• 한국환경농학회지
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• 제34권3호
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• pp.210-216
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• 2015

BACKGROUND: In korea, sweet persimmon(Diospyros kaki) cultivation is front to abiotic stresses such as frost damage at fruit maturing stage. The cold and rapid freezing stresses are most damaging to fruit production which is most actively progressed in late fall. This study was performed to evaluate the validity of chlorophyll fluorescence imaging(CFI) technology to determine the degree of frost damage in sweet persimmon fruits. METHODS AND RESULTS: The sweet persimmon fruits were measured separately for each treatment(15, 30, 60 minutes) at 24 hours after treatment(HAT) rapid freezing. A CFI FluorCam (FC 1000-H, PSI, Czech Republic) was used to measure the fluorescence images of the fruits. In rapid freezing for 15 minutes, photochemical parameters were not changed. However, in rapid freezing for 30 and 60 minutes, photochemical parameters were lowered. Especially, $F_m$, $F_v$, $F_v/F_m$ and ${\Phi}PSII$ values were declined under rapid freezing. CONCLUSION: In our study, it was clearly indicated that the rapid freezing could be a stress in sweet persimmon fruits. The CFI analysis and its related parameters are applicable as a rapid assessing technique for the determination of frost damage.

• 보존과학회지
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• 제35권3호
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• pp.237-244
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• 2019

본 연구에서는 우리나라 근대시기 유화 작품 3점('소년', '소녀', '혜화동풍경')에 테라헤르츠 이미징 기법을 활용하여 추출 가능한 작품 내부 정보의 종류와 이를 추출하기 위한 분석 조건을 연구하였다. 또한 테라헤르츠 스캔 적용 시 대상 작품의 굴곡에 따라 분석 대상 표면과 검출부 사이의 거리가 변화되어 발생하는 이미지 왜곡이 주된 문제점임을 파악하고, 이를 보완하기 위한 방법으로 '작동 거리 유지 장치'를 고안하였다. 연구 결과, 테라헤르츠 이미징 기법을 이용하여 유화의 바탕재 특성과 내부의 손상형태를 파악할 수 있음을 확인하였고 각 특성을 확인할 수 있는 최적의 조건을 제시하였다. 바탕재의 특성과 하부층 확인에는 테라헤르츠 주파수 분해 이미지를 활용하는 것이 유용하였으며 붓터치 등 채색기법을 파악하는 것에는 최대 반사피크 이미지와 단면 이미지가 효과적이었다. 또한 표면에서 관찰할 수 없는 작품 내부 손상 정보는 단면 이미지와 주파수 분해 이미지를 비교하는 것이 유용하였다. 회화작품에 적용한 결과, '소년'과 '소녀'에서는 내부의 구조적 손상 자국을, '혜화동풍경'에서는 작가의 채색 방식을 확인하였다. 이상의 결과는 우리나라 근대기 유화의 예방보존 및 보존처리를 위한 상태분석 및 진단에 활용될 수 있을 것으로 기대된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.546-548
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• 2010

This paper proposes a new baseline-free TR-based SHM method in which the time-reversal (TR) property of the guided Lamb waves is utilized. The new TR-based SHM method has two distinct features when compared with the other existing SHM techniques: (1) The measurement- based backward TR process is replaced by the computation-based process (2) In place of the comparison method most commonly used for SHM, the TOF information of the damage signal extracted from the reconstructed signal is utilized for the damage diagnosis. For the damage diagnosis, the imaging method is adopted to efficiently detect damage by representing the damage as an image. The proposed TR-based SHM technique is then validated through the damage diagnosis experiment for an aluminum plate with a damage at different locations.

• 한국정밀공학회지
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• 제27권6호
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• pp.64-74
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• 2010

This paper proposes a new TR-based baseline-free SHM technique in which the time-reversal (TR) property of the guided Lamb waves is utilized. The new TR-based SHM technique has two distinct features when compared with the other TR-based SHM techniques: (1) The backward TR process commonly conducted by the measurement is replaced by the computation-based process; (2) In place of the comparison method, the TOF information of the damage signal extracted from the reconstructed signal is used for the damage diagnosis in conjunction with the imaging method which enables us to represent the damage as an image. The proposed TR-based SHM technique is then validated through the damage diagnosis experiment for an aluminum plate with a damage at different locations.

