• 한국소음진동공학회논문집
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• 제22권4호
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• pp.307-317
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• 2012

The LRT(light rail transit) system, which has medium transport capacity between subway and bus is an advanced transportation system. It has many benefits like chap construction and operational cost down through driverless and flexible route planning. The rubber tired AGT(K-AGT) is a kind of LRT, which has rubber wheels and side guides. The side guides has many advantages, but brings vibration and noise problems from the friction between the guide rail and the wheels. This is the major source for the of passengers' discomfort. The purpose of this paper is to analyze dynamic characteries and running stability of the rubber tired AGT localization bogie if the AGT's speed is increased from 70 km/h to 80 km/h. The current design parameters of bogie suspension, as it is designed, was examined to satisfy the comfort index of the railway vehicle in performance test.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.357-360
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• 2002

Nowadays, the improvement and development of Multi-media, information and communication technology are rapidly processed. And many products, for example, digital camera, digital camcorder, and PDA, are used for them. They need large data storage capacity and small size, light storage system. Due to that, many studies and researches in data storage system have been carried out. Especially, micro drive system was presented by IBM.(1) However, its system is expensive and uneasy to be portable. In ODD technologies, 1 inch drive system is not yet or in processing status.(2) If to be possible and to be come up, it is cheap than HDD system and easy to transfer information. In this paper, a miniaturized actuator(about linch) is designed and tested for ODD system. Specially, it is adapted for NFR(Near-field Recoding) system using SIL(Solid Immersion Lens). It is the dual-servo actuator which consists of a coarse actuator and fine actuator. Its actuating force generation method is VCM(Voice Ceil Motor). The fine actuator has 4-wire suspensions and bobbin wrapped by coil and includes focusing motion as well as tracking motion. The coarse actuator has an actuating coil and V-grooved guide mechanism. Also, the characteristics of the designed actuator is estimated by sine-swept mode and LDV(Laser Doppler Vibro-meter).

• 한국정밀공학회지
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• 제22권9호
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• pp.27-33
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• 2005

This study deals with the truing of diamond wheel fur the manufacture of micro v-shaped grooves with fine sharp edges in the grinding. Fine micro v-shaped grooves are key components to fabricate LGP(light guide plate), optical fiber connector and so on. Conventional v-shaped groove methods such as etching and lithography are difficult to make grooves with accuracy and cutting by lathe is difficult to select target materials. Therefore, as a preliminary stage to developing the grinding technology that will be expected fabrications for micro 3-dimensional structure of high effectivity and accuracy and freed up the restrictions of machinability to the materials for micro v-shaped grooves, truing is carried out with resin bond diamond wheel and electroforming diamond wheel using a cup-type truer. From the experimental results, it is found that the effects according to working direction of the cup-type truer and the restrainable methods of plastic deformation that is generated at wheel edge are examined. As a result, fine micro v-shaped diamond wheel was obtained, which are applicable to micro grinding for optical devices.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.818-821
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• 2004

With a rapid development in the area of micro and ultra precision technology, the micro surface machining of small size parts are explosively increased. Especially, to improve efficiency of various beams in lens and reflector, non-rotational symmetric form and several mm level heights changeable surface can be machined at a time. These geometric complex 3D surface cannot be machined by general short stroke FTS. The long stroke FTS if firmly needed to move directly several mm and have nm level positioning accuracy for the complex surface form. The long stroke FTS used linear motors to drive moving unit long and fine, aero static bearings to decrease friction and moving errors in guide way, optical linear scale with nm level resolution to measure position of FTS. Furthermore, to increase the performance of acceleration of FTS, the light material, such as AL is used for the structure and the high stiffness box type structure is selected. In this paper, the genetic algorithm approach is described to determine a set of design parameters for auto tuning. The authors have attempted to model the design problem with the objective of minimizing the error, such as variable pattern change. This method can give the better alternative than existing other method.

• 한국항행학회논문지
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• 제15권5호
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• pp.839-844
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• 2011

기존의 위치인식 시스템을 활용한 방법으로는 적외선, 초음파, RFID, GPS, UWB, 신호 세기 등을 이용한 방법이 있지만, 각 시스템은 음영지역에서의 위치인식이 필요하다. 본 논문에서는 협력 스펙트럼 센싱(Cooperative Spectrum Sensing)을 이용해 사물이 움직이는 경로와 위치를 판단하고, 센서가 위치한 정해진 경로를 이탈할 경우에 이를 인지해 정상적인 경로로 이동할 수 있도록 도와준다. 협력 스펙트럼 센싱은 1차 사용자에게 간섭 영향을 미치지 않는 범위 내에서 전파인지 사용자에게 최적의 전송 전력과 변조 레벨을 결정할 수 있기 때문에 주파수의 사용 효율을 높일 수 있다. 본 논문에서는 협력 스펙트럼 센싱 기법을 이용한 위치인식 시스템을 제안하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 추계학술대회 논문집
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• pp.73-76
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• 2009

