• Corrosion Science and Technology
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• v.23 no.4
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• pp.324-333
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• 2024

Atmospheric corrosion poses a significant threat to durability of metallic materials and safety of structures, making precise prediction of corrosion rates crucial in industrial and engineering settings. Understanding the exact rate of corrosion is essential. However, accurate inclusion of various environmental factors that can influence atmospheric corrosion in the calculation of corrosion rate is a complex challenge. This study introduces a physics-based model that incorporates electrochemical methods and considers active surface area affected by surface contaminants to estimate atmospheric corrosion rate of carbon steel. The model can evaluate corrosion levels using key factors such as chloride deposition rate, relative humidity, and the presence of surface particles. By integrating these considerations, this model moves beyond empirical estimations, providing a more stable prediction of corrosion rate that is less susceptible to environmental variations. This model provides a robust tool for defense applications, offering precise insights into the dynamics of atmospheric corrosion that could enhance the maintenance and safety of weapon systems.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.1
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• pp.18-27
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• 2020

Objectives: For testing asbestos stabilizer products which are used for the maintenance and management of asbestos-containing materials, durability assessment should accompany the evaluation of basic properties and performance. Therefore, in this study we designed a testing method and constructed a database of durability performance, thereby providing basic data for reliability studies of asbestos stabilizer. Methods: Since the ceiling materials targeted in this study are interior materials, test conditions of 95% relative humidity and 60℃ temperature were designed in consideration of the effect of high relative humidity in summer and seasonal indoor temperatures. Plate-shaped specimens treated with asbestos stabilizers were maintained in a thermo-hygrostat for 5, 10, and 20 days, and then the asbestos scattering prevention rate was measured by air erosion testing. Results: The scattering concentration tended to increase with time under the single humidity condition, and exceeded the indoor air quality standard of 0.01 f/cc, during the 20 days of maintenance. On the other hand, there was little change according to the temperature condition. In the case of a complex condition with temperature and humidity, the results were similar to the humidity test, but the scattering concentration increased more sharply at 20 days. Conclusions: The main deterioration factor that affects the durability of asbestos stabilizer is humidity, and the deterioration is caused by a mechanism in which the stabilizer coated on the surface is re-dissolved by moisture and evaporates or the coating layer is peeled off, which is accelerated by high temperatures.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.13-19
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• 2009

A 440MHz wireless and passive surface acoustic wave (SAW) based chemical sensor was developed on a $41^{\circ}YX\;LiNbO_3$ piezoelectric substrate for simultaneous measurement of $CO_2$ gas and relative humidity (RH) using a reflective delay line pattern as the sensor element. The reflective delay line is composed of an interdigital transducer (IDT) and several shorted grating reflectors. A Teflon AF 2400 and a hydrophilic $SiO_2$ layer were used as $CO_2$ and water vapor sensitive films. The coupling of mode (COM) modeling was conducted to determine optimal device parameters prior to fabrication. According to simulation results, the device was fabricated and then wirelessly measured using the network analyzer. The measured reflective coefficient $S_{11}$ in the time domain showed high signal/noise (S/N) ratio, small signal attenuation, and few spurious peaks. In the $CO_2$ and humidity testing, high sensitivity ($2^{\circ}/ppm$ for $CO_2$ detection and $7.45^{\circ}/%$RH for humidity sensing), good linearity and repeatability were observed in the $CO_2$ concentration ranges of $75{\sim}375ppm$ and humidity levels of $20{\sim}80%$RH. Temperature and humidity compensations were also investigated during the sensitivity evaluation process.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.377-385
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• 2022

Surface morphology and adsorption characteristics of charcoals prepared from Korean traditional kiln were analyzed, and their moisture adsorption capacities were examined with respect to humidity and temperature change. Moisture adsorption capacities of red-clay powder, activated carbon fiber fabric (ACF fabric) and activated carbon fiber paper(ACF paper) were also examined to compare with those of charcoals. Moisture adsorption capacity of charcoal was low less than 45% humidity due to its hydrophobic property, but it slowly and linearly increased as increasing the humidity. Moisture adsorption capacity of red-clay powder was similar to charcoal at low level humidity, it increased exponentially as increasing the humidity showing Type V adsorption isotherm. Therefore, the weather forecast annal prepared by employee of weather centre in Joseon Dynasty is experimentally approved. ACF fabric and ACF paper show excellent moisture adsorption capacities, which can be used to humidity measuring sensor. Adsorption isotherm of charcoal slice was peculear showing the mixed Type I and Type IV due to low-pressure hysteresis that was occurred from embedment of nitrogen in crevice of charcoal. The specific surface area of charcoal increased by grinding charcoal slice to powder, resulted in increasing the desorption amount of adsorbent at low relative pressure.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.49-58
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• 1998

