• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
• /
• pp.837-840
• /
• 1988

We study both theoretically and experimentally the motion of fluid driven by electro-thermally ablated gas pressure in a cavity with a single exhauster. A possibility of jet propulsion engine for steamers is also discussed as an application of the fluid motion.

• 한국HCI학회:학술대회논문집
• /
• 한국HCI학회 2006년도 학술대회 1부
• /
• pp.954-959
• /
• 2006

Virtual Reality simulation enables immersive 3D experience of a Virtual Environment. A simulation-based VE can be used to map real world phenomena into virtual experience. This research studies on the use of Newton's physics law to demonstrate the effects of forces upon object's falling movement, and their effects towards other fallible objects. A reconfigurable simulation enables users to reconfigure the parameters of the objects involved in the simulation, so that they can see different effects from the different configurations, such as force magnitude and distance between objects. This concept is suitable for a classroom learning of physics law. Preliminary implementation is done on a PC with a joystick for 4DOF movement. The graphics is implemented by SGI OpenGL Performer. A middleware called NAVERLib that consists of Performer's modules for easy XML-based configuration is used for management of visualization, network and devices connection, and where the engine of this domino simulation is attached.

• 한국게임학회 논문지
• /
• 제9권5호
• /
• pp.95-104
• /
• 2009

최근 게임이나 시뮬레이터 개발에 있어서 물리기반 시뮬레이션을 통해 사실성을 높인 고품질의 3D 콘텐츠를 개발하고자하는 사례가 많아지고 있다. 본 논문에서는 오픈소스 물리엔진인 ODE를 이용하여 중량물을 취급하는 천장크레인 시뮬레이터의 개발하는 방법을 제안하였다. 그리고 상용 천장크레인 시뮬레이터와의 물리적 특성 비교분석을 통해 오픈소스 물리엔진으로도 사실성 높은 훈련용 시뮬레이터 개발이 충분히 가능하다는 것을 확인하였다. 본 논문에서 제안한 천장크레인 시뮬레이터는 학교 등의 공공기관에서 교육용이나 훈련용으로 충분히 활용할 수 있을 것으로 예상된다.

• International Journal of Internet, Broadcasting and Communication
• /
• 제14권1호
• /
• pp.105-115
• /
• 2022

The platform for displaying cars has been changing with the times. From the popularity of paper media to the rise of computer graphics, the improvement of technology has brought more space and possibilities to the automotive industry. Yiming Zhong proposed the workflow of car configurator through Unreal Engine 4 to implement the basic functions of configuration in 2021, according to Yiming Zhong's final presentation, there is still room to improve the realism of graphics and functionality of the car configurator. Therefore, in this paper we propose to upgrade the car shaders and lighting environments according to the real-world physics and add multi-scenes switching function to car configurator. However the multi-scenes switching function also brings a large amount of data, which leads to the problem of display lag. At the end of the paper, we use the level of details(LOD) process to reduce the amount of data for real-time computing in Unreal Engine 4 and the increase of frames per second(FPS) values verifies the feasibility of our optimization solution.

• 한국광학회지
• /
• 제17권3호
• /
• pp.240-247
• /
• 2006

본논문에서는 LCOS형 마이크로 디스플레이를 이용하여 60인치 이상의 대화면에서도 고해상도 및 슬림형이 가능한 프로젝션 TV용 광학계를 설계하였다. 조명광학계, 투사광학계, 색분리 합성계 그리고 마이크로 디스플레이 사이의 상호관계를 정량화하여 최적의 광학엔진을 구현하기 위한 초기데이터를 설정하고, 이로부터 최적화 과정을 통하여 각각의 광학계를 설계하였다. 고휘도를 구현하기 위한 3-panel 방식을 도입하고, 4개의 프리즘을 대칭적으로 배열하여 RGB의 광경로가 동일하도록 색분리 합성계를 구성하여 조명광학계를 컴팩트하게 설정하였다. 또한 투사광학계의 렌즈 군 사이에 거울을 삽입하여 접은 형태로 구성하여 고해상도 및 슬림형이 가능한 광학엔진을 설계하였다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집B
• /
• pp.491-496
• /
• 2000

The physics of the flow field surrounding an engine nacelle afterbody is very complex. A high pressure jet from the nozzle interacts with the external flow and causes upstream influence on the afterbody surface field. At certain conditions, the nozzle boundary layer can separate, either by shock wave interaction or by adverse pressure gradient effect, resulting in a severe drag penalty. Furthermore, a finite afterbody base implies a recirculating flow region. A flow modeling method has been developed to analyze the flow in the annular base(rear-facing surface) of a circular engine nacelle flying at subsonic speed but with a supersonic exhause jet. Real values of exhaust gas properties and temperature are included.

