• 한국지구과학회지
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• 제40권4호
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• pp.428-435
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• 2019

In the shallow coastal area, located off the northwestern Taean Peninsula of the eastern Yellow Sea, geoacoustic models with two layers were reconstructed for underwater acoustic experimentation and modeling. The Yellow Sea experienced glacio-eustasy sea-level fluctuations during Quaternary period. Coastal sedimentation in the Yellow Sea was characterized by alternating terrestrial and shallow marine deposits that reflected the fluctuating sea levels. The coastal geoacoustic models were based on data from piston, grab cores and the high-resolution 3.5 kHz, chirp seismic profiles (about 70 line-kilometers, respectively). Geoacoustic data of the cores were extrapolated down to 3 m in depth for geoacoustic models. The geoacoustic property of seafloor sediments is considered a key parameter for modeling underwater acoustic environments. For simulating actual underwater environments, the P-wave speed of the models was adjusted to in-situ depth below the sea floor using the Hamilton method. The proposed geoacoustic models could be used for submarine acoustic inversion and modeling in shallow-water environments of the study area.

• 대한수의학회지
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• 제50권2호
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• pp.155-160
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• 2010

The objective of this study was to compare wound healing in stomach with $CO_{2}$ laser and scalpel incision by measuring the extent of bleeding, the ease of gastric incision, incision time, degree of adhesion and wound healing degree in dogs. Sixteen healthy dogs were used. Two symmetrical incisions were made in ventral aspect of the stomach between the greater and lesser curvatures were made with scalpel and 0.2 mm spot diameter $CO_{2}$ laser (8W, continuous wave) in sixteen dogs. And then each wound was closed with absorbable suture in a two-layer inverting seromuscular pattern. At 3, 7, 14 and 21 days after initial wounding, each wound was taken for histological observation. On surgery, the extent of bleeding, the ease of incision and incision time showed significant differences between the groups. The $CO_{2}$ laser provided better hemostasis (p < 0.05) and smaller postoperative adhesion compared with the scalpel. However, the scalpel produced faster speed of incision and was easier to handle than the $CO_{2}$ laser (p < 0.05). Although there was no considerable difference between the two groups in histological observation, necrosis and calcium deposit tended to be larger in the $CO_{2}$ laser than in the scalpel.

• 말소리와 음성과학
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• 제1권3호
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• pp.151-154
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• 2009

The external ear generates resonance gain because of anatomical characteristics. The ear canal resonance is influenced by the length and volume of the ear canal, the pinna, the concha cavity, the body trunk, and the speed of sound wave. This study is focus on the influence of the volume of ear canal. 17-healthy-adult (32 ears) were participated. They did not have any medical and ear disease history. The maximum resonance frequency of the ear canal was 2675 (${\pm}265$) Hz at azimuth $0^{\circ}$ and 2784 (${\pm}268$) Hz at azimuth $45^{\circ}$. The resonance gain was 18.1 (${\pm}3.9$) dB at azimuth $0^{\circ}$ and 17.9 (${\pm}3.8$) dB at azimuth $45^{\circ}$, respectively. The ear canal volume was 0.78 (${\pm}0.2$) cc and 1.32 (${\pm}0.8$) cc including static compliance. The ear canal resonance was changed depending on the ear canal volume. It was also statistically correlated at azimuth $0^{\circ}$ (p=0.038) and $45^{\circ}$ (p=0.013), respectively. The resonance gain was not correlated with the ear canal volume. The change of resonance frequency according to the ear canal volume will be useful information in the field of audiological rehabilitation especially for hearing aids fitting. In addition, we expected this study can provide the basic information for the study of the external ear resonance characteristics.

