• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.99-104
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• 2007

Tracer gas technique is widely used to measure the ventilation rates and/or ventilation effectiveness of building spaces. However, the conventional method using a single tracer gas can measure only outdoor air change rates in a single zone. This paper deals with the multi-gas tracer technique to measure air exchange rates between rooms. Interzonal air movements are important to characterize overall ventilation performance of complicated multi-zone buildings. Experiments are conducted in a simple two-room model with known airflow rates using tracer gases of SF6 and R134a. The concentration decays of two tracer gases are measured after simultaneous injections in each room. The governing equations are derived from the continuity and the mass balance of each room. The data reduction procedure are developed to obtain the inter-room airflow rates using the governing matrix inversion, and various data manipulation methods are tested, such as data shift, interpolation, smoothing, and etc, to improve the estimate and interpretation of the results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.4
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• pp.347-354
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• 2016

Because typical gas turbine systems have frequent startup and shutdown operations, it is likely to cause cracks at the gas turbine casing and gas leakages at casing flanges due to thermal fatigue and embrittlement. Therefore, the evaluation of structural integrity and gas leakage at the gas turbine casings must be performed. In this paper, we have evaluated the structural integrity of the turbine casing and bolts under a normal operation in accordance with ASME B&PVC and evaluated the leakage at casing flanges by examination of contact pressure calculated using the finite element analysis. Finally, we propose a design flow including finite element modeling, the interpretation and evaluation methods for gas turbine casings. This may be utilized in the design and development of gas turbine casings.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.634-637
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• 2005

Multichannel seismic data acquired in Ulleung Basin of East Sea for gas hydrate exploration. The seismic sections of this area show strong BSR(bottom simulating reflections) associated with methane hydrate occurrence in deep marine sediments. Very limited information is available from deep sea drilling as the risk of heating and destabilizing the initial hydrate conditions during the processing of drilling is considerably high. Not so many advanced status of gas hydrate exploration in Korea, the most of information of gas hydrate characteristics and properties are inferred from seismic reflection data. In this study, The AVO analysis using the long offset seismic data acquired in Ulleung Basin used to explain the characteristics and structure of gas hydrate. It is used primarily P-wave velocity accessible from seismic data. To make a good quality of AVO analysis input data, seismic preprocessing including 'true gain correction', 'source signature deconvolution', twice velocity analysis and some kinds of multiple rejection and enhancing the signal to noise ratio processes is carried out very carefully. The results of AVO analysis, the eight kinds of AVO attributes are estimated basically and some others of AVO attributes are evaluated for interpretation of AVO analysis additionally. The impedance variation at the boundary of gas hydrate and free gas is estimated for investing the BSR characteristics and properties. The complex analysis is performed also to verifying the amplitude variation and phase shift occurrence at BSR. Type III AVO anomaly appearance at saturated free gas area is detected on BSR. It can be an important evidence of gas hydrate deposition upper the BSR.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.3
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• pp.75-80
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• 2019

The article is devoted to the interpretation of ammonia, one of the fine dust precursors, absorption behavior in water turbulent flow. The water flow was considered as a turbulent flow with Reynolds number more than $10^4$, because ammonia gas penetration depth was deeper at turbulent flow compared to laminar flow. For the interpretation, the dimensionless mass transfer governing-equation and the constant physical-properties at room temperature were used. The diffusivity of ammonia in water and the kinematic viscosity of water were $2{\times}10^{-9}m^2/s$ and $1{\times}10^{-6}m^2/s$, respectively. The concentration distribution of ammonia in water was estimated with respect to the position from the point where the water started to be exposed to ammonia. The quantitative distribution as a function of the mixing length was also acquired. The quantitative interpretation may provide the insight how much the turbulent flow was more efficient to remove ammonia rather than the laminar flow.

• 전기의세계
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• v.27 no.1
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• pp.45-48
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• 1978

A pressure dependence in the value of Es/p at a constant pd is observed in sulphur hexafluoride at pressures in excess of about one bar. This is explained in terms of the non-idealgas behavior of SF$_{6}$ which has a significant influence on the interpretation of electrical breakdown of this gas. The criterions for breakdown at low pressures and in the presence of rough electrodes are modified to allow this phenomeneon.n.

• Proceedings of the SAREK Conference
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• 2004.06a
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• pp.48-48
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• 2004

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.433-438
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• 2004

Clusters of galaxies generally form by the gravitational merger of smaller clusters and groups. Major cluster mergers are the most energetic events in the Universe since the Big Bang. The basic properties of cluster mergers and their effects are discussed. Mergers drive shocks into the intracluster gas, and these shocks heat the intracluster gas. As a result of the impulsive heating and compression associated with mergers, there is a large transient increase in the X-ray luminosities and temperatures of merging clusters. These merger boost can affect X-ray surveys of clusters and their cosmological interpretation. Similar boosts occur in the strong lensing cross-sections and Sunyaev-Zeldovich effect in merging clusters. Merger shock and turbulence associated with mergers should also (re)accelerate nonthermal relativistic particles. As a result of particle acceleration in shocks and turbulent acceleration following mergers, clusters of galaxies should contain very large populations of relativistic electrons and ions. Observations and models for the radio, extreme ultraviolet, hard X-ray, and gamma-ray emission from nonthermal particles accelerated in these shocks will also be described. Gamma-ray observations with GLAST seem particularly promising.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.67.2-67.2
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• 2013

Part of mid-J CO emission detected by the Herschel/PACS observations of embedded young stellar objects (YSOs) has been attributed to the UV-heated outflow walls. We have applied our newly developed self-consistent models of Photon Dominated Region (PDR) and Non-LTE line Radiative transfer In general Grid (RIG) to the Herschel FIR CO observations. If the black body radiation of T = 15,000 K is used, the observed mid-J CO line fluxes can be produced in inner dense regions (n ${\geq}$ 106 cm-3) with -4.5 ${\leq}$ log Gdust/n ${\leq}$ -2.5, where gas temperatures are larger than 300 K and CO abundances are ${\geq}$ 10-5, along the UV-heated outflow walls. The contribution of the UV heated outflow cavity wall in Class I seems to be larger than that in Class 0.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.567-571
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• 2004

Recently, GIS(Gas Insulated Switchgear) has been recognizing of importance on development of diagnosis technique which is happened problem on confidence for a long time use. Therefore, the measurement and analysis of PD with prior phenomenon of insulation breakdown is used many method of diagnosis for GIS. In this paper, we simulate trouble condition in DS and analysis trouble signal to use electrical and mechanical methods, interpretation of detected signal has analysed with to use ø-q-n pattern and neural network. For this analysis, we have used the induction and AE(acoustic emission) sensors. For the simulation experiment, we make DS for 170 KV GIS and analyze the classification and characteristics of detected signals with the application of neural network algorithm.

• Journal of Welding and Joining
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• v.35 no.3
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• pp.75-81
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• 2017

Recently in the welding field, the establishment of unmanned and automated systems are rapidly developing. Accurate interpretation of the welding phenomenon is applied a number of monitoring systems. In this paper, butt welding (6t) type I using Plasma-MIG welding was carried out. And we evaluated characteristics of the Al-5083 aluminium alloy in Plasma-MIG hybrid welding. Process variables including the plasma current, MIG voltage, wire feeding rate and the welding speed were used. Butt welding was conducted 1 pass. Argon gas was used as the protective gas that results from the experiment were able to achieve full penetration. In addition to monitoring the welding process occurring during MIG welding current, welding votage and Plasma current, voltage were collected in real time, the photodiode and CCD cameras observing the phenomenon that the welding is in progress were measured using a quantity of light.