• Journal of Energy Engineering
• /
• v.26 no.4
• /
• pp.35-44
• /
• 2017

Disposal of municipal solid waste has become a major problem in many countries around the world. As landfill space for the disposal of ash from Municipal Solid Waste Incineration (MSWI) becomes scarce, numerous reports and researches address the various environmental issues about the municipal solid waste incineration waste management and other particulate matters with the range of 10 ~ 2.5. Although in many developing and industrialization countries landfill with the disposal of municipal solid waste, open incineration has become a common practice. Large municipal waste incinerators are major industrial facilities and have the potential to be significant sources of environmental pollution. Despite the significant volume reduction from incineration, waste recycling is important to ensuring the future welfare of mankind. The main goal of the present work is the physical and chemical characterization of the local incineration bottom ash towards its eventual re-utilization. In this paper, we reported the studies on physical and chemical characteristics of municipal solid waste incineration (MSWI) fly ash and bottom ash containing particulate matter whose particulate sizes are lower than $PM_{10}$, $PM_{2.5}$ and heavy metal were investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11b
• /
• pp.1-6
• /
• 2004

In this paper author describe the undoped and $Co^{2+}$ (0.5mole%)doped $Cd_4GeS_6$ single crystals were grown by the chemical transporting reaction(CTR) method using high purity(6N) Cd, $GeS_2$, S elements. It was found from the analysis of X-ray diffraction that the undoped and $Co^{2+}$(0.5mole%) doped $Cd_{4}GeS_{6}$ compounds have a monoclinic structure in space grop Cc. The optical energy band gap was direct band gap and temperature dependence of optical energy gap was fitted well to Varshni equation. Impurity optical absorption peaks due to the doped cobalt in the $Cd_4GeS_6:Co^{2+}$ single crystal were observed at 3593cm-1, 5048cm-1, 5901cm-1, 7322cm-1, 12834cm-1, 13250cm-1, 14250cm-1，and 14975cm-1 at 11.3K.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.13 no.2 s.29
• /
• pp.169-172
• /
• 2007

This paper presents circuit models and control algorithms of distributed generation system(DGS) which consists of Z-type converter and PWM inverter. Z-type converter which employs both the L and C passive components and shoot-through zero vectors instead qf the conventional DC/DC converter in order to step up DC-link voltage. Discrete time sliding mode control with the asymptotic observer is used for current control. This system am be used for power conversion of DC renewable energy.

• Nuclear Engineering and Technology
• /
• v.38 no.4
• /
• pp.343-352
• /
• 2006

Convenient analytical tools for evaluation of the aperiodic and the fluctuating instabilities of the passive residual heat removal system (PRHRS) of an integral reactor are developed and results are discussed from the viewpoint of the system design. First, a static model for the aperiodic instability using the system hydraulic loss relation and the downcomer feedwater heating equations is developed. The calculated hydraulic relation between the pressure drop and the feedwater flow rate shows that several static states can exist with various numbers of water-mode feedwater module pipes. It is shown that the most probable state can exist by basic physical reasoning, that there is no flow rate through the steam-mode feedwater module pipes. Second, a dynamic model for the fluctuating instability due to steam generation retardation in the steam generator and the dynamic interaction of two compressible volumes, that is, the steam volume of the main steam pipe lines and the gas volume of the compensating tank is formulated and the D-decomposition method is applied after linearization of the governing equations. The results show that the PRHRS becomes stabilized with a smaller volume compensating tank, a larger volume steam space and higher hydraulic resistance of the path $a_{ct}$. Increasing the operating steam pressure has a stabilizing effect. The analytical model and the results obtained from this study will be utilized for PRHRS performance improvement.

• Nuclear Engineering and Technology
• /
• v.46 no.5
• /
• pp.619-632
• /
• 2014

The Best Estimate Plus Uncertainty (BEPU) method has been widely used to evaluate the uncertainty of a best-estimate thermal hydraulic system code against a figure of merit. This uncertainty is typically evaluated based on the physical model's uncertainties determined by expert judgment. This paper introduces the application of data assimilation methodology to determine the uncertainty bands of the physical models, e.g., the mean value and standard deviation of the parameters, based upon the statistical approach rather than expert judgment. Data assimilation suggests a mathematical methodology for the best estimate bias and the uncertainties of the physical models which optimize the system response following the calibration of model parameters and responses. The mathematical approaches include deterministic and probabilistic methods of data assimilation to solve both linear and nonlinear problems with the a posteriori distribution of parameters derived based on Bayes' theorem. The inverse problem was solved analytically to obtain the mean value and standard deviation of the parameters assuming Gaussian distributions for the parameters and responses, and a sampling method was utilized to illustrate the non-Gaussian a posteriori distributions of parameters. SPACE is used to demonstrate the data assimilation method by determining the bias and the uncertainty bands of the physical models employing Bennett's heated tube test data and Becker's post critical heat flux experimental data. Based on the results of the data assimilation process, the major sources of the modeling uncertainties were identified for further model development.

