• Current Optics and Photonics
• /
• v.2 no.3
• /
• pp.280-285
• /
• 2018

A new method to design a see-through off-axis head-mounted-display (OA-HMD) optical system with an ellipsoidal surface is proposed, in which a tilted ellipsoidal surface is used as the combiner, which yields the benefits of easier fabrication and testing compared to a freeform surface. Moreover, we realize a coaxial structure in the relay lens group, which is simple and has looser tolerance requirements, thus making assembly easier. The OA-HMD optical system we realize has a simple structure and consists of a combiner and 7 pieces of coaxial relay lenses. It has a $48^{\circ}{\times}36^{\circ}$ field of view (FOV) and 12-mm exit pupil diameter.

• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.2
• /
• pp.88.1-88.1
• /
• 2017

We report a novel design of the "linear astigmatism-free" three mirror system (LAF-TMS). In general, the linear astigmatism is one of the most dominant aberration degrading image qualities in common off-axis systems. The proposed LAF-TMS is based on a confocal off-axis three mirror system, where higher order aberrations are minimized via our numerical optimization. The system comprises three pieces of aluminum-alloy freeform mirrors that are feasible to be fabricated with current single-point diamond turning (SPDT) machining technology. The surface figures, dimensions, and positions of mirrors are carefully optimized for a LAF performance. For higher precision-positioning mechanism, we also included alignment parts: shims (for tilting) and L-brackets (for decentering). Any possible mechanical deformation due to assembly process as well as 1-G gravity, and its influence on optical performances of the system are investigated via the finite element (FE) analysis. The LAF-TMS has low f-number and a wide field of view, which is promising for sky monitoring programs such as supernova surveys.

• Journal of the Korean Institute of Rural Architecture
• /
• v.21 no.3
• /
• pp.41-48
• /
• 2019

The purpose of this study is to understand whether the architecture of the mountain village conforms to the geography and local landscape, and become a unique scenic element. Also, the study is to grasp the status of the village landscape design elements. The methods and contents of the study were surveyed by field research with references in Biederbach community, an isolated mountain village in Southwestern Germany. The time frame for the survey research is July 2015. The contents of the study include the analysis of the village's landscape structure, architecture, and landscape design patterns. The following conclusions were reached through the above research process. First, the village landscape structure seen in the mid-distance view is the hilly scene of the alpine region, which houses the sloping terrain of Black Forest and surrounds the residential area with the grassland covered by the Black Forest. Second, the main elements of the town's landscape building are historical culture, traditional architecture, topology and nature, and artificial environmental design. Third, the landscape design utilizing the village's resources creates a sustainable community's residential environment.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.11
• /
• pp.1029-1035
• /
• 2011

Pressure pulsation of exciting sources that generally occurs on the piping system connected to the discharge of BFP(boiler feed water pump) in power plants causes wave reflection, wave interference, resonance, standing wave and so on. But if the operating speed of the pump is changed, the state of the noise and vibration can be done because characteristics of the exciting source are changed. This paper is to investigate the cause of the noise and vibration occurring on the piping system when the operating speed of BFP is down in accordance with lowering of the power generation. It is approached to two points of view ; Firstly, it is examined whether the pulsation source impacts on the shell mode vibration that vibrates radially across the cross-section of the pipe. But it doesn't affect the shell mode as much as the resonance occurs. Secondly, to find the relation between the pulsation source and the acoustic mode of the piping system, analysis for the piping system by indirect BEM(boundary element method) is carried out. Therefore it is investigated that the mechanism of the noise and vibration relates with acoustic mode of the piping system.

• Journal of the Korean housing association
• /
• v.23 no.6
• /
• pp.21-30
• /
• 2012

In foreign countries, the use of containers has already been stabilized with their advantages utilized in various forms. Containers are also utilized in Korea as various forms of architecture, but domestic container buildings have poor public consciousness so as to be limitedly utilized as temporary structures based on economic efficiency. Besides, there is the lack of research and development on them. Particularly, despite the advantages of containers as housing facilities, the use of containers as short- or middle-term temporary housing is limited and does not spread. Also, compared to general housing, containers have lower quality of physical environment and even frequently bring about negligent accidents such as fire and electric shock. Thus, this study intends to identify the actual condition of using container houses, the problems in using them, and the direction of improving their residential environment. For this purpose, it analyzes the present condition and characteristics of domestic container housing, and derives conclusions from the focus group interview with 23 residents who have lived in Seoul and Gyeonggi-do for over a year about such survey items as daylighting, ventilation, privacy condition, water service and sewerage, insulation, soundproofing, view, and room scale.

