• Corrosion Science and Technology
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• v.9 no.2
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• pp.81-86
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• 2010

The mechanisms of selective oxidation of intercritically annealed CMnAl TRIP steels in a Continuous Galvanizing Line (GCL) were studied by cross-sectional observation of the surface and sub-surface regions by means of High Resolution Transmission Electron Microscopy (HR-TEM). The selective oxidation and nitriding of an intercritically annealed CMnAl TRIP steel in a controlled dew point 10%$H_2+N_2$ atmosphere resulted in the formation of c-xMnO.$MnO_2$ (1${\leq}$x<3) and c-xMnO.$Al_2O_3$ ($x{\geq}1$) particles on the steel surface. Single crystal c-xMnO.$SiO_2$ ($2{\leq}x{\leq}4$) oxide particles were also observed on the surface. A thin film of crystalline c-xMnO.$SiO_2$ (2${\leq}$x<3) and c-xMnO.$Al_2O_3$ ($x{\geq}1$) was present between these particles. In the sub-surface region, internal oxidation, nitriding and intermetallic compound formation were observed. In the first region, large crystalline c-xMnO.$SiO_2$ ($1{\geq}x{\geq}2$) and c-xMnO.$Al_2O_3$ ($x{\geq}1$) oxides particles were present. In the second region, c-AlN particles were observed, and in a third region, small $MnAl_x$ (x>1) intermetallic compound particles were observed.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.715-722
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• 1995

Vinylbenzyl triphenyl phosphonium chloride (VTPC) was prepared for the humid membrane. The humidity sensitive memo)lane was composed of copolymers, which have differnet content of VTPC and styrene (VTPC : ST=1 : 0.7 : 3, 5 : 5, 3 : 7). The changes in electrical properties of copolymers with relative humidity were measured. It was found that the impedance decreased with an increase of the content of VTPC in the humid membrane, and the Impedance also decreased with an increase of thickness of humid membrane. The copolymer derived from same equip of VTPC and ST showed 12M$\Omega$-100M$\Omega$ at 70%RH-90%RH, which was required for the current humidity sensor operating at high humidity or dew point. The temperature dependence coefficient at a temperature range 15$^{\circ}C$∼35$^{\circ}C$ was found to be -0.5%RH/$^{\circ}C$ and the hysterisis fabled within the range ${\pm}$2%RH. The response time was found to be 40seconds for varing relative humidity from 75% RH to 95%RH and vice versa.

• Journal of the Korean earth science society
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• v.39 no.5
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• pp.403-418
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• 2018

This study conducted synoptic and mesoscale analyses to understand the cause of Japan Tsukuba tornado development, which occurred at 0340 UTC 6 May 2012. Prior to the tornado occurrence, there was a circular jet stream over Japan, and the surface was moist due to overnight precipitation. The circular jet stream brought cold and dry air to the upper-level atmosphere which let strong solar radiation heat the ground with clearing of sky cover. A tornadic supercell developed in the area of potentially unstable atmosphere. Sounding data at Tateno showed a capping inversion at 900 hPa at 0000 UTC 6 May. Strong insolation in early morning hours and removal of the inversion instigated vigorous updraft with rotation due to vertical shear in the upper-level atmosphere. This caused multiple tornadoes to occur from 0220 to 0340 UTC 6 May 2012. When comparing Tateno's climatological temperature and dew-point temperature profile on the day of event, the mid-level atmosphere was moister than typical sounding in the region. This study showed that tornado development in Tsukuba was caused by a combination of (a) topography and potential vorticity anomaly, which increased vorticity over the Kanto Plain; (b) vertical shear, which produced horizontal vortex line; and c) thermal instability, which triggered supercell and tilted the vortex line in the vertical.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.3
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• pp.103-119
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• 2016

