• Nuclear Engineering and Technology
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• 제54권2호
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• pp.661-665
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• 2022

The 3 MeV proton irradiation effects on SiGe low noise amplifier (LNA) (NXP BGU7005) performance under different voltage supply VCC (0 V, 2.5 V) conditions were firstly experimental studied in this present work. The S parameters including S₁₁, S₂₂, S₂₁, 1 dB compression point and noise figure (NF) of the test samples under different bias voltage supply were measured and compared before and after 3 MeV proton irradiation. The total proton irradiation fluence was 1 × 10¹⁵ protons/cm². The maximum degradation quantities of the gain S₂₁ and NF of the test samples under zero bias are measured respectively 1.6 dB and 1.2 dB. Compared with the samples under 2.5 V bias supply, the maximum degradation of S₂₁ and NF are respectively 1.1 dB and 0.8 dB in the whole frequency band. It is noteworthy that the gain and NF of SiGe LNAs under zero-bias mode suffer enhanced degradation compared with those under normal bias supply. The key influence factors are discussed based on the correlation of the SiGe device and the LNA circuit. Different process of the ionization damage and displacement damage under zero-bias and 2.5 V bias voltage supply contributed to the degradation difference. The underlying physical mechanisms are analyzed and investigated.

• Journal of Periodontal and Implant Science
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• 제44권5호
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• pp.227-234
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• 2014

Purpose: Dentin hypersensitivity is a potential threat to oral health. Laser irradiation may provide reliable and reproducible treatment but remains controversial. The present study aimed to evaluate the effects of $CO_2$ or erbium-doped yttrium aluminium garnet (Er:YAG) laser therapy, and to assess mineral content. Methods: Eighteen human single-rooted teeth affected with advanced periodontitis were obtained. Buccal and lingual surfaces were planed to form 36 specimens. Ethylenediaminetetraacetic acid gel (24%) was applied to remove the smear layer and simulate hypersensitive teeth. The experimental groups were: group 1, control (no irradiation); group 2, $CO_2$ laser (repetitive pulsed mode, 2 W, $2.7J/cm^2$); and group 3, Er:YAG laser (slight contact mode, 40 mJ/pulse and 10 Hz). To evaluate dentinal tubule occlusion, six specimens per group (2-mm thickness) were prepared and observed using scanning electron microscopy (SEM) for calculation of the occlusion percentage. To evaluate the mineral content, six specimens per group (0.6-mm thickness) were used, and then the levels of Ca, K, Mg, Na, and P were measured by inductively coupled plasma-atomic emission spectrometry. In addition, the surface temperature of the specimens during laser irradiation was analyzed by a thermograph. Results: The SEM photomicrographs indicated melted areas around exposed dentinal tubules and a significantly greater percentage of tubular occlusion in the $CO_2$ and Er:YAG laser groups than the control, and in the Er:YAG group than the $CO_2$ laser group. In addition, no significant differences were noted among the experimental groups for the mineral elements analyzed. The $CO_2$ laser group showed an evident thermal effect compared to the Er:YAG group. Conclusions: $CO_2$ and Er:YAG laser are effective in treating dentin hypersensitivity and reducing its symptoms. However, the Er:YAG laser has a more significant effect; thus, it may constitute a useful conditioning item. Furthermore, neither $CO_2$ nor Er:YAG lasers affected the compositional structure of the mineral content.

• Medical Lasers
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• 제7권1호
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• pp.6-12
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• 2018

Introduction Energy-based devices allow for a more rapid and efficient ligation of blood vessels during operations. In the present study, we evaluated the feasibility of a laser as an alternative energy source for the vessel sealing system and determined the optimal condition of laser for an effective vessel sealing through histologic examination. Materials and Methods The arteries (5 mm diameter) harvested from porcine legs were compressed between two glass-slides to eliminate its luminal space and were irradiated with 1,470-nm diode laser under various sealing conditions, including laser power (5-30 W), irradiation time (5 or 10 seconds), and focus mode (focus or defocus). Subsequently, the irradiated vessels were fixed in 4% formaldehyde and then processed to paraffin block. The paraffinized sample was sectioned and stained with hematoxylin and eosin for histological evaluation. Results The extent of tissue change was positively correlated with duration and power of laser. In defocus mode, the irradiated vessels showed sufficient tissue denaturation for sealing effect without severe tissue destruction. Moreover, among the various conditions of irradiation, laser power between 15 and 20 W, as well as exposure time of 5 seconds were appropriate for sealing the blood vessels. Conclusion Adequate power and irradiation duration of laser can render blood vessels to be sealed effectively, although the higher power of laser may be required to cut the vessels.

