• Journal of information and communication convergence engineering
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• 제5권4호
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• pp.374-376
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• 2007

The output characteristics of HF and DF lasers were compared theoretically. The simulation code shows the good agreement with the experimental results well. As results, the effect of chain termination reaction in $F_2$ rich mixture is larger than that of $SF_6$ rich mixture in HF and DF lasers.

• Journal of Acupuncture Research
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• 제27권5호
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• pp.51-58
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• 2010

Objectives : The purpose of this study is to assess the effect of laser acupuncture at $HT_7$ for reducing mental stress using power spectrum analysis of the heart rate variability. Methods : 36 healthy volunteers(control group: 18, treatment group: 18) participated in this study. After instrumentation and 5-minute rest period, 5-minute metal stress by operation was provided. HRV was recorded before and after the mental stress(1st, 2nd HRV). After 2nd HRV recording, the control group rested for 15 minutes without any treatments. Participants in the treatment group received laser acupuncture to $HT_7$ unilaterally and rested for 15minutes. Points were irradiated for 60seconds, and the intensity was 1.8J(output 20%). And then 3rd HRV was recorded. Results : In simple rest group, LF norm showed a significant change after mental stress. In laser acupuncture group, LF norm, HF norm, LF, HF and LF/HF ratio showed a significant change after mental stress. But there were no significant difference between two groups(ANCOVA test, p>0.05). In laser acupuncture group, LF norm, HF norm, HF and LF/HF ratio showed a significant change after laser acupuncture treatment. And there were significant differences between two groups(p<0.05). Conclusions : This study suggests that laser acupuncture at $HT_7$ can regulate and prevent the alternation of autonomic nervous system due to mental stress.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.591-593
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• 2007

최근 에너지효율이 높은 고출력 HF 레이저에 대한 관심이 다시 높아지고 있다. 레이저점화방식의 최적설계와 출력특성의 향상을 위해 정확한 이론해석 모델이 필요하다. 따라서 본 연구에서는 최신의 반응정수를 적용한 HF 화학레이저 모델을 구축하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.304.2-304.2
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• 2016

Hafnium oxide-aluminum oxide (HfO2-Al2O3) dielectric films have been fabricated by Pulsed Laser Deposition (PLD), and their properties are studied in comparison with HfO2 films. As a gate dielectric of the TFT, in spite of its high dielectric constant, HfO2 has a small energy band gap and microcrystalline structure with rough surface characteristics. When fabricated by the device, it has the drawback of generating a high leakage current. In this study, the HfAlO films was obtained by Pulsed Laser Deposition with HfO2-Al2O3 target(chemical composition of (HfO2)86wt%(Al2O3)14wt%). The characteristics of the thin Film have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM) and spectroscopic ellipsometer (SE) analyses. The X-ray diffraction studies confirmed that the HfAlO has amorphous structure. The RMS value can be compared to the surface roughness via AFM analysis, it showed HfAlO thin Film has more lower properties than HfO2. The energy band gap (Eg) deduced by spectroscopic ellipsometer was increased. HfAlO films was expected to improved the interface quality between channel and gate insulator. Apply to an oxide thin Film Transistors, HfAlO may help improve the properties of device.

• 대한화학회지
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• 제33권2호
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• pp.168-176
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• 1989

화학 레이저 모델의 이론적 연구를 화학 반응속도론, gain 과정과 유도 방출과정을 고려하여 수행하였다. 우선 F+$H_2$비 연쇄반응 HF 화학 레이저를 진동준위가 v = 3 까지 pumping되는 것으로 생각하고 관련된 rate equation을 풀어서 출력을 산출하였다. 여기서 조화진동자를 가정한 계산과 비조화성 보정을 해준 계산결과의 비교로부터 그 차이가 거의 없음을 확인하였다. 또한 여러가지 온도와 초기농도를 택하여 산출되는 laser 축력의 변화를 검토하였다. 그리고 $H_2$+$F_2$ 연쇄반응 HF 화학 레이저에 관한 비교적 단순한 model simulation을 수행하였다. 이 계산 결과는 이미 보고된 상당히 복잡한 계산결과와 비교하여 만족할 정도이었다.

• 한국광학회지
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• 제12권3호
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• pp.153-157
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• 2001

들뜬 상태 HF* 분자으 형광세기를 측정하여 불소-수소 연소 유도에 의한 HF 레이저발진을 위한 조업조언을 논하였다. 불소원자 생산을 위한 적정 불소 주입 조건은 수소연료 주입 몰(mole)수의 두 배이었다. 들뜬 상태 HF*분자 생산을 위하여 슬릿형태의 이차원적 구조를 가지는 연소노즐을 이용하였으며, 이차 수소연료의 주입 몰수가 불소기체 주입 몰수의 1.3배 일 경우 들뜬 상태 HF* 분자의 형광세기는 최대를 나타내었다.