This study aims to assess habitat feature on the large-scale spawning ground of the Boreal Digging Frog Kaloula borealis in Daemyung retarding basin of Daegu, and to analyze the relationships between species abundance and meteorological factors for each habitat. Fifty-seven(57) pitfalls were installed to collect species abundance of 4 survey regions, and high-resolution satellite image, soil sampling equipment, digital topographic map, and GPS were used to develop habitat features such as terrain, soil, vegetation, human disturbance. The analysis shows that the frog is most abundant in sloped region with densely herbaceous cover in southern part of the retarding basin. In the breeding season, lowland regions, where Phragmites communis and P. japonica dominant wetlands and temporary ponds distributed, are heavily concentrated by the species for spawning and foraging. Located in between legally protected Dalsung wetands and lowland regions of the retarding basin, riverine natural levee is ecologically important area as core habitat for Kaloula borealis, and high number of individuals were detected both breeding and non-breeding seasons. Temperate- and pressure-related meteorological elements are selected as statistically significant variables in species abundance of non-breeding season in lowland and highland regions. However, in sloped regions, only a few variables are statistically significant during non-breeding season. Moreover, breeding activities in sloped regions are statistically significant with minimum temperature, grass minimum temperature, dew point temperature, and vapor pressure. Significant meteorological factors with habitat features are effectively applied to establish species conservation strategy of the retarding basin and to construct for avoiding massive road-kills on neighboring roads of the study sites, particularly post-breeding movements from spawning to burrowing areas.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.750-750
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• 2002

The Airship PKNU is a roughly 12 m (32 ft) long blimp, filled with helium, whose two-gasoline power(3hp per engine) are independently radio controlled. The motors and propellers can be tilted and are attached to the gondola through an axle and supporting braces. Four stabilizing fins are mounted at the tail of the airship. To fill in the helium, a valve is placed at the bottom of the hull. The inaugural flight was on jul. 31.2002 at the Pusan, S.korea Most environment monitoring system\ problem use satellite image. But, Low resolution satellite image (multi-spectral) : 1km ∼ 250 m ground resolutions is lows. So, detail information acquisition is hard at the complex terrain. High resolution satellite image (black and white) 30m : The ground resolution is high. But it is high price, visit cycle and delivery time is long So. We want make high accuracy airship photogrammetry system. This airship can catch picture Multi. spectral Aerial photographing (visible, Near infrared and thermal infrared), and High resolution (over 6million pixel). It can take atmosphere datum (Temperature (wet bulb, dew point, general), Pressure (static, dynamic), Humidity, wind speed). this airship is very Quickness that aircraft install time is lower than 30 minutes, it is compact and that conveyance is easy. High-capacity save image (628 cut per 1time (over 6million and 4band(R,G,B,NIR)) and this airship can save datum this High accuracy navigatin (position and rotate angle) by DGPS tech. and Gyro system. this airship will do monitor about red-tide, sea surface temperate, and CH-A, SS and etc.

• Journal of the Korean Wood Science and Technology
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• v.47 no.4
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• pp.533-542
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• 2019

As energy costs increase, more people has become interested on energy efficiency and savings in residential buildings. The two main subjects related to energy in residential buildings are insulation and condensation. There are two approaches to prevent condensation; increasing air tightness and maintaining the temperature inside of the wall structure over the dew point, which is in turn related to insulation. Even though the Korean government has highlighted the importance of energy efficiency for residential housings, and in spite of the customers' demands, the timber construction industry is still using conventional light-frame construction without even trying to improve energy efficiency. In this study, various types and combinations of wall structures were tested under cold outdoor and warm indoor temperatures to analyse the temperature gradients and to determine the possible sites of condensation in the wall structures. In addition to the experimental tests, three theoretical models were developed and their estimations of temperature change through the wall structure were compared with the actual measurements to evaluate accuracy of the models. The results of the three models agree relatively well with the experimental values, indicating that they can be used to estimate temperature changes in wall structures. The theoretical analysis of different insulation layers' combinations show that condensation may occur within the mid-layer in the conventional light-frame wall structures for any combination of inner-, mid-, and outer-layers of insulation. Therefore, it can be concluded that the addition of an inner and outer insulation layer or increasing the thickness of insulation may not be adequate to prevent condensation in the wall structure without preventing penetration of warm moist air into the wall structure.