• 대한의용생체공학회:의공학회지
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• 제37권4호
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• pp.134-139
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• 2016

US Food and Drug Administration (FDA) approved as a innovative cure for cancer, 1996. The effect is death of cancer cells through necrosis, apoptosis. Mainly the Continuous Wave mode (CW) use for PDT Laser. It sting, the question including itch, and etc. Reportedly, the increase of temperature with the perforated edema, ulcer, necrosis. The Thermal relaxation time and Oxygen recovery time is necessary. To give a normal oxygen recovery time of the cell, used Pulse mode. Progress, it was Burst Pulse mode when easing the thermal wake, the simplicity was secured, the PDT effect is good. Excepted in control group CW, Pulse, Burst pulse mode were incubated with various concentrations of 5-aminolevulinic acid hydrochloride (ALA-5). The tumor size reduction CW mode (44%), Pulse mode (48%), Burst pulse mode (53%) at 4 week after PDT with 0.3, 0.3, 0.3 mg/ml of ALA-5. After 4 hours, investigation of 100, 100, $100J/cm^2$ laser irradiation. The pulse mode was superior in expirimental data analysis. And it was the Burst pulse mode edge head of a family effect.

• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.1028-1032
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• 2005

Liquid crystal (LC) alignment using a photoalignment method by irradiation of polarized ultraviolet (UV) on an alignment layer has been investigated. Photoalignment method exhibits weaker anchoring energy than rubbing method so that we have studied electro-optic characteristics of fringe-field switching (FFS) mode with alignment layers using the photo and rubbing alignment methods. The cell using photo alignment layer shows lower threshold and operation voltage than those using rubbed alignment layer. Also, the former method shows higher transmittance than that of the latter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.118-122
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• 2005

Liquid crystal (LC) alignment using a photoalignment method by irradiation of polarized ultraviolet (UV) on an alignment layer has been investigated. Photoalignment method exhibits weaker anchoring energy than rubbing method so that we have studied electro-optic characteristics of fringe-field switching (FFS) mode with alignment layers using the photo and rubbing alignment methods. The cell using photo alignment layer shows lower threshold and operation voltage than those using rubbed alignment layer. Also. the former method shows higher transmittance than that of the latter.

• 한국정보통신학회논문지
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• 제16권10호
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• pp.2287-2292
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• 2012

본 논문에서는 Ge가 함유된 일반 단일모드 광섬유의 감마선 유입손실을 측정하였다. 방사선 선원은 $Co^{60}$ 감마선 선원을 이용하였으며, 총 4시간동안 0.5 kGy/hr, 2 kGy/hr, 8 kGy/hr의 선량률로 조사하였다. 그 결과 감마선 조사에 의한 단일모드 광섬유의 전송손실이 뚜렷하게 나타났으며, 동일 누적선량에서 선량률이 클수록 전송손실이 증가하는 선량률 효과가 나타났다. 또한 감마선 조사 종료 후 광섬유의 전송손실이 클수록 유입손실의 회복률이 증가하는 어닐링 특성을 보였다. 본 실험결과는 향후 광섬유의 내방사화 연구의 기초자료로 활용할 것이다.