• 전력전자학회논문지
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• 제12권3호
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• pp.267-275
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• 2007

본 논문은 현재 청정에너지의 개념으로 대두되고 있는 에너지원 가운데 기계적인 에너지로 저장하여 필요 시 꺼내어 사용할 수 있는 플라이휠 에너지 저장장치에 대한 에너지 입, 출력 모델링 및 PWM 인버터 시스템의 해석 및 제어에 관한 논문으로서, 플라이휠 저장장치 특성 및 시스템 모델링에 관해 논의한다. 재질에 따른 플라이휠의 특성과 플라이휠 에너지 저장장치의 속도 특성에 따른 전압과 전류의 변화량을 수식으로 간략화 하여 분석하고, 시뮬레이션을 통하여 플라이휠의 에너지 저장상태를 분석하였다. 또한, 부하측 전원의 이상유무에 관계없이 에너지를 공급할 수 있는 Online UPS로 사용하기 위해 PDFF 제어기법을 이용하여 전압제어 및 전류제어의 이중루프 제어로 구성된 단상 PW방식의 인버터 시스템 제작하였으며, 실험을 통하여 실제로 0.1[p.u], 1[p.u]에서의 제어되는 전압, 전류제어파형 및 THD 특성에 관하여 평가한다.

• Restorative Dentistry and Endodontics
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• 제30권1호
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• pp.16-21
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• 2005

본 실험에서는 근관 충전 후 Streptococcus mutans를 이용하여 포스트 와동 형성 전후의 근관부미세 누출을 비교하였다. 40개의 발치된 치아를 치근단의 길이가 14 mm가 되도록 치관부를 제거한 뒤, 06 taper $Profile^{(R)}$로 MAF 크기가 $\#40$이 되게 근관 확대를 시행하였다. 근관 확대 후 continuous wave technique으로 근관 충전을 시행하였다. 실험군은 다음과 같다. 1군은 양성 대조군으로 sealer 없이 근관 충전 하였다. 2군은 음성 대조군으로 sticky wax로 치근면을 완전히 막았다. 3군은 근관 충전 후 전체 길이를 14 mm로 유지하였다. 4군은 근관 충전 후 거타퍼치를 5 mm 길이로 남겨두고 포스트 와동을 형성하였다. 치근을 플라스틱 튜브 안에 위치시켜 치근첨은 Andrade's indicator가 첨가되어 있는 BHI 배지에 접촉되도록 하고 상부에서는 bacteria가 유입되도록 하였다. 실험군 3에서의 색변화는 평균 27.2일 만에 일어났으며 포스트 와동 형성한 4군은 평균 15.7일만에 색변화가 일어났으며 3군과 4군 사이에 통계학적으로 유의차를 나타내었다(P = 0.0007).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.430-430
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• 2008

Using multi plasma enhanced chemical vapor deposition system (Multi-PECVD), p-a-Si:H deposition layer as a $p^+$ region which was annealed by laser (Q-switched fiber laser, $\lambda$ = 1064 nm) on an n-type single crystalline Si (100) plane circle wafer was prepared as new doping method for single crystalline interdigitated back contact (IBC) solar cells. As lots of earlier studies implemented, most cases dealt with the excimer (excited dimer) laserannealing or crystallization of boron with the ultraviolet wavelength range and $10^{-9}$ sec pulse duration. In this study, the Q-switched fiber laser which has higher power, longer wavelength of infrared range ($\lambda$ = 1064 nm) and longer pulse duration of $10^{-8}$ sec than excimer laser was introduced for uniformly deposited p-a-Si:H layer to be annealed and to make sheet resistance expectable as an important process for IBC solar cell $p^+$ layer on a polished n-type Si circle wafer. A $525{\mu}m$ thick n-type Si semiconductor circle wafer of (100) plane which was dipped in a buffered hydrofluoric acid solution for 30 seconds was mounted on the Multi-PECVD system for p-a-Si:H deposition layer with the ratio of $SiH_4:H_2:B_2H_6$ = 30:120:30, at $200^{\circ}C$, 50 W power, 0.2 Torr pressure for 20 minutes. 15 mm $\times$ 15 mm size laser cut samples were annealed by fiber laser with different sets of power levels and frequencies. By comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 50 mm/s of mark speed, 160 kHz of period, 21 % of power level with continuous wave mode of scanner lens showed the features of small difference of lifetime and lowering sheet resistance than before the fiber laser treatment with not much surface damages. Diode level device was made to confirm these experimental results by measuring C-V, I-V characteristics. Uniform and expectable boron doped layer can play an important role to predict the efficiency during the fabricating process of IBC solar cells.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.456-456
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• 2009