• Journal of the Korean Solar Energy Society
• /
• v.25 no.2
• /
• pp.63-69
• /
• 2005

This study is the survey of a transition procedure of building services systems(heat source, HVAC, water supply) through the survey of existing office buildings, building design documents. The preference & major consideration of system selection is the engineer's opinions. The results of this survey can be used in selection of building services system design. In this survey, "Hot & cold water generator system" and "single duct CAV+FCU system", "Elevated water tank system" are selected. The most important consideration in system selection is the energy saving in heat source system, and comfort in HVAC system, and water pressure in water supply system. They prefer "steam boiler+absorption chiller system" for heat source system, "steam boiler+ice thermal storage system", "hot & cold water generator system", "district heating+absorption chiller system" : "single duct CAV+FCU system" and "single duct VAV+convector system" for HVAC system: and "booster pump system" for water supply system.

• Journal of the Korean Solar Energy Society
• /
• v.32 no.4
• /
• pp.51-58
• /
• 2012

This study aims to analyze characteristics of Cell surface temperature and generated power performance for improving PV(Photovoltaic) system condition according to the cell opening ratio of transparent crystal PV system at Spandrel of curtain-wall. For this purpose, alternatives were classified for eight different cases that opening ratio of transparent crystal PV system varied from 0% to 70%, which was used by simulation tool, EnergyPlus. As results, it turned out that increasing opening ratio of transparent crystal PV system led higher PV surface temperature, back-sheet type was thus the most advantageous for decreasing surface temperature, annual generating efficiency, and annual accumulated generating power. Consequently, blocking off air space from outside insolation can advantageously keep to be better condition for generated power performance.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.3
• /
• pp.373-376
• /
• 2004

A novel Er(III) complex with oxydiacetate and 1,10-phenanthroline was synthesized and its structure and luminescence properties were characterized. The complex of $[Er(ODA){\cdot}(phen){\cdot}4H_2O]^+$ crystallizes in the monoclinic space group $P2_1$/n with a = 12.216(4) ${\AA}$, b = 16.680(2) ${\AA}$, c = 12.627(3) ${\AA}$, ${\beta}=108.30(2)^{\circ}$, V = 2442.7(11) ${\AA}^3$, Z = 4 and ${\rho}=1.841 g/cm^3$. When the complex is excited at the He-Cd 325-nm line, it produces two broad bands spanning the regions 350-650 nm and 1200-1650 nm. The emission band of the complex is characterized by a series of spectral dips in the visible emission profile. The complex exhibits sensitized near- IR emission via two kinds of energy transfers from phen to Er(III): nonradiative and radiative energy transfers.

• Journal of the Korean Chemical Society
• /
• v.39 no.1
• /
• pp.14-22
• /
• 1995

This paper is concerned with the design of optimal surface heating patterns that result in focusing acoustic energy inside a subsurface target volume at a specified target time. The surface of the solid is heated by an incident laser beam which gives rise to shear and compressional waves propagating into the solid. The optimal heating design process aims to achieve the desired energy focusing at the target with minimal laser power densities and minimal system disturbance away from the target. The optimality conditions are secured via the conjugated gradient method and by the finite element method along with using the half-space Green's function matrix. Good quality energy focusing is achived with the optimal designs reflecting the high directivity of the photothermally generated shear wave patterns.

• Journal of the Korean Solar Energy Society
• /
• v.34 no.1
• /
• pp.58-63
• /
• 2014

A vertical closed loop ground source heat pump (GSHP) is used to produce heat from the low-grade energy source such as the outside air and ground source. It is known that a heat pump system type has better efficiency comparing to the electric heating system. This study only demonstrates that the vertical closed loop GSHP system is a feasible choice for space cooling of air conditioning. The coefficient of performance (COP) is the ratio of heat output to work supplied to the system in the form of electricity. For the vertical closed loop GSHP system in a cooling mode, the COP is the most commonly used way for judging the efficiency. For the purpose of this experiment, vertical closed loop GSHP system was installed in the laboratory and the experiment was executed. As a result, an average COP of vertical-closed loop GSHP system was 3.62 when the outside average temperature was $33^{\circ}C$.