• Journal of Soil and Groundwater Environment
• /
• v.6 no.2
• /
• pp.31-38
• /
• 2001

An illegal landfill In Korea was evaluated in a view of environmental quality to figure out reusing the area. The sampling spots were selected at a point in the landfill and three points in it's around area(two points in a paddy soils and one in a farm field). The eleven pollutants regulated in the Korean Soil Environmental Preservation Act (KSEPA) were analysed from the soil sample with the method of the KSEPA. As the results of the analysis the level of concentration with most samples indicated the requirement of the KSEPA. The concentration of soil samples met the standard: however, some pollutants in the ground water and leachate showed higher concentration than that of the requirement. Therefore, we must consider the treatments of the pollutants in the ground water and leachate when designing this landfill area for reusing.

• Journal of the Korean Society of Industry Convergence
• /
• v.4 no.4
• /
• pp.441-450
• /
• 2001

This dissertation deal with over-all wireless communication technology. And introduce wireless communication technology analytically that it use for Home-LAN communication technology (HomeRF, Bluetooth, IEEE 802.11, HIPERLAN, etc). Home-LAN communications issue by the terminal field of the latest high-speed network construction. This technologies possesses characteristics and significances as the representative technology using in Home-LAN communication technology. Also, the method of application is conditional on individually. Wireless LAN put Home-LAN communications to practical use. Bluetooth have practical use for an individual mobile communications with internet. HomeRF have a vision that the construction of wireless system in house purely. Therefore, this dissertation investigates merits and demerits between those technologies. And then leads the most compatible technology for application of Home-LAN. Finally, this thesis have a view of the development course hereafter.

• Journal of Korean Society of Rural Planning
• /
• v.22 no.1
• /
• pp.93-100
• /
• 2016

Land price can be affected by convenience or psychological repulsion like PIMFY (Please In My Front Yard) or NIMBY (Not In My Back Yard) for various facilities. Services related to public establishment, welfare, medical attention, and amenities in rural areas are comparatively poorer than those in urban areas. The purpose of this study is to estimate the implications of the accessibility to community facilities in rural areas for land prices using a hedonic price model. The accessibility to facilities is estimated by real road distances and the land prices are applied for four types of land usages: field, rice paddy, building lots, and village halls. Community facilities are classified from public and community services view: education, safety, culture, transport, environment, health care, and finance. The results show that the accessibility to health care and transport can positively affect land prices and the accessibility to environment (waste facilities and junkyard) and unpleasant services (funeral hall and charnel house) can negatively affect land prices. Especially, the accessibility to hospital is the most positive influential factor for all types of land usages.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.05a
• /
• pp.51-54
• /
• 2007

The purpose of this paper is the development of measurement algorithm for green-sheet based on the digital image processing technique. The Low Temperature Cofired Ceramic (LTCC) technology can be defined as a way to produce multilayer circuits with the help of single tapes, which are used to apply conductive, dielectric and / or resistive pastes on. These single green-sheets have to be laminated together and fired in one step all. Main functionality of the green-sheet film measurement algorithm is to measure the position and size of the punching hole in each single layer. The line scan camera coupled with motorized X-Y stage is used for developing the algorithm. In order to measure the entire film area using several scanning steps, the overlapping method is used. In the process of development of the algorithm based on the image processing and analysis, strong background technology and know-how have been accumulated.

• Journal of Korean Society on Water Environment
• /
• v.26 no.2
• /
• pp.252-260
• /
• 2010

The point rainfall measurements need to be converted to the areal rainfall by means of mean areal precipitation (MAP) estimation methods. And it is not appropriate to evaluate the areal rainfall with constant drift because of the geomorphological influences to rainfall field. Non-stationarity should be applied to the estimation of the areal rainfall, therefore, to consider these effects. Kriging methods with special functional would be a suitable tool in this case. Generalized covariance Kriging method is the most developed one among different Kriging methods. From this point of view this study performs the analysis of its applicability to distributed runoff model. For these purpose, distributed rainfall was created by Thiessen and Kriging method. And distributed rainfall of each method was applied into HyGIS-GRM. The result of applying, Runoff was different in the rainfall data form. Therefore, To apply Kriging method with physical meaning is that it is the useful method as distributed rainfall-runoff model.