• Imaging Science in Dentistry
• /
• 제34권1호
• /
• pp.19-23
• /
• 2004

Purpose: To compare the diagnostic accuracy of Kodak Insight film with other intra-oral films in the detection of dental caries. Materials and Methods : Periapical radiographs of 99 extracted human teeth with sound proximal surfaces and interproximal artificial cavities were made on Kodak Ultra speed, Ektaspeed, Agfa Ektaspeed and Kodak Insight films and automatically processed. Six dentists examined the presence of dental caries using a five-point confidence rating scale and compared the diagnostic accuracy by ROC (Receiver Operating Characteristic) analysis and ANOVA test. Results: The sensitivity of Kodak Ultra speed, Ektaspeed, Agfa Ektaspeed and Insight film were 0.84, 0.77, 0.75 and 0.79 respectively. The specificity of Kodak Ultra speed, Ektaspeed, Agfa Ektaspeed and Insight film were 0.97. 0.95. 0.96 and 0.94 respectively. The mean ROC areas (Az) of Kodak Ultra speed, Ektaspeed, Agfa Ektaspeed and Insight film were 0.917, 0.910, 0.894, 0.909 respectively. There was no significant differences between Az of Insight film and other films (p = 0.178). Conclusion: Theses results suggested that Kodak Insight film have the comparative diagnostic accuracy of dental caries with Ultraspeed and Ektaspeed films.

• 소성∙가공
• /
• 제18권1호
• /
• pp.39-44
• /
• 2009

This paper is concerned with forming technology of an automotive front side member part with ultra high strength steel sheet of DP980. The forming technology considered in this paper is the draw & form type, which installs the upper pad and lower pad to produce the complicated shape of ultra high strength steel sheet. In order to produce sound product, comparison between form type and draw & form type and between draw type and draw & form type are investigated by FE-analysis. FE-analysis is carried out with commercial sheet metal forming analysis S/W, DYNAFORM. It was shown from FE-analysis that the draw & form type satisfied the required specifications such as the dimensional accuracy and soundness of automotive front side member part. The effectiveness of the analytical result was verified by the experiment. From this investigation, the draw & form type is proved to be able to supply useful forming technology in forming ultra high strength steel.

• 감성과학
• /
• 제9권2호
• /
• pp.133-140
• /
• 2006

본 연구에서는 의복 착용 시 직물이 스치면서 발생하는 왕복마찰음에 대한 물리적 소리특성과 주관적 감각을 고찰하기 위해, 왕복운동을 이용한 직물마찰음발생장치를 개발하고 이 장치를 이용하여 5가지 직물의 왕복마찰음을 녹음한 후, 총음압(LPT), 음압차(${\Delta}L$), 주파수차(${\Delta}f$)를 계산하였다. 왕복마찰음에 대한 주관적 감각은 7개의 소리감각(부드러움, 시끄러움, 날카로움, 맑음, 거침, 높음, 유쾌함)에 대하여 의미미분척도로 평가되었다. 나일론 태피터와 폴리에스테르 레노 직물의 왕복마찰음은 높은 LPT를 나타내어 시끄럽고 날카롭고 거칠며 불쾌한 소리로 인지되었다. 반면 LPT와 ${\Delta}f$의 값이 작은 폴리에스테르 울트라스웨이드와 실크 크레이프드신 직물의 왕복 마찰음은 부드럽고 조용한 소리로 평가되었다. 마찰방향(왕복 방향, 한 방향)에 따른 직물의 마찰음 비교시, 왕복 방향 마찰음은 한 방향 마찰음보다 더 날카롭고 시끄럽고 거칠게 인지되었으며 마찰방향에 상관없이 LPT가 소리감각을 예측하는 중요한 요인으로 나타났다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 춘계학술대회논문집
• /
• pp.594-599
• /
• 2000

Two basic acoustic quantities, the characteristic impedances and the propagation constants, of the two different ultra lightweight concrete absorbers were examined with impedance tube method. A transmission loss was tested and compared with theoretical values. The results show that these kinds of sample have proper sound absorption and transmission loss capabilities. It means that they can be used in various fields where noise proof is needed.