The optical structure of edge-lit LED backlight has been optimized via simulation study in order to remove bright spots appearing on the entrance region of the light guide plate (LGP) and thus to improve the luminance uniformity. The density of scattering dots located on the back surface of LGP was adjusted according to the location of LED's. In addition, lenticular lenses or a diffuse transmissive surface were formed on the side surface of LGP facing the LED's, and the density of lenticular lenses was optimized for redistributing rays emitted from LED's into wider angles. The bright spots which could be seen from conventional LED backlight were removed by the combination of these two optical structures. The application of diffuse surface to the entrance face gave better uniformity than the application of lenticular lenses. However, dark regions still appear on the entrance region of LGP, which should be removed by more appropriate optical design for achieving better luminance uniformity on the LED backlight.

• 한국대기환경학회지
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• 제17권4호
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• pp.313-319
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• 2001

The development of ozone SRP (Standard Reference Photometer) designated as a G-7 project by the Korean Ministry of Environment began 1997 and is now nearly completed. With the completion of the ozone SRP we will not only acquire a qualification to participate in the international ozone calibration system but also enhance calibration credibility of ozone similarly to that of other ambient air pollution monitors. As the ozone SRP uses highly cleaned blank air that can be distinguished from general ozone analyzer, it is possible to reduce errors associated with the determination of ozone via elongation of the absorption length as long as 1 meter In addition, gas chopping method hat been adopted to cut down interference of other substances and time drift. Furthermore, the system has also been modified to minimize the strayed ultra-violet noise along the light path. In this paper, a new method for uncertainty evaluation has been introduced, which is guided by the ISO (International Standard Organization) GUM (Guide to the Expression of Uncertainty in Measurement) through assessments of the uncertainty type B (that was impossible to estimate before) as well as the uncertainty type A (based on statistics).

• KIEAE Journal
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• 제9권4호
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• pp.17-22
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• 2009

It is common to design the duct branches where to supply the required air flow for individual room in residential apartment house. However it is difficult to adjust the air volume adequately in small air duct branches in residential ventilation system. The purpose of this study is to figure out the performance of Multidrop chamber coupling system for the residential ventilation system. The experiments were designed to simulate apartment of $84m^2$ and established multidrop chamber duct and general duct on the ceiling of the apartment. Distribution performance of air supply rate were evaluated in this experiments. As a result, distribution performance of air supply rate in the general duct is different from designed air supply rate by about 35% ~ 50% and about 10% in the multidrop chamber system. In additional the sound insulation performance of the multidrop chamber system decreased about 20% compared with general duct system. Therefore, the multidrop chamber system is considered to satisfy proper air supply rate of each room and to improve the sound insulation performance in apartment Houses.

• Journal of the Optical Society of Korea
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• 제12권1호
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• pp.25-30
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• 2008

The optical performances of 15-inch edge-lit backlight were simulated by using a Monte Carlo ray-tracing technique. The backlight model was built by combining a wedge-type light guide plate, a diffuser sheet, a tubular fluorescent lamp with a lamp reflector, and two crossed prism sheets. Angular distributions of the luminance on each optical component obtained from simulation were consistent with those obtained from experiments on a real 15-inch backlight. The constructed backlight model was used to evaluate the optical performances of a micro-pyramid film. It was found that the on-axis luminance gain on the pyramid film is higher than that on one prism film but much lower than that on the two crossed prism films. These results suggest that a reliable simulation model can be used to develop new hybrid films and to optimize the optical structure of edge-lit backlight in order to reduce the developmental period.

• 소성∙가공
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• 제22권2호
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• pp.80-85
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• 2013

The surface integrity of micro-machined products affects the performance of products significantly. Micro-burrs resulting from micro-cutting degrades the surface quality. Therefore it is desired to eliminate them completely and many studies have been undertaken for this purpose. In this study, micro-end-milling was carried out on nickel alloy and brass materials commercially used for light guide plate mold in 3-D optical devices. After completing this micro-machining, the burr heights were measured with a microscope. Then, deburring was done on the machined edges using the MR jet polishing method. A jet angle of $0^{\circ}$ and deburring times of 1, 3, and 5 min. were chosen. It was found that burrs were completely eliminated after 5 min of MR fluid jet polishing.