Boron doping on an n-type Si wafer is requisite process for IBC (Interdigitated Back Contact) solar cells. Fiber laser annealing is one of boron doping methods. For the boron doping, uniformly coated or deposited film is highly required. Plasma enhanced chemical vapor deposition (PECVD) method provides a uniform dopant film or layer which can facilitate doping. Because amorphous silicon layer absorption range for the wavelength of fiber laser does not match well for the direct annealing. In this study, to enhance thermal affection on the existing p-a-Si:H layer, a ${\mu}c$-Si:H intrinsic layer was deposited on the p-a-Si:H layer additionally by PECVD. To improve heat transfer rate to the amorphous silicon layer, and as heating both sides and protecting boron eliminating from the amorphous silicon layer. For p-a-Si:H layer with the ratio of $SiH_4$ : $B_2H_6$ : $H_2$ = 30 : 30 : 120, at $200^{\circ}C$, 50 W, 0.2 Torr for 30 minutes, and for ${\mu}c$-Si:H intrinsic layer, $SiH_4$ : $H_2$ = 10 : 300, at $200^{\circ}C$, 30 W, 0.5 Torr for 60 minutes, 2 cm $\times$ 2 cm size wafers were used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 20 ~ 27 % of power, 150 ~ 160 kHz, 20 ~ 50 mm/s of marking speed, and $10\;{\sim}\;50 {\mu}m$ spacing with continuous wave mode of scanner lens showed the correlation between lifetime and sheet resistance as $100\;{\Omega}/sq$ and $11.8\;{\mu}s$ vs. $17\;{\Omega}/sq$ and $8.2\;{\mu}s$. Comparing to the singly deposited p-a-Si:H layer case, the additional ${\mu}c$-Si:H layer for doping resulted in no trade-offs, but showed slight improvement of both lifetime and sheet resistance, however sheet resistance might be confined by the additional intrinsic layer. This might come from the ineffective crystallization of amorphous silicon layer. For the additional layer case, lifetime and sheet resistance were measured as $84.8\;{\Omega}/sq$ and $11.09\;{\mu}s$ vs. $79.8\;{\Omega}/sq$ and $11.93\;{\mu}s$. The co-existence of $n^+$layeronthesamesurfaceandeliminating the laser damage should be taken into account for an IBC solar cell structure. Heavily doped uniform boron layer by fiber laser brings not only basic and essential conditions for the beginning step of IBC solar cell fabrication processes, but also the controllable doping concentration and depth that can be established according to the deposition conditions of layers.

• 대한물리치료과학회지
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• 제14권1_4호
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• pp.11-23
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• 2007

This study was performed to evaluate the effects of low-intensity ultrasound application to the peripheral nerve injury animal model on enhancement of nerve regeneration and functional recovery. Using aseptic microsurgical techniques, the sciatic nerve of adult male Sprague-Dawley rats was crushed at the outside of right mid-thigh for 30 seconds with fine forceps. Beginning just after surgery, various continuous-wave ultrasound treatments with intensities of 0.2 W/$cm^2$, 0.5 W /$cm^2$ and 1.0 W /$cm^2$ operated at 1 MHz or sham treatment were applied to the opposite inside of the crush site for 1 minute every other day with a transducer moving speed of 2cm/sec. For evaluation of the progress of sciatic nerve regeneration, c-Fos expression in the lumbar spinal cord (L4-5) dorsal horn was investigated. c-fos expression was markedly increased at 1hour after sciatic nerve crush injury, then gradually decreased thereafter. The c-fos expressions were significantly decreased (p<0.05) in all the experimental groups in comparison with the control group until 3days post-crush, and the degrees of decrease were higher in 0.5 W/$cm^2$ and 1 W/$cm^2$ intensity ultrasound application groups. It is suggested that low-intensity ultrasound application to an animal model of sciatic crush injury may suppress pain transmission and promote nerve regeneration, and which may result in delayed progress of muscle atrophy and accelerated progress of muscle recovery and eventually may result in accelerated and improved foot function recovery.

