• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.1
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• pp.51-62
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• 2020

This study was conducted to develop a method for depth assessment of embedded sources using gamma-spectrum ratio and for the evaluation of field applicability. To this end, Peak to Compton and Peak to valley ratio changes were evaluated according to ¹³⁷Cs, ⁶⁰Co, ¹⁵²Eu point source depth using HPGe detector and MCNP simulation. The effects of measurement distance of PTV and PTC methods were evaluated. Using the results, the source depth assessment equation using the PTC and PTV methods was derived based on the detection distance of 50 cm. In addition, the sensitivity of detection distance changes was assessed when using PTV and PTC methods, and error increased by 3 to 4 cm when detection distance decreased by 20 cm based on 50 cm. However, it was confirmed that if the detection distance was increased to 100 cm, the effects of detection distance were small. And PTV and PTC methods were compared with the two distance measurement method which evaluates the depth of source by the change of net peak counting rate according to the detection distance. As a result of source depth assessment, the PTV and PTC showed a maximum error of 1.87 cm and the two distance measurement method showed maximum error of 2.69 cm. The results of the experiment confirmed that the accuracy of the PTV and PTC methods was higher than two distance measurement. In addition, Sensitivity evaluation by horizontal position error of source has maximum error of less than 25.59 cm for the two distance measurement method. On the other hand, PTV and PTC method showed high accuracy with maximum error of less than 8.04 cm. In addition, the PTC method has lowest standard deviation for the same time measurement, which is expected to enable rapid measurement.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1456-1458
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• 1996

In resonant tunneling diodes with the quantum well structure showing the negative differential resistance (NDR), it is essential to increase both the peak-to-valley current ratio (PVCR) and the peak current density ($J_p$) for the accurate switching operation and the high output of the device. In this work, a resonant interband tunneling diode (RITD) with single quantum well structure, which is composed of $In_{0.53}Ga_{0.47}As/ln_{0.52}Al_{0.48}As$ heterojunction on the InP substrate, is suggested to improve the PVCR and $J_p$ through the narrowed tunnel barriers. As the result, the measured I-V curves showed the PVCR over 60.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.4
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• pp.27-32
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• 1997

In resonant tunneling diodes with the quantum well structure showing the negative differential resistance (NDR), it is essential to increase both the peak-to-valley current ratio (PVCR) and the peak current desnity ( $J_{p}$) for the accurate digital switching operation and the high output of the device. In this work, a resonant interband tunneling diode (RITD) with single quantum well structure, which is composed of I $n_{0.47}$As/I $n_{0.52}$A $l_{0.48}$As heterojunction on the InP substrate, is fabricated ot improve PVCR and JP, and then the dependence of I-V charcteristics on the width of the quantum well was investigated.d.ted.d.

• Geomechanics and Engineering
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• v.38 no.1
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• pp.15-28
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• 2024

The rapid development of the economy has compelled the widen of highways, and the main challenge of this undertaking lies in the uneven settlement of road embankments. Through field and numerical experiments, this study explores the deformation mechanism of shallow buried pipelines due to road widening. The utilization of Plaxis3D software, which is adapt at simulating complex engineering geological conditions, enables the simulation of the settlement of both the central and right-side road embankments. Comparing with other numerical software such as ABAQUS and COMSOL, Plaxis provided more constitutive models including HS, HSS and Hoek-Brown model. The work concludes that the uneven settlement of road cross-sections is positively correlated with the horizontal distance from the pipeline, with a maximum settlement of 73 mm observed after construction. Furthermore, based on the Winkler's assumption, theoretical settlement and stress calculation methods are established. Results indicate that the maximum difference between the calculated values of this formula and simulated values is 1.9% and 7%, respectively. Additionally, the study investigates the stress and settlement of the pipeline's top under different angles to understand its behavior under various conditions. It finds that with traffic loads applied to the new embankment, a lever effect occurs on the lower pipeline, with the fulcrum located within the central isolation zone, leading to a transition in curve type from "single peak and single valley" to "double peak and single valley." Moreover, the settlement of pipelines on both sides of the central isolation zone and the normal stress of the pipeline's top section are symmetrical.