• Journal of the Optical Society of Korea
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• 제20권1호
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• pp.78-87
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• 2016

Red blood cells (RBCs) are customarily adhered to a bio-functionalised substrate to make them stationary in interferometric phase-imaging modalities. This can make them susceptible to receive alterations in innate morphology due to their own weight. Optical tweezers (OTs) often driven by Gaussian profile of a laser beam is an alternative modality to overcome contact-induced perturbation but at the same time a steeply focused laser beam might cause photo-damage. In order to address both the photo-damage and substrate adherence induced perturbations, we were motivated to stabilize the RBC in OTs by utilizing a laser beam of ‘arbitrary intensity profile’ generated by a source having cavity imperfections per se. Thus the immobilized RBC was investigated for phase-imaging with sinusoidal interferograms generated by a compact and robust Michelson interferometer which was designed from a cubic beam splitter having one surface coated with reflective material and another adjacent coplanar surface aligned against a mirror. Reflected interferograms from bilayers membrane of a trapped RBC were recorded and analyzed. Our phase-imaging set-up is limited to work in reflection configuration only because of the availability of an upright microscope. Due to RBC’s membrane being poorly reflective for visible wavelengths, quantitative information in the signal is weak and therefore, the quality of experimental results is limited in comparison to results obtained in transmission mode by various holographic techniques reported elsewhere.

• 대한핵의학회지
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• 제34권1호
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• pp.1-9
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• 2000

The rapid progress of molecular genetic methods over the past two decades has necessitated the development of methods to detect and quantify genetic activity within living bodies. Reporter genes provide a rapid and convenient tool to monitor gene expression by yielding a readily measurable phenotype upon expression when introduced into a biological system. Conventional reporter systems, however, are limited in their usefulness for in vivo experiments or human gene therapy because of its invasive nature which requires cell damage before assays can be performed. This offers an unique opportunity for nuclear imaging techniques to develope a novel method for imaging both the location and amount of gene expression noninvasively. Current developments to achieve this goal rely on utilizing either reporter enzymes that accumulate radiolabeled substrates or reporter receptors that bind specific radioligands. This overview includes a brief introduction to the background for such research, a summary of published results, and an outlook for future directions.

• 비파괴검사학회지
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• 제29권4호
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• pp.283-292
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• 2009

Laser-based ultrasonic sensing requires the probe with fixed fecal length, but this requirement is not essential in laser-based ultrasonic generation. Based on this fact, we designed a pulsed laser-based ultrasonic wave propagation imaging (UWPI) system with a tilting mirror system for rapid scanning of target, and an in-line band-pass filtering capable of ultrasoaic mode selection. 1D-temporal averaging, 2D-spatial averaging, and 3D-data structure building algorithms were developed far clearer results allowing fur higher damage detectability. The imaging results on a flat stainless steel plate were presented in movie and snapshot formats which showed the propagation of ultrasound visible as a concentric wavefield emerging from the location of an ultrasonic sensor. A hole in the plate with a diameter of 1 mm was indicated by the scattering wavefields. The results showed that this robust UWPI system is independent of focal length and reference data requirements.

• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.39.1-39.20
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• 2018

Magnetic resonance imaging (MRI) is an advanced diagnostic tool used in both medicine and dentistry. Since it functions based on a strong uniform static magnetic field and radiofrequency pulses, it is advantageous over imaging techniques that rely on ionizing radiation. Unfortunately, the magnetic field and radiofrequency pulses generated within the magnetic resonance imager interact unfavorably with dental materials that have magnetic properties. This leads to unwanted effects such as artifact formation, heat generation, and mechanical displacement. These are a potential source of damage to the oral tissue surrounding the affected dental materials. This review aims to compile, based on the current available evidence, recommendations for dentists and radiologists regarding the safety and appropriate management of dental materials during MRI in patients with orthodontic appliances, maxillofacial prostheses, dental implants, direct and indirect restorative materials, and endodontic materials.

• Investigative Magnetic Resonance Imaging
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• 제20권1호
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• pp.71-74
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• 2016

Wernicke's encephalopathy (WE) is an acute neurological disorder resulting from thiamine deficiency. Early diagnosis and treatment of WE is important to avoid persistent brain damage. Although histopathologic examination usually demonstrates pin-point hemorrhages in affected brain parenchyma, secondary hemorrhage is a rare but serious complication of WE. We experienced a rare case of intracranial hemorrhage related to WE in a 56-year-old male patient with malnourishment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.85.2-85.2
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• 2016

With the advent of ultra-short high-intense XFEL (X-ray Free Electron Laser), time-resolved dynamics has become of great importance in exploring femtosecond real-world phenomena of nanoscience and biology. These include studying the response of materials to femtosecond laser excitation and investigating the interaction of XFEL itself with condensed matter. A variety of dynamic phenomena have been investigated such as radiation damage, ultrafast melting process, non-equilibrium phase transitions caused by orbital-lattice-spin couplings. As far as bulk materials are concerned, the sample size has no effect on the following dynamic process. As a result, imaging information is not required by and large. If the sample size is of tens of nanometers, however, sample starts to experience quantum confinement effect which, in turn, affects the following dynamic process. Therefore, to understand the fundamental dynamic phenomena in nano-science, time-resolved imaging information is essential. In this talk, we will briefly introduce scientific highlights achieved in XFEL-based dynamics. In case of bio-imaging, recent scientific topics will be mentioned as well. Finally, we will aim to present feasible topics in ultrafast time-resolved imaging and to discuss the future plan of CXI beamline at PAL-XFEL.