• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.4
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• pp.215-221
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• 1991

Laminar film condensation of a saturated vapor in forced flow over a flat plate is analyzed by using integral method. Laminar condensate film is so thin that the inertia and thermal convection terms in liquid flow can be neglected. Approximate solutions for water are presented and well agreed with the similarity solutions over the wide range of physical parameter, Cp1(Ts-Tw)/Pr.hfg. For the strong condensation case, it is found that magnitude of the interfacial shear stress at the liquid-vapor interphase boundary is approximately equal to the momentum transferred by condensation, i.e., ${\tau}_i{\simeq}\dot{m}(U_O-U_i)$.

• Journal of Korea Multimedia Society
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• v.22 no.10
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• pp.1187-1198
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• 2019

In this study, we propose a new $PM_{10}$ forecasting model for Seoul region using DNN(Deep Neural Network) and secondary data. The previous numerical and Julian forecast model have been developed using primary data such as weather and air quality measurements. These models give excellent results for accuracy and false alarms, but POD is not good for the daily life usage. To solve this problem, we develop four secondary factors composed with primary data, which reflect the correlations between primary factors and high $PM_{10}$ concentrations. The proposed 4 models are A(Anomaly), BT(Back trajectory), CB(Contribution), CS(Cosine similarity), and ALL(model using all 4 secondary data). Among them, model ALL shows the best performance in all indicators, especially the PODs are improved.

• The Korean Journal of Mycology
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• v.51 no.2
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• pp.127-133
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• 2023

We report the first discovery of Penicillium mexicanum in Korea. Fungal strains were isolated from air samples collected in Taean-gun, Chungcheongnam-do, Korea. The strain was identified based on its morphological characteristics, as well as molecular phylogenetic analysis of the internal transcribed spacer (ITS), β-tubulin (BenA), and calmodulin (CaM) regions. This strain exhibited a high sequence similarity to the reference sequences of P. mexicanum. These findings enhance our understanding of fungal biodiversity in Korea and underscore the importance of continuous monitoring of fungal species.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1376-1383
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• 2002

Seismic qualification of the Air Cleaning Units for nuclear power plant Ulchin 5&6 has been performed with the guideline of ASME Section III and IEEE 344 code. By using the structural and geometrical similarity analysis, the three models to be analyzed are condensed into a single model and, at the same time, the excitation forces and other operating loads for each model are encompassed with respect to different loading conditions. As the fundamental frequencies of the structure are found to be less than 33Hz, which is the upper frequency limit of the seismic load, response spectrum analysis using ANSYS is performed in order to combine the modal stresses within the frequency limit. In order to confirm the structural and electric stability of the major components, modal analysis theory is adopted to derive the required response spectrum at the component locations. As the all combined stresses obtained from the above procedures are less than allowable stresses and no mechanical or electrical failures are found from the seismic testing, the authors confirm the safety of the nuclear equipments Air Cleaning Units studied in this paper.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.6
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• pp.695-702
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• 1999

A cross-flow fan which constitutes a fan-duct system with a stabilizer and a scroll-casing is widely used in many air-ventilating and air-conditioning devices. The cross-flow fan system has many design parameters which have crucial influence on the performance and the noise characteristics of the devices, which means many difficulties during the design stage of the devices and the general design guide has not sufficiently established yet. This study presents the experimental results of the parameter investigation of some chosen design parameter values, which are the shapes of the stabilizers, the profiles of the scroll casing part, and the diffusion angles of the flow exit. The results are expressed by the varying performance characteristics with the values of the parameters. They are found to have considerable effects on the system performance and should be considered with care in the design stage. Finally some helpful guides for the design and manufacturing of the cross-flow fan system are proposed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.2
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• pp.129-136
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• 2006

Optimal design of an air-to-liquid finned plate heat exchanger is considered theoretically in this study. Based on existing correlations for the pressure loss and the heat transfer in channel flows, the optimal configuration of the plate heat exchanger including the optimal plate pitch and the optimal fin pitch is obtained to maximize the heat transfer within the limit of the pressure drop for a given flow depth of the plate heat exchanger. It is found that the optimal fin pitch is about one ninth of the optimal plate pitch. In the optimal configuration, the flow and thermal condition in the channels is just at the boundary between the laminar developing and laminar fully developed states. It is also found when reducing the flow depth of plate heat exchangers for compactness, the heat transfer performance can be maintained exactly the same if the geometric parameters such as the plate thickness, plate pitch, fin thickness, and fin pitch are reduced proportional to the square root of the flow depth as long as the flow keeps laminar within the heat exchangers.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.404-409
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• 2001