• Korean Journal of Environment and Ecology
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• v.2 no.1
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• pp.66-85
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• 1988

The user's composition in Chiak Mountain National Park showed that male, twenties(20-29 ages) and high school or more graduated students were 64.7％, 72.5％ and 95％ respectively by sex, age and education. In visiting purpose, the natural parks characteristics shelved to be a important merit of Chiak Mountain, but the picnic patterns as of neighbourhood park and the recreation patterns as of recreation ground were appeared to be important simultaneously. In preferable place of visitors, the water in valley, natural landscape and climbing were prefered. In the district of Temple Kuryong valley, the peak season of visiting was Fall, and the peak hours during a day was 10 hours A.M and 5 hours P.M. Therfora the management plan in consideration of hiking pattern of nature park, picnic pattern as of neighbourhood park and recreation pattern as of recreation ground shall be necessary to solve the conflicts among functions in Chiak Mountain National Park.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.6
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• pp.587-595
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• 2011

In this paper, we focus on the issue of automatic selection for multi-level threshold, and we greatly improve the efficiency of Otsu's method for image segmentation based on genetic algorithm. We have investigated and evaluated the performance of the Otsu and Valley-emphasis threshold methods. Based on this observation we propose a method for automatic threshold method that segments an image into more than two regions with high performance and processing in real-time. Our paper introduced new peak detection, combines with evolution algorithm using MAGA (Modified Adaptive Genetic Algorithm) and HCA (Hill Climbing Algorithm), to find the best threshold automatically, accurately, and quickly. The experimental results show that the proposed evolutionary algorithm achieves a satisfactory segmentation effect and that the processing time can be greatly reduced when the number of thresholds increases.

• Journal of the Korean Geographical Society
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• v.39 no.6 s.105
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• pp.833-844
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• 2004

In Chugaryeong rift valley, lava plateau formation by the fissure eruption had vanished original landforms and effected on drainage derangement and revision. 4 rivers including Namdae-cheon, Bukhan-gang, Imjin-gang and Hantan-gang watersheds have shared Cheolwon-Pyeonggang lava plateau, that is, ownerless watershed. Main agency of the dividing process are central-eruption volcanic peaks such as Orisan(453m) and 680 Peak. Especially, Orisan has played the role of divide point for 4 watersheds. In the lower-relief plateau zone, complex drainage system have caused continually river capture between neighboring watersheds. In more elevated range slope, river capture have proceeded to headward erosion. Hydrogeomorphologically, lava-filled valley has initiated decrease of the original size of flood plain, maybe, causing higher capability of inundation by heavy rains, and then more active dissection of lava plateau layer.

• Journal of Radiation Protection and Research
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• v.43 no.2
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• pp.75-84
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• 2018

Background: Gamma-ray spectrometry helps in radiation shielding problems and different applications of radioisotopes. Experimental arrangements including broad beam geometries are widely used. The aim is to investigate and evaluate the ${\gamma}-ray$ spectra via attenuation by environmental materials. Materials and Methods: The photo peak to nominated parts in the ${\gamma}-ray$ spectra and the attenuation coefficients ${\mu}_b/{\rho}$ from broad beam geometries are measured for the materials water, soil, sand and cement at the energies 0.662, 1.25, and 1.332 MeV with a $3{^{\prime}^{\prime}}{\times}3{^{\prime}^{\prime}}$ NaI(Tl) detector. Results and Discussion: The ${\gamma}-ray$ spectra vary according to changes in the effective atomic number $Z_{eff}$ of the attenuator, the photon energy and the solid angle. The peak to total ratios are the most sensitive parts to variations in the experimental conditions and overturn in the region 0.663 MeV to 1.332 MeV. This is indicated as inversion trend. The results are discussed in view of $Z_{eff}$ and the experimental conditions. The intensity build-up is larger at the lower energy and larger scattering angles in agreement with Klein-Nishina formula and other results. The build-up factor B is$${\sim_=}$$1 at high ${\gamma}-energies$ and small scattering angles. Conclusion: The sensitivity to material characteristics decrease gradually from peak: to total, to Compton valley, to Compton plateau ratios. Rigorous collimation is necessary at small energies. Cement, of the largest $Z_{eff}$, is characterized by the maximum broad beam mass attenuation coefficients ${\mu}_b/{\rho}$. The obtained results provide information to decide for the suitable experimental set-up based on aim of the work.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.5
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• pp.64-72
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• 2007

