• 대한소아치과학회지
• /
• 제24권1호
• /
• pp.301-312
• /
• 1997

The purpose of this study was to evaluate the analgesic effect on pulp induced by pulsed Nd : YAG laser according to the power density, irradiated time and the method of application (Non-contact vs contact) in vivo. Experiments were carried out on 90 volunteers who have sound 4 canines. Each canine was grouped by the intensity and the time of irradiation of pulsed Nd : YAG laser was measured. Mean EPT response(units) was measured at 5 min, 30 min, and 60 min after irradiation with various intensity(1.5-3W, 15-30Hz), irradiated time (1.5min, 3min), and application method (Non-contact and contact). The results were as follows: 1. 5 minutes after irradiation, the mean EPT response(units) was increased by 32 % in the non-contact method and by 35% in the contact method of application. Which showed significant difference in mean EPT response(units) compared to not-lased canine in each groups(P<0.05). 2. The mean EPT response(units) with irradiating condition according to the various laser intensity, and the irradiation time stastically did not show significant difference in each groups as time elapsed. 3. There was no significant difference between the non-contact and contact method in the mean EPT response(units). 4. The mean EPT response(units) returned to the baseline value within 30 miuntes. In regard to the above results, the analgesic effect on pulp induced by pulsed Nd : YAG laser resulted a slight increase of pulpal pain threshold, but it was not as high as to replace the role of drug analgesia as whole. This technique can be used for inducing pulpal analgesia as adjunct to other pain control methods and is needed to develop better analgesic effects.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2007년도 추계학술대회 및 제23회 정기총회
• /
• pp.198-199
• /
• 2007

이 연구에서는 36년간(1970-2005년)의 장기 데이터를 이용하여 우리나라에 영향을 미치는 태풍의 대부분이 통과하는 남해의 해수면온도 변화와 태풍의 세기 변화와의 관계가 분석 연구되었다. 우리나라 남해의 해수면온도는 연구 기간 동안 지속적으로 상승하는 추세를 보인다. 2000년 이래 6년간(2000-2005년)의 평균 해수면온도는 16.95$^{\circ}C$로 1970년대 10년간(1970-1979년)의 평균 해수면온도 15.74$^{\circ}C$보다 1.21$^{\circ}C$나 높다. 특히, 1994년 이후 그 상승폭은 크다. 태풍의 세기는 중심기압에 의하여 나타낼 수 있다. 남해를 통과하면서 우리 나라에 영향을 미친 태풍의 최저중심기압의 변화를 살펴보면 1970년 이후 지속적으로 하강하고 있음을 알 수 있다. 2000년 이래 6년간 (2000-2005년)의 평균 최저중심기압은 983hPa로, 1970년대 10년간(1970-1979년)의 평균 최저중심기압 992hPa보다 9hPa 이나 낮다. 상관 분석에 의하여, 1970년 이후의 태풍 세기 강화는 남해 해수면온도의 상승과 관련이 있다는 사실을 알 수 있었다.

• 한국항해항만학회지
• /
• 제32권5호
• /
• pp.403-407
• /
• 2008

이 연구에서는 36년간(1970-2005년)의 장기 데이터를 이용하여 우리나라에 영향을 미치는 태풍의 대부분이 통과하는 남해의 해수면 온도와 태풍의 세기 변화와의 관계를 분석, 연구하였다. 우리나라 남해의 해수면온도는 연구 기간 동안 지속적으로 상승하는 추세를 보인다. 1996년 이래 10년간(1996-2005년)의 평균 해수면온도는 $16.77^{\circ}C$로 1970년대 10년간(1970-1979년)의 평균 해수면온도 $15.74^{\circ}C$보다 $1.03^{\circ}C$나 높다. 특히, 1994년 이후 그 상승폭은 크다. 태풍의 세기는 최저해면기압에 의하여 나타낼 수 있다. 남해를 통과하면서 우리나라에 영향을 미친 태풍의 최저해면기압의 변화를 살펴보면, 1970년 이후 지속적으로 하강하고 있음을 알 수 있다. 1996년 이래 10년간(1996-2005년)의 평균 최저 해면기압은 979.2hPa로, 1970년대 10년간(1970-1979년)의 평균 최저해면기압 989.3hPa보다 10.1Pa이나 낮다. 상관분석에 의하여, 1970년 이후의 태풍 세기 강화는 남해 해수면온도의 상승과 상관이 있다는 사실을 확인하였다.

• 음성과학
• /
• 제10권2호
• /
• pp.111-128
• /
• 2003

Aerodynamic study is valuable information about the vocal efficiency in translating airflow to acoustic signal. The purpose of this study was to investigate the differences between trained singers and untrained controls under different two pitch by simultaneous using the airway interruption method and electroglottography (EGG). Under singing a Korean lied 'Gene', 20 (Male 10, Female 10) trained singers were studied on two one-octave different tone. Mean flow rate (MFR) , subglottic pressure (Psub) and intensity were measured with aerodynamic test using the Phonatory function analyzer (Nagashima Ltd. Model PS 77H, Tokyo, Japan). Closed quotients (Qx), jitter and shimmer were also investigated by electroglottography using Lx speech studio (Laryngograph Ltd, London, UK). These data were compared with those of normal controls. MFR and Psub were increased on high pitch tone in all subject groups. Statistically significant increasing of Qx and intensity were observed in male trained singers on high pitch tone (Qx;p = .025, intensity;p < .001). Beacasue of increasing of Qx and intensity, vocal efficiency was also significantly increased in male singers (p < .001). The trained singers' phonation was more efficient than untrained singers. The result means that the trained singers can increase the loudness with little changing of mean flow rate, subglottic pressure but more increasing of glottic closed quotients.

