• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.30 no.7
• /
• pp.24-28
• /
• 2001

터널 환기 설비는 터널에서 발생하는 오염물질을 희석 배출하여 터널에서의 안전운행 및 쾌적한 환경을 유지함을 목적으로 한다. 이를 위해서 각종 환기설비가 필요하게 되며, 이에 대한 설계 검토가 요구되고 있다. 본 원고에서는 제트팬 방식의 터널에서 풍속 측정을 중심으로 하여 측정결과 및 분석결과를 소개하고자 한다.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.6
• /
• pp.90-99
• /
• 2002

The main purpose of this study lies on the development of micro dilution tunnel based on the Sierra Dilution chamber model. As a primary examination, characteristics of flow and temperature distributions during the steady dilution process in dilution chamber are observed with numerical analysis. The penetration of dilution air through porous tube as well as wall temperature and temperature gradient inside porous tube are examined. The thermophoretic velocity in terms of temperature behavior inside porous tube are defined and examined. Based on the ratio of penetration and thermophoretic velocities, all part of porous tube are shown to be safe from the particulate depositions. However, The inlet portion of porous tube in addition to the portion of impinging of dilution air are marginally safe from the particulate depositions. Generally the safer design against particulate deposition is required in provision f3r steady dilution process and for transient process as well.

• Magazine of korean Tunnelling and Underground Space Association
• /
• v.5 no.4
• /
• pp.62-84
• /
• 2003

• Vacuum Magazine
• /
• v.3 no.4
• /
• pp.14-18
• /
• 2016

In this article, we will summarize recent advances in ultrahigh vacuum (UHV) low-temperature scanning tunneling microscopy (STM) during the last decade. Leading STM groups have finished or are constructing UHV milli-Kelvin high magnetic field STM capable of a few tens of milli-Kelvin and ~ 10 tesla. Applications with UHV sub-Kelvin high magnetic STM have been increased since mid-2000's. Active research using UHV low temperature tuning fork atomic force microscopes and UHV photon low-temperature scanning tunneling microscopes will be introduced. Considering these advances of UHV low-temperature STM we will discuss next trend in STM in the near future.

• Journal of the korean Society of Automotive Engineers
• /
• v.9 no.1
• /
• pp.40-48
• /
• 1987

A Mini-Dilution Tunnel is described as a scaled down comparision of a Standard Tunnel. The paper presents the result of experimental investigations on measuring the particulate emission of a diesel engine in a Mini and a Standard Dilution Tunnel. The result offers a contribution to understanding about the influence of several parameters including dilution ratios, mixture temperatures, mixture conditions, filter temperatures, and flow conditions. In the experiment either increasing the filter temperature and mixture temperature at a fixed dilution ratio or increasing the dilution ratio at a fixed filter temperature and mixture temperature resulted in a decrease in the total particulate mass. These changes in total particulate mass were attributed to the changes in the soluble organic fraction of the particulate sample. Also, mass differences between the Mini and the Standard Dilution Tunnel for the same engine conditions were within approximately 15% of each other.

• 한국터널공학회:학술대회논문집
• /
• 2005.04a
• /
• pp.189-201
• /
• 2005

Brittle failure has been detected in over-stressed rock mass during the construction of oil storage cavern. The main characteristics of stress induced brittle failure of the site are introduced. Various evaluation and measures are sought to stabilize the over-stressed rock mass. The major results from numerical analysis of the cavern are presented, and from current microseismic monitoring to detect hazard from brittle failure are presented.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.1
• /
• pp.114-120
• /
• 2008

Recently, the nano-PM's number concentration emitted by diesel internal combustion engine has focused on attention because this particulate matters are suspected being hazardous of human health. In this study, The nano-PM mass and size of diesel passenger vehicles were measured on chassis dynamometer test bench. The particulate matters(PM) emissions of these vehicles were investigated by number concentration too. A condensation particle counter(CPC) system was applied to measure the particle number and size concentration of diesel exhaust particles at the end of dilution tunnel along the NEDC(ECE15+EUDC) and CVS-75 vehicle test mode. As the research result, the characteristic of vehicle test mode on the diesel nano-particle number and size distribution was investigated in this study.

• Tunnel and Underground Space
• /
• v.19 no.3
• /
• pp.167-173
• /
• 2009

Underground storage cavern is known as the most complicated underground project because of the complexity of construction schedule, tunnel size, and geological problems. In order to optimize the construction schedule of underground storage cavern, two up-to-date technologies were applied. The first technology was 3 dimensional visualization of complicated underground structures, and the second was 4 dimensional simulation considering construction resources, geological conditions and construction schedule. This application case shows that we can achieve optimized construction schedule in the ways to optimize the number of work teams, fleets, the sequence of tunnel excavation, the commencement time of excavation and the hauling route of materials and excavated rocks. 3 dimensional modeling can help designer being able to understand the status of complicated underground structures and to investigate the geological data in the exact 3 dimensional space. Moreover, using 4 dimensional simulation, designer is able to determine the bottle neck point which appear during hauling of excavated rocks and to investigate the daily fluctuation in cost.

• Tunnel and Underground Space
• /
• v.8 no.1
• /
• pp.17-25
• /
• 1998

This paper investigates coupled thermal, mechanical and hydraulic phenomena in deep rock mass especially for underground heat storage system. Firstly, concepts of underground heat storage were presented and coupling phenomena in this area were illustrated. In order to understand the basic mechanism of thermal, hydraulic and deformation behavior in rock cavern disturbed by thermal gradient about 10$0^{\circ}C$, various numerical experiments were conducted using several codes. The study involves the behavior of fractured rock mass including rock joint. In spite of the limitation of codes modelling fully coupled effects, these codes could be applied in analysis of underground heat storage. The heat loss in rock mass, which is a major factor in heat storage, is insignificant in all results.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.949-959
• /
• 2006

Despite of the popularity of using empirical methods for support design, empirical rules suffer from the inherent problem of providing no indication of the safety degree of the design. For the support design of large span tunnel, it was considered that the empirical design guidelines should be augmented by more explicit design methods. This paper presents an overview of the analytical support design methodology that is used to refine initial empirical recommendations. The initial support design supplemented by analytical methods is validated by probabilistic and deterministic approach applied to stress-induced and structurally controlled gravity-driven instability problem each. As a result, the extent of the potential failure zone is sorted out and numerical parametric studies were performed to gain insight into the overall behavior of tunnel in the potential failure zone. Concequently, it was decided that additional conservation techniques have to be planed as a reserved support pattern.