This study investigated the types, forms, and origination of litter found along one hiking course in Moaksan Provincial Park, 'Jungin-ri Course'(entrance-ridge-valley-peak). In addition, a survey was conducted to understand hikers' litter control awareness in order to determine possible backcountry litter control measures. The following are the results of this study: 1. For the litter Sequency investigation, 199 recyclable pieces of litter were found on the mid-slope(61.6%), 89 by the entrance(27.6%), 19 in the valley(5.9%) and 16 on the peak(4.9%). A total of 323 pieces of litter were found. Paper materials were the most common, followed by plastic containers such as PET bottles and yogurt containers. Of particular interest, 288 papers and cans were found on the mid-slope(46.9%). By the entrance, more plastics and bottles were found. 2. There were 614 pieces of flammable litter collected and only 19 pieces of non-flammable. Most of the flammable litter, including snack pacts, plastic bags, processed lumber, cigarette butts, tissues, cigarette boxes, and fabric was found on the mid-slope. 3. Very little food waste was found throughout the whole site proving that the policy prohibiting hikers from cooking and eating at the designated sites has been effective. However, food waste is difficult to find because it naturally decays with time. 4. $X^2$-test was used to find different types of litter and their verified origination frequency. It was found that recyclable litter, and food waste took about 1%. In addition, recyclable litter, especially bottles, was found relatively frequently by the entrance. Flammable litter was found most often at the peak. 5. The questionnaire results showed that 48.2% of the respondents "shorten their hiking journey and purchase food outside the entrance" and 29.6% said that they "bring a packed meal from home". Only 8.2% said that they "cook something when an appropriate location is found". At the Jungin-ri course, a few hikers brought their own food to eat or cook, but most hikers purchased something to eat onsite. 6. The results of the question about having experience littering while hiking showed that 19.3% litter and 79.2% do not. Those that responded "yes" gave various reasons for littering. 63.6% claimed, "there are no designated trash containers". 15.9% said they litter subconsciously. Finally, 3.2% insist that they litter "because food naturally decomposes". 7. As a result of the overall satisfaction according to the Likert scale and the analysis with an average of 14 variables, it was found that the average "toxic litter control convenience" was 2.41 with very low satisfaction. Thus, the results indicate the importance of providing appropriate back country litter control facilities.

• Elastomers and Composites
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• v.49 no.2
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• pp.103-109
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• 2014

Blends of emulsion SBR (E-SBR) and solution SBR (S-SBR) were prepared, and their microstructures (styrene, 1,2-unit, cis-1,4-unit, and trans-1,4-unit contents) were analyzed by Fourier transform infrared spectroscopy (FTIR) with transmittance mode. Method to measure absorbance by valley-to-valley baseline (TV) is objectively reasonable, but has a demerit which peak intensity of the cis-1,4-unit cannot be correctly measured. In order to obtain information for the four microstructures including cis-1,4-unit, measurement methods without correction (TM) and correction to 99% transmittance (TB) were compared to the TV method. Results obtained by the TB method were closer to those obtained by the TV one than those obtained by the TM. The microstructures were determined from the absorbances obtained by the TM and TB methods according to the ISO/FDIS 21561:2005(E). Variations of the styrene, 1,2-unit, and trans-1,4-unit contents with the blend ratio of E-SBR/S-SBR showed relatively good linearities, and there was no big difference between results obtained by the TM and TB methods. Variations of the cis-1,4-unit content with the blend ratio absolutely did not show linearities irrespective of the TM and TB methods.