• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.306-311
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• 2000

This paper deals with the development of Laser Doppler Vibrometer (LDV) that can mea~ure the tlequency and amphlude of the ultrasonic vibralion. Hc-Ne laser (632.8 om) is used as a light source, and Michelson interferometer in winch frequency of the objective beam is shIfted by Bragg cell IS adopted The frequency modulated signal centered at 40 MHz flom the PIN diode IS amplified. down-col1vel1ed to 2.5 MHz, filtered and digiLized. The voltage output that is proportional to the velocity of the vibratwg surface is obtawed using digItal PLL. A microprocessor is used to extract the frequcncy aud amplitude of the vibratIOn from the voltage output. It is found that the developed LDV can measure up to 300 kHz vibratIOn and the mlillmUITI measurable amplitude is I nm at 300 kHz. We believe thatlhis LDV can be used to measure the vibratIOn of the heavy electric maclllnery and micro-size structures. tures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.8
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• pp.1709-1715
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• 2005

This paper describes the development of 3-D web graphic library for dynamic web graphic design. The 3-D web graphic library developed in this per supports creation of 3-D objects like cube and sphere objects, elimination of hidden line and surface, and the shading of diffuse and specular reflections. It provides, in drawing, perspective projection of an object depth first sort of multiple objects, and wire frame and solid models. It also supports texture mapping function for realistic and dynamic web application in application software. Each created 3-D object gives functions for the scaling, translation, and rotation of itself. It can be used for the development of dynamic web application software and the advertisement of information for business and tourism as a 3-D web graphic library engine. It is written in 'Java' language and runs on web browsers with Java virtual machine without any dependancy of client computer system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.804-806
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• 2004

As a noninvasive imaging meathod, optical coherence tomography system has been extensively studied because it has some advantage such as imaging of high resolution, low cost, and compace size configuration. The optical power of the sample signal reflected from an object is usually very small in optical coherence tomography(OCT) due to absorption and scattering in a sample material. Furthermore, there happens a serious loss of sample signal power in a fiber coupler because it does not transfer to a photodetector but return to the optical source. In order to improve the SNR of OCT system, basic Michelson and Mach-Zehnder interferometer types were configured then, we compared simulation with measurement of reference sample Therefore, an On in configuration of Math-Zehnder interferometer was demonstrated in order to improve the signal to noise ratio

• Journal of Korea Multimedia Society
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• v.16 no.3
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• pp.375-387
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• 2013

Advanced internet service and smart equipment have caused an environment supporting various online learning anytime and anywhere, which requires learning contents optimized on a new media. Among various on/off line education related to IT, most part if it is office SW. Many oh them cannot make a good education for effective training in practical because many instructors are tend to focus on teaching simple function and use examples of formality repeatedly. In this paper we propose a new office SW education system that make use of LET(Live EduTainer) based on RTE(Real Training Environment) which maximize the effect of learning and it is integrated with GBL(Game Based Learning) which gives rise to interesting in a knowledge as well as simple teaching so that learners are absorbed on it. We'll elaborate a method for teaching and learning required in this system, design and configuration of the system.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.4
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• pp.65-70
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• 2010

A small unmanned aerial vehicle(UAV), which uses a propulsion system consisting of electric motor and battery, weighs less than 8 kg, capable of hand launch. Because it is easy to operate and able to transmit image information in real time, the use of small UAV has been increasing. However, very few analysis methods or analysis results on flight performance of the small UAV have been known so far. In this paper, the performance analysis methods of a small UAV, which is manufactured to study an electric powered UAV, are suggested and their results are achieved. Aerodynamic data of the vehicle are obtained by making use of gliding performance from actual flight test, and required thrust and required power by flight speed are predicted. In addition, the methods to predict range and endurance in case of using battery as power source are suggested and their results are achieved.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.127-135
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• 2014

Interactive-typed devices and contents that have been often applied in the field of entertainment and game are the technology that allows you to maximize the enjoyment and participation of users through the interaction of each. In this paper, we designed an interactive-typed smartphone app that is based on the Android platform, implemented the wearable Bluetooth device to control via a interactive interface with a vibration sensor and three-axis acceleration sensor. We tested the functionality and 3-axis motion's operability by using smartphone app, interface interactive-typed device that has been developed, prove useful as a wearable Bluetooth device that has the convenience of the user. Further, it is shown that by implementing the optimized protocol of the sensor data transfer over Bluetooth, it is possible to reduce the malfunction of the content of the smart phone.

• Korean Journal of Optics and Photonics
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• v.3 no.1
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• pp.55-62
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• 1992

The optical absorption characteristics of glasses colored by CdS. CdSe, $CdS_{1-x}Se_x$,ZnS, and ZnSe microcrystallites have been studied with emphasis on changes of the cut-off wavelength. The sharpcut filters with various cut-off wavelengths were fabricated by controlling the composition and the heat-treatment temperature. The cut-off wavelength shifts due to the different heat-treatment temperatures for CdS. CdSe, ZnS, and ZnSe doped SK-16 glasses were found to be relatively small(~30 nm). However, by treating the CdS1,Se, doped SK-16 glasses with different x values at the same heattreatment temperature, it was possible to obtain the filters with various cut-off wavelengths(~130 nm) without losing the high extinction coefficients of the filters. The filter glasses with various cut-off wavelngths(~100 nm) and high extinction coefficiencts were also produced by treating the CdSe and $CdS_{0.5}Se_{0.5}$ doped ZK-1 glasses at different temperatures.