• 지구물리와물리탐사
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• 제18권2호
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• pp.74-84
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• 2015

탄성 거꿀 참반사 보정(elastic reverse-time migration)을 통해 물리적으로 의미가 있는 영상을 얻기 위해서는 탄성 파동방정식(elastic wave equation)을 통해 재구성된 벡터 파동장(reconstructed vector wavefield)으로부터 P파와 S파를 분리하는 파분리 알고리듬이 필요하다. 그리고 이방성을 고려한 탄성 거꿀 참반사 보정으로의 확장을 위해서는 이방성을 고려한 탄성 모델링 알고리듬 뿐만 아니라 이방성을 고려한 파분리가 필요하다. 이방성 탄성매질에서의 파분리는 등방성 탄성매질에서 주로 이용하는 Helmholtz decomposition과는 달리 탄성매질의 수직 속도 및 이방성 계수에 따라 계산된 유사미분필터(pseudo-derivative filter)를 이용한다. 이 필터는 적용에 많은 계산이 필요하기 때문에 이 연구를 통해 많은 양의 병렬계산을 효율적으로 수행할 수 있는 GPU (Graphic Processing Unit)를 이용하여 이방성 파분리를 수행하는 알고리듬을 개발하였다. 또한 GPU를 이용해 파분리를 수행하는 알고리듬을 포함하고 MPI (Message-Passing Interface)를 이용하는 효율성 높은 이방성 탄성 거꿀 참반사 보정 알고리듬을 개발하였다. 개발된 알고리듬의 검증을 위해 Marmousi-II 탄성모델을 기초로 수직 횡등방성(vertically transversely isotropy; VTI) 탄성모델을 구축하여 수치모형 실험을 수행해 다성분 합성탄성파탐사자료를 생성하였다. 이 합성탄성파 자료에 개발된 이방성 탄성 거꿀 참반사 보정 알고리듬을 적용하여 GPU와 MPI를 효과적으로 이용한 계산속도 향상과 이방성 파분리에 의한 영상결과의 정확도 향상을 보여주었다.

• 콘크리트학회논문집
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• 제16권5호
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• pp.581-589
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• 2004

본 논문에서는 일정진폭 휨인장 및 쪼갬인장 반복하중을 받는 콘크리트의 피로신뢰성과 모델제안을 위하여 도로포장에 사용되는 콘크리트를 대상으로 연구하였다. 실험데이터는 2-모수 Weibull 확률분포함수를 사용하여 신뢰성 해석을 수행하였고, 적합도 검정을 통하여 이를 기반으로 한 모델을 제시하였다. 피로실험은 $150 mm{\times}75 mm$ 시험체의 쪼갬인장피로 실험방법과 $150 mm{\times}150 mm{\times}550 mm$ 시험체의 휨인장피로 실험방법을 적용였으며 일정 진폭 피로하중에 대하여 수행하였다. 두 가지의 실험방법에 대하여 응력 수준 90, 80, $70\%$로 변화하여 실험하고 이때 적용한 응력비는 0.1, 하중재하속도 20Hz, 정현파(sine)를 적용하였다. 연구결과 콘크리트 피로데이터의 분산성으로 인하여 보다 정확한 해석을 위해 두 가지의 해석 기준을 설정하여 제시하였으며, 그래픽방법, 모멘트방법 및 최우도법에 의해 2-모수 Weibull의 매개변수 $\alpha$와 u를 계산하고 이를 이용하여 확률밀도함수(P.D.F)와 누적분포함수(C.D.F)를 도시하였다. 또한, Weibull의 확률분포함수를 이용한 신뢰성 해석은 Kolmogorov-Smirnov의 방법을 사용하여 $5\%$의 유의수준에서 적합도 검정을 수행한 결과 채택되는 것으로 나타났다. 이러한 해석에 기초하여 쪼갬인장피로실험과 휨인장피로 실험에 대한 피로모델을 제시하고 응력수준에 따른 피로수명과 200만회 및 1,000만회에서의 피로강도를 산정하여 제시하였으며 국외의 주요 피로모델과 비교하였다.