Seismic qualification of the Air Cleaning Units for nuclear power plant Ulchin 5&6 has been performed with the guideline of ASME Section III and IEEE 344 code. By using the structural and geometrical similarity analysis, the three models to be analyzed is condensed into a single model and, at the same time, the excitation forces and other operating loads for each model are encompassed with respect to different loading conditions. As the fundamental frequencies of the structure are found to be less than 33Hz, which is the upper frequency limit of the seismic load, response spectrum analysis using ANSYS is performed in order to combine the modal stresses within the frequency limit. In order to confirm the structural and electric stability of the major components, modal analysis theory is adopted to derive the required response spectrum at the component locations. As the all combined stresses obtained from the above procedures are less than allowable stresses and no mechanical or electrical failures are found from the seismic testing, the authors confirm the safety of the nuclear equipments Air Cleaning Units studied in this paper.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.1
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• pp.49-54
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• 2009

Ventilation requirement of apartment was mandated according to building equipment standards in 2006. When ventilation unit was considering for indoor air quality maintenance, we needed energy saving and efficiency ventilation control methods. This study carried out experiment of ventilation rate 0.7 adequacy. When we lived in apartment, we assumed that sleeping time was long stayed time in unconsciousness. Experiments carried out ventilation rate 0, 0.1, 0.4 and 0.7 in environment chamber from 22 o'clock to 06 o'clock, the concentration of $CO_2$, temperature and humidity rate measured. Analyzing the results, conclusions are as follows. 1) When we sleep in bedroom, ventilation rate 0.4 meet the requirements of domestic legal standards. Conform fan of similarity law, ventilation rate 0.4 reduced power cost about 80% than 0.7. 2) In generally sleeping time 8 hours, peak point control reduced running time of ventilation unit about 43% than normal control.

• Journal of Korean Society of Forest Science
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• v.85 no.1
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• pp.1-14
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• 1996

The object of this study was to examine the effects of air pollution on forest vegetation structure in the vinicity of Sasang industrial complex in Korea. Forest vegetation structure was investigated at 19 sample plots surrounding industrial complex and at one site away from industrial complex as a control. The results obtained were as follows; 1. For analysis of vegetation structure, upperstory of forests was mostly consisted of Pinus thunbergii, and partly of Alnus firma and Robinia pseudoacacia. In midstory, major components were Pinus thunbergii, Robinia pseudoacacia, Rhus trichocarpa, Rhus chinensis and Styrax japonica, In lower story, Pinus thunbergii was a minor component, while Robinia pseudoacacia, Quercus serrata, Rhus trichocarpa. and Rhododendron yedoense var. poukhanense which were known to be resistant to air pollution were found in large number. Especially, importance percentage of Robinia pseudoacacia was high, while that of Rhododendron mucronulatum was low in surrounding industrial complex. 2. For woody plants, number of species, species diversity and similarity index in industrial complex, were not significantly different from those in control plot. 3. For herbs, Oplismenus undulatifolius appeared in large number in most plots. The $SDR_3$ of Miscanthus sinensis, Calamagrostis arundinacea, Paederia scandens, Spodiopogon cotulifer and Carex humilis were high, but that of Aster scaber, Saussurea seoulensis, Solidago virgaaurea var. asiatica and Prunella vulgaris var. lilacina were low in the vicinity of industrial complex. 4. Number of herb species decreased to below 10 species at surrounding industrial complex as compared to 20 species in the control plot. In addition species diversity, and similarity index in the industrial complex were lower than those in control plot. It may be concluded that Pinus thunbergii forests in industrial complex consists of tree species resistant to air pollution, and that composition of woody vegetation in industrial complex was not much different from control plot, while composition of herbs was already quite different between the two plots. Forest vegetation structure, therefore, may change with time due to air pollution in the industrial complex.

• Atmosphere
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• v.24 no.4
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• pp.471-479
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• 2014

A road surface temperature prediction model (UM-Road) using input data of the Unified Model (UM) output and road physical properties is developed and verified with the use of the observed data at road weather information system. The UM outputs of air temperature, relative humidity, wind speed, downward shortwave radiation, net longwave radiation, precipitation and the road properties such as slope angles, albedo, thermal conductivity, heat capacity at maximum 7 depth are used. The net radiation is computed by a surface radiation energy balance, the ground heat flux at surface is estimated by a surface energy balance based on the Monin-Obukhov similarity, the ground heat transfer process is applied to predict the road surface temperature. If the observed road surface temperature exists, the simulated road surface temperature is corrected by mean bias during the last 24 hours. The developed UM-Road is verified using the observed data at road side for the period from 21 to 31 March 2013. It is found that the UM-Road simulates the diurnal trend and peak values of road surface temperature very well and the 50% (90%) of temperature difference lies within ${\pm}1.5^{\circ}C$ (${\pm}2.5^{\circ}C$) except for precipitation case.