• Journal of Mechanical Science and Technology
• /
• 제15권2호
• /
• pp.152-159
• /
• 2001

In this paper it is intended to set-up a sound model of the 60,000rpm 100kW prototype APU gas turbine rotor-bearing system, and particularly to investigate the influences of the tie shaft on the rotordynamic characteristics of the entire APU gas turbine rotor-bearing system, employing the dual shaft model. Firstly, a mock-up APU rotor has been constructed to test and verify the model. Analytical natural frequency results have agreed with the corresponding modal test ones to within 5% difference. Then, the rotordynamic characteristics of the prototype APU rotorbearing system have been investigated. Natural vibration and unbalance response analyses results have shown that the inner tie shaft resonance can cause high enough vibration of the outer main rotor shaft. This could be a concern as the rotor journals operate on very thin air film at high speed. It is concluded as a conservative design practice that the inner tie shaft should be explicitly modeled in the rotordynamic analysis of the APU rotor-bearing system.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.347-351
• /
• 1997

A micromachined piezoelectic cantilever transducer,which works both as a microphone and as a microspeaker,has been fabricated and tested. The 2000*2000*3.mu.m .sap2. cantilever has oxide(ZnO)piezoelectric thin film on a supporting layer of low-pressure chemical-vapor-deposited(LPCVD)low-stress siliconnitride. A highlight of the fabrication process which may also be relevant for other micromachined stuctures is the technique for producing a flat,multilayer cantilever. The measured microphone sensitivity is fairly constant at 2 mV/.mu.bar in the low frequency range and rise to 20 mV/.mu.bar at the lowest resonant frequency of 890 Hz. The 2 mV/.mu.bar sensitivity is the highest report to data for a microphone with a micromachined diaphragm. When measured into a 2 cm/sap3 coupler with 4V (zero-park)drive,the microspeaker output sound pressure level(SPL) is 75 dB at 890 Hz. It increases to approximately 100dB SPL at 4.8kHz with 6V(zero-park)drive. The measured microphone frequency response agrees well with the results of an ABAQUS simulation.

• 한국소음진동공학회논문집
• /
• 제13권7호
• /
• pp.499-507
• /
• 2003

This paper presents a method for active noise control (ANC) in a duct by using a ring-tyPe smart foam. The ring-type smart foam consists of an elastic porous material of lining shape and a PVDF film embedded In the material. The PVDF element acts as a secondary sound source to reduce the noise. Active noise control using a ring-type smart foam is only effective locally because of the way to excite radially. To enlarge the quiet zone, the duct Is lined with additional acoustic foam between the smart foam and the error microphone. When cancellation path ks optimized by the LMS/RLS algorithm, the computation power is reduced while control performance Is maintained. The filtered-x LMS algorithm is used to minimize the error signal.

• 한국정밀공학회지
• /
• 제19권10호
• /
• pp.37-44
• /
• 2002

The dynamic behavior of rotor-bearing system has been investigated using finite element method. A procedure is presented for dynamic modeling of rotor-bearing system which consists of shaft elements, rigid disk, flexible bearing and support structure. A finite element model including the effects of rotary inertia, shear deformation, gyroscopic moments is developed. Linear stiffness and damping coefficients are calculated for 2 lobe sleeve bearing. The whirl frequency, mode shape, stability and unbalance response of rotor system including effects of bearing coefficient and support structures are calculated.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
• /
• pp.45-46
• /
• 2005

The piezoelectric ZnO thin films were deposited onto Al/Si substrate in order to figure out the crystalline and the residual stress of deposited films. As the $Ar/O_2$ gas ratio is increased, c-axis orientation of deposited films is significantly enhanced and also the residual stresses of ZnO films are all compressive. They are decreased from -1.2 GPa to -950 MPa as the $Ar/O_2$ gas ratio is increased. A diaphragm-based piezoelectric microspeaker fabricated on ONO films shows about 14 mPa output pressure at 1 kHz with $8V_{peak-to-peak}$.

• 센서학회지
• /
• 제25권6호
• /
• pp.412-417
• /
• 2016

Scent display is used mainly to augment immersion, reality and emotion, besides provide more tension and suggestion. However, this paper pay attention to effect of smells as ambient media, and propose a notification service using scents without sound and vibration when a user has new mail, test message and phone call. And we designed a scent service platform and API function for easy application of scent notification service. We demonstrated feasibility by experiment using smart phone and self-producted scent device.

• 센서학회지
• /
• 제30권5호
• /
• pp.273-278
• /
• 2021

Here, we studied the change in the mechanical stiffness of a diaphragm according to the corrugation pattern. The diaphragm consists of a silicon oxide and nitride double layer; a corrugation pattern was formed by dry etching, and the diaphragm was released by wet etching. The fabrication of the thin film was verified using focused ion beam and scanning electron microscopy images. The mechanical stiffness of the diaphragm was obtained by measuring the surface vibration using a laser Doppler vibrometer while applying external sound pressure. Flat squares, diaphragms with square corrugations, and circular corrugation patterns were measured and compared. The stiffness of the diaphragm with a corrugation structure was found to be smaller than that without a corrugation structure; in particular, circular corrugation showed a better effect because of the high symmetry. Furthermore, the effect of corrugation was theoretically predicted. The proposed corrugated diaphragm showed comparable flexibility with the state-of-the-art MEMS microphone diaphragm.