• Nuclear Engineering and Technology
• /
• 제38권3호
• /
• pp.277-284
• /
• 2006

In order to ensure the structural integrity of nuclear welded structures during design life, the fatigue life has to be evaluated by fatigue analysis procedures presented in technical codes such as ASME B&PV Code Section III. However, existing fatigue analysis procedures do not explicitly consider the presence of welded joints. A new fatigue analysis procedure based on a structural stress/fracture mechanics approach has been recently developed in order to reduce conservatism by erasing uncertainty in the analysis procedure. A recent review of fatigue crack growth data under various mean loading conditions using the structural stress/fracture mechanics approach, does not consider the mean loading effect, revealed some significant discrepancies in fatigue crack growth curves according to the mean loading conditions. In this paper, we propose the use of the stress intensity factor range ${\Delta}K$ characterized with loading ratio R effects in terms of the structural stress. We demonstrate the effectiveness in characterizing fatigue crack growth and S-N behavior using the well-known data. It was identified that the S-N data under high mean loading could be consolidated in a master S-N curve for welded joints.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2005년도 추계학술대회 논문집
• /
• pp.17-22
• /
• 2005

An experimental study was carried out to investigate the effect of local ultrasonic forcing on a turbulent boundary layer. Stereoscopic particle image velocimetry (SPIV) was used to probe the characteristics of the flow. A ultrasonic forcing system was made by adhering six ultrasonic transducers to the local flat plate. Cavitation which generates uncountable minute air-bubbles having fast wall normal velocity occurs when ultrasonic was projected into water. The SPIV results showed that the wall normal mean velocity is increased in a boundary layer dramatically and the streamwise mean velocity is reduced. The skin friction coefficient ($C_{f}$) decreases $60\%$ and gradually recovers at the downstream. The ultrasonic forcing reduces wall-region streamwise turbulent intensity, however, streamwise turbulent intensity is increased away from the wall. Wall-normal turbulent intensity is almost the same near the wall but it increases away from the wall, In tile vicinity of the wall, Reynold shear stress, sweep strength and production of turbulent kinetic energy were decreased. This suggests that the streamwise vortical structures are lifted by ultrasonic forcing and then skin friction is reduced.

• 설비공학논문집
• /
• 제5권4호
• /
• pp.235-242
• /
• 1993

The flow characteristics of developing turbulent pulsating flows are investigated experimentally in the entrance region of a square duct ($40mm{\times}40mm$ and 4,000mm). Mean velocity profiles, turbulence intensity and entrance length are measured by using a hot-wire anemometer system together with data acquisition and processing systems. It is found that the velocity waveforms are not changed in the fully developed flow region where that $x/Dh{\geq}40$. For turbulent pulsating flow, the turbulent components in the velocity waveforms increase as the dimensionless transverse position approaches the wall. Mean velocity profiles of the turbulent steady flows follow the one-seventh power law profile in the fully developed flow region. Turbulence intensity increases as the dimensionless transverse position increases from the center to the wall of the duct, and is slightly smaller in the accelerating phase than in the decelerating phase for the turbulent pulsating flows. The entrance length of the turbulent pulsating flow is about 40 times as large as the hydraulic diameter under the present experimental conditions.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집B
• /
• pp.267-271
• /
• 2000

The local heat transfer rate of an axisymmetric submerged air jet impinging on normal to a heated flat plate was investigated experimentally with varying solidity of mesh screen. The mean velocity and turbulent Intensity profiles of streamwise velocity component were measured using a hot-wire anemometry. The temperature distribution on the heated flat surface was measured with thermocouples. The screen installed in front of the nozzle exit(behind of 35mm) modify the jet flow structure and local heat transfer characteristics. For higher solidity screen, turbulence intensity at core lesion is high and increases the local heat transfer rate at nozzle-to-plate spacings(L/D<6). For larger nozzle-to-plate spacings(L/D>6), however, the turbulent Intensities of all screens tested in this study approach to an asymptotic curve, but the small mean velocity at the core region reduces the local heat transfer rate for high solidity screens.

• 한국수산과학회지
• /
• 제28권6호
• /
• pp.805-811
• /
• 1995

Final biomass yields (peak optical density) and growth rates (divisions/day) of seven clones of Skeletonema costatum from Korean coastal waters were measured to understand their intraspecific variations in the light intensity niche component under $25^{\circ}C$ condition. Daily growth rates of 6 of 7 S. costatum, clones were maximum at 6000 lux while that of YS4, a neritic clone, was maximum at 9000 lux. The final biomass yields of 4 of the 7 S. costatum clones were maximum at the lowest light intensity of 2000 lux. Minimum final biomass yields were found at 9000 lux in all the S. costatum clones other than an estuarine clone, HDC9. The intraspecific variations of the mean growth rate and mean final biomass yield under each of the three different light intensity in terms of the coefficient of variation were not greater than 10% in any of the 7 S. costatum clones.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
• /
• pp.128-134
• /
• 2006

A characterization of turbulent reacting flows has proved difficult owing to the complex interaction between turbulence, mixing, and combustion chemistry. There are many types of time scales in turbulent flame which can determine flame structure. This counter jet type premixed burner produces high intensity turbulence. The goal is to gain better insights into the flame structures at high turbulence. 6 propane/air flames gave been studied with high velocity fluctuation in bundle type nozzle and in one hole type nozzle. By measuring velocity fluctuation, turbulent intensity and integral length scale are obtained. And sets of OH LIF images were processed to see flame structure of the mean flame curvatures and flame lengths for comparison with turbulence intensity and turbulent length scales. The results show that the decrease in nozzle size generates smaller flow eddy and mean curvatures of the flame fronts, and a decrease in Damkohler number estimated from flow time scale measurement.