to Photo Couplers(P/C) for Signal Transmission by Electronic Devices (전자기기의 신호전송을 위한 Photo Couplers(P/C) 의 위험 요소 발굴)

  • Park, Hyung-Ki;Choi, Chung-Seog
    • Journal of the Korean Society of Safety
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    • v.28 no.2
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    • pp.26-30
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    • 2013
  • The purpose of this study is to find risk factors by analyzing the operation principle of a photo coupler (P/C) used to remove the noise of electronic devices and establish a base for the performance improvement of developed products. It was found from the P/C circuit analysis of normal products that they were equipped with an electrolytic condenser of $0.1{\mu}F$ to smooth system signals. Due to the epoxy resin packing the external part of the P/C, this study experienced a limit to visually examine the damage to it. It could be seen from the analysis of electric characteristics of the P/C that the forward voltage ($V_f$) and reverse current ($I_r$) were 1.3 V and 10 uA, respectively. In addition, it is required that the breakdown voltage (VCE) between the collector (C) and emitter (E) be maintained at less than 35 V. The and of the damaged product #1 were comparatively good. However, the measurement of was 100.0 uA. From this, it is thought that a short circuit occurred to the internal circuit. Moreover, from the fact that the of the damaged product #2 was open circuit and the measurement of was 0.0 uA, it is thought that the collector and emitter was separated or insulation resistance was significantly high. Furthermore, from the fact that the of the damaged product #3 was open circuit and the measurement of was 0.0 uA, it is thought that the space between the collector (C) and emitter (E) failed to meet the design standard or that they were separated. Therefore, it is thought that fabricating the P/C by increasing the reverse current 10 mA to 50 mA will prevent its malfunction.