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Lock-in amplifier를 이용한 광신호 측정시스템의 reference signal에 따른 noise 감소 방법
김지훈,전수진,정태경,최영완 한국정보통신설비학회 2016 한국정보통신설비학회 학술대회 Vol.2016 No.09
Lock-in amplifier (LIA)는 미세신호를 검출할 수 있다는 장점이 있어 광센서 측정시스템으로 연구가 활발하게 진행 되고 있다. 일반적으로 LIA는 trans-impedance amplifier (TIA), phase sensitive detector (PSD), low-pass filter (LPF) 로 구성되어 있다. LIA의 dynamic reserve를 향상시키는 방법 중에서 DC성분 신호를 측정하는 방법 대신 TIA에서 noise gain이 최소화 되는 영역인 2ω 주파수 성분을 측정하는 방법이 있다. 이러한 방법을 사용하는 LIA 에서는 band pass filter (BPF)를 이용하여 PSD의 출력을 측정하기 때문에, TIA의 SNR을 향상시키기 위해서는 pass band 영역의 잡음을 감소시켜야 한다. 본 논문에서는 PSD의 출력에서의 harmonic성분을 제거하기 위해 stwp wise reference signal을 사용하여 pass band 영역의 noise spectral density를 감소시키는 방법에 대하여 제시하였다. 시뮬레이션 결과 noise spectral density가 감소함을 확인하였다.
Renewing Found Footage Filmmaking with Digital Technologies: Ken Jacobs’s Recent Digital Films
김지훈 한국영화학회 2015 영화연구 Vol.0 No.66
This paper discusses Ken Jacobs’s short and feature‐length films made with digital video since the 2000s from two perspectives. First, I investigate the ways in which Jacobs extends his celluloid‐based found footage filmmaking to the realm of digital editing in those films while also resulting in the technical and aesthetic hybridities of their images. By examining Return to the Scene of the Crime (2008) and Anaglyph Tom (Tom with the Puffy Cheeks) (2008), two digital remakes of his Tom, Tom, the Piper’s Son (1969) as a landmark found footage film based upon a variety of techniques to transform the footage of a 1905 silent film of the same title and thereby to unveil its material, technical, and aesthetic dimensions, this paper argues that Jacobs’s translation of his analytical and deconstructive special effects deployed in his original Tom, Tom in digital editing techniques serves for the historical consciousness of found footage filmmaking, which drives its filmmakers to engage with lost cinematic objects from the early history of cinema to discover their material and technical traces in the present. Second, this paper also examines the ways in which Jacobs’s embrace of digital video for reworking existing films and photographic images in the past relates to his intermedial translation of one art to another―for instance, from painting to cinema, or from his idiosyncratic projection performance (called “Nervous System”) to single‐channel moving images. To this end, I investigate Jacobs’s Capitalism: Child Labor (2007) in terms of how his techniques of manipulating a stereoscopic photograph in the 19th century invite the viewer to see its underlying historical traces while also offering her a media‐archaeological perspective on the ambivalent relation of photographic stillness to the cinema. Consequently, Jacobs’s digital films suggest that today’s found footage filmmaking as a specific mode of experimental cinema renews and expands on its traditional assets―its key aesthetics and techniques, its analytical and deconstructive approaches to the existing film, and its metahistorical commitment to the past of cinema―through its encounter with new media.
Full HD TV를 위한 효율적인 VDP SoC 구조
김지훈,김영철,Kim, Ji-Hoon,Kim, Young-Chul 한국스마트미디어학회 2012 스마트미디어저널 Vol.1 No.1
본 논문에서는 Full HD TV를 위한 화질 개선 VDP( Video Display Processor)의 SoC( System on a Chip) 구현을 위한 효율적인 하드웨어 구조를 제안한다. 제안한 구조는 SoC 설계의 한 방법으로써 효율적인 버스 구조와 유연성 있는 인터페이스를 지원하여 실시간 비디오 처리를 가능하게 한다. VDP를 구성 하고 있는 비디오 IP 들은 고화질 영상 제공 및 화질 개선을 위한 목적으로 설계 되었고, 각각의 IP는 실시간성 보장 및 SoC의 하드웨어 통합을 위해서 Avalon 인터페이스가 사용되었다. 이는 설계시간을 단축하고, IP 검증과 특히 SoC를 구성하는데 있어서 IP 추가 삭제 및 변경 등이 용이함으로써 사용자의 편리성을 높여준다. 또한 SoC의 임베디드 소프트웨어는 실시간으로 비디오 세부 항목 설정 및 데이터 전송 방식 설정 등을 제어할 수 있음으로써 유연성 있는 실시간 처리 시스템을 구현할 수 있다. VDP의 SoC 구현은 CyclonIII SoPC(System on a Programmable Chip) 플랫폼 상에서 구현되었으며, 실험 결과 SD 해상도의 입력 영상을 Full HD 해상도로 변환시킴으로써 고화질 영상을 획득 할 수 있다. This Paper proposes an effective SoC hardware architecture implementing a VDP for Full HD TVs. The proposed architecture makes real time video processing possible with supporting efficient bus architecture and flexible interface. Video IP cores in the VDP are designed to provide a high quality of improved image enhancement function. The Avalon interface is adopted to guarantee real-time capability to IPs as well as SoC integration. This leads to reduced design time and also enhanced designer's convenience due to the easiness in IP addition, deletion, and revision for IP verification and SoC integration. The embedded software makes it possible to implement flexible real-time system by controlling setting parameter details and data transmitting schemes in real-time. The proposed VDP SoC design is implemented on Cyclon III SoPC platform. The experimental results show that our proposed architecture of the VDP SoC successfully provides required quality of Video image by converting SD level input to Full HD level image.
김지훈,김광민,박한울,이창수,남승원,임경준,정지영,홍성주,이철균 한국생물공학회 2021 Biotechnology and Bioprocess Engineering Vol.26 No.2
Salt stress can be used to increase intracellular lipid content of microalgae. However, the growth of microalgae is decreased under salt stress. Thus, a two-stage cultivation strategy with a growth phase followed by a stress stage is required to improve lipid content. In this study, adaptive laboratory evolution (ALE) with salt stress was conducted to improve biomass and fatty acid (FA) productivity using a locally isolated freshwater microalga Parachlorella sp. in a single-stage cultivation. Algal cell growth and FA production under conditions of salt stress (0 - 40 g of NaCl/L) were compared to those in a 0.5 L bubble column photobioreactor and appropriate levels of salt stress (10 and 20 g/L) were determined for ALE. During the ALE process, the average cell size increased from 3.0 to 3.9 μm. After eight consecutive ALE cycles, microalgal growth rate was remarkably increased to close to that of the culture without salt stress. Furthermore, FA content in microalga was improved from 7.5% to 25%. This result was confirmed by observations with various types of microscopes. Eventually, overall FA productivity was increased up to 219.0 ± 10.7 mg/L/day with the addition of 20 g of NaCl/L, which was 233% greater than that of the culture without salt stress (93.8 ± 5.3 mg/L/day) due to increased FA content. Recovered biomass productivity was 80% of that in the culture without salt stress. These results suggest that microalgal FA production can be significantly improved by a simple ALE process without an additional stress culture step.