• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1185-1193
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• 2023

The increasing interest in soil moisture data from satellite imagery for applications in hydrology, meteorology, and agriculture has led to the development of methods to produce variable-resolution soil moisture maps. Research on accurate soil moisture estimation using satellite imagery is essential for remote sensing applications. The purpose of this study is to generate a soil moisture estimation map for a test area using KOMPSAT-3/3A and KOMPSAT-5 SAR imagery and to quantitatively compare the results with soil moisture data from the Soil Moisture Active Passive (SMAP) mission provided by NASA, with a focus on accuracy validation. In addition, the Korean Environmental Geographic Information Service (EGIS) land cover map was used to determine soil moisture, especially in agricultural and forested regions. The selected test area for this study is the western part of Jeju, South Korea, where input data were available for the soil moisture estimation algorithm based on the Water Cloud Model (WCM). Synthetic Aperture Radar (SAR) imagery from KOMPSAT-5 HV and Sentinel-1 VV were used for soil moisture estimation, while vegetation indices were calculated from the surface reflectance of KOMPSAT-3 imagery. Comparison of the derived soil moisture results with SMAP (L-3) and SMAP (L-4) data by differencing showed a mean difference of 4.13±3.60 p% and 14.24±2.10 p%, respectively, indicating a level of agreement. This research suggests the potential for producing highly accurate and precise soil moisture maps using future South Korean satellite imagery and publicly available data sources, as demonstrated in this study.

• Journal of the Korean association of regional geographers
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• v.13 no.2
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• pp.201-219
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• 2007

To understand the structure and dynamics of different forms of learning, whether incidental or conscious, we have to study them as parts or aspects of concrete historical activities with specifiable contexts. This realization is more embodied in apprenticeship learning situations of the student teachers. In this perspective, this paper aims to understand the student teachers' experience on geography teaching as a participant observer in the secondary schools. The 9 student teachers during the teaching internship have written their 38 journals, which was quality analysed to find out key concepts for the purpose of this research. Major conclusions are suggested below as follows. First, the most student teachers were experienced in geography teaching in the secondary schools through the 2-weeks practice teaching. Second, in the positive perspective, student teachers observed on that teachers would teaching well interact with student and experienced teachers would settle down to student's studies. Third, in the negative perspective, student teachers observed on that teachers lecture with only text, and cooperative learning by student presentation in the geography class. Finally, In third person perspective, there is no students' or teachers' productive questions in the whole-class conversation. In addition to that the most mentor teachers lecture do all of the talking in class. In effect these student teachers' experiences, especially 'reality of the geography teaching' and 'practical knowledge of the novice mentor teachers or experienced mentor teachers', either reinforce or modify understanding about the geography teaching practices.

• Journal of the Korean Association of Geographic Information Studies
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• v.2 no.2
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• pp.45-58
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• 1999

Digital map is utilized for an effective display of the distributions of the hydrogeological variables such as water table height(hydraulic head) and log-transmissivity(lnT) in north Pohang, KyungBug. Specifically the geostatistical method kriging is used to construct the distributions in an unconfined aquifer from a finite set of measured data. The experimental variograms for both the head and lnT suggest spherical models with nugget of 0 and range of 6km. The kriged results by using these variograms show that the head decreases primarily from the west to the east with a large peak in the north-western part and lnT is at the maximum level in the central part with outwardly decreasing trend. The constructed delineation is also used to calculate the flow field in the region. Finite differences with second order consistency are used to calculate the fluxes in the east(x) and north(y) across a vertical cross-section of unit width and height equal to the thickness of the wet zone in the aquifer. It is demonstrated that the flow is dominantly in the east with diverging trend on the eastern hillside of the water table peak. A few convergent spots also appear.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.1
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• pp.29-34
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• 2004

We present the first demonstration of waveguide-type depleted optical thyristor laser diode with InGaAs/InGaAsP multiple quantum well structure. The measured switching voltage and current are 4.63 V and 10uA respectively. The holding voltage and current are respectively 0.59 V, 20uA. The lasing threshold current at the temperature of $25^{\circ}C$ and $10^{\circ}C$ are 111 mAA and 72.5 mA, respectively. The lasing wavelength is centered at 1.561um at a bias current equal to 1.41 times threshold.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.1
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• pp.27-33
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• 2009

Shock tube flow measurement has been often hampered a finite opening time of diaphragm, but there is no systematic work to investigate its effect on the shock tube flow. In the present study, both the experimental and computational works have been performed on the shock tube flows at low pressure ratios. The computational analysis has been performed using the two-dimensional, unsteady, compressible Navier-Stokes equations, based upon a TVD MUSCL finite difference scheme. It is known that the present computational results reproduce the experimental data with good accuracy and simulate successfully the process of diaphragm opening as a function of time. The concept of an imaginary center is introduced to quantify the non-centered expansion wave due to a finite opening time of diaphragm. The results obtained show that the diaphragm opening time is reduced as the initial pressure ratio of shock tube increases, leading to the effect of a finite opening time of diaphragm to be more remarkable at low pressure ratios.