• Journal of Oral Medicine and Pain
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• 제18권2호
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• pp.97-106
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• 1993

This study was performed to investigate the effects of infrared and visible light laser irradiation on cell viability of human gingival fibroblast. For the present study, the author used cultured fibroblast originated from sound gingiva which were fifth of sixth passage. Laser machine utilized here were stomalaser which irradiate infrared (GaAs diode) and red (HeNe) laser in turn with pulse wave pattern or continuous wave pattern, and the machine had several frequency mode presented by regeneration, relaxation and analgesic modalities. Cultured fibroblast samples were divided by this modalities of cell counts and laser exposure time which were 7-seconds of 150 seconds, respectively. 1 day after laser irradiation, each cell-well was treated with MTT and measured optical density with ELISA. The obtained results were as follows : 1. There was a tendency of increasing optical density in proportion to irradiation time in groups of $1\times10^4$ cell per well but in groups of $5\times10^3$ cell per well, reverse phenomena were observed. 2. The difference of optical density according to frequency modalities were not showed significantly except several cases in groups of $5\times10^3$ cell per well. 3. In general, cell viability of cultured human gingival fibroblast wer not showed consistent feature by low level laser irradiation.

• Nuclear Engineering and Technology
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• 제51권8호
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• pp.1983-1990
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• 2019

Spray deposited Molybdenum trioxide (MoO₃) thin film of thickness nearly 379 nm were irradiated with 200 MeV Ag¹⁵⁺ ion beam at different fluences (Ø) of 5 ×10¹¹, 1 × 10¹², 5 × 10¹² and 1 × 10¹³ ions/㎠. The X-ray diffraction (XRD) pattern of the pristine film confirms orthorhombic structure and the crystallinity decreased after irradiation with the fluence of 5 × 10¹¹ ions/㎠ due to irradiation induced defects and became amorphous at higher fluence. In pristine film, Raman modes at 665, 820, 996 cm^-1 belong to Mo-O stretching, 286 cm^-1 belong to Mo-O bending mode and those below 200 cm^-1 are associated with lattice modes. Raman peak intensities decreased upon irradiation and vanished completely for the ion fluence of 5 ×10¹² ions/㎠. The percentage of optical transmittance of pristine film was nearly 40%, while for irradiated films it decreased significantly. Red shift was observed for both the direct and indirect band gaps. The pristine film surface had densely packed rod like structures with relatively less porosity. Surface roughness decreased significantly after irradiation. The electrical transport properties were also studied for both the pristine and irradiated films by Hall effect. The results are discussed.

• 대한소아치과학회지
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• 제30권4호
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• pp.660-666
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• 2003

치아우식증은 산에 의해 법랑질이 탈회되는 현상으로 소아 및 청소년기에 가장 흔히 발생하는 구강질환 중의 하나로서, 치아우식증의 원인요소 중 다른 인자들보다 객관적으로 조사할 수 있는 구강내 세균에 대한 연구가 활발히 이루어져 왔다. 이 연구는 구강내의 치태라는 고체상태의 조건과 유사한 상태로 Er:YAG 레이저가 구강내 산 생성세균인 S. mutans의 증식에 미치는 영향 및 레이저의 조사시간에 따른 차이를 평가하고자 하였다. Er:YAG 레이저의 구강내 산 생성 세균인 S. mutans에 대한 증식억제효과를 평가하기 위하여 S. mutans pellet에 Er:YAG 레이저를 비접촉식 방법으로, 50mJ, 10Hz, 그리고 조사시간을 1초, 3초, 5초, 7초, 9초로 달리하여 조사하고 이때의 세균의 성장률과 산 생성능을 0, 2, 4, 8, 12, 24, 36, 48시간 동안 측정한 결과 다음과 같은 결과를 얻었다. 1. 레이저를 조사한 군이 레이저를 조사하지 않은 대조군에 비해 세균의 성장률이 감소되었다(P<0.01). 2. 레이저를 조사한 후 12시간까지 1, 3, 5초 조사군에 비해 7, 9초 조사군에서 세균의 성장율이 유의하게 감소되었으나(P<0.05), 24시간 후부터는 서로 유의할만한 차이를 보이지 않았다. 3. 레이저를 조사한 시간이 증가함에 따라 세균의 산 생성능력이 회복되는 시간이 길어짐이 관찰되었고 24시간 후에는 대조군과 차이를 보이지 않음으로써 일정 시간 이후에는 점차적으로 산 생성능력이 회복됨을 알 수 있었다.