• 한국전자파학회논문지
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• 제23권6호
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• pp.731-739
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• 2012

일반적으로 평행평판 도파관에서 발생하는 가장 낮은 고차 모드는 $TE_1$ 모드와 $TM_1$ 모드로 알려져 있다. 본 논문에서는 평행평판 도파관에서 이보다 더 낮은 주파수에서 발생하는 TE 모드에 대해 고찰한다. 평행평판 도파관의 열려 있는 양 옆을 완전 자성 도체(PMC)로 가정하여 TE 모드의 전자계 분포를 유도하였고, 이 모드의 존재를 평행평판 도파관 공동기를 제작하여 실험함으로써 실증하였다. 열려 있는 양 옆의 경계가 완전한 자성 도체가 아니므로 인해 나타나는 특성에 대해서도 고찰하였다.

• 한국진공학회지
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• 제15권1호
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• pp.24-30
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• 2006

광학공동 적분 투과 분광법(integrated cavity output spectroscopy, ICOS)은 파장가변 레이저와 광학공동을 이용해 미량기체의 절대 밀도를 고감도로 측정할 수 있는 실시간 흡수 분광계측 기법이다. 이 기법은 압전 소자를 이용해 길이가 변조되는 고 피네스(high finesse) 파브리-페로 공동(Fabry-Perot cavity)을 공명 투과하는 연속파 파장 변조 레이저의 적분 출력으로 부터 공동 내부 시료의 분광 흡수량을 측정하는 원리를 이용한다. 본 연구에서는 764,7nm 파장 근처에서 파장이 변조되는 외부 공진기 반도체 레이저를 광원으로 사용하고, $99.997\%$의 높은 반사율을 갖는 거울로 구성된 파브리-페로 공동을 이용해 파장에 따른 투과 감쇠 신호를 발생시키는 실험 장치를 구성하였다. 산소 기체에 대한 측정 실험을 수행한 결과, 최소 흡수계수 $8.45\times10^{-8}cm^{-1}$에 해당하는 미량기체 밀도를 측정할 수 있는 성능을 얻었다.

• 천문학회지
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• 제20권1호
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• pp.27-47
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• 1987

In the present study a two-mode, separately concurring resonant cavity model is proposed for theoretical interpretation of the 3 minute umbral oscillation. The proposed model has been investigated by calculating the transmission coefficients of the waves propagating through the umbral photosphere (photospheric weak-field cavity) and chromosphere (chromospheric strong-field cavity) into the corona, for 3 different umbral model atmospheres by Staude (1982), Beebe et al. (1982) and Avrett (1981). In computing the transmission coefficients we made use of multi-layer approximation by representing the umbra] atmosphere by a number of separate layers with (1) temperature varying linearly with depth and (2) temperature constant within each layer. The medium is assumed to be compressible, non-viscous, perfectly conducting under gravity. The computed resonant periods, transmission spectra, phase spectra, and kinetic energy density of the waves associated with the oscillations are presented in comparison with the observations and their model dependent characteristics are discussed.

• 전기학회논문지
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• 제56권6호
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• pp.1165-1169
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• 2007

In this study, a novel sensor system for measuring the temperature inside an oral cavity is proposed. With this aim, a small size of thermistor was used for resolving the cavity's temperature with the resolution of $0.1^{\circ}C$. To evaluate effectiveness of our sensor system, the temperature and its output voltage characteristic, and the specifications of response are investigated. It turned out to be that our sensor system has a linear property in terms of temperature variations for a healthy subject's body temperature range and has a good response time within 3 seconds. Also, in order to investigate the medical application, our sensor system is sought to measure the real temperature variations of a subject's oral cavity and ark shell especially for 'before' and 'after' exercise mode.

• Journal of Mechanical Science and Technology
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• 제17권4호
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• pp.590-598
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• 2003

A computational aero-acoustic (CAA) method is used to predict the tonal noise generated from a cavity of automobile door seals or gaps at low flow Mach numbers (A$\_$$\infty$/=0.077 and 0.147) In the present method, the acoustically perturbed Euler equations are solved with the acoustic source term obtained from the unsteady incompressible Navier-Stokes calculations of the cavity flow in self-sustained oscillations. The aerodynamic and acoustic fields are computed for the Reynolds numbers based on the displacement thickness, Re$\_$$\delta$*/=850 and 1620 and their fundamental mode characteristics are investigated. The present method is also verified with the experimentally measured sound pressure level (SPL) spectra.