• Journal of Korea Entertainment Industry Association
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• v.14 no.1
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• pp.107-116
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• 2020

The Hong Kong film "Project Gutenberg" has obtained the great achievements at the box office and public reputation due to such multiple factors as realistic counterfeit banknote production process, breathtaking gunfight scenes, brain-burning plot, unexpected reversal ending, personal charm of Chow Yun-Fat and so on. In terms of film narrative, the director utilized the narrator, Li Wen, to guide the police and audience in the limited angle of perspective into the scheme, and make the symbolic meaning image of the actor Chow Yun-Fat stengthen the audience's confirmation for the imagination of "painter", with the introduction of multiple narratives and flashback of different characters and scenes, and then finally, used the narrative structure with multiple lines and layers to uncover the truth. There are three great reversals in the film, each of which is overthrow for the film plot, and every overthrow is a disavowal of the audience's cognition for the previous story; therefore it brings the greatly emotional tension, making the audience get complete release and relief in the process of the psychological game of cognition, identification and decision-making at the end.

• Journal of the Korea Society of Computer and Information
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• v.28 no.9
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• pp.55-62
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• 2023

In this paper, we present a method that utilizes geometry-based sound generation techniques to efficiently handle multiple sound sources, wind turbulence, and temperature-dependent interactions. Recently, a method based on reduced raytracing has been proposed to update the sound position and efficiently calculate sound propagation and diffraction without recursive reflection/refraction of many rays, but this approach only considers the propagation characteristics of sound and does not consider the interaction of multiple sound sources, wind currents, and temperature. These limitations make it difficult to create sound scenes in a variety of virtual environments because they only generate static sounds. In this paper, we propose a method for efficiently constructing a sound map in a situation where multiple sounds are placed, and a method for efficiently controlling the movement of an agent through it. In addition, we propose a method for controlling sound propagation by considering wind currents and temperature. The method proposed in this paper can be utilized in various fields such as metaverse environment design and crowd simulation, as well as games that can improve content immersion based on sound.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.261-261
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• 2016

플래시 메모리 (flash memory)는 DRAM(dynamic racdom access memory)이나 SRAM(static random access memory)에 비해 소자의 구조가 매우 단순하기 때문에 집적도가 높아서 기기의 소형화가 가능하다는 점과 제조비용이 낮다는 장점을 가지고 있다. 또한, 전원을 차단하면 정보가 사라지는 DRAM이나 SRAM과 달리 전원이 꺼지더라도 저장된 정보가 지워지지 않는다는 특징을 가지고 있어서 ROM(read only memory)과 정보의 입출력이 자유로운 RAM의 장점을 동시에 가지기 때문에 활용도가 크다. 또한, 속도가 빠르고 소비전력이 작아서 USB 드라이브, 디지털 TV, 디지털 캠코더, 디지털 카메라, 휴대전화, 개인용 휴대단말기, 게임기 및 MP3 플레이어 등에 널리 사용되고 있다. 특히, 낸드(NAND)형의 플래시 메모리는 고집적이 가능하며 하드디스크를 대체할 수 있어 고집적 음성이나 화상 등의 저장용으로 많이 쓰이며 일정량의 정보를 저장해두고 작업해야 하는 휴대형 기기에도 적합하며 가격도 노어(NOR)형에 비해 저렴하다는 장점을 가진다. 최근에는 smart watch, wearable device 등과 같은 차세대 디스플레이 소자에 대한 관심이 증가함에 따라 투명하고 유연한 메모리 소자에 대한 연구가 다양하게 진행되고 있으며 유리나 플라스틱과 같은 기판 위에서 투명한 플래시 메모리를 형성하는 기술에 대한 관심이 높아지고 있다. 전하트랩형 (charge trap type) 플래시 메모리는 플로팅 게이트형 플래시 메모리와는 다르게 정보를 절연막 층에 저장하므로 인접 셀간의 간섭이나 소자의 크기를 줄일 수 있기 때문에 투명하고 유연한 메모리 소자에 적용이 가능한 차세대 플래시 메모리로 기대되고 있다. 전하트랩형 플래시메모리는 정보를 저장하기 위하여 tunneling layer, trap layer, blocking layer의 3층으로 이루어진 게이트 절연막을 가진다. 전하트랩 플래시 메모리는 게이트 전압에 따라서 채널의 전자가 tunnel layer를 통해 trap layer에 주입되어 정보를 기억하게 되는데, trap layer에 주입된 전자가 다시 채널로 빠져나가는 charge loss 현상이 큰 문제점으로 지적된다. 따라서 tunnel layer의 막질향상을 위한 다양한 열처리 방법들이 제시되고 있으며, 기존의 CTA (conventional thermal annealing) 방식은 상대적으로 높은 온도와 긴 열처리 시간을 가지고, RTA (rapid thermal annealing) 방식은 매우 높은 열처리 온도를 필요로 하기 때문에 플라스틱, 유리와 같은 다양한 기판에 적용이 어렵다. 따라서 본 연구에서는 기존의 열처리 방식보다 에너지 전달 효율이 높고, 저온공정 및 열처리 시간을 단축시킬 수 있는 마이크로웨이브 열처리(microwave irradiation, MWI)를 도입하였다. Tunneling layer, trap layer, blocking layer를 가지는 MOS capacitor 구조의 전하트랩형 플래시 메모리를 제작하여 CTA, RTA, MWI 처리를 실시한 다음, 전기적 특성을 평가하였다. 그 결과, 마이크로웨이브 열처리를 실시한 메모리 소자는 CTA 처리한 소자와 거의 동등한 정도의 우수한 전기적인 특성을 나타내는 것을 확인하였다. 따라서, MWI를 이용하면 tunnel layer의 막질을 향상시킬 뿐만 아니라, thermal budget을 크게 줄일 수 있어 차세대 투명하고 유연한 메모리 소자 제작에 큰 기여를 할 것으로 예상한다.