• 한국콘텐츠학회논문지
• /
• 제14권4호
• /
• pp.110-122
• /
• 2014

우리나라의 영화산업은 지난 10여 년 간 비약적으로 성장해 왔으며, 이에 따라 영화의 흥행이나 영화관 매출에 영향을 미치는 요인들에 대한 학계의 관심도 점차 높아지고 있다. 지금까지 영화의 흥행이나 영화관 매출에 대한 연구들은 대부분 영화의 제작이나 배급 또는 상영단계의 영화컨텐츠에 초점을 두고 있다. 그런데 우리나라 영화산업은 미국과는 다르게 대기업에 의한 제작, 배급, 상영단계가 수직계열화 되어 있고, 이들이 운영하는 멀티플렉스가 전체 극장의 80%를 차지하고 있다는 점에서 영화 컨텐츠 요소가 영화관 매출에 끼치는 영향보다는 오히려, 영화관 자체의 시설이나, 영화관 주변의 상권 입지요인이 영화관 매출에 더 큰 영향을 미칠 수 있을 것으로 보인다. 본 연구는 기존의 상권이나 입지연구에서는 상대적으로 덜 다루어졌던 자원 기반이론과 산업조직론의 S-C-PParadigm을 바탕으로, 영화관 자체의 내부환경 즉, 영화관 특성 요인과 영화관의 외부환경인 상권 입지요인(입지특성, 접근특성, 인구통계특성)이 영화관 매출에 끼치는 영향을 분석하였다. 분석결과, 상영관 평균 수용인원은 대도시 뿐만 아니라 중소도시의 영화상영관에도 매출에 가장 중요한 영향을 끼치는 변수로 나타났으며, 대도시(인구 100만명 이상)에 위치한 영화상영관은 상대적으로 영화관 특성요인(진동좌석, 특수음향시설, 프리미엄영화관, VIP라운지의 유무)들이, 중소도시에 위치한 영화관은 입지특성(쇼핑몰 입점여부, 경쟁업체)이나 접근특성(지하철역, 버스노선)이 더 영화관 매출에 영향을 미치는 것으로 나타났다. 마지막으로 연구의 시사점과 한계점에 대해 기술하였다.

• 디지털융복합연구
• /
• 제15권9호
• /
• pp.453-461
• /
• 2017

영화 속 영상 이미지는 그 어느 때보다 화려해지고 표현영역과 대상이 무한대로 넓어졌지만 상상력의 범위가 넓혀졌다고는 말할 수 없으며 오히려 대중문화의 태동기였던 60-70년대는 다양한 영상 문법과 테크닉을 통해 자신만의 작가 주의적 영상 스타일과 표현양식을 구현하는 영화들이 속속 등장하는 시기였다. 기술적 완벽성과 실험적 스타일을 추구해온 명장 스탠리 큐브릭 감독의 '시계태엽오렌지'는 전통적인 영상문법을 활용하여 만들어진 수작으로 당시 파격적인 소재와 수준 높은 예술적 표현기법으로 큰 반향을 얻었다. 이러한 여러 기법은 극단적인 폭력과 선정적인 영화에 대해 관객을 상황에 대한 감정적인 동조가 아닌, 아이러니를 통한 이성적인 관찰로 유도하였다. 이것은 감독의 목적이 기술적 완벽성에 있었던 것이 아니라 현실 사회의 모순을 드러내고, 나아가 사회 자체의 존재의미에 대해서 성찰 하게끔 하는 것이였기 때문이다. 이러한 창의적인 전통적 영상문법과 표현 방법 등은 이면에 존재하는 의미를 관객에게 무의식적으로 인지케 함으로서 의도한 메시지를 보다 강하고 효과적으로 전달케 하며 예술적인 깊이도 동시에 창출 가능케 하는 훌륭한 영상 스타일이라고 할 수 있다.

• Imaging Science in Dentistry
• /
• 제30권4호
• /
• pp.265-274
• /
• 2000

Purpose: The aims of the present study are to determine the optimum compression rate in terms of file size reduction and diagnostic quality of the images after compression and evaluate the transmission speed of original or each compressed image. Materials and Methods: The material consisted of 24 extracted human premolars and molars. The occlusal surfaces and proximal surfaces of the teeth had a clinical disease spectrum that ranged from sound to varying degrees of fissure discoloration and cavitation. The images from Digora system were exported in TIFF and the images from conventional intraoral film were scanned and digitalized in TIFF by Nikon SF-200 scanner (Nikon, Japan). And six compression factors were chosen and applied on the basis of the results from a pilot study. The total number of images to be assessed were 336. Three radiologists assessed the occlusal and proximal surfaces of the teeth with 5-rank scale. Finally diagnosed as either sound or carious lesion by one expert oral pathologist. And sensitivity, specificity and k value for diagnostic agreement was calculated. Also the area (Az) values under the ROC curve were calculated and paired t-test and oneway ANOVA test was performed. Thereafter, transmission time of the image files of the each compression level was compared with that of the original image files. Results: No significant difference was found between original and the corresponding images up to 7% (1 : 14) compression ratio for both the occlusal and proximal caries (p<0.05). JPEG3 (1 : 14) image files are transmitted fast more than 10 times, maintained diagnostic information in image, compared with original image files. Conclusion: 1 : 14 compressed image file may be used instead of the original image and reduce storage needs and transmission time.