• Korean Journal of Metals and Materials
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• v.46 no.5
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• pp.289-295
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• 2008

The effect of the alloy elements(Si/Mn) ratio on the coating quality including wettabilty with molten zinc, galvannealing kinetics and crater has been investigated in interstitial-free high strength steel(IFHSS) containing Si and Mn. When the Si/Mn ratio was below 0.75, IF-HSS exhibited a good wettability leading to a good galvannealed coating quality after annealing at $800^{\circ}C$ for 40s in $15%H_2-N_2$ mixed gas with dew point $-60^{\circ}C$. In contrast, the wettability and galvannealed coating quality were deteriorated in the Si/ Mn ratio above 0.75. It is shown that they have relevance to oxides forms by selective oxidation on the steel surface. The oxide particles dispersed on the steel surface with a surface coverage of below 40% resulted in good wettability and galvannealed coating quality. The oxide particle is mainly consisted of $Mn_2SiO_4$ with low contact angle in molten zinc. On the other hand, the continuous oxide layer on the steel surface, such as network- and film-type,caused to poor wettability and galvannealed coating quality. The coverage of oxide layer was above 80%, and its chemical species was $SiO_2$ with high contact angle in molten zinc. Consequently, the Si/Mn alloy ratio played an importance role in galvannealed coating quality of IF-HSS.

• Korean Journal of Metals and Materials
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• v.49 no.4
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• pp.281-290
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• 2011

In order to gain better understanding of the selective surface oxidation and its influence on the galvanizability of a transformation-induced plasticity (TRIP) assisted steel containing 1.5 wt.% Si and 1.6 wt.% Mn, a model experiment has been carried out by depositing Si and Mn (each with a nominal thickness of 10 nm) in either monolayers or bilayers on a low-alloy interstitial-free (IF) steel sheet. After intercritical annealing at $800^{\circ}C$ in a $N_2$ ambient with a dew point of $-40^{\circ}C$, the surface scale formed on 590 MPa TRIP steel exhibited a microstructure similar to that of the scale formed on the Mn/Si bilayer-coated IF steel, consisting of $Mn_{2}SiO_{4}$ particles embedded in an amorphous $SiO_{2}$ film. The present study results indicated that, during the intercritical annealing process of 590 MPa TRIP steel, surface segregation of Si occurs first to form an amorphous $SiO_{2}$ film, which in turn accelerates the out-diffusion of Mn to form more stable Mn-Si oxide particles on the steel surface. During hot-dip galvanizing, particulate $Fe_{3}O_{4}$, MnO, and Si-Mn oxides were reduced more readily by Al in a Zn bath than the amorphous $SiO_{2}$ film. Therefore, in order to improve the galvanizability of 590 TRIP steel, it is most desirable to minimize the surface segregation of Si during the intercritical annealing process.

• Journal of the Korean GEO-environmental Society
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• v.23 no.4
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• pp.11-20
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• 2022

In order to acquire hydraulic characteristics for unsaturated layers, water retention tests were performed and compared by using the evaporation method, volumetric pressure plate extractor (VPPE) and chilled-mirror dew point method. The evaporation and chilled-mirror method are currently developed experimental technology and measure the water retention curve of unsaturated soils quickly and accurately. In the evaporation and VPPE method, the water retention has been measured and compared until 100kPa matric suction and consequently the result of the evaporation method could be verified. In the chilled-mirror method, the water retention has been measured until high level of matric suction and the overall shape of water retention curves could be obtained. As a result of water retention tests, the representative water retention curves were obtained and the applicability of each test method was discussed. Using both the evaporation and chilled-mirror methods, the soil water retention curve can be acquired reasonably for the whole range of matric suction.

• Journal of Environmental Impact Assessment
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• v.33 no.2
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• pp.74-83
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• 2024

This study aims to estimate roadkill occurrences and investigate influential factors in Chungcheongnam-do, contributing to the establishment of roadkill prevention measures. By comprehensively considering weather, road, and environmental information, machine learning was utilized to estimate roadkill incidents and analyze the importance of each variable, deriving primary influencing factors. The Gradient Boosting Machine (GBM) exhibited the best performance, achieving an accuracy of 92.0%, a recall of 84.6%, an F1-score of 89.2%, and an AUC of 0.907. The key factors affecting roadkill included average local atmospheric pressure (hPa), average ground temperature (℃), month, average dew point temperature (℃), presence of median barriers, and average wind speed (m/s). These findings are anticipated to contribute to roadkill prevention strategies and enhance traffic safety, playing a crucial role in maintaining a balance between ecosystems and road development.