• Bulletin of the Korean Chemical Society
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• 제15권9호
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• pp.724-729
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• 1994

The effect of oxygen for the HF chemical laser performance has been theoretically investigated. Due to the inhibition mechanism of $O_2$ in $H_2$/$F_2$ chain reaction, the rate for the formation of HF is reduced by the addition of $O_2$. As the concentration of $O_2$ in the reaction mixture increases, the pulse power and temperature of the system becomes lower, while total output energy does not change significantly. But addition of $O_2$ makes the system easy to be controlled and the composition of $H_2$+$F_2$ can be high at constant total pressure. With this system, it is possible to obtain higher output energy than oxygen free environment.

• 대한중풍순환신경학회지
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• 제6권1호
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• pp.9-16
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• 2005

Objective : The heart rate variability is very useful indicator to study the function of the autonomic nervous system(ANS), and the physiologic signals can be observed based on the changes of the ANS of the heart. In order to assay the effects of the laser exposing to healthy subjects, the double blind test has been performed. Methods : This study included 62 healthy adults who have not any ANS disease and had normal sinus rhythm in electrocardiogram. The control group consisted of 31 subjects, laser group consisted of 31 subject. HRV was measured for 5 minutes before laser irradiation, sham and real laser irradiated for 30 minutes and than HRV remeasured for 5 minutes. Statistical significance was evaluated by independent T-test. Results : Mean HRV, Ln(VLF), Ln(HF), Ln(TP) of both groups at post-laser period decreased compared with that of the pre-laser period. Ln(LF) of both groups at post-laser period increased compared with that of the pre-laser period. LF/HF, SDNN of real laser group decreased and sham group decreased. Conclusions : There is no difference between two groups. The reason is presumed that all the studied subjects are healthy adults, and also the short and single transcutaneous laser irradiation would not influence upon changes of the ANS. The further study must be followed.

• E2M - 전기 전자와 첨단 소재
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• 제16권9호
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• pp.63.2-64
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• 2003

Epitaxial yttrium-stabilized HfO$_2$ thin films were deposited on p-type (100) Si substrates by pulsed laser deposition at a relatively lower substrate temperature of 550. Transmission electron microscopy observation revealed a fixed orientation relationship between the epitaxial film and Si; that is, (100)Si.(100)HfO$_2$ and [001]Si/[001]HfO$_2$. The film/Si interface is not atomically flat, suggesting possible interfacial reaction and diffusion, X-ray photoelectron spectrum analysis also revealed the interfacial reaction and diffusion evidenced by Hf silicate and Hf-Si bond formation at the interface. The epitaxial growth of the yttrium stabilized HfO$_2$ thin film on bare Si is via a direct growth mechanism without involoving the reaction between Hf atoms and SiO$_2$ layer. High-frequency capacitance-voltage measurement on an as-grown 40-A yttrium-stabilized HfO$_2$ epitaxial film yielded an dielectric constant of about 14 and equivalent oxide thickness to SiO$_2$ of 12 A. The leakage current density is 7.0${\times}$ 10e-2 A/$\textrm{cm}^2$ at 1V gate bias voltage.

• 한국전기전자재료학회논문지
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• 제21권1호
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• pp.1-4
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• 2008

The electrical characteristics of polycrystalline silicon (poly-Si) thin film transistor (TFT) crystallized by excimer laser annealing (ELA) method were evaluated, The polycrystalline silicon thin-film transistor (poly-Si TFT) has higher electric field-effect-mobility and larger drivability than the amorphous silicon TFT. However, to poly-Si TFT's using conventional processes, the temperature must be very high. For this reason, an amorphous silicon film on a buried oxide was crystallized by annealing with a KrF excimer laser (248 nm)to fabricate a poly-Si film at low temperature. Then, High permittivity $HfO_2$ of 20 nm as the gate-insulator was deposited by atomic layer deposition (ALD) to low temperature process. In addition, the solid phase crystallization (SPC) was compared to the ELA method as a crystallization technique of amorphous-silicon film. As a result, the crystallinity and surface roughness of poly-Si crystallized by ELA method was superior to the SPC method. Also, we obtained excellent device characteristics from the Poly-Si TFT fabricated by the ELA crystallization method.