• Journal of Welding and Joining
• /
• 제31권3호
• /
• pp.22-30
• /
• 2013

Due to ELV banning, automotive electronics cannot use four kinds of heavy metal element (Pb, Hg, Cd, $Cr^{6+}$) from 2016. Therefore, this study was focused on degradation characteristics of Sn-3.0Ag-0.5Cu Lead-free solder joint with OSP and ENIG finsh under various reliability assessment method, as like to thermal shock test and high temeprature/high humidity test with test duration for cabin electronics. Also, we compared bonding strength degradation to other advanced research results of electronic control unit for engine room because of difference service temperature with mount location in automotive. Whisker growth phenomenon and mitigation method which were essentially consideration items for Pb-free car electronics were examined. Conformal coating is a strong candidate for mitigating whisker growth in automotive electronics. Necessary condition to adapt Pb-free in car electronics was shown.

• 한국농공학회논문집
• /
• 제54권3호
• /
• pp.81-89
• /
• 2012

This paper presents a set of controlled simulated statical and engineering mechanical experiments accessible via the virtual world environment (VWE) and virtual physics lab S/W. Online courses of the university offering courses and/or programs online are growing and the number of students want education in ways which fit their personal places, e-learning is becoming more important and ubiquitous each year. In this study, first of all, question is rather 'How do we execute the learning effectiveness of e-learning courses?' than 'Why does they need e-learnig or VW-learning?'. In particular, is it possible to effectively teach mechanical engineering courses online? The answer was 'No'. So, there is little research on many of these questions. And another important question is 'Is e-learning cost effective?'. For the answer, This research provided that an instructional design model is used to 'How to think and apply the Newtonian forces' in the virtual physics lab S/W. Collected data from student are administered in the spring semester when students studied 'Introduction to Bio-resources and Systems Engineering'. Results show that a cadre of students can take highly interactively physical properties of mechanical engineering in the virtual laboratory environment. Those show that VWE is greater than that of a similar real world presentation or experimental lab, since most of students are delighted to modify and retry modeling works in the VWE.

• 천문학회보
• /
• 제41권2호
• /
• pp.64.2-64.2
• /
• 2016

Optical variability is one way to probe the nature of the central engine of AGN at smaller linear scales and previous studies have shown that optical variability is more prevalent at longer timescales and at shorter wavelengths. Especially, intra-night variability can be explained through the damped random walk model but small samples and inhomogeneous data have made constraining this model hard. To understand the properties and physical mechanism of optical variability, we are performing the KMTNet Active Nuclei Variability Survey (KANVaS). Test data of KMTNet in the COSMOS field was obtained over 2 separate nights during 2015, in B, V, R, and I bands. Each night was composed of 5 and 9 epochs with ~30 min cadence. To find AGN in the COSMOS field, we applied multi-wavelength selection methods. Different selection methods means we are looking different region in unification model of AGN, and 100~120, 400~500, 50~100 number of AGN are detected in X-ray, mid-infrared, and radio selection of AGN, respectively. We performed image convolution to reflect seeing fluctuation, then differential photometry between the selected AGN and nearby stars to achieve photometric uncertainty ~0.01mag. We employed one of the standard time-series analysis tools to identify variable AGN, chi-square test. Preliminarily results indicate that intra-night variability is found for X-ray selected, Type1 AGN are 23.6%, 26.4%, 21.3% and 20.7% in the B, V, R, and I band, respectively. The majority of the identified variable AGN are classified as Type 1 AGN, with only a handful of Type 2 AGN showing evidence for variability. The work done so far confirms that there are type and wavelength dependence of intra-night optical variability of AGN.

• 비파괴검사학회지
• /
• 제30권5호
• /
• pp.423-428
• /
• 2010

본 논문에서는 ESPI 방법을 이용하여 자동차 엔진의 핵심 부품인 TPS의 열변형력에 따른 변외변형을 측정하여 열변형 특성을 분석하였다. 높은 해상도의 CCD와 줌렌즈를 사용하여 부품의 검사영역을 가로 세로 각각 5cm로 최소화하였다. 주행거리가 다른 TPS 부품들을 4-step 위상이동법과 위상 연속화를 통해 변형량이 연속적으로 변하는 위상도를 얻었고, 3차원으로 변형의 모양과 크기를 나타내었다. 약 $70^{\circ}C$의 온도를 유지하면서 TPS 부품에 열을 가한 경우 주행거리가 길어질수록 TPS 변형은 크게 측정되었고, 위로 볼록한 형태로 변형되었다. 그리고 내부결함이 있는 부품에서는 위상도에 불연속적인 무늬가 나타났고, 아래로 오목한 모양을 갖는 변형으로 나타났다.