• Journal of the Mineralogical Society of Korea
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• v.28 no.2
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• pp.165-171
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• 2015

Dust samples collected from air in metropolitan areas of Busan and Ulsan were analyzed by phase contrast microscopy, phase contrast dispersion microscopy and SEM. Asbestos concentration in dust samples was lower than detection limit. Many fibrous materials were observed in dust samples, but most of them were organic fibers. Inorganic fibers such as rock fiber, ceramic fiber and gypsum were contained in the samples and non-fibrous minerals such as quartz, calcite and feldspar were also occasionally observed. Domestic law requires that asbestos in air dust is mainly analyzed by phase contrast microscopy. From this study, however, precise analysis of asbestos was almost impossible by this method only. As indicated in JIS method of Japan, therefore, count and identification of asbestos were more efficient by dispersion staining method after removing organic materials in samples by low temperature incinerator.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.78-79
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• 2012

To improve moving vehicles' accuracy, one-way Network RTK which guarantees high accuracy and integrity regardless the distance from rovers to Reference Station(RS) is being considered. Correction of one-way Network RTK can be generated only after constructing RS network surrounding the rover, therefore a correction discontinuity is inevitably occurred when the RS set has been changed. The discontinuity is not eliminated by the DD(Double Difference) method, and our simulation shows that it causes 13cm(horizontal) and 48cm(vertical) position error. We suggest three solutions to reduce this discontinuity, which are identification of master RS with neighbor networks, duplication of communication module to receive corrections from other network, and ambiguity levelling between neighbor networks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.3
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• pp.295-302
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• 2020

Disaster Preventing Zone (DPZ) is one of the zoning for land use regulation. Though the purpose of the designating of DPZs is to improve the area be safer, people has the negative recognition on DPZs. They think DPZs are regulation to restrict the actions and finally causes decrease on the land price. In this context, the aim of this study is to investigate the correlation between the designation of the DPZs and the land price of the DPZs in Seoul Metropolitan City. We applied the Difference in different (DID) which is one of the research methods to verify the cause and effect of specific policy. As a result, it was found statistically significant that land price of parcels designated as DPZs was 420,000 won higher than those not designated. The same results were obtained when the land characteristics were added, and the robustness of the model was indirectly confirmed. Based on the results, the designating of the DPZs was contrary to the expectation. Although it is necessary to analyze the result of the study more microscopically, It will be necessary to change the perception that it will decline.

• Journal of Energy Engineering
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• v.2 no.3
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• pp.268-275
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• 1993

A series of parametric investigations are performed in order to resolve the flow characteristic of a Quebec city stoker incinerator. The parameters considered in this study are five internal configurations of the Quebec city stoker itself and its modified ones, primary air velocity, the injection velocity and angle of the secondary air, and the reduction of the stoker exit area. A control-volume based finite-difference method by Patankar together with the power-law scheme is employed for discretization. The resolution of the pressure-velocity coupling is made by the use of SIMPLEC algorithm. The standard, two equation, k-$\varepsilon$ model is incorporated for the closure of turbulence. The size of recirculation region, turbulent viscosity, the mass fraction of the secondary air and pressure drop are calculated in order to analyze the characteristics of flow field. The results are physically acceptable and discussed in detail. The flow field of the Quebec city stoker shows the strong recirculation zone together with the high turbulence intensity over the upper part of the incinerator.

• Journal of Labour Economics
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• v.25 no.1
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• pp.131-160
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• 2002

This article tried to find out the individual wage effect of training. This Article used 1998, 1999 KLIPS(Korea Labor and Income Panel Study) panel data. The size of the individual wage effect of training was twice of tenure's, and had significance. Training had a good effect on the job satisfaction and carrier development. To overcome self selection bias, this article regressed the first difference of wage equations, but we didn't get the significant results. Dividing sample into quitters and non-quitters in order to investigate the relation between training cost and benefit, we regressed separately the each first difference of wage equation. On quitters, the individual effect of training appeared significantly, but on non-quitters, it didn't. This results mean that employer does not raise wage rate according to upgraded skill originated in incumbent's training. And the results also mean that the upgraded skill of employee who quit pre-employer is recognized by new employer, and his wage rate rises in his new job.