An experimental study was performed to discover the effect of adsorbed moisture on the rolling resistance behavior of pure silver coated 52100 bearing steel. Plasma surface modifications were performed on the silver coated specimen to change the wetting characteristics. Experiments using a thrust ball beating-typed roiling test-rig were performed under vacuum, dry air and various tmmidity conditions. Results showed that the changes in the wetting characteristics influenced remarkably on the silver particle agglomeration and resulted in the different behavior of rolling resistance with humidity.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.71-71
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• 2013

AZ31 마그네슘 합금 판재는 경량화가 요구되는 분야에 사용되는 것을 목표로 설계되어 상업화가 추진되고 있으며, 이의 적용을 위해서는 마그네슘 판재의 내 부식성을 제어하는 표면처리 공정이 필수적이다. 표면처리에서는 강판 및 알루미늄판재의 표면처리 공정에 이용되는 화성처리-전착도장 공정에 따라야 하겠지만, 산 용액에 매우 취약한 마그네슘 소재의 특성상 같은 처리 조건을 적용하기 어렵다. 산 종류에 따른 AZ31 마그네슘합금판재 표면처리효과를 알아보기 위해 여러 종류의 산 처리 후 내 부식성을 알아보고 HH(Heat and Humidity; 가압, 가습 조건에서 열처리) 공정을 접목시킨 표면처리 결과에 대하여도 관찰하였다. 그 중 불산을 이용한 표면처리는 농도별로 진행하여 산세의 농도가 표면에 주는 영향에 대하여도 알아보았다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.7
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• pp.607-616
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• 2002

This study has been conducted to evaluate the applicability of the control method in the dehumidification-integrated radiant floor cooling system in terms of stability of the room air temperature and the control variables through experiments. To do this, the relationship between the control variables in preventing floor surface condensation is first analyzed and the control method is predetermined through simulations. The results are as follows. First, it is necessary to determine the operation status of the dehumidification system according to the relationship between floor surface temperature and dew point temperature in the conditioned space. Second, outdoor reset with indoor temperature feedback control is better than on/off bang-bang control with respect to temperature stability in controlling the room air temperature and the possibility of energy savings. Finally, the humidity sensor can be located with the current thermostat in that there are small differences in absolute humidity in vertical distribution.

• Journal of the Korean housing association
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• v.15 no.2
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• pp.19-25
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• 2004

The aim of the research was to evaluate the characteristics of indoor thermal environment and thermal sensation in the traditional Ondol room. Indoor thermal factors including air temperature, operative temperature, floor surface temperature, relative humidity, PMV, OT were measured, and survey was carried out to understand subjective responses of resident's related to indoor thermal environment in Ondol room. The analysed houses are: the Chung hyo dang(the head house of Ryu family in Andong) and the Pyeung won jung(the traditional house in Yesan). The purpose of the survey was to know the relationship between resident's sensation and thermal environmental indicators such as air temperature, relative humidity, floor surface temperature, OT. The experimental results have pointed out how Ondol room may lead to comfortable and uniform indoor thermal environments.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.380-384
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• 2010

본 연구는 가을철 산불조심기간 중 영동지방 활엽수림에 대하여 임분별로 강우 후 익일부터 6일간 임내의 지표연료를 직경별 0.6cm 이하, 0.6~3.0cm, 3.0~6.0cm, 6.0cm 이상에 대한 연료습도 변화를 실측하는 한편, 기상인자를 고려한 통계분석을 실시하여 경과일수별 연료습도추정 예측식을 개발하였다. 결정계수인 $R^2$ 값은 0.75~0.90의 적합성을 나타내었으며, 향후 강우 후 기상자료를 이용하여 임내 연료습도를 예측하여 산불위험예보로 활용하는데 매우 유용한 자료로 이용할 수 있을 것으로 판단된다.

• Atmosphere
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• v.27 no.2
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• pp.235-249
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• 2017

This paper describes methodology verifying near-surface predictability of numerical weather prediction models against the surface synoptic weather station network (SYNOP) observation. As verification variables, temperature, wind, humidity-related variables, total cloud cover, and surface pressure are included in this tool. Quality controlled SYNOP observation through the pre-processing for data assimilation is used. To consider the difference of topographic height between observation and model grid points, vertical inter/extrapolation is applied for temperature, humidity, and surface pressure verification. This verification algorithm is applied for verifying medium-range forecasts by a global forecasting model developed by Korea Institute of Atmospheric Prediction Systems to measure the near-surface predictability of the model and to evaluate the capability of the developed verification tool. It is found that the verification of near-surface prediction against SYNOP observation shows consistency with verification of upper atmosphere against global radiosonde observation, suggesting reliability of those data and demonstrating importance of verification against in-situ measurement as well. Although verifying modeled total cloud cover with observation might have limitation due to the different definition between the model and observation, it is also capable to diagnose the relative bias of model predictability such as a regional reliability and diurnal evolution of the bias.