• Journal of Advanced Marine Engineering and Technology
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• 제24권2호
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• pp.97-103
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• 2000

Gas pulsation discharged from the cylinder causes noise in the rotary compressor. Mufflers are usually used to reduce the noise generated by the gas pulsation. The muffler has been designed to maximize the acoustic transmission loss of the muffler. The gas which went through muffler is discharged to the cavity in compressor. Thus, the acoustic characteristics of cavity should be taken into account in muffler design. In this paper, the program for the acoustic substructure synthesis method is developed. This program can be interfaced with SYSNOISE which is commercial acoustic package. Several types of mufflers designed to have the better acoustic performance are suggested in this work and compared with the existing commerical muffler in the compressor. The acoustic performance of mufflers taking into consideration of the cavity in the compressor is also carried out by the developed program.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1994년도 추계학술대회논문집; 한국종합전시장, 18 Nov. 1994
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• pp.288-294
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• 1994

A study of prediction and qualification techniques for structure borne booming noise is presented in this paper. Result from acoustic normal mode finite element analysis of a 1/2 size vehicle cavity sample model is compared to the that from an experiment. Coupled structural-acoustic analysis is performed on a 1/4 size vehicle cavity sample model surrounded by 2 mm thick normal steel plates. Interior noise levels around passensger's ear position are predicted and reduced by structural modification based on panel participation factor analysis about the sample cavity model. Futhermore, optimization technique in application of anti-vibration pad is studied.

• 한국자동차공학회논문집
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• 제16권3호
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• pp.102-110
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• 2008

It is well known that the acoustic cavity inside the tire-wheel assembly contributes to vehicle interior noise and ride comfort. In this paper, we performed acoustic and structural modal testings by varying the temperature ranging from $20^{\circ}\;to\;45^{\circ}C$ to investigate the effects of temperature on acoustic cavity resonance and structural vibration characteristics for unloaded and loaded tires. The testing has given us some findings, which are reported in this paper.

• Journal of Periodontal and Implant Science
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• 제34권4호
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• pp.723-731
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• 2004

Helicobacter pylori(H. pylori) has been associated with the cause of chronic gastritis, peptic ulcers and gastric cancer. Although it may be transmitted through the oral cavity, it is unknown whether the oral cavity acts as a reservoir of H. pylori. The purpose of this study was to investigate the mode of detection of H. pylori in oral cavity of adult periodontitis patients with plaque and periodontal pocket which atmosphere is grown well H. pylori. We analysed detection rate of H. pylori in saliva and subgingival plaques of 17 adult periodontitis patients without symptoms of gastroduodenal disease by nested PCR. Samples tested comprised saliva and subgingival plaques from central incisor, 1st premolar and 1st molar. H. pylori DNA was not identified in saliva from all patients. The detection rate in subgingival plaque from incisors, premolars and molars was 5.9%, 5.9% and 17.7%, respectively. In conclusion, the dental plaque and periodontal pocket (especially, of molars) in adult periodontitis can be favorable reservoir of H. pylori and may be the source of infection and transmission of H. pylori.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.173-178
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• 2000

A prototype for a highly sensitive, automated measurement system for the microwave surface resistance of high-T$_c$ superconductor films was set up, and tested by measuring the microwave surface resistances of high-T$_c$ YBa$_2$Cu$_3$O$_{7-{\delta}}$(YBCO) films at the frequency of about 19.6 GHz and the temperature of 30 K ${\sim}$ 90 K. An open-ended TE$_{011}$ mode sapphire-loaded cylindrical cavity resonator was used as the measurement probe, where YBCO films were used as the endplates of the cylindrical cavity. The characteristics of the measurement system include functions to display the unloaded ${\varrho}$ and the resonant frequency of the TE$_{011}$ mode resonator as well as the microwave surface resistance of the YBCO films, all simultaneously as a function of temperature. Applicability of the measurement system for investigating the homogeneity in the microwave properties of large high-T$_c$ superconductor films is discussed.