• 콘크리트학회논문집
• /
• 제12권6호
• /
• pp.91-98
• /
• 2000

Porous concrete having continuous voids is gaining more interest as an ecological material. It has several useful functions such as water and air permeability, sound absorption, etc. Its strengths are considerably lower than those of conventional concrete due to the large and continuous voids in it. This study has been carried out to investigate the influence of mix factors and mixture proportion of aggregate on the strengths and water permeability of porous concrete. And it has been carried out to investigate the evaluation of void of porous concrete by the ultra-sonic pulse velocity. The results f this study are as follows: 1) The theoretical void ratio has greater influence than any other factor on the strengths and water permeability of porous concrete. And it is a little affected by the replacement proportion of silica-fume and mixture proportion of aggregate. 2) Because the coefficients of correlation between the void ratio and ultra-sonic pulse velocity were relatively high, it will be possible that the void ratio is predicted by the ultra-sonic pulse velocity.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -1
• /
• pp.389-392
• /
• 2002

In this paper, we implemented system to detect obstacle in that develop a guidance robot for the visually impaired through sound. We used ultra sonic sensor to detect obstacle. We supposed the algorithm that classifies distance and direction of obstacle using information that produce correct warning negative sign according to direction and distance of obstacle. According to the experiment, a reagent could detect obstacle without sight information.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 춘계학술대회 논문집
• /
• pp.1489-1491
• /
• 2004

PD in air is accompanied by light, sound and electromagnetic wave. Light and sound can be prevented from blocking between PD sources and sensor but electromagnetic wave can be transferred to long distance without any interference an captured by antenna. This paper investigated the wideband antenna is appropriate for sensing Partial discharge in air. PD was generated from simulated PD source which consist of needle and flat electrode with small gap. Signals obtained from wideband antenna were diminished in both time and frequence region with the distance between PD source and antenna.

• 한국정밀공학회지
• /
• 제14권5호
• /
• pp.85-91
• /
• 1997

Air grinding time in grinding process has a great effect on its efficiency due to low feedrate. This paper presents a reduction methos of air grinding time in cylindrical plunge grinding operation. Tje reduction of air grinding time is accomplished by finding the distance between contact point and rising point of ultra- sonic signal of the grinding wheel to workpiece. It uses a variation of sound signal generated by the flow of coolant when the grinding wheel approaches to workpiece. The ultrasonic sensor with 23 kHz center fre- quency and 8 kHz bandwidth is used to find the nearest approaching point(NAP). Monitoring and control system of the grinding conditions is implemented with CNC controller to control feedrate override and ultrasonic sensor to find NAP. The experimental result shows that the ultrasonic signal is a good measure- ment to find NAP. But it needs the considerations for the effect of the relationship between flowrate of coolant and diameter of workpiece.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1996년도 추계학술대회논문집
• /
• pp.99-104
• /
• 1996

A proform for engine valve was designed by finite element method. In the preform design of engine valve, various initial billets are simulated for better preform to get sound final product. Here a preform is design to get desirable metal flow in the forming so that the final product has more uniform strain distribution. after forming. The analysis of the micro-structure of the value formed through the designed process was also performed and result was compared with that of simulation.

• 한국콘텐츠학회논문지
• /
• 제10권9호
• /
• pp.285-292
• /
• 2010

본 연구는 8방향 경사와 회전운동이 만성요통환자의 통증과 동적균형에 미치는 영향을 알아보고자 시행되었다. 20명의 만성요통환자가 실험에 참여하였다. 10명(실험군)은 물리치료기구[온열팩{Hot Pack(H/P), 경피신경자극{Transcutaneous Electric Nerve Stimulation(TENS)}, 초음파{Ultra Sound(U/S)}]를 이용한 치료를 받은 후에 8방향 경사와 회전운동을 실시하였고 나머지 10명(대조군)은 물리치료기구를 이용한 치료만 실시되었다. 치료 중재는 주 3회, 6주 동안 적용되었다. 동적균형과 통증은 Star Excursion Balance Test(SEBT)과 Visual Analog Scale(VAS)를 이용하여 측정하였다. VAS 점수는 두 그룹 모두 감소하였으나 실험군에서 보다 유의하게 감소하였다. 동적균형 능력 또한 실험군에서 보다 유의한 증가를 나타내었다. 따라서 8방향 경사와 회전운동은 만성요통환자의 통증과 동적균형에 효과